Theoptimized procedure has been successively applied to the determinationof ultratraces of GO in water samples.The extensive useof graphene materials in real-world applicationshas increased their potential release into the environment. To evaluatetheir possible health and ecological risks, there is a need for analyticalmethods that can quantify these materials at very low concentrationsin environmental media such as water. In this work, a simple, reproducible,and sensitive method to detect graphene oxide (GO) in water samplesusing the surface-enhanced Raman spectroscopy (SERS) technique ispresented. The Raman signal of graphene is enhanced when depositedon a substrate of gold nanoparticles (AuNPs), thus enabling its determinationat low concentrations with no need for any preconcentration step.The practical limit of quantification achieved with the proposed methodwas 0.1 ng mL Thisstudy describes how to detect very small amounts ofgraphene-based materials in aquatic environments in relation to materialsapplications and policy regulations. For example, they have been used in epoxyresins to improve their mechanical properties, in conductive inksfor flexible electronics, in anticorrosion coatings, as part of interconnectorsfor 5G data communication, sports products 9 or wearable health monitors.12Thediscovery of graphene and graphene-related materials (GRM)has been a great boost for materials science. Their extraordinarycharacteristics, such as excellent mechanical and optical properties,and thermal and electrical conductivities,13 but even today, one of the issues that remains to be resolvedis their detection and quantification in low concentrations in environmentalmedia while differentiating them from other carbonaceous materials.Throughout their life cycle, these graphene-based systems can endup in the environment, for example, in aqueous systems, and causehealth problems and even become harmful to ecosystems due to absorptionby organisms.15 Some health-related problemscould be pulmonary inflammation or thrombotoxicity in contact withhigh concentrations of carbon nanomaterials.16 As such, the detection of graphene materials in these media is crucialfor evaluating their potential ecotoxicological effects.18In parallel to the development of these applications, thetechniquesused for GRM characterization have also improved,19 GO has been widely used for the preparationof membranes, providing new opportunities for high-performance nanofiltrationapplications.20 This nanofiltration canbe used for decolorization22 water softening,25 natural organic matter removal,26 heavy-metalremoval,27 and organic solvent separation.29 Moreover, GO has shown bactericidal properties, and flakes of GOcan envelop and confine microorganisms by enclosing them in an insulatingcarbon blanket.30 Despite all of theseadvantages, GO could be released from the membranes and contaminatethe treated waters.Paradoxically, GRMs, and in particular graphene oxide (GO),canbe used in environmental protocols for water treatment.13 These approaches takeadvantage of the structural, thermal, and electrical properties ofGO and include X-ray photoelectron spectroscopy (XPS), UV–visspectroscopy, fluorescence spectroscopy, and Raman spectroscopy. Althoughthe XPS technique is widely used for characterizing and, at times,detecting GO in water samples, it is subject to interference fromthe abundant, naturally occurring carbon-containing substances inwaters, and therefore is not very useful for quantifying GO in water.With regard to the UV–vis spectroscopy, GO can be quantifiedusing the Lambert–Beer law;31 however,this technique cannot distinguish the absorbance of GO from that ofother substances, thus leading to false positives. Similarly, fluorescencespectroscopy is not used as widely as UV–vis spectroscopy toquantify GO in aqueous media due to the nonlinear relationship betweenfluorescence intensity and the concentration of GO in aqueous media,thus meaning that this technique is mainly used for semiquantitativeanalysis. Finally, isotope labeling is not suitable for practicalsamples.32For all of these reasons, and to establishthe safe use of graphenein everyday products, it is necessary to develop simple, rapid, andsensitive methods to analyze and detect GO in water samples at ultratracelevels. Analytical techniques for quantifying GO are normally basedon its unique physicochemical properties, which differentiate GO fromother compounds.D, ∼1350 cm–1) and graphitic  bands representative of the sp2-hybridized network ofcarbon disrupted by edges and defects along the basal plane. However,this technique is not sensitive enough to detect the amount of GOpresent in real samples. In this regard, Yang et al.33 developed a method for the fast identification and quantificationof GO in local water samples based on reduction with hydrazine tominimize the fluorescence signal and subsequent analysis using Ramanspectroscopy, obtaining a limit of quantification (LOQ) of 1000 ngmL–1. To improve the sensitivity, GO in water sampleshas been subjected to a preconcentration step on a cellulose membraneand finally determined by fluorescence quenching using graphene quantumdots,34 giving an LOQ of 117 ng mL–1. However, these methods are less sensitive and moretime-consuming owing to the need for reduction and preconcentrationsteps, respectively. These shortcomings can be circumvented by developingeffective and selective methods for minimizing the problems associatedwith sample treatment and sensitivity. Surface-enhanced Raman spectroscopy(SERS) is a good alternative for detecting GO with high selectivityand sensitivity. Indeed, given its potential for extremely high enhancementlevels, SERS transforms Raman spectroscopy from a structural analyticaltool to a structurally sensitive single-molecule probe.35 When GO is in contact with metallic nanoparticles,two effects may contribute to the enhancement of the Raman signal.First, the collective oscillation of electrons in metallic nanoparticles,like gold nanoparticles (AuNPs), leads to the so-called plasmon resonance,which can resonate with the energy of the excitation laser, thus resultingin high local optical fields (electromagnetic field enhancement).In addition, the electronic interaction between graphene and metalnanostructures can result in an increase in the Raman signal .38 AuNPs have advantages over other metal nanoparticles due to theireasy synthesis and excellent stability, providing a high surface/volumeratio with exceptional optoelectronic properties. These propertiescan also be controlled by varying their size, shape, and the surroundingchemical environment, being crucial to achieve better SERS substrates.41Raman spectroscopy offersbetter specificity than XPS, UV–visspectroscopy, and fluorimetry for identifying GO by detecting thesignature defect  is a helpful tool to estimatethe efficiencyof SERS substrate as an amplifier of the Raman signal of the analytes.34 The results are very promising as regards thedevelopment and commercialization of GO-based devices.Herein, we describe a new and simple method for detectingand quantifyingGO in aqueous samples using SERS. This method has good reproducibilityfor aqueous samples and high sensitivity, thereby improving the reportedlimit of detection (LOD) for GO by fluorescence sensors.2 wafers were purchased from Pure Wafer . Graphene oxide working solutions were preparedat room temperature by dispersion in deionized water.All reagents were of analyticalgrade or better. Graphene oxide  wassupplied by Abalonyx . Sodium citrate (≥99%),gold(III) chloride (≥99.99%), 2-propanol (≥99.8%), andhydrochloric acid (≥37%) were obtained from Sigma-Aldrich . Nitric acid (≥60%) was purchased from Panreac . Acetone (≥99.5%) was acquired from Labkem . Si/SiO–1. The resulting spectrum was obtained by averaging 3000 spectra inmapping mode. Scanning electron microscopy (SEM) images were recordedusing a ZEISS GeminiSEM 500 field emission instrument with an acceleration voltage of 0.02–30 kV and a probe currentof 3 pA to 20 nA. This instrument is equipped with several detectors:an in-lens secondary electron detector, an in-lens energy selectedbackscatter detector (EsB), an annular scanning transmission electronmicroscopy (STEM) detector (aSTEM 4), and an EBSD detector (electronbackscatter diffraction) to investigate crystalline orientation. Thesamples were prepared on a lacey carbon surface by deposition of adispersion of the nanomaterial. The ultraviolet–visible (UV–vis)spectrum of gold nanoparticles was collected using 1 cm quartz cuvettesand a Cary 5000 UV–vis–NIR spectrophotometer in therange of 200–800 nm at room temperature. An ultrasound bath, an Ossila spin coater (United Kingdom),and a Milli-Q system  were also used. Thermogravimetricanalysis (TGA) was carried out with a TGA Q50 (TA Instruments) equipmentusing a ramp from 100 to 800 °C at 10 °C min–1 under a nitrogen atmosphere. LECO CHNS-932 analyzer was used forthe elemental analysis with complete combustion of the sample.Ramanspectra were recorded using an InVia Renishaw microspectrometer equippedwith a 532 nm point-based laser. The power density was kept below10%, and a 1 s acquisition time was used to avoid laser heating effects.The spectrum range was between 1109.18 and 2228.67 cm45 Briefly, 5 mL of a 1 mM solutionof gold(III) chloride was heated to boiling under magnetic stirring.Then, 5 mL of a 38.8 M sodium citrate solution was added at the boilingpoint and the mixture was heated at reflux for 15 min. Upon stirring,the solution became wine-red in color. Finally, the colloidal suspensionwas stirred and then allowed to stand at room temperature, givinga final concentration of 10.7 nM in water. AuNPs were kept in an amberedbottle at 4 °C.All glass materialsused were cleaned using aqua regia (a mixture of 1:3 nitric acid andhydrochloric acid), then washed with ultrapure water, and dried inair. The nanoparticles were synthesized following a previously describedprocedure.46The gold nanoparticles synthesized were characterizedby UV–visspectroscopy and STEM to determine their size and concentration 1. The ST–1, is related to the defect and disorderlevel within the layers, whereas the G peak, at 1580 cm–1, is due to structures with sp2 domains.48 Regarding the GO oxidation degree, a weight loss of 48.6% was obtainedby thermogravimetric analysis , 2-propanol,and acetone, and dried under a nitrogen gas flow. Afterward, 120 drops(1200 μL) of GO solution were added to the center of the SERSsubstrate using an automatic micropipette. These drops were depositedindividually, waiting until complete evaporation of the previous drop,heating at 50 °C using a hot plate.The SERS-active substrate was preparedas follows: 20 μL of a 10.7 nM solution of the previously synthesizedAuNPs was deposited dropwise (two drops of 10 μL each) ontoa Si/SiO–1 was selected as the analytical signaland subsequently used to quantify GO in the water samples. The spectrumof AuNPs deposited on the substrate by drop casting (20 μL ofa 10.7 nM solution)  was usedas the control and was subtracted for all samples to avoid interferenceof the Au signal with the GO band. All measurements and the calibrationline were performed on the same day and 24 h after the preparationof the substrates. SERS measurements were acquired for 400 μm2 surfaces located in the middle of the drops with an averageof 3000 spectra measurements. The baseline was removed using Windows-basedRaman Environment (WiRE) software. The 3000 spectra were then averagedto give a single spectrum for each replica using a program generatedin MATLAB R2020a with our own code. Finally, calculations were performedusing OriginPro 9.1.The analyte depositedwas analyzed by SERS detection using a Raman spectrometer with a 532nm point-based laser. The laser power was set to 50 mW, and an acquisitiontime of 1 s was employed for measurements. Three different substrateswere prepared for each GO concentration. The intensity of the GO bandat 1346.08 cm2 was chosen since it shows a strong peak at 520 cm–1 in the Raman spectrum. This band is helpful for calibration dueto the lack of interference with GO.46 Theoptimal parameters for the Raman studies were a laser power of 50mW and a wavelength of 532 nm. The sensitivity of the spectrum andduration of the acquisition was 1 s, the same conditions for graphene-relatedmaterials as previously established by our group.49 Although the best results were obtained by mapping 10,000points, we reduced the spectra to 3000 points to optimize the timeper measurement. The mapped areas have an average surface of 400 μm2.To design a robust and reliable methodology for the quantificationof GO, different variables were studied. The first step involved selectionof the appropriate substrate for deposition of the AuNPs. Si/SiO46The next step was to find the optimal volume of AuNPsto obtain a homogeneous SERS substrate (to improve the repeatabilityand reproducibility of our methodology) and, therefore, the best improvementin the GO signal. Our group has already optimized a volume of AuNPsof 20 μL (10.7 nM) for carbon nanomaterials, and we have shownthat a higher concentration of AuNPs decreases the Raman signal ofgraphene due to the thickness of the gold layer.The best methodology for the deposition of both AuNPsand GO toachieve a homogeneous surface was also studied. Two procedures, namely,drop casting and spin coating, were examined. Each drop was depositedand evaporated for the first method, heating at 50 °C on a hotplate. The procedure was repeated until all of the desired drops hadbeen placed. For spin coating, the drops were deposited, and the substratespun at 3000 rpm for 20 s between drops using a spin coater. The highesthomogeneity was obtained using drop casting with the same number ofdrops 3.–1) and another by adding 600 μL of GO dispersion(2000 ng mL–1) only. We found an increase in theintensity of the GO peaks in the Raman spectra in the presence ofAu nanoparticles .Two substrates were prepared using drop casting: one by adding20 μL of AuNPs and 600 μL of GO dispersion (2000 ng mL–1) were depositedon the substrate using the drop casting technique to determine theoptimal volume of GO needed for detection. The best result in termsof homogeneity was at 120 drops (1200 μL). Even when obtaininghomogeneous surfaces  ofGO standards  shows a goodcorrelation between intensity and concentration; on the contrary,the G peak (1587.22 cm–1) does not show correlation.The SERS substrate presents a highly variable peak intensity at thesame Raman shift as for the G peak of GO, with a relative standarddeviation (RSD) of 6.7%. However, for the band at 1346.08 cm–1 (D peak), the control AuNP substrate shows an RSD of 2.6%, witha very low intensity. As such, the D band was chosen as the most appropriatepeak to achieve repeatable and reproducible measurements.Finally, the optimal band for the quantification of GO was alsoexamined. The D peak , were measured by deposing Au nanoparticles on a graphenesubstrate by thermal evaporation.52 Inanother recent study, an enhancement of the Raman signals for as-growngraphene on Cu foils was observed by depositing a 4 nm thick Au film.53 Similar orders of magnitude were found in thequantification of these presynthesized graphene derivatives usingmore sophisticated methods.53An enhancementfactor of 61 was determined for our aqueous graphenedispersions. The EF value is not standardized, and extremely differentEF factors can be observed depending on the substrate and the analyte.Examples in the literature were not found for the quantification ofGO by the SERS technique in real water samples, but the quantificationof some presynthesized graphene derivatives is described. For example,the SERS spectra of single-layer graphene, prepared by mechanicalexfoliation , are also presented in –1. Repeatability andreproducibility tests were also carried out. These aspects were estimatedby calculating the RSDs between the measurements for the same substrateand measurements for different substrates at the same concentration.Thus, we differentiated between intrasubstrate RSD and intersubstrateRSD  and practical limitof quantification (P-LOQ)] and precision. The analytical featureswere calculated by depositing the optimal volume of AuNPs (20 μL)on a bare Si/SiO ng mL–1 5. A strarateRSD 6. Theinurements 6a. The iurements 6b was de–1 andprecision (RSD < 10%), was 0.1 ng mL–1 1. This vTo validate the proposed method, deionized and tap water sampleswere analyzed following the recommended procedure. Although no grapheneoxide was expected to be found in them, the recoveries obtained werehigher than those anticipated for spiked samples. Three fortificationlevels were assayed for each sample; the recovery values are shownin The RSD was calculated from the average recoveries calculated forthe three replicates of each sample. Thus, the RSD range for recoveryvalues was from 2.72 to 7.19%.The continuous increase in thenumber of products based on graphenederivatives makes it likely that, at the end of their useful life,these materials will end up in the environment. However, due to theinsufficient information regarding toxicological aspects, their regulationis still scarce. For this reason, in this study, we developed a methodto detect and quantify GO using SERS. This analytical technique allowsus to detect analytes down to the single-molecule level, with highspecificity, thus resulting in a methodology that is able to quantifyGO at a trace level. We have also shown that the presence of AuNPsincreases the Raman spectra signal of GO, thus allowing the detectionof this compound without a previous preconcentration step.–1. Our literature review failed to identify methodologieswith this sensitivity and power to detect low concentrations. Moreover,this study has shown how this methodology is simple, useful, and effectivein water samples. Although the preparation of substrate and sampleare carried out off-line, we are already considering the on-line preparationtogether with the optimization of new active SERS substrate. Subsequentprogress in the development of methodologies for detecting and quantifyingGO rapidly and straightforwardly in the environment will help to regulatethese products and ensure their safe use in everyday products.Themethod proposed has a limit of quantification of 0.1 ng mL


T ∼ 99 °C.The findings presented here provide a basis for selecting the mostappropriate and suitable method and parameters for silicone oil graftingaimed at low pinning and low hysteresis surfaces for specific applications.Wetting plays a major role in the close interactionsbetween liquidsand solid surfaces, which can be tailored by modifying the chemistryas well as the structures of the surfaces’ outermost layer.Several methodologies, such as chemical vapor deposition, physicalvapor deposition, electroplating, and chemical reactions, among others,have been adopted for the alteration/modification of such interactionssuitable for various applications. However, the fabrication of low-contactline-pinning hydrophobic surfaces via simple and easy methods remainsan open challenge. In this work, we exploit one-step and multiple-stepsilicone oil (5–100 cSt) grafting on smooth silicon substrates, lookingclosely at the effect of viscosity as well as the volume and layers(one to five) of oil grafted as a function of the deposition method.Remarkably, the optimization of grafting of silicone oil fabricationresults in non-wetting surfaces with extremely low contact angle hysteresis (CAH) below 1° and high contact angles (CAs) of ∼108°after a single grafting step, which is an order of magnitude smallerthan the reported values of previous works on silicone oil-graftedsurfaces. Moreover, the different droplet–surface interactionsand pinning behavior can additionally be tailored to the specificapplication with CAH ranging from 1 to 20° and sliding anglesbetween 1.5 and 60° (for droplet volumes of 3 μL), dependingon the fabrication parameters adopted. In terms of roughness, allthe samples (independent of the grafting parameters) showed smallchanges in the root-mean-square roughness below 20 nm. Lastly, stabilityanalysis of the grafting method reported here under various conditionsshows that the coating is quite stable under mechanical vibrations(bath ultrasonication) and in a chemical environment (ultrasonicationin a bath of ethanol) but loses its low-pinning characteristics whenexposed to saturated steam at  Experimentally, the solid–liquidinteractions and wettability are usually described in terms of apparentcontact angle (CA), which is the CA displayed near the contact lineupon the gentle deposition of a droplet on a solid surface. In addition,the advancing as well as the receding CA [the difference between bothgives the contact angle hysteresis (CAH)20] and the sliding angle (SA), additionally provide a metric for thecharacterization of the droplet/film-surface pinning. Therefore, sustainedefforts have been dedicated to developing new coatings and novel proceduresaiming to minimize contact line pinning, promote high mobility, andeventually achieve as low a CAH as possible.Wetting is a surface propertyused to describe the behavior andinteractions between liquid droplets and/or films and solid or liquid-likesolid surfaces. By manipulating a surface’s outermost layer,either physically or chemically, we can control the interaction betweensolids and liquids. This finds application in many engineering, medical,and industrial fields such as anti-icing,21 used a CVD process to coat varioussubstrates, including glass and silicon. This changed the CA fromless than 20° to 60–75° after 30 min of CVD exposuretime, hence enhancing the nonwetting nature of the surface. Mena etal.22 also applied CVD to coat sapphiresubstrates with porous gallium nitride. The surfaces showed a CA of96° after a deposition time of 45 min.Different techniqueshave been utilized to alter the surface physicochemicalcomposition as well as its morphology to transform the intrinsic hydrophilicityof solid surfaces into hydrophobicity. These include chemical vapordeposition (CVD), physical vapor deposition (PVD), and spin coating,among others. CVD and PVD techniques have been widely applied to turnhydrophilic surfaces into hydrophobic ones with a small CAH by depositinga conformal hydrophobic silane-type promoter, initially in a gaseousor solid form, onto an otherwise hydrophilic surface. Silverio etal.24 used CVD to depositpolydivinylbenzene thin films on silicon wafers, which initially showeda CAH of 20° with a rapid decay in the receding CA as time passedand hence a consequent rapid increase in the CAH. Thermal treatmentwas done to stabilize this decay in the receding CA, resulting ina stable CAH of 20–30° even after 2 months. Further effortsto create hydrophobic coatings were carried out by Paxson et al.25 using CVD yielding surfaces with CAH of 5°.These CVD-coated surfaces enabled condensation in a dropwise manner,with the consequent enhancement on the heat transfer performance.More recently, Ma et al.26 have made useof a lipid-inspired high adhesive interface by depositing perfluorodecyltrichlorosilanevia molecular vapor deposition and a conformal fluorine polymer CFx via plasma-enhanced CVD, showing high-condensation heat transferperformance and durability over a year. In addition to these, data-drivenpredictions and/or machine learning can also be applied for the optimizationof parameters, such as CA.27 On the otherhand, Lee et al.23 made use of PVD techniqueto enhance the hydrophobicity of glass enabling condensation occurrencein a dropwise fashion. Stearic acid films of various thicknesses weredeposited on substrates, and it was observed that the advancing CAincreased in a stepper fashion than the receding CA, with the evidentincrease in CAH as the thickness of the deposited films increased,until it reached a plateau at 20° for films thicker than 20 nm.They also reported that a smaller CAH can be achieved when the depositedcoating is continuous and homogeneous rather than heterogeneous asexpected. We can note that CVD has received most of the attentionin the past decade, and it is the most commonly used technique dueto its ability to deposit a monolayer of the coating with very accurateand controlled properties, as well as higher purity when comparedto PVD, while PVD has mostly been applied as a protective coatingagainst chemicals or corrosion.Apart from achievinga low CAH, the stability of the coating andhence keeping uniform CA and CAH for longer periods of time is alsocrucial. Zhao et al.28 on hydrophilic glasssubstrates, which resulted in a CA of approximately 92°. Furthermore,Syafiq et al.29 developed a three-steptechnique for creating transparent hydrophobic coatings on a glasssurface. Along with high transparency, the surfaces showed a CA of103.9°. Although these coatings showed good results in termsof wettability, transparency, and stability, the preparation methodinvolved several steps and chemicals, making it not suitable as aneasy and fast procedure.Although the functionalizationtechniques described above providea desirable outcome in terms of low wettability and low pinning, theyare, however, rather complex and difficult to fabricate as per theneed for an environmental chamber and vacuum for the deposition ofhigh-quality coatings. In contrast, spin coating of hydrophobic filmscan be carried out without the need for a controlled environment orvacuum, although there is need for a further annealing process. Theannealing process via sol–gel spin coating was exploited byBougharouat et al.32 This method involves dip-coating a substrate in an isopropanol solutionof dimethyldimethoxysilane and sulfuric acid, followed by drying andrinsing the substrate with water, isopropanol, and toluene. The resultingsurfaces showed very low CAH of approximately 1°  with lower droplet mobility (high dynamic friction) whencompared to other functionalization techniques providing similar oreven higher CAH.33One more recent promising approachfor the fabrication of low-contactline-pinning surfaces is the use of slippery omniphobic covalentlyattached liquid (SOCAL) surfaces.5 Note that grafting of silicone at ambient temperatureand in the absence of UV radiation is also possible and has been recentlyreported.34 The types of oils/lubricantsused in the process can range from fluorinated solvents and siliconeoils to mineral oils and ionic liquids. Silicone oils and mineraloils are used most commonly because of their chemical compatibilitywith various substrates and wide viscosity ranges with no change intheir chemical properties.35 In this regard,Eifert et al.36 and Chen et al.37 proposed a simpler technique to create hydrophobicsurfaces with a further step of lubricant impregnation on severalsubstrates. Silicone oil is applied to the surface and treated thermally.As a result, oil evaporates, leaving behind PDMS brushes that attachto the original surface, either glass, aluminum, silicon, copper,stainless steel, or brass, conferring a hydrophobic behavior and anintermediate CAH (20°). After further impregnation of the samesilicone oil within the PDMS brushes, stable lubricant-infused surfaces(LISs) with a CAH of 2.4° were attained by Eifert et al.36Another novelmethodology explored for inducing the hydrophobicityof a solid surface is via oil grafting. This grafting process consistsof the insertion of polydimethylsiloxane (PDMS) brushes by evaporatingan oil on a surface via heating or using ultraviolet (UV) radiation.Despite the promising results obtainedfrom these findings, noguidelines or attempts on the optimization of various parameters,such as the grafting temperature, type of oil, volume of oil grafted,oil viscosity, substrate underneath, and number of layers grafted/thicknessof the coating, have been considered. The optimization of such parametersis very critical for the accurate control of the wettability and/orcontact line pinning on these silicone oil-grafted hydrophobic surfaces.36 The durability and stability aswell as the changes in roughness of the prepared surfaces have alsobeen investigated and reported. In summary, this work provides a frameworkto select the most suitable method for altering surface wettabilityand/or tuning contact line pinning via silicone oil grafting usingthe pipette/dip-coating method and thermal grafting. Surfaces createdin this manner could be further impregnated with oil to create slipperylubricant-infused porous surfaces (SLIPS) or LIS.Hence, here, we report a methodological and systemic approach providingsuitable conditions for grafting silicone oil on solid surfaces, enablinghydrophobicity coupled with the flexible tuning of the CAH. This proposedmethod is simple, as it may only require one step, and easy, as itdoes not need vacuum conditions. The prepared surfaces adopting differentfabrication parameters are then characterized in terms of wettabilityshowing a high CA ∼ 108°, low-to-intermediate CAH between1 and 20°, and low-to-high sliding/roll-off angles between 1.5and 60° for 3 μL water droplets. By optimizing the fabricationparameters, extremely low CAH below 1° can be attained, as reportedhere, which is still lower than the values reported on LIS by Eifertet al.22.136 In addition, an air plasma cleaner  is used to further cleanthe samples from any organic compound adsorbed onto the surface priorto grafting. A heating plate (Fisher Scientific UK Ltd.) is used forgrafting the silicone oil.Plain silicon wafers witha smooth finish on one side, purchased from Si-Mat , are used as the hydrophilic substrate. Silicon wafers arediced into 1 cm × 1 cm samples. Silicone oils varying in viscosities are purchased from Sigma-Aldrich. Pureacetone and ethanol organic solvents (Sigma-Aldrich) are used forcleaning the silicon wafers in an ultrasonic bath . On one hand, silicon wafers are adopted for thefabrication procedure because of their very smooth finish on one ofthe sides, which rules out any effects of structures or surface roughnesson both the wettability characterization and the grating coating methodemployed. On the other hand, silicone oil is selected as the graftedlubricant owing to its nontoxicity, environmental friendliness, lowcost, and ready availability, as reported by Eifert et al.2.238 prior to the silicone oil grafting.The plasma-cleaning step is performed to ensure the complete spreadof silicone oil on substrates since the presence of hydroxyl groupsafter plasma cleaning enhances surface wettability39 and provides better uniformity and stability of the oilgrafted. Surfaces prepared without plasma cleaning still show goodresults in terms of wettability and low CAH, as shown in the Supporting Information Section SI-1. The CAsbefore and after solvent cleaning and after air plasma cleaning aremeasured at different laboratory ambient exposure times, which arepresented in 38 After that, finite CAs of28°, 49°, and 59° are reported after 3, 7, and 14 days,respectively  are also investigated. The different grafting parameters investigatedare summarized in The fabricationprocess is depicted in the schematic diagram shown in Supporting Information Section SI-2. These withdrawal speedsdeposited approximately 0.187, 0.185, and 0.855 μL of oil foreach coated layer, according to the Landau–Levich–Derjaguin(LLD) equation.41 We note here that theLLD equation estimates the thickness of the oil layer, which is thenmultiplied by the area of the substrate to estimate the approximatevolumes reported above. Thereafter, silicone oil is then grafted onthe surface, making use of the heating plate at 200 °C for 100and 1000 cSt oils and at 250 °C for 20 cSt oil. A smooth surfacefinish is observed after the evaporation of 20 and 100 cSt oils; however,for 1000 cSt oil, nonuniform evaporation and nonuniform depositionof the oil on the surface were apparent. Hence, the present graftingmethod is deemed not suitable for such high-viscosity oil and henceoils with of viscosities higher than 100 cSt are not further consideredwithin this investigation. 5 cSt oil grafted samples are also preparedvia the dip-coating method  to allow comparison betweenthe two oil application methods for this low-viscosity oil.We note here the occurrence of nonuniform evaporationof siliconeoil during grafting in the case of medium/high-viscosity oils , which have been applied evenly following the pipettemethod at grafting temperatures of 250–300 °C. Hence,to ensure the deposition of a uniform thin layer of high-viscosityoils, the dip-coating method, with withdrawal speeds of 0.05 mm/sfor 20 cSt oil, 0.01 mm/s for 100 cSt oil, and 0.01 mm/s for 1000cSt oil, is adopted along with low-grafting temperatures. The effectof grafting temperatures is briefly described in 2.4x–y–z stage,is used to deposit deionized water droplets of controlled volume of3 ± 0.5 μL on different fabricated samples. The schematicof the setup is shown in 43 The apparent CA is measured after the gentle/slowdeposition of a droplet on the surface. In order to retrieve the CAH,upon droplet deposition, water is added and withdrawn at the rateof 0.2 μL/s to obtain the advancing CA and receding CA, respectively.These are used to calculate the CAH = advancing CA – recedingCA. The SA on the other hand is measured as the tilting angle at whicha 3 μL water droplet rolls off from the surface. All experimentsare performed at ambient room conditions, that is, at ambient temperatureof 23 ± 3 °C, relative humidity of 38 ± 2%, and ambientpressure of 1 atm. 44 Here, the advancingCA is calculated as the average CA over a range of values at the initiationof the base radius motion, and the receding CA is obtained as theCA value when the base radius starts to decrease.The fabricated surfaces are then characterized in terms of wettabilityor apparent CA, CAH, and SA. The working fluid used is deionized waterwith a surface tension of 72 mN/m at ambient temperature. A drop shapeanalyzer DSA100 from KRÜSS ,comprising of an automated dosing system including a syringe and aneedle, a CCD camera, a back light, and a manually controlled 3The preparedsamples are characterized in terms of apparent CA,CAH, and SA. All experiments are repeated three times for SA and CAH,while for apparent CA, an average of the CA at four different samplelocations  is utilized. The results obtained are then presented anddiscussed in terms of different fabrication parameters as follows:in 3.136 reporting a CAH of 20°, and a 2-fold decrease in theSA when compared to Chen et al’s37 (SA of 10° for a 5 μL water droplet). The extremely lowCAH reported here is analogous to that recently reported on SLIPS/(LISs)46 and/or SOCAL.3238 While there isno obvious change in the apparent CA upon implementation of the secondlayer, an increase in both CAH and SA is observed for all oils, althoughthe effect is more pronounced for 5 and 20 cSt oil viscosities thanfor higher viscosity ones. Rather similar values of CAH and SA arereported independently of the presence of one or two layers for 100cSt prepared by dip-coating. The effect of number of layers is furtheraddressed in Various viscosityoils  are utilized to address the effect of viscosityon the apparent CA, CAH, and SA, as all these parameters are related,to some extent, to surface wettability and contact line pinning. 3.247In additionto the oil viscosity, different numbers of layers (from one to five)are grafted on substrates, and the apparent CA, CAH, and SA are thenreported in 37Nonetheless, the different deposited volumes andthe differentoil deposition methods do yield differences in the apparent CA rangingfrom 99° to 110° about all in the cases of low- and medium-viscosityoils of 5 and 20 cSt 6. The ra48 The lower CAH and SAreported for multiple-layer grafted surfaces can be explained by theincreased number and density of the embedded PDMS brushes, forminga denser chain structure, which effectively inhibits the direct interactionof water droplets with the underlying substrate,47 and hence droplets are more mobile. We shall stress herethat in the case of low-viscosity silicone oil (5 cSt), the depositionof the oil via the dip-coating or pipette method, making use of smalloil volumes before grafting, may not allow for the complete coverageof the substrate. This is supported by the high droplet pinning tothe surface not being able to slide from the surface even for SA ashigh as 90°, in agreement with the SA on bare silicon substrates.Although no major changes are observedwhen looking at the apparentCA, an overall decreasing trend in CAH and SA is observed as the numberof layers increases for all samples with 5 cSt grafted oil 7a,d. A rIn the case of 20 cSt grafted oil making use of5 μL oilper layer via the pipette method, a slight increase in CAH and inthe SA are observed after the second layer, while a further decreasefor a CAH below 2° and a SA near 10° are reported for thethird layer, as shown in 50 In addition, the thickness of the grafted layer also increases proportionallywith the viscosity of the oil (length of polymer chains) grafted51 and with the number of layers, thereby preventingany direct contact between the droplet and the silicon substrate,which results in high apparent CA as well as low CAH and SA.Samples grafted with 100 cSt oil deposited via the dip-coatingmethod yielded the lowest CAH among all samples after the first layer,with a slight upsurge in the CAH for further grafted layers. Nonetheless,CAH results for multiple layers were all below 1° and self-containedwithin the standard deviation, as seen in 3.342 In the case of20 cSt silicone oil, 2 and 5 μL via the pipette method and 0.187μL via the dip-coating method are grafted. While in the caseof 100 cSt silicone oil 0.185 μL per layer are deposited. Asshown in The differentvolumes of oil grafted per layer are found in 36 Weassume that the rather high contact line pinning reported in Ref 36can be attributed to the small amount of oil deposited on the surface,to the rinsing step adopted after grafting, or to the lack of oxygenplasma treatement before grafting.When looking closely at the SA for 5 cSt oil grafted samples, theSA typically decreases as the volume of oil applied via pipette increases7d–f,excNext, when looking into 20cSt grafted oil samples, the highestvalues of the SA are observed for the dip-coated samples 7e, unlikTo someextent, the volume of oil deposited/grafted on the surfaceis both proportional to the number of layers and to the amount ofoil deposited for each step via the pipette method. Typically, greatervolume and greater number of layers decrease contact line pinningand increase droplet mobility for low-viscosity oils (5 cSt). However,in the case of medium- and high-viscosity oils (20 and 100 cSt), thelowest of the volumes deposited via the pipette method and the lowvolume deposited via the dip-coating method yield the lowest CAH andSA, with these slightly increasing with the number of layers.3.4To understandthe changes in surface morphology after oil grafting, the profileof the prepared samples is measured using a DektakXT Stylus Profilerwith the Standard Manual X-Y Sample-Positioning Stage ,and the root-mean-square (RMS) roughness values are calculated. Itcan be observed from 3.5Supporting Information SectionSI-3. To first check the mechanical stability of the coatings, thesamples are placed in an ultrasonic bath for 30 min. Sonication meanssubjecting the samples to mechanical vibrations by placing them ina beaker in an ultrasonic bath of water. The temperature is maintainedat 17–20 °C for sonication in controlled temperature tests.Samples are placed in a beaker containing ethanol, which is placedin an ultrasonic bath of water for sonication in ethanol tests. Theerror bars are attained by repeating each test three times. We notethat as the ultrasonication proceeds, the temperature of the mediaand that of the samples increase to values near 50 °C due tothe imposed mechanical vibrations. It is observed that in the caseof increasing temperature, the stability worsens under mechanicalvibration in ethanol tests . Under solely mechanicalvibrations with increasing medium temperature, the apparent CA slightlyincreases, while under mechanical vibrations at controlled temperature,the apparent CA decreases down to approximately 100° for both5 cSt with five layers and 100 cSt with three layers. When lookinginto the results after mechanical vibration tests under noncontrolledtemperature condition, the CAH remained below 1° showing loweror equal CAH than before the mechanical test. At controlled temperature,the CAH increases to 8° for both cases . Whereas, for high-viscosity oil graftedsamples, that is 100 cSt, a 3–4° decrease in the apparentCA is observed after the first cycle, and no further change is reportedeven after seven cycles of steam exposure with an apparent CA above104°. In terms of CAH, for 5 cSt oil grafted samples, a smallincrease is perceived after one cycle, while a substantial increaseis observed afterwards. While for 100 cSt oil grafted samples, theincrease in CAH is very small below 10° for two- and three-layergrafted samples even after five cycles of steam exposure. Thereafter,the CAH increases sharply with a value equal to or above 20°.This is coherent with the results reported by Liu et al.,53 where CAH below 20° is reported on PDMSbrushes even after 40 h of exposure to the steam; however, in theircase, the steam temperature was kept at 70 °C, while our saturatedsteam was at 99 °C. When comparing these two works, as the temperatureof the steam increases (from 70 to 99 °C), the stability of PDMSbrushes decreases. Overall, the 100 cSt oil grafted samples showedvery good results in terms of wettability (high apparent CA), contactline pinning (low SA as well as low CAH), and stability, with lowchange in apparent CA, CAH, and SA, throughout the different tests.Although PDMS brushes can actually be utilized effectively for steamcondensation,54 it did not work in ourcase. We note here that more research work focusing on the physicaland chemical interactions between the grafted oil and the solid surfaceare needed for the development of more stable grafting proceduresin harsh environments.To further investigate the stability ofthe PDMS brushes graftedin a humid and high-temperature environment, samples are subjectedto high-temperature saturated steam (99 ± 1 °C) for differentnumber of cycles with a duration of 5 min per cycle. For low-viscositygrafted oil, that is 5 cSt, the apparent CA decreases marginally afterone cycle, but a considerable decrease was observed after three cycleswith an apparent CA below 100°  are grafted, which ultimately enhances the mobilityof the three-phase contact line on such surfaces as in the presentcase.57 This is also supported by the factthat the bigger island features on grafted samples (longer molecularchain lengths in our case) ensure the full coverage of the substrate,leaving no gaps between the grafted structures (PDMS brushes), whichreduce the presence of pinning sites, and as such, a low CAH is observedon such surfaces.55A recent review by Chen et al. provides a clear accounton theeffect of molecular weight or chain length of the grafted brusheson the grafting density and on CAH. On one hand, an increase in themolecular weight or chain length of the grafted PDMS brushes resultsin a decrease of the grafting density. On the other hand, a decreaseand then an increase in the CAH is reported as the molecular weightor chain length of the PDMS brushes increases.Supporting Information.Besides siliconas the base substrate, additional experiments makinguse of polished copper substrates showed, on the one hand, similarapparent CA in the hydrophobic regime. On the other hand, CAH in thecase of 5 cSt grafted oil increased considerably by 1 order of magnitude,whereas in the case of 100 cSt grafted oil, only an increase of 1or 2° was observed when compared to silicon based ones. The presumablylower wetting and higher roughness of the copper substrates  would slow down or hinderthe motion of the silicone oil contact line during grafting, whichmay result in less uniform and less homogeneous film deposition duringgrafting with the consequent droplet pinning enhancement. In addition,the different affinity of the PDMS brush attachment  with the basesubstrate also may play a role in the motion of the water dropletcontact line when characterizing the CAH. Further details on theseresults are provided in Section SI-3 of the Supporting Information. Overall, 100 cSt oil-grafted samples show the highest stabilityeven after 10 h of mechanical vibrations and after 5 h of sonicationin an organic solvent (ethanol), which render these surfaces promisingcandidates for fluid manipulation. Findings reported here not onlybenefit the industry but also biomedical, microfluidics, engineering,and electronic applications.58Although it is not the primary focus ofthis communication, thestability of the grafted layers is of paramount importance for long-termapplications. Nonetheless, to provide some preliminary insights onthe stability of the different grafted surfaces; mechanical vibrations,chemical immersion, coupled chemical and mechanical vibrations, andsteam environment, have been carried out and are included and discussedin 4We have presented a systematicapproach to optimize the fabricationparameters for preparing easy, one-step, low-CAH water-repellent surfacesby silicone oil grafting over bare silicon wafers. Silicone oils withviscosities ranging from 5 to 100 cSt have been applied using eithera pipette or dip-coating method for mono- and multilayer/step depositionprior to grafting. During grafting, the oil evaporates, leaving behindthe so-called PDMS brushes, rendering the surface hydrophobic withnonwetting CAs between 105 and 108° and a different range ofSAs and CAH as a function of the fabrication procedure adopted. Optimizedgrafting parameters enabled a remarkable CAH below 1° for 100cSt silicone oil, owing to the longer molecular chains of the PDMSbrushes that are covalently attached to the surface. This extremelylow CAH is comparable to current LISs and slippery, omniphobic, covalentlyattached liquid-like surfaces and an order of magnitude lower thanthat reported by earlier works using a similar grafting procedure.In addition, the parameters studied here offer the additional capabilityof tuning the CAH between 1 and 20° and SAs between 1.5 and 60°(for 3 μL water droplets), depending on the fabrication procedure.When looking at the different parameters studied, higher volumes ofthe deposited oil are preferred for low-viscosity oils, whereas lowoil volumes as well as lower grafting temperatures are more appropriatefor high-viscosity oils. Moreover, the prepared surfaces demonstrategood stability under various tests, with the 100 cSt oil-grafted sampleshowing the highest stability in terms of wettability, with CAs inthe range of 103–107° and CAH below 9° even after10 cycles of ultrasonication in ethanol. Our findings support theparameter optimization of an easy, fast, and universal approach tocreate hydrophobic low contact line pinning surfaces, which may beutilized to fabricate further LISs and/or SLIPSs where the stabilityof the coating, prior to impregnating a lubricant oil, is crucialfor specific engineering and/or industrial applications.


Obtained results showed that AAEM compounds promote the decomposition of biomass by reducing the initial and peak pyrolysis temperatures. More specifically, the catalytic effect of the alkaline earth metal was shown to be stronger than that of alkali metals. To further interpret the obtained trends, a kinetic modeling of measured data was realized using two isoconversional methods  and Kissinger–Akahira–Sunose (KAS) models). With a view to identifying a suitable reaction model, model fitting and master plot methods were considered to be coupled with the isoconversional modeling approaches. The 3-D diffusion reaction model has been identified as being well suited to properly simulate the evolution of the conversion degree of each sample as a function of the temperature. Furthermore, the kinetic parameters derived from the present modeling work highlighted significant decreases of the activation energies when impregnating wood with AAEM chlorides, thus corroborating the existence of catalytic effects shifting the decomposition process to lower temperatures. A survey of the speculated pathways allowing to account for the impact of AAEMs on the thermal degradation of woody biomass is eventually proposed to better interpret the trends identified in this work.This work analyzes the catalytic effects induced by alkali and alkaline earth metals (AAEMs) on pyrolysis kinetics. To this end, thermogravimetric analyses (TGA) were carried out with raw beech wood and samples impregnated with NaCl, KCl and MgCl Alongside increasing concerns about global warming, biomass, a neutral-carbon fuel, is attracting more and more attention, not only for heat and electricity generation, but also for the production of valuable biochemicals and biomaterials. When being pyrolyzed under an inert atmosphere, the biopolymers composing the lignocellulosic biomass typically decompose into biochar, bio-oil and incondensable biogas . However2CO3 and K2CO3) on the production of phenols during the pyrolysis of lignin [2, they have proven to enhance the degradation of hemicellulose to form oxygenate molecules and furans [Among the catalysts currently considered in the framework of biomass pyrolysis, specific attention has recently been devoted to alkali and alkaline earth metals (AAEMs) due to their low toxicity, affordable price, high catalytic efficiency and non-negligible quantity in raw biomass . AAEM cof lignin . They nof lignin . Furtherf lignin . They ref lignin . As for d furans  while prd furans .Notwithstanding the findings reported in the above literature survey, kinetic analyses dealing with the AAEM-catalyzed pyrolysis of biomass remain relatively rare, as highlighted in . This la2) added by wet impregnation. Non-isothermal thermogravimetric measurements were performed with heating rates ranging from 5 to 30 °C/min. Obtained results were then modeled by means of two isoconversional models  and Kissinger–Akahira–Sunose (KAS) models) to ease the interpretation of obtained trends.With this in mind, the present work aims at analyzing and modeling the kinetics related to the AAEM-catalyzed pyrolysis of a woody biomass. To this end, pyrolysis experiments were conducted with raw beechwood and samples catalyzed with three AAEM compounds . Four heating rates  were used to heat the samples from room temperature up to 950 °C, with a plateau at 105 °C, for 20 min to ensure the elimination of free water. To perform all the TGA tests, 10 mg of sample was put in alumina crucibles. An inert atmosphere was continuously maintained around heated samples by means of a 100 mL/min nitrogen flow. Three tests were performed for each sample and operating condition. It should therefore be considered that all the mass loss profiles presented in the following and used for the modeling work presented in −1), The variation of the fuel conversion degree The term on the right-hand side of Equation (3) corresponds to an exponential integral which has no exact solution (in closed form). An algebraic approximation of this term must therefore be used to enable the calculation ,25. By rsumption , the funAs for the OFW integral isoconversional model ,28, it cRegarding the values of termined :(7)Aα=R×As far as the KAS model is concerned, it consists of plotting straight lines depicting the evolution of With a view to selecting a proper reaction model, two possible routes are summarized in the review by Wang et al. . The firenergies ,31,32,33energies ,35,36.The data fitting method selected herein consists of the Šatava–Šesták model , which iIn the present work, 10 different reaction models were tested, namely, F1, F2, F3, D2, D3, R2, R3, A2, A3 and A4 ,45.To ease the identification of a suitable reaction model, Sánchez-Jiménez et al. proposed a calculation procedure consisting of transforming measured data into an experimental master plot that does not depend on experimental conditions . This maBy combining the general expression of dFor a single-step process, the expression of the reaction model is invariable. Using a reference point at By comparing theoretical and experimental curves  and final (Tf) decomposition temperatures estimated for conversion degrees of 10 and 90%, respectively, as well as the peak temperature (Tp) assessed at the peak mass loss rate.To better highlight and discuss the observed discrepancies, Based on the data gathered in i and Tp values, which is consistent with the role played by alkali and alkaline earth metals on the reduction of the pyrolysis temperatures [i reductions observed with MgCl2 regardless of the heating rate. Impregnating beech wood with magnesium chloride indeed allows reducing the initial pyrolysis temperatures by 43 °C on average when considering all i values measured for the raw biomass sample. On the other hand, potassium only induces a mean Ti drop of 10 °C against 1.6 °C for sodium, which mainly shows a catalytic effect for temperatures higher than 300 °C.As shown in eratures ,51,52,53i values were much more reduced when using alkaline earth metals such as calcium and magnesium instead of potassium to catalyze the pyrolysis of rice straw and cellulose, respectively [It is noteworthy that these trends are actually in line with those identified in previous investigations dealing with the impact of AAEMs on the pyrolysis of woody biomass components. Yu et al. indeed reported that magnesium was able to lower the onset temperature of cellulose pyrolysis . Gao et ectively ,53.p indeed decreases by 22, 29 and 15 °C on average for the samples impregnated with NaCl, KCl and MgCl2, respectively  when impregnating beech wood with AAEMs. Mean TG700°C values calculated based on all heating rates indeed pass from 30.4 wt% for the raw biomass to 38.6 wt%, 37.7 wt% and 34.1 wt% when using sodium-, potassium- and magnesium-based catalysts, respectively. Such a trend, which here again, is in line with the observations made in previous studies [As for the peak temperatures, similar trends are observed for all catalysts. Tvely see . It is i studies ,55,56,57As illustrated in energies ,58, whicenergies  has sincenergies ,60,61,62The OFW and KAS isoconversional models were implemented following the calculation procedures described in 2 ≈ 0.985 on average). As can be seen, for each 10% step of the conversion degree, identical activation energies are obtained with the OFW and KAS models . The activation energies then increase for higher conversion degree, thus indicating a pyrolysis behavior relatively similar to that described in the case of beech wood. Another interesting feature emerging from the tests performed with NaCl, KCl and MgCl2 concerns the global reduction of the When analyzing the results gathered in  cleaved . As for 0 kJ/mol . Neverthn), diffusion (Dn), geometrical contraction (Rn) and nucleation (An) ones, as listed in The Šatava–Šesták model was implemented following the procedure described in 2 ≤ 0.99), identifying a proper model based solely on R2 values may be inadequate, as highlighted by Khawam and Flanagan [Although most of the tested models allow obtaining a high coefficient of correlation  and diffusion (D2 and D3) models allow obtaining activation energies quite close to those inferred using the OFW and KAS models. Nevertheless, the D3 model still appears to be the most suited. Its use indeed leads to the lowest deviations between the To corroborate the conclusion drawn above, we carried out complementary calculations aimed at stimulating the evolution of the conversion degree of each sample as a function of the temperature when considering the 10 reaction models used herein. Obtaining such curves, however, required integrating both As can be seen by looking at Following the procedure described in By integrating the parameters assessed by means of the OFW and KAS models in Equation (2) while considering the so-identified D3 mechanism, one obtains the conversion degree profiles depicted in 2 reach values of 1.83 × 10−4 s−1, 2.92 × 10−4 s−1, 3.83 × 10−4 s−1 and 4.26 × 10−3 s−1, respectively, for a temperature of 325 °C . Furthermore, the ability of the tested AAEM chlorides to promote the pyrolysis follows the sequence: MgCl2 > KCl > NaCl, which is in line with the experimental observations made in As can be seen, simulated data satisfactorily reproduce their experimental counterparts regardless of the considered sample. As such, the results depicted in To better understand the observations made in + cations have been proven to act on cellulose through hemolytic cleavage in pyranose rings and heterocyclic cleavage of glycosidic linkage while promoting ring scission, isomerization, dehydration, decarbonylation and/or decarboxylation reactions, which promote the formation of smaller furans and alcohols [First, alkali and alkaline earth metals have been demonstrated to promote the cleavage of intra- and inter-molecular bonds  in biomass. They, moreover, favor the cracking of primary volatiles, thus enhancing the yields of light oxygenated compounds and incondensable gaseous species while contributing to limiting the formation of levoglucosan. In that respect, Zhao and Li notably showed that small sodium cations were likely to pierce through rice husk textures to act on biopolymers , thus changing the pyrolysis reaction pathways and favoring biomass degradation . More spalcohols ,70. Besialcohols . Furtheralcohols . As for alcohols ,13,71. A2-impregnated yellow poplar that magnesium could enhance the repolymerization of the volatile molecules released, which would increase the average molecular weight, the viscosity and the solid content of the produced bio-oil despite its higher water content [Secondly, AAEMs can play an important catalytic role as bridges linking adjacent oxygenated functional groups. As such, AAEMs are thus likely to promote recombination reactions favoring the formation of char. Hwang et al. notably reported in their study on the pyrolysis of MgCl content . Such a 2) was investigated at four heating rates by means of thermogravimetric analyses. Obtained results showed that the tested alkali and alkaline earth metals promote biomass decomposition by reducing the initial and peak pyrolysis temperatures. The alkaline earth metal (magnesium) was, moreover, found to exhibit a higher catalytic effect than alkali metals (sodium and potassium), as exemplified by its higher ability to reduce initial decomposition temperatures. A comprehensive kinetic analysis of measured data was then realized using two model-free methods (OFW and KAS models). In terms of highlights, the OFW and KAS models led to inferring very similar activation energies, which were, moreover, found to be lower for the samples impregnated with NaCl, KCl and MgCl2, thus corroborating the existence of a catalytic effect when such AAEM compounds are added to beech wood. Coupling the above-mentioned isoconversional models with model fitting and master plot approaches allowed to identify the D3 mechanism as being well suited to reproduce experimentally monitored data. While they allowed to simulate the evolution of the conversion degree of each sample as a function of the temperature regardless of the heating rate, the kinetic parameters inferred within this work also led to an illustration of increases of the pyrolysis rate constants when impregnating biomass with AAEMs.The pyrolysis of raw beech wood and samples impregnated with three AAEM catalysts  have been discussed herein in a bid to interpret the observations made throughout this study. The trends depicted herein thus allowed to corroborate some speculated pathways proposed to account for the impact of AAEMs on the thermal degradation of woody biomass. Furthermore, obtained results also confirmed the interest of coupling varied modeling approaches to contribute to elucidating the fundamentals of AAEM-catalyzed pyrolysis, noting that complementary simulation tools including refined global kinetic schemes as well as phenomenological models would benefit from being considered in complementary studies, thus paving the way for future works to be undertaken.


P < 0.001). The procedure-related complication rate was 6.0%. All 19 patients (14.1%) with stent occlusion underwent endoscopic re-intervention successfully. Multivariate analyses revealed chemotherapy after DS placement (P = 0.01), stricture site in D3  (P = 0.01), and a Glasgow Prognostic Score (GPS) of 0–1 before duodenal stent placement (P < 0.001) were factors significantly associated with prolonged OS. In conclusion, patients with a GPS of 0–1 and D3 stricture who are tolerant of chemotherapy are suitable candidates for DS placement.Endoscopic duodenal stent (DS) placement for malignant gastric outlet obstruction (GOO) is rapidly increasing in clinical practice; however, the most suitable patient candidates for DS placement have not been determined. One hundred and thirty-five patients with GOO who underwent DS placement in three Japanese referral centers between January 2010 and October 2019 were retrospectively evaluated. Overall survival (OS) after DS placement, technical/clinical success rates, adverse events, and predictive factors affecting OS after DS placement were also analyzed. The median OS after DS placement of all patients was 81 (7–901) days. Technical and clinical success rates were 99.3% and 83.7%, respectively. The GOO Scoring System score significantly increased before and after DS placement (0.9 vs. 2.7,  GOO is a common complication of advanced pancreato-biliary cancer, distal gastric cancer, duodenal cancer, and metastases from other malignancies2. Once malignant GOO occurs, patients experience episodes of abdominal fullness, nausea, vomiting, and the difficulty of adequate oral intake3. These symptoms significantly impact performance status and quality of life, resulting in difficulties with cancer treatment and shortening of patient survival4. GOO is usually treated with surgical gastrojejunostomy (GJ) or insertion of an endoscopic duodenal stent (DS). Although it remains unknown whether DS is superior to GJ for malignant GOO, DS placement is rapidly increasing in clinical practice since it is a less-invasive treatment that promptly relieves symptoms6. However, the long-term efficacy and safety of DS have not been fully elucidated in the era of advancing oncological treatments, and several issues, such as short overall survival (OS) after DS placement, high rate of re-intervention, and multiple type of cancers as the cause of GOO, remain unsolved.Gastric outlet obstruction (GOO) occurs as a result of a narrowing in the region of the gastroduodenum, which induces failed or delayed passage of gastric contents from the stomach to the jejunum10. However, the relationship between these systemic inflammatory markers and the prognosis of patients with DS placement is scarcely known.Recently, simple parameters of systemic inflammation, such as the neutrophil-to-lymphocyte ratio (NLR) and the Glasgow Prognostic Score (GPS), have been recognized as prognostic markers for patients with various cancers including pancreato-biliary malignancies12, but some patients, following DS placement, are unable to receive chemotherapy due to low performance status in daily clinical practice. Thus, it has not been determined who will benefit most from DS placement despite the widespread application of DSs.Treatment after DS placement is another important issue because it significantly affects OS in patients with DS. Several previous reports revealed the efficacy of chemotherapy after DS placementIn this study, we evaluated the safety and efficacy of endoscopic DS placement for patients with GOO in three referral centers located in the Kyushu region of Japan. We aimed to evaluate the clinical effectiveness of DS placement and to identify prognostic factors associated with survival after DS placement.This retrospective study was conducted at three referral centers to evaluate the efficacy and long-term outcome of patients with GOO who underwent endoscopic insertion of a DS. Patients with GOO were recruited from each hospital between January 2010 and October 2019. The patients with malignant GOO who underwent DS placement during the above period were included in this study. The exclusion criteria were as follows: poor general condition (high risk of endoscopic procedure), resectable diseases, and surgically altered anatomy except for Billroth I reconstruction. We reviewed the following clinical data: age, sex, symptoms, Eastern Cooperative Oncology Group Performance Status (PS), NLR and GPS before DS placement, Gastric Outlet Obstruction Scoring System (GOOSS) score, primary cancer type, site of stenosis, procedures for duodenal stenosis and biliary obstruction, re-intervention, OS, adverse events, such as procedure-related complications and stent dysfunction, and oncological treatments. The primary endpoint was OS after DS placement. The secondary endpoints were technical/clinical success rates, rate of adverse events, predictive factors for clinical success, and predictive factors affecting OS after DS placement. We obtained informed consent for the DS placements from all patients. This study was conducted in accordance with Helsinki Declaration, and the study protocol was approved by the Ethics Committee of Kyushu University , Nakatsu Municipal Hospital , and Kyushu Medical Center .Endoscopic DS placements were performed under conscious sedation induced by an intravenous injection of midazolam and/or pentazocine. A lateral-viewing duodenal endoscope  or a forward-viewing gastrointestinal endoscope  was used according to the site of the stricture. First, an endoscope was inserted at the proximal site of stenosis with a catheter, and a guidewire passed through the stricture. After confirming the site and length of duodenal stenosis with a contrast medium, the DS was deployed across the stricture under endoscopic and fluoroscopic guidance. According to the site and length of a stricture, a WallFlex DS , Niti-S DS  or Evolution DS  was selected based on the endoscopist’s preference.2. We recorded the GOOSS within the 7 days before and after placement of the DS, and the best score was applied to the analysis.The extent of oral intake was evaluated using the GOOSS: 0, no oral intake; (1) exclusively liquid diet; (2) exclusively soft solid diet; and (3) low-residue or full diet13.The sites of the duodenal obstruction were defined as D1, D2, and D3, as previously reported; D1 and D3 strictures were in the proximal and distal parts of the papilla, respectively, and a D2 stricture was defined as having involvement in the papillaOS was defined as the duration from the date of DS placement to the date of death. Technical success was defined as the adequate endoscopic placement of the DS across the stenosis. Clinical success was defined as the achievement of a GOOSS score of 3 after DS placement.P < 0.05.Statistical analyses were performed using the JMP version 15 software . GOOSS scores before and after DS placement were compared using a Wilcoxon signed-rank test. Predictive factors for clinical success were analyzed using logistic regression models. OS was analyzed using the Kaplan–Meier method. Univariate and multivariate analyses were conducted using the Cox proportional hazard model to reveal the predictive factors for OS. The level of significance was set at A total of 138 patients with GOO who underwent endoscopic DS placement were enrolled in the study. Three patients were excluded, two of whom with surgically altered anatomy had a stent insertion for another object, such as resolution of obstructive jaundice and afferent loop syndrome. One patient had surgical treatment after DS placement. Thus, 135 patients were analyzed, and their clinical characteristics are summarized in Table Of the 135 patients, 67 (49.7%) had poor PS (2 or 3), and 65 (48.1%) had a GPS of 0 or 1. The most common primary cancer was pancreatic ductal adenocarcinoma (PDAC) (68.1%), followed by cholangiocarcinoma (13.3%). Ninety-eight patients (72.6%) had metastatic diseases. The site of GOO was most often located in D1 (47.4%), and the numbers of D2 and D3 strictures were comparable. Regarding the type of DS, Niti-S, WallFlex, and Evolution, which were all uncovered type, were used in 59, 51, and 25 patients, respectively (Supplementary Table P < 0.001). Of the 135 patients, 113 achieved a GOOSS score of 3 after DS placement, indicating the rate of clinical success was 83.7%. The type of DS did not affect the clinical outcomes.The clinical outcomes of DS placement are shown in Table The adverse events of DS placement and details of endoscopic re-intervention are shown in Table Stent occlusion due to tumor ingrowth or overgrowth occurred in 19 of 135 patients 14.1%) during the observation period. Stent patency of 19 patients with stent occlusion was 66 (5–418) days, and all patients successfully underwent endoscopic re-intervention with additional DS placement. Details of patients with stent occlusion and endoscopic re-intervention are shown in Table .1% durinTo reveal the predictive factors for improved QOL, such as an achievement of GOOSS 3 after DS placement, we compared the clinical characteristics between the patients with clinical success (GOOSS 3 after DS placement) and failure (GOOSS 0–2 after DS placement) (Supplementary Table P < 0.001), locally advanced disease , chemotherapy after DS placement , and stricture site in D3  were factors significantly associated with prolonged OS  days . OS in the chemotherapy group was significantly longer compared to the best supportive care group . In addition, OS of the patients with a D3 stricture was significantly longer than those with a D1 or D2 stricture .Figure This study demonstrated the efficacy and safety of DS placement for GOO, which resulted from pancreato-biliary and other malignancies in clinical settings in the Kyushu region of Japan. The technical and clinical success rates were high, and complications were acceptable; however, patient prognosis after DS placement was very poor, a median of 81 days. We found that a GPS of 0–1, D3 stricture, or receipt of chemotherapy after DS placement led to longer OS.14 and 9515 days, which were comparable to that of the results of the present study. The high proportion of patients with PDAC (over 60%) might have been the reason for poor prognosis in this study. However, OS after DS placement did not significantly differ between patients with and without PDAC  in our cohort. Similarly, Miyabe et al.16 reported that survival durations after DS placement in patients with pancreato-biliary and other cancers were comparable. In a larger study by Oh et al.3 (292 patients), post-stent placement survival was similar between patients with pancreatic and non-pancreatic cancer (2.7 vs. 2.4 months). A recent study from a French cancer center, including patients with various cancer types, also revealed a poor prognosis of four months after DS placement17. Although endoscopic DS placement itself is a safe procedure and tends to be the first-line treatment for malignant GOO, endoscopists should recognize that GOO is still a poor prognostic marker for patients with cancers, regardless of origin, in the era of advancement of oncological treatment.PDAC is widely recognized as a highly lethal disease. Two retrospective studies from Japan reported the median survival times after DS placement for patients with advanced pancreatic cancer of 89.516. Oh et al.3 reported that chemotherapy post-stent placement was significantly associated with better post-stent placement survival in both patients with pancreatic and non-pancreatic cancer. Clinicians should consider the induction or re-induction of chemotherapy in tolerable patients after DS placement to achieve longer OS.Given that chemotherapy was selected for tolerable patients, it was reasonable that chemotherapy after DS placement was the most favorable factor for prolonged OS. Similarly, several studies indicated chemotherapy after DS placement as a predictive factor for longer OS12 and Sugiura et al.18 reported that an NLR ≥ 5 or NLR ≥ 4 was significantly associated with poor prognosis in patients with pancreatic cancer. Although an NLR < 4.6 in our study was not significant and the optimal cut-off value of the NLR remains unknown, the NLR may be a prognostic factor for patients with DS placement. A GPS or modified GPS was reported to be a predictor for patients with stenting in other fields, such as esophageal stent19, biliary obstruction21, and obstructive colorectal cancer22; however, the role of GPS has not been clarified in patients with DS placement. To the best of our knowledge, we are the first to reveal the importance of a GPS before DS placement in patients with GOO. We should take systemic inflammatory markers, such as the GPS, into consideration when deciding on a DS placement because it is a very simple and easily assessable marker.A systemic inflammatory marker, GPS, was also a prognostic factor after DS placement in our study. Although there are few reports regarding systemic inflammation in patients who underwent DS placement, Kobayashi et al.23. However, it has not been clarified whether prognosis depends on the stricture site. Several studies demonstrated that the stricture site was not a significant prognostic factor for duration of survival or stent patency25. Jung et al.25 reported that the clinical success rate was significantly greater in patients with stenosis of the peri-pyloric region  than those of the duodenal region (second and third portions of the duodenum), although the stent patency period was not different. Theoretically, patients with a D3 stricture have less involvement of the biliary tract, which may facilitate prompt induction of chemotherapy after DS placement. These patients might be suitable candidates for DS placement. Clinical images of a representative patient who received chemotherapy after DS placement for a D3 stricture are shown in Fig. The stricture site D3 was another significant favorable factor for prolonged OS after DS placement, which was the new finding in the present study. For patients with malignant GOO, the stricture site was divided into three or four portions, D1, D2, D3, and D4, in the previous studies26, the rate of stent migration after uncovered DS placement was as low as 2.2% (4/184), which was similar with our results. We think that stent migration rarely occurs if expert endoscopists carefully perform DS placement using an uncovered stent. On the other hand, the weak point of uncovered DS is frequent stent occlusion due to the tumor ingrowth or overgrowth. Actually, 19 of 135 patients (14.1%) had stent occlusion in our study and required additional DS placement. We should take into consideration the more frequent occlusion of DS when prolonged OS is achieved due to advances of oncological treatment in the future.In this study, we performed uncovered DS placement as an initial procedure in all patients with GOO. In a recent randomized prospective study regarding malignant GOO from JapanThis study has several limitations. First, we retrospectively analyzed patients with malignant GOO who had been treated with an endoscopic DS placement. A comparative analysis of DS placement to surgical bypass was not performed in this study. A comparative analysis in future studies could give insight into the factors that make DS the more suitable or better option. Second, this study included heterogenous primary cancers, not just pancreatic cancers, and various sites of malignancies. Third, chemotherapy regimen for pancreatic cancer or biliary cancer was not consistent due to a long-term study period, which may affect clinical outcomes including OS. Although a larger study is required to validate the benefit of DS for GOO, our results have important implications regarding clinical decision-making for patients with malignant GOO.In conclusion, we demonstrated the safety and efficacy of endoscopic DS placement for patients with GOO in real clinical settings. Patients with a GPS of 0–1 and a D3 stricture who are tolerant of chemotherapy might be suitable candidates for endoscopic DS placement.Supplementary Tables.


IntroductionHypertension (HTN) is one of the most important cardiovascular risk factors. It is associated with significant complications, such as coronary artery disease, stroke, and chronic kidney disease. Awareness among hypertensive patients regarding their blood pressure (BP) is low in the Kingdom of Saudi Arabia.AimThis study aimed to evaluate the awareness of patients regarding their BP readings and to identify which aspects of HTN they needed to be informed about.Patients and methodsA descriptive cross-sectional study was conducted among hypertensive patients attending outpatient clinics at King Fahad Medical City, Riyadh, Saudi Arabia. An electronic questionnaire was used by a trained physician to collect data from patients during telephone interviews. The information included socio-demographic data , family history, compliance with medications, and BP measurements. Patients were asked to answer questions to assess their awareness of their BP readings.ResultsOf the 475 hypertensive patients included in this study, 32.7% were aged between 56 and 65 years and 60.4% were female. The proportion of patients who had knowledge of their target BP  was 74.4%. The significant independent predictors of increased knowledge about BP were a high level of education, regular measurement of BP, and having received education about a healthy lifestyle. The significant independent predictor of decreased knowledge about BP was having an acceptable or poor understanding of chronic BP.ConclusionHypertensive patients visiting the outpatient clinic at King Fahad Hospital had a good understanding of their target BP readings. Educated patients who regularly measured their BP and who received education about a healthy lifestyle tended to exhibit a higher motivation to achieve their BP targets. More research is needed to gain more insights into the knowledge of hypertensive patients and into how they manage their BP to determine the factors that influence their knowledge. Hypertension (HTN) is one of the most important cardiovascular risk factors that is associated with significant complications such as coronary artery disease, stroke, and renal failure . AwareneConsidering these important interventions, we propose evaluating the awareness of HTN among the patients and how the counseling provided by the treating physicians helped identify which area of HTN they needed to learn more about.A descriptive cross-sectional study was conducted on patients attending outpatient clinics at King Fahad Medical City, Riyadh, Saudi Arabia, during the study period of six months. A total of 475 patients were chosen to collect data on their HTN knowledge and awareness, as well as their BP measurement results during a visit. We designed questionnaires for face-to-face data collection, but as some patients cannot attend the clinic due to COVID-19 restrictions, we collected their data during telephone interviews. Verbal consent was taken from each patient before starting each interview, and those who refused the interview were excluded from our study. Both face-to-face and telephone interview data were collected by trained physicians. The information included demographics, family history, compliance with medication, and BP measurements. Patients were asked to answer questions to assess their awareness of their BP readings.Statistical analysisCategorical variables were calculated to present numbers and percentages (%). Analysis of the relationship between the knowledge about BP reading among the socio-demographic and other related characteristics of hypertensive patients was conducted using the chi-square test. The generated significant results were then gathered into a multivariate regression model to determine the significant independent predictors associated with knowledge about BP with corresponding odds ratios and a 95% confidence interval (CI). A p-value of 0.05 at 95% CI was used to indicate statistical significance. The data were analyzed using Statistical Packages for Social Sciences (SPSS) version 26 .We received survey responses from 465 hypertensive patients. Table Regarding complications and compliance with anti-hypertensive medications, Table As shown in Figure As shown in Table When evaluating the relationship between the knowledge about BP readings and the socio-demographic characteristics of the patients, we found that the proportion of patients who knew their BP readings was significantly higher among patients who were in compliance with their BP medications (p = 0.001), patients with complications due to HTN (p = 0.036), patients who had perceived good understanding about chronic BP (p < 0.001), and patients who had discussed healthy lifestyles (p < 0.001) Table . In contWe performed multivariate regression analysis to predict the influence of having knowledge about BP readings Table . Based oThe present study was conducted to determine the knowledge of hypertensive patients regarding their BP readings and to identify the factors that influence this knowledge. Our results indicate that there is satisfactory knowledge among hypertensive patients regarding their target BP readings. Nearly three-quarters 74.4%) of our patients were aware of the importance of achieving their BP targets, and 77.8% of our patients had an acceptable to good understanding of chronic HTN. Several studies have reported that patients with HTN are aware of their disease, its significance, their target BP values, the associated risks, and treatment options -4. Alsha.4% of ouIn this study, several factors were significantly associated with knowledge about BP readings, including age group, education level, time since diagnosis, regularly measuring BP, compliance with BP medications, complications due to HTN, visits to the emergency department due to HTN, level of understanding of chronic HTN, and having received education about healthy lifestyles. However, in our adjusted model, only education level, regularly measuring BP, level of understanding of chronic BP, and having received education about healthy lifestyles remained significant. Increased knowledge about BP readings was associated with a higher education level, measuring BP regularly, and receiving education about a healthy lifestyle; decreased knowledge of BP readings was associated with having an acceptable or poor understanding of chronic HTN. A large population-based cohort study done in China by Sun et al.  showed bHowever, these findings are inconsistent with those of a study by Mirzaei et al. . In theiThe advantages of having a high level of education are supported in the literature. Patients with a higher level of education are more likely to have better perspectives regarding their disease. Bakhsh et al. reported that highly educated patients demonstrated better awareness and self-management practices regarding their disease than less educated patients . A studyMost of our patients showed increased knowledge and good practices regarding their disease and its management. For example, 97.8% of the patients received medications for HTN, while compliance with HTN medications was 79.1%. Furthermore, 61.1% of patients had received education about the goal of BP measurement, and approximately 72.9% had received information about healthy lifestyles. However, the patients’ interest in enhancing their knowledge about some aspects of their disease was estimated to be lower. Only 43.4% of our patients showed interest in healthy food and sports, 27.5% showed interest in the complications of HTN, and only 22.2% showed interest in HTN treatments. In Iran, the use of prescribed anti-hypertensive medications was reported by 71.5% of patients; however, only 38.9% were able to control their BP . Of the The preferred learning resource for HTN education among our patients was face-to-face discussion (50.5%); explanatory videos were the second most preferred option 32%), and written publications were the least preferred option (16.8%). The preferred source of HTN information was social media (39.1%) followed by social gatherings (28.4%) and the doctor (12.3%). These results contrasted those of Oliveria et al., who found that the most common source of information for hypertensive patients was a physician or other healthcare provider followed by mass media (59%) and friends and relatives (30%) 2%, and w. The rolHypertensive patients who visited the outpatient clinic at King Fahad Hospital had a good understanding of their target BP readings. Being educated, regularly measuring BP, and having received education about healthy lifestyles were associated with increased motivation to achieve BP targets. Awareness campaigns are needed to educate patients with HTN about the importance of controlled BP, and the role of healthcare providers is vital in this population. More research is needed to obtain more insight into the knowledge of hypertensive patients regarding how they manage their BP and to determine the factors that influence this knowledge.


Demographic trends show an increasing number of elderly people and thus a growing need for palliative care (PC). Such care is increasingly being provided by long-term care (LTC) facilities. The present study aimed at exploring PC indicators of residents at LTC facilities belonging to a non-profit provider in Lower Saxony, Germany, in order to identify potential improvements.N = 471) were collected anonymously between March and May 2020. Based on key literature on quality indicators of PC in LTC facilities in Germany, a structured survey was developed by a multidisciplinary research team. The descriptive, comparative and inferential data analysis was conducted using the SPSS software package.A descriptive cross-sectional study was conducted, drawing on routine nursing chart data. Structural data from 16 participating LTC facilities and the care data of all residents who died in 2019 (p < .001) than did non-cancer patients. Differences emerged in the distribution of PC indicators between LTC facilities. Facilities that have more PC trained staff offered more ACP, supported by more specialized PC teams and hospice services, and had fewer hospitalizations. In addition, more volunteer hospice services were offered in urban facilities.In total, the complete records of 363 (77%) residents who died in the participating LTC facilities in 2019 were retrieved. The records reflected that 45% of the residents had been hospitalized at least once during the last 6 months of their lives, and 19% had died in hospital. Advance care planning (ACP) consultation was offered to 168 (46%) residents, and 64 (38%) declined this offer. A written advance directive was available for 47% of the residents. A specialized PC team and hospice service volunteers were involved in caring for 6% and 14% of the residents, respectively. Cancer patients received support from external services significantly more frequently (Overall, a rather positive picture of PC in participating LTC facilities in Germany emerged, although there were differences in the expression of certain indicators between facilities. ACP consultation, volunteer hospice services, and hospital admissions appeared to be superior in LTC facilities with more trained PC staff. Therefore, PC training for staff should be further promoted. Due to the ongoing sociodemographic transition the number of older and chronically ill people in the global population increased , and thuIn the German federal state of Lower Saxony, approximately 112,000 people are currently accommodated in LTC facilities , where tVarious initiatives have been undertaken, both nationally and internationally, to establish a hospice culture and to improve the administration of PC in LTC facilities , 14. In This paper presents the results of an analysis of the nursing chart data of residents who died in 2019, with respect to PC in the last phase of life. It concludes by identifying potential improvements for PC within LTC facilities in Germany.A retrospective analysis of the routine nursing chart data of the last 12 and 6 months of life of LTC facility residents who died in 2019 was conducted. All 146 LTC facilities in Lower Saxony of a particular protestant non-profit provider were invited by post to participate in the ImPAct study in December 2019, and to nominate one contact person. After 2 weeks, all facilities were asked again about their willingness to participate, via telephone. In January 2020, 18 (12%) LTC facilities agreed to participate in the study. Main reasons stated for not-participation were limited resources (38%) and involvement in other projects (33%). General structural data for the facilities and the number of deceased residents in 2019 were requested. In a second step, 491 (corresponding to the data gathered in the previous step) anonymous survey forms were sent out to the contact persons at the participating LTC facilities. These persons were invited to fill in one survey for each deceased resident (data collection period: March to May 2020). A reminder letter was sent to the participating LTC facilities in April 2020.For the anonymized data collection, the contact persons in the participating LTC facilities were asked to extract certain data into a standardized survey form. Based on key literature on quality indicators for PC in LTC facilities , 15–18 as). Group differences for metric data were calculated using T test and for ordinal data using Mann–Whitney U test. To evaluate the impact of facility  and resident characteristics  on PC variables  linear mixed effects regression models were applied. To take into account the cluster structure, the LTC facilities were included as random effects in the model. Data were analyzed using the Statistical Package for Sciences, version 26  and STATA, version 16.Quantitative data were analyzed descriptively and correlations between nominal and ordinal data were calculated with rank correlation coefficient Spearmann roh  data forms on the deceased residents. After the reminder letter additional 55 (12%) data forms were returned, so that in total 363 data forms were send back completely until May 2020 (77%).The majority of the 16 LTC facilities were located in small- to mid-sized cities Table . On averAccording to the information provided by the LTC facility contact persons, the majority of the residents were female (68%), and residents’ average age at the time of admission was 83 years. The facilities mainly accommodated residents on care grades 3 (31%), 4 (30%), 2 (22%), 5 (16%) and 1 (1%), according to the German compulsory nursing care insurance scheme. In 2019, 33% of the residents in these facilities died.p < 0.001). In total, 333 (92%) of the deceased residents had received regular visits from their next of kin (mainly their children (73%) and spouse (20%)) during their last 6 months of life.Nursing data on the 363 deceased residents revealed that the majority (71%) were female, and their average age was 87 years (SD = 8) at the time of death (Table p < 0.001).While nearly two-thirds of the deceased residents had lived in the LTC facility for more than 1 year, 28% had died within their first 6 months in the facility Table . A seconOverall, almost two-thirds of the deceased residents had suffered from multiple illnesses (three or more chronic diseases). Furthermore, the majority had been highly dependent on support in their activities of daily living during their last phase of life. At the time of death, 36% of the residents were receiving care level 5, according to the German compulsory nursing care insurance scheme (Table p < 0.000) (Table s: -0.129*).Table 0) Table . FurtherWith respect to hospitalization, 45% of residents were admitted to hospital at least once during their last 6 months of life, with an average length of stay of 8 days. Overall, 20% of the residents living in LTC facilities, died in hospital. Advance care planning (ACP) consultation was offered to 168 (46%) residents. Of these, 64 (38%) refused the offer. Health care proxies and advance directives were registered for 235 (65%) and 169 (47%) residents, respectively. Finally, 43% of the residents had a do not resuscitate (DNR) order as far as it had been documented in their nursing record, which was complied with in 96% of the cases, according to the LTC facility contact persons.s: -0.178**). There was also a weak relationship between the place of death (in the facility) and support administered from voluntary hospice services (rs: 0.129*). Finally, there were weak to moderate correlations between facilities’ number of qualified PC staff and: (1) support administered by specialized PC teams (rs: 0.123*), (2) support administered by volunteer hospice services (rs: 0.109*), (3) number of hospitalizations (rs: -0.155**) and (4) ACP consultation offers (rs: 0.536**).Residents who expressed desires concerning end-of-life care were more likely to die in the facility  and resident characteristics  influenced PC delivery. The mixed effects logistic regression Table  showed tThe present study aimed at exploring the current status of PC in LTC facilities of a non-profit provider in Lower Saxony, Germany, drawing on routine nursing care data for 363 residents who died in 2019. In summary, 45% of the residents were hospitalized in the last 6 months of life, and 20% died in hospital. 46% and 47% of residents received ACP and had an AD, respectively. 6% received specialized palliative care and 14% voluntary hospice companions.Overall, a quite positive picture of PC emerged, though the implementation of PC varied widely across the included facilities. Health insurance data show that 70% of deceased residents in German LTC facilities had at least one hospitalization in the 6 months prior to death . In our Few residents (20%) in the current sample died in hospital. Hoffmann and Allers  showed tThe legislated agreement to determine residents’ wishes in terms of ACP GVP, § 132 SGB V) by special trained ACP consultants has just been implemented in Germany since 2018. Our data show that approximately every second LTC facility resident who died in 2019 was already offered these ACP consultations. These consultations might support residents’ relatives and healthcare providers in the decision-making process and reduced hospitalization , 32. Nev SGB V byIn total, 14% of the deceased residents in the investigated LTC facilities were accompanied by volunteer hospice services. This is comparable to data from a survey of relatives of deceased residents, who reported companionship by hospice volunteers in about 13% . The datAcross the investigated LTC facilities, there were differences in the expression of surveyed PC indicators. Some studies have shown that the size and location of LTC facilities can impact the level of care provided . Our datAlthough a recent review showed only few effects of staff training on PC , our datThe present study referred to recent nursing data on PC with respect to a large sample of deceased residents at LTC facilities run by a specific non-profit provider in a single federal state of Germany; thus, the generalizability of the results to other providers or regions might be limited. In addition, only in one facility, none of the employees had a PC training. Due to the low response rate during the COVID-19 outbreak in spring 2020, a high degree of positive self-selection bias amongst the facilities must be considered.The analyzed nursing documentation did not cover all aspects of PC in the LTC facilities . Additionally, not all documented aspects were surveyed (e.g. pain assessment and management). In the analysis of the data, only selected characteristics of the LTC facilities were recorded. Thus, other possible conditioning factors were not analyzed in more detail.Overall, a rather positive picture of PC in the participating LTC facilities emerged, although there were differences in the expression of certain indicators between facilities. Measured quality indicators for PC – in particular ACP consultation, volunteer hospice services, and hospital admissions at the end of life – appeared to be superior in LTC facilities with more trained PC staff. Therefore PC training for staff should be promoted. As the results refer to only nursing documentation, the views of relevant stakeholders should also be investigated.