Activation of βARs allows rapid enhancement of myocardial function in order to fuel the muscles for running and fighting in a fight‐or‐flight response. Likewise, βARs become activated during cardiovascular disease in an attempt to counteract the restrictions of cardiac output. However, long‐term stimulation of βARs increases the likelihood of cardiac arrhythmias, adverse ventricular remodelling, decline of cardiac performance and premature death, thereby limiting the use of βAR agonists in the treatment of heart failure. Recently the endogenous Raf kinase inhibitor protein (RKIP) was found to activate βAR signalling of the heart without adverse effects. This review will summarize the current knowledge on RKIP‐driven compared to receptor‐mediated signalling in cardiomyocytes. Emphasis is given to the differential effects of RKIP on β AAVadeno‐associated virusAC6adenylyl cyclase 6βARβ‐adrenergic receptorβARKctβ‐adrenergic receptor kinase, C‐terminusCaMKII2+/calmodulin‐dependent protein kinase IICacAMPcyclic adenosine monophosphatecMyBPCcardiac myosin binding protein CEpacexchange protein directly activated by cAMPERK1/2extracellular signal‐regulated protein kinases 1 and 2GPCRG‐protein‐coupled receptorGRKG‐protein‐coupled receptor kinaseiGinhibitory G‐proteinsGstimulatory G‐proteinKOknock‐outLTCC2+ channelL‐type CaMEKmitogen‐activated protein kinase kinaseNCXsodium–calcium exchangerPDEIIIphosphodiesterase IIIPEBPphosphatidylethanolamine‐binding proteinPKAprotein kinase APKCprotein kinase CPLNphospholambanPMCA2+‐ATPasesarcolemmal CaRKIPRaf kinase inhibitor proteinRyR2ryanodine receptor 2S100A1S100 calcium binding protein A1SERCA2a2+‐ATPasesarco‐/endoplasmic reticulum CaSRsarcoplasmic reticulumTnItroponin Iet al. Heart failure occurs if cardiac output is reduced to an extent that it cannot meet the body's needs. It represents one of the leading causes of morbidity and mortality in developed countries and results from the loss and/or dysfunction of cardiomyocytes due to literally any insult to the heart, most frequently chronic arterial hypertension, myocardial infarction, aortic stenosis or infectious diseases. The activation of the sympathetic nervous system via β‐adrenergic receptors (βARs) is the most important compensatory mechanism in heart failure, acting to stabilize the hemodynamic situation by accelerating cardiac contraction and relaxation (Ponikowski 2+) are the critical intermediary that translates sympathetic activity into myofilament movement. Changes of beat‐to‐beat myocyte Ca2+ cycling are also among the hallmarks of heart failure. Further, local Ca2+ release events (Ca2+ sparks) and/or altered Ca2+ sensitivity of cardiomyocytes contribute to contractile dysfunction and increase the risk of cardiac arrhythmias in failing hearts as well as in diseases like inherited cardiomyopathy or early after myocardial infarction , speed of relaxation (positive lusitropy), atrioventricular conduction (positive dromotropy) and heart rate (positive chronotropy)  that stimulate adenylyl cyclases to produce the second messenger cyclic adenosine monophosphate (cAMP), which in turn activates the cAMP‐dependent protein kinase A (PKA). In cardiomyocytes, regulators of beat‐to‐beat Ca2+ cycling and sarcomere proteins represent major substrates of PKA. Activation of PKA causes phosphorylation of L‐type Ca2+ channels (LTCCs). This increases Ca2+ influx; phosphorylation of phospholamban (PLN), which accelerates the reuptake of Ca2+ into the sarcoplasmatic reticulum (SR); phosphorylation of ryanodine receptors 2 (RyR2), which increases SR Ca2+ release; phosphorylation of troponin I (TnI) and of cardiac myosin binding protein C (cMyBPC), which decreases myofilament Ca2+ sensitivity; and phosphorylation of titin, which reduces the sarcomeric passive stiffness , a kinase that also impacts on Ca2+ homeostasis by phosphorylation of RyR2, PLN or cMyBPC, thereby further potentiating βAR‐mediated cardiac contraction and relaxation . In line with this, the unfavourable outcome of the Ile164 polymorphism was suggested to result from the loss of β2ARs coupled to Gi and their protective effects on apoptosis  improve patients’ symptoms and significantly promote survival when applied carefully at slowly increasing dosages. Multiple studies within the last two decades have shown that β‐blockers improve survival for chronic heart failure by up to 30% , an enzyme that degrades cAMP; activation of PKA; inhibition of protein phosphatase 1, an enzyme that reduces PKA‐mediated activation of calcium cycling proteins; or activation of CaMKII , which plays an important role in diastolic Ca2+ removal. SERCA2a activity was modulated via deletion of the SERCA2a inhibitor PLN, overexpression of SERCA2a or overexpression of S100 calcium binding protein A1 (S100A1). Further, the LTCC was targeted using the Gβγ scavenger C‐terminus of the β‐adrenergic receptor kinase (βARKct), which leads to disinhibition of G‐protein (Gβγ)‐mediated inhibition of the channel  safely increased left ventricular function beyond standard heart failure therapy in a recently published phase 1/2 trial of AC6 gene transfer in heart failure patients  family, which has been characterized as a modulator of signal transduction cascades in mammalian cells and has been reviewed in detail by Trakul & Rosner , Granovset al. . PEBP/RK. et al. . This caet al. et al. et al. et al. et al. et al. et al. Even though other kinase signalling cascades such as the nuclear factor κ‐light‐chain‐enhancer of activated B‐cells (NFκB) and glycogen synthase kinase‐3β are also known to be regulated by RKIP in cultured cells, thus far only Raf‐1, MEK1 and ERK2 as well as GRK2 have been identified as direct interaction partners of RKIP of which only Raf‐1 and GRK2 have been validated under endogenous conditions 1AR–Gs signalling, which results in enhanced contraction and relaxation via increased PLN and TnI phosphorylation and subsequently increased SERCA2a activity, higher SR Ca2+ load and decreased Ca2+ sensitivity of myofilaments. Cardiac contractility of RKIP‐overexpressing mice was improved compared to control animals up to an age of at least 12–14 months; and lifespan of RKIP‐overexpressing mice under these conditions was at least as long as of non‐transgenic mice 1AR–Gs signalling, RKIP‐stimulated hearts are still able to respond adequately to physiological stress situations because the size of the dobutamine response of RKIP‐overexpressing and wild‐type hearts is similar. This moderate or submaximal activation may play an important role for the observed reduction of cardiomyocyte apoptosis, interstitial fibrosis, brain natriuretic peptide and collagen expression in RKIP‐overexpressing mice compared to wild‐type controls and the overall well‐tolerated positive inotropic phenotype of RKIP‐overexpressing mice 1AR–Gs‐signalling that stimulates the activity of both PKA and CaMKII, RKIP activates β2AR–Gi in mouse hearts. The simultaneous activation of β2AR–Gi within the transverse (t)‐tubular region prevents the adverse effects of mere β1AR–Gs, such as diastolic Ca2+ leak and cardiac arrhythmia due to hyperphosphorylation and subsequent activation of the RyR2 or hyperphosphorylation of the LTCC. These RKIP effects appear to be mediated by β2AR–Gi signalling since this protection is absent in RKIP‐overexpressing mice lacking β2ARs and in the presence of the Gi inhibitor pertussis toxin et al. et al. RKIP was found to inhibit βAR downregulation and thereby secures sustained positive inotropy, which is not achieved by direct agonist‐mediated βAR stimulation (Lorenz (5)−/−) dramatically increased it. This effect is β2AR dependent since the protection from apoptosis is absent in RKIP‐transgenic mice lacking the β2AR. Interestingly, β2AR–Gi is known to stimulate the kinase Akt, which in turn mediates anti‐apoptotic effects  while RKIP deficiency exaggerated heart failure under these conditions. AAV9‐mediated gene transfer protected wild‐type and RKIP knockout mice from transverse aortic constriction‐induced heart failure (Schmid Ser153), but in the absence of Ser153 phosphorylation it acts as a Raf‐1 inhibitor. In the heart, Raf–MEK–ERK1/2 signalling promotes cell survival  but rather circumvent activation of the RyR2  or even protect from RyR2 sensitization   that counteracts several maladaptive β1AR effects such as RyR2 sensitization, diastolic Ca2+ leaks and arrhythmia as well as apoptosis and fibrosis. Indeed, ‘sole’ β1AR activation as provided in RKIP transgenic mice lacking the β2AR (β2KO) increased cardiac contractility, but also reduced overall survival of ageing RKIP transgenic mice (RKIP/β2KO) compared to β2KO controls , 1% by the sarcolemmal Ca2+‐ATPase (PMCA) and 1% by the mitochondrial Ca2+ uniporter) , the SERCA2a regulator PLN plays a pivotal role in modulating myocyte Ca2+ distribution and kinetics. PLN inhibits SERCA2a, thereby attenuating the rate of Ca2+ transport to the SR. Phosphorylation of PLN by PKA at serine 16 can almost fully relieve this inhibitory effect leading to a pronounced acceleration of SR Ca2+ uptake. As Ca2+ is sequestered by the SR, in the sarcomeres TnI inhibition of actin–myosin interactions is re‐established and myocytes relax  Bers, . Since S2+ cycling. Although the causes of heart failure can vary widely, e.g. myocardial infarction, arterial hypertension, infections or genetic defects, the pattern of abnormal Ca2+ metabolism is relatively uniform , but primarily due to reduced SERCA2a activity. Depression of the Ca2+ pump results from reduced SERCA2a expression in failing hearts, whereas PLN levels remain stable leading to a reduced SERCA/PLN ratio  and threonine 17 (CaMKII site) leading to efficient release of PLN from SERCA2a and subsequent activation of SERCA2a. The RKIP‐induced increase in Ca2+ reuptake during diastole may further be supported by an accelerated Ca2+ release from the myofilaments mediated by enhanced TnI phosphorylation at the serine residues 23 and 24. Further, via GRK inhibition, RKIP prevents βAR desensitization and βAR degradation in a heart under chronic sympathetic stress, which subsequently secures efficient and continuous Ca2+ cycling. In addition, RKIP overexpression is able to prevent a loss of SERCA2a expression in a failing mouse heart, which in turn also ensures effective Ca2+ cycling in cardiomyocytes.RKIP seems to provide a promising approach for the restoration of depressed Ca2+, the enhanced Ca2+ load would explain the hypercontractile phenotype of RKIP‐overexpressing hearts and the improved cardiac function in a mouse model of heart failure due to chronic pressure overload  and both early and delayed afterdepolarizations that trigger aberrant electrical activity and arrhythmias of the heart  accelerates cytosolic Ca2+ elimination by PKA‐dependent phosphorylation of PLN and (3) increases SR Ca2+ filling and therefore the size of the Ca2+ transients. Finally, RKIP overexpression prevented morphological and functional maladaptation of the heart in mice subjected to long‐term pressure overload. Future studies will show if these beneficial effects hold true for the rescue of independent models of heart failure.Pharmacological and gene therapeutic studies are aimed at fixing the Cas signalling/β1AR leading to functional recovery of the heart and (2) the protection of the heart under sympathetic stress from exaggerated β1AR downstream signalling including protection from apoptosis and pro‐arrhythmic adverse effects via β2AR activation. This approach promises a new therapeutic strategy to achieve well‐tolerated long‐term increases in cardiac contractility. RKIP comprises several favourable characteristic effects on calcium cycling, calcium sensitivity, G‐protein recruitment to βARs and a physiological extent or range of βAR activation and has proven protective in murine heart failure. Future studies will further unravel the signalling network induced by RKIP that is responsible for the well‐tolerated mode of βAR activation and evaluate its therapeutic efficacy in various disease entities.RKIP is an endogenous protein that exhibits a combination of favourable effects for heart failure patients: (1) the gain/increase of cardiac contractile efficiency by the activation of GThe authors have no competing interests.All authors have approved the final version of the manuscript and agreed to be accountable for all aspects of the work. All persons designated as authors qualify for authorship, and all those who qualify for authorship are listed.This work was supported by Deutsche Forschungsgemeinschaft  and SFB 1116 (TPA02 to J.P.S.)), by Bundesministerium für Bildung und Forschung ) and by the Ministry for Innovation, Science and Research of the Federal State of North Rhine‐Westphalia (K.L.). A PhD position was awarded to T.B. by the Elite Network of Bavaria within the IDK ‘receptor dynamics’.


KEAP1 loss modulates sensitivity to kinase targeted therapy in lung cancer. Published 1, February 2017In the published article, there is an error in the inline table for sgRNA sequences—the “Target sequence” for sgKEAP1-4is shown as “GAGGACACACTTCTCGCCCA”, which is a duplicate of the target sequence for sgKEAP1-3. The correct “Target sequence” for sgKEAP1-4is ACTGGGCGGCCGGTGCATCC.The Corrected Table is shown here:sgRNA SequencesThe originally published Table is also shown for reference:sgRNA SequencesThe article has been corrected accordingly.


The adsorbent dosage and adsorption time of the obtained CaCO3 MSs were investigated. The results suggest that these CaCO3 MSs can rapidly and efficiently remove 99–100% of anionic dyes within the first 2 min. The obtained CaCO3 MSs have a high Brunauer–Emmett–Teller surface area (211.77 m2 g−1). In addition, the maximum adsorption capacity of the obtained CaCO3 MSs towards Congo red was 99.6 mg g−1. We also found that the core–shell structured CaCO3 MSs have a high recycling capability for removing dyes from water. Our results demonstrate that the prepared core–shell structured CaCO3 MSs can be used as an ideal, rapid, efficient and recyclable adsorbent to remove dyes from aqueous solution.Core–shell structured CaCO Howev3 microspheres (MSs) can be easily separated from the liquid phase through a simple sedimentation method in a short time, benefiting from their high density and micrometre size; thus, they can be ideally used in dye adsorption according to the solid–liquid separation property [3 MSs suitable reusable adsorbents. In this paper, we propose a strategy of preparing core–shell structured CaCO3 MSs as economical and recyclable adsorbents to remove organic dyes from water.Calcium carbonate is a low-cost and abundant material in nature . CaCO3 mproperty . Core–shproperty ,23. Besi3 MSs in the presence of hesperidin (Hesp). Hesp has been reported to regulate the formation of CaCO3 microspheres in our former work [4)2CO3 to NaHCO3. This change can provide the advantage of producing a core–shell structure in the products. The detailed steps are illustrated in 2+ and Hesp, which will form Ca–Hesp complexes due to the interactions of the Ca2+ and –OH groups on Hesp molecules [3 solution is added into the aqueous solution drop by drop. Then, 2+ from Ca–Hesp complexes, which provide sites for further nucleation. When heating the reaction system, the outer layer of the 3 (as the shell of CaCO3 MSs) because of the instability of 3 diffusing into the system reacts with 3 MSs. Finally, after aging for a certain time, the core–shell structured CaCO3 MSs are obtained.We use a facile, one-pot method to synthesize core–shell structured CaCOmer work ; howeverolecules . Subsequ3 MSs, as illustrated in 3 MSs can be considered as easily separated, high-efficiency and recyclable adsorbent for removal of dyes.To investigate the adsorption properties of obtained core--shell structured CaCO2.2.1.2 , NaHCO3  and NH3·H2O  were purchased from Sinopharm Chemical Regent Co. Ltd . Coomassie brilliant blue G-250 (CBB), Congo red (CR), Alcian blue (AB) and methylene blue (MB) were purchased from Sigma Aldrich. Triply distilled deionized water was used during all the applications.Hesperidin and ammonia  were purchased from Sigma Chemical Co. . CaCl2.2.3 MSs were synthesized by a facile, one-pot method. Firstly, 0.4% (wt %) Hesp solution was prepared by alkaline aqueous solution . Then, CaCl2 , NaHCO3  and the prepared Hesp solution (5 ml) were added into a beaker (150 ml), into which 80 ml of water was further added. The mixture was vortex-stirred  to obtain a homogeneous solution. After that, the solution was heated to 65°C and kept for 20 min. The beaker and 100 ml of ammonia (in another beaker) were placed in a closed desiccator for 24 h at room temperature. By NH3 diffusing and dissolving in the solution, the mineralization of CaCO3 MSs was initiated. The products were collected by centrifugation, and rinsed with deionized water several times. Finally, the obtained products were dried at 70°C for further analysis.The core–shell structured CaCO2.3.3 MSs were investigated by scanning electron microscopy  and transmission electron microscopy . The composition of the CaCO3 MSs was identified by using Fourier transform infrared (FTIR) spectroscopy  in the range of 4000 to 400 cm−1 with the KBr disc method. The as-prepared CaCO3 MSs were examined with powder X-ray diffraction analysis  with Cu Kα radiation to obtain the crystallographic structure of the MSs. N2 adsorption–desorption measurements were performed on a ASAP-2460 instrument with the MicroActive software , using Brunauer–Emmett–Teller (BET) calculations for surface area and Barrett–Joyner–Halenda calculations for pore size distribution.The morphologies of the obtained CaCO3 MSs were studied by a UV--visible absorption spectrophotometer (PerkinElmer Lambda 605S UV/Vis spectrometer). The dye solution was centrifuged; then, the supernatant was analysed to get absorbance by the UV--visible spectrometer at each maximum absorption wavelength (CBB (585 nm), CR (498 nm), AB (600 nm) and MB (664 nm)).The adsorption experiments of CBB, CR, AB and MB from an aqueous medium on the core–shell structured CaCO2.4.−1), CR (500 mg l−1), AB (500 mg l−1) and MB (200 mg l−1) from water by core–shell structured CaCO3 MSs can be described briefly as follows.The adsorption of CBB , 0–50 mg (CR), 0–200 mg (AB) and 0–300 mg (MB) for a 10 ml sample bottle containing 4 ml of dye solution. After a given adsorption time, the mixture was centrifuged, and then the supernatant was analysed to obtain the absorbance with the UV--visible spectrometer at each maximum absorption wavelength.The effect of the adsorbent dosage (AD) on the adsorption process was investigated by adding different dosages of CaCO3 MSs for anionic dyes (CBB and CR) has already reached approximately 100% when the AD increases to 20 mg. Therefore, the adsorbent dosage of 20 mg (for CBB and CR) was used to determine the adsorption time. To determine the adsorption time of AB and MB, the adsorbent dosage was set as 100 mg and 200 mg , respectively.According to the experimental results listed in this paper, the adsorption efficiency of CaCO3 cubic microcrystals were prepared and used as dye adsorbent in the contrast experiments.CaCOTo investigate the adsorption efficiency in the above experiments, we adopt a similar calibration curve method based on UV--visible spectroscopy as reported in our previous work ,25.qe) was calculated according to the following equation:C0 and Ce are initial and equilibrium dye concentrations, respectively (mg l−1), V is the solution volume (l) and m is the adsorbent dosage of CaCO3 MSs (g).The equilibrium adsorption capacity (2.5.3 MSs were separated (from the dye solution), dried and burned at 450°C for 2 h to desorb the dyes by using a muffle furnace. Then, those calcinated CaCO3 MSs were reused to adsorb dyes according to the previous experiment steps. To investigate the recyclability of those core–shell structured CaCO3 MSs, such an ‘adsorption--calcination (desorption)--adsorption’ cycle was carried out five times in each group.The recyclability of the adsorbent is very important. After dye adsorption, the CaCO3.a) clearly shows that the obtained CaCO3 crystals are MSs (3–5 µm in diameter) with rough surfaces. The inset image in figure 2a shows a single CaCO3 MS with a broken surface. It is obvious that this CaCO3 MS has a thin shell which surrounds the inner core. The detailed surface features of the CaCO3 MS are shown in figure 2b. It is clear that the porous surface of such a MS is composed of units of numerous small particles. The TEM image in figure 2c further confirms the core–shell structure of the obtained products. It clearly shows that the CaCO3 MS has a thin, porous and loose shell, and a condensed core. The magnified TEM image (figure 2d) provides the detailed structure of the shell shown in figure 2c. It is the aggregate of many spherical nanocrystals with an average size of approximately 30 nm in diameter. Owing to the hierarchical core–shell structure, these CaCO3 MSs are endowed with a large surface area. Thus, BET measurements were carried out to study the porosity and pore size distribution of the MS samples. A BET surface area of 211.77 m2 g−1 is achieved for CaCO3 MSs with an average pore size of 7.8 nm . These data suggest that the CaCO3 MSs can offer lots of adsorption sites for organic dye molecules.The SEM image a clearlya) located at 712, 876 cm−1  and 745 cm−1 (ascribed to characteristic absorption peaks of vaterite) indicate that these core–shell structured CaCO3 MSs are composed of both calcite and vaterite [figure 3b further proved the polycrystalline property of the CaCO3 MSs. The reflections at 2θ = 21.1, 29.6, 36.0, 39.5, 43.3, 47.2, 47.8 48.6 and 65.2° are attributable to planes of calcite (JCPDS card no. 83-0578), while reflections at 23.1, 25.1, 27.3, 32.9, 43.9, 50.3 and 55.8° are attributable to planes of vaterite (JCPDS card no. 72-0506). Rao's equation is adopted to calculate the relative fractions of vaterite (fv) and calcite in the crystalline phase according to the literature [3 microspheres are 76.01% and 23.99%, respectively.The absorption peaks . Figure 4a shows that the increase in the AD of CaCO3 MSs will decrease the absorbance at 585 nm (maximum absorption peak of CBB) gradually. Moreover, these absorption curves tend to be more flat on increasing the AD to 10 mg. When the AD reaches 20 mg, it can be found that nearly all (99.57 wt%) the CBB dye has successfully been adsorbed by the CaCO3 MSs. The insets in figure 4a show the images of the CBB solution  and the supernatant after adsorption by 20 mg of CaCO3 MSs (right image). It is obvious that the blue colour of the CBB solution has faded in the supernatant. Both the disappearance of the absorption peak and the fading of the colour indicate that the core–shell structured CaCO3 MSs have strong adsorption capability for CBB. From the adsorption curves and insets shown in figure 4b, it can be found that the adsorption of CR by the CaCO3 MSs is similar to that of CBB in figure 4a. When the AD reaches 20 mg, the added CaCO3 MSs can strongly adsorb almost all the CR dye (99.60 wt%) from the solution. Figure 4c indicates that the CaCO3 MSs present similar adsorption behaviour in AB solution as in CBB and CR solutions. The difference is that a larger amount of CaCO3 MSs (200 mg) than 50 mg is needed to adsorb 99.79 wt% of AB from the solution. However, the adsorption of CaCO3 in the MB solution is much different from that of the other three dyes (figure 4d). By increasing the added amount of CaCO3 MSs from 0 to 200 mg, the absorbance at 664 nm (maximum absorption peak of MB) is decreased gradually. However, when the adsorbent dosage is further increased from 250 mg to 300 mg, such decrease in absorbance is not as obvious as before. The inset in figure 4d indicates that the blue colour of the MB solution has not faded thoroughly in the supernatant after being adsorbed by 300 mg of CaCO3 MSs; 54.83 wt% of MB molecules are still left in the supernatant.3 MSs present different adsorption capacities for CBB, CR, AB and MB under optimal adsorbent dosages. 3 MSs in the solutions of the four dyes. It is obvious that CaCO3 MSs can completely remove CBB or CR molecules very rapidly . For AB, CaCO3 MSs need a long time  to adsorb almost all dye molecules. Figure 5d reveals that CaCO3 MSs can remove about 76.61 wt % MB from water after a quite long AT of 18 days.The above results  demonstr3 MSs can efficiently adsorb both CBB and CR as quickly as 2 min. For AB molecules, CaCO3 MSs can also completely remove them, but the AT is 28 h. For MB, CaCO3 MSs cannot efficiently remove all dye molecules, even with a given AT of more than half a month. The above difference may be ascribed to the chemical structure of the four dyes. As illustrated in 3 MSs. This feature ensures that CBB and CR have a strong combination with the CaCO3 MSs. Thus, CaCO3 MSs can adsorb CBB and CR efficiently and rapidly. With regard to AB and MB , they are cationic dyes with tertiary ammonium and quaternary ammonium groups. Those tertiary ammonium groups will bind the Ca2+ of the CaCO3 MSs. However, positively charged quaternary ammonium groups will repel the Ca2+ on the CaCO3 MSs. For AB, it has more tertiary ammonium groups (12) than quaternary ammonium groups (4). Thus, CaCO3 MSs can efficiently adsorb AB molecules due to the tertiary ammonium groups. The AT is quite long (28 h) because of the exclusion between quaternary ammonium groups and the Ca2+ ions. With regard to MB, its molecular size is much smaller than AB, so the exclusion between quaternary ammonium groups and the Ca2+ ions is stronger than that of AB. Therefore, the CaCO3 MSs only remove about 76.61 wt% MB from water after a quite long AT of 18 days.The results in figures B and MB c,d, theya). Figure 6b further directly shows the adsorption and desorption of dyes by the CaCO3 MSs in the recycling experiments. According to the SEM image  and BET data  of these CaCO3 MSs, which have been used for five recycling experiments, it is clear that these CaCO3 MSs maintain their original structure well after five recycling experiments. This indicates the obtained core–shell CaCO3 MSs are stable in the recycling experiments. Electronic supplementary material, figure S4, shows that the BET surface area of CaCO3 MSs after five cycles has no obvious change.The recycling experiments were performed for five cycles (adsorption–desorption) and the results are depicted in figure 63 MSs are stable in the recycling experiments and maintain a high removal efficiency for dyes.Furthermore, it was found that the removal efficiency of dyes has declined slightly to 93.86% for CBB, 95.63% for CR and 92.40% for AB after the 10th cycle. This suggests that the obtained CaCOa) reveals that the morphology of the calcite materials is that of smooth cubic microcrystals. The adsorption of dyes by CaCO3 materials could be attributed to the electrostatic interaction between Ca2+ and organic dye molecules. Compared to the smooth, cubic calcite microcrystals, the core–shell structured CaCO3 MSs have a much larger surface area which can provide more adsorption sites (Ca2+). Therefore, the removal of dyes by core–shell CaCO3 MSs from aqueous solution is a more rapid and efficient process (figure 7b–e) than that by using cubic CaCO3 materials as adsorbents.We use calcite microcrystals as adsorbent in the contrast experiment of dye adsorption . The SEMfigure 7qe) for Congo red in this paper and reported results is presented in 3 MSs is larger (99.6 mg g−1) and the adsorption time is remarkably faster (2 min) than for those materials reported previously [−1, and the adsorption time for the equilibrium is 200 min [et al. reported that the adsorption capacity of mesoporous Fe2O3 is 53 mg g−1, and the adsorption time for the equilibrium is 120 min [3 MSs can be used as a rapid and efficient adsorbent to remove anionic dyes from aqueous solution.A comparison of the adsorption capacity (eviously –32. For  200 min . Yu et a 120 min . Therefo4.3 MSs by a facile, one-pot method at room temperature. The results suggest that these CaCO3 MSs can rapidly and efficiently remove 99–100% of CBB and CR dyes within 2 min. We also found that these core–shell structured CaCO3 MSs have a high recycling capability for removing dyes from water. Our results demonstrate that the obtained core–shell structured CaCO3 MSs can be used as an ideal, rapid, efficient and recyclable adsorbent to remove dyes from aqueous solution.In this work, we prepared core–shell structured CaCO


Highly sensitive hydrogen detection at room temperature can be realized by employing solution‐processed MoS2 nanosheet–Pd nanoparticle composite. A MoS2–Pd composite exhibits greater sensing performance than its graphene counterpart, indicating that solvent exfoliated MoS2 holds great promise for inexpensive and scalable fabrication of highly sensitive chemical sensors. Hydrogen, a clean and abundant energy source, has been utilized in fuel cells to generate electricity with the aim of reducing the dependence on fossil fuels. However, hydrogen is a colorless, odorless, tasteless, flammable, and explosive gas, which arises some safety concerns. For the safe implementation of fuel cells, hydrogen leaks have to be detected before hydrogen concentration reaches a hazardous level.2 and NH3.2D materials have drawn tremendous attention in recent years due to their novel and unique electronic, optical, and mechanical properties.2) has been explored for electronic applications due to its sizable band gap , which enables its conductivity to be modulated by a gate voltage.2 has a layered structure, where each layer consists of covalently bonded Mo–S atoms and the neighboring layers attach each other by van der Waals forces.2 can be obtained by mechanical or chemical exfoliation of bulk MoS2 or can be grown by Chemical Vapor Deposition (CVD).et al. have demonstrated mechanically exfoliated single layer MoS2 flake as a chemical sensor, in which monolayer MoS2 shows a strong response to electron donors (triethylamine) and a lower response to electron acceptors (acetone) with detection limits of 10 ppb (parts per billion) and 500 ppm (parts per million), respectively, attributed to the n‐type nature of MoS2.2 films have also been investigated for the gas sensing and a strong response was found towards NH3 with a detection limit of 300 ppb.2, high temperature growth conditions (750–1000 °C)Recently, molybdenum disulfide  and results in MoS2 nanosheets with traces of lithium particles, which degrades the MoS2 semiconducting properties.2 nanosheets, in which exfoliation takes place by ultrasonication of bulk MoS2 in suitable solvents such as N‐methyl‐pyrrolidone (NMP) or isopropanol whose surface tension is in the range of 30–40 mJ m−2, which facilitates the exfoliation process.Chemical exfoliation of MoS2 nanosheet–Pd nanoparticle composite for H2 sensing at room temperature, in which MoS2–Pd composite show remarkable electrical response towards H2 with excellent response and recovery times. A few‐layers MoS2 nanosheets can be produced by a facile solvent exfoliation method and the MoS2–Pd composite can be fabricated by simply drop casting of MoS2–PdCl2 solution and subsequent annealing process. The effect of annealing time on H2 sensing performance of MoS2–Pd composite is investigated. The sensing mechanism is studied by transport measurements of MoS2 nanosheets and MoS2–Pd composite by fabricating field effect transistor (FET) devices. We also compare the H2 sensing performance of MoS2–Pd composite with graphene–Pd composite, fabricated in a similar fashion, revealing that MoS2–Pd exhibits much higher sensor response with shorter response and recovery times and indicating that 2D MoS2 is a promising candidate for highly sensitive room temperature gas detection.In this work, we present solution‐processed MoS2–Pd composite was prepared by drop casting of MoS2–PdCl2 solution . The optical image of sensor device is shown in Figure 2–Pd composite film, in which MoS2–Pd composite forms a continuous film (around 500 nm thick) in a self‐assembled manner. From the top‐view SEM image  measurements and thickness analysis of the MoS2 nanosheets dispersed on a Si substrate were carried out. We measured the thickness of nine MoS2 nanosheets, in which we found that the thickness of the nanosheets range from 2.2 to 25.8 nm, with the majority of them having a thickness less than 10 nm. By considering the thickness of the single layer MoS2 being 0.65 nm, the number of layers is estimated to range from 3 to 40 . Figure 2–Pd composite, in which Pd NPs (20–100 nm diameter) are sandwiched by MoS2 nanosheets.MoSon Figure1a on SFigures2 powder, MoS2 nanosheets, and MoS2–Pd composite. XRD pattern of bulk MoS2 powder shows the main peaks of molybdenite‐2H, in which a strong peak is observed at 2θ ≈ 14.4o (002), indicating that MoS2 powder is highly crystalline.2 nanosheets and MoS2–Pd composite also showed the (002) peaks with smaller intensities, indicating that MoS2 is highly exfoliated after ultrasonication.2–Pd composite, which can be attributed to the possibility that MoS2 nanosheets are precluded from restacking by Pd NPs. To further analyze MoS2, Raman spectroscopy measurements were performed X‐ray diffraction (XRD) analyses  flow rate at room temperature. In our measurements, the effect of N2 on sensor response is strictly eliminated by flowing N2 prior to H2 until the sensor response is stabilized. The MoS2 nanosheets and MoS2–Pd composite show a strong response to N2, which could be explained by the fact that O2 molecules are pushed outside of the chamber by N2 flow, in which p‐doping effect of O2 vanishes. O2 adsorption is known to lead significant hole doping in graphene,2. The sensor response is defined as R1/R2, where R1 and R2 are the resistance of the sensor device in N2 and H2, respectively. Figure2 nanosheets and MoS2–Pd composite to 50 000 ppm of H2, in which MoS2 nanosheets do not show any significant response to H2 exposure  while MoS2–Pd composite shows a strong response. Pd NPs serve as the sensing material, where the work function of Pd shifts upon H2 exposure due to the formation of PdHx compounds.2 molecules can dissociate on the surface of Pd and diffuse into the Pd lattice changing its work function.2 is altered by changing the overall resistance of the device. The role of 2D MoS2 is crucial since it serves as a platform for the attachment of the Pd NPs and provides high surface‐to‐volume‐ratio and low charge carrier density in the background due to its semiconducting nature, which makes it highly sensitive to H2 exposure. The resistance of MoS2–Pd composite device exhibits a sharp decrease with H2 exposure followed by saturation, with the sensor response being about 10, as well as the sensor shows complete recovery in air without any heating or UV irradiation. Desorption of hydrogen atoms from Pd takes place in the presence of O2 by forming H2O,2–Pd composite sensor device has response and recovery times of 40 and 83 s, respectively. I–V measurements were performed before and after H2 exposure  of the samples show that annealing changes the morphology of the film into a more spaced structure, which helps the recovery of the sensors. On the other hand, reduced sensor response could be explained by the fact that annealing turns MoS2 nanosheets into a more agglomerated structure resulting in a decrease in the number of Pd NPs which contact to MoS2 nanosheets.The effect of annealing time on the sensor characteristics of MoS2–Pd composite to ammonia, ethanol and acetone. As shown in Figure 2–Pd composite has a little cross‐sensitivity to these gases.We also investigated the cross‐sensitivity of MoS2 , in which graphene–Pd composite  shows a sensor response of only 1.34 with a response time of 102 s and incomplete recovery in 30 min. Unlike MoS2–Pd, the resistance of graphene–Pd composite increases with H2 exposure indicating that graphene–Pd composite are initially p‐doped and the reduction in the work function of Pd upon H2 exposure leads to partial depletion of holes in graphene increasing its resistance. It is clearly seen that MoS2–Pd composite exhibits superior H2 sensing performance than its graphene counterpart indicating that 2D MoS2 is more promising for room temperature hydrogen detection.As a comparison, we fabricated graphene–Pd composite sensor and measured its electrical response to 50 000 ppm of H2–Pd composite, transport measurements were carried out by fabricating FET devices. Figure2 nanosheets and MoS2–Pd composite, in which MoS2 nanosheets and MoS2–Pd composite both show n‐type transport behavior with a large shift to the positive side in threshold voltage for MoS2–Pd composite. This indicates Pd NPs have a p‐doping effect on MoS2 causing partial depletion of electrons. Based on these results, we believe that work function of Pd is higher than that of MoS2 before H2 exposure, which is consistent with the reported work function values of Pd (5.1–5.6 eV)2 (4.3–5.2 eV).2 exposure, work function of Pd decreases significantly resulting in a recovery of depleted electrons in MoS2, which in turn reduces the overall resistance.In order to elucidate the sensing mechanism of MoS2 at room temperature by employing solution‐processed MoS2 nanosheet–Pd nanoparticle composite, which can be readily fabricated by a facile solvent exfoliation and drop casting method. In particular, MoS2–Pd composite sensor exhibits a sensor response of around 10 toward 50 000 ppm H2 with a response and recovery time of 40 and 83 s, respectively. Pd NPs enable sensitivity toward H2 based on work function modulation of Pd providing high sensitivity, fast response, and recovery. Recovery time can be further decreased down to 28 s by increasing the annealing time. Furthermore, the sensing performance of MoS2–Pd was compared with graphene–Pd composite film, in which MoS2–Pd outperforms graphene–Pd composite film. These results indicate that chemically exfoliated MoS2 holds a great potential for the inexpensive and scalable fabrication of high sensitivity chemical sensors.In summary, we demonstrated highly sensitive detection of HMaterials: Bulk MoS2 powder (5 μm powder size), NMP, and palladium chloride (PdCl2) were purchased from Sigma Aldrich. Bulk graphite flakes were purchased from Graphene Supermarket.2–PdCl2 and Graphene–PdCl2 SolutionsPreparation of MoS: A 400 mg bulk MoS2 powder was mixed with 80 mL NMP and then the mixture was probe sonicated (750 W and 80% amplitude) in an ice bath for 2 h to exfoliate bulk MoS2. The resultant solution was then centrifuged at 1500 rpm for 45 min to remove any remaining bulk particles. After that, NMP was evaporated in a vacuum oven followed by redispersion of MoS2 nanosheets in deionized water with a concentration of 1.5 mg mL−1. MoS2–PdCl2 solution was prepared by adding 30 mg PdCl2 into 20 mL of MoS2–water solution and a subsequent sonication for 30 min. Graphene–PdCl2 solution was prepared by following the same procedure.Fabrication of Hydrogen Sensors: A 0.5 mL of prepared MoS2–PdCl2 and graphene‐PdCl2 solution was dropped on SiO2‐coated Si substrates, followed by baking on a hot plate at 100 °C until the solution is dried. The resultant film was then annealed in forming gas atmosphere at 400 °C to reduce PdCl2 and remove any remaining NMP. In order to fabricate the contacts for sensing measurements a piece of Teflon tape was used as a mask to define the channel (2 mm channel length and 1 cm width) and subsequent sputter deposition of Ti/Au (10/150 nm) was performed. For the fabrication of MoS2 nanosheet sensors, MoS2 nanosheets which were dispersed in ethanol was spin coated on SiO2‐coated Si substrate and then photolithography and following deposition of Ti/Au (10/150 nm) was performed to fabricate the finger electrodes.Characterization: XRD measurements were conducted by a Bruker D2 Phaser X‐ray diffractometer (XRD) with Cu Kα (λ = 0.154 nm) as the radiation source. Raman spectroscopy measurements were carried out by a Renishaw raman spectrometer at 514 nm. AFM measurements were performed with a Digital Instruments 3100 microscope under tapping mode.Sensing Measurements: H2 (50 000 ppm) in N2 was used as a starting gas and it was diluted with N2 to the desired concentrations by using mass flow controllers. For the measurements, target gas was flowed with 200 sccm flow rate through a small glass chamber (10 cm3 volume), where the sensor device is mounted and the resistance was recorded by Keithley multimeter (2100). For ammonia sensing measurements, 50 ppm ammonia gas in N2 was used. For ethanol and acetone sensing measurements, the desired amount of liquid acetone and ethanol  were evaporated in a closed chamber, in which the concentrations of the solvents correspond to 50 000 ppm. For the recovery of the sensors, air was introduced into the chamber.Fabrication of FET Devices and Transport Measurements: MoS2 nanosheets and MoS2 nanosheet‐PdCl2 dispersed in ethanol were spin coated on a SiO2 (300 nm thick) coated Si (high doped) substrate. A subsequent annealing process at 400 °C in forming gas environment was performed in order to reduce PdCl2. Source and drain electrodes were fabricated by photolithography and subsequent evaporation of Ti/Au (10/150 nm). Transport measurements were conducted by B1500 Agilent semiconductor device analyzer.As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re‐organized for online delivery, but are not copy‐edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors.SupplementaryClick here for additional data file.


An invariant bulk thermal conductivity of about 0.3 W m−1 K−1 gives rise to a thermoelectric Figure of merit ZT ∼ 10−4 that remains unaltered for an insulator content of more than 60 wt%. Free‐standing, mechanically robust tapes illustrate the versatility of the developed dopant:semiconductor:insulator ternary blends.Poly(ethylene oxide) is demonstrated to be a suitable matrix polymer for the solution‐doped conjugated polymer poly(3‐hexylthiophene). The polarity of the insulator combined with carefully chosen processing conditions permits the fabrication of tens of micrometer‐thick films that feature a fine distribution of the F4TCNQ dopant:semiconductor complex. Changes in electrical conductivity from 0.1 to 0.3 S cm A number of printing and coating techniques can be employed to create the up to millimeter‐thick structures that are needed for thermoelectric applications. The use of polymeric materials is desirable since they permit to adjust the solution viscosity that is required for a particular processing method.The most promising approach to enhance the rheological and mechanical properties of an organic semiconductor is blending with commodity polymers, for which a wide range of molecular weights is readily available. Blends of an organic semiconductor and insulating polymer have been successfully employed for a range of opto‐electronic devices including field‐effect transistors (FETs)ZT = σα2T/κ ∼ 10−4, where α is the Seebeck coefficient, T is the absolute temperature, and σ and κ are the electrical and thermal conductivity, respectively. One approach to further tune the thermoelectric properties of polymer semiconductor:insulator blends is the addition of a molecular dopant such as 2,3,5,6‐tetrafluoro‐7,7,8,8‐tetracyanoquinodimethane (F4TCNQ), which has been widely studied in conjunction with polythiophenesSo far the use of polymer semiconductor:insulator blends for thermoelectrics has only received limited interest. Recently, Lu et al. examined the thermoelectric properties of poly(3‐butyltiophene):polystyrene (P3BT:PS) blends.In this work, we explore the use of semi‐crystalline poly(ethylene oxide) (PEO) as the matrix polymer in thermoelectric polymer semiconductor:insulator blends. PEO is likely to provide better compatibility with F4TCNQ as well as the conjugated polymer:dopant ion pair due to its higher polarity. We chose to work with the semi‐crystalline conjugated polymer poly(3‐hexylthiophene) (P3HT) because of its good solubility in organic solvents as well as the extensive literature on both doping of P3HT with F4TCNQ2FigureIn a first set of experiments we explored different processing schemes in order to identify a method that permits the fabrication of homogeneous, F4TCNQ‐doped P3HT:PEO films Figure1. Dopi2 . Encouraged by the homogeneous appearance of films drop‐cast at 110 °C we chose to focus all remaining experiments on samples processed according to the scheme detailed in Figure It is well established that processing of P3HT and F4TCNQ from the same solution is strongly affected by the temperature. One reason is the poor solubility of F4TCNQ in nonpolar organic solvents, which requires temperatures above 80 °C. Moreover, Duong et al. have shown that P3HT and F4TCNQ aggregate at room temperature but dissociate at e.g., 80 °C.−1 upon doping  of spin‐coated thin films allowed us to elucidate the impact of F4TCNQ doping on the solid‐state structure of both P3HT and PEO. GIWAXS diffractograms indicate that the out‐of‐plane 100 diffraction of neat P3HT as well as P3HT blended with PEO shifts from 3.9 to 3.5 nmng Figure2. We eWe employed Rutherford backscattering spectrometry (RBS) to gain insight into the vertical distribution of the semiconductor and matrix polymer in spin‐coated films. The relative intensity of the carbon and sulfur signal (extracted from fits to the RBS spectra) in neat 1:9 P3HT:PEO as well as films doped with 5 and 20 mol% F4TCNQ agreed well with the semiconductor:insulator ratio . The equivalent width of spectral features associated with sulfur and carbon indicates that the distribution of the two elements is similar throughout the thickness of the film. Since only P3HT contains sulfur we conclude that the here studied samples are characterized by an even depth‐distribution of the semiconductor. This conclusion is corroborated by attempts to fit the recorded spectra with e.g., a bilayer model , with enhanced surface concentrations of sulfur, which resulted in significantly less accurate fits.Figure2, which increased to 2 domains per μm2 for strongly doped blends. We argue that at least part of the F4TCNQ:P3HT co‐crystal phase separates into distinct domains. The remaining material has an approximately one and three orders of magnitude higher conductivity than neat 1:9 P3HT:PEO for weak and strong doping, respectively. Thus, we conclude that in both cases doped films are characterized by highly conducting islands of strongly doped, phase‐separated F4TCNQ:P3HT that are surrounded by moderately conducting material, which mostly consists of PEO that contains more weakly doped P3HT.Current‐sensing atomic force microscopy (CS‐AFM) of spin‐coated films allowed us to study the lateral distribution of the conducting phase. First of all, we observe that blends weakly and strongly doped with 5 and 20 mol% F4TCNQ, respectively, display a higher through‐plane conductivity across the whole scanned surface than undoped 1:9 P3HT:PEO. This observation suggests that – as already indicated by RBS – the conducting phase is continuous throughout the film. Whereas current‐sensing maps of neat 1:9 P3HT:PEO appear featureless, 200 nanometer‐sized domains become visible upon doping that feature a two orders of magnitude higher conductivity than the surrounding material  for blends with a P3HT:PEO ratio of 1:9  of F4TCNQ from UV–vis‐NIR absorption spectra of thin films. We define doping efficiency as the ratio of F4TCNQ anion concentration to total F4TCNQ concentration. Previously, a doping efficiency of up to 63% was reported for P3HT doped at ambient temperature,−1 K−1 for undoped 3:7 P3HT:PEO, which is in close agreement with values measured for the neat blend components  yielded an electrical conductivity of σ ∼ 0.3 S cm4Materials: Regio‐regular poly(3‐hexylthiophene (P3HT) from Ossila , PEO from Polysciences (weight‐average molecular weight Mw = 5000 kg mol−1) and 2,3,5,6‐tetrafluoro‐7,7,8,8‐tetracyanoquinodimethane (F4TCNQ) from TCI Chemicals were used as received without further purification. The solvents ortho‐dichlorobenzene  and chlorobenzene  were purchased from Sigma‐Aldrich and DCM (purity > 99 %) was purchased from Fisher Scientific. Size exclusion chromatography (SEC) was carried out on an Agilent PL‐GPC 220 Integrated High Temperature GPC/SEC System in 1,2,4‐trichlorobenzene at 150 °C using polystyrene standards as a reference.Sample Preparation: P3HT and PEO were dissolved at a temperature of 80 °C and a concentration of 20 g L−1 in 1:1 mixtures of ODCB:CB. F4TCNQ was dissolved at a concentration of 4 g L−1 in DCM for sequential doping and ODCB for solution doping. Then, different ratios of the polymer solutions were mixed to achieve the desired P3HT:PEO ratio, followed by addition of F4TCNQ:ODCB solutions in case of solution doping. The F4TCNQ content was always given as the molar fraction relative to the P3HT repeat unit. Micrometer‐thick films for optical microscopy, electrical conductivity and Seebeck measurements were drop‐cast onto cleaned microscopy glass slides (2.5 × 2.5) cm at the temperatures indicated in Figure 2 substrates for GIWAXS (1000 rpm for 90 s followed by 10 s at 3000 rpm). The thickness of drop‐cast and spin‐coated films was determined with a micro‐caliper and a Dektak 150 Profilometer, respectively. A free standing tape of strongly doped 3:7 P3HT:PEO was prepared by drop‐casting from 50 g L−1 ODCB:CB solutions onto cleaned microscopy slides, followed by hot‐pressing at 60 °C. Note, that the peak melting temperature of the used PEO grade was 63 °C.F4TCNQ Anion Spectrum: Separate solutions of F4TCNQ and potassium iodide (Sigma‐Aldrich) with a concentration of 1 mol L−1 were prepared at 75 °C in acetonitrile . 1.5 molar equivalents of the hot potassium iodide solution were added to the F4TCNQ solution, which turned from yellow to green. The solution was kept at 75 °C for 1 h and then cooled to ambient temperature. One day later a blue precipitate had formed, which was filtered, carefully washed with small amounts of cold acetonitrile and dried under vacuum overnight. The resulting blue powder was dissolved in acetonitrile. Absorption spectra of concentrations ranging from 8 × 10−6 to 7 × 10−5 mol L−1 were taken in order to determine the extinction coefficient ε of the F4TCNQ anion as a function of wavelength.Optical Microscopy: Transmission optical micrographs were recorded with a Zeiss Axio Scope A1.UV–Vis Absorption Spectroscopy: Measurements were performed with a PerkinElmer Lambda 900 spectrophotometer equipped with an integrating sphere. Absorption spectra of doped P3HT:PEO blend films were fitted with two Gaussian peaks , a P3HT aggregate Spano modelCurrent‐Sensing Atomic Force Microscopy (CS‐AFM): CS‐AFM images were recorded with an Agilent 5500LS instrument using a Rocky Mountain Nanotechnology solid platinum tip model RMN‐25PT300. The force applied was the same for all the images, 300 nN, which was chosen to ensure a good tip‐sample electrical contact. The current was amplified with a “Resiscope V2” external module attached to the AFM, which applies the bias voltage to the sample while the tip was grounded. The voltage used for all the images where set at the same value, + 1 V DC, current scale was logarithmic.Grazing‐Incidence Wide‐Angle X‐Ray Scattering (GIWAXS): GIWAXS images were obtained at the D‐line at the Cornell High Energy Synchrotron Source (CHESS) at Cornell University. A synchrotron radiation of a wavelength of 1.155 Å was used for these measurements. A Pilatus 200K detector with pixel size of 172 μm × 172 μm was used to collect X‐rays scattered by the sample at a sample to detector distance of 173.8 mm.Rutherford Backscattering Spectrometry (RBS): Rutherford backscattering spectrometry was performed using a 2 MeV He+ primary beam provided by the tandem accelerator at Uppsala University. Spectra were recorded for particles scattered at 170 degrees with respect to the incident beam direction. The analysis was performed with help of the commercial software package SIMNRA.Electrical Characterization: The electrical resistivity was measured with a four point probe setup from Jandel Engineering  using colinear tungsten carbide electrodes with equidistant spacing of 1 mm and held down with a constant weight of 60 g. Seebeck coefficients were measured at 300 K with an SB1000 instrument equipped with a K2000 temperature controller from MMR Technologies using a thermal load of 1–2 K and a constantan wire as an internal reference. Samples of about 1 mm × 4 mm were cut from drop‐cast films and mounted on the sample stage using silver paint . Measurements were done at a relative humidity of typically not more than 30%; vacuum‐drying had no effect on subsequent Seebeck measurements.Bulk Thermal Conductivity Measurements: Samples for thermal conductivity were prepared by drop‐casting ≈400 mg of material from 50 g L−1 ODCB:CB solutions onto cleaned microscopy glass slides, followed by cold pressing of dried material at ambient temperature and 26 kN cm−2 to form two pellets with a diameter of 13 mm and a thickness of ≈1.4 mm. The density was determined by measuring the volume and weight of the pellets. A TPS 2500 S Thermal Constants Analyzer from Hot Disk was used to first determine the (volumetric) specific heat capacity and then the thermal conductivity at ambient temperature using sensor 7531 and expanded polystyrene as the surrounding insulating material. An isotropic model was used for data analysis.Mechanical Characterization: Tensile stress‐strain curves of drop‐cast samples were recorded with a DMA Q800 from TA Instruments at room temperature and a constant sample displacement rate of 400 μm min−1.As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re‐organized for online delivery, but are not copy‐edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors.SupplementaryClick here for additional data file.


Dynamic in vivo NMR during breath hold apnea was performed at 3 T on two healthy volunteers following inhalation of hyperpolarized 129Xe.Hyperpolarized 129Xe chemical shift in RBCs was found to increase nonlinearly with blood oxygenation at 1.5 T and 3 T. During breath hold apnea, the 129Xe chemical shift in RBCs exhibited a periodic time modulation and showed a net decrease in chemical shift of ∼1 ppm over a 35 s breath hold, corresponding to a decrease of 7–10 % in RBC oxygenation. The 129Xe‐RBC signal amplitude showed a modulation with the same frequency as the 129Xe‐RBC chemical shift.The 129Xe‐RBC chemical shift to measure pulmonary blood oxygenation in vivo has been demonstrated. Correlation between 129Xe‐RBC signal and 129Xe‐RBC chemical shift modulations in the lung warrants further investigation, with the aim to better quantify temporal blood oxygenation changes in the cardiopulmonary vascular circuit. Magn Reson Med 77:1399–1408, 2017. © 2016 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.The feasibility of using the  Knowledge of tissue oxygenation can provide valuable insight into the pathophysiology of a spectrum of diseases. For example, in the discrimination of the penumbra following stroke MR perfusion imaging can be used to measure blood delivery to a tissue of interest, however, oxygen supply and demand can be independent of one another, e.g., revascularization of fibrotic tissue provides blood flow out of proportion to metabolic demand. Likewise, tissues with low levels of perfusion have an adequate oxygen supply while at rest, but an inadequate oxygen supply during periods of increased metabolic demand. Tissue perfusion alone, therefore, does not completely describe the underlying physiology of gas exchange T2* dephasing and diffusion due to microscopic susceptibility gradients, and is therefore very much dependent upon the means of measurement, for example the choice of pulse sequence and field strength. Techniques that introduce exogenous tracers for MR oximetry, such as Overhauser‐enhanced MRI of unpaired radicals 19F MRI T1 of inhaled hyperpolarized 3He gas in the airspaces Several techniques have been developed to quantify regional oxygenation using MRI. A promising method is the use of blood oxygen level dependent (BOLD) MRI 129Xe MR has been shown in numerous studies to be a useful noninvasive probe of lung structure 129Xe NMR is highly sensitive to the xenon chemical environment: 129Xe nuclei exhibit a marked change in resonance frequency when dissolved in different biological fluids and tissues Xenon has been in routine clinical use for many years as a tracer of blood perfusion 129Xe gas is inhaled into the lungs. The largest peak originates from 129Xe gas in the alveolar airspaces and the two other peaks, centered approximately 200 ppm away from the gas peak, have been attributed to 129Xe dissolved in lung parenchymal tissue/blood plasma (TP) and in red blood cells (RBCs) 129Xe resonances 129Xe resonance frequency in RBCs was shown previously by Wolber et al. to be sensitive to blood oxygen saturation, sO2129Xe chemical shift dependence on blood oxygenation are not yet fully understood, and the dependence is currently thought to be due to the conformational changes of hemoglobin as it binds and releases oxygen molecules Three distinct NMR peaks are observed in vivo when 129Xe dissolved in samples of human blood were obtained to validate the previous in vitro work conducted at B0 = 1.5 T by Wolber et al. 129Xe‐RBC resonance frequency and blood oxygenation, over the full oxygenation range at the two clinically relevant field strengths of 1.5 T and 3 T. Using this relationship, measurements of RBC sO2 in vivo in healthy human lungs were then derived using whole lung NMR spectroscopy measurements of lung oxygen desaturation during breath hold apnea. A technique for the noninvasive dynamic detection of RBC sO2 in vivo using hyperpolarized 129Xe is hereby demonstrated.In the study reported here, spectra of hyperpolarized 129Xe), 10 % nitrogen and 87 % helium was flowed through a glass cell  on a home‐built 129Xe spin‐exchange optical pumping polarizer 129Xe was cryogenically separated in a liquid nitrogen‐cooled distilator and collected in its frozen state over a time of ∼20 min (xenon volume ∼ 200 mL) for in vitro samples and ∼60 min (xenon volume 600 mL) for in vivo samples.For in vitro and in vivo studies, a gas mixture of 3 % isotopically enriched xenon  by venipuncture and transferred into lithium heparin vacuum containers approximately 2–3 h before the start of the NMR experiments. All blood samples were allowed to equilibrate to a temperature of 20 ± 2 °C (the temperature at which the scanner room is maintained). Before conducting the NMR experiments, the xenon was first dissolved in the blood. To ensure effective mixing, the xenon and blood were passed through an exchange module sO2 (fraction of hemoglobin molecules that are fully oxygenated), pO2 ,pCO2 , HCT (fraction of red blood cells within whole blood) and pH. Immediately after acquiring NMR spectra as described below, approximately 0.1 mL of blood was withdrawn directly from the NMR sample syringe and taken to the blood gas analyzer for analysis. Full experimental details of the xenon/oxygen dissolution method and RBC sO2 measurement technique have been described previously in a study reporting the T1 relaxation behavior of 129Xe in blood A clinical blood gas analyzer  was used to analyze each blood sample and determine the following physiological parameters: 129Xe dissolved in RBCs and plasma. The gas exchange membrane was positioned near the sensitive volume of the NMR coil to reduce the xenon‐blood transit time to the coil and, thus minimizing T1 relaxation. To calibrate the excitation flip angle, a small sample of the hyperpolarized 129Xe‐blood mixture was placed within the active coil volume. Hard pulses of duration 500 μs were used to acquire spectra, and from these, the 129Xe‐RBC signal decrease was fitted to (cos α)n‐1, where α is the flip angle to be calibrated and n is the RF pulse number A custom‐built, eight‐turn solenoid radiofrequency (RF) coil of 15 mm inner diameter was used for transmission/reception at the frequency of B0 field strengths, 20 pulse‐acquire measurements were made with 512 sample points, a receiver bandwidth of 2.5 kHz and a repetition time (TR) of 500 ms. Free induction decay data were imported into MATLAB  for spectral analysis. Zero‐order phase corrections (on the 129Xe‐RBC resonance), followed by first‐order phase corrections  were performed on the averaged raw data, and absorption spectra, Re[L], were fitted in the chemical shift (δ) domain to a linear combination of two LorentziansAr, Bp are the amplitudes of the RBC and plasma 129Xe resonances; δr0, δp0 are the maxima of the 129Xe‐RBC and 129Xe‐plasma resonances; and Γr, Γp are the full width half maxima of the two respective peaks. Figure 129Xe‐blood spectrum.Spectra were acquired on both 1.5 T  and 3 T  MR scanners. At both 129Xe resonance was used for excitation of the 129Xe dissolved in RBCs (129Xe‐RBC) and parenchymal tissue/blood plasma (129Xe‐TP) using a flexible quadrature transmit/receive RF coil tuned to 35.35 MHz . See Figure 129Xe‐gas, 129Xe‐RBC, and 129Xe‐TP peaks in the lungs measured at 3 T.Whole‐lung spectroscopy experiments were then performed at 3 T  on two healthy male Caucasian volunteers (24 and 28 years old). All experiments were performed during breath hold apnea lasting 35–40 s. A 360 μs duration 90° hard pulse centered ∼200 ppm downfield from the gaseous 129Xe gas peak was determined to be ∼2.5° . To achieve a TR of 100 ms at 3 kHz bandwidth, the number of samples was decreased to 128, reducing the spectral resolution to ∼0.7 ppm. The spectra were phased and fitted to a double Lorentzian using the same method outlined in the previous section.Two separate pulse‐acquire sequences with TRs of 100 ms (performed on the 28‐year‐old volunteer) and 800 ms (performed on both volunteers) were used, and the effective flip angle excitation on the 129Xe and sO2 of blood was calibrated in a controlled in vitro environment. The resonance frequency of 129Xe dissolved in plasma was used as a reference as it was found not to vary as a function of blood oxygenation in vitro. Increasing RBC sO2 caused an increase in the resonance frequency of 129Xe dissolved in RBCs. The RBC‐plasma peak separation increased from approximately 20.4 ppm, when the blood was in a completely deoxygenated state, to approximately 25.5 ppm when the blood was in a fully oxygenated state.The relationship between the chemical shift of sO2 behavior was consistent at B0 magnetic field strengths of both 1.5 T and 3 T. To quantify the change in RBC‐plasma peak separation, δ, as a function of sO2, the 129Xe‐RBC and 129Xe‐plasma peak locations, δr0 and δp0, were determined by fitting the spectra to Equation sO2. The extracted peak separations are plotted as a function of sO2 in Figure 129Xe in RBCs appears to be nonlinearly dependent on the measured sO2, which is consistent with the previous observations of Wolber et al. α and β are empirical constants and δ0 is the RBC‐plasma peak separation in fully deoxygenated blood , or of the order of (TR = 800 ms), the RBC capillary transit time of ∼750 ms To determine whether a similar shift in the resonance frequency of 129Xe‐TP signal exhibited a monotonic decay over the breath hold time , which acts as a longitudinal magnetization reservoir, replenishing the 129Xe‐dissolved magnetization in between RF pulses. With this assumption, a T1 fit  was performed on the decaying 129Xe‐TP signal, resulting in an approximate 129Xe‐gas T1 value of 18.8 s, which is in good agreement with previously measured 129Xe‐gas T1 values of ∼ 20 s 129Xe‐RBC signal was observed to decay with the same overall rate as the 129Xe‐TP signal, it did not decay monotonically; instead, the signal was observed to modulate periodically over the breath hold time  was measured to be 4–8 s (0.125–0.25 Hz).To view this oscillatory decay behavior more clearly, the 129Xe‐TP resonance was observed to remain fixed in position over the 35 s breath hold, the 129Xe‐RBC resonance chemical shift was observed to decrease by approximately 1 ppm. The first observation of in vivo 129Xe‐RBC resonance shifts with lung oxygenation was first reported in our preliminary work 129Xe‐RBC resonance frequency in patients with idiopathic pulmonary fibrosis relative to healthy normals. Here, the 129Xe‐RBC chemical shift exhibited a periodic modulation at the same frequency as the 129Xe‐RBC signal oscillation, with a 180° phase difference  of ∼1 s over the breath hold duration.In these calculations, it was assumed that the temperature difference in vitro (20 °C) and in vivo 37 °C) has a negligible effect on the 7 °C has 129Xe‐RBC chemical shift on sO2 has been reported in previous work by Wolber et al. 129Xe‐RBC chemical shift difference between oxygenated and deoxygenated blood. Instead, the authors hypothesized that the observed nonlinear relationship between blood oxygenation and chemical shift is the result of an oxygen‐dependent hemoglobin affinity for xenon. To date, a total of 12 xenon binding sites have been located in deoxyhemoglobin using X‐ray crystallography 129Xe‐RBC chemical shift and blood oxygenation.The observation of a nonlinear dependence of 129Xe in a solvent solution is determined by the local magnetic field experienced at the nucleus, which is mediated by the screening (or shielding) constant, σ:ωObs is the observed resonance frequency, γ is the gyromagnetic ratio, B0 is the applied static magnetic field and Beff is the effective field at the nucleus. Following the pioneering work of Buckingham et al. σ, of a nucleus can be expressed as the sum of the screening constant of the individual nucleus, σ0, and a term arising due to the presence of the solvent medium, σm, thusσa is a contribution from molecular anisotropy effects, σe is the polar effect caused by an electric field, σw is due to the van der Waals forces between the solute and solvent and σb indicates the shielding arising from bulk magnetic susceptibility effects within the solvent, which we neglect as a significant contributor to 129Xe chemical shift changes with blood oxygenation from the conclusions drawn by Wolber et al. 129Xe dissolved in solution at 20 °C and at body temperature (37 °C), the anisotropic and electric field terms are zero The resonance frequency of −σw = BF¯2, where F¯2 is the mean square electric field brought about by fluctuations among electrons located on the neighboring solvent molecules and B is the “shielding hyperpolarizability” 129Xe, whose nucleus is surrounded by a large, easily‐deformed electron cloud. As a result of this high shielding hyperpolarizabilty, the chemical shift of dissolved 129Xe in a solvent is very sensitive to small differences in the dispersion fields acting within liquid solvents. The most commonly used approach to correlate solvent‐induced 129Xe chemical shifts with F¯2 is to use a continuum model to describe the solvent F¯2 is proportional to the square of the Bayliss‐McRae function, g(n)F¯2∝[g(n)]2 = [(n2−1)/(2n2+1)]2, where n is the index of refraction of the solvent. The refractive indices of oxyhemoglobin and deoxyhemoglobin have been recently measured by Zhernovaya et al. 129Xe‐RBC chemical shift change with blood oxygenation cannot be predicted using whole blood refractive index measurements.Stephen 129Xe forms transient van der Waals bonds with hemoglobin, the net electron cloud of 129Xe is likely to be drawn to the more electronegative O2 molecule in oxyhemoglobin. This would act to increase the deshielding of the 129Xe nucleus, thereby reducing σw, resulting in an increased 129Xe‐RBC resonance frequency, which is in agreement with the observed data.Experiments using Mössbauer spectroscopy σw is strongly dependent on the separation between a nucleus and the molecules giving rise to fluctuating electric fields F¯2, experienced by the 129Xe nucleus within the hemoglobin. Each RBC contains a large number of individual hemoglobin molecules, and the fraction of hemoglobin molecules in the oxy‐ and deoxy‐conformations has been measured previously in horse hemoglobin to vary smoothly as a function of blood oxygenation 129Xe nuclei would thus be expected to vary smoothly as a function of blood oxygenation, which is consistent with the observation of a smooth nonlinear change in the 129Xe‐RBC resonance with blood oxygenation.In addition to changes in the electronegativity of the hemoglobin molecules with blood oxygenation, the xenon‐hemoglobin binding site locations may change as the hemoglobin makes transitions between oxy‐ and deoxy‐conformations. As the extent of the shielding constant 129Xe relaxation rate and 129Xe‐RBC chemical shift with sO2 are related, a correlation plot of the variation of the two NMR parameters was generated, as shown in Figure 129Xe‐RBC relaxation rate data are taken from our previous study 129Xe‐RBC relaxation rate and sO2 was determined. The plot reveals that changes in 129Xe‐RBC relaxation rate and 129Xe‐RBC chemical shift are well correlated, with a coefficient of determination of R2 = 0.83. This presents strong empirical evidence that the underlying physical mechanism driving these observed changes in chemical shift and relaxation rate is the same. As the chemical shift and relaxation rate of 129Xe in solvents is strongly dependent on intermolecular separations, we therefore conclude it is likely that oxygen‐modulated xenon binding is largely responsible for the observed 129Xe‐RBC chemical shift and relaxation rate sO2 dependencies.Finally, to help determine whether the underlying mechanisms driving the change in sO2 values calculated from the 129Xe‐RBC chemical shift were shown to oscillate over the breath hold at the same frequency as the 129Xe‐RBC signal amplitude modulation, but with a 180° phase difference; the sO2 maxima were observed to coincide with the 129Xe‐RBC signal minima, suggestive of a link between pulmonary oxygenation and 129Xe‐RBC signal changes. The calculated sO2 of ∼0.87 for both volunteers at the beginning of the breath hold suggests that the observed 129Xe‐RBC signal comprises 129Xe dissolved in blood containing RBCs with mixed sO2 values; otherwise it would be expected that the calculated sO2 would equal either 1.00 for fully oxygenated blood or ∼0.75 for deoxygenated blood. Indeed, for TR values of 100–800 ms, the observed 129Xe‐RBC signal should be constituted primarily by 129Xe nuclei dissolved in blood circulating in the alveolar capillary bed, which contains blood with a range of sO2 values. Signal contribution from 129Xe dissolved in blood circulating in the pulmonary arteries (precapillary blood) is assumed to be negligible as a result of 129Xe polarization losses incurred during 129Xe transit in the systemic circulation. Signal from 129Xe in the pulmonary veins is also considered to be negligible, as the postcapillary 129Xe signal is destroyed by 90° RF pulses for TR values of 100–800 ms, which are of the order of the RBC capillary transit time of 750 ms.As shown in Figures sO2 of RBCs which contribute to the observed 129Xe‐RBC signal for TR = 800 ms can be derived using the following assumption: the average RBC oxygenation in the capillaries sO2c = [0.75 (deoxygenated) + 1.00 (oxygenated)] / 2 = 0.88. This agrees well with the sO2 value of 0.87 calculated from the ∼22 ppm chemical shift observed at the start of breath hold apnea in both healthy volunteers for TR = 800 ms.A first‐order estimate of the expected average sO2 of 7–10 % was calculated for both volunteers. During breath hold the oxygen partial pressure, pO2, in the lungs will decrease over time. Measurements of changes in oxygen partial pressure as a function of breath hold have been performed in both animal and human lungs using hyperpolarized 3He MR pO2 can be approximated by a linear relationship R is the rate of oxygen extraction by perfusion and p0 is the initial pO2. Previous studies involving pO2 mapping with 3He in healthy volunteers R to decrease with decreasing p0. This may be a result of the lower baseline pO2 reducing the alveolar‐capillary pO2 gradient, and, therefore, decreasing the rate of diffusion of oxygen from the alveoli into the capillaries. It is worth noting that over long breath holds and/or large R values, an exponential model of oxygen depletion should be used instead of Equation t is the first term in the Taylor expansion of an exponential function pO2 of 140 mbar pO2 drop upon inhalation of 1 L of anoxic gas (Xe/N2) can be estimated by scaling the pO2 with the increase in lung volume to 4 L, i.e. p0 = 140×(3/4)≈105 mbar. The R value for p0= 105 mbar has been reported to be R = 0.7 mbar/s pO2 is estimated to drop to pO2 = 81 mbar at the end of 35 s of breath hold apnea, which corresponds to a saturation sO2 value of 0.89 from the standard oxygen‐hemoglobin dissociation curve sO2c = [0.75 (deoxygenated) + 0.89 (oxygenated)] / 2 = 0.82, which is in reasonable agreement with the sO2 estimates  of approximately 0.80 for both volunteers after ∼35 s of breath hold apnea.After 35 s of breath hold apnea, a decrease in the observed 129Xe‐RBC and 129Xe‐TP signals were observed to oscillate at a frequency close to the cardiac pulsation frequency . Cardiac‐gated acquisitions may allow the probing of 129Xe‐RBC chemical shifts (sO2) at specific time points in the cardiac cycle, opening up the possibility of using 129Xe NMR to quantify temporal blood oxygenation changes in the cardiopulmonary vascular circuit.For the faster‐sampled experiment at TR = 100 ms, the spectral resolution was limited to 0.7 ppm, which was insufficient to spectrally discriminate changes in the 129Xe‐TP signal modulation arises from blood plasma flux changes within the cardiac cycle, it is possible to compare the peak‐to‐peak 129Xe‐RBC signal, amplitude, SA, with the 129Xe‐TP signal amplitude, SB, to estimate the relative RBC and plasma concentrations in the blood circulating through the capillaries. Thus, by taking the average of the first five SA and SB values after steady‐state was reached, sa = 0.113±0.004 and sb = 0.050±0.003, respectively, the HCT in the capillaries may be estimated fromx = Saδb/Sbδa and δa= 0.27, δb= 0.094 are the solubilities of xenon in RBCs and plasma at 37 °C c = 0.44, in good agreement with the Fåhræus effect which predicts HCT < 0.50 With the assumption that the 129Xe spectroscopy oximetry technique may also have applications outside of the lungs. For example, Mazzanti et al. 129Xe dissolved in the rat brain can be modulated in a manner responsive to stimuli, suggestive that there is a significant contribution to the measured 129Xe signal from blood flow/perfusion. Moreover, dissolved 129Xe spectra from the human brain have been successfully acquired 129Xe can be detected in organs quite distal from the point of uptake in the lungs.This dissolved 129Xe imaging methods 129Xe‐RBC peak position would affect the intensity of the 129Xe‐RBC phase image.Finally, this work has implications for Dixon‐based dissolved 129Xe as an exogenous NMR probe of pulmonary blood oxygenation in humans has been explored. A nonlinear relationship between the measured sO2 values and the NMR resonance frequency of 129Xe dissolved in RBCs has been observed in vitro from blood samples at 1.5 T and 3 T. This relationship was evaluated over the entire range of possible blood oxygenation values and appears to be independent of magnetic field strength.In this study, the feasibility of using hyperpolarized sO2 values by means of in vivo dissolved 129Xe whole‐lung spectroscopy experiments conducted during apnea on a 3 T whole body system. To date, we are not aware of any other means of noninvasively measuring pulmonary blood oxygenation. The common modulation frequency of blood oxygenation and 129Xe‐RBC signal change during breath hold is interesting and further work with cardiac‐gated hyperpolarized 129Xe NMR is underway to help understand this newly observed phenomenon. Lastly, the HCT in the pulmonary capillaries has been estimated from 129Xe spectroscopic data. Further work is underway to validate hyperpolarized 129Xe NMR as a noninvasive technique for quantification of HCT in the pulmonary capillaries.Furthermore, this relation has been used to derive lung blood


The sensory characteristics of the material towards carbon monoxide in the concentration range 6.7–20 ppm have been examined in both dry and humid air. A sensor signal is achieved in dry air at sufficiently low temperatures T = 80–120 °C, but the increase in relative humidity results in the disappearance of sensor signal in this temperature range. At temperatures above 200 °C the inversion of the sensor signal in dry air was observed. In the temperature interval 180–200 °C the sensor signal toward CO is nearly the same at 0, 20 and 60% r.h. The obtained results are discussed in relation with the specific features of the adsorption of CO, oxygen, and water molecules on the surface of Co3O4. The independence of the sensor signal from the air humidity combined with a sufficiently short response time at a moderate operating temperature makes Co3O4 a very promising material for CO detection in conditions of variable humidity.Nanocrystalline cobalt oxide Co By. By34]. 3O4 sensitivity to CO in the temperature interval 150–300 °C. However, at the temperature T > 200 °C an additional mechanism can be involved in the CO oxidation process. As follows from the detailed review  begins to exceed the hole concentration [p], then the electrons become the main charge carriers ([n] > [p]) and the type of conductivity changes from p-type to n-type resulting in the inversion of sensor signal.If in the surface layer of Co2S detection by p-type CuO nanowire sensor operated at 325 °C [From TPD curves of oxygen  34] one one34] ot 325 °C . For CuOt 325 °C . Conside3O4 crystal lattice during the oxidation of CO by Mars–van Krevelen mechanism. One of the stages of this process is the filling of the oxygen vacancy by the oxygen atom, which is the limiting stage of the process as a whole.The values of response and recovery time obtained in dry air as a function of temperature are shown in 3O4 with a mean particle size of 30–40 nm and specific surface area of 8–13 m2/g has been prepared by the carbonate method and characterized in detail using XRD, ED, TEM and HAADF-STEM imaging and EDX analysis and FTIR spectroscopy.Nanocrystalline p-type Co3O4 in CO detection were investigated in the temperature range 60–300 °C at different humidity levels 0, 20 and 60% r.h. In dry air the maximum sensor signal was observed in low temperature interval 80–120 °C. The increase in relative humidity results in the disappearance of sensor signal in this temperature range because of transformation of active oxygen species adsorbed on Co3O4 surface (α oxygen) into inactive ones (ε oxygen), and formation of thermally stable surface carbonates. The values of response and recovery time for the processes, in which the formation of the sensor signal is due to the CO interaction with adsorbed oxygen are close and do not depend on the humidity level.The gas sensor properties of synthesized CoT = 240–300 °C the inversion of the sensor signal was observed during CO detection in dry air. This fact is explained by the participation of the oxygen of the Co3O4 crystal lattice during the oxidation of CO by Mars–van Krevelen mechanism.In the temperature range 3O4 a very promising material for outdoor and indoor CO detection.The sensor signal to CO at 180–200 °C is nearly the same at 0, 20 and 60% r.h. since CO molecules are oxidized by the reactive oxygen species (β oxygen) originated from


APN) is known to promote the osteogenic differentiation of human jaw bone marrow mesenchymal stem cells (h‐JBMMSCs). However, the underlying mechanism has not been fully elucidated. Previously, we showed that APN could promote h‐JBMMSC osteogenesis via APPL1‐p38 by up‐regulating osteogenesis‐related genes. Here, we aimed to determine whether APN could promote h‐JBMMSC chemotaxis through CXCL1/CXCL8. The CCK‐8, wound healing and transwell assays were used to evaluate the proliferation, migration and chemotaxis of h‐JBMMSCs with or without APN treatment. Chemotaxis‐related genes were screened using RNA‐seq, and the results were validated using real‐time PCR and ELISA. We also performed Western blot using the AMPK inhibitor, WZ4003, and the p38 MAPK inhibitor, SB203580, to identify the signalling pathway involved. We found that APN could promote h‐JBMMSC chemotaxis in the co‐culture transwell system. CXCL1 and CXCL8 were screened and confirmed as the up‐regulated target genes. The APN‐induced CXCL1/8 up‐regulation to promote chemotaxis could be blocked by CXCR2 inhibitor SB225002. Western blot revealed that the phosphorylation of AMPK and p38 MAPK increased in a time‐dependent manner with APN treatment. Additionally, WZ4003 and SB203580 could suppress the APN‐induced overexpression of CXCL1 and CXCL8. The results of the transwell chemotaxis assay also supported the above results. Our data suggest that APN can promote h‐JBMMSC chemotaxis by up‐regulating CXCL1 and CXCL8.Adiponectin ( Adiponectin was discovered in 1995 and is a 30‐kD protein that contains a globular domain (residues 111–247) APN exerts various physiological effects on many types of cells by suppressing cell death and inflammation and enhancing cell survival CXCL1 belongs to the chemokine family, along with CXCL8 and many others in vivoin vitro study, APN was found to promote the osteogenesis of human jaw bone mesenchymal stem cells (h‐JBMMSCs) through the APPL1‐p38 MAPK signalling pathway In our previous study, we showed that APN could promote the osteogenesis of extraction sockets of beagle dogs The h‐JBMMSCs were cultured as described in our previous study, and the protocol was approved by the Medical Ethical Commission of the Peking University School of Stomatology (PKUSSIRB‐201520026). The informed consent was obtained from all the patients. The h‐JBMMSCs were obtained from patients undergoing orthognathic surgery and were identified based on positivity for CD73, CD90 and CD105 and negativity for CD34, CD11b, CD19, CD45 and HLA‐DR using flow cytometry in vitro using the CCK‐8 assay . Briefly, 3 × 103 h‐JBMMSCs were plated onto 96‐well plates with 100 μl medium per well. Following overnight incubation, 10 μl of CCK‐8 solution was added to ten wells and incubated for 2 hrs in the incubator. Colour evaluation was performed photometrically at 450 nm using an ELx808 absorbance microplate reader . All the cells were cultured with complete medium (data not shown) or osteoblast‐inducing conditional medium for 8 days to determine the proliferation rate. During these 8 days of culture, PBS and APN were added to the control group and APN‐treatment group, respectively, every 3 days.Cell proliferation was measured 5 h‐JBMMSCs was cultured as confluent monolayers and wounded by scratching across the 6‐well plates with a 200‐μl pipette tip. The deciduous cells were removed using PBS. The wounded monolayers were then photographed at 10× magnification  and analysed 0, 6 and 12 hrs after scratching. Three different media were applied to determine the effect of APN treatment on the migration rate of the h‐JBMMSCs. The first was complete medium with or without APN (data not shown); the second was osteoblast‐inducing conditional medium with or without APN treatment for three times during a week, followed by scratching and assessment (data not shown); the third medium was the supernatant of the h‐JBMMSCs cultured in osteoblast‐inducing conditional medium with or without APN treatment for three times.A total of 5 × 105 h‐JBMMSCs (200 μl) were planted into the upper compartment and 1.3 ml complete medium with or without APN or CXCL1  or CXCL8  was added into the lower compartment. In the co‐culture transwell assay, 1 × 105 h‐JBMMSCs (1 ml) were placed into the lower compartment. After the h‐JBMMSCs reached confluence, osteoblast‐inducing conditional medium was added and the cells were cultured for 7 days, during which new medium and APN were added three times. Next, 1 × 105 of the h‐JBMMSCs (200 μl) were placed into the upper compartment while ensuring that the volume of medium in the lower compartment was maintained at 1.3 ml. After 12 hrs, the upper compartment was washed with PBS three times and the cells were fixed with 10% paraformaldehyde for 10 min. The cells were then stained with crystal violet and photographed at 10× magnification  after wiping out the cells from the upper surface of the upper compartment.Chemotaxis was measured using a transwell assay . In the monoculture transwell assay, 1 × 10h‐JBMMSCs were cultured in osteoblast‐inducing conditional medium for 7 days, during which new medium and APN were added three times. The cells were then washed with pre‐cooled PBS three times, and RNA was extracted using the TRIzol reagent . The samples were then analysed using Illumina high‐throughput sequencing platforms .−ΔΔCt method.mRNA was extracted from the cells using the TRIzol reagent . The PrimeScript™ RT Master Mix  was applied to generate cDNA. Relative quantitative PCR was then performed using SYBR  green master and the ABI 7500 real‐time PCR machine . The real‐time PCR was performed in 20 μl master mix containing 10 μl SYBR, 50 ng cDNA and 250 nM of each primer . The thermal cycling conditions were as follows: 10 min. at 95°C, 40 cycles at 95°C for 15 sec. and at 60°C for 60 sec. The relative expression levels of the genes were measured using the 2h‐JBMMSCs were cultured in osteoblast‐inducing conditional medium in 24‐well plates with or without APN. The cells in the APN‐treatment groups were cultured for 7 days with the addition of APN three times (once every 3 days). All the cells and supernatants were collected for ELISA. Total protein was extracted using the RIPA buffer , and the protein concentration was determined using the bicinchoninic acid reagent . ELISA was then used to assess the levels of CXCL1  and CXCL8  in the cytoplasm and supernatant according to the manufacturers’ instructions.The h‐JBMMSCs were cultured in 60‐mm dishes, then starved for 12 hrs after reaching 90% confluence and treated with 1 μg/ml APN at the indicated time‐points. The primary antibodies used were as follows: p‐p38 MAPK  at 1:1000; p38 MAPK  at 1:1000; p‐AMPK  at 1:1000; AMPK  at 1:1000; and actin  at 1:1000. Anti‐rabbit secondary antibody  was used at 1:5000. The protein concentration was detected using a chemiluminescence detection system  and analysed using ImageJ software .P < 0.05) between the groups were valued using one‐way analysis of variance or the Student's t‐test. All the statistical analyses were performed using SPSS 19.0 software .Data are represented as the mean ± standard deviation. Statistically significant differences (P > 0.05). The migration rates of the control and APN‐treatment group, as determined using the wound healing assay, were 35.33 ± 1.65 μm/h and 34.08 ± 1.77 μm/h, respectively, at 6 hrs and 43.33 ± 1.65 μm/h and 43.08 ± 1.89 μm/h, respectively, at 12 hrs , with no significant difference. The monoculture transwell assay showed that the migrating cell counts of the h‐JBMMSCs did not significantly change after APN (1 μg/ml) treatment  in the lower compartment. In the co‐culture transwell assay, after the h‐JBMMSCs in the lower compartment were treated with APN three times in osteoblast‐inducing conditional medium for 7 days, the upper compartment was seeded with h‐JBMMSCs from the lower compartment for 12 hrs. The migrating cell counts were 149 ± 11 and 104 ± 8  with and without APN treatment, respectively.The CCK‐8 cell proliferation assay showed that there was no significant difference between the control and the APN‐treatment group from day 1 to day 8 in the osteoblast‐inducing conditional medium . The fold change in the expression of CXCL1 and CXCL8 was 4.8 and 5.5, respectively, in the APN‐treatment group compared to the expression in the control group  and 11.7 times , respectively, in the APN‐treatment group  and 7.1 times , respectively, in the APN‐treatment group than in the control group. The CXCL8/total protein (pg/g) level of the cells and supernatants was increased 1.8 times  and 34.8 times , respectively, in the APN‐treatment group . Western blot revealed that h‐JBMMSCs expressed CXCR1 and CXCR2 and that CXCR2 was up‐regulated with APN treatment . When h‐JBMMSCs were pre‐treated with SB225002, the migrating cells were inhibited in both the co‐culture  and the monoculture  transwell systems  but could not suppress the APN‐induced increase in the CXCL1/total protein and CXCL8/total protein levels in the supernatants . Compared to the control‐APN(+) group, the p38 MAPK‐APN(+) group and AMPK‐APN(+) group showed significantly lower levels of CXCL1/total protein and CXCL8/total protein in the cells and the supernatants . Treatment with the inhibitors significantly down‐regulated CXCR1 and CXCR2 (P < 0.05), but showed no response to APN treatment .The AMPK inhibitor, WZ4003, and the p38 MAPK inhibitor, SB203580, could suppress the APN‐induced increase in the CXCL1/total protein and CXCL8/total protein levels in the cells . The proliferation rate of the h‐JBMMSCs after APN treatment (1 μg/ml) in either complete medium (data not shown) or osteoblast‐inducing conditional medium showed no significant difference compared with the untreated group . Real‐time PCR . When h‐JBMMSCs were pre‐treated with SB225002, the APN‐induced chemotaxis and CXCL1/8‐induced chemotaxis were inhibited. Other reports also proved that SB225002 could inhibit the CXCL1/8‐induced chemotaxis in neutrophils To identify the chemokines involved in the APN‐induced chemotaxis of h‐JBMMSCs, after culturing the cells in osteoblast‐inducing conditional medium with or without APN for 1 week, the total RNA of the h‐JBMMSCs was extracted and analysed using RNA‐seq. Among the up‐regulated genes, CXCL1 and CXCL8 genes were selected as the target genes, and the fold changes in their expression levels were 4.8 and 5.5, respectively, between the APN‐treated and untreated groups  signalling pathway by binding with the membrane receptor AdipoR1 To the best of our knowledge, this is the first study showing the effect of APN on the chemotaxis of h‐JBMMSCs during their differentiation into the osteoblastic lineage. The involved AMPK and p38 MAPK pathways may contribute to our understanding of the mechanism by which APN regulated the chemotaxis of h‐JBMMSCs during osteogenesis. However, the mechanisms of APN‐induced osteogenesis are complicated and need detailed investigation in future studies. In conclusion, the results of our present study indicate that APN‐induced osteogenesis might involve two synchronous and independent steps: promotion of the chemotaxis of h‐JBMMSCs to the extraction sockets and facilitation of the osteogenic differentiation of h‐JBMMSCs Fig. . This stThe authors declare no conflict of interest.