Pleurotus ostreatus and Pleurotus djamor were analyzed using the data mining technique: K-means clustering algorithm. The parameters evaluated were: biological efficiency, crop yield ratio, productivity rate, nutritional composition, antioxidant and antimicrobial activities in the production of fruit bodies of 50 strains of Pleurotus ostreatus and 50 strains of Pleurotus djamor, cultivated on the most representative agricultural wastes from the province of Guayas: 80% sugarcane bagasse and 20% wheat straw (M1), and 60% wheat straw and 40% sugarcane bagasse (M2). The database of the parameters obtained in experimental procedures was grouped into three clusters, providing a visualization of the strains with a higher relation to each parameter (vector) measured.Data of the commercial parameters of  The province of Guayas, comprising 25 cantons, including the canton of Guayaquil, which consists of the Municipality of Guayaquil and two areas of urban expansion, along with five rural cantons: Morro, Juan Gómez Rendón, Posorja, Puna and Tenguel. The province of Guayas is part of Zone 5, according to SENPLADES, National Secretariat for Planning and Development, which subdivides the country into nine zones. The main land-use of the Guayas province is agriculture (27%), followed by livestock production and aquaculture. This province has gone through three main economic booms .The first economic boom occurred in 1880 when it was the main cocoa exporting city (between 20% and 25% of the world), becoming an important commercial and financial center, which generated an increase in the city’s population . The secThe cultivation of edible mushrooms has gradually grown using homemade techniques until becoming a highly technical industry ,8,9,10. Pleurotus spp. [Pleurotus spp. has not been allowed to be used for the benefit of human health in Ecuador. In order to illustrate adequate visualization, the use of data mining tools, such as the K-means clustering algorithm, upon big data, about the commercial parameters of Pleurotus spp. is important [One of the principal genera of edible mushrooms with the highest production around the world is tus spp. ,14. Thestus spp. ,16. Thestus spp. ,18,19. Atus spp. . Howevermportant .In this paper, the focus is on clustering. The clusters have been applied in many research areas such as mathematics, engineering, economics, marketing, machine learning, pattern recognition, genetics, bioinformatics, psychology, biology, data compression and information retrieval . The iniThe main goal was to use a data mining technique, the K-means clustering algorithm, to verify the influence of two mixtures of agricultural wastes obtained from the province of Guayas on the viability of the mushrooms production, the nutritional profile and also in the antioxidant and antimicrobial properties. The use of the K-means clustering algorithm allowed the indication of the strain cultivated on a specific mixture of agricultural wastes that obtained the highest values in commercial parameters. Pleurotus ostreatus (PO) and 50 strains of Pleurotus djamor (PD) were used. These strains were collected from producers in the province of Guayas. The strains were maintained on MEA dishes and are deposited at the fungal collection of the Research and Development Laboratory of Ecuahidrolizados.In this study, 50 strains of Strains were cultivated using two mixtures of agricultural wastes: 80% sugarcane bagasse and 20% wheat straw (M1), and 60% wheat straw and 40% sugarcane bagasse (M2). The mixtures of agricultural wastes were moistened for 1 day. Subsequently, the mixture was placed (1 kg wet weight) in plastic bags and pasteurized for 10 h at 80 °C.Pleurotus ostreatus (PO) and the strains of Pleurotus djamor (PD). Thereafter, the bags with the substrate, were incubated in a dark room at a temperature of 30 ± 1 °C.After pasteurization and conditioning, with the substrate at ambient temperature, the bags with the substrate were inoculated with 150 g of wheat grain previously colonized with the strains of Finally, once the mycelium of the strain had colonized the substrate, the bags with the substrate were transferred to a room with favorable conditions for the fructification: relative humidity was maintained between 85% and 90%, a temperature of 25 ± 1 °C, air recirculation and period of illumination of 12 h .The biological efficiency (BE) is a productivity parameter that explains the capacity of the substrate to produce fruit bodies and was calculated using the following equation :(1)BE(%)Equation (1). Biological efficiency of the mushrooms.The yield ratio is an analyzed variable widely adopted for industrial crops and was calculated with the following equation :(2)Y(%)=Equation (2). Yield ratio of the mushrooms.The productivity rate is the relation between BE and the precocity (namely days between inoculation and harvest) and was calculated using the following equation :(3)PR(% Equation (3). Productivity rate of the mushrooms.The nutritional value of the mushroom sample was analyzed using AOAC procedures concerning the composition of proteins, fat, carbohydrates and ash . For theEquation (4). Percentage of carbohydrates of the mushrooms.−5 mol L−1) were pipetted and mixed in a 96 well plate. The reaction mixture was incubated in the dark for 30 min, and the absorption was measured at 515 nm using a microplate reader [To evaluate the antioxidant activity, the DPPH radical-scavenging assay was used. In the beginning, 30 μL of the extract and 270 μL of methanol containing DPPH radicals (6 × 10Equation (5). DPPH radical scavenging activity (RSA).Pseudomonas aeruginosa (ABN 187) and Salmonella typhimurium (ABN 572); and the following Gram-positive bacteria: Micrococcus flavus (ABP 147) and Staphylococcus aureus (ABP 784). The microorganisms are deposited at the Research and Development Laboratory of Ecuahidrolizados.The antimicrobial activity was analyzed using the following Gram-negative bacteria: 6 CFU/mL. The mushroom extracts of Pleurotus spp. were dissolved in 30% ethanol, mixed with nutrient media for bacteria (Tryptic Soy Broth) containing bacterial inoculum (1.0 × 105 CFU per well) with a final volume of 100 µL [Bacterial suspensions were adjusted with sterile saline to a concentration of 1.0 × 10f 100 µL .k represents the kth center, and xi represents the ith point in the data set. The solution to the centroid uk is as follows:The K-means grouping method is a non-hierarchical technique used to group observations into K groups. Each item is assigned to a group with the closest center. The algorithm iteratively updates the groups to minimize the variation of their elements. The basic K-means algorithm, which was used in this article, refers to the Euclidean metric to define the distance between the elements and the centers of the clusters . The EucFurthermore, the result of the K-means method is highly dependent on the number of clusters defined beforehand. In general, the iterative clustering method of K-means is implemented as follows: Step 1: A value of K is chosen. It is used as the initial set of K centroids. Step 2: Each of the objects is assigned to the group with the closest centroid. Step 3: The new centroids of the K groups are determined, calculating the mean of the group members. Step 4: Steps 3 and 4 are repeated until there are no changes in the criterion function after one iteration .The main advantages of the K-means algorithm are its low complexity, it is computationally fast, the ability to handle large data sets and the flexibility to adjust the cluster number. K-means clustering was used to extract clusters from the dataset that had been optimized by feature selection.Additionally, a PCA biplot  was applPleurotus ostreatus and Pleurotus djamor and assess its influence on commercial parameters: biological efficiency, crop yield ratio, productivity rate, nutritional composition, antioxidant and antimicrobial activities.The focus of this work was to determine the viability of the use of agricultural wastes from the province of Guayas on the cultivation of the strains The numeration of the strains cultivated on the two mixtures of agriculture was made using the following distribution:Pleurotus ostreatus or Pleurotus djamor cultivated on the mixture M1.1–50: Strains of Pleurotus ostreatus or Pleurotus djamor cultivated on the mixture M2.51–100: Strains of Pleurotus ostreatus strains cultivated on agricultural wastes from the province of Guayas, while in the graphic (b) the use of three clusters for the productivity parameters of Pleurotus djamor strains grown on the two mixtures of substrates was shown. The results show the normal distribution of 100 data points around three clusters in each graphic. The size of each cluster is related to the number of data points, in graphic (a): the size of Cluster 1 (color red) is 34, the size of Cluster 2 (color black) is 27, and the size of Cluster 3 (color green) is 39. Pleurotus ostreatus strains grown on the two mixtures belonging to Cluster 3 did not show a relationship with the Pleurotus ostreatus strains grown on the two mixtures belonging to Cluster 1 and Cluster 2. This result indicates that the strains that belong to Cluster 1 and Cluster 2 showed higher values of the productivity parameters in comparison to the other Pleurotus ostreatus strains (Cluster 3). On the other hand, in graphic (b): the size of Cluster 1 (color red) is 34, the size of Cluster 2 (color red) is 27, and the size of Cluster 3 (color black) is 39. Pleurotus djamor strains produced on the two mixtures belonging to Cluster 3 did not show a relationship with the Pleurotus djamor strains cultivated on the two substrates belonging to Cluster 1 and Cluster 2. This result indicates that the strains belonging to Cluster 1 and Cluster 2 presented higher values of productivity parameters in comparison to Pleurotus djamor strains belonging to Cluster 3. Since the data points are normally distributed, the clusters vary in size with the maximum data points and minimum data points. The supplementation of the substrate on mushroom cultivation has been carried out with relative success, aiming at controlling pests or increasing crop yields [p yields . The resPleurotus ostreatus cultivated on the two mixtures of agricultural wastes with a higher relation to biological efficiencies and production rates, while Cluster 1 (color red) indicates the presence of 28 strains of Pleurotus ostreatus cultivated on the two mixtures of substrates with a higher relation to the yields, and Cluster 3 (color blue) indicates the presence of 43 strains of Pleurotus ostreatus cultivated on the two mixtures of agricultural wastes. On the other hand, in graphic (b) also there are differences between the clusters, Cluster 1 (color red) indicates the presence of 22 strains of Pleurotus djamor growth on the two mixtures of agricultural wastes with a higher relation to biological efficiencies and yields, whereas Cluster 2 (color green) indicates the presence of 28 strains of Pleurotus djamor cultivated on the two mixtures of substrates with a higher relation to production rates, and Cluster 3 (color blue) indicates the presence of 50 strains of Pleurotus djamor growth on the two mixtures of substrates.The commercial production of mushrooms is largely determined by the availability and utilization of cheap materials of agricultural wastes that represent the ideal and most promising substrates for cultivation ,38. The Pleurotus ostreatus fruit bodies produced on agricultural wastes from the province of Guayas, while in graphic (b) the use of three clusters for the nutritional composition and biological properties of Pleurotus djamor mushrooms cultivated on the two mixtures of substrates is shown. A normal distribution of 100 data points around three clusters in each graphic was presented. The size of each cluster is related to the number of data points, in graphic (a): the size of Cluster 1 (color red) is 23, the size of Cluster 2 (color black) is 23, and the size of Cluster 3 (color green) is 54. The three clusters present the Pleurotus ostreatus fruit bodies with the highest values of nutritional composition and biological properties. On the other hand, in graphic (b): the size of Cluster 1 (color red) is 23, the size of Cluster 2 (color black) is 23, and the size of Cluster 3 (color green) is 54. Pleurotus djamor mushrooms with the highest values of nutritional composition and biological properties are shown by the three clusters. It is important to indicate that the clusters vary in size with maximum data points and minimum data points.Pleurotus ostreatus cultivated on the two mixtures of agricultural wastes with a higher relation to the crude fiber contents and antibacterial activities, while Cluster 2 (color green) indicates the presence of mushrooms of 28 strains of Pleurotus ostreatus cultivated on the two mixtures of food wastes with a higher relation to the antioxidant activities, and Cluster 3 (color red) indicates the presence of fruit bodies of 56 strains of Pleurotus ostreatus cultivated on the two mixtures of agricultural wastes with a higher relation to the protein, ash, fat and carbohydrate contents. On the other hand, in graphic (b), there are also differences between the clusters, Cluster 1 (color red) indicates the presence of 19 strains of mushrooms of Pleurotus djamor growth on the two mixtures of agricultural wastes with a higher relation to protein contents and antibacterial activities, whereas Cluster 2 (color green) indicates the presence of fruit bodies of 34 strains of Pleurotus djamor cultivated on the two mixtures of substrates with a higher relation to ash and fat contents and also antioxidant activities, and Cluster 3 (color blue) indicates the presence of mushrooms of 47 strains of Pleurotus djamor growth on the two mixtures of substrates with a higher relation to carbohydrate and crude fiber contents.The moisture and fat contents of the mushrooms are influenced by the composition of the agricultural wastes used in the cultivation of edible fungi ,40. The Pleurotus ostreatus and Pleurotus djamor cultivated on the most representative agricultural wastes from the province of Guayas, with the commercial parameters measured in experimental procedures.The K-means clustering algorithm was used to obtain proper grouping data using three clusters and providing visualization about the relationships between strains of edible fungi Pleurotus ostreatus and Pleurotus djamor has a higher relation to the productivity parameters: biological efficiencies, crop yields and productivity rates.PCA Biplots presented that the use of mixture 1 in the cultivation of the strains of edible fungi Pleurotus ostreatus and Pleurotus djamor, cultivated on two mixtures of agricultural wastes, allowed the indication of how to obtain the highest values in productivity parameters or biological properties due to the strain grown on a specific substrate.The use of the K-means clustering algorithm on the commercial parameters of edible fungi


Depending on the final temperature, three stages of silicene evolution can be distinguished: (i) the growth of the low buckled phase, (ii) the formation of a layered heterostructure of the low buckled and planar phases of silicene and (iii) the gradual destruction of the silicene. Each stage is characterized by its unique surface morphology and characteristic diffraction patterns. The present study gives an overview of structures formed on the surface of ultrathin Au films and morphology changes between room temperature and the temperature at which the formation of Au droplets on the Si(111) surface occurs.The formation and evolution of silicene on ultrathin Au films have been investigated with low energy electron microscopy and diffraction. Careful control of the annealing rate and temperature of Au films epitaxially grown on the Si(111) surface allows for the preparation of a large scale, of the order of cm Much of the modern research related to condensed matter concerns ultrathin layered systems, which possess unique and unexpected, but often very desired, properties unknown for bulk materials. Tailor-made two-dimensional 2D) materials constitute a particularly interesting group of systems that can be used as building blocks in nanotechnology. A specific section of the 2D’s consists of a rapidly expanding family of materials composed of only one element of group 13–16 of the periodic table. Undoubtedly the most famous of them is graphene, obtained in 2004 D materia,22,23.2sp-3sp and pure 2sp hybridization, respectively. Silicene, theoretically predicted in 1994 [2(0001) [2sp hybridization of Si atoms was also found [This article is related to the next mono-elemental 2D material based on Si atom silicene. Due to the fact that silicene is chemically compatible with modern electronics based on silicon, it is hoped to be used as a basic functional material in miniaturized electronics and optoelectronics applications. Silicene forms two phases, namely low buckled and planar, on the atomic scale. Thus, it seems to be an exceptionally interesting material with  in 1994 , has bee in 1994 ,36,37,38 in 1994 ,40,41. T in 1994 ,43,44. O in 1994 ,46,47,48 in 1994 , ZrC in 1994 ,53, Si  and alsoso found .The planar and low buckled phases of silicene forming layered heterostructures have been described in detail . OrderedHere, we report on the details of the formation of silicene on ultrathin layers of Au(111) deposited on a Si(111) substrate. We carefully analyze the subsequent stages of the silicene formation by self-ordering: (i) preordering of the low buckled phase, (ii) its coexistence with the planar allotrope and (iii) final gradual decomposition of the silicene lattice. It is worth noticing that the individual stages of silicene evolution and their fingerprints can be supervised by the exact temperature control of the system. −11 mbar. Si(111) monocrystalline substrate with a specific resistivity of 3–8 Ω cm at room temperature (RT) was used for the preparation of silicene. All experiments have been performed in a Low Energy Electron Microscope (LEEM)  under an ultra-high vacuum with a base pressure below 3 × 10−10 mbar by the molecular beam epitaxy method. In order to determine the evaporation rate, we grew Au on a W(110) substrate. The elevated temperature growth assures a monolayer-by-monolayer growth mode of the two first layers. The completion and appearance of the first and second Au layers are visible as a strong contrast change in LEEM. After the growth of the Au film , gentle annealing was applied with an initial rate of 10 K/min, which was reduced down to 3 K/min at 370 K and 1 K/min while approaching 470 K. Such a heating rate is an order of magnitude smaller than that described in [−1.The Si(111)-(6 × 6)Au surface is known to promote more flat growth of Au films at RT compared to the Si substrates with other reconstructions . Thereforibed in ,62. The It is well known that in the considered system of Au films on Si, a significant diffusion of the Si atoms from the substrate through the gold layer to the surface of the sample occurs and increases with rising temperature. Besides the growing rate of diffusion of the Si atoms, the temperature increase also causes crystallographic ordering of the surface layer. Under a proper control of experimental conditions, the planar phase coexisting with the low buckled phase of silicene could be obtained ,59.It appears that depending on the annealing temperature of the Au ultrathin films, three stages in the formation and appearance of silicene could be distinguished: (i) a low buckled phase, (ii) a layered heterostructure of the low buckled and planar phases and (iii) a silicene degradation stage. In terms of the complexity of silicene degradation, the last stage may be additionally divided into two steps denoted as (1) domain multiplication and (2) domain degradation. The freshly prepared non-annealed RT system of rough Au film revealed a very weak order of the surface. Although the LEEM images did not show any extra features, apart from the occasionally visible Au droplets, there was a very blurry set of barely visible spots forming a ring in the LEED pattern, The existence of the diffraction spots showed that the surface layer formed in situ by the spontaneous segregation of Si atoms is not completely amorphous; instead, it reveals a very short-range order. The diffraction spots initially forming the blurry ring separated and became relatively sharp and intense upon annealing. The pink arrow in Further increase of the sample temperature by just a few degrees revealed a set of 24 new diffraction spots, which are in a bit smaller distance to the (00) one. The new pattern is a fingerprint of two coexisting phases of silicene—the low buckled one and the new planar allotrope. They are marked by pink loops and green circles, respectively, in The domains of the planar silicene grow with increasing temperature and finally cover the entire surface after annealing at the temperature range of 470–490 K. The planar phase of silicene formed four major well-developed domains visible as four sets of hexagonally arranged diffraction spots in LEED patterns, It is worth emphasizing that there was a relatively narrow range of temperatures where the structure of the planar silicene with only 24 perfectly separated and intense diffraction spots related to this phase. Besides these strongest diffraction spots  occurring in regions of different thicknesses. Examples of reflectivity vs. electron energy curves taken at different sample regions are shown in At this stage of annealing, new rotated planar silicene domains usually appear. Moreover, as the temperature still increased, one can notice the formation of other domains with slightly larger lattices constant than estimated for the planar silicene 4.34 ± 0.05 Å, marked by ellipses in Various lattice constants of the planar silicene were also reported in the previous STM experiments .At still higher annealing temperatures, the observed changes of the surface morphology became even more dramatic. The Au layer cracked and consequently uncovered the silicon substrate. The de-wetting process was visible in both the LEED patterns and LEEM images. The obvious sign of the formation of separated Au islands was the appearance of the Si(1 × 1) together with the (√3 × √3) superstructure diffraction spots in the LEED pattern. They are marked in Such a modified diffraction pattern shows that one of the main domains of the planar silicene disappeared at this temperature. Further temperature increase causes a gradual disappearance of the diffraction spots related to the remaining domains of the planar silicene. As a result, only 12 diffraction spots (two domains) and 6 diffraction spots (one domain) remained at 550 K and 560 K, respectively. Finally, at 565 K, residuals of silicene completely vanished, and only Si(1 × 1) together with the (√3 × √3) reconstruction remained. Numerous and very weak other diffraction spots were related to the (6 × 6)Au superstructures recovering after the Au de-wetting process.The morphology of the layer after annealing at high temperatures depended on the Au film thickness. Thicker films revealed a much larger diversity of thicknesses of the Au islands, while the thinner ones are less rough. Initially, the polygon-shaped features of the planar phase of silicene uniformly covered the whole surface. With increasing temperature, clear changes of surface topography took place: the area occupied by the silicene became reduced. The well-resolved planar silicene mesh survived in the form of small regions (one of such regions is marked by green arrow), Analysis of the intensity of the reflected electrons as a function of the energy of incident beam recorded for selected regions of the surface, It is worthwhile to emphasize that the de-wetting process did not proceed homogeneously and was very sensitive to local conditions like substrate morphology, Au layer thickness and temperature. Therefore, various regions of the sample can be found at different stages of the transformation at the same time of thermal treatment. While a clean Si crystal surface decorated with Au droplets exists at a given location, residual silicene may still be present in its close vicinity, 2. Annealing at higher temperatures caused significant changes in the morphology of the Au layer. It formed large atomically flat regions of different heights, revealing a quantum size effect. At this stage, the Au layer remained continuous, and its top was still covered with the heterostructure of both phases of silicene. However, the characteristic superstructures became weaker, indicating a decreasing order of both silicene phases. A further temperature increase broke the Au layer. Finally, Au atoms formed droplets decorating the surface of the Si crystal where no silicene features existed anymore. Besides the Au droplets, the Si surface was covered with a very thin layer of gold atoms forming (√3 × √3) reconstruction. The present study allows for a better understanding of changes occurring on the surface of the Au/Si system upon its annealing between room temperature and the temperature at which the formation of Au droplets occurs. In conclusion, the thermally induced changes of the crystallographic structure and surface morphology of ultrathin Au layers grown at RT on the Si(111) surface were investigated by means of the low energy electron microscopy and low energy electron diffraction techniques. The diffusion of silicon atoms from the Si substrate through the Au film to its surface caused the formation of the low buckled phase of silicene. Although at room temperature the silicene layer was poorly ordered, the post-deposition sample annealing increased the size of silicene domains. The silicene layer was built of four rotated domains and remained as the only phase up to about 425 K. Above that temperature, besides the low buckled phase, the planar phase of silicene was also formed. Similarly, it consisted of four main domains. Each domain of the planar silicene had its counterpart in the low buckled phase. The domains of both phases were rotated in respect to each other, resulting in the appearance of characteristic superstructures in the LEED patterns: (√3 × √3), (√7 × √7) and (√21 × √21). Both silicene phases formed very well-ordered layered heterostructures covering the entire sample surface with the size of the order of cm


Single-crystal monolayer graphene with a lateral size of 800 μm can be grown on the back of copper foils after 60 min of growth. Raman spectroscopy revealed the single-crystal graphene to be in uniform monolayers with a low D-band intensity.The nucleation of graphene at different locations in the quartz boat was studied, and the lowest nucleation density of graphene in the quartz boat was found. The nucleation density of graphene is the lowest at the bottom of the quartz boat near the gas inlet side. Based on the above results, a simple and reproducible way is proposed to significantly suppress the nucleation density of graphene on the copper foil during the chemical vapor deposition process. Placing the copper foil with an area of 1.3 cm × 1 cm in the middle of the bottom of the quartz boat or further back, and placing two copper pockets in front of the copper foil, an ultra-low nucleation density of ~42 nucleus/cm Graphene is composed of two-dimensional carbon atoms assembled in a hexagonal structure, akin to a honeycomb, and has exceptional chemical stability, superior mechanical stability, and very high thermal conductivities and electronic conductivities ,2,3. BecIt is still a challenge to grow large-size single-crystal graphene. There are two ideas to improve the size of single-crystal graphene, which are the single-seed method and the multi-seed method . The key2 was achieved. After increasing the growth time to 60 min, single-crystal monolayer graphene with a lateral size of 800 μm can be grown on the back of copper foils under the optimized growth condition. In addition, the Raman study indicates that the single-crystal graphene synthetized by our method has a very low D-band intensity on the silicon dioxide grown on Si wafers, which is of high quality.In this paper, the nucleation of graphene at different locations in the quartz boat isexplored through three groups of comparative experiments. Based on the results of these experiments, we report a simple and reproducible way to significantly suppress the nucleation density by placing the copper foil with an area of 1.3 cm × 1.0 cm in the middle of the bottom of the quartz boat, or further back, and placing two copper pockets in front of the copper foil. Nucleation density of graphene on the back of copper foils can be significantly reduced and an ultra-low nucleation density of ~42 nucleus/cm2:CH4 = 50:50:0.5 (in the unit of sccm), and growth time of 45 min. After studying the nucleation of graphene at different locations in the quartz boat, a new growth mode was used. A piece of copper foil with an area of 1.3 cm × 1.0 cm was prepared and then placed at the middle position of the bottom of the quartz boat. The distance between the copper foil and the bottom of the quartz boat was 0.5 cm, and the center of the copper foil was about 4 cm away from the tail of quartz boat . At the same time, two copper pockets were placed in front of the copper foil in order to further reduce the methane flow at the bottom of the quartz boat, as shown in Figure 6a. Finally, the quartz boat with copper foils was placed into the quartz tube and the growth test was carried out in the center of the heating furnace. The growth parameters were as follows: furnace temperature 1030 °C, Ar:H2:CH4 = 50:50:0.5 (in the unit of sccm), and growth time of 60 min. Each group of experiments was repeated multiple times, until the results were stable.Graphene was synthesized by the low-pressure CVD in a tube furnace. The copper foils were folded into copper pockets, and a Cu pocket was made by first bending a copper foil  and then crimping or pressing the three open edges carefully by using metal tweezers . The cop4)2S2O8) aqueous solution . After etching, the PMMA/graphene was rinsed in DI water several times. The PMMA/graphene was dried in a desiccator and then placed on the SiO2/Si substrate. The PMMA layer was dissolved using hot acetone .A thin film of polymethyl methacrylate (PMMA)  was spin-coated onto the graphene/Cu (600 r/min for 6 s then 3000 r/min for 40 s). The etching of Cu usually takes 3 h. Then, the PMMA/graphene/Cu thin film was placed into 30 mg/mL ammonium persulfate  and the nucleation density of graphene was very low. There were only about 102 nucleation sites of graphene in the area of 3.5 cm × 2 cm, and the nucleation density of graphene is 27 nucleus/cmThe above four groups of experiments were carried out multiple times in each group. The distribution of the nucleation density of graphene at four locations in the quartz boat was obtained after stable results appeared. We found that the nucleation density of graphene at the bottom of the quartz boat (location 2 or location 4) was lower than that at the top (location 1 or location 3), and the closer to the gas inlet side (location 1 or location 2), the lower the nucleation density of the graphene in the copper pockets method. In the copper pockets method, the growth of single-crystal graphene depends on the smooth inner surface of the copper pockets during the growth process. The smoothness of the inner surface is created by the dynamic balance of the evaporation and deposition of copper inside copper pockets . In addi2  were placed at the bottom of quartz boat, and two copper pockets were in front of this, single-crystal graphene could be stably obtained on the surfaces of copper foils. 2 under this condition. Based on the above results, we proposed a simple and reproducible way to synthesize single-crystal graphene. A copper foil with an area of 1.3 cm × 1.0 cm was placed on the middle of the bottom of the quartz boat, or further back, and two copper pockets were placed in front of the copper foil, as shown in 2D/IG intensity ratio was ~1.2, and there was no obvious D peak. High-quality graphene was obtained by our growth and transfer method.By placing copper foils on the bottom of the quartz boat . The single-crystal graphene with a diameter of 800 μm can be obtained directly on copper foils by our method after growing for 60 min. Raman spectroscopy revealed the single-crystal graphene to be in uniform monolayers with a low D-band intensity. The single-crystal graphene prepared in our work can be used in many kinds of 2D electronics, such as flexible electrodes and flexible field effect transistors, because of its ultra-high carrier mobility and excellent flexibility.


The cables of high-strength carbon fiber reinforced polymer (CFRP) plates are starting to be applied to large spatial structures. However, their main anchorage systems rely on the adhesive force, which entails risks to their integrity resulting from aging of the binding agent. In this study, a friction-based wedge anchorage system was designed for CFRP plates. The working mechanism of the proposed anchorage system was explored both theoretically and experimentally. The anti-slip mechanism and condition of CFRP plates were formulated so that the equivalent frictional angle of the contact surface between a CFRP plate and wedges must not be smaller than the sum of the dip angle of the wedge external conical surface and the frictional angle between the wedges and barrel. An analysis of the stress distribution in the anchorage zone of the CFRP plate was conducted using the Tsai-Wu failure criterion, which concluded that the compressive stresses should be reduced on the section closer to the load-bearing end of the anchorage system. Furthermore, the anchorage efficiency coefficient was proposed, which depends on stress concentration coefficients, plate thickness, length of anchorage zone, dip angle of wedge external conical surface, and its frictional angle. Then, it was determined that the minimum length of an anchorage zone for the CFRP plates with various specifications should be at least 49 times larger than the CFRP thickness. A finite element analysis and static tensile tests on six specimens were carried out. The experimental results revealed that the anchorage efficiency coefficient of the optimized anchor reached 97.9%. Carbon Fiber Reinforcement Polymers (CFRPs) have excellent corrosion resistance, light weight, and high strength. They can also be conveniently used in construction ,2. CFRP While CFRP plates have the potential to be used in high-tension cables, their effective anchorage is a precondition for this type of application . HoweverIn order to facilitate wider application of CFRP plates in civil engineering, a friction-based wedge anchor for CFRP plates is proposed in this study and its design method is systematically developed. The proposed anchorage structure uses mechanical friction and biting force, which eliminates the problem of aging-related binder failure of traditional anchorages. Furthermore, the proposed anchorage structure is small, safe, and convenient in construction, which will aid its practical applications. The optimal design of the anchorage is studied considering slip resistance, stress redistribution, and factors influencing the anchorage efficiency to determine the key dimensions of anchorage device. Finite element simulations and static tension tests were also carried out. In the latter, a 50 × 3 mm CFRP plate anchorage was tested and validated, and the next step will be to conduct tests on other commonly used CFRP plate anchorages.A diagram of the proposed anchorage system is shown in The failure of a wedge-type anchor for CFRP plates can generally be of three types : slip faα and β are the taper and frictional angle of wedge external conical surface, respectively.The friction-based wedge anchor had two key contact interfaces. The contact interface between the barrel and the wedge is referred to as Interface 1, while that between the CFRP plate and wedge as Interface 2. The wedges are required to self-lock after the CFRP plate is tensioned so that retraction does not occur when the tensile force in the CFRP plate decreases, thus the following should be satisfied:F is the tensile force in CFRP plate, and f1 and N1 are the frictional and normal force acting on Interface 1, respectively. It can be demonstrated that:After wedge self-locking, the anchorage system can be treated in the analysis as a plane-symmetric model . The equμ is the frictional coefficient of Interface 2, and f2 and N2 are the frictional and normal forces acting on Interface 2, respectively.To ensure that the CFRP plate does not slip along its contact interfaces with the wedges, the frictional resistance generated by the wedges and the CFRP plate should be greater than the tensioning force in the CFRP plate. A free-body diagram for the CFRP plate can be analyzed considering only the frictional resistance between the CFRP plate and the wedges, leading to the following condition :(4)F≤μN2Combining Equations (3) and (4), the following relationship can be obtained:θ is the equivalent frictional angle of the contact interface between CFRP plate and wedges, then:If The tensile and compressive stress distributions inside the anchor in safe state were obtained according to the relevant strength theories, and the stress redistribution mechanism was further elucidated to guide the design of the anchorage system. The strength theories commonly adopted for composite materials include maximum stress theory, maximum strain theory, Tsai-Hill theory, and Tsai-Wu theory ,33. The σ1, σ2, and σ6 are the longitudinal, transverse, and shear stress, respectively. Coefficients iF and ijF, which are related to the strength of CFRP plate material, can be obtained from experimental data according to the following formulas:Xt and Xc are the longitudinal tensile and compressive strength, respectively, Yt and Yc are the transverse tensile and comprehensive strength, respectively, and S is the shear strength. The high-strength CFRP plates investigated in this study were formed through the pultrusion process, and the carbon fiber yarns were parallel and uniformly distributed in the longitudinal direction. Therefore, Xt was determined based on the strength of carbon fiber yarns, and it was taken as Xt = 2400 MPa according to the yarns strength grade adopted in engineering applications. The compressive and tensile strengths of CFRP plate in other directions were obtained from the corresponding values for the isotropic epoxy resin matrix. It was experimentally determined that Xc = Yt = Yc = 120 MPa [F2 = 0. Strength Xc of the CFRP plate was much smaller than Xt, thus the limiting value of two-way tensile failure test mainly depended on the ultimate compressive strength; thus, σ6 = 0, because the longitudinal and transverse directions of CFRP plate were essentially identical with the directions of the principal stresses in the anchor. Using σ6 = 0, the following simplified formulas were obtained:When the CFRP plate is in a linear elastic state, the left-hand side of the above equation must not exceed 1. In a planar stress state, the expression for orthotropic material can be transformed into the following form: 120 MPa , and theIt was assumed thatThe expressions were simplified using MATLAB, and then the relationship between the tensile stress and compressive stress of the CFRP plate in the anchorage zone in safe state was obtained as follows:n segments along its length. Each section of the CFRP plate was subjected to a vertical normal force, iN, and longitudinal frictional resistance, iF, as shown in Starting from the load-bearing end, the anchor was divided into i of CFRP plate, respectively, and i1k and i2k are the tensile and compressive stress concentration coefficients of segment i of CFRP plate, respectively.Given that any nonuniform contact between the wedges and the CFRP plate will lead to a concentration of longitudinal tensile stress and vertical compressive stress, the following notation is adopted:According to Equation (15), the relationship between tensile and compressive stress of each segment in safe state should satisfy the following:i of the CFRP plate can be expressed as follows:S is the cross-sections area of segment i  of the CFRP plate.Due to the frictional forces between the wedge and the CFRP plate, the longitudinal stress in the CFRP plate will be gradually reduced moving away from the load-bearing end. The average longitudinal tensile stress in segment k1 and k2, of all sections are assumed to be equal, and then:The stress concentration coefficients, Under the ideal state, the stress concentration coefficients remain the same in each segment thus for any section, the following holds true:S is the sectional area of the CFRP plate , and hS is the contact area between the CFRP plate segment and the wedges . The formulas for the areas were substituted into the above equation to obtain:The ultimate stress in the stress concentration zone on each section is required to be equal, and it was substituted into Equation (20) to obtain the following:k2 · n · d/L, and then:To simplify the formula, it was assumed that As segments closer to the load-bearing end have greater values of expression It can thus be concluded that the clamping stress of sections closer to the load-bearing end should be smaller, and a suitable compressive stress adjustment mechanism should make it possible for the wedges to gradually press the CFRP plate tightly from the large end to the small end.bF is the standard ultimate tensile force of the CFRP plate.From Equations (19) and (24), the following can be deduced:iF, of each segment was assumed to be proportional to the clamping force, iN, namely:k is the proportionality coefficient, k = 2tan(α+β). Then:The frictional resistance, As Hence:By substituting Equation (30) into Equation (26), the following is obtained:The relationship n is a large number, thenIf pkF, of the anchorage system, F should still satisfy Equation (34).When reaching the ultimate breaking force, The following relationships can be obtained using the anchorage efficiency coefficient, mA, was defined as follows:The anchorage efficiency coefficient, The following conclusions can be obtained from Equations (36) and (37):Am, depends on the stress concentration coefficients (k1 and k2), plate thickness (d), length of anchorage zone (L), taper of wedge external conical surface (α), and its frictional angle (β). Larger values of Am correspond to better anchorage system performance.(1) The anchorage efficiency index, k1 and k2 correspond to higher values of the anchorage system efficiency coefficient. In order to ensure high anchorage performance, the geometric parameters of the anchorage system should be selected such that Am exceeds 1.0 and k1 is not greater than 2.(2) Smaller values of stress concentration coefficients α) and frictional angle of wedge external surface (β), the higher the anchorage efficiency coefficient, but this is restricted by equation (6), namely, protecting the CFRP plate from slipping.(3) The greater the sum of the taper of wedge external conical surface (d), the longer the anchorage zone (L) required, and the two are in direct proportion to each other. Moreover, their ratio affects the anchorage system performance, and smaller ratios produce higher anchorage efficiency coefficients.(4) The greater the thickness of CFRP plate (The key geometric parameters of the anchorage system can be determined according to Equations (1), (6), (25) and (36) as follows:α and β(1) Determination of α and β of anchorage systems with different specifications in the same anchorage system are essentially identical. Using the frictional coefficient of contact interface under high stress determined by Huang [β = 14°, which decreased to 7° after a lubricating agent was applied. To pull smoothly the wedge into the barrel, α should not be too large, and it was taken as 4°, which met the requirement of Equation (1).In general, the values of by Huang , the fri(2) Determine the parameters of the contact interface between CFRP plate and wedgesk1 and k2) as much as possible, emery was sprayed evenly on the clamping surfaces of the wedges instead of suing indentations or tooth, thus the damage caused to the CFRP plate was very small. Following Meng [α and β was 18°. The non-slip requirements for the CFRP plate were already satisfied by Equation (6).In order to reduce the stress concentration coefficients  Determination of k1 and k2 were both taken as 1, and that of β as 7°, all of which were substituted into Equation (36) to obtain the minimum anchorage length of CFRP plate as follows:The length of the anchorage zone should be as short as possible in order to reduce the size and weight of the anchor. The anchorage systems in the same system should be designed according to the same anchorage efficiency coefficient and stress concentration coefficient. As stipulated in the standard , the ancFurthermore, the anchorage lengths of the CFRP plate commonly used in engineering practice were determined as shown in (4) Selection of barrel and wedge materialsCr steel has good toughness and high strength and was selected as the barrel material, because it will have to bear safely a large circumferential tensile stress. Its elongation ratio is greater or equal to 9%, the yield strength and ultimate tensile strength are 785 MPa and 980 MPa, respectively. The wedges should be made of soft steel in an effort to mitigate the stress concentration in the CFRP plate. To reduce cost, the wedges can be made of A3 steel or 45 steel without heat treatment. The 40(5) Determination of contact parameters between barrel and wedgesThe dip angle of wedge external conical surface was set to be slightly larger than that of the barrel, and the big ends of wedges were the first ones to contact the barrel so that the compressive stress distribution could meet the requirements of Equation (25). In general, the optimal performance was reached when the difference between the two angles was 10 min, which was adjusted according to the static loading test results.The anchorage of a 50 × 3 mm CFRP plate was taken as an example for finite element analysis to obtain the stress distribution in the optimized anchor. Using symmetry, a 1/4-model of the anchorage device was formulated.The material of the barrel was 40Cr steel, with elastic modulus of 210 GPa and Poisson’s ratio of 0.3. The material of the wedges was 45 steel, with an elastic modulus of 206 GPa and Poisson’s ratio of 0.3. The elastic modulus of the CFRP plate was 160 GPa, Poisson’s ratio 0.25, and standard strength 2,400 MPa. The friction coefficient between the barrel and wedges was assumed as 0.24  and thatThe finite element mesh is shown in The stress in the barrel was mainly concentrated at the end of the large hole where it contacts the wedge. The maximum stress in the wedge occurred also in the contact area with the barrel. The maximum von Mises stresses in both components were smaller than their yield strengths. Thus, the finite element analysis verified the correctness of material selection for the barrel and wedges to ensure appropriate safety margins, as discussed in Point (4) in As seen in The anchor was optimized for the CFRP plate with a strength of 2400 MPa and sectional area of 50 mm × 3 mm. The length of barrel was taken as 150 mm and the blanking length of CFRP plate as 1500 mm. The length of free section of the specimen was ensured to be greater than 1000 mm. Six CFRP plate anchors were assembled to perform a static tensile test. A specimen with the assembled anchor is shown in A schematic diagram of the testing apparatus is shown in bF. After straightening of the CFRP plate and confirming the apparatus was working correctly, the specimens were unloaded and the initial readings were recorded. The main loading test followed the phased multi-stage loading protocol: The multi-stage loading was conducted using 5% of bF in the initial phase. After the load reached 60% of bF, the multi-stage loading was implemented according to 2% of bF. When the load reached 70% of bF, it was held for 5 min, and then increased continuously until the specimen failed. The loading rate was controlled within 0.05–0.07 mm/s.First, specimens were preloaded to 5% of Each specimen suffered tensile fracture. As the load increased, the CFRP plates started cracking from the middle towards both sides, then damage gradually extended to the anchors, and plates disintegrated into individual carbon fiber yarns in a sudden explosion. Each failed specimen presented the characteristic burst shape. The tensile failure of specimens was always due to breaking of carbon fiber yarns, as shown in After the test, the wedges were withdrawn, and the barrel, wedges, and CFRP plate were inspected. The barrel and wedges were intact, as shown in The emery sprayed on the wedges was cleaned, which revealed the bite marks left on the surface by squeezed emery, as shown in There were obvious signs of extension and emery biting into the surface of the anchorage area of the CFRP plates, as shown in The results of the static tensile test are summarized in To investigate the effect of the wedge on the CFRP plate during tensioning, the force- displacement curves were plotted for the six experimental specimens in α, β and L in Points (1) and (3) in The force-displacement curves of the six specimens were consistent with one another. During the loading process, the displacements of the CFRP plates increased linearly and rapidly with the load without sudden changes, which indicated that the stiffness of the CFRP plates did not change significantly during the tensioning process, and no slip occurred. This shows that by the suitable selection of parameters Except for Specimen 1, in the remaining specimens adding lubricant reduced the friction coefficient between the barrel and the wedge, and the displacement of Specimen 1 was larger than the rest of the specimens. This further verified the assumption made in Point (1) in In this study, a design method for a friction-based wedge anchorage system for high-strength CFRP plates was systematically developed and investigated. An anti-slip condition for the anchor assembly of CFRP plates was derived. Then, the factors influencing anchorage performance and their effect were analyzed using the Tsai-Wu failure criterion. Mathematical expressions for the relationships between the anchorage efficiency coefficient and the influencing factors were derived, and the key geometric parameters of the anchorage system were determined. A finite element analysis and a static tensile test were performed to better prove the proposed method soundness. The following conclusions were drawn:(1) The equivalent frictional angle of the contact interface between the CFRP plate and wedges should not be smaller than the sum of the dip angle of the wedge external conical surface and the frictional angle between wedges and barrel, to prevent the CFRP plate from slipping out of the anchorage system.(2) The compressive stress of the section closer to the load-bearing end of the anchorage system should be reduced. The dip angle of wedge external conical surface should be slightly larger than that of the barrel, with the angle difference of 10 min. In this way, the wedges can clamp the CFRP plate tightly from the large end to the small end and improve the anchorage performance.Am, is determined by the stress concentration coefficients (1k and 2k), plate thickness (d), length of anchorage zone (L), taper of wedge external conical surface (α), and its frictional angle (β). The optimal design of an anchor for CFRP plates can be achieved using the design expressions. The minimum anchorage length of CFRP plates with various specifications was determined as L ≥ 49d.(3) The anchorage efficiency coefficient, (4) The results of the static tensile test of anchor assemblies for CFRP plates demonstrated that all optimally designed specimens satisfied the anchorage requirements. The wedges can be easily pulled into the barrel under the low-stress state after a lubricating agent is applied to their interfaces, which can further increase the anchorage efficiency coefficient (up to as high as 97.9%). It was verified through the tests that the optimally designed anchor provides reliable and efficient anchorage.


Bipolar disorder (BD) is amongst the most common heritable mental disorders, but the clarification of its genetic roots has proven to be very challenging. Many single nucleotide polymorphisms (SNPs) have been identified to be associated with BD. SNPs in the CACNA1C gene have emerged as the most significantly associated with the disease. The aim of the present study is to provide a concise description of SNP 1006737 variants identified by Real Time PCR and confirm sequencing analysis with the Sanger method in order to estimate the association with BD. The molecular method was tested on 47 Sardinian subjects of whom 23 were found to not be mutated, 1 was found to be a carrier of the homozygous A allele and 23 were found to be carriers of the heterozygous G allele. Moreover, the positive results of the preliminary application suggest that the development of the screener could be extended to the other 5 genetic variables identified as associated with BD. Bipolar disorder (BD) is amongst the most common heritable mental disorders, but the clarification of its genetic roots has proven to be challenging . The gen2+ channel, CACNA1C provides the depolarization of neurons through calcium ion influx [One of the candidate genes most commonly associated with bipolar disorder is the CACNA1C gene. This gene encodes the alpha-1 subunit of voltage-gated calcium channel CaV1.2 . Moreoven influx . To daten influx , 9. The n influx , 11.The genetic roots of BD underpin an evolutionary basis for the persistence of the disorder in the general population despite its impact on morbidity, mortality, and quality of life , 13. AffMany single nucleotide polymorphisms (SNPs) have been identified to be associated with BD. SNPs in the CACNA1C gene have emerged as the most significantly associated with the disease. The aim of the present study is to provide a concise description of SNP 1006737 variants identified by Real Time PCR and confirm sequencing analysis with the Sanger method, to estimate the association with BD.th, 2019 (reference number NP / 2019 / 1003).A total of 47 Sardinian subjects were examined using oral mucosal samples collected with oral swabs and stored in 1 ml eppendorf tubes containing 400 µl of 0.5 M EDTA and dimethyl sulfoxide. 16 subjects were BD patients with comorbid conditions, such as anxiety, psychosis and depression from the Centro di Psichiatria di Consultazione e Psicosomatica (CPCP- AOU Cagliari). Overall, 9 BD patients manifested familiarity concerning bipolar disorder, anxiety, depression and psychosis. Other 31 subjects were part of the control group. Regarding them, 27 subjects were from Sardinia, while 3 Sardinians residing in France and 1 Sardinian residing in Brazil. The Committee of the “Azienda Ospedaliero-Universitaria di Cagliari”, Cagliari, Italy, approved the study on February 27e.g., DNasy Blood & Qiagen Tissue Kit). The molecular system involves the use of a Fluorescence Resonance Energy Transfer (FRET) probe [DNA was extracted using a specific extraction kit for tissue fragments (T) probe  that wasT) probe -22. One In the PCR apparatus, this result has been visualized by a shift in the melting peak, monitoring the F2 fluorescence during the heating of the sample -26.Our work is an indicator of a good possibility of allelic diversity for this gene region by evaluating the melting temperatures. To confirm the specificity of the method, some samples were analyzed by Sanger sequencing. Regarding this step of the study, we used Real-time PCR mutation analysis with FRET probes as a method used to differentiate A and G alleles in SNP rs1006737. FRET probes are able to distinguish the presence of both G and A alleles with specificity and selectivity errors (heterozygous profile).Overall, the molecular method was tested on 47 subjects, of whom 23 were found to not be mutated, 1 was found to be a carrier of the homozygous A allele and 23 carriers of the heterozygous G allele.The preliminary results seem to indirectly confirm the starting hypothesis according to which a genetic condition is being explored that can give rise to contrasting phenotypes in terms of adaptation. Additionally, the proposed technique appears innovative, interesting and practicable. The preliminary application showed that the development of the screener can also be applied to the other 5 genetic variables identified ; in fact, with the analysis of a single variable, there is a tendency to identify the target object, that is the screener that identifies the spectrum of bipolar disorder.


In this paper, the response surface methodology (RSM) was proposed for studying the synergistic extraction of chromium(III) ions by double-carrier supported liquid membrane (DCSLM) with organophosphorus carriers (D2EHPA/Cyanex272). At first, the optimization method of “one-factor-at-a-time” was adopted for determination of the best conditions for Cr(III) extraction by SLM with only one carrier (D2EHPA). The optimum/threshold D2EHPA concentration in the membrane phase increased linearly with initial concentration of Cr(III) ions in the feed phase. After the addition the second carrier (Cyanex272), the synergistic effect was observed. The largest percentage of extraction and the shorter time was obtained. The optimization of the synergistic extraction in DCSLM system by RSM using Box–Behnken design (BBD) for three variables , and time of the process) was studied. The statistical model was verified with the analysis of variance (ANOVA) for the response surface quadratic model. The reduced quadratic model showed that the predicted values were in agreement with those obtained experimentally, as well as the fact that the concentrations and proportions of the carriers had a significant influence on the response. The developed model was considered to be verified and can be used to predict the optimal condition for the chromium ions extraction. Heavy metals  and their compounds are among the worst water contaminants. They accumulate in the sediments and are toxic for living organisms. The highest oxidation state of chromium is +6, the lowest is −2; the +3 and +6 states are most common in chromium compounds. It is still problematic to remove chromium from wastewater efficiently . On the When many factors and interactions affect desired results, response surface methodology (RSM) is an effective tool for optimizing the process ,10,11. RSome authors ,14,15,16In recent years, the results of research on the optimization of the membrane separation process using RSM have been published increasingly more often ,14,15,16This work is devoted to the optimization of the chromium(III) separation process using experimental and statistical studies. The study presents the influence of the main process parameters  on the possibility of separation of Cr(III) from acid solutions with a double carrier supported liquid membrane. The research was carried out using the most commonly used organophosphorus carriers of the Cr(III) ions: bis(2-ethylhexyl) phosphoric acid (D2EHPA) and bis phosphine acid (Cyanex272) ,4.The optimization method of “one experimental parameter at a time” was adopted for determination of the best conditions of Cr(III) recovery, from acidic aqueous solution by SLM with only one carrier (D2EHPA). In the next step, the modelling of the process was achieved by response surface methodology (RSM) using Box–Behnken design (BBD). BBD was used because, as reported by other authors ,12, it i3 6H2O, ≥96% purity), hydrochloric acid (HCl), kerosene, and 1.5-diphenylcarbazide were obtained from Sigma-Aldrich, Poland. O-ksylene was purchased from Fluka, Poland. All chemicals were of analytical and reagent grade and were used as received without further purification. All aqueous solutions were prepared using deionized water. The immobilized liquid membrane was a PTFE porous polymer film with a pore size of 0.45 mm and porosity of 64% obtained from Sartorius, Germany.Bis phosphinic acid (Cyanex272) was purchased from Cytec, Canada. Bis(2-ethylhexyl) phosphoric acid (D2EHPA) was purchased from Merck, Germany. Both substances were used to as an ions carrier. Chromium(III) chloride hexahydrate (CrCl3 each) equipped with a mechanical stirrer each, and immersed in a water bath, pH meter , and thermostat with temperature and water level control system to ensure proper process temperature. Chambers were separated by membrane (active area 15.2 cm2) prepared by soaking PTFE porous polymer film for 24 h in a mixture of the carriers and organic solvents. The final concentration of the carriers in the membrane was changed in the range of 0–80 % v/v, while the volume concentration ratio of the kerosene/o-xylene was constant and equal to 2:1.A detailed diagram of the experimental laboratory-scale unit has been reported elsewhere . The sep3. As the stripping solution, 6 M HCl aqueous solution was used. The initial pH of the feed phase was equal to 4. The separation process was carried out at ambient temperature (T = 25 ± 0.5 °C) and atmospheric pressure. The samples were collected both from feed and receiving phase in the defined time intervals Feed solutions were prepared by dissolution the appropriate amount of the chromium(III) chloride in the deionized water. The final concentration was in the range of 0.025 to 1.000 g/dmThe spectrophotometric method was used for the Cr(III) ion concentration determination. Analysis was conducted using a NANOCOLOR UV/VIS NUV480 spectrophotometer  equipped with quartz cuvette cell, with path length of 1 cm. After solution intake, the sample was mineralized. The residue was diluted in deionized water, and stock solution of 1,5-diphenylcarbazide was added. The solution absorbance was measured at wavelength λ = 540 nm with a spectrophotometer. The concentration of the Cr(III) ions was read from the calibration curve. Each measurement was repeated three times. The Cr(III) ions concentrations are the average of the results obtained with the standard deviation value ± 0.0003.In accordance with previous studies ,4, threeThe liquid membrane extraction process is most often studied using the one-factor-at-a-time (OFAT) method. In this method, one process variable is changed at a time, while others are kept on the same fixed level. This approach has several disadvantages, e.g., problems with the estimation of the interaction between process parameters may lead to overlooking optimal solution, and it is a time- and labor-consuming method. In recent years, design of experiments (DoE) and response surface methodology (RSM) are more willingly used to study, analyze, and optimize different industrial and laboratory processes ,12.The design of experiments (DoE) method is used for the selection of independent variables (process parameters) significantly affecting the process, development of the mathematical model fitting the obtained data, and the process optimization. The correct application of the method requires a multistep approach: defining the problem , strategy selection (selection of the variables or process optimization), design of the experimental matrix, conducting experiments, analysis of obtained data, development of the mathematical model and its evaluation, and model validation. ix is the coded value of the i-th independent variable, iX is the the real/uncoded value of the i independent variable, Xi,0 is the real/uncoded value of the i independent variable at the center point, and ΔiX is the step change value of iX determined from Equation (2).Xi,max is the maximum real value of the i-th independent variable, and Xi,min is the minimum real value of the i independent variable in the experimental space.The analysis of the obtained experimental results is carried out on normalized (coded) variables. Normalization of variables is the transformation of the independent variable real values into dimensionless values according to Equation (1).Y is the predicted response, kx is the coded value of independent variables, k is the number of independent variables used in the study, b0 is the constant, ib is the linear model coefficients, ijb is the linear model coefficients for interaction, and iib is the quadratic model coefficients.To find the optimal solution, it is necessary to use the polynomial function containing quadratic expressions. Most often, the second-degree polynomial equation is used (Equation (3)).ib statistically significantly differ from 0, then the corresponding independent variables ix influence the response.The obtained experimental results are used to calculate model coefficients. Then, the determination coefficients value are used to check the fit of the regression model to experimental results. The application of Fisher’s test allows for the determination of the individual model coefficients’ statistical significance. If the regression coefficient In the first step of the study, the optimization method of “one experimental parameter at a time”, was adopted to establish optimal conditions for the separation of the Cr(III) from acidic aqueous solution by SLM with D2EHPA carrier. To determine the effect of the concentration of the D2EHPA on the transport of Cr(III) ions in the studied system, we carried out the process for different initial concentrations of D2EHPA in the membrane and different initial concentrations of Cr(III) ions in the feed phase. The results of the experiments illustrated in It was observed that regardless of the initial Cr(III) concentration, there was a certain threshold concentration of the D2EHPA in SLM that guaranteed the highest efficiency of the process. The value of D2EHPA threshold concentration in SLM increased linearly with the initial concentration of Cr(III) ions in the feed phase , Table 3max) was the shortest, and consequently the process rate was the fastest (max). For example, for the initial concentration Cr(III) = 0.025 g/L, it was 0.5 h, while for 1.0 g/L, time extended to 10 h.The time to reach the maximum extraction percentage  concentration is a limiting factor for the extraction efficiency in the SLM system. As reported by the authors ,20, highIn previous works ,4, we ha2 and adjusted R2 achieved. Therefore, the quadratic equation was selected for further analysis.BBD for the process variables of DCSLM is shown in 2 and adjusted R2 was larger than the recommended one (>0.2). This may demonstrate a large block effect or problems with models or data. The achievement of statistically significant value lack of fit (0.0497) is the incompliance of this model as this parameter should be statistically non-significant.The statistical model was verified by employing ANOVA for the response surface quadratic model. As can be seen in 2, adjusted R2, and predicted R2 coefficients were achieved. Results of ANOVA are presented in c is Cyanex272 concentration, B is the initial Cr(III) concentration, and C is the time of the process. At a further stage of analysis, statistically non-significant terms of the initial equation were eliminated from the analysis. The reduction was made using a step-by-step method (from the most insignificant term). For both these response variables, only statistically significant terms were left, and higher RAs seen in 2 shows the prediction of a response value estimated by the model. The difference between adjusted R2 and predicted R2 was expected to be in the range of 0–0.200 for the adequacy of the model. On this occasion, the predicted R2 of 0.6142 was in reasonable agreement with the adjusted R2 of 0.8073. Adequate precision is an estimation of the signal to noise ratio. A ratio greater than 4 is desirable, and hence the ratio of 13.069 implies an adequate signal. Therefore, this model can be used to navigate the design space.Predicted RIn A Design Expert program was employed to plot the fitted response surface to understand the interaction of the most important parameters required for the optimum condition for the extraction of chromium(III). The plots are illustrated in v/v) improved percentages of extraction of chromium(III) because of the higher available Cyanex272 reacting with Cr(III) ions at the interface of feed phase [v/v Cyanex272 reduced the tmax of the Cr(III) ion pertraction to the membrane phase and improved the extraction percentage, regardless of the initial Cr(III) ion concentrations (v/v), the percentage of extraction decreased because of the limited mass transfer rate of Cr(III) ions across the liquid membrane phase. The increase in the concentration of Cyanex272  concentration, and C is the time of the process.Using the same methodology, we analyzed the effect of D2EHPA concentration on extraction with the Cyanex272 threshold concentration in DCSLM . The aim2 of 0.7603 was in reasonable agreement with the adjusted R2 of 0.8913. The estimation of the signal to noise ratio was 14.844, and therefore this model can be used to navigate the design space.The statistical model was verified by employing ANOVA for the response surface quadratic model. As can be seen in The 3D response surface plots and the contour plots are drawn visually to illustrate the main and interactive effects of the independent variables in v/v Cyanex272 and 30–40% v/v D2EHPA) allows for the obtaining of the largest percentage of extraction, regardless of the initial concentration of Cr(III) ions. Moreover, the results summarized in The results show that the presence of two carriers in a suitable ratio (5% The addition of a second carrier (Cyanex272) threshold concentration to DCSLM allowed for an increase of 30% more of the concentration of D2EHPA in the membrane phase . The prev/v Cyanex272/30% v/v D2EHPA). The maximum extraction of about 99% was observed for a low concentration of Cr(III) ions < 0.2 g/L after 3 h. For higher initial concentrations of Cr(III) ions > 0.3 g/L, the extraction percentage decreased up to 50 %. Analysis of the pH of the feed phase during the process with high initial Cr(III) ion concentration (>0.3 g/L) (0.3 g/L)  showed tv/v Cyanex272 and 20% v/v D2EHPA. The two other parameters (Cr(III) concentration and extraction time) were changed in the range of the experimental design limits. The experimental conditions, value of response predicted by model and experimental result, and statistical parameters  are shown in The developed mathematical model was verified by conducting four additional experiments. The carrier ratio was set on a constant level of 5% 2 87.17%). Thus, the developed model was considered to be verified and can be used to predict the optimal condition for the chromium ion extraction.A satisfactory correlation was noticed between the experimental data and predicted values  ions from aqueous solutions by the supported liquid membrane with D2EHPA carrier showed that the initial Cr(III) ion concentration is a limiting factor for the extraction efficiency. There is a threshold  concentration of the D2EHPA in SLM that guarantees the highest efficiency of the process. The value of D2EHPA threshold concentration increased linearly with increasing initial concentration of Cr(III) ions in the feed phase. Moreover, the synergistic effect was observed, which was characterized by an increasing in extraction efficiency after adding the second carrier (Cyanex272). The addition of threshold Cyanex272 concentration to SLM allowed for an increase of 30% more of the concentration of D2EHPA in the membrane phase. This increased the extraction percentage of the Cr(III) ions to the membrane phase and shortened the time of the maximum Cr(III) ion extraction to the membrane phase.v/v Cyanex272 and 30–40% v/v D2EHPA) allowed for the obtaining of the largest percentage of extraction, regardless of the initial concentration of Cr(III) ions compared to a SLM with only D2EHPA. In the case of low initial concentration of Cr(III) ions (<0.1 g/L), a reduction in the total extraction time was also noted.The presence of two carriers in DCSLM in a suitable ratio (5% The modelling of the process was achieved by response surface methodology (RSM) using Box–Behnken design (BBD). The DCSLM system has been successfully optimized. The experimental design, regression analysis, and quadratic models developed using response surface methodology according to BBD for the extraction efficiency were noticed to be reasonably accurate and effective in predicting the value of the response within the limits of the factors investigated. The reduced cubic of the quadratic model showed that the predicted values were in good agreement with those found experimentally, and the parameter of carrier concentrations/proportion had an important effect on the response.A response surface methodology is an effective tool for optimizing the separation process using the supported liquid membrane technique. This tool greatly helps in carrying out research because it allows for the reduction in research time and minimization of its costs.


Competence-based learning must be integrated into the practical development of Physiotherapy. Teamwork, interpersonal relations, analytical skills or critical/clinical thinking are some examples of internationally recommended competences in this kind of university studies. Therefore, there is a need to evaluate this learning in Physiotherapy through valid tools that facilitate this task.To analyze the psychometric properties according to competences in Clinical Practices (RECOPC-FIS II) in order to assess 14 transversal or universal competences of under-graduate students in the Physiotherapy degree.rd and 4th year of the Physiotherapy degree and 202 clinical tutors who assessed these students using the RECOPC-FIS II. Different psychometric properties were analyzed: factor structure, internal consistency and sensitivity to change.A validation study was conducted with 197 students in the 3th year with respect to that of the 3rd year, reaching significant differences in all of them.The RECOPC-FIS II has a high internal consistency. Its 14 items saturate in a single factor. Regarding the sensitivity to change, the rubric showed higher scores in the Practicum of the 4The RECOPC-FIS II is a valid and reliable instrument to assess the transversal competencies of undergraduate students of Physiotherapy during their clinical practice. Therefore, it is intended to facilitate the acquisition of essential skills for the development of their professional career. The flexibility of this tool would allow its adaptation to other health science courses. Recently, there has been a paradigm shift in higher education with an increased focus on competence training. Competences are dynamic combinations of knowledge, procedures and attitudes . They reCompetence-based learning must be integrated into the practical development of Physiotherapy and, due to their nature, competences can only be reached in the final stages of a training process –4. One oQuality improvement has been advocated in the European higher education area . CompeteWithin competences, we can consider the universal or transversal competences, which are common to most degrees, although with a different incidence, and contextualized in each degree course . These tDespite the fact that competence training has been greatly improved, using competences to guide curriculum development has proved problematic . In the Among all the courses of higher education degrees in health sciences, one of the most important is the Practicum  , 21. StuDue to the relevance of competence training included in the Practicum, it is essential to ensure its assessment, even though it is a challenge for any teacher involved in the training process , particuTo that end, it is necessary to create valid and reliable competence assessment tools to evaluate performance in the authentic practice environments related to health sciences . One of In addition, in the case of Practicums, the use of rubrics is an essential element , since tDespite their pragmatism, there are scarce rubrics published in the international literature for the assessment of Physiotherapy Practicums , 35–37. For this purpose, the RECOPC-FIS I  was created in Spain  through The RECOPC-FIS II includes 14 items related to the most relevant competences , which guide the student towards a competence itinerary that responds to the requirements of the curriculum. It evaluates oral and written communication, teamwork, interpersonal relationships, analysis and synthesis capacity, critical/clinical thinking, decision making, autonomous learning, initiative and entrepreneurship, and the capacity to adapt to new situations, among others see . HoweverThe main objective of the present study was to assess the psychometric properties of the RECOPC-FIS II, in order to have a valid and reliable tool for the assessment of transversal competences in the Practicums of Physiotherapy university programs.rd year) and P2 (4th year), 6 students only in P1 and 130 in P2. The response rate was 100% (202/202). The tutors were all physiotherapists working in public or private centres, in the specific services that each rotation required  and with at least 1 year of clinical experience. Clinical tutors were also required to sign a specific collaboration agreement with the university from which the students they were tutoring came.A total of 202 tutors completed the RECOPC-FIS II regarding the clinical practices carried out by 197 students of the degree of Physiotherapy of the University of Málaga (112 were woman: 56.85%): of which 61 were evaluated in P1 .RECOPC-FIS II is a transversal competence assessment tool that evaluates 14 competences, transformed into 14 evaluable items or criteria in this rubric for education practice, which are: C1, identification of the dysfunction or pathology; C2, physiotherapy diagnosis ; C3, therapeutic objectives; C4, integral treatment; C5, treatment planning; C6, evaluation of the results; C7, technical and manual skills in the application of therapies; C8, responsibility regarding the attention given to the patient and suitability of the clinical interventions; C9, clinical reasoning; C10, interpersonal relationships; C11, oral communication with the patient, relatives and interdisciplinary team; C12, team work; C13, disease prevention and promotion of health; and C14, autonomous learning see .The fourteen evaluable criteria of RECOPC-FIS II correspond to competences related to the learning of conceptual contents and the mastering of procedural and attitudinal contents. Some of the items evaluate several transversal competences at the same time.Furthermore, RECOPC-FIS II includes four achievement levels, to avoid intermediate values. The tutor had to select one of the four levels based on the knowledge, involvement in learning and autonomy of the student, and then give a numerical grade. For each competence, the questionnaire includes specific information about each achievement level .For the grading of the students and for this validation study, we gathered both the ratings given by the tutors to each student for each item of the rubric and the total mean of all the items for each Practicum (P1-P2).With the aim of analyzing the validity of the assessment instrument, an exploratory factor analysis (EFA) was carried out with all the items, in order to determine the accuracy of the measurement with respect to what was evaluated. Prior to the EFA, we conducted the Bartlett’s sphericity test, as well as the Kaiser-Meyer-Olkin test to determine the adequacy of carrying out this analysis. The internal consistency was calculated using Cronbach’s alpha. For these analyses, the sample consisted of 197 evaluations. Of the students who had been evaluated in both P1 and P2 (n = 61), the average of each of the competencies was calculated.Lastly, with the aim of analyzing the instrument’s sensitivity to change, we conducted the Student’s T-test for related samples, comparing each item of the corresponding scale of P1 and P2, for a group of students. Based on their knowledge and experiences, the P2 students were expected to obtain higher grades than the P1 students.All the analyses were carried out using IBM SPSS Statistics v.21.0. All relevant data are within the manuscript and its Supporting Information files .The mean score of almost all the items was around 8 points. Preliminary analyses showed that the data were appropriate for an EFA [Kaiser–Meyer–Olkin (KMO) measure of sampling adequacy = 0.97; Bartlett’s sphericity test (χ2/gl = 3363.52/91. p < .001). All the items were grouped in a single factor, which explained 76.93% of the variance. The internal consistency of the tool obtained with Cronbach’s alpha was 0.976.With the aim of analyzing the sensitivity to change of RECOPC-FIS II, 61 students were selected, who were evaluated both in P1 and then in P2. As is shown in The mean score for each item of the RECOPC-FIS II was between 7.97 for C1 (identification of the dysfunction or pathology) and 8.67 for C10  in P1; and 8.30 for C2 (physiotherapy diagnosis) and 8.93 for C10  in P2. The factor analysis showed the unidimensionality of RECOPC-FIS II , as well as a high internal consistency (Cronbach’s α = 0.976). The RECOPC-FIS II tool was sensitive to detecting improvements in all competencies, comparing the scores of P1 with those of P2.The obtained results demonstrate both the adequacy of the psychometric properties of the items and the reliability of RECOPC-FIS II. The different analyses conducted provide evidence of the validity of a 14-item structure and they show adequate statistical indices . SimilarReliability and validity analyses that have been conducted during the design of the different clinical performance assessment tools in Physiotherapy included in the review by O’Connor et al.  showed prd and 4th year who used this rubric in two consecutive academic years. All the ratings of the 14 competences were higher in the P2 group with respect to P1. The changes in the health care provided in the different clinical settings through which our students pass in the different Practicums (P1 and P2) allow them to improve the competences acquired over time. These results could indicate that students are acquiring the necessary skills on a continuum, in such a way that, at the end of their studies, when they graduate, they achieve a consolidation of skills that qualifies them to enter real clinical practice, as suggested by Miller et al. in their study [Among the most important results of this study, this tool proved to be very sensitive to change, as can be observed from the analyses conducted with the 61 students from the 3ir study . The comir study , 41, 42.ir study . The feair study , 43–46 air study , 45. Morir study , 47. Likir study , which, th-year students, which will allow them to further and better develop these skills, as is shown by the better grades obtained in P2 , Enabling the acquirement of a skill assessment tool that is sensitive to change, which is a very important psychometric property. Further studies should be conducted in order to determine the degree of student satisfaction and usefulness of this assessment system.This rubric allows the student to recognize his/her advances, achievements and difficulties, analyze his/her evolution, and develop a critical and reflective attitude towards his/her educational process. Within each achievement level, the degree of task or behavior performance with respect to what must be evaluated in the student was clearly established, ensuring the maximum quality of care, evaluation objectivity and homogeneity among the different participants and care centers involved in the evaluation process. Incorporating these levels of achievement, which other tools have not contemplated , 35, 37,In short, the present study emphasizes the importance of assessing transversal competences of the Physiotherapy Practicum using a valid and reliable tool such as the RECOPC-FIS II. Limitations or inconsistencies in the robustness of measurement tools may negatively affect clinical tutors’ decision making about the students they assess. Consequently, this could affect the practical preparation of graduates and even patient safety .On the other hand, the acquisition of skills and qualities essential for the development of students’ professional life will be facilitated. It is of utmost importance for the acquisition of these skills and qualities to be extensible to all degrees in health sciences at the national and international level. Previous tools did not offer the possibility of being adapted to other degrees in health sciences, since they used competences specific to the profession , 35, 37.rd and 4th year students, since, during the first year of the study, it was only possible to collect data from students in P1, and data from students in the Practicum were only collected from 2 academic years.As a limitation of the present study, it is important to highlight the difference in the number of participants between the 3In conclusion, RECOPC-FIS II proved to be a reliable and valid instrument for the evaluation of the transversal competences of the Practicum of Physiotherapy, providing useful information to both tutors and students. This tool would unify educational programs, promoting a shared and transparent common language when conducting assessments in health science courses. In line with other studies, this tool grants an essential role to the evaluation of the clinical practice in the training of physiotherapy students, being one of the few instruments published in Spanish .S1 Dataset(XLSX)Click here for additional data file.S1 Appendix(DOCX)Click here for additional data file.


The plasticity of the central nervous system (CNS) allows the change of neuronal organization and function after environmental stimuli or adaptation after sensory deprivation. The so-called critical period (CP) for neuroplasticity is the time window when each sensory brain region is more sensitive to changes and adaptations. This time window is usually different for each primary sensory area: somatosensory (S1), visual (V1), and auditory (A1). Several intrinsic mechanisms are also involved in the start and end of the CP for neuroplasticity; however, which is its duration in S1, VI, and A1? This systematic review evaluated studies on the determination of these time windows in small rodents. The careful study selection and methodological quality assessment indicated that the CP for neuroplasticity is different among the sensory areas, and the brain maps are influenced by environmental stimuli. Moreover, there is an overlap between the time windows of some sensory areas. Finally, the time window duration of the CP for neuroplasticity is predominant in S1. Neuroplasticity is the capacity of the central nervous system (CNS) to undergo structural and functional changes in response to environmental sensory experiences or even to adapt following injury  and conducted by following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement  review included randomized controlled studies that evaluated neuroplasticity (P) through experimental interventions during the CP (I) and reported the time window duration (start and end) in the primary sensory areas of the cerebral cortex (Co).English-language studies without the date of the publication restriction were searched in the PubMed, Web of Science, ScienceDirect, Embase, and Virtual Health Library databases by two reviewers (LP and GC) using the MeSH descriptors “neuronal plasticity,” “critical period,” and “cerebral cortex.” Additional primary studies were also searched throughout the reference lists of the retrieved articles. The search strategy was slightly adapted in each database and followed the PICo inclusion criteria described in the in vitro studies were excluded.The studies were selected by following the criteria: (1) descriptor in the title or abstract, (2) English language, (3) original studies, and (4) animal model with small rodents. Reviews, case reports, descriptive studies, opinion articles, technical reports, guidelines, human, and https://rayyan.ai/) to exclude duplicated articles and studies with titles and abstracts that did not meet the eligibility criteria. After full-text reading, two independent reviewers (LP and GC) performed the final selection, and any disagreement was resolved by a third reviewer (CB). Then, the following data of the selected articles were extracted: publication year, analyzed cortical sensory area, characteristics of the animals, and main outcomes regarding the time window of the CP for neuroplasticity in S1, V1, and A1 areas.The retrieved articles were uploaded to the Rayyan review assistance tool , which is based on the Cochrane RoB tool and has been adjusted for biases that play a specific role in animal intervention studies  Is there a possibility that the results are biased? (2) Do the results have factors that confuse the interpretation of the results? (3) Could the study results occur by chance? Articles that received mostly “no” answers were considered methodologically viable and with a low risk of bias.Among 1,859 articles, 625 duplicates and other 1,219 articles were excluded during the title and abstract reading. Thus, 15 articles were fully read. Two articles were excluded since the CP for neuroplasticity was associated with neurodegenerative diseases, while one study did not meet the aim of this review. Then, 12 articles were eligible for the qualitative assessment .Studies regarding the S1 area were performed by using electrophysiological recordings . The time window of the CP for neuroplasticity in the S1 area starts early, followed by A1 and V1 areas. S1 and A1 were found with the longest and shortest time windows, respectively. Moreover, the S1 completely and partially overlaps the A1 and V1 time windows of the CP, respectively .Considering that the outcome of a systematic review depends on the methodological quality of the studies  and the Coordination for the Improvement of Higher Education Personnel .The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.