Chemical Composite Research Articles

Long-Range π-π Stacking Brings High Electron Delocalization for Enhanced Photocatalytic Activity in Hydrogen-Bonded Organic Framework.

Unlike many studies that regulate transport and separation behaviour of photogenerated charge carriers through controlling the chemical composite, our work demonstrates this goal can be achieved through simply tuning the molecular π-π packing from short-range to long-range within hydrogen-bonded organic frameworks (HOFs) without altering the building blocks or network topology. Further investigations reveal that the long-range π-π stacking significantly promotes electron delocalization and enhances electron density, thereby effectively suppressing electron-hole recombination and augmenting the charge transfer rate. Simultaneously, acting as a porous substrate, it boosts electron density of Pd nanoparticle loaded on its surfaces, resulting in remarkable CO2 photoreduction catalytic activity (CO generation rate: 48.1 μmol/g/h) without the need for hole scavengers. Our study provide insight into regulating the charge carrier behaviours in molecular assemblies based on hydrogen bonds, offering a new clue for efficient photocatalyst design.

MOISTURE-HARVESTING LIZARD SKINS AS AN INSPIRATON FOR PERFORMATIVE BUILDING ENVELOPES IN ARID CLIMATES

Research on shape-shifting adaptive architectural skins has recently focused on bio-inspired programmable materials. Only a few studies however examine the microstructure of living organisms, especially in terms of morphological adaptation in harsh climatic conditions. This paper explores the microstructure of moisture-harvesting lizard skins, specifically the Trapelus species of the Agamidae family in North-East Africa, as an inspiration for programmable materials in adaptive building skins in the arid climate of Egypt. The paper investigates the ability to improve the durability and morphological capabilities of programmable materials based on surface formation, utilizing digital fabrication techniques. A series of physical experiments were conducted on different samples of 3D printed wood filament under several humidity conditions, as a single layer, with textured patterns, and with the addition of potassium chloride as a moisture-harvesting chemical composite. The paper concluded that materials composed of textured patterns and moisture-harvesting chemical composites exhibited the highest moisture retention, therefore leading to advantages in its use in adaptive building skins in arid climates, through a wide variety of design possibilities for performative building envelopes.

Клінічне дослідження відновлень зубів з різних матеріалів

The purpose of the study was a comparative clinical evaluation of direct cervical restorations of teeth made from different materials. Materials and methods. In 49 patients aged from 22 to 37 years, direct restoration of 97 teeth with cervical carious lesions was carried out. Group 1 included 19 people (39.6% of the number of examined) with 35 restorations (36.1% of the number of restorations) from photocomposite, group 2 – 14 people (29.2%), in whom 34 restorations were performed (35.1%) with glass ionomer cement, in 15 patients (31.3%) of group 3 28 restorations (28.9%) were performed with chemically hardening composite. The examination was carried out the next day, after 6 and 12 months according to clinical and aesthetic criteria. Results and discussion. The next day, in patients of group 1, 2 restored teeth (5.7% of their number in patients of the group) had increased sensitivity. After 6 months, 1 restoration (2.9%) was missing in patients of group 1, 2 restorations (5.7%) had marginal fit violations, 1 (2.9%) – had marginal coloration, and 1 restored tooth (2.9%) was diagnosed with hypersensitivity. In patients of group 2, in 5 restorations (14.7%) defects of marginal fit and marginal coloration were detected. In persons of group 3, in 3 restorations (10.7%) the marginal fit was violated, in 4 (14.7%) – coloration. In the period of 12 months, in persons of group 1, 1 restoration (3.2% of their number at this time) was again absent, secondary caries was detected, defects in the marginal fit of the photocomposite were recorded in 3 restorations (8.6%), marginal coloration – in 4 (11.4%). In patients of group 2, in 6 restorations (22.2% of the number in this period), the marginal fit of the glass ionomer was violated, in 8 (29.6%) – marginal coloration. In patients of group 3, defects in the marginal fit of the chemical composite were identified in 7 restorations (29.2% of the number in this period), marginal coloration – in 6 (25%), secondary caries was found along with 1 restoration (4.2%). The undisputed dominance of the photocomposite material in the aesthetic evaluation of the state of restorations was proven, in particular, according to criteria that included color matching and surface roughness, only single deviations were found in photocomposite restorations, and in restorations from glass ionomer cement and chemically hardening composite, they were found several times more. Conclusion. When using photocomposite material to restore teeth with cervical carious lesions, the possibility of the abfraction effect with subsequent loss of restorations and the increased risk of postoperative sensitivity in the restored teeth should be taken into account

Study on Flocculation Behavior of Cr(VI) Using a Novel Chitosan Functionalized with Thiol Groups

In this study, CTS-GSH was prepared by grafting thiol (-SH) groups onto chitosan (CTS), which was characterized through Fourier Transform Infrared (FT-IR) spectra, Scanning Electron Microscopy (SEM) and Differential Thermal Analysis-Thermogravimetric Analysis (DTA-TG). The performance of CTS-GSH was evaluated by measuring Cr(VI) removal efficiency. The -SH group was successfully grafted onto CTS, forming a chemical composite, CTS-GSH, with a rough, porous and spatial network surface. All of the molecules tested in this study were efficient at removing Cr(VI) from the solution. The more CTS-GSH added, the more Cr(VI) removed. When a suitable dosage of CTS-GSH was added, Cr(VI) was almost completely removed. The acidic environment at pH 5-6 was beneficial for the removal of Cr(VI), and at pH 6, the maximum removal efficiency was achieved. Further experimentation showed that with 100.0 mg/L CTS-GSH for the disposal of 5.0 mg/L Cr(VI) solution, the removal rate of Cr(VI) reached 99.3% with a slow stirring time of 8.0 min and sedimentation time of 3 h; the presence of four common ions, including Mg2+, Ca2+, SO42- and CO32-, had an inhibitory effect on CTS-GSH's ability to remove Cr(VI) from the aqueous solution, and more CTS-GSH was needed to reduce this inhibiting action. Overall, CTS-GSH exhibited good results in Cr(VI) removal, and thus has good potential for the further treatment of heavy metal wastewater.

The modelling and simulation of perovskite solar cell consisting textile-based electrodes

Perovskite solar cell (PSC) consisting textile-based electrodes has been created novel features for future energy supply. Recently, Cs0.05(FA0.85MA0.15)0.95Pb(I0.85Br0.15)3 perovskite has appeared as a favourable candidate for flexible perovskite solar cells. However, a confined performance was acquired when the conventional Spiro-OMeTAD were used as hole transport layer (HTL) material because of suboptimal valance band offset (ΔEV) between Perovskite/HTL layers. In this study, a theoretical drift–diffusion​ modelling is used by finite volume method (FVM) to investigate performance of textile perovskite solar cell with double hole transport layers (HTLs) with graded band gap energies. Copper thiocyanate (CuSCN) and Nickel Oxide (NiO) are replaced as double HTLs, which dramatically enhanced the performance due to optimal upward step by step valance band offsets (ΔEV) between Perovskite/Textile Composite Electrode layers. It is shown that the decreasing of the metal–semiconductor schottky barrier height of electrodes leads to significant increase in fill factor (FF). Also, it is revealed that the enriching of perovskite carrier diffusion length by equipoising of carrier capture cross section, carrier total defect density and carrier thermal velocity substantially promote the overall device efficiency. The short-circuit current (Jsc) of 20.65 mA/cm 2, open-circuit voltage (Voc) of 1.19 V, fill factor (FF) of 73.57%, and power conversion efficiency (PCE) of 18.20% have been obtained by optimization of electrodes properties and perovskite layers. Remarkably, the advantageous of low cost, flexible, and chemical stable conducive textile composite, extends new opportunities in the commercial expansion of highly efficient photovoltaic textile in optoelectronic industry field.

Characterization and Analysis of Intelligent Eco-Friendly Coating for Porcelain Insulator Flash-Over Protection

Among all the astonishing equipment found in power transmission and distribution networks, the insulator plays a vital role by providing mechanical support and electrical protection to power system. Despite all these noteworthy facts, the breakdown of insulators owing to surface contaminants appears to be particularly fascinating in today’s scientific world. Researchers provide a plethora of methods to eradicate this problem. Amidst the methods, superhydrophobic coating for insulators which is one of the widely used method, provide better solution as it offers resistance to moisture, wetness, dust and ice. This unique property of superhydrophobic coated insulators require further investigation. Hence to achieve this purpose, preparation of eco-friendly superhydrophobic solution of PDMS (Poly di methyl siloxane) with MTMS (Methyl tri methoxy silane) composites was made and analysed. In this study superhydrophobic coatings were prepared by using sol-gel method and spray coating technique. Authors performed characterization studies by using goniometer to measure the contact angle (CA) for superhydrophobic coating on insulator surface and it was found to be from 165° to 170° and sliding angle was from 5° to 10° confirming superhydrophobic property. Fourier Transforms Infrared Spectroscopy (FTIR) analysis validates the chemical composite of the coatings. Scanning Electron Microscope (SEM) analysis was used to observe the surface morphology of coating with estimated thickness L = 2 μm.Thermogravimetric analysis (TGA) was conducted to study about thermal withstanding limit of the coating above 600 °C. Finally, in an intentional contaminated conditions based on solid layer method of IEC60507 standards and IEC 60587 standards insulation resistances were tested using a megger instrument and self-cleaning ability of coating was also determined in this research.

Atom-Bond Connectivity Index in Various Graphs

A topological index, furthermore identified by way of connective index, is a molecular construction descriptor intended from a molecular graph of a chemical composite, which symbolizes its topology. Different topological indices remain branded established on their degree, spectrum, and distance. Here we investigation on we designed and analyzed the degree oriented topological directories, such as atom-bond connectivity index. Further investigated the index in regular graph, complete graph, complete bipartite graph, union of graphs, and join of graphs are derived. Further explain the theorem by examples.

Chemical composite of indigenous whole grain scented joha rice varietal prevents type 2 diabetes in rats through ameliorating insulin sensitization by the IRS-1/AKT/PI3K signalling cascade

Preventive measures to lower the prevalence of type-2 diabetes development using dietary phytochemicals are most realistic. A phytochemical composite derived from whole grain scented joha rice (PCKJ), which is indigenous to the North-eastern Region, India, was investigated to understand its preventive efficacy in rats in which type 2 diabetes was induced using a high-fat high-fructose (HFHF) diet and a low dose of streptozotocin, and the findings were correlated with those in L6-myotubes. Studies on cultured L6 myotubes revealed that treatment with PCKJ facilitated glucose uptake and GLUT-4 translocation to the plasma membrane, as evidenced by confocal microscopy and/or cell fractionation studies. Furthermore, the FFA-induced L6 myotubes were identified as having elevated levels of PI3K, p-AKT (Ser473) and GLUT-4, which returned to the basal level upon exposure to PCKJ. The administration of PCKJ (100 mg per kg body weight, oral gavage, 24 weeks) to rats significantly reduced their blood glucose levels along with common lipid and liver biomarkers (LDL, triglycerides, cholesterol, ALT, and AST) compared to the control group. Moreover, immunoblotting analysis showed that upon PCKJ treatment, PI3K, p-AKT and GLUT-4 levels are upregulated in the skeletal tissue of HFHF-fed rats, similar to the in vitro model. The alteration in the levels of inflammatory cytokines IL-6, IL-10 and IFN-γ in diabetic rats returned to normal levels upon exposure to PCKJ. Histological analysis of vital tissues further strengthens the findings of the preventive value of PCKJ against the development of insulin resistance. In conclusion, this study showed the prophylactic effect of PCKJ as a potent chemical composite, which can be used to develop functional foods (nutraceuticals) for ameliorating type-2 diabetes by improving insulin sensitization and thereby glucose metabolism.

Effect of graphite microstructure on their physical parameters and wettability properties

To produce castings of titanium, nickel, zinc, copper and many other metal alloys, graphite molds can be used. Using graphite molds has many advantages which are no lubricate or coating layers are needed, high cooling rate, easy of production of complicated shapes. However, for good quality of castings there is needed a good quality of graphite with high mechanical properties and good heat transfer coefficient. Because of no room for manipulating of chemical composite of graphite molds, the most important factor influencing the properties of the molds is their production process. Thus, in the present study mechanical properties of two different type of graphite were investigated. There was graphite produced by different technological processes. One of the processes was a typical graphite production process from the isotropic coke, the second process was an electrolytic method production. Investigations included mechanical tests as well as the structure observations by scanning electron microscope. Chemical analysis was determined by Energy Dispersive X-ray Spectroscopy method additionally, phase analysis using the XRD method was performed. Mechanical properties were obtained by compression tests and three points banding tests at room temperature. It was found that the porosity of a graphite is the key parameter for good its mechanical properties. In addition, it was found that the mechanical anisotropy of graphite is the effect of the production method where the size and distribution of pores play an important role. Ill. 7. Ref. 9.

A Psychoanalysis of Milk: The Case of Alfred Hitchcock

A Psychoanalysis of Milk: The Case of Alfred Hitchcock

S-doping α-Fe2O3 induced efficient electron-hole separation for enhanced persulfate activation toward carbamazepine oxidation: Experimental and DFT study

• S-doped α-Fe 2 O 3 was synthesized successfully via a three-steps method. • UV/PS/S-α-Fe 2 O 3 process presented excellent performance for CBZ removal. • S-α-Fe 2 O 3 exhibited slower electrons-holes recombination rate and narrower band gap. • ·OH, SO 4 - ·, O 2 – · and h + were responsible for CBZ degradation in UV/PS/S-α-Fe 2 O 3 process. • The hydroxylation, deamination, decarbonylation, ketonization and ring cleavage were the main degradation routes. As a typical iron-based oxide semiconductor with abundant reserves, α-Fe 2 O 3 has been widely used in the domain of photocatalysis and environmental remediation. Here, sulfur doped α-Fe 2 O 3 (S-α-Fe 2 O 3 ) has been successfully fabricated through coprecipitation, hydrothermal and calcination processes and applied to activate persulfate (PS) for carbamazepine (CBZ) degradation under UV irradiation. Systematic characterizations were conducted to analyze the morphology, structure and chemical composite of S-α-Fe 2 O 3 . UV/PS/S-α-Fe 2 O 3 process showed remarkably enhanced photocatalytic performance for CBZ degradation. The degradation rate constant (7.78 × 10 −2 min −1 ) was about 2.2 and 14.1 times as high as that of UV/PS/α-Fe 2 O 3 (3.60 × 10 −2 min −1 ) and UV/PS (5.53 × 10 −3 min −1 ) processes, respectively. With increasing PS concentration and photocatalyst dosage, the removal efficiency of CBZ both increased. UV/PS/S-α-Fe 2 O 3 process can efficiently and steadily operate in a wide pH range of 3.0–8.0. The introduction of water matrix species (i.e. chloride, bicarbonate, nitrate and humic acid) exerted different effects on CBZ degradation. S-dopant was doped via forming ≡Fe III -SO 4 2- bond on S-α-Fe 2 O 3 surface, and doped sulfur functioned as surface electrons trapping centers derived from DFT study. The band gap value of S-α-Fe 2 O 3 was reduced and the separation efficiency of photogenerated electrons and holes was improved. Hydroxyl radicals, sulfate radicals, superoxide radicals and holes all contributed to CBZ destruction. Furthermore, two major routes of CBZ degradation were proposed as hydroxylation and deamination, then followed by decarbonxylation, ketonization and ring cleavage based on the results of HPLC-MS and DFT calculation.

Transitions among Cracking, Peeling and Homogenization on Drying of an Aqueous Solution Containing Glucose and Starch

A morphological transition was observed in the drying of an aqueous solution containing glucose and starch, which are the monomer and polymer of the same chemical composite. With an increase in the...

Development of ensemble learning models to evaluate the strength of coal-grout materials

In the loose and fractured coal seam with particularly low uniaxial compressive strength (UCS), driving a roadway is extremely difficult as roof falling and wall spalling occur frequently. To address this issue, the jet grouting (JG) technique (high-pressure grout mixed with coal particles) was first introduced in this study to improve the self-supporting ability of coal mass. To evaluate the strength of the jet-grouted coal-grout composite (JG composite), the UCS evolution patterns were analyzed by preparing 405 specimens combining the influential variables of grout types, curing time, and coal to grout (C/G) ratio. Furthermore, the relationships between UCS and these influencing variables were modeled using ensemble learning methods i.e. gradient boosted regression tree (GBRT) and random forest (RF) with their hyperparameters tuned by the particle swarm optimization (PSO). The results showed that the chemical grout composite has higher short-term strength, while the cement grout composite can achieve more stable strength in the long term. The PSO-GBRT and PSO-RF models can both achieve high prediction accuracy. Also, the variable importance analysis demonstrated that the grout type and curing time should be considered carefully. This study provides a robust intelligent model for predicting UCS of JG composites, which boosts JG design in the field.

Column reverse rougher flotation of iron bearing fine tailings assisted by HIC and a new cationic collector

This work focuses on a novel treatment process for Brazilian iron bearing fine tailings by rougher reverse column flotation assisted by high-intensity conditioning (HIC) with a new cationic collector in a conventional column cell (CCC) and in a modified three-product column (3PC). The samples (30–35% solids), corresponded to very fine (49% of the mass below 10 µm) and low-grade iron bearing tailings (40–43% Fe) collected from the thickened overflow of the desliming hydrocyclones. The objectives were to obtain two “concentrates” as feeds to future beneficiation processes; first, a non-floated product with a minimum grade about 48–50% Fe content (iron concentrate) and the floated material with a maximum grade of 15% Fe (named siliceous concentrates). Both goals were achieved due to the high selectivity of a chemical composite of amide-amines acting as a flotation collector/frother for the siliceous gangue particles. In addition, HIC was needed to enhance the flotation recoveries by improving capture by bubbles; without HIC, the mass being floated was very low (<10%). Best results were obtained by optimising the superficial flux parameters (Jsl, Jg and Jw) and residence time. Flotation in the 3PC led to purer siliceous concentrates with Fe grade lower than 10–12% Fe. Mechanisms involved were discussed in terms of mass transfer and interfacial phenomena. It is believed that the process has a high potential in the treatment of fresh iron tailings, a very old and relevant problem in the area.

Synergistic single process additive manufacturing of hydro-responsive Ag nanoparticle composites by digital visible light processing 3D printing

Single unit process fabrication of a responsive Ag nanoparticle (NP) chemical hydrogel composite is achieved through digital visible light processing (DLP) 3D printing of a self-assembled nanostructured (multilamellar) resin doped with Ag(i).

Cooperative Enhancement Solar Hydrogen Generation of Reformed g-C3N4/TiO2 Mesocrystals Composites

Using template-free process of KOH modified g-C3N4 and solvothermal methods, TC-x composites are synthesized successfully. The morphological characteristics, crystal and chemical composite of the reformed TC-x composites are studied by a series of characterization instruments and methods. Furthermore, TC-x composites is investigated as photocatalytic water splitting hydrogen catalyst. Under simulated sunlight illumination, the amount of reformed g-C3N4 added obvious effects on photocatalytic properties of TC-x composites. The results of hydrogen (H2) production show that reformed with 100 mg g-C3N4 are 1.5 times higher efficiency than that of TiO2 Mesocrystals. Its outstanding catalytic properties are attributed to the effective electron–hole separation which robust charge transfer and reduction capability. The mechanism of increasing hydrogen evolution activity and possible reasons for improving photocatalytic efficiency is also explained. This finding about g-C3N4/TiO2 composites provides a new idea for synthesis and application of a new type of photocatalytic material for energy and environment.

The composition design and properties investigation of Al-based amorphous powder

By adding different amounts of rare earth element Y and Gd in Al86Ni8Co1La5, aluminum amorphous ribbon samples were prepared using single roller melt-spinning under 2 different roller speeds. Then X-ray diffraction (XRD), transmission electron microscope (TEM) and differential scanning calorimetry (DSC) were adopted to study the effect of rare earth element Y and Gd additions on phase structure, forming ability and thermal stability of Al86Ni8Co1La5 alloy. The results show that the better chemical composite is Al86Ni8Co1La1Y2Gd2, which can form a whole amorphous strip when the roller speed is 3 m/s. After the better chemical composition is confirmed, the Al-based amorphous powder is produced using gas atomization and its properties are also validated using cold spray technique. The thickness, porosity and amorphous amount of coatings is about 600 μm, 0.5% and 80.2% (CS–C), respectively. These findings indicate that Al86Ni8Co1La1Y2Gd2 amorphous powder can be used as raw materials for cold spray technique.

Solid-Phase Hydrogen Storage Based on NH3BH3-SiO2 Nanocomposite for Thermolysis

Current H2-proton exchange membrane fuel cell systems available for commercial applications employ heavy and high-risk physical hydrogen storage containers. However, these compressed or liquefied H2-containing cylinders are only suitable for ground-based electric vehicles, because although highly purified H2 can be stored in a cylinder, it is not compatible with unmanned aerial vehicles (UAVs), which require a lighter and more stable energy source. Here, we introduce a chemical hydrogen storage composite, composed of ammonia borane (AB) as a hydrogen source and various heterogeneous catalysts, to elevate the thermal dehydrogenation rate. Nanoscale SiO2 catalysts with a cotton structure dramatically increase the hydrogen evolution rate on demand, while simultaneously lowering the startup temperature for AB thermolysis. Results show that the dehydrogenation reaction of AB with a cotton-structured SiO2 nanocatalyst composite occurs below 90°C, the reaction time is less than a minute, and the hydrogen generation yield is over 12 wt%, with an activation energy of 63.9 kJ·mol-1.

Effect of pH on phase, morphologies, and photocatalytic properties of BiOCl synthesized by hydrothermal method

The effect of pH on preparation of visible light–driven BiOCl photocatalysts under different pH values by hydrothermal method was prepared in this research. The as-prepared visible light–driven BiOCl photocatalysts were characterized by X-ray powder diffraction (XRD), Raman spectroscopy, Fourier transform infrared (FTIR) spectrophotometry, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) to characterize the phase, atom vibration, morphologies, and chemical composite of as-synthesized BiOCl samples. The XRD patterns of products revealed the presence of pure tetragonal BiOCl phase in the solutions with the pH of 2–10. The morphologies of BiOCl samples at pH 2–10 were observed by SEM, revealing that the precursor solution pH has a large effect on the final morphologies of BiOCl samples after hydrothermal synthesis. Photocatalytic activities of BiOCl photocatalysts were studied by photodegradation of rhodamine B (RhB) under visible light irradiation. When the precursor solution pH was 8, it was found that BiOCl catalysts exhibited the best photocatalytic activities.

Enhanced electrochemical and safe performances of LiNi1/3Co1/3Mn1/3O2 by nano-CeO2 coating via a novel hydrolysis precipitate reaction route

The homogeneous nano-CeO2 coated on the LiNi1/3Co1/3Mn1/3O2 powder like substrate was prepared via a novel hydrolytic precipitation reaction followed by the thoroughly baking at 450 °C. The chemical composite of nano-CeO2 coating layer was spectroscopically examined by X-ray diffraction, field-emission scanning electron microscopy and X-ray photoelectron spectrometer. The electrochemical characterization of the resulting materials proclaim that nano-CeO2 coating can drastically improve lithium storage performances. The optimum coating amount of CeO2 is as high as 2 wt%, which rendered a discharge capacity of 148.9 mAh g−1 with 91.6% capacity retention ensuing as many as 100 cycles. In particular, the exothermic peak is vastly increased from 256.4 to 338.2 °C. The value is superior to its counterparts, LiNi1/3Co1/3Mn1/3O2. It paves a new avenue for developing high safety lithium batteries.