Preparation of biomimetic three-dimensional gelatin/montmorillonite–chitosan scaffold for tissue engineering

A novel gelatin/montmorillonite–chitosan (Gel/MMT–CS) nanocomposite scaffold was prepared via the intercalation process and the freeze-drying technique, using the ice particulates as the porogen materials. Properties including pore structure, water adsorption content, in vitro degradation and tensile strength were investigated. It was demonstrated that the introduced intercalation structure endowed the Gel/MMT–CS scaffold with good mechanical properties and a controllable degradation rate. Scanning of the electron microscope images revealed that the scaffold obtained was highly porous and suitable for the implanted cells to adhere and grow. The mitochondrial activity assay provided good evidences of cells viability on the Gel/MMT–CS membranes, giving an indication of possible application as a matrix for tissue engineering.     

A systematic study of photocatalytic H2 production from propionic acid solution over Pt/TiO2 photocatalyst

The propionic acid (HPr) is one of the main by‐products during fermentative H₂ process. To efficiently convert HPr to H₂ gas, photocatalytic H₂ production from HPr solution with the use of Pt/TiO₂ photocatalyst under ultraviolet light has been studied in this research. The Pt/TiO₂ photocatalyst has been prepared by the sol–gel method and further characterized by X‐ray diffraction, TEM and XPS. Effects of Pt loading amount, HPr concentration, initial pH value on photocatalytic H₂ production have been investigated in detail. From practical point of view, the H₂ evolution from HPr solution under UV irradiation for prolonged time has been studied as well. The Langmuir model can be able to describe the relationship between HPr concentration with the maximum rate of H₂ production. The apparent quantum efficiency and apparent energy conversion efficiency are found to 1.65 and 0.72%, respectively. To better understand the photocatalytic H₂ process over Pt/TiO₂, a possible mechanism for the degradation of HPr has been proposed as well. Based on our results, an efficient route for hydrogen production from renewable biomass can be established by coupling biological H₂ production process with photocatalytic H₂ production process. Copyright © 2010 John Wiley & Sons, Ltd.     

Ultrathin MoSSe alloy nanosheets anchored on carbon nanotubes as advanced catalysts for hydrogen evolution

The activity of transition metal dichalcogenides (TMD) toward hydrogen evolution reaction (HER) derives from the active sites at the edges, but the basal surface still remain catalytic insert. Herein, ultrathin MoSSe alloy nanosheets array on multiwalled carbon nanotubes (MWCNTs) to form a core shell structure via a simple solvothermal process. These three-dimensional (3D) MoSSe hybrids show a high activity in hydrogen evolution reaction (HER) with a small Tafel slope of 38 mV dec⁻¹ and a low overpotential of 102 mV at 10 mA cm⁻². In addition, their HER activity remains remarkably stable without significant decay after 100 h polarization. Such superior catalytic HER activity springs from the 3D hierarchical heterostructure, which is abundant of catalytic edge sites, and the alloy effect between S and Se, which will create huge defects and strain to form vacancy sites on the basal plane. This strategy may open a new avenue toward the development of nonprecious high-performance HER catalysts.     

Machine learning technology in biodiesel research: A review

Biodiesel has the potential to significantly contribute to making transportation fuels more sustainable. Due to the complexity and nonlinearity of processes for biodiesel production and use, fast and accurate modeling tools are required for their design, optimization, monitoring, and control. Data-driven machine learning (ML) techniques have demonstrated superior predictive capability compared to conventional methods for modeling such highly complex processes. Among the available ML techniques, the artificial neural network (ANN) technology is the most widely used approach in biodiesel research. The ANN approach is a computational learning method that mimics the human brain's neurological processing ability to map input-output relationships of ill-defined systems. Given its high generalization capacity, ANN has gained popularity in dealing with complex nonlinear real-world engineering and scientific problems. This paper is devoted to thoroughly reviewing and critically discussing various ML technology applications, with a particular focus on ANN, to solve function approximation, optimization, monitoring, and control problems in biodiesel research. Moreover, the advantages and disadvantages of using ML technology in biodiesel research are highlighted to direct future R&D efforts in this domain. ML technology has generally been used in biodiesel research for modeling (trans)esterification processes, physico-chemical characteristics of biodiesel, and biodiesel-fueled internal combustion engines. The primary purpose of introducing ML technology to the biodiesel industry has been to monitor and control biodiesel systems in real-time; however, these issues have rarely been explored in the literature. Therefore, future studies appear to be directed towards the use of ML techniques for real-time process monitoring and control of biodiesel systems to enhance production efficiency, economic viability, and environmental sustainability.     

Influence of micro- and nanoparticles of zirconium oxides on the dielectric properties of CaCu3Ti4O12

This work presents the results of Zr oxide doping of a CaCu₃Ti₄O₁₂ (CCTO) ceramic prepared by a solid-state reaction. Different stoichiometries (ZrO and ZrO₂) and grain sizes (micro- and nanoparticles) were added as dopants at concentrations of 0.5 and 1.0 wt%. Zr-doping controls the grain size growth, leading to a reduction of the grain size as observed by scanning electron microscopy. For both dopant concentrations, all of the samples exhibited lower dielectric loss and a smaller dielectric constant than those of undoped CCTO. The sample doped with 0.5% of the non-stoichiometric ZrO exhibits a dielectric constant over 3200 and a dissipation factor of 0.02 at 1 kHz. The impedance spectroscopy analysis confirms that the decrease of dielectric loss is mainly due to an increase in resistivity at grain boundaries, which is attributed to the suppression of oxygen-loss promoted by dopants.     

Detection of the residues of nineteen pesticides in fresh vegetable samples using gas chromatography–mass spectrometry

In this study, we investigated the presence of 19 different agricultural pesticides in 210 samples of eight types of domestic vegetables collected from several vegetable-growing regions in Bangladesh. A multiresidue method was developed to detect the pesticide levels in the collected samples using gas chromatography with mass spectrophotometry (GC–MS). Pesticide residues were detected in 51.30% of the total samples, and among the positive samples, 38.89% contained levels above the maximum residue levels (MRLs). The most frequently detected pesticides were chlorpyrifos (34) followed by carbofuran (17), diazinon (16), carbaryl (14), malathion (11), endosulfan (8), cypermethrin (7) and dimethoate (6). Some (10.47%) of the samples contained multiple residues. It is concluded that the continuous monitoring and strict regulation of pesticide use on food crops, especially vegetables, are necessary.     

Biohydrogen production from Humulus scandens by dark fermentation: Potential evaluation and process optimization

As a perennial grass, Humulus scandens is rich in cellulose which can be fermented for bioenergy producing. Hence, the hydrogen production potential of the Humulus scandens from dark fermentation by Enterobacter aerogenes was investigated in this paper. Cellulase amount, inoculation amount, and initial pH value were evaluated. The interrelationship between these factors were studied by Response Surface Box-Behnken Experiments. Results showed that there was a significant correlation between the three factors. Through the correction of the regression equation, the optimized technological conditions were obtained. The amount of cellulase was 0.203 g g⁻¹ TS, the inoculation amount was 42.6%, the initial pH value was 6.59, the pre-estimated maximum cumulative value of hydrogen production was 65.12 mL g⁻¹ TS, and it was similar to the test mean value which was 64.08 mL g⁻¹ TS.     

An algebraic formulation of the simplex linear method for multiple integrals over the d-dimensional domain

We present the systematic treatment of multiple integrals over a simplex of the dimensionality d (d-simplex). The integrand is an analytical function in a suitable domain, and the linear form was employed as an argument. Using the elements obtained from the values of the integrand at the vertices of the d-simplex, integral can be evaluated analytically and expressed as the quotient of two determinants. Potential applications of the results described in the present study include numerical computations of Green?s function (GF), and the response of quantum systems in terms of complex susceptibilities in multidimensional space.     

Enhanced performance of γ-Fe2O3:WO3 nanocomposite towards selective acetone vapor detection

Metal oxide nanocomposite sensors based on γ-Fe₂O₃ and WO₃ were investigated in acetone vapor of various concentrations (1–100 ppm) at operating temperatures between 250 and 350 °C. The composites were prepared by simple solid state mixing and porous thick-film gas sensors were fabricated on alumina substrates. The γ-Fe₂O₃:WO₃ (50:50) nanocomposite showed a marked enhancement in sensing response down to 1 ppm acetone vapor detection at 300 °C. The response was ~2-fold better compared to pure WO₃ or pure γ-Fe₂O₃ with a very fast response (1 s) and very short recovery time (3 s). No appreciable sensitivity was observed towards alcohol vapor (an interfacing agent for diabetics) and in moisture (present in breath). The enhanced performance was due to n–n heterojunction effect.     

Preparation and comparative evaluation of well-defined fluorinated acrylic copolymer latex and solution for ancient stone protection

In this work the well-defined fluorinated acrylic copolymer latex and solution were prepared by the radical initiated seed emulsion polymerization and solution polymerization, respectively, using the same monomers of dodecafluoroheptyl methacrylate (DFHM), butyl acrylate (BA) and methyl methylacrylate (MMA). The copolymer latex BA/MMA/DFHM was designed as core–shell structure and the copolymer solution poly(BA–MMA–DFHM) was structured with low molecular weight. The chemical and morphology structures as well as the film properties obtained from latex and solution were analyzed and compared by spectroscopic techniques (FT-IR and NMR), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), gel permeation chromatography (GPC), scanning electron microscopy coupled with energy-dispersive X-ray detector (SEM–EDX) and static contact angles (CAs) instrument. Moreover, the BA/MMA/DFHM latex and poly(BA–MMA–DFHM) solution (with 29 wt% of DFHM) were applied onto two kinds of sandstone samples by capillary absorption, and their preliminary protecting efficiency was evaluated. It is demonstrated that the comprehensive performances of BA/MMA/DFHM latex films were quite comparable to those of poly(BA–MMA–DFHM) solution cast films, the latter exhibited a better protective performance.