Cu/CuO Composite Track-Etched Membranes for Catalytic Decomposition of Nitrophenols and Removal of As(III)

One of the promising applications of nanomaterials is to use them as catalysts and sorbents to remove toxic pollutants such as nitroaromatic compounds and heavy metal ions for environmental protection. This work reports the synthesis of Cu/CuO-deposited composite track-etched membranes through low-temperature annealing and their application in catalysis and sorption. The synthesized Cu/CuO/poly(ethylene terephthalate) (PET) composites presented efficient catalytic activity with high conversion yield in the reduction of nitro aryl compounds to their corresponding amino derivatives. It has been found that increasing the time of annealing raises the ratio of the copper(II) oxide (CuO) tenorite phase in the structure, which leads to a significant increase in the catalytic activity of the composites. The samples presented maximum catalytic activity after 5 h of annealing, where the ratio of CuO phase and the degree of crystallinity were 64.3% and 62.7%, respectively. The catalytic activity of pristine and annealed composites was tested in the reduction of 4-nitroaniline and was shown to remain practically unchanged for five consecutive test cycles. Composites annealed at 140 °C were also tested for their capacity to absorb arsenic(III) ions in cross-flow mode. It was observed that the sorption capacity of composite membranes increased by 48.7% compared to the pristine sample and reached its maximum after 10 h of annealing, then gradually decreased by 24% with further annealing.

Dithienylethene metallodendrimers with high photochromic efficiency

It has been extremely challenging to achieve multi-photochromic systems with-out affecting the individual photoswitching properties of the constituent units. Herein, we present the design and synthesis of a new family of platinum-acetylide dendrimers containing up to twenty-one photochromic dithienylethene (DTE) units that exhibit both high photochromic efficiency and individual switch-ing properties. Upon irradiation with ultraviolet (UV) and visible (Vis) light, the resultant metallodendrimers display high conversion yield and excellent fatigue resistance. More interestingly, cyclization-cycloreversion kinetics revealed that the photochromic property of each DTE unit in these metallodendrimers is unaf-fected by its neighbor and the full ring-closure of up to twenty-one DTE units in one single dendrimer has been achieved.

Expendable Graphite as an Efficient Flame-Retardant for Novel Partial Bio-Based Rigid Polyurethane Foams

The rigid polyurethane foam (PU) is a versatile material, used especially for construction and household applications. The current situation demands a facile, cost-efficient, and greener approach for developing the polyurethanes from bio-derived materials. In this study, we present a novel bio-polyol synthesized using carvone, an extract from caraway, spearmint, or dill seeds via facile thiol-ene reaction. Our one-step reaction uses a UV irradiation to allow the room temperature conversion of the carvone to a high purity bio-polyol, as confirmed from the standard analytical characterizations. The hydroxyl number of 365 mg KOH/g close to its theoretical limit confirms the high conversion yield of the polyol for rigid PU synthesis. To overcome the flammability issues in PU, expandable graphite (EG) powder was used as an additive flame-retardant during the synthesis step. The resulting foams with EG maintained the uniform closed cell structure (>95%) with a high compression strength of 175 kPa. The addition of EG in PU results in the formation of a protective char layer during the flammability test and reduces the weight loss from 40.70% to 3.55% and burning time from 87 to 11 s. Our results confirm that the carvone-based polyol can be a novel alternative to the petroleum polyols for an industrial-scale application.

Enrichment of Polyglucosylated Isoflavones from Soybean Isoflavone Aglycones Using Optimized Amylosucrase Transglycosylation

Isoflavones in soybeans are well-known phytoestrogens. Soy isoflavones present in conjugated forms are converted to aglycone forms during processing and storage. Isoflavone aglycones (IFAs) of soybeans in human diets have poor solubility in water, resulting in low bioavailability and bioactivity. Enzyme-mediated glycosylation is an efficient and environmentally friendly way to modify the physicochemical properties of soy IFAs. In this study, we determined the optimal reaction conditions for Deinococcus geothermalis amylosucrase-mediated α-1,4 glycosylation of IFA-rich soybean extract to improve the bioaccessibility of IFAs. The conversion yields of soy IFAs were in decreasing order as follows: genistein > daidzein > glycitein. An enzyme quantity of 5 U and donor:acceptor ratios of 1000:1 (glycitein) and 400:1 (daidzein and genistein) resulted in high conversion yield (average 95.7%). These optimal reaction conditions for transglycosylation can be used to obtain transglycosylated IFA-rich functional ingredients from soybeans.

Efficient Synthesis of Alkali Borohydrides from Mechanochemical Reduction of Borates Using Magnesium–Aluminum-Based Waste

Lithium borohydride (LiBH4) and sodium borohydride (NaBH4) were synthesized via mechanical milling of LiBO2, and NaBO2 with Mg–Al-based waste under controlled gaseous atmosphere conditions. Following this approach, the results herein presented indicate that LiBH4 and NaBH4 can be formed with a high conversion yield starting from the anhydrous borates under 70 bar H2. Interestingly, NaBH4 can also be obtained with a high conversion yield by milling NaBO2·4H2O and Mg–Al-based waste under an argon atmosphere. Under optimized molar ratios of the starting materials and milling parameters, NaBH4 and LiBH4 were obtained with conversion ratios higher than 99.5%. Based on the collected experimental results, the influence of the milling energy and the correlation with the final yields were also discussed.

Hydrolysis Kinetics of Oil Palm Empty Fruit Bunch in Ionic Liquids and Cellulase Integrated System

Ionic liquids (ILs) are developing as potential solvents in lignocellulose solvation, which enables cellulase accessibility into the substrate. Nevertheless, ILs could result in enzyme deactivation because of the high polarity. Therefore, developing a system of ILs-compatible cellulase (IL-E) to promote lignocellulose conversion into sugars is a challenge in ILs applications. This study used an IL-E to attain high conversion yield of sugars from oil palm empty fruit bunch (EFB). Cellulase (Tr-Cel) from Trichoderma reesei was stable in the ILs, 1-ethyl-3-methyl imidazolium diethyl phosphate [EMIM]DEP and choline acetate [Cho]OAc. The inhibition and deactivation of cellulase were evaluated using the model substrate, carboxymethyl cellulose (CMC) and EFB as a lignocellulosic material to assess the hydrolytic activity. The enzyme kinetics revealed that [Cho]OAc acted as a noncompetitive inhibitor. Additionally, [EMIM]DEP may not be considered as an inhibitor as it increases the Vmax and does not significantly affect the KM. In both cases, the study proved that IL did not result in a severe loss of cellulase activity, which is a promising outcome for one-pot hydrolysis of lignocellulosic materials.

Cell-Free Metabolic Engineering: Recent Developments and Future Prospects

Due to the ongoing crises of fossil fuel depletion, climate change, and environmental pollution, microbial processes are increasingly considered as a potential alternative for cleaner and more efficient production of the diverse chemicals required for modern civilization. However, many issues, including low efficiency of raw material conversion and unintended release of genetically modified microorganisms into the environment, have limited the use of bioprocesses that rely on recombinant microorganisms. Cell-free metabolic engineering is emerging as a new approach that overcomes the limitations of existing cell-based systems. Instead of relying on metabolic processes carried out by living cells, cell-free metabolic engineering harnesses the metabolic activities of cell lysates in vitro. Such approaches offer several potential benefits, including operational simplicity, high conversion yield and productivity, and prevention of environmental release of microorganisms. In this article, we review the recent progress in this field and discuss the prospects of this technique as a next-generation bioconversion platform for the chemical industry.

Scandium(iii) triflate-promoted serine/threonine-selective peptide bond cleavage

The site-selective hydrolysis of peptide bonds at Ser and Thr positions was promoted by scandium(iii) triflate with a high conversion yield.