Insight into Biomass Upgrade: A Review on Hydrogenation of 5-Hydroxymethylfurfural (HMF) to 2,5-Dimethylfuran (DMF)

Recent developments in the transformation of biobased 5-hydroxymethylfurfural (HMF) into a potential liquid fuel, 2,5-dimethylfuran (DMF), are summarised. This review focuses briefly on the history of HMF conversion to DMF in terms of the feedstock used and emphasises the ideal requirements in terms of the catalytic properties needed in HMF transformation into DMF. The recent state of the art and works on HMF transformation into DMF are discussed in comparison to noble metals and non-noble metals as well as bimetallic catalysts. The effect of the support used and the reaction conditions are also discussed. The recommendations for future work and challenges faced are specified.     

The Effects of Polyphenol,Tannic Acid,or Tannic Acid in Combination with Pamidronate on Human Osteoblast Cell Line Metabolism

Background: This study investigates the effect of tannic acid (TA) combined with pamidronate (PAM) on a human osteoblast cell line. Methods: EC₅₀ for TA, PAM, and different combination ratios of TA and PAM (25:75, 50:50, 75:25) were measured by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. The combination index value was utilized to analyze the degree of drug interaction, while trypan blue assay was applied to analyze the cells proliferation effect. The mineralization and detection of bone BSP and Osx genes were determined via histochemical staining and PCR test, respectively. Results: The EC₅₀ of osteoblasts treated with TA and a 75:25 ratio of TA and PAM were more potent with lower EC₅₀ at 0.56 µg/mL and 0.48 µg/mL, respectively. The combination of TA and PAM (75:25) was shown to have synergistic interaction. On Day 7, both TA and PAM groups showed significantly increased proliferation compared with control and combination groups. On Day 7, both the TA and combination-treated groups demonstrated a higher production of calcium deposits than the control and PAM-treated groups. Moreover, on Day 7, the combination-treated group showed a significantly higher expression of BSP and Osx genes than both the TA and PAM groups. Conclusion: Combination treatment of TA and PAM at 75:25 ameliorated the highest enhancement of osteoblast proliferation and mineralization as well as caused a high expression of BSP and Osx genes.     

Core Shell Nanostructure: Impregnated Activated Carbon as Adsorbent for Hydrogen Sulfide Adsorption

This study focuses on the synthesis, characterization, and evaluation of the performance of core shell nanostructure adsorbent for hydrogen sulfide (H₂S) capture. Commercial coconut shell activated carbon (CAC) and commercial mixed gas of 5000 ppm H₂S balanced N₂ were used. With different preparation techniques, the CAC was modified by core shell impregnation with zinc oxide (ZnO), titanium oxide (TiO₂), potassium hydroxide (KOH), and zinc acetate (ZnAC₂). The core structure was prepared with CAC impregnated by single chemical and double chemical labelled with ZnAC₂-CAC (single chemical), ZnAC₂/KOH-CAC, ZnAC₂/ZnO-CAC, and ZnAC₂/TiO₂-CAC. Then, the prepared core was layered either with KOH, TiO₂, NH₃, or TEOS for the shell. The synthesized adsorbents were characterized in physical and chemical characterization through scanning electron microscopy (SEM), thermal gravimetric analysis (TGA), and Brunauer-Emmett-Teller (BET) analyzers. Operation of the adsorber column takes place at ambient temperature, with absolute pressure at 1.5 bar. The H₂S gas was fed into the column at 5.5 L/min and the loaded adsorbents were 150 g. The performance of synthesized adsorbent was analyzed through the adsorbent’s capability in capturing H₂S gas. Based on the results, ZnAc₂/ZnO/CAC_WOS shows a better adsorption capacity with 1.17 mg H₂S/g and a 53% increment compared to raw CAC. However, the degradation of the adsorbents was higher compared to ZnAc₂/ZnO/CAC_OS and to ZnAc₂/ZnO/CAC_WS ZnAc₂/ZnO/CAC_OS. The presence of silica as a shell has potentially increased the adsorbent’s stability in several cycles of adsorption-desorption.     

Antibacterial Activity of Clay Soils against Food-Borne Salmonella typhimurium and Staphylococcus aureus

Natural clays have recently been proven to possess antibacterial properties. Effective natural antimicrobial agents are needed to combat bacterial contamination on food contact surfaces, which are increasingly more prevalent in the food chain. This study sought to determine the antibacterial activity of clays against the food-borne pathogens Salmonella typhimurium ATCC 14028 and Staphylococcus aureus ATCC 13565. Soils were processed to yield leachates and suspensions from untreated and treated clays. Soil particle size, pH, cation-exchange capacity, metal composition and mineralogy were characterized. Antibacterial screening was performed on six Malaysian soils via the disc diffusion method. In addition, a time-kill assay was conducted on selected antibacterial clays after 6 h of exposure. The screening revealed that Munchong and Carey clays significantly inhibit Salmonella typhimurium (11.00 ± 0.71 mm) and S. aureus (7.63 ± 0.48 mm), respectively. Treated Carey clay leachate and suspension completely kill Salmonella typhimurium, while S. aureus viability is reduced (2 to 3 log₁₀). The untreated Carey and all Munchong clays proved ineffective as antibacterials. XRD analysis confirmed the presence of pyrite and magnetite. Treated Carey clays had a higher soluble metal content compared to Munchong; namely Al (92.63 ± 2.18 mg/L), Fe (65.69 ± 3.09 mg/L) and Mg (88.48 ± 2.29 mg/L). Our results suggest that metal ion toxicity is responsible for the antibacterial activity of these clays.     

Separation of oxidized and deamidated human growth hormone variants by isocratic reversed-phase high-performance liquid chromatography.

Reversed-phase high-performance liquid chromatography (RP-HPLC) was utilized for the separation of recombinant human growth hormone (hGH) variants on a C18 silica column at 55 degrees C using an isocratic mobile phase which contained 27% 1-propanol in a 25 mM potassium phosphate buffer, pH 6.5. Three of the obtained peaks were characterized by tryptic mapping and mass spectrometry; two of the peaks were found to contain oxidized hGH (dioxy Met14/Met125 and Met125 sulfoxide) while the third contained a deamidated form (Asn149-->Asp149 or Asn152-->Asp152). Compared to the European Pharmacopoeia RP-HPLC method of hGH analysis, this new method gives two additional peaks and a 50% reduction in the analysis time.     

Variable selection in discriminant analysis based on the location model for mixed variables

Non-parametric smoothing of the location model is a potential basis for discriminating between groups of objects using mixtures of continuous and categorical variables simultaneously. However, it may lead to unreliable estimates of parameters when too many variables are involved. This paper proposes a method for performing variable selection on the basis of distance between groups as measured by smoothed Kullback–Leibler divergence. Searching strategies using forward, backward and stepwise selections are outlined, and corresponding stopping rules derived from asymptotic distributional results are proposed. Results from a Monte Carlo study demonstrate the feasibility of the method. Examples on real data show that the method is generally competitive with, and sometimes is better than, other existing classification methods.     

Oxide-assisted growth of silicon nanowires by carbothermal evaporation

Silicon nanowires (SiNWs) have successfully been synthesized by carbothermal evaporation method. By ramping-up the furnace system at 20 °C min⁻¹ to 1100 °C for 6 h, the vertically aligned coexist with crooked SiNWs were achieved on the silicon substrate located at 12 cm from source material. The processing parameters such as temperature, heating rate, duration, substrate position and location are very important to produce SiNWs. Morphology and chemical composition of deposited products were investigated by field-emission scanning electron microscopy (FESEM) equipped with energy dispersive X-ray analysis (EDX). The existence of small sphere silicon oxide capped nanowires suggested that the formation of SiNWs was governed by oxide-assisted growth (OAG) mechanism.     

A Partial Double-Pass S-Band Erbium-Doped Fibre Amplifier

An efficient and low noise short wavelength band erbium-doped fibre amplifier （S-band EDFA） is proposed and demonstrated using double-pass configuration. This amplifier provides a gain of 1500 nm signal as high as 26.9 dB, which is 9.6 dB higher than the two-stage single-pass amplifier. The corresponding noise figure obtained is 7.5 dB, which is of the same level as in the single-pass amplifier and more than 2 dB lower than the previously reported double-pass amplifier [IEIOE Electron. Express 2 （2005） 182]. The gain enhancement is due to the double pass-propagation of the test signal in the second stage, which increases the effective erbium-doped fibre （EDF） length. The low noise is attributed to the optical circulator between EDFs, which prevents the backward amplified spontaneous emission from propagating into the input part of the amplifier. The proposed amplifier is expected to play an important role in the development of a practical S-band EDFA.     

以对二甲苯氧化为对苯二甲酸为例简要综述一级C–H键活化(英文)

The oxidation of para‐xylene to terephthalic acid has been commercialised as the AMOCO process(Co/Mn/Br) that uses a homogeneous catalyst of cobalt and manganese together with a corrosive bromide compound as a promoter. This process is conducted in acidic medium at a high tempera‐ture(175–225 °C). Concerns over environmental and safety issues have driven studies to find mild‐er oxidation reactions of para‐xylene. This review discussed past and current progress in the oxida‐tion of para‐xylene process. The discussion concentrates on the approach of green chemistry in‐cluding(1) using heterogeneous catalysts with promising high selectivity and mild reaction condi‐tion,(2) application of carbon dioxide as a co‐oxidant, and(3) application of alternative promoters. The optimisation of para‐xylene oxidation was also outlined.