Preparation and characterization of branched micro/nano Se

Branched micro/nano Se was prepared by the redaction of L-Cys•HCl and H2SeO3 in hydrothermal method, as β-CD was used as soft template. The structures of products were characterized by SEM, TEM and XRD. Some important factors influencing the morphology of products were studied and discussed, including the amounts of soft template, the reaction temperature and the reaction time. The results showed that external causes had a potent effect on the morphology of micro/nano Se. The uniform branched micro/nano Se prepared under the optimal reaction condition was rhombohedral trigonal selenium t-Se0, but its crystallinity degree was low.

Identification and structural analysis of a thermophilic β-1,3-glucanase from compost

Abstractβ-1,3-glucanase can specifically hydrolyze glucans to oligosaccharides and has potential applications in biotechnology. We used the metatranscriptomic technology to discover a thermophilic β-1,3-glucanase from compost. The phylogenetic study shows that it belongs to the family 16 glycoside hydrolase (GH16) and is most homologous with an enzyme from Streptomyces sioyaensis, an actinobacterium. It has the activity of 146.9 U/mg in the optimal reaction condition (75 °C and pH 5.5). Its catalytic domain was crystallized and diffracted to 1.14 Å resolution. The crystal structure shows a sandwich-like β-jelly-roll fold with two disulfide bonds. After analyzing the occurring frequencies of these cysteine residues, we designed two mutants (C160G and C180I) to study the role of these disulfide bonds. Both mutants have decreased their optimal temperature from 75 to 70 °C, which indicate that the disulfide bonds are important to maintain thermostability. Interestingly, the activity of C160G has increased ~ 17% to reach 171.4 U/mg. We speculate that the increased activity of C160G mutant is due to increased dynamics near the active site. Our studies give a good example of balancing the rigidity and flexibility for enzyme activity, which is helpful for protein engineering.

Study on Remediation of Hexachlorobenzene Contaminated Soil by Mechanochemical Method

The mechanochemical method is a potential way to destroy pollutants such as heavy metals and organic compounds due to its advantages such as complete reaction, adaptation of various pollutants and low energy consumption, etc. Research work was conducted to investigate the feasibility of remediating the persistent organic pollutants (POPs) contaminated soil and how the parameters influence the destruction of the pollutants. In the study, hexachlorobenzene (HCB) was used as a presentative of the POPs in soil. Natural minerals such as albite and magnetite were selected as additives to treat HCB contaminated soil with the application of mechanochemical method. The reasonable operation parameters as well as the soil properties on the destruction of HCB were determined. Analysis such as Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffractometer (XRD), X-ray Photoelectron Spectroscopy (XPS) and Raman Spectrometer were conducted for the supplement of mechanism study. A degradation rate of 92.5% for HCB was achieved under the optimal reaction condition. According to the XPS analysis results, the transformed valence state of iron, provided electrons for the destruction of HCB, on the basis of specific structure of albite. The amorphous carbon and graphite carbon were the final products of the destruction of HCB in the process of ball milling. The selected reagents with albite and magnetite would be viable for the damage of other POPs by mechanochemical method.

An Unexpected Reaction of Isodehydracetic Acid with Amines in the Presence of 1-Ethyl-3-(3-dimethylaminopropyl) Carbodiimide Hydrochloride Yields a New Type of β-Enaminones

The reaction of isodehydracetic acid with amines was serendipitously found to afford β-enaminones in the presence of the coupling agent 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC). Under the optimal reaction condition, 23 examples of α-aminomethylene glutaconic anhydride were obtained at approximately 30−80% yields. This is a concise, operationally simple method to expediently synthesize a new type of β-enaminone-containing compound.

Microwave-Assisted Homogeneous Acid Catalysis and Chemoenzymatic Synthesis of Dialkyl Succinate in a Flow Reactor

Two new continuous flow systems for the production of dialkyl succinates were developed via the esterification of succinic acid, and via the trans-esterification of dimethyl succinate. The first microwave-assisted continuous esterification of succinic acid with H2SO4 as a chemical homogeneous catalyst was successfully achieved via a single pass (ca 320 s) at 65–115 °C using a MiniFlow 200ss Sairem Technology. The first continuous trans-esterification of dimethyl succinate with lipase Cal B as an enzymatic catalyst was developed using a Syrris Asia Technology, with an optimal reaction condition of 14 min at 40 °C. Dialkyl succinates were produced with the two technologies, but higher productivity was observed for the microwave-assisted continuous esterification using chemical catalysts. The continuous flow trans-esterification demonstrated a number of advantages, but it resulted in lower yield of the target esters.

Optimization of reaction parameters for the green synthesis of zero valent iron nanoparticles using pine tree needles

In the current study, the optimal reaction condition for fabrication of INPs by using pine tree (Pinus eldarica) leaf extract was developed. A fractional factorial design was utilized to screen the effective parameters in the green synthesis reaction, and central composite face design was employed to achieve the optimal reaction condition. Leaf extract and iron precursor concentrations were found to be the most effective parameters for the fabrication of INPs. Physicochemical characteristics of the obtained nanoparticles were evaluated by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffractometer (XRD), vibrating sample magnetometer (VSM), thermogravimetric analysis (TGA), and derivative thermo gravimetric (DTG). The prepared particles were found to be zero-valent iron nanoparticles without any iron oxide impurities. Nanoparticles were spherical in shape with diameters ranging from 8 nm to 34 nm with a mean particle size of 18 nm. The fabricated particles were amorphous with a low magnetization value of 33 memu/g.

Optimization of Lipase-Catalyzed Synthesis of Fatty Hydroxamic Acids from Terminalia Catappa L. Kernel Oil

Fatty hydroxamic acids (FHA) have been successfully synthesized from Terminalia catappa L. (local name: ketapang) kernel oil by a one-step lipase catalyzed reaction. The use of immobilized lipase as a catalyst to synthesize FHA has several advantages such as a simple purification of product and environmentally friendly. In addition, it also allows the reaction to be carried out under mild conditions, which reduces the reaction’s side products. The optimal reaction condition obtains were 40°C temperature reaction for 25 h with the ratio of ketapang seeds oil (g): hydroxilamin (mmol) is 1 : 2.861 mmol and the ratio of lipase enzyme (g): ketapang kernel oil (g) is 0,015: 1. Amount of hydroxamic group in 1 gr of sample is 2.46 mol. Qualitative test of FHAs was carried out by color test and FTIR. Complex colors of the FHA with copper (II) and iron (III) are green and dark red, respectively. For FTIR analysis of FHAs group, various peak appeared such as C=O amide (1685 cm-1), O-H (3434 cm-1), N-H (3261,09 and 1568,64 cm-1) and C-N (939,91 cm-1).

Contrast Experiment on Advanced Treatment of Pharmaceutical and Paper-making Wastewater through Cinder Fenton-like Process

The Fenton-like process of catalyzing H2O2 with Fe2+ and cinder is adopted to subject pharmaceutical and paper-making wastewater to advanced treatment. The influence of each factor is determined using orthogonal experiment and single factor test. The optimal combination of influencing factors is 0.3mmol · L-1 of FeSO4 · 7H2O, [H2O2]:[Fe2+]=8:1 and 10g · L-1 of pyrites cinder. The reaction time in pharmaceutical wastewater and paper-making wastewater is 30min and 60min respectively, testifying to the fact that the reaction in pharmaceutical wastewater is faster than that in paper-making wastewater and the lower utilization rate of cinder in pharmaceutical wastewater. Under the optimal reaction condition, the COD removal rate of these two kinds of wastewater can reach as high as 65% and 72%. Characterized by simple operation and requiring less reagent dosage, this method does not have to regulate the pH of flooding water and allows the repeated usage of cinder.

Development and Application of a Novel Nucleic Amplification Kit on Rapid Detection of Various Types of Staphylococci Strains

A loop-mediated isothermal amplification (LAMP) method for rapid detection of various staphylococci strains and associated antibiotic resistance determinant had been developed and evaluated in this study. Six primers, including outer primers, inner primers and loop primers, were specially designed for recognizing eight distinct sequences on four targets: 16Sr RNA,femA,mecA, andorfX. Twenty-seven reference strains, including various species of gram-negative and-positive isolates, were included in this study to evaluate and optimize LAMP assays. The optimal reaction condition was found to be 65°C for 45 min, with detection limits at 100 fg DNA/tube and 10 CFU/reaction for 16S rRNA, 100 fg DNA/tube and 10 CFU/reaction forfemA, 1 pg DNA/tube and 100 CFU/reaction formecA, 10 DNA/tube and 10 CFU/reaction fororfX, respectively. Application of LAMP assays were performed on 166 various types of staphylococci isolates, the detection rate of LAMP assays for the 16Sr RNA,femA,mecA, andorfXwas 100% (166/166), 98.5% (64/65), 94.3% (66/70), and 98.6% (69/70) and the negative predictive value (NPV) was 100%, 98.1%, 92.3%, and 92.7% respectively; with a 100% positive predictive value (PPV) for all three targets. In conclusion, LAMP assays were demonstrated to be useful and powerful tools for rapid detection of various staphylococci strains.