Effect of biochar on the mobility and photodegradation of metribuzin and metabolites in soil‒biochar thin-layer chromatography plates

Biochars obtained by biomass pyrolysis have been proposed as a soil amendment to improve soil properties and fertility as well as to retain pesticides and other environmental contaminants. The present study investigates the degradation of metribuzin herbicide and its metabolites deamino- (DA), deaminodiketo- (DADK) and diketo- (DK) metribuzin under simulated solar light and dark conditions as well as their mobility using TLC plates coated with soil and soil?biochar mixtures at 1% and 5% w/w ratio. Biochar was characterised by X-Ray diffraction, porosimetry, scanning electron microscopy and Fourier transform infrared spectroscopy. Degradation under light conditions followed biphasic kinetics, with bi-exponential model fitted better for the soil substrate, while the Gustafson–Holden model was found more appropriate to describe degradation kinetics in 1% soil/biochar mixture. In soil, DA presented the lowest degradation rate (DT₅₀:440.9 h), followed by metribuzin (DT₅₀:208.0 h), DADK (DT₅₀:110.8 h) and DK (DT₅₀:106.5 h). The addition of biochar reduced drastically the degradation or even inhibited the photolytic process for the studied reaction period. The mobility retention factor (Rf) in soil ranged from 0.49 for metribuzin to 0.63 for DADK. The addition of biochar practically immobilises the compounds in the surface layer as Rf ranged from 0.14 to 0.10 for metribuzin and from 0.23 to 0.16 for DADK in soil/biochar mixtures 1% and 5%, respectively. In conclusion, the addition of biochar reduced dramatically the photodegradation rates as well as the mobility of metribuzin and its metabolites due to increased adsorption.     

Production and Characterization of β-Glucanase Secreted by the Yeast Kluyveromyces marxianus

An extracellular β-glucanase secreted by Kluyveromyces marxianus was identified for the first time. The optimal conditions for the production of this enzyme were evaluated by response surface methodology. The optimal conditions to produce β-glucanase were a glucose concentration of 4 % (w/v), a pH of 5.5, and an incubation temperature of 35 °C. Response surface methodology was also used to determine the pH and temperature required for the optimal enzymatic activity. The highest enzyme activity was obtained at a pH of 5.5 and a temperature of 55 °C. Furthermore, the enzyme was partially purified and sequenced, and its specificity for different substrates was evaluated. The results suggest that the enzyme is an endo-β-1,3(4)-glucanase. After optimizing the conditions for β-glucanase production, the culture supernatant was found to be effective in digesting the cell wall of the yeast Saccharomyces cerevisiae, showing the great potential of β-glucanase in the biotechnological production of soluble β-glucan.     

Synthesis and Characterization of the Polyacrylonitrile-block-poly（methyl acrylate） by RAFT Technique

Reversible addition-fragmentation chain transfer polymerization (RAFT) was firstly reported in 1998 by Rizzardo1. This technique provided the possibility to synthesize polymers with controlled molecular weight, narrow molecular weight distribution, and we…     

Synthesis, Characterization and the Effect of Glucose-lowering of Guanidino Acid Oxovanadium（Ⅳ） Complexes

Two guanidino acid oxovanadium(Ⅳ) complexes have been synthesized. Preliminary tests in vivo have shown that the two title complexes all display lowering glucose activity in vivo to STZ-rats. The effect of glucose-lowering of guanidino acetic acid oxovanadium(Ⅳ) complex in vivo is higher than that of guanidino propanoic acid oxovanadium(Ⅳ) complex.     

Synthesis and Characterization of Polyimide‐Silica Hybrids: Effect of Matrix Polarity on the Mechanical and Thermal Properties

Polyimide‐silica hybrid materials have been prepared through the sol‐gel process by mixing various proportions of tetraethoxysilane (TEOS) with polyamic acids (PAAs). Two types of PPAs were employed. The first was obtained by reacting an equimolar mixture of oxydianiline (ODA) and pyromellitic dianhydride (PMDA) in dimethylactamide (DMAc) as solvent. The second was prepared using a mixture of ODA and 2,2‐Bis(3‐amino‐4‐hydroxyphenyl)hexafluoropropane (6F‐OHDA) in molar ratio 9:1, respectively and reacting with a stoichiometric amount of PMDA in DMAc. Polyamic acids were converted to polyimides and a sol‐gel reaction proceeded simultaneously by heating the hybrid films to 300°C. The hydroxyl groups from 6F‐OHDA allows the secondary bonding between the polyimide and growing silica phase and thus retard the gross phase separation. Only the 10 mol% addition of 6F‐OHDA in the polyimide chain resulted in a drastically different microstructure for the resulting hybrids. SEM, stress‐strain analysis, temperature variation of storage and loss modulus, and thermal stability were used to characterize the hybrid materials. Properties of both types of hybrids have been compared and related to the two different types of structures of polyimides used in the preparation of the hybrids.     

Synthesis and Characterization of Linked Clusters Capped by Alkylidyne

1 INTRODUCTION Constructing higher nuclearity clusters with well-defined dimensions and structures provide a rather active field of chemistry with potential applications in areas including nanotechnology, molecular recognition and catalysis[1~4]. A continuing effort has been directed toward developing a better methodology for systematic synthesis of supracluster compounds through molecular design [5,6]. On the basis of extensive investigation on the metal exchange reaction in cluster com…     

Capacitance Characterization of the Effect of pH Value on the Self—assembled Monolayers of Octadecanethiol

In this paper,the membrane capacitance(Cm),which was obtained from the ecectrochemical impedance spectroscopy(EIS) method,was used to characterize the effect of pH value on the self-assembled monolayers(SAMs) of octadecanethiol(18SH) for the first time.The results not only strongly proved that inorganic ions could penetrate the SAMs of 18SH,but also ascertained that SAMs of 18SH were not an absolute of free of ion-penetration.Verifying the existence of pin-holes in the octadecanethiol SAMs was the main contribution of this paper,which coincided with the former conjecture very well.     

Characterization of the Interaction between Bovine Serum Albumin and Lomefloxacin by Capillary Zone Electrophoresis

Three capillary zone electrophoresis (CZE) methods of the frontal analysis (FA), vacancypeak (VP) and simplified Hummel-Dreyer (SHD) were applied to investigate interaction betweenbovine serum albumin (BSA) and lomefloxacin, the experimental condition was established after alarge number of tests. Based on the site-binding model, the binding parameters were measuredaccording to the site model by Scatchard.     

Characterization of Galactosyl-neoglycoalbumin by MALDI-TOF-MS

Matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS, model AXIMA CFR ) was used to analyze galactosyl-HSA (human serum albumin) synthesized in our laboratory. It clearly showed that HSA covalently combined with galactoses. Galactosyl-HSA is pure and the ratio of galactosyl residues to protein is 48:1.     

High-Throughput Synthesis and Characterization of Aryl Silicones by Using the Piers–Rubinsztajn Reaction

Arylsilicones are widely exploited for their thermal and optical properties. The creation of phenylsilicone elastomers with specific physical properties is typically done by a “one-off” formulation and test process. Herein, it is demonstrated that high-throughput synthesis methods can be used to rapidly prepare a series of arylsilicone elastomers and then the relative impact of different aryl groups on their physical properties is assessed. Aromatic groups were incorporated into polydimethylsiloxane (PDMS) elastomers by exploiting the relative reactivity of different functional groups in the Piers–Rubinsztajn reaction. To analyze trends in the silicone mechanical properties as a function of increasing aryl concentration—structure/property relationships—libraries of elastomers were both quickly synthesized and characterized by using high-throughput suites starting from low viscosity silicone oils/monomers in 96-well plates. Liquid handling parameters were optimized to effectively work with the silicones. Incorporating aryl instead of alkyl crosslinkers into the PDMS backbone increased the silicone elastomer modulus by approximately 50 % (at a crosslink density of 6 %); elastomers prepared with an aromatic crosslinker with three contact points led to much higher moduli compared with those with one contact point at the same crosslink density. When located at precise rather than random points on the silicone chains, diphenylsilicones had lower moduli than analogous monophenylsilicones.     

Synthesis and Characterization of Star-like Liquid Crystals Centered by Silicon

The synthesis and characterization of two new star-like liquid crystals are reported. They are made of a silicon core and four alkoxyazobenzene monomers in the periphery. Theirp hase behaviors and the structures are determined by infrared absorption spectroscopy (IR), nuclear magnetic resonance spectroscopy (NMR), elemental analysis (EA), polarizing optical microscope (POM) and differential scanning calorimetry (DSC).     

Synthesis and Characterization of the β-BaB2O4 Phase Obtained by the Polymeric Precursor Method

A modified polymeric precursor method based on the Pechini process was used to synthesize -BaB₂O₄ (-BBO) crystalline phase. D-sorbitol (C₆H₁₄O₆) was used as a polymerizing agent to avoid the loss of boron during the samples' calcination and crystallization. The -BBO stoichiometric crystalline phase was only obtained when sorbitol was added to the solution. The results of Raman spectroscopy show that the amorphous phase is only completely eliminated when the samples are heat-treated at 750°C for 20 h. Thin films of -BBO phase displaying a preferred orientation were obtained when crystallized at 750°C for 2 h and deposited on sapphire substrate.     

Characterization of the Microstructure Changes of Polypropylene Induced by Pan—milling

1 INTRUDUCTION Mechanochemistry is an interdisciplinary science based on chemistry and mechanics, related to the changes of structure, properties of matters and the preparation of new materials induced by external mechanical actions, such as attrition, milling, grinding, pulverization, impact etc. Mechanochemical process, such as high-energy ball milling and mechanical alloying, has become a popular method to make nanocrystalline materials and find their wide applications to numerous clas…     

Synthesis and Characterization of Star-branched Polyisobutylene by Combination of Anionic Polymerization and Cationic Polymerization

The construction of polymer materials with controlled compositions, topologies, and functionalities has been the enduring focus in current research1,2. Among them, star polymers have been extensively studied for a long time, due to their markedly lower so…     

CZTS nanoparticles by one-pot sonochemical route – Effect of power density,pH and bath temperature

One-pot synthesis of nanosized CZTS particles using ultrasound employing citric acid as the complexing agent has been studied. The CZTS nanoparticles synthesis at different bath temperatures, pH and power densities was attempted. The power density used for the reaction did not alter the crystallinity and morphology of the synthesized particles. However, the chemical composition and the bandgap of the particles showed significant variation with the applied power density. Apart from affecting the composition, bandgap and electrical characteristics, the bath temperature considerably affected the crystallinity of the CZTS nanoparticles. Based on the conditions of synthesis, the particle size ranged between 25 ​nm and 40 ​nm. Depending on the process conditions, the bandgap of the particles varied between 1.4 ​eV and 2.9 ​eV. The samples synthesized under a power density of 46 ​W ​L⁻¹ and 40 ​°C bath temperature with reactant pH of 3.5 showed composition closer to the required stoichiometry.     

Effect of Pb2＋ on the Kinetic and Spectral Characterization of Ribulose-1,5-bisphosphate Carboxylase/Oxygenase

本文利用各种光谱手段在体外研究了各种浓度的Pb2+对菠菜Rubisco活性影响的机制。 结果表明,Rubisco活性随着Pb2+处理浓度的增加而逐渐下降,低浓度Pb2+下Rubisco的动力学常数和最大反应速率分别为1.74 µM 和 0.42 µmol CO2/mg protein∙min,高浓度Pb2+下Rubisco的动力学常数和最大反应速率分别为11.82 µM and 0.28 µmol CO2/mg protein∙min。光谱学分析证实Pb2+可直接结合到Rubisco上, 其结合位点数为1.1个,结合常数分别为8.63×104 和 2.18×105 L/mol。ICP-MS和圆二色谱分析证实Pb2+取代了酶活性中心的Mg2+ 并改变了酶的构象。     

Synthesis and Characterization of Zirconia Nanocrystallites by Cationic Surfactant and Anionic Surfactant

1 INTRODUCTION Zirconia is a kind of metallic oxide with high mel- ting point. It is highly corrosion-resistant for acid fu- sant and neutral fusant, thus it can be used as refrac- tory material, and it can also be utilized as acid acy- loxy bi-functional catalystic material owing to hav- ing both acid and alkali surface centers[1]. Moreover, zirconia has superior ion-exchange capacity as well as chemical and mechanical stability, therefore, it can also be applied as a catalyst carrier. …     

Effect of hydrophobicity on the stability of sol–gel silica coatings in vacuum and their laser damage threshold

Silica antireflective coatings modified by hexamethyldisilazane (HMDS) were deposited on clean substrates (silicon wafer or K9 glass blanks) by sol–gel processing. The effects of HMDS on the contamination resistant capability and laser-induced damage threshold (LIDT) of coatings were investigated. Transmission electron microscopy revealed that a stable sol with uniformly distributed silica particles with an average particle size of about 15 nm was acquired by adding appropriate amount of HMDS into the standard SiO₂ sol. With the modified sol the resultant coatings were hydrophobic and the contact angle for water increased with increasing amount of HMDS in the reaction mixture. Such increase in hydrophobicity was not the result of surface roughness. The antireflective properties were retained after HMDS-treatment and the maximum transmission values were above 99 %. The introduction of HMDS into silica sols had also increased the LIDT of coatings from 24.3 to 37.0 J cm^?2 when the molar ratio of HMDS to tetraethoxysilane was 0.05:1. The increase in LIDT was attributed to the decrease of nodular defect and uniform microstructures of coatings as an effect of the HMDS modification. After some of the hydroxyl groups on the surface of the SiO₂ particle were replaced by methyl groups, from which the SiO₂ particle gained a water-repellent surface, the stability of coatings in vacuum was increased. The maximum transmission values of modified coatings decreased by only 0.25 % after storage under vacuum for 168 h. In contrast, the standard sol–gel silica coatings decreased about 2 % under similar conditions. The LIDT of modified coatings remained as high as 30.8 J cm^?2, more than that of standard coatings stored for the same duration in air.     

Effect of ionic strength on the stabilities of ciprofloxacin – Metal complexes

Proton–ligand dissociation constant of 1-cyclopropyl-1,4-dihydro-4-oxo-7-(1-piperazinyl) quinolone-3-carboxylic acid is ciprofloxacin and metal–ligand stability constants of its complexes with some metal ions have been determined potentiometrically in the presence of (0.01, 0.02 and 0.03 mol/dm³) NaClO₄. The order of the stability constants of the formed complexes increases in the sequence Cu²⁺, Fe³⁺, Ni²⁺ and Zn²⁺ and decreases with increase in the concentration of ionic strength.     

Characterization and classification of stationary phases in HPLC and SFC – a review

Packed column supercritical fluid chromatography (pSFC) is an attractive technique in drug discovery related analysis because it offers several advantages over the more commonly used high-performance liquid chromatography (HPLC) technique. The environmental-friendly CO₂ mobile phase, the high-throughput capacity, the increased efficiency and the lower operational costs give SFC additional benefits over HPLC in analysis related to drug development. The latter technique is well established and has been used for decades in the pharmaceutical industry. On the other hand, SFC is still in its infancy, even though the technique has been known for decades and researchers are still discovering the possibilities and limitations of this technique.