Antimicrobial performance of nanostructured silica–titania sieves loaded with izohidrafural against microbial strains isolated from urinary tract infections

This study aimed to examine the efficiency of novel bioactive nanostructures represented by silica–titania sieves used as carriers for a new antibacterial agent izohidrafural against bacterial strains isolated from nosocomial urinary tract infections, by using biological quantitative assays. Several release trials have been established and compared with MCM-41 in parallel experiments to achieve the optimum release profile. The obtained systems showed that silica–titania sieves loaded with izohidrafural proved to be the most active material against Klebsiella pneumoniae (average minimal inhibitory concentration [MIC] 40.62 μg/mL), desaminase-positive strains (average MIC 2.925 μg/mL), and Proteus mirabilis (average MIC 9.37 μg/mL), the last being reported with the highest growth rate in the urinary tract catheters. In contrast, the nonloaded silica–titanium sieves exhibited the highest antimicrobial activity against the Gram-positive cocci. Izohidrafural exhibited the highest antimicrobial efficiency, superior to the common drug nitrofurantoin against most Escherichia coli strains, with average MIC of 4.68 μg/mL.     

One-step synthesis of hollow UO2 nanospheres via radiolytic reduction of ammonium uranyl tricarbonate

Black precipitates were successfully obtained by radiolytic reduction of ammonium uranyl tricarbonate in the aqueous solution of HCOONH_4 by one step.TEM,SAED,EDS,and XRD analysis indicated that the precipitates consist of hollow UO_2 nanospheres(φ:30-50 nm,wall thickness:8-15 nm,and cavity diameter:10-20 nm).The effect of HCOONH_4 concentration,irradiation time and dose rate on the morphology,and size of nanospheres was investigated.Then,a gas-bubble template mechanism was proposed.     

Why do ammonium salt/phenol-based deep eutectic solvents show low viscosity?

The viscosity of deep eutectic solvents (DESs) plays an important role in determining how they are used industrially. In order to gain a deeper insight into the parameters which affect the viscosity of ionic DES, a series of systems composed of ammonium salts and two types of representative donors were prepared and characterized. They were investigated by quantum-chemistry calculations and molecular dynamics simulations. The viscosity of phenol/4-methylphenol-based system is much lower than that of glycolic acid-based system. Moreover, DESs containing glycolic acid exhibit higher activation energy values compared with DESs containing phenolics. It was found the existence of a strong charge transfer complex between glycolic acid and ammonium salt, thus suggesting its vital role in the fluidity difference of studied mixtures. The hydrogen bonds of glycolic acid-based system are partially covalent and partially electrostatic, manifested via atoms in molecules (AIM) analysis. Additionally, Cl^??HO_{phenolic hydroxyl} is expected to be less covalent than Cl^??HO_carboxyl, which is also identified by lower delocalization index in the AIM basin. The interaction network stability of glycolic acid-based DES is more robust than that of phenolics-based one due to the strong covalency of hydrogen bond. This is the main reason that ammonium salt/phenol-based DESs show low viscosity. This work gives new perspectives on more rational design of novel DES with low viscosity.     

Ca2+-Mg2+-Zn2+体系在水溶性聚磷酸铵溶液中螯合规律的研究

近年来,水溶性聚磷酸铵在液体肥料和复合肥料的领域受到了广泛的关注,并在发达国家中得到了大面积的推广及应用。在pH值为5.5~8.0、温度为278.15 K~323.15 K的条件下,本文采用滴定法研究Ca_²⁺-Mg_²⁺-Zn_²⁺体系在聚磷酸铵溶液中的螯合规律。实验结果表明：相同质量分数的聚磷酸铵溶液对金属离子的螯合量会随着体系中Ca_²⁺、Mg_²⁺、Zn_²⁺的摩尔浓度的变化而变化;随着温度的升高而逐渐降低;随着pH的增加而逐渐增加;随着聚合度的升高而逐渐增加。采用傅里叶红外光谱对聚磷酸铵和A₁B₃C₃体系的螯合物进行表征。     

阻燃抗菌羊毛织物的制备及其性能

利用分子间氢键和电荷相互作用力,通过层层喷涂组装技术,将带负电的氧化石墨烯(GO)与带正电的支化聚乙烯亚胺(bPEI)交替沉积到羊毛织物表面,制备(GO/bPEI)_n涂层,再喷涂上一层聚磷酸铵(APP),获得(GO/bPEI)_n-APP修饰的阻燃抗菌羊毛织物。通过阻燃性能测试、热失重分析、导热性能测试和抗菌性能分析证明:相比于纯羊毛织物,通过层层喷涂组装技术获得的(GO/bPEI)_n-APP修饰的羊毛织物的阻燃和抗菌性能显著提高。(GO/bPEI)₇-APP修饰的羊毛织物的极限氧指数为30%,对金黄色葡萄糖球菌的抗菌率47%。实验进一步证实,将氧化石墨烯还原成还原氧化石墨烯(rGO)后,(rGO/bPEI)₇-APP修饰的羊毛织物由于表面吸附更多的APP,所以其极限氧指数高达35%,对金黄色葡萄糖球菌的抗菌率也得到提升(64%)。     

Raman study of NH4CI at high pressures

Abstract

The Raman spectrum of ammonium chloride has been carefully studied in the vicinity of its Λ-transition. Spectra were recorded as a function of temperature under various fixed pressures close to 1.6 kbar, which is the pressure required to make the Λ-transition become second order. The critical exponents derivable from the spectroscopic data seem to be as reliable as those from other types of data, even in the multicritical region.     

Efficient and Mild Oxidative Nuclear Thiocyanation of Activated Aromatic Compounds Using Ammonium Thiocyanate and Diacetoxyiodobenzene

Abstract

A mild and general method for the nuclear thiocyanation of electron rich arenes has been developed by the reaction of NH₄SCN with diacetoxyiodobenzene as the oxidant.     

Reductive amination of ketones: novel one-step transfer hydrogenations in batch and continuous-flow mode

Various ketones were efficiently transformed into the corresponding amines using ammonium formate in the presence of Zn dust or 10% Pd/C. The low-cost Zn dust method proved to be effective in amine formation from carbonyl groups at the benzylic side-chain position of aromatic systems, whereas 10% Pd/C was an efficient catalyst in the reductive aminations of carbonyl groups non-conjugated with any π-system. The 10% Pd/C-catalyzed reductions were performed more effectively in a continuous-flow X-Cube reactor than in the batch system.     

A Rapid and Efficient Multicomponent Synthesis of Bi-Quinolines Under Solvent-Free Conditions

An efficient synthesis of substituted condensed quinolino-quinolines has been achieved in a one-pot reaction from 2-hydroxy/mercapto/seleno-4-methylquinoline and 2-mercapto/seleno-3-formyl quinolines using anhydrous ammonium hydroxide as the reductant by microwave irradiation under solvent-free conditions.     

Splitting of libration mode frequencies in the vicinity of orientation phase transition in NH4Br

Abstract

Vibrational spectra of NH₄Br at high pressures up to 4·5GPa have been studied by means of incoherent inelastic neutron scattering using sapphire anvil high pressure cell technique. Libration mode splitting was investigated in the vicinity of the orientation phase transition (P_tr = 2·7 GPa) and this effect disappears if pressure is less or higher than P_tr. This effect is explained in terms of two-well asymmetric potential.