Influence of pH on the transport of nanoscale zinc oxide in saturated porous media

Widespread use of nanoscale zinc oxide (nZnO) in various fields causes subsurface environment contamination. Even though the transport of dissolved zinc ions in subsurface environments such as soils and sediments has been widely studied, the transport mechanism of nZnO in such environments is poorly understood. In addition, nZnO is often combined with stabilizers or dispersing agents to prevent its aggregation in products. The purpose of this study is to determine the influence of pH on the transport properties of pristine nZnO and carboxymethyl cellulose (CMC) stabilized nZnO (CMC–nZnO) suspensions in silica sand packed column under saturated flow conditions. Transport data were collected at different pHs (pHs: 3, 7, 9, and 11) under 1 mL/min flow rate conditions in a 1.1 cm diameter column. It is found that the transport trends of pristine nZnO and CMC–nZnO were different. For pristine nZnO, mobility of total Zn reached a minimum around its point of zero charge (pH 8.9). Whereas in the case of CMC–nZnO, the mobility of total Zn decreased as the pH of the solution pH increased from 3 to 11. ZnO and Zn ion mixture were separated using diafiltration membrane. It showed that most of the nZnO and CMC–nZnO exists as Zn ion at pH 3 before and after eluting from the sand packed column whereas at pH 11, they exist as particles. This study shows the strong influence of pH and stabilizing agents on nZnO transport. These factors should be considered during subsurface transport of nZnO.     

The Stefan problem of evaporation of a volatile component from a binary liquid mixture

The study is concerned with the Stefan problem of evaporation of a volatile component from its solution with a virtually non-volatile material. The analysis provides an analytical solution to the problem based on mass-transfer fundamentals. Results yield the evaporation rate, interfacial mole fractions, concentration profiles in the gas and liquid phases, and the location of the evaporation front. The analysis can be used to provide the binary liquid diffusion coefficient of the volatile component based on experimental data for the liquid–gas interface position as a function of time. The requirements for such a measurement are discussed in terms of the volatility of the evaporating component and its initial concentration in the liquid mixture. Fig. 1 Gas–liquid interface movement in a partially filled tube

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杂化化合物(C7H11N2)2[CdCl4]·0.5H2O的晶体结构、光谱表征和光学性质

开发了标题化合物（C₇H₁₁N₂）₂[CdCl₄]·0.5H₂O （C₇H₁₁N₂=4-（二甲基氨基）吡啶鎓）的制备程序,并得到良好的收率和纯度。Cd（Ⅱ）离子在略微扭曲的四面体环境中与4个氯离子配位。晶体排列显示出层状结构,有机层和无机层交替排列,平行于（001）平面,位于x=n+1/2（n∈Z）。在晶体中,有机层和无机层通过C—H…Cl、C—H…O、N—H…Cl和N—H…O氢键相互作用连接。Hirshfeld表面分析和结构的指纹图表明分子堆积受氢键和π堆积的控制。UV-Vis漫反射光谱使我们能够用Tauc外推法确定具有半导体特性的3.596 eV的直接带隙。观察到的在562 nm处具有最大值的光致发光带归属于4-（二甲基氨基）吡啶鎓阳离子中的激发π-π^*态。     

Stereoselective synthesis of functionalized vinyl ethers from allyl bromides activated by triethylamine

An efficient coupling reaction of allyl bromides with various alcohols as nucleophiles activated by triethylamine, leading to functionalized vinyl ethers in good yields and with full stereoselectivity.     

The active analog approach applied to the pharmacophore identification of benzodiazepine receptor ligands

Summary Applied to seven potent benzodiazepine-receptor ligands belonging to chemically different classes, the active analog approach allowed the stepwise identification of the pharmacophoric pattern associated with the recognition by the benzodiazepine receptor.A unique pharmacophore model was derived which involves six critical zones: (a) a -electron rich aromatic (PAR) zone; (b) two electron-rich zones ₁ and ₂ placed at 5.0 and 4.5 Å respectively from the reference centroid in the PAR zone; (c) a freely rotating aromatic ring (FRA) region; (d) an out-of-plane region (OPR), strongly associated with agonist properties; and (e) an additional hydrophobic region (AHR).The model accommodates all presently known ligands of the benzodiazepine receptor, identifies sensitivity to steric hindrance close to the ₁ zone, accounts forR andS differential affinities and distinguishes requirements for agonist versus non-agonist activity profiles.Abbreviations Pyrazoloquinolines CGS (2-phenyl-2,5-dihydro pyrazolo [4,3-c] quinoline-3 (3H)-one) - Cinnolinones CIN (2-(4-methoxyphenyl)-benzo [h] 3-cinnolinone - Triazolophthalazines TZPH (3-(4-methoxyphenyl)-6 pyrrolidinotriazolo [4,3-a] phthalazine - Cyclopyrrolones RP 27267, CLO ([6-(5-chloro-2-pyridyl)-6,7-dihydro-7 oxo-5H-pyrrolo [3,4-b]pyrazin-5-yl] 4-methyl-l-piperazine carboxylate) - Phenylquinolines PK (phenyl-2 (morpholinocarbonyl methyl oxy)-4 quinoline - -Carbolines BCC (3-carboethoxy--carboline) - Benzodiazepines: Diazepam DZ (7-chloro-1,3-dihydro-1-methyl-5 phenyl-2H-1,4-benzodiazepin-2-one)     

Statistical validation of sulfate quantification methods used for analysis of acid mine drainage

Turbidimetric method (TM), ion chromatography (IC) and inductively coupled plasma atomic emission spectrometry (ICP-AES) with and without acid digestion have been compared and validated for the determination of sulfate in mining wastewater. Analytical methods were chosen to compare the performance of a portable field turbidimetric instrument and to validate the underlying assumption utilized in conversion of total sulfur to sulfate during ICP-AES analysis. Accuracy and precision of analytical techniques were compared to one another using control and field samples collected from a mine site using the Bonferroni multiple comparison test. Effects of sample dilution, filter pore size and acidification on sulfate quantification were also studied. The results showed that IC and ICP-AES with and without acid digestion provided excellent recoveries in the case of control samples (within 90-110%). These analytical methods also showed lower relative standard deviation for both control and field samples. On the other hand, performance of the turbidimetric method was severely affected by sample dilution and acidification, and also revealed poor sulfate recoveries for control samples ranging from 0 to 83.5%. Analysis of variance (ANOVA) was used to evaluate the response (sulfate concentration) obtained from factorial design. Analytical method had significant effect (P < 0.0001) on the sulfate quantification. The interaction between determination method and sample dilution was more significant than other two-way interactions.     

Synthesis of [MnCl<Subscript>3</Subscript>(H<Subscript>2</Subscript>O)<Subscript>2</Subscript>(Hatz)]·H<Subscript>2</Subscript>O and investigation of its structure via X-ray diffraction,spectroscopic measurements and DFT calculations

The 3-amino-1,2,4-triazole (atz)-based manganese complex was prepared and characterized through single-crystal X-ray diffraction, IR, EPR, and UV–visible spectroscopy. In the crystal structure, individual complex are interconnected through N(O)–H…Cl hydrogen bonds into 1D undulating chains running parallel to the [110] direction of the unit cell. Chains further grow into 2D supramolecular layers by way of the lattice water molecules of coordination and the chloride anions (O–H…Cl). Layers pack along the b-axis of the unit cell mediated by O–H…Cl(N) and N–H…O(Cl) hydrogen bonds forming a 3D supramolecular architecture. The theoretical calculations were also performed to optimize the structure of the complexes in the gas phase to confirm the structures proposed by X-ray crystallography. In addition, IR and UV–visible spectra of complex were calculated and compared with the corresponding experimental spectra to complete the experimental structural identification. The three-dimensional Hirshfeld surface (3D-HS) and their relative two-dimensional fingerprint plots (2D-FP) reveal that the structure is dominated by H…Cl/Cl…H (50.5%), H…O/O…H (11.3%) and N…O/O…N (10.2%) contacts.     

Remote control of extended depth of field focusing

We propose a novel system allowing remote control of the location of the extended focal depth region. This system may find applications in situations where controllable optical access to an enclosure is needed and it is desirable to minimize the movement of the focusing lens. Our scheme uses three axicons, two external ones generating a ring and an internal one producing the focal region. We present a proof of concept of this system, consisting of measurements of the longitudinal and transverse intensity distributions, for a reference configuration and one with a displaced position of the extended depth of field focus.     

A generalization of Fan��s matching theorem

We introduce a generalized coercivity type condition for setvalued maps defined on topological spaces endowed with a generalized convex structure and we extend Fan’s matching theorem.