An Exemplar Imidazoline Surfactant for Corrosion Inhibitor Studies: Synthesis,Characterization, and Physicochemical Properties

An optimized one-pot recipe has been developed to synthesize a surfactant molecule, referred to as OMID, consisting of an imidazoline head group and aliphatic tail, which is an exemplar corrosion inhibitor for carbon steel in acidic solutions. As evidenced by gas chromatography, ¹H and ¹³C nuclear magnetic resonance, and Fourier-transform infrared data, a high-purity product was achieved without the use of either a solvent or catalyst. Critical micelle concentration values and corrosion inhibition efficiencies ( η %) were determined in aqueous solutions of hydrochloric acid and sulfuric acid using surface tensiometry and linear polarization resistance measurements, respectively. Hydrolysis of the imidazoline head group as a function of pH (0–11) was explored with ultraviolet–visible absorption spectroscopy. In addition, N 1s and C 1s X-ray photoelectron spectroscopy data were acquired from both surface-adsorbed OMID and a multilayer of the imidazoline head group of OMID. These latter data are highly relevant to those attempting to understand OMID inhibition chemistry.     

按需出版在挑战中快步前行

在西方,按需出版已经得到普及,每年都会有40万种图书以按需出版的方式出版,超过90%的西方出版商已经开始探寻属于自己的按需出版道路。 这是一家拥有7年历史的按需出版界大亨,其足迹遍布120多个国家与地区,他与亚马逊以及Ingram公司等巨头有着密切的合作,向50多个国家销售电子书和书籍,并为全球10000多名作者提供出版服务——他就是按需出版领域的领跑者,美国全球按需出版公司（PODG）。近日,PODG公司总裁Robert Fletcher接受本刊独家采访,畅谈了PODG的按需出版商业模式,以及他眼中的＂中西方＂按需出版市场特点及前景展望。     

Association of Perfluorooctanoic Acid (PFOA) and Perfluorooctane Sulfonate (PFOS) with age of puberty among children living near a chemical plant

Animal studies suggest that perfluorocarbons (PFCs) may alter sexual maturation. Relationships of human PFC exposure with puberty are not clear. We conducted a cross-sectional study to investigate whether perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) were associated with indicators of sexual maturation in a 2005-2006 survey of residents with PFOA water contamination from the Mid-Ohio Valley. Participants were 3076 boys and 2931 girls aged 8-18 years. They were classified as having reached puberty based on either hormone levels (total >50 ng/dL and free >5 pg/mL testosterone in boys and estradiol >20 pg/mL in girls) or onset of menarche. We estimated the odds of having reached puberty classified by these criteria and the fitted median age of reaching puberty in relation to serum PFOA and PFOS concentrations measured when puberty status was assigned. For boys, there was a relationship of reduced odds of reached puberty (raised testosterone) with increasing PFOS (delay of 190 days between the highest and lowest quartile). For girls, higher concentrations of PFOA or PFOS were associated with reduced odds of postmenarche (130 and 138 days of delay, respectively). In conclusion, our study showed a later age of puberty in this population correlated with PFC concentrations.     

Determination of mineral element composition of Ayoyo,Baobab and Dandelion vegetable green leaves in Ghana using instrumental neutron activation analysis

The present investigation was undertaken to determine the nutritional compositions (mineral elements) of three green leafy vegetable; Dandelion (Taraxacum Officinale), Ayoyo (Corchorus Olitorius) and Baobab (Adasonia Digitata). The ultimate goal is to improve nutrition and health by advocating for increased consumption of indigenous green leafy vegetables with an objective to increasing public acceptance, awareness and utilization. The mineral elements were determined using instrumental neutron activation analysis, over 20 elements were detected. However, 14 mineral elements were quantitatively evaluated on the basis of k₀-method and relative comparator method. The leaves were characterized with high concentration of Mg, Ca, Cl and K, and substantive amount of Mn, Fe, Zn, Cu and I. The composition of the mineral elements and its respective percent contribution to Recommended Dietary Allowance/Adequate Intake (RDA/AI) for various life groups indicates that reasonable consumption of any of the three green leafy vegetable can contribute substantive amount of daily nutritional requirement for minor nutrients like; I, Cu, Zn, Mn, and Fe as well as major nutritional (Mg, Ca, Cl and K) needs for all life groups. Each of the leaves was also characterize with high K/Na ratios. Tolerable upper intake levels (UL) analysis also showed no significant abuse for the mineral elements determined. Other potential toxic elements (As, Cd and Hg) and non-nutritional minerals (Br, V, Al and Ba) were either not detected or were found in low concentrations.     

Alkane cracking reactions in zeolites with coadsorbed metal halides

HY which is loaded with SbF₅, BCl₃, or BF₃ at low coverages, one metal halide molecule per Brønsted acid site, is shown to be active in the isomerization and cracking of n-hexane and n-butane at room temperature. In contrast, NaY with the same metal halide loading shows greatly reduced activity under identical reaction conditions. The cracking reaction was repeated with DY in place of HY, demonstrating deuterium incorporation into the hexane isomer and light alkane products through interaction with the Brønsted site. Flow reactor studies demonstrate that the conversion is not constant as a function of time on stream, going through an induction period, reaching a maximum, at around 400 s, and then decaying to ~1% after 1 h.     

Temperature gradients drive radial fluid flow in petri dishes and multiwell plates

Liquid in a Petri dish spontaneously circulates in a radial pattern, even when the dish is at rest. These fluid flows have been observed and utilized for biological research, but their origins have not been well‐studied. Here, particle‐tracking to measure velocities of radial fluid flows, which are shown to be linked to evaporation, is used. Infrared thermal imaging was used to identify thermal gradients at the air‐liquid interface and at the bottom of the dish. Two‐color ratiometric fluorescence confocal imaging was used to measure thermal gradients in the vertical direction within the fluid. A finite‐element model of the fluid, incorporating the measured temperature profiles, shows that buoyancy forces are sufficient to produce flows consistent with the measured particle velocity results. Such flows may arise in other dish or plate formats, and may impact biological research in positive or negative ways. © 2016 American Institute of Chemical Engineers AIChE J, 62: 2227–2233, 2016     

Initialising distillation column models

Difficulties associated with the optimisation of distillation column models by non-linear programming are considered. The paper presents a systematic procedure to enable these difficulties to be overcome and proposes a particular formulation of the distillation column model. A certain limiting case of the column model is examined, that of infinite reflux or zero feed. This limiting case considerably simplifies the model and provides a system of non-linear equations that is readily solved. The solution of this problem gives useful information about the purity that can be achieved in the general case and the number of plates needed to attain a given level of purity. The limiting problem provides starting values for the solution of the general column and suggests a homotopy that can be followed if difficulties arise in obtaining convergence. To obtain a stable form of the limiting case requires the general column model to be formulated in a certain way, which to our knowledge has not previously been considered. The ideas have been successfully tested on various multi-column flowsheets involving distillation columns with heat integration.     

Performance evaluation of canine-associated Bacteroidales assays in a multi-laboratory comparison study

The contribution of fecal pollution from dogs in urbanized areas can be significant and is an often underestimated problem. Microbial source tracking methods (MST) utilizing quantitative PCR of dog-associated gene sequences encoding 16S rRNA of Bacteroidales are a useful tool to estimate these contributions. However, data about the performance of available assays are scarce. The results of a multi-laboratory study testing two assays for the determination of dog-associated Bacteroidales (DogBact and BacCan-UCD) on 64 single and mixed fecal source samples created from pooled fecal samples collected in California are presented here. Standardization of qPCR data treatment lowered inter-laboratory variability of sensitivity and specificity results. Both assays exhibited 100% sensitivity. Normalization methods are presented that eliminated random and confirmed non-target responses. The combination of standardized qPCR data treatment, use of normalization via a non-target specific Bacteroidales assay (GenBac3), and application of threshold criteria improved the calculated specificity significantly for both assays. Such measures would reasonably improve MST data interpretation not only for canine-associated assays, but for all qPCR assays used in identifying and monitoring fecal pollution in the environment.     

The cost of a package plant membrane bioreactor

The capital and operating costs associated with a small package plant MBR for small-scale domestic duty has been appraised based on a medium-strength municipal wastewater. The three main membrane configurations were considered, these being multi-tube, hollow fibre and flat sheet, with the most appropriate plant design chosen for each configuration. The analysis proceeded via a consideration of the estimated amortised capital costs of the plant individual components and their installation, coupled with operating costs based largely on energy demand and residuals management. Energy demand was calculated from aeration and pumping costs, with aeration based on a combination of empirical relationships for membrane aeration and mass balance, and the modified Activated Sludge Model version 2 used for estimating tank size and sludge generation. Results indicate that it is possible to produce a single household MBR at a capital cost similar to the current market cost for package treatment plants. Desludging and maintenance of these plants is similar but power requirements for an MBR are around 4 times that associated with more conventional package plants. Economies of scale exist from 6-20 p.e. plants but above 20 p.e. there is little cost difference per head, due to the design assumptions made. CAPEX and OPEX are to some extent interchangeable; reductions in CAPEX are associated with an increase in OPEX and vice versa. Whilst costs are high, the market for package MBRs is significantly influenced by the recycling potential of the effluent produced.     

Hydrogen and oxygen from water—II: Some considerations in the reduction of the idea to practice

An analytical model of an archetypal device for using solar energy in a one-step thermochemical process for producing hydrogen and oxygen from water is presented. It is used to help us anticipate and evaluate sources of irreversibilities associated with the operation of various components of such a device and to suggest alternatives which should be considered.