THEORETICAL PREDICTIONS OF STRUCTURES AND VIBRATIONAL INFRARED FREQUENCIES. I. MERCAPTANS AND SULFIDES

Abstract

We report the computed equilibrium geometries and vibrational infrared frequencies of a group of thirteen mercaptans and sulfides. The computations were based on the Gaussian 86 Program Package utilizing 3-21G basis sets. The theoretical bond distances and bond angles are in agreement with the available experimental data. The agreement between computed frequencies and available experimental values seems reasonable. We also used the computations as guidelines for the assignment of available experimental infrared frequencies. We believe that it is possible to make reliable frequency predictions by combining computations with available experimental data for groups of similar molecules. However, it is necessary to introduce different correction factors for different types of vibrational modes if we use 3-21G basis sets.     

Reducing methane formation in methanol to olefins reaction on metal impregnated SAPO-34 molecular sieve

SAPO-34 silicoaluminophosphate molecular sieve produces large amounts of methane at elevated temperatures in the methanol to olefins (MTO) process. This significantly reduces the lower olefins selectivity a key factor in determining the commercial viability of this catalyst. Impregnation of the SAPO-34 molecular sieve with metal ions such as K, Cs, Pt, Ag and Ce was found to reduce the amount of methane significantly at higher temperatures thereby increasing the lower olefins selectivity. This observed effect is less apparent at lower temperatures where the amount of methane formed is generally low. This revised version was published online in June 2006 with corrections to the Cover Date.     

Divergent and Overlapping Roles for Selected Phytochemicals in the Regulation of Pathological Cardiac Hypertrophy

Plant-based foods, like fruits, vegetables, whole grains, legumes, nuts, seeds and other foodstuffs, have been deemed as heart healthy. The chemicals within these plant-based foods, i.e., phytochemicals, are credited with protecting the heart. However, the mechanistic actions of phytochemicals, which prevent clinical endpoints, such as pathological cardiac hypertrophy, are still being elucidated. We sought to characterize the overlapping and divergent mechanisms by which 18 selected phytochemicals prevent phenylephrine- and phorbol 12-myristate 13-acetate-mediated cardiomyocyte enlargement. Of the tested 18 compounds, six attenuated PE- and PMA-mediated enlargement of neonatal rat ventricular myocytes. Cell viability assays showed that apigenin, baicalein, berberine hydrochloride, emodin, luteolin and quercetin dihydrate did not reduce cell size through cytotoxicity. Four of the six phytochemicals, apigenin, baicalein, berberine hydrochloride and emodin, robustly inhibited stress-induced hypertrophy and were analyzed further against intracellular signaling and genome-wide changes in mRNA expression. The four phytochemicals differentially regulated mitogen-activated protein kinases and protein kinase D. RNA-sequencing further showed divergence in gene regulation, while pathway analysis demonstrated overlap in the regulation of inflammatory pathways. Combined, this study provided a comprehensive analysis of cardioprotective phytochemicals. These data highlight two defining observations: (1) that these compounds predominantly target divergent gene pathways within cardiac myocytes and (2) that regulation of overlapping signaling and gene pathways may be of particular importance for the anti-hypertrophic actions of these phytochemicals. Despite these new findings, future works investigating rodent models of heart failure are still needed to understand the roles for these compounds in the heart.     

Polymicrobial Biofilm Inhibition Effects of Acetate‐Buffered Chitosan Sponge Delivery Device

Polymicrobial biofilm‐associated implant infections present a challenging clinical problem. Through modifications of lyophilized chitosan sponges, degradable drug delivery devices for antibiotic solution have been fabricated for prevention and treatment of contaminated musculoskeletal wounds. Elution of amikacin, vancomycin, or a combination of both follows a burst release pattern with vancomycin released above minimum inhibitory concentration for Staphylococcus aureus for 72 h and amikacin released above inhibitory concentrations for Pseudomonas aeruginosa for 3 h. Delivery of a vancomycin, amikacin, or a combination of both reduces biofilm formation on polytetrafluoroethylene catheters in an in vivo model of contamination. Release of dual antibiotics from sponges is more effective at preventing biofilm formation than single‐loaded chitosan sponges. Treatment of pre‐formed biofilm with high‐dose antibiotic release from chitosan sponges shows minimal reduction after 48 h. These results demonstrate infection‐preventive efficacy for antibiotic‐loaded sponges, as well as the need for modifications in the development of advanced materials to enhance treatment efficacy in removing established biofilm.

     

Flexural,impact, rheological and physical characterizations of POM reinforced by carbon nanotubes and paraffin oil

The paraffin oil dispersion technique innovated in the recent years to synthesize bulk polymer nanocomposite materials has a uniform dispersion. This research work aims to study the effect of added carbon nanotubes (CNTs) on flexural, impact and rheology behaviors of polyoxymethylene (POM) reinforced by 0–0.03 wt% of CNT using paraffin oil dispersion technique. The wettability and lamellar thickness were measured and rheological performance investigated using a parallel plate rheometer. The flexural and impact mechanical properties were also evaluated. The fracture surfaces were then examined by microscopy. The results showed that the energy to break, flexural strength and modulus increased proportionally with the addition of the amount of CNT in the matrix. For the rheology behavior, the viscosity decreased at the low percentage of CNT and then increased with increase in the percentage weight ratio of CNT in the POM matrix. It was also noted that the water contact angle rose with the increase the CNT percentages. Copyright © 2016 John Wiley & Sons, Ltd.     

In Vivo Endoscopic Tissue Identification by Rapid Evaporative Ionization Mass Spectrometry (REIMS)

Gastrointestinal cancers are a leading cause of mortality, accounting for 23 % of cancer‐related deaths worldwide. In order to improve outcomes from these cancers, novel tissue characterization methods are needed to facilitate accurate diagnosis. Rapid evaporative ionization mass spectrometry (REIMS) is a technique developed for the in vivo classification of human tissue through mass spectrometric analysis of aerosols released during electrosurgical dissection. This ionization technique was further developed by utilizing surface induced dissociation and was integrated with an endoscopic polypectomy snare to allow in vivo analysis of the gastrointestinal tract. We tested the classification performance of this novel endoscopic REIMS method in vivo. It was shown to be capable of differentiating between healthy layers of the intestinal wall, cancer, and adenomatous polyps based on the REIMS fingerprint of each tissue type in vivo.     

A Flexible Photoactive Titanium Metal–Organic Framework Based on a [TiIV3(μ3‐O)(O)2(COO)6] Cluster

The synthesis of titanium–carboxylate metal–organic frameworks (MOFs) is hampered by the high reactivity of the commonly employed alkoxide precursors. Herein, we present an innovative approach to titanium‐based MOFs by the use of titanocene dichloride to synthesize COK‐69, the first breathing Ti MOF, which is built up from trans‐1,4‐cyclohexanedicarboxylate linkers and an unprecedented [Ti^IV₃(μ₃‐O)(O)₂(COO)₆] cluster. The photoactive properties of COK‐69 were investigated in depth by proton‐coupled electron‐transfer experiments, which revealed that up to one Ti^IV center per cluster can be photoreduced to Ti^III while preserving the structural integrity of the framework. The electronic structure of COK‐69 was determined by molecular modeling, and a band gap of 3.77 eV was found.     

Total axle load effects on soil compaction

Theoretical and applied research has shown that the pressure at a point in the subsurface soil is a function of both the surface unit pressure and the extent of the area over which it is applied (total load). Thirty years ago, most of the soil compaction from vehicle traffic was in the plow layer and was removed by normal cultural practices. As equipment has increased in size and mass, machine designers have increased tire sizes to keep the soil surface unit pressure relatively constant. However, the increase in total axle loads is believed to have caused an increase in compaction at any given depth in the soil profile, resulting in significant compaction in the subsoil.Two tires of different sizes, a standard agricultural tire and a flotation tire were used to support equal loads. Soil pressures were measured at three depths in the soil profile directly beneath each of the tires. Two soils were used and each was prepared first in a uniform density profile, and then they were prepared with a simulated traffic pan (layer of higher density) at a depth of approximately 30 cm.Results showed that the presence of a traffic pan in the soil profile caused higher soil pressures above the pan and lower pressures below it than was the case for a uniform soil profile. The soil contact surface of the flotation tire was approximately 22% greater than the agricultural tire. The greater contact surface did reduce soil pressures at the soil surface, of course, but the total axle load was still the dominant factor in the 18–50 cm-depth range used in this study.     

Er∶Yb∶YCOB晶体制备及其激光二极管抽运激光特性

研究了Er∶Yb∶YCa4O(BO3)3(简称Er∶Yb∶YCOB)的多晶制备和单晶生长,用提拉法生长出光学质量优良的Er∶Yb∶YCOB单晶,测量了其吸收光谱和荧光光谱,分析了其能级和泵浦原理,并进行了以激光二极管为抽运源的激光试验,实现了Er∶Yb∶YCOB晶体的在1.55μm附近110mW的激光输出,且斜效率达18.9;.     

Multi-scale magnetic resonance measurements and validation of Discrete Element Model simulations

This short review describes the capabilities of magnetic resonance (MR) to image opaque single- and two-phase granular systems, such as rotating cylinders and gas-fluidized beds operated in different fluidization regimes. The unique capability of MR to not only image the solids’ distribution (voidage) but also the velocity of the particulate phase is clearly shown. It is demonstrated that MR can provide measurements over different length and time scales. With the MR equipment used for the studies summarized here, temporal and spatial scales range from sub-millisecond to hours and from a few hundred micrometres to a few centimetres, respectively. Besides providing crucial data required for an improved understanding of the underlying physics of granular flows, multi-scale MR measurements were also used to validate numerical simulations of granular systems. It is shown that predictions of time-averaged properties, such as voidage and velocity of the particulate phase, made using the Discrete Element Model agree very well with MR measurements.