Chiral phospha[n]ferrocenophanes: New Metallopolymers through Ring-Opening Polymerizations

Chiral polymers have many important applications, including separation of racemic compounds and catalysts in asymmetric syntheses. There are many examples of chiral natural polymers, such as proteins, DNA, or cellulose. However, synthetic chiral polymers are rather rare. On the other hand, the incorporation of metal centers into synthetic polymer chains allows the preparation of new functional materials with unique properties that complement those of organic macromolecular materials. Recently, Müller’s group developed a synthetic route to strained ferrocenophanes (FCPs) with planar chirality, and via ring-opening polymerization (ROP), new chiral metallopolymers could be obtained. In this thesis, the syntheses of new chiral phospha[n]FCPs are described, as well as their behaviors towards ROP. New enantiomerically pure phospha[n]FCPs (n = 1, 2) equipped with two iPr groups in α positions were prepared. The molecular structure of diphospha[2]FCP (Sp,Sp,R,R)-90CH2SiMe3 was determined by single-crystal X-ray analysis showing a tilt angle α = 12.2°. Furthermore, the new chiral (Sp,Sp,S,S)-1,1′-(NiPr2)2fciPr 88NiPr2 (fciPr = (Sp,Sp)-[(Me2CH)–(C5H3)]2Fe) was also selectively synthesized and isolated, which gave suitable crystals for single-crystal X-ray analysis. Attempted anionic ROPs were performed on phospha[1]FCPs, however, no polymeric materials could be obtained from these reactions. Detailed studies on phospha[1]FCPs with different substituents on phosphorus atom were carried out, showing that the initiation step in the anionic ROP worked, but the ring-propagation did not occur. In attempts to perform this type of reaction, one of the phospha[1]FCP (Sp,Sp)-20Ph showed the ability to be cleanly ring-opened when using 1 equiv of nBuLi and afforded a 3 to 1 diastereomeric mixture of products. This mixture was sulfurized and a single isomer, (Sp,R)-95S, was isolated and characterized by single-crystal X-ray analysis. In addition, based on the clean anionic ring-opening reaction of the compound (Sp,Sp)-20Ph with 1 equiv of nBuLi, the new chiral ferrocene-based phosphine ligand (Sp,S)-99 was successfully synthesized. In order to measure the amount of strain in [1]FCPs, differential scanning calorimetry (DSC) studies were performed on a series of phospha[1]FCPs having different substituent groups. On the other hand, thermal ROP of compound (Sp,Sp)-21Ph afforded both linear polymer 102n and cyclic oligomers 103. Gel permeation chromatography (GPC) of the sulfurized polymer resulted in a molecular weight of 19 kDa (Mw) and a dispersity of 1.3 (Ð). Mass spectroscopic analysis of the oligomers showed the presence of cyclic species from dimers to hexamers. After sulfurization, preparative thin layer chromatography (PTLC) led to the separation of five isomeric dimers. Structural characterization of one of the dimers (syn-C2-103S-3) by single-crystal X-ray analysis revealed that Fe–Cp bond broke during the thermal ROP process

EFL LEARNERS’ PERCEPTION ABOUT PREFIXES AND SUFFIXES IN ENGLISH MORPHOLOGY

Affix knowledge is crucial for enhancing word knowledge in English morphology. Understanding the meaning of affixes not only helps develop knowledge of words but also helps master grammar. This study uses a questionnaire to assess the knowledge of prefixes and affixes and determine students' awareness of affixes. The 21 students participating in the study were all students of the 45th course, majoring in high-quality English. A survey about affix identification was given to participants, to determine their definitions and perceptions of prefixes and suffixes in English morphology. The results show that students can identify a common affix but have difficulty with strange affixes. However, to understand affixes well and be good at morphological awareness, students need to cultivate and understand the theoretical aspects of this knowledge. Another inference of these findings is favorable in the discussion part.  Article visualizations

Treatment of landfill leachate through struvite precipitation and nitrogen removal bacteria and poly-phosphate bacteria (in-pots experiment)

Abstract— Landfill leacheate is a type of wastewater which contains large amounts of nitrogen and phosphorus, therefore it needed to be treated before releasing to directly to the environment. The combination between struvite precipitation and nitrogen removal and poly-P bacteria into wastewater for landfill leachate treatment has been found to be a cost-effective practive, a viable technology in terms of environmental protection and sustainability, especially in the developing-countries. For optimum struvite crystallization from landfill leachate, the Mg:PO4 molar ratio as (1.2:1) was used, the pH of reaction was adjusted to 9 and the sample was stirred continously during 40 minutes. The supernatant sample was then added 1% nitrogen removal bacteria (Pseudomonas stutzeri D3b strain) and 1% poly-P bacteria (Kurthia sp. TGT1013L strain), 5 g glucose/L and aeration 12/24h during 3 days, ammonium concentration reduced significantly from 1076 mg/L to 1.5 mg/L and orthophosphate concentration decreased noticeably from 24.91 mg/L to 7.6 mg/L

Operator entanglement of two-qubit joint unitary operations revisited: Schmidt number approach

Operator entanglement of two-qubit joint unitary operations is revisited. Schmidt number is an important attribute of a two-qubit unitary operation, and may have connection with the entanglement measure of the unitary operator. We found the entanglement measure of two-qubit unitary operators is classified by the Schmidt number of the unitary operators. The exact relation between the operator entanglement and the parameters of the unitary operator is clarified too.Comment: To appear in the Brazilian Journal of Physic

Synthesis of antiulcer drug esomeprazole.

Esomeprazole (Nexium®), the (S)-isomer of Omeprazole, is the first proton-pump inhibitor developed as a single isomer for the treatment of acid-related diseases. It is used for the treatment of peptic ulcers, gastroesophagal reflux disease, and erosive esophagitis. Herein, we report our synthetic study of esomeprazole sodium salt from the starting    2-mercapto-5-methoxybenzimidazole and 2-(chloromethyl)-4-methoxy-3,5-dimethylpyridine hydrochloride reagents. The Esomeprazole sodium salt was obtained from enantioselectivesulfoxidation reaction in moderate yield with high enantioselectivity

Dissecting the effect of family business exposure on entrepreneurial implementation intention

Purpose Scholars have typically examined family business exposure as an aggregate variable. However, it is probable that this trend oversimplifies the complexity of family exposure and its nuanced influence on entrepreneurial behaviour. Thus, to extend the theoretical boundary, this inquiry investigates distinct dimensions of family exposure in Nigeria while drawing on the theory of planned behaviour. Methodology Data were collected from five public universities in Nigeria. A sample of 1,314 respondents was analysed using a partial least squares structural equation modelling approach to determine the influence of alternate family business exposures. Findings The results show that entrepreneurial exposure in the forms of parent, family member and work involvement have salient and distinctive influences on implementation intention to the extent that entrepreneurial self-efficacy, attitudes and subjective norms are uniquely impacted. Originality This study offers novel insights on the predictors of entrepreneurial implementation intention through the distinctive effects of (1) family member exposure, (2) parent exposure and (3) work involvement exposure among students in the family firm context

Assessment of intrahepatic blood flow by Doppler ultrasonography: Relationship between the hepatic vein, portal vein, hepatic artery and portal pressure measured intraoperatively in patients with portal hypertension

<p>Abstract</p> <p>Background</p> <p>Abnormality of hepatic vein (HV) waveforms evaluated by Doppler ultrasonography has been widely studied in patients with chronic liver disease. We investigated the correlation between changes in HV waveforms and portal vein velocity (PVVel), the hepatic artery pulsatility index (HAPI), and also the extent of abnormal Doppler HV waveforms expressed as damping index (DI), severity of portal hypertension expressed as Child-Pugh scores and portal pressure (PP) measured directly from patients with portal hypertension (PHT) to evaluate the indicative value of abnormal HV waveforms and discuss the cause of abnormal HV waveform.</p> <p>Methods</p> <p>Sixty patients who had been diagnosed with PHT and accepted surgical therapy of portosystemic shunts were investigated. PP was measured intraoperatively. Thirty healthy volunteers with no history of chronic liver disease were enrolled as the control group. HV waveforms were categorized as triphasic, biphasic or monophasic. DI was compared as the quantitative indicator of abnormal HV waveforms. Another two Doppler parameters, PVVel and HAPI were also measured. These Doppler features were compared with PP, Child-Pugh scores and histological changes assessed by liver biopsy.</p> <p>Results</p> <p>In the patient group, the Doppler flow waveforms in the middle HV were triphasic in 31.6%, biphasic in 46.7%, and monophasic in 21.6% of subjects. These figures were 86.7%, 10.0%, and 3.3%, respectively, in healthy subjects. With the flattening of HV waveforms, the HAPI increased significantly (<it>r </it>= 00.438, <it>p </it>< 0.0001), whereas PVVel decreased significantly (<it>r </it>= -0.44, <it>p <</it>0.0001). Blood flow parameters, HAPI, PVVel and HV-waveform changes showed no significant correlations with Child-Pugh scores. The latter showed a significant correlation with PP (<it>r </it>= 0.589, <it>p </it>= 0.044). Changes of HV waveform and DI significantly correlated with PP (<it>r </it>= 0.579, <it>r </it>= 0.473, <it>p <</it>0.0001), and significant correlation between DI and Child-Pugh scores was observed (<it>r </it>= 0.411, <it>p = </it>0.001). PP was significantly different with respect to nodule size (<it>p </it>< 0.05), but HV-waveform changes were not significantly correlated with pathological changes.</p> <p>Conclusion</p> <p>In patients with PHT, a monophasic HV waveform indicates higher portal pressure. Furthermore, quantitative indicator DI can reflect both higher portal pressure and more severe liver dysfunction. Flattening of HV waveforms accompanied by an increase in the HAPI and decrease in PVVel support the hypothesis that histological changes reducing HV compliance be the cause of abnormality of Doppler HV waveforms from the hemodynamic angle.</p

Tin Dioxide Nanocrystals as an Effective Sensitizer for Erbium Ions in Er-Doped SnO 2

Undoped SnO2 and erbium-doped SnO2 powders were successfully prepared by precipitation method. The effect of the heat treatment and doping contents on the structure of tin oxide and optical properties was also studied. The XRD data and Raman spectra indicate that the SnO2 crystals have formed after being heat-treated at 400°C and the average size of grains is about 8 nm for doping content of 1 mol%. An increase of doping concentration has controlled the growth of nanocrystals. The principle of the visible and infrared emissions of SnO2 and SnO2:Er is also discussed. All photoluminescence study shows that the Er3+ ions can be located in SnO2 nanocrystals and that there is energy transfer from defect levels of SnO2 nanoparticles to neighboring Er3+ ions of crystals

Intact satellite cells lead to remarkable protection against Smn gene defect in differentiated skeletal muscle

Deletion of murine Smn exon 7, the most frequent mutation found in spinal muscular atrophy, has been directed to either both satellite cells, the muscle progenitor cells and fused myotubes, or fused myotubes only. When satellite cells were mutated, mutant mice develop severe myopathic process, progressive motor paralysis, and early death at 1 mo of age (severe mutant). Impaired muscle regeneration of severe mutants correlated with defect of myogenic precursor cells both in vitro and in vivo. In contrast, when satellite cells remained intact, mutant mice develop similar myopathic process but exhibit mild phenotype with median survival of 8 mo and motor performance similar to that of controls (mild mutant). High proportion of regenerating myofibers expressing SMN was observed in mild mutants compensating for progressive loss of mature myofibers within the first 6 mo of age. Then, in spite of normal contractile properties of myofibers, mild mutants develop reduction of muscle force and mass. Progressive decline of muscle regeneration process was no more able to counterbalance muscle degeneration leading to dramatic loss of myofibers. These data indicate that intact satellite cells remarkably improve the survival and motor performance of mutant mice suffering from chronic myopathy, and suggest a limited potential of satellite cells to regenerate skeletal muscle

Improvement in photovoltaic performance of rutile-phased TiO2 nanorod/nanoflower-based dye-sensitized solar cell

An improved dye-sensitized solar cell (DSC) of rutile-phased titanium dioxide (TiO2) electrode with increased power conversion efficiency was successfully fabricated. Rutile-phased TiO2 nanorods and nanoflowers were grown directly on fluorine-doped SnO2 (FTO) by simple aqueous chemical growth technique using one-step hydrothermal process. The solution was prepared by mixing hydrochloric acid, deionized water, and titanium butoxide used as precursor. In the preparation of DSC, both TiO2 nanorods and nanoflowers, platinum (Pt), ruthenium dye N719, and DPMII electrolyte were used as photoelectrode, counter electrode, dye solution, and liquid electrolyte, respectively. The prepared rutile-phased TiO2 nanorods and nanoflowers samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The DSCs were fabricated based on the rutile-phased titanium dioxide nanorod and nanoflower photoelectrodes. For their energy conversion efficiency, I-V characteristics and electrochemical impedance spectroscopy were studied. We also investigated the effect of cetyltrimethylammonium bromide (CTAB) reaction times 2, 5, and 10 h in the preparation of rutile-phased TiO2 nanoflowers for DSC. CTAB is one of the capping agents that cover the refine surface of nanoparticles and prevent them from coagulation or aggregation. In our final result, the combination of rutile-phased TiO2 nanorod- and nanoflower-based DSCs showed best efficiency at approximately 3.11% due to its good electron transport of TiO2 nanorods and increased surface area by the TiO2 nanoflowers that had increased dye absorption