Preparation of natural α-tocopherol from non-α-tocopherols

Non-a-tocopherols are hydroxymethylated and hydrogenated to produce α-tocopherol in one pot process by simultaneously reacting with paraformaldehyde and hydrogen in the presence of catalysts of benzenesulfonic acid and 5% Pd/C in an autoclave. Effects of various operation conditions have been studied. The preferable reaction conditions are: temperature 180 ℃ to 200 ℃, pressure 5.0 MPa, acid concentration 0.5 g/100 ml ethanol, mass ratio of Pd/C to tocopherols 7.1 g/100 g, and reaction time 5.0 h. A product with α-tocopherol content of 80% was obtained by using a raw material with a total tocopherols content of 80.54%. The conversion of non-α-tocopherols is almost 100%, and the mole yield of a-tocopherol is more than 90%.     

Preparation of glucosamine by hydrolysis of chitosan with commercial α-amylase and glucoamylase

Objective  

In order to overcome the defects of chemical hydrolysis approach to prepare glucosamine, an enzymatic hydrolysis method was developed.     

Do tuition fees affect the mobility of university applicants? Evidence from a natural experiment

Several German states recently introduced tuition fees for university education. We investigate whether these tuition fees influence the mobility of university applicants. Based on administrative data of applicants for medical schools in Germany, we estimate the effect of tuition fees on the probability of applying for a university in the home state. We find a small but significant reaction: The probability of applying for a university in the home state falls by 2 percentage points (baseline: 69%) for high-school graduates who come from a state with tuition fees. Moreover, we find that students with better high-school grades react more strongly to tuition fees. This might have important effects on the composition of students across states.     

Comparative studies on the biochemical characteristics of natural actomyosin isolated from PSE and normal pork

INTRODUCTION The meat industry is facing consumer demandsfor high, predictable, and consistent meat quality.One of the major problems is the change in exuda-tion, colour, and firmness that characterize meatquality. High incidence of pale, soft and exudative(PSE) pork cause poor technological quality, driploss, and shrinkage during storage as well as unat-tractive visual appearance for consumers. PSE porkalso causes an economic impact on the industrybecause of product dehydration d…     

Centenarians’ experience of (non-)loneliness—life lessons

This article presents the results of qualitative research carried out among Polish centenarians who have not experienced loneliness. Objectives: An attempt to find factors protecting against loneliness. A total of 17 cases were included in the research. Method: A collective case study (Stake, 2009) with in-depth interview was applied to the research carried out by the authors. The results show that activity together with personal characteristics (lifelong optimism) allows the building of positive social relationships and contribute to protection against loneliness among the oldest old. Discussion and Implications: The centenarians interviewed experienced many traumatic events in their lives and still they did not know the feeling of loneliness. The cases researched were diverse with respect to social and economic status, health condition, and family status but the common aspect was their lifetime activity and their high level of optimism. The lifelong activity of the respondents allowed them to build social relationships and establish new acquaintanceships, both intra- and intergenerationally. Promoting examples of “positive long-livers” may play preventive role and contribute to the quality of life in late old age, and as societies are ageing, the results are also important for public health.     

Progress in catalytic membrane reactors for removing sulfur from natural gas

Increasingly high requirement driven by environmental concern leads to more rigorous standards for sulfur dosage in fuel. Natural gas desulfurization is an important unit for industrial natural gas process. Catalytic membrane reactor for sulfur compounds removal is a newly emerged and integrated membrane technology. We reviewed the current progress for desulfurization of natural gas with membrane process, and predicted that the process combined with catalytic membrane reactor and microwave irradiation for desulfurization of natural gas might be an integrated and promising unit for large scale desulfurization with high efficiency.     

Re-contextualising TPACK: exploring teachers’ (non-)use of digital technologies

Technological, pedagogical and content knowledge (TPACK) has been used by hundreds of studies as a theoretical framework to explore teachers’ technology use in classroom settings. While these studies have contributed to understandings of the interplay between these different knowledge domains and the differences between pre- and in-service teachers’ knowledge, little work has been done to examine the influence of teachers’ socially mediated workplace settings on TPACK enactment. This article begins to address this issue reporting findings from an eight-month case study involving 10 teachers in an Australian secondary school. Results reported in this article indicate that TPACK enactment is influenced by processes of identity development and practice. These findings challenge the established position of knowledge as an epistemological possession inherent in the TPACK framework rather than also considering knowing as an epistemology of practice. Implications for in-service teachers and school authorities are discussed and suggestions for future research considered.     

Porous structures of natural materials and bionic design

INTRODUCTION After long period natural selections and evolu-tions,natural porous structures always integrate various functions and have many characters superior to artificial porous structures,which are mainly composed of composite and complex structures.Natural porous structures can prevent seeds,eggs,etc.from invasion of water or cracks due to collision,exchange matters with the environment during the metabolism process,and use less material to form larger space under equivalent conditio…     

Preparation of a novel biodegradable β-cyclodextrin-containing polymer

A novel cyclodextrin-containing polymer was prepared by graftingβ-cyclodextrin onto the backbone of poly(D,L-lactic acid)(PLA).First,mono(6-(2-aminoethyl)amino-6-deoxy)-β-cyclodextrin(β-CD-6-en)was prepared by sulfonylation and amination ofβ-cyclodextrin and modified poly(D,L-lactic acid)(MPLA)was prepared by free radical polymerization of maleic anhydride and PLA.Then,grafting ofβ-cyclodextrin derivative to MPLA backbone was carried out by N-acylation reaction of MPLA andβ-CD-6-en in dimethyl formamide.The...     

Preparation of Vitamin E Intermediate from an Inexpensive Substrate by Selective Oxidation of Pseudocumene in HCOOH–H_2O_2 System

In this paper, 2,3,5-trimethyl-1,4-benzoquinone(TMBQ) was synthesized through the direct oxidation of1,2,4-trimethylbenzene(pseudocumene, TMB) in the HCOOH–H_2O_2 system. The influence ofthree active species was studied, including performic acid(PFA) generated in formic acid, peracetic acid(PAA) generated in acetic acid, and trifluoroperacetic(TFPA) acid generated in trifluoroacetic acid. The effects ofsulfuric acid and sodium formate addition were investigated, the overoxidation ofTMB was discussed, and the main reason for the decreasing selectivity was revealed. The oxidation ofTMB can be controlled and improved through adjusting the reaction temperature, mole ratio ofoxidant to substrate, and reactant concentration. The TMBQ yield of28% was achieved with a TMB concentration of0.2 mol/L, H_2O_2/TMB mole ratio of6:1, and reaction temperature 37 °C. The selectivity of72% was obtained with a TMB concentration of0.2 mol/L, H_2O_2/TMB mole ratio of5:1, and reaction temperature of27 °C. The reaction mechanisms were proposed and discussed based on the gas chromatography–flame ionization detection(GC–FID) and gas chromatography–mass spectrometer(GC–MS) results.     

For want of a better word: unlocking threshold concepts in natural sciences with a key from the humanities?

The process of identifying threshold concepts invites experts to reflect on their discipline in a new way with the ultimate goal of improving learning and teaching. During a workshop to identify threshold concepts in biochemistry, we asked a group of natural scientists to explore ‘signification,’ a threshold concept from the humanities, as a mechanism to push them out of their comfort zones and recall how it feels to experience learning from a student’s perspective. In addition to accomplishing this goal, we subsequently realized that signification could also help us uncover and remedy ways in which use of scientific terminology impedes learning in biochemistry. Using the results of a survey of university teachers that aimed at refining a list of possible threshold concepts, we present three scenarios to illustrate the challenges that teachers and students encounter when attempting to cement a label (the signifier) and a concept (the signified) into a coherent sign. Based on these findings, we propose that teachers can better explore threshold concepts if they carefully consider the role terminology plays in learning and teaching. Thus we describe the ‘terminological canyon’ through which university teachers must journey in order to produce effective learning and teaching activities related to the threshold concepts. While the work described here pertains to biochemistry, we believe the process and findings can be generalized to a broad range of disciplines.     

Die of与Die from

问:The boy was dying fast from a swordthrust.(那男孩因受剑伤快要死了。)(S.B.Z,P35)在此句中的介词from可不可以换成of? 答:一般说,因疾病、饥饿、年老、哀恸、失望等而死,用die of。例如:     

A Practical and Efficient Procedure for Preparation of Oximes by Use of InCl3

InCl3 catalyzes the reaction of hydroxylamine hydrochloride with a number of aldehydes and ketones under solvent free condition to afford an efficient method for the synthesis of oximes.     

Why do good performing students highly rate their instructors? Evidence from a natural experiment

This article analyzes the behavior of students in a college classroom with regard to their evaluation of teacher performance. As some students are randomly able to see their grades prior to the evaluation, the “natural” experiment provides a unique opportunity for testing the hypothesis as to whether there exists a possibility of a hedonic (implicit) exchange between the students’ grades and teaching evaluations. Students with good grades tend to highly rate the teaching quality of their instructors, in comparison with those who receive relatively poor grades. This study finds that students with better grades than their expected grades provide a psychological “gift” to their teachers by giving a higher teacher evaluation, whereas it is the opposite with those students receiving lower grades than their expectation. These empirical results demonstrate that a previous interpretation on the effect of student grades in an incumbent course with regard to the teaching quality may have to be somewhat discounted.     

Immunomodulatory function of orally administered thymosin α1

INTRODUCTION The thymus is a vital immune organ and plays a very important role in the development and mainte- nance of the lymph system. The extract of animal thymus has been used in clinical practice as an ad- junct treatment in patients with carcinoma, viral in- fection and immunodeficiency, but the extract con- taining miscellaneous animal proteins may easily lead to allergy in patients. Thymosin α1 (Tα1) is the most potent ingredient in thymosin and the biological ac- tivity of pur…     

Improved Synthesis of Nefazodone from Phenol

A route for the synthesis of nefazodone is reported. Nefazodone was obtained with an overall yield of 37. 2% from phenol. The key steps involve the improved synthesis of 5-ethyl-4-(2-phenoxyethyl)-1, 2, 4-triazol-3(2H)-one, a key intermediate in the synthesis of nefazodone. The phenol was etherified with 1, 2-dichloroethane (75%), followed by iodination-amination with Nal and CH_3OH-NH_3(85.7%), acylation with ethyl chloroformate (95.7%) and cyclization with propionyl hy-drazine (83.6%).     

Preparation of Urea Nitrogen Adsorbent of Complex Type and Adsorption Capacity of Urea Nitrogen onto the Adsorbent

The urea nitrogen adsorbent of complex type, which consists of chitosan coated dialdehyde cellulose （CDAC） and immobilized urease in gelatin membrane （IE）, was prepared. The cellulose, the dialdehyde cellulose （DAC） and the CDAC were characterized by scanning electronic microscope. The results indicate that the cellulose C2-C3 bond was broken under the oxidation of periodate and it was oxidated to DAC. The DAC was coated with chitosan and the CDAC was obtained. The adsorption of urea nitrogen onto the adsorbent in Na2HPO4-NaH2PO4 buffer solution was studied in batch system. The effects of the experiment parameters, including degree of oxidation of CDAC, initial urea nitrogen concentration, pH and temperature, on the adsorption capacity of urea nitrogen onto the adsorbent at CDAC/IE weight ratio 10：1 were investigated. The results indicate that these parameters affected significantly the adsorption capacity. The adsorption capacity of urea nitrogen onto the adsorbent was 36.7 mg/g at the degree of oxidation of CDAC 88%, initial urea nitrogen concentration 600 mg/L, pH 7.4 and temperature 37℃.     

Preparation and Properties of TiN_x-SiO_2 Antireflective Coatings with Print Process

1　Introduction　TiNxcoatingspossessmanygoodproperties,suchashighhardness,highmeltingpoint,abrasionresistantanderosionresistant[1,2].Ithasbeenwidelyusedasabrasionanderosionresistantlayerinthefieldsofelectronicengineering,machineryandsoon.Itisalsousedasadornmentmaterialduetoitsgoldcolor.Inthepresentpaper,TiNxisanalyzedashighindexmaterialinplaceofTiO2fortheantireflective(AR)coatings.　Forthesolgelprocess,dipandspinprocessareoftenusedtopreparecoatings.Inthispaper,printprocess,traditionallyuse…