A Review on Structure–Activity Relationship of Dietary Polyphenols Inhibiting α-Amylase

The inhibitory effects of dietary polyphenols against α-amylase have attracted great interest among researchers. The aim of this review is to give an overview of the research reports on the structure–activity relationship of polyphenols inhibiting α-amylase. The molecular structures that influence the inhibition are the following: (1) The hydroxylation of flavonoids improved the inhibitory effect on α-amylase; (2) Presence of an unsaturated 2,3-bond in conjugation with a 4-carbonyl group has been associated with stronger inhibition; (3) The glycosylation of flavonoids decreased the inhibitory effect on α-amylase depending on the conjugation site and the class of sugar moiety; (4) The methylation and methoxylation of flavonoids obviously weakened the inhibitory effect; (5) The galloylated catechins have higher inhibition than nongalloylated catechins; the catechol-type catechins were stronger than the pyrogallol-type catechins; the inhibition activities of the catechins with 2,3-trans structure were higher than those of the catechins with 2,3-cis structure; (6) Cyanidin-3-glucoside showed higher inhibition against than cyanidin and cyanidin-3-galactoside and cyanidin-3,5-diglucoside had no inhibitory activity; (7) Ellagitannins with β-galloyl groups at glucose C-1 positions have higher inhibitory effect than the α-galloyl and nongalloyl compounds and the molecular weight of ellagitannins is not an important element.     

(α+β)Dual Phase CuZnAl Shape Memory Alloy

The effect of α phase on CuZnAl shape memo-ry alloy(SMA)has been systematically studied byelectrical resistance method,quantitative measure-ment of micrography and transmission electronmicroscopy(TEM).It is found that,by controllingthe amount of α phase in(α+β)-CuZnAl alloy,phase transformation temperatures can be adjustedprecisely in a wide range,while the good shapememory effect of CuZnAl is kept.In a word,quenching from(α+β)dual phase region is a rea-sonable method of adjusting phase transformationtemperatures for CuZnAl alloy.     

织物用聚醚改性氨基硅油柔软剂的合成

以α,ω-二羟基聚二甲基硅氧烷(WS-62M)、N-β-氨乙基-γ-氨丙基三甲氧基硅烷(SG-Si900)和聚氧乙烯甲基缩水甘油醚(GPOME)为原料,经酯交换和开环反应合成了可用于织物柔软整理的聚醚改性氨基硅油,用它整理后的织物具有柔软的手感、较好的白度和吸水性。氨基硅油的最佳合成条件:n(WS-62M)/n(SG-Si900)=1.33:1,ω(三乙胺)=1.53%,反应温度120℃,反应时间10 h,在0.01 MPa 条件下抽真空0.5～1h。聚醚改性氨基硅油的最佳合成条件:n(GPOME)/n(氨基硅油)=7.2:1,m(异丙醇)/m(GPOME+氨基硅油)=1:1,反应温度80℃,反应时间5 h。     

Changes in glycoalkaloids content of potatoes destined for consumption

The purpose of the present study was to determine glycoalkaloid content of early potato cultivars, grown with the use of various N rates and subsequent changes resulting from preparation of potatoes for consumption. The material taken for the study consisted of three very early potato cultivars from the growing seasons of 2003–2005: Bard, Lord and Denar, grown in the experimental plots belonging to Wroclaw University of Environmental and Life Sciences.     

The electroreduction of alkyl iodides and polyiodides: The kinetic model of EC(C)E and ECE-EC(C)E mechanisms with included transfer coefficient variability

The cyclic voltammetry electroreduction of seven alkyl iodides was investigated in 0.3 M TBAP/DMF on glassy carbon electrode. The influence of carbon chain length and the number of iodine atoms in the molecule was examined. The two-electron reductive cleavage with iodine elimination was numerically resolved into one-electron consecutive steps. The mechanism of the process was discussed applying the mathematical EC(C)E and ECE-EC(C)E kinetic models with included transfer coefficient variability for one stage electroreduction of RI and two stage electroreduction of RI₂, respectively. For electroreduction of diiodomethane the discrimination of elementary alpha parameter between two reduction stages was determined.     

Inhibition of α-amylase activity by condensed tannins

The ability of grape seed procyanidins to inhibit α-amylase activity was studied using a colorimetric method. This ability was found to be related with the average degree of polymerisation of the tested procyanidins. These interactions were further evaluated by fluorescence quenching, dynamic light scattering (DLS) and nephelometry, in order to understand the mechanisms by which they occur. A relationship between aggregate formation and enzymatic inhibition was observed. The interaction between procyanidins and enzyme involves a specific interaction as inferred from the calculated apparent bimolecular quenching constant in the fluorescence assays. Further experiments involved the determination of the effect of carbohydrates on the enzymatic inhibition observed. It was shown that pectin and arabic gum inhibited the formation of insoluble aggregates but were unable to restore fluorescence and activity to the enzyme. This suggests that these carbohydrates resulted in a decrease in turbidity due to the formation of a ternary complex with protein/polyphenol.     

TiAlCNO过渡层组织结构及其对Al_2O_3涂层结构性能的影响

MT-TiCN/α-Al2O3多层涂层是高性能硬质合金CVD涂层刀具的典型涂层结构,得到广泛的应用和研究。TiAlCNO过渡层可以改善MT-TiCN/α-Al2O3涂层之间的结合性能。通过改变沉积气氛氧化势,制备了不同成分的TiAlCNO过渡层和MT-TiCN/TiAlCNO/Al2O3多层涂层,研究了沉积气氛氧化势对TiAlCNO过渡层和MT-TiCN/TiAlCNO/Al2O3多层涂层的结构性能的影响。结果表明:当沉积气氛中有CO2时,沉积TiAlCNO过渡层中可以检测到α-Al2O3相;随沉积气氛中CO2的增加,TiAlCNO过渡层中的Al含量增加,沉积在TiAlCNO过渡层表面的α-Al2O3涂层织构降低,结合强度增加。当TiAlCNO过渡层沉积气氛中CO2流量由0 L/min增加到1 L/min时,Al2O3涂层的织构系数TC(113)由0.64增加到1.33,而TC(012)由2.07降到1.5,TC(110)由1.99降到0.97;划痕临界载荷LC由36.5 N增加到51.7 N。     

Ti-50Ni钎焊TZM与ZrCp-W接头界面组织及性能

采用Ti-50Ni(at%)钎料实现了TZM合金与ZrC_p-W复合材料的真空钎焊连接,通过SEM、EDS、XRD等方法分析了接头界面的微观组织结构,研究了钎焊温度对TZM/Ti-50Ni/ZrC_p-W接头界面组织及性能的影响。结果表明:钎焊接头的典型界面结构为TZM/Ti-Mo+TiNi_3+Mo-Ti-W/Ti Ni+TiNi_3+W(s,s)+(Ti,Zr)C/ZrC_p-W。随着钎焊温度的升高,Ti-Mo固溶体层宽度逐渐增大,线状条纹增多、增宽,组织逐渐粗大,晶界变圆滑;接头的抗剪强度随钎焊温度升高先升高后降低,当钎焊温度为1340℃,保温10 min时,接头获得最大抗剪强度为146 MPa。     

3,5-二氯-2-戊酮的合成研究

以α-氯-α-乙酰基-γ-丁内酯、固体光气为原料,N,N-二甲基哌啶盐酸盐为催化剂合成了3,5-二氯-2-戊酮。考察了催化剂种类、氮气通入速率、物料配比、滴加时间、滴加温度等因素对反应的影响。优化条件下,3,5-二氯-2-戊酮的含量94.0%,收率81.5%(以α-氯-α-乙酰基-γ-丁内酯计)。     

球团烟气脱硫石膏制备α型高强石膏的研究

以球团烟气脱硫石膏作主要原料,添加剂使用丁二酸和十二烷基苯磺酸钠,并使用加压盐溶液的方法研制出抗压强度能达到45 MPa以上的α型高强石膏。分析了球团烟气脱硫石膏的物理及化学性能,转晶剂的含量与种类以及工艺条件对制品性能的影响,揭示了α型高强石膏的形成机理。结果表明：在使用加压盐溶液方法的前提下,温度、转晶剂用量、盐溶液浓度都会对制品的强度产生影响。