Synthesis and evaluation of a novel antibacterial dental resin composite with quaternary ammonium salts

The novel quaternary ammonium bromide (QAB)-containing oligomers were synthesized and applied for developing an antibacterial resin composite. Compressive strength (CS) and S. mutans (an oral bacteria strain) viability were used to evaluate the mechanical strength and antibacterial activity of the formed composites. All the QAB-modified resin composites showed significant antibacterial activity and mechanical strength reduction. Increasing chain length and loading significantly enhanced the antibacterial activity but dramatically reduced the CS as well. The 30-day aging study showed that the incorporation of the QAB accelerated the degradation of the composite, suggesting that the QAB may not be well suitable for development of antibacterial dental resin composites or at least the QAB loading should be well controlled, unlike its use in dental glass-ionomer cements. The work in this study is beneficial and valuable to those who are interested in studying antibacterial dental resin composites.

FCC汽油烷基化处理对S Zorb装置进料换热器结焦的影响

针对S Zorb进料换热器的结焦问题,分析了结焦形成的原因,研究了烷基化脱硫降烯烃反应对催化裂化(FCC)汽油结焦性质的影响,并优化了FCC汽油烷基化反应的催化剂、反应温度、反应空速。结果表明:在备选的4种催化剂中,Amberlyst 35树脂对FCC汽油烷基化反应的催化性能最佳,优化的FCC汽油烷基化反应温度为90℃、质量空速为1.0 h^(-1)、压力为0.5 MPa;在优化条件下进行烷基化处理后,汽油的结焦量显著降低,但辛烷值、饱和蒸气压也有所下降。在烷基化反应后的汽油中添加C 4混合烃,可以提高汽油辛烷值和饱和蒸气压,使烷基化汽油满足质量标准要求。

DCHA AS A NEW REAGENT FOR THE ESTERIFICATION OF OBSTINATED AMINO ACIDS BY THE MERRIFIELD'S RESIN

The obstinated amino acid,Boc-Asn(or Boc-Gln),was directly anchored onto the Merrifield's resin using DCHA as the base in present reaction.The yield(71.88%)of Boc-Asn-OCH_2-resin was much better than those(0-33.5%)using Cs_2CO_3,KOH,KF.DEA and TEA as the base.which are efficient reagents for other amino acids in the same reaction.

SEPARATING SCN^- FROM DESULPHURIZATION WASTE SOLUTION OF COCKING PLANT BY D241 RESIN

SCN^- from desulphurization waste solution of cocking plant was separated by D241 anion exchange resin. When SCN＂ concentration of the waste liquid is O.116mg/ml, its dynamic exchange capability is 93.61mg/g resin. The condition of use KOH as eluted solution to elute SCN^- is KOH concentration 0.5mol/L, flow velocity 60mi/h, with 60ml eluted solution can completely elute SCN＂ which exchanged from waste solution. Vaporized the eluted solution, obtain the KSCN crystal in which the concentration of SCN^- is 53.34%, converts to KSCN is 89.2%. SCN^- crystal was separate out from Na2SO3/KOH mixed solution. The relationship between the proportion of Na2S2O3/KOH, free liquids in crystal and the saturation solution volume when crystal appear, the content of KSCN in crystal： the ratio of K2S2O3/KSCN show direct ratio with the saturation solution volume when the crystal birth, r^2=0.9964; when the ratio of K2S2O3/KSCN is between 0.15 and 0.25, the content of SCN^- in the crystals grow with K2S2O3 content increases, the content of free liquids in crystal also along with it increase; When the ratio of Na2S2O3/KOH is 0.15, the content of SCN^- is 54.56%; convert to KSCN is 76.2%. When the ratio of K2S2O3/ESCN is 0.25, the content of SCN^- is 65.28%; convert to KSCN is 91.2%. When the ratio of K2S2O3/KSCN exceeds 0.25, the content of SCN^- in the crystals and the content of free liquids in crystal reduce when the ratio of K2S2O3/KSCN increase.

猪胰脂肪酶固定化及连续流催化拆分合成(S)-2-四氢糠酸

通过筛选实验确定了树脂ESQ-3为PPL的最佳固定化载体,并确定了最佳固定化条件和固定化酶PPL@ESQ-3拆分四氢呋喃-2-甲酸丁酯(2-THFAD)的最适条件,将此固定化条件应用于连续流反应器系统并进行条件优化。实验结果表明:在该条件下,59 min即可将60 mmol 2-THFAD完全拆分得到(S)-四氢呋喃-2-甲酸丁酯((S)-2-THFAD,ee_(s)≥99%),催化效率达到3.347μmol/(min·g),催化效果远胜于间歇式反应;(S)-2-THFAD直接由Novozym 435水解得(S)-2-THFA(ee_(p)≥99%),比旋度[α]_(D)^(21)=3.542(2.0mol/L,甲醇)。PPL@ESQ-3连续流反应体系表现出了优秀的催化能力,具有适用于工业化生产(S)-2-THFA的应用潜力。

A Novel Antibacterial Dental Resin Composite

This study reports the synthesis and evaluation of a novel furanone-containing antibacterial resin composite. Compres-sive strength (CS) and S. mutans viability were used to evaluate the mechanical strength and antibacterial activity of the composites. With 5% to 30% addition of the furanone derivative, the composite showed no change in CS but a significant antibacterial activity with a 16% - 68% reduction in the S. mutans viability. Further, the antibacterial activity of the modified composite was not affected by human saliva. The aging study implies that the modified composite may have a long-lasting antibacterial function. Within the limitations of this study, it appears that this experimental resin composite may potentially be developed into a clinically attractive dental restorative due to its high mechanical strength and antibacterial function.

Properties of a New Dental Photocurable Matrix Resin with Low Shrinkage

In order to reduce the amount of volumetric shrinkage that occurs in dental composites as a result of curing,a new kind of dental matrix resin combining bisphenol-S-bis（3-meth acry late-2-hydroxy propyl）ether（BisS-GMA） with the expanding monomer unsaturated spiro orthoesters 2-methylene-1,4,6-trispiro[4,4] nonane （SOE） was prepared,with triethylene glycol dimethacrylate （TEGDMA） as diluent.CQ （camphorquinone） of 1wt% and DMAEMA （2-（dimethylamino） ethyl meth acrylate） of 2wt% were used as photoinitiation system to initiate the copolymerization of the matrix resins.The performance including volumetric shrinkage,degree of conversion and condition of the ring-opening reaction of SOE,as well as curing time and the tensile bond strength were investigated respectively by the dilatometer,Fourier transfer infrared,the universal testing machine,and so on.The ring-opening polymerization of SOE occurred.Meanwhile,the obtain copolymers were crosslinked.The matrix resin containing BisS-GMA and SOE showed a reduced amount of volumetric shrinkage at 1.52%,which is a promising strategy for obtaining a polymer with a low amount of volumetric shrinkage.Furthermore,the other properties were not compromised.

基于XF—S4240的自动声讯系统的设计

本文中的自动声讯系统的语音播放基于XF—S4240语音合成模块,采用单片机和计算机控制相结合的模式,实现中文文本到语音的转换,提高了自动声讯系统的语音质量。

Kinetics of Reaction Bisphenol-S Epoxy Resin with Methylacrylic Acid

The reaction kinetics of bisphenol-S epoxy resin with methyl-acrylic acid in the presence of quaternary ammonium salt catalyst was studied. The reaction rate constants at different temperatures were determined. The reaction is first order with respect to epoxy group, zero order with respect to methylacrylic acid and 0.71 order with respect to quaternary ammonium salt catalyst, respectively. The mechanism of this reaction was discussed.

Adherence of <i>Streptococcus mutans</i>and Adsorption of Salivary Protein to Resin Composites Containing S-PRG Fillers

The purpose of this study was to measure the amount of adsorption of various salivary proteins to a resin composite having various amounts of surface pre-reacted glass-ionomer (S-PRG) fillers, and to make a comparative study of the adherence of S. mutans to the resin composite covered by various salivary proteins. We experimentally produced resin composites (S-PRG resin) having the basic composition of Bis-GMA/TEGDMA and various amount of the S-PRG fillers ranging between 0 - 60 wt%. Each S-PRG resin block was soaked in 5 kinds of components found in salivary fluid (Mucin 1, Lactoferrin, IgA, Cystatin C, and Lysozyme), and the amount of adsorption was measured by use of a spectrophotometer. The amount of the adsorption of salivary Mucin 1 was higher than that of any other salivary component tested regardless of the percentage of the S-PRG filler. In the case of salivary Lysoxyme used for coating, the amount of its adsorption increased with an increase in the percentage of the S-PRG filler. In addition, resin blocks coated with various salivary proteins were incubated at 37℃ for 2 hours with radio-labeled S. mutans for a quantitative adherence test. Labeled bacteria that adhered to the resin blocks were collected by using an automatic sample combustion system and a liquid scintillation counter. The absorbed salivary components, especially Mucin 1 and Lysozyme, inhibited the adhesion of S. mutans to the S-PRG resin;however, these changes were generally directional rather than statistically significant.

Characterization of Unsaturated Polyester Filled with Waste Coconut Shells, Walnut Shells, and Carbon Fibers

This study aims to evaluate the erosion behavior and the hardness of hybrid composites made of varying amounts of coconut shells,walnut shells,and carbonfibers dispersed in a polyester matrix.MINITAB(L16)Taguchi experiments were used to determine the optimal combination of parameters.In particular,an erosion device con-sisting of a motor with a constantflow rate of 45 L/min,a pump with a diameter of 40 mm,a nozzle with a dia-meter of 5 mm,and a tank made of“perspex glass”55 cm long,30 cm tall,and 25 cm wide was used.The tests were conducted by varying the sample-to-nozzle distance,the pattern angle,and the sand particle size.The results have revealed that the presence of 7.5%by weight of waste coconut shell,for conditions corresponding to 90°angle,sand size 425μm,stand distance 30 cm,gives the best wear resistance(3.04×10^(-5) g/g).Thefiller content and sand particle size affect the erosive rate,with the angle playing a secondary role.The distance between the sample and the nozzle has a weaker effect on erosive wear.The hardness results show that the models(UP-5%carbonfiber-2.5-3.5-4.5-5.5-6.5-7.5 wt.%waste coconut shell)give the best values for prayer compared to the samples(UP-5 wt.%carbonfiber-2.5-3.5-4.5-5.5-6.5-7.5 wt.%waste walnut shell).

芳胺固化双酚S环氧树脂动态力学性质的研究

用高分子材料动态力学谱仪研究了芳香二胺固化双酚 S环氧树脂 (BPSER)的固化过程 ,讨论了固化时间、固化温度及固化剂的摩尔比等因素对固化物玻璃化温度的影响 ,结果表明在理论固化剂用量条件下采用变温固化过程有利于反应的控制 ,并可以有效提高固化产物的玻璃化温度。文中进一步研究了利用双酚 S环氧树脂对双酚 A环氧树脂 (BPAER) /芳胺体系的改性作用 ,表明 BPSER与 BPAER/芳胺固化体系能在较宽的比例范围内很好地相容 。

S-8大孔吸附树脂对大豆异黄酮吸附饱和度的研究

利用S 8极性大孔吸附树脂对酸解提取物稠膏中大豆异黄酮进行吸附饱和度实验,得出每17gS 8大孔树脂可吸附酸解提取物1 5164g,吸附大豆异黄酮0 337g。

茜素红S螯合树脂分离富集测定地质样品中的痕量金、铂和钯

用螯合树脂对金属进行分离富集及测定，前人已做了许多有意义的研究［１～４］．曾用含键合Ｓ双硫腙（Ｐ－Ｄ）和脱氢双硫腙（Ｐ－ＤＴ）功能团的离子交换树脂和螯合树脂分离金和铂族金属［５］，用双硫腙负载树脂分离富集Ｃｕ（Ⅱ）［６］，用磺基二硫腙负载树脂分离富集...

S-MMA-DVB三元共聚大孔吸附树脂的合成及性能

以液体石蜡、甲苯和环己酮作致孔剂 ,采用悬浮聚合合成S -MMA -DVB大孔吸附树脂 ,研究单体和致孔剂组成对孔结构的影响 ,液体石蜡和环己酮分别适宜于使树脂内部生成起扩散通道作用的大孔和发挥物理吸附作用的微孔 ,两者的比例一般控制在致孔剂总量的 2 0 %～ 30 %和 12 %～ 15 %。并测定了树脂对水中维生素C的吸附能力为 17.6mg/g ,该树脂与日本产类似树脂的化学组成、孔结构以及对维生素C的吸附能力相似或接近。

茜素红-S螯合形成树脂吸附测定地质样品的金、铂和钯

以茜素红-S(1,2-二羟基蒽醌-3-磺酸钠)为螯合剂,与大孔强碱性阴离子树脂D296-R合成茜素红-S螯合形成树脂,能够在酸性介质中使螯合形成树脂中的-OH离解出H+,变成-O-,与大体积的贵金属碘络阴离子[MeI4]2-相遇形成稳定的螯合物。在较宽的酸度范围内使Au、Pt、Pd与贱金属有效分离,并抑制NO3-对贵金属吸附的影响。与高压密闭溶矿方式相结合,Au、Pt、Pd的回收率均大于92%,检出限:Au 0.047 ng/g、Pt 0.082 ng/g、Pd 0.051 ng/g。应用于铂族元素地球化学成分分析一级标准物质中Au、Pt、Pd的测定,结果与认定值的相对误差(RE)为-7.58%~10.9%,相对标准偏差(RSD)均小于9.86%。

S-8大孔吸附树脂固定果胶酶条件的优化研究

用S-8大孔吸附树脂作为载体对果胶酶固定化,对影响果胶酶固定化效果的反应温度、时间、pH及果胶酶用量四个参数,采用四因素三水平正交试验进行了优化,结果表明,最适果胶酶固定化的条件为:温度25℃,pH5.5,吸附14h,加酶量0.5mL/g树脂,固定化果胶酶的酶活回收率为55.56%。

双酚-S环氧树脂与间苯二胺固化反应动力学

用示差扫描量热法(DSC)研究了双酚-S环氧树脂(BPSER)与间苯二胺固化反应的历程。实验结果表明,固化反应主要分为2个阶段,前期由化学动力学控制,服从自催化机理,实验数据利用Kamal方程处理得到2个速率常数k1、k2及2个反应级数m、n,k1、k1值随反应温度的升高均呈增大的趋势,总反应级数m+n在2～2 5之间;反应活化能E1、E2分别为64 18kJ/mol和48 30kJ/mol。当反应程度达到60%左右后,由于交联程度增加,分子质量迅速增大,分子间扩散较慢,进入反应的第二阶段,主要由扩散作用控制固化速率。文章还讨论了该体系固化反应的分子机理,认为其经历了三分子的过渡态。

双酚-S环氧树脂/聚氨酯互穿网络的热性能

研究了双酚-S环氧树脂/聚氨酯(BPSER/PU)互穿网络的性能。实验表明,完全固化后的双酚-S环氧树脂的玻璃化温度比双酚-A环氧树脂在相同条件下高40～50℃。通过动态力学谱仪(TBA)研究了BPSER与PU的配比和玻璃化温度之间的关系,讨论了两相间的相容性。结果表明,随着BPSER用量的增加,体系的玻璃化温度升高。m(BPSER)/m(PU)=25/75是两组分均匀混合的最佳值,形成了反应型互穿聚合物网络。另外,用热重分析仪(TGA)研究了完全固化后的互穿聚合物网络的热分解行为,结果表明,BPSER的加入可提高PU的初始热分解温度。

S-8大孔树脂对灰树花子实体多糖酶解液色素吸附的影响

目的 研究大孔树脂对灰树花子实体多糖酶解液色素的吸附过程和行为.方法 测定S-8树脂对多糖色素的吸附量,绘制吸附动力学和热力学曲线,并对结果进行模拟,确定相应的动力学和热力学模型参数.结果 拟二级动力学方程可更好地描述S-8树脂对色素的吸附过程;热力学结果表明3种双参数模型对色素在S-8大孔树脂上的吸附均有较好的适用性,适用性依次Langmuir＞ Temkin＞ Freundlich;树脂对多糖色素的吸附焓变和吸附熵变均大于零,吸附自由能小于零,平均吸附能小于20 kJ/mol.结论 S-8树脂对色素的吸附过程是自发进行的单分子层物理吸附,在293～ 313 K范围内,升温有利于吸附过程的进行.