水杨酸-壳聚糖/聚乙烯醇共混膜的制备及性能

采用溶液共混法制备了一系列不同水杨酸含量的水杨酸-壳聚糖/聚乙烯(SA-CS/PVA)共混膜,用红外光谱(FT-IR)、X射线衍射(XRD)、扫描电镜(SEM)和原子力显微镜(AFM)等对共混膜进行表征,并对其透气性和力学性能进行测试。结果表明,当水杨酸含量≤30%时,SA与CS、PVA具有良好的相容性;水杨酸的加入使共混膜表面的粗糙度增加;共混膜的透气性、拉伸强度和断裂伸长率随水杨酸含量的增加而减小。     

粉煤灰抑制ASR的机制

本文研究粉煤灰对ASR的抑制作用.测定了不同粉煤灰掺量砂浆棒膨胀率、水泥石中Ca(OH)2含量以及主要水化产物C-S-H凝胶的微观结构和化学组成,并对粉煤灰抑制ASR的机制进行探讨.结果表明:随粉煤灰掺量增加,其对ASR具有显著的抑制效果.水泥石中Ca(OH)2含量不断减少,二次反应生成大量低n(Ca)/n(Si)的C-S-H凝胶.随n(Ca)/n(Si)降低,C-S-H凝胶中固溶了大量的Al,凝胶的固碱能力增强,从而使混凝土孔溶液中的有效碱大大减少,减轻了ASR程度.凝胶的固碱能力增强除了因n(Ca)/n(Si)降低,使C-S-H凝胶的固碱能力增强之外.还可能因为Al3 代替Si4 形成[AlO4]5-四面体,由于Al3 比Si4 少一价,引起电价不平衡,系统带负电,因此碱离子更容易进入C-S-H凝胶中,减少了碱与活性集料反应的机会.     

稀土掺杂碱锌硼硅酸盐玻璃的制备及其性能的研究

稀土玻璃由于具有高折射、低色散的特点，在红外光学玻璃以及有色光学玻璃等领域有着特殊的应用。主要研究了稀土钐掺杂碱硼硅酸盐玻璃的形成能力、玻璃的析晶产物以及稀土含量对玻璃吸收光谱的影响。实验结果表明，稀土氧化钐对碱硼硅酸盐玻璃具有较强的影响，随着稀土含量的增加玻璃的形成区域迅速缩小，玻璃的析晶能力以及对可见区和近红外区的光吸收逐渐增强。玻璃的析晶产物主要是六方(H)与三斜(T)晶型的硼酸钐晶体。     

低温对西番莲采后贮藏品质的影响

目的 探究低温贮藏对西番莲采后贮藏保鲜效果的影响.方法 以西番莲为实验材料,检测西番莲果实的皱缩指数、质量损失率、好果率、色差、相对电导率、丙二醛含量、可溶性固形物含量、可滴定酸含量、Vc含量、可溶性蛋白含量和SOD酶活性等生理生化指标的变化,研究低温贮藏(3,8,13℃)对西番莲采后生理和营养品质的影响.结果 在8℃下贮藏的保鲜效果优于3,13℃组,其可以有效地维持果实的色泽和好果率,抑制质量损失率、皱缩指数、相对电导率和丙二醛含量的增加,保持较好的可溶性固形物、可滴定酸、Vc、可溶性蛋白含量,提高果实的SOD酶活性,较好地保持了果实的贮藏品质.结论 西番莲采后在8℃下贮藏对果实贮藏保鲜的效果最佳,可以有效地延缓果实衰老.     

喜树碱生物合成途径及其代谢调控的研究进展

喜树碱类抗癌药物的大量生产是目前生物技术研究的热点之一。本文通过对喜树碱的生物合成途径和关键酶及其基因的表达调控等方面的研宽进展进行综述,指出阐明喜树碱的生物合成途径及其代谢调控机制,实施次生代谢工程,是应用生物技求方法大量生产喜树碱及其衍生物的根本途径。     

外源甜菜碱与褪黑素复合处理对龙眼果实贮藏性能的影响

目的 研究不同浓度甜菜碱与褪黑素复合处理对采后龙眼果实冷藏的保鲜效果,以期为龙眼贮藏保鲜新技术提供理论参考。方法 以‘储良’龙眼为实验材料,分别采用0、5、10、15 mmol/L的甜菜碱与300 mmol/L的褪黑素复配制成保鲜剂处理果实。在温度为4 ℃、相对湿度为85%条件下贮藏,研究其冷藏期间质量损失率及可溶性固形物(TSS)、可滴定酸(TA)、抗坏血酸(VC)、丙二醛(MDA)、游离脯氨酸含量和过氧化氢酶(CAT)、过氧化物酶(POD)、超氧化物歧化酶(SOD)活性的变化。结果 与300 mmol/L褪黑素对照组相比,复合保鲜剂能有效减少龙眼果实水分、TSS、TA、VC和游离脯氨酸含量的损失,使龙眼果肉保持较高的SOD、CAT活性(P<0.05),而POD活性和MDA含量维持在较低水平。结论 300 mmol/L褪黑素+10 mmol/L甜菜碱处理对龙眼的冷藏保鲜效果最佳。     

采后茉莉酸甲酯处理对蓝莓果实抗病性的影响

目的研究简易自发气调包装及不同浓度茉莉酸甲酯(MeJA)处理对采后蓝莓果实抗性的影响。方法分别用浓度为0.15,0.3 mmol/L的MeJA以及去离子水浸泡蓝莓果实,时间均为10 min,将取出的果实晾干、预冷,装入厚度为0.0294 mm的聚乙烯简易自发气调包装袋中,于1℃下贮藏,以15 d为1周期对蓝莓呼吸代谢及抗性相关指标进行测定,即袋内CO_2和O_2浓度,以及果实亮度、感官评定、呼吸速率、硬度、腐烂率、pH值、可溶性固形物(SSC)含量、苯丙氨酸解氨酶(PAL)活性、多酚氧化酶(PPO)活性、过氧化物酶(POD)活性、木质素含量等。结果 MeJA处理可有效保持包装袋内适宜的CO_2和O_2浓度,并可减缓果实硬度、亮度的下降,抑制果实呼吸速率、pH值及SSC含量的上升,提高果实木质素含量,降低果实腐烂率,显著提高PAL,PPO,POD等抗性相关酶活性(P0.05)。结论简易自发气调包装结合MeJA处理可通过抑制呼吸代谢、提高苯丙烷代谢及抗氧化酶活性,从而诱导采后蓝莓果实抗性的产生,保持采后果实品质。在2种浓度的MeJA处理中,浓度为0.15 mmol/L的处理效果最好。     

失水程度对板栗贮藏中部分生理指标的影响

为了解不同失水程度对板栗保鲜贮藏的影响机制,以镇安红栗为试验材料,研究了不同失水程度的板栗在贮藏过程中腐烂率、水分含量、电导率、呼吸强度、过氧化氢酶(CAT)、过氧化物酶(POD)和超氧化物歧化酶(SOD)等生理指标的变化.结果表明,失水5%的板栗在贮藏期间的腐烂率、呼吸强度和电导率显著低于对照;CAT、POD和SOD活性维持较高水平.失水10%和15%的板栗在贮藏期间的腐烂率、相对电导率和呼吸强度显著高于对照,POD和SOD显著低于对照、处于低水平.试验表明,板栗采后少量失水对保鲜贮藏有一定的促进作用.     

水杨酸在植物胁迫抗性中的作用机制

水杨酸(SA)是植物体内一种重要的内源信号分子,不仅能调节植物的一些生长发育过程,还在植物胁迫抗性中发挥着重要的作用。本文主要简要综述了SA在诱导植物抗性方面的作用,分析和揭示了水杨酸增强植物抗性的初步机理。     

光敏性有机硅丙烯酸酯的合成及其改性紫外光固化材料研究

以Karstedt催化荆,催化端氢硅油(DHPS)和三缩丙二醇二丙烯酸酯(TPGDA)的硅氢加成反应,合成光敏性有机硅丙烯酸酯(SA).反应产物用红外光谱和紫外一可见光谱进行了表征,将不同比例的有机硅丙烯酸酯作为活性稀释剂添加到光固化体系中,考察了配方分别在空气和N2中的光固化性能,利用扫描电镜观察了光固化膜的表面形貌,研究了SA对光固化材料机械性能、热稳定性以及化学稳定性的影响.结果表明,氧阻聚作用对于SA配方比较明显,能显著降低其固化速率;SA对光固化膜物理化学性能有一定影响,含有5%SA的光固化材料综合性能优异,超过此含量,光固化材料机械和化学稳定性随着SA含量的增加反而降低;热重分析表明,SA能提高体系的热稳定性.     

Cadmium tolerance and accumulation characteristics of Bidens pilosa L. as a potential Cd-hyperaccumulator

Recently, researchers are becoming interested in using hyperaccumulators for decontamination of heavy metal polluted soils, whereas few species that hyperaccumulate cadmium (Cd) has been identified in the plant kingdom. In this study, the physiological mechanisms at the seedling stage and growth responses and Cd uptake and accumulation at flowering and mature stages of Bidens pilosa L. under Cd treatments were investigated. At the seedling stage, when soil Cd was lower than 16mgkg(-1), the plant did not show obvious symptom of phytoxicity, and the alterations of chlorophyll (CHL), superoxide dismutase (SOD), peroxidase (POD), malondialdehyde (MDA), and soluble protein (SP) did not have significant differences when compared with the control. At the flowering and mature stages, under low Cd treatments (相似文献   

Accumulation and acute toxicity of silver in Potamogeton crispus L.

In the present study, Potamogeton crispus L. plants exposed to various concentrations of silver (Ag) (5, 10, 15, and 20 μM) for 5 d were investigated to determine the accumulating potential of Ag and its influence on nutrient elements, chlorophyll pigments and fluorescence, various antioxidant enzymes and compounds, adenosine triphosphate (ATP), protein content and ultrastructure. The accumulation of Ag was found to increase in a concentration dependent manner with a maximum of 29.3 μg g^?1 at 20 μM. The nutrient elements (except Ca), photosynthetic pigments, chlorophyll a fluorescence parameters (Fo, Fv, Fv/Fm, Fv/Fo), malondialdehyde (MDA), ATP, peroxidase (POD) activity, ascorbate (AsA), reduced glutathione (GSH) and protein contents decreased significantly as concentration of Ag augmented. In contrast, an induction in SOD activity was recorded, while an initial rise in Ca content and CAT activity was followed by subsequent decline. Morphological symptoms of senescence phenomena such as chlorosis and damage of chloroplasts and mitochondria were observed even at the lowest concentration of Ag, which suggested that Ag hastened the senescence of the tested plants. The loss of nutrients and chlorophyll content and damage of chloroplasts were associated with disturbances in photosynthetic capacity as indicated by the quenching of chlorophyll a fluorescence. Decreased chlorophyll and protein contents suggest oxidative stress induced by Ag. In addition, both the reduction of ATP and the damage to the ultrastructure of organelles were indicative of general disarray in the cellular functions exerted by Ag.     

壳聚糖/柠檬酸复合涂膜对胡萝卜的保鲜效果

目的研究壳聚糖和柠檬酸复合涂膜对胡萝卜保鲜效果的影响,为胡萝卜采后保鲜贮藏提供新途径。方法以胡萝卜为实验材料,采用壳聚糖(质量分数为1%)涂膜、壳聚糖(质量分数为1%)/柠檬酸(质量分数为1%)复合涂膜处理胡萝卜,以未涂膜处理的胡萝卜为空白对照,研究贮藏期间不同处理组胡萝卜的主要品质指标和生理活性随贮藏时间的变化情况。结果贮藏90 d后,复合涂膜处理组胡萝卜的呼吸强度为3.02 mg/(kg·h),质量损失率为3.32%,Vc含量为0.1704 mg/g,可溶性糖质量分数为2.08%,胡萝卜素含量为0.0549mg/g,POD活性为0.53U/g,PAL活性为65.87U/g,复合涂膜较单一涂膜更好地延缓了贮藏期间Vc含量、可溶性糖含量和胡萝卜素含量的下降,较好地保持了POD和PAL酶的活性。结论壳聚糖涂膜和壳聚糖/柠檬酸复合涂膜处理能够有效提高胡萝卜的贮藏品质,维持其生理活性,延缓衰老进程,其中,壳聚糖/柠檬酸复合涂膜处理的综合保鲜效果要优于单一壳聚糖涂膜处理。     

壳聚糖-肉桂精油复合涂膜的制备及其对核桃贮藏品质的影响

目的 研究壳聚糖（Chitosan,CS）浓度和肉桂精油（Cinnamon Essential Oil,CEO）添加量对复合膜性能（力学性能、透氧率、吸湿率、抗氧化性）的影响及最佳复合涂膜对核桃贮藏品质的作用效果。方法 采用不同质量分数（1%、1.5%、2%）的CS与不同质量分数（0.1%、0.2%、0.3%、0.4%）的CEO制备复合涂膜，对涂膜的各项性能进行表征，采用最佳比例的复合涂膜处理核桃，测定核桃在贮藏期间的营养及氧化相关指标的变化。结果 质量分数为1.5%的CS和质量分数为0.3%的CEO制备的复合膜具备良好的机械与抗氧化性能，经过涂膜处理后的核桃相较于对照组和纯CS处理组能够有效保持核桃在贮藏期间含水量、可溶性蛋白、脂肪的含量及较高的过氧化物酶（Peroxidase,POD）活性；同时抑制了核桃在贮藏期间酸价、丙二醛含量、多酚氧化酶（Polyphenol Oxidase,PPO）活性的增加。结论 添加CEO能够有效提升壳聚糖涂膜的性能，最佳比例制备的CS-CEO复合涂膜可以较好地保持核桃在贮藏期间的营养与抗氧化品质。     

Comparative cytotoxicity evaluation of different size gold nanoparticles in human dermal fibroblasts

The aim of this work was to compare the effects of three commercially available gold nanoparticles (AuNPs) of different sizes (30, 50 and 90 nm) on the viability of normal human dermal fibroblasts (NHDF). In addition, we evaluated protective effect of N-Acetyl-L-cysteine (NAC), total glutathione content (GSH/GSSG), superoxide dismutase (SOD) activity and reactive oxygen species (ROS) production to investigate if oxidative stress was involved in the cytotoxic response of these AuNPs. Although AuNP-induced cytotoxicity was dose and time dependent, nanoparticle size slightly influenced the cytotoxic response of AuNPs assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and lactate dehydrogenase. Regarding oxidative parameters, NAC produced no significant protection of NHDF cells against treatment with any of the three AuNPs. Independently on nanoparticle size, GSH/GSSG content was drastically depleted after 24 h of incubation with the three AuNPs (less than 15% in all cases), while no statistically significant changes on SOD activity were reported (～90% of activity). The three AuNPs also caused a notable increase in the ROS production of NHDF cells. In conclusion, our data suggest that AuNP-induced cytotoxicity in NHDF is mediated by oxidative stress and it is independent of nanoparticle size.     

SO2不同保鲜处理对醉金香葡萄贮藏效果的影响

目的探究SO2不同保鲜处理对醉金香葡萄贮藏效果及安全性的影响。方法采用SO2气态处理结合固态保鲜剂处理SO2气+CT2和SO2气+简化包,以及单独固态保鲜剂处理CK+CT2和CK+简化包对葡萄进行处理,并贮藏于(0±0.5)℃的冷库中,分别在贮藏30,60,90,105 d时进行调查,并分析贮藏期间葡萄的脱粒率、腐烂率、呼吸强度、乙烯生成速率、可溶性固形物含量、可滴定酸含量、Vc含量、果梗和果皮电导率、MDA含量、叶绿素含量、花青素含量、PPO活性和POD活性。结果在4种保鲜处理中,CK+简化包处理对抑制葡萄果实腐烂有较好的作用,SO2+简化包处理对抑制脱粒表现较好,同时还可有效保持果实的可溶性固形物、可滴定酸、Vc、果梗叶绿素等含量,能很好地抑制果梗和果皮膜透性的增加及丙二醛含量的增加,对降低呼吸作用和乙烯释放量,抑制褐变,抑制PPO和POD活性等方面也起到了积极的作用。结论SO2气态处理结合固态保鲜剂处理(SO2气+简化包)能较好地保持葡萄贮藏期间的品质,延缓其衰老。     

Fast release of liquid antisolvent precipitated fenofibrate at high drug loading from biocompatible thin films

Motivated by recent papers on nano and micro-particle slurry casting of poorly water-soluble drugs forming biocompatible films with enhanced properties, this work explores incorporation of liquid antisolvent (LAS) precipitated suspensions of fenofibrate, a model poorly soluble drug using both semi-synthetic (HPMC E15 LV) and natural (sodium alginate, SA) polymer as film formers. Centrifugation and subsequent resuspension were employed to minimize residual solvent and increase drug loading (～20%) in the LAS suspensions and in the film. Film’s critical quality attributes (CQAs), including drug distribution and uniformity, mechanical properties, and dissolution were assessed. Crystalline nature of FNB was largely preserved in the film without any polymorphic changes confirmed by XRD, DSC, and Raman. The NIR chemical imaging, corroborated by SEM imaging and drug content relative standard deviation (RSD) indicates that the drug is uniformly distributed without any observable large agglomerates. The films with SA showed lower mechanical strength as compared to HPMC due to SA’s low molecular weight. All films exhibited immediate drug release as has been the case using FNB nano particles in previous papers. Interestingly, although addition of plasticizer improved film dissolution, HPMC-based films had a faster dissolution compared to SA-based films in spite of higher mechanical strength of the former.     

Seed germination and biochemical profile of Citrus reticulata (Kinnow) exposed to green synthesised silver nanoparticles

The biosynthesis of silver nanoparticles (AgNPs) is substantial for its applications in different fields. The Moringa oleifera leaves were used as reducing and stabilising agent for the biosynthesis of AgNPs. The synthesised AgNPs were characterised through UV–visible spectroscopy, zeta analyser, scanning electron microscopy (SEM) and energy dispersive Xray (EDX). In this study, effects of the synthesised AgNPs were also evaluated on nucellus tissues germination frequency and biochemical parameters of plant tissues. Nucellus tissues of Citrus reticulata were inoculated on MS medium supplemented with 10, 20, 30 and 40 µg/ml suspension of the synthesised AgNPs. Green synthesised AgNPs enhanced the in vitro germination because of low toxicity and nonfriendly issues. Significant results were obtained for germination parameters i.e. root and shoot length and seedling vigour index in response to 30 µg/ml suspension of green synthesised AgNPs. The 30 µ/ml suspension of AgNPs also enhanced antioxidant activity (41%) and SOD activity (0.36 nM/min/mg FW) while total phenolic content (4.7 µg/mg FW) and total flavonoid content (1.1 µg/mg FW) was significantly high when MS medium was fortified with 40 µg/ml suspension of the synthesised AgNPs. The content of total protein was significant (558 µg/BSA Eq/mg FW) in control plantlets as compared to the other treatments.Inspec keywords: antibacterial activity, ultraviolet spectra, X‐ray chemical analysis, proteins, microorganisms, biochemistry, nanofabrication, silver, nanotechnology, visible spectra, surface plasmon resonance, nanoparticles, suspensions, nanomedicine, scanning electron microscopy, electrokinetic effectsOther keywords: green synthesised silver nanoparticles, superoxide dismutase activity, biochemical profile, UV–visible spectroscopy, Citrus reticulata, green synthesised suspension, EDX detector, zeta potential, scanning electron microscopy, SEM, energy dispersive X‐ray, EDX, total phenolic content, total flavonoid content, size 423.0 nm to 425.0 nm, size 8.0 nm to 28.0 nm     

In vitro evaluation of polymeric micelles based on hydrophobically-modified sulfated chitosan as a carrier of doxorubicin

Four types of doxorubicin (DOX)-loaded polymeric micelles based on hydrophobically-modified sulfated chitosan (SCTS) were prepared. The hydrophobic group was composed of glycyrrhetinic acid (GA), cholic acid, stearic acid (SA) or lauric aldehyde. DOX encapsulation depended on several parameters, including the degree of substitution of the sulfate group and the hydrophobic group, and the type of hydrophobic group. Of these micelles, GA-SCTS micelles had the best capability to solubilize DOX. In addition, GA-SCTS micelles had the ability to target HepG(2) cells, and the IC50 for DOX-loaded GA-SCTS micelles was 54.7?ng/mL, which was much lower than that of the other micelles. Further studies on the DOX-loaded GA-SCTS micelles showed that they were stable in salt and protein solutions, in cell culture media, and during long-term storage (6?months). Based on these results, these micelles may be a promising DOX-encapsulated formulation, particularly, GA-SCTS as a potential vehicle for liver-targeted delivery.     

Understanding biotoxicity for reusability of municipal solid waste incinerator (MSWI) ash

This feasibility study using Escherichia coli DH5alpha as a reporter microorganism tended to disclose toxicity ranking of various ashes of municipal solid waste incinerator (MSWI) in comparison with typical toxic chemicals for reusability in further applications. Previous study indicated that growth inhibition to bacterial cells occurred at concentrations above 0.156, 0.625 and 0.0195g/L for bottom ash (BA), cyclone ash (CA), scrubber ash (SA), respectively, suggesting the toxicity ranking of SA>BA>CA. This follow-up study clearly stated that compared to cadmium(II) and chromium(II) SA seemed to be the most toxic species to DH5alpha. Large amounts of supplemented lime (CaO) were used for neutralization of acid gas in incinerator, SA was thus contained high-levels of sulfate, chloride and nitrate salts. Therefore, compared to other ashes a marked increase in toxicity was observed in SA. Regarding soluble cations and anions in ashes, nitrite ion seemed to stimulate instead of repress cell growth. In contrast, nitrate ion showed so-called "sufficient challenge" characteristics for growth enhancement and inhibition at low and high concentration, respectively. Low solubility of metallic ions (e.g., Pb(II) and Cu(II)) in ashes likely resulted in low mobility in the environment and low risk to humans. The findings showed that toxicity attenuation of SA will be inevitably required as SA is even more toxic than Cr(II) and Cd(II).