Synthesis and Characterization of a Hydroxyethyl Derivative of Chitosan and Evaluation of Its Biosafety

Hydroxyethyl chitosan(HE-chitosan) is a water-soluble derivative of chitosan with many apparent biological properties. For example, it is non-toxic and rapidly biodegradable. Moreover, HE-chitosan has advantages in water-solubility, moisture retention and gelling property due to its hydroxyethyl group. However, the biocompatibility and biodegradability of this multifunctional derivative have rarely been documented although they are critical for its application in biomedical and clinical treatments. The purpose of this work was to evaluate the biosafety of HE-chitosan, and draw important clues for its diverse applications. HE-chitosan was synthesized and characterized its chemical structure with FTIR. Its molecular weight(MW) was determined by gel permeation chromatography(GPC), and its deacetylation degree(DD) was investigated through potentiometric analysis. The cytotoxicity of HE-chitosan on mouse fibroblast cell L929 was tested. The biocompatibility and biodegradability of HE-chitosan in rat and rabbit were evaluated. The FTIR results indicated that the hydroxyethyl groups were linked to C6 of chitosan. The GPC analysis confirmed that its Mw was about 90.01 k Da. It was also demonstrated that HE-chitosan had excellent biocompatibility and biodegradability in vivo and had no cytotoxicity on L929. These findings indicated that HE-chitosan can potentially be applied as a biomaterial in tissue engineering, drug delivery, and other biomedical fields.     

Molecular Weight Controllable Degradation of Laminaria japonica Polysaccharides and Its Antioxidant Properties

In this study, molecular weight controllable degradation of algal Laminaria japonica polysaccharides(LPS) was investigated by ultrasound combined with hydrogen peroxide. Three main factors, i.e., ultrasonic power(A), ultrasonic time(B), and H_2O_2 concentration(C) were chosen for optimizing parameters by employing three-factors, three-levels BBD. The influence of degradation on structure change and antioxidant activities was also investigated. A second-order polynomial equation including molecular weight(Y) of Laminaria japonica polysaccharides and each variable parameter, i.e., ultrasonic power(A), ultrasonic time(B), and H_2O_2 concentration(C), was established: Y=20718.67-4273.13A-4000.38B-1438.75C+2333.25AB+1511.00AC+873.00BC+2838.29A~2 + 2490.79B~2+873.04C~2. The equation regression coefficient value(R~2 = 0.969) indicated that this equation was valid. The value of the adjusted determination coefficient(adjusted R~2 = 0.914) also confirmed that the model was highly significant. The results of selected experimental degradation conditions matched with the predicted value. FT-IR spectra revealed that the structures of LPS before and after degradation were not significantly changed. Antioxidant activities of LPS revealed that low Mws possessed stronger inhibitory than the original polysaccharides. The scavenging effects on superoxide radicals was the highest when IC50 of crude LPS was 4.92 mg mL~(-1) and IC50 of Mw 18.576 KDa was 1.02 mg mL~(-1), which was fourfold higher than initial polysaccharide.     

Preparation and characterization of magnetic resin made from chitosan and cerium

In this study,the water-based ferromagnetic fluid and magnetic resin made from chitosan and cerium complex(MRCCC) were successfully prepared by using the chemical co-precipitation technique and by the reversed-phase suspension cross-linking polymerization.MRCCC presented uniform and narrow particle size distribution as determined by the Laser Particles Sizer.The Inductively Coupled Plasma-Atomic Emission Spectrometry(ICP-AES),Fourier transform infrared spectroscopy(FT-IR),differential scanning calorimetry(DSC)and X-ray powder diffraction(XRD)study demonstrated that there were iron and cerium existing in MRCCC.The movement of MRCCC under magnetic field proved its magnetic property.The swelling kinetics in water or solutions with different pH indicated that MRCCC could be applied in solutions with pH greater than 1.0.The ferromagnetic fluid particles were stable in MRCCC soaked in solutions with pH >2.0.In view of these results,MRCCC can be used as material for separation,clarification,adsorption,sustained release and hydrolysis activity.     

Pharmacokinetics and Biodegradation Performance of a Hydroxypropyl Chitosan Derivative

Hydroxypropyl chitosan(HP-chitosan) has been shown to have promising applications in a wide range of areas due to its biocompatibility, biodegradability and various biological activities, especially in the biomedical and pharmaceutical fields. However, it is not yet known about its pharmacokinetics and biodegradation performance, which are crucial for its clinical applications. In order to lay a foundation for its further applications and exploitations, here we carried out fluorescence intensity and GPC analyses to determine the pharmacokinetics mode of fluorescein isothiocyanate-labeled HP-chitosan(FITC-HP-chitosan) and its biodegradability. The results showed that after intraperitoneal administration at a dose of 10 mg per rat, FITC-HP-chitosan could be absorbed rapidly and distributed to liver, kidney and spleen through blood. It was indicated that FITC-HP-chitosan could be utilized effectively, and 88.47% of the FITC-HP-chitosan could be excreted by urine within 11 days with a molecular weight less than 10 k Da. Moreover, our data indicated that there was an obvious degradation process occurred in liver( 10 k Da at 24 h). In summary, HP-chitosan has excellent bioavailability and biodegradability, suggesting the potential applications of hydroxypropyl-modified chitosan as materials in drug delivery, tissue engineering and biomedical area.     

基于Pt/SAPO-11和Pt/ZSM-22催化剂的溶剂脱蜡油加氢异构反应

采用常规水热法合成SAPO-11和ZSM-22分子筛,制备分别含有分子筛的催化剂,借助XRD、SEM和NH3-TPD表征2种催化剂的结构和酸性,并以加氢预精制溶剂脱蜡油为原料,采用固定床反应器研究Pt/SAPO-11和Pt/ZSM-22催化剂的加氢异构反应性能.结果表明:催化剂的反应活性和选择性主要取决于催化剂的酸量和酸强度,相对而言,由于SAPO-11分子筛催化剂弱酸含量较高,具有更佳的异构化选择性.利用1HNMR和13CNMR核磁共振研究加氢异构反应前后基础油的化学结构变化,Pt/SAPO-11催化剂有较高的加氢异构选择性.     

Structural analysis and anti-complement activity of polysaccharides extracted from Grateloupia livida (Harv.) Yamada

Polysaccharides were extracted from Grateloupia livida(Harv.) Yamada using hot water(extracted product denoted WGW) and then degraded in dilute sulfuric acid(degraded product denoted WGWD). The degraded mixture was then separated into four fractions through anion exchange chromatography on 2-diethylaminoethanol(DEAE)-Bio-Gel Agarose FF gel. Electrospray ionization collision-induced dissociation tandem mass spectrometry(ESI-CID-MS/MS) was performed to elucidate the structural features of all fractions. In combination with nuclear magnetic resonance spectroscopy(NMR)and infrared spectroscopy(IR) data, the major polysaccharide structures were concluded to be μ-carrageenan and κ-carrageenan. μ-Carrageenan usually has a backbone of alternating 1,3-linked β-D-galactopyranose residues sulfated at C-4 and 1,4-linked a-D-galactopyranose residues sulfated at C-6, while κ-carrageenan consists of alternating 1,3-linked β-D-galactopyranose residues sulfated at C-4 and 1,4-linked a-D-3,6-anhydrogalactopyranose residues. Trace v-carrageenan, composed of 1,3-linked β-D-galactopyranose residues sulfated at C-4 and 1,4-linked a-D-galactopyranose residues sulfated at C-2 and C-6, was also detected. Furthermore, the polysaccharide had a backbone comprising 1,3-linked β-D-galactopyranose and1,4-linked α-L-galactopyranose sulfated at C-6, which is the agarose precursor. The hydroxy groups in the galactopyranose were partially substituted by methyl and pyruvic acid acetal(PA) groups. The anticomplementary activities of WGW and its derivatives against classical pathways were measured. The native polysaccharides in WGW had higher activities, while the derivatives had much weaker activities. This indicated that the molecular weight and sulfate content were important factors affecting the anti-complement activity.     

新型两亲性低分子多胺页岩抑制剂的特性

为提高胺类抑制剂的抑制性和抗温性,优选一种新型两亲性低分子多胺BHTA,设计页岩滚动分散实验、抑制膨润土造浆实验、粒度分布测试评价抑制性能.结果表明:BHTA抑制性优于传统的无机盐类抑制剂KCl和国外聚胺产品Ultrahib,能有效抑制黏土水化膨胀和分散,耐温性优良,可用作泥页岩水化抑制剂.采用Zeta电位测试、红外光谱分析、改性膨润土吸水实验及X线衍射分析测试黏土层间距等,探讨BHTA的作用机理,表明BHTA主要通过质子化胺基与黏土颗粒的静电作用、氢键吸附在黏土表面,以静电吸附为主,通过疏水屏蔽作用发挥抑制作用;BHTA单层吸附进入黏土层间,能最大限度降低黏土水化层间距,破坏黏土水化结构.     

Molecular weight controllable degradation of <Emphasis Type="Italic">Laminaria japonica</Emphasis> polysaccharides and its antioxidant properties

In this study, molecular weight controllable degradation of algal Laminaria japonica polysaccharides（LPS） was investigated by ultrasound combined with hydrogen peroxide. Three main factors, i.e., ultrasonic power（A）, ultrasonic time（B）, and H₂O₂ concentration（C） were chosen for optimizing parameters by employing three-factors, three-levels BBD. The influence of degradation on structure change and antioxidant activities was also investigated. A second-order polynomial equation including molecular weight（Y） of Laminaria japonica polysaccharides and each variable parameter, i.e., ultrasonic power（A）, ultrasonic time（B）, and H₂O₂ concentration（C）, was established: Y=20718.67-4273.13A-4000.38B-1438.75C+2333.25AB+1511.00AC+873.00BC+2838.29A² + 2490.79B²+873.04C². The equation regression coefficient value（R² = 0.969） indicated that this equation was valid. The value of the adjusted determination coefficient（adjusted R² = 0.914） also confirmed that the model was highly significant. The results of selected experimental degradation conditions matched with the predicted value. FT-IR spectra revealed that the structures of LPS before and after degradation were not significantly changed. Antioxidant activities of LPS revealed that low Mws possessed stronger inhibitory than the original polysaccharides. The scavenging effects on superoxide radicals was the highest when IC50 of crude LPS was 4.92 mg mL^-1 and IC50 of Mw 18.576 KDa was 1.02 mg mL^-1, which was fourfold higher than initial polysaccharide.     

Pharmacokinetics and Biodegradation of Chitosan in Rats

Chitosan, an excellent biomedical material, has received a widespread in vivo application. In contrast, its metabolism and distribution once being implanted were less documented. In this study, the pharmacokinetics and biodegradation of fluorescein isothiocyanate(FITC) labeled and muscle implantation administrated chitosan in rats were investigated with fluorescence spectrophotometry, histological assay and gel chromatography. After implantation, chitosan was degraded gradually during its distribution to diverse organs. Among the tested organs, liver and kidney were found to be the first two highest in chitosan content, which was followed by heart, brain and spleen. Urinary excretion was believed to be the major pathway of chitosan elimination, yet 80% of chitosan administered to rats was not trackable in their urine. This indicated that the majority of chitosan was degraded in tissues. In average, the molecular weight of the degradation products of chitosan in diverse organs and urine was found to be 65 k Da. This further confirmed the in vivo degradation of chitosan. Our findings provided new evidences for the intensive and safe application of chitosan as a biomedical material.     

湿热处理对壳聚糖/PVA共混膜结构和性能的影响

用流延法成功制备壳聚糖/PVA共混膜,并进行湿热处理,用FT-IR、XRD对经过湿热处理共混膜进行了表征,测试了膜的力学性能和吸水性;结果表明,随着湿热处理时间的增长共混膜的无水结晶峰出现并不断增强。共混膜的吸水性实验表明,壳聚糖/PVA共混膜的pH敏感性可通过控制湿热处理的时间来改变,由于湿热处理不需要引入诸如戊二醛等对生物有毒副作用的化学交联剂,所以该法可望在壳聚糖/PVA共混膜控释体系的后处理方面得到应用。     

Degradation significantly decreased the ecosystem multifunctionality of three alpine grasslands: evidences from a large-scale survey on the Qinghai-Tibetan Plateau

Owing to the joint effects of ecosystem fragility,anthropogenic disturbance and climate change,alpine grasslands(alpine meadow,alpine steppe and alpine desert)have experienced serious degradation during the past several decades.Grasslands degradation has severely affected the delivery of ecosystem multifunctionality(EMF)and services,and then threatens the livelihood of local herdsmen and ecological security of China.However,we still lack comprehensive insights about the effects of degradation and climatic factors on EMF of alpine grasslands,especially for alpine desert ecosystem.Therefore,we applied a large-scale field investigation to answer this question.Our results suggested grassland degradation significantly decreased the belowground ecosystem multifunctionality(BEMF)and EMF of alpine grasslands and aboveground ecosystem multifunctionality(AEMF)of alpine meadow,while did not reduce the AEMF of alpine steppe and desert.Except for the insignificant difference between degraded steppe and degraded desert in AEMF,the alpine meadow showed the highest AEMF,BEMF and EMF,alpine steppe ranked the second and alpine desert was the lowest.AEMF,BEMF and EMF of health alpine grasslands were strongly affected by mean annual precipitation(MAP)(19%-51%)and mean annual temperature(MAT)(9%-36%),while those of degraded meadow and degraded desert were not impacted by precipitation and temperature.AEMF and BEMF showed a synergistic relationship in healthy alpine grasslands(12%-28%),but not in degraded grasslands.Our findings emphasized the urgency of implementing the feasible ecological restoration project to mitigate the negative influences of grassland degradation on EMF of alpine ecosystems.     

Structural studies on the oligomers from the polysaccharide ofGracilaria textorii (Rhodophyta) using β-agarase and13C-NMR spectroscopy

The 60% ethanolic extract fromGracilaria textorii (Rhodophyta) was degraded with β-agarase, and certain charged (sulfated) and neutral oligosaccharides were separated by using DEAE Sephadex A25 and Bio- gel P6, P2 chromatographic techniques. Some of the charged oligomers were verified to be neoagarotetraose-6³-sulfate (DP2), neoagarohexaose-6³, 6⁵-disulfate (DP3) and neoagarooctaose-6³, 6⁵, 6⁷-trisulfate (DP4) by using¹³C- and¹H-NMR spectroscopy. One neutral oligomer was assumed to be a mixture of methylated neoagarotetraoses (DP2) by¹H-NMR spectroscopy. These oligomers assigned by their chemical shifts may be used as the model compounds for the structural investigation of the agar-type sulfated polysaccharides using the β-agarase degradation method. Contribution No. 1749 from the Institute of Oceanology, Academia Sinica.     

Response to selection for fast growth in the second generation of Pacific oyster (Crassostrea gigas)

Mass selection for fast growth was conducted in three Pacific oyster (Crassostrea gigas) stocks from China, Japan and Korea using previously established lines (CS1, JS1, and KS1). To determine whether continuous progress can be achieved by selection for growth, the progeny of three second-generation Pacific oyster lines was selected for shell height and evaluated via a 400-day farming experiment. When harvested at the end of the experiment, the selected crosses of CS2, JS2, and KS2 lines grew by 9.2%, 10.2% and 9.6% larger than the control crosses, respectively. During grow-out stage, the genetic gain of three selected lines was (10.2 ± 1.4)%, (10.4 ± 0.3)%, and (8.4 ± 1.6)%, respectively; and the corresponding realized heritability was 0.457 ± 0.143, 0.312 ± 0.071 and 0.332 ± 0.009, respectively. These results indicated that the selection for fast growth achieved steady progress in the second generation of oyster. Our work provides supportive evidence for the continuity of the Pacific oyster selective breeding program.     

北京防震历史经验与汶川地震灾后城镇选址重建

5.12汶川8.0级地震使灾区蒙受了巨大的生命和财产损失,地震造成的灾害与灾区地质构造有极强的空间相关性。灾区地震历史的分析结果表明,该区域地震格局有明显的时空特征,重灾区灾后重建城镇选址宜多学科联合谨慎规划。康熙18年(1679年)的北京平谷-三河8.0级地震与5.12汶川地震惨烈程度相近,北京地质构造研究与地震时空格局分析具有重大的现实意义,北京城市发展中的防震规划历史经验值得5.12地震灾区在重建与今后发展中借鉴。     

Photochemical degradation of triadimefon in seawater

The photochemical degradation of triadimefon in seawater was investigated under different reaction conditions in this study. The results showed that triadimefon could be effectively degraded by the irradiation of a high-pressure mercury lamp and the photodegradation rotes were influenced by aquatic media, heavy metal ions and photosensitizers. The photochemical degradation of triadimefon followed the first-order reaction kinetic behavior, with the rate constants ranging from 0.0027 to 0.0128 min-1 under the studied conditions. The photolysis of triadimefon was slower in natural seawater than in distilled water or synthetic seawater. All the heavy metal ions studied in this paper had inhibition effects on the photolysis of triadimefon. Acetone, as a common photosensitizer, could accelerate the photolysis of triadimefon. Three photoproducts were identified by GC-MS analysis. Our study confirmed that photochemical degradation is an effective pathway to remove triadimefon in seawater.     

新型壳聚糖季铵盐衍生物的合成与表征

采用甲磺酸作为溶剂兼作氨基保护试剂,对壳聚糖上的羟基选择性酯化,再游离出氨基并对其氯乙酰化,最后进行吡啶成盐,得到新型水溶性的壳聚糖季铵盐衍生物,产物的结构通过核磁共振氢谱和红外光谱进行了表征,从而为壳聚糖季铵盐衍生物的制备提供了一种新途径。     

利用高频GPS反演强震面波震级的最优适用范围探讨

通过解算2010-04-04El Mayor-Cucapah Mw7.2地震的高频(1Hz)GPS数据,获取测站的动态位移,并根据Gutenberg经验震级公式反演面波震级,探索高频GPS反演震级的最优适用范围。结果表明,当高频GPS测站震中距分布于50~350km时,利用其水平位移峰值反演得到的面波震级为7.21,与美国USGS公布的震级Mw7.2一致;但当震中距350km时,高频GPS相对于强震仪位移峰值存在"上漂现象",反演得到的震级为7.6~8.0。建议利用高频GPS建立经验模型反演强震面波震级时,应考虑其适用范围。     

Preliminary study on PAH degradation by bacteria from contaminated sediments in Xiamen Western Sea,Fujian, China

In order to estimate the biodegradation of three polycyclic aromatic hydrocarbons (PAHs) compounds, bacterial strains were isolated from marine sediments in three heavily contaminated sites (Yuandang Lake, Dongdu Port and Aquacultural zones in Maluan Bay) in Xiamen Western Sea. The results show three bacterial strains, which used pyrene as the sole carbon source, were identified as strains of Aureobacterium sp.,Arthrobacter sp., Rhodococcus sp. The PAH-degrading bacteria isolated had a strong ability to degrade phenanhrene, fluoranthene and pyrene at different degradation rates. The highest degradation rate was observed when three PAH compounds were mixed with an individual strain in the medium. The three PAHs were degraded after one week with a degradation rate of 89.94 % for phenanthrene and 93.4 % for both of fluoranthene and pyrene.In addition, after 25 days of incubation, the degradation rate was 99.98 % for phenanthrene and 99.97 % for both of fluoranthene and pyrene. Optical density was measured to estimate bacterial growth during the degradation of PAHs. Highest levels of bacterial growth were observed with a three PAH mixture in the culture, suggesting that the concentration of PAHs influenced bacterial growth and the highest levels of degradation for most series were detected after one week of incubation.     

三江源南部草地退化时空特征分析

本文利用三江源南部1977年MSS、1990年TM和2004年TM三期遥感影像,结合1∶10万地形图、1∶100万草地图、1∶100万植被图和野外考察等资料,分析该区草地退化的时空变化特征和规律。结果表明:该区草地总体呈轻度退化,即为轻度破碎化退化、轻度覆盖度下降、轻度破碎化和轻度覆盖度下降复合型退化,共占研究区退化总面积的84.3%;轻度退化草地主要散布在唐古拉山东北部区域,中度退化草地多数分布于河流、居民点周围,草地轻度沙化/盐化退化主要发生在湖盆周围、河岸附近、滩地等区域。草地退化面积随海拔高度升高近似于正态分布,退化面积集中4 400～5 300m左右。1977～1990年和1990～2004年前后两期草地退化面积占研究区草地面积12.6%和18.9%,指示着草地状况的恶化。同时,对前后两个时段比较发现,草地退化发生以破碎化为先导,随后发生覆盖度持续降低。沼泽和沼泽化草甸的变化反映了区内气候的趋干化。另外,受气候条件等因素的影响,前期草地和沼泽变化有转好迹象。     

Preparation of adsorbent with magnesium sulfate and straw pulp black liquor and its phenol adsorption properties

A magnesia adsorbent was prepared from straw pulp black liquor and magnesium sulfate for the first time, and its adsorption of phenol from aqueous solution was examined. The characteristics of the adsorbent were tested through chemical analysis, surface analysis, X-ray diffraction and FT-IR spectroscopy. The effects of various factors, such as dose, adsorption time and adsorption temperature, on phenol adsorption behavior were studied. The results show that the adsorption processes can be fitted to the isotherm Langmuir model very well. It was found that the adsorption process was strongly influenced by temperature and the optimal temperature for phenol removal was 40 °C. The optimum adsorption time was 10 min, and desorption would happen afterwards. Between the models of Langmuir and Freundlich, the adsorption process of phenol onto magnesia fitted the Langmuir equation better.