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1.
硫酸交联壳聚糖干膜的13C CP MAS NMR研究   总被引:2,自引:0,他引:2  
江涛  杨年华 《波谱学杂志》1997,14(2):115-119
以不同浓度硫酸交联的壳聚糖干膜为研究对象,在国内首次采用13C CP MAS NMR技术从分子水平上对壳聚糖膜的结构进行研究,结果表明干膜壳聚糖分子的构象能直观地反映出膜的交联状况,交联状况与膜的分离性能密切相关,但仅对干膜的考察还不够全面.  相似文献   

2.
用核磁共振方法研究了β-CD与三种菁染料3,3′-二(3-磺丙基)噻菁三乙胺盐(d-yeA)、3,3′-二(3-磺丙基)-5-氯-噻菁三乙胺盐(dyeB)和3,3′-二(3-磺丙基) -5,5′-二苯基-9-乙基恶碳菁(dyeC)在溶液中的包合现象和包合物的动态结构,实验发现β-CD环糊精疏水腔中的H-3和H-5以及三种菁染料的芳环上质子的化学位移由于形成包合物而发生明显变化, 而且峰的位置随包合程度的不同而不同. 实验中发现包合物的荧光强度随β-CD浓度增加而减弱,相应计算表明β-CD与三种菁染料形成了1∶1的包合物.本文研究了三种包合物中主体部分OH-3和OH-6的化学位移随温度变化的情况,获得了包合物中氢键强弱的信息, 通过NMR化学位移滴定法计算得到了三种包合物在水溶液中的稳定常数, 在上述工作的基础上,本文提出了三种包合物的结构模型,描述了客体进入主体腔中的动态过程.  相似文献   

3.
CO32-掺杂是提高纳米羟基磷灰石(n-HA)生物活性的有效方法之一。以Ca(NO3)2·4H2O和Na3PO4·12H2O为主要原料,Na2CO3作为CO2-3来源,合成纳米碳羟基磷灰石(n-CHA)晶体。采用TEM,XRD,FTIR,RS对合成晶体形貌和结构进行表征。结果表明:合成的n-HA晶体长度约为60~80nm,宽度在20~30nm之间,形状为针状,具有良好的结晶度,与自然骨磷灰石形貌相似;n-CHA晶体随CO2-3掺入量的增加,结晶度降低;合成的n-CHA晶体的晶胞参数a值随着CO2-3加入量的增大不断收缩,但c值增大,参数比c/a值增大,符合B型取代(取代PO3-4)的晶胞参数变化规律。红外谱图中,872cm-1附近出现AB混合型取代(同时取代OH-,PO3-4)的CO2-3面外弯曲振动特征红外峰,同时CO2-3的不对称伸缩振动红外峰在1 454和1 420cm-1附近出现分裂峰,1 540cm-1附近出现弱CO2-3峰;1 122cm-1附近出现CO2-3对称伸缩振动拉曼峰,1 071cm-1附近出现CO2-3的B型替代特征拉曼峰,通过计算PO3-4,CO2-3,OH-拉曼峰的积分面积比PO3-4/CO2-3,OH-/CO23,PO3-4/OH-,表明CO2-3在替换时,先以B型为主,随着CO2-3掺入量的增加,发生A型替代(取代OH-)。实验结果表明,合成的磷灰石晶体为B型取代(取代PO3-4)为主的AB混合型取代的n-CHA。与人骨磷灰石晶体在形态、尺寸、晶体结构和生长方式上具有相似性,可称为类骨磷灰石。  相似文献   

4.
壳聚糖富集-火焰原子吸收法测定痕量银   总被引:8,自引:0,他引:8  
研究了天然高分子吸附剂壳聚糖对银离子的吸附行为以及在不同pH值、干扰离子存在时对壳聚糖吸附银离子的影响,通过选择最佳吸附条件,建立了壳聚糖富集火焰原子吸收法测定银的方法。当溶液pH60、流速为1mL·min-1时,吸附率最高,达967%,静态饱和吸附量为978mg·g-1。用1mol·L-1H2SO4作为洗脱剂,洗脱效果最好。壳聚糖不吸附K+,Na+,Ca2+,Mg2+,Mn2+,富集时可与被测银离子分离,不干扰测定。100mg·mL-1的Al3+,Cr3+,80mg·mL-1的Ni2+,Cu2+,Pb2+,Zn2+虽然可被壳聚糖吸附,但不干扰测定。用此方法对实验室含银(183μg·mL-1)废水中的Ag进行测定,回收率为943%。  相似文献   

5.
利用1H NMR、13C NMR、COSY、HSQC和HMBC等多种核磁共振技术,结合MS技术,确认了皂苷Tb的2个糖基化产物的结构,即偏诺皂苷元-3-O-α-D-葡萄糖-(1→3)[α-L-鼠李糖(1→2)]-β-D-葡萄糖苷(1)和偏诺皂苷元-3-O-α-D-葡萄糖-(1→4)-α-D-葡萄糖-(1→3)[α-L-鼠李糖-(1→2)]-β-D-葡萄糖苷(2). 化合物1和2为新化合物,对其1H NMR和13C NMR信号分别进行了全归属和详细分析.  相似文献   

6.
以3-氧化木糖为原料,通过Henry反应与硝基甲烷加成,得到两种硝基糖化合物1,2-O-异丙叉基-3-C-硝甲基-5-对甲苯磺酰基-α-D-呋喃核糖(1)和1,2-O-异丙叉基-3-C-硝甲基-4-甲烯基-α-D-呋喃核糖(2),其中化合物2为新型的硝基糖化合物.通过应用1D NMR和2D NMR测试了化合物2的1H NMR、13C NMR、1H-1H COSY、gHSQC和gHMBC,对化合物2的1H和13C进行了全归属.  相似文献   

7.
从胭脂树(Bixo orellana)种子中分离得到了一种胭脂树低聚糖:α-D-半乳糖-(1→3)-α-D-半乳糖-(1→6) -α-D-葡萄糖-(1→2)-β-D-果糖(BO-1). 通过1D NMR和2D NMR实验技术对其1H NMR和13C NMR谱信号进行了全归属.   相似文献   

8.
含手性轴的季戊四醇双缩醛的NMR研究   总被引:1,自引:1,他引:0  
采用1D和2D梯度场NMR技术(包括1D 1H NMR, 13C NMR, DEPT, 2D 1H-1H COSY, HSQC, HMBC),对3,3′-二(2,4-二氯苯基)-2,4,2′,4′-四氧杂螺[5.5]十一烷的4个亚甲基呈现的4组裂分峰进行了明确的归属,也对化合物中其它1H和13C NMR谱信号进行了全归属,为四氧杂螺双缩醛类化合物的结构鉴定提供了充分依据.  相似文献   

9.
猪去氧胆酸衍生物的NMR研究   总被引:1,自引:0,他引:1  
对6α-羟基-3α-苯甲酰氧基-5β-胆烷酸甲酯(化合物1)及3α-羟基-6α-苯甲酰氧基-5β-胆烷酸甲酯(化合物[STHZ]2[STBZ])进行了1H,13C NMR检测,通过DEPT及DQF-COSY,13C-1H COSY, COLOC等NMR技术对其1H和13C NMR数据进行了全归属和详细的解析,并指出了其NMR数据特征.  相似文献   

10.
本文测定了N(,N′)-(二)对甲苯磺酰基大环醚双内酯(附图11~6),N,N′-二羧甲基大环醚双内酯和大环胺双内酰胺(图18~2),4′-丹磺酰氨基苯并冠醚(图113~16)等十八个新冠醚的~1H,~(13)C NMR谱并进行了归属。作者发现,随着冠醚环的增大,冠1~6的次甲基b和冠8~11的次甲基a、b、c的~1H化学位移向低场移动,当冠环增大至21~24员时,这种偏移趋于极限。溶剂对8~11化合物的~1H NMR影响表明,次甲基a、b、c的~1H位移随溶剂的极性增大而增大,次序为:CD_3COOD>PY-d_5≥D_2O>>CD_3OD>CD_3CD_2OD>DMF-d_6>DMSO-d_6。  相似文献   

11.
Hexanoyl chitosan and lauroyl chitosan were prepared by acyl modification of chitosan. Films of hexanoyl chitosan- and lauroyl chitosan-based polymer electrolytes incorporated with different weight concentrations of sodium iodide (NaI) were prepared using the solution casting technique. FTIR and differential scanning calorimetry (DSC) results suggested that NaI interacted with both hexanoyl chitosan and lauroyl chitosan. Maximum conductivities of 1.3 × 10?6 and 1.1 × 10?8 S cm?1 are achieved for hexanoyl chitosan and lauroyl chitosan, respectively. Higher conductivity in hexanoyl chitosan is attributed to higher ion mobility as supported by DSC results. The dielectric constants of neat hexanoyl chitosan and lauroyl chitosan are 2.7 and 1.9, respectively, estimated from impedance spectroscopy. Higher dielectric constant of hexanoyl chitosan resulted in greater NaI dissociation and hence higher conductivity. Deconvolution of O═C-NHR and OCOR bands of polymer has been carried out to estimate the amount of dissociated Na+ ions from NaI. The findings were in good agreement with conductivity results. In order to assess quantitatively, the conductivity, parameter number, n, and mobility, μ, of ions were calculated using impedance spectroscopy. XRD results showed the influence of NaI on the crystalline content of the electrolyte system. Sample with lower crystalline content exhibited higher conductivity.  相似文献   

12.
Hexanoyl chitosan soluble in THF is prepared by acyl modification of chitosan. Epoxidation natural rubber (ENR25) (25 mol%) is chosen to blend with hexanoyl chitosan. Films of hexanoyl chitosan/ENR25 blends containing lithium bis(trifluoromethanesulfonyl)imide (LiN(CF3SO2)2) and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMImTFSI) are prepared by solution casting technique. FTIR results suggested that LiN(CF3SO2)2 salt interacted with hexanoyl chitosan, ENR25, and EMImTFSI. EMImTFSI interacted with hexanoyl chitosan and ENR25 to form EMIm+-hexanoyl chitosan and EMIm+-ENR25 complexes, respectively. The effect of EMImTFSI on the morphology and thermal properties of the blends is investigated by polarized optical microscopy (POM) and differential scanning calorimetry (DSC), respectively. The ionic conductivity of the electrolytes is measured by electrochemical impedance spectroscopy (EIS). Upon addition of 12 wt% EMImTFSI, a maximum conductivity of 1.3 × 10?6 S cm?1 is achieved. Methods based on impedance spectroscopy and FTIR are employed to study the transport properties of the prepared polymer electrolytes. The ac conductivity was found to obey universal law, σ(ω)?=?σ dc ?+? S . The temperature dependence of exponent s is interpreted by the small polaron hopping (SPH) model.  相似文献   

13.
Hydroxyapatite Nano Sol Prepared via A Mechanochemical Route   总被引:2,自引:0,他引:2  
Well-dispersed sol with crystalline hydroxyapatite (HAp) was obtained directly by milling a mixture comprising Ca(OH)2, an aqueous solution of H3PO4 and a dispersant, an ammonium salt of polyacrylic acid. The average crystallite size of HAp was below 20 nm. Ca/P molar ratio of the product was 1.51 ± 0.04, i.e. Ca deficient from stoichiometric HAp. Minimum apparent viscosity was attained at a dispersant concentration 0.92wt% of sol. An as-milled sol was diluted by a factor 10–2.61 solid wt% to give a Newtonian fluid of 2 mPa s. From the diluted sol, we obtained a few m thick dense film of HAp by dip coating on the slide glass precoated by chitosan.  相似文献   

14.
The chitosan-coated magnetic nanoparticles (CS MNPs) were in situ synthesized by cross-linking method. In this method; during the adsorption of cationic chitosan molecules onto the surface of anionic magnetic nanoparticles (MNPs) with electrostatic interactions, tripolyphosphate (TPP) is added for ionic cross-linking of the chitosan molecules with each other. The characterization of synthesized nanoparticles was performed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS/ESCA), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), dynamic light scattering (DLS), thermal gravimetric analysis (TGA), and vibrating sample magnetometry (VSM) analyses. The XRD and XPS analyses proved that the synthesized iron oxide was magnetite (Fe3O4). The layer of chitosan on the magnetite surface was confirmed by FTIR. TEM results demonstrated a spherical morphology. In the synthesis, at higher NH4OH concentrations, smaller sized nanoparticles were obtained. The average diameters were generally between 2 and 8?nm for CS MNPs in TEM and between 58 and 103?nm in DLS. The average diameters of bare MNPs were found as around 18?nm both in TEM and DLS. TGA results indicated that the chitosan content of CS MNPs were between 15 and 23?% by weight. Bare and CS MNPs were superparamagnetic. These nanoparticles were found non-cytotoxic on cancer cell lines (SiHa, HeLa). The synthesized MNPs have many potential applications in biomedicine including targeted drug delivery, magnetic resonance imaging?(MRI), and magnetic hyperthermia.  相似文献   

15.
The enzymatic destruction of chitosan in an acetic acid solution in the presence of sodium chloride and sulfate was considered. It was shown that the addition of these low-molecular electrolytes is accompanied by a tightening of the macromolecular coil, as indicated by a decrease in the α constant in the Mark–Kuhn–Houwink equation and the intrinsic viscosity of chitosan. As a consequence, the chitosan units become less accessible for interaction with the enzyme, and the kinetic parameters of the process (Michaelis constant K M and the maximum rate of enzymatic destruction V max) change accordingly. This suggests that the resistance of this polymer to the enzyme action can be enhanced by introducing low-molecular electrolyte salts in the solution or film coating to suppress the polyelectrolyte swelling of chitosan.  相似文献   

16.
Design of peptide affinity ligands against biological targets is important for a broad range of applications. Here, we report on de novo and combinatorial strategies for the design of high-affinity and high-specificity peptides against S-protein as a target. The peptide libraries employed in this study contain (1) consensus motif (CM) sequences identified from high-throughput phage combinatorial screening, (2) point mutations of CM sequences, and (3) de novo sequences rationally designed based on stereo-chemical information of the complex between S-protein and its natural ligand, S-peptide. In general, point mutations to CM allowed for modulating peptide affinity and specificity over a broad range. This is particularly useful in designing peptides with varying affinities and specificities for the target. De novo sequences, especially those based on the S-protein binding pocket, on average bound with higher affinities within a narrow range (10–100 nM) as compared to point mutations to CM (1 nM–2 $\mu $ M). As such, the approaches described here serve as a general guide for optimizing the design of peptide affinity ligands for a wide range of target proteins or applications.  相似文献   

17.
The problem of center-of-mass (CM) contaminations in ab initio nuclear structure calculations using configuration interaction (CI) and coupled-cluster (CC) approaches is analyzed. A rigorous and quantitative scheme for diagnosing the CM contamination of intrinsic observables is proposed and applied to ground-state calculations for 4He and 16O. The CI and CC calculations for 16O based on model spaces defined via a truncation of the single-particle basis lead to sizable CM contaminations, while the importance-truncated no-core shell model based on the NmaxΩ space is virtually free of CM contaminations.  相似文献   

18.
19.
《Physics letters. A》2020,384(29):126775
Detecting toxic gases is of great importance to protect our health and preserve the quality of life. In this work, graphene (G) and graphene oxide with three different modifications (G–O, G–OH, and G–O–OH) have been used to detect hydrogen selenide (H2Se), hydrogen telluride (H2Te), and phosphine (PH3) molecules based on Atomistic ToolKit Virtual NanoLab (ATK-VNL) package. The adsorption energy (Eads), adsorption distance (D), charge transfer (ΔQ), density of states (DOS), and band structure have been investigated to confirm the adsorption of H2Se, H2Te, and PH3 on the surface of G, G–O, G–OH, and G–O–OH systems. The results of G revealed highest Eads for the case of H2Te with −0.143 eV. After the functionalization of G surface, the adsorption parameters reflected an improvement due to the presence of the functional groups. Particularly, the highest adsorption energy was found between G–O system and H2Se gas with Eads of −0.319 eV. The smallest adsorption distance was found between G–OH system and H2Se gas. The highest charge transfer was found for the case of H2Se gas adsorbed on G–O–OH system. By thorough comparison of the adsorption energy, adsorption distance, and charge transfer between G, G–O, G–OH, and G–O–OH systems and the three gases, G–O–OH system can be considered as a potential sensor for H2Se gas.  相似文献   

20.
The mammalian female reproductive tract cells have been wildely used in in vitro fertilization. We studied the secretory proteins of porcine oviductal epithelial cells (POEC), and cumulus cells (CC) co-cultured with granulosa cells (GC) in conditioned media (CM), and their ability in inducing acrosome reaction (AR) on frozen-thawed bovine spermatozoa. POEC and CC+GC were cultured in M 199 medium for 48, 96 and 144h prior to investigation of protein secretion. The results from SDS-PAGE showed secretory proteins sizes of about 17, 22 and >220kDa in both CM from POEC and CC+GC. To test the ability of CM from POEC and CC+GC in inducing AR, the CM was frozen for 1-3 months before incubating with frozen-thawed bovine spermatozoa. Percentages of the spermatozoa with AR were determined under an inverted microscope and it was found that the tested group 1 (incubated with fresh and frozen CM from POEC for 1-3 months) were 78.44+/-7.25, 75.78+/-4.41, 65.22+/-5.59 and 50.56+/-6.25, respectively. The tested group 2 (incubated with fresh and frozen CM from CC+GC for 1-3 months) had the percentages of the spermatozoa with AR at 88.67+/-4.03, 82.22+/-3.46, 71.00+/-3.16, and 58.56+/-4.69, respectively. Statistical analysis of all group percentages indicated that they were significantly different (P<0.05). Transmission electron microscope studies demonstrated that there were morphological changes on the sperm heads which resulted in the leakage of acrosin and subsequent AR. We concluded that the CM from both POEC and CC+GC efficiently increased in vitro AR on frozen-thawed bovine spermatozoa. Identification and functions of these secretory proteins are currently under investigation which may lead us to a better understanding of other beneficial effects in the utilization of both CM conditions.  相似文献   

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