Thermomechanical analysis (TMA) can be used as a sensitive tool to follow crystallization behavior in non-crystalline materials. Newly developed method is based on slowing down of sample deformation caused by viscous flow above the glass transition due to macroscopic crystal growth. It is shown that a typical TMA sigmoidal curve reasonably well corresponds to direct measurement of crystal growth kinetics by means of optical microscopy. The method has been used to study crystallization kinetics in Ge38S62 glass. The TMA measurement is able to detect earlier stages of crystallization than obtained by differential scanning calorimetry measurement. The activation energy obtained from the shift of extrapolated end of TMA curve with heating rate (E = 263 ± 7 kJ mol?1) is similar to the activation energy of ??-GeS2 crystal growth in Ge38S62 glass (EG = 247 ± 23 kJ mol?1) obtained from direct optical microscopy measurements. 相似文献
The possibility of incorporating a stimuli-responsive microgel into a silica matrix by the sol–gel method was studied. This
method allows the preparation of a novel class of functional finishes for textile material modification, which is aimed at
the creation of simultaneous stimulus-responsive behaviour and functional protective properties. Using a pad-dry-cure method,
a thermo- and pH-responsive microgel (PNCS) based on poly-(N-isopropylacrylamide) (poly-NiPAAm) and chitosan was embedded into a silica matrix on a previously activated polyester (PES)
fabric. The matrix was composed of a model sol–gel precursor, vinyltrimethoxysilane (VTMS), in combination with hydrophilic
fumed silica nanoparticles (SiO2). Functionalized PES fabric samples were characterised by determining the morphological and chemical properties using scanning
electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The
stimuli (temperature and pH) responsiveness of the functionalized PES fabric was established by measuring its porosity, wicking
ability, moisture content, drying rate, water vapour transmission rate and water uptake. In order to assess the washing fastness
of the surface modifying systems, the tests were done before and after five consecutive washings. The results showed that
sol–gel technology is an appropriate method for the incorporation of PNCS microgel on PES fibre surface. Because of the elasticity
of the sol–gel matrix, the VTMS/SiO2 polysiloxane film had no adverse influence on the swelling/deswelling effect of the PNCS microgel, thus retaining and even
enhancing its stimulus response. 相似文献
Biodistribution, pharmacokinetics, and efficacy of prostate‐cancer‐targeted HPMA copolymer/DTX conjugates are evaluated in nude mice bearing prostate cancer C4‐2 xenografts. PSMA‐specific monoclonal antibodies 3F/11 are used as the targeting moiety. Control conjugates contain either non‐specific IgG or no IgG. The ratios of tumor accumulation to total background organs (heart, lung, kidney, liver, spleen and blood) accumulation increase substantially with time for the targeted conjugate, and the ratio at 48 h is 7‐fold higher than that at 6 h. Preliminary evaluation of the efficacy of the conjugates in vivo show tumor growth inhibition for all HPMA copolymer/DTX conjugates.
The incorporation of lipid moieties into synthetic peptide vaccines has been demonstrated to self-adjuvant otherwise poorly immunogenic peptides, whereas carbohydrates have emerged to be advantageous carriers for assembling these peptides. With the advent of an efficient native chemical ligation method, which is compatible with both peptides and carbohydrates, we have developed highly pure self-adjuvanting tetravalent group A streptococcal vaccine candidates assembled on carbohydrate templates. The utility of chemoselective ligation has overcome difficulties in the synthesis and purification of branched high molecular weight peptides. Circular dichroism measurements provided the evidence of α-helix formation of the assembled peptide epitopes, which may have impact on their immunogenicity. 相似文献
Let A(z) be a given polynomial n×n matrix with det A(z)=1. It is shown that there exists an entire matrix-valued function X(z) such that expX(z)=A(z) if and only if the eigenvalues of A(z) are independent of z. 相似文献
In cyclic voltammetry (at a mercury drop electrode) guanine residues in the polynucleotide chain give a characteristic anodic peak at potentials close to ?0.3 V (vs. saturated calomel electrode). At low concentrations of polynucleotide, this peak can be enhanced substantially if the potential scan is preceded by adsorptive preconcentration of the polynucleotide at the hanging mercury drop electrode. With accumulation times shorter than 10 min at pH 6.8, the limit of detection of a single-stranded polynucleotide is < 0.1 μg ml?1. The peak of double-helical deoxyribonucleic acid (DNA) is considerably lower than that of single-stranded DNA under the same conditions, which can be exploited to determine low concentrations of single-stranded DNA in the presence of double-stranded DNA. 相似文献
Novel polymeric delivery systems for the photosensitizer mesochlorin e6 (Mce6) were synthesized to overcome problems of systemic toxicity. A disulfide bond was included to allow for quick release of Mce6 from the N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer backbone once internalized in tumor tissue. The synthesized conjugates demonstrated a time-dependent reductive cleavage with an accompanying increase in the quantum yield of singlet oxygen generation on exposure to DTT. Quicker release kinetics and a higher cytotoxicity in SKOV-3 human ovarian carcinoma cells were obtained as compared to polymer conjugate with a proteolytically cleavable GFLG spacer. These novel conjugates hold promise as clinically relevant drug delivery systems for photodynamic therapy of cancer. 相似文献
A method for the measurement of ascorbic acid using HPLC with UV detection and investigation into the protein precipitation techniques with regard to stability and recovery are described. The effectiveness of various protein precipitants was tested. Stability of ascorbic acid samples for analysis was investigated over 10 h. Ascorbic acid samples extracted with metaphosphoric acid were stable on a cooled autosampler (4 degrees C) for at least 10 h (with a decline of 1.8% for ascorbic acid solution and 2.8% for plasma). Perchloric acid as protein precipitant for ascorbic acid was unsuitable (with a decline of 36.0% for ascorbic acid solution and 7.3% for plasma). Analytical performance of this method is satisfactory. The intra- and interassay coefficients of variation were 2.1% (n = 10) and 5.8% (n = 12), respectively. The calibration curve was linear with the tested range of 2.0-250.0 micromol/L. The recovery was 96.1% with CV = 4.8% (n = 6) and the LOD was 3 micromol/L. The preliminary reference ranges of ascorbic acid in a group of blood donors are 50.8 +/- 22.4 micromol/L. This assay is a highly sensitive and reproducible HPLC method for the determination of ascorbic acid in human plasma. 相似文献
A method for the determination and quantification of collagen types I-V in rat tissues has been developed. This method is based on collagen fragmentation by cyanogen bromide followed by trypsin digestion. After that, HPLC-MS/MS (HPLC coupled to an IT mass spectrometer) analyses of the resulting peptide mixtures (peptide maps) were performed. Specific peptides for each collagen type were selected. According to online databases, these peptides are present in human, bovine, and rat collagens. As a result, this method can be potentially applied to other species' tissues as well, such as human tissues, and provides a universal and simple method of quantifying collagen types. The applicability of this method for analyzing collagen types was demonstrated on rat tissues (skin, tendon, and aorta). 相似文献
Samples of Mg4Al2 layered double hydroxide (LDH) intercalated with p-methylbenzoate and p-bromobenzoate anions were prepared by reconstruction of calcined LDH. The interlayer arrangement of guests was investigated by molecular modeling combined with X-ray powder diffraction and thermogravimetry. Molecular modeling was carried out in a Cerius2 modeling environment. In both structures the guest anions adopt a nearly perpendicular arrangement of their long axis with respect to the host layers and they are anchored to the OH groups of the layers through COO* groups via electrostatic interactions. Molecular modeling revealed that both structures of the intercalates exhibit a certain disorder of guest anions in the interlayer space. In the case of LDH-p-methylbenzoate intercalate the anions tend to be situated in disordered rows, and the LDH-p-bromobenzoate intercalate exhibits a total disorientation of guest anions. A good agreement between calculated and measured X-ray diffraction patterns and between experimental and calculated basal spacings was obtained. In the LDH-p-methylbenzoate intercalate d exp=16.96 A and d calc=16.97 A, and in the case of LDH-p-bromobenzoate intercalate d exp=17.19 A and d calc=17.40 A. 相似文献