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1.
The dynamic rheological behavior of high density polyethylene (HDPE)/ultrahigh molecular weight polyethylene (UHMWPE) blends, low density polyethylene (LDPE)/UHMWPE blends and linear low density polyethylene (LLDPE)/ UHMWPE blends was measured in parallel plate rheometer at 200°C. The analysis of log-additivity rule, Cole-Cole plots and Han curves of the three series blends indicated that the LDPE/UHMWPE blends were miscible in the melt, while the HDPE/UHMWPE blends and LLDPE/UHMWPE blends showed phase separation. The DSC results of LLDPE/UHMWPE blends and HDPE/UHMWPE blends were consistent with the rheological properties, while for the thermal properties of LDPE/UHMWPE blends, results revealed three endothermic peaks, which indicated a liquid-solid phase separation in LDPE/UHMWPE blends. 相似文献
2.
C. E. Parker H. Iwahashi K. B. Tomer 《Journal of the American Society for Mass Spectrometry》1991,2(5):413-418
The 4-POBN[α-(4-pyridyl-l-oxide)-N-tert-butyl-nitrone] radical adducts of ethyl and pentyl radicals were determined by a combination of high performance liquid chromatography (HPLC) combined with electron paramagnetic resonance (EPR) with HPLC-electrospray (ESI)-mass spectrometry and HPLC-thermospray (TSP)-MS. The identifIcation of the peak corresponding to the spin-trapped radical was done by performing HPLC-EPR under the same chromatographic conditions as the HPLC-MS. The radical adducts could be determined by both techniques, even though for ESI only 12 μL/min of the total 1 mL/min HPLC flow rate could be directed into the ion source. 相似文献
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4.
In this study, Pt nanoparticles (NPs) were supported on reduced graphene oxide with the aid of disodium ethylenediamine-tetraacetate, where the Pt iona were initially attached to EDTA-functionalized graphene oxide (EDTA-GO) sheets and then the metal ion and the graphene oxide were reduced simultaneously by ethylene glycol. Electrochemical properties of the catalysts were studied by measuring cyclic voltammetries, and functional groups of the synthesized materials were investigated by Fourier transform infrared spectrometry. Average sizes and lattice parameters were measured by scanning electron microscopy, transmission electron microscopy images, and X-ray diffraction. The results showed that Pt NPs were successfully deposited on the EDTA-GO with the crystallite size of about 2.3 nm. The prepared catalysts demonstrated an enhanced tolerance towards CO poisoning, when EDTA-GO was used as supports. This suggests that EDTA plays a crucial role in the dispersion and electrocatalytic activity of the metal nanoparticles. 相似文献
5.
Masumi Villeneuve Mihoko Tanaka Mayuko Abe Hiroyasu Sakamoto Yoshiteru Hayami 《Colloid and polymer science》2014,292(9):2335-2348
A rigorous thermodynamic treatment appropriate for surface adsorption from mixed aqueous solution of alkali and polyprotic acid was derived. Those equations were applied to mixed aqueous solution/air systems of alkali metal hydroxide and FeIII complex with ethylenediamine- N, N, N′,N′-tetraacetate (Fe-EDTA). Surface density of each species arising from Fe-EDTA was separately evaluated, and thus, surface activity of Fe-EDTA was studied, especially its dependence on pH and how it is influenced by the counter cations. Fe-EDTA was positively adsorbed at the water/air interface at very low pHs and negatively at high pHs. The pH range of positive adsorption of Fe-EDTA with potassium ion, as a counter ion, was wider than that with sodium ion. Thus, potassium ion, a structure breaker, tended to smooth surface adsorption of Fe-EDTA at the water/air interface, whereas sodium ion, a structure maker, tended to withdraw Fe-EDTA from the interfacial region. 相似文献
6.
In the development of nanoparticle-based vaccine adjuvants, the interaction between nanoparticles (NPs) and the cells is a key factor. To control them, we focused on the relationship between the hydrophobicity of the side chains and the cell membrane. In this study, amphiphilic poly(γ-glutamic acid) (γ-PGA), using various types of hydrophobic side chains, was synthesized and used to prepare NPs for evaluating the membrane disruptive activity. When leucine ethyl ester (Leu), methionine ethyl ester (Met), or tryptophan ethyl ester (Trp) was grafted, each polymer formed monodispersed NPs at physiological conditions. Significantly, NPs composed of Leu and Trp showed a membrane disruptive activity at the endosomal environment (pH 5–6.5), while NPs composed of Met did not show. This might be due to the weak hydrophobicity of Met compared to that of Leu and Trp, which demonstrated that the interaction between NPs and cells could be controlled by designing the polymer compositions. 相似文献
7.
Mo Wang Huanshun Yin Zhengliang Fu Yunlong Guo Xinxu Wang Yunlei Zhou Shiyun Ai 《Journal of Solid State Electrochemistry》2014,18(10):2829-2835
MicroRNAs (miRNAs), a class of small endogenous nonprotein-coding RNAs, regulate a wide range of biological processes, and their abnormal expressions are related to the growth and development of plants. Thus, a simple, rapid, and highly sensitive assay for miRNA detection is of great significance. In this work, a label-free and ultrasensitive assay for miRNA detection using protein cage nanoparticles has been developed. Apoferritin-encapsulated Cu nanoparticles (Cu-apoferritin) could be immobilized on the electrode through special reaction between amino and carboxyl. Hybridization event between the probe DNA and the target miRNA-159a is confirmed by electrochemical oxidation signal after Cu released into the detection buffer by adjusting the pH. This assay is highly selective and sensitive with a low detection limit of 3.5 fM. Moreover, the developed method can even discriminate single-base mismatched strand between the complementary targets. The effect of abscisic acid on the expression level of miRNA-159a in Arabidopsis thaliana seeds was also investigated. 相似文献
8.
György Pátzay Yahya Ramadan Csilla Tonkó 《Journal of Radioanalytical and Nuclear Chemistry》2014,302(1):161-168
A novel direct method for the determination of EDTA in alkaline radioactive evaporator residue solution was developed and validated based on ion chromatography with suppressed conductimetric detection and anion exchange columns (A Supp 4, 4 mm × 250 mm and A Supp 5, 4 mm × 150 mm). The yttrium-EDTA complex resulted one single chromatographic peak in the eluent and allowed the correct determination of EDTA in an alkaline, high concentration radioactive waste water. Depending on coexisting substances, suitable eluent is 10.0 mM carbonate buffer/pH 10.6 or 10.75 (t R,Y–EDTA = 7.01 and 6.4 min, respectively). For 10.0 mM carbonate buffer/pH 10.6 and isocratic flow rate of 1.0 cm3/min, a linear calibration curve was obtained from 5 to 40 mg/dm3 (r > 0.999) EDTA. Good resolution was achieved from commonly coexisting anions (chloride, nitrite, nitrate, sulphate, phosphate, bromide and citrate). The developed simple ion chromatographic method was applied for the assay of EDTA in various radioactive alkaline solutions. 相似文献
9.
M. Reza Hormozi-Nezhad M. Azargun N. Fahimi-Kashani 《Journal of the Iranian Chemical Society》2014,11(5):1249-1255
We report herein the development of a highly sensitive colorimetric method for detection of d-Penicillamine using citrate-capped gold nanoparticles (AuNPs). This assay relies upon the distance-dependent of gold nanoparticles surface plasmon resonance band of gold nanoparticles. By replacing the thiol-containing chelator drug, d-Penicillamine, with citrate on the gold nanoparticles surface, a new peak appearing at a longer wavelength intensifies and shifts further to the red from the original peak position due to aggregation of gold nanoparticles which depends on ionic strength, gold nanoparticles and d-Penicillamine concentration. During this process, the plasmon band at 521 nm decreases gradually along with the formation of a new red-shifted band at 630 nm. The calibration curve which is derived from the ratio intensities of absorbance at longer wavelength (630 nm) to original wavelength (521 nm) displays a linear relation in the range of 5.0 × 10?6–3.0 × 10?4 M d-Penicillamine. Lower limit of detection for d-Penicillamine, at the signal-to-noise ratio of 3 (3σ), was 3.8 × 10?6 M. The developed methodology was successfully applied for the determination of d-Penicillamine in human urine and plasma. 相似文献
10.
M. S. Gaur Pramod Kumar Singh Asif Ali Rekha Singh 《Journal of Thermal Analysis and Calorimetry》2014,117(3):1407-1417
β-phase polyvinylidene fluoride (PVDF)–BaTiO3 nanocomposite samples have been prepared by solution mixing method. XRD data represent that the crystallinity of PVDF decreases with increase in loading level of BaTiO3 nanoparticles. DSC curve represents that the melting point of PVDF is lightly affected by loading concentration of BaTiO3. The morphology and microstructure of PVDF and PVDF embedded by BaTiO3 nanofillers were investigated by using inverted contrast microscopy (ICM) and scanning electron microscopy (SEM). FTIR interferrometry is proven that PVDF and BaTiO3 are not chemically interacting; therefore, interaction of BaTiO3 is van der Waals type of interaction. The thermally stimulated discharge current (TSDC) of PVDF and PVDF–BaTiO3 nanocomposites sample was characterized by single peak. The observed TSDC peak is discussed on the basis of dipolar and interfacial polarization. 相似文献
11.
Utpal Chowdhury Bhaben Tanti Parakkal Rethy Padma Raj Gajurel 《Applied biochemistry and biotechnology》2014,174(1):168-173
The utility of RAPD markers in assessing genetic diversity and phenetic relationships of six different species of Piper from Northeast India was investigated. Polymerase chain reaction (PCR) with four arbitrary 10-mer oligonucleotide primers applied to the six species produced a total of 195 marker bands, of which, 159 were polymorphic. On average, six RAPD fragments were amplified per reaction. In the UPGMA phenetic dendrogram based on Jaccard’s coefficient, the different accessions of Piper showed a high level of genetic variation. This study may be useful in identifying diverse genetic stocks of Piper, which may then be conserved on a priority basis. 相似文献
12.
Min Zhang Cuicui Ding Liulian Huang Lihui Chen Haiyang Yang 《Cellulose (London, England)》2014,21(5):3311-3322
Collagen/cellulose blended solutions with collagen/cellulose mass ratio (Col/Cel) of 0, 1/40, 1/20, 1/10 and 1/5 were prepared using [Emim]Ac as solvent. The interactions between the two polymers before and after regeneration were investigated. In steady shear flow, all of the experimental viscosity values were greater than those of the estimated values calculated from the log-additivity rule for each sample, suggesting interactions between the two polymers in solutions. All solutions exhibited shear thinning behavior and the flow curves could be described by Cross model. Zero shear viscosity (η 0) versus Col/Cel was examined and a linear increase (from 8.73 to 16.39 Pa·s) can be observed for η 0 as Col/Cel ≤ 1/10, while there was only a slight increase (from 16.39 to 18.42 Pa·s) in η 0 as Col/Cel increased to 1/5. Dynamic rheology results suggested the existence of aggregates in solution with Col/Cel = 1/10. Furthermore, the activation energy of solution was 84.5 kJ mol?1 as Col/Cel = 1/10, higher than that of cellulose solution (44.2 kJ mol?1). Regenerated films were prepared and characterized to trace back the interactions between the two polymers in [Emim]Ac. Fourier transform infrared spectroscopy indicated the hydrogen-bond interaction between collagen and cellulose in films. The denaturation temperature of collagen in films with Col/Cel ≤ 1/10 could be improved, but it was decreased with the increase of collagen content, and finally was reduced to be close to that of collagen as Col/Cel = 1/5. The features of dynamic mechanical analysis for films were indicative of the lack of homogeneity between collagen and cellulose as Col/Cel = 1/5. Atomic force microscopy images further confirmed the phase-separation when Col/Cel = 1/5. 相似文献
13.
G. M. Magomedov S. Yu. Khashirova F. K. Ramazanov Z. L. Beslaneeva A. K. Mikitaev 《Polymer Science Series A》2014,56(5):652-661
Nanocomposite materials composed of HDPE and new guanidine-containing organoclays have been investigated. The basic changes in the relaxation properties of HDPE after the addition of guanidine-containing organoclays that vary in composition and content have been found. It has been shown that, depending on their structures and affinities for the polymer, guanidine-containing modifiers of montmorillonite have different effects on the structure and relaxation properties of the polymer. 相似文献
14.
Ling Chen Baoying Xie Lei Li Weizhong Jiang Yang Zhang Jin Fu Guoxian Guan Yan Qiu 《Chromatographia》2014,77(17-18):1241-1247
Free fatty acids (FFAs), major cellular metabolites, play an important role during tumor pathogenesis. Enhanced de novo fatty acid synthesis in tissues is a characteristic feature of cancer. Therefore, measurement of FFA concentration in biological samples is beneficial for cancer research and clinical diagnosis. Herein, a rapid, stable, and sensitive detection methodology was established to simultaneously quantify 22 FFAs using high-performance liquid chromatography/electrospray ionization tandem mass spectrometry (HPLC/ESI–MS/MS). The HPLC–MS/MS system was run in negative ion mode for 15 min using multiple reaction monitoring. The lipids were extracted from colon tissues of colon cancer patients and then injected into the HPLC–MS/MS system for analysis. Colon samples were analyzed by inter-day repeatability and intra-day repeatability, with less than 5 % deviation for most fatty acids. This approach is successful to determine low picogram concentrations of each FFA molecule using milligrams of tissue, and provides a promising method for FFA microanalysis in clinical samples. 相似文献
15.
Rong-li Zhang Jia-di Sun Jing Luo Sheng Xu Xiao-ya Liu 《Colloid and polymer science》2014,292(9):2295-2302
Poly(γ-glutamic acid) (γ-PGA) has been widely used in many applications due to its excellent biodegradability, biocompatibility, and nontoxic properties. In this study, we synthesized a novel photo-sensitive amphiphilic poly(γ-glutamic acid)-graft-7-amino-4-methylcoumarin (AMC-γ-PGA) copolymer, which can self-assemble into nanoparticles (NPs) via solvent exchange method. The resultant AMC-γ-PGA NPs showed sensitivity to UV irradiation, pH, and ionic strength, owing to the presence of coumarin groups and carboxyl groups on the AMC-γ-PGA copolymer. The AMC-γ-PGA NPs were then used as a matrix to entrap hemoglobin (Hb). The obtained Hb@AMC-γ-PGA nanocomposites were cast on the electrode to form a nanocomposite film, which was then photo-crosslinked by UV irradiation to lock and immobilize Hb. Cyclic voltammetry (CV) experiment showed that the Hb@AMC-γ-PGA-nanocomposite-modified electrode exhibited good electrochemical catalytic activity for H2O2, implying that the AMC-γ-PGA NPs provided a favorable microenvironment for Hb and preserved the bioactivity of Hb. In addition, the leakage of Hb was efficiently avoided with the photo-crosslinking of the AMC-γ-PGA NPs. The biocompatible photo-sensitive AMC-γ-PGA NPs provided an excellent platform for immobilization of Hb on electrode. 相似文献
16.
Ferid Abidi Neyssene Aissaoui Jean-Marc Chobert Thomas Haertlé Mohamed Nejib Marzouki 《Applied biochemistry and biotechnology》2014,174(1):186-205
In the present study, purification and properties of an extracellular neutral serine protease from the fungus Penicillium italicum and its potential application as an antioxidant peptides producer are reported. The protease was purified to homogeneity using ammonium sulfate precipitation, Sephacryl S-200 gel filtration, diethylaminoethanol (DEAE)-Sepharose ion exchange chromatography, and TSK-HPLC gel filtration with a 10.2-fold increase in specific activity and 25.8 % recovery. The purified enzyme appeared as single protein band with a molecular mass of 24 kDa in sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The optimum pH and temperature for the proteolytic activity were pH 7.0 and 50 °C, respectively. The enzyme was stable in the pH range of 6.0–9.0. The protease was activated by divalent cations such as Ca2+ and Mg2+. Complete inhibition of the purified enzyme by phenylmethylsulfonyl fluoride confirmed that the protease was of serine-type. The purified enzyme revealed high stability and relatively broad specificity. Scorpaena notata muscle protein hydrolysates prepared using purified serine protease (protease from P. italicum (Prot-Pen)) showed good in vitro antioxidative activities. The antioxidant activities of Scorpaena muscle protein hydrolyzed by Prot-Pen (SMPH-PP) were evaluated using various antioxidant assays: 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, reducing power, ferrous chelating activity, and DNA nicking assay. SMPH-PP showed varying degrees of antioxidant activity and almost the same strongest protection against hydroxyl radical induced DNA breakage. 相似文献
17.
JeongWoo Kang Su-Jeong Park Hae-Chul Park Vinayakumar Gedi ByungJae So Kwang-Jick Lee 《Applied biochemistry and biotechnology》2014,174(1):1-5
Nonsteroidal anti-inflammatory drugs (NSAIDs) are the group of drugs having the therapeutic efficacy of analgesic and antipyretic. To detect health-threatening residues of NSAIDs, a fast and easy multiresidue method based on liquid chromatography tandem mass spectrometry (LC-MS/MS) was described. Ten NSAIDs were extracted from the tissues using 2 mL of acetonitrile and 0.1 mL of 2 mM ammonium formate in distilled water. After clean-up using C18 sorbent, it was evaporated under nitrogen, reconstituted with 1 mL distilled water and analyzed by LC-MS/MS. The method was validated based on guideline for residue testing laboratory. Furthermore, the method has also been applied successfully to detect ten NSAIDs from bovine, porcine, and chicken liver tissues. In a total of 315 liver samples tested, acetylic salicylic acid was detected from 28 porcine and 2 chicken liver tissues at levels of 13?~?576 and 50?~?53 ng/g, respectively. Subsequently, paracetamol was detected in 15 porcine liver tissues with a detection levels of 28?~?381 ng/g. Phenylbutazone and its metabolite, oxyphenylbutazone, were detected at 247 and 15 ng/g range in one of the bovine liver tissue, respectively. 相似文献
18.
Hongliang Wang Ganghua Tang Kongzhen Hu Tingting Huang Xiang Liang Sijin Li Zhifang Wu 《Journal of Radioanalytical and Nuclear Chemistry》2014,302(1):273-280
Small-molecular probe 18F-labeled bis(zinc(II)-dipicolylamine) complex (18F-FB-DPAZn2) was evaluated for PET imaging of sterile inflammation. In comparison with 18F-2-deoxy-β-d-glucose (18F-FDG), 18F-radiolabeled Annexin V (18F-FB-Annexin V) showed rapid clearance of radioactivity from the kidney and low uptake in most tissues. Both the lower radioactivity accumulation in brain and heart and the higher uptakes in the lung, liver, and intestine were observed for the biodistribution of 18F-FB-DPAZn2. In PET imaging, 18F-FDG showed significantly higher tumor and inflammation uptake than did of 18F-FB-DPAZn2 and 18F-FB-Annexin V in the S-180 fibrosarcoma mouse model and sterile inflammation mouse model. Both 18F-FB-DPAZn2 and 18F-FB-Annexin V performed the specifically localization in inflammation, and the ratios of inflammatory lesion-to-muscle and tumor-to-muscle were 1.83 ± 0.20 and 0.90 ± 0.12 (P < 0.05) for 18F-FB-DPAZn2, and 1.51 ± 0.14 and 1.21 ± 0.12 (P > 0.05) for 18F-FB-Annexin V, respectively. Terminal deoxynucleotide end-labeling (TUNEL) assays performed on the dissected tissues showed the significantly more TUNEL-positive nuclei in the inflammatory muscle than in tumor and normal muscle, and these TUNEL results correlated with the uptake of 18F-FB-DPAZn2 in dissected tissues. Biodistribution and PET imaging studies showed that the 18F-FB-DPAZn2 is suitable for imaging sterile inflammation in vivo and is capable of the differentiating tumor from inflammation. 相似文献
19.
Debipreeta Bhowmik Franco Buzzetti Gaetano Fiorillo Laura Franchini Tanjia Monir Syeda Paolo Lombardi Gopinatha Suresh Kumar 《Journal of Thermal Analysis and Calorimetry》2014,118(1):461-473
The interaction of 13- monophenylalkyl and diphenylalkyl berberine analogs with tRNAphe has been investigated using various thermochemical techniques like thermal melting, isothermal titration calorimetry, and differential scanning calorimetry experiments. Thermal melting studies revealed that all the analogs stabilized the tRNAphe better than berberine. The binding affinity for the analogs was of the order of 105 M?1. Calorimetry results suggested that the binding of these analogs was predominantly entropy driven with small negative enthalpy contribution to the standard molar Gibbs energy. The temperature dependence of the standard molar enthalpy changes yielded negative values of standard molar heat capacity changes for the complexation revealing substantial hydrophobic contribution in the RNA binding of these analogs. An enthalpy–entropy compensation behavior was also seen in all the systems. The diphenylalkyl analogs were found to be more effective tRNAphe binders compared to the monophenylalkyl analogs. The utility of the present work lies in understanding the structural and energetic aspects of the interaction of these berberine analogs with tRNA, which may be useful in the development of RNA-targeted drugs. 相似文献
20.
A. M. Flank R. C. Karnatak C. Blancard J. M. Esteva P. Lagarde J. P. Connerade 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1991,21(4):357-366
TheK absorption edge of Si in matrix isolated SiO molecular clusters was studied for various dilutionsR(Ar/SiO). The spectra from the clusters at different dilutions show a dramatic evolution in their relative intensity. Two types of spectral features from Si atoms present in the clusters could be detected in the spectra. The first is due to the Si atoms which are tetrahedrally coordinated to Si and O atoms responsible for the presence of different Si oxidation states. The Si+, Si3+ and Si4+ oxidation states in SiO clusters and in bulk were readily identified. The Si2+ oxidation state whose abundance in SiO clusters is predicted by structural considerations is not clearly observed. The second type of feature, whose intensity decreases with the dilution R, can be attributed to the presence of Si atoms possessing unsaturated bonds. In order to explain this the clustering of 4–6 SiO molecules is simulated to yield different tetrahedral bonding microstructures in which the well coordinated as well as under coordinated Si atoms are present. The behaviour of the spectral features resulting from these microstructures is discussed. 相似文献