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991.
Y. C. Wong D. W. M. Sin Y. C. Yip L. Valiente A. Toervenyi J. Wang G. Labarraque P. Gupta D. Soni Surmadi E. Hwang C. Yafa O. Cankur E. Uysal G. Turk R. Huertas 《Accreditation and quality assurance》2009,14(3):151-158
A Comité Consultatif pour la Quantité de Matière (CCQM) inter-laboratory comparison program, CCQM-P97, for the analysis of
cadmium and lead in Herba Demodii Styracifolii was organized by the Hong Kong Government Laboratory. The objective of the program was to establish comparability of trace
metals analysis in herbal matrices amongst the participating national metrology institutes. The arithmetic mean values of
the 13 participants were 0.3186 mg kg−1 (RSD = 11.3%) and 1.650 mg kg−1 (RSD = 11.0%) for cadmium and lead, respectively. The participants using double-isotope dilution mass spectrometry technique
for their quantification were found to provide similar mean values to those of non-isotope dilution mass spectrometry users.
The observation indicated that trace metal analysis in herbal matrices was not method-dependent, but the use of the highest
metrological IDMS approach gave a better precision than other routine calibration methods. 相似文献
992.
The influence of the negative substrate bias on the interfacial and microstructural characteristics of nanocrystalline silicon (nc-Si) thin films was deposited by hot wire chemical vapor deposition (HWCVD). Structural characterization of nc-Si films was performed by small angle X-ray diffraction (SAXRD), Raman spectroscopy, X-ray reflectivity (XRR) and field emission scanning electron microscopy (FESEM). Crystalline fraction and crystallite size increases from 61.31 to 74.13% and 13.3 to 21.6 nm, respectively, with an increasing negative bias from 0 to ?200 V. Furthermore, the deposition rate of nc-Si films increases from 25 to 68 nm/min by increase of negative substrate bias from 0 to ?200 V. 相似文献
993.
Mi-Hyun Park Soo Heon Kwak Kwang Joong Kim Min Jin Go Hye-Ja Lee Kyung-Seon Kim Joo-Yeon Hwang Kuchan Kimm Young-Min Cho Hong Kyu Lee Kyong Soo Park Jong-Young Lee 《Experimental & molecular medicine》2013,45(2):e7
The incidence of type 2 diabetes is rising rapidly because of an increase in the incidence of being overweight and obesity. Identification of genetic determinants for complex diseases, such as type 2 diabetes, may provide insight into disease pathogenesis. The aim of the study was to investigate the shared genetic factors that predispose individuals to being overweight and developing type 2 diabetes. We conducted genome-wide linkage analyses for type 2 diabetes in 386 affected individuals (269 sibpairs) from 171 Korean families and association analyses with single-nucleotide polymorphisms of candidate genes within linkage regions to identify genetic variants that predispose individuals to being overweight and developing type 2 diabetes. Through fine-mapping analysis of chromosome 4q34-35, we detected a locus potentially linked (nonparametric linkage 2.81, logarithm of odds 2.27, P=6 × 10−4) to type 2 diabetes in overweight or obese individuals (body mass index, BMI⩾23 kg m−2). Multiple regression analysis with type 2 diabetes-related phenotypes revealed a significant association (false discovery rate (FDR) P=0.006 for rs13144140; FDR P=0.002 for rs6830266) between GPM6A (rs13144140) and BMI and waist–hip ratio, and between NEIL3 (rs6830266) and insulin level from 1314 normal individuals. Our systematic search of genome-wide linkage and association studies, demonstrate that a linkage peak for type 2 diabetes on chromosome 4q34-35 contains two type 2 diabetes-related genes, GPM6A and NEIL3. 相似文献
994.
Dr. Fadlilatul Taufany Dr. Chun‐Jern Pan Feng‐Ju Lai Dr. Hung‐Lung Chou Loka Subramanyam Sarma Dr. John Rick Jhih‐Min Lin Dr. Jyh‐Fu Lee Dr. Mau‐Tsu Tang Prof. Bing‐Joe Hwang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(3):905-915
A controlled composition‐based method—that is, the microwave‐assisted ethylene glycol (MEG) method—was successfully developed to prepare bimetallic PtxRu100?x/C nanoparticles (NPs) with different alloy compositions. This study highlights the impact of the variation in alloy composition of PtxRu100?x/C NPs on their alloying extent (structure) and subsequently their catalytic activity towards the methanol oxidation reaction (MOR). The alloying extent of these PtxRu100?x/C NPs has a strong influence on their Pt d‐band vacancy and Pt electroactive surface area (Pt ECSA); this relationship was systematically evaluated by using X‐ray absorption (XAS), scanning electron microscopy (SEM) coupled with energy dispersive X‐ray spectroscopy (EDX), transmission electron microscopy (TEM), density functional theory (DFT) calculations, and electrochemical analyses. The MOR activity depends on two effects that act in cooperation, namely, the number of active Pt sites and their activity. Here the number of active Pt sites is associated with the Pt ECSA value, whereas the Pt‐site activity is associated with the alloying extent and Pt d‐band vacancy (electronic) effects. Among the PtxRu100?x/C NPs with various Pt:Ru atomic ratios (x=25, 50, and 75), the Pt75Ru25/C NPs were shown to be superior in MOR activity on account of their favorable alloying extent, Pt d‐band vacancy, and Pt ECSA. This short study brings new insight into probing the synergistic effect on the surface reactivity of the PtxRu100?x/C NPs, and possibly other bimetallic Pt‐based alloy NPs. 相似文献
995.
Multivalent Polymer Nanocomplex Targeting Endosomal Receptor of Immune Cells for Enhanced Antitumor and Systemic Memory Response 下载免费PDF全文
Sun‐Young Kim Min Beom Heo Dr. Geum‐Sook Hwang Youngae Jung Dr. Do Yeol Choi Prof. Dr. Yeong‐Min Park Prof. Dr. Yong Taik Lim 《Angewandte Chemie (International ed. in English)》2015,54(28):8139-8143
We have designed and synthesized linear polymer‐based nanoconjugates and nanocomplexes bearing multivalent immunostimulatory ligands and also demonstrated that the synthetic multivalent nanocomplexes led to an enhanced stimulation of immune cells in vitro and antitumor and systemic immune memory response in vivo. We have developed hyaluronic acid (HA)‐based multivalent nanoconjugates and nanocomplexes for enhanced immunostimulation through the combination of multivalent immune adjuvants with CpG ODNs (as a TLR9 ligand) and cationic poly(L ‐lysine) (PLL; for the enhancement of cellular uptake). The multivalent HA‐CpG nanoconjugate efficiently stimulated the antigen‐presenting cells and the multivalent PLL/HA‐CpG nanocomplex also led to an enhanced cellular uptake as well as continuous stimulation of endosomal TLR9. The mice vaccinated with dendritic cells treated with the multivalent nanocomplex exhibited tumor growth inhibition as well as a strong antitumor memory response. 相似文献
996.
Mussel‐Inspired Protein Nanoparticles Containing Iron(III)–DOPA Complexes for pH‐Responsive Drug Delivery 下载免费PDF全文
Dr. Bum Jin Kim Hogyun Cheong Dr. Byeong Hee Hwang Prof. Hyung Joon Cha 《Angewandte Chemie (International ed. in English)》2015,54(25):7318-7322
A novel bioinspired strategy for protein nanoparticle (NP) synthesis to achieve pH‐responsive drug release exploits the pH‐dependent changes in the coordination stoichiometry of iron(III)–3,4‐dihydroxyphenylalanine (DOPA) complexes, which play a major cross‐linking role in mussel byssal threads. Doxorubicin‐loaded polymeric NPs that are based on FeIII–DOPA complexation were thus synthesized with a DOPA‐modified recombinant mussel adhesive protein through a co‐electrospraying process. The release of doxorubicin was found to be predominantly governed by a change in the structure of the FeIII–DOPA complexes induced by an acidic pH value. It was also demonstrated that the fabricated NPs exhibited effective cytotoxicity towards cancer cells through efficient cellular uptake and cytosolic release. Therefore, it is anticipated that FeIII–DOPA complexation can be successfully utilized as a new design principle for pH‐responsive NPs for diverse controlled drug‐delivery applications. 相似文献
997.
Gd‐DTPA‐Dopamine‐Bisphytanyl Amphiphile: Synthesis,Characterisation and Relaxation Parameters of the Nanoassemblies and Their Potential as MRI Contrast Agents 下载免费PDF全文
Abhishek Gupta Dr. Scott A. Willis Lynne J. Waddington Dr. Tim Stait‐Gardner Dr. Liliana de Campo Prof. Dennis W. Hwang Dr. Nigel Kirby Prof. William S. Price Dr. Minoo J. Moghaddam 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(40):13950-13960
Here, a new amphiphilic magnetic resonance imaging (MRI) contrast agent, a GdIII‐chelated diethylenetriaminepentaacetic acid conjugated to two branched alkyl chains via a dopamine spacer, Gd‐DTPA‐dopamine‐bisphytanyl (Gd‐DTPA‐Dop‐Phy), which is readily capable of self‐assembling into liposomal nanoassemblies upon dispersion in an aqueous solution, is reported. In vitro relaxivities of the dispersions were found to be much higher than Magnevist, a commercially available contrast agent, at 0.47 T but comparable at 9.40 T. Analysis of variable temperature 17O NMR transverse relaxation measurements revealed the water exchange of the nanoassemblies to be faster than that previously reported for paramagnetic liposomes. Molecular reorientation dynamics were probed by 1H NMRD profiles using a classical inner and outer sphere relaxation model and a Lipari–Szabo “model‐free” approach. High payloads of GdIII ions in the liposomal nanoassemblies made solely from the Gd‐DTPA‐Dop‐Phy amphiphiles, in combination with slow molecular reorientation and fast water exchange makes this novel amphiphile a suitable candidate to be investigated as an advanced MRI contrast agent. 相似文献
998.
Adsorptive Separation of Acetylene from Light Hydrocarbons by Mesoporous Iron Trimesate MIL‐100(Fe) 下载免费PDF全文
Sukyung Lee Kyoung Ho Cho Dr. Young Kyu Hwang Prof. Dr. Marco Daturi Prof. Chul‐Ho Jun Prof. Dr. Rajamani Krishna Prof. Dr. Jong‐San Chang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(50):18431-18438
A reducible metal–organic framework (MOF), iron(III) trimesate, denoted as MIL‐100(Fe), was investigated for the separation and purification of methane/ethane/ethylene/acetylene and an acetylene/CO2 mixtures by using sorption isotherms, breakthrough experiments, ideal adsorbed solution theory (IAST) calculations, and IR spectroscopic analysis. The MIL‐100(Fe) showed high adsorption selectivity not only for acetylene and ethylene over methane and ethane, but also for acetylene over CO2. The separation and purification of acetylene over ethylene was also possible for MIL‐100(Fe) activated at 423 K. According to the data obtained from operando IR spectroscopy, the unsaturated FeIII sites and surface OH groups are mainly responsible for the successful separation of the acetylene/ethylene mixture, whereas the unsaturated FeII sites have a detrimental effect on both separation and purification. The potential of MIL‐100(Fe) for the separation of a mixture of C2H2/CO2 was also examined by using the IAST calculations and transient breakthrough simulations. Comparing the IAST selectivity calculations of C2H2/CO2 for four MOFs selected from the literature, the selectivity with MIL‐100(Fe) was higher than those of CuBTC, ZJU‐60a, and PCP‐33, but lower than that of HOF‐3. 相似文献
999.
Imgon Hwang Seulgi So Mohamed Mokhtar Abdelmohsen Alshehri Shaeel A. Al‐Thabaiti Dr. Anca Mazare Prof. Patrik Schmuki 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(25):9204-9208
In the present work we report significant enhancement of the photoelectrochemical properties of self‐ organized TiO2 nanotubes by a combined “de‐coring” of classic nanotubes followed by an appropiate TiCl4 treatment. We show that, except for the expected particle decoration, a key effect of the TiCl4 treatment is that the electron transport characteristics in TiO2 nanotubes can be drastically improved, for example, we observe an enhancement of up to 70 % in electron‐transport times. 相似文献
1000.
Bridging cysteine ligands of the Cu(A) center in an engineered Cu(A) azurin were replaced with serine, and the variants (Cys116Ser and Cys112Ser Cu(A) azurin) were characterized by mass spectrometry, as well as UV-vis and electron paramagnetic resonance (EPR) spectroscopic techniques. The replacements resulted in dramatically perturbed spectroscopic properties, indicating that the cysteines play a critical role in maintaining the structural integrity of the Cu center. The replacements at different cysteine residues resulted in different perturbations, even though the two cysteines are geometrically symmetrical in the primary coordination sphere with respect to the two copper ions. The Cys112Ser variant contains two distinct type 2 copper centers, while the Cys116Ser variant has one type 1 copper center with slight tetragonal distortion. Both the UV-vis and EPR spectra of the Cys116Ser variant change with pH, and the pK(a) of the transition is 6.0. A type 1 copper EPR spectrum with A(||) = 26 G was obtained at pH 7.0, while a type 2 copper EPR spectrum with A(||) = 140 G was found at pH 5.0. Interestingly, lowering the temperature from 290 to 85 K resulted in conversion of the Cys116Ser variant from a type 1 copper center to a type 2 copper center, suggesting rearrangement of the ligand around the copper or binding of an exogenous ligand at low temperature. This difference in mutation effects at different cysteines may be due to different constraints exerted on the two cysteines by hydrogen-bonding patterns in the ligand loop. 相似文献