Novel silicon-based alternating copolymers: synthesis,photophysical properties,and tunable EL colors

We synthesized novel silicon-based alternating copolymers for tunable electroluminescent (EL) colors by Heck synthetic method. Their thermal, photophysical and electroluminescent properties were studied. Most of them exhibited a blue-green EL color at the operating voltage of lower than 12 V. Unusually, we observed the white EL color from a EL device based on SiPhPVK. From photophysical studies and the time-resolved PL spectroscopies, it might be attributed to the formation of stabilized excited state in SiPhPVK. Furthermore, in order to reduce the operating voltage of their LED with increasing the electron affinity of the main chain in silicon-based alternating copolymers, we synthesized the silicon-based copolymers containing electron transporting oxadiazole units in main chain. We also studied their photophysical and electroluminescent properties.     

Aurones and Flavonols from Coreopsis lanceolata L. Flowers and Their Anti-Oxidant,Pro-Inflammatory Inhibition Effects,and Recovery Effects on Alloxan-Induced Pancreatic Islets in Zebrafish

(1) Background: Many flavonoids have been reported to exhibit pharmacological activity; a preparatory study confirmed that Coreopsis lanceolata flowers (CLFs) contained high flavonoid structure content; (2) Methods: CLFs were extracted in aqueous methanol (MeOH:H₂O = 4:1) and fractionated into acetic ester (EtOAc), normal butanol (n-BuOH), and H₂O fractions. Repeated column chromatographies for two fractions led to the isolation of two aurones and two flavonols; (3) Results: Four flavonoids were identified based on a variety of spectroscopic data analyses to be leptosidin (1), leptosin (2), isoquercetin (3), and astragalin (4), respectively. This is the first report for isolation of 2–4 from CLFs. High-performance liquid chromatography (HPLC) analysis determined the content levels of compounds 1–4 in the MeOH extract to be 2.8 ± 0.3 mg/g (1), 17.9 ± 0.9 mg/g (2), 3.0 ± 0.2 mg/g (3), and 10.9 ± 0.9 mg/g (4), respectively. All isolated compounds showed radical scavenging activities and recovery activities in Caco-2, RAW264.7, PC-12, and HepG2 cells against reactive oxygen species. MeOH extract, EtOAc fraction, and 1–3 suppressed NO formation in LPS-stimulated RAW 264.7 cells and decreased iNOS and COX-2 expression. Furthermore, all compounds recovered the pancreatic islets damaged by alloxan treatment in zebrafish; (4) Conclusions: The outcome proposes 1–4 to serve as components of CLFs in standardizing anti-oxidant, pro-inflammatory inhibition, and potential anti-diabetic agents.     

In vivo study on the protection of indole‐3‐carbinol (I3C) against the mouse acute alcoholic liver injury by micro‐Raman spectroscopy

Micro‐Raman spectroscopy (MRS) was utilized for the first time to evaluate the effect of indole‐3‐carbinol (I3C) on acute alcoholic liver injury in vivo. In situ Raman analysis of tissue sections provided distinct spectra that can be used to distinguish alcoholic liver injury as well as ethanol‐induced liver fibrosis from the normal state. Sixteen mice with liver diseases including acute liver injury and chronic liver fibrosis, and eight mice with normal liver tissues, and eight remedial mice were studied employing the Raman spectroscopic technique in conjunction with biomedical assays. The biochemical changes in mouse liver tissue when liver injury/fibrosis occurs such as the loss of reduced glutathione (GSH), and the increase of collagen (α‐helix protein) were observed by MRS. The intensity ratio of two Raman peaks (I₁₄₅₀/I₆₆₆) and in combination with statistical analysis of the entire Raman spectrum was found capable of classifying liver tissues with different pathological features. Raman spectroscopy therefore is an important candidate for a nondestructive in vivo screening of the effect of drug treatment on liver disease, which potentially decreases the time‐consuming clinical trials. Copyright © 2008 John Wiley & Sons, Ltd.     

Temperature-dependent photoluminescence of dimethylzinc-treated ZnSe/ZnS quantum dots

Temperature-dependent photoluminescence (PL) measurements were carried out ZnSe/ZnS quantum dots (QDs) grown with post-growth interruption under a dimethylzinc (DMZn) flow. The PL spectra showed sigmoidal peak shifts and V-shaped full width at half maximum (FWHM) variations with increasing temperature, which strongly suggest that the QD structure of ZnSe/ZnS is quite similar to that of other material systems grown in the Stranski–Krastanov mode. Apparent differences are revealed as a consequence of DMZn treatment: (i) the PL spectra of ZnSe/ZnS QDs showed peaks at higher energies and persisted up to 300 K, and(ii) the minimum points of the V-shaped FWHM appear at a higher temperature compared to H₂-purged ZnSe/ZnS QDs. Experimental results demonstrate the enhancement of localization energy.     

Synthesis and spectroscopic characterization of new iron(III) complexes of S-Alkyl/Aryl dithiocarbazates of 5-methyl-3-formylpyrazole and 5-methyl-3-formylpyrazolyl-thiosemicarbazones

New iron (III) complexes of S-methyl-βN-(5-methylpyrazole-3-yl)methylenedithiocarbazate, S-benzyl-β-N-β-(5-methylpyrazole-3-yl)methylenedithiocarbazate, 5-methyl-3-formylpyrazole-3-pyrrolidinylthiosemicarbazone, and 5-methyl-3-formylpyrazole-⁴N-benzylthiosemicarbazone have been synthesized and physicochemically characterized by elemental analyses, magnetic moment measurements (polycrystalline state), electronic, IR, and EPR spectra, as well as conductance measurements, are used to confirm the coordination geometry. The spectral studies reveal the low-spin distorted octahedral structure of the iron (III) complexes containing two uninegative tridentate ligands with NNS donor sites, where the EPR data confirm the presence of a spin — paired iron (III) with d _xz ² d _yz ² d _xy ¹ configuration in the ground state. The article is published in the original.     

The relevance of DEA benchmarking information and the Least-Distance Measure

Efficiency analysis is performed not only to estimate the current level of efficiency, but also to provide information on how to remove inefficiency, that is, to obtain benchmarking information. Data Envelopment Analysis (DEA) was developed in order to satisfy both objectives and the strength of its benchmarking analysis gives DEA a unique advantage over other methodologies of efficiency analysis. This study proposes the use of the Least-Distance Measure in order to obtain the shortest projection from the evaluated Decision Making Unit (DMU) to the strongly efficient production frontier, thus allowing an inefficient DMU to find the easiest way to improve its efficiency. In addition to producing reasonable benchmarking information, the proposed model provides efficiency values which satisfy the general requirements that every well-defined efficiency measure should meet.     

Modification of both the electrophilic center and substituents on the nonleaving group in pyridinolysis of O-4-nitrophenyl benzoate and thionobenzoates

A kinetic study is reported for reactions of 4-nitrophenyl benzoate (1c) and O-4-nitrophenyl X-substituted thionobenzoates (2a-e) with a series of pyridines in 80 mol % H2O/20 mol % dimethyl sulfoxide (DMSO) at 25.0 +/- 0.1 degrees C. O-4-Nitrophenyl thionobenzoate (2c) is more reactive than its oxygen analogue 1c toward all the pyridines studied. The Br?nsted-type plot is linear with beta(nuc)=1.06 for reactions of 1c but curved for the corresponding reactions of 2c with beta(nu)c decreasing from 1.38 to 0.38 as the pyridine basicity increases, indicating that the reaction mechanism is also influenced on changing the electrophilic center from C=O to C=S. The curvature center of the curved Br?nsted-type plots (defined as pK(a)(o)) occurs at pKa = 9.3 regardless of the electronic nature of the substituent X in the nonleaving group. The Hammett plot for reactions of 2a-e with 4-aminopyridine is nonlinear, i.e., the substrates having an electron-donating substituent exhibit negative deviations from the Hammett plot. However, the Yukawa-Tsuno plot for the same reactions exhibits good linear correlation, indicating that the negative deviations shown by these substrates arise from stabilization of the ground state through resonance interaction between the electron-donating substituent X and the C=S bond.     

Loss of Acot12 contributes to NAFLD independent of lipolysis of adipose tissue

In this study, we hypothesized that deregulation in the maintenance of the pool of coenzyme A (CoA) may play a crucial role in the pathogenesis of nonalcoholic fatty liver disease (NAFLD). Specific deletion of Acot12 (Acot12^−/−), the major acyl-CoA thioesterase, induced the accumulation of acetyl-CoA and resulted in the stimulation of de novo lipogenesis (DNL) and cholesterol biosynthesis in the liver. KEGG pathway analysis suggested PPARα signaling as the most significantly enriched pathway in Acot12^−/− livers. Surprisingly, the exposure of Acot12^−/− hepatocytes to fenofibrate significantly increased the accumulation of acetyl-CoA and resulted in the stimulation of cholesterol biosynthesis and DNL. Interaction analysis, including proximity-dependent biotin identification (BioID) analysis, suggested that ACOT12 may directly interact with vacuolar protein sorting-associated protein 33A (VPS33A) and play a role in vesicle-mediated cholesterol trafficking and the process of lysosomal degradation of cholesterol in hepatocytes. In summary, in this study, we found that ACOT12 deficiency is responsible for the pathogenesis of NAFLD through the accumulation of acetyl-CoA and the stimulation of DNL and cholesterol via activation of PPARα and inhibition of cholesterol trafficking.Subject terms: Gene expression, Disease model     

Functional magnetic resonance cholangiography with Gd-EOB-DTPA: A study in healthy volunteers

Purpose

To describe the patterns of bile distribution in the biliary tree, duodenum, jejunum, and stomach, and to determine the gallbladder ejection fraction (GBEF) by using functional magnetic resonance cholangiography (MRC) with gadolinium-ethoxybenzyl-diethylenetriamine penta-acetic acid (Gd-EOB-DTPA) in healthy volunteers.

Materials and Methods

Forty subjects were included in this study. After conventional MRC, pre-fatty meal MRC (PRFM) was obtained at 30, 40, 50, and 60 min after contrast agent injection. Then, post-fatty meal MRC (POFM) was obtained every 10 min for 1 h. We assessed the PRFM and POFM for opacification of contrast agent in the first- and second-order intrahepatic ducts (IHDs) and the common bile duct (CBD). Contrast agent opacification in the cystic duct was assessed, and the percentage volume of contrast agent filling in the gallbladder (GB) was calculated on PRFM. We calculated the GBEF and assessed the presence of contrast agent in the GB, duodenum, jejunum, and stomach.

Results

Thirty-six (90%) subjects showed grade 3 CBD opacification (visible contrast and well-defined bile duct border) on 60-min PRFM. Thirty-four (85%) subjects showed grade 3 first-order IHD opacification on 60-min PRFM. All (100%) subjects showed cystic duct opacification of contrast agent, and the average percentage volume of contrast agent filling in the GB was 68.81% ± 16.84% on 60-min PRFM. The GBEF at 30-min POFM was 35.00% ± 18.26%. Ten (25%) subjects had no contrast agent in the stomach and small bowel on all PRFMs. Twelve (30%) subjects had contrast medium in the stomach on PRFM and/or POFM.

Conclusions

Functional MRC with Gd-EOB-DTPA can allow determining the distribution of bile in the biliary tree and small intestine, as well as the GBEF.