Structure and absolute configuration of 9-desoxy-9-chloroquinine,C20H23N2OCl

The title compound crystallizes in the orthorhombic space groupp2₁2₁2₁a=8.674(1),b=8.944(1),c=23.255(4) Å,Z=4. The structure was solved by direct methods, and refined by full-matrix least squares toR=0.047 for 1472 observed reflections. Determination of the absolute configuration [S at C(9)] enabled a discrepancy in the literature concerning the stereochemical outcome of the reaction between SOCl₂ and quinine to be resolved.     

Separation, identification, and quantification of selected withanolides in plant extracts of Withania somnifera by HPLC-UV(DAD)--positive ion electrospray ionisation-mass spectrometry

This paper describes a method for separation, identification, and quantification of selected withanolides in Withania somnifera plant extracts by HPLC-UV(DAD)-Mass Spectrometry (HPLC-MS). Withaferin-A (WS-3), 12-deoxywithastramonolide (WS-12DS), Withanolide A (WS-1), and Withanone (WS-2) were used as external standards. The compounds were isolated from Withania somnifera by repeated column chromatography of the root extract and their identity was established by 1H- and 13C-NMR and mass spectral data. The compounds were chromatographed on a Merck (250 x 4.6 mm ID, 5 microm) column and analyzed by Electrospray Ionization on a mass spectrometer in Selected Ion Mode (SIM). For quantification, [M + Na]+ ions were monitored. Linear calibration curves were obtained in the concentration range of 1.50 microg/mL to 6.5 microg/mL. The method was applied successfully to the detection and quantification of the said withanolides in a number of samples.     

Covalent Organic Frameworks-based Nanocomposites for Oxygen reduction reaction

Journal of Inclusion Phenomena and Macrocyclic Chemistry - Due to the sluggish nature of the oxygen reduction reaction (ORR), it requires electro-catalysts to speed up the kinetics of ORR at a...     

Polymer-Assisted Electrophoretic Synthesis of N-Doped Graphene-Polypyrrole Demonstrating Oxygen Reduction with Excellent Methanol Crossover Impact and Durability

The design and synthesis of metal-free catalysts with superior electrocatalytic activity, high durability, low cost, and under mild conditions is extremely desirable but remains challenging. To address this problem, a polymer-assisted electrochemical exfoliation technique of graphite in the presence of an aqueous acidic medium is reported. This simple, cost-effective, and mass-scale production approach could open the possibility for the synthesis of high-quality nitrogen-doped graphene–polypyrrole (NG-PPy). The NG-PPy catalyst displays an improved half wave potential (E_1/2=0.77 V) in alkaline medium compared with G-PPy (E_1/2=0.66 V). Most importantly, this catalyst demonstrates excellent stability with high methanol tolerance, and it outperforms the commercial Pt/C catalyst and other previously reported metal-free catalysts. The content of graphitic nitrogen atoms is the key factor for the enhancement of electrocatalytic activity towards oxygen reduction reactions (ORR). Interestingly, the NG-PPy catalyst can be used as a cathode material in a zinc–air battery, which demonstrates a higher peak power density (59 mW cm⁻²) than G-PPy (36.6 mW cm⁻²), highlighting the importance of the low-cost material synthesis approach towards the development of metal-free efficient ORR catalysts for fuel cell and metal–air battery applications. Remarkably, the polymer-assisted electrophoretic exfoliation of graphite with a high yield (≈88 wt %) of few-layer graphene flakes could pave the way towards the mass production of high-quality graphene for a variety of applications.     

Oscillator strength measurements of the 4s5s 3S1 → 4snp 3Po2 Rydberg transitions of zinc

In the present experimental work, oscillator strengths of the 4s5s ³S₁ → 4snp ³P^o₂ (18?≤?n?≤?53) Rydberg transitions of zinc are reported. The stepwise laser excitation from the ground state 4s^{2 1}S₀ was achieved using three dye laser beams simultaneously pumped by the second (532?nm) and third (355?nm) harmonics of a Q-switched Nd: YAG (Neodymium-doped yttrium aluminum garnet) laser. The vapor containment and detection system was a single wire thermionic diode ion detector operating in space charge limited mode. A trend of the above-mentioned f-values from n?=?18 to 53 versus the principle quantum number n has been presented. Furthermore, continuity has been verified between the discrete f-values and the oscillator strength density at the threshold.     

Profiling of hydroxyurea-treated β-thalassemia/ serum proteome through nano-LC–ESI–MS/ MS in combination with microsol-isoelectric focusing

Advancements in proteomic tools offer a comprehensive solution to studying the complexity of diseases at molecular level. This study focusses on the clinical proteomic profiling of pre- and post-hydroxyurea (HU)-treated β-thalassemia patients in parallel with healthy individuals to better understand the role of HU in the treatment of β-thalassemia. The strategy encompasses sequential high-resolution protein fractionation using MicroSol-isoelectric focusing (ZOOM- IEF) followed by one-dimensional SDS-PAGE before nano-RP-LC–MS/ MS analysis of tryptic peptides. Protein identification was performed through Mascot search using NCBInr and SwissProt databases. Several different proteins were observed in pool serum samples of each of the three study groups. Approximately, 1250 proteins exclusive to each group were identified, and after removing the redundant and low sequence coverage proteins, the number was reduced to 576 (201 in healthy, 187 in HU-untreated and 188 in HU-treated group). Uniquely identified proteins in the HU-treated group regulate the focal adhesion, ECM-receptor interaction, PI3K-Akt signaling, Rap1 signaling, cAMP signaling, platelet activation, and Ca²⁺ signaling pathways in the HU-treated group. The proteomic profile presented here will add to the current state of understanding of molecular mechanisms involved in hydroxyurea treatment of β-thalassemia.     

Ionic liquid infused starch-cellulose derivative based quasi-solid dye-sensitized solar cell: exploiting the rheological properties of natural polymers

Cellulose - Starch and cellulose have long been used in various industrial applications as gelating agents. In this work, the intrinsic adhesive properties of these biopolymers are exploited for...     

Validated TLC-densitometry method for the simultaneous analysis of pyrethroid insecticides in agricultural and domestic products

Background

For therapeutic monitoring and pharmacokinetic studies of lenalidomide (LND), the potent drug for treatment of multiple myeloma (MM), a specific antibody was required for the development of a sensitive immunoassay system for the accurate determination of LND in plasma.

Results

In this study, a hapten of LND (N-glutaryl-LND) was synthesized by introducing the glutaryl moiety, as a spacer, into the primary aromatic amine site of the LND molecular structure. The structure of the hapten (G-LND) was confirmed by mass, ¹H-NMR, and ¹³C spectrometric techniques. G-LND was coupled to each of bovine serum albumin (BSA) and keyhole limpet hemocyanin (KLH) proteins by ethyl-3-(3-dimethylaminopropyl) carbodiimide as a coupling reagent. LND-KLH conjugate was used as an immunogen. Four female 2-3 months old New Zealand white rabbits were immunized with an emulsion of LND-KLH with Freund`s adjuvant. The immune response of the rabbits was monitored by direct enzyme-linked immunosorbent assay (ELISA) using LND-BSA immobilized onto microwell plates as a solid phase. The rabbit that showed the highest antibody titer and affinity to LND was scarified and its sera were collected. The IgG fraction was isolated and purified by affinity chromatography on protein A column. The specificity of the purified antibody for LND was evaluated by indirect competitive ELISA using dexamethasone as a competitor as it is used with LND in a combination therapy.

Conclusions

The high affinity of the antibody (IC₅₀ = 10 ng/mL) will be useful in the development of an immunoassay system for the determination of plasma LND concentrations. Current research is going to optimize the assay conditions and validate the procedures for the routine application in clinical laboratories.     

室温下Ga1-xHoxN (x=0.0 and 0.05)稀磁半导体薄膜磁性

采用热蒸镀技术和后续氨退火制备了Ho掺杂GaN稀磁半导体薄膜. X射线衍射分析表明,所有的峰属于六角纤锌矿结构. 利用扫描电子显微镜和能量色散谱分别进行了表面形貌和成分分析. 用振动样品磁强计在室温测定了Ga_1-xHo_xN(x=0.0,0.05)的室温铁磁性. 磁性测量结果表明,未掺杂薄膜GaN具有抗磁性行为,而Ho掺杂Ga_0.95Ho_0.05N的薄膜表现出铁磁行为.     

Versatile nanocomposites in phosphoproteomics: A review

Protein phosphorylation is one of the most important post-translational modifications. Phosphorylated peptides are present in low abundance in blood serum but play a vital role in regulatory mechanisms and may serve as casual factors in diseases. The enrichment and analysis of phosphorylated peptides directly from human serum and mapping the phosphorylation sites is a challenging task. Versatile nanocomposites of different materials have been synthesized using simple but efficient methodologies for their enrichment. The nanocomposites include magnetic, coated, embedded as well as chemically derivatized materials. Different base materials such as polymers, carbon based and metal oxides are used. The comparison of nanocomposites with respective nanoparticles provides sufficient facts about their efficiency in terms of loading capacity and capture efficiency. The cost for preparing them is low and they hold great promise to be used as chromatographic materials for phosphopeptide enrichment. This review gives an overview of different nanocomposites in phosphoproteomics, discussing the improved efficiency than the individual counterparts and highlighting their significance in phosphopeptide enrichment.