Application of microcrystalline cellulose as an efficient and cheap sorbent for the extraction of metoprolol from plasma and wastewater before HPLC–MS/MS determination

A dispersive solid-phase extraction method based on a new sorbent has been performed on plasma and wastewater samples to determine metoprolol by high-performance liquid chromatography–tandem mass spectrometry. In this study, the analyte was adsorbed from the samples onto microcrystalline cellulose as a green and efficient sorbent and then eluted for use in the determination step. In the mass spectrometer, the analyte was detected in the positive mode and selectivity of the analysis was increased by sequential mass analysis through multiple reaction monitoring. All of the effective parameters in the extraction of metoprolol from plasma and wastewater were optimized. Under optimal conditions the method was linear in the ranges of 1–1,000 and 0.1–1,000 ng/ml in plasma and wastewater samples, respectively. The detection limits of the method were 0.30 and 0.03 ng/ml in plasma and wastewater samples, respectively. The data showed that the method provides low detection limit, wide linear range, good precision and high extraction recovery. Finally several plasma and wastewater samples were successfully analyzed using the method. The use of a small amount of a green and inexpensive sorbent and a low volume of plasma without the need for further pretreatment steps are the main advantages of the method.     

Silica-Supported MnII Sites as Efficient Catalysts for Carbonyl Hydroboration,Hydrosilylation, and Transesterification

Manganese, the third most abundant transition-metal element after iron and titanium, has recently been demonstrated to be an effective homogeneous catalyst in numerous reactions. Herein, the preparation of silica-supported Mn^II sites is reported using Surface Organometallic Chemistry (SOMC), combined with tailored thermolytic molecular precursors approach based on Mn₂[OSi(OtBu)₃]₄ and Mn{N(SiMe₃)₂}₂⋅THF. These supported Mn^II sites, free of organic ligands, efficiently catalyze numerous reactions: hydroboration and hydrosilylation of ketones and aldehydes as well as the transesterification of industrially relevant substrates.     

Electrical Stimulation of Human Mesenchymal Stem Cells on Conductive Substrates Promotes Neural Priming

Electrical stimulation (ES) within a conductive scaffold is potentially beneficial in encouraging the differentiation of stem cells toward a neuronal phenotype. To improve stem cell-based regenerative therapies, it is essential to use electroconductive scaffolds with appropriate stiffnesses to regulate the amount and location of ES delivery. Herein, biodegradable electroconductive substrates with different stiffnesses are fabricated from chitosan-grafted-polyaniline (CS-g-PANI) copolymers. Human mesenchymal stem cells (hMSCs) cultured on soft conductive scaffolds show a morphological change with significant filopodial elongation after electrically stimulated culture along with upregulation of neuronal markers and downregulation of glial markers. Compared to stiff conductive scaffolds and non-conductive CS scaffolds, soft conductive CS-g-PANI scaffolds promote increased expression of microtubule-associated protein 2 (MAP2) and neurofilament heavy chain (NF-H) after application of ES. At the same time, there is a decrease in the expression of the glial markers glial fibrillary acidic protein (GFAP) and vimentin after ES. Furthermore, the elevation of intracellular calcium [Ca²⁺] during spontaneous, cell-generated Ca²⁺ transients further suggests that electric field stimulation of hMSCs cultured on conductive substrates can promote a neural-like phenotype. The findings suggest that the combination of the soft conductive CS-g-PANI substrate and ES is a promising new tool for enhancing neuronal tissue engineering outcomes.     

Ni(II), Co(II), and Cu(II) complexes incorporating 2-pyrazinecarboxylic acid：Synthesis,characterization, electrochemical evaluation,and catalytic activity for the synthesis of 2H-indazolo[2,1-b]phthalazine-triones

Three complexes containing 2-pyrazinecarboxylate (pzca–), including [Ni(pzca)2(H2O)2], [Co(pzca)2(H2O)2], and [Cu(pzca)2(H2O)2], have been synthesized and characterized using physico-chemical and spectroscopic methods. Furthermore, the structure of each complex was determined by single-crystal X-ray diffraction. All three complexes have an octahedral geometry, where the metal ion chelated by two carboxylate oxygens, two nitrogen atoms belonging to pyrazinic acid molecules, and two oxygen atoms of two water molecules. The catalytic activities of these complex-es were also investigated in the green synthesis of 2H-indazolo[2,1-b]phthalazine-triones by the reaction of hydrazine hydrate with an arylaldehyde, phthalic anhydride, and dimedone in acetic acid.     

Palladium on magnetic Irish moss: A new nano‐biocatalyst for suzuki type cross‐coupling reactions

A novel heterogeneous magnetic palladium nano‐biocatalyst was designed by utilizing Irish moss, a family of sulfated polysaccharides extracted from algae, as a natural biopolymer. This magnetic Irish moss decorated with palladium (Pd–Fe₃O₄@IM) to form a biomagnetic catalytic system was synthesized and well characterized by FT–IR analysis, X‐ray powder diffraction, field emission scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, atomic absorption spectroscopy and transmission electron microscopy. The catalyst was stable to air and moisture and displayed high catalytic activity in ligand‐free Suzuki–Miyaura cross‐coupling reactions conducted under green chemistry reaction conditions. The aromatic ketones are produced by the cross‐coupling reaction between acid chlorides and aryl boronic acid derivatives in high yields.     

Generation and recombination in two-dimensional bipolar transistors

We study the effects of recombination and generation process on the operation of bipolar junction transistor based on two-dimensional materials, and in particular, graphone. Here, we use Shockley–Read–Hall model to study these process. First, we investigate the current–voltage characteristics of a graphone p–n junction considering generation and recombination process. Then, we calculate the estimated changes in current gain, cutoff frequency, and output characteristics of a graphone bipolar junction transistor designed in a recent study.     

Novel Four-Step Synthesis of Thioxo-quinazolino[3,4-a]quinazolinone Derivatives

A novel synthesis of thioxo-quinazolino[3,4-a]quinazolinone framework was developed through a four-step reaction starting from isatoic anhydride. The resulting 2-aminobenzamides from the reaction of isatoic anhydride and different amines underwent coupling–cyclization reaction with 2-nitrobenzaldehydes, reduction of nitro group, and then cyclization reaction with carbon disulfide (CS₂). All steps were carried out under easy and user-friendly conditions in a short time without using expensive catalysts or reagents.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]     

Liquid-vapor transition driven by bond disorder

We report grand-canonical Monte Carlo simulations of an equimolar mixture of hard colloids coated with long polymers that have a complementary functionalization. Such systems have the potential to function as self-healing materials. Under conditions where the complementary polymer ends are strongly associated, we observe a first-order vapor-liquid transition from a dilute gas of colloidal dimers to a dense, liquid-like phase. This transition is driven exclusively by the increase in entropy associated with bond disorder-an effect that was predicted theoretically by Zilman et al. [Phys. Rev. Lett. 91, 015901 (2003)10.1103/PhysRevLett.91.015901]. Our simulations rationalize experimental observations by Schmatko et al. [Soft Matter 03 (2007) 703.].     

Exploring the hydroxylation-dehydrogenation connection: novel catalytic activity of castor stearoyl-ACP Delta(9) desaturase

The novel product profile obtained by incubating chiral fluorinated substrate analogues with castor stearoyl-ACP Delta(9) desaturase has been rationalized through a series of labeling studies. It was found that the introduction of the Z-double bond between C-9 and C-10 of the parent substrate occurs with pro-R enantioselectivity--a result that accounts for the observed stereochemistry of oxidation products derived from (9R)- and (9S)-9-fluorostearoyl-ACP. Oxidation of (9R)-9-fluorostearoyl-ACP occurs via at least two rapidly interchanging substrate conformations in the active site as detected by reaction pathway branching induced by deuteration at C-10 and C-11. Hydroxylation and desaturation of this substrate share the same site of initial oxidative attack.     

The quantum chemical calculation of NMR two-bond spin–spin coupling constants in the N?···H–OH?→?N–H···OH? switching

A quantum chemical study has been carried out to investigate the effects of the size of H₂O cluster and substituents (X = H, Me, OMe, CHO, NO, and NO₂) in the para position of the anilide ion on the two-bond spin–spin coupling constants (SSCCs) ^2h J _N···O across in the N–H–O switching at B3LYP/6-311 ++G(2d,2p) level of theory. The changes in ^2h J _N···O SSCCs due to variation of substituent and H₂O cluster size were well monitored by changes in binding energy, structural parameter, electron density topography, natural charge, charge transfer, and percentage of p-character of N atom in the C–N bond. Linear correlations were found between ^2h J _N···O and above-mentioned properties.