Search

A highly conductive thin film composite based on silver nanoparticles (AgNPs) and malic acid (MA) was deposited on glassy carbon electrode (GCE) for the selective and sensitive electrochemical sensing of trichloroacetic acid (TCA). The casting solution containing MA functionalized AgNPs was employed as a precursor for the thermal deposition of the AgNPs integrated MA thin film composite onto the GCE surface. The uniform coverage of AgNPs within the thin film composite at GCE was obtained by field emission scanning electron microscopy (FESEM). A significantly high charge transfer resistance of the modified electrode (85.7 Ω for AgNPs-MA/GCE in 2 mM [Fe(CN)6]3-/4- at a bias of +0.235 V as compared to bare GCE (38.01 Ω) verified the optimum coating of AgNPs-MA composite at the surface of the electrode. The AgNPs-MA composite deposited GCE revealed substantial electrocatalytic activity toward TCA reduction with significantly enhanced reduction current. The novel electrode manifested a linear square wave voltammetric (SWV) response over the concentration ranges of 0.1–2 (R2 = 0.9953) and 4-100 μM (R2 = 0.9969) with a limit of detection (LOD) and limit of quantification (LOQ) of 30 nM and 92.5 nM, respectively. The modified electrode exhibited an excellent long-term stability (30 days) with the retention of >95% of initial current. The selectivity of the proposed electrode for the determination of TCA was examined in the presence of dichloroacetic acid (DCA) and monochloroacetic acid (MCA) with the retention of high recovery percentages.

The colloidal dispersion of copper nanoparticles (CuNPs), prepared by reducing Cu2+ ions using ascorbic acid, was characterized and used for electrochemical and antimicrobial activity investigations. By depositing CuNPs onto the glassy carbon electrode (GCE) surface the CuNPs/GCE was constructed, which was used to study electrochemical behavior of CuNPs and to carry out direct electrochemical detection of trichloroacetic acid (TCA) and 2-chlorophenol (2-CP) in neutral medium. Excellent electrocatalytic ability of CuNPs, assessed by cyclic voltammetry (CV), for the reduction of TCA and 2-CP was detected. The electrochemical impedance analysis (EIS) of the GCE and CuNPs modified GCE evidenced higher charge transfer activity across the modified electrode surface. The antibacterial activity tests of as-synthesized CuNPs on the selected pathogenic strains of pathogenic strains of Salmonella group B (7.9±0.912), Klebsiella pneumonia (8.33±1.561), Escherichia Coli (15.65±1.612), Enterococcus faecalis (5.4±0.612), Staphylococcus aureus (12.6±1.531) and yeast Candida albicans (11.4.3±1.512), respectively, were performed. The results indicated that the use of CuNPs can be pursued as an alternative strategy (to antibiotics) for averting infections by controlling bacterial adhesion and bacterial bio-film formation against microbial infections.

Copper(II) carboxylates are reduced efficiently by methanol in the presence of alkynes and form yellow alkynylcopper(I) polymeric precatalysts that are involved with azides, in the absence of added ligands, in the catalytic cycles that result in the formation of 1,4-disubstituted 1,2,3-triazoles.

We describe the development of a mild and efficient method for the preparation of β-unsaturated α-amino esters through the ytterbium triflate catalyzed addition of potassium alkynyltrifluoroborate salts to imino esters. The synthetic viability of this protocol was supported by its high yields, short reaction times, and efficiency with regard to the scope of the substrates.

A simple protocol which led to an effective construction of α-alkenyl-α-amino esters was achieved under mild conditions. This transformation proceeded by Yb-catalyzed addition of alkenyltrifluoroborates across the imine double bond. A variety of functional groups could be applicable to both partners.

Copper(II) carboxylates are reduced efficiently by methanol in the presence of alkynes and form yellow alkynylcopper(I) polymeric precatalysts that are involved with azides, in the absence of added ligands, in the catalytic cycles that result in the formation of 1,4-disubstituted 1,2,3-triazoles.

We reported a fast and easy method for obtaining biarylic units from tyrosine derivatives via Suzuki-Miyaura cross-coupling using a variety of substituted and unsubstituted potassium aryl- and heteroaryltrifluoroborate salts. The scope of the methodology was also extended to the formation of bis-tyrosine linked dipeptide bonds, leading to biologically interesting compounds. Some biarylic units were obtained as free amino acids through the one step cleavage reaction in good yields.

Studies have shown that the risk of malignancy in follicular neoplasms is as high as 30%. Often, surgery is recommended for such lesions, not for therapeutic purposes but as a diagnostic method, leading to increased hospital costs and related morbidities. Recent studies have suggested that tumor size predicts malignant potential of these follicular neoplasms. Our aim was to identify the impact of nodule size on the risk of malignancy for such lesions.A retrospective medical chart review was undertaken for patients who underwent thyroid surgery at a single academic North American Institution. A total of 120 follicular lesions, follicular neoplasms (Bethesda category IV) or follicular lesions of undetermined significance (Bethesda category III) in 110 patients undergoing thyroid surgery were evaluated. Nodule size as measured by ultrasound, fine-needle aspiration cytological results, and final histopathology reports were reviewed. Analysis was performed by classification according to nodule size:3 cm, ≥3 cm,4 cm and ≥4 cm.Out of the 120 nodules, 48 (40%) were reported to be malignant on final pathological examination. The malignancy rate in nodules3 cm and ≥ 3cm was 41% and 37.8%, respectively (p=0.84). When 4 cm was used as the cut-off, the rate in nodules4 cm and ≥4 cm was 40.6% and 37.5%, respectively (p=0.82).Increased thyroid nodule size does not increase the malignancy rate for follicular neoplasms. Hence, we recommend against routine total thyroidectomy for patients with follicular neoplasms based on the size criteria.

The reaction of ethyl (p-methoxyphenylimino)acetate with propargyl bromide mediated by activated zinc powder afforded alkynyl amine, which was then reacted with a variety of organic azides using a microwave energy source, leading to β-1,2,3-triazolyl-α-amino esters in good yield.

The advantages of the mild and efficient method for the synthesis of the title compounds are high yields, short reaction times, and efficiency with regard to the scope of the substrates.

OBJECTIVE The etiology of altered sensorium in diabetic ketoacidosis (DKA) remains unclear. Therefore, we sought to determine the origin of depressed consciousness in DKA. RESEARCH DESIGN AND METHODS We analyzed retrospectively clinical and biochemical data of DKA patients admitted in a community teaching hospital. RESULTS We recorded 216 cases, 21% of which occurred in subjects with type 2 diabetes. Mean serum osmolality and pH were 304 ± 31.6 mOsm/kg and 7.14 ± 0.15, respectively. Acidosis emerged as the prime determinant of altered sensorium, but hyperosmolarity played a synergistic role in patients with severe acidosis to precipitate depressed sensorium (odds ratio 2.87). Combination of severe acidosis and hyperosmolarity predicted altered consciousness with 61% sensitivity and 87% specificity. Mortality occurred in 0.9% of the cases. CONCLUSIONS Acidosis was independently associated with altered sensorium, but hyperosmolarity and serum “ketone” levels were not. Combination of hyperosmolarity and acidosis predicted altered sensorium with good sensitivity and specificity.

Yellow polymeric alkynylcopper(I) compounds observed in the three-component Mannich reactions of alkynes, secondary amines and aldehydes are shown to be pre-catalysts that give rise to catalytic copper(I) alkyne complexes by interaction with secondary amines (see scheme). Interaction of these complexes with iminium ions (formed from aldehydes or their equivalents, including CH2Cl2), results in the formation of Mannich bases in high yields.

In the title compound, C15H20BrNO2, there are two independent molecules (AandB) comprising the asymmetric unit and these adopt very similar conformations. InA, the dihedral angle between the CO2and MeC=CMe2groups is 80.7 (3)°, and these make dihedral angles of 3.5 (3) and 84.09 (16)°, respectively, with the bromobenzene ring. The equivalent dihedral angles for moleculeBare 78.4 (3), 2.1 (3) and 78.37 (12)°, respectively. The most prominent interactions in the crystal packing are amine-N—H...O(carbonyl) hydrogen bonds between the two independent molecules, resulting in non-centrosymmetric ten-membered {...OC2NH}2synthons. Statistical disorder is noted for each of the terminal methyl groups of the ethyl residues.