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  • Author: Hongyu Zhang x
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Synthesis and characterization of thiourea

Abstract

Herein, a simple and effective method for the preparation of thiourea using a nucleophilic substitution reaction is reported. Urea and Lawesson’s reagent were used as the raw materials to prepare thiourea via a one-step method involving the sulfuration reaction, and the reaction mechanism was analyzed. The effect of the reaction time, reaction temperature, and mass ratio of the raw materials on the yield of thiourea were investigated.The most beneficial conditions used for the reaction were determined to be: Reaction time = 3.5 h, reaction temperature = 75°C, and mass ratio of urea to Lawesson’s reagent = 2:1. Under these optimal conditions, the average yield of thiourea over five replicate experiments was 62.37%. Characterization using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and thermogravimetric analysis (TGA) showed that the as-synthesized substance was thiourea. Our synthetic method has the advantages of high yield, mild reaction conditions and simplicity.

Open access
Should vasoconstrictors be considered in a cirrhotic patient with acute non-variceal upper gastrointestinal bleeding?

Abstract

Varices manifest as a major etiology of upper gastrointestinal bleeding in patients with chronic liver diseases, such as liver cirrhosis and hepatocellular carcinoma. By contrast, non-variceal upper gastrointestinal bleeding is rare. Pharmacological treatment differs between patients with variceal and non-variceal bleeding. Vasoconstrictors are recommended for the treatment of variceal bleeding, rather than non-variceal bleeding. In contrast, pump proton inhibitors are recommended for the treatment of non-variceal bleeding, rather than variceal bleeding. Herein, we present a case with liver cirrhosis and acute upper gastrointestinal bleeding who had a high risk of rebleeding (i.e., Child–Pugh class C, hepatocellular carcinoma, portal vein thrombosis, low albumin, and high international normalized ratio and D-dimer). As the source of bleeding was obscure, only terlipressin without pump proton inhibitors was initially administered. Acute bleeding episode was effectively controlled. After that, an elective endoscopic examination confirmed that the source of bleeding was attributed to peptic ulcer, rather than varices. Based on this preliminary case report, we further discussed the potential role of vasoconstrictors in a patient with cirrhosis with acute non-variceal upper gastrointestinal bleeding.

Open access
Successful pharmacotherapy for multiple acute decompensation events in a cirrhotic patient with acute-on-chronic liver failure: A case report

Abstract

Acute-on-chronic liver failure (ACLF) is a potentially lethal syndrome, which is characterized by an acute deterioration of liver function in patients with chronic liver diseases. The present paper reported that an alcoholic cirrhotic patient with ACLF developed septic shock, hydrothorax, ascites, hepatic encephalopathy, acute kidney injury, and acute upper gastrointestinal bleeding at the same hospitalization and was successfully rescued by pharmacotherapy alone without any invasive intervention.

Open access
Short Note: Development and characterization of 16 new polymorphic microsatellite loci for Schima superba (Theaceae)

Abstract

Schima superba is a common dominant tree species in evergreen broad-leaved forest in subtropical China. Despite its multiple usages in wood industry, reforestation and traditional Chinese medicine, its genetic diversity is poorly studied. To help studying its genetic diversity and structure in the future, after microsatellite enrichment and screening, we identified 16 microsatellites in S. superba. These markers showed polymorphism in three populations. The number of alleles per locus ranged from 3 to 32 with a mean of 14. Within populations, the observed and unbiased expected heterozygosities ranged from 0.048 to 0.926 and from 0.048 to 0.949, respectively. The newly developed 16 microsatellites will be useful for investigating the genetic diversity and structure from large scale patterns to fine-scale structures in this species.

Open access
Hydrothermal synthesis and thermoelectric properties of PbS

Abstract

In this paper, hydrothermal approach combined with high pressure sintering method was employed to synthesize PbS. The X-ray diffraction results show that single phase PbS can be obtained by a simple hydrothermal method. The scanning electron microscope results show that the PbS sample has nearly cubic shape and preserves well crystallized and coarse grains after high pressure sintering. The thermoelectric performance of PbS obtained in this study is comparable to that of a PbS sample prepared by conventional method. The carrier type and concentration of PbS can be tuned effectively by doping with Bi. The maximum figure of merit for PbS doped with 1 mol% Bi reaches 0.44 at 550 K, which is about 30 % higher than that of undoped PbS. These results indicate that hydrothermal method provides a viable and controllable way of tuning the electrical transport and thermoelectric properties for PbS.

Open access