A microfluidic concentration gradient colorimetric system for rapid detection of nitrite in surface water.

A microfluidic concentration gradient colorimetric detection system consisting of a microfluidic concentration gradient colorimetric detection chip, a self-built colorimetric signal acquisition box and a self-written smartphone APP was constructed for the rapid, in-field and visual quantitative detection of nitrite. Specifically, nitrite with initial concentration of C0 can be automatically diluted into 8 concentration gradients characterized by arithmetic series, and the concentrations are 0, 0.20 C0, 0.33 C0, 0.46 C0, 0.59 C0, 0.72 C0, 0.86 C0 and C0. The colorimetric signal acquisition box avoided the interference of light spots on data acquisition. Under the optimal experimental conditions, the quantitative detection of nitrite was achieved by the proposed two-step colorimetric method based on the inhibition of AuNPs signal amplification, and the limit of detection (LOD) was 0.14 mg/L. The microfluidic concentration gradient colorimetric detection system was able to detect nitrite as low as 0.43 mg/L and showed a good specificity. The practical application was investigated by analyzing 10 actual samples of river and lake water, pure water and tap water. The recoveries of the microfluidic concentration gradient colorimetric detection system ranged from 94.92% to 105.60%, which indicates that the method had a good application prospect in the detection of practical samples.

The role of dctP gene in regulating colonization, adhesion and pathogenicity of Vibrio alginolyticus strain HY9901.

Vibriosis caused by Vibrio alginolyticus has severely affected the development of mariculture industry in recent decades. DctP, a tripartite ATP-independent periplasmic transporter solute-binding subunit, is thought to be one of the virulence factors in Vibrio. In this study, the results displayed no difference in morphological characteristics and growth between ΔdctP (dctP mutant strain) and WT (wild-type strain). Nevertheless, the ability of swarming motility, biofilm formation, ECPase formation, cell adhesion and colonized ability of ΔdctP significantly decreased compared to those of WT. The LD50 of ΔdctP significantly increased by 40-fold compared to that of WT. The transcriptome analysis demonstrated the deletion mutation of dctP could regulate the expression levels of 22 genes related to colonization, adhesion and pathogenicity in V. alginolyticus. The analysis of qRT-PCR showed the transcriptome data were reliable. These results reveal the effect of attenuated function of DctP on colonization, adherence and pathogenicity by controlling the expression of related gene.

A Rare Case of Persistent Unilateral Gestational Gigantomastia.

A 34-year-old para 2 + 0 Indonesian woman presented with persistent right-sided gestational gigantomastia some 24 months following delivery. This was severely debilitating her activities of daily living, including caring for her children. On examination, she was found to have extreme hypertrophy of her right breast, which was nodular throughout on palpation. Biochemical investigations were unremarkable and revealed no obvious etiology. Magnetic resonance imaging identified grossly enlarged right breast tissue with prominent vessels. Given the minimal involution of her breast over the 24 months postpartum, she elected for a breast reduction with free nipple grafting following appropriate counseling. This was performed through excision of breast parenchyma preserving superior-medial tissue, followed by a free nipple graft.

Synthesis and application of a series of amphipathic chitosan derivatives and the corresponding magnetic nanoparticle-embedded polymeric micelles.

Magnetic nanoparticle-embedded polymeric micelles (MNP-PMs) prepared with amphipathic polymers are an important sustained-release carrier for hydrophobic drugs. The amphipathic chitosan derivatives (ACDs) based stimuli-responsive slow-release carriers have attracted considerable attentions because of the bioactivities and modifiability of chitosan. In the current study, a series of ACDs including alkylated N-(2-hydroxy) propyl-3-trimethyl ammonium chitosan chloride (alkyl-HTCC) and alkylated polyethylene glycol N-(2-hydroxy) propyl-3-trimethyl ammonium chitosan chloride (alkyl-PEG-HTCC) were prepared by the reductive amination of HTCC and PEG-HTCC, and their structures and properties were characterized. Octyl-HTCC/O-Fe3O4 and octyl-PEG-HTCC/O-Fe3O4 MNP-PMs were prepared by the hydrophobic interactions between the corresponding ACDs and oil soluble Fe3O4 magnetic nanoparticles (O-Fe3O4 MNPs), and characterized for the structure, magnetic performance and surface charge state. Their potential application as a drug delivery carrier was investigated upon the embedding efficiency and pH dependent sustained-release performance using the hydrophobic drug, paclitaxel (PTX), as a model drug. Our work has provided a new application strategy of ACDs in the multi-functional drug delivery carrier.

A Rare Presentation of Sudden Death due to Pulmonary Thromboembolism Possibly as a Result of Giant Hepatic Hemangioma.

Hepatic hemangiomas are usually detected incidentally when investigating for other nonrelated pathologies. When symptomatic, they are usually large and cause symptoms such as abdominal discomfort or other digestive issues. Occasionally, uncommon presentations such as bleeding with coagulopathy (Kasabach-Merritt syndrome) or even fever of unknown origin may occur. As hepatic hemangiomas are benign, they do not result in tumor emboli and pulmonary thromboembolism due to hepatic hemangiomas is extremely rare. This is a case report of a rare case of a female with no known past medical history who presented with sudden death due to pulmonary thromboembolism, possibly as a result of an underlying giant hepatic hemangioma. Incidentally, she also had three other tumors-pancreatic cystic lymphangioma, cerebral capillary telangiectasia, and papillary thyroid carcinoma, and their potential contribution to the cause of death will be discussed.

Preparation of porous carboxymethyl chitosan grafted poly (acrylic acid) superabsorbent by solvent precipitation and its application as a hemostatic wound dressing.

The volume phase transition of a hydrogel initiated by shrinking may result in complex patterns on its surface. Based on this unique property of hydrogel, we have developed a novel solvent precipitation method to prepare a kind of novel superabsorbent polymers with excellent hemostatic properties. A porous carboxymethyl chitosan grafted poly (acrylic acid) (CMCTS-g-PAA) superabsorbent polymer was prepared by precipitating CMCTS-g-PAA hydrogel with ethanol. Its potential application in hemostatic wound dressing was investigated. The results indicate that the modified superabsorbent polymer is non-cytotoxic. It showed a high swelling capacity and better hemostatic performance in the treatments of hemorrhage model of ear artery, arteria cruralis and spleen of the New Zealand white rabbit than the unmodified polymer and other commonly used clinic wound dressings. The hemostatic mechanism of the porous CMCTS-g-PAA polymer was also discussed.

Strangled at birth? Forest biotech and the Convention on Biological Diversity.

Against the Cartagena Protocol and widespread scientific support for a case-by-case approach to regulation, the Convention on Biological Diversity has become a platform for imposing broad restrictions on research and development of all types of transgenic trees.

[Study on the ultraviolet spectra of diacetone acrylamide].

Diacetone acrylamide (DAAM) is an important monomer which can be copolymerized with other monomers, so the copolymers with different properties can be obtained. In the present paper, the ultraviolet spectra of diacetone acrylamide solutions in four different solvents (water, acetonitrile, methanol, cyclohexane) were studied, and it was found that there were two strong absorption peaks around 200 nm and 226 nm, respectively. The absorption peak around 200 nm was sensitive to the polarity of the solvent. The absorption shifted to the lower wavelength as the polarity of the solvent was increased, especially in water and acetonitrile. And the adsorption shifted to longer wavelength with the increase in the concentration. However, the other absorption peak at 226 nm remained basically stable when the concentration or the polarity of the solvent was changed. Obviously the absorption at 226 nm is reasonably considered as a characteristic peak of DAAM in the ultraviolet quantitative analysis. And the other absorption peak at 200 nm which is sensitive to the solvent and concentration can be taken to study the interactions between DAAM and solvent molecules. Also, the strength of the adsorption was affected by the polarity of the solvent.

Crosslinked carboxymethylchitosan-g-poly(acrylic acid) copolymer as a novel superabsorbent polymer.

A novel carboxymethylchitosan-g-poly(acrylic acid) (CMCTS-g-PAA) superabsorbent polymer was prepared through graft polymerization of acrylic acid onto the chain of carboxymethylchitosan and subsequent crosslinking. It was demonstrated by FTIR spectroscopy that acrylic acid had been graft polymerized with carboxymethylchitosan. The thermal stability of the polymer was characterized by thermogravimetric analysis. By studying the swelling ratio of the polymer synthesized under different conditions, optimization conditions were found for a polymer with the highest swelling ratio. The rate of water absorption of the polymer was high, and the swelling of the polymer fitted the process of first dynamics. The swelling ratio of the polymer was pH-dependent.

Improvement of alkali solubility of cellulose with enzymatic treatment.

Cellulose was treated with different extracellular microbial enzymes. The treatment of cellulose with the enzymes can improve alkaline solubility. Both endoglucanase and crude cellulase decreased the average degrees of polymerization ([see text]) and improved the alkaline solubility of cellulose most efficiently. The composition of the enzyme, the type of cellulosic materials, pretreatment, and the treatment conditions are the key factors for its effective processing, using the enzymes to improve on alkaline solubility of cellulose. The improvement in the alkaline solubility is caused by the decrease in [see text] and hydrogen bond because of enzymatic hydrolysis.

[Studies on the ultraviolet spectra of PU/PA composite emulsions].

PUA composite particles were prepared by seeded surfactant-free emulsion polymerization, the polyurethane (PU) aqueous dispersions were used as seed particles. The studies on the UV spectra of PUA composite emulsions were carried out, the results showed that the maximum absorbance of n-pi* transition evidently shifted to red wavelength with increasing the concentration of the aqueous PU seed dispersions; the UV absorbance of PU dispersions decreased with increasing the amounts of the hydrophilic chain-extender and increased with increasing the NCO/OH molar ratios; when the hydrophilic chain-extender was 7.5%, the UV absorbance of PUA composite emulsion reached the lowest, the type of initiators showed less influence on the absorbance of UV spectra of PUA composite emulsions. Moreover, the UV spectra of PU dispersions and the diameters of PUA composite emulsion particles were nearly correlative.

Study on lyotropic liquid-crystalline properties of trimethylsilyl hydroxypropylcellulose.

The lyotropic liquid-crystalline behavior of trimethylsilyl hydroxypropylcellulose (TMS-HPC) is reported in this paper. The introduction of the trimethylsilyl (TMS) group in the parent HPC increases the solubility in organic solvents, and the lyotropic mesophase can be formed in concentrated acetone solution. The critical concentration (C*) in acetone is approximately 36%. The liquid crystalline nature of TMS-HPC/acetone solution was confirmed by PLM, and the mechanism of liquid crystallization was studied by FTIR and WAXD methods.

The properties of enzyme-hydrolyzed cellulose in aqueous sodium hydroxide.

Pure natural cellulose (softwood pulp) modified with cellulase is allowed to react with sodium hydroxide in a muller, and changes in structure and properties are investigated by FTIR and DSC. The reactivity of cellulose for some dissolving and derivatization processes is shown to be improved by an enzymatic hydrolysis and admixture with sodium hydroxide. The modified cellulose dissolved at 9% (wt) sodium hydroxide at -10 degrees C at 6% pulp consistency, while the DP of cellulose is >350.

Effects of cellulase on the modification of cellulose.

Multicomponent cellulases, purified endoglucanases and cellobiohydrolases were assayed and shown to modify pure natural cellulose (softwood pulp). Changes in structure and properties of the cellulose caused by enzymatic treatment depend on the composition, the type of enzyme, and the treatment conditions. The reactivity of cellulose for some dissolving and derivatization processes may be improved by enzymatic hydrolysis. Endoglucanases decreased the average degrees of polymerization (DP) and improved the alkaline solubility of cellulose most efficiently. The variation in the supramolecular structure estimated from the infrared spectra of the cellulose samples was found to be correlated with the reactivity and might represent wide variations in conformation caused by the breakdown of the hydrogen bonds.