A structure-property study for konjac glucomannan and guar galactomannan: Selective carboxylation and scale inhibition.

The effect of structural difference for konjac glucomannan (KGM) and guar galactomannan (GGM) on their physicochemical properties including selective carboxylation, biodegradation and scale inhibition was firstly investigated. Compared with GGM, KGM can be specially modified by amino acid to prepare carboxyl-functionalized polysaccharides. The structure-activity relationship explaining the difference in carboxylation activity and the anti-scaling abilities of polysaccharides and carboxylated derivatives were explored by static anti-scaling, iron oxide dispersion and biodegradation tests coupled with structural and morphological characterizations. KGM with linear structure was preferred for carboxylated modification by glutamic acid (KGMG) and aspartic acid (KGMA) while GGM with branched structure failed to accomplish that due to steric hindrance. GGM and KGM showed limited scale inhibition performance, which was probably attributed to the moderate adsorption and isolation effect of macromolecular stereoscopic structure. While KGMA and KGMG performed as effective and degradable inhibitors for CaCO3 scale with inhibitory efficiencies > 90 %.

The dichotomous role of TGF-ß in controlling liver cancer cell survival and proliferation.

Hepatocellular carcinoma (HCC) is the major form of primary liver cancer and one of the most prevalent and life-threatening malignancies globally. One of the hallmarks in HCC is the sustained cell survival and proliferative signals, which are determined by the balance between oncogenes and tumor suppressors. Transforming growth factor beta (TGF-ß) is an effective growth inhibitor of epithelial cells including hepatocytes, through induction of cell cycle arrest, apoptosis, cellular senescence, or autophagy. The antitumorigenic effects of TGF-ß are bypassed during liver tumorigenesis via multiple mechanisms. Furthermore, along with malignant progression, TGF-ß switches to promote cancer cell survival and proliferation. This dichotomous nature of TGF-ß is one of the barriers to therapeutic targeting in liver cancer. Thereafter, understanding the underlying molecular mechanisms is a prerequisite for discovering novel antitumor drugs that may specifically disable the growth-promoting branch of TGF-ß signaling or restore its tumor-suppressive arm. This review summarizes how TGF-ß inhibits or promotes liver cancer cell survival and proliferation, highlighting the functional switch mechanisms during the process.

Experimental and theoretical studies of sodium acetyldithiocarbamate for the removal of Cu2+ and Ni2+ from aqueous solution.

With the continuous worsening of water pollution, the use of various collectors to remove heavy metal ions from aqueous solutions has attracted widespread attention. In this work, an acid-resistant collector, sodium acetyldithiocarbamate (ADTC) that combines acetamide with carbon disulfide was proposed for heavy metal removal. The structure of ADTC was characterized by Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance spectrometer (NMR). Flame atomic absorption spectrophotometry (FAAS) was used to detect the concentration of metal ions in the solution before and after the treatment of the chelating agents. The chelation removal efficiency are compared for different chelating agents for Cu2+ and Ni2+ in acidic aqueous solution with pH = 1-7, and compared to the chelation removal efficiency of sodium diethyldithiocarbamate (DDTC) and sodium ethyl xanthate (SEX) chelating agents. The experimental results suggest the order of the chelating ability is ADTC > DDTC > SEX for Cu2+ and Ni2+. The chelating ability of ADTC to Ni2+ is stronger than that of Cu2+. The chelating ability of the collector is greatly affected by the pH value. The ADTC has a good chelating ability in the pH range of 3-7. The molecular orbital distribution, charge and electrostatic potential surfaces in quantum chemistry are used to explore the main active sites of the chelating agent are the S atom. The results of high resolution mass spectrometry showed that the ADTC is coordinated with the positive divalent metal ion in the ratio of 2:1. According to the results, the dithioamino (-NHCSS-) groups are coordinated with the positive divalent metal ion in a 2:1 ratio. Molecular dynamics simulation is used to explore the adsorption energy and binding strength of the chelating agent on the metal surface.

A self-curing konjac glucomannan/CaCO3 coating for corrosion protection of AA5052 aluminum alloy in NaCl solution.

A composite coating containing konjac glucomannan (KGM) and CaCO3 was fabricated on AA5052 alloy through a self-curing process, and its surface morphology and component were characterized by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The effect of Ca(OH)2 content on the protective property of the composite coating for aluminum alloy in 3.5 wt% NaCl solution was evaluated by electrochemical impedance spectroscopy measurements. Moreover, the inhibitory performance of the coating on the pitting corrosion of metal was examined by potentiodynamic polarization curves and atomic force microscopy (AFM). The images of scanning electron microscope show the composite coating with a thickness of 50 µm has well-defined branch-shaped structure. The FT-IR spectra confirm the successful fabrication of the polymer coating through the formation of CaCO3. The results of electrochemical impedance spectroscopy suggest that the resistance of the aluminum alloy sample coated with such protective layer is improved by six orders of magnitude, compared with the bare metal. After 60 d of immersion, the polarization curve data and AFM analysis show the pitting corrosion occurring on AA5052 surface is prevented due to the barrier property of coating.

Effect of scale inhibitors on the structure and morphology of CaCO3 crystal electrochemically deposited on TA1 alloy.

The deposition of CaCO3 scale in circulating cooling water on metal surface is a major concern in industry. This paper focuses on the feasibility of electrochemical methods to study the scale inhibition performance of 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP) and 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTCA), Polyacrylic Acid (PAA), including linear sweep voltammetry, chronoamperometry, and electrochemical impedance spectroscopy (EIS). In addition, the coverage, morphology and structure of deposited CaCO3 crystal on titanium alloy surface in the absence and presence of inhibitors were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). A new method for calculating the efficiency of scale inhibitors was proposed so that it can be calculated by using the change in residual current density (ir). In order to prove the feasibility and accuracy of such method, the efficiencies of inhibitors were evaluated using ir and charge transfer resistance (Rct), respectively. In addition, molecular dynamics (MD) simulations were performed to evaluate the interaction between the scale inhibitor molecule and the CaCO3 crystal. The experimental results show that both the residual current density obtained by chronoamperometry and the charge transfer resistance obtained by electrochemical impedance spectroscopy can be used to evaluate the efficiency of scale inhibitors, and there is high consistency from the calculation results. It is also confirmed by X-ray diffraction and scanning electron microscopy studies that the presence of inhibitor reduces the surface coverage of CaCO3 at metal electrode and that the crystal structure of CaCO3 is transformed from the original aragonite into the most unstable vaterite. The best inhibition efficiency of PBTCA for CaCO3 deposit is confirmed by the results of MD simulations.

Efficiency and Safety Assurance of Six Fungicides Applied on Postharvest Cabbages Stored in a Natural Environment.

Postharvest disease is a major factor in the limited shelf life of many fruits and vegetables, and it is often managed using fungicidal spraying or soaking. In this study, we first tested the efficiency of six common fungicides on postharvest head cabbage ( Brassica oleracea var. capitata) against Botrytis cinerea. Afterward, the elimination abilities of these six fungicides on different layers of cabbage heads were examined, and the effects of the household processes on residue removal were evaluated. Results showed that very low contents of residues reached the inner layers and that peeling the three outmost leaves of cabbage could eliminate most of the investigated fungicides. All six fungicides disappeared during washing, stir-frying, or boiling, among which cyprodinil was the easiest to be eliminated. Furthermore, the combined processes reduced the residues below the limits of quantification for all six investigated fungicides, even after 2 days of spraying.

Cadmium-induced serotonergic neuron and reproduction damages conferred lethality in the nematode Caenorhabditis elegans.

Cadmium is a ubiquitous environmental toxicant. The use of Caenorhabditis elegans as a model for monitoring cadmium exposure has revealed several conserved signaling pathways. However, little is known about the killing process during lethality assay. In the present study, we investigated the effects serotonergic neuronal and reproductive damages on cadmium exposure in C. elegans. We found that sterile hermaphrodites, males and worms that passed reproduction span presented high cadmium resistance compared to those of young adults. The results demonstrated that reproduction process other than reproduction capacity conferred cadmium sensitivity. Cadmium exposure resulted in high ratio bagging phenotype, which was a severe reproductive deficit with embryos hatched internally that could cause worms to die early. The mechanism of bagging formation was ascribed to cadmium-induced egg laying deficiency that led embryos to retain and hatch in uterus. The addition of serotonin and imipramine promoted egg laying and thereby increased cadmium resistance. The results demonstrated that vulval muscles responsible for egg laying were still functional, while the serotonergic hermaphrodite specific neurons might be dysfunctional under cadmium exposure. Cadmium exposure resulted in shrinkage of serotonergic neuronal body and reduced expressions of tryptophan hydroxylase, the key enzyme for serotonin synthesis. The protection of serotonergic neuron through transient thermal preconditioning improved survival rate. In conclusion, our study demonstrated that damages of serotonergic neurons and reproduction conferred to cadmium-induced lethality.

Inhibitory effect of konjac glucomanan on pitting corrosion of AA5052 aluminium alloy in NaCl solution.

A natural carbohydrate polymer, konjac glucomanan, has been extracted from commercial product and studied as a green corrosion inhibitor for AA5052 aluminium alloy in 3.5 wt% NaCl solution by high-performance gel permeation chromatography (GPC), thermo gravimetric analysis (TGA), Fourier-transform infrared (FT-IR) spectra, electrochemical measurement and surface characterization techniques. The results of GPC measurements suggest the weight-average molecular weight and the number-average molecular weight of KGM with 98.2% purity are 1.61 × 105 g/mol and 1.54 × 105 g/mol, respectively. Potentiodynamic polarization curves show konjac glucomanan behaves as a mixed-type inhibitor with dominant anodic effect and that its maximum efficiency at 200 ppm is 94%. Electrochemical impedance spectroscopy (EIS) studies reveal the resistance of oxide film is approximately two orders of magnitude greater than the resistance of adsorbed inhibitor layer and that they both increase with KGM concentration. Moreover, in-situ electrochemical noise (EN) detection demonstrates that the growth and propagation stages of the pitting corrosion germinating on metal surface are blocked by polysaccharide additive, which is confirmed by the surface analysis of aluminium alloy using scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and Raman spectroscopy. At last, it is found that the addition of KGM makes it harder for water droplet containing NaCl to wet the metallic substrate.

Amino acids modified konjac glucomannan as green corrosion inhibitors for mild steel in HCl solution.

Konjac glucomannan (KGM) was modified with amino acids to synthesize polysaccharide esters (KGMA and KGMH) which were evaluated as corrosion inhibitor for mild steel in 0.5M HCl solution by weight loss tests, Tafel curves, electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). The synthetic polymers were found to have the lower water absorbency and the higher water solubility than KGM. Gravimetric measurements showed the maximum efficiencies of KGMA and KGMH for decreasing the corrosion rate of metal at 2000ppm are up to 89.9% and 92.4%, respectively. Polarization curves indicated polysaccharide esters could retard both hydrogen evolution reaction and metal dissolution reaction and that the inhibitory effect was concentration dependent. Besides, EIS studies demonstrated the corrosion resistance of mild steel in hydrochloric acid was enhanced by polymer additives. The observations on mild steel surface by SEM suggested the metallic substrate obtained good protection against corrosion in inhibitor-containing HCl solution. The adsorptive behavior of polymer molecules including physisorption and chemisorption obeyed Langmuir isotherm and UV-vis spectra revealed the formation of inhibitor-ion complex. The better performance of KGMH on corrosion inhibition was attributed to the easier transfer of π-electron or n-electron, which was confirmed by quantum chemical calculations.

Aeromicrobium camelliae sp. nov., isolated from Pu'er tea.

A novel Gram-reaction-positive, aerobic and non-spore-forming rod-shaped bacterial strain, YS17T, was isolated from ripened Pu'er tea. Growth of the strain was observed at 15-50 °C (optimum 30-37 °C) and at pH 5.5-10.5 (optimum 6.0-9.5). Phylogenetic analysis of 16S rRNA gene sequences indicated that the strain represented a member of the genus Aeromicrobium. The strains most closely related to YS17T were Aeromicrobium erythreum DSM 8599T, Aeromicrobium alkaliterrae JCM 13518T and Aeromicrobium ginsengisoli JCM 14732T, with 16S rRNA gene sequence similarities of 96.8, 96.8 and 96.7 %, respectively. DNA-DNA hybridization of YS17T with the type strains of the most closely related species, A. erythreum DSM 8599T, A. alkaliterrae JCM 13518T and A. ginsengisoli JCM 14732T, yielded reassociation values of 10.9, 16.8 and 10.9 %, respectively. The diagnostic diamino acid of the cell wall peptidoglycan was ll-diaminopimelic acid. The predominant menaquinones were menaquinone MK-9(H4) (76 %) and MK-8(H4) (17 %). The major fatty acids were C16 : 0, 10-methyl C18 : 0 and C18 : 1ω9c. The DNA G+C content of YS17T was 66 mol%. YS17T could be differentiated from recognized species of the genus Aeromicrobium on the basis of phenotypic characteristics, chemotaxonomic differences, phylogenetic analysis and DNA-DNA hybridization data. On the basis of evidence from the polyphasic analyses performed as part of this study a novel species, Aeromicrobium camelliae sp. nov., is proposed, with strain YS17T ( = CGMCC 1.12942T = JCM 30952T) as the type strain.

Pullulanibacillus pueri sp. nov., isolated from Pu'er tea.

A novel Gram-stain-positive, aerobic, endospore-forming, rod-shaped bacterial strain YN3(T) was isolated from ripened Pu'er tea. Phylogenetic analysis of 16S rRNA gene sequences showed that the strain belonged to the family Sporolactobacillaceae and was closely related to Pullulanibacillus naganoensis DSM 10191(T) (95.8% 16S rRNA gene sequence similarity) and Pullulanibacillus uraniitolerans DSM 19429(T) (95.4%). Growth of the strain was observed at 20-50 °C (optimum 30-37 °C), at pH 4.0-8.0 (optimum pH 5.0-6.0). The strain had a cell-wall type A1γ peptidoglycan with meso-diaminopimelic acid as the diagnostic diamino acid. The predominant menaquinone was menaquinone-7 (MK-7). The major fatty acids were anteiso-C15:0, anteiso-C17:0 and C18:1ω7c. The DNA G+C content of strain YN3(T) was 38.7 mol%. Strain YN3(T) could be differentiated from recognized species of the genus Pullulanibacillus based on phenotypic characteristics, chemotaxonomic differences, phylogenetic analysis and DNA-DNA hybridization data. On the basis of polyphasic evidence from this study, Pullulanibacilluspueri sp. nov., is proposed, with strain YN3(T) ( = CGMCC 1.12777(T ) = JCM 30075(T)) as the type strain.

Paenibacillus yunnanensis sp. nov., isolated from Pu'er tea.

A novel Gram-staining-positive, aerobic, endospore-forming, rod-shaped bacterial strain, YN2T, was isolated from ripened Pu'er tea. Phylogenetic analysis of 16S rRNA gene sequences showed that the strain represented a novel species of the genus Paenibacillus. The strains most closely related to strain YN2T were Paenibacillus vulneris JCM 18268T and Paenibacillus rigui JCM 16352T, with 16S rRNA similarities of 98.6 and 95.5 %, respectively. Chemotaxonomic data supported the affiliation of the new isolate to the genus Paenibacillus, including MK-7 as the major menaquinone, DNA G+C content of 51 mol%, cell-wall type A1γ (meso-diaminopimelic acid as the diagnostic diamino acid) and anteiso-C15 : 0 and iso-C16 : 0 as the major fatty acids. Major polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylmonomethylethanolamine and phospholipid. Strain YN2T could be differentiated from recognized species of the genus Paenibacillus based on phenotypic characteristics, chemotaxonomic differences, phylogenetic analysis and DNA-DNA hybridization data. On the basis of evidence from this polyphasic study, Paenibacillus yunnanensis sp. nov., is proposed, with strain YN2T ( = CGMCC 1.12968T = JCM 30953T) as the type strain.

Mineral nutrient imbalance, DNA lesion and DNA-protein crosslink involved in growth retardation of Vicia faba L. seedlings exposed to lanthanum ions.

Effects of mineral nutrient imbalance, DNA lesion and DNA-protein crosslink on growth of Vicia faba L. seedlings hydroponically cultivated in concentrations of extraneous lanthanum (La) for 20 days were investigated in the present experiment. The results showed that contents of La, Cu or K elements in roots generally changed synchronously with those in leaves, while Ca, Fe, Zn, Mg, Mn or P in the roots altered inversely to those in the leaves. Thus, the extraneous La led to redistribution and imbalance of mineral nutrient elements in the roots and leaves. DNA lesion and DNA-protein crosslink were investigated by single cell gel electrophoresis (SCGE) and sodium dodecyl sulfate/potassium (SDS/K+) precipitation methods, respectively. The results demonstrated that the increasing La induced DNA break and DNA-protein crosslinks (DPCs) in the seedlings. These results suggested that mineral nutrient imbalance, DNA lesion and DNA-protein crosslink were involved in the growth retardation and growth alteration of the seedlings, which may help to understand the mechanisms of rare earth elements (REEs) on plant growth.

Cellulosilyticum ruminicola, a newly described rumen bacterium that possesses redundant fibrolytic-protein-encoding genes and degrades lignocellulose with multiple carbohydrate- borne fibrolytic enzymes.

Cellulosilyticum ruminicola H1 is a newly described bacterium isolated from yak (Bos grunniens) rumen and is characterized by its ability to grow on a variety of hemicelluloses and degrade cellulosic materials. In this study, we performed the whole-genome sequencing of C. ruminicola H1 and observed a comprehensive set of genes encoding the enzymes essential for hydrolyzing plant cell wall. The corresponding enzymatic activities were also determined in strain H1; these included endoglucanases, cellobiohydrolases, xylanases, mannanase, pectinases, and feruloyl esterases and acetyl esterases to break the interbridge cross-link, as well as the enzymes that degrade the glycosidic bonds. This bacterium appears to produce polymer hydrolases that act on both soluble and crystal celluloses. Approximately half of the cellulytic activities, including cellobiohydrolase (50%), feruloyl esterase (45%), and one third of xylanase (31%) and endoglucanase (36%) activities were bound to cellulosic fibers. However, only a minority of mannase (6.78%) and pectinase (1.76%) activities were fiber associated. Strain H1 seems to degrade the plant-derived polysaccharides by producing individual fibrolytic enzymes, whereas the majority of polysaccharide hydrolases contain carbohydrate-binding module. Cellulosome or cellulosomelike protein complex was never isolated from this bacterium. Thus, the fibrolytic enzyme production of strain H1 may represent a different strategy in cellulase organization used by most of other ruminal microbes, but it applies the fungal mode of cellulose production.

Proteiniclasticum ruminis gen. nov., sp. nov., a strictly anaerobic proteolytic bacterium isolated from yak rumen.

Two strictly anaerobic, proteolytic bacterial strains, designated strain D3RC-2(T) and D3RC-3r, were isolated from a cellulose-degrading mixed culture enriched from yak rumen content. The strains were Gram-stain negative and non-spore-forming with cell sizes of 0.5-0.8 x 0.6-2.0 mum. The temperature range for growth was 24-46 degrees C (optimum 38-39 degrees C) and the pH range was between 5.6 and 8.7 (optimum 7.0-7.3). Both strains used soya peptone, tryptone, l-phenylalanine, l-leucine, l-methionine, l-serine, l-valine, l-threonine and l-histidine as carbon and nitrogen sources, but did not use any of the saccharides tested. The major fermentation products from PY medium were acetate, propionate and iso-butyrate. The DNA G+C contents of strains D3RC-2(T) and D3RC-3r were 41.0+/-0.1 mol% and 41.3+/-0.1 mol% (HPLC), respectively. Phylogenetic analysis based on 16S rRNA gene sequences revealed that the two strains represented a new phyletic sublineage within the family Clostridiaceae, with <93.8 % 16S rRNA gene sequence similarity to recognized species. On the basis of the phenotypic, genotypic and physiological evidence, strains D3RC-2(T) and D3RC-3r are proposed as representing a novel species of a new genus, for which the name Proteiniclasticum ruminis gen. nov., sp. nov. is proposed. The type strain of the type species is D3RC-2(T) (=AS 1.5057(T)=JCM 14817(T)).

Selenomonas bovis sp. nov., isolated from yak rumen contents.

Two strictly anaerobic, crescent-shaped bacterial strains, designated WGT and Ycb08, were isolated from a cellulose-degrading mixed culture enriched from yak rumen contents. The strains were Gram-negative, non-spore-forming and motile, with four to six flagella situated at the centre of the concave side of the cell. The cells were 0.9-1.1x4-6 microm. Growth was observed at 27-46 degrees C (optimum 39 degrees C) and pH 4.2-8.3 (optimum pH 7.0-7.2). Arabinose, glucose, mannose, cellobiose, lactose, sucrose, trehalose, melibiose, raffinose, salicin and aesculin were fermented. The end products of glucose fermentation were acetate, propionate and CO2. The G+C contents of strains WGT and Ycb08 were respectively 63.9+/-0.2 and 62.5+/-0.2 mol% (Tm). Phylogenetic analysis based on 16S rRNA gene sequences revealed that the two strains were related to the genera Mitsuokella and Selenomonas at similarity levels below 97%; however, they differed from members of the genus Mitsuokella in their flagellar arrangement. On the basis of phenotypic, genotypic and physiological evidence, strains WGT and Ycb08 are identified as members of a novel species of the genus Selenomonas, for which the name Selenomonas bovis sp. nov. is proposed. The type strain is WGT (=CGMCC 1.5073T=JCM 15470T).