Impact of changes in collagen construction and molecular state on integrin - binding properties.

The interaction between the integrin and collagen is important in cell adhesion and signaling. Collagen, as the main component of extracellular matrix, is a base material for tissue engineering constructs. In tissue engineering, the collagen structure and molecule state may be altered to varying degrees in the process of processing and utilizing, thereby affecting its biological properties. In this work, the impact of changes in collagen structure and molecular state on the binding properties of collagen to integrin α2ß1 and integrin specific cell adhesion were explored. The results showed that the molecular structure of collagen is destroyed under the influence of heating, freeze-grinding and irradiation, the triple helix integrity is reduced and molecular breaking degree is increased. The binding ability of collagen to integrin α2ß1 is increased with the increase of triple helix integrity and decays exponentially with the increase of molecular breaking degree. The collagen molecular state can also influences the binding ability of collagen to cellular receptor. The collagen fibrils binding to integrin α2ß1 and HT1080 cells is stronger than to collagen monomolecule. Meanwhile, the hybrid fibril exhibits a different cellular receptor binding performance from corresponding single species collagen fibril. These findings provide ideas for the design and development of new collagen-based biomaterials and tissue engineering research.

Diaphragmatic ultrasound can help evaluate pulmonary dysfunction in patients with stroke.

Objective: Pulmonary dysfunction after stroke is increasingly gaining attention from clinical and rehabilitation specialists. However, owing to cognitive and motor dysfunction in patients with stroke, determining the pulmonary function of these patients remains challenging. The present study aimed to devise a simple method for an early evaluation of pulmonary dysfunction in patients with stroke. Methods: Overall, 41 patients with stroke in the recovery period (stroke group) and 22 matched healthy controls (control group) were included in the study. We first collected data regarding baseline characteristics for all participants. Furthermore, the participants with stroke were examined using additional scales, such as the National Institutes of Health Stroke Scale (NIHSS), Fugl-Meyer assessment scale (FMA), and modified Barthel Index (MBI). Subsequently, we examined the participants with simple pulmonary function detection and diaphragm ultrasound (B-mode). Ultrasound indices calculated were as follows: the thickness of the diaphragm under the position of functional residual capacity (TdiFRC), the thickness of the diaphragm under the position of forced vital capacity (TdiFVC), thickness fraction, and diaphragmatic mobility. Finally, we compared and analyzed all data to identify group differences, the correlation between pulmonary function and diaphragmatic ultrasound indices, and the correlation between pulmonary function and assessment scale scores in patients with stroke, respectively. Results: Compared with the control group, patients in the stroke group exhibited lower values for indices of pulmonary and diaphragmatic function (p < 0.001), except for TdiFRC (p > 0.05). The majority of the patients with stroke had restrictive ventilatory dysfunction, as indicated by a significantly higher incidence ratio (36 in 41 patients) than that in the control group (0 in 22 patients) (p < 0.001). Moreover, significant correlations were found between pulmonary function and diaphragmatic ultrasound indices (p < 0.05), with the strongest correlation between TdiFVC and pulmonary indices. In the stroke group, pulmonary function indices were negatively correlated with the NIHSS scores (p < 0.001) and positively correlated with the FMA scores (p < 0.001). No (p > 0.05) or weak (p < 0.05) correlation was found between pulmonary function indices and the MBI scores. Conclusion: We found that patients with stroke had pulmonary dysfunction even in the recovery period. Diaphragmatic ultrasound can be used as a simple and effective tool for detecting pulmonary dysfunction in patients with stroke, with TdiFVC being the most effective index.

Removal of COD and colour in real pharmaceutical wastewater by photoelectrocatalytic oxidation method.

In this study, TiO2/Ni photo-anode and multi-walled carbon nano-tubes (MWCNTs) air cathode were prepared by the dip-coating method, and the photoelectrocatalytic degradation of real pharmaceutical wastewater was investigated in the self-made reactor. The combination of the TiO2/Ni electrode and MWCNTs air cathode was adopted to treat the pharmaceutical wastewater by the process of photoelectrocatalysis. Various operational parameters to achieve optimum efficiency of this photoelectrocatalytic degradation system are presented, such as applied bias voltage, NaCl concentration, pH and different degradation methods. Under the optimal conditions, the removal of chemical oxygen demand (COD) and colour are 93.5% and 78.5% respectively. The possible roles of the anode-cathode on the reactions and the probable mechanisms of effect were also discussed. The photoelectrocatalytic technology can be used for the long-term treatment of real pharmaceutical wastewater.

Photoelectrocatalytic degradation of high COD dipterex pesticide by using TiO2/Ni photo electrode.

A TiO2 thin film electrode deposited on porous nickel net (TiO2/Ni) was prepared by the sol-gel method, and the surface morphology, crystal structure features and the grain size were characterized by Field emission scan electron microscopy (FESEM) and X-ray diffraction (XRD). The photoelectrocatalytic system was set up using a UV high-pressure mercury lamp as the light source, TiO2 coated on foamed nickel as photo anode, Pt sheet as counter electrode and the pesticide dipterex in synthetic wastewater. Various factors that influence the photoelectrocatalytic decomposition of dipterex pesticide have been studied, such as degradation time, the type of electrolyte, current density, original pH value and different degradation methods. The prepared catalysts were employed to photoelectrocatalytically degrade the pesticide dipterex under UV irradiation, comparing the results with photocatalytic degradation and electrochemical oxidation. The results indicated that under the optimal conditions of 0.02 mol/L NaCl as the supporting electrolyte, current density = 2.5 mA/cm2, pH 6.0 and dipterex pesticide 40 mg/L, and reaction time 2 hr, dipterex chemical oxygen demand (COD) removal rate and organophosphorous conversion of up to 82.6% and 83.5% were achieved, respectively. The method of photoelectrocatalytic degradation is more efficient than photocatalysis and electrochemical oxidation. The possible roles of the electrolytes on the reactions and probable mechanisms were also discussed.

Reactivity of nickel in soils: evidence of retention kinetics.

The bioavailability and mobility of nickel (Ni) is highly dependent on the mechanisms associated with Ni adsorption-desorption and its kinetics in soils. To examine the characteristics of Ni retention and release, kinetic sorption batch experiments were performed on three soils having different properties, followed by Ni desorption using successive dilutions. Sorption of Ni by all soils was highly nonlinear and strongly kinetic, where the rate of Ni retention was rapid initially and was followed by gradual or somewhat slow retention behavior with increasing reaction time. Desorption of Ni was strongly irreversible and hysteretic in nature, indicating lack of equilibrium retention and/or irreversible or slowly reversible processes. A sequential extraction procedure provided evidence that a significant amount of Ni was irreversibly adsorbed on all soils. A nonlinear multireaction model with equilibrium-kinetic-irreversible reaction sites successfully described the retention (adsorption) and subsequent release of Ni on the different soils. The model was also capable of predicting Ni desorption kinetics based on adsorption data sets only.

Mercury adsorption-desorption and transport in soils.

Kinetic sorption and column miscible displacement transport experiments were performed to quantify the extent of retention/release and the mobility of mercury in different soils. Results indicated that adsorption of mercury was rapid and highly nonlinear with sorption capacities having the following sequence: Sharkey clay > Olivier loam > Windsor sand. Mercury adsorption by all soils was strongly irreversible where the amounts released or desorbed were often less than 1% of that applied. Moreover, the removal of soil organic matter resulted in a decrease of mercury adsorption in all soils. Adsorption was described with limited success using a nonlinear (Freundlich) model. Results from the transport experiments indicated that the mobility of mercury was highly retarded, with extremely low concentrations of mercury in column effluents. Furthermore, mercury breakthrough curves exhibited erratic patterns with ill-distinguished peaks. Therefore, mercury is best regarded as strongly retained and highly "immobile" in the soils investigated. This is most likely due to highly stable complex formation (irreversible forms) and strong binding to high-affinity sites. In a column packed with reference sand material, a symmetric breakthrough curve was obtained where the recovery of mercury in the leachate was only 17.3% of that applied. Mercury retention by the reference sand was likely due to adsorption by quartz and metal-oxides.

[Effect of low molecular weight organic acids on inorganic phosphorus transformation in red soil and its acidity].

Red soil samples collected from southern Hubei province and northern Jiangxi province were tested to analyze their inorganic phosphorus fractions, pH and active aluminum after incubated with added various organic acids. The results indicated that application of organic acids increased the content of Ca2-P in both red soils, in the order of citric acid > malic acid > succinic acid > acetic acid, did not affect the contents of Ca8-P and Ca10-P, but usually reduced Fe-P, Al-P and O-P. The pH values of the soils treated by organic acids, except for acetic acid, were reduced by 0.65-1.96, compared with the control. Soil active Al extracted with 0.02 mol.L-1 CaCl2 in treatments with citric, malic and succinic acid was 5.7-51.3 times as the control, and Al extracted with 1 mol.L-1 KCl also increased 4.0-67.3 times. However, acetic acid had little influence on active soil Al. It was concluded that in red soils, organic acid could improve phosphorus availability, but enhance the soil toxicity caused by active Al.