A faster and more effective chrome tanning process assisted by microwave.

In leather manufacturing, microwave usually has the ability to strengthen the combination between collagen and chemicals and make the corresponding procedures faster and more effective. Although some studies clarified that tanning under microwave resulted in leather with better thermal stability, the process and leather properties of the pelt chrome tanning had not been elaborated in detail. Thus, in this study, pickled goat pelt was tanned for 5 h as a penetration procedure and then basified for another 5 h as a fixation procedure under microwave heating (MW) and water bath heating (WB); then, the changes in the pH of the chromium complexes as well as the leather chrome content were measured; finally, thermal behaviors and collagen structure of leather tanned under different methods were measured. The results indicated that microwave promoted chrome tanning agent penetration and exhaustion, consequently, chrome tanning process was faster and more effective. The leather tanned with microwave assistance had better hydrothermal and thermal stability as well as thermal decomposition resistance, indicating microwave leading to excellent tanning effect. Nevertheless, when microwave was applied in the chrome tanning process, the hierarchical structure of the leather and the collagen conformation including triple helix was not affected, and the combination pattern between ligands and chromium was also the same as that of the conventional. In brief, microwave could fasten the chrome tanning process and result in extraordinary tanning effect without damaging the leather structure; therefore, microwave might be a new method for promoting tanning efficiency and effect in future.

A review for tannery wastewater treatment: some thoughts under stricter discharge requirements.

To meet the extremely strict requirements of tannery wastewater, scientists need to urgently devise novel methods for controlling the quality of tannery wastewater. With these methods, it would be easier to promote sustainable development in the tannery industry. In this article, we summarize the following aspects of tannery wastewater: (i) the sources and characteristics of tannery wastewater, (ii) the main treatment methods (primary, secondary, and tertiary treatments), and (iii) resource utilization status of wastewater. In a brief introduction, we describe how tannery wastewater is currently subjected to single-pollutant treatment methods that strive to remove various toxic chemicals, including total nitrogen, total phosphorus, chloride ion, chromic salts, sulfur-containing compounds, and dyes. The methods for treating tannery wastewater is proposed. We anticipate that by using a proposed combination treatment techniques, the effluents in tannery wastewater can eventually be controlled to satisfy the stricter standards of wastewater disposal. Moreover, we also focus our efforts on recycling wastewater.

The mechanism of force transference in feet of children ages two to six.

The aim of this study was to design an algorithm to quantify the plantar force transference of children from ages 2-6. In total, 319 healthy children without abnormal gait patterns, foot deformities or injuries, able to walk independently, and with normal BMIs were recruited, and their plantar force distributions were measured. Their plantar areas were divided into ten parts: the hallux, toes #2-5, the first to fifth metatarsal heads (1st-5th MTH), the mid-foot (MF), medial heel (MH) and lateral heel (LH), in which a relative force-time integral (FTIrel) (%) was calculated. Our results show that the FTIrel was significantly transferred along either the transverse or longitudinal arches. The middle of the forefoot and the toe areas were the two main loading regions in children aged 2-3, and posterior to anterior FTIrel shifting was typical. However, anterior to posterior and lateral to medial FTI transferences were found in children aged 5-6, and major loading was found in the heel area. Further, loading in the mid-foot varied with the child's development and was observed to tend to decrease over time. Overall, according to the algorithm designed in this study, these results demonstrated that the development of the arches, both in transverse and longitudinal directions, had already begun in early stages of toddlerhood. Meanwhile, the arches were an important attractor engaged in the windlass mechanism while walking, and they played a major role as bridges to promote posterior to anterior and medial to lateral force transference.

Quantifying intra-limb coordination in walking of healthy children aged three to six.

The aim of this study was first to quantify intra-limb coordination and then to explore the gender differences of 180 healthy children aged 3-6. The children's joint Euler angles and angular velocities were measured and were used to calculate the phase angle (PA) and continuous relative phase (CRP). Firstly, a portrait of the mean and standard deviation (SD) of PA and CRP was applied to quantify coordination in the knees and ankles; then five key events in walking were selected and their inter-age differences were assessed by One-way ANOVA. Finally, gender differences were evaluated by GLM-Univariate. The significance level was 0.05 and confidence interval was 95%. Our results show that similar portraits of PA and CRP were found for knees and ankles from age 3-6; SD demonstrated that the PA and CRP in the knees and ankles were consistent with the increase in age. Moreover, θ_CRP(K-A) demonstrated that the direction reversal in heels off of those two joints in children aged 5 and 6 was earlier than those of age 3 and 4 and no inter-age significant differences were recorded for PA and CRP in either gait event. Finally, gender differences exist before the age of six, particularly in the transition period such as heel contact, toe off and during the mid swing. Overall, although further development such as gait control or balance is still improving, basic principle of intra-limb coordination has formed by the age of 3 and gender differences already existed before age of 6.

Application of the sheepskin mattress in clinical care for pressure relieving: a quantitative experimental evaluation.

This study aimed at quantitatively evaluating the effectiveness of sheepskin mattress (SSM) in pressure relieving, and then variables of peak pressure (mmHg) (PP), average pressure (AP) and contact area (cm(2)) (CA) at the total, back, sacrum and heel regions of 18 students supinely lying in a control mattress (CM), standard hospital mattress (SHM), SHM+SSM, SSM+CM and AM+CM were measured and contrasted. Paired-T test with a significant level of .05 shows that: the intervention of SSM significantly increased the total CA of SHM by 395.6 cm(2) and lowered its PP and AP by 8.8 and 2.0 mmHg respectively; further, the pressure distribution of SSM+CM was superior to that of AM+CM. The reliability of this study, with exception of the heel area, was proven to be good. Overall, the sheepskin mattress is an effective product in pressure reliving.

Approach for measuring the angle of hallux valgus.

BACKGROUND: There is medium correlation between the current anthropometric method and the radiography in the angle of hallux valgus (AoH) measurement, so this study aimed at designing a reliable and more accurate approach to measure the AoH (AoH). MATERIALS AND METHODS: Fifteen age, body weight, and height matched male students were included and those with foot disorders, deformities, or injuries were excluded from the study. The dorsal protrusions of the first metatarsal and the hallux were marked by palpating from three experienced observers; then their barefoot model in standing was collected by a three dimensional laser scanning system. The AoH was defined in the X-Y plane by the angle between the line joining the marks of centre of head and centre of base of metatarsal shaft and the one connecting the marks of the centre of metatarsal head and the hallux. The same procedure was repeated a week later. Besides, other measures based on the footprint, outline, and the radiography were also available for comparisons. Paired t-test, linear regression, and reliability analysis were applied for statistical analysis with significant level of 0.05 and 95% confidence interval. RESULTS: There were no significant differences recorded between the new method and the radiographic method (P = 0.069). The AoH was superior to the methods of footprint and outline and it displayed a relative higher correlation with the radiographic method (r = 0.94, r (2) = 0.89). Moreover both the inter and intraobserver reliabilities of this method were proved to be good. CONCLUSION: This new method can be used for hallux valgus inspection and evaluation.

Characterization of antioxidant polysaccharides from Auricularia auricular using microwave-assisted extraction.

Influence of microwave-assisted extraction (MAE) to the characterization and corresponding antioxidant activity of polysaccharides from Auricularia auricula (AAP) was determined. According to gas chromatography-mass spectrometry, high performance size exclusion chromatography, Fourier transform infrared spectroscopy, partial acid hydrolysis, periodic acid oxidation, Smith degradation, methylation analysis and atomic force microscopy, AAP was a heteropolysaccharide (composed of glucose, galactose, mannose, arabinose and rhamnose at the molar ratio of 37.53:1:4.32:0.93:0.91) with the molecular weight of 2.77×10(4) Da, observed as a spherical lump, and the backbone of AAP was mainly composed by glucose with (1→3) linked. Moreover, AAP exhibited significant in vitro antioxidant activity in scavenging free radicals (ABTS, DPPH, superoxide and hydroxyl radicals), in lipid peroxidation and reducing power assays. The present result suggested that AAP by MAE had low molecular weight and remarkable antioxidant capability.

Removal of hexavalent chromium in tannery wastewater by Bacillus cereus.

Bacillus cereus was used to remove chromium (Cr(VI)) from medium containing tannery wastewater under different conditions. The maximum rate of Cr(VI) removal was attained at a temperature of 37 °C, pH of 7.0-9.0, and biomass of 20 g/L when the initial Cr(VI) concentration was less than 50 mg/L. Under the optimum conditions, the Cr(VI) in tannery wastewater was treated with each cellular component of B. cereus to detect its ability to reduce Cr(VI). The results showed that the removal rate of Cr(VI) for the cell-free extracts could reach 92.70%, which was close to that of the whole cells (96.85%), indicating that the Cr(VI) reductase generated by B. cereus is primarily intracellular. Additionally, during continuous culture of the B. cereus, the strain showed good consecutive growth and removal ability. After treatment of 20 mg/L Cr(VI) for 48 h, the B. cereus was observed by SEM and TEM-EDX. SEM images showed that the B. cereus used to treat Cr(VI) grew well and had a uniform cellular size. TEM-EDX analysis revealed large quantities of chromium in the B. cereus cells used to treat Cr(VI). Overall, the results presented herein demonstrate that B. cereus can be used as a new biomaterial to remove Cr(VI) from tannery wastewater.

Stabilization of chromium: an alternative to make safe leathers.

In this study, the original causes for hexavalent chromium presence in the leather were first evaluated by ageing of chromium(III) solutions and chrome tanned hide powder (50 degrees C, UV lightening at 340 nm, 0-36 h). The results showed that the trivalent chromium at instable coordination state was easy to convert into hexavalent chromium in high pH environment, and the probability of the oxidation increased in this order: multi-coordinate chromium, mono-coordinate chromium, and free chromium. For this reason, the process for stabilizing chromium in the leather was designed with the specific material, which was mostly consisted of the reducers and the chelating agents. After treated with the developed process, these leathers were aged (50 degrees C, UV irradiance as 0.68 W/m(2) at 340 nm, 0-72 h) to estimate chromium(VI) presence. Hexavalent chromium was not found in these treated leathers even if the leathers were aged for 72 h. Moreover, the physical and mechanical properties for the leathers varied little after treating. In a word, an inherent safe and effective process was proved to avoid the formation of hexavalent chromium in the leather.