Corrosion behaviour of die-cast AZ91D magnesium alloys in sodium sulphate solutions with different pH values

The corrosion behaviours of die-cast AZ91D magnesium alloys were investigated in 0.1 mol/L sodium sulphate （Na 2 SO 4 ） solutions with different pH values. The corrosion rates, morphologies, and compositions of the corrosion products were studied by means of scanning electron microscopy （SEM）, Fourier transform infrared spectroscopy （FTIR）, and X-ray diffractometry （XRD）. The results indicate that the order of corrosion rates in Na 2 SO 4 solutions with various pH values is pH 2pH 4pH 7pH 9pH 12. The corrosion rates in acidic solutions are higher than those in alkaline solutions, and the corrosion products are mainly magnesium hydroxide （Mg（OH） 2 ） and hydrated sulphate pickeringite （MgAl 2 （SO 4 ） 4 ·22H 2 O）. The results also indicate that the solution pH can influence the corrosion rate and morphology of corrosion products. Chloride ions and sulphate ions have different pitting initiation time.

Attenuation of dextran sodium sulphate induced colitis in matrix metalloproteinase-9 deficient mice

AIM: To study whether matrix metalloproteinase-9 (MMP-9) is a key factor in epithelial damage in the dextran sodium sulphate (DSS) model of colitis in mice.METHODS: MMP-9-deficient and wild-type (wt) mice were given 5% DSS in drinking water for 5 d followed by recovery up to 7 d. On d 5 and 12 after induction of colitis, gelatinases, MMP-2 and MMP-9, were measured in homogenates of colonic tissue by zymography and Western blot, whereas tissue inhibitor of metalloproteinases (TIMPs) were measured by reverse zymography. The gelatinolytic activity was also determined in supernatants of polymorphonuclear leukocytes (PMN) isolated from mice blood. Moreover, intestinal epithelial cells were stimulated with TNF-α to study whether these cells were able to produce MMPs. Finally, colonic mucosal lesions were measured by microscopic examination. RESULTS: On d 5 of colitis, the activity of MMP-9 was increased in homogenates of colonic tissues (0.24 ± 0.1 vs 21.3 ± 6.4, P < 0.05) and PMN from peripheral blood in wt (0.5 ± 0.1 vs 10.4 ± 0.7, P < 0.05), but not in MMP-9-deficient animals. The MMP-9 activity was also up-regulated by TNF-α in epithelial intestinal cells (2.5 ± 0.5 vs 14.7 ± 3.0, P < 0.05). Although colitis also led to increase of TIMP-1 activity, the MMP-9/TIMP-1 balance remained elevated. Finally, in the MMP-9-deficient colitic mice both the extent and severity of intestinal epithelialinjury were significantly attenuated when compared with wt mice. CONCLUSION: We conclude that DSS induced colitis is markedly attenuated in animals lacking MMP-9. This suggests that intestinal injury induced by DSS is modu-lated by MMP-9 and that inhibition of this gelatinase may reduce inflammation.

The Effect of Additives on Crystal Size of Sodium Sulphate

1 Introduction Anhydrous sodium,mainly produced in the United States,Canada,Japan,is indispensable commodities and raw materials in daily life and industry.In recent years,anhydrous sodium sulfate of general size was much oversupplied[1].However particles anhydrous sodium sulphate of large size is not adequate to the demand for its

Selective debenzylation of benzyl esters by silica-supported sodium hydrogen sulphate

A new debenzylation of benzyl esters by silica-supported sodium hydrogen sulfate is described. The debenzylation could be achieved selectively and efficiently in good to excellent yields without affecting sensitive functional groups such as nitro, unsaturated bonds, and ethyl ester.

Renal Toxicity of Nickel,Sodium Lauryl Sulphate and Their Combination after Dermal Application in Guinea Pigs

The guinea pigs were dermally exposed to nickel (Ni), sodium lauryl sulphate (SLS) and in their combination for 7 and 14 days. The exposure to Ni and SLS produced changes in enzymes and lipid peroxidation in kidney. The exposure to Ni or SLS depicted slight changes while combined exposure to Ni plus SLS exhibited more degenerative changes in kidney. The result of the study suggests that industrial workers and/or populations exposed simultaneously to Ni and SLS produces more damage to kidney.

Preparation and Characterization of Gelatins from Two Sudanese Edible Insects

Gelatins extracted from two edible insects Aspongubus viduatus （melon bug） and Agonoscelis pubescens （sorghum bug） were studied. The two insects showed 27.0 and 28.2% crude protein, respectively. Extraction of gelatin using hot water gave high yield followed by mild acid and distilled water extraction, respectively. SDS-PAGE pattern showed low molecular weight chains, and the two gelatins contained protein with molecular weight of 40 kDa as main component. The differential scanning calorimetry thermograms results confirm no difference between extraction methods concerning the extracted gelatin quality. FTIR spectra of melon and sorghum bug gelatins were similar and the absorption bands were situated in more than 6 bands in melon bug gelatin and only 6 bands in sorghum bug gelatin. Amide II bands of gelatins from both melon and sorghum bug appeared at around 1554 cm^-1, while Amide I bands （1734-1632 cmt） appeared only in melon bug method 2 （MB2） and melon bug method3 （MB3）. Microstructures of the insect gelatin examined with the scanning electron microscope showed that melon bug exhibited the finest gelatin network with very small voids. Melon bug gelatin showed finer structure with smaller protein strands and voids than sorghum bug gelatin.

Validation of Metformin Hydrochloride in Human Plasma by HPLC-Photo Diode Array （PDA） for Application of Bioequivalence Study

A sensitive and specific high performance liquid chromatography （HPLC） method was developed and validated for the simultaneous determination of metformin hydrochloride （HCI） in human plasma. The HPLC method consists of isocratic eluation with a mixture of 60% buffer （10 mM sodium dihyrogenphosphate-10 mM sodium dodecyl sulphate） and 40% acetonitrile with final pH 7.0 with flow rate of 1.0 mL/min on a Kromasil~ Akzo Nobel RP-18 （4.6 mm ID ~ 250 mm, 5 ~tm） column at an ambient temperature. Photo diode array detection was performed in program mode at 234 rim. The analyte and diazepam as internal standard （IS） were extracted from plasma using 10% trichloroacetic acid. The assay was linear over the therapeutic concentration range of 20-2,500 ng/mL for metformin HCI with correlation coefficient of r = 0.9999. Limit of quantitation was 20 ng/mL. The results obtained for intraJinter day accuracy and precision complied very well with the generally accepted criteria for bio-analytical assay. The method was applied to bioequivalence （BE） study of metformin HCI in healthy Indonesian volunteers after treatment with 750 mg XR metformin HCI. This BE study shows that the two formulations are equivalent so that they were therapeutically interchangeable for each other.

Bilayer characteristics and cholesterol effects of sodium dialkylmethyl sulphates

The gel-liquid crystal phase transitions(PT)in bilayers formed from a series of synthetic sodium dialkylmethyl sulphates have been studied by both fluorescence and differential scanning cal- orimetry(DSC)methods,which are between the transitions of the corresponding phospholipids and the quarternary ammonium salt bilayers possessing the same hydrocarbon chains.The fluorescence I_3/I_1 ratio(R)of probe pyrene in the bilayers decreases below and increases above the transitions respectively with increasing the chain length of the surfactants in the series SUDS,SPHS,and SHOS.In addition, the difference between the R above and below the transition(⊿R)is larger in the suspension prepared at the temperature above that of the transition than in that formed at room temperature.Intermem- brahe transfer and transbilayer migration(flip-flop)evaluated by means of DSC of a mixture of equi- molar aqueous dispersions of SHOS and SPHS as well as by ESR of bilayer embedding the stable free radical 4-HD-TEMPO in the presence and absence of excess ascorbic acid take place noticeably only at the temperature above that of the transitions.Cholesterol has shown the same effect on ⊿R as to decrease the length of the alkyl chain of the surfactants.It also causes a decrease of the fluorescence Intensity ratio of excimer to monomer of pyrene,I_e/I_m(S),in both phase.The results are discussed in terms of bilayer structure,chain fluidity,and permeability of water.

Investigation of phase-change materials for interior temperature regulation in public transport

Regulating the indoor temperature of public transport on hot sunny days is a prime concern,as both the external and internal heat sources play an active role in heat gain.Experimental studies have been carried out on a bus model using sodium sulphate decahydrate as a phase-change material(PCM)that is placed in between the ceiling and the roof.Studies are conducted on a sunny day and also for different cases of external(300-W surface heater)and internal(25-W light bulb)heat sources.The results show that PCM,in the presence of an external heat source,can help to keep the indoor temperature lower and delay the time period for increasing the temperature by absorbing heat during the phase change.On the other hand,the presence of the internal heat source contributes to a detrimental effect on the indoor temperature,which gradually increases with the elapse of time.With the combination of the external and internal heat sources,it is found that the internal heat source plays a dominating factor to raise the indoor temperature.It is revealed from the experimental results that a 12.7-mm single layer and a single PCM are not enough to counter the internal heat of 25 W unless the thickness of the PCM layer is increased to delay the increase in the indoor temperature.An additional PCM layer with a lower melting temperature could be placed at the inner portion of the ceiling to have effective thermal-energy storage by absorbing the substantial heat gain from the internal heat sources.