[High accuracy sample positioning system for hard X-ray microprobe].

A novel sample offline positioning system was developed for hard X-ray micro-focus beamline (BL15U1) at Shanghai Synchrotron Radiation Facility (SSRF). The positioning system is composed of three parts: off-line sample microscope system, on-line sample experiment system, and high-precision positioning sample holder. It makes a potent combination of the on-line X-ray fluorescence imaging and the off-line microscopic examination in three steps: compiling of control program, positioning of sample holder, and conversion of the two coordinates. It's the first time in the domestic synchrotron radiation facilities to achieve sample offline positioning in micron scale. The system helps the researchers find the object of study in micro zone quickly and accurately, when they study the micro characteristics of materials using synchrotron radiation micro X-ray beam. The gold mesh was used as an object of study. By comparing the differences of coordinates of gold mesh nodes between pictures from offline microscope and pictures from X-ray fluorescence mapping, the accuracy of the offline positioning system was verified. The results showed that the average errors of X-axis and Z-axis were 1.3 and 2.5 microm respectively, using the positioning method. It was demonstrated that the sample offline positioning system not only is suitable for these applications with high efficiency, but also supply hard X-ray micro-focus beamline with the technical preparations of sample automatic focusing method.

[Effects of simvastatin on the left ventricular hypertrophy in spontaneously hypertensive rats and its relationship with the expression of protein kinase B].

OBJECTIVE: To investigate the effects of simvastatin on left ventricular hypertrophy (LVH) in spontaneously hypertensive rats (SHRs) and its possible mechanism. METHODS: Sixteen male SHRs were randomly divided into 2 equal groups: treatment group and SHR control to be given simvastatin or glucose-normal saline by oral gavage for 10 weeks. Eight Wistar-Kyoto (WKY) rats were given normal saline as normal controls. Blood pressure was measured before the experiment and then once every week after the beginning of experiment. By the end of the experiment the rats were killed and their hearts were taken out to measure the left ventricle weight/body weight. RT-PCR was used to detect the mRNA expression of atrial natriuretic peptide (ANP) and of protein kinase B (PKB) in myocardium. Western blotting was used to examine the protein expression of PKB. RESULTS: (1) The systolic blood pressure of the SHR normal control and treatment groups were 221 mm Hg +/- 10 mm Hg and 217 mm Hg +/- 8 mm Hg respectively (P > 0.05) and the systolic pressure of the normal control group was 126 +/- 6 mm Hg, significantly lower than those of the 2 SHR groups (both P < 0.01). (2) The LVW/BW values of the SHR control group were 3.04 mg/g +/- 0.12 mg/g, 3.73 mg/g +/- 0.08 mg/g, and 4.10 mg/g +/- 0.13 mg/g in the normal control group, SHR treatment group and SHR control group respectively with significant difference between any 2 groups (all P < 0.01). (3) The mRNA expression levels of ANP were 0.44 +/- 0.33, 0.27 +/- 0.03, and 0.17 +/- 0.33 in the SHR control group, SHR treatment group, and normal control group respectively (P < 0.01 or P < 0.05). (4) The mRNA expression levels of PKB were 0.45 +/- 0.05, 0.32 +/- 0.03, and 0.19 +/- 0.02 in the SHR control group, SHR treatment group, and normal control group respectively (P < 0.01 or P < 0.05). CONCLUSION: Simvastatin reverses LVH and myocyte phenocyte transformation in the SHRs with the possible mechanism of decreasing the expression level of PKB.

Serum hepatic enzyme manifestations in patients with severe acute respiratory syndrome: retrospective analysis.

AIM: To evaluate the hepatic function in patients with severe acute respiratory syndrome (SARS) and possible causes of hepatic disorder in these patients. METHODS: One hundred and eighty-two patients with SARS were employed in a retrospective study that investigated hepatic dysfunction. Liver alanine aminotransferase (ALT), aspartate aminotransferase (AST) and lactic dehydrogenase (LDH) were analyzed in these patients. Patients with different hospital treatments were further investigated. RESULTS: Of the 182 patients, 128(70.3%) had abnormal ALT activity, 57(31.3%) had abnormal AST activity and 87(47.8%) had abnormal LDH activity. The peak of elevated hepatic enzyme activities occurred between the sixth day and the tenth day after the first day of reported fever. Of the 182 patients, 160(87.9%) had been treated with antibiotics, 137(75.2%) with Ribavirin, and 115(63.2%) with methylpredisolone. There was no statistically significant correlation between the duration of Ribavirin treatment and hepatic dysfunction. CONCLUSION: Abnormal liver functions were common in patients with SARS and could be associated with virus replication in the liver.

Template-derived carbon: an unexpected promoter for the creation of strong basicity on mesoporous silica.

Template-derived carbon is demonstrated to effectively promote the creation of strong basicity on mesoporous silica, for the first time. New materials owning ordered mesoporous structure, strong basicity, and excellent catalytic activity are thus successfully constructed at low temperatures, which are impossible to achieve using conventional methods.

Three one-dimensional coordination polymers based on 1,1'-bis(pyridin-4-ylmethyl)-2,2'-bi-1H-benzimidazole and HgX2 (X = Cl, Br and I).

A new 2,2'-bi-1H-benzimidazole bridging organic ligand, namely 1,1'-bis(pyridin-4-ylmethyl)-2,2'-bi-1H-benzimidazole, C26H20N6, L or (I), has been synthesized and used to create three new one-dimensional coordination polymers, viz. catena-poly[[dichloridomercury(II)]-µ-1,1'-bis(pyridin-4-ylmethyl)-2,2'-bi-1H-benzimidazole], [HgCl2(C26H20N6)]n, (II), and the bromido, [HgBr2(C26H20N6)]n, (III), and iodido, [HgI2(C26H20N6)]n, (IV), analogues. Free ligand L crystallizes with two symmetry-independent half-molecules in the asymmetric unit and each L molecule resides on a crytallographic inversion centre. In structures (II)-(IV), the L ligand is also positioned on a crystallographic inversion centre, whereas the Hg centre resides on a crystallographic twofold axis. Compound (I) adopts an anti conformation in the solid state and forms a two-dimensional network in the crystallographic bc plane via π-π and C-H...π interactions. The three Hg(II) coordination complexes, (II)-(IV), have one-dimensional zigzag chains composed of L and HgX2 (X = Cl, Br and I), and the Hg(II) centres are in a distorted tetrahedral [HgX2N2] coordination geometry. Complexes (III) and (IV) are isomorphous, whereas complex (II) displays an interesting conformational difference from the others, i.e. a twist in the flexible bridging ligand.

Low-temperature fabrication of mesoporous solid strong bases by using multifunction of a carbon interlayer.

Mesoporous solid strong bases are highly promising for applications as environmentally benign catalysts in various reactions. Their preparation attracts increasing attention for the demand of sustainable chemistry. In the present study, a new strategy was designed to fabricate strong basicity on mesoporous silica by using multifunction of a carbon interlayer. A typical mesoporous silica, SBA-15, was precoated with a layer of carbon prior to the introduction of base precursor LiNO3. The carbon interlayer performs two functions by promoting the conversion of LiNO3 at low temperatures and by improving the alkali-resistant ability of siliceous host. Only a tiny amount of LiNO3 was decomposed on pristine SBA-15 at 400 °C; for the samples containing >8 wt % of carbon, however, LiNO3 can be entirely converted to strongly basic sites Li2O under the same conditions. The guest-host redox reaction was proven to be the answer for the conversion of LiNO3, which breaks the tradition of thermally induced decomposition. More importantly, the residual carbon layer can prevent the siliceous frameworks from corroding by the newly formed strongly basic species, which is different from the complete destruction of mesostructure in the absence of carbon. Therefore, materials possessing both ordered mesostructure and strong basicity were successfully fabricated, which is extremely desirable for catalysis and impossible to realize by conventional methods. We also demonstrated that the resultant mesoporous basic materials are active in heterogeneous synthesis of dimethyl carbonate (DMC) and the yield of DMC can reach 32.4%, which is apparently higher than that over the catalysts without a carbon interlayer (<12.9%) despite the same lithium content. The strong basicity, in combination with the uniform mesopores, is believed to be responsible for such a high activity.

[Comprehensive study of lead pollution in atmospheric aerosol of Shanghai].

The lead contamination, lead species and source assignment were studied by a combination of several analytical techniques such as Proton-induced X-ray emission analysis (PIXE), Proton microprobe (micro-PIXE), Inductively coupled plasma-mass spectrometry (ICP-MS) and extended X-ray absorption fine structure (EXAFS) techniques. The results indicate that the lead concentration in the air of Shanghai gradually decreased over the last years. The atmospheric lead concentration of PM10 in the winter of 2002 was 369 ng x m(-3), which had declined by 28% in 2001, and in the winter of 2003 it decreased further to 237 ng x m(-3). The main lead species in the samples collected in the winter of 2003 were probably PbCl2, PbSO4 and PbO. The source apportionment was calculated in terms of the combination of lead isotope ratios and lead mass balance method, assisted by single particle analysis with micro-PIXE and pattern recognition. The results suggest that the major contributors of atmospheric lead pollution in Shanghai are the coal combustion dust; the metallurgic dust and vehicle exhaust particles, with a contribution around 50%, 35% and 15%, respectively. It probably is the first time to give a city a quantitative estimation of lead pollution contribution from emission sources. The influence from leaded gasoline was still present in the atmosphere by four or five years after the phasing out of leaded gasoline.