Reversal of bone loss in mice by nongenotropic signaling of sex steroids

We show that sex steroids protect the adult murine skeleton through a mechanism that is distinct from that used to preserve the mass and function of reproductive organs. The classical genotropic actions of sex steroid receptors are dispensable for their bone protective effects, but essential for their effects on reproductive tissues. A synthetic ligand (4-estren-3alpha,17beta-diol) that reproduces the nongenotropic effects of sex steroids, without affecting classical transcription, increases bone mass and strength in ovariectomized females above the level of the estrogen-replete state and is at least as effective as dihydrotestosterone in orchidectomized males, without affecting reproductive organs. Such ligands merit investigation as potential therapeutic alternatives to hormone replacement for osteoporosis in both women and men [corrected].

Population-based, case-control study of blood C-peptide level and breast cancer risk

Insulin resistance has been suggested to be associated with an increased risk of breast cancer. Insulin sensitivity can be measured using blood C-peptide, a marker of insulin secretion. It is thus conceivable that blood C-peptide levels may be associated with breast cancer risk. To evaluate this hypothesis, we analyzed data from a subset (143 case-control pairs matched by age and status of menopause) of women who participated in the Shanghai Breast Cancer Study, a population-based, case-control study conducted in Shanghai during 1996-1998. Fasting blood samples were collected from study subjects to measure C-peptide levels. For cancer patients, the samples were collected before any cancer therapy. Conditional logistic regression was used to estimate adjusted odds ratios and 95% confidence intervals related to C-peptide levels. Breast cancer risk was increased with increasing levels of C-peptide (trend test, P = 0.01), with an odds ratio of 2.7 (95% confidence interval = 1.2-5.9) observed for the highest compared with the lowest tertile of C-peptide concentration after adjusting for body mass index and age at the first live birth. The risk was not altered after fully adjusting for other traditional risk factors for breast cancer. This positive association was observed in both pre and postmenopausal women and regardless of the levels of waist-to-hip ratio or body mass index. The results from this study were consistent with the insulin-resistance hypothesis for breast cancer and suggest that increased levels of C-peptide may contribute to the development of breast cancer.

Comparison of transcranial color-coded sonography and magnetic resonance angiography in acute ischemic stroke

BACKGROUND AND PURPOSE

This study was designed to assess the accuracy of transcranial color-coded sonography (TCCS) as compared to magnetic resonance angiography (MRA) for detecting intracranial arterial stenosis in patients with acute cerebral ischemia.

METHODS

The authors prospectively identified 120 consecutive patients admitted with acute ischemic stroke and performed both TCCS and MRA with a mean interval of 1 day. TCCS data (sampling depth, peak systolic and end diastolic angle-corrected velocity, mean angle-corrected velocity, and pulsatility index) for middle cerebral arteries (MCAs) were compared to MRA data and classified into 4 grades: normal (grade 1): normal caliber and signal; mild stenosis (grade 2): irregular lumen with reduced signal; severe stenosis (grade 3): absent signal in the stenotic segment (flow gap) and reconstituted distal signal; and possible occlusion (grade 4): absent signal. The cutoffs were chosen to maximize diagnostic accuracy.

RESULTS

Interobserver agreement for MRA grading resulted in a weighted-kappa value of 0.776. The rate of poor temporal window was 37% (89/240). Doppler signals were obtained in 135 vessels, and the angle-corrected velocities (peak systolic, end diastolic, mean) were significantly different (P = .001, P = .006, and P < .001) among the MRA grades: grade 1 (100, 47, 68 cm/s), grade 2 (171, 72, 110 cm/s), grade 3 (226, 79, 134 cm/s), grade 4 (61, 26, 39 cm/s). Additionally, an angle-corrected MCA peak systolic velocity > or = 120 cm/s correlates with intracranial stenosis on MRA (grade 2 or worse) with high specificity (90.5%; 95% confidence interval = 78.5%-96.8%) and positive predictive value (93.9%) but relatively low sensitivity (66.7%; 95% confidence interval = 61.2%-69.5%) and negative predictive value (55.1%).

CONCLUSION

Elevated MCA velocities on TCCS correlate with intracranial stenosis detected on MRA. An angle-corrected peak systolic velocity > or = 120 cm/s is highly specific for detecting intracranial stenosis as defined by significant MRA abnormality.

Synthesis and photodynamic action of diphenyl-2,3-dihydroxychlorin: a potential tumor photosensitizer

The synthesis, photophysical properties of diphenyl-2,3-dihydroxychlorin (DPCOH) and its photocytotoxicity to tumor cells are described. DPCOH exhibits photodynamic activity in terms of type I and type II mechanisms under irradiation. The quantum yield of (1)O(2) in CHCl(3) is 0.7. For the photocytotoxicity to tumor cells, DPCOH proved to be 200 times more potent than HPD, and the dark toxicity is low (dark IC(90)>32 microg/mL).

Dual control of LIF expression and LIF receptor function regulate Stat3 activation at the onset of uterine receptivity and embryo implantation

Leukemia inhibitory factor (LIF) expression in the uterus is essential for embryo implantation in mice. Here we describe the spatial and temporal regulation of LIF signaling in vivo by using tissues isolated from uteri on different days over the implantation period. During this time, LIF receptors are expressed predominantly in the luminal epithelium (LE) of the uterus. Isolated epithelium responds to LIF by phosphorylation and nuclear translocation of signal transducer and activator of transcription (Stat) 3, but not by an increase in mitogen-activated protein kinase levels. The related cytokines Il-6, ciliary neurotrophic factor, as well as epidermal growth factor, do not activate Stat3, although epidermal growth factor stimulates mitogen-activated protein kinase. In vivo Stat3 activation is induced by LIF alone, resulting in the localization of Stat3 specifically to the nuclei of the LE coinciding with the onset of uterine receptivity. The responsiveness of the LE to LIF is regulated temporally, with Stat activation being restricted to day 4 of pregnancy despite the presence of constant levels of LIF receptor throughout the preimplantation period. Uterine receptivity is therefore under dual control and is regulated by both the onset of LIF expression in the endometrial glands and the release from inhibition of receptor function in the LE.

Identification of antihypertensive peptides from peptic digest of two microalgae, Chlorella vulgaris and Spirulina platensis

The peptidic fractions that inhibited angiotensin I-converting enzyme (ACE) were separated from the peptic digests of 2 microalgae, Chlorella vulgaris and Spirulina platensis, by ion exchange chromatography and gel filtration. Oral administration of peptidic fractions into spontaneously hypertensive rats at 200 mg/kg of body weight resulted in marked antihypertensive effects. Further separation of the peptidic fractions by ODS high-performance liquid chromatography furnished the following active peptides: Ile-Val-Val-Glu (inhibitory against ACE with an IC(50) of 315.3 microM), Ala-Phe-Leu (63.8 microM), Phe-Ala-Leu (26.3 microM), Ala-Glu-Leu (57.1 microM), and Val-Val-Pro-Pro-Ala (79.5 microM) from C. vulgaris; Ile-Ala-Glu (34.7 microM), Phe-Ala-Leu, Ala-Glu-Leu, Ile-Ala-Pro-Gly (11.4 microM), and Val-Ala-Phe (35.8 microM) from S. platensis.

A recombinant chimera composed of repeat region RR1 of Mycoplasma hyopneumoniae adhesin with Pseudomonas exotoxin: in vivo evaluation of specific IgG response in mice and pigs

Using the binding and translocation domain of Pseudomonas exotoxin A [domain III deleted PE termed PE(DeltaIII)] as a vehicle, this study characterized and evaluated a novel application of PE toxin in Mycoplasma hyopneumoniae adhesin used as an immunogen. PCR and sequence analysis revealed that 16 copies of AAKPV(E) in tandem repeat region 1 (RR1) of M. hyopneumoniae 97kDa adhesion were successfully fused to the downstream of PE(DeltaIII) to create a subunit vaccine, i.e. PE(DeltaIII)-RR1. This chimeric protein, over-expressed in inclusion bodies of E. coli BL21(DE3)pLysS, was characterized by a monoclonal antibody (MAb) F2G5 prepared against RR1 of the 97kDa adhesin and was readily purified. The data indicated that the epitope recognized by MAb F2G5 was located in the structure of PE(DeltaIII)-RR1. Using ELISA and Western blot analyses, the specific IgG immune response against RR1 and whole adhesin in mice immunized with PE(DeltaIII)-RR1 was found more marked than that in mice immunized with the M. hyopneumoniae whole cells. Similarly, PE(DeltaIII)-RR1 also stimulated a remarkable IgG response against RR1 in pigs compared to that in pigs immunized with the conventional M. hyopneumoniae vaccine. The PE(DeltaIII)-RR1 would be potentially useful for the future development of a M. hyopneumoniae adhesin vaccine.

Semipreparative Capillary Electrochromatography

Capillaries with inner diameters of 550 microm have successfully been packed with 1.5-microm octadecyl silica particles using frits made of macroporous polymers by the UV photopolymerization of a solution of glycidyl methacrylate and trimethylolpropane trimethacrylate. This type of frit is found superior to one made of low-melting point poly(styrene-co-divinylbenzene) beads. Bubble formation is not observed to occur within these capillary columns under our experimental conditions. Separations can be achieved with sample injection volumes as high as 1 microL. To demonstrate its semipreparative use, a mixture of 500 nL of taxol (20 mM) and its precursor, baccatin III (30 mM), is separated using such a column with a Tris buffer.

Leukemia inhibitory factor can substitute for nidatory estrogen and is essential to inducing a receptive uterus for implantation but is not essential for subsequent embryogenesis

A stage critical in mammalian development is embryo implantation. At this point, the blastocyst establishes a close interaction with the uterine tissues, a step necessary for its continued embryonic development. In many mammalian species, including man, uterine expression of the cytokine, leukemia inhibitory factor (LIF) is coincident with the onset of implantation and in mice LIF is essential to this process. The reasons for implantation failure have not been established. Here we show in LIF-deficient mice that up to the onset of implantation, changes in uterine cell proliferation, hormone levels, blastocyst localization, as well as expression of lactoferrin and Muc-1, do not differ from wild-types. However, the uterus fails to respond to the presence of embryos or to artificial stimuli by decidualizing. In mice, implantation and decidualization are induced by nidatory estrogen. We show that uterine expression of LIF is up-regulated by estrogen and LIF can replace nidatory estrogen at inducing both implantation and decidualization in ovariectomized mice. Implantation of LIF-deficient embryos in the LIF-deficient females, with normal development to term is rescued by i.p. injection of LIF. Transient expression of LIF on D4 of pregnancy is therefore only required to induce a state of receptivity in the uterus permitting embryo implantation and decidualization. LIF is neither required by the embryo for development nor for the maintenance of pregnancy.

Identification of the copper-zinc superoxide dismutase activity in Mycoplasma hyopneumoniae

Copper-zinc superoxide dismutase (Cu/ZnSOD), a key enzyme in defense against toxic oxygen-free radicals, is widespread in eukaryotes and several species of gram-negative bacteria. The presence of this enzyme in Mycoplasma hyopneumoniae (M. hyopneumoniae), the primary pathogen of mycoplasmal pneumonia in pigs, was examined since the polyclonal antibody against bovine Cu/ZnSOD was dominantly cross-reactive with the M. hyopneumoniae Cu/ZnSOD from whole cellular proteins. In situ activity staining on SDS-PAGE showed that the molecular mass of M. hyopneumoniae Cu/ZnSOD in reducing form was approximately 17kDa. The presence of Cu and Zn ions at the active site of the enzyme was confirmed on the basis of inhibition by KCN and by H(2)O(2). The activity of M. hyopneumoniae Cu/ZnSOD on both SDS- and native-polyacrylamide gels was completely inhibited by 2mM KCN and the gels showed no iron-containing SOD (FeSOD) or manganese-containing SOD (MnSOD) in the crude extracts. The activity of M. hyopneumoniae Cu/ZnSOD in crude extract was 70units/mg protein and was 55% inhibited by 5mM KCN and 56% inactivated by 40mM H(2)O(2). This enzyme was growth-stage dependent and evidenced markedly higher production during the early log phase. Different expression levels of Cu/ZnSOD activity in field isolates were also detected. Taken together, the presence of Cu/ZnSOD in M. hyopneumoniae was identified for the first time.

Softening of fused-silica capillaries during particle packing

When a semipreparative capillary electrochromatography (CEC) capillary is packed with silica particles and exposed to solvent, its mechanical strength is markedly reduced. In our studies, a fused-silica capillary (internal diameter > 200 microm and wall thickness < 150 microm) was packed under pressure (approximately 200 psi) with spherical silica particles (1.5-5 microm) suspended in water or various common organic solvents. After one hour of exposure, the capillary can be readily deformed, and it keeps its deformed shape upon release of the force causing deformation. It is suggested that capillary softening is promoted through the propagation of internal microcracks that have been caused by action of the particles during packing in the presence of solvent. Application of a protective coating to the inside of the capillary is found to reduce or eliminate capillary softening.

Direct detection of crosslinks of collagen and elastin in the hydrolysates of human yellow ligament using single-column high performance liquid chromatography

Collagen and elastin are recognized as two major connective tissue proteins of human yellow ligament. In both collagen and elastin there are many kinds of intra- or intermolecular crosslinks. Pyridinoline (Pyr) and deoxypyridinoline (Dpyr) are mature crosslinks which maintain the structure of the collagen fibril. Desmosine (Des) and isodesmosine (Isodes) represent the major crosslinking components of elastin. Pentosidine (Pen), which is a senescent crosslink and one of the advanced glycation end products, accumulates with age in tissue proteins including collagen. We developed a direct and one-injection HPLC method to measure Pyr, Dpyr, Des, Isodes, and Pen in the hydrolysate of human yellow ligament. This method used one column and two detectors. Recovery rates of Pyr, Dpyr, Pen, Des, and Isodes were 86.4-98.3, 83.6-96.8, 78.7-95.6, 83.6-97.9, and 85.6-99.3%, respectively (n = 8). The intraassay coefficients of variation for Pyr, Dpyr, Pen, Des, and Isodes were 3.7, 4.1, 5.4, 4.5, and 4.7%, respectively (n = 8), and the interassay coefficients of variation for Pyr, Dpyr, Pen, Des, and Isodes were 4.4, 5.1, 4.9, 4.6 and 4.1%, respectively. Linear regression analysis showed the linearity (r = 0.99, P = 0.0001) of calibration line for each Pyr, Dpyr, Pen, Des, and Isodes. Using this method, we investigated age-related changes in the crosslinks of collagen and elastin in human yellow ligament. There was a significant correlation between Pen and age, but no correlations with Pyr, Dpyr, Des, and Isodes. We believe that this method is useful for investigating the content of these crosslinks in both collagen and elastin under various conditions.

Comparison of the concentrations of pentosidine in the synovial fluid, serum and urine of patients with rheumatoid arthritis and osteoarthritis

OBJECTIVE

Pentosidine, an advanced glycation end product (AGE), has recently been observed to be elevated in rheumatoid arthritis (RA). The aim was to elucidate which pentosidine levels, i.e. in serum, synovial fluid or urine, are more related to the disease status of RA.

METHODS

We measured levels of pentosidine in serum, synovial fluid or urine in RA compared with osteoarthritis (OA), and examined the relationship between pentosidine and RA disease activity. Subjects were 20 patients with RA and 22 patients with OA.

RESULTS

In total RA and OA patients combined, there was a significant correlation between pentosidine in serum, synovial fluid and urine. Pentosidine in serum and synovial fluid was significantly higher in RA than in OA. In RA, there were significant correlations between pentosidine in serum and synovial fluid and C-reactive protein, Lansbury index (LI) and erythrocyte sedimentation rate.

CONCLUSIONS

These results demonstrate that pentosidine levels in body fluids correlated with each other, and pentosidine in serum and in synovial fluid is associated with the systemic inflammatory activity of RA. Higher or similar concentrations of pentosidine in serum compared with synovial fluids indicate that the elevated pentosidine levels in serum in RA are not derived from the synovial fluid, but from an increase in the formation of pentosidine in the whole body in RA. Among body fluids, serum pentosidine was the superior indicator for RA disease status.

Transendothelial migration of lymphocytes in chronic lymphocytic leukaemia is impaired and involved down-regulation of both L-selectin and CD23

Chronic lymphocytic leukaemia (B-CLL) is characterized by a progressive accumulation of B lymphocytes in blood and bone marrow and high concentrations of soluble CD23 and L-selectin are found in the serum of these patients. In this study lymphocytes from normal subjects and patients with B-CLL were allowed to undergo transendothelial migration across confluent layers of human umbilical vein endothelial cells. Lymphocytes in B-CLL samples showed an impaired capacity to migrate while the minor proportion of normal T cells was enriched by a mean of 2.5-fold in the transmigrated lymphocytes. In contrast, the ratio of B to T lymphocytes in normal preparations was unchanged in the transmigrated population. The expression of adhesion molecules on B-CLL lymphocytes before and after transendothelial migration was studied by flow cytometry which showed that 71 +/- 5% of L-selectin was lost from the surface of transmigrated lymphocytes. T and B cells from normal subjects also showed a major loss of L-selectin after transmigration. B-CLL lymphocytes and normal B cells expressed CD23 but this molecule was down-regulated following transendothelial migration, whereas the expression of VLA-4, ICAM-1, LFA-1 and CD44 was unchanged. Lymphocytes incubated with oxidized ATP, an irreversible inhibitor of P2Z/P2X7 purinoceptors, retained their capacity for transendothelial migration and showed the same loss of L-selectin as control leukaemic lymphocytes. Our results show that B-CLL lymphocytes have impaired ability for transendothelial migration compared to normal peripheral blood lymphocytes. Moreover, transendothelial migration involves a universal loss of L-selectin and CD23 from lymphocytes which suggests that the high serum levels of soluble L-selectin and CD23 observed in B-CLL may be generated by shedding during the process of transendothelial migration.

Miller Fisher syndrome with central involvement: successful treatment with plasmapheresis

Miller Fisher syndrome is characterized by external ophthalmoplegia, ataxia, and areflexia. Most researchers favor a peripheral origin while others suggest a brainstem inflammatory lesion or a combination of central and peripheral demyelination. We report 2 cases of Miller Fisher syndrome with the typical triad of ataxia, areflexia, and ophthalmoplegia. Strong clinical evidence of central involvement included initial drowsiness, bilateral Babinski sign, and quadriparesis. Evoked potential studies showed prolongation of central conduction time. Plasmapheresis was performed to relieve respiratory failure in Patient 1 and to shorten the duration of nasogastric tube feeding due to severe bulbar palsy in Patient 2. Significant improvement of electrophysiologic parameters was recorded after plasmapheresis. Abnormal evoked potentials, together with clinical evidence of central nervous system abnormalities, support the hypothesis that there is a combination of peripheral and central involvement in Miller Fisher syndrome in our patients. Plasmapheresis is highly effective in relieving the profound neurological deficits of this atypical syndrome.

Assessment of coke oven emissions exposure among coking workers

Coking workers are regularly exposed to coke oven emissions, which consist primarily of polycyclic aromatic hydrocarbons and volatile organic compounds. This study measured the workers' exposure to the benzene soluble fraction of total particulates (BSF). The study population consisted of 88 coking workers as an exposure group and 59 referents. Personal breathing-zone samples of BSF and total particulates were taken from all study subjects for 3 consecutive days. The highest BSF concentrations were found among the topside oven workers (geometric mean; range) (microgram/m3): lidman (515; 72-18, 181), tar chaser (432; 51-4334), and larry car operator (185; 55-649). The lowest was 7 micrograms/m3 in the referents. Among the samples at the topside oven 84% exceeded the Occupational Safety and Health Administration standard (150 micrograms/m3 BSF). The percentage of BSF in total particulates varied across job classifications, ranging from 0.3% in wharfmen to 24% in tar chasers. Area sampling indicated that the BSF concentration at the topside area was sixtyfold higher than that at the administrative area, which was approximately 2 km from the coke oven plant.

Metastable polymorph of etoposide with higher dissolution rate

Etoposide, an anticancer drug, has low oral bioavailability because of low aqueous solubility, slow dissolution rate, and instability in acidic pH. Our objective was to enhance the aqueous solubility and dissolution rate of etoposide by polymorph formation. Preparation of various polymorphs of etoposide was attempted by crystallizing etoposide from organic solvents. Physicochemical properties of the crystals, namely, crystal habit, thermal behavior with hot-stage microscopy, thermal analysis by differential scanning calorimetry, IR spectrum, and solubility and dissolution rates, were examined. Based on the physicochemical characteristics, a metastable polymorph of etoposide was identified when it was crystallized from isopropanol. The metastable polymorph had an equilibrium solubility and intrinsic dissolution rate of 221 micrograms/ml and 16.3 micrograms/min/cm2, respectively; 1.9 and 1.7 times that of etoposide powder at 25 degrees C, respectively.

Switching transient analysis of a metal/ferroelectric/semiconductor switch diode with high speed response to infrared light

A thin PbTiO(3)-n-p(+) silicon switch diode has been developed, in which the switching voltage (the turned-on voltage) changes in proportion to the infrared light power. The diode has a rapid response time of 0.65 mus compared with other conventional infrared sensors. It is attributed to the rapid switching device structure and the smaller pyroelectric layer thickness, 50 nm. In this paper, we have analyzed the rapid switching transient response by using heat conduction and switching theory successfully. The experimental results are in agreement with the theoretical analysis.

Pentosidine in synovial fluid in osteoarthritis and rheumatoid arthritis: relationship with disease activity in rheumatoid arthritis

OBJECTIVE

Pentosidine is an advanced glycation endproduct formed by glycosylation and oxidation. Our aim was to develop a means to measure pentosidine in synovial fluid (SF), and to compare its concentration in SF in patients with osteoarthritis (OA) and rheumatoid arthritis (RA), and to investigate the relationship between its concentration in SF and the disease activity of RA.

METHODS

SF was collected from knee joints in 31 patients with RA and 40 with OA, who had hydrarthrosis. One patient with RA and 7 with OA who had the complication of diabetes mellitus or chronic renal failure made up the DM/CRF group, and the remaining patients made up the RA group (n = 30) and the OA group (n = 33). Pentosidine was measured by the direct HPLC method with column switching after hydrolysis of SF.

RESULTS

Pentosidine was detected in all SF and was greater in RA (83.9 +/- 46.0 nmol/l, mean +/- SD) than in OA (40.1 +/- 19.6 nmol/l). Three DM/CRF patients undergoing hemodialysis had markedly high pentosidine levels (482.5 +/- 280.8 nmol/l). There was a significant correlation between pentosidine and C-reactive protein (CRP), erythrocyte sedimentation rate, and Lansbury Index (p < 0.01). Patients with RA were divided into high and low activity groups according to the CRP and Lansbury Index. Pentosidine was significantly higher in the high activity group (CRP > or = 2.0 mg/dl and Lansbury Index > or = 50%) than in the low activity group (CRP < 2.0 and/or Lansbury Index < 50) (100.9 +/- 42.8 vs 58.5 +/- 39.6 nmol/; p = 0.0013).

CONCLUSION

Pentosidine in synovial fluid was higher in RA than in OA. Pentosidine levels in SF were related to the disease activity in RA.

Paracrine effects of hepatocyte growth factor/scatter factor on non-small-cell lung carcinoma cell lines

We have studied the mitogenic, motogenic and morphogenic effects of hepatocyte growth factor (HGF), also known as scatter factor (SF), on 15 non-small-cell lung carcinoma (NSCLC) cell lines that have had their ras genotype determined. HGF/SF stimulated proliferation in only three cell lines and exerted no mitogenic activity on six lines. The growth of the remaining six lines was inhibited. The mitogenic effects were not related to the ras genotype of these cell lines, but the inhibitory effect was more commonly observed in cell lines with relatively high levels of Met/HGF receptor (HGFR) expression. HGF/SF induced or enhanced both scatter activity on monolayer culture and single-cell invasion in collagen gels in approximately half of these cell lines. Although the ras genotype of tumour cells did not influence the HGF/SF-induced motogenic activity, cell lines with the mutant ras genotype more commonly demonstrated a spontaneous motogenic activity than those with the wild-type ras genotype. When tumour cells were grown in collagen gels, HGF/SF induced irregular branching extensions of cell aggregates formed by five out of eight adenocarcinoma cell lines, but significant lumen morphogenesis was distinctly absent. The presence of autocrine HGF/SF loop in these tumour cell lines did not influence their spontaneous or HGF/SF-induced mitogenic, motogenic or morphogenic activities. Overall, our data suggest that stimulation of cell motility, rather than proliferation or differentiation, is the predominant paracrine effect of HGF/SF on NSCLC cells in vitro.

The commissioning of a flexible low-cost multipurpose X-ray beamline at SRRC

A low-cost multipurpose X-ray beamline has been commissioned at the bending magnet B15 of the Synchrotron Radiation Research Center (SRRC). The beamline is constructed in such a way to accommodate the various needs of small research consortia, from universities or research institutes, whose requirements of a beamline facility are quite diverse while under limited funding support. Flexibility is the special feature of this beamline. It is capable of performing quick test measurements without a prolonged reviewing process. Switching between different techniques, such as white-beam irradiation, EXAFS and X-ray scattering, can be achieved within 1 h. Novel experiments, such as energy-dispersive small-angle scattering experiments and energy-dispersive reflectivity measurements, can also be performed.

A compact mirror manipulator in the SRRC beamline

A compact mirror manipulator which has high stiffness and is easily adjustable has been developed for new beamlines at SRRC. It consists of a vertical stem to support the mirror and allows for six-axis precise positioning. The rotation adjustment is designed with a minimum of cross-coupling between adjustments. An independent support is fixed to the ground to reduce vibration from the chamber and the pump. Some performance test results in vacuum and in atmosphere, including vibration, repeatability, long-term drift etc., are described in this paper.

A dynamic local bump system for producing synchrotron radiation with an alternating elliptical polarization

To facilitate high-sensitivity soft X-ray magnetic circular dichroism experiments, a dynamic local bump system has been developed at the SRRC storage ring. This system was devised to vary dynamically the vertical slope of the electron beam in a bending magnet, producing, in the electron orbit plane, soft X-rays with an alternating elliptical polarization. The local bump was created by using two pairs of vertical correctors located on each side of the bending magnet. The bump strength coefficient was obtained both from calculated estimation and from measured beam-response matrices. Control electronics for proper bump strength settings were designed to incorporate the existing orbit-corrector function. A corresponding graphic user interface was implemented so that the bump amplitude could be easily adjusted. The performance of this system is presented. Disturbance on the stored electron beam orbit was observed while flipping the corrector polarity during EPBM (elliptical polarization from bending magnets) operation. A local feedback loop, developed to eliminate such disturbance on other beamlines, is also described.

Effects of magnets with non-unit magnetic permeability on an elliptically polarizing undulator

This study employs the three-dimensional magnetostatic code TOSCA to assess numerically the effects of NdFeB magnets with non-unit magnetic permeability on an elliptically polarizing undulator. A reduction of a few percent of the on-axis magnetic field strength is predicted. In addition, a deviation of +/-100 G cm uncompensated dipole steering is predicted in a phase shift of 180 degrees for the elliptically polarizing undulator EPU5.6 (having a period length of 56 mm) at the minimum gap of 18 mm, which is related primarily to the configuration of the device end scheme. Results presented herein demonstrate that implementing an active compensation mechanism is a prerequisite for minimizing the orbit distortion during phase-shift adjustment, particularly for operating such a polarizing undulator in a third-generation machine having a median energy similar to that of the 1.5 GeV storage ring at SRRC.