Search

Frequency adjusting precision is an important performance indicator of miniaturized rubidium atomic clock (RAC) in some applications, such as the case in GPS disciplined RAC systems. This parameter is determined mainly by the resolution of digital phase-locked loop (PLL) in the frequency multiplier-synthesizer. To improve the frequency adjusting precision of a miniaturized high-performance high-stability RAC developed by our research group, the original RAC circuit scheme was improved by designing and implementing a new decimal frequency multiplier-synthesizer based on a high precision direct digital frequency synthesizer (DDS). Tests showed that this design achieved high precision frequency adjustment, while maintained the frequency stability as high as the original scheme.

Objective: To investigate DNA methylation (DNAm) status of dickkopf‐associated protein 1 (DKK‐1) in ossified hip capsule synovium and serum among patients with ankylosing spondylitis (AS). Methods: Western blot was applied to detect the level of DKK‐1 protein expression in hip joint capsule tissues from four patients with AS as well as four patients with femoral neck fracture (FNF) caused by trauma as control. DKK‐1 gene promoter methylation (GPM) was examined by methylation‐specific polymerase chain reaction. Reverse transcription‐polymerase chain reaction was performed to examine the messenger RNA (mRNA) levels of DKK‐1, β‐catenin, and Wnt3a in both tissue and serum. The DNAm status of serum DKK‐1 was measured among 36 patients with AS and syndesmophytes (AS + syndesmophytes group), 40 patients with AS but no syndesmophyte (AS group), and 42 healthy individuals (control group). Also, the serum levels of DKK‐1 were measured by enzyme‐linked immunosorbent assay. The modified New York criteria (mNYC) together with the modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS) were adopted to examine the radiographic progression of AS. The receiver operating characteristic (ROC) curve was applied to investigate the diagnostic value of the methylation rate of DKK‐1 with regard to radiographic progression. Results: The expressions of DKK‐1 protein and mRNA in hip joint capsule tissues of AS patients were significantly lower, while DKK‐1 GPM rate, β‐catenin mRNA, and Wnt3a mRNA were markedly higher when compared with FNF group. For serum samples, the DKK‐1 methylation rate was significantly higher in AS+ syndesmophytes group in contrast to AS group and healthy controls. Serum levels of DKK‐1 protein and mRNA in AS with syndesmophytes group were markedly decreased, while β‐catenin mRNA and Wnt3a mRNA expressions were significantly increased than AS with no syndesmophyte group and the healthy control group. AS patients in Grade 4 showed a significantly higher serum DKK‐1 GPM rate than those in Grade 3 based on mNYC. Serum DKK‐1 GPM level was markedly and positively correlated with mSASSS. Serum levels of DKK‐1 in AS+ syndesmophytes group were markedly lower compared with AS but no syndesmophyte group and healthy controls. ROC curve analysis indicated that serum DKK‐1 methylation rate serves as a decent indicator for AS radiographic progression. Conclusion: DNAm of DKK‐1 may correlate with pathological bone formation in AS, which may provide new strategies for the treatment of AS abnormal bone formation. [ABSTRACT FROM AUTHOR]

We have analyzed the effects of various normally distributed nonuniformities of sampled fiber Bragg gratings on the reflective spectra and group time delay. Through numerical simulations we have drawn the following conclusions: (1) the magnitude of nonuniformity with normal distribution of the fiber's average refractive-index modulation [bar][delta][n.sub.eff] greatly influences the characteristics of both reflective spectra and group time delay, whose suggested precision varies from 20% to 10%; (2) the nonuniformities of sampling periods P and sampling lengths L are important factors that influence the characteristics of the group time delay, and the accepted tolerance of dimensional precision of both P and L are [+ or -] 4 [micro]m; and (3) the tolerance of nonuniformity of the sampling period's chirp coefficient is high, and its precision can be as great as 100% with few adverse effects. OCIS codes: 060.2330, 060.2340, 050.2770.

• The design approach of UHP-ECC was comprehensively reviewed. • The mechanical properties of UHP-ECC were systematically discussed. • Cost-performance evaluation on the mixture proportion of UHP-ECC was performed. Ultra-high performance engineered cementitious composite (UHP-ECC) is gaining significant interest among civil engineering researchers, owing to its excellent mechanical performance. This review is carried out to systematically summarize the design approach and fundamental factors influencing the mechanical properties of UHP-ECC, specifically the fiber parameters, water-binder ratio, nanomaterials, mineral admixtures, cyclic load, and strain rate. Besides, shrinkage performance and shrinkage mitigation approach of UHP-ECC are also discussed in this paper. Finally, the structural application of UHP-ECC is summarized. Based on the Technique for Order Performance by Similarity to Ideal Solution (TOPSIS) method, the economic evaluation of the mixture proportion of current available UHP-ECCs is conducted to suggest the mixture proportions for the design of highly cost-effective UHP-ECC. [ABSTRACT FROM AUTHOR]

• The incorporation of superabsorbent polymer (SAP) and united expansion agent (UEA) could effectively mitigate the autogenous shrinkage. • The inclusion of SAP reduced the fracture toughness by increasing the matrix porosity, thus improving the multiple cracking and strain-hardening behavior of UHP-ECC. • Pseudo strain hardening index of each specimen was conducted to explain the effect of incorporation of SAP and UEA on the tensile properties of UHP-ECC. Ultra-high performance engineered cementitious composites (UHP-ECC) had received extensive attention in recent years in material as well as the field of structural rehabilitation and strengthening due to its excellent mechanical properties, such as high strength and high ductility. However, the high shrinkage is one of the bottlenecks limiting widespread engineering application of UHP-ECC. In this paper, superabsorbent polymers (SAP) and United expansion agent (UEA) were introduced to mitigate UHP-ECC shrinkage. And the effect of different amounts of SAP with UEA on the shrinkage and tensile properties of UHP-ECC are investigate. Results indicate that the incorporation of SAP and UEA can effectively mitigate the autogenous shrinkage, and the autogenous shrinkage decreased with the increasing SAP dosage; however, drying shrinkage had the opposite trend. The incorporation of SAP and UEA improved the tensile ductility of UHP-ECC. The inclusion of SAP reduced the fracture toughness by increasing the matrix porosity, which produced more micro-cracking sources, thus improving the multiple cracking and strain-hardening behaviors of UHP-ECC. Conversely, the incorporation of SAP decreased the fiber/matrix interaction as well as decreasing the effective number of polyethylene (PE) fibers in the cross-section, thus reducing the tensile strength. Finally, pseudo strain hardening index of each specimen was conducted to analyze the effect of SAP with UEA on the tensile properties of UHP-ECC. [ABSTRACT FROM AUTHOR]

To study the effect of early intervention of liver-soothing and Blood-activating decoction combined with acupuncture in improving neurological functions, depressive symptom and life quality of patients with post-stroke depression, and compare with fluoxetine hydrochloride. Specifically, 63 patients with post-stroke depression were randomly divided into the traditional Chinese medicine (TCM) acupuncture group (31 cases) and the western medicine group (32 cases). On the basis of the conventional treatment of the primary disease, the TCM acupuncture group was treated with liver-soothing and blood-activating decoction and acupuncture, while the western medicine group was treated with fluoxetine hydrochloride for four weeks. In the follow-up visit six months later, scores of HAMD, NIHSS and SS-QOL were observed. The scores of HAMD and NIHSS of both groups were significantly decreased (P < 0.01), while the scores of SS-QOL increased significantly, with a notable difference compared with that before the treatment (P < 0.01). Specifically, the TCM acupuncture group's was superior to the western medicine group (P < 0.05). The study suggests that the early intervention of liver-soothing and blood-activating decoction combined with acupuncture on patients with post-stroke depression has the effect in relieving depression symptom and improving neurological functions, thereby improving their quality of life and prognosis.

Objective: To look for the natural ligand(s) of human triggering receptor expressed on myeloid cell-1 (TREM-1), in order to provide the theoretical basis for elucidation of the pathogenesis of sepsis., Methods: Neutrophils and monocytes isolated from human peripheral blood were treated with heat-inactivated Staphylococcus aureus, Pseudomonas aeruginosa, Mycobacterium tuberculosis, Staphylococcus aureus L-form or Pseudomonas aeruginosa L-form respectively for 24 hours. The cell wall was extracted from Staphylococcus aureus, Pseudomonas aeruginosa and Mycobacterium tuberculosis by ultrasound. Neutrophils and monocytes were isolated and treated with the cell wall respectively for 24 hours. Neutrophils and monocytes were isolated and treated with three main components from bacterial cell wall (polysaccharides, lipids and proteins) respectively for 24 hours. The level of TREM-1 mRNA was measured with fluorescent quantitative polymerase chain reaction (PCR), and the concentrations of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 beta (IL-1 beta) were measured with enzyme-linked immunosorbent assay (ELISA)., Results: The TREM-1 mRNA level and the concentrations of TNF-alpha and IL-1 beta in cell supernatant of neutrophils and monocytes were upgraded when treated with cell, cell wall and cell wall polysaccharides of Staphylococcus aureus and Pseudomonas aeruginosa. Compared with the blank control group, the TREM-1 mRNA level of neutrophils and monocytes was upgraded to (3.86+/-0.20)-fold and (5.15+/-0.56)-fold respectively when treated with cell wall polysaccharides of Staphylococcus aureus (both P<0.05); the TREM-1 mRNA level of neutrophils and monocytes was upgraded to (4.03+/-0.15)-fold and (7.22+/-0.73)-fold respectively when treated with cell wall polysaccharides of Pseudomonas aeruginosa (both P<0.05). The effect could be attenuated by the addition of LP17 which could bind TREM-1 ligand. This attenuating effect was not found when the cells were treated with cell, cell wall or cell wall polysaccharides of Mycobacterium tuberculosis., Conclusion: The study provides the evidence that TREM-1 natural ligand(s) is present on cell wall of bacteria including Staphylococcus aureus and Pseudomonas aeruginosa, and it might be polysaccharides.

The trace elements, Ca, Mg, Ba, Co, Cd, Cu, Mn, Pb, Sr, Zn, Al, Fe, Ni, Ti, Si and V, in K2CrO4 were simultaneously determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). Optimum spectral lines were selected for each analyzed element. The matrix effect was studied and eliminated through matrix matching. The results show that the linear correlations of standard curves are good (R2 = 0.998 6-1.000) under the determined conditions. The recoveries of standard addition are in the range of 83.7%-113.0%, and the relative standard deviations are lower than 9.48% (n = 9). Detection limits of these impurities are in the range of 0.075-2. 625 mg x kg(-1). The method is rapid, simple, accurate and credible, so it can be used for the determination of impurities in K2 CrO4 product. The results also show that there is relatively high content of Ca, Mg, Al and Si in K2 CrO4 product, so the K2 CrO4 product can't be directly used for the ion membrane electrochemical synthesis of chromic anhydride and the product must be taken for further purification.