284 research outputs found

    Purification and Pyrolysis of Bacterial Cellulose from Kombucha Pellicle

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    Kombucha SCOBY pellicle formed as a waste product in the kombucha tea fermentation industry can be used as a potential source for bacterial cellulose. The research compared four simple, scalable purification methods for the purification of this jelly-like cellulosic matrix containing bacteria, yeast cells, proteins, and polyphenols as impurities. The method using two successive 1.0 M NaOH washing at 90°C, followed by the treatment of 1.5 % (w/w) aq. NaOCl for 2h was the most effective method and gave the purified cellulose sample the highest Leucometer whiteness value of 81.4±4.8. The purified cellulose samples were analyzed by FT-IR, TGA, SEM, EDS, and water absorption at room temperature. After purified, the cellulose samples were pyrolyzed, and graphene oxide was directly produced at 600 to 800°C. The pyrolysis samples were analyzed by FT-IR, SEM, RAMAN, and ZETA potential

    On Fan's conjecture about 44-flow

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    Let GG be a bridgeless graph, CC is a circuit of GG. Fan proposed a conjecture that if G/CG/C admits a nowhere-zero 4-flow, then GG admits a 4-flow (D,f)(D,f) such that E(G)E(C)E(G)-E(C)\subseteq supp(f)(f) and supp(f)E(C)>34E(C)|\textrm{supp}(f)\cap E(C)|>\frac{3}{4}|E(C)|. The purpose of this conjecture is to find shorter circuit cover in bridgeless graphs. Fan showed that the conjecture holds for E(C)19.|E(C)|\le19. Wang, Lu and Zhang showed that the conjecture holds for E(C)27|E(C)|\le 27. In this paper, we prove that the conjecture holds for $|E(C)|\le 35.

    Efficient activation of T cells by human monocyte-derived dendritic cells (HMDCs) pulsed with Coxiella burnetii outer membrane protein Com1 but not by HspB-pulsed HMDCs

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    <p>Abstract</p> <p>Background</p> <p><it>Coxiella burnetii </it>is an obligate intracellular bacterium and the etiologic agent of Q fever; both coxiella outer membrane protein 1 (Com1) and heat shock protein B (HspB) are its major immunodominant antigens. It is not clear whether Com1 and HspB have the ability to mount immune responses against <it>C. burnetii </it>infection.</p> <p>Results</p> <p>The recombinant proteins Com1 and HspB were applied to pulse human monocyte-derived dendritic cells (HMDCs), and the pulsed HMDCs were used to stimulate isogenic T cells. Com1-pulsed HMDCs expressed substantially higher levels of surface molecules (CD83, CD40, CD80, CD86, CD54, and CD58) and a higher level of interleukin-12 than HspB-pulsed HMDCs. Moreover, Com1-pulsed HMDCs induced high-level proliferation and activation of CD4<sup>+ </sup>and CD8<sup>+ </sup>cells, which expressed high levels of T-cell activation marker CD69 and inflammatory cytokines IFN-γ and TNF-α. In contrast, HspB-pulsed HMDCs were unable to induce efficient T-cell proliferation and activation.</p> <p>Conclusions</p> <p>Our results demonstrate that Com1-pulsed HMDCs are able to induce efficient T-cell proliferation and drive T cells toward Th1 and Tc1 polarization; however, HspB-pulsed HMDCs are unable to do so. Unlike HspB, Com1 is a protective antigen, which was demonstrated by the adoptive transfer of Com1-pulsed bone marrow dendritic cells into naive BALB/c mice.</p

    Chronic Heat Stress Weakened the Innate Immunity and Increased the Virulence of Highly Pathogenic Avian Influenza Virus H5N1 in Mice

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    Chronic heat stress (CHS) can negatively affect immune response in animals. In this study we assessed the effects of CHS on host innate immunity and avian influenza virus H5N1 infection in mice. Mice were divided into two groups: CHS and thermally neutral (TN). The CHS treatment group exhibited reduced local immunity in the respiratory tract, including the number of pulmonary alveolar macrophages and lesions in the nasal mucosa, trachea, and lungs. Meanwhile, CHS retarded dendritic cells (DCs) maturation and reduced the mRNA levels of IL-6 and IFN-β significantly (P < .05). After the CHS treatment, mice were infected with H5N1 virus. The mortality rate and viral load in the lungs of CHS group were higher than those of TN group. The results suggest that the CHS treatment could suppress local immunity in the respiratory tract and innate host immunity in mice significantly and moderately increased the virulence in H5N1-infected mice

    A rapid and non-invasive method for measuring the peak positive pressure of HIFU fields by a laser beam

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    Based on the acousto-optic interaction, we propose a laser deflection method for rapidly, non-invasively and quantitatively measuring the peak positive pressure of HIFU fields. In the characterization of HIFU fields, the effect of nonlinear propagation is considered. The relation between the laser deflection length and the peak positive pressure is derived. Then the laser deflection method is assessed by comparing it with the hydrophone method. The experimental results show that the peak positive pressure measured by laser deflection method is little higher than that obtained by the hydrophone, confirming that they are in reasonable agreement. Considering that the peak pressure measured by hydrophones is always underestimated, the laser deflection method is assumed to be more accurate than the hydrophone method due to the absence of the errors in hydrophone spatial-averaging measurement and the influence of waveform distortion on hydrophone corrections. Moreover, noting that the Lorentz formula still remains applicable to high-pressure environments, the laser deflection method exhibits a great potential for measuring HIFU field under high-pressure amplitude. Additionally, the laser deflection method provides a rapid way for measuring the peak positive pressure, without the scan time, which is required by the hydrophones

    Preparation of Bioactive Glasses with Controllable Degradation Behavior and Their Bioactive Characterization

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    Bioactive glasses and ceramics have been widely investigated for bone repair because of their excel-lent bioactive characteristics. However, these biomaterials undergo incomplete conversion into a bone-like material, which severely limits their biomedical application. In this paper, borosilicate bioac-tive glasses were prepared by traditional melting process. The results showed that borosilicate glasses possessed high biocompatibility and bioactivity. In addition, when immersed in a 0.02 mol/L K2HPO4 solution, particles of a borate glass were fully converted to HA. The desirable conversion rate to HA may be achieved through the adjustment of the B2O3/SiO2 ratio. The results of XRD and FTIR analysis indicated that the degradation product was carbonate-substituted hydroxyapatite, which was similar to the inorganic component of bone

    Identification of novel driver mutations of the discoidin domain receptor 2 (DDR2) gene in squamous cell lung cancer of Chinese patients

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    BACKGROUND: Although many of the recently approved genomically targeted therapies have improved outcomes for patients in non–small-cell lung cancer (NSCLC) with lung adenocarcinoma, little is known about the genomic alterations that drive lung squamous cell cancer (SCC) and development of effective targeted therapies in lung SCC is a promising area to be further investigated. Discoidin domain receptor 2 (DDR2), is a novel receptor tyrosine kinases that respond to several collagens and involved in tissue repair, primary and metastatic cancer progression. METHODS: Expression of DDR2 mRNA was analyzed in 54 lung SCC tissues by qRT-PCR. Over-expression approaches were used to investigate the biological functions of DDR2 and its’ mutations in lung SCC cells. Conventional Sanger sequencing was used to investigate the mutations of DDR2 gene in 86 samples. The effect of DDR2 and its’ mutations on proliferation was evaluated by MTT and colony formation assays; cell migration and invasion was evaluated by trasnwell assays. Lung SCC cells stably transfected with pEGFP-DDR2 WT, pEGFP-DDR2-S131C or empty vector were injection into nude mice to study the effect of DDR2 and its’ mutation on tumorigenesis in vivo. Protein and mRNA expression levels of E-cadherin and MMP2 were determined by qRT-PCR and western blot analysis. Differences between groups were tested for significance using Student’s t-test (two-tailed). RESULTS: In this study, we found that DDR2 mRNA levels were significantly decreased in 54 lung SCC tissues compared with normal lung tissues. Moreover, there were 3 novel DDR2 mutations (G531V, S131C, T681I) in 4 patients and provide the mutation rate of 4.6% in the 86 patients with lung SCC. The mutation of S131C in DDR2 could promote lung SCC cells proliferation, migration and invasion via inducing MMP-2, but reducing E-cadherin expression. CONCLUSIONS: These data indicated that the novel DDR2 mutation may contribute to the development and progression of lung SCC and this effect may be associated with increased proliferation and invasiveness, at least in part, via regulating E-cadherin expression
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