The dynamic behavior of bacterial macrofibers growing with one end prevented from rotating: variation in shaft rotation along the fiber's length, and supercoil movement on a solid surface toward the constrained end

BACKGROUND: Bacterial macrofibers twist as they grow, writhe, supercoil and wind up into plectonemic structures (helical forms the individual filaments of which cannot be taken apart without unwinding) that eventually carry loops at both of their ends. Terminal loops rotate about the axis of a fiber's shaft in contrary directions at increasing rate as the shaft elongates. Theory suggests that rotation rates should vary linearly along the length of a fiber ranging from maxima at the loop ends to zero at an intermediate point. Blocking rotation at one end of a fiber should lead to a single gradient: zero at the blocked end to maximum at the free end. We tested this conclusion by measuring directly the rotation at various distances along fiber length from the blocked end. The movement of supercoils over a solid surface was also measured in tethered macrofibers. RESULTS: Macrofibers that hung down from a floating wire inserted through a terminal loop grew vertically and produced small plectonemic structures by supercoiling along their length. Using these as markers for shaft rotation we observed a uniform gradient of initial rotation rates with slopes of 25.6°/min. mm. and 36.2°/min. mm. in two different fibers. Measurements of the distal tip rotation in a third fiber as a function of length showed increases proportional to increases in length with constant of proportionality 79.2 rad/mm. Another fiber tethered to the floor grew horizontally with a length-doubling time of 74 min, made contact periodically with the floor and supercoiled repeatedly. The supercoils moved over the floor toward the tether at approximately 0.06 mm/min, 4 times faster than the fiber growth rate. Over a period of 800 minutes the fiber grew to 23 mm in length and was entirely retracted back to the tether by a process involving 29 supercoils. CONCLUSIONS: The rate at which growing bacterial macrofibers rotated about the axis of the fiber shaft measured at various locations along fibers in structures prevented from rotating at one end reveal that the rate varied linearly from zero at the blocked end to maximum at the distal end. The increasing number of twisting cells in growing fibers caused the distal end to continuously rotate faster. When the free end was intermittently prevented from rotating a torque developed which was relieved by supercoiling. On a solid surface the supercoils moved toward the end permanently blocked from rotating as a result of supercoil rolling over the surface and the formation of new supercoils that reduced fiber length between the initial supercoil and the wire tether. All of the motions are ramifications of cell growth with twist and the highly ordered multicellular state of macrofibers

Evolution of H9N2 influenza viruses from domestic poultry in Mainland China

AbstractH9N2 viruses have circulated in domestic poultry in Mainland China since 1994, and an inactivated vaccine has been used in chickens to control the disease since 1998. The present study analyzed 27 H9N2 avian influenza viruses that were isolated from chickens and ducks from 1996 to 2002. Infection studies indicated that most of the viruses replicate efficiently but none of them is lethal for SPF chickens. However, these viruses exhibit different phenotypes of replication in a mouse model. Five viruses, including 4 early isolates and one 2000 isolate, are not able to replicate in mice; 14 viruses replicate to moderate titers in mouse lungs and cause less than 5% weight loss, while other 8 viruses could replicate to high titers in the lungs and 7 of them induce 10–20% weight loss of the mice on day 5 after inoculation. Most of the viruses isolated after 1996 are antigenically different from the vaccine strain that is currently used in China. Three viruses isolated in central China in 1998 are resistant to adamantanes. Phylogenetic analysis revealed that all of the viruses originated from CK/BJ/1/94-like virus and formed multiple genotypes through complicated reassortment with QA/HK/G1/97-, CK/HK/G9/97-, CK/SH/F/98-, and TY/WI/66-like viruses. This study is a description of the previously uncharacterized H9N2 avian influenza viruses recently circulating in chickens and ducks in Mainland China. Our findings suggest that urgent attention should be paid to the control of H9N2 influenza viruses in animals and to the human's influenza pandemic preparedness

CT and clinical features for distinguishing endophytic clear cell renal cell carcinoma from urothelial carcinoma

PURPOSEWe aimed to characterize the clinical and multiphase computed tomography (CT) features of the distinguishing endophytic clear cell renal cell carcinoma (ECCRCC) from endophytic renal urothelial carcinoma (ERUC).METHODSData from 44 patients (35 men and 9 women) with ECCRCC and 21 patients (17 men and 4 women) with ERUC were retrospectively assessed. The mean patient age was 55 years (48.25- 59.50 years) and 68 years (63.00-73.00 years), respectively. Univariate and multivariate logistic regression analyses were performed to determine independent predictors for ECCRCC and to construct a predictive model that comprised clinical and CT characteristics for the differential diagnosis of ECCRCC and ERUC. Differential diagnostic performance was assessed using the area under the receiver operating characteristic curve (AUC).RESULTSThe independent predictors of ECCRCC were heterogeneous enhancement (odds ratio [OR]=0.027, P=.005), hematuria (OR for gross hematuria=53.995, P=.003; OR for microscopic hematuria=31.126, P = .027), and an infiltrative growth pattern (OR=24.301, P = .022). The AUC of the predictive model was 0.938 (P < .001, sensitivity=84.10%, specificity=95.20%), which had a better diagnostic performance than heterogeneous enhancement (AUC=0.766, P=.001, sensitivity=81.82%, specificity=71.43%), hematuria (AUC=0.786, P < .001, sensitivity=81.82%, specificity=66.67%), and infiltrative growth pattern (AUC=0.748, P=.001, sensitivity=90.48%, specificity=59.09%).CONCLUSIONThe independent predictors, as well as the predictive model of CT and clinical characteristics, may assist in the differential diagnosis of ECCRCC and ERUC and provide useful information for clinical decision-making

Analysis of Aroma Differences between Hunan Compressed Dark Tea and Raw Dark Tea

To explore the differences in aroma between compressed dark tea and raw dark tea, headspace solid phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS) and sensory evaluation were used to analyze and compare the flavor quality and aroma composition of four kinds of Hunan compressed dark tea and raw dark tea stored under the same condition. The results showed that compared with the raw tea, the pine smoke-like aroma and the crude, green, sour and other miscellaneous off-odors of the compressed tea were weaker, the concentration of aroma was higher and more long-lasting, and the stable flavor was more prominent. Furthermore, the contents of 15 unpleasant aroma components such as (E,Z)-2,4-heptadienal, 2,3,5,6-tetramethylpyrazine, and acetic acid in the compressed tea decreased, while the contents of 11 pleasant aroma components such as (E,E)-2,4-heptadienal, saffron aldehyde and butylated hydroxytoluene increased. Through principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA), 10 characteristic aroma components which could potentially be used to discriminate between compressed dark tea and raw dark tea were identified including acetic acid, 2-butyl-1-octanol, 1,2,3-trimethylbenzene, (Z)-2-decylenaldehyde, linalool, octanol, α-terpineol, 3-tridecanone, (E,Z)-2,6-nonadienol and phenylethanol. These results can provide a reference for further research on the quality formation mechanism of Hunan dark tea and the development of dark tea products

Correlation between intercalated magnetic layers and superconductivity in pressurized EuFe2(As0.81P0.19)2

We report comprehensive high pressure studies on correlation between intercalated magnetic layers and superconductivity in EuFe2(As0.81P0.19)2 single crystal through in-situ high pressure resistance, specific heat, X-ray diffraction and X-ray absorption measurements. We find that an unconfirmed magnetic order of the intercalated layers coexists with superconductivity in a narrow pressure range 0-0.5GPa, and then it converts to a ferromagnetic (FM) order at pressure above 0.5 GPa, where its superconductivity is absent. The obtained temperature-pressure phase diagram clearly demonstrates that the unconfirmed magnetic order can emerge from the superconducting state. In stark contrast, the superconductivity cannot develop from the FM state that is evolved from the unconfirmed magnetic state. High pressure X-ray absorption (XAS) measurements reveal that the pressure-induced enhancement of Eu's mean valence plays an important role in suppressing the superconductivity and tuning the transition from the unconfirmed magnetic state to a FM state. The unusual interplay among valence state of Eu ions, magnetism and superconductivity under pressure may shed new light on understanding the role of the intercalated magnetic layers in Fe-based superconductors

Research for Inertia Response and Primary Frequency Regulation Ability of Wind Turbine

[Introduction] Large-scale connection of wind power to the power grid poses great challenges to the stability (especially frequency stability) of grid operation.In order to solve the problem of inadequate frequency regulation capability caused by large-scale connection of wind power to the power grid and improve the frequency adaptability of wind power grid connection, wind turbines need to have frequency regulation function and response timeliness. [Method] This paper adopted a frequency regulation system scheme based on rotor kinetic energy and pitch angle reserve, which could provide active support for the power grid quickly and accurately during the power grid frequency change. Firstly, the main control algorithm was designed based on the theoretical analysis of inertia response and primary frequency regulation algorithm logic. Then, the functional verification was carried out on the co-simulation platform. Finally, the actual test was carried out in a project.[Result] The simulation and test results showed that the frequency regulation system scheme based on rotor kinetic energy and pitch angle reserve could cope with a variety of grid frequency changes and quickly provided active support. [Conclusion] The frequency regulation system scheme of wind turbines can perform a fast inertia response (with the response time less than 500 ms) and primary frequency regulation response (with the response time less than 5 s) under various frequency change conditions and provide active support for the power grid, which can help recover the grid frequency and effectively improve the frequency adaptability of wind turbines

Association of triglyceride-glucose index with the prevalence of cardiovascular disease in malnourished/non-malnourished patients: a large cross-sectional study

BackgroundNumerous investigations have demonstrated a strong association between the TyG (triglyceride-glucose) index, which is derived from lipid and glucose levels in the bloodstream, and the onset and progression of cardiovascular diseases (CVD). Blood glucose and blood lipids are affected by nutritional status, and few studies have explored whether the correlation between TyG index and the risk of CVD is affected by nutritional status.AimsTo investigate the connection between TyG index and the risk of CVD among individuals with varying nutritional statuses.MethodA total of 19,847 were included in the analysis, of which 15,955 participants were non-malnourished and 3,892 patients were malnourished. According to the TyG index quartile, the patients were categorized into four groups. Logistic regression analysis and restricted cubic spline was used to study the relationship between TyG index and the risk of CVD in normal and malnourished populations.ResultsThe results of the restricted cubic spline showed that the TyG index was positively associated with the risk of CVD in the non-malnourished population. The TyG index showed a U-shaped association with the risk of CVD in malnourished people. The result is consistent with that of logistic regression (Malnutrition: Group 2: OR: 1.14; 95% CI: 0.85–1.53; Group 3: OR: 1.36; 95% CI: 1.03–1.79; Group 4: OR: 1.72; 95% CI:1.31–2.25, P for trend &lt;0.001; Non-malnutrition: Group 2: OR: 0.82; 95% CI: 0.46–1.48; Group 3: OR: 0.88; 95% CI: 0.49–1.57; Group 4: OR: 1.45; 95% CI:0.83–2.52, P for trend =0.067).ConclusionsThe association between the TyG index and the risk of CVD varied depending on the nutritional states. When using TyG index to assess the risk of CVD, stratification combined with nutritional status helps to more accurately screen patients at high risk of CVD

Assembly and Misassembly of Cystic Fibrosis Transmembrane Conductance Regulator: Folding Defects Caused by Deletion of F508 Occur Before and After the Calnexin-dependent Association of Membrane Spanning Domain (MSD) 1 and MSD2

Cystic fibrosis transmembrane conductance regulator (CFTR) is a polytopic membrane protein that functions as a Cl− channel and consists of two membrane spanning domains (MSDs), two cytosolic nucleotide binding domains (NBDs), and a cytosolic regulatory domain. Cytosolic 70-kDa heat shock protein (Hsp70), and endoplasmic reticulum-localized calnexin are chaperones that facilitate CFTR biogenesis. Hsp70 functions in both the cotranslational folding and posttranslational degradation of CFTR. Yet, the mechanism for calnexin action in folding and quality control of CFTR is not clear. Investigation of this question revealed that calnexin is not essential for CFTR or CFTRΔF508 degradation. We identified a dependence on calnexin for proper assembly of CFTR's membrane spanning domains. Interestingly, efficient folding of NBD2 was also found to be dependent upon calnexin binding to CFTR. Furthermore, we identified folding defects caused by deletion of F508 that occurred before and after the calnexin-dependent association of MSD1 and MSD2. Early folding defects are evident upon translation of the NBD1 and R-domain and are sensed by the RMA-1 ubiquitin ligase complex