In this work, an all-fiberized and narrow-linewidth fiber amplifier with record output power and near-diffraction-limited beam quality is presented. Up to 6.12 kW fiber laser with the conversion efficiency of approximately 78.8% is achieved through the fiber amplifier based on a conventional step-index active fiber. At the maximum output power, the 3 dB spectral linewidth is approximately 0.86 nm and the beam quality factor is Mx2 = 1.43, My2 = 1.36. We have also measured and compared the output properties of the fiber amplifier employing different pumping schemes. Notably, the practical power limit of the fiber amplifier could be estimated through the maximum output powers of the fiber amplifier employing unidirectional pumping schemes. Overall, this work could provide a good reference for the optimal design and potential exploration of high-power narrow-linewidth fiber laser systems.

Autoimmune thyroiditis (AIT) has a complex aetiology and the susceptibility to it is determined by a combination of genetic and environmental factors, although these are not yet fully understood. The present research aimed to explore the DNA methylation patterns in whole blood of extrinsic apoptotic signalling pathway-related genes in AIT among areas with different iodine levels. We selected the iodine-fortification areas, iodine-adequate areas and water-based iodine-excess areas from Shandong Province of China as survey sites. Totally, 176 AIT cases and 176 controls were included. MethylTargetTM and QT-PCR technology were used to detect candidate genes’ DNA methylation levels and mRNA expression levels, respectively. We found that death associated protein kinase 1 (DAPK1) DNA methylation levels in AIT cases (especially in female) were significantly higher than controls (t = 2·7715, P = 0·0059; t = 2·4638, P = 0·0143 in female). There were differences in DAPK1 (t = 2·5384, P = 0·0121), TNF superfamily member 8 (t = 2·1667, P = 0·0334) and TNF-α-induced protein 8 (TNFAIP8) (t = 2·5672, P = 0·0121) genes methylation between cases and controls with different water iodine levels. The mRNA expression of DAPK1 (t = 4·329, P < 0·001) and TNFAIP8 (t = 3·775, P < 0·001) in the cases was increased. We identified the differences in the DNA methylation status of the extrinsic apoptotic signalling pathway-related genes between AIT and controls and in different iodine levels areas. The results were verified at the mRNA level. The environmental iodine may affect DNA methylation to some extent.

The aim of this study was to explore the frequency and distribution of gene mutations that are related to isoniazid (INH) and rifampin (RIF)-resistance in the strains of the multidrug-resistant tuberculosis (MDR-TB) Mycobacterium tuberculosis (M.tb) in Beijing, China. In this retrospective study, the genotypes of 173 MDR-TB strains were analysed by spoligotyping. The katG, inhA genes and the promoter region of inhA, in which genetic mutations confer INH resistance; and the rpoB gene, in which genetic mutations confer RIF resistance, were sequenced. The percentage of resistance-associated nucleotide alterations among the strains of different genotypes was also analysed. In total, 90.8% (157/173) of the MDR strains belonged to the Beijing genotype. Population characteristics were not significantly different among the strains of different genotypes. In total, 50.3% (87/173) strains had mutations at codon S315T of katG; 16.8% (29/173) of strains had mutations in the inhA promoter region; of them, 5.5% (15/173) had point mutations at −15 base (C→T) of the inhA promoter region. In total, 86.7% (150/173) strains had mutations at rpoB gene; of them, 40% (69/173) strains had mutations at codon S531L of rpoB. The frequency of mutations was not significantly higher in Beijing genotypic MDR strains than in non-Beijing genotypes. Beijing genotypic MDR-TB strains were spreading in Beijing and present a major challenge to TB control in this region. A high prevalence of katG Ser315Thr, inhA promoter region (−15C→T) and rpoB (S531L) mutations was observed. Molecular diagnostics based on gene mutations was a useful method for rapid detection of MDR-TB in Beijing, China.

We present an experimental study on controlling the number of vortices and the torque in a Taylor–Couette flow of water for Reynolds numbers from 660 to 1320. Different flow states are achieved in the annulus of width $d$ between the inner rotating and outer stationary cylinders through manipulating the initial height of the water annulus. We show that the torque exerted on the inner cylinder of the Taylor–Couette system can be reduced by up to 20 % by controlling the flow at a state where fewer than the nominal number of vortices develop between the cylinders. This flow state is achieved by starting the system with an initial water annulus height $h_0$ (which nominally corresponds to $h_0/d$ vortices), then gradually adding water into the annulus while the inner cylinder keeps rotating. During this filling process the flow topology is so persistent that the number of vortices does not increase; instead, the vortices are greatly stretched in the axial (vertical) direction. We show that this state with stretched vortices is sustainable until the vortices are stretched to around 2.05 times their nominal size. Our experiments reveal that by manipulating the initial height of the liquid annulus we are able to generate different flow states and demonstrate how the different flow states manifest themselves in global momentum transport.

Underground Nuclear Astrophysics in China (JUNA) will take the advantage of the ultra-low background in Jinping underground lab. High current accelerator with an ECR source and detectors were commissioned. JUNA plans to study directly a number of nuclear reactions important to hydrostatic stellar evolution at their relevant stellar energies. At the first period, JUNA aims at the direct measurements of 25Mg(p,γ)26 Al, 19F(p,α) 16 O, 13C(α, n) 16O and 12C(α,γ) 16O near the Gamow window. The current progress of JUNA will be given.

In this paper, a tri-band bandpass filter (BPF) using asymmetric stub-loaded stepped-impedance resonator (SL-SIR) is presented. The asymmetric characteristic of SL-SIR broadens degrees of freedom for three controllable modes design. Also, the coupling coefficients (Mij) and the external quality factors (Qei) at each passband of the filter can be independently adjusted by the proposed mixed-type feedline structure. Besides, multi-transmission zeros are produced to improve the isolation and selectivity of the passbands. Finally, a tri-band BPF is operated at 1.9 GHz (time division long term evolution – TD-LTE band), 3.2 GHz (worldwide interoperability for microwave access – WiMAX band), and 5.8 GHz (wireless local area networks – WLAN band) and their insertion loss are 1.03, 0.94, and 1.27 dB, respectively. The measured results of the fabricated tri-band BPF exhibit good agreement with simulated results.

Watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai var. lanatus] is an economically important vegetable belonging to the Cucurbitaceae family. Genotypes that exhibit agronomically important traits are selected for the development of elite cultivars. Understanding the genetic diversity and the genotype population structure based on molecular markers at the genome level can speed up the utilization of diverse genetic resources for varietal improvement. In the present study, we carried out an analysis of genetic diversity based on 3882 SNP markers across 37 core watermelon genotypes, including the most widely used watermelon varieties and wild watermelon. Based on the SNP genotyping data of the 37 watermelon genotypes screened, gene diversity and polymorphism information content values across chromosomes varied between 0.03–0.5 and 0.02–0.38, with averages of 0.14 and 0.13, respectively. The two wild watermelon genotypes were distinct from cultivated varieties and the remaining 35 cultivated genotypes were differentiated into three major clusters: 20 genotypes were grouped in cluster I; 11 genotypes were grouped in cluster II; three advanced breeding lines of yellow fruit flesh and genotype SW043 were grouped in cluster III. The results from neighbour-joining dendrogram, principal coordinate analysis and STRUCTURE analysis approaches were consistent, and the grouping of genotypes was generally in agreement with their origins. Here we reveal the genetic relationships among the core watermelon genotypes maintained at the Jiangsu Academy of Agricultural Sciences, China. The molecular and phenotypic characterization of the existing core watermelon genotypes, together with specific agronomic characteristics, can be utilized by researchers and breeders for future watermelon improvement.

In this study, novel Si2Sb2Te6 phase change material is investigated in detail for the phase change memory application using transmission electron microscopy and X-ray photoelectron spectroscopy. The phenomenon that Te diffuses to the film surface during phase switching and successively evaporates out has been confirmed. The phase change memory cells employing Si2Sb2Te6 and Si3Sb2Te3 materials are fabricated and programmed. For the Si2Sb2Te6-based cell a data endurance of 5×105 cycles is achieved with a failure mode resembling reset stuck, which can be attributed to the migration of Tellurium during the operation cycles. It means that a thermally stable material system of SixSb2Te3 is preferred for the PCM applications.

The effect of minor transition metal (TM) additives of Ni, Co, or Zn on the interfacial reactions of the solder joints between Sn–Ag–Cu (SAC) solder and the Cu/Ni(P)/Au substrate was investigated, especially subsequent to multi-reflowing. (Cu,Ni)6Sn5 formed at the interface of all the joints except that of SAC–Ni, of which the interfacial compound was (Ni,Cu)6Sn5. The interfacial compounds of the SAC–Co and SAC–Zn contained a small amount of alloying elements of less than 3 at.%. Two P-rich layers, Ni3P and Ni–Sn–P emerged at the interface of the SAC joints. Nanoindentation analysis indicates that the hardness and Young’s modulus of these two phases were slightly higher than those of the Ni(P) substrate, which were in turn much greater than those of the Cu–Ni–Sn compounds. Worthy of notice is that with TM additions, the Ni–Sn–P phase between Ni3P and interfacial compounds was absent even after 10 reflows. For the SAC–Co joints, the growth of Ni-containing intermetallic compounds within the solder gave rise to the excess Ni dissolution, which caused a discrete Ni3P layer and over-consumed Ni(P) substrate underneath the grooves in-between (Cu, Ni)6Sn5 scallop grains at the interface. This phenomenon is presented for the first time, and the mechanism is proposed in this study.