High-gain ultraviolet Cu-II laser in a segmented hollow cathodedischarge

We report measurements of the discharge and laser characteristics of an ultraviolet (UV) copper ion laser radiating on the 248.6- and 270.3-nm transitions. Our 50-cm active length laser operates in a high-voltage segmented hollow cathode discharge with Brewster windows and external mirrors. The lowest threshold currents were 7.3 and 5.6 A for the above transitions, respectively. The threshold current was found to increase with decreasing active length. We obtained superior gain characteristics (to 11.2 and 8.8%/m gain for the 248.6-and 270.3-nm transitions, respectively, at 0.3 A/cm linear current density) compared with previous studies on UV Cu ion lasers in conventional hollow cathode discharges     

Maternal Phylogeny of a Newly-Found Yak Population in China

The Jinchuan yak is a new yak population identified in Sichuan, China. This population has a special anatomical characteristic: an additional pair of ribs compared with other yak breeds. The genetic structure of this population is unknown. In the present study, we investigated the maternal phylogeny of this special yak population using the mitochondrial DNA variation. A total of 23 Jinchuan yaks were sequenced for a 823-bp fragment of D-loop control region and three individuals were sequenced for the whole mtDNA genome with a length of 16,371-bp. To compare with the data from other yaks, we extracted sequence data from Genebank, including D-loop of 398 yaks (from 12 breeds) and 55 wild yaks, and whole mitochondrial genomes of 53 yaks (from 12 breeds) and 21 wild yaks. A total of 127 haplotypes were defined, based on the D-loop data. Thirteen haplotypes were defined from 23 mtDNA D-loop sequences of Jinchuan yaks, six of which were shared only by Jinchuan, and one was shared by Jinchuan and wild yaks. The Jinquan yaks were found to carry clades A and B from lineage I and clade C of lineage II, respectively. It was also suggested that the Jinchuan population has no distinct different phylogenetic relationship in maternal inheritance with other breeds of yak. The highly haplotype diversity of the Pali breed, Jinchuan population, Maiwa breed and Jiulong breed suggested that the yak was first domesticated from wild yaks in the middle Himalayan region and the northern Hengduan Mountains. The special anatomic characteristic that we found in the Jinchuan population needs further studies based on nuclear data.     

Comparison of Cu-II 781 nm lasers using high-voltage hollow-cathodeand hollow-anode-cathode discharges

Voltage-current characteristics and the Cu-II 780.8 nm laser performances are described for a novel segmented hollow cathode and for three- and four-slot hollow-anode cathode (HAC) tubes. Each of these operate at a higher voltage and with higher slope resistance than a conventional hollow cathode and produce improved laser performance. The best laser performance is obtained with the segmented tube. The application of a longitudinal magnetic field raises the discharge voltage and enhances the laser performance for the segmented tube and raises the voltage for the four-slot HAC tube. The magnetic field lowers the voltage and reduces the laser performance with the three-slot HAC tube. The voltage effects are attributed to the deflection of the fast electrons by the magnetic field and represent experimental evidence for the oscillation of electrons in a hollow-cathode discharge     

A high-voltage hollow-cathode Au-II 282-nm laser

Laser operation on the Au-II 282.3-nm line is obtained from a high-voltage, segmented hollow-cathode discharge tube with external mirrors. Measurements of the laser output power and the small-signal gain demonstrate that, for a given total discharge current, the optimum performance of the laser is obtained for a discharge length for which the linear current density is approximately 65 mA cm^-1. The gain is approximately 2546 m^-1 at this current density and increases with current density up to the highest value used (250 mA cm ^-1), at which the gain exceeds 50% m^-1. The threshold current decreases monotonically, with decreasing length, the lowest observed value being 6.28 A for a length of 5 cm. A quasi-CW output power of 20 mW is obtained for a gain length of 20 cm and a discharge current of 3.2 A in a partially optimized tube with unoptimized output coupling     

High-gain hollow-cathode metal ion lasers for the UV and VUV

The segmented hollow-cathode pumping discharge gives a higher gain on the He-Cu⁺ 781, He-Au⁺ 282, and Ne-Cu⁺ 270-nm lines at lower discharge current and input power than do the conventional hollow-cathode, hollow anode cathode and helical hollow-cathode discharges. The segmented hollow-cathode offers the prospect of compact low-cost repetitively pulsed UV laser for applications to biomedical and other spectroscopically-based instrumentation. The projections for increasing the gain on the He-Cu ⁺ VUV lines indicate that laser action on one or more of these lines may be achieved     

蜂蜜产地与蜜源矿物元素溯源方法的建立

基于矿物元素含量进行蜂蜜产地和蜜源溯源分析,建立产地和蜜源双目标溯源方法。采用全谱直读电感耦合等离子体原子发射光谱法(ICP-OES)测定蜜样矿物元素含量,在单目标溯源方法基础上,引进哑变量回归和校正模型,从而建立了蜂蜜产地、蜜源双目标溯源分析方法,并以四川蜂蜜为例,进行验证分析。结果显示,针对产地进行的逐步判别分析筛选出As、B、Ca等6个元素用于建立判别模型,回代验证的正确判别率达91.7%,交叉检验判别率为83.3%;针对蜜源的逐步判别分析筛选出B、Ca、Cu等5种元素用于建立判别模型,判别率为80%,交叉检验判别率为78.2%。基于矿物元素含量对蜂蜜进行产地与蜜源的溯源是可行的,所建立的方法具有一定借鉴意义;产地、蜜源两组判别方程适宜于研究区的溯源研究。