6.1 MW, 10 kHz Side-Pumped Burst-Mode Nd:YAG Laser

We present a compact high-peak-power, high-repetition-rate burst-mode laser from a master-oscillator power amplifier (MOPA) at 1064 nm for laser-based measurement applications. The oscillator is an 808 nm pulsed laser diode side-pumped acousto-optical (A-O) Q-switched Nd:YAG laser at repetition rates ranging from 10–100 kHz, producing a pulse train with a pulse number of 2–25. The maximum output energy of the oscillator is 15.6 mJ at 10 kHz, whereas it is 1.7 mJ at 100 kHz. After twostage amplifiers, a single-pulse energy of 85.2 mJ with a pulse-width of 14.5 ns is achieved at 10 kHz, which produces a peak power of 6.1 MW. At 100 kHz, the total burst energy reaches 220 mJ with a single-pulse energy of 8.8 mJ in the pulse burst laser system.     

Recent progress on the mechanics of sharply bent DNA

Despite extensive studies on the mechanics of DNA under external constrains, such as tension, torsion, and bending, several important aspects have remained poorly understood. One biologically important example is the mechanics of DNA under sharp bending conditions, which has been debated for a decade without thorough comprehension. The debate is about the interesting phenomenon raised from a series of different experiments: sharply bent DNA has a surprisingly high apparent bending flexibility that deviates from the canonical bending elasticity of DNA. This finding has motivated various theoretical models, which mainly incorporate the excitation of mechanical defects inside severely bent DNA molecules. Here, we review the recent progress on the understanding of the mechanics of sharply bent DNA and provide our view on this important question by interrogating the theoretical foundation of these experimental measurements.     

Progress of Jinping Underground laboratory for Nuclear Astrophysics (JUNA)

Jinping Underground laboratory for Nuclear Astrophysics(JUNA) will take the advantage of the ultra-low background of CJPL lab and high current accelerator based on an ECR source and a highly sensitive detector to directly study for the first time a number of crucial reactions occurring at their relevant stellar energies during the evolution of hydrostatic stars. In its first phase, JUNA aims at the direct measurements of~(25)Mg(p,γ)~(26)Al,~(19)F(p,α)~(16)O,~(13)C(α,n)~(16)O and ~(12)C(α,γ)~(16)O reactions. The experimental setup,which includes an accelerator system with high stability and high intensity, a detector system, and a shielding material with low background, will be established during the above research. The current progress of JUNA will be given.     

Laser-induced breakdown spectroscopy in Asia

Laser-induced breakdown spectroscopy (LIBS) is an analytical detection technique based on atomic emission spectroscopy to measure the elemental composition. LIBS has been extensively studied and developed due to the non-contact, fast response, high sensitivity, real-time and multi-elemental detection features. The development and applications of LIBS technique in Asia are summarized and discussed in this review paper. The researchers in Asia work on different aspects of the LIBS study in fundamentals, data processing and modeling, applications and instrumentations. According to the current research status, the challenges, opportunities and further development of LIBS technique in Asia are also evaluated to promote LIBS research and its applications.     

Porous WO<Subscript>3</Subscript>/reduced graphene oxide composite film with enhanced electrochromic properties

The porous WO₃/reduced graphene oxide (rGO) composite films are prepared on indium–tin oxide (ITO) glass by sol-gel method. The mixture sol combines peroxotungstic acid solution with rGO dispersion reduced by ethylene glycol (EG). The excessive EG and other organic additives are subsequently removed by annealing, which leads to the formation of porous structure. Compared with pure WO₃ film, WO₃/rGO composite film shows improved electrochromic performance because of enhanced double insertion/extraction of ions and electrons. It realizes a large optical modulation (64.2 % at 633 nm), fast switching speed (9.5 s for coloration and 4.5 s for bleaching), good cycling stability as well as reversibility.     

Preparation and performance of sulfur–carbon composite based on hollow carbon nanofiber for lithium-sulfur batteries

A unique structured hollow carbon nanofiber–sulfur composite material (HCF–S) was fabricated and characterized in lithium-sulfur batteries. It is found that a part of spherical sulfur particles are located in the voids formed by the intertwined fibers and the others are confined in hollow channel of the HCF. The high conductive and porous HCF favors the construction of stable three-dimensional conducting network and convenient infiltration of the electrolytes into the cathode. The HCF–S cathode exhibits excellent electrochemical performance in the electrolyte with LiNO₃. By contrast, the ionic liquid electrolyte provides insufficient shuttle suppression and weakens ion transport, which leads to poor cycle and rate capability.     

Synthesis of Li<Subscript>4</Subscript>Ti<Subscript>5</Subscript>O<Subscript>12</Subscript>-reduced graphene oxide composite and its application for hybrid supercapacitors

We describe in this paper the synthesis and the characterization of Li₄Ti₅O₁₂-reduced graphene oxide (LTO-RGO) composite and demonstrate their use as hybrid supercapacitor, which is consist of an LTO negative electrode and activate carbon (AC) positive electrode. The LTO-RGO composites were synthesized using a simple, one-step process, in which lithium sources and titanium sources were dissolved in a graphene oxide (GO) suspension and then thermal treated in N₂. The lithium-ion battery with LTO-RGO composite anode electrode revealed higher discharge capacity (167 mAh g^?1 at 0.2 C) and better capacity retention (67%) than the one with pure LTO. Meanwhile, compared with the AC//LTO supercapacitor, the AC//LTO-RGO hybrid supercapacitor exhibits higher energy density and power density. Results show that the LTO-RGO composite is a very promising anode material for hybrid supercapacitor.     

基于漫反射光谱法下层组织信息的最佳探测位置的研究

由于人体组织结构的复杂性和个体差异性,采用光谱分析技术实现组织内部信息的检测方法中,仍存在着检测位置不明确的问题。采用多位置空间分辨漫反射光谱法对脂肪肌肉组织中内部信息的最佳探测位置进行了研究。由于目标组织为肌肉组织,为了消除由于不同人体皮下脂肪层厚度的差异以及目标层中多次后向散射光对测量结果引起的较大误差,并根据光在复杂生物组织中的传输模型,通过增加约束条件——两条理想的“香蕉型”路径—来定义有效光子比SNR,并以SNR作为评价最佳探测位置SDS_best的标准,对优化后的Monte Carlo仿真结果进行统计分析,分别研究了脂肪层厚度h_f、脂肪层吸收系数μ_af和肌肉层吸收系数μ_am与光源探测器间距SDS之间的关系,并以h_f为自变量与SDS_best建立线性回归模型。研究表明,(1)当0<h_f<0.6 cm时,μ_af和μ_am对SDS_best几乎没有影响,而h_f与SDS_best的建模相关系数R2为0.991 8;(2)任取脂肪层厚度值0.12与0.22 cm作预测,得到预测误差分别为0.030 14和0.020 16,预测误差均能控制在5%以内。该方法能更方便、快速地为测量组织内部信息确定最佳检测位置,并有效削弱浅表组织以及目标层中多次背向散射光的干扰。     

基于FTIR技术的酸牛奶营养成分快速检测方法研究

酸牛奶作为一种重要的发酵乳制品,伴随着发酵过程,其各种营养成分时刻发生着复杂的变化,因此,建立酸牛奶的快速高效检测技术可以实现对生产过程的实时监控,这也是食品安全监管要达到的重要目标。傅里叶变换红外光谱技术(FTIR)因其快速、高通量、无化学污染、可对掺假成分予以分辨等特点被广泛应用于食品安全领域。以FTIR技术为核心,利用氟化钙薄膜法,将酸牛奶FTIR光谱图与其营养成分(能量值,蛋白质、脂肪、碳水化合物和钠含量)对照,建立了基于最小二乘法(PLS)的定量化预测模型。结果表明,该模型样品校正集的能量值,蛋白质、脂肪、碳水化合物和钠含量的交叉检验R2值分别达到0.938 9,0.926 6,0.918 6,0.941 8和0.977 1;该模型用于预测,其样品验证集的交叉检验R2值分别为0.920 5,0.905 3,0.908 5,0.939 3和0.936 4。由此可见,该模型对酸牛奶各营养指标均具有较好的预测准确性,在时间上具备较好的稳定性。不同于传统的化学检测方法,本研究为实现对酸牛奶品质的快速检测提供了一种较为可行的方法。该方法作为乳制品质量监控技术的一项初步探索,具有较好的应用前景。