Compact microfiber Bragg gratings with high-index contrast

We fabricate fiber Bragg grating (FBG) in microfibers (MFs) using focused ion beam milling technique. By periodically etching 100 nm-depth grooves on the surface of silica MFs with diameters less than 2 μm, evident grating features with transmission dip up to 15 dB are obtained. Because of the high-index contrast of the gratings structure, the length of the microfiber Bragg grating (MFBG) can be reduced to 500 μm level. Using a 518 μm-length 1.8 μm-diameter MFBG, we also demonstrate sensitivity up to 660 nm per refractive index unit (RIU) for refractive index (RI) sensing. The highly compact MFBGs demonstrated here may serve as low-dimensional building blocks for miniaturized photonic components and devices.     

Al70Co15Tb5Ni10合金中准晶T相和相关相的形成

 对Al₇₀Co₁₅Tb₅Ni₁₀合金进行了静高压（4.40 GPa）熔态（1 450 ℃）淬火（冷却速率为10² ℃/s）研究。首次在该系统中观察到准晶T相和一个新的十次准晶相关相形成。使用透射电镜对准晶相和准晶相关相进行了结构分析，得到了准晶相关相的晶胞参数。使用已有的理论模型对该相关相的形成进行了讨论。     

基于液晶电视屏的可编程实时光学图象预处理器

本文报道一个新颖的实时光学图象预处理器。该预处理器采用一个经过改装的微型黑白液晶电视可进行电压控制的实时光学对比度翻转和边缘增强处理。文中给出其工作原理、结构及处理结果。     

分区适应截值模型及其在交通标志识别中的应用

针对Ｈｏｐｆｉｅｌｄ网络模型在存储模式不满足０和１状态的均匀分布及数目对等的条件下存储容量及寻址能力下降的缺点，提出并用光束方向编码光学实现了三值（１，０，－１）互连的分区适应截值模型，并把这一模型应用到交通标志的识别中，结果表明该模型及光学系统有很好的稳定性。     

Existence problem of optical correlation based pattern recognition

The existence problem of optical correlation based pattern recognition, namely its range of validity and its limitation, is discussed in this paper conjointly with the function approximation theory of neural networks. The conclusion is that only if the sets to be recognized are linearly separable (which is rare) or the subsets, in which a segmental sample of the targets is involved, are linearly separable, can the classical 4f optical correlation system carry out the task of recognition inerrably. The recognition principle of a joint transform correlator is the same as that of a 4f system, and so is its range of validities. Based on the demonstration of the existence problem of optical correlation based pattern recognition an evaluation on some important problems that were studied in this field over the past 40 years is presented explicitly.     

Synthesis of the Hemoglobin‐Conjugated Polymer Micelles by Thiol Michael Addition Reactions

Amphiphilic triblock copolymers mPEG‐b‐PMAC‐b‐PCL are synthesized using methoxyl poly(ethylene glycol), cyclic carbonic ester monomer including acryloyl group, and ε‐caprolactone. Copolymers are self‐assembled into core–shell micelles in aqueous solution. Thiolated hemoglobin (Hb) is conjugated with micelles sufficiently through thiol Michael addition reaction to form hemoglobin nanoparticles (HbNs) with 200 nm in diameter. The conjugation of Hb onto the micelle surface is further confirmed by X‐ray photoelectron spectroscopy. Feeding ratio of copolymer micelles to Hb at 1:3 would lead to the highest hemoglobin loading efficiency 36.7 wt%. The UV results demonstrate that the gas transporting capacity of HbNs is well remained after Hb is conjugated with polymeric micelles. Furthermore, the obtained HbNs have no obvious detrimental effects on blood components in vitro. This system may thus have great potential as one of the candidates to be developed as oxygen carriers and provide a reference for the modification of protein drugs.

     

Ultrastructural and Intracellular Chemical Changes of a Novel Halophilic Strain V430 of <Emphasis Type="Italic">Staphylococcus saprophyticus</Emphasis> under CaCl<Subscript>2</Subscript> Stress

Observation of the ultrastructural and intracellular chemical changes of CaCl₂-tolerant strains is important both for understanding their adaptation mechanism under high salt stress and for providing theoretical basis of their application in treating high-CaCl₂ wastewaters. A novel strain V 430 isolated by us has been successfully used to decrease the chemical oxygen demand (COD) concentration of diosgenin wastewater from 20 g l⁻¹ to less than 0.5 g l⁻¹. For this study, strain V430 was incubated in culture media of different CaCl₂ concentrations (up to 9.0%). Strain V430 cells incubated in media of high CaCl₂ concentration excreted extracellular substances and accumulated intracellular Ca²⁺ and K⁺ and free amino acids. The levels of intracellular cations and free amino acids increased with increase in CaCl₂ concentration of the medium. The increase in total free amino acids was mostly due to accumulation of glutamic acid. The strain cells under 9.0% CaCl₂ stress took up K⁺ in a short time, while accumulation of Ca²⁺ proceeded over the whole growth process.     

Stevioside Activates AMPK to Suppress Inflammation in Macrophages and Protects Mice from LPS-Induced Lethal Shock

Stevioside, a diterpenoid glycoside, is widely used as a natural sweetener; meanwhile, it has been proven to possess various pharmacological properties as well. However, until now there were no comprehensive evaluations focused on the anti-inflammatory activity of stevioside. Thus, the anti-inflammatory activities of stevioside, both in macrophages (RAW 264.7 cells, THP-1 cells, and mouse peritoneal macrophages) and in mice, were extensively investigated for the potential application of stevioside as a novel anti-inflammatory agent. The results showed that stevioside was capable of down-regulating lipopolysaccharide (LPS)-induced expression and production of pro-inflammatory cytokines and mediators in macrophages from different sources, such as IL-6, TNF-α, IL-1β, iNOS/NO, COX2, and HMGB1, whereas it up-regulated the anti-inflammatory cytokines IL-10 and TGF-β1. Further investigation showed that stevioside could activate the AMPK -mediated inhibition of IRF5 and NF-κB pathways. Similarly, in mice with LPS-induced lethal shock, stevioside inhibited release of pro-inflammatory factors, enhanced production of IL-10, and increased the survival rate of mice. More importantly, stevioside was also shown to activate AMPK in the periphery blood mononuclear cells of mice. Together, these results indicated that stevioside could significantly attenuate LPS-induced inflammatory responses both in vitro and in vivo through regulating several signaling pathways. These findings further strengthened the evidence that stevioside may be developed into a therapeutic agent against inflammatory diseases.     

Ultrasensitive detection of the β-adrenergic agonist brombuterol by a SERS-based lateral flow immunochromatographic assay using flower-like gold-silver core-shell nanoparticles

The β-adrenergic agonist brombuterol (BB) is illicitly used as an additive in animal feed to enhance the lean meat-to-fat ratio. The authors describe an ultrasensitive lateral flow immunochromatographic assay (LFIA) based on the use of surface enhanced Raman scattering (SERS) for the determination of brombuterol in swine meat and urine samples. Flower-like gold-silver core-shell bimetallic nanoparticles (referred to as AuNF@Ag) displaying strong SERS enhancement were synthesized, characterized and used as the substrate for the preparation of the LFIA. Polyclonal antibody against brombuterol was immobilized on the surface of the AuNF@Ag particles carrying the Raman reporter 4-mercaptobenzoic acid (MBA). After performing an LFIA, the Raman scattering intensity of MBA on the test line was measured and used for quantitation of brombuterol. Figures of merit of this assay procedure include (a) duration of LFIA process of 15 min; (b) an IC₅₀ value (e.g. the concentration of brombuterol producing 50% of signal inhibition in standard curve) of 380 pg mL-1; and (c) a limit of detection as low as 0.5 pg mL-1. The LFIA is selective over the molecules salbutamol, ractopamine, phenylethanolamine A, isoproterenol and phenylephrine, but shows a 8.5% cross-reactivity to clenbuterol, probably due to the high structural similarity. Swine meat and urine samples spiked with different amounts of brombuterol were analyzed by this method and gave recoveries between 95.8 and 108.0%, and relative standard deviations between 2.0 and 6.3% (for n = 3).

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Graphical abstract Schematic presentation of the lateral flow immunochromatographic assay (LFIA) based on surface enhanced Raman scattering (SERS) using flower-like gold-silver core-shell nanoparticles. It is capable of detecting brombuterol in swine meat and urine samples with high sensitivity and specificity.

     

“学习包:自动控制与模块机器人”教学案例

1背景和教学任务"学习包:自动控制与模块机器人"是上海科学技术出版社的《物理》高中二年级第一学期的一节内容.所谓"学习包",就是围绕某一特定内容整合学生经验所构成的相对完整的探究式学习单元."学习包"是上海二期课改新教材中出现的一种新