Spin-orbital separation in the quasi-one-dimensional Mott insulator Sr2CuO3

When viewed as an elementary particle, the electron has spin and charge. When binding to the atomic nucleus, it also acquires an angular momentum quantum number corresponding to the quantized atomic orbital it occupies. Even if electrons in solids form bands and delocalize from the nuclei, in Mott insulators they retain their three fundamental quantum numbers: spin, charge and orbital. The hallmark of one-dimensional physics is a breaking up of the elementary electron into its separate degrees of freedom. The separation of the electron into independent quasi-particles that carry either spin (spinons) or charge (holons) was first observed fifteen years ago. Here we report observation of the separation of the orbital degree of freedom (orbiton) using resonant inelastic X-ray scattering on the one-dimensional Mott insulator Sr2CuO3. We resolve an orbiton separating itself from spinons and propagating through the lattice as a distinct quasi-particle with a substantial dispersion in energy over momentum, of about 0.2 electronvolts, over nearly one Brillouin zone.     

Platensimycin is a selective FabF inhibitor with potent antibiotic properties

Bacterial infection remains a serious threat to human lives because of emerging resistance to existing antibiotics. Although the scientific community has avidly pursued the discovery of new antibiotics that interact with new targets, these efforts have met with limited success since the early 1960s. Here we report the discovery of platensimycin, a previously unknown class of antibiotics produced by Streptomyces platensis. Platensimycin demonstrates strong, broad-spectrum Gram-positive antibacterial activity by selectively inhibiting cellular lipid biosynthesis. We show that this anti-bacterial effect is exerted through the selective targeting of beta-ketoacyl-(acyl-carrier-protein (ACP)) synthase I/II (FabF/B) in the synthetic pathway of fatty acids. Direct binding assays show that platensimycin interacts specifically with the acyl-enzyme intermediate of the target protein, and X-ray crystallographic studies reveal that a specific conformational change that occurs on acylation must take place before the inhibitor can bind. Treatment with platensimycin eradicates Staphylococcus aureus infection in mice. Because of its unique mode of action, platensimycin shows no cross-resistance to other key antibiotic-resistant strains tested, including methicillin-resistant S. aureus, vancomycin-intermediate S. aureus and vancomycin-resistant enterococci. Platensimycin is the most potent inhibitor reported for the FabF/B condensing enzymes, and is the only inhibitor of these targets that shows broad-spectrum activity, in vivo efficacy and no observed toxicity.     

Seismic reflection images of the Moho underlying melt sills at the East Pacific Rise

The determination of melt distribution in the crust and the nature of the crust-mantle boundary (the 'Moho') is fundamental to the understanding of crustal accretion processes at oceanic spreading centres. Upper-crustal magma chambers have been imaged beneath fast- and intermediate-spreading centres but it has been difficult to image structures beneath these magma sills. Using three-dimensional seismic reflection images, here we report the presence of Moho reflections beneath a crustal magma chamber at the 9 degrees 03' N overlapping spreading centre, East Pacific Rise. Our observations highlight the formation of the Moho at zero-aged crust. Over a distance of less than 7 km along the ridge crest, a rapid increase in two-way travel time of seismic waves between the magma chamber and Moho reflections is observed, which we suggest is due to a melt anomaly in the lower crust. The amplitude versus offset variation of reflections from the magma chamber shows a coincident region of higher melt fraction overlying this anomalous region, supporting the conclusion of additional melt at depth.     

印度的农业信息化

众所周知，农产品交易的顺利进行需要一个有效可靠而的市场买卖信息系统，它能为农户提供关于到货、当前价格、大致价格趋势、交易价格等新鲜的市场信息。但要建立这样一个信息系统，需要在村级水平上建立信息站点，并对市场信息进行实时更新，然后提供给农户。     

含FeO熔渣还原过程起泡行为研究

在１４４０－１５３０ ℃，通过Ｘ射线装置观测了石墨还原ＣａＯ－ＳｉＯ２－Ａｌ２Ｏ３－ＦｅＯ熔渣（ＣａＯ／ＳｉＯ２＝０．７５－１．５）中ＦｅＯ反应过程中渣的起泡行为，测定了熔渣的起泡指数和起泡率等参数。结果表明，熔渣的起泡率随熔渣中ＦｅＯ的初己考叭墼疃鹊纳叨龃蟆?     

含FeO熔渣起泡指数的因次分析

通过对石墨还原ＣａＯ－ＳｉＯ２－Ａｌ２Ｏ３－ＦｅＯ熔渣中ＦｅＯ过程起泡指数的因次分析，得出影响渣的起泡指数∑的因素有熔渣密度ρ，粘度μ，表面张力σ及重力加速度ｇ．起泡指数的经验表达式为：∑＝１６４．６（μ４／ρ３σｇ５）１／８．该式可表征不同渣系的起泡指数．分析表明，影响熔渣起泡的因素主要有渣中气体的产生速度和熔渣本身的性质．