Evaluating the metabolic perturbations in Mangifera indica (mango) ripened with various ripening agents/practices through gas chromatography ‐ mass spectrometry based metabolomics

Mangifera indica L. (mango) is said to be the king of fruits due to its rich nutritional properties and mainly originates from the Indian sub‐continent. The consumption pattern of the mangoes has increased drastically, due to which, many ripening practices/agents were used to make it ready‐to‐eat fruit or juice for the consumers. The fruit quality and metabolic composition are said to be altered due to different ripening agents/practices. The present communication mainly deals to understand the metabolic perturbations in mango fruits due to different ripening practices/agents (room temperature ripening, ethylene, and calcium carbide) using gas chromatography ‐ mass spectrometry based metabolomics. The partial least square‐discriminant analysis has found 16 differential metabolites for different ripening agents/practices which are belong to the classes of amino acids, fatty acids, sugars, and polyols. Four metabolic pathways were found to alter in the fruit metabolome due to different ripening agents/practices. Fructose, glucose, and galactose were found to be significantly up‐regulated due to calcium carbide ripening in comparison to other ripening agents/practices. Overall findings from the present study advocates that mass spectrometry based metabolomics can be valuable tool to understand the fruit quality and safety with respect to consumer health.     

A simple method to synthesize single-crystalline lanthanide orthovanadate nanorods

Single-crystalline tetragonal LnVO₄ (Ln=La, Nd, Sm, Eu, Dy) nanorods were prepared via a simple hydrothermal method, in the absence of any surfactant or template using cheap and simple inorganic salts as raw materials. The products were characterized by XRD, TEM, HRTEM, and PL. It has been shown that after the hydrothermal process, LaVO₄ transformed its crystal structure from monoclinic to tetragonal phase, but LnVO₄ (Ln=Nd, Sm, Eu, Dy) have not exhibited the structural change. This could be associated with the change of lanthanide ion radius. TEM and HRTEM results show that the nanorods are pure, structurally uniform, single crystalline, and most of them are free from dislocations. Further study reveals the nanorods grow along the [001] direction. A possible growth mechanism of lanthanide orthovanadate nanorods was also proposed. The advantages of our method for the nanorods synthesis lie in the high yield and the low temperature and mild reaction conditions, which permit large scale production at low cost.     

On First-order Corrections to the LSW Theory II: Finite Systems

We consider first–order corrections to the classical theory by Lifshitz, Slyozov and Wagner (LSW) for systems with a finite number of particles. Numerical simulations in V. E Fradkov etal. [Phys. Rev. E 53:3925–3932 (1996)] show a cross–over in the scaling of the correction term from ^1/3 to ^1/2 ( is the volume fraction of particles), when the system size becomes larger than the screening length. We rigorously derive this cross–over for the rate of change of the energy, starting from the monopole approximation. The proof exploits the fact that the rate of change of energy has a variational characterization.     

ZnCdSe量子点的激子行为研究

用金属有机化学气相沉积(MOCVD)的方法在晶格失配较小的情况下制备了ZnCdSe量子点。并用原子力显微镜(AFM)和极低温度下的发光光谱确认了量子点的形成。原子力显微镜观测的形貌变化发现。随着生长后时间的增加,量子点的尺寸逐渐增大。而密度减小,这是由于熟化过程作用的结果。随着量子点生长完毕与加盖层之间间隔时间的增加,量子点的发光峰位明显红移,且由变温光谱得到的激子束缚能逐渐变小。这可以解释为随着间隔时间的增加,量子点的熟化过程导致量子点的尺寸增大,量子限域效应减弱所致。     

Ostwald‐Ripening‐Induced Growth of Parallel Face‐Exposed Ag Nanoplates on Micro‐Hemispheres for High SERS Activity

Ag nanoplates, as two‐dimensional plasmonic nanostructures, have attracted intensive attention due to their strong shape‐dependent optical properties and related applications. Here parallel face‐exposed Ag nanoplates vertically grown on micro‐hemisphere surfaces have been achieved by firstly electrodepositing the micro‐hemispheres assembled by Ag nanoplates, whose planar surfaces are stuck together, on indium tin oxide substrates, and then Ostwald ripening the as‐electrodeposited micro‐hemispheres in water. The sizes of the nanoplates and the gaps between the neighboring nanoplates have been tailored by tuning the Ostwald‐ripening duration, so that the SERS activity of the micro‐hemispheres has been remarkably improved. The improved SERS activity can be well explained by our systematic finite‐element simulation. Therefore, Ostwald ripening offers a route to the synthesis of Ag nanoplates, and the optimization of plasmon coupling and SERS activity of nanostructure‐assembled systems.     

Self‐template hydrothermal synthesis ZnS microspheres

Zinc sulfide (ZnS) microspheres were synthesized by a self‐template hydrothermal route using thiourea as sulphur source. The formation of these hollow spheres was mainly attributed to the oriented aggregation of ZnS nanocystals around the gas‐liquid interface between gas (H₂S, NH₃, or CO₂) and water followed by an Ostwald ripening process. The gas bubbles of H₂S, NH₃, or CO₂ produced during the reaction might play a soft‐template to form ZnS hollow microspheres. The products were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), electron diffraction (ED), and photoluminescence (PL). The crystal structure of prepared ZnS microspheres is hexagonal phase polycrystalline. The average microspheres diameter is 1.5 ‐ 6 µm. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

多层螺旋CT小肠造影对炎症性肠病的诊断价值

探讨多层计算机断层扫描肠造影(CTE)在炎症性肠病(IBD)中的诊断及病情评估价值.研究纳入临床疑为IBD患者150例,最终确诊102例,分析CTE对IBD的临床诊断及疾病评估价值,并以结肠镜结果为参照,分析其对病变肠段定位的准确性.结果发现克罗恩病(CD)及溃疡性结肠炎(UC)患者肠壁增厚、肠壁异常强化、肠道狭窄、肠...     

纳米尺度的消化熟化及其在单分散纳米材料制备中的应用

近年来，消化熟化方法已经被广泛采用来制备单分散纳米粒子，特别是在制备亚10 nm的小尺寸纳米粒子方面具有显著优势.但是，目前国内尚未发现关于此方法的中文文献报道，影响了部分国内学者对消化熟化方法的认识和应用.因此，从纳米尺度的消化熟化现象的发现过程和机理的提出开始，分析了沉淀反应前驱物、消化熟化剂种类、热处理温度和时间、溶剂类型以及其他因素对消化熟化现象的影响，介绍了基于颗粒表面带电与曲率效应、颗粒表面与配体分子层的相互作用以及消化熟化过程中的竞争反应平衡等因素的理论模型和研究结果，阐述了消化熟化法在制备金属纳米粒子、合金纳米粒子、金属氧化物和硫族化合物量子点以及其他纳米粒子等单分散纳米材料中的应用，最后展望了消化熟化法制备的单分散纳米粒子在纳米组装和多相催化等领域的应用.     

Preparation of water-in-diesel oil nano-emulsion using nonionic surfactants with enhanced stability and flow properties

Formation of water-in-diesel oil (w/o) nano-emulsion has been achieved by a low-energy emulsification method by stabilizing a new combination of nonionic sorbitan esters surfactants, that is PEG20-sorbitan monostearate and sorbitan monooleate in mixed proportions. Different combinations of the surfactants (T6?+?S8) have been tested and the best possible combination of mixed surfactants is found at a surfactants ratio of 35:65 (wt/wt) for T6:S8 at hydrophile–lipophile balance (HLB)?=?8.01, which resulted in smaller droplet size of 44.87?nm. A phase diagram study is performed to identify the zones of formation of transparent, translucent, and opaque emulsions (44?nm??27?m³?·?s^?1. Comparison of Ostwald ripening rate with other sets of surfactants obtained by different authors showed the lowest rate among them, indicative of enhanced stability. A rheological study of the tested set of nano-emulsions depicts the Newtonian behavior (1.0371?≤?n?≤?1.0826) over a wider range of shear rates (10–1000?s^?1) at different temperatures (25–40°C).     

Dependence of emulsion stability on particle size: Relative importance of drop concentration and destabilization rate on the half lifetimes of O/W nanoemulsions

This study reports the behavior of ionic dodecane-in-water nanoemulsions in distinct salt concentrations. Systems of smaller particle size (74–285 nm) were synthesized by a sudden dilution of an equilibrated mixture. Larger size systems (384–670 nm) were obtained from a set of formerly smaller nanoemulsions that evolved unperturbed for 2 weeks. Characteristic destabilization times for flocculation, coalescence, and Ostwald ripening were evaluated. In general, it was observed that stability increases with drop size. However, this size dependence is largely the consequence of the lower particle concentration of the coarser emulsions.