Green synthesis of MIL⁃101/Au composite particles and their sensitivity to Raman detection of thiram

Metal⁃organic framework(MOF)MIL⁃101 and surface plasmon polariton(SPP)supported gold nanoparti⁃cles(Au NPs)hybrid systems were developed as a highly sensitive and reproducible surface⁃enhanced Raman scat⁃tering(SERS)detection platform,in which a green electrostatic self⁃assembly technology was adopted to construct the substrate.In an aqueous solution,the electronegativity of the particles can be used to prepare the composite sub⁃strate without any surface modifier.Due to the enrichment capacity of MIL⁃101 and the electromagnetic enhance⁃ment from Au NPs,the well⁃designed MIL⁃101/Au composites possessed ultrahigh sensitivity with the detection limit of Rhodamine 6G(R6G)as low as 10^(-10) mol·L^(-1).Meanwhile,the substrate exhibits high stability,excellent reproduc⁃ibility,and recyclability.Additionally,the novel substrate can be explored for direct capture,and sensitively detect pesticide residues such as thiram.

A gradient nano/micro-structured surface layer on copper induced by severe plasticity roller burnishing

In order to investigate a gradient nano/micro-structured surface layer on pure copper produced by severe plasticity roller burnishing （SPRB） and grain refinement mechanism, the microstructure characteristics and material properties of sample at various depths from the topmost surface were investigated by SEM, TEM, XRD, OM etc. The experimental results show that the gradient nano/micro-structure was introduced into the surface layer of over 100μm in thickness. The remarkable increase in hardness near the topmost surface was mainly attributed to the reduced grain size. The equiaxed nano-sized grains were in random orientation and the most of their boundaries were low-angle grain boundaries （LAGBs）. The coarse grains are refined into the few micro-sized grains by dislocation activities;deformation twinning was found to be the primary form for the formation of submicron grains;the formation of nanostructure was dominated by dislocation activities accompanied with rotation of grains in local region.

Preparation and tribological properties of surface modified Cu nanoparticles

Cu nanoparticles surface-modified by dioctylamine dithiocarbamate （DTC8） were synthesized using a two-phase extraction route. The size, morphology and structure of resultant surface-capped Cu nanoparticles （coded as DTC8-Cu） were analyzed by means of X-ray diffraction, transmission electron microscopy and infrared spectrometry. The tribological behavior of DTC8-Cu as an additive in liquid paraffin was evaluated with a four-ball machine, and the surface topography of the wear scar was also examined by means of scanning electron microscopy. Results show that Cu nanoparticles modified by DTC8 have a small particle size and a narrow size distribution. Besides, DTC8-Cu as an additive in liquid paraffin has excellent antiwear ability, due to the deposition of nano-Cu with low melting point on worn steel surface leading to the formation of a self-repairing protective layer thereon.

Isolation and Identification of Submergence-induced Genes in Maize (Zea mays) Seedlings by Suppression Subtractive Hybridization

To investigate the expression profile of maize genes induced by submergence, a subtracted cDNA library of maize seedling roots was constructed using suppression subtractive hybridization (SSH). The cDNA of maize seedling roots treated with submergence (ST) was used as tester and what from untreated roots (UT) as driver. Products of the secondary PCR from the forward subtraction were cloned into T/A vector and transferred into Escherichia coli strain JM10B by electroporation. Four hundred and eight randomly chosen transformants carrying cDNA fragments were screened with PCR-Select Deferential Screening Kit. One hundred and eighty-four cDNA clones were identified as, submergence specifically induced or highly expressed. After sequencing and removing redundant cDNAs, we got 95 submergence-induced cDNA clones. Of the 95 cDNA clones, 68 contain the regions with 60%-90% identity to their homolog in GenBank, 21 are expected to be novel genes, only 6 correspond to the published maize sequences.

Synthesis and electrochemical properties of highly dispersed Li_(4)Ti_(5)O_(12)nanocrystalline for lithium secondary batteries

A sol-gel method using lauric acid as surfactant was used to synthesize Li4Ti5O12 nanocrystals with an ultra-fine particle size distribution between 120 and 250 nm.In order to obtain the electrode materials with the best electrochemical performance,the content of lauric acid during Li4Ti5O12 synthesis was systematically studied.The physical and electrochemical properties of the synthesized samples were characterized by X-ray diffraction（XRD）,field emission scanning electron microscopy（FESEM）,transmission electron microscopy（TEM）,laser particle size analysis,alternating current impedance（AC） and galvanostatic charge-discharge experiments.The highly dispersed Li4Ti5O12 nanocrystals obtained at 800 ℃ for 10 h can deliver a specific capacity of 163.3 mA-h/g at 1C rate without obvious capacity fade up to 50 cycles.The results suggest that well dispersed Li4Ti5O12 nanocrystals shorten the Li-ion diffusion length and enhance the electrochemical kinetics of the samples,which are very crucial to high rate capability.

The Inheritance and Expression of cry1A Gene in Transgenic Maize

We investigated the inheritance and expression of cry1A gene in transgenic maize ( Zea mays L.) by Southern blotting analysis and enzyme_linked immunosorbent assays (ELISA). The results showed that cry1A had been transmitted to progeny of transgenic maize as a single gene. Contents of cry1A insecticidal protein were significantly different among transgenic maize lines and various tissues of the same transgenic lines. High expression of cry1A protein occurred in green tissues, such as leaf and husk leaf, and low expression occurred in pith, tassel, ear pith, pollen and silk. The results also showed that the contents of cry1A insecticidal protein in leaves of transgenic maize increased with the advance of development and there was no significant difference in cry1A expression level among various generations of transgenic maize.

Effects of surface nanocrystallization on corrosion resistance of β-type titanium alloy

Surface mechanical attrition treatment (SMAT) was performed on biomedicalβ-type TiNbZrFe alloy for 60 min at room temperature to study the effect of surface nanocrystallization on the corrosion resistance of TiNbZrFe alloy in physiological environment. The surface nanostructure was characterized by TEM, and the electrochemical behaviors of the samples with nanocrystalline layer and coarse grain were comparatively investigated in 0.9% NaCl and 0.2% NaF solutions, respectively. The results indicate that nanocrystallines with the size of 10-30 nm are formed within the surface layer of 30 μm in depth. The nanocrystallized surface behaves higher impedance, more positive corrosion potential and lower corrosion current density in 0.9%NaCl and 0.2%NaF solutions as compared with the coarse grain surface. The improvement of the corrosion resistance is attributed to the rapid formation of stable and dense passive film on the nanocrystallized surface of TiNbZrFe alloy.

Synthesis of Cu2O/Ag Composite with Visible Light Photocatalytic Degradation Activity for in situ SERS Analysis

A multifunctional Cu2O/Ag micro-nanocomposite, which has the characteristics of high cat- alytic activities under the visible light and high surface-enhanced Raman scattering （SERS） activity, was fabricated via a facile method and employed for the in situ SERS monitoring of the photocatalytic degradation reaction of crystal violet. Through the variation of the AgNO3 concentration, Ag content on the Cu2O template can be controllably tuned, which has great influence on the SERS effect. The results indicate that Ag nanopartieles form on the Cu2O nanoframes to obtain the Cu2O/Ag nanoeomposite, which can act as an excellent bifunetional platform for in situ monitoring of photocatalytic degradation of organic pollutions by SERS.

Synthesis and optical properties research of gold nanoparticles with different morphologies

This paper presents an approach to synthesis of gold nanoparticles with different morphologies and investigation of the relationship between morphologies and their optical properties.Spherical gold nanoparticles with different sizes are synthesized via reduction method.Using seed-mediated solution growth method,gold nanoparticles with shuttle,star and stick shapes can be obtained.The sizes and morphologies of the gold nanoparticles are characterized by transmission electron microscopy （TEM）.The characterization results illustrate the growth process of the gold nanoparticles with different morphologies.Absorption spectroscopy and Raman spectroscopy measurements are performed to demonstrate the relationship between the morphologies and optical properties.The results of Raman characterization show that the gold nanoparticles with different morphologies can be used to probe molecules with different concentrations.

Construction of Maize Universal Expression Vector PGM-35Sbar and Maize Transformation

[Objective] The paper was to construct maize universal expression vector, in order to provide basis for using transgenic methods to improve abiotic stress tolerance of maize. [Method] Based on the transformation of existing pGreen0229 plant expression vector, phosphinothricin-resistant selectable marker-bar gene driving by CaMv35S promoter was constructed, which could be used to connect target gene of maize expression vector PGM-35Sbar, and transform Ji444 maize inbred lines by pollen tube pathway. [Result] The universal expression vector for PGM-35Sbar maize had been successfully constructed. When the maize plants were transformed, 14 resistant plants were obtained, and 12 plants were identified to be positive plants by PCR detection. [Conclusion] The study provided basis for rapid construction of maize expression vector containing specific target gene.

地面温度规范化的重要性

地面温度的准确性存在着很大的人为原因.《规范》要求:“地温场地表疏松…,表身和感应部分一半埋入土中,一半露出地面,埋入部分便与土壤密贴,不可留空隙”.这一规定看着容易,做好却不易,且做好与否对内在质量关系很大. 1、地表疏松.关键是靠观测员的责任心,要及时疏松不但关系到“一半入土”

Preparation and stability of zinc ferrite nano-particle suspension of ammonia-water solution

In order to apply nano-particles to the ammonia-water absorption refrigeration, the zinc ferrite nano-particles suspension of ammonia-water solution with the mixed surfactants of sodium dodecyl benzene sulfonate （SDBS） and cetyl trimethyl ammonium bromide （CTAB） is prepared. A series of experiments is performed to investigate the stability of the prepared nanofluid with different contents and proportions of surfactants, different durations of ultrasonic wave vibration and different durations of illumination. The optimal dispersion conditions are 1.5% SDBS, 0. 015% CTAB（mass fraction）, 30 min of ultrasonic vibration and over 72 h of illumination. Finally, based on double electrode layer theory, the influences of the content of the surfactants on the stability of nanofluid are analyzed. The existence of the optimal surfactant content is proved, which is in accordance with the experimental results.

Investigation on Quick Surface Metallization of Nano Titania Powder

Quick surface metallization of titania powder was carried out by electrolesschemical deposition of nickel. The fabricated product was characterized by XRD, SEM, FTIR andcross-section metallography. The analysis results show that titania particles are completely coatedby a thin nickel shell about 600 nm thick composed of nano-sized crystalline nickel particles.Mechanism of nickel chemical deposition on nano powder is proposed.

Nanogrinding of SiC wafers with high flatness and low subsurface damage

Nanogrinding of SiC wafers with high flatness and low subsurface damage was proposed and nanogrinding experiments were carried out on an ultra precision grinding machine with fine diamond wheels. Experimental results show that nanogrinding can produce flatness less than 1.0μm and a surface roughness Ra of 0.42nm. It is found that nanogrinding is capable of producing much flatter SiC wafers with a lower damage than double side lapping and mechanical polishing in much less time and it can replace double side lapping and mechanical polishing and reduce the removal amount of chemical mechanical polishing.

Photoluminescence of [Eu(bpy)_2]^(3+) dispersed in MCM-41 and HMS

[Eu(bpy)_2]^(3+) (bpy:2,2'-bipyridine) was encapsulated in hexagonalmesoporous materials MCM-41 and HMS. XRD spectra, ICP analysis, IR spectra, N_2 adsorptionmeasurements and the photoluminescence spectra were used to characterize the correspondingimpregnated samples. After the impregnation of [Eu(bpy)_2]^(3+), the BET surface, pore diameters andpore volume of the impregnated samples were decreased. All the impregnated samples exhibited thetypical photoluminescence of Eu^(3+) when excited with a xenon lamp. Compared with the impregnatedHMS, the impregnated MCM-41 samples show higher photoluminescence efficiency for the impregnation of[Eu(bpy)_2]^(3+). It suggests that MCM-41 is a more efficient host for the photoluminescence ofeuropium complexes than HMS.

采蟾酥过好五道关

浙江省海宁市龙头阁两栖爬行动物研究所在总结采集蟾酥中,有一套经验:采集蟾酥要"关关相护"才行,一道关互"洁身自好"。就是将蟾蜍洗干净,达到体表无泥土,晾干后使耳后变软,掐取蟾酥。二道关互"济济满堂"。就是用手挤蟾酥时,先用左手将蟾酥从头往下掇,再捉住前后四条脚,蟾蜍腹部就会鼓起,耳后腺当即膨大;然后右手拿铝制夹子挤两个耳后腺,

Affinity and fluorescent detection of surfactants/ssDNA and single-walled carbon nanotube

A new biosensor platform was explored for detection of surfactant based on fluorescence changes from single strand DNA （ssDNA） and single-walled carbon nanotubes （SWNTs）. Thermodynamics assay was performed to value the stability of probe. The affinities of SWNT to five common surfactants （SDS, DBS, Triton X-100, Tween-20 and Tween-80） were investigated by real-time fluorescence method. The effects of Mg^2＋ and pH on the fluorescence intensity of self-assembled quenched sensor were performed. The fluorescent emission spectra were used to measure the responses of self-assembled quenched fluorescent of ssDNA/SWNTs to different concentration surfactant（Triton X-100）. The FAM-DNA wrapped SWNTs probe was stable in a wide temperature range （5 ℃ to 80℃）. The binding strength of surfactants and single-stranded DNA （ssDNA） on SWNTs surfaces was shown as follows： Triton X-100〉DBS〉Tween-20〉Tween-80〉ssDNA〉SDS, and the optimized reaction conditions included pH 7.4 and 10 mmol/L Mg2＋. The fluorescence of FAM-ssDNA wrapped SWNTs was proportionally recovered as a result of adding different concentrations of Triton X- 100, which realizes the quantitative detection of Triton X- 100.

Preparation of gradient wettability surface by anodization depositing copper hydroxide on copper surface

A facile route for preparation of gradient wettability surface on copper substrate with contact angle changing from 90.3°to4.2°was developed.The Cu（OH）2 nanoribbon arrays were electrochemically deposited on copper foil via a modified anodization technology,and the growth degree and density of the Cu（OH）2 arrays may be controlled varying with position along the substrate by slowly adding aqueous solution of KOH into the two-electrode cell of an anodization system to form the gradient surface.The prepared surface was water resistant and thermal stable,which could keep its gradient wetting property after being immersed in water bath at 100℃ for 10 h.The results of scanning electron microscopy（SEM）,X-ray diffraction（XRD） and X-ray photoelectron spectroscopy（XPS） demonstrate that the distribution of Cu（OH）2 nanoribbon arrays on copper surface are responsible for the gradient wettability.

Triangular Au-Ag framework nanostructures prepared by multi-stage replacement and their spectral properties

Triangular Au-Ag framework nanostructures （TFN） were synthesized via a multi-step galvanic replacement reaction （MGRR） of single-crystalline triangular silver nanoplates in a chlorauric acid （HAuCl4） solution at room temperature. The morphological, compositional, and crystal structural changes involved with reaction steps were analyzed by using transmission electron microscopy（TEM）, energy-dispersive X-ray spectrometry （EDX）, and X-ray diffraction. TEM combined with EDX and selected area electron diffraction confirmed the replacement of Ag with Au. The in-plane dipolar surface plasmon resonance （SPR） absorption band of the Ag nanoplates locating initially at around 700 nm gradually redshifted to 1 100 nm via a multi-stage replacement manner after 7 stages. The adding amount of HAuCl4 per stage influenced the average redshift value per stage, thus enabled a fine tuning of the in-plane dipolar band. A proposed formation mechanism of the original Ag nanoplates developing pores while growing Au nanoparticles covering this underlying structure at more reaction steps was confirmed by exploiting surface-enhanced Raman scattering （SERS）.

Probe the Effects of Surface Adsorbates on ZnO Nanowire Conductivity using Dielectric Force Microscopy

Characterization of electric properties of nanomaterials usually involves fabricating field effect transistors （FET） and deriving materials properties from device performances. However, the quality of electrode contacts in FET devices heavily influences the device performance, which makes it difficult to obtain the intrinsic electric properties of nanomaterials. Dielectric force microscopy （DFM）, a contactless method developed recently, can detect the low-frequency dielectric responses of nanomaterials without electric contact, which avoids the influence of electric contact and can be used to study the intrinsic conductivity of nanomaterials. Here we study the influences of surface adsorbates on the conductivity of ZnO nanowires （NWs） by using FET and DFM methods. The conductivity of ZnO NW is much larger in N2 atmosphere than that in ambient environment as measured by FET device, which is further proven by DFM measurement that the ZnO NW exhibits larger dielectric response in N2 environment, and the influence of electrode contacts on measurement can be ruled out. Based on these results, it can be concluded that the adsorbates on ZnO NW surface highly influence the conductivity of ZnO NW rather than the electrode contact. This work also verifies the capability of DFM in measuring electric properties of nanomaterials.