Effect of Low Temperature Treatment on Agrobacterium-mediated Transformation of Maize Seed Buds

[Objectives]This study was conducted to improve the genetic transformation rate of maize. [Methods]The seeds of maize ＂ Zheng 58＂ as the experimental material were germinated and treated under freezing temperature of-18 ℃ for 30 and 35 min. The EGFP gene was transformed into the growth points of these seed buds by Agrobacterium tumefaciens EHA105. The transformation effect was determined by fluorescence protein detection on transformed buds. [Results]After a certain period of treatment at-18 ℃ following germination and transformation of maize bud growth points with A. tumefaciens,although the survival rate of maize buds was reduced,the percentage of transformed cells significantly increased. [Conclusions]Low temperature treatment can improve the transformation efficiency of A. tumefaciens to the growth point of maize bud.

Effects of Low Temperature Treatment on Bolting of Radish(Raphanus sativus L.)

[Objectives]This study was conducted to screen out a vernalization method of radish that is more suitable for breeding and hybrid production.[Methods]Eight radish inbred lines with different bolting tolerance were used as the research objects for the experiment.The following three treatments were done:(1)treating at 4℃in the dark with heat preservation for 1,2,3,4,and 5 weeks,respectively~([1]),(2)treating at 4℃in the dark with heat preservation for 3 weeks after 24 h incubation in light at 20℃,and(3)treating under light at a low temperature of 6.5℃for three weeks after cultivating under light at 20℃to 4 true leaves.The effects of low temperature treatment on the bolting and flowering time of different varieties of radish treated at different developmental stages were analyzed.[Results]When comparing these three methods,the low-temperature treatment of wet seeds had a better effect on early bolting of radish and is simpler and more feasible.The effect of treating four-leaf seedlings at 6.5℃was the worst;most radish inbred lines could shorten bolting time when treated at 4℃for one week;and within a certain range,the longer the 4℃treatment time,the better the vernalization effect.Different radish inbred lines had different performances to low temperature treatment.[Conclusions]This study provides a scientific basis for the theoretical research on vernalization of radish.

Polyphenol content and antioxidant activity in mulberry powder treated at high temperature

The aim of this study was to investigate changes of polyphenols content and the antioxidant activity of mulberry fruit powder after heating at high temperature.The mulberry fruit powder was heated by baking method at different temperature and time.The DPPH scavenging ability,the OH^(•-) scavenging ability and the O_(2)^(•-) scavenging ability were used to evaluate the changes in the antioxidant activity of the mulberry fruit powder after the heat treatment.The results showed that 74.87%of the polyphenols in the mulberry powder were lost after heating at 150℃for 5 min,and almost all the polyphenols were lost with the increase of the heating time and temperature.The antioxidant experiment showed that the DPPH scavenging rate,OH^(•-) scavenging rate and O_(2)^(•-) scavenging rate of mulberry fruit powder were 68.90%,39.15%and 14.09%,respectively after treatment at 150℃ for 5 min.Mulberry fruit powder still has some potential to be added to baked goods as a functional ingredient.

Effect of Heat Treatment Temperature on Properties of Chinese Calcined Flint Clay Based Plastic Refractories

Effects of different heat treatment temperatures on properties of Chinese calcined flint clay based plastic refractories were investigated using Chinese calcined flint clay as starting material, aluminum sulfate and fireclay as binding system. The results showed that with temperature rising, Chinese calcined flint clay based plastic refractories shrinked firstly and then expanded. The modulus of rupture （MOR） and the cold crushing strength （CCS） inereased firstly and then decreased from 110 ℃ to 600 ℃ , then increased obviously. Thermal expansion coefficient increased from 110 ℃ to 760 ℃, decreased from 760 ℃ to 1 300 ℃ , and increased from 1 300 ℃ to1500 ℃.

Fretting Wear Behavior of Medium Carbon Steel Modified by Low Temperature Gas Multi-component Thermo-chemical Treatment

The introduction of surface engineering is expected to be an effective strategy against fretting damage. A large number of studies show that the low gas multi-component （such as carbon, nitrogen, sulphur and oxygen, etc） thermo-chemical treatment（LTGMTT） can overcome the brittleness of nitriding process, and upgrade the surface hardness and improve the wear resistance and fatigue properties of the work-pieces significantly. However, there are few reports on the anti-fretting properties of the LTGMTT modified layer up to now, which limits the applications of fretting. So this paper discusses the fretting wear behavior of modified layer on the surface of LZ50 （0.48%C） steel prepared by low temperature gas multi-component thermo-chemical treatment （LTGMTT） technology. The fretting wear tests of the modified layer flat specimens and its substrate （LZ50 steel） against 52100 steel balls with diameter of 40 mm are carried out under normal load of 150 N and displacement amplitudes varied from 2 μm to 40 μm. Characterization of the modified layer and dynamic analyses in combination with microscopic examinations were performed through the means of scanning electron microscope（SEM）, optical microscope（OM）, X-ray diffraction（XRD） and surface profilometer. The experimental results showed that the modified layer with a total thickness of 60 μm was consisted of three parts, i.e., loose layer, compound layer and diffusion layer. Compared with the substrate, the range of the mixed fretting regime（MFR） of the LTGMTT modified layer diminished, and the slip regime（SR） of the modified layer shifted to the direction of smaller displacement amplitude. The coefficient of friction（COF） of the modified layer was lower than that of the substrate in the initial stage. For the modified layer, the damage in partial slip regime（PSR） was very slight. The fretting wear mechanism of the modified layer both in MFR and SR was abrasive wear and delamination. The modified layer presented better wear resistance than the substrate in PSR and MFR; however, in SR, the wear resistance of the modified layer decreased with the increase of the displacement amplitudes. The experimental results can provide some experimental bases for promoting industrial application of LTGMTT modified layer in anti-fretting wear.

Effect of Treatment Temperature on Iron Nitride Foils Irradiated with Nitrogen Plasma

We investigated the effect of treatment temperature on the magnetic property of iron nitride foils irradiated with nitrogen plasma. The iron nitride foils irradiated with nitrogen plasma were composed of ε-Fe2/3N, γ'-Fe4N and γ nitrogen austenite in α-Fe of the matrix. The saturation magnetization of the iron nitride foils decreased with increasing the surface temperature. The coercive force of the iron nitride foils increased with increasing the surface temperature.

Effect of heat treatment temperature of the glaze lager on the structure and the formaldehyde removal performance of an interior wall tile

With the improvement of people’s living standards,a large number of petroleum products,daily necessities and decorations that can produce volatile organic compounds are used in decoration,which seriously affects the indoor air quality.Interior decoration materials have become a research hotspot in recent years.The purpose of this paper is to develop a kind of interior wall material with good indoor formaldehyde removal effect,easily using,and low cost.In this paper,combining different heat treatment temperatures of the glaze layer,tourmaline/diatomite-based interior wall tiles were prepared by ultrafine grinding,solid sintering,and low temperature calcination.The glaze layer under different heat treatment temperatures was characterized by thermogravimetric-differential thermal analysis,X-ray diffraction,and scanning electron microscope.The influences of heat treatment temperature on the microscopic morphology and structure of the glaze layer were analyzed.Taking formaldehyde as the target degradation product,the effects of tourmaline/diatomite-based interior wall tiles on the removal of formaldehyde under different heat treatment temperatures of the glaze layer were investigated.The results showed that with the increase in heat treatment temperature,the original pores of diatomite decreased,the specific surface area decreased,and the structure of tourmaline changed.At 850℃,the surface structure of the material was slightly damaged,the strength was increased,and the removal effect of formaldehyde was better.In a 1 m^(3) environmental chamber,the formaldehyde removal rate reached 73.6%in 300 min.When the temperature was increased to 950℃ and above,diatomite and the structure of tourmaline were destroyed,and the ability of the material to adsorb and degrade formaldehyde decreased.

Influence of Heat Treatment Temperature on Microstructure and Bonding of TiO2 Film Coated on Diamond Particles Surface

TiO_2 films were coated on the surface of diamond particles using a sol-gel method. The effects of heat treatment temperature on the morphology, phase composition and chemical bond of diamond particles coated with TiO2 films were investigated through SEM, TEM, X-ray diffraction analysis, Raman spectroscopy, FTIR, and XPS. The results showed that when being heat-treated at 600 ℃, the amorphous TiO_2 film transfered to the anatase film which bonded well with diamond substrate. Meanwhile, the Ti-O-C bond formed between TiO2 film and diamond substrate. When being heat-treated at 800 ℃, TiO2 film was still anatase, and partial diamond began to graphitize. The graphitizated carbon could also form the Ti-O-C bond with TiO_2 film, although TiO_2 film would tend to crack in this case.

Spent graphite regeneration:Exploring diverse repairing manners with impurities-catalyzing effect towards high performance and low energy consumption

Spent battery recycling has received considerable attention because of its economic and environmental potential.A large amount of retired graphite has been produced as the main electrode material,accompanied by a detailed exploration of the repair mechanism.However,they still suffer from unclear repair mechanisms and physicochemical evolution.In this study,spent graphite was repaired employing three methodologies:pickling-sintering,pyrogenic-recovery,and high-temperature sintering.Owing to the catalytic effect of the metal-based impurities and temperature control,the as-obtained samples displayed an ordered transformation,including the interlayer distance,crystalline degree,and grain size.As anodes of lithium ions batteries,the capacity of repaired samples reached up to 310 mA h g^(-1)above after 300loops at 1.0 C,similar to that of commercial graphite.Meanwhile,benefitting from the effective assembly of carbon atoms in internal structure of graphite at>1400℃,their initial coulombic efficiency were>87%.Even at 2.0 C,the capacity of samples remained approximately 244 mA h g^(-1)after 500 cycles.Detailed electrochemical and kinetic analyses revealed that a low temperature enhanced the isotropy,thereby enhancing the rate properties.Further,economic and environmental analyses revealed that the revenue obtained through suitable pyrogenic-recovering manners was approximately the largest value(5500$t^(-1)).Thus,this study is expected to clarify the in-depth effect of different repair methods on the traits of graphite,while offering all-round evaluations of repaired graphite.

INFLUENCE OF HEAT TREATMENT ON OXIDATION PROPERTIES OF C/C COMPOSITES FABRICATED BY HIGH PRESSURE IMPREGNATION CARBONIZATION

Felt base carbon/carbon composites fabricated by super-high pressure impregnation carbonization process (SPIC) were heat treated at high temperature 2773K. The oxidation properties of felt base carbon/carbon composites were investigated at different temperatures (773-1173K), and the microstructures of carbon/carbon composites were studied by SEM and X-ray diffraction. The experimental results showed that the inter-laminar distance of (002) plane (d002) deceased while the microcrystalline stack height (Lc) increased. The oxidation rate of felt base carbon/carbon composites was invari-able at certain temperatures. The oxidation mechanism of carbon/carbon composites changed remarkably at the oxidation temperature 973K. At the initial oxidation stage of carbon/carbon composites, carbon matrix was oxidized much more rapidly than carbon felt.

Low-temperature Rapid Synthesis of Ultrafine Hafnium Carbide Ceramic Powders

Nano hafnium carbide（HfC） powders were synthesized by sol-gel combining hightemperature rapid heat treatment process using citric acid and hafnium tetrachloride as the raw materials. The effects of ball milling treatment on the phase and morphology of pyrolysis products（HfO_2-C） and final HfC product were investigated and the influences of heat treatment temperature and holding time on the structure and properties of the synthesized hafnium carbide powders were also studied. The experimental results showed that the HfO_2-C powders with good uniformity and small particle size were prepared by controlling the milling time. Pure HfC powders with an average particle size of 500 nm were obtained at 1 700 ℃ with a holding time of 3 min, and the oxygen content was about 0.69 wt%, lower than that of the hafnium carbide powders prepared by SPS（0.97%）.

Room temperature NO2-sensing properties of hexagonal tungsten oxide nanorods

Hexagonal WO_3 nanorods were synthesized through a facile hydrothermal method. The nanorods properties were investigated by scanning electron microscope（SEM）, transmission electron microscope（TEM）, energy dispersive spectroscopy（EDS）, and x-ray diffraction（XRD）. The NO_2-sensing performances in terms of sensor response, response/recovery times and repeatability at room temperature were optimized by varying the heat treatment temperature of WO_3 nanorods. The optimized NO_2sensor（400-℃-annealed WO_3 nanorods） showed an ultra-high sensor response of 3.2 and short response time of 1 s to 5-ppm NO_2. In addition, the 400-℃-annealed sample exhibited more stable repeatability.Furthermore, dynamic responses measurements of annealed samples showed that all the annealed WO_3 nanorods sensors presented p-type behaviors. We suppose the p-type behavior of the WO_3 nanorods sensor to be that an inversion layer is formed in the space charge layer when the sensor is exposed to NO_2 at room temperature.Therefore, the 400-℃-annealed WO_3 nanorods sensor is one of the most energy conservation candidates to detect NO_2 at room temperature.

Synthesis of Iron-containing Carbon Microparticles from Deoiled Asphalt and Ferrocene

The deoiled asphalt as the carbon source and the ferrocene as the metal source and the catalyst precursor were chosen to synthesize iron-containing carbon microparticles through co-carbonization at the temperature of about 450℃ for 3 h. The resulting products were treated at 2 000 ℃ for 2 h. All samples were examined by high resolution transmission electron microscopy （HRTEM） and X-ray diffraction （XRD）. The results show that the iron particles in the heat-treated material are completely coated by carbon. In addition to the fully filled carbon microparticles as well as hollow carbon ones, also form carbon fibers with hollow centers. The formation mechanism of the as-prepared products was discussed briefly.

Photoacoustic characteristics of lipid-rich plaques under ultra-low temperature and formaldehyde treatment

Photoacoustic imaging （PAI） has been used to characterize the spatial and quantitative features of lipid-rich atherosclerotic plaques with high sensitivity and specificity. In this Letter, we first validate that the ultra-low temperature and formaldehyde treatment have no effect on photoacoustic characteristics of the artery samples. Comparative experiments between the PAI and histological results demonstrate that the ultra-low temperature or formaldehyde treatment has few effects on the PAI of the lipid-rich atherosclerotic plaques; the lipid relative concentration and the lipid percentage by PAI hold high correlation with histology.

Effect of rhenium on the microstructure and mechanical behavior of Fe–2.25Cr–1.6W–0.25V-0.1C bainitic steels

A new ferritic creep resistant steel has been developed by eliminating Nb and adding 1.5 mass % Re to a ferritic steel grade T/P23 with the aim of enhancing its mechanical properties at high temperature.Cast ingots of both steels, new grade and ASTM T/P 23, were hot rolled at 900℃ and then submitted to a thermal treatment consisting of solubilization at 1050℃ and tempering at 700℃. Tempered bainitic microstructures obtained contain second phases reinforcing carbide particles, mainly M_6C and M_（23）C_6 at the boundaries of both, prior austenite grains and bainitic ferrite laths, as well as MC within the grains. Mechanical properties at temperatures ranging from 540 to 600℃ were studied by strain-ratechange tests in compression at strain rates between 10^（-7） and 10^（-4）s^（-1）. These tests showed high stress exponents（n ≥ 20） and activation energies（Q ≈ 400 k J/mol） for both alloys, which were associated with a dislocation movement mechanism with a strong interaction between dislocations and precipitates. On the other hand, a creep exponent of 5 was derived for the stress dependence of minimum creep rate from conventional-type creep tests at 600℃. Although this stress exponent is usually related to a dislocation climb controlled creep mechanism, remarkable microstructural degradation observed with increasing creep time makes difficult to elucidate the true deformation mechanism controlling creep.