Sixty-four Holstein steers (247 ± 4 kg) were used in a 70-d experiment to evaluate the effects of partial replacement of steam flake corn (SFC) with extruded corn meal (EC) on growth performance and dietary net e...Sixty-four Holstein steers (247 ± 4 kg) were used in a 70-d experiment to evaluate the effects of partial replacement of steam flake corn (SFC) with extruded corn meal (EC) on growth performance and dietary net energy. Treatments consisted of a steam flaked corn-based finishing diet containing 0%, 10%, 20%, or 30% EC, where EC replaced 0%, 15%, 30%, or 45% of SFC (DM basis). Replacement of SFC with increasing levels of EC did not affect (P > 0.10) ADG, DMI, and gain efficiency. When EC replaced 15% to 30% of SFC, observed dietary NE was 99% of expected. Whereas, when EC replaced 45% of SFC, observed dietary NE was 94% of expected. Four Holstein steers (210 ± 7 kg) with cannulas in the rumen and proximal duodenum were used in a 4 × 4 Latin square experiment to evaluate treatment effects on characteristics of digestion. Partial replacement of SFC with EC did not affect (P > 0.10) flow of undegraded feed N and microbial N and to the small intestine, and ruminal microbial N efficiency (g microbial N/kg OM fermented). Likewise, there were no treatment effects (P > 0.10) on ruminal digestion of OM, NDF, starch and feed N. As expected, total tract digestion of starch for all treatments exceeded 99%. However, partial replacement of SFC with EC decreased total tract digestion of DM and OM (linear effect, P = 0.02), and dietary DE (linear effect, P = 0.03). These effects were more pronounced where EC replaced 45% of SFC. Partial replacement of SFC with EC did not affect (P > 0.10) ruminal pH, total VFA concentration, molar proportions of acetate, propionate, and butyrate, and estimated methane production. It is concluded that partial replacement of SFC with EC does not have a beneficial effect on ruminal microbial efficiency and digestive function. The feeding value of extruded corn for feedlot cattle is comparable to that of steam flaked corn provided the inclusion rate does not exceed 20% of diet dry matter.展开更多
We study systematically the negative magnetoresistance(MR)effect in WTe_(2±α)flakes with different thicknesses and doping concentrations.The negative MR is sensitive to the relative orientation between electrica...We study systematically the negative magnetoresistance(MR)effect in WTe_(2±α)flakes with different thicknesses and doping concentrations.The negative MR is sensitive to the relative orientation between electrical-/magnetic-field and crystallographic orientation of WTe_(2±α).The analysis proves that the negative MR originates from chiral anomaly and is anisotropic.Maximum entropy mobility spectrum is used to analyze the electron and hole concentrations in the flake samples.It is found that the negative MR observed in WTe_(2±α)flakes with low doping concentration is small,and the high doping concentration is large.The doping-induced disorder obviously inhibits the positive MR,so the negative MR can be more easily observed.In a word,we introduce disorder to suppress positive MR by doping,and successfully obtain the negative MR in WTe_(2±α)flakes with different thicknesses and doping concentrations,which indicates that the chiral anomaly effect in WTe_(2)is robust.展开更多
Graphene flakes(GF)have been prepared and assessed as a material for improving flow in oil pipelines under the effect of an electric field.In particular,different amounts of GFs have been considered in order to determ...Graphene flakes(GF)have been prepared and assessed as a material for improving flow in oil pipelines under the effect of an electric field.In particular,different amounts of GFs have been considered in order to determine the optimal flow conditions.The GFs were prepared from graphite foam,derived from the dehydration of sugar with a particle size of 500-600μm,which was dispersed in ethanol and exfoliated in a ball mill under a shear force.After 15 h of exfoliation,sonication,and subsequent high-speed centrifugation at 3000 rpm,irregular-shaped GFs of 50-140 nm were produced and characterized using scanning electron microscopy,X-ray diffractometry,atomic force microscopy,and Raman spectroscopy.The prepared graphene sheets have been found to display excellent morphology and good graphitic structure.Experiments on flow improvement were conducted using the central composite rotatable design method for three parameters:stimulation time(15,30,45,and 60 s),applied voltage(150,170,200,and 220 V),and concentration of the GFs(0,100,200,and 400 mg/L).The optimal conditions for improved crude oil flow were then determined using the STATISTICA and WinQSB software packages.The results have confirmed the effectiveness of the use of the prepared GFs as a flow improver for crude oil,where the flow improvement is essentially a result of a reduction in viscosity and suppression of friction in the crude oil system.展开更多
湖泊对气候变化非常敏感,是气候变化的指示器。青藏高原湖泊众多,但由于观测数据的缺乏,目前对全球变暖背景下高原湖泊热力状况的研究依然不足且多为短期研究。利用中国科学院青藏高原研究所(ITPCAS)开发的中国区域高时空分辨率地面气...湖泊对气候变化非常敏感,是气候变化的指示器。青藏高原湖泊众多,但由于观测数据的缺乏,目前对全球变暖背景下高原湖泊热力状况的研究依然不足且多为短期研究。利用中国科学院青藏高原研究所(ITPCAS)开发的中国区域高时空分辨率地面气象要素驱动数据集、MODIS地表温度数据、青海湖浮标观测数据,分析了Freshwater Lake Model(简称Flake模式)在青海湖的适用性,揭示了青海湖热力状况对气候变化的响应。结果表明,Flake模式能够很好的模拟出青海湖的热力状况,但对夏季与秋季的湖表面水温(特别是夜间)模拟偏高,部分是驱动数据误差造成的,修正驱动数据后模拟效果得到改善。对1989 2012年Flake模拟的湖表面温度与ITPCAS数据不同驱动要素之间的年际变化趋势与相关性进行分析,发现青海湖表面温度呈现上升趋势,与气温、向下长波辐射有较好的正相关性,而与风速负相关。内部热力状况的模拟结果显示,青海湖混合层温度基本全年呈上升趋势,其中5、6月及12月增温最显著;湖泊底层温度在5月以及12月的两次季节性翻转时期呈上升趋势,在6 10月湖水分层期呈下降趋势,分层期湖泊上层温度升高会加强湖水层结稳定性,使湖水混合减弱,导致底层温度下降。展开更多
The mineralogy and petrography of natural graphite in Saba Boru of Ethiopia indicate that there exists flake graphite with a slightly oval structured fine size according to our study on thin and polished sections.Here...The mineralogy and petrography of natural graphite in Saba Boru of Ethiopia indicate that there exists flake graphite with a slightly oval structured fine size according to our study on thin and polished sections.Herein,for estimating the carbon content in graphite,the ASTM-C561,the test method for ash in a graphite sample,was used.For characterizing graphite,x-ray diffraction,x-ray fluorescence,inductively coupled plasma mass spectroscopy,and scanning electron microscopy were also used.Chemical analysis of ore samples determined that the average compositions are 63.35%SiO2,15.45%Al2O3,2.36%Fe2O3,2.07%K2O,less than1%others,and loss-on-ignition(LOI)in the range of^4.74%–37.42%.The total carbon content of graphitic ore ranged from 4.11%to 33.14%.Importantly,when graphite is concentrated through floatation,its average purity and recovery are 92.97%and 90.82%,respectively.Furthermore,once the graphite concentrates are treated with hydrofluoric acid,the average value attains a high grade of 96.48%C.Moreover,the average ash content is 81.93%(pre-flotation)and 3.1%(post-flotation),respectively.Finally,after beneficiation,a silica is identified as a major gangue(85.88%),usable as a raw material for other purposes such as cement.Hence,these graphite-bearing rocks seem to be worth exploring for commercialization opportunities.展开更多
The FTP200 flake tantalum powder was introduced.The microstructures of the powder with leaf-like primary particles having an average flakiness of 2 to 20 and porous agglomerated particles were observed.The chemical co...The FTP200 flake tantalum powder was introduced.The microstructures of the powder with leaf-like primary particles having an average flakiness of 2 to 20 and porous agglomerated particles were observed.The chemical composition,physical properties,and electrical properties of the FTP200 powder were compared with those of the FTW300 nodular powder.The FTP200 powder is more sinter-resistant,and the surface area of the flake tantalum powder under sintering at high temperature has less loss than that of the nodular tantalum powder.The specific capacitance of the flake tantalum powder is higher than that of the nodular tantalum powder with the same surface area when anodized at high voltage.Thus,the flake tantalum powder is suitable for manufacturing tantalum solid electrolytic capacitors in the range of median and high(20-63 V) voltages.展开更多
To explore the mechanism of carbonyl iron flake composites for microwave complex permeability, this paper investigates the feature of the flakes. The shape anisotropy was certified by the results of the magnetization ...To explore the mechanism of carbonyl iron flake composites for microwave complex permeability, this paper investigates the feature of the flakes. The shape anisotropy was certified by the results of the magnetization hysteresis loops and the Mossbauer spectra. Furthermore, the shape anisotropy was used to explain the origin of composite microwave performance, and the calculated results agree with the experiment. It is believed that the shape anisotropy dominates microwave complex permeability, and the natural resonance plays main role in flake.展开更多
The properties of gray cast iron(GCI)are affected by density of matrix,size of flake graphite and primary austenite.In this paper,the Y-type specimen of GCI was prepared by lost foam casting(LFC)with and without vibra...The properties of gray cast iron(GCI)are affected by density of matrix,size of flake graphite and primary austenite.In this paper,the Y-type specimen of GCI was prepared by lost foam casting(LFC)with and without vibration,and the influence of vibration frequency on the density of matrix,size of primary phase,and properties of the GCI was studied.The results show that the length of the flake graphite and the size of the primary austenite in GCI firstly decrease and then increase with the increase of the vibration frequency.With a vibration frequency of 35 Hz,the length of the flake graphite is the shortest,the primary austenite is the finest and the density of the matrix is the highest.In addition,the tensile strength,elongation and hardness of the GCI firstly increase and then decrease with the increase of the vibration frequency,due to the refinement of the primary phase and the increase of the matrix density.In order to analyze the refinement mechanism of the primary phase of the GCI fabricated by the LFC with vibration,the solidification temperature fields of the GCI fabricated by the LFC with the vibration frequency of 0 and 35 Hz were measured.The results show that the vibration reduces the eutectic point of the GCI and increases the supercooling degree during the eutectic transformation.As a result,the length of the flake graphite and the size of the primary austenite in GCI fabricated by LFC with the vibration frequency of 35 Hz decrease.展开更多
Developing flexible sensors with high working performance holds intense interest for diverse applications in leveraging the Internet-of-things(IoT)infrastructures.For flexible piezoresistive sensors,traditionally most...Developing flexible sensors with high working performance holds intense interest for diverse applications in leveraging the Internet-of-things(IoT)infrastructures.For flexible piezoresistive sensors,traditionally most efforts are focused on tailoring the sensing materials to enhance the contact resistance variation for improving the sensitivity and working range,and it,however,remains challenging to simultaneously achieve flexible sensor with a linear working range over a high-pressure region(>100 kPa)and keep a reliable sensitivity.Herein,we devised a laserengraved silver-coated fabric as"soft"sensor electrode material to markedly advance the flexible sensor's linear working range to a level of 800 kPa with a high sensitivity of 6.4 kPa^-1 yet a fast response time of only 4 ms as well as long-time durability,which was rarely reported before.The integrated sensor successfully routed the wireless signal of pulse rate to the portable smartphone,further demonstrating its potential as a reliable electronic.Along with the rationally building the electrode instead of merely focusing on sensing materials capable of significantly improving the sensor's performance,we expect that this design concept and sensor system could potentially pave the way for developing more advanced wearable electronics in the future.展开更多
The mixed matrix membranes(MMMs) were developed by incorporating graphite oxide(GO) flakes functionalized with iron oxide(Fe_3O_4) into Pebax matrix. The Pebax/Fe_3O_4–GO MMMs were used to separate CO_2/CH_4 and CO_2...The mixed matrix membranes(MMMs) were developed by incorporating graphite oxide(GO) flakes functionalized with iron oxide(Fe_3O_4) into Pebax matrix. The Pebax/Fe_3O_4–GO MMMs were used to separate CO_2/CH_4 and CO_2/N_2 gas mixture. The results showed that the MMMs with magnetic alignment presented the better gas separation performance than that of random arrangement of Pebax/Fe_3O_4–GO mixed matrix membranes. The reason was that the Fe_3O_4–GO flakes arranged magnetically in the membrane played a multiple role in improving the performance of MMMs. Firstly, under the action of the magnetic field,the magnetic alignment of Fe_3O_4–GO flakes in Pebax matrix constructed the shorter transfer path for gas molecule, increasing the CO_2 permeability. Secondly, the hydroxyl groups in GO flakes and the presence of Fe_3O_4 have stronger binding force for water, improving the CO_2 solubility selectivity. Thirdly, the better interaction between the magnetic alignment of GO composites and polymer matrix, reduced the interface defects. Especially, the optimum gas separation performance was obtained at the Fe_3O_4–GO flakes content of 3 wt% in Pebax matrix at vertical arrangement with selectivity of 47 and 75 for CO_2/CH_4 and CO_2/N_2, respectively, and CO_2 permeability of 538 Barrer at 0.2 MPa and room temperature.展开更多
一维湖泊模式是青藏高原湖泊研究的主要手段之一,但不同湖泊模式在青藏高原适用性及其差异依然不够明确。利用MODIS地表温度数据、青藏高原鄂陵湖站点观测的气象数据、湖温及湖面能量数据,驱动、评估和对比了目前应用最为广泛的两个一...一维湖泊模式是青藏高原湖泊研究的主要手段之一,但不同湖泊模式在青藏高原适用性及其差异依然不够明确。利用MODIS地表温度数据、青藏高原鄂陵湖站点观测的气象数据、湖温及湖面能量数据,驱动、评估和对比了目前应用最为广泛的两个一维湖泊模式Freshwater Lake Model(FLake)和Community Land Model version 4.5(CLM4.5)中耦合的湖泊模块在青藏高原典型湖泊的适用性。结果表明:FLake和CLM模式均能较好的对湖泊热力状况进行模拟,CLM模式对于湖表面温度和湖泊内部不同深度的温度模拟优于Flake模式,净辐射和能量的累积也是CLM模式的模拟值更接近观测值。造成Flake模式模拟偏差更大的原因与模式中计算感热、潜热的摩擦速度有关,观测的摩擦速度均值为0.22 m·s-1,CLM模式中的摩擦速度与观测值接近,为Flake模式的1.5倍,将CLM模式中的摩擦速度替换到Flake模式中后模拟结果有明显的改善。展开更多
The use of laser-induced breakdown spectroscopy(LIBS) for the analysis of heavy metals in water samples is investigated. Some factors such as splashing, surface ripples, extinction of emitted intensity, and a shorter ...The use of laser-induced breakdown spectroscopy(LIBS) for the analysis of heavy metals in water samples is investigated. Some factors such as splashing, surface ripples, extinction of emitted intensity, and a shorter plasma lifetime will influence the results if the water sample is directly measured. In order to avoid these disadvantages and the ‘coffee-ring effect', hydrophilic graphite flakes with annular grooves were used for the first time to enrich and concentrate heavy metals in water samples before being analyzed by LIBS. The proposed method and procedure have been evaluated to concentrate and analyze cadmium, chromium, copper, nickel, lead,and zinc in a water sample. The correlation coefficients were all above 0.99. The detection limits of 0.029, 0.087, 0.012, 0.083, 0.125, and 0.049 mgl^(-1) for Cd, Cr, Cu, Ni, Pb, and Zn,respectively, were obtained in samples prepared in a laboratory. With this structure, the heavy metals homogeneously distribute in the annular groove and the relative standard deviations are all below 6%. This method is very convenient and suitable for online in situ analysis of heavy metals.展开更多
The preparation of fine copper powders by chemical reduction method was investigated. The reaction of [Cu(NH3)4]2^+ complex with hydrazine hydrate gives spherical monodispersed fine copper powders. The spherical co...The preparation of fine copper powders by chemical reduction method was investigated. The reaction of [Cu(NH3)4]2^+ complex with hydrazine hydrate gives spherical monodispersed fine copper powders. The spherical copper powder with a uniform size of 3.5 ± 0.5 μtm was processed to obtain flake copper powder having a uniform size of 8-10 μm, excellent dispersibility and uniform shape. The spherical copper powder of 2.5 ±0.3 μm in size, flake copper, glass frit and vehicle were mixed to prepare copper paste, which was fired in 910-920℃ to obtain BME-MLCC (base metal multilayer ceramic capacitor) with a dense surface of end termination, high adhesion and qualified electrical behavior. Polarized light photo and SEM were employed to observe the copper end termination of BME-MLCC. The rough interface from the interracial reaction between glass and chip gives high adhesion.展开更多
The effect of graphite surface modification on the thermal conductivity(TC) and bending strength of graphite flakes/Al composites(Gf/Al) prepared by gas pressure infiltration were investigated. Al3 Ni and Al4C3 phase ...The effect of graphite surface modification on the thermal conductivity(TC) and bending strength of graphite flakes/Al composites(Gf/Al) prepared by gas pressure infiltration were investigated. Al3 Ni and Al4C3 phase may form at the interface in Ni-coated Gf/Al and uncoated Gf/Al composites, respectively, while the Al-Cu compound cannot be observed in Cu-coated Gf/Al composites. The Cu and Ni coatings enhance TC and the bending strength of the composites in the meantime. TC of Cu-coated Gf/Al composites reach 515 Wm^-1·K^-1 with 75 vol% Gf, which are higher than that of Ni-coated Gf/Al. Meanwhile, due to Al3 Ni at the interface, the bending strength of Ni-coated Gf/Al composites are far more than those of the uncoated and Cu-coated Gf/Al with the same content of Gf. The results indicate that metal-coated Gf can effectively improve the interfacial bonding between Gf and Al.展开更多
Aluminum storage systems with graphite cathode have been greatly promoting the development of state-of-the-art rechargeable aluminum batteries over the last five years;this is due to the ultra-stable cycling,high capa...Aluminum storage systems with graphite cathode have been greatly promoting the development of state-of-the-art rechargeable aluminum batteries over the last five years;this is due to the ultra-stable cycling,high capacity,and good safety of the systems.This study discussed the change of electrochemical behaviors caused by the structural difference between flake graphite and expandable graphite,the effects of temperature on the electrochemical performance of graphite in low-cost AlCl_(3)-NaCl inorganic molten salt,and the reaction mechanisms of aluminum complex ions in both graphite materials by scanning electron microscopy,X-ray diffraction,Raman spectroscopy,cyclic voltammetry,and galvanostatic charge-discharge measurements.It was found that flake graphite stacked with noticeably small and thin graphene nanosheets exhibited high capacity and fairly good rate capability.The battery could achieve a high capacity of^219 mA·h·g^(-1) over 1200 cycles at a high current density of 5 A·g^(-1),with Coulombic efficiency of 94.1%.Moreover,the reaction mechanisms are clarified:For the flake graphite with small and thin graphene nanosheets and high mesopore structures,the reaction mechanism consisted of not only the intercalation of AlCl4^-anions between graphene layers but also the adsorption of Al Cl4^-anions within mesopores;however,for the well-stacked and highly parallel layered large-size expandable graphite,the reaction mechanism mainly involved the intercalation of AlCl4^-anions.展开更多
In order to investigate the food nutrition and safety of potato,the objective of the present study is to quantify glycoalkaloids(-chaconine and-solanine)and phenolic compounds in three potato cultivars,namely,Russet B...In order to investigate the food nutrition and safety of potato,the objective of the present study is to quantify glycoalkaloids(-chaconine and-solanine)and phenolic compounds in three potato cultivars,namely,Russet Burbank,Atlantic,and Shepody,grown in Hebei,China,and these two classes of biologically active compounds in commercial dehydrated potato flakes were also investigated.The total glycoalkaloid levels in whole potatoes ranged from 4.72 mg/kg for Shepody potatoes to 34.45 mg/kg for Russet Burbank potatoes.The ratio of-chaconine to-solanine in whole potatoes ranged from 0.41 for Russet Burbank potatoes to 3.61 for Atlantic potatoes.The removal rate of total glycoalkaloids in Russet Burbank potatoes during dehydrated potato flake processing is 90.0%.Chlorogenic acid is the dominant phenolic compound in Russet Burbank potatoes.By contrast,Atlantic and Shepody potatoes contain considerable caffeic acid.The loss rate of phenolic compounds in Russet Burbank during dehydrated potato flake processing is 50.47%.展开更多
Low carbon Al2O3 - C refractories specimens were prepared with tabular alumina (3. 0 - 1.0, 1.0 - 0. 5, 0.6-0.2, ≤0.3, ≤0. 045 and ≤0. 02 mm), active alumina micropowder (≤2 μm ) and silicon ( 〈≤0. 045 mm ...Low carbon Al2O3 - C refractories specimens were prepared with tabular alumina (3. 0 - 1.0, 1.0 - 0. 5, 0.6-0.2, ≤0.3, ≤0. 045 and ≤0. 02 mm), active alumina micropowder (≤2 μm ) and silicon ( 〈≤0. 045 mm ) as main raw materials. Nano carbon black (N220) and natural graphite flake ( 〈≤0. 074 mm ) were adopted as the carbon sources. The specimens were treated at 800, 1 000, 1 200 and 1 400 ℃ under coke embedded atmosphere. The effects of additions of nano carbon black and graphite flake on mechanical properties and thermal shock resistance of the specimens were stud- ied. Their mechanical properties were measured by three- point bending test and thermal shock resistance was de- termined by water quenching method. The phase compo- sition of the specimens was analyzed with X-ray diffrac- tion and microstruetures were observed through FESEM. The results reveal that: (1) the strengths of A1203 - C refractories with these two carbon sources show no big differences when coked at lower than 1 000 ℃ ; when coked at over 1 200 ℃ , the strengths of the specimens with graphite added are much higher than those of the specimens containing carbon black due to much more sil- icon carbide whiskers formed; (2) since the nano carbon black has small particle size, they can be filled into in- terstice of Al2O3 particles to form the nano carbon net- work structure, absorbing and relieving the thermal stressgenerated from expansion and contraction and reducing the thermal expansion coefficient of the specimens, thus their thermal shock resistance is better than that of the specimens containing graphite ; ( 3 ) low carbon Al2 O3 - C refractories with good mechanical properties and excellent thermal shock resistance can be prepared with combi- nation of nano carbon black and graphite flake.展开更多
This paper reports the results of the study of micronucleus frequency in peripheral lymphocytes in workers exposed to soft wood dust (poplar and linden wood) in match factories. 298 workers exposed to soft wood dust i...This paper reports the results of the study of micronucleus frequency in peripheral lymphocytes in workers exposed to soft wood dust (poplar and linden wood) in match factories. 298 workers exposed to soft wood dust in three match factories were defined as exposure group and 45 waiters in a restaurant as control group. The frequency of micronucleus in peripheral lymphocytes was examined and the control's 95% confidential upper limit≥ 4‰ was defined as the standard to determine the positivity. The positive rate in the exposure group was 36.2% while that in the control group was only 4.4%; the difference is significant (P <0.01). As the coefficient of correlation between length of work and positive rate was 0.86 (P <0.01 ), a dose/time-response is in existence. Meanwhile, the analysis of relation between quantity of smoking and positive rate eliminated the effect of smoking on variation of positive rates. In this paper, we also discussed the relation between positive rates and wood dust concentrations in different worksites and we think that the volatile and unsteady substances in soft wood dust are micronucleus-inducing matters展开更多
The polyaniline (PANI) films doped with complex acid (sulfuric acid and sulfosalicylic acid) were prepared using the potentiostatic method on bare nickel flake (NF) and flexible polyethylene terephthalate (PET...The polyaniline (PANI) films doped with complex acid (sulfuric acid and sulfosalicylic acid) were prepared using the potentiostatic method on bare nickel flake (NF) and flexible polyethylene terephthalate (PET)/indium tin oxide (ITO) substrates. The contents of the PANI films,surface elements, electrochromic property and electrical conductivity were characterized by energy dispersive X-ray spectrometer (EDS), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The experimental results show that differences exist among cycle stability, redox reversibility and response time of polyaniline films on these two kinds of substrates, but the electrochromic phenomenon of the PANI films is in substantial agreement. The equilibrium transmittance spectra in the visible region (400-800 nm) for the PANI film on flexible PET/ITO substrate was obtained at different applied potential from -0.4 to 1.5 V. The results show that the transmittance of the PANI film by applying voltage is adjustable in a row and has excellent electrochromic performance.展开更多
文摘Sixty-four Holstein steers (247 ± 4 kg) were used in a 70-d experiment to evaluate the effects of partial replacement of steam flake corn (SFC) with extruded corn meal (EC) on growth performance and dietary net energy. Treatments consisted of a steam flaked corn-based finishing diet containing 0%, 10%, 20%, or 30% EC, where EC replaced 0%, 15%, 30%, or 45% of SFC (DM basis). Replacement of SFC with increasing levels of EC did not affect (P > 0.10) ADG, DMI, and gain efficiency. When EC replaced 15% to 30% of SFC, observed dietary NE was 99% of expected. Whereas, when EC replaced 45% of SFC, observed dietary NE was 94% of expected. Four Holstein steers (210 ± 7 kg) with cannulas in the rumen and proximal duodenum were used in a 4 × 4 Latin square experiment to evaluate treatment effects on characteristics of digestion. Partial replacement of SFC with EC did not affect (P > 0.10) flow of undegraded feed N and microbial N and to the small intestine, and ruminal microbial N efficiency (g microbial N/kg OM fermented). Likewise, there were no treatment effects (P > 0.10) on ruminal digestion of OM, NDF, starch and feed N. As expected, total tract digestion of starch for all treatments exceeded 99%. However, partial replacement of SFC with EC decreased total tract digestion of DM and OM (linear effect, P = 0.02), and dietary DE (linear effect, P = 0.03). These effects were more pronounced where EC replaced 45% of SFC. Partial replacement of SFC with EC did not affect (P > 0.10) ruminal pH, total VFA concentration, molar proportions of acetate, propionate, and butyrate, and estimated methane production. It is concluded that partial replacement of SFC with EC does not have a beneficial effect on ruminal microbial efficiency and digestive function. The feeding value of extruded corn for feedlot cattle is comparable to that of steam flaked corn provided the inclusion rate does not exceed 20% of diet dry matter.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.92065110,11674031,11974048,12074334)the National Basic Research Program of China(Grant Nos.2014CB920903 and 2013CB921701)。
文摘We study systematically the negative magnetoresistance(MR)effect in WTe_(2±α)flakes with different thicknesses and doping concentrations.The negative MR is sensitive to the relative orientation between electrical-/magnetic-field and crystallographic orientation of WTe_(2±α).The analysis proves that the negative MR originates from chiral anomaly and is anisotropic.Maximum entropy mobility spectrum is used to analyze the electron and hole concentrations in the flake samples.It is found that the negative MR observed in WTe_(2±α)flakes with low doping concentration is small,and the high doping concentration is large.The doping-induced disorder obviously inhibits the positive MR,so the negative MR can be more easily observed.In a word,we introduce disorder to suppress positive MR by doping,and successfully obtain the negative MR in WTe_(2±α)flakes with different thicknesses and doping concentrations,which indicates that the chiral anomaly effect in WTe_(2)is robust.
文摘Graphene flakes(GF)have been prepared and assessed as a material for improving flow in oil pipelines under the effect of an electric field.In particular,different amounts of GFs have been considered in order to determine the optimal flow conditions.The GFs were prepared from graphite foam,derived from the dehydration of sugar with a particle size of 500-600μm,which was dispersed in ethanol and exfoliated in a ball mill under a shear force.After 15 h of exfoliation,sonication,and subsequent high-speed centrifugation at 3000 rpm,irregular-shaped GFs of 50-140 nm were produced and characterized using scanning electron microscopy,X-ray diffractometry,atomic force microscopy,and Raman spectroscopy.The prepared graphene sheets have been found to display excellent morphology and good graphitic structure.Experiments on flow improvement were conducted using the central composite rotatable design method for three parameters:stimulation time(15,30,45,and 60 s),applied voltage(150,170,200,and 220 V),and concentration of the GFs(0,100,200,and 400 mg/L).The optimal conditions for improved crude oil flow were then determined using the STATISTICA and WinQSB software packages.The results have confirmed the effectiveness of the use of the prepared GFs as a flow improver for crude oil,where the flow improvement is essentially a result of a reduction in viscosity and suppression of friction in the crude oil system.
文摘湖泊对气候变化非常敏感,是气候变化的指示器。青藏高原湖泊众多,但由于观测数据的缺乏,目前对全球变暖背景下高原湖泊热力状况的研究依然不足且多为短期研究。利用中国科学院青藏高原研究所(ITPCAS)开发的中国区域高时空分辨率地面气象要素驱动数据集、MODIS地表温度数据、青海湖浮标观测数据,分析了Freshwater Lake Model(简称Flake模式)在青海湖的适用性,揭示了青海湖热力状况对气候变化的响应。结果表明,Flake模式能够很好的模拟出青海湖的热力状况,但对夏季与秋季的湖表面水温(特别是夜间)模拟偏高,部分是驱动数据误差造成的,修正驱动数据后模拟效果得到改善。对1989 2012年Flake模拟的湖表面温度与ITPCAS数据不同驱动要素之间的年际变化趋势与相关性进行分析,发现青海湖表面温度呈现上升趋势,与气温、向下长波辐射有较好的正相关性,而与风速负相关。内部热力状况的模拟结果显示,青海湖混合层温度基本全年呈上升趋势,其中5、6月及12月增温最显著;湖泊底层温度在5月以及12月的两次季节性翻转时期呈上升趋势,在6 10月湖水分层期呈下降趋势,分层期湖泊上层温度升高会加强湖水层结稳定性,使湖水混合减弱,导致底层温度下降。
基金This work was supported by Jimma Institute of Technology through Mega Project.
文摘The mineralogy and petrography of natural graphite in Saba Boru of Ethiopia indicate that there exists flake graphite with a slightly oval structured fine size according to our study on thin and polished sections.Herein,for estimating the carbon content in graphite,the ASTM-C561,the test method for ash in a graphite sample,was used.For characterizing graphite,x-ray diffraction,x-ray fluorescence,inductively coupled plasma mass spectroscopy,and scanning electron microscopy were also used.Chemical analysis of ore samples determined that the average compositions are 63.35%SiO2,15.45%Al2O3,2.36%Fe2O3,2.07%K2O,less than1%others,and loss-on-ignition(LOI)in the range of^4.74%–37.42%.The total carbon content of graphitic ore ranged from 4.11%to 33.14%.Importantly,when graphite is concentrated through floatation,its average purity and recovery are 92.97%and 90.82%,respectively.Furthermore,once the graphite concentrates are treated with hydrofluoric acid,the average value attains a high grade of 96.48%C.Moreover,the average ash content is 81.93%(pre-flotation)and 3.1%(post-flotation),respectively.Finally,after beneficiation,a silica is identified as a major gangue(85.88%),usable as a raw material for other purposes such as cement.Hence,these graphite-bearing rocks seem to be worth exploring for commercialization opportunities.
文摘The FTP200 flake tantalum powder was introduced.The microstructures of the powder with leaf-like primary particles having an average flakiness of 2 to 20 and porous agglomerated particles were observed.The chemical composition,physical properties,and electrical properties of the FTP200 powder were compared with those of the FTW300 nodular powder.The FTP200 powder is more sinter-resistant,and the surface area of the flake tantalum powder under sintering at high temperature has less loss than that of the nodular tantalum powder.The specific capacitance of the flake tantalum powder is higher than that of the nodular tantalum powder with the same surface area when anodized at high voltage.Thus,the flake tantalum powder is suitable for manufacturing tantalum solid electrolytic capacitors in the range of median and high(20-63 V) voltages.
基金Project supported by the National Natural Science Foundation of China (Grant Nos 90505007 and 10774061)
文摘To explore the mechanism of carbonyl iron flake composites for microwave complex permeability, this paper investigates the feature of the flakes. The shape anisotropy was certified by the results of the magnetization hysteresis loops and the Mossbauer spectra. Furthermore, the shape anisotropy was used to explain the origin of composite microwave performance, and the calculated results agree with the experiment. It is believed that the shape anisotropy dominates microwave complex permeability, and the natural resonance plays main role in flake.
基金financially supported by the National High Technology Research and Development Program of China(No.2007AA03Z113)
文摘The properties of gray cast iron(GCI)are affected by density of matrix,size of flake graphite and primary austenite.In this paper,the Y-type specimen of GCI was prepared by lost foam casting(LFC)with and without vibration,and the influence of vibration frequency on the density of matrix,size of primary phase,and properties of the GCI was studied.The results show that the length of the flake graphite and the size of the primary austenite in GCI firstly decrease and then increase with the increase of the vibration frequency.With a vibration frequency of 35 Hz,the length of the flake graphite is the shortest,the primary austenite is the finest and the density of the matrix is the highest.In addition,the tensile strength,elongation and hardness of the GCI firstly increase and then decrease with the increase of the vibration frequency,due to the refinement of the primary phase and the increase of the matrix density.In order to analyze the refinement mechanism of the primary phase of the GCI fabricated by the LFC with vibration,the solidification temperature fields of the GCI fabricated by the LFC with the vibration frequency of 0 and 35 Hz were measured.The results show that the vibration reduces the eutectic point of the GCI and increases the supercooling degree during the eutectic transformation.As a result,the length of the flake graphite and the size of the primary austenite in GCI fabricated by LFC with the vibration frequency of 35 Hz decrease.
基金the financial support of the project from the National Natural Science Foundation of China(No.61904141)the funding of Natural Science Foundation of Shaanxi Province(No.2020JQ-295)+3 种基金the Key Research and Development Program of Shaanxi(Program No.2020GY-252)National Key Laboratory of Science and Technology on Vacuum Technology and Physics(HTKJ2019KL510007)City University of Hong Kong(Project Nos.7005070 and 9667153)Shenzhen Science and Technology Innovation Committee under the Grant JCYJ20170818103206501。
文摘Developing flexible sensors with high working performance holds intense interest for diverse applications in leveraging the Internet-of-things(IoT)infrastructures.For flexible piezoresistive sensors,traditionally most efforts are focused on tailoring the sensing materials to enhance the contact resistance variation for improving the sensitivity and working range,and it,however,remains challenging to simultaneously achieve flexible sensor with a linear working range over a high-pressure region(>100 kPa)and keep a reliable sensitivity.Herein,we devised a laserengraved silver-coated fabric as"soft"sensor electrode material to markedly advance the flexible sensor's linear working range to a level of 800 kPa with a high sensitivity of 6.4 kPa^-1 yet a fast response time of only 4 ms as well as long-time durability,which was rarely reported before.The integrated sensor successfully routed the wireless signal of pulse rate to the portable smartphone,further demonstrating its potential as a reliable electronic.Along with the rationally building the electrode instead of merely focusing on sensing materials capable of significantly improving the sensor's performance,we expect that this design concept and sensor system could potentially pave the way for developing more advanced wearable electronics in the future.
基金supported by the National High Technology Research and Development Program of China (2012AA03A611)The Program for Changjiang Scholars and Innovative Research Team in University (IRT-15R46)Yangtze River scholar research project of Shihezi University (CJXZ201601)
文摘The mixed matrix membranes(MMMs) were developed by incorporating graphite oxide(GO) flakes functionalized with iron oxide(Fe_3O_4) into Pebax matrix. The Pebax/Fe_3O_4–GO MMMs were used to separate CO_2/CH_4 and CO_2/N_2 gas mixture. The results showed that the MMMs with magnetic alignment presented the better gas separation performance than that of random arrangement of Pebax/Fe_3O_4–GO mixed matrix membranes. The reason was that the Fe_3O_4–GO flakes arranged magnetically in the membrane played a multiple role in improving the performance of MMMs. Firstly, under the action of the magnetic field,the magnetic alignment of Fe_3O_4–GO flakes in Pebax matrix constructed the shorter transfer path for gas molecule, increasing the CO_2 permeability. Secondly, the hydroxyl groups in GO flakes and the presence of Fe_3O_4 have stronger binding force for water, improving the CO_2 solubility selectivity. Thirdly, the better interaction between the magnetic alignment of GO composites and polymer matrix, reduced the interface defects. Especially, the optimum gas separation performance was obtained at the Fe_3O_4–GO flakes content of 3 wt% in Pebax matrix at vertical arrangement with selectivity of 47 and 75 for CO_2/CH_4 and CO_2/N_2, respectively, and CO_2 permeability of 538 Barrer at 0.2 MPa and room temperature.
文摘一维湖泊模式是青藏高原湖泊研究的主要手段之一,但不同湖泊模式在青藏高原适用性及其差异依然不够明确。利用MODIS地表温度数据、青藏高原鄂陵湖站点观测的气象数据、湖温及湖面能量数据,驱动、评估和对比了目前应用最为广泛的两个一维湖泊模式Freshwater Lake Model(FLake)和Community Land Model version 4.5(CLM4.5)中耦合的湖泊模块在青藏高原典型湖泊的适用性。结果表明:FLake和CLM模式均能较好的对湖泊热力状况进行模拟,CLM模式对于湖表面温度和湖泊内部不同深度的温度模拟优于Flake模式,净辐射和能量的累积也是CLM模式的模拟值更接近观测值。造成Flake模式模拟偏差更大的原因与模式中计算感热、潜热的摩擦速度有关,观测的摩擦速度均值为0.22 m·s-1,CLM模式中的摩擦速度与观测值接近,为Flake模式的1.5倍,将CLM模式中的摩擦速度替换到Flake模式中后模拟结果有明显的改善。
基金supported by National Natural Science Foundation of China (No. 21735005)the Science and Technology Program of Anhui Province (No. 1501041119)+1 种基金the Science and Technology Major Special Program of Anhui Province (No. 15CZZ04125)National Key Research and Development Plan of China (No. 2016YFD0800902-2)
文摘The use of laser-induced breakdown spectroscopy(LIBS) for the analysis of heavy metals in water samples is investigated. Some factors such as splashing, surface ripples, extinction of emitted intensity, and a shorter plasma lifetime will influence the results if the water sample is directly measured. In order to avoid these disadvantages and the ‘coffee-ring effect', hydrophilic graphite flakes with annular grooves were used for the first time to enrich and concentrate heavy metals in water samples before being analyzed by LIBS. The proposed method and procedure have been evaluated to concentrate and analyze cadmium, chromium, copper, nickel, lead,and zinc in a water sample. The correlation coefficients were all above 0.99. The detection limits of 0.029, 0.087, 0.012, 0.083, 0.125, and 0.049 mgl^(-1) for Cd, Cr, Cu, Ni, Pb, and Zn,respectively, were obtained in samples prepared in a laboratory. With this structure, the heavy metals homogeneously distribute in the annular groove and the relative standard deviations are all below 6%. This method is very convenient and suitable for online in situ analysis of heavy metals.
文摘The preparation of fine copper powders by chemical reduction method was investigated. The reaction of [Cu(NH3)4]2^+ complex with hydrazine hydrate gives spherical monodispersed fine copper powders. The spherical copper powder with a uniform size of 3.5 ± 0.5 μtm was processed to obtain flake copper powder having a uniform size of 8-10 μm, excellent dispersibility and uniform shape. The spherical copper powder of 2.5 ±0.3 μm in size, flake copper, glass frit and vehicle were mixed to prepare copper paste, which was fired in 910-920℃ to obtain BME-MLCC (base metal multilayer ceramic capacitor) with a dense surface of end termination, high adhesion and qualified electrical behavior. Polarized light photo and SEM were employed to observe the copper end termination of BME-MLCC. The rough interface from the interracial reaction between glass and chip gives high adhesion.
基金Funded by the Research Fund of the State Key Laboratory of Solidification Processing(NWPU),China(No.126-QP-2015).
文摘The effect of graphite surface modification on the thermal conductivity(TC) and bending strength of graphite flakes/Al composites(Gf/Al) prepared by gas pressure infiltration were investigated. Al3 Ni and Al4C3 phase may form at the interface in Ni-coated Gf/Al and uncoated Gf/Al composites, respectively, while the Al-Cu compound cannot be observed in Cu-coated Gf/Al composites. The Cu and Ni coatings enhance TC and the bending strength of the composites in the meantime. TC of Cu-coated Gf/Al composites reach 515 Wm^-1·K^-1 with 75 vol% Gf, which are higher than that of Ni-coated Gf/Al. Meanwhile, due to Al3 Ni at the interface, the bending strength of Ni-coated Gf/Al composites are far more than those of the uncoated and Cu-coated Gf/Al with the same content of Gf. The results indicate that metal-coated Gf can effectively improve the interfacial bonding between Gf and Al.
基金the National Natural Science Foundation of China(No.51804022)the Fundamental Research Funds for the Central Universities(No.FRF-TP-18-003C2)。
文摘Aluminum storage systems with graphite cathode have been greatly promoting the development of state-of-the-art rechargeable aluminum batteries over the last five years;this is due to the ultra-stable cycling,high capacity,and good safety of the systems.This study discussed the change of electrochemical behaviors caused by the structural difference between flake graphite and expandable graphite,the effects of temperature on the electrochemical performance of graphite in low-cost AlCl_(3)-NaCl inorganic molten salt,and the reaction mechanisms of aluminum complex ions in both graphite materials by scanning electron microscopy,X-ray diffraction,Raman spectroscopy,cyclic voltammetry,and galvanostatic charge-discharge measurements.It was found that flake graphite stacked with noticeably small and thin graphene nanosheets exhibited high capacity and fairly good rate capability.The battery could achieve a high capacity of^219 mA·h·g^(-1) over 1200 cycles at a high current density of 5 A·g^(-1),with Coulombic efficiency of 94.1%.Moreover,the reaction mechanisms are clarified:For the flake graphite with small and thin graphene nanosheets and high mesopore structures,the reaction mechanism consisted of not only the intercalation of AlCl4^-anions between graphene layers but also the adsorption of Al Cl4^-anions within mesopores;however,for the well-stacked and highly parallel layered large-size expandable graphite,the reaction mechanism mainly involved the intercalation of AlCl4^-anions.
基金This work was supported by the China Agriculture Research System(CARS-10)the National Key Research and Development Plan(2016YFD0401302-02)+2 种基金the Science and Technology Major Project of Gansu Province(1602NKDJ022-1)the Natural Science Foundation of Gansu Province(1501RJZA004)the Science and Technology Planing Project of Lanzhou(2016-3-123).
文摘In order to investigate the food nutrition and safety of potato,the objective of the present study is to quantify glycoalkaloids(-chaconine and-solanine)and phenolic compounds in three potato cultivars,namely,Russet Burbank,Atlantic,and Shepody,grown in Hebei,China,and these two classes of biologically active compounds in commercial dehydrated potato flakes were also investigated.The total glycoalkaloid levels in whole potatoes ranged from 4.72 mg/kg for Shepody potatoes to 34.45 mg/kg for Russet Burbank potatoes.The ratio of-chaconine to-solanine in whole potatoes ranged from 0.41 for Russet Burbank potatoes to 3.61 for Atlantic potatoes.The removal rate of total glycoalkaloids in Russet Burbank potatoes during dehydrated potato flake processing is 90.0%.Chlorogenic acid is the dominant phenolic compound in Russet Burbank potatoes.By contrast,Atlantic and Shepody potatoes contain considerable caffeic acid.The loss rate of phenolic compounds in Russet Burbank during dehydrated potato flake processing is 50.47%.
文摘Low carbon Al2O3 - C refractories specimens were prepared with tabular alumina (3. 0 - 1.0, 1.0 - 0. 5, 0.6-0.2, ≤0.3, ≤0. 045 and ≤0. 02 mm), active alumina micropowder (≤2 μm ) and silicon ( 〈≤0. 045 mm ) as main raw materials. Nano carbon black (N220) and natural graphite flake ( 〈≤0. 074 mm ) were adopted as the carbon sources. The specimens were treated at 800, 1 000, 1 200 and 1 400 ℃ under coke embedded atmosphere. The effects of additions of nano carbon black and graphite flake on mechanical properties and thermal shock resistance of the specimens were stud- ied. Their mechanical properties were measured by three- point bending test and thermal shock resistance was de- termined by water quenching method. The phase compo- sition of the specimens was analyzed with X-ray diffrac- tion and microstruetures were observed through FESEM. The results reveal that: (1) the strengths of A1203 - C refractories with these two carbon sources show no big differences when coked at lower than 1 000 ℃ ; when coked at over 1 200 ℃ , the strengths of the specimens with graphite added are much higher than those of the specimens containing carbon black due to much more sil- icon carbide whiskers formed; (2) since the nano carbon black has small particle size, they can be filled into in- terstice of Al2O3 particles to form the nano carbon net- work structure, absorbing and relieving the thermal stressgenerated from expansion and contraction and reducing the thermal expansion coefficient of the specimens, thus their thermal shock resistance is better than that of the specimens containing graphite ; ( 3 ) low carbon Al2 O3 - C refractories with good mechanical properties and excellent thermal shock resistance can be prepared with combi- nation of nano carbon black and graphite flake.
文摘This paper reports the results of the study of micronucleus frequency in peripheral lymphocytes in workers exposed to soft wood dust (poplar and linden wood) in match factories. 298 workers exposed to soft wood dust in three match factories were defined as exposure group and 45 waiters in a restaurant as control group. The frequency of micronucleus in peripheral lymphocytes was examined and the control's 95% confidential upper limit≥ 4‰ was defined as the standard to determine the positivity. The positive rate in the exposure group was 36.2% while that in the control group was only 4.4%; the difference is significant (P <0.01). As the coefficient of correlation between length of work and positive rate was 0.86 (P <0.01 ), a dose/time-response is in existence. Meanwhile, the analysis of relation between quantity of smoking and positive rate eliminated the effect of smoking on variation of positive rates. In this paper, we also discussed the relation between positive rates and wood dust concentrations in different worksites and we think that the volatile and unsteady substances in soft wood dust are micronucleus-inducing matters
基金Funded by the National Natural Science Foundation of China (No.201760 66)
文摘The polyaniline (PANI) films doped with complex acid (sulfuric acid and sulfosalicylic acid) were prepared using the potentiostatic method on bare nickel flake (NF) and flexible polyethylene terephthalate (PET)/indium tin oxide (ITO) substrates. The contents of the PANI films,surface elements, electrochromic property and electrical conductivity were characterized by energy dispersive X-ray spectrometer (EDS), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The experimental results show that differences exist among cycle stability, redox reversibility and response time of polyaniline films on these two kinds of substrates, but the electrochromic phenomenon of the PANI films is in substantial agreement. The equilibrium transmittance spectra in the visible region (400-800 nm) for the PANI film on flexible PET/ITO substrate was obtained at different applied potential from -0.4 to 1.5 V. The results show that the transmittance of the PANI film by applying voltage is adjustable in a row and has excellent electrochromic performance.