Properties of TiAICrN coatings prepared by vacuum cathodic arc ion plating

TiAlCrN coatings were deposited by means of vacuum cathodic arc ion plating technique on TC 11 （Ti-6.5Al-3.5Mo-1.5Zr-0.3Si） titanium alloy substrates. The composition, phase structure, mechanical performance, and oxidation-resistance of the nivide coatings were investi- gated by scanning electron microscopy （SEM）, atomic force microscope （AFM）, X-ray diffraction （XRD）, auger electron spectroscopy （AES）, and X-ray photoelectron microscopy （XPS）. A new process for preparing protective coatings of the titanium alloy is successfully ac- quired. The experimental results indicate that the added element chromium in the TiAlN coatings make a contribution to form the （220） pre- ferred direction. The phases of the coatings are composed of （Ti,Al）N and （Ti,Cr）N. After 700~C and 800~C oxidation, AES analysis shows that the diffusion distribution of the TiAlCrN coatings emerges a step shape. From the outside to the inner, the concentrations of O, Al, and Cr reduce, but those of Ti and N increase. The Al-rich oxide is formed on the surface of the coatings, and the mixed structure of Ti-rich and Cr-rich oxides is formed in the internal layer. The oxidation resistance of the TiAlCrN coatings is excellent at the range of 700 to 800~C. Adhesion wear is the dominant mechanical characteristic for the titanium alloy at room temperature, and the protective coatings with high hardness can improve the mechanical properties of the titanium alloy. The wear resistance of the TC 11 alloy is considerably improved by the TiAlCrN coatings.

Lithium intercalation/de-intercalation behavior of a composite Sn/C thin film fabricated by magnetron sputtering

A tin film of 320 nm in thickness on Cu foil and its composite film with graphite of-50 nm in thickness on it were fabricated by magnetron sputtering. The surface morphology, composition, surface distributions of alloy elements, and lithium intercalation/de-intercalation behaviors of the fabricated films were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, electron probe microanalyzer （EPMA）, X-ray photoelectron spectroscopy （XPS）, inductively coupled plasma atomic emission spectrometry （ICP）, cyclic voltammetry （CV）, and galvanostatic charge/discharge （GC） measurements. It is found that the lithium intercalation/de-intercalation behavior of the Sn film can be significantly improved by its composite with graphite. With cycling, the discharge capacity of the Sn film without composite changes from 570 mAh/g of the 2nd cycle to 270 mAh/g of the 20th cycle, and its efficiency for the discharge and charge is between 90% and 95%. Nevertheless, the discharge capacity of the composite Sn/C film changes from 575 mAh/g of the 2nd cycle to 515 mAh/g of the 20th cycle, and its efficiency for the discharge and charge is between 95% and 100%. The performance improvement of tin by its composite with graphite is ascribed to the retardation of the bulk tin cracking from volume change during lithium intercalation and de-intercalation, which leads to the pulverization of tin.

TiO_2-coated SnO_2 hollow spheres as anode materials for lithium ion batteries

TiO2-coated SnO2 （TCS） hollow spheres, which are new anode materials for lithium ion （Li-ion） batteries, were prepared and characterized with X-ray diffraction （XRD）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, cyclic voltammetry （CV）, and galvanostatic charge/discharge tests. The results obtained from XRD, SEM, and TEM show that TiO2 can be uniforrrdy coated on the surface of SnO2 hollow spheres with the assistance of anionic surfactant. The cyclic voltammograms indicate that both TiO2 and SnO2 exhibit the activity for Li-ion storage. The charge/discharge tests show that the prepared TCS hollow spheres have a higher reversible coulomb efficiency and a better cycling stability than the uncoated SnO2 hollow spheres.

Effects of Ti_(0.5)Al_(0.5)N coatings on the protecting against oxidation for titanium alloys

Ti0.5Al0.5N coatings were deposited on TC11（Ti-6.5Al-3.5Mo-1.5Zr-0.3Si） and silicon substrates using a cathode arc ion-plating system.The microstructure, composition, phase structure, and oxidation-resistance of the alloys and nitride coatings were investigated by scanning electron microscopy, X-ray diffraction, transmission electron microscopy, Auger electron spectroscopy, and thermal analyzer.The results show that the oxidation resistance of the titanium alloy is relatively limited;the compound structures of Ti mixed with Al oxides are formed during the heating process.The phases of the Ti0.5Al0.5N coatings are composed of a TiN solid solution phase.The oxidation kinetics obeys the parabolic law.During the oxidation process, the selective oxidation of Al occurs, thus protecting the underlying coating and substrate.

Structure and electrochemical properties of hypo-stoichiometric hydro-gen storage alloys prepared by twin-roller rapid quenching process

The stoichiometric alloy MlB5.0 and the hypo-stoichiometric alloy MlB4.85 were prepared by twin-roller rapid quenching process, and their structure and electrochemical properties were studied. The results of XRD show that both of the alloys have a typical single-phase hexagonal CaCus-type structure. The cell volume of the hylpo-stoichiometric alloy M1B4.85 is slightly larger than that of the stoichiometric alloy M1B5.0, although its lattice constant cla is smaller. Under 2 C discharging rate, i.e. 640 mA/g, the M1B4.85 has a discharge capacity of 320 mAh/g, which is higher than that of the M1Bs.o, 312 mAh/g. Nevertheless, the capacities of the M1B4.85 and the M1Bs.o decline 24.7% and 20.2% after 400 cycles, respectively. The relationship of electrochemical performances of the alloys with their structures is discussed.

急性等容血液稀释对靶控输注依托咪酯血药浓度和肾上腺皮质功能的影响

目的观察急性等容血液稀释(ANH)对靶控输注(TCI)依托咪酯血药浓度和肾上腺皮质功能的影响。方法选择多节段脊柱手术患者60例,男35例,女25例,年龄30~60岁,BMI 20~25 kg/m^(2),ASAⅠ或Ⅱ级。采用随机数字表法将患者分为两组:ANH组和对照组,每组30例。TCI依托咪酯麻醉诱导和麻醉维持。ANH组麻醉诱导平稳后行ANH,理想Hct 28%~30%,术后1 h内回输完毕;对照组常规处理。记录依托咪酯用量。采用液相色谱-串联质谱(LC-MS/MS)法检测两组术毕即刻、术后10、20、30 min的依托咪酯血药浓度和ANH组自体血采集入储血袋即刻、在储血袋保存1 h、回输即刻的依托咪酯血药浓度。采用化学发光免疫分析(CLIA)法检测麻醉诱导前、术毕即刻、术后1、2 d的血浆皮质醇(Cor)、促肾上腺皮质激素(ACTH)和醛固酮(ALD)浓度。结果两组依托咪酯用量差异无统计学意义。与术毕即刻比较,术后10、20和30 min两组依托咪酯血药浓度明显降低(P<0.05)。与对照组比较,术后10 min ANH组依托咪酯血药浓度明显升高(P<0.05)。ANH组自体血采集入储血袋即刻、在储血袋保存1 h和回输即刻依托咪酯血药浓度分别为(547.8±119.4)、(536.7±107.8)、(522.8±91.7)ng/ml。与麻醉诱导前比较,术毕即刻两组Cor、ALD浓度明显降低(P<0.05),ACTH浓度明显升高(P<0.05),麻醉诱导前和术后1、2 d两组Cor、ALD和ACTH浓度差异无统计学意义。结论ANH用于TCI依托咪酯的骨科手术中,采集的自体血回输后仅短暂(10 min左右)增加依托咪酯的血药浓度,肾上腺皮质功能在术后24 h内恢复到麻醉诱导前水平。

Ab initio study of the effects of Ag/Mn doping on the electronic structure of LiFePO_4

Based on density functional theory (DFT) of the first-principle for the cathode materials of lithium ion battery, the electronic structures of Li(Fe1-xMex)PO4 (Me = Ag/Mn, x = 0―0.40) are calculated by plane wave pseudo-potential method using Cambridge serial total energy package (CASTEP) program. The calculated results show that the Fermi level of mixed atoms Fe1-xAgx moves into its conduction bands (CBs) due to the Ag doping. The Li(Fe1-xAgx)PO4 system displays the periodic direct semiconductor characteristic with the increase of Ag-doped concentration. However, for Fe1-xMnx mixed atoms, the Fermi level is pined at the bottom of conduction bands (CBs), which is ascribed to the interaction be-tween Mn(3d) electrons and Fe(4s) electrons. The intensity of the partial density of states (PDOS) near the bottom of CBs becomes stronger with the increase of Mn-doped concentration. The Fermi energy of the Li(Fe1-xMnx)PO4 reaches maximum at x = 0.25, which is consistent with the experimental value of x = 0.20. The whole conduction property of Mn-doped LiFePO4 is superior to that of Ag-doped LiFePO4 cathode material, but the structural stability is reverse.

Dead lithium phase investigation of Sn-Zn alloy as anode materials for lithium ion battery

In this work, based on First-principle plane wave pseudo-potential method, we have carried out an in-depth study on the possible dead lithium phase of Sn-Zn alloy as anode materials for lithium ion batteries. Through investigation, we found that the phases LixSn4Zn4(x = 2, 4, 6, 8) contributed to re-versible capacity, while the phases LixSn4Zn8-(x-4)(x = 4.74, 7.72) led to capacity loss due to high forma-tion energy, namely, they were the dead lithium phases during the charge/discharge process. And we come up with a new idea that stable lithium alloy phase with high lithiation formation energy (dead lithium phase) can also result in high loss of active lithium ion, besides the traditional expression that the formation of solid electrolyte interface film leads to high capacity loss.

First-principle study on NiSn_(0.5)Ti_(0.5) phase as electrode materials for lithium ion battery

The electronic structure and electrochemical parameters of ternary NiSn0.5Ti0.5 phase are investigated by plane-wave pseudopotential method of the first-principle.The interstitial sites are firstly filled with lithium atoms,and then the substitution for Ni sites occurs.The results show that the Fermi level of lithium-intercalated phase goes up with the increasing lithium concentration.These interactions of M-M covalent bonds (M=Ni,Sn,Ti) become weak,while Li-M bonds are found to increase.NiSn 0.5Ti0.5 phase is characterized with high theoretical capacity and low voltage of lithium-intercalation.The obvious volume effect from 77.15%to 189.94% would lead to the failure of the electrode material,and therefore the NiSn0.5Ti0.5 compound should be limited as low as possible in multi-element Sn-based alloy.

患儿术后糖原累积病发作1例:与癫痫发作的鉴别诊断

患儿,女性,1岁7个月,以反复咽部充血,双侧扁桃体肿大入院。患儿曾在当地医院诊断为"癫痫",间断服用抗癫痫药物,目前病情稳定。否认药物及食物过敏史,无相关疾病家族史。患儿为第1胎第1产,父母非近亲结婚。体检:T 37.5℃,HR 95次/min,RR 23次/min,身高64 cm,体重9 kg,发育迟缓。患儿神智清楚,呼吸平稳,腹软,无压痛及反跳痛,未触及肝脏、脾脏,肝肾区无叩击痛,无移动性浊音。