Mechanical synthesis and rapid consolidation of a nanocrystalline 5.33Fe0.37Cr0.16Al0.4Si0.07-Al2O3 composite by high-frequency induction heating

Nanopowders of 5.33Fe_0.37Cr_0.16Al_0.4Si_0.07 and Al₂O₃ were synthesized from Fe₂O₃, Cr, Si, and Al powders by high-energy ball milling. A high-density nanocrystalline 5.33Fe_0.37Cr_0.16Al_0.4Si_0.07-Al₂O₃ composite was consolidated by a high-frequency, induction-heated sintering (HFIHS) method within three minutes from mechanically synthesized powders of Al₂O₃ and 5.33Fe_0.37Cr_0.16Al_0.4Si_0.07. The advantage of this process is that it allows very quick densification to near theoretical density and prohibits grain growth in nano-structured materials. The average grain sizes of Al₂O₃ and 5.33Fe_0.37Cr_0.16Al_0.4Si_0.07 were 99 nm and 14 nm, respectively.     

Low temperature performance of graphite and LiNi0.6Co0.2Mn0.2O2 electrodes in Li-ion batteries

Low temperature (LT) behavior of graphite/LiNi_0.6Co_0.2Mn_0.2O₂ (NCM622) cells prepared with low loading or LL (thinner electrodes prepared with low loading and packing density) and high loading or HL (thicker electrodes prepared with high loading and packing density) were investigated. The cells were prepared as half coin cell, full coin cell, and full pouch cell to identify the main factors that limit LT operations of lithium ion batteries. All the cells were tested at ?32 °C, and the capacity retention at LT was compared to the capacity retention at room temperature (RT). The Li⁺ insertion kinetics was analyzed by electrochemical impedance spectroscopy. The LL electrodes showed a lesser charge transfer resistance (R _ct) than that shown by the thicker electrodes at LT. The diffusion coefficients of Li⁺ calculated via the galvanostatic intermittent titration technique (GITT) in graphite and NCM622 electrodes prepared with LL and HL at RT were in the range of 10^?8 cm²/s but decreased to the range of 10^?13 and 10^?11 cm²/s at ?32 °C, respectively. GITT results confirmed that the capacity loss at LT, with increased electrode loading, arose from the limitation of Li-ion diffusion within the electrode.     

Glycoprotein hormone alpha-subunit secretion in non-functioning pituitary adenomas

The aim of the present study was to investigate the prevalence of elevated free glycoprotein hormone alpha-subunit in different pituitary adenomas, to establish the diagnostic value of the basal and stimulated free alpha-subunit secretion in non-functioning adenomas. Serum basal levels of alpha-subunit were increased in 1 of 22 untreated, in 1 of 16 operated patients with non-functioning adenoma, in 6 of 28 untreated, in 1 of 7 operated patients with acromegaly, in 0 of 5 untreated prolactinomas and in 0 of 1 untreated gonadotrop adenoma. Overall free alpha-subunit levels were increased in 9 of 79 cases (11.4%). In 6 of 9 patients with untreated non-functioning adenoma thyrotrop hormone releasing hormone caused an abnormal--paradox--elevation of serum alpha-subunit. These data indicate that measurement of basal and stimulated alpha-subunit is of relatively poor value in the diagnosis of non-functioning pituitary adenomas. The transsphenoidal surgery did not resulted in a change of alpha-subunit secretion neither in patients with non-functioning adenoma nor with acromegaly. The present data confirm the view that non-functioning pituitary adenomas are not homogeneous since this subset of tumors includes adenomas that either do not secrete measurable amounts of free alpha-subunit or produce normal or supranormal amounts of subunits as consequence of still undefined biosynthetic abnormalities.     

Disintegration of excess activated sludge--evaluation and experience of full-scale applications.

Anaerobic digestion of sewage sludge can be improved by introducing a disintegration of excess activated sludge as a pretreatment process. The disintegration brings a deeper degradation of organic matter and less amount of output sludge for disposal, a higher production of biogas and consequently energy yield, in some cases suppression of digesters foaming and better dewaterability. The full-scale application of disintegration by a lysate-thickening centrifuge was monitored long term in three different WWTPs. The evaluation of contribution of disintegration to biogas production and digested sludge quality was assessed and operational experience is discussed. Increment of specific biogas production was evaluated in the range of 15-26%, organic matter in digested sludge significantly decreased to 48-49%. Results proved that the installation of a disintegrating centrifuge in WWTPs of different sizes and conditions would be useful and beneficial.     

Suppression of inherent ferromagnetism in Pr-doped CeO(2) nanocrystals

Ce(1-x)Pr(x)O(2-δ) (0 ≤x≤ 0.4) nanocrystals were synthesized by self-propagating method and thoroughly characterized using X-ray diffraction, Raman and X-ray photoelectron spectroscopy and magnetic measurements. Undoped CeO(2) nanocrystals exhibited intrinsic ferromagnetism at room temperature. Despite the increased concentration of oxygen vacancies in doped samples, our results showed that ferromagnetic ordering rapidly degrades with Pr doping. The suppression of ferromagnetism can be explained in terms of the different dopant valence state, the different nature of the vacancies formed in Pr-doped samples and their ability/disability to establish the ferromagnetic ordering.     

Effect of FeAl3 on properties of (W,Ti)C–FeAl3 hard materials consolidated by a pulsed current activated sintering method

Using a pulsed current activated sintering (PCAS) method, the densification of (W,Ti)C and (W,Ti)C–FeAl₃ hard materials was accomplished within 3 min. The advantage of this process is not only rapid densification to near theoretical density, but also prevention of grain growth in nano-structured materials. Highly dense (W,Ti)C and (W,Ti)C–FeAl₃ with a relative density up to 99% were obtained within 3 min by PCAS under a pressure of 80 MPa. The average grain size of the (W,Ti)C was less than 100 nm. Hardness and fracture toughness of the dense (W,Ti)C and (W,Ti)C–FeAl₃ produced by PCAS were also investigated. The fracture toughness and hardness values of (W,Ti)C, (W,Ti)C–5 vol.% FeAl₃, and (W,Ti)C–10 vol.% FeAl₃ consolidated by PCAS were 7.5 MPa m^1/2 and 2650 kg/mm², 10.5 MPa m^1/2 and 2480 kg/mm², 11 MPa m^1/2 and 2300 kg/mm², respectively.     

Rapid consolidation of nanocrystalline 3Ni–Al2O3 composite from mechanically synthesized powders by high frequency induction heated sintering

Nanopowders of Ni and Al₂O₃ were synthesized from 3NiO and 2Al powders by high energy ball milling. Nanocrystalline Al₂O₃ reinforced composite was consolidated by high frequency induction heated sintering method within 2 min from mechanically synthesized powders of Al₂O₃ and 3Ni. The relative density of the composite was 96%. The average hardness and fracture toughness values obtained were 645 kg/mm² and 6.3 MPa m^1/2, respectively.     

Performance improvements in temperature reconstructions of 2-D tunable diode laser absorption spectroscopy (TDLAS)

Performance improvement was attained in data reconstructions of 2-dimensional tunable diode laser absorption spectroscopy(TDLAS). Multiplicative Algebraic Reconstruction Technique(MART) algorithm was adopted for data reconstruction. The data obtained in an experiment for the measurement of temperature and concentration fields of gas flows were used. The measurement theory is based upon the Beer-Lambert law, and the measurement system consists of a tunable laser, collimators, detectors, and an analyzer. Methane was used as a fuel for combustion with air in the Bunsen-type burner. The data used for the reconstruction are from the optical signals of 8-laser beams passed on a cross-section of the methane flame. The performances of MART algorithm in data reconstruction were validated and compared with those obtained by Algebraic Reconstruction Technique(ART) algorithm.     

A practical 2D/3D SLAM using directional patterns of an indoor structure

This paper presents a practical two-dimensional (2D)/three-dimensional (3D) simultaneous localization and mapping (SLAM) algorithm using directional features for ordinary indoor environments; this algorithm is adaptable to various conditions, computationally inexpensive, and accurate enough to use for practical applications. The proposed algorithm uses odometry acquired from other sensors or other algorithms as the initial estimate and the directional features of indoor structures as landmarks. The directional features can only correct the rotation error of the odometry. However, we show that the greater part of the translation error of the odometry can also be corrected when the directional features are detected at almost positions accurately. In that case, there is no need to use other kinds of features to correct translation error. The directions of indoor structures have two advantages as landmarks. First, the extraction of them is not affected by obstacles. Second, the number of them is small regardless of the size of the building. Because of these advantages, the proposed SLAM algorithm shows robustness for parameters and lightweight properties. From extensive experiments with 2D/3D datasets taken from different buildings, we show the practicality of the proposed algorithm. We also demonstrate that the 2D algorithm runs in real time on a low-end smartphone.     

Pressure Effect on the Coexistence of Magnetism and Superconductivity in Ho1−x Dy x Ni2B2C

We have measured the transport properties of Ho_(1–x)Dy _x Ni₂B₂C (x=0.1, 0.4) single crystals to study the effects of high pressure conditions on the superconductivity and magnetism. The pressure affects the pair-breaking interaction by changing the magnetic exchange integral J _sf. In the case of x=0.1, the superconducting transition temperature T _c is higher than the Néel temperature T _N and decreases as the pressure increases. On the other hand, for x=0.4, when have lower T _N than T _c, T _c does not change with increasing pressure. These results are due to the effect of the pressure on J _sf.