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In this research, the characteristics of nickel-titanium (NiTi) powders produced by electrode induction melting inert gas atomization (EIGA) technique for additive manufacturing (AM) technology are investigated using various powder characterization technologies. The results show that the particle size distribution (PSD) of pre-alloyed NiTi powders prepared by EIGA has the range of 10 μm to 180 μm. The mean particle size distribution (D50) of the powder is 75 μm. The oxygen increase of the powder is only 0.005% compared to the raw rod. According to the requirements of the characteristics of the metal powder material used for AM, the powders are sieved into three categories, P1 (15-63 μm), P2 (63-150 μm), and P3 (>150 μm), respectively. The flow rates of P1 and P2 are 19.3 and 17.5 s·(50 g)-1, respectively. The surface, crosssectional microstructure, phase structure, and martensitic transformation temperature of the pre-alloyed NiTi powders with different particle sizes are investigated. The results show that powders of different particle sizes are primarily spherical or nearly spherical. The grain size of powders reduces with the decreasing of particle size. Both the bar stock and the powders of P1, P2, and P3 mainly exhibit the B2 phase. Comparing the powders P1, P2, and P3, the transformation temperature reduces with the decrease of particle size. A high density (99.55%) pre-alloyed NiTi specimen is successfully produced by selective laser melting (SLM) technology using P1 powders. The results indicate that the pre-alloyed NiTi alloy powder is appropriate for AM, which also has a good reference value for researchers producing AM powders.

Distribution of the adsorbed water on BaTiO3 ferroelectric single crystal (001) surface was investigated by means of scanning probe microscopy. Under high relative humidity, above 95%, the presence of water droplets was observed on domain surfaces. The droplets were up to 20 nm high and their morphology changed when electrical field was applied between the single crystal substrates and droplets via scanning probe microscopy. With an electric field applied parallel to the (001) top surface, the droplets on c domains spread out, followed by complete recovery upon switching the electric field off. However, few droplets on a domains tend to shrink with the electrical field application. It is shown that the screening surface charges and induced charges on droplets surface play a dominant role in droplets behavior. [ABSTRACT FROM AUTHOR]

The potential distribution of ferroelectric domains on a (001) BaTiO3 single crystal surface was investigated via scanning Kelvin probe microscopy at room temperature, with and without an electric field applied parallel to the (001) surface. A reversal of the c domain charge was observed after reaching a critical electric field intensity of 6 V/mm, which was much lower than the 200 V/mm coercive field. An immediate recovery was observed upon switching off the electric field. The humidity has a significant effect on the intensity of the inversion electric field. Surface adsorbates significantly affected the ferroelectric surface potential behavior. Due to a low 4 kJ/mol desorption energy, the electric field successfully removed surface adsorbates, allowing for the surface potential to reflect the actual domain polarization state. [ABSTRACT FROM AUTHOR]

Classification of stellar spectra from voluminous spectra is a very important and challenging task. In order to better classify stellar spectra, inspired by the principle of deep convolutional neural network (CNN), we propose a supervised algorithm for stellar spectra classification based on 1D stellar spectra convolutional neural network (1D SSCNN). In 1D SSCNN, we modify the traditional 2D convolutional neural network into 1D network to adapt to the spectral classification. On the basis of using convolution algorithm, the spectral features are extracted and used for classification. We first use the stellar spectra data to train a 1D SSCNN to obtain a well-trained model, and then we apply the well-trained model to classify the unknown spectra. To evaluate the performance of the proposed algorithms, we apply 1D SSCNN to classify three spectral types: F-type spectra, G-type spectra, and K-type spectra and 10 subclasses of K-type spectra: A0-type, A5-type, F0-type, F5-type, G0-type, G5-type, K0-type, K5-type, M0-type, and M5-type spectra from Sloan Digital Sky Survey (SDSS). Our 1D SSCNN algorithm obtain higher classification accuracy compared with support vector machine (SVM), random forest (RF), and artificial neural network (ANN). [ABSTRACT FROM AUTHOR]

OBJECTIVE: Cervical cancer has become the fourth most common cancer in developing countries. This study aimed to investigate anti-tumor effects of Metformin combining with carboplatin in cervical cell line, HeLa cell. MATERIALS AND METHODS: Human cervical cancer cell line, HeLa cell, was treated with Metformin (5 mmol/l or 10 mmol/l) or/and carboplatin (25 mg/l or 50 mg/l) at different final concentrations, and divided into 8 groups. 3-(4,5-dimethylthiazol-2-yl)- 2,5-diphenyltetrazolium bromide (MTT) assay was used to evaluate cell viability. Acridine orange/ethidium bromide (AO/EB) staining was used to examine nuclear fragments and cell apoptosis. Annexin V/propidium iodide (PI) staining was employed to detect apoptosis of HeLa cells. Mitochondrial membrane potential of the HeLa cells was evaluated by staining with 5,5,6,6-tetrachloro-1,1,3,3-tetraethylbenzimidazolylcarbocyanine iodide (JC-1) reagent. RESULTS: MTT results showed that Metformin combining carboplatin significantly reduced HeLa cell viability compared to that of no-drug treatment group (p<0.05). Metformin combining carboplatin significantly increased the amounts of nuclear fragments compared to that of no-drug treatment group (p<0.05). The flow cytometry assay results indicated that Metformin combining carboplatin significantly enhanced the apoptotic rates compared to that of no-drug treatment group (p<0.05). The JC-1 staining findings illustrated that Metformin combining carboplatin significantly decreased the mitochondrial membrane potential compared to that of no-drug treatment group (p<0.05). CONCLUSIONS: Metformin enhanced the inhibitive effects of carboplatin on HeLa cell proliferation. Metformin increased the sensitivity of HeLa cell to the treatment of Carboplatin by activating mitochondrial-associated apoptosis signaling pathway. [ABSTRACT FROM AUTHOR]

The potential distribution of BaTiO3 single crystal ferroelectric domains was investigated by scanning Kelvin probe microscopy at room temperature with and without an electric field applied parallel to the (001) top surface. Immediate c domain surface potential inversion was observed after reaching the 6 V/mm critical electric field intensity followed by complete recovery upon switching the electric field off. Piezoresponse force microscopy was used to characterize domain structure evolution during the electric field application, which caused c domain motion. Newly formed domain patterns were stable for a month after switching the electric field off. Screening surface charges and their mobility play a dominant role in this experiment. [ABSTRACT FROM AUTHOR]