Showing papers by "Chonbuk National University published in 2004"
TL;DR: It is shown that reoxygenation after prolonged hypoxia reduces the reactive oxygen species (ROS) threshold for the mitochondrial permeability transition (MPT) in cardiomyocytes and that cell survival is steeply negatively correlated with the fraction of depolarized mitochondria.
Abstract: Environmental stresses converge on the mitochondria that can trigger or inhibit cell death. Excitable, postmitotic cells, in response to sublethal noxious stress, engage mechanisms that afford protection from subsequent insults. We show that reoxygenation after prolonged hypoxia reduces the reactive oxygen species (ROS) threshold for the mitochondrial permeability transition (MPT) in cardiomyocytes and that cell survival is steeply negatively correlated with the fraction of depolarized mitochondria. Cell protection that exhibits a memory (preconditioning) results from triggered mitochondrial swelling that causes enhanced substrate oxidation and ROS production, leading to redox activation of PKC, which inhibits glycogen synthase kinase-3beta (GSK-3beta). Alternatively, receptor tyrosine kinase or certain G protein-coupled receptor activation elicits cell protection (without mitochondrial swelling or durable memory) by inhibiting GSK-3beta, via protein kinase B/Akt and mTOR/p70(s6k) pathways, PKC pathways, or protein kinase A pathways. The convergence of these pathways via inhibition of GSK-3beta on the end effector, the permeability transition pore complex, to limit MPT induction is the general mechanism of cardiomyocyte protection.
963 citations
TL;DR: Experiments revealed that the proposed hybrid GA is superior to both a simple GA and sequential search algorithms, and showed better convergence properties compared to the classical GAs.
Abstract: This paper proposes a novel hybrid genetic algorithm for feature selection. Local search operations are devised and embedded in hybrid GAs to fine-tune the search. The operations are parameterized in terms of their fine-tuning power, and their effectiveness and timing requirements are analyzed and compared. The hybridization technique produces two desirable effects: a significant improvement in the final performance and the acquisition of subset-size control. The hybrid GAs showed better convergence properties compared to the classical GAs. A method of performing rigorous timing analysis was developed, in order to compare the timing requirement of the conventional and the proposed algorithms. Experiments performed with various standard data sets revealed that the proposed hybrid GA is superior to both a simple GA and sequential search algorithms.
844 citations
TL;DR: In this article, an electrospun nonwoven fabric of a cationic polysaccharide, chitosan, was successfully prepared and the effect of the electrospinning solvent and the chitosa concentration on the morphology of the resulting non-woven fabrics was investigated.
Abstract: Summary: An electrospun nonwoven fabric of a cationic polysaccharide, chitosan, was successfully prepared. The present study focuses on the effect of the electrospinning solvent and the chitosan concentration on the morphology of the resulting nonwoven fabrics. The solvents tested were dilute hydrochloric acid, acetic acid, neat formic acid and trifluoroacetic acid. As the chitosan concentration was increased, the morphology of the deposition on the collector changed from spherical beads to interconnected fibrous networks. The addition of dichloromethane to the chitosan-TFA solution improved the homogeneity of the electrospun chitosan fiber. Under optimized conditions, homogenous (not interconnected) chitosan fibers with a mean diameter of 330 nm were prepared.
Effects of the coexisting dichloromethane (MC) in the prespun chitosan-TFA solution on the morphology of the electrospun chitosan fibers. The volume ratio of TFA:MC was 70:30 (×5 000).
620 citations
TL;DR: The studies illustrated the potential use of SMEDDS for the delivery of hydrophobic compounds, such as simvastatin by the oral route, and its potential use for in vitro dissolution and bioavailability assessment.
518 citations
TL;DR: In this article, a nanofibrous matrix was fabricated from a biodegradable poly(p-dioxanone-co-L-lactide)-block-poly(ethylene glycol) copolymer, and the morphology of cell-matrix interaction with the electrospun matrix was examined.
491 citations
TL;DR: In this article, the effects of molecular weights of atactic polyvinyl alcohols (a-PVAs) on the characteristics of electrospun a-PVA nanofabrics were investigated.
Abstract: Atactic poly(vinyl alcohols) (a-PVAs) having number-average degrees of polymerization [(Pn)s] of 1700 and 4000 were prepared by the solution polymerization of vinyl acetate, which was followed by the saponification of poly(vinyl acetate) to investigate the effects of molecular weights of a-PVA on the characteristics of electrospun a-PVA nanofabrics. A-PVA nanofabrics were prepared by electrospinning with controlling the process parameters including the electrical field, conductivity, tip-to-collector distance, and solution concentration. Through a series of characterization experiments, we identified that the molecular weight of a-PVA had a marked influence on the structure and properties of nanofabrics produced. That is, the higher the molecular weight of PVA, the superior the physical properties of PVA nanofabric. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1638–1646, 2004
374 citations
TL;DR: RF ablation appears to be a safe and promising procedure for the treatment of inoperable NSCLC and metastases.
Abstract: PURPOSE: To assess technical feasibility, efficacy, and complications of percutaneous computed tomography (CT)-guided transthoracic radiofrequency (RF) ablation for treating inoperable non–small cell lung cancer (NSCLC) and lung metastases. MATERIALS AND METHODS: Twenty-six patients with 27 NSCLCs and four patients with five lung metastases underwent RF ablation with cooled-tip electrodes with CT guidance. Patients were not candidates for surgery because of either advanced-stage disease (n = 20) and/or comorbid processes (n = 4) or refusal to undergo surgery (n = 6). The procedure was performed with the intent to cure in 10 (33%) patients with stage I tumors and as palliative therapy in 20 (67%) patients. Contrast material–enhanced CT was performed immediately, 1 month, and then every 3 months after RF ablation to evaluate the response to therapy. Time to death for each patient was calculated with Kaplan-Meier analysis, and the effect of tumor size and the extent of coagulation necrosis on time to death w...
323 citations
TL;DR: Ulasonic irrigation ex vivo is more effective than syringe irrigation in removing artificially created dentine debris placed in simulated uninstrumented extensions and irregularities in straight, wide root canals.
Abstract: Lee S-J, Wu M-K, Wesselink PR. The effectiveness of syringe irrigation and ultrasonics to remove debris from simulated irregularities within prepared root canal walls. International Endodontic Journal, 37, 672–678, 2004.
264 citations
TL;DR: CPsuperH as discussed by the authors is a Fortran program that calculates the mass spectrum and decay widths of the neutral and charged Higgs bosons in the Minimal Supersymmetric Standard Model with explicit CP violation.
264 citations
TL;DR: By replacing the N-terminal portion of Ang1 with the short coiled-coil domain of cartilage oligomeric matrix protein (COMP), this variant is a soluble, stable, and potent Ang1 variant, COMP-Ang1, which is more potent than native Ang1 in phosphorylating the tyrosine kinase with Ig and epidermal growth factor homology domain 2 (Tie2) receptor and Akt in primary cultured endothelial cells.
Abstract: Angiopoietin-1 (Ang1) has potential therapeutic applications in inducing angiogenesis, enhancing endothelial cell survival, and preventing vascular leakage. However, production of Ang1 is hindered by aggregation and insolubility resulting from disulfide-linked higher-order structures. Here, by replacing the N-terminal portion of Ang1 with the short coiled-coil domain of cartilage oligomeric matrix protein (COMP), we have generated a soluble, stable, and potent Ang1 variant, COMP-Ang1. This variant is more potent than native Ang1 in phosphorylating the tyrosine kinase with Ig and epidermal growth factor homology domain 2 (Tie2) receptor and Akt in primary cultured endothelial cells, enhancing angiogenesis in vitro and increasing adult angiogenesis in vivo. Thus, COMP-Ang1 is an effective alternative to native Ang1 for therapeutic angiogenesis in vivo.
261 citations
TL;DR: In this article, the optical and electrical properties of single-crystalline silicon carbide nanowires (SiC NWs) were reported, which were fabricated by a chemical vapor deposition process, and had diameters of <100nm and lengths of several μm.
Abstract: We report on the optical and electrical transport properties of single-crystalline silicon carbide nanowires (SiC NWs). The NWs were fabricated by a chemical vapor deposition process, and had diameters of <100nm and lengths of several μm. X-ray diffraction and transmission electron microscopy analysis showed the single-crystalline nature of NWs with a growth direction of ⟨111⟩. Photoluminescence characterization showed blue emission at room temperature. The electrical measurements from a field effect transistor structure on individual NWs showed n-type semiconductor characteristics. The resistivity and estimated electron mobility on the NWs are 2.2×10−2Ωcm for 0V of gate voltage and 15cm2∕(Vs), respectively. Our low-resistivity SiC NWs could be applied to a high-temperature operation sensor and actuator due to its own excellent electrical and optical properties.
TL;DR: A novel low-power multiplexer-based 1-bit full adder that uses 12 transistors (MBA-12T) that has no direct connections to the power-supply nodes, leading to a noticeable reduction in short-current power consumption.
Abstract: The 1-bit full adder circuit is a very important component in the design of application specific integrated circuits. This paper presents a novel low-power multiplexer-based 1-bit full adder that uses 12 transistors (MBA-12T). In addition to reduced transition activity and charge recycling capability, this circuit has no direct connections to the power-supply nodes, leading to a noticeable reduction in short-current power consumption. Intensive HSPICE simulation shows that the new adder has more than 26% in power savings over conventional 28-transistor CMOS adder and it consumes 23% less power than 10-transistor adders (SERF and 10T ) and is 64% faster.
TL;DR: Univariate and multivariate analyses showed that a high level of Bmi-1 expression was significantly correlated with axillary lymph node metastases and positive estrogen receptor status, suggesting that Bmi -1 might be involved in the tumor progression and metastasis of invasive ductal breast cancer.
TL;DR: Results indicate that not only PI-3 kinase activation but also inhibition of PTEN by ROS is needed to increase cellular level of phosphatidylinositol 3,4,5-trisphosphate for recruiting downstream signaling molecules such as PDK-1 and Akt in insulin-mediated signaling.
Abstract: Phosphoinositide-3 kinase (PI-3 kinase) and its downstream signaling molecules PDK-1 and Akt were analyzed in SK-N-SH and SK-N-BE(2) human neuroblastoma cell lines. When cells were stimulated with insulin, PI-3 kinase was activated in both cell lines, whereas the translocation of PDK-1 to the membrane fraction and phosphorylated Akt were observed only in SK-N-SH cells. Analyses of the insulin-mediated reactive oxygen species (ROS) generation and Phosphatase and Tensin homolog (PTEN) oxidation indicate that PTEN oxidation occurred in SK-N-SH cells, which can produce ROS, but not in SK-N-BE(2) cells, which cannot increase ROS in response to insulin stimulation. When SK-N-SH cells were pretreated with the NADPH oxidase inhibitor diphenyleneiodonium chloride before insulin stimulation, insulin-mediated translocation of PDK-1 to the membrane fraction and phosphorylation of Akt were remarkably reduced, whereas PI-3 kinase activity was not changed significantly. These results indicate that not only PI-3 kinase activation but also inhibition of PTEN by ROS is needed to increase cellular level of phosphatidylinositol 3,4,5-trisphosphate for recruiting downstream signaling molecules such as PDK-1 and Akt in insulin-mediated signaling. Moreover, the ROS generated by insulin stimulation mainly contributes to the inactivation of PTEN and not to the activation of PI-3 kinase in the PI-3 kinase/Akt pathway.
TL;DR: A new approach to the automatic execution of business processes using event-condition-action (ECA) rules that can be automatically triggered by an active database is proposed.
Abstract: Changes in recent business environments have created the necessity for a more efficient and effective business process management. The workflow management system is software that assists in defining business processes as well as automatically controlling the execution of the processes. We propose a new approach to the automatic execution of business processes using event-condition-action (ECA) rules that can be automatically triggered by an active database. First of all, we propose the concept of blocks that can classify process flows into several patterns. A block is a minimal unit that can specify the behaviors represented in a process model. An algorithm is developed to detect blocks from a process definition network and transform it into a hierarchical tree model. The behaviors in each block type are modeled using ACTA formalism. This provides a theoretical basis from which ECA rules are identified. The proposed ECA rule-based approach shows that it is possible to execute the workflow using the active capability of database without users' intervention. The operation of the proposed methods is illustrated through an example process.
TL;DR: The fungicidal activities of Cassia tora extracts and their active principles were determined against Botrytis cineria, Erysiphe graminis, Phytophthora infestans, Puccinia recondita, Pyricularia grisea, and Rhizoctonia solani using a whole plant method in vivo and were compared with synthetic fungicides and three commercially available anthraquinones.
Abstract: The fungicidal activities of Cassia tora extracts and their active principles were determined against Botrytis cineria, Erysiphe graminis, Phytophthora infestans, Puccinia recondita, Pyricularia grisea, and Rhizoctonia solani using a whole plant method in vivo and were compared with synthetic fungicides and three commercially available anthraquinones. The responses varied with the plant pathogen tested. At 1 g/L, the chloroform fraction of C. tora showed a strong fungicidal activity against B. cinerea, E. graminis, P. infestans, and R. solani. Emodin, physcion, and rhein were isolated from the chloroform fraction using chromatographic techniques and showed strong and moderate fungicidal activities against B. cinerea, E. graminis, P. infestans, and R. solani. Furthermore, aloe-emodin showed strong and moderate fungicidal activities against B. cinerea and R. solani, respectively, but did not inhibit the growth of E. graminis, P. infestans, P. recondita, and Py. grisea. Little or no activity was observed for anthraquinone and anthraquinone-2-carboxylic acid when tested at 1 g/L. Chlorothalonil and dichlofluanid as synthetic fungicides were active against P. infestans and B. cinerea at 0.05 g/L, respectively. Our results demonstrate the fungicidal actions of emodin, physcion, and rhein from C. tora.
Centers for Disease Control and Prevention1, Chinese Center for Disease Control and Prevention2, Southeast University3, The Chinese University of Hong Kong4, Gadjah Mada University5, International Vaccine Institute6, Chonbuk National University7, Hanyang University8, Thailand Ministry of Public Health9, Pasteur Institute10
TL;DR: The Asian Rotavirus Surveillance Network is a novel, regional approach to surveillance for vaccine-preventable diseases that should provide increased visibility and advocacy, enable more efficient data collection, facilitate training, and serve as the paradigm for rotavirus surveillance activities in other regions.
Abstract: Rotavirus remains the most common cause of severe, dehydrating diarrhea among children worldwide. Several rotavirus vaccines are under development. Decisions about new vaccine introduction will require reliable data on disease impact. The Asian Rotavirus Surveillance Network, begun in 2000 to facilitate collection of these data, is a regional collaboration of 36 hospitals in nine countries or areas that conduct surveillance for rotavirus hospitalizations using a uniform World Health Organization protocol. We summarize the Network's organization and experience from August 2001 through July 2002. During this period, 45% of acute diarrheal hospitalizations among children 0–5 years were attributable to rotavirus, higher than previous estimates. Rotavirus was detected in all sites year-round. This network is a novel, regional approach to surveillance for vaccine-preventable diseases. Such a network should provide increased visibility and advocacy, enable more efficient data collection, facilitate training, and serve as the paradigm for rotavirus surveillance activities in other regions.
TL;DR: In irradiated mice, COMP-Ang1 protected against radiation-induced apoptosis in microcapillary endothelial cells of the intestinal villi and prolonged survival and could be used as a therapeutic protein for specific protection against endothelial cell injury.
Abstract: Radiation therapy is a widely used cancer treatment, but it causes side effects even when localized radiotherapy is used. Extensive apoptosis of microvascular endothelial cells of the lamina propria is the primary lesion initiating intestinal radiation damage after abdominal radiation therapy. Many in vitro studies suggest that angiopoietin-1 (Ang1) has potential therapeutic applications in enhancing endothelial cell survival. For in vivo use, we developed a soluble, stable, and potent Ang1 variant, COMP-Ang1. COMP-Ang1 is more potent than native Ang1 in phosphorylating the Tie2 receptor in lung endothelial cells in vivo. Interestingly, COMP-Ang1 administered i.v. was mainly localized to microvascular endothelial cells of the intestinal villi and lung but not to microvascular endothelial cells of the liver. In irradiated mice, i.v. COMP-Ang1 protected against radiation-induced apoptosis in microcapillary endothelial cells of the intestinal villi and prolonged survival. Thus, COMP-Ang1 could be used as a therapeutic protein for specific protection against endothelial cell injury.
TL;DR: By simulations, it is shown that quantization error can be reduced up to 50% by the proposed error compensation method compared with the existing method with approximately the same hardware overhead in the bias generation circuit.
Abstract: This paper presents an error compensation method for a modified Booth fixed-width multiplier that receives a W-bit input and produces a W-bit product. To efficiently compensate for the quantization error, Booth encoder outputs (not multiplier coefficients) are used for the generation of error compensation bias. The truncated bits are divided into two groups depending upon their effects on the quantization error. Then, different error compensation methods are applied to each group. By simulations, it is shown that quantization error can be reduced up to 50% by the proposed error compensation method compared with the existing method with approximately the same hardware overhead in the bias generation circuit. It is also shown that the proposed method leads to up to 35% reduction in area and power consumption of a multiplier compared with the ideal multiplier.
TL;DR: In this paper, a dense pure WC hard material with a relative density of up to 97.6% was produced with simultaneous application of 60MPa pressure and electric current of 2800A within 2min.
Abstract: The rapid sintering of nano-structured WC hard materials in a short time is introduced with a focus on the manufacturing potential of this spark plasma sintering process. The advantage of this process allows very quick densification to near theoretical density and prohibition of grain growth in nano-structured materials. A dense pure WC hard material with a relative density of up to 97.6% was produced with simultaneous application of 60 MPa pressure and electric current of 2800 A within 2 min. A larger current caused a higher rate of temperature increase and therefore a higher densification rate of the WC powder. The finer the initial WC powder size the higher is the density and the better are the mechanical properties. The fracture toughness and hardness values obtained were 6.6 MPa m1/2 and 2480 kg/mm2, respectively under 60 MPa pressure and 2800 A using 0.4 μm WC powder.
TL;DR: It is demonstrated that the surface topography plays an important role for phenotypic expression of the MG63 osteoblast-like cells as micropore size gets larger, cell number is reduced and cell differentiation and matrix production is increased.
TL;DR: In this paper, the optical properties of ZnO bulk grown by hydrothermal method were investigated on the Znterminated surface by using Raman scattering and photoluminescence (PL).
TL;DR: Evidence is provided that TERT is inducible in postmitotic neurons after ischemic brain injury and prevents NMDA neurotoxicity through shift of the cytosolic free Ca2+ into the mitochondria, and thus plays a protective role in ameliorating isChemic neuronal cell death.
Abstract: The catalytic subunit of telomerase reverse transcriptase (TERT) protects dividing cells from replicative senescence in vitro. Here, we show that expression of TERT mRNA is induced in the ipsilateral cortical neurons after occlusion of the middle cerebral artery in adult mice. Transgenic mice that overexpress TERT showed significant resistance to ischemic brain injury. Among excitotoxicity, oxidative stress, and apoptosis comprising of routes of ischemic neuronal death, NMDA receptor-mediated excitotoxicity was reduced in forebrain cell cultures overexpressing TERT. NMDA-induced accumulation of cytosolic free Ca2+ ([Ca2+]c) was reduced in forebrain neurons from TERT transgenic mice, which was attributable to the rapid flow of [Ca2+]c into the mitochondria from the cytosol without change in Ca2+ influx and efflux through the plasma membrane. The present study provides evidence that TERT is inducible in postmitotic neurons after ischemic brain injury and prevents NMDA neurotoxicity through shift of the cytosolic free Ca2+ into the mitochondria, and thus plays a protective role in ameliorating ischemic neuronal cell death.
TL;DR: In this article, the effect of the molecular weight of the polymer on electrospun poly(ethylene terephthalate) (PET) nonwovens and their mechanical properties as a function of the linear velocity of drum surface was evaluated.
Abstract: In this study, we evaluated the effect of the molecular weight of the polymer on electrospun poly(ethylene terephthalate) (PET) nonwovens, and their mechanical properties as a function of the linear velocity of drum surface. Polymer solutions and electrospun PET nonwovens were characterized by means of viscometer, tensiometer, scanning electron microscope (SEM), wide angle X-ray diffraction measurement (WAXD) and universal testing machine (UTM). By keeping the uniform solution viscosity, regardless of molecular weight differences, electrospun PET nonwovens with similar average diameter could be obtained. In addition, the mechanical properties of the electrospun PET nonwovens were strongly dependent on the linear velocity of drum surface. From the results of the WAXD scan, it was found that the polymer took on a particular molecular orientation when the linear velocity of drum surface was increased. The peaks became more definite and apparent, evolving from an amorphous pattern at 0 m/min to peaks and signifying the presence of crystallinity at 45 m/min.
TL;DR: In simulated plastic root canals, the diameter and taper of root canal influenced the effectiveness of ultrasonic irrigation to remove artificially placed dentine debris.
Abstract: Aim To investigate the influence of diameter and taper of root canals on the effectiveness of ultrasonic irrigation to remove artificially placed dentine debris from simulated uninstrumented extensions in simulated root canals.
Method Three groups of standard canals were cut in resin blocks using either size 20, .04 taper ProFile instruments, size 20, .06 Greater Taper (GT) rotary instruments or size 20, .08 GT instruments, respectively. Each resin block was then split longitudinally through the canal, forming two halves. In one canal wall, a standard groove 4 mm in length was cut 2–6 mm from the apical end of the canal, to simulate uninstrumented canal extensions. Each groove was filled with dentine debris mixed with 2% NaOCl to simulate a situation when dentine debris accumulates in the uninstrumented canal extensions. Each canal was reassembled by joining the two halves of the resin block by means of wires and sticky wax. In each canal ultrasonic irrigation was performed for 3 min using 2% NaOCl as irrigant. Before and after irrigation, images of each half of the canal with a groove were taken using a microscope and a digital camera, after which they were scanned into a PC as TIFF images. The quantity of dentine debris in the groove was evaluated using a scoring system: the higher the score, the larger the amount of debris remaining. The score data were analysed by means of Kruskal–Wallis and Mann–Whitney U-tests.
Results After ultrasonic irrigation, the debris score for the size 20, .04 taper group was significantly higher than that for the size 20, .06 group (P = 0.040) and the size 20, .08 group (P = 0.006) groups. However, no significant difference was found between the size 20, .06 and the size 20, .08 groups (P = 0.320).
Conclusion In simulated plastic root canals, the diameter and taper of root canal influenced the effectiveness of ultrasonic irrigation to remove artificially placed dentine debris.
TL;DR: Results showed that RCMF contained an antioxidant potential and strongly suppressed the proliferative capability of B lymphoma cells, and flavonoid derivatives are the main active compounds responsible for the antioxidant and antiproliferative activities of RCMF.
TL;DR: The limited diversity of msp2 transcripts in the absence of immune pressure suggests selection for Msp2 by specific functions beyond that of immune evasion, in spite of a large genomic reservoir for MSP2 diversity.
Abstract: Background
Anaplasma phagocytophilum strains often vary in Msp2 expression, a situation assumed to be related to immune evasion. However, Msp2 is also an adhesin, and little is known about the role of endogenous msp2 transcriptional changes in the absence of immune selection. Thus, Msp2 profiles and msp2 transcripts of low passage A. phagocytophilum Webster strain, initially comprised of a single abundant msp2 transcript, were re-examined after ≥ 20 in vitro passages without immune selection.
TL;DR: The results suggest that mycoviruses modulate the MAPK and thereby provoke the aberrant expression of target genes, some of which are likely to be implicated in viral symptom development.
Abstract: We examined the biological function of cpmk1, which encodes a MAPK of Cryphonectria parasitica, and its regulation by mycovirus. Sequence comparisons revealed that cpmk1 had highest homology with osm1, a hog1-homologue from Magnaporthe grisea. A growth defect was observed in the cpmk1-null mutant under hyperosmotic conditions, indicating that cpmk1 functionally belongs to a hog1 subfamily. Immunoblot analyses indicated that the CpMK1 pathway was affected specifically in hyperosmotic conditions by the hypovirus CHV1-EP713. Moreover, the virus-infected hypovirulent UEP1 strain also exhibited severe osmosensitivity compared to the virus-free isogenic strain EP155/2, thus providing additional evidence for viral regulation of cpmk1 in response to a hypertonic stress. Besides osmosensitivity, disruption of cpmk1 resulted in several, but not all, hypovirulence-associated changes, such as reduced pigmentation, conidiation, laccase production and cryparin expression. However, the cpmk1-null mutant exhibited an increased accumulation of pheromone gene transcripts. Virulence assays of the cpmk1-null mutant revealed reduced canker area, but not as severe as that of UEP1. These results suggest that mycoviruses modulate the MAPK and thereby provoke the aberrant expression of target genes, some of which are likely to be implicated in viral symptom development.
TL;DR: In this article, the synthesis of titanium dioxide nanofibers with 200-300 nm diameter was presented, which were obtained by high temperature calcination of the inorganic-organic composite fibers.
Abstract: The synthesis of titanium dioxide nanofibers with 200–300 nm diameter was presented. The new inorganic-organic hybrid nanofibers were prepared by sol-gel processing and electrospinning technique using a viscous solution of titanium isopropoxide (TiP)/poly(vinyl acetate) (PVAc). Pure titanium dioxide nanofibers were obtained by high temperature calcination of the inorganic-organic composite fibers. SEM, FT-IR, and WAXD techniques were employed to characterize these nanofibers. The titanium dioxide nanostructured fibers have rougher surface and smaller diameter compare with PVAc/TiP composite nanofibers. The anatase to rutile phase transformation occurred when the calcination temperature was increased from 600 °C to 1000 °C.
TL;DR: In this article, the machinability and deformation mechanism of Si 3 N 4 /BN nanocomposites were investigated, and the damage of the monolithic Si3 N 4 and Si 3 n 4/BN microcomposites indicated a classical Hertzian cone fracture and many large cracks.
Abstract: The machinability and deformation mechanism of Si 3 N 4 /BN nanocomposites were investigated in the present work. The fracture strength of Si 3 N 4 /BN microcomposites remarkably decreased with increased hexagonal graphitic boron nitride (h-BN) content, although machinability was somewhat improved. However, the nanocomposites fabricated using the chemical method simultaneously had high fracture strength and good machinability. Hertzian contact tests were performed to clarify the deformation behavior by mechanical shock. As a result of this test, the damage of the monolithic Si 3 N 4 and Si 3 N 4 /BN microcomposites indicated a classical Hertzian cone fracture and many large cracks, whereas the damage observed in the nanocomposites appeared to be quasi-plastic deformation.