The Study of Copper Powder Sintering for Porous Wick Structures with High Capillary Force.

The porosity, permeability, and capillary force of porous sintered copper were examined in relation to the effects of copper powder size, pore-forming agent, and sintering conditions. Cu powder with particle sizes of 100 and 200 µm was mixed with pore-forming agents ranging from 15 to 45 weight percent, and the mixture was sintered in a vacuum tube furnace. Copper powder necks were formed at sintering temperatures higher than 900 °C. The porosity, as determined by the Archimedes measurement method, and the permeability performance of the sintered body displayed higher values when the Cu powder size was uniform or small. To investigate the capillary force of the sintered foam, a test was conducted using a raised meniscus test device. As more forming agent was added, the capillary force increased. It was also higher when the Cu powder size was larger and the size of the powders was not uniform. The result was discussed in relation to porosity and pore size distribution.

Topographically designed hybrid nanostructures via nanotransfer printing and block copolymer self-assembly.

Nanotransfer printing (nTP) has attracted much attention due to its high pattern resolution, simple process, and low processing cost for useful nanofabrication. Here, we introduce a thermally assisted nTP (T-nTP) process for the effective fabrication of various periodic three-dimensional (3D) nanosheets, such as concavo-convex lines, spine lines, square domes, and complex multi-line patterns. The T-nTP method allows continuous nanoscale 3D patterns with functionality to be transferred onto both rigid and flexible substrates by heat without any collapse of uniform convex nanostructures with nanochannels. We also show the pattern formation of multi-layered hybrid structures consisting of two or more materials by T-nTP. Furthermore, the formation of silicon oxide nanodots (0D) within a printed metallic nanowave structure (3D) can be achieved by the combined method of T-nTP and the self-assembly of poly(styrene-b-dimethylsiloxane) (PS-b-PDMS) block copolymers. Moreover, we demonstrate how to obtain well-defined oxide-metal hybrid nanostructures (0D-in-3D) through the spontaneous accommodation of PDMS spheres in the confined spaces of an Au-wave nanotemplate. This approach is applicable during the nanofabrication of various high-resolution devices with complex geometrical nanopatterns.

Controlled self-assembly of block copolymers in printed sub-20 nm cross-bar structures.

Directed self-assembly (DSA) of block copolymers (BCPs) has garnered much attention due to its excellent pattern resolution, simple process, and good compatibility with many other lithography methods for useful nanodevice applications. Here, we present a BCP-based multiple nanopatterning process to achieve three-dimensional (3D) pattern formation of metal/oxide hybrid nanostructures. We employed a self-assembled sub-20 nm SiO x line pattern as a master mold for nanotransfer printing (nTP) to generate a cross-bar array. By using the transfer-printed cross-bar structures as BCP-guiding templates, we can obtain well-ordered BCP microdomains in the distinct spaces of the nanotemplates through a confined BCP self-assembly process. We also demonstrate the morphological evolution of a cylinder-forming BCP by controlling the BCP film thickness, showing a clear morphological transition from cylinders to spheres in the designated nanospaces. Furthermore, we demonstrate how to control the number of BCP spheres within the cross-bar 3D pattern by adjusting the printing angle of the multiple nTP process to provide a suitable area for spontaneous BCP accommodation. This multiple-patterning-based approach is applicable to useful 3D nanofabrication of various devices with complex hybrid nanostructures.

Effects of Cooling Rate during Quenching and Tempering Conditions on Microstructures and Mechanical Properties of Carbon Steel Flange.

This study investigated the mechanical properties of steel in flanges, with the goal of obtaining high strength and high toughness. Quenching was applied alone or in combination with tempering at one of nine combinations of three temperatures TTEM and durations tTEM. Cooling rates at various flange locations during quenching were first estimated using finite element method simulation, and the three locations were selected for mechanical testing in terms of cooling rate. Microstructures of specimens were observed at each condition. Tensile test and hardness test were performed at room temperature, and a Charpy impact test was performed at -46 °C. All specimens had a multiphase microstructure composed of matrix and secondary phases, which decomposed under the various tempering conditions. Decrease in cooling rate (CR) during quenching caused reduction in hardness and strength but did not affect low-temperature toughness significantly. After tempering, hardness and strength were reduced and low-temperature toughness was increased. Microstructures and mechanical properties under the various tempering conditions and CRs during quenching were discussed. This work was based on the properties directly obtained from flanges under industrial processes and is thus expected to be useful for practical applications.

Sensory characteristics and consumer acceptance of frozen cooked rice by a rapid freezing process compared to homemade and aseptic packaged cooked rice.

Descriptive analysis and consumer acceptance tests were conducted with frozen (FCR), homemade (HCR), and aseptic-packaged (ACR) cooked rice products from two cultivars-IM and SD. FCR was prepared using a rapid freezing process, which may provide consumers with a quality similar to that of HCR. The intensity of the flavors of roasted, glutinous rice, rice cake, and rice starch and the textures of glutinousness, moistness, chunkiness, adhesiveness, and squishiness were all greater in the FCR as compared to the HCR and ACR (p<0.05) in IM and SD cultivars. The differences in sensory characteristics between the FCR and ACR were larger than the equivalent differences between the FCR and HCR. Overall consumer acceptance ratings for FCR in overall aspect, appearance, aroma, and texture were not significantly different compared to those for HCR (p>0.05); however, in most cases these factors showed significant differences when compared with ACR (p<0.05). From partial least square regression analysis, cooked rice was positively related to sweet, transparency, glossiness, roasted, glutinousness, chunkiness, moistness, glutinous rice, adhesiveness, rice shape, rice starch, and squishiness attributes but negatively related to raw rice, old rice, old rice aroma, a particle feeling, off-aroma, white color, scatteredness, slickness, size of cooked rice, and firmness attributes.

Magnetic levitating polymeric nano/microparticular substrates for three-dimensional tumor cell culture.

Herein, we describe magnetic cell levitation models using conventional polymeric microparticles or nanoparticles as a substrate for the three-dimensional tumor cell culture. When the magnetic force originating from the ring-shaped magnets overcame the gravitational force, the magnetic field-levitated KB tumor cells adhered to the surface area of magnetic iron oxide (Fe(3)O(4))-encapsulated nano/microparticles and concentrated clusters of levitated cells, ultimately developing tumor cells to tumor spheroids. These simple cell culture models may prove useful for the screening of anticancer drugs and their formulations.

pH-sensitive properties of surface charge-switched multifunctional polymeric micelle.

A surface charge-switched polymeric micelle with a pH signal was developed as a drug-carrying nanovehicle for tumor targeting. The micelles (particle size: approximately 85 nm), constructed from poly(L-lactic acid)-b-poly(ethylene glycol)-b-poly(L-lysine-N(epsilon)-(2,3-dimethyl maleic acid)) (PLA-b-PEG-b-PLys-DMA) and formed by self-assembly in an aqueous pH 7.4 solution, consisted of a hydrophobic core (PLA core) and two hydrophilic shells (PEG shell and PLys-DMA shell). An anionic charge can be built on the surface of the micelle at a physiological pH (approximately pH 7.4) due to 2,3-dimethyl maleic acid (DMA). However, DMA becomes chemically dissociated from the micelle under mild acidic conditions (pH 6.5-7.0) such as that found in solid tumors, which results in the formation of a cationic surface due to the poly(L-lysine) (PLys). This pH-triggered switch in surface charge may enhance cellular uptake of micelles to solid tumors, via an adsorptive endocytotic pathway due to the electrostatic interaction between micelles and cells. In addition, blending of the poly(L-histidine) (polyHis) into the hydrophobic core provides a mechanism for endosomal pH-triggered drug-release from the polymeric micelle. These combined properties of the polymeric micelle may aid in tumor-specific drug accumulation and allow it to be used as an effective treatment for tumors.

Multivariate analysis of the predictors of survival for patients with hepatocellular carcinoma undergoing transarterial chemoembolization: focusing on superselective chemoembolization.

OBJECTIVE: While the prognostic factors of survival for patients with hepatocellular carcinoma (HCC) who underwent transarterial chemoembolization (TACE) are well known, the clinical significance of performing selective TACE for HCC patients has not been clearly documented. We tried to analyze the potential factors of disease-free survival for these patients, including the performance of selective TACE. MATERIALS AND METHODS: A total of 151 patients with HCC who underwent TACE were retrospectively analyzed for their disease-free survival (a median follow-up of 23 months, range: 1-88 months). Univariate and multivariate analyses were performed for 20 potential factors by using the Cox proportional hazard model, including 19 baseline factors and one procedure-related factor (conventional versus selective TACE). The parameters that proved to be significant on the univariate analysis were subsequently tested with the multivariate model. RESULTS: Conventional or selective TACE was performed for 40 and 111 patients, respectively. Univariate and multivariate analyses revealed that tumor multiplicity, venous tumor thrombosis and selective TACE were the only three independent significant prognostic factors of disease-free survival (p = 0.002, 0.015 and 0.019, respectively). CONCLUSION: In our study, selective TACE was a favorable prognostic factor for the disease-free survival of patients with HCC who underwent TACE.

Comparison of 7 staging systems for patients with hepatocellular carcinoma undergoing transarterial chemoembolization.

BACKGROUND: Many liver staging systems have been proposed for patients with hepatocellular carcinoma after locoregional therapy; however, controversies persist regarding which system is the best. In this study, the authors compared the performance of 7 staging systems in a cohort of patients with hepatocellular carcinoma who underwent transarterial chemoembolization. METHODS: In total, 131 patients with hepatocellular carcinoma who underwent transarterial chemoembolization between August 1998 and February 2005 were included in the study. Demographic, laboratory, and tumor characteristics were determined at diagnosis and before therapy. At the time of censorship, 109 patients had died (83.2%). Predictors of survival were identified by using the Cox proportional hazards model. The likelihood-ratio chi-square statistic and the Akaike Information Criterion were calculated for 7 prognostic systems to evaluate their discriminatory ability. Comparisons of the survival rate between each stage were performed to evaluate the monotonicity of the gradients using Kaplan-Meier estimation and the log-rank test. RESULTS: The 5-year survival rate for the entire cohort was 13.6%. The independent predictors of survival were serum albumin level (60 ng/mL), and portal or hepatic vein tumor thrombosis (P= .001, P= .001, P= .004, and P= .000, respectively). The Cancer of the Liver Italian Program classification system was superior to the other 6 prognostic systems regarding discriminatory ability and the monotonicity of the gradients. CONCLUSIONS: In this comparison of many staging systems, the Cancer of Liver Italian Program system provided the best prognostic stratification for a cohort the patients with hepatocellular carcinoma who underwent transarterial chemoembolization.

Local recurrence of hepatocellular carcinoma after segmental transarterial chemoembolization: risk estimates based on multiple prognostic factors.

OBJECTIVE: To determine the prognostic factors for local recurrence of nodular hepatocellular carcinoma after segmental transarterial chemoembolization. MATERIALS AND METHODS: Seventy-four nodular hepatocellular carcinoma tumors < or = 5 cm were retrospectively analyzed for local recurrence after segmental transarterial chemoembolization using follow-up CT images (median follow-up of 17 months, 4-77 months in range). The tumors were divided into four groups (IA, IB, IIA, and IIB) according to whether the one-month follow-up CT imaging, after segmental transarterial chemoembolization, showed homogeneous (Group I) or inhomogeneous (Group II) iodized oil accumulation, or whether the tumors were located within the liver segment (Group A) or in a segmental border zone (Group B). Comparison of tumor characteristics between Group IA and the other three groups was performed using the chi-square test. Local recurrence rates were compared among the groups using the Kaplan-Meier estimation and log rank test. RESULTS: Local tumor recurrence occurred in 19 hepatocellular carcinoma tumors (25.7%). There were: 28, 18, 17, and 11 tumors in Group IA, IB, IIA, and IIB, respectively. One of 28 (3.6%) tumors in Group IA, and 18 of 46 (39.1%) tumors in the other three groups showed local recurrence. Comparisons between Group IA and the other three groups showed that the tumor characteristics were similar. One-, two-, and three-year estimated local recurrence rates in Group IA were 0%, 11.1%, and 11.1%, respectively. The difference between Group IA and the other three groups was statistically significant (p = 0.000). CONCLUSION: An acceptably low rate of local recurrence was observed for small or intermediate nodular tumors located within the liver segment with homogeneous iodized oil accumulation.

Sub-micrometer patterning of proteins by electric lithography.

We report in this paper an electric lithographic (EL) technique to generate protein patterns with sub-micrometer resolution on a poly(N-tBOC-2-aminoethyl methacrylate) surface. In the EL process, an electric potential is applied between metal patterns on a mask and the poly(N-tBOC-2-aminoethyl methacrylate) layer to electrochemically induce the dissociation of the tBOC from the amine functional groups. Proteins are then selectively attached to the amine functional groups in the modified polymer surface areas to form protein patterns. This technique can reliably generate high-resolution protein patterns down to approximately 300 nm on the polymer surface at a high speed with a simple process/system.

Risk factors for local tumor recurrence after segmental transarterial chemoembolization for hepatocellular carcinoma: the importance of tumor located in the segmental border zone.

OBJECTIVE: We wanted to evaluate whether tumors located in a segmental border zone are predisposed to local recurrence after performing segmental transarterial chemoembolization for hepatocellular carcinoma. MATERIALS AND METHODS: Seventy-three hepatocellular carcinoma nodules were retrospectively analyzed for local tumor recurrence after performing segmental transarterial chemoembolization by using follow-up CT studies (median follow-up period: 20 months, range: 4-77 months). The tumors were divided into two groups according to whether the lesions were located at the segmental border zone (Group I) or not (Group II). Comparison of the tumor characteristics and chemoembolization methods between the two groups was performed using the chi-square test. The local recurrence rates were compared by Kaplan-Meyer method and analyzed with the log rank test. RESULT: Local tumor recurrence occurred for 25 hepatocellular carcinoma nodules (42.9%). The follow-up periods, tumor characteristics and chemoembolization methods between Groups l and ll were comparable. The local recurrence rate was 64.0% (16/25) in Group I and 18.8% (9/48) in Group II. The difference was statistically significant on the univariate and multivariate analyses (p = 0.000 for both). CONCLUSION: Tumor location in a segmental border zone was a significant risk factor for local tumor recurrence after performing segmental transarterial chemoembolization for hepatocellular carcinoma.

Percutaneous radiofrequency ablation therapy of hepatocellular carcinoma using multitined expandable electrodes: comparison of subcapsular and nonsubcapsular tumors.

OBJECTIVE: Our objective was to compare the prognosis of subcapsular and nonsubcapsular hepatocellular carcinoma after percutaneous radiofrequency ablation using multitined expandable electrodes. MATERIALS AND METHODS: Some controversies exist about the clinical usefulness of percutaneous radiofrequency ablation of subcapsular hepatocellular carcinoma. Twenty-eight patients underwent percutaneous radiofrequency ablation of 43 hepatocellular carcinomas using multitined expandable electrodes. Twelve tumors were subcapsular and 31 were nonsubcapsular. We attempted to use normal liver as a pathway to the tumor when possible. Tumor size ranged from 1.0 to 4.2 cm (mean, 1.8 cm). Median follow-up was 16 months. Initial ablation was considered to have been complete when no enhancement was seen in the region of the ablated lesion on 1-month follow-up CT or on follow-up CT performed immediately after repeated ablation. Initial complete ablation and local tumor progression rates were compared between subcapsular and nonsubcapsular tumors. Eleven patients had subcapsular tumors (group 1), whereas the other 17 patients did not have subcapsular tumors (group 2). Major complication and mortality rates were compared between the two groups. RESULTS: No significant differences in initial complete ablation rate (100% vs 96.7%, p = 1.000) or local tumor progression rate (0% vs 10.0%, p = 0.545) were found between subcapsular and nonsubcapsular tumors. No procedure-related major complication or mortality occurred. The overall 1- and 3-year survival rates were 89.3% and 60.3%, respectively. CONCLUSION: The rates of local tumor progression and complications for radiofrequency ablation using multitined expandable electrodes for subcapsular hepatocellular carcinomas were comparable to those for nonsubcapsular hepatocellular carcinomas.