Energy-absorption analyses of honeycomb-structured Al-alloy and nylon sheets using modified split Hopkinson pressure bar.

Thin cylindrical honeycomb-structured aluminum alloy and mono-cast (MC) nylon were studied as superior energy-absorbing materials compared to metallic foams. Their energy-absorbing performance was assessed using a modified split Hopkinson pressure bar (SHPB). Key parameters included maximum impact acceleration (amax) and its reduction ratio (compared to the none-specimen case). The lowest amax reduction ratio was observed in bulk Al sheets without honeycomb cavities. As the cavity fraction increased up to 79% in honeycomb-structured Al specimens, the amax reduction ratio improved due to broadened stress-time curves with a shallow-plateau shape. This made high-cavity-fraction Al specimens preferable for higher-energy absorption and lighter-weight buffering materials. In nylon specimens, the amax reduction ratio increased until the fraction reached 52% due the softer and more deformable nature of the polymeric nylon. Thicker or rotated Al specimens also showed higher amax reduction ratios due to sufficient and continuous energy absorption. The modified SHPB demonstrated effective energy-buffering concepts and provided insightful amax interpretations, overcoming complexities in energy absorption analyses.

FeF3/(Acetylene Black and Multi-Walled Carbon Nanotube) Composite for Cathode Active Material of Thermal Battery through Formation of Conductive Network Channels.

Considerable research is being conducted on the use of FeF3 as a cathode replacement for FeS2 in thermal batteries. However, FeF3 alone is inefficient as a cathode active material because of its low electrical conductivity due to its wide bandgap (5.96 eV). Herein, acetylene black and multi-walled carbon nanotubes (MWCNTs) were combined with FeF3, and the ratio was optimized. When acetylene black and MWCNTs were added separately to FeF3, the electrical conductivity increased, but the mechanical strength decreased. When acetylene black and MWCNTs were both added to FeF3, the FeF3/M1AB4 sample (with 1 wt.% MWCNTs and 4% AB) afforded a discharge capacity of approximately 74% of the theoretical capacity (712 mAh/g) of FeF3. Considering the electrical conductivity and mechanical strength, this composition was confirmed to be the most suitable.

Development of a low-melting-point eutectic salt and evaluation of its discharge performance for light weight thermal batteries.

This paper proposes low-melting-point eutectic salts containing RbCl as electrolytes for light weight thermal batteries. The handleability of the eutectic salts was remarkably improved for commercialisation. Their performance as thermal battery molten-salt electrolytes was verified using tests on a single cell and a 12-cell stacked battery.

Binder-Free Cathode for Thermal Batteries Fabricated Using FeS2 Treated Metal Foam.

In this study, we fabricated a cathode with lower amounts of additive materials and higher amounts of active materials than those of a conventional cathode. A thermal battery was fabricated using FeS2 treated foam as the cathode frame, and its feasibility was verified. X-ray diffraction, transmission electron microscopy, and scanning electron microscopy were used to analyze the effects of thermal sulfidation temperature (400 and 500°C) on the structure and surface morphology of the FeS2 foam. The optimal temperature for the fabrication of the FeSx treated foam was determined to be 500°C. The FeS2 treated foam reduced the interfacial resistance and improved the mechanical strength of the cathode. The discharge capacity of the thermal battery using the FeS2 treated foam was about 1.3 times higher than that of a thermal battery using pure Fe metal foam.

Carbon-Heteroatom Bond Formation by an Ultrasonic Chemical Reaction for Energy Storage Systems.

The direct formation of CN and CO bonds from inert gases is essential for chemical/biological processes and energy storage systems. However, its application to carbon nanomaterials for improved energy storage remains technologically challenging. A simple and very fast method to form CN and CO bonds in reduced graphene oxide (RGO) and carbon nanotubes (CNTs) by an ultrasonic chemical reaction is described. Electrodes of nitrogen- or oxygen-doped RGO (N-RGO or O-RGO, respectively) are fabricated via the fixation between N2 or O2 carrier gas molecules and ultrasonically activated RGO. The materials exhibit much higher capacitance after doping (133, 284, and 74 F g-1 for O-RGO, N-RGO, and RGO, respectively). Furthermore, the doped 2D RGO and 1D CNT materials are prepared by layer-by-layer deposition using ultrasonic spray to form 3D porous electrodes. These electrodes demonstrate very high specific capacitances (62.8 mF cm-2 and 621 F g-1 at 10 mV s-1 for N-RGO/N-CNT at 1:1, v/v), high cycling stability, and structural flexibility.

Development and application of evaluation indices for hospital infection surveillance and control programs in the Republic of Korea.

OBJECTIVE: To develop new evaluation indices of infection control and to use them to evaluate Korean infection surveillance and control programs (ISCPs). DESIGN: We performed a questionnaire-based survey to 164 acute care general hospitals throughout the Republic of Korea that had more than 300 beds. Study methods were based completely on those of the Study on the Efficacy of Nosocomial Infection Control (SENIC). Four SENIC indices (hospital epidemiologist index, infection control nurse index, surveillance index, and control index) and 4 newly developed indices (healthcare worker index, quality improvement index, resource index, and hand hygiene facilities index) were used to evaluate Korean ISCPs. Data were collected by questionnaire from June 17 to October 11, 2003. SETTING: One hundred sixty-four general hospitals with more than 300 beds in the Republic of Korea. RESULTS: Personnel from 85 general hospitals responded to the study questionnaire. The reliability and validity of the evaluation indices were statistically significant (P<.05). The 8 evaluation indices were categorized into 2 factor groups: personnel factors (hospital epidemiologist index and infection control nurse index) and activity factors (the remaining 6 indices). Korean ISCPs showed a major weakness in surveillance. The scores for the newly developed evaluation indices were better than those for the SENIC evaluation indices. However, most Korean hospitals were estimated to have had only slight reductions in nosocomial infection rates. The evaluation indices were influenced significantly by the number of beds in the hospital, whether the hospital was located in the Seoul-Gyonggi region, the presence of full-time infection control nurses at the hospital, the education level of the infection control nurses, and the nurses' experience in infection control (P<.05). CONCLUSIONS: The reliability and validity of the SENIC evaluation indices and the newly developed evaluation indices were satisfactory in evaluating Korean ISCPs. However, surveillance should be improved to increase the efficacy of Korean ISCPs.