Abstract Shisaka Smelting Co., Ltd. has recovered crude zinc oxide pellets from an electric arc furnace dust (EAF dust) by the Waelz kiln process since 1977. The EAF dust processing line consists of ...a reduction roasting process, a Waelz oxide washing process, and a drying/calcination process. In late years, about 90,000 tons of EAF dust is processed annually at Shisaka. The recovered zinc is sold to zinc smelters as crude zinc oxide pellets, and the amount of production of the pellets is about 40,000 tons per year. Two types of zinc oxide pellets are produced, and the product for electro-refinery requires high quality, especially in fluorine reduction. Most of fluorine are distributed to the clinker in a reduction roasting process, and others are distributed to the Waelz oxide. Conventionally, high-grade crude zinc oxide pellets were produced by washing the Waelz oxide and by volatilizing and separating fluorine under high temperature operation in a drying rotary kiln. However, formation of accretion in the kiln and damage of the shell and refractories of the kiln often occurred under the influence of high temperature operation, and stable consecutive operation of the kiln was difficult. To improve this situation, the fluorine input was reduced by compounding management of EAF dust in the reduction roasting process, and the material residence time in the drying rotary kiln was extended by reducing rotary speed. These improvements resulted in stable consecutive operation under low temperature conditions and increased production of high-grade crude zinc oxide pellets. To improve this situation, the fluorine input was reduced by compounding management of EAF dust in the reduction roasting process, and the material residence time in the drying rotary kiln was extended by reducing rotary speed. These improvements resulted in stable consecutive operation under low temperature conditions and increased production of high-grade crude zinc oxide pellets.
Contact precautions are required to prevent transmission of multi-drug-resistant organisms; however, reports on adherence rates vary. This study used video monitoring to evaluate adherence to the use ...of personal protective equipment (PPE) by different types of healthcare workers.
This observational study was conducted in a 781-bed tertiary hospital from July 2016 to March 2017. Cameras were installed in areas where staff don PPE. Infection control teams observed the videos and assessed adherence rates.
In total, 1097 opportunities for donning PPE were observed. Most staff observed were nurses and nursing assistants (Ns/Nsas) (880/1097, 80.2%). Overall, the adherence rate to appropriate PPE use was 34.0%. The adherence rate among Ns/Nsas was lower (239/858, 27.9%) compared with infectious disease doctors (18/18, 100%) and cleaning staff (42/49, 85.7%). The adherence rate for PPE use for Clostridium difficile infection (CDI) with toxin detection was significantly higher than that for CDI without toxin detection and multi-drug-resistant organisms (P<0.001 for both). The adherence rate for patients with an independent functional status was higher than that for patients with a dependent functional status (P=0.018). The adherence rate was lower in the intensive care unit (ICU) than in non-ICU wards (27.6% vs 36.5%; P=0.006).
Video monitoring is a useful tool for monitoring adherence to PPE use, facilitating observation of more PPE opportunities than direct observation. Adherence to contact precautions varied by occupation; however, overall adherence was insufficient. The lower adherence rate in nurses might be due to more frequent care visits.
We analysed associations between exposure to nightlife businesses and severe acute respiratory syndrome coronavirus 2 PCR test results at a tertiary hospital in Tokyo between March and April 2020. A ...nightlife group was defined as those who had worked at or visited the businesses. We included 1517 individuals; 196 (12.9%) were categorised as the nightlife group. After propensity score matching, the proportion of positive PCR tests in the nightlife group was significantly higher than that in the non-nightlife group (nightlife, 63.8%; non-nightlife, 23.0%; P < 0.001). An inclusive approach to mitigate risks related to the businesses needs to be identified.
► Corrosion resistance of these Al-containing ODS steels in lead-bismuth eutectic containing 10-6 wt% oxygen was investigated. ► The test temperature was 650 and 700 °C and the maximum exposure ...duration was 10000 h. ► Al surface alloying by pulsed electron beam improved corrosion resistance. ► Al addition to the matrix with small amounts of Zr or Hf was also effective.
The effectiveness of Al addition for improvement of the corrosion resistance of ODS steel in lead–bismuth eutectic (LBE) was investigated. Al-alloying surface treatment using a GESA facility was applied to 9Cr-ODS martensitic steel, and the corrosion resistance in stagnant LBE containing 10−6wt% oxygen was subsequently examined. Corrosion resistance of ODS ferritic steels with high Cr content (14.7wt%), containing 3.3–3.8wt% Al and small amounts of Zr or Hf, was also examined. Al-alloying surface treated 9Cr-ODS martensitic steel was tested at 650°C and ODS ferritic steels with high Cr content, containing 3.3–3.8wt% Al and small amounts of Zr or Hf, were tested at 650 and 700°C. The maximum exposure duration was 10,000h. All tested materials showed good corrosion resistance under all test conditions. Both the Al-alloying surface treatment by the GESA facility and the Al addition to the matrix with small amounts of Zr or Hf effectively improved the compatibility of ODS steel with LBE at high temperatures.
The corrosion resistances of ODS steels with 0–3.5
wt% Al and 13.7–17.3
wt% Cr, and a 12Cr steel were examined. The experiments were conducted at 550 and 650
°C for up to 3000
h in stagnant LBE ...containing 10
−6 and 10
−8
wt% oxygen for the ODS steels, and at 550
°C for up to 5000
h in that containing 10
−8
wt% oxygen for the 12Cr steel. Protective Al oxide scales were formed on the surfaces of the ODS steels with approximately 3.5
wt% Al and 13.7–17.3
wt% Cr. Addition of Al is very effective in improving the corrosion resistance of ODS steels. The ODS steel with 16
wt% Cr and no Al did not show any corrosion resistance except in LBE with 10
−6
wt% oxygen at 550
°C. The corrosion resistance may not be improved by solely increasing Cr concentration.
In July 1996, an outbreak of Escherichia coli O157: H7 infection occurred among schoolchildren in Sakai City, Osaka, Japan. This outbreak developed in 13 North-East District and 34 Middle-South ...District elementary schools in the city. All children hospitalized on July 17–19 had presented on July 8 (North-East District) and July 9 (Middle-South District). School lunches served on July 1 and 8 in the North-East District and on July 1, 4, 8, and 9 in the Middle-South District were proposed by a food consumption study to be associated with infection. White radish sprouts from a single farm were the only uncooked food common to the most highly implicated meals on the involved days in two school districts (sweet and sour chicken with lettuce on July 8 in the North-East District and chilled Japanese noodles on July 9 in the Middle-South District). Two incidents of E. coli O157: H7 in neighboring areas were also related to white radish sprouts from the farm. The pulse-field gel electrophoresis patterns of isolates from patients in these two districts and the neighboring areas were identical. Thus, it was concluded that the cause of the outbreak was the white radish sprouts shipped on July 7–9 from one particular farm. Am J Epidemiol 1999;150:787-96.
Magnesium (Mg) alloys are attractive as structural materials due to their light weight and high specific strength. It is well known that Mg alloy has hexagonal close-packed (HCP) structure and only ...basal slip or twinning can operate during plastic deformation because critical resolved shear stresses of the other slip systems such as pyramidal or prismatic slips are much higher than the basal slip. Thus sometimes characteristic fracture surfaces are formed during stress corrosion cracking (SCC) or fatigue crack propagation (FCP) in Mg alloys, where many parallel lines are formed. These lines are different from so-called fatigue striations, because they are formed even under sustained load condition of SCC. Consequently, electron back scattered diffraction (EBSD) technique was applied on the fracture surface, and the formation mechanism of parallel lines was investigated. EBSD-assisted fractography had revealed that the characteristic parallel lines were formed due to the operation of basal slips, not twining. It is considered that hydrogen-enhanced localized plasticity (HELP) mechanism had been activated under corrosive environment.
We compared the cognitive functions and interictal cerebral glucose metabolism of 11 patients with mesial temporal lobe epilepsy (MTLE) with frequent seizures to those of 10 patients with MTLE with ...rare seizures; the groups were matched for age, sex, education, IQ, and focus side. The frequent-seizure group had more set-shifting impairment that correlated with glucose hypometabolism in the prefrontal cortices. Our results suggest that frequent seizures in MTLE are associated with hypofunction of the prefrontal cortex.
Our new proposal of voltage-control spintronics memory (VoCSM) in which spin-orbit torque in conjunction with the voltage-control-magnetic-anisotropy effect works as the writing principle showed ...small switching current of <inline-formula> <tex-math notation="LaTeX">37~\mu \text{A} </tex-math></inline-formula> for about 350 <inline-formula> <tex-math notation="LaTeX">K_{B}T </tex-math></inline-formula> switching energy. This indicates VoCSM's writing efficiency is so high that VoCSM would be applicable for deep learning memories requiring ultra-low power consumption.
•Effects of helium production, displacement damage on mechanical properties and surface acoustic wave (SAW) in austenitic stainless steels of 316FR and 304 and a martensitic steel HCM12A steels are ...presented.•Large irradiation hardening due to He was measured by nano-indentation technique in 316FR, 304, and HCM12A irradiated at 550 °C in a high fluence irradiation facility (HIT).•Correlation between the irradiation hardening and SAW propagation velocity was obtained in 316FR.•SAW technique is very useful for irradiation damage as a non-destructive test.
The effects of helium production, displacement damage on mechanical properties and microstructures were investigated in some specimens such as austenitic stainless steels of SUS304 and SUS316 and a high chromium martensitic steel of HCM12A steels irradiated in a high fluence irradiation facility (HIT) of the University of Tokyo. The simultaneous dual ion (nickel plus helium ions) irradiations were adopted to simulate nuclear irradiation environments such as fast reactor and fusion reactor at HIT to 1 or 10 dpa and to 0, 1, 10, and 100 appm-He at 500, 550, and 600 °C. Thin foils for a transmission electron microscopy (TEM) were prepared with a focused ion beam (FIB) micro-sampling system. After the irradiation, the microstructures were observed by a transmission electron microscope and the irradiation hardening was measured by nano-indentation technique. In this study, the efficient of non-destructive measurement method of surface acoustic wave (SAW) excited by laser beam on the detection of radiation hardening behavior was also examined. Irradiation hardening was observed and the increment was tended to increase with dpa and He/dpa, which was especially effective in the condition of 100 appmHe/dpa even at 550 °C. Non-linear effect on amplitude of the excited SAW was also observed on the ion irradiated materials, and the propagation velocity of SAW was tended to be increased with irradiation dose. It was found that the behaviors of SAWs results were correlated with the changes of mechanical properties.
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