Effects of Cold Working on Precipitation in Age-hardenable Alloys

Experiments have been carried out to examine the effects of cold working on the rate of precipitation in high purity copper alloys and aluminium alloys with measurements of electrical resistance, micro-hardness and thermo-electromotive force, X-ray Laue photographs and small angle scatter method. The correlation between cold working and the excess vacancies retained in quenching was investigated in water quenched and air cooled specimens. The experiments provided evidence that cold working accelerates the process at higher ageing temperatures, and that at lower ageing temperatures the rate of precipitation of cold worked specimens is less than that of unworked materials. In Al-Ag and Al-Cu alloys, the formation of zones was hindered and the precipitation of the more stable intermediate phases γ´ or θ´ was accelerated. The suppressive effect of cold working is thought to be a general phenomenon in age-hardenable alloys, because the effect is also found in alloys such as Cu-Cr alloys in which the precipitation sequence is simple. The mechanism of retarding by cold working is due to two effects : one is the sweeping out of the quenched-in vacancies, which are necessary for solute diffusion, by the motion of jogs in dislocations during cold working, and the other is the formation of many smaller clusters of enriched solute atoms which were formed by the stronger binding interaction energies between solute atoms and the lattice defects introduced by cold working

Aging Characteristics and Effects of Plastic Deformation on Precipitation in Al-4% Cu and Al-20% Ag Alloys with or without Trace Elements

The experiments have been carried out to examine the effects of plastic deformation and addition of small amounts of third elements on the aging process in Al-4%Cu and Al-20%Ag alloys by the X-ray Laue method, micro-hardness measurements, transmission electron microscopic studies and resistivity measurements. In binary Al-4% Cu alloys, the plastic deformation immediately after quenching retards the growth of G.P. (1) and G.P. (2), and accelerates the nucleation of the θ′ phase. In Al-20% Ag alloys, similar results are obtained. In undeformed ternary Al-Cu alloy, the retarding effects of third elements on aging become stronger in the order Be<Ti<Zr. In Al-Cu-Zr alloys, the plastic deformation much accelerates the growth of G.P. (1). The role of excess vacancies on aging and the interaction between dislocation and precipitates are discussed

Transmission Electron Microscopic Investigation on Recrystallization and Precipitation of Magnesium and Magnesium Alloys

Experiments have been carried out to examine aging characteristics, recrystallization phenomena and effects of plastic deformation after water-quenching on the precipitation of Mg-Th alloys in the composition range from 1.7 to 4.0 w/t% thorium as compared with pure magnesium, Mg-Zn and Mg-Al alloys mainly with electron microscopic observations in thin foils. In Mg-4.0% Th alloys, G. P. zones were confirmed to exist before the appearance of the transition phase Mg2Th in accordance with the result of measurements of electrical resistance. The presence of thorium in a magnesium alloy greatly retarded such processes as recovery and recrystallization. This slowing up process seems to be reflected in the slow precipitation rate of Mg-Th compounds. The effects of cold working on precipitation in these alloys are not simple but complex

Electron-Microscopic Investigation on Precipitation Phenomena in Aluminium-Zinc Alloys

The precipitation process, its relation with lattice defects and the effect of cold working on precipitation and grain boundary reaction in the aluminium alloys containing ll.2, 17.4, 28.3 and 40.8% zinc respectively were investigated by means of X-ray diffraction, hardness measurements and transmission electron microscopy. It was found that face-centered cubic transition precipitates were formed in granular shape in ll.2% or 17.4% zinc alloys and were plate-like in 28.3% zinc alloys. The plate-like transition precipitates were formed on {110} matrix planes, perhaps preferentially on the prismatic dislocation loops. The results are shown to be consistent with the hypothesis that in the quenched alloys precipitation occurs on prismatic dislocation loops that result from the condensation of quenched-in vacancies. In Al-28.3 and 40.8% Zn alloys, the grain boundary reaction is predominant at lower aging temperatures

On Precipitation Phenomena in Magnesium-Zinc Alloys

The ageing characteristics of magnesium-zinc alloys in the composition range from 3.2 to 19.0 wt.% zinc were studied at temperatures from 70° to 200°C mainly with X-ray diffraction methods and electron-microscopic observations with thin foils. The G.P. zones were confirmed to exist on the {1011} matrix planes. The transition phase on the {1010} matrix planes is MgZn´ indistinguishable from the hexagonal Laves phase MgZn₂. The effects of plastic deformation were examined with direct observations by thin foils. The formation of G.P. zones on the {1011} matrix plane was hindered by cold working after water quenching, while the rates of precipitation of the transition phase β´ and equilibrium phase β were accelerated

Incarcerated Amyand’s Hernia

A 76-year-old Japanese man was transferred to our hospital to undergo rehabilitation after traffic accident-related injuries. Seven days post-admission, he presented with abdominal pain and an 8-cm lump in the right inguinal region. He was diagnosed with an incarcerated inguinal hernia and underwent elective surgery the day after manual reduction. He had a normal vermiform appendix which was observed to have adhered to the right indirect hernia sac. An appendectomy and hernia repair using lightweight mesh were performed. We discuss the surgical management of this rare incarcerated Amyand’s hernia and the relevant literature

Uteluftsventilerad krypgrund, teori och praktik

Uteluftsventilerade krypgrunder är kända för att kunna drabbas av problem med hög relativ luftfuktighet inne i kryputrymmet. Förhållandena som uppstår kan då vara gynnsamma för biologisk påväxt vilket i sin tur kan ha en negativ inverkan på både konstruktionens hållfasthet och inomhusluftens kvalitet. Problem uppstår dels på grund av att krypgrunden förblir för kall sommartid och dels på grund av en hög fuktbelastning från underliggande mark. I denna rapport härleds nya teoretiska samband för att beskriva hur temperaturen vid blindbotten inne i krypgrunden beror av temperaturen inomhus, utomhus och vid grundbotten. Metoden kan användas för att uppskatta hur relativa luftfuktigheten varierar inne i kryputrymmet och hur denna påverkas av olika åtgärder. Forskningsarbetet har här riktat in sig på att undersöka effekten av ventilation kombinerat med värmetillförsel, och en framtagen regleralgoritm påvisar att värmetillförsel kan användas periodvis under kritiska perioder för att öka mängden fukt som ventilation kan föra ut ur krypgrunden.Outdoor air-ventilated crawls spaces are known to face problems caused by a high relative humidity inside the crawl space. The conditions then become favourable for different types of biological fouling. This in turn can have a negative impact on both the structural properties of building materials and the quality of the indoor air. Problems with high relative humidity are partly due to insufficient heating of the crawl space during the summer and partly due to a high moisture load from the ground below. In this report, new theoretical relations are derived that explain how the temperature beneath the floor structure is related to the temperature indoors, outdoors, and at the ground surface. The method can be used to estimate how the relative humidity varies inside the crawl space and how it can be affected by different measures. We have focused on measures based on combinations of controlled ventilation and heating, and developed a control algorithm which suggests that additional heating could be used periodically, during critical periods, to increase the amount of moisture that can be removed from the crawl space using ventilation

Clinical Significance of Peripheral Blood T Lymphocyte Subsets in Helicobacter pylori-Infected Patients

Background. Helicobacter pylori chronically colonizes gastric/duodenal mucosa and induces gastroduodenal disease and vigorous humoral and cellular immune responses. Methods. In order to clarify the immunological changes induced by this infection, we determined the percentage and, as indicated, ratios of the following cells in peripheral blood of 45 H. pylori-infected patients and 21 control subjects: CD4+ T cell, CD8+ T cells, T helper 1 cells (Th1), T helper 2 cells (Th2), CD4+CD25+ T cells, Foxp3+ regulatory T cells (Tregs), CD4/CD8 ratio, and Th1/Th2 ratio. Results. The percentage of CD8+ T cells was significantly lower in H. pylori-infected patients (mean ± SD; 18.0 ± 7.1%) compared to control subjects (mean ± SD; 23.2 ± 7.8%) (P < 0.05). The CD4/CD8 ratio was significantly higher in H. pylori-infected patients (mean ± SD; 3.1 ± 2.4) compared to control subjects (mean ± SD; 2.1 ± 1.0) (P < 0.05). The Th1/Th2 ratio was significantly lower in H. pylori-infected patients (mean ± SD; 10.0 ± 8.5) compared to control subjects (mean ± SD; 14.5 ± 9.0) (P < 0.05). The percentage of CD4+CD25+ T cells in H. pylori-infected patients (mean ± SD; 13.2 ± 6.2%) was significantly higher than that in control subjects (mean ± SD; 9.8 ± 3.4%) (P < 0.05). However, there was no significant difference in Tregs. Conclusion. Tregs did not decrease, but the activation of humoral immunity and Th2 polarization were observed in the peripheral blood of H. pylori-infected patients. In some cases, these changes may induce systemic autoimmune diseases

Metataxonomic Analysis of the Uterine Microbiota Associated with Low Fertility in Dairy Cows Using Endometrial Tissues Prior to First Artificial Insemination

The deterioration in reproductive performance in association with low fertility leads to significant economic losses on dairy farms. The uterine microbiota has begun to attract attention as a possible cause of unexplained low fertility. We analyzed the uterine microbiota associated with fertility by 16S rRNA gene amplicon sequencing in dairy cows. First, the alpha (Chao1 and Shannon) and beta (unweighted and weighted UniFrac) diversities of 69 cows at four dairy farms that had passed the voluntary waiting period before the first artificial insemination (AI) were analyzed with respect to factors including farm, housing style, feeding management, parity, and AI frequency to conception. Significant differences were observed in the farm, housing style, and feeding management, except parity and AI frequency to conception. The other diversity metrics did not show significant differences in the tested factors. Similar results were obtained for the predicted functional profile. Next, the microbial diversity analysis of 31 cows at a single farm using weighted UniFrac distance matrices revealed a correlation with AI frequency to conception but not with parity. In correlation with AI frequency to conception, the predicted function profile appeared to be slightly modified and a single bacterial taxon, Arcobacter, was detected. The bacterial associations related to fertility were estimated. Considering these, the uterine microbiota in dairy cows can be varied depending on the farm management practices and may become one of the measures for low fertility