Utjecaj sastava zaštitnog plina pri MIG postupku zavarivanja na mehanička svojstva niskougljičnih čelika

The present study is focused on the mechanical properties of the deposited material which was extracted from welded region. This study explains the effect of the shielding gas composition on tensile behavior, R = - 1 fatigue response and various tempe-rature impact test results of MIG welded low carbon steels. In tensile tests, the stre-ngth values are increased with increase of CO2 content, whereas the ductility is decreased. In the fatigue tests, the fatigue strength and the number of cycles to failure enhanced as the content of CO2 increased. However, the impact toughness of the filler material is seriously influenced by the content of the shielding gas. An increase in CO2 content caused significant decrease in toughness values at all temperatures.Ovaj rad se usredotočio na mehanička svojstva dodatnog materijala uzetog iz zavarenog područja. Rad objašnjava utjecaj sastava zaštitnog plina na vlačnost, R = -1 zamor i rezultate ispitivanja žilavosti na raznim temperaturama niskougljičnih čelika zavarenih metodom MIG. U testovima za ispitivanje vlačne čvrstoće vrijednosti čvrstoće su povećane kao rezultat povećanog sadržaja CO2, a plastičnost je smanjena. U testovima za ispitivanje zamora povećala se dinamička čvrstoća kao i broj ciklusa prije pucanja zajedno s povećanom količinom CO2. Međutim, žilavost materijala za dodavanje jako ovisi o zaštitnom plinu. Povećanje količine CO2 značajno smanjuje žilavost na svim temperaturama

Utjecaj TIG zavarivanja na mikrostrukturu i mehanička svojstva sučeljeno zavarenog nelegiranog titana

Microstructures, properties and technical parameters of welding specimen of 3 mm thick sheets of commercially pure titanium have been studied. The results indicate that the TIG welding process is suitable for commercially pure titanium, full penetration and the welding seam without defects can be obtained. The tensile, bending and hardness properties of the joints are corresponding to matrix structure. The mechanical properties of the three welded joints are similar to each other and comparable to those of the base material.U radu su prikazani rezultati ispitivanja mikrostrukture, mehaničkih svojstava i tehnički parametri zavarivanja limova debljine 3 mm iz titana komercijalne čistoće. Rezultati su pokazali da je TIG postupak zavarivanja pogodan za zavarivanje komercijalno čistog titana, te da se može postići potpuna penetracija i zavareni spoj bez defekata. Svojstva dobivena razvlačenjem i savijanjem kao i tvrdoća odgovaraju svojstvima osnovnog materijala

Turkish version of impact on family scale: a study of reliability and validity

<p>Abstract</p> <p>Background</p> <p>Although there is a considerably high prevalence of developmental disorders in Turkey there are not many assessment tools related to evaluating the impact of these children on their family. The aim of this study was to determine the validity and reliability of the Turkish version of the Impact on Family Scale (IPFAM), a health related quality of life measurement to be utilized in clinical trials, health care services, research and evaluation.</p> <p>Methods</p> <p>Caregivers of 85 children with developmental disabilities answered the questionnaire and 65 of them answered it twice with a one week interval. The reliability of the measurement was assessed by Cronbach's alpha coefficient, and with intraclass correlation coefficient (ICC) for test-retest reliability. Construct validity was assessed by calculating the correlation between total impact score of IPFAM, WeeFIM and the physiotherapists' evaluation via Visual Analogue Scale (VAS) to determine the child's disability.</p> <p>Results</p> <p>Test-retest reliability was found to be ICC = 0.953 for total impact, 0.843 for financial support, 0.940 for general impact, 0.871 for disruption of social relations and 0.787 for coping. Internal consistency was tested using Cronbach's alpha and was found to be 0.902 for total impact of IPFAM. For construct validity the correlation between total impact score of IPFAM and WeeFIM was r = -0,532 (p < 0.001) and the correlation between total impact score of IPFAM and the physiotherapist's evaluation was r = 0.519 (p < 0.001).</p> <p>Conclusion</p> <p>The Turkish version of IPFAM was found to be a reliable and valid instrument for assessing the impact of developmental disorders of the child on the family.</p

Investigation of Changes in Mechanical Properties and Microstructures of Mild Steel Joint by Oxy-Hydrogen Welding

In this paper, in order to see weldability behaviour of mild steels joint by the oxy-hydrogen welding technique, an investigation of changes in mechanical properties and microstructures of mild steel is carried out. The specimens with 1.5 mm thickness and 125 mm length are welded by using both the oxyhydrogen and oxy-acetylene gases. Microstructural analysis is carried out on the cross sectional area of the welding zone in order to compare the changes in weld metals and the heat affected zones in terms of the welding gases. Experimental results of the tensile strength and microhardness obtained with mechanical tests show that samples welded with oxy-acetylene exhibited 10% higher yield strength than that of the samples welded with oxy-hydrogen. However, the oxy-hydrogen welding technique can be used as an alternative to the oxy-acetylene welding, since it has advantageous of being clean and economic.С целью выяснения качества сварного шва на малоуглеродистой стали, полученного водород-кислородной сваркой, проведено исследование изменений механических свойств и микроструктуры данного типа стали. Образцы толщиной 1,5 мм и длиной 125 мм сваривались как водород-кислородной, так и ацетиленокислородной сваркой. Был проведён микроструктурный анализ поперечного сечения зоны сварки с целью сравнения изменений в металле шва и зоне термического влияния в зависимости от сварочного газа. Экспериментальные результаты по пределу прочности при растяжении и микротвёрдости, полученные при механических испытаниях, показали, что образцы, сваренные ацетиленокислородной сваркой, имеют прочность при растяжении на 10% выше, чем водород-кислородной. Однако водород-кислородная сварка может быть использована как альтернатива ацетиленокислородной сварке, так как она имеет преимущества по чистоте и экономичности.З метою з’ясування якости зварюваного шва на маловуглецевій сталі, виробленого водневокисневим зварюванням, виконано дослідження змін механічних властивостей і мікроструктури даного типу сталі. Зразки товщиною у 1,5 мм та довжиною у 125 мм зварювалися як водневокисневим, так і ацетиленокисневим зварюванням. Виконано мікроструктурну аналізу поперечного перерізу зони зварювання з метою порівняння змін у металі шва та зоні термічного впливу в залежності від зварювального газу. Експериментальні результати стосовно границі міцности при розтягу та мікротвердости, одержані під час механічних випробувань, показали, що зразки, зварені ацетиленокисневим зварюванням, мають міцність при розтягу, на 10% вищу, ніж зварені водневокисневою газовою сумішшю. Однак водневокисневе зварювання може бути використано як альтернатива ацетиленокисневому зварюванню завдяки його перевазі за чистотою та економічністю

Communication Research

Contains reports on seven research projects.Rockefeller FoundationCarnegie Foundatio

Communication Research

Contains reports on five research projects.Rand Corporatio

Communication Research

Contains reports on nine research projects.Bell Telephone Laboratories, Incorporate

Novel roles for class II Phosphoinositide 3-Kinase C2 beta in signalling pathways involved in prostate cancer cell invasion

Phosphoinositide 3-kinases (PI3Ks) regulate several cellular functions such as proliferation, growth, survival and migration. The eight PI3K isoforms are grouped into three classes and the three enzymes belonging to the class II subfamily (PI3K-C2a, ß and ?) are the least investigated amongst all PI3Ks. Interest on these isoforms has been recently fuelled by the identification of specific physiological roles for class II PI3Ks and by accumulating evidence indicating their involvement in human diseases. While it is now established that these isoforms can regulate distinct cellular functions compared to other PI3Ks, there is still a limited understanding of the signalling pathways that can be specifically regulated by class II PI3Ks. Here we show that PI3K-C2ß regulates mitogen-activated protein kinase kinase (MEK1/2) and extracellular signal-regulated kinase (ERK1/2) activation in prostate cancer (PCa) cells. We further demonstrate that MEK/ERK and PI3K-C2ß are required for PCa cell invasion but not proliferation. In addition we show that PI3K-C2ß but not MEK/ERK regulates PCa cell migration as well as expression of the transcription factor Slug. These data identify novel signalling pathways specifically regulated by PI3K-C2ß and they further identify this enzyme as a key regulator of PCa cell migration and invasion