Wear resistance of cast graphitic aluminium alloys

Wear rates of several cast aluminium base alloys have been measured for lubricated rubbing against a rotating hardened steel disk. Wear rates of cast graphitic aluminium-silicon-nickel alloys were lower than those of pure Al, Al-Si and Al-Si-Ni alloys especially above pressures of 0.02 kg/mm2. The high wear resistance is attributed to the presence of graphite particles in the matrix which act as a solid lubricant. Additions of nickel alone to Al-Si alloys decrease the wear resistance. Graphitic aluminium-silicon-nickel alloys containing above 2% graphite can be mated unlubricated against the rotating steel disk after a one minute lubricated run-in period. Graphite particles may be potentially suitable to replace part of all of the tin in aluminium-tin bearing alloys.

Correlación entre la personalidad y los factores de la Teoría del Comportamiento Planeado (TCP) en adolescentes escolarizados de 11-19 años del Caribe Colombiano

The increasing rate of pregnancies in teenagers and the high incident of the infections of sexual transmission (HIV/ AIDS, for example), these are health related issues (and especially the sexual and reproductive health), which have received great attention on the part of investigators and of the public opinion in general. Recently, there has been evidenced that teenagers carry out very easily risk sexual behaviors, and those who have not presented the above mentioned behaviors also show high levels of intention to carry out them. There is the hypothesis that besides cognitive variables such as attitudes, subjective norms, perceived behavioral control and intention, the personality of the young persons is an aspect that plays an important paper in their sexual and reproductive health. Significant correlations were found between the variales of the TPB and the personality traits; the results suggest that the direction of these correlations is associated with the specific type of behavior or situation that is assessed. Keywords: personality, theory of planned behavior, adolescents, reproductive sexuality.

Behaviour of ultrasonic velocities in amorphous Se90Ge10 and Se85Ge15 alloys near their glass transition

Precise measurements of 10 MHz frequency longitudinal and shear wave velocities are reported in amorphous SeGe alloys near their glass transition temperature T g . There is a sharp decrease of the velocities near T g , but the reduction in velocities appears smaller than expected.

Effect of microstructure and mechanical properties on the seizure resistance of cast aluminium alloys

Seizure resistance of several cast aluminium base alloys has been examined using a standard Hohman Wear Tester. Disks of aluminium base alloys were run against a standard aluminium 12% silicon base alloy. The seizure resistance of the alloys (as measured by the lowest bearing parameter reached before seizure) increased with hardness, yield and tensile strength. In Al-Si-Ni alloys where silicon and nickel have little solid solubility in α-aluminium and Si and Ni Al3 hard phases are formed, the minimum bearing parameter decreased with the parameter V (The product of vol. % of hard phases in the disk and the shoe). Apparently the silicon and NiAl3 particles provided discontinuities in the matrix and reduced the probability (1 − V) of the α-aluminium phase in the disk coming into contact with the α-aluminium phase in the shoe. The copper and magnesium containing Al-Si-Ni alloys with lesser volumes of hard phases exhibit considerably better seizure resistance indicating that a slight increase in the solute content or the hardness of the primary α-phase leads to a considerable increase in seizure resistance. Deformation during wear and seizure leads to fragmentation of the original hard particles into considerably smaller particles uniformly dispersed in the deformed α-aluminium matrix.

Wear resistance of cast graphitic aluminium alloys

Wear rates of several cast aluminium base alloys have been measured for lubricated rubbing against a rotating hardened steel disk. Wear rates of cast graphitic aluminium-silicon-nickel alloys were lower than those of pure Al, Al-Si and Al-Si-Ni alloys especially above pressures of 0.02 kg/mm2. The high wear resistance is attributed to the presence of graphite particles in the matrix which act as a solid lubricant. Additions of nickel alone to Al-Si alloys decrease the wear resistance. Graphitic aluminium-silicon-nickel alloys containing above 2% graphite can be mated unlubricated against the rotating steel disk after a one minute lubricated run-in period. Graphite particles may be potentially suitable to replace part of all of the tin in aluminium-tin bearing alloys.

Graduate School for Jewish Social Work (New York, N.Y.) records, undated, 1925-1950.

The collection consists of records of the administration of the school; records of a Lower East Side documentation project, including photographs; and letters from a project on the Men's and Women's Department of Der Tag. The collection is arranged in four series: Series I. Administration, Series II. Committee on Research, Series III. Der Tag Project, and Series IV. East Side Project.

Grand Street Boys' Association (New York, N.Y.) Records, undated, 1907-1968, bulk 1940-2000.

The Grand Street Boys' Association began in 1916 as a reunion of men who had grown up on or near Grand Street in the Lower East Side neighborhood of Manhattan and quickly grew into an active club, open to all men (and eventually women) regardless of religion, ethnicity, or social class. The Association promoted welfare projects, acts of fellowship and tolerance, scholarships, youth employment, war efforts, and the elimination of discrimination in sports, among other projects. The collection documents the activities of the Association, as well as the Grand Street Boys' Foundation, its financial arm established in 1945, and its Hobbycraft Program, a charitable program tasked with collecting and redistributing donated items to charitable and nonprofit organizations. Materials include administrative records, financial records, correspondence, minutes, membership records, newsletters, yearbooks, artifacts, speeches, and photographs relating to both the New York Grand Street Boys' Association and the Association's Grand Street House in England. Series I, comprising the majority of the collection, contains the records of the Grand Street Boys' Association. In it are extensive membership records, meeting minutes, annual yearbooks, financial records, administrative material, newsletters, and artifacts. Series II documents the Grand Street Boys' Foundation and contains administrative records and financial records. Some overlap of material will be found in Series I and II such as material pertaining to the relationship between the Association and Foundation. Series III consists of photographs documenting both the Association and Foundation. The photographs show members and highlight the activities of the Grand Street Boys.

Congregation Shearith Israel (New York, N.Y.) records, undated, 1755-1996.

Contains published and manuscript material relating to the activities and administration of the congregation and its subsidiary organizations including reports and weekly bulletins, early financial records and lists of those honored at religious services, copies of resolutions and forms of service and prayers for various occasions in manuscript form. Contains also material relating to the cemetery photographs, the Hebra Hased Va-Amet (the congregational burial society) and to later clergy in the congregation, Henry Pereira Mendes, David de Sola Pool and Louis Coleman Gerstein including published copies of their sermons.

Board of Jewish Education (New York, N.Y.) records, undated, ca. 1920-ca. 1989.

Collection includes promotional material such as posters and pamphlets, surveys conducted by the BJE, and press releases. Also includes numerous publications, the majority being bulletins, newsletters, educational material, and bibliographies.

Plan Kryvorizʹkoĭ okrugi, Shyrokivsʹkogo raĭonu, Sverdlovsʻkoĭ silʻrady na uchastok zemli zemelʹnoï gromady vys. U 1 (Voroshilosʻkyĭ)z dorizannym do nʻogo uchaskom zemli Kolfonda Y. 52oskolfonda Nº 35 otgranichennogo v pori︠a︡dke ustroĭstva kolonizat︠s︡ionnogo fonda

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Plan otvoda zemli kollektiva "Poltavt︠s︡y" Krivorogskogo okruga Sofievskogo raĭona ploshchadiʻ︠u︡ 182 desi︠a︡tiny

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Plan poselka "Poltavt︠s︡y"

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Plan otvoda zemli kollektiva "Poltavt︠s︡y" Krivorogskogo okruga Sofievskogo raĭona ploshchadiʻ︠u︡ 182 desi︠a︡tiny

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Cadmium stress alters the redox reaction and hormone balance in oilseed rape (Brassica napus L.) leaves

In order to understand the physiological response of oilseed rape (Brassica napus L.) leaves to cadmium (Cd) stress and exploit the physiological mechanisms involved in Cd tolerance, macro-mineral and chlorophyll concentrations, reactive oxygen species (ROS) accumulation, activities of enzymatic antioxidants, nonenzymatic compounds metabolism, endogenous hormonal changes, and balance in leaves of oilseed rape exposed to 0, 100, or 200 μM CdSO4 were investigated. The results showed that under Cd exposure, Cd concentrations in the leaves continually increased while macro-minerals and chlorophyll concentrations decreased significantly. Meanwhile, with increased Cd stress, superoxide anion (O 2 • − ) production rate and hydrogen peroxide (H2O2) concentrations in the leaves increased significantly, which caused malondialdehyde (MDA) accumulation and oxidative stress. For scavenging excess accumulated ROS and alleviating oxidative injury in the leaves, the activity of enzymatic antioxidants, such as superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), was increased significantly at certain stress levels. However, with increased Cd stress, the antioxidant enzyme activities all showed a trend towards reduction. The nonenzymatic antioxidative compounds, such as proline and total soluble sugars, accumulated continuously with increased Cd stress to play a long-term role in scavenging ROS. In addition, ABA levels also increased continuously with Cd stress while ZR decreased and the ABA/ZR ratio increased, which might also be providing a protective role against Cd toxicity.

Ultrasonic velocities and thermal expansion coefficients of amorphous Se80Te20 and Se90Te10 alloys near glass transitions

Precise measurements of the ultrasonic velocities and thermal expansivities of amorphous Se80Te20 and Se90Te10 alloys are reported near the glass transition. The samples are produced by liquid quenching. The longitudinal and transverse velocities are measured at 10 MHz frequency using the McSkimin pulse superposition technique. The thermal expansivities,agr, are measured using a three-terminal capacitance bridge. Theagr-values show a sharp maximum near the glass transition temperature,T g. The ultrasonic velocities also show a large temperature derivative, dV/dT nearT g. The data are discussed in terms of existing theories of the glass transition. The continuous change inagr shows that the glass transition is not a first-order transition, as suggested by some theories. The samples are found to be deformed by small loads nearT g. The ultrasonic velocities and dV/dT have contributions arising from this deformation.