Development and Optimization of Tin/Flux Mixture for Direct Tinning and Interfacial Bonding in Aluminum/Steel Bimetallic Compound Casting.

Interfacial bonding highly affects the quality of bimetallic bearing materials, which primarily depend upon the surface quality of a solid metal substrate in liquid-solid compound casting. In many cases, an intermediate thin metallic layer is deposited on the solid substrate before depositing the liquid metal, which improves the interfacial bonding of the opposing materials. The present work aims to develop and optimize the tinning process of a solid carbon steel substrate after incorporating flux constituents with the tin powder. Five ratios of tin-to-flux-i.e., 1:1, 1:5, 1:10, 1:15, and 1:20-were used for tinning process of carbon steel solid substrate. Furthermore, the effect of volume ratios of liquid Al-based bearing alloy to solid steel substrate were also varied-i.e., 5:1, 6.5:1 and 8.5:1-to optimize the microstructural and mechanical performance, which were evaluated by interfacial microstructural investigation, bonding area determination, hardness and interfacial strength measurements. It was found that a tin-to-flux ratio of 1:10 offered the optimum performance in AlSn12Si4Cu1/steel bimetallic materials, showing a homogenous and continuous interfacial layer structure, while tinned steels using other percentages showed discontinuous and thin layers, as in 1:5 and 1:15, respectively. Furthermore, bimetallic interfacial bonding area and hardness increased by increasing the volume ratio of liquid Al alloy to solid steel substrate. A complete interface bonding area was achieved by using the volume ratio of liquid Al alloy to solid steel substrate of ≥8.5.

School mental health screening: a model for developing countries.

Using the experience derived from a screening programme of all school-going children in the Al Ain District, United Arab Emirates, this article reports on a cost-effective model that can be used in other developing countries. The need for training child health and school professionals in identifying mental and developmental disorders is discussed.

Conception rates and assisted reproduction in subfertility due to unilateral cryptorchidism.

During 774 spontaneous cycles and 87 cycles of assisted reproduction, the conception rates were evaluated in 48 infertile couples in whom unilateral cryptorchidism was the causal factor. In spite of adjuvant therapy of the male partner, the spontaneous conception rate was very low (1% per cycle). Intra-uterine insemination (IUI) and conventional in vitro fertilization (IVF) resulted in similar success rates of 6.1 and 8.7% per cycle/attempt respectively. After intra-cyto-plasmic sperm injection (ICSI), 46.7% pregnancies were obtained per attempt, and sperm requirements for the latter treatment to be successful were lower than for IUI. It is concluded that subfertility in men with unilateral cryptorchidism is severe, conventional IVF has little advantage, but ICSI is highly successful.

Inhibin and steroid response to testicular stimulation with pure FSH (Metrodin) in infertile men with unilateral cryptorchidism.

Static measurements of immunoreactive inhibin have proven of little relevance in the diagnosis of testicular disorders. Dynamic evaluation of the inhibin secretory reserve might detect a specific Sertoli cell defect in a subgroup of infertile men. We compared the response of inhibin and steroids to an intravenous injection of pure FSH (Metrodin, Serono, 300 IU) in 13 infertile men with unilateral cryptorchidism to that in eight normal fertile men. Blood was aspirated before, 24, 48, and 72 h after the FSH injection. Two subgroups of patients with unilateral cryptorchidism were detected: those who responded by secreting inhibin in a pattern similar to normal men (seven patients), and those who responded poorly or not at all (six patients). The presumed cause of this difference is a defect of Sertoli cell reserve function due to a combination of insults to the testes, and not to cryptorchidism itself. The difference in response to FSH cannot be predicted from semen analysis nor from static hormone measurements. Overall, inhibin levels correlated significantly with the serum concentrations of FSH (r = -0.36, P < 0.05), testosterone (r = 0.37, P < 0.05), and 17-hydroxyprogesterone (r = 0.66, P < 0.001). It is concluded that, in infertile men with unilateral cryptorchidism, Stimulation of Sertoli cells by FSH can identify a subgroup of patients with Sertoli cell malfunction involving inhibin synthesis.