Study of hardness and microstructure of Fe-C-Si-Mn-B hardfacing alloy

Iron based alloys are normally utilized for abrasive coatings to resist wear. Chromium added iron alloys are commonly chosen for hardfacing, which is one of the surface improvement methods. Such alloys are costly and give a moderate hardness to the deposits, due to the large addition of chromium. Fe-C-Si-Mn alloys show hardness up to 450VHN, without heat treatment, which is an established fact. In this work boron is added to Fe-C-Si-Mn welding alloys, deposits are made on low carbon steel substrates and resultant hardness is found to be an average of 650VHN, which is equivalent to some of the chromium containing ferrous alloys. Boron addition to Fe-C-Si-Mn alloy causes it to harden further, such that it can be utilized to combat wear. A few alloys are produced with the addition of boron (< 0.02Wt %) and tested for hardness and microstructure. Fe-C-Si-Mn-B alloys produced in the form welding electrodes can be utilized for hardfacing purposes with specific industrial applications. Micrographs reveal the presence of lower bainite and tempered martensite

Community and international nutrition: Vitamin A supplementation at birth delays pneumococcal colonization in South Indian infants

Nasopharyngeal colonization is a risk factor for pneumococcal disease, a leading cause of complications and death in infants. We assessed the impact of vitamin A supplementation in reducing pneumococcal colonization in infants from an area with endemic vitamin A deficiency. We recruited 464 2-mo-old infants from a rural area in South India. Infants were randomly assigned to receive two 7000-μg retinol equivalent doses of vitamin A (n = 239) or placebo (n = 225) orally at birth, and nasopharyngeal specimens were collected at ages 2, 4 and 6 mo. We studied the effect of vitamin A on culture-confirmed pneumococcal colonization and on the distribution of pneumococcal serotypes. Analyses were conducted by intention-to-treat. The risk of colonization among infants aged 4 mo who were not colonized by age 2 mo was significantly reduced in the vitamin A group compared with the placebo group [odds ratio 0.51 (0.28, 0.92), P = 0.02). The odds of colonization were 27% lower in the treatment group than in the placebo group [odds ratio 0.73 (0.48, 1.1), P = 0.13]. No differences were detected in the prevalence of invasive serotypes. The risk of colonization with penicillin-resistant isolates was 74% lower in the vitamin A group than in the placebo group at 2 mo of age. However, the prevalence of penicillin-resistant isolates was only 4%. Neonatal vitamin A supplementation may play a role in lowering morbidity rates associated with pneumococcal disease by delaying the age at which colonization occurs

Risk factors of chronic Kidney disease influencing cardiac calcification

We sought to determine the influence of risk factors of chronic kidney disease (CKD) on cardiac calcification. We studied the correlation between coronary artery calcium score (CACS) and the type and duration of dialysis as well as the presence of diabetes mellitus and hypertension. The relation between calcium score and mortality was also analyzed. Patients with CKD attending the outpatient department or admitted in our hospital were included. They were subjected to high-resolution computerized tomography of the thorax to determine their CACS. Serum levels of intact parathyroid hormone (iPTH), highly sensitive C-reactive protein (hCRP), homocysteine, calcium, phosphorus, and calcium × phosphorus product were measured. Out of the 50 patients studied, 39 were hypertensive (78%), 32 were diabetic (64.4%), 20 were on hemodialysis, and 13 were on continuous ambulatory peritoneal dialysis. The mean CACS was 388.6. Twenty-nine patients had high iPTH levels and 92.9% of them had calcium score >400 (P = 0.013). Twenty-eight patients had high hCRP and 85.7% of these patients had calcium score >400 (P = 0.048). Patients on dialysis for more than two years had higher calcium score >400 (P = 0.035). 43% of diabetics had calcium score >400 (P = 0.008). All the six patients who died had calcium score >400 (P = 0). There was statistically no significant association noted between hypertension, high calcium x phosphorus product, and high homocysteine levels, and high calcium score. Our study suggests that higher values of iPTH, hCRP, and longer duration on dialysis are associated with accelerated cardiac calcification. Calcification scores >400 are associated with increased mortality

Functional Antibody Activity Elicited by Fractional Doses of Haemophilus influenzae Type b Conjugate Vaccine (Polyribosylribitol Phosphate–Tetanus Toxoid Conjugate)

We evaluated the functional activities of antibodies, serum bactericidal activity (SBA), and immunoglobulin G (IgG) antibody avidity indices, using sodium thiocyanate (NaSCN) elution, elicited after vaccination with fractional doses of the Haemophilus influenzae type b conjugate (polyribosylribitol phosphate [PRP] conjugated to tetanus toxoid [PRP-T]) vaccine. A cohort of 600 infants from the Dominican Republic were randomized to receive one of three regimens of the PRP-T vaccine at ages 2, 4, and 6 months: full doses (10 μg of PRP antigen), one-half doses (5.0 μg), and one-third doses (3.3 μg) (J. Fernandez et al., Am. J. Trop. Med. Hyg. 62:485–490, 2000). Sixty serum samples, collected at age 7 months, with ≥2.0 μg of anti-PRP IgG per ml were randomly selected for avidity determinations. Geometric mean IgG concentrations were 13, 14, and 17 μg/ml for infants who received the full-dose (n = 19), one-half-dose (n = 19), and one-third-dose (n = 22) regimens, respectively. SBA geometric mean titers (1/dilution) were 85.0, 82.0, and 76.1 in sera from infants receiving the full-, one-half-, and one-third-dose regimens, respectively. Avidity indices (mean ± standard error weighted average of NaSCN molar concentration × serum dilution factor) were 71.9 ± 9.4, 123.6 ± 26.8, and 150.9 ± 24.9 for the full-, one-half-, and one-third-dose regimens, respectively. Upon comparison, the only significant difference (P = 0.024) found was a greater avidity index for sera from infants receiving the one-third-dose regimen than for sera from infants receiving the the full-dose regimen. We conclude that fractional doses elicit similar functional antibody activities in infants with ≥2 μg of anti-PRP IgG per ml, corresponding to 89, 90, and 97% of infants receiving three doses of either the full concentration or one-half or one-third of the labeled concentration, respectively. This approach offers an alternative strategy for the prevention of H. influenzae type b disease in countries with limited resources