Influence of austenitising temperature on the formation of strain induced martensite in austempered ductile iron

The present work was taken up to study the influence of austenitising temperature on the formation of strain-induced martensite in austempered ductile iron. Ductile iron containing 1.5 wt.% nickel, 0.3 wt.% molybdenum and 0.5 wt.% copper was subjected to austempering treatments which consisted of three austenitising temperatures, namely 850, 900 and 950 °C, and three austempering temperatures, namely 300, 350 and 400 °C. Tensile tests were carried out under all the heat-treatment conditions and strain-hardening behaviour was studied by applying Hollomon equation. Microstructures were studied by optical microscopy and X-ray diffraction. It was found that increasing austenitising temperature increased the tendency for the formation of strain-induced martensite at all the austempering temperatures.     

Pristine, adherent ultrathin gold nanowires on substrates and between pre-defined contacts via a wet chemical route

We demonstrate a simple strategy of obtaining clean, ultrathin single crystal Au nanowires on substrates and interconnecting pre-defined contacts with an insight into the growth mechanism. The pristine nature enables electron transport measurement through such ultrathin wires and opens up possibilities of exploring its properties for a wide range of applications.     

Comparison of swab transport media for recovery of Listeria monocytogenes from environmental samples

Environmental monitoring is recognized as an important strategy for controlling Listeria monocytogenes in food processing facilities. Samples are taken by swabbing environmental surfaces, and the swabs are immersed in a medium for transport to the laboratory. In this study, buffered peptone water (BPW), Dey-Engley neutralizing broth (DE), neutralizing buffer (NB), Letheen broth (LE), and newly described MCC buffer (MCC) were evaluated as transport media for recovery of sanitizer-stressed L. monocytogenes from inoculated swabs. After storage at 4°C, the media performed similarly, but at 25°C relative recovery efficiency from the inoculated sponges was DE > LE > BPW > MCC > NB. Recoveries from stainless steel surfaces followed similar trends. MCC, DE, and NB were compared for L. monocytogenes recovery in the presence of Escherichia coli, Enterococcus faecalis, Lactobacillus plantarum, Pseudomonas fluorescens, and Listeria innocua. After 4°C storage, all population levels changed little; after 25°C storage, DE allowed the best growth of L. monocytogenes regardless of other species present. MCC, DE, and NB performed similarly for recovery of L. monocytogenes from an artificial milk biofilm and for recovery of Listeria spp. from swabs obtained from a meat processing facility. Transport medium formulation, time and temperature of swab storage, and coexistence of other species affect recovery of sanitizer-stressed L. monocytogenes from environmental swabs. The study confirms the need to maintain 4°C storage conditions during swab transport.     

Development of a process for shelf stable dairy dessert dalia and its physico-chemical properties

Dalia, is a traditional dairy food of Indian sub-continent. It is consumed as dessert by cooking cracked wheat (dalia grains) in milk along with addition of sugar. It is used as a breakfast food especially for growing children and also for old age people. It has a poor shelf life of 1–2 days. In order to enhance its shelf life, dalia was processed in tin-free steel cans at 121.1 °C in a rotary over pressure retort. Process lethality (F_o) was found to vary from 3.90 to 8.22 min for different formulations. The average composition of retort sterilized dalia dessert comprised of 29.60 g/100 g total solids (TS), 3.56 g/100 g protein, 0.84 g/100 g ash and 21.54 g/100 g total carbohydrates including 2.88 g/100 g amylose. The product had a short lag period for the heating curve, j_h (0.40–0.85), small heating rate index, f_h (3.2–5.5 min) and a short lag factor for the cooling curve, j_c (0.91–1.10) implying essentially convective heating regime. The process time (B) was 10.20–15.78 min for F_o value of 3.90–8.22 min, whereas the cook value (C_g) was 28.95–54.03 min. F_o value of 4.15 min and nisin 376 IU/g yielded a product that was both safe and wholesome for 72 days at 37 °C.     

Studies on use of Enteromorpha in snack food

Seaweeds, also known as sea vegetables, are of nutritional interest, as they are rich in vitamins, minerals and dietary fiber. Enteromorpha compressa (Linnaeus), green seaweed (chlorophyta), which is a rich source of iron and dietary fibre was used as an ingredient in the preparation of Pakoda, a common traditional snack food in India. Pakoda samples showed increases in ash, protein and total dietary fibre contents with increase in Enteromorpha level, accompanied by a nearly fivefold increase in iron content (26.4–126 mg/100 g) and fourfold increase in calcium content (30.1–124 mg/100 g). Bioavailability of iron in Enteromorpha, and Pakoda containing 7.5% of Enteromorpha, did not show any difference (55–56%) at pH 7.5 (intestinal condition). But, at pH 1.35 (gastric condition) the bioavailability of iron in Pakoda containing Enteromorpha was found to be slightly higher (27.1%) than that in Enteromorpha. Reducing power (155–222 μg/g) increased as the Enteromorpha level increased from 0% to 15%. But the addition of Enteromorpha was found to decrease free radical-scavenging activity and the total phenol content. Pakoda containing up to 7.5% of Enteromorpha was found to have a sensory quality comparable with that of Pakoda without Enteromorpha.     

Coexistence of migraine and idiopathic intracranial hypertension without papilledema

Eighty-five patients with refractory transformed migraine type of chronic daily headache (CDH) had spinal tap as a part of diagnostic work-up. Twelve had increased intracranial pressure without papilledema, transient visual obscurations, or visual field defects. The headache profile of these 12 patients was not different from that of transformed migraine type of CDH. Acute headache exacerbations responded to specific antimigraine agents such as ergotamine, dihydroergotamine (DHE), and sumatriptan, whereas prophylactic antimigraine medications were only partially helpful. Addition of agents such as acetazolamide and furosemide, after the diagnosis of increased intracranial pressure, resulted in better control of symptoms. These observations suggest a link between migraine and idiopathic intracranial hypertension that needs further research. In refractory CDH with migrainous features, a spinal tap to exclude coexistent idiopathic intracranial hypertension without papilledema may be indicated.     

Conformation, protein-carbohydrate interactions and a novel subunit association in the refined structure of peanut lectin-lactose complex

The structure of the complex of the tetrameric peanut lectin with lactose has been refined to an R-value of 16.4% using 2.25 angstroms resolution X-ray diffraction data. The subunit conformation in the structure is similar to that in other legume lectins except in the loops. It has been shown that in the tertiary structure of legume lectins, the short five-stranded sheet plays a major role in connecting the larger flat six-stranded and curved seven-stranded sheets. Furthermore, the loops that connect the strands at the two ends of the seven-stranded sheet curve toward and interact with each other to produce a second hydrophobic core in addition to the one between the two large sheets. The protein-lactose interactions involve the invariant features observed in other legume lectins in addition to those characteristic of peanut lectin. The "open" quaternary association in peanut lectin is stabilised by hydrophobic, hydrogen-bonded and water-mediated interactions. Contrary to the earlier belief, the structure of peanut lectin demonstrates that the variability in quaternary association in legume lectins, despite all of them having nearly the same tertiary structure, is not necessarily caused by covalently bound carbohydrate. An attempt has been made to provide a structural rationale for this variability, on the basis of buried surface areas during dimerisation. A total of 45 water molecules remain invariant when the hydration shells of the four subunits are compared. A majority of them appear to be involved in stabilising loops.