Coconut-growing soils of Kerala: 1. Characteristics and classification

Coconut plantations are the major land use systems in Kerala state. The tropical hot humid climate and soils of the state are considered suitable for the palm, with the exception of highlands occurring 600 m above MSL. However, the productivity of coconut is abysmally low in the state with an average productivity of around 40 nuts per year per palm. To find out whether the highly weathered and leached low activity clay soils developed in tropical hot humid climate is responsible for the low yield, an assessment of soil qualities in the coconut-growing soils of the state was made. Six distinct regions of coconut cultivation in the state were identified and delineated based on the variability of agro-climate and soils, viz., Central and Eastern Palakkad, Northern Kerala, Central Kerala, Southern Kerala, Onattukara sandy plains and coastal sandy plains. Soil profiles were studied at representative sites in each region. Investigated morphological features and sampled horizon-wise for the analysis of physical and chemical properties of the soil. Coconut-growing soils of Kerala state are in general deep and well drained, clayey or sandy having good structure permitting rapid transmission of water. The soils of Palakkad, Southern Kerala and Coastal Sandy Plains have near neutral reaction whereas the extensive areas of laterite soils of Northern and Central Kerala and sandy soils of Onattukara were strongly acid and had high levels of KCl extractable aluminium. The acid soils also analysed for low levels of basic cations, potassium, calcium and magnesium. Soils from all regions except Palakkad have low CEC. Surface and sub-soils base status were extremely low for soils of Northern and Central Kerala and Onattukara sandy plain. The soils of Central and Eastern Palakkad were classified as Typic Haplustalfs, Northern Kerala as Plinthic Humults, Central Kerala as Typic Plinthustults, Southern Kerala as Rhodic Kandiustults and the soils of sandy plains as Ustipsamments, according to soil taxonomy

Case based measles surveillance in Pune: Evidence to guide current and future measles control and elimination efforts in India

Background: According to WHO estimates, 35% of global measles deaths in 2011 occurred in India. In 2013, India committed to a goal of measles elimination by 2020. Laboratory supported case based measles surveillance is an essential component of measles elimination strategies. Results from a case-based measles surveillance system in Pune district (November 2009 through December 2011) are reported here with wider implications for measles elimination efforts in India.Methods: Standard protocols were followed for case identification, investigation and classification. Suspected measles cases were confirmed through serology (IgM) or epidemiological linkage or clinical presentation. Data regarding age, sex, vaccination status were collected and annualized incidence rates for measles and rubella cases calculated.Results: Of the 1011 suspected measles cases reported to the surveillance system, 76% were confirmed measles, 6% were confirmed rubella, and 17% were non-measles, non-rubella cases. Of the confirmed measles cases, 95% were less than 15 years of age. Annual measles incidence rate was more than 250 per million persons and nearly half were associated with outbreaks. Thirty-nine per cent of the confirmed measles cases were vaccinated with one dose of measles vaccine (MCV1).Conclusion: Surveillance demonstrated high measles incidence and frequent outbreaks in Pune where MCV1 coverage in infants was above 90%. Results indicate that even high coverage with a single dose of measles vaccine was insufficient to provide population protection and prevent measles outbreaks. An effective measles and rubella surveillance system provides essential information to plan, implement and evaluate measles immunization strategies and monitor progress towards measles elimination

Mechanical properties of Ti-6Al-4V selectively laser melted parts with body-centred-cubic lattices of varying cell size

Significant weight savings in parts can be made through the use of additive manufacture (AM), a process which enables the construction of more complex geometries, such as functionally graded lattices, than can be achieved conventionally. The existing framework describing the mechanical properties of lattices places strong emphasis on one property, the relative density of the repeating cells, but there are other properties to consider if lattices are to be used effectively. In this work, we explore the effects of cell size and number of cells, attempting to construct more complete models for the mechanical performance of lattices. This was achieved by examining the modulus and ultimate tensile strength of latticed tensile specimens with a range of unit cell sizes and fixed relative density. Understanding how these mechanical properties depend upon the lattice design variables is crucial for the development of design tools, such as finite element methods, that deliver the best performance from AM latticed parts. We observed significant reductions in modulus and strength with increasing cell size, and these reductions cannot be explained by increasing strut porosity as has previously been suggested. We obtained power law relationships for the mechanical properties of the latticed specimens as a function of cell size, which are similar in form to the existing laws for the relative density dependence. These can be used to predict the properties of latticed column structures comprised of body-centred-cubic (BCC) cells, and may also be adapted for other part geometries. In addition, we propose a novel way to analyse the tensile modulus data, which considers a relative lattice cell size rather than an absolute size. This may lead to more general models for the mechanical properties of lattice structures, applicable to parts of varying size

Effect of Magnesium Addition on the Cell Structure of Foams Produced From Re-melted Aluminum Alloy Scrap

Closed-cell foams were produced from re-melted aluminum alloy scrap that contained 0.13 wt pct Mg magnesium in the as-received state and higher levels after adding 1, 2, or 5 wt pct Mg. The excess Mg gave rise to the fragmentation of long oxide filaments present in the scrap alloy into smaller filaments and improved its distribution and wetting by the Al matrix. Foaming the re-melted scrap alloy containing 1, 2, and 5 wt pct Mg excess showed stability and good expansion in comparison to the scrap alloy containing 0.13 wt pct Mg only, but the cells became non-equiaxed when the Mg concentration was high (≥2 wt pct excess) due to cell wall rupture during solidification. Compressibility and energy absorption behavior were studied for scrap alloy foams containing 1 wt pct Mg excess, which is the optimum level to obtain good expansion, stability, and uniform cell size. Foams with densities in the range of 0.2 to 0.4 g cm−1 produced by holding at the foaming temperature for different times were used for the investigation. A uniform cell structure led to flatter stress plateaus, higher energy absorption efficiencies, and reduced “knockdown” in strength compared with commercial foams made by gas bubbling. The mechanical performance found is comparable to that of commercial foams made by a similar method but the expected costs are lower

On the fatigue life enhancement due to periodic healing of a NiTi shape memory alloy

Fatigue failure in NiTi based shape memory alloys (SMAs) that are in the austenitic state is accelerated by the progressive accumulation of stress-induced martensite (SIM) under cyclic loading, even when the maximum stress of the fatigue cycle is well below that required for stress-induced martensitic transformation. Wagner et al. (2008) [1] have shown that periodic annealing of the fatigued specimens at temperatures well above the austenitic finish temperature, which they termed as ‘healing’, can enhance the fatigue life of the SMAs that are cyclically loaded in the austenitic state. In this paper, the optimum interval at which healing must be performed is investigated. Experimental results show that considerable improvement in the total life of the SMA component can be realized if the fatigued specimens are healed periodically right after 20% of their service life has lapsed. Healing later (at 40% and 60% of the fatigue life) does not lead to any significant improvement, indicating that irreversible damage has already set in. Real-time infrared thermography technique was used to study the thermal signatures during tensile and fatigue testing. Results show that it is possible to monitor the formation of SIM during cyclic loading using thermography.Agency for Science, Technology and Research (A*STAR)The work at the Nanyang Technological University was supported by the funding from Agency for Science, Technology, and Research (A*STAR) via the Structural Metals and Alloys Programme (No. A18B1b0061)

Pressure sensitive flow and constraint factor in amorphous materials below glass transition

International audienceThe constraint factor, C (given by the hardness-yield strength ratio H/Y in the fully plastic regime of indentation), in metallic glasses, is greater than three, a reflection of the sensitivity of their plastic flow to pressure. Furthermore, C increases with increasing temperature. In this work, we examine if this is true in amorphous polymers as well, through experiments on amorphous poly(methyl methacrylate) (PMMA). Uniaxial compression as well as spherical indentation tests were conducted in the 248-348 K range to construct H/Y versus indentation strain plots at each temperature and obtain the C-values. Results show that C increases with temperature in PMMA as well. Good correlation between the loss factors, measured using a dynamic mechanical analyzer, and C, suggest that the enhanced sensitivity to pressure is possibly due to beta-relaxation. We offer possible mechanistic reasons for the observed trends in amorphous materials in terms of relaxation processes