Kaolin shear thickening fluid reinforced UHMWPE composites for protective clothing

This study reports the designing and reinforcing of impact resistant textile composites using kaolin based shear thickening colloidal dispersions as the filler material. The reinforced fabric is targeted for the chest protection of cricketers. A shear thickening fluid (STF) has been prepared using kaolin and glycerol, at kaolin volume fractions of 34% and 38%. A combination of mixing techniques including mechanical blending and ultra-sonication are used to prepare the colloidal dispersions. Ultra high molecular weight polyethylene (UHMWPE) woven fabric structures are reinforced with the STF. The fabric coated with STF are then measured for their flexibility, and impact resistance using Shirley stiffness tester and a series of modified drop tower tests respectively. Kaolin STF at 38% volume fraction shows best results in impregnated fabric samples. STF reinforced fabrics provide better impact resistance with improved moisture absorption and flexibility in comparison to the conventional chest guard material

Effectiveness of Early Warning Dissemination A Case Study on Tsunami Early Warning in Sri Lanka

Media & Communication technology has an important role to play in disastercommunication by educating people about natural disasters. As the whole world isentertaining the results of new communication technology, the attention of the disastermanagement experts has driven towards, using this new technology in disastercommunication. Accurate and timely information about natural disasters were needednot only for the people at risk ,but also for the government officials, community leaders,donor agencies and media, to take necessary steps to reduce risk as well as to speedrecovery. Effective risk reduction involves mitigation measures in hazards prone areas.It may also involve overcoming the socioeconomic, institutional and political barriers tothe adoption of effective risk reduction strategies and measures in developing countries.Therefore, effective disaster communication is very essential for the sustainable disasterrisk reduction. As Sri Lanka is a country accustomed to disasters, this is an importantfact. In 2004, tsunami hit Sri Lanka without any prior warning. But in April, 2012 theDisaster Management Center, official institution involved in Early Warningdissemination, was equipped with new technology. Therefore, this paper is aiming atinvestigating the effectiveness of the present Early Warning dissemination mechanismin Sri Lanka. The study, being basically quantitative, employed descriptive statistics foranalytical purpose using the primary data collected in one GN Division in Galle district.The study revealed that the strongest method of Early Warning dissemination is theSiren. The community was already aware on the way they should behave on such anevent. The trust worthiness about the Early Warning message seemed to have a linkwith the authority of the party who disseminate the message. Furthermore, the electronicmedia seems to have a good reputation among the public regarding there work in EarlyWarning dissemination.Key words: Disaster communication, Early warning, Disaster risk reduction, Naturaldisaste

Model multiple antigenic and homopolymeric peptides from non-repetitive sequences of malaria merozoite proteins elicit biologically irrelevant antibodies

AbstractThree model peptides containing B-epitopes from conserved, non-repetitive regions of the merozoite surface antigens, MSA2 and MSA1, and the erythrocyte binding protein EBP of Plasmodium falciparum were synthesised. The peptides incorporated GPG spacers and C residues at the N and C termini, and were polymerised by oxidation to form cystine bridges. Multiple copies of essentially the same peptide sequences were also synthesised on a branching lysyl matrix to form a tetrameric multiple antigen peptide. Rabbits were immunised with the polymerised and multiple antigen peptides, in alum followed by Freund’s adjuvant, and the antibody responses examined by IFA and ELISA. Reproducible antibody responses were obtained against the MSA1 and EBP but not MSA2 peptides. IgG antibody levels detected by ELISA after three injections of antigen in alum, increased significantly after further immunisation in Freund’s adjuvant. IgG levels were largely maintained for at least 23 weeks after the final immunisation. IgM antibodies, generally detectable only after immunisation in Freund’s adjuvant, were absent 23 weeks later. Antibody titres against the native protein on fixed parasites, assayed by IFA, were three to five orders of magnitude lower than the corresponding ELISA titres against the peptides. Antibody-dependent inhibition of P. falciparum growth in vitro could not be demonstrated with the immune rabbit sera. The MSA1 and EBP peptides elicited cross-reactive antibodies. The results suggest that the selected non-repetitive sequences are conformationally constrained in the native proteins and only a small proportion of the anti-peptide antibodies bind to the native proteins. The significance of the findings for the development of peptide vaccines and the use of peptides in immunoassays is discussed

High intensity impulsive loading by explosively accelerated granular matter

© 2017 Elsevier Ltd The mechanism by which a spherical shell of granular matter is accelerated by an internal explosion together with its subsequent loading of a high ductility, edge clamped steel plate are investigated by a combination of instrumented experimentation and particle-based simulation. By using a large spherical explosive charge to drive the expansion of a water saturated synthetic sand shell, it has been possible to create sand front impact speeds with a test plate that exceeded 1200 m/s. Direct observations of the evolution of the sand front were made using a pair of high speed video cameras, and revealed rapid initial acceleration of the sand accompanied by the formation of locally faster sand spikes, followed by deceleration. The pressure evolution and specific impulse during particle impact were measured using the Kolsky bar. A discrete particle-based numerical simulation method implemented in the IMPETUS Afea code was then used to simulate the pressure and impulse applied to the Kolsky bar and to model dynamic deformation of the plate and its support structure. The simulation analyzed the interactions between the explosively accelerated high explosive, air, and sand particles and the shock fronts that propagated though each interface after detonation. The impulse applied to the test plate and its support structure were well reproduced by the simulation. The simulations also revealed significant dispersion of the sand, with some sand particles attaining radial velocities that were almost 50% higher than that of the main front. They also identified the presence of an experimentally unobservable instability at the energetic material-wet sand interface. The deceleration of the sand with distance of propagation was found to be the result of momentum transferring collisions with the background air, resulting in the formation of a strong air shock ahead of the sand front. This processes resulted in the eventual transfer of all the sand momentum to the air and significantly influenced the dynamically changing topology of the sand-air interface. While the differential acceleration of the sand particles to form a dispersed front, and their deceleration by air drag were well modeled, the topology of the sand instabilities at the sand front-air interface were not resolved by the simulations.This research was funded by the Defense Advanced Research Projects Agency (DARPA) under grant number W91CRB-11-1-0005 (Program manager, Dr. J. Goldwasser)

Response of square honeycomb core sandwich panels to granular matter impact

The deformation of square honeycomb core, stainless steel sandwich panels by the impact of explosively accelerated granular matter has been investigated and compared to results from a previous study using equivalent (same material and mass per unit area) solid plates subjected to similar impulsive loadings. Spherical explosive charges surrounded by 25-150 kg mass annular shells of water-saturated granular media (either fused silica or zirconia particles) were suspended above the center of the edge clamped test panels. The radially expanding granular particle front velocities were measured from high-speed video images, and revealed that the granular matter had been accelerated to velocities of 500-1200 m/s after detonation. A Kolsky bar was used to measure the time-dependent pressure and impulse at a position equivalent to the panel center, while the permanent deflections of the sandwich panels were determined by profilometry after the experiments. Even though fracture of electron beam welds used to attach the back face sheet to the sandwich panel core occurred in all the tests, the permanent deflections of the sandwich panel back faces were significantly less than those of equivalent solid plates, and were accompanied by minimal core compression. Discrete particle simulations of the granular matter acceleration and impact loading of the sandwich panels indicated that their superior deflection benefit arose from their high bending resistance rather than particle-structure interactions. This benefit was offset when the rear face of the sandwich was kept the same distance from the impulsive source as that of the solid plate since the impact face of the sandwich panel was closer to the impulsive source, subjecting it to a higher impulse than the solid plate. However, a substantial deflection reduction was still achieved by use of a strong core sandwich design

High intensity impact of granular matter with edge-clamped ductile plates

The deformation of ductile square stainless steel plates during central impact by high velocity, spherically symmetric granular particle shells has been investigated using an approach that combined large-scale experiments with numerical simulation. The study used suspended spherical explosive charges to accelerate 25–150 kg concentric shells of water saturated glass or higher density zirconia particles to velocities of 500–1200 m/s. The test charges were positioned above the center of 2.54 cm thick, 1.32 m × 1.32 m wide edge clamped panels made of 304 stainless steel, and their permanent deflection fields measured after testing. A novel edge restraint approach was utilized to avoid disruption of reflected particle flow over the impacted surface of the sample and so avoid plate failure near the gripped regions. The end of a Kolsky bar was positioned at a location symmetrically equivalent to the plate center, and was used to measure both the pressure and the specific impulse applied to the plate center. The evolution of the granular shell topology following charge detonation was characterized by analysis of high-speed video images. The radial expansion of the granular shells, the pressure and impulse that they transferred to the Kolsky bar, and the test plates out-of-plane displacement field were all well predicted by a discrete particle-based simulation approach. The study confirms earlier simplified model estimates of an approximately linear dependence of the plates out-of-plane displacement upon incident impulse, and validates the use of the edge restraint concept. It also experimentally identifies the existence of a granular shell velocity dependent instability at the leading edge of the fastest expanding granular shells.The authors are grateful for the experimental assistance and guidance provided by Tommy Eanes. The funding for this research was provided by the Defense Advanced Research Projects Agency (DARPA) under grant number W91CRB-11-1-0005 (Program manager, Dr. J. Goldwasser)

Atomic Fluorine Beam Etching Of Silicon And Related Materials

A 1 eV neutral atomic fluorine beam has been shown to produce etch rates in silicon as high as 1 µm/min. Using a CaF 2 resist layer we fabricated 120 µm-deep by 1 µm-wide trenches (aspect ratio 120:1) in silicon with little sidewall taper (slopes of about 1000:1) or aspect-ratio dependent etching effects. Achieving such anisotropic etching suggests that the scattered species do not contribute significantly to sidewall etching under the conditions of this experiment. We estimate that the ultimate depth attainable for a 1 µm-wide trench is about 250 µm and that the critical parameter for attaining a trench of a certain depth is the aspect ratio. Our observations and analysis suggest that this etching technique can be used to fabricate trenches on a nanoscale level while maintaining high aspect ratios of 100 or greater. JVST_web.doc 09/12/99

Utilization of a deoxynucleoside diphosphate substrate by HIV reverse transcriptase

Background: Deoxynucleoside triphosphates (dNTPs) are the normal substrates for DNA sysnthesis is catalyzed by polymerases such as HIV-1 reverse transcriptase (RT). However, substantial amounts of deoxynucleoside diphosphates (dNDPs) are also present in the cell. Use of dNDPs in HIV-1 DNA sysnthesis could have significant implications for the efficacy of nucleoside RT inhibitors such as AZT which are first line therapeutics fro treatment of HIV infection. Our earlier work on HIV-1 reverse transcriptase (RT) suggested that the interaction between the γ phosphate of the incoming dNTP and RT residue K65 in the active site is not essential for dNTP insertion, implying that this polymerase may be able to insert dNPs in addition to dNTPs. Methodology/Principal Findings: We examined the ability of recombinant wild type (wt) and mutant RTs with substitutions at residue K65 to utilize a dNDP substrate in primer extension reactions. We found that wild type HIV-1 RT indeed catalyzes incorporation of dNDP substrates whereas RT with mutations of residue K645 were unable to catalyze this reaction. Wild type HIV-1 RT also catalyzed the reverse reaction, inorganic phosphate-dependent phosphorolysis. Nucleotide-mediated phosphorolytic removal of chain-terminating 3′-terminal nucleoside inhibitors such as AZT forms the basis of HIV-1 resistance to such drugs, and this removal is enhanced by thymidine analog mutations (TAMs). We found that both wt and TAM-containing RTs were able to catalyze Pi-mediated phosphorolysis of 3′-terminal AZT at physiological levels of Pi with an efficacy similar to that for ATP-dependent AZT-excision. Conclusion: We have identified two new catalytic function of HIV-1 RT, the use of dNDPs as substrates for DNA synthesis, and the use of Pi as substrate for phosphorolytic removal of primer 3′-terminal nucleotides. The ability to insert dNDPs has been documented for only one other DNA polymerase The RB69 DNA polymerase and the reverse reaction employing inorganic phosphate has not been documented for any DNA polymerase. Importantly, our results show that Pi-mediated phosphorolysis can contribute to AZT resistance and indicates that factors that influence HIV resistance to AZT are more complex than previously appreciated. © 2008 Garforth et al

Estimating process capability index Cpm using a bootstrap sequential sampling procedure

Construction of a confidence interval for process capability index CPM is often based on a normal approximation with fixed sample size. In this article, we describe a different approach in constructing a fixed-width confidence interval for process capability index CPM with a preassigned accuracy by using a combination of bootstrap and sequential sampling schemes. The optimal sample size required to achieve a preassigned confidence level is obtained using both two-stage and modified two-stage sequential procedures. The procedure developed is also validated using an extensive simulation study.<br /

Land use-based participatory assessment of ecosystem services for ecological restoration in village tank cascade systems of Sri Lanka

Village Tank Cascade System (VTCS) landscapes in the dry zone of Sri Lanka provide multiple ecosystem services (ESs) and benefits to local communities, sustaining the productivity of their land use systems (LUSs). However, there is a lack of adequate scientific research on the ESs of LUSs, despite the recent land use changes that have greatly impacted the provisioning of ESs. Collection of baseline ESs data is a pre-requisite for decision making on ESs-based ecological restoration and management of the VTCS. Thus, this study aimed at assessing ESs of the Mahakanumulla VTCS (MVTCS) located in the Anuradhapura district of Sri Lanka by using a participatory approach involving the integration of local knowledge, expert judgements and LUSs attribute data to assess the ESs. The methodology was designed to integrate the biodiversity and land degradation status of LUSs in a way that is directly linked with the supply of ESs. The study identified twenty-four ESs of the MVTCS based on community perceptions. The identified ESs were assessed as a function of LUSs to develop an ecosystem service supply (ESS) and demand (ESD) matrix model. The results reveal that the current overall ESD for regulating and supporting ESs is higher than the ESS capacity of MVTCS. The assessment also revealed that land degradation and biodiversity deterioration reduce the capacity to provide ESs. Downstream LUSs of the meso-catchment were found to be more vulnerable to degradation and insufficient to provide ESs. Further, the study established that ESs in the MVTCS are generated through direct species-based and biophysical-based providers. In addition, it emerged that social and cultural engagements also played an important role in association with both providers to generate certain types of ESs. Therefore, it can be concluded that VTCS ecological restoration depends on the extent to which integrated effort addresses the levels of ecological complexity, as well as the social engagement of communities and stakeholders. The results of this study provide a scientific basis that can inform future land use decision making and practices that are applicable to successful ESs-based ecological restoration and management of the VTCSs in the dry zone of Sri Lanka