Gun Technology Research Articles

The Hypervelocity Impact Facility at the University of Kent: Recent Upgrades and Specialized Capabilities.

Impact events are ubiquitous across the entire Solar System; craters are observed from Mercury to distant Pluto. This process has been occurring since the Solar System formed and is still occurring today. During such events, which typically occur at speeds measured in kilometers per second, extreme pressures and elevated temperatures are created. In order to understand the physical processes that occur under such conditions, we have been using a two-stage light gas gun to recreate hypervelocity impacts on a range of targets that are representative (in both composition and physical condition) of the surfaces of all objects within the Solar System.Within this paper we describe the advances we have made in light-gas gun technology, specifically focusing on the University of Kent’s light gas-gun, over the past 30 years which have led to significant advancements in Planetary Science and the general field of shock physics.

Prevention of Firearm Suicide in the United States: What Works and What Is Possible.

About 21,000 suicides in the United States in 2014 involved a firearm. The authors reviewed evidence from around the world regarding the relationship between firearm ownership rates and firearm suicide rates and the potential effectiveness of policy-based strategies for preventing firearm suicides in the United States. Relevant publications were identified by searches of PubMed, PsycINFO, MEDLINE, and Google Scholar from 1980 to September 2015, using the search terms suicide AND firearms OR guns. Excluding duplicates, 1,687 results were found, 60 of which were selected for inclusion; these sources yielded an additional 10 studies, for a total of 70 studies. Case-control and ecological studies investigating geographic and temporal variations in firearm ownership and firearm suicide rates indicate that greater firearm availability is associated with higher firearm suicide rates. Time-series analyses, mostly from other countries, show that legislation reducing firearm ownership lowers firearm suicide rates. Because the Second Amendment curtails legislation broadly restricting firearm access in the United States, the emphasis is shifted to restricting access for those at risk of harming themselves or others. Most suicides involve guns purchased years earlier. Targeted initiatives like gun violence restraining orders, smart gun technology, and gun safety education campaigns potentially reduce access to already purchased firearms by suicidal individuals. Such measures are too new to have evidence of effectiveness. Broadly reducing availability and access to firearms has lowered firearm suicide rates in other countries but does not appear feasible in the United States. Approaches restricting access of at-risk individuals to already purchased firearms by engaging the public and major stakeholders require urgent implementation and outcome evaluation for firearm suicide prevention.

Cloning of SjCA gene and its expression analysis on upland cottons

Acquisition of salt-tolerant genes from exogenous plants to improve cotton salt resistance has always been a hotspot of research on cotton salt resistance. However, the information regarding the method of conversion of living cotton pollens by portable gene gun technology is still little. Complete sequence information of the Carbonic Anhydrase (CA) gene was obtained from NCBI database, and its full ORF length sequence was cloned by RT-PCR technology. After the construction of pBI121-CA::GFP fusion expression vector, we used cotton pollens from upland cotton varieties Y-2067, ZA-23, and GZ-2, which have weaker autofluorescence, to conduct the research on the transient expression of cotton pollens in vivo via particle bombardment (gene gun technology). The results indicated that green fluorescence enhancement of the three kinds of cotton pollens was realized after the CA gene transformation, meaning that the CA gene expression level was increased. Besides, the salt tolerance germination ability of transgenic T1 seeds was also improved. Our research initially established a transient expression system of cotton pollen in vivo via particle bombardment technology, laying the theoretical foundation for further research of cotton genetic transformation and creation of cotton salt-tolerant germplasm.

Bacterial spores as particulate carriers for gene gun delivery of plasmid DNA

Bacillus subtilis spores represent a suitable platform for the adsorption of proteins, enzymes and viral particles at physiological conditions. In the present work, we demonstrate that purified spores can also adsorb DNA on their surface after treatment with cationic molecules. In addition, we demonstrate that DNA-coated B. subtilis spores can be used as particulate carriers and act as an alternative to gold microparticles for the biolistic (gene gun) administration of plasmid DNA in mice. Gene gun delivery of spores pre-treated with DODAB (dioctadecyldimethylammonium bromide) allowed efficient plasmid DNA absorption and induced protein expression levels similar to those obtained with gold microparticles. More importantly, we demonstrated that a DNA vaccine adsorbed on spores can be loaded into biolistic cartridges and efficiently delivered into mice, which induced specific cellular and antibody responses. Altogether, these data indicate that B. subtilis spores represent a simple and low cost alternative for the in vivo delivery of DNA vaccines by the gene gun technology.

Growth of poly-crystalline Cu films on Y substrates by picosecond pulsed laser deposition for photocathode applications

In this work, the deposition of Cu thin films on Y substrates for photocathode applications by pulsed laser deposition employing picosecond laser pulses is reported and compared with the use of nanosecond pulses. The influence of power density (6–50GW/cm2) on the ablation of the target material, as well as on the properties of the resulting film, is discussed. The material transfer from the target to the substrate surface was found to be rather efficient, in comparison to nanosecond ablation, leading to the growth of films with high thickness. Scanning electron microscope analysis indicated a quasi-continuous film morphology, at low power density values, becoming granular with increasing power density. The structural investigation, through X-ray diffraction, revealed the poly-crystalline nature of the films, with a preferential growth along the (111) crystallographic orientation of Cu cubic network. Finally, energy-dispersive X-ray spectroscopy showed a low contamination level of the grown films, demonstrating the potential of a PLD technique for the fabrication of Cu/Y patterned structures, with applications in radiofrequency electron gun technology.

Simulation based iterative post-optimization of paths of robot guided thermal spraying

Abstract Robot-based thermal spraying is a production process in which an industrial robot guides a spray gun along a path in order to spray molten material onto a workpiece surface to form a coating of desired thickness. This paper is concerned with optimizing a given path of this sort by post-processing. Reasons for doing so are to reduce the thickness error caused by a not sufficiently precise design of the given path, to adapt the path to a changed spray gun or spray technology, to adapt the path to slight incremental changes of the workpiece geometry, or to smooth the path in order to improve its execution by the robot. An approach to post-optimization using the nonlinear conjugate gradient method is presented which employs a high-quality GPGPU-based simulation of the spray process for the evaluation of the coating thickness error and additionally taking care of the kinematic path quality. The number of computationally time-consuming calls of the simulation is kept low by analytically calculating estimates of gradients from a simplified material deposition model. A rigorous experimental evaluation on case studies of the mentioned applications shows that the method efficiently delivers improved paths which reduce the coating error on real free form surfaces considerably, i.e. the squared coating error is below 3.5% of the original value in every case study.

Tilted femtosecond pulses for velocity matching in gas-phase ultrafast electron diffraction

Recent advances in pulsed electron gun technology have resulted in femtosecond electron pulses becoming available for ultrafast electron diffraction experiments. For experiments investigating chemical dynamics in the gas phase, the resolution is still limited to picosecond time scales due to the velocity mismatch between laser and electron pulses. Tilted laser pulses can be used for velocity matching, but thus far this has not been demonstrated over an extended target in a diffraction setting. We demonstrate an optical configuration to deliver high-intensity laser pulses with a tilted pulse front for velocity matching over the typical length of a gas jet. A laser pulse is diffracted from a grating to introduce angular dispersion, and the grating surface is imaged on the target using large demagnification. The laser pulse duration and tilt angle were measured at and near the image plane using two different techniques: second harmonic cross correlation and an interferometric method. We found that a temporal resolution on the order of 100 fs can be achieved over a range of approximately 1 mm around the image plane.

Approaches to Improve the Oral Bioavailability and Effects of Novel Anticancer Drugs Berberine and Betulinic Acid

BackgroundThe poor bioavailability of Berberine (BBR) and Betulinic acid (BA) limits the development of these promising anticancer agents for clinical use. In the current study, BBR and BA in spray dried (SD) mucoadhesive microparticle formulations were prepared.MethodsA patented dual channel spray gun technology established in our laboratory was used for both formulations. Gastrointestinal (GI) permeability studies were carried out using Caco-2 cell monolayer grown in in-vitro system. The oral bioavailability and pharmacokinetic profile of SD formulations were studied in Sprague Dawley rats. A549 orthotopic and H1650 metastatic NSCLC models were utilized for the anticancer evaluations.ResultsPharmacokinetic studies demonstrated that BBR and BA SD formulations resulted in 3.46 and 3.90 fold respectively, significant increase in plasma Cmax concentrations. AUC levels were increased by 6.98 and 7.41 fold in BBR and BA SD formulations, respectively. Compared to untreated controls groups, 49.8 & 53.4% decrease in the tumor volumes was observed in SD formulation groups of BBR and BA, respectively. Molecular studies done on excised tumor (A549) tissue suggested that BBR in SD form resulted in a significant decrease in the survivin, Bcl-2, cyclin D1, MMP-9, HIF-1α, VEGF and CD31 expressions. Cleaved caspase 3, p53 and TUNEL expressions were increased in SD formulations. The RT-PCR analysis on H1650 tumor tissue suggested that p38, Phospho-JNK, Bax, BAD, cleaved caspase 3&8 mRNA expressions were significantly increased in BA SD formulations. Chronic administration of BBR and BA SD formulations did not show any toxicity.ConclusionsDue to significant increase in oral bioavailability and superior anticancer effects, our results suggest that spray drying is a superior alternative formulation approach for oral delivery of BBR and BA.

Firearms in Nineteenth-Century Botswana: The Case of Livingstone's 8-Bore Bullet

While the importance of firearms in shaping the history of Southern Africa has long been acknowledged, the participation by local societies in the nineteenth-century revolution in gun technology has been relatively neglected. This paper examines the nature of munitions in Botswana during the critical decade that led up to the 1852–1853 Batswana-Boer War, focusing on the early presence of elongated or conical bullets and large bore hunting rifles, as well as artillery in the region. The findings have a bearing on a re-evaluation of the wider regional balance of military power during the period, as well as the relationship between the evolution of armaments and local society.

The Effects of Pulse Pressure from Seismic Water Gun Technology on Northern Pike

AbstractWe examined the efficacy of sound pressure pulses generated from a water gun for controlling invasive Northern Pike Esox lucius. Pulse pressures from two sizes of water guns were evaluated for their effects on individual fish placed at a predetermined random distance. Fish mortality from a 5,620.8‐cm3 water gun (peak pressure source level = 252 dB referenced to 1 μP at 1 m) was assessed every 24 h for 168 h, and damage (intact, hematoma, or rupture) to the gas bladder, kidney, and liver was recorded. The experiment was replicated with a 1,966.4‐cm3 water gun (peak pressure source level = 244 dB referenced to 1 μP at 1 m), but fish were euthanized immediately. The peak sound pressure level (SPLpeak), peak‐to‐peak sound pressure level (SPLp‐p), and frequency spectrums were recorded, and the cumulative sound exposure level (SELcum) was subsequently calculated. The SPLpeak, SPLp‐p, and SELcum were correlated, and values varied significantly by treatment group for both guns. Mortality increased and organ damage was greater with decreasing distance to the water gun. Mortality (31%) by 168 h was only observed for Northern Pike exhibiting the highest degree of organ damage. Mortality at 72 h and 168 h postexposure was associated with increasing SELcum above 195 dB. The minimum SELcum calculated for gas bladder rupture was 199 dB recorded at 9 m from the 5,620.8‐cm3 water gun and 194 dB recorded at 6 m from the 1,966.4‐cm3 water gun. Among Northern Pike that were exposed to the large water gun, 100% of fish exposed at 3 and 6 m had ruptured gas bladders, and 86% exposed at 9 m had ruptured gas bladders. Among fish that were exposed to pulse pressures from the smaller water gun, 78% exhibited gas bladder rupture. Results from these initial controlled experiments underscore the potential of water guns as a tool for controlling Northern Pike.

Estimations of compatibility of supercapacitors for use as power sources for resistance welding guns

Supercapacitors offer potential for several kilojoules of energy to be proved in a small package with limited charge voltage (few volts). A preliminary examination of supercapacitors suggests that both the voltages used and retainable energies are well matched for resistance spot welding applications. Utilization of supercapacitors as resistance welding power supplies offers significant weight reduction over conventional (transformer and power supply) approaches, with subsequent economic advantages. In this work, some preliminary analyses have been done to assess the potential for using supercapacitors as resistance welding power supplies. This was done by integrating two separate analyses: one to assess the inductive response of specific weld gun designs and the second to define the current response of supercapacitors matched with that inductance. Results demonstrated potential for achieving desired currents and pulse widths with the proper selection of supercapacitor type and arrangement as well as secondary gun configuration. These analyses were further used to understand implications of system design on overall deliverable current capability. While the results described here only describe potential, some recommendations are made for next steps advancing supercapacitor-based resistance spot weld gun technology.

Design and implementation of a fs-resolved transmission electron microscope based on thermionic gun technology

In this paper, the design and implementation of a femtosecond-resolved ultrafast transmission electron microscope is presented, based on a thermionic gun geometry. Utilizing an additional magnetic lens between the electron acceleration and the nominal condenser lens system, a larger percentage of the electrons created at the cathode are delivered to the specimen without degrading temporal, spatial and energy resolution significantly, while at the same time maintaining the femtosecond temporal resolution. Using the photon-induced near field electron microscopy effect (PINEM) on silver nanowires the cross-correlation between the light and electron pulses was measured, showing the impact of the gun settings and initiating laser pulse duration on the electron bunch properties. Tuneable electron pulses between 300fs and several ps can be obtained, and an overall energy resolution around 1eV was achieved.

BioSpotlight

BioTechniquesVol. 54, No. 1 BioSpotlightOpen AccessBioSpotlightNathan BlowNathan BlowSearch for more papers by this authorPublished Online:3 Apr 2018https://doi.org/10.2144/000113983AboutSectionsPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinkedInRedditEmail Adapter-less library constructionA key ingredient in today's massively parallel next-generation sequencing approaches is the creation of a sequencing library. Although several approaches have been advanced in recent years to construct these libraries they all generally require large amounts of starting material and additional purification steps such as gel extraction, placing restrictions on researchers. In this issue of BioTechniques, David Lazinksi and Andrew Camilli from Tufts University School of Medicine (Boston, MA) report on their development of a new technique for next-generation sequencing library preparation based on the use of homopolymer tails. Called homopolymer tail-mediated ligation PCR, or HTML-PCR for short, Lazinski and Camilli's approach starts with a controlled reaction to add homopolymer deoxycytosine (dC) tails to the 3' ends of double stranded DNA. The addition of these tails enables the annealing and ligation of chimeric oligonucleotides with a user-defined sequence at the 5' end and 4-7 complementary deoxyguanosines (dG). From here, the first annealed primer can be used in combination with a second primer possessing a long dG region complementary to the homopolymer dC tail and a second user-defined sequence in a PCR reaction to generate the final library products for sequencing. The authors tested their approach by creating Vibrio cholerae and Streptococcus pneumoniae libraries from nanogram and even sub-nanogram quantities of starting material, finding that HTML-PCR actually generated libraries that were at least partial effective down to 0.01ng of input material. In order to address the possibility that the homopolymer stretch of dG nucleotides in the second primer could amplify long oligo(dC) regions in the cases of larger genomes, the authors suggested the use of the artificial base 2-amino deoxyadenosine (2-amino dA) instead of dC for tailing and the use of deoxythymidines (dT) in the primers, since oligo(dT) primers can more stably anneal to 2-amino dA stretches than endogenous dA stretches in the genome. Unlike more the traditional approaches for sequencing library construction where adapters are directly ligated onto double stranded genomic DNA, HTML-PCR does not use adapters which enables the method to work with less starting material and eliminates the need for gel purification to remove adapter-dimers (gel purification can still be used for size selection if needed). And while other adapter-free methods have been published, HTML-PCR takes advantage of materials readily available in most molecular biology labs, making the technique accessible and cost-effective. In the end, these advantages also raise the interesting possibility that HTML-PCR could be further adapted in the future to work with high-throughput robotic applications.General structure of the oligoelectrolyte polymeric carrier BG-2See “Homopolymer tail mediated ligation PCR: a streamlined and highly efficient method for DNA cloning and library construction”Carrying the loadAs any yeast biologist out there can attest, transforming yeast is a tricky business. This is due in large measure to the presence of a glycan- and mannose-rich cell wall acting as a barrier for the introduction of genetic material. Genetic transformation techniques, including lithium chloride-based chemical transformation, electroporation, and the use of gene gun technologies, have been described and refined. However, while specific approaches might prove useful with certain yeast species, there are several yeast species with strong potential for biotechnology applications where genetic transformation approaches would be highly desirable but the available methods have proven to be inefficient. Seeing the need for an improved transformation methodology, Filyak et al. detail the use an oligoelectrolyte polymeric carrier for yeast transformation in this issue of BioTechniques. The key to the author's new approach lies in the design of their polymeric carrier, which is composed of an anionic backbone with dimethyl aminoethyl methacrylate-based side branches. In direct comparisons with lithium chloride-based transformation and electroporation, the polymeric nanoscale carrier yielded at least two times more Hansenula polymorpha tranformants and five times more Pichia pastoris transformants. In addition, the polymeric carrier was as effective as lithium chloride and electroporation methodologies for the transformation of Saccharomyces cerevisiae, further confirming the wide range of yeast species this method can transform. The new polymeric carrier-based transformation approach described by Filyak et al. not only provides another tool for biologists in their quest to understand and genetically manipulate yeast species, but also presents a new avenue for exploration of genetic transformation technology in general as their technique is one of the first examples of the use of nanoscale carriers for DNA delivery in yeast.See “A novel method for genetic transformation of yeast cells using oligoelectrolyte polymeric nanoscale carriers”FiguresReferencesRelatedDetails Vol. 54, No. 1 Follow us on social media for the latest updates Metrics Downloaded 82 times History Published online 3 April 2018 Published in print January 2013 Information© 2013 Author(s)PDF download

Inhibition of the binding of MSG-intermolt-specific complex, MIC, to the sericin-1 gene promoter and sericin-1 gene expression by POU-M1/SGF-3

The sericin-1 gene encoding a glue protein is expressed in the middle silk gland (MSG) of the silkworm, Bombyx mori. A member of the class III POU domain transcription factors, POU-M1, was cloned as the factor bound to the SC site of the sericin-1 promoter and has been proposed to be a positive transcription factor. In this study, we analyzed the expression pattern of the POU-M1 gene in fourth and fifth instars in comparison with the pattern of the sericin-1 gene. The POU-M1 gene was expressed strongly in the region anterior to the sericin-1-expressing portion of the silk gland at both feeding stages. As the sericin-1-expressing region expands from the posterior to middle portions of the MSG in the fifth instar, the POU-M1-expressing region retreated from the middle to anterior portion. Introduction of the expression vector of POU-M1 into the silk glands by gene gun technology repressed promoter activity of the sericin-1 gene, suggesting that POU-M1 regulates the sericin-1 gene negatively. An in vitro binding assay showed that POU-M1 bound not only to the SC site but also to other promoter elements newly detected in vivo. Another spatiotemporal specific factor MIC binds to these elements, and POU-M1 competed with MIC to bind at the -70 site essential for promoter activity. These results suggest that POU-M1 is involved in restricting the anterior boundary of the sericin-1-expressing region in the silk gland by inhibiting the binding of the transcriptional activator to the promoter elements.

Dispersive transport in molecularly doped polymers: Theory and experiment

Theoretical and experimental studies of the carrier transport in molecularly doped polymers (MDPs) have been reported. Theoretical analysis uses the multiple trapping (MT) model with an exponential and Gaussian trap distributions. Experimental technique is based on an electron gun technology enabling one to conduct time of flight measurements using the surface and the bulk carrier generation. The list of MDPs tested includes both polar and non-polar systems, some with varying dopant concentration. Experimental results are compared to the MT model predictions as well as the mainstream theories of the hopping conduction in MDPs.

Electron Gun Technologies for High Resolution Electron Microscopes

High-brightness electron gun technologies for high resolution electron microscopes are reviewed. High performance electron beam apparatuses today are equipped with either Schottky emission or field emission type cathodes, both of which have sharply etched tips for electric field enhancement that promotes electron emission. One of the key elements in these pointed cathodes is a proper control of the tip geometry. It substantially affects the emitter optics and performance. It is shown that the geometry is dictated by the faceting of the tip, which is in turn determined by the Equilibrium Crystal Shape (ECS). The ECS is the tip geometry that minimizes the surface free energy and dependent on the emitter operation environment. By proper choice of the tip field and temperature, one can control the degree of faceting and achieve optically desirable tip geometries.

Cutting AISI 1045 steel at very high speeds

An experimental device, based on the light-gas gun technology, was set up to realize high speed cutting over a wide range of cutting speeds from 30m/s to 200m/s. High-speed cutting experiments were performed on AISI 1045 steels. The investigation of chip morphology, micro-structures, micro-hardness and the finished surface integrity were carried out, focusing on the physical phenomena accompanying the saw-tooth chip formation. The results reveal that, with increasing the cutting speed, the transition of chip morphology from continue to saw-tooth could be attributed to repeated thermoplastic shear-banding rather than periodic cracking. In particular, a severe material flow leading to mass transfer of heat was observed at very high cutting speed. The effect of mass transfer of heat on thermoplastic shear instability was further investigated, which implies that the mass transfer of heat would retard the formation of saw-tooth chip. Finally, the influence of cutting speed and mass transfer on the temperature distribution during high speed machining was briefly discussed.

Development and Spread of Firearms in Medieval and Early Modern Eurasia

AbstractRecent research has overturned the pre‐existing understanding of the history of guns and gunpowder. This has invalidated the Military Revolution theory that argued that firearms revolutionized Europe warfare between 1500 and 1800, leading to the modern nation state. More research will be necessary to detail how and why gunpowder and guns spread throughout the world the way they did, and why Europeans were able to advance gun technology so quickly beginning in the 17th century.

BXERL photo-injector based on a 217 MHz normal conducting RF gun

The Beijing X-ray Energy Recovery Linac (BXERL) test facility is proposed in Institute of High Physics (IHEP). In this proposal, the main linac requires the injector to provide an electron beam with 5 MeV energy and 10 mA average current. An injector based on DC gun technology is the first candidate electron source for BXERL. However, the field emission in the DC gun cavity makes it much more difficult to increase the high voltage to more than 500 kV. Another technology based on a 217 MHz normal conducting RF gun is proposed as the backup injector for this test facility. We have designed this RF gun with 2D SUPERFISH code and 3D MICROWAVE STUDIO code. In this paper, we present the optimized design of the gun cavity, the gun RF parameters and the set-up of the whole injector system. The detailed beam dynamics have been done and the simulation results show that the injector can generate electron bunches with RMS normalized emittance 1.0 πmm·mrad, bunch length 0.77 mm, beam energy 5.0 MeV and energy spread 0.60%.

Novel enhancer and promoter elements indispensable for the tissue-specific expression of the sericin-1 gene of the silkworm Bombyx mori

Sericins are glue proteins produced specifically in the middle silk gland (MSG) of the silkworm Bombyx mori, while the silk fiber protein, fibroin, is produced in the posterior silk gland (PSG). These silk proteins are expected to be useful biomaterials in medical technology as well as biotechnology. In this study, we analyzed promoter elements of the sericin-1 gene ( ser1) in vivo by introducing reporter constructs into silk glands via gene gun technology. The region from −1602 to +47 was sufficient to induce MSG-specific expression. The 5′ deletion mutants showed a three-step decrease in promoter activity with the key sequences located between −1362 and −1250, −201 and −116, and −115 and −37. We detected a tissue- and stage-specific factor complex (MSG–intermolt-specific complex: MIC) bound to the sequence elements around the −1350, −320, −180, and −70 regions. A mutation in the −70 region, which inhibits MIC-binding, diminished almost all promoter activity, while another mutation that did not inhibit MIC-binding showed no effect on promoter activity. The results suggest that the binding of MIC to the above elements is intrinsic for the spatiotemporal specificity of ser1 in vivo.