Gelatin Block Research Articles

Distortion of the temporary cavity and its influence on staining in firearm barrels.

After contact shots to the head, biological traces can be found inside the barrel of the firearm. Experimental protocols to generate this sort of staining, using 12cm gelatin cubes containing thin foil bags filled with acrylic paint, human blood, and radiocontrast agent, have been developed. Previous research on shots fired at a distance has shown the underlay sustaining these gelatin cubes has an influence on experimental results. This study was conducted to investigate the role of the sustaining base of the gelatin blocks during contact shots, and its influence on the staining result inside firearm barrels. Eighteen contact shots were performed using 22 LR, 32 ACP (7.65 Browning) and 9mm Luger semi-automatic pistols. With each pistol, shots were fired onto six gelatin cubes; three placed upon a rigid platform and three upon an elastic underlay. The shots were recorded by a high-speed video camera as they penetrated the gelatin cube. Any staining present inside the firearm barrels after the shots were fired was documented by endoscopy. Cross sections of the gelatin blocks were then compared to the high-speed video. It was found that the nature of the staining inside the barrel was not influenced by the underlay sustaining the target model. In the experiment using a 9mm Luger, the rigid counterfort provoked a visible distortion of the temporary cavity, but, cross sectional analysis of the gelatin cubes did not reveal a relevant influence of the sustaining underlay on the crack length in the gelatin. This could be explained by a secondary expansion of the temporary cavity left by the projectile as a consequence of subsequent inflow of muzzle gases.

A theoretical model of non-deforming bullets penetrating ballistic gelatin

To investigate the interaction mechanisms between bullets and living tissues, ballistic gelatin is used as the tissue simulant and a theoretical ballistic model is established. The drag force, the lift force and the overturning moment on the bullet are obtained based on the assumption that the pressure on the wetted area is consisted of a dynamic term and a static term. To verify the ballistic model, a non-deforming 7.62 × 39 mm rifle bullet is fired in the gelatin block. Spatial positions and orientations of the bullet are obtained through the reflective mirror system. The calculated displacements of the center of mass agree well with the experimental data. Both the yaw angles and the elevation angles of the bullet coincide well with the corresponding experimental data in the first 250 mm of penetration. As shape parameters of the bullet are integrated in the forces and in the moment in the model, the model is expected to be used in the motion predictions of different bullets.

A comparison of penetration and damage caused by different types of arrowheads on loose and tight fit clothing

Bows and arrows are used more for recreation, sport and hunting in the Western world and tend not to be as popular a weapon as firearms or knives. Yet there are still injuries and fatalities caused by these low-velocity weapons due to their availability to the public and that a licence is not required to own them. This study aimed to highlight the penetration capabilities of aluminium arrows into soft tissue and bones in the presence of clothing. Further from that, how the type and fit of clothing as well as arrowhead type contribute to penetration capacity. In this study ballistic gelatine blocks (non-clothed and loose fit or tight fit clothed) were shot using a 24lb weight draw recurve bow and aluminium arrows accompanied by four different arrowheads (bullet, judo, blunt and broadhead).The penetration capability of aluminium arrows was examined, and the depth of penetration was found to be dependent on the type of arrowhead used as well as by the type and fit or lack thereof of the clothing covering the block. Loose fit clothing reduced penetration with half of the samples, reducing penetration capacity by percentages between 0% and 98.33%, at a range of 10m. While the remaining half of the samples covered with tight clothing led to reductions in penetration of between 14.06% and 94.12%.The damage to the clothing and the gelatine (puncturing, cutting and tearing) was affected by the shape of the arrowhead, with the least damaged caused by the blunt arrowheads and the most by the broadhead arrows. Clothing fibres were also at times found within the projectile tract within the gelatine showing potential for subsequent infection of an individual with an arrow wound.Ribs, femur bones and spinal columns encased in some of the gelatine blocks all showed varying levels of damage, with the most and obvious damage being exhibited by the ribs and spinal column.The information gleaned from the damage to clothing, gelatine blocks and bones could potentially be useful for forensic investigators, for example, when a body has been discovered with no weapons or gunshot residue present.

Sorbitol-based supramolecular organogelators with effective phase-selective gelation and significant self-healing property

ABSTRACTSeveral effective phase-selective gelators (PSGs) have been developed from a series of cheap and easy-to-make sorbitol-based compounds for the removal of many oils from their biphasic mixtures with water. The dominant factors that drive gelation have been studied using FTIR and temperature-dependent 1H NMR spectra. Additionally, the case of PSGs exhibit significant self-healing properties that can recover the gelatin block and hence provide a more flexible approach for oil-spill recovery. The highly effective phase-selective performance and self-healing properties of these organogelators indicate the potential and promising applicability in oil-spill recovery.

The effect of helmet materials and simulated bone and tissue layers on bullet behaviour in a gelatine model of overmatch penetrating head injury

The aim of this work was to simulate an overmatch ballistic event against a head wearing a helmet. The experiments were designed to understand how layers of bone (or synthetic bone), synthetic skin and currently used helmet materials influence the behaviour of full metal jacket mild steel core (FMJ MSC) 7.62 × 39 mm bullets, impacting on targets with a mean velocity of 650 m/s. Bullet behaviour within 10% (by mass) gelatine blocks was assessed by measurements made of the temporary cavity within the blocks using high-speed video and of the permanent cavity by dissecting blocks post firing. While ANOVA did not find significant difference at the 0.05 level in the mean values of most of the measurements, there was a significant difference in neck length within the gelatine blocks. The addition of material layers did produce greater variability in the temporary cavity measurements under some of the conditions. One of the synthetic bone polymers with a synthetic skin layer produced similar results within the gelatine blocks to the horse scapulae (with residual tissue) and may be suitable for future ballistic experiments.

Wound morphology in contact shots from blank cartridge handguns: a study on composite models.

It is a well-known fact that blank cartridge guns can cause penetrating and even fatal injuries when discharged in contact or at very close ranges. In these cases, the gas jet perforates the skin leaving an entrance wound similar to that from a conventional gun. In order to investigate the wound morphology in contact shots from blank firearms, test shots were fired at composite models of pig skin and gelatin blocks using three different calibre 9-mm blank cartridge handguns (two pistols and one revolver) and two types of ammunition. It turned out that the penetrating gas jet produced roundish skin defects resembling bullet entrance holes. Small skin particles from the perforation site were dispersed in the underlying simulant where radiating cracks containing greyish gunshot residues indicated the original expansion of the inrushing combustion gases. Apart from the size of the permanent entrance hole in the skin and the final position of the displaced tissue particles, the penetration depth of the gas jet was determined. Under the specified conditions of the test shots, the zone of mechanical destruction within the simulant was 2.2 to 6.1cm in length, which illustrates the injuring potential of contact shots inflicted with blank cartridge handguns.

The influence of the counterfort while ballistic testing using gelatine blocks.

In wound ballistic research, gelatine blocks of various dimensions are used depending on the simulated anatomical region. When relatively small blocks are used as substitute for a head, problems with regard to the expansion of the gelatine block could arise. The study was conducted to analyse the influence of the material the gelatine block is placed upon. Thirty-six shots were performed on 12cm gelatine cubes doped with thin foil bags containing acrylic paint. Eighteen blocks each were placed on a rigid table or on a synthetic sponge of 5cm height. Deforming bullets with different kinetic energies were fired from distance and recorded by a high-speed video camera. Subsequently, the gelatine cubes were cut into 1cm thick slices which were scanned using a flatbed scanner. Cracks in the gelatine were analysed by measuring the longest crack, Fackler's wound profile and the polygon (perimeter and area) outlining the ends of the cracks. The energy dissipated ranged from 153 to 707J. For moderate energy transfer, no significant influence of the sustaining material was discerned. With increasing dissipated energy, the sponge was compressed correspondingly, and the cracks were longer than in gelatine blocks which had been placed on a table. High-speed video revealed a loss of symmetry and a flattened inferior margin of the temporary cavity with energies superior to approx. Two hundred Joules when the blocks were placed on a rigid platform. However, 12cm gelatine cubes showed material limits by a non-linear response when more than 400J were dissipated for both rigid and elastic sustainment. In conclusion, the smaller the gelatine blocks and the greater the energy transfers, the more important it is to take into account the counterfort of the sustaining material.

The reference cube: A new ballistic model to generate staining in firearm barrels.

After contact shots to the head biological traces can be found inside firearm barrels. So far silicone coated, gelatin filled box models were used to generate such staining according to the triple contrast method (mixture of acrylic paint, barium sulfate and blood sealed in a thin foil bag). This study was conducted to develop a transparent ballistic model allowing contact shots. Gelatin filled polyethylene bottles with and without a silicone coat were tested in comparison to non-covered gelatin blocks. Finally, thin foil bags of 5cm×5cm dimension were glued on a synthetic absorbent kitchen wipe on top of which 1L 10% gelatin solution was molded to create blocks of 8.5cm length. A kitchen wipe with a paint pad on its inside formed the front of the cube. Three contact shots each with a 9mm Luger pistol and a .38 special revolver were performed on all model variations. The staining was documented by endoscopy and swabs gathered from both ends of the barrel were analyzed by quantitative PCR. Reliable staining was achieved using the front covered gelatin block with comparable results to the silicone coated box model used before. For further research using ballistic models to simulate a human head a symmetric form of the gelatin block such as a cube is recommended.

A fully synthetic lung model for wound-ballistic experiments—First results

PurposeToday, synthetic models have all but replaced animal and corpse models in examining damage to soft-tissues and skeletal structures by ballistic trauma. As, however, non-solid organs such as the lungs, have not been able to be replaced by a fully synthetic model we attempted to create such a model. Material and methods20% ordnance gelatine was frothed with a household mixer and cooled to stable foam. Several of these foam blocks were then stuck together with liquid gelatine and placed between 10% gelatine blocks. As controls, we embedded pig lungs in gelatine and compared the wound channels seen in computed tomography created upon shooting with 9mm Luger. ResultsThe fully synthetic models displayed radiological and physical densities comparable to real lungs. The wound profile characteristics of the fully synthetic lung models were very similar to the semisynthetic swine-gelatine models regarding the permanent wound cavity. Furthermore, in both semi- and fully synthetic models we detected a ring surrounding the permanent wound channel, most likely representing the remnants of the temporary wound cavity. ConclusionOur results indicate that this fully synthetic lung model is a viable substitute for ballistic experiments on lungs. We believe that further research on the temporary wound channel in lungs is possible with this model in order to provide more insight into the effect of ballistic trauma to the lungs not seen otherwise.

An experimental study on the effects of the head angle and bullet diameter on the penetration of a gelatin block

This research conducts 300 small-scale ammunition experiments using moderate bullet speeds and a variety of bullet configurations in order to understand the relationship between penetration behavior and bullet shape. To maximize the survivability of soldiers and reduce their vulnerability and ballistics wounds, it is very important to understand the penetration physics of bullets. Inside human bodies, tumbling and traveling trajectories are important factors to consider when analyzing human injuries due to ballistics. Therefore, many kinds of bullets and armor have been proposed to minimize or maximize human damage. In this study, to support the development of bullets, 10 bullets with different head angle shapes and different diameters were manufactured and fired at speeds less than 200m/s towards transparent gelatin blocks, and the damage mechanisms, i.e., temporary cavities and permanent cavities, were studied by taking penetration images using a high speed camera. It was found that the tumbling and rotations of bullets are influenced by kinetic energies and the shapes of bullets, and several empirical relationships are derived. The results suggest that the shapes and the diameters are crucial factors for ballistics wounds.

Needle-Free Injection of Vesicular Phospholipid Gels—A Novel Approach to Overcome an Administration Hurdle for Semisolid Depot Systems

Vesicular phospholipid gels (VPGs) are depot formulations for the sustained release of drugs which are characterized by a high amount of phospholipids in the formulation. They consist of physiological excipients only and therefore display high biocompatibility. Their manufacture is simple, cheap, solvent free, and ideal for the processing of proteins and peptides because of the low stress on the molecule, for example, by elevated temperatures. One major hurdle of VPGs is their high viscosity which makes them hard to almost impossible to inject with conventional, thin needles used for subcutaneous administration. However, so far no data are published to overcome this administration challenge. In the present study, needle-free injection was investigated and successfully applied as a technology for the easy and elegant administration of VPGs. VPGs with different phospholipid content were injected with a Biojector 2000 into gelatin blocks and full thickness pig skin postmortem as in vitro models and the injection depth was determined after injection. The release behavior was tested after shearing the VPG with the device to evaluate the effect of shearing on the drug release from the formulation. No differences were observed when compared to an ejection with needle and syringe.

Possible influences on bullet trajectory deflection in ballistic gelatine

The influence of the distance to the top and bottom of a gelatine block and to bullet tracks from previously fired shots on a bullet’s trajectory, when passing through ballistic gelatine, was studied. No significant difference in deflection was found when trajectories of 9mm Luger bullets, fired at a 3.5cm distance to the top and bottom of a gelatine block and to bullet tracks from previously fired shots, were compared to trajectories of bullets fired 7cm or more away from any of the aforementioned aspects. A surprisingly consistent 6.5° absolute deflection angle was found when these bullets passed through 22.5 to 23.5cm of ballistic gelatine. The projection angle, determined by the direction of the deflection, appeared to be random. The consistent absolute angle, in combination with the random projection angle, resulted in a cone-like deflection pattern.

Rifle bullet penetration into ballistic gelatin

The penetration of a rifle bullet into a block of ballistic gelatin is experimentally and computationally studied for enhancing our understanding of the damage caused to human soft tissues. The gelatin is modeled as an isotropic and homogeneous elastic-plastic linearly strain-hardening material that obeys a polynomial equation of state. Effects of numerical uncertainties on penetration characteristics are found by repeating simulations with minute variations in the impact speed and the angle of attack. The temporary cavity formed in the gelatin and seen in pictures taken by two high speed cameras is found to compare well with the computed one. The computed time histories of the hydrostatic pressure at points situated 60 mm above the line of impact are found to have "two peaks", one due to the bullet impact and the other due to the bullet tumbling. Contours of the von Mises stress and of the effective plastic strain in the gelatin block imply that a very small region adjacent to the cavity surface is plastically deformed. The angle of attack is found to noticeably affect the penetration depth at the instant of the bullet tumbling through 90°.

Comparative Evaluation of Potentially Radiolucent Projectile Components by Radiographs and Computed Tomography.

Projectile components that are traditionally radiolucent can be of considerable importance in determination of weapon type and caliber, but they are often missed on evaluation of postmortem radiographs. We hypothesized that these components would be significantly better visualized by evaluation of computed tomography (CT) scans compared to the practice standard of radiography alone. In this project, potentially radiolucent projectile components were both pulled apart and fired, and the radiolucent components were recovered. These components were embedded in blocks of ballistics gelatin and were imaged using both radiography and CT. The scans were evaluated by three blinded, board-certified radiologists for the presence/absence of projectile components and true-negative regions in each block. If a radiologist indicated visualization of a projectile component, they were further requested to describe their observation. It was found that traditionally radiolucent projectile components are not significantly more often identified on CT scans than radiography (p<0.05).

Transient pressure wave in the behind armor blunt trauma: experimental and computational investigation

In the last few decades, various researches focus on the transient pressure in the behind armor blunt trauma. This paper presented a investigation on the transient pressure in the ballistic gelatin behind a soft body armor subjected to the impacting from three ammunitions. Experimental results show that three peaks appear on the pressure–time curves without taking into account the ammunition type and the impact velocity. Furthermore, numerical models of the test were created to compare modelling results to the pressure from the pressure gauges buried in the gelatin block. The main features on the pressure–time cure were discussed to analyze the wave formation and propagation. With the verified model, the effect of the boundary was also investigated to explain the wave reflection which appeared after two peaks.

Fast and safe fabrication of a free-standing chitosan/alginate nanomembrane to promote stem cell delivery and wound healing.

Polymeric ultrathin membranes that are compatible with cells offer tremendous advantages for tissue engineering. In this article, we report a free-standing nanomembrane that was developed using a layer-by-layer self-assembly technique with a safe and sacrificial substrate method. After ionization, two oppositely charged polyelectrolytes, alginate and chitosan, were alternately deposited on a substrate of a solidified gelatin block to form an ultrathin nanomembrane. The space between the two adjacent layers was ∼200 nm. The thickness of the nanomembrane was proportional to the number of layers. The temperature-sensitive gelatin gel served as a sacrificial template at 37°C. The free-standing nanomembrane promoted bone marrow stem cell adhesion and proliferation. Fluorescence-activated cell sorting was used to analyze green-fluorescent-protein-positive mesenchymal stem cells from the wounds, which showed a significantly high survival and proliferation from the nanomembrane when cells were transplanted to mouse dorsal skin that had a full-thickness burn. The bone-marrow-stem-cell-loaded nanomembrane also accelerated wound contraction and epidermalization. Therefore, this methodology provides a fast and facile approach to construct free-standing ultrathin scaffolds for tissue engineering. The biocompatibility and free-standing nature of the fabricated nanomembrane may be particularly useful for stem cell delivery and wound healing.

3D printing complex scaffolds using freeform reversible embedding of suspended hydrogels (FRESH)

3D printing complex scaffolds using freeform reversible embedding of suspended hydrogels (FRESH)

Preservation and storage of prepared ballistic gelatine

The use of ballistic gelatine, generally accepted as a human muscle tissue simulant in wound ballistic studies, might be improved by adding a preservative (Methyl 4-hydroxybenzoate) which inhibits microbial growth. This study shows that replacing a part of the gelatine powder by the preservative does not significantly alter the penetration depth of projectiles. Storing prepared blocks of ballistic gelatine over time decreased the penetration depth of projectiles. Storage of prepared gelatine for 4 week already showed a significant effect on the penetration depth of projectiles.

Investigation of bullet penetration in ballistic gelatin via finite element simulation and experiment

To qualitatively understand the deformation processes and damages in the human body caused by high-speed impact, we conducted experimental and computational investigations for bullet penetration into viscoelastic ballistic gelatin blocks. Because it is difficult to measure the strain rate-dependent material properties of viscoelastic gelatin blocks during high-speed impact, the material properties that are indirectly defined by the stress relaxation test were used for the computational simulation. We also conducted some firing experiments and analyzed the deformation processes of the structures. In particular, the passing through times and the shapes of the temporary and permanent cavities inside the ballistic gelatin blocks were analyzed and compared. This data reveals that the employed material models, with some modifications for the FE simulation, are sufficient for predicting the high-speed impact behaviors. To investigate the shapes of the permanent cavities and fragments made by bullets inside the gelatin blocks, two-dimensional sectional images were taken by an industrial CT scanner and a three-dimensional CAD model was constructed based on these images.

Effect of injection pressure and fluid volume and density on the jet dispersion pattern of needle-free injection devices

Needle-free injection devices improve vaccinator safety and optimise vaccine delivery time by eliminating the use of needles involved with traditional vaccination techniques. Of significant importance is a full understanding of the relationships that exist between the injection properties and the depth and shape of the injectate's dispersion. Work has been done to characterise the distribution of human needle-free injection devices, but little research has been conducted on livestock injections, which operate at much higher pressures and volumes. Therefore, the aim of this research was to characterise the injection profile of a livestock needle-free injection device while varying the injection pressure and fluid volume and density. Water and porcine circovirus vaccine were injected into ballistic gelatin blocks and the injection mechanism was captured using high-speed photography. The volume was varied between 1.0 and 2.5 ml and orifice pressure between 40 and 220 MPa. It was found that pressure influenced the depth of penetration, but had little effect on the shape of the injection profile. In contrast, the volume and density increased the penetration depth and varied the dispersion pattern. These results can be used to better understand how the injection profile of a needle-free injection device changes given an initial set of parameters. This will be important for developing administration protocols that successfully deliver intradermal, subcutaneous, and intramuscular livestock injections.