The punched-out tissue complex (skin-bone "imprimatum") in shots from captive-bolt guns: does it act as a secondary projectile?

From the first half of the twentieth century to the present day, injuries and fatalities from captive-bolt livestock stunners are a major topic in forensic medicine. The vast majority of cases account for suicides with the frontal, temporal, parietal, and occipital regions being the most common sites of entrance (in descending order of frequency). Due to the limited length of the bolt, the corresponding wound channel within the braincase is only several centimeters long. It has been a controversial subject for a long time, whether the skin-bone complex punched out by the conically grooved end of the steel rod may act as a "secondary projectile" being propelled beyond the actual path of the bolt. To answer this question, experimental shots from various types of captive bolt-guns were fired to simulants. Video-documentation employing a high-speed motion camera showed that the punched-out pieces of skin and bone did not move further than the bolt. Thus, a secondary extension of the total wound channel could not be observed. However, the suction effect caused by the bolt's rearward movement may induce a slight retrograde displacement of the skin-bone complex

Rearward movement of the slide in semi-automatic pistols: a factor potentially influencing the configuration of muzzle imprint marks in contact shots.

A muzzle imprint mark is a highly diagnostic finding, which indicates a contact shot. In many cases, it also provides additional information on the type of the weapon used and on the way in which it was held at the time of firing. In semi-automatic pistols, some constructional elements constituting the muzzle plane move to the rear together with the slide, which may prevent them from causing a corresponding imprint close to the bullet entrance hole. The present study comprises 30 consecutive autopsy cases of fatal contact shots to the head inflicted with semi-automatic pistols. The imprint marks accompanying the entrance wounds were compared with the muzzle ends of the respective weapons both before and after retracting the slide. It turned out that in a considerable number of cases (3 out of 30), the retractable parts were not depicted or only to a minor degree as components of the imprint mark. In order to validate the presumed correlation, experimental shots were fired to composite models using pistols in which the movable and the stationary parts forming the muzzle plane were dyed with different paints. Thus, it could be demonstrated that the muzzle imprint preferentially mirrors the front sides of the stationary parts such as the barrel end, the recoil guide, and the gun housing. Immediately after discharge, the slide and the ballooning skin of the bullet entrance site move in the same direction. The stationary parts of the weapon block the expansion of the skin bulging towards the muzzle, so that the skin gets firmly pressed against them. The dynamic interaction between the gun and the entrance region resulting in a characteristic imprint mark could be visualized by the use of a high-speed motion camera recording test shots to different composite models

A patterned abrasion caused by the impact of a cartridge case may simulate an atypical muzzle imprint mark.

In contact shots, the muzzle imprint is an informative finding associated with the entrance wound. It typically mirrors the constructional components being in line with the muzzle or just behind. Under special conditions, other patterned skin marks located near a gunshot entrance wound may give the impression to be part of the muzzle imprint. A potential mechanism causing a patterned pressure abrasion in close proximity to the bullet entrance site is demonstrated on the basis of a suicidal shot to the temple. The skin lesion in question appeared as a ring-shaped excoriation with a diameter corresponding to that of the cartridge case. Two hypotheses concerning the causative mechanism were investigated by test shots: - After being ejected, the cartridge case ricocheted inside a confined space (car cabin in the particular case) and secondarily hit the skin near the gunshot entrance wound. - The ejection of the cartridge case failed so that the case became stuck in the ejection port and its mouth contacted the skin when the body collapsed after being hit

Fatal contact shot to the chest caused by the gas jet from a muzzle-loading pistol discharging only black powder and no bullet: case study and experimental simulation of the wounding effect.

In modern medico-legal literature, only a small number of publications deal with fatal injuries from black powder guns. Most of them focus on the morphological features such as intense soot soiling, blast tattooing and burn effects in close-range shots or describe the wound ballistics of spherical lead bullets. Another kind of "unusual" and potentially lethal weapons are handguns destined for firing only blank cartridges such as starter and alarm pistols. The dangerousness of these guns is restricted to very close and contact range shots and results from the gas jet produced by the deflagration of the propellant. The present paper reports on a suicide committed with a muzzle-loading percussion pistol cal. 45. An unusually large stellate entrance wound was located in the precordial region, accompanied by an imprint mark from the ramrod and a faint greenish discoloration (apparently due to the formation of sulfhemoglobin). Autopsy revealed an oversized powder cavity, multiple fractures of the anterior thoracic wall as well as ruptures of the heart, the aorta, the left hepatic lobe and the diaphragm. In total, the zone of mechanical destruction had a diameter of approx. 15 cm. As there was no exit wound and no bullet lodged in the body, the injury was caused exclusively by the inrushing combustion gases of the propellant (black powder) comparable with the gas jet of a blank cartridge gun. In contact shots to ballistic gelatine using the suicide's pistol loaded with black powder but no projectile, the formation of a nearly spherical cavity could be demonstrated by means of a high-speed camera. The extent of the temporary cavity after firing with 5 g of black powder roughly corresponded to the zone of destruction found in the suicide's body

Optically robust, highly permeable and elastic protein films that support dual cornea cell types

Damaged corneas can lead to blindness. Due to the worldwide shortage of donor corneas there is a tremendous unmet demand for a robust corneal replacement that supports growth of the major corneal cell types. Commercial artificial corneas comprise plastic polymers that do not adequately support diverse cell growth. We present a new class of protein elastomer-dominated synthetic corneas with attractive performance that intimately couple biologically active tropoelastin to mechanically robust and durable protein silk. Fabricated films substantially replicate the natural cornea physically and by interacting with both key cells types used in cornea repair. Performance encompasses optical clarity at high transmittance, compatible refractive index, substantial glucose permeability, compliant mechanical properties, and support of both growth and function of corneal epithelial and endothelial cells