Search

The copper-using cultures of North America’s Archaic Period (10,000–3000 BP) have long been an archaeological enigma. For millennia, Middle and Late Archaic hunter-gatherers (8000–3000 BP) around the Upper Great Lakes region made utilitarian implements out of copper, only for these items to decline in prominence and frequency as populations grew and social complexity increased during the Archaic to Woodland Transition. From a cultural evolutionary perspective, the trajectory of North America’s copper usage presents a conundrum, as it is generally assumed that “superior” tools, i.e., metals, will replace inferior ones, i.e., stone. For well over a century, scholars have pondered the reason for the demise of copper technology that was once a wide-spread phenomenon. To address this question, an extensive archaeological experimental program was conducted which compared replica copper tools (spear points, knife blades, and awls) to analogous ones made of stone or bone to assess whether relative functional efficiency contributed to the decline of utilitarian copper implements. Here, the results of this three-part research program are presented in concert with population dynamics and ecological change to paint a broader picture of the complex interrelationships between the social, ecological, and technological spheres of past human behaviors. The synthesis of these approaches reveals that functional explanations—derived from experimental archaeology placed in an evolutionary framework—can shed much light on the trajectory of metal use in the North American Great Lakes.

AISI D2 steels are an interesting family of tool steels that generally have applications in knife blades, shaper blades, and forging and punching dies due to its optimum toughness, lower wear rate,...

Sharp force trauma is routinely encountered in forensic practice. Often the question is posed, how much pressure or energy would have been necessary to inflict a cut with a specific knife, in order to further characterize the perpetrator or determine his intent to cause harm. This paper investigates two knife blades and its individual pressures needed to cut through the epidermis and dermis. In order to examine the necessary force for cutting through the skin, we performed experiments on a piglet skin-on-gelatin phantom. Two similarly small knives-a paring knife with a serrated blade and a Swiss Army pocket knife with a smooth blade-were moved over the phantom surface using a mobile cutting apparatus with varying weight on the load arm with the knife. The depth of the cut was to be determined according to a scale from zero to three: grade 0 = no cut; grade 1 = cut into epidermis only; grade 2 = cut into dermis; grade 3 = complete transection of the entire skin. Each cut inflicted at a specific pressure force was assessed closely in order to ascertain depth, calculate the velocity, and ultimately determine the point at which a cut would inflict grade 3 damage. The smooth blade of a pocket knife needed at least 1900g pressure in order to slice through pig skin mounted on a thick gelatin block, whereas a serrated blade of a paring knife managed to cut into or through the dermis at a comparatively lower force of 700g. Our study shows that at the same cutting velocity, a significant difference in pressure is necessary to inflict the same degree of damage.

Delimbing of harvested wood is the first step towards obtaining finished products, where it is necessary to strain after achievement of maximum efficiency in the use of raw materials and quality improvement of the obtained assortment. Herewith, high-quality cleaning and minimization of damage of tree trunks is associated to a great extent with reliable operation of the delimbing and pull-through devices of logging machines that carry out both removal of branches and technological movement of wood. An intensive blunting of delimbing knives occurs in operation of the delimbing and pull-through device. As a result, the forces spent on delimbing increase and the process of stable cutting is disrupted. Partial cutting, and with an increase in pressure on the knives their cutting into a trunk and breaking out of limb occur, which reduce the quality of the harvested wood and lead to further intensification of wearing out of the cutting devices. The wearing out of knives is due to the action of a complex set of mechanical, chemical, temperature and other factors that accompany the technological process. This leads to a change in the dimensions of knife cutting edges. In order to improve the quality of delimbing and at that reduce the energy consumption, it is necessary to assess the influence of geometric and physico-chemical parameters of the cutting knives on their wear resistance, which will allow to theoretically justify the rational geometry of the cutting wedge and requirements for the physico-chemical characteristics of the recommended materials. The force interaction analysis of the cutting wedge with the cut limb has shown that, already at the beginning of the contact, the cutting blade is acted by the shock bending load, which, when peak values are reached, often leads to wearing out by chipping of sufficiently large microvolumes of the cutting edge. In this case, the wearing out of delimbing knives occurs mainly due to thedevelopment of microcracks, which are formed as a result of anti-plane deformation when applying stresses, and depends on the parameters of brittle crushing of materials. Moreover, the wearing out becomes more intense with contact with contaminated and wet, and in winter period frozen wood, which leads to intensification of corrosion and mechanical processes in the marginal areas of knife blades. The solution of the problem of increasing the wear resistance of delimbing knives can be provided by optimization of dimensions of knife wedge and formation of favorable physical and mechanical characteristics in the surface layer that minimize the wear intensity. The favorable dimensions of knife wedge were experimentally determined for this purpose. Complex alloyed chromium-nickel steel and rational modes of its heat treatment are proposed for the manufacture of delimbing knifes. Electrodeposition hardening is recommended as the surface treatment, which allows to optimize the surface roughness and form a favorable compressive stress in the marginal areas, thus providing high wear resistance of delimbing knives.For citation: Pilyushina G.A., Pamfilov E.A., Sheveleva E.V. Wear Resistance Improvement of Delimbing Knives of Multifunctional Logging Machines. Lesnoy Zhurnal [Russian Forestry Journal], 2019, no. 6, pp. 174–184. DOI: 10.17238/issn0536-1036.2019.6.174

Background: The presence of retained foreign bodies in the spinal canal has been reported in the literature. They are attributed to retained pieces of medical equipment after surgery, or, following trauma, to residual bullets, glass fragments, or knife blades. Although some retained materials do not cause any neurological deficits in the short run, others may become symptomatic months later. Case Description: A 2-year-old male presented with a history of intermittent fever and mild lower extremity weakness. Notably, the original infectious workup was negative. However, a noncontrast CT scan later documented a needle-shaped foreign body in the spinal canal at the T10 level. During the T10 laminectomy, a needle (i.e. from a medical syringe) was removed, the patient remained neurologically intact. The foreign body turned out to be a medical syringe needle tip. Conclusion: A 2-year-old male presented with fevers and mild lower extremity weakness attributed to an intraspinal needle tip found utilizing CT at the T10 level. T10 laminectomy allowed for removal of a small needle tip. This shows the importance of removing retained spinal foreign bodies to avoid further/future neurological injury, and/or the potential risks/complications of foreign body migration/sequestration.

Detailed information on skeletal trauma analysis of burned bone is important to ascertain the manner and cause of death in forensic casework. This research used three different knife types, one with a non-serrated blade, one a fine-serrated blade, and one a coarse-serrated blade, to inflict trauma to manually macerated Sus scrofa ribs (n = 240), and these ribs were later exposed to heat. Qualitative and quantitative analyses were conducted using macroscopic and microscopic techniques to assess specific characteristics of the cut marks. Differences in cut mark dimension and morphology of the ribs were investigated. After heat exposure, the cut marks on the rib samples remained recognisable and did not alter considerably. A level of dimensional and morphological preservation was reliant on the cutting action and the features of the knife blade as well as surrounding bone injury. The cut marks inflicted by the non-serrated blade remained recognisable despite exposure to the burning process. However, the cut marks inflicted by the coarse-serrated blade were likely to change significantly when exposed to heat. This study leads to two important results: (1) identification of pre-existing cut marks prior to heat exposure is possible in reconstructed burned bone fragments, and (2) cut marks from different types of knife blades showed dissimilar responses to heat. The outcomes obtained in this study stressed the need to adopt great care with the effects of heat on skeletal trauma analysis.

This study investigated the effect of the combination of basic electrolysed water (BEW) and slightly acid electrolysed water (SAEW) with ultrasound (US) for cleaning and sanitation of the knives used in slaughtering processes. The knives were sonicated in a US bath using two modes of operation (normal and sweep) in two steps: (i) 5 min with BEW and (ii) 10 min with SAEW at 35 °C. The microbiological counts and the possible changes in the physical structure of the knives were evaluated. The association BEW + SAEW + US, in the sweep mode, provided lower mesophilic, enterobacterial, Staphylococcus aureus and yeast counts when compared to the values recommended by the international legislation. In addition, these conditions removed all organic residues from the knife blades and promoted the highest migration rate of the residues to the US water bath (12.35 mg/L·min), without modifications in the knife blades. Thus, cleaning and sanitation of knives was feasible with the association of BEW + SAEW + US, which could be a useful alternative for the meat industry.

Edged weapons are frequently used to commit violent crimes (e.g., homicides, assaults or sequestrations). Following a stabbing, a fibre transfer might occur from the damaged fabric to the blade. It is crucial to investigate whether the target fibres were transferred to the blade as a result of the stabbing and if they are in association with the offence or whether they originate from another unrelated event (i.e., part of the background). The aim of this study is to explore the background population of fibres recovered on knife blades (police seizures and everyday knives) to help the interpretation of the results stemming from the analysis of the fibre evidence in crime cases involving the use of a bladed weapon. A population study was carried out to learn about the variety, the distribution and the size of the fibre population present on knife blades. After recovery using tapes lifting, stereoscopic examinations were performed to classify around 1500 fibres according to their colour and generic type. The most common colour/type combinations were: colourless/white cotton (31%), blue cotton (16%) and grey cotton fibres (11%). As blue fibres represent one of the most common colour group, they were selected to carry out a colour block study (based on microscopy observations and microspectrophotometry UV-vis spectra) to investigate the number and the size of the groups of indistinguishable fibres present on each blade. Only 30% of the knife blades presented more than one blue cotton fibre. The number of groups found per knife varied between 1 and 3, each group containing between 2 and 6 fibres. Findings revealed an important difference between the background fibre populations in terms of quantity of fibres, their morphology and spatial distributions - and the population of fibres transferred in a stabbing. The collected data can be used in a Bayesian approach to help with the interpretation of results.

AISI 440 is well known for its high strength and hardness with high carbon content. It is used for applications in bearings, knife blades. In this paper, the mechanical properties and the microstructureof AISI 440 steel with the tempering process is presented. The results showed that the microstructure of AISI 440 steel contains the mixture of martensite and the retained austentite, the austenite were expanded in the hardened martensited matrix. The mechanical properties like tensile strength, elongation and hardness were also discussed.

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link. 10.1016/j.scijus.2020.08.002. Bladed weapons are frequently encountered in violent crime offences including street based and armed robberies, murder, sexual assaults and terrorism. A study was conducted involving four frequently encountered clothing fabrics: t-shirt (knitted cotton), denim jeans (twill woven cotton), long sleeved top (knitted synthetic blend), and skirt (non-woven faux leather) and five knives to investigate any damage resulting from a downward stabbing motion, with 300 stabs in total. Any resultant penetrating severance damage was then photographed, measured and analysed. Statistical analysis revealed significant differences between the stab hole size and shape, as a consequence of the design of a bladed weapon (in particular, the tip shape) that caused it. There is a notable correlation between the Assure knife (rounded tip) and no resulting severance damage, as the fabric surfaces were not breached with this knife. This suggests a clear alternative to pointed tip knife blades. These findings will be of interest to investigators of knife crime offences, crime-reduction units, knife manufacturers and practitioners, who share the goal of identifying a safer alternative to conventional knife blade design.

Introduction The rationale for discarding the skin knife blade and replacing it with another blade for deeper dissection is to prevent bacteria that may be present on the skin from being carried into the deeper layers of the wound. This practice is very controversial because numerous, yet limited, studies exist that support and refute the findings. The purpose of this study was to directly compare the rate of contamination of a skin knife blade with a control blade. Methods We took the surface samples using Replicate Organism Detection and Counting plates of 344 knife blades immediately after making skin incision during the following four types of orthopaedic cases: total hip arthroplasty, total knee arthroplasty, lumbar spine surgery, and cervical spine surgery. At the same time, we sampled 344 control blades. The comparison of positives skin versus control, overall and within each subgroup was done using a bivariate two-sample z-test for the equality of proportions. Results Overall, 35 (5.1%) of the 688 specimens had a positive result. No difference was noted in the rate of positive cultures for the 344 skin blades 4.9% and the 344 control blades 5.2%. No differences were observed in the rate of positive specimens for skin blades (7.4%, 3.4%, 7.7%, and 3.9%) and control blades (2.5%, 4.1%, 7.7%, and 9.2%) for total hip arthroplasty, total knee arthroplasty, C spine, and L spine, respectively. No differences were observed regarding skin prep, room number, case order, room turnover time, or in-room to incision time. Staphylococus species was the predominant bacteria identified. Conclusion We found no evidence to support the theoretical advantage of changing the knife blade after making skin incision to avoid contamination. Contamination rates were the same for both the skin and control blades overall and for all subgroup analysis.

Background Bovine digital dermatitis (BDD) is a painful infectious foot disease of cattle, and much evidence implicates a pathogenic role for treponemes. This study measured the survival of BDD treponemes on hoof knife blades and tested the efficacy of relevant disinfectants under laboratory conditions. Methods Two strains of BDD treponemes were applied to hoof knife blades under aerobic conditions. Swabs were taken at different time points (10 minutes, one hour, two hours, four hours and 18 hours) and again after 20-second disinfection time with one of five disinfectants. Swabs were used directly for nested PCR to detect treponemes or inoculated for anaerobic growth, and subsequently examined using phase contrast microscopy and PCR. Results BDD treponeme DNA was detectable by nested PCR at all survival time points, and these organisms were culturable from hoof knives for two hours after exposure under aerobic conditions in the laboratory. Three of the five disinfectants—1 per cent volume per volume (v/v) FAM30®, 2 per cent weight per volume (w/v) Virkon® or 2 per cent (v/v) sodium hypochlorite—were effective at preventing visible growth of treponemes following 20-seconds contact, and 1 per cent (v/v) FAM30® also prevented detection of treponemes by PCR. Conclusion Treponeme viability of two hours under aerobic conditions suggests BDD treponemes could be transmitted between cows on hoof knives. It is therefore important to apply a disinfection protocol during foot-trimming; the authors have identified three common disinfectants that may be suitable.

Tool marks on bones induced by knife blades can be analysed morphometrically in order to enable an allocation of the suspected "inflicting weapon" to the particular morphology of the bone lesions. Until now, geometric morphometrics has not been used to analyse the morphology of knife lesions on fleshed bones in detail. By using twelve experimental knives and a drop weight tower, stab/cut injuries were inflicted on untreated pig ribs. The morphology of the experimentally produced lesions was subsequently recorded with three imaging techniques (μCT, macro photography and SEM) and analysed with different morphometric software (Amira, tps and Morpheus). Based on the measured distances between the walls of the kerf marks, which corresponded to the thickness of the blade, one could conclude to the respective blade thickness with a deviation of max. ±0.35mm and match the injuries to the knives. With subsequent reanalysis after maceration, an average shrinkage factor up to 8.6% was observed. Among the three imaging techniques used in this study, μCT was the most accurate and efficient technique, particularly because it represented the only non-destructive modality to document injuries without maceration, even though μCT is more expensive and time-consuming as well as less accessible than a macro SLR-camera or a SEM. For optimal characterizations of the blades' and kerfs' shapes the software tps proofed to be the best choice. Accordingly, geometric morphometrics could serve as a tool in forensic investigations concerning kerf marks.

In 2009, a new citrus viral disease caused by citrus yellow vein clearing virus (CYVCV) was first discovered in China, and now CYVCV is widely distributed in the field. CYVCV is transmissible by grafting and is spread by aphids from lemon to bean, and from bean to bean. However, whether CYVCV is transmitted by contaminated tools is unknown. In this study, the transmissibility of CYVCV with contaminated knife blades was investigated in sour orange and rough lemon. Three months after knife blade inoculation, CYVCV was detected in 16.5% of sour orange and 20.0% of rough lemon, respectively. Furthermore, six months post inoculation, the presence of CYVCV in sour orange and rough lemon was 23.3 and 20.0%, respectively. The results indicated that CYVCV is transmitted from citrus to citrus by contaminated knife blades.

Cutting operations for fresh-cut produce are usually accomplished by stainless steel knives. Waterjet cutting employs a very small stream of high-pressure water, and the type of nozzle, conveyor speed, and water pressure are the main factors that affect the quality of the cut. Two tests were conducted, cutting romaine lettuce either by an Urschel Translicer 2500 on a pilot process line using new or used and reconditioned (e.g., 3× used and sharpened) blades or by a KMT pilot waterjet system using standard or food-grade nozzles. Cut romaine showed whitening dehydration and red discoloration defects on cut surfaces. In both tests, cut romaine packaged commercially in a modified atmosphere had only minor differences in cut surface defects between blade and waterjet cutting. However, large differences due to cutting treatments were observed in cut romaine stored in bags without modified atmosphere at 2.5°C. In test 1, pieces were of very high quality with no differences between cutting method until 18 days at 2.5°C, when waterjet-cut pieces had higher visual quality with less discoloration than blade-cut pieces. New knife blades produced less damage to cut surfaces than used and reconditioned blades. The food-grade nozzle was superior to the standard waterjet nozzle. In test 2, discoloration appeared by day 9 in bags with no modified atmosphere at 2.5°C, and there were clear quality differences between cutting methods, with waterjet cutting using the food-grade nozzle better than blade cutting. There were no persistent differences in total bacterial counts between cutting methods. Potentially, improved cutting technology could reduce the need for extreme package atmospheres and/or ensure higher product quality with package leakers.

In this study we investigated the feasibility of using photon activation analysis (PAA) for the identification and individualization of crime scene evidence. We prepared six samples of stainless steel knife blades belonging to same or different knives and activated them with bremsstrahlung photons produced by a 30 MeV electron beam. A number of alloying elements and impurities were identified by gamma-spectroscopy. Comparing the ratios of concentrations of Ti, Cr, As, Co, and Ni, allowed us to easily attribute the samples. While more work is needed to optimize the analytical method and improve its sensitivity, we believe PAA can be successfully used for non-destructive evidence materials identification.

Earlier studies have found varying contamination rates using separate skin and deep knives in total hip (THA) and total knee (TKA) arthroplasty surgery. Previous studies were primarily conducted in the setting of concomitant use of laminar airflow and/or plastic adhesive draping. This has lead to conflicting conclusions regarding discarding the skin knife or not. This study evaluates the prevalence of contamination of a separate skin knife using modern antiseptic technique in primary THA and TKA without laminar airflow. Three knives from each primary THA and TKA surgery in non-laminar airflow operating rooms were collected: one used for the skin, one used for deeper tissues and one control knife. A total of 831 knife blades from 277 patients were cultured 12 days. Contamination of the skin knife was found in eight patients (2.8 %), contamination of the "deep" knife in five patients (1.8 %) and contamination of the control knife in five patients (1.8 %). No patient developed an infection with 1-year follow-up. Our findings suggest a very low rate of contamination of the skin knife using modern antiseptic technique without laminar airflow and/or plastic adhesive draping and do not support the use of a separate skin knife in arthroplasty surgery.

No description supplied

The combination of ultrasound (US) with chlorinated water (CW) and neutral detergent (ND) for simultaneous cleaning and sanitation of knives used during cattle slaughter was evaluated as a novel non thermal treatment. The US mode of operation, detergent concentration and time of treatment were studied and the results were compared with the conventional sanitation method used in meat industries. The conventional sanitation method promoted a decrease (p0.05) in the counts of mesophiles, Enterobacteriaceae, molds and yeasts, and a similar behavior was observed for US+CW (2.05±0.08mg/l of chlorine, and mode operation normal and sweep for 10min) and US+CW+ND (5ml/l and mode operation sweep for 5min) methods. Nevertheless, when detergent concentration and sonication time were increased (20ml/l, 15min) a strong decrease (p0.05) in the counts of mesophiles, Enterobacteriaceae, Staphylococcus aureus, molds and yeasts. Knife blades presented appropriate hygienic-sanitary properties in such conditions based on the Clean-Trace Surface Protein Plus™ test swab, which were better than the results obtained from conventional method. Kinetic modeling of knife sanitation was performed according to the transfer of organic matter, nitrogen and phosphorus during the process indicated highest migration rate of residues for US+CW+ND method, reaching 1.61mg/l·min. The hardness of knives' surface (Rockwell) was not changed by sonication using US+CW+ND method. These results indicate that both knife cleaning and sanitation processes could be performed in a unique step without the use of heat.

In addition to reconstructing the course of events, the medical examiner will often have to answer questions regarding the force necessary to inflict a certain injury in stabbing incidents. Several groups have examined the force needed to penetrate soft-tissue and clothing; however, no studies addressing the energy needed for penetrating ribs exist. Therefore, we decided to investigate this force on an animal model. Ribs from healthy, 8 to 10-month-old pigs were used as a substitute for human ribs. These ribs were then stabbed either transversely or longitudinally with two different pocket-knife blades, namely a Swiss Army pocket knife and a sturdier pocket knife (Classic Schnitzmesser, Herbertz Solingen) dropped from a drop-tower at defined heights and therefore defined energies. Longitudinally orientated stabs showed complete piercing of the ribs at approximately 11 Joules (J) or with a stabbing force in excess of 906 Newton (N) for both blade types. Transversely orientated stabs, however, displayed complete piercing between 11 and 16 J, or in excess of 1198 N, with the sturdy pocket knife tending to require a little more energy than the Swiss army pocket knife. Young adult porcine ribs are completely pierced by pocket knife blades at energies between 11 and 16 J. Assuming the porcine ribs are comparable to those ribs of young adult humans, our results indicate that a complete penetration of the chest wall through the ribs by stabbing with a pocket knife is rather easily achieved.

C athodic electrodeposition is currently used to protect the totality of the world automotive production against corrosion. Although this technology is highly competitive, some aspects, as the coverage of salient edges, could still be improved. Special paints containing flow modifiers have consequently been developed. Salt fog exposure on steel knife blades is the most frequently performed test to characterize the protection afforded by cataphoretic coatings against edge corrosion. In this study, a method based on electrochemical techniques, among which cathodic polarization and electrochemical impedance spectroscopy (EIS), is proposed for the special characterization of edge coverage in a faster and less restrictive way in comparison with salt fog spray. The combination of dc and ac measurements is also employed to accelerate the degradation process and to improve the fitting of EIS spectra. In order to validate these testing methods, different kinds of pretreatments and coatings were selected. The influence on edge corrosion of different parameters as the coating thickness and the amount of flow modifier were determined.

Unpacked cut chicken meat in retailis is intensely influenced by micro-environment. The aim of this paper is to determine closer the risks that exist in retail. The existing microbiological risk is determined by taking swabs from worker's hands, equipment and tools which came in direct contact with meat during work. The swabs were taken monthly during the two year period, in total number of 576. Swabs were tested by standard SRPS ISO methods:4833:2008 for determining aerobic colony count; 6888- 1:2009 for determining coagulase positive staphylococci; 16649-2:2008 for determining Escherichia coli; 15213:2011 for determining sulfitereducting clostridia and 6579:2008 for determining Salmonella spp. In 30% of the total number of taken swabs inadequate results were obtained, by category: 80% inadequate results of plastic sacs used for servicing the customers, 67% of the trenchers in shower cases, 33% of the worker's hands, 12% of the plastic meat cutting boards, 10% of meat grabbers and 9% of knife blades. The obtained results can be used to determine more closely the critical points of process steps in defining the standard operational and hygienic procedures for poultry meat handling in retail. Obtained results also can be used in risk analysis operation in retail sale of cut unpacked poultry meat.

A knife blade cutting experiment was performed to study the effect of clearance between two knife blades on cutting only one layer of a multi-layer thin film. The multi-layer thin films are made up of three major layers: a 0.1mm Polyethylene terephthalate (PET) layer, a 25 ~ 50 μm elastic plastic layer, and a 0.18 mm paper layer. The clearance between two knife blades is controlled by a micro manual stage. The cutting parameters are the clearance of knife blades, the edge of knife blades, and cutting speed. The relationships between layers to be cut and clearance between knife blades are measured using specific knife blades and a constant cut speed. Using the experimental results, several criteria for cutting paper layer are critically assessed. Through assessment of the criteria, the paper layer alone is practicably removed from multi-layer thin film. This experiment successfully provided a method to cut a specific layer but other layers of multi-layer thin film at once.

The process of decomposition of oil palm empty fruit bunches (EFB) can be accelerated by chopping the bunches into small pieces. In this study, EFB cutting tests were carried out using knife blades and an experimental cylinder-type chopping machine. The knife edge angle had a significant effect on the specific cutting force and the cutting energy. For the impact cutting, the specific torque requirement was affected by the peripheral cutting speed. Increasing the speed from 5.3 to 14.3 m s-1 reduced the cutting torque by 14.3%. An experimental chopping machine with a capacity of 3540 kg h-1 has been developed and tested for the empty fruit bunches.

A study is presented on the relative wear rates of two carbon steels, a Damascus steel and a stainless steel, using the Cutlery and Allied Trades Research Association (CATRA) of Sheffield England cutting test machine. The carbon steels and stainless steel were heat treated to produce a fine array of carbides in a martensite matrix. Tests were done at hardness values of HRC = 41 and 61. At HRC = 61 the stainless steel had slightly superior cutting performance over the carbon steels, while at HRC = 41 the Damascus steel had slightly superior cutting performance.

Objective:To discuss the management and to review the literature regarding retained knife blades in the head and neck.Case report:We present three cases in which patients presented with retained knife blades in the head and neck region; in two of these, the diagnosis was delayed by more than eight weeks. In all patients, the retained knife blade was removed through the pathway of insertion, without significant sequelae.Discussion:The methods of removal, appropriate radiological investigations and patient profiles are discussed.Conclusions:We propose that radiography be performed on all patients presenting with facial stab injuries which are anything more than superficial. We further suggest that the direct extraction of sharp objects through the pathway of insertion is safe if radiological studies show no risk of vascular injury.

Knives are among the weapons most frequently involved in criminal cases. They represent the most encountered category of weapons in Swiss homicide cases (completed and attempted homicides considered) and are also frequently employed in assault cases, notably bodily injuries. Whenever a knife is involved in a stabbing event, DNA and fingerprints may be sought. When garments are damaged, fibres can also be investigated. Fibres from the victim's garments might transfer onto the blade of the knife used in the assault and can thus provide useful information to determine whether a particular weapon could have be used to stab the victim. This study simulates vertical stabbings into garments with the use of a special holding device. Different types of knives and blades straight or serrated were used as weapons. Two garments presenting different shedding capacities and garment structures were also considered for the simulations. The distribution of fibres transferred onto the blade (number and position) was recorded for each simulation performed. Sequences of stabbings into the two garments were also carried out to assess whether the order of the stabs could be determined. Several parameters were considered, notably the distribution of fibres transferred onto the blade. The transfer of fibres inside the stab damage ballistic soap was used in this study and on the area near the second damage was also investigated. This study provides new insight into the interpretation of fibres transferred onto knives after a single stab or a sequence of stabbings and into determining the stabbing sequence. Finally, the study brings some guidelines for the search and recovery of fibres on the crime scene and on the blades of knives.

The aim of this study was to re-assess whether the use of a ‘one-knife technique’ can be considered as safe as the alternative practice of using separate skin and inside knives for elective orthopaedic surgery. A total of 609 knife blades from 203 elective orthopaedic operations, with equal numbers of skin, inside and control blades, were cultured using direct and enrichment media. We found 31 skin blades (15.3%), 22 inside blades (10.8%), and 13 control blades (6.4%) gave bacterial growth. Of the 31 contaminated skin blades only three (9.7%) had growth of the same organism as found on the corresponding inside blade. It is not known whether contamination of deeper layers in the remaining 90% was prevented by changing the knife after the skin incision. The organisms cultured were predominantly coagulase-negative staphylococci and proprionibacterium species; both are known to be the major culprits in peri-prosthetic infection. Our study suggests that the use of separate skin and inside knives should be maintained as good medical practice, since the cost of a single deep infection in human and financial terms can be considerable.

A 1-year study was carried out to investigate the prevalence of Salmonella in two abattoir environments coded "A" and "B" in Gaborone, Botswana. The total number of environmental samples collected from abattoirs A and B was 250 and 300, respectively. The samples were taken from soils in the corrals, knife blades, saw blades, cattle-drinking water, cattle feces, and feed. Preenrichment, enrichment, and selective/differential media, which enabled the favorable growth of Salmonella, were used in the study. Salmonellae were present in all sampled environments. The most common serotypes found in the environment at abattoir A were E1, C1, C2, and B. Serotypes B, C1, C2, C3, and E1 were common in abattoir B. Antigenic characterization of the salmonellae isolates showed that Salmonella Anatum, Salmonella Azteca, Salmonella Saintpaul, Salmonella Cerro, and Salmonella Westhampton were predominant in abattoir A, whereas Salmonella Anatum, Salmonella Mbandaka, Salmonella Molade, Salmonella Reading, and Salmonella Oranienburg were dominant in abattoir B. Implementing hazard analysis critical control point principles in work procedures would definitely reduce the gross contamination taking place in abattoirs.

Methicillin-resistant Staphylococcus aureus (MRSA) is a pathogen that has developed resistance to beta-lactam antibiotics and has been isolated at low population numbers in retail meat products. The objectives of this study were to estimate the potential transfer of MRSA from contaminated retail pork products to food contact surfaces and to estimate the potential for human exposure to MRSA by contact with those contaminated surfaces. Pork loins, bacon, and fresh pork sausage were inoculated with a four-strain mixed MRSA culture over a range of populations from approximately 4 to 8 log, vacuum packaged, and stored for 2 weeks at 5°C to simulate normal packaging and distribution. Primary transfer was determined by placing inoculated products on knife blades, cutting boards, and a human skin model (pork skin) for 5 min. Secondary transfer was determined by placing an inoculated product on the contact surface, removing it, and then placing the secondary contact surface on the initial contact surface. A pork skin model was used to simulate transfer to human skin by placing it into contact with the contact surface. The percentages of transfer for primary transfer from the inoculated products to the cutting board ranged from 39 to 49%, while the percentages of transfer to the knife ranged from 17 to 42%. The percentages of transfer from the inoculated products to the pork skin ranged from 26 to 36%. The secondary transfer percentages ranged from 2.2 to 5.2% across all products and contact surfaces. Statistical analysis showed no significant differences in the amounts of transfer between transfer surfaces and across cell concentrations.

A series of stab-penetration tests were carried out using model knife blades with different degrees of sharpness. Target blocks of flesh simulant were penetrated by the knife blades at constant low velocity and the penetration force was monitored. PSDB 10/93, a test protocol for stab-resistant body armour, recommends a modelling clay (Roma Plastilina) as a flesh simulant. From the stab-penetration tests it was found that Roma Plastilina has poor resemblance to flesh, and a simulant such as gelatine is more realistic. Bowie knife blades are specified in the test protocol while kitchen knives appear to be the most common in real incidents. More importantly, no required blade sharpness is specified in the test protocol, an aspect that could lead to inconsistencies in test results.

An experimental apparatus has been built that provides information on forces associated with slitting plastic films. The apparatus uses commercially available scissors as an analogue to the counter-rotating knife blades used in industry. Cutting forces were measured using sharp and worn blades at a range of slitting speeds from 0.05–2.5 m s−1. Two important film-base materials were studied; the first was polyethylene terephthalate (PET) and the second, acetal butylate. The influences of speed and knife-edge radius were measured for each base material. For the PET-based film, the forces increased as the blade became dull and decreased with cutting speed. At low speeds, the force required to cut the acetal butylate film was independent of speed, but a sharp decrease in force was observed at a speed that depended upon the blade sharpness. An empirical model for the slitting process has been developed that can estimate the forces measured.

Graffiti was one of the most visible forms of popular resistance to President MacMahon’s revocation of Jules Simon’s republican government on 16 May 1877, to the naming of a prime minister from the minority monarchist party, and to the dismissal of the Chamber of Deputies. For the five months of this foundational political crisis and ensuing election campaign, presidential posters and those of official candidates were crossed out, torn down, soiled or written on with ironic expressions. Messages of mockery, conveying humour of a scatological or pornographic bent, were engraved with knife blades or drawn on the walls of many cities in France, especially Paris. Through this form of protest, which was iconoclastic in its content and sometimes in its style, a democratic political culture is unveiled that was profoundly anchored in the working class, in Paris and elsewhere, both geographically and sociologically. Abstract: Les graffitis ont constitue l’une des formes les plus spectaculaires de resistance populaire au renvoi par Mac-Mahon du cabinet republicain de Jules Simon le 16 mai 1877, a la nomination d’un ministere minoritaire et a la dissolution de la Chambre des deputes. Pendant les cinq mois que durerent cette crise politique fondatrice et la campagne electorale qui s’ensuivit, les affiches presidentielles et celles des candidats officiels furent biffees, arrachees, souillees ou leur contenu complete par des mots ironiques ou injurieux. Des messages railleurs, porteurs d’un humour a teneur scatologique ou pornographique, furent ecrits a la pointe du couteau ou dessines sur les murs de nombreuses villes de France, a commencer par Paris. A travers ce mode de protestation iconoclaste sur le fond comme parfois sur la forme se devoile une culture politique democratique profondement ancree dans les classes populaires parisiennes, mais aussi au-dela, tant geographiquement que sociologiquement.

Nine Mayan obsidian knife blades from two Late Classic (i.e. 700–900 A.D.) sites in the Yucatan Peninsula, Mexico, have been analyzed by inductively coupled plasma emission spectroscopy (ICPES) for the elements Ca, Fe, K, Ba, La, Mn, Sr, Ti, Zn and Zr, Rb was analyzed by atomic absorption spectrophotometry. These data permit unique assignment of a volcanic obsidian source for each artifact. Obsidian for five of the blades originated from the Pachuca and Zinapecuaro-Ucareo localities near present-day Mexico City; obsidian for the other four was derived from El Chayal, a locality near present-day Guatemala City, Guatemala. These results indicate that extensive trade and supply networks existed during Late Classic times. From purely an analytical standpoint, these results demonstrate that ICPES is a potentially valuable tool in geo-archaeological studies.

In response to continued concerns regarding Listeria cross-contamination during the slicing of deli meats, a series of specially prepared grade 304 and 316 stainless steel kitchen knife blades was inoculated with a six-strain Listeria monocytogenes cocktail (10(8), 10(5), and 10(3) CFU per blade) composed of two weak, two medium, and two strong biofilm-forming strains. The blades were then attached to an Instron 5565 electromechanical compression analyzer and used to slice whole chubs of delicatessen turkey breast, bologna, and salami to entirety (30 slices) at a cutting speed of 8.3 mm/s. Homogenates of the slices in University of Vermont Medium were surface or pour plated with modified Oxford agar and then enriched. Listeria transfer from knife blades inoculated at 10(8) CFU per blade was logarithmic, with a 2-log decrease seen after 8 to 12 slices and direct counts obtained thereafter out to 30 slices. However, blades containing 10(5) and 10(3) CFU per blade typically yielded direct counts out to only 20 and 5 slices, respectively. Normalizing data on a log scale for the first 10 slices resulted in significantly greater Listeria transfer and "tailing" from grade 304 as opposed to grade 316 stainless (P0.05) for all three products. After 1 year of use, surface roughness values as determined by surface profilometry were significantly greater (P0.001) for grade 304 than for grade 316 stainless blades. Cutting force and blade sharpness were not significantly different (P0.05) within stainless steel grade (P0.05) for each product. However, significant differences in cutting force were seen between salami and turkey (P0.05) for grades 304 and 316 stainless, respectively. In addition to compositional differences in the deli meats and knife blades, wear and scoring on the blade likely affected Listeria transfer during slicing.

There is an immediate requirement for law enforcement and homeland security to identify concealed weapons which may present a threat to official personnel and the general public. This involves suicide bomb vests, handguns, knife blades, and other threatening weapons. The weapons may be composed of a large range of materials such as metals, nonmetals, plastics and explosives. The Homeland Security Advanced Research Projects Agency (HSARPA) and the National Institute of Justice (NIJ) are presently funding programs collectively covering all relevant portions of the electromagnetic spectrum and ultrasound in order to detect these weapons through the various materials that may be used to conceal these weapons This paper outlines the various imaging techniques being investigated and present results where available

A retained knife blade following a stab wound to the face is an uncommon injury that may give anxiety to the doctor managing the case. In 11 patients presenting with retained blades, simple withdrawal was associated with no untoward effect. In two patients the blade was not visible from the outside. The authors recommend that patients presenting with stab wound of the face are radiographed before discharge.

Objective. To describe cases of intra-orbital knife blade foreign body following stabs to the orbit, together with a novel technique for removal. Methods. Retrospective case series of 3 patients. Results. All 3 patients had knife blades embedded in the orbit as a result of assault. The blades assumed the same direction within the orbit with varying degrees of depth, one causing serious vascular injury. In 2 cases the globes were intact after foreign body removal, with good visual outcomes. The third patient required enucleation. Two of the 3 knife blades were removed using a ‘double bone nibbler’ technique. The third was embedded without a handle and required removal with minor manipulation of the globe. Conclusions. Thorough investigation for vascular injury must be done before any attempted surgical removal. Visual outcomes can be good after removal of a knife blade foreign body. The double bone nibbler technique is promising for the controlled removal of embedded blades that are rigidly fixed.

Study Design. Four cases in which, during standard laminectomies, knife blades brokes deep into the disc space are reported. Summary of Background Data. These broken knife blades could not be removed at the time of initial operations. Results. Follow-up studies indicated further anterior migration of retained fragments in two cases after ambulation. Conclusions. Because of the potential hazards of late intraabdominal visceral or vascular injuries, removal of sharp retained fragments at another session is recommended

We recently encountered a 21-year-old single, nulliparous woman who presented with vaginal pain and a raised body mass index. Pelvic examination failed because of pain and difficulty inserting a speculum. Radiography revealed two Stanley-knife blades in the pelvic region (Fig. 1). These were removed from the vagina under general anaesthesia, to reveal an intact vagina. She opted for early discharge, only to re-present two days later with another pair of Stanley-knife blades in the same location. Removal was again easy. She was transferred to psychiatric care, but discharged herself the following day after she was recognized by a doctor from another hospital where she had presented several times with similar complaints, receiving various unnecessary treatments. She declined expert help and defaulted from follow-up. Munchausen’s syndrome owes its name to Baron von Munchausen, the 18th century Ger

Radial keratotomy offers a unique opportunity to study corneal wound healing because the corneas are normal, the fine knife blades disrupt adjacent tissue minimally, no sutures are used, there is minimal inflammation, and few postoperative drugs are administered. We studied corneal wounds with a slit-lamp microscope as they healed from two weeks to three years after radial keratotomy in 84 eyes of 51 consecutive patients enrolled in the Prospective Evaluation of Radial Keratotomy (PERK) Study. One day after surgery, the incisions were surrounded by edema. At two weeks, a dense, gray, diffusely marginated opacity occupied 0.1 mm on both sides of the incision. At three months, the area adjacent to the incision was filled with discrete, fine, gray spicules that protruded at right angles from the incision. At six months, the gray cloudiness had completely disappeared, and the individual spicules were more prominent. By one year, the spicules were disappearing from the anterior portion of the incision and were concentrated primarily in the posterior part of the incisions. At two and three years, the incision scar was fainter and the spicules had disappeared from all but the deep posterior part of the wound. We believe that these spicules correspond to the reorganization of the stroma along the edges of the corneal incision. The persistence of the spicules suggests that wound healing in radial keratotomy may not be complete until two years or more after surgery.

The first paper in this series described the results of laboratory measurements and road evaluation tests on a series of tread stocks over a wide range of severities, and indicated the various advantages and limitations involved in the laboratory and road measurements. It is the purpose of the present paper to describe in greater detail the abrasion instrument used in these studies. The laboratory measurement of abrasion resistance was reviewed by Buist in 1950. The paper describes 21 laboratory abraders. Developments in abrasion instruments and methods which have since appeared in the literature have been primarily concerned with modifications and refinements on these basic types. A novel type of instrument described by Newton, Grinter and Sears, uses stationary knife blades to scrape a rotating rubber disc. The research group at the Emeryville Shell Development laboratories investigating characterization of elastomeric properties some years ago decided that its requirements in laboratory abrasion testing could best be satisfied by an abrader of the Dunlop-Lambourn type because of its versatility in providing control of angular velocity, load, slip, energy transfer, and temperature. Also, in the Lambourn abrader, the motor-driven vulcanizate wheel driving a braked abrasive wheel resembles the action of a driven tire rolling on a pavement. A given section of the tire tread surface is subjected to stressing and abrasion only during the portion of the cycle when in direct contact with the abrading surface. Cooling and relaxation occur during the portion of the cycle when the section is not in contact with the surface. Viscoelastic and abrasion mechanisms can operate in the laboratory at frequency levels approximating those encountered in road tests.

Pilcher 4 collected a group of cases from the l i terature in which the brain had been penetrated by a var ie ty of objects. The list of objects included knife blades, pi tchfork prongs, crochet hook, kni t t ing needles, splinters of wood, breech pins, an umbrella rib, surgical instruments, nails, carpet tack, automobile bolt, crowbar, oil-can spout and others. Two remarkable cases of metal l ic foreign bodies in the 3rd ventricle were reported by Schnitker 6 and by Greenwood. 3 In both of these cases the pat ients survived with remarkable recovery, surgical removal having been conducted in one of them. Another interesting case was tha t of Sherman 7 in which a brass foreign body was lodged in the brain s tem and removed successfully. Askenasy et al. 1 reported ~ cases of sewing needle in the brain after intervals of 23 and 54 years. Numerous other remarkable cases may be found in the li terature. In the ~ cases comprising the subject of the present report, the penetrat ing object was unusual both in nature and location. I n each case, the pat ient was injured by impalement upon the antenna of an automobile radio. Because of the association of these injuries with automobiles, the Nat iona l Safety Council was asked to review its records for any possible similar cases bu t none was found. 5 The case reported by Goald and Ronderos ~ is similar to Case 1 described herein and will be discussed later.

During the 1978 and 1979 field seasons in the Bache Peninsula region on the east coast of Ellesmere Island ... a number of artifacts mostly of European manufacture and presumably related to Norse activities was located in old Thule culture winter house ruins. The finds were made on three sites in the study area ... Skraeling Island (Chain mail sections, knife blades, boat rivets, iron point and copper pieces, woolen cloth), the Eskimobyen site on Knud Peninsula (barrel bottom, box section, copper piece), and Haa Island (ivory figurine). A general description of these finds, locational data, associated radiocarbon dates and material analyses are presented. ...