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Having previously reported on bunching via echo-enabled harmonic generation (EEHG) as an effective way to improve the longitudinal coherence in the NSLS-II storage ring [X. Yang et al., Sci. Rep. 12, 9437 (2022)], we demonstrate that this EEHG scheme can be easily adopted to any fourth generation diffraction-limited synchrotron light source with significant benefits. The advantage of the scheme is that it requires no change of the lattice and is fully compatible with other beamlines. Since the EEHG performance is mainly determined by the momentum compaction, beam emittances, and beta functions of a SR lattice, we have identified these crucial parameters and successfully built a generalized model, which can predict the performance of nearly any SLS. Regarding the fourth generation SLSs, momentum compactions are often significantly smaller; thus, to cover the x rays with a photon energy of up to 1 keV, we utilize a specific design, including a 250 nm seed-laser wavelength. Our model predicts that for most of the current and future fourth generation SLSs, the EEHG scheme can produce significant prebunching up to harmonic 200 and, thus, generate a few MW scale peak power at 1.25 nm wavelength.

ObjectivesThe surgical challenge with severe hindfoot injuries is one of technical feasibility, and whether the limb can be salvaged. There is an additional question of whether these injuries should be managed with limb salvage, or whether patients would achieve a greater quality of life with a transtibial amputation. This study aims to measure functional outcomes in military patients sustaining hindfoot fractures, and identify injury features associated with poor function.MethodsFollow-up was attempted in all United Kingdom military casualties sustaining hindfoot fractures. All respondents underwent short-form (SF)-12 scoring; those retaining their limb also completed the American Academy of Orthopaedic Surgeons Foot and Ankle (AAOS F&A) outcomes questionnaire. A multivariate regression analysis identified injury features associated with poor functional recovery.ResultsIn 12 years of conflict, 114 patients sustained 134 fractures. Follow-up consisted of 90 fractures (90/134, 67%), at a median of five years (interquartile range (IQR) 52 to 80 months). The median Short-Form 12 physical component score (PCS) of 62 individuals retaining their limb was 45 (IQR 36 to 53), significantly lower than the median of 51 (IQR 46 to 54) in patients who underwent delayed amputation after attempted reconstruction (p = 0.0351). Regression analysis identified three variables associated with a poor F&A score: negative Bohler’s angle on initial radiograph; coexisting talus and calcaneus fracture; and tibial plafond fracture in addition to a hindfoot fracture. The presence of two out of three variables was associated with a significantly lower PCS compared with amputees (medians 29, IQR 27 to 43 vs 51, IQR 46 to 54; p < 0.0001).ConclusionsAt five years, patients with reconstructed hindfoot fractures have inferior outcomes to those who have delayed amputation. It is possible to identify injuries which will go on to have particularly poor outcomes. Cite this article: P. M. Bennett, T. Stevenson, I. D. Sargeant, A. Mountain, J. G. Penn-Barwell. Outcomes following limb salvage after combat hindfoot injury are inferior to delayed amputation at five years. Bone Joint Res 2018;7:131–138. DOI: 10.1302/2046-3758.72.BJR-2017-0217.R2.

This study examines changing spatial patterns of botanical collections over a 400 year time frame, focussing on the collections at the Natural History Museum (BM) in comparison with global patterns. The Plant Collector Resource Database, which contains 68,000 collector records was used to generate 250,667 unique collector × country × date records. We observe an exponential increase in the number of collectors over time. The activities of collectors were investigated in 50-year time-slices from 1650–2000. We specifically considered the geographic scope of collections (i.e., countries in which collections were made), the depth of collections (i.e., the number of collectors per country) and the uniqueness of collections (i.e., the proportion not duplicated in other herbaria). Uniqueness was highest for the earliest time-slice. Collector activity is shown to be strongly influenced by extrinsic factors such as the development of trade and empire, which allowed for collections to expand in scope and depth, and ...

Introduction Extremity injuries predominate in warfare, however their nature, and overall burden to the individual and the health service is yet to be characterised for the UK military in the recent conflicts of Iraq and Afghanistan. Methods We reviewed the all extremity injuries in survivors from the Joint Theatre Trauma Registry (JTTR) between 2003 and 2014. All cases recorded in the JTTR between the invasion of Iraq on the 19th March 2003 and cessation of combat operations in Afghanistan on the 27th October 2014, were examined. Casualties who were killed in action or died from their wounds were excluded. All extremity injury codes were included, capturing patients with soft tissue injuries but no fracture or amputation. Results Of 2348 UK combatants surviving injury in Iraq and Afghanistan, 1813 (77%) had extremity injuries; of these 205 (11%) had at least one amputation at the wrist/ankle or more proximal. Trans-tibial was the most common level of limb loss. Eighty five casualties lost 2 limbs, 83 of these (98%) lost both lower limbs and 17 lost 3 limbs. Aside from amputations, there were 1530 fractures, 501 (33%) involving the upper limb and 1029 (67%) in the lower limb and pelvis. The tibia was the most frequently fractured bone. Of the lower limb fractures, 597 (58%) were open compared with 344 (69%) in the upper limb. Total Length of Stay (LOS) following extremity injury was 24,486 days or 69 years and 1 month; there were a total 2817 surgical episodes performed on extremities. Median length of stay Length of Stay (LOS) for major amputations (i.e. those at the wrist/ankle or more proximal) was 51 days (IQR 30–65) with a median of 7 surgical procedures on their limbs (IQR 5–9). In casualties with fractures but no amputation, median LOS was 13 days (IQR 6–25) with a median of 2 surgical procedures (IQR 1–4). Conclusion Utilising a dedicated injury database, this study illustrates for the first time in the United Kingdom military population, that the extremities are involved in the vast majority of combat injuries and the large surgical workload required for their treatment.

Open fractures and traumatic wounds represent a surgical challenge due to the risk of infection that can, at the extreme threaten life and limb but more commonly limit options for reconstruction. The treatment of these wounds requires removal of contamination and non-viable tissue in a way that minimizes further tissue damage, because healthy tissue in the wound bed is essential for microbial eradication. In more high-energy and complex wounds, particularly those associated with fractures, treatment requires a combined approach from both orthopaedic and plastic surgical teams. Initial surgical treatment is an urgent priority and must involve senior surgeons from both specialities. This combined approach can maximize potential for reconstruction and rehabilitation while minimizing risk of complications like infection and amputation. However, this combined approach requires significant resources and therefore these injuries should be managed in specialist centres appropriately staffed and resourced.

It is thought likely that the next conflict in which the Naval Service is closely engaged will show greater similarity to the Falklands War (Operation CORPORATE) of 35 years ago than to the recent, prolonged, counter-insurgency operation in Afghanistan (Operation HERRICK). This study uses registry data to examine casualties sustained on Op CORPORATE and compares the injury severity of survivors with that observed on Op HERRICK. Because of their mechanistic consistency, dismounted gunshot wound (GSW) casualties are used as the cohorts for comparison.This report details the first systematic quantitative analysis of Op CORPORATE casualties. The analysis suggests that, at least amongst those dismounted casualties injured by GSW, more severely injured casualties survived during Op HERRICK than during Op CORPORATE. Allowing for the different operational scenarios and the significant differences in the provision of medical care, it can be concluded that these differences were not as marked as might have been expected and that, overall, survival outcomes approached those seen more recently in Afghanistan.

Sir Gilbert Blane (1749-1834) was a Medical Officer in the Royal Navy who saw action against both the French and Spanish fleets, and later served as a Commissioner on the Sick and Wounded Board of the Admiralty. His work to improve the living conditions and health of sailors, and the significant reductions in sickness rates this achieved, brought him national recognition and honoursIn 1830, Sir Gilbert Blane established a legacy with the Royal College of Surgeons of England for the award of a Gold Medal in his name to be awarded to medical officers ‘who have brought about an advancement….or improvement in any matter affecting the health or living conditions of Naval personnel’. The first two Gilbert Blane medals were awarded in 1832, and the eponymous award continues to this day, 182 years after his death.

The aim of this study was to characterise severe open tibial shaft fractures sustained by the UK military personnel over 10 years of combat in Iraq and Afghanistan. The UK military Joint Theatre Trauma Registry was searched for all such injuries, and clinical records were reviewed for all patients. One hundred Gustilo–Anderson III tibia fractures in 89 patients were identified in the 10 year study period; the majority sustained injuries through explosive weapons (63, 68 %) with the remainder being injured from gunshot wounds. Three fractures were not followed up for 12 months and were therefore excluded. Twenty-two (23 %) of the remaining 97 tibial fractures were complicated by infection, with S. aureus being the causative agent in 13/22 infected fractures (59 %). Neither injury severity, mechanism, the use of an external fixator, the need for vascularised tissue transfer nor smoking status was associated with subsequent infection. Bone loss was significantly associated with subsequent infection (p

The management of trauma patients has changed radically in the last decade, and studies have shown overall improvements in survival. However, reduction in mortality for the many may obscure a lack of progress in some high-risk patients. We sought to examine the outcomes for hypotensive patients requiring laparotomy in UK military and civilian cohorts.We undertook a review of two prospectively maintained trauma databases: the UK Joint Theatre Trauma Registry for the military cohort (February 4, 2003, to September 21, 2014) and the trauma registry of the Royal London Hospital major trauma center (January 1, 2012, to January 1, 2017) for civilian patients. Adults undergoing trauma laparotomy within 90 minutes of arrival at the emergency department (ED) were included.Hypotension was present on arrival at the ED in 155 (20.4%) of 761 military patients. Mortality was higher in hypotensive casualties (25.8% vs. 9.7% in normotensive casualties; p0.001). Hypotension was present on arrival at the ED in 63 (35.7%) of 176 civilian patients. Mortality was higher in hypotensive patients (47.6% vs. 12.4% in normotensive patients; p0.001). In both cohorts of hypotensive patients, neither the average injury severity, the prehospital time, the ED arrival systolic blood pressure, nor mortality rate changed significantly during the study period.Despite improvements in survival after trauma for patients overall, the mortality for patients undergoing laparotomy who arrive at the ED with hypotension has not changed and appears stubbornly resistant to all efforts. Specific enquiry and research should continue to be directed at this high-risk group of patients.Prognostic/Epidemiologic, level IV.

Introduction Gunshot wounding (GSW) is the second most common mechanism of injury in warfare after explosive injury. The aim of this study was to define the clinical burden of GSW placed on UK forces throughout the recent Iraq and Afghanistan conflicts. Methods This study was a retrospective review of data from the UK Military Joint Theatre Trauma Registry (JTTR). A JTTR search identified records within the 12 year period of conflict between 19 Mar 2003 and 27 Oct 2014 of all UK military GSW casualties sustained during the complete timelines of both conflicts. Included cases had their clinical timelines and treatment further examined from time of injury up until discharge from hospital or death. Results There were 723 casualties identified (177 fatalities, 546 survivors). Median age at the time of injury was 24 years (range 18–46 years), with 99.6% of casualties being male. Most common anatomical locations for injury were the extremities, with 52% of all casualties sustaining extremity GSW, followed by 16% GSW to the head, 15% to the thorax, and 7% to the abdomen. In survivors, the rate of extremity injury was higher at 69%, with head, thorax and abdomen injuries relatively lower at 5%, 11% and 6% respectively. All GSW casualties had a total of 2827 separate injuries catalogued. A total of 545 casualties (523 survivors, 22 fatalities) underwent 2357 recorded surgical procedures, which were carried out over 1455 surgical episodes between admission to a deployed medical facility and subsequent transfer to the Royal Centre for Defence Medicine (RCDM) in the UK. This gave a median of 3 (IQR 2–5) surgical procedures within a median of 2 (IQR 2–3) surgical episodes per casualty. Casualties had a combined length of stay (LoS) of 25 years within a medical facility, with a mean LoS in a deployed facility of 1.9 days and 14 days in RCDM. Conclusion These findings define the massive burden of injury associated with battlefield GSW and underscore the need for further research to both reduce wound incidence and severity of these complex injuries.

BACKGROUND: The United Kingdom was at war in Iraq and Afghanistan for more than a decade. Despite assertions regarding advances in military trauma care during these wars, thus far, no studies have examined survival in UK troops during this sustained period of combat. The aims of this study were to examine temporal changes of injury patterns defined by body region and survival in a population of UK Military casualties between 2003 and 2012 in Iraq and Afghanistan. METHODS: The UK Military Joint Theatre Trauma Registry was searched for all UK Military casualties (survivors and fatalities) sustained on operations between January 1, 2003, and December 31, 2012. The New Injury Severity Score (NISS) was used to stratify injury severity. RESULTS: There were 2,792 UK Military casualties sustaining 14,252 separate injuries during the study period. There were 608 fatalities (22% of all casualties). Approximately 70% of casualties injured in hostile action resulted from explosive munitions. The extremities were the most commonly injured body region, involved in 43% of all injuries. The NISS associated with a 50% chance of survival rose each year from 32 in 2003 to 60 in 2012. CONCLUSION: An improvement in survival during the 10-year period is demonstrated. A majority of wounds are a result of explosive munitions, and the extremities are the most commonly affected body region. The authors recommend the development of more sophisticated techniques for the measuring of the performance of combat casualty care systems to include measures of morbidity and functional recovery as well as survival. LEVEL OF EVIDENCE: Epidemiologic study, level III. Language: en

The Natural History Museum, London (NHMUK) has embarked on an ambitious programme to digitise its collections. The first phase of this programme was to undertake a series of pilot projects to develop the workflows and infrastructure needed to support mass digitisation of very large scientific collections. This paper presents the results of one of the pilot projects – iCollections. This project digitised all the lepidopteran specimens usually considered as butterflies, 181,545 specimens representing 89 species from the British Isles and Ireland. The data digitised includes, species name, georeferenced location, collector and collection date - the what, where, who and when of specimen data. In addition, a digital image of each specimen was taken. A previous paper explained the way the data were obtained and the background to the collections that made up the project. The present paper describes the technical, logistical, and economic aspects of managing the project.

The Trauma and Injury Severity Score (TRISS) methodology is used in both the UK and US Military trauma registries. The method relies on dividing casualties according to mechanism, penetrating or blunt, and uses different weighting coefficients accordingly. The UK Military Joint Theatre Trauma Registry uses the original coefficients devised in 1987, whereas the US military registry uses updated civilian coefficients, but it is not clear how either registry analyzes explosive casualties according to the TRISS methodology. This study aims to use the UK Military Joint Theatre Trauma Registry to calculate new TRISS coefficients for contemporary battlefield casualties injured by either gunshot or explosive mechanisms. The secondary aim of this study is to apply the revised TRISS coefficients to examine the survival trends of UK casualties from recent military conflicts. Materials and Methods: The Joint Theatre Trauma Registry was searched for all UK casualties injured or killed in Iraq and Afghanistan by explosive or gunshot mechanisms between January 1, 2003 and December 31, 2014. Details of these casualties including injuries and vital signs were reviewed. Logistic regression analysis was performed to devise new TRISS coefficients; these were then used to examine survival over the 12 yr of the study. Comparing the predictions from the gunshot TRISS model to the observed outcomes, it demonstrates a sensitivity of 98.1% and a specificity of 96.8% and an overall accuracy of 97.8%. With respect to the explosive TRISS model, there is a sensitivity of 98.6%, a specificity of 97.4%, and an overall accuracy of 98.4%. When this updated and mechanism-specific TRISS methodology was used to measure changes in survival over the study period, survival following these injuries improved until 2012 when performance was maintained for the last 2 yr of the study. Conclusion: This study for the first time refines the TRISS methodology with coefficients appropriate for use within combat casualty care systems. This improved methodology reveals that UK combat casualty care performance appears to have improved until 2012 when this standard was maintained.

Weapon development throughout history has focused on overmatch of the enemy’s capability by increasing the range and lethality of weapons. This process in the fourteenth Century meant the introduction of early firearms in Europe [1].

Beam breakup due to the hose instability for electron transport through hollow plasma channels is examined numerically and compared with analytical theory. Wakefields are simulated for different geometries, including cylindrical hollow channels and the “bubble” regime, and the simulations are carried out with advanced Particle-In-Cell algorithms. Results are compared to previous estimates for beams accelerated in a plasma.

1. No ballistic wound (with the possible exception of head and neck wounds) should be closed primarily. 2. Ballistic casualties need urgent systemic antibiotics. 3. Ballistic wounds should be irrigated with saline. 4. Wounds with retention of the round, fragmentation or bone strike should be regarded as higher energy transfer: consideration should be given to fasciotomy and more aggressive wound exploration. 5. Low energy transfer wounds should be considered for less aggressive surgical management if the wider healthcare context permits easy return to theatre. 6. Tissue excision should be performed after extension of the wound beyond the zone of injury.

Objectives The purpose of this study was to refine an accepted contaminated rat femur defect model to result in an infection rate of approximately 50%. This threshold will allow examination of treatments aimed at reducing infection in open fractures with less risk of type II error. Methods Defects were created in the stablised femurs of anaethetised rats, contaminated with Staphylococcus aureus and then debrided and irrigated six hours later. After 14 days, the bone and implants were harvested for separate microbiological analysis. This basic model was developed in several studies by varying the quantity of bacterial inoculation, introducing various doses of systemic antibiotics with and without local antibiotics. Results The bacterial inoculation associated with a 50% infection rate was established as 1 × 102 colony forming units (CFU). With an initial bacterial inoculum of 1 × 105 CFU, the dose of systemic antibiotics associated with 50% infection was 5 mg/Kg of cafazolin injected sub-cutaneously every 12 hours, starting at the time of the first debridment and continuing for 72 hours (seven doses). The systemic dose of cafazolin was lowered to 2 mg/Kg when antibiotic polymethyl methacrylate beads were used concurrently with the same amount of bacterial inoculation. Conclusion This model of open fracture infection has been further refined with potential for local and systemic antibiotics. This is a versatile model and with the concepts presented herein, it can be modified to evaluate various emerging therapies and concepts for open fractures. Cite this article: Bone Joint Res 2014;3:187–92.

Objectives: Local delivery allows a high concentration of antibiotics to be achieved in the wound while avoiding the side effects and cost of systemic administration. Beads molded from polymethylmethacrylate cement are commonly used for local antibiotic delivery but are not ideal. The purpose of this study was to determine whether a bioabsorbable gel delivering vancomycin and gentamicin is more effective in reducing infection than beads delivering vancomycin and tobramycin. Methods: This study used a segmental defect rat model contaminated with Staphylococcus aureus and treated with clinically relevant local antibiotic doses, delivered by gel or beads. In the gel group, 1 mL of gel containing gentamicin and vancomycin was spread throughout the wound. In the bead group, four 3-mm beads containing tobramycin and vancomycin were placed in the wound, 2 in the defect and 2 in the adjacent tissue envelope, there was also a control group that received no antibiotic treatment. After 14 days, bone and hardware was harvested for separate microbiological analysis. Results: There was a significantly lower infection rate in groups treated with antibiotics delivered by gel compared with those treated with either antibiotic beads or no antibiotics at all (P , 0.001). Quantitative cultures also demonstrate significantly less bacteria in the wounds treated with the gel than in the control or bead groups (P # 0.004). Conclusions: These results suggest that antibiotic delivery by a gel is superior to beads. The authors propose that antibiotic depot by polymethylmethacrylate antibiotic beads is less effective because this method has to rely on diffusion of the antibiotic from the high concentration close to the beads to all regions of the wound.

AimsA frequently-seen injury pattern in current military experience is traumatic lower limb amputation as a result of improvised explosive devices (IEDs). This injury can coexist with fractures involving the pelvic ring. This study aims to assess the frequency of concomitant pelvic fracture in IED-related lower limb amputation.MethodsA retrospective analysis of the trauma charts, medical notes, and digital imaging was undertaken for all patients arriving at the Emergency Department at the UK military field hospital in Camp Bastion, Afghanistan, with a traumatic lower limb amputation in the six months between September 2009 and April 2010, in order to determine the incidence of associated pelvic ring fractures.ResultsOf 77 consecutive patients with traumatic lower limb amputations, 17 (22%) had an associated pelvic fracture (eleven with displaced pelvic ring fractures, five undisplaced fractures and one acetabular fracture). Unilateral amputees (n=31) had a 10% incidence of associated pelvic fracture, whilst 30 % of bilateral amputees (n=46) had a concurrent pelvic fracture. However, in bilateral, trans-femoral amputations (n=28) the incidence of pelvic fracture was 39%.ConclusionsThe study demonstrates a high incidence of pelvic fractures in patients with traumatic lower limb amputations, supporting the routine pre-hospital application of pelvic binders in this patient group.

Objectives Severe extremity injuries are the most significant injury sustained in combat wounds. Despite optimal clinical management, non-union and infection remain common complications. In a concerted effort to dovetail research efforts, there has been a collaboration between the UK and USA, with British military surgeons conducting translational studies under the auspices of the US Institute of Surgical Research. This paper describes 3 years of work. Methods A variety of studies were conducted using, and developing, a previously validated rat femur critical-sized defect model. Timing of surgical debridement and irrigation, different types of irrigants and different means of delivery of antibiotic and growth factors for infection control and to promote bone healing were investigated. Results Early debridement and irrigation were independently shown to reduce infection. Normal saline was the most optimal irrigant, superior to disinfectant solutions. A biodegradable gel demonstrated superior antibiotic delivery capabilities than standard polymethylmethacrylate beads. A polyurethane scaffold was shown to have the ability to deliver both antibiotics and growth factors. Discussion The importance of early transit times to Role 3 capabilities for definitive surgical care has been underlined. Novel and superior methods of antibiotic and growth factor delivery, compared with current clinical standards of care, have been shown. There is the potential for translation to clinical studies to promote infection control and bone healing in these devastating injuries.

Re-reading Surg Capt Rick Jolly’s account of his time in command of the Ajax Bay facility I am reminded of our discussions as we collaborated on our reappraisal of medical support to Op CORPORATE, published last year in this Journal. After the sad news of his recent death I have paused to further

Blast and ballistic weapons used on the battlefield cause devastating injuries rarely seen outside armed conflict. These extremely high-energy injuries predominantly affect the limbs and are usually heavily contaminated with soil, foliage, clothing and even tissue from other casualties. Once life-threatening haemorrhage has been addressed, the military surgeon’s priority is to control infection. Combining historical knowledge from previous conflicts with more recent experience has resulted in a systematic approach to these injuries. Urgent debridement of necrotic and severely contaminated tissue, irrigation and local and systemic antibiotics are the basis of management. These principles have resulted in successful healing of previously unsurvivable wounds. Healthy tissue must be retained for future reconstruction, vulnerable but viable tissue protected to allow survival and avascular tissue removed with all contamination. While recent technological and scientific advances have offered some advantages, they must be judged in the context of a hard-won historical knowledge of these wounds. This approach is applicable to comparable civilian injury patterns. One of the few potential benefits of war is the associated improvement in our understanding of treating the severely injured; for this positive effect to be realised these experiences must be shared.

As mankind continues to extend technological boundaries, sensors must be improved in order to keep pace. The current problem that engineers and scientists face is how to actively monitor structures for damage. One possible method is to embed a triboluminescent material into a composite structure. Nearby sensors would monitor these structures for structural failure or impacts. This paper reports on recently completed research that incorporated the strongly triboluminescent europium dibenzoylmethide triethylammonium (europium tetrakis) into a selection of polymers, such as poly(methyl methacrylate). Additional work was completed to determine if europium tetrakis could be mixed with Cytoseal 60 and 280 to form a durable triboluminescent polymer for small-area sensors. Using a custom-built drop tower, the triboluminescent light yield and decay times was measured for the newly created triboluminescent polymers. In this paper, we have studied the effects of increasing poly(methyl methacrylate) (PMMA) concentration on the triboluminescent properties of europium dibenzoylmethide triethylammonium (EuD4TEA). The research shows that the amount of PMMA could be increased such that the EuD4TEA PMMA polymer could be sensitive to selective minimum energies. Thus, a functional triboluminescent polymer was successfully obtained for the first time.

The objective of this study is to compare antimicrobial effect of irrigation with chlorhexidine gluconate (CHG) to saline in an animal model.This study used a segmental defect rat femur model contaminated with Staphylococcus aureus and treated 6 hours after injury with debridement and irrigation with 60 mL of fluid delivered at low pressure. In study groups of 10 animals each, 3 concentrations of CHG (0.5%, 0.05%, and 0.005%) were used and a group irrigated with 0.05% CHG and then saline and a control group treated with saline only. After irrigation the wounds were closed, and the rats were recovered. Fourteen days later, bone and implants were harvested for separate microbiological analysis.There was no statistical difference detected between the subsequent presence or quantity of bacteria after irrigation, with aqueous CHG at a range of concentrations comparing irrigation with saline alone.This study does not support the use of CHG as an irrigant. This may be due to the antibacterial effect of CHG being offset by the associated host tissue toxicity. Host tissue damage from high irrigation pressures and cytotoxic solutions has been shown to allow bacteria to thrive. We believe this is due to a "rebound" of bacteria growth in a wound bed containing small quantities of necrotic tissue damaged by CHG exposure.