A method for screening groundwater vulnerability from subsurface hydrocarbon extraction practices.

This paper describes a new screening method for assessing groundwater vulnerability to pollution from hydrocarbon exploitation in the subsurface. The method can be used for various hydrocarbon energy sources, including conventional oil and gas, shale gas and oil, coal bed methane and underground coal gasification. Intrinsic vulnerability of potential receptors is assessed at any particular location by identifying possible geological pathways for contaminant transport. This is followed by an assessment of specific vulnerability which takes into account the nature of the subsurface hydrocarbon activity and driving heads. A confidence rating is attached to each parameter in the assessment to provide an indication of the confidence in the screening. Risk categories and associated confidence ratings are designed to aid in environmental decision making, regulation and management, highlighting where additional information is required. The method is demonstrated for conventional gas and proposed shale gas operations in northern England but can be adapted for use in any geological or hydrogeological setting and for other subsurface activities.

Declining trends in invasive orthopedic interventions for people with hemophilia enrolled in the Universal Data Collection program (2000-2010).

INTRODUCTION: Recurrent joint hemarthroses due to hemophilia (Factor VIII and Factor IX deficiency) often lead to invasive orthopedic interventions to decrease frequency of bleeding and/or to alleviate pain associated with end-stage hemophilic arthropathy. AIM: Identify trends in invasive orthopedic interventions among people with hemophilia who were enrolled in the Universal Data Collection (UDC) program during the period 2000-2010. METHODS: Data were collected from 130 hemophilia treatment centers in the United States annually during the period 2000-2010, in collaboration with the Centers for Disease Control and Prevention (CDC). The number of visits in which an invasive orthopedic intervention was reported was expressed as a proportion of the total visits in each year of the program. Invasive orthopedic interventions consisted of arthroplasty, arthrodesis, and synovectomy. Joints included in this study were the shoulder, elbow, hip, knee, and ankle. RESULTS: A 5.6% decrease in all invasive orthopedic interventions in all joints of people with hemophilia enrolled in the UDC program over the 11-year study period was observed. CONCLUSIONS: These data reflect a declining trend in invasive orthopedic interventions in people with hemophilia. Further research is needed to understand the characteristics that may influence invasive orthopedic interventions.

Equipping for risk: Lessons learnt from the UK shale-gas experience on assessing environmental risks for the future geoenergy use of the deep subsurface.

findings are presented from an investigation to improve understanding of the environmental risks associated with developing an unconventional-hydrocarbons industry in the UK. The EQUIPT4RISK project, funded by UK Research Councils, focused on investigations around Preston New Road (PNR), Fylde, Lancashire, and Kirby Misperton Site A (KMA), North Yorkshire, where operator licences to explore for shale gas by hydraulic fracturing (HF) were issued in 2016, although exploration only took place at PNR. EQUIPT4RISK considered atmospheric (greenhouse gases, air quality), water (groundwater quality) and solid-earth (seismicity) compartments to characterise and model local conditions and environmental responses to HF activities. Risk assessment was based on the source-pathway-receptor approach. Baseline monitoring of air around the two sites characterised the variability with meteorological conditions, and isotopic signatures were able to discriminate biogenic methane (cattle) from thermogenic (natural-gas) sources. Monitoring of a post-HF nitrogen-lift (well-cleaning) operation at PNR detected the release of atmospheric emissions of methane (4.2 ± 1.4 t CH4). Groundwater monitoring around KMA identified high baseline methane concentrations and detected ethane and propane at some locations. Dissolved methane was inferred from stable-isotopic evidence as overwhelmingly of biogenic origin. Groundwater-quality monitoring around PNR found no evidence of HF-induced impacts. Two approaches for modelling induced seismicity and associated seismic risk were developed using observations of seismicity and operational parameters from PNR in 2018 and 2019. Novel methodologies developed for monitoring include use of machine learning to identify fugitive atmospheric methane, Bayesian statistics to assess changes to groundwater quality, a seismicity forecasting model seeded by the HF-fluid injection rate and high-resolution monitoring of soil-gas methane. The project developed a risk-assessment framework, aligned with ISO 31000 risk-management principles, to assess the theoretical combined and cumulative environmental risks from operations over time. This demonstrated the spatial and temporal evolution of risk profiles: seismic and atmospheric impacts from the shale-gas operations are modelled to be localised and short-lived, while risk to groundwater quality is longer-term.

Practical methods for the measurement of logP for surfactants.

Hydrophobicity is a commonly used parameter in quantitative structure activity relationships. The ability to determine the octanol-water partition coefficient (logP) empirically for non-ionizing, non-surfactant type chemicals using traditional stir-flask methods has been successful and well documented. In comparison the ability to measure logP for surfactants is considered impractical due to their amphiphilic nature, which gives them a tendency to form micelles and reside at the octanol-water interface. In this study we have shown that working with compounds below their critical micelle concentrations (CMC), at the experimental concentrations, it is possible to obtain experimental logP values for a series of sulphobetaines using the stir-flask method coupled with reversed phase-high performance liquid chromatography (RP-HPLC). Until now the ability to verify calculated logP values for surfactants has been limited. Measuring logP as described here can now be applied to other surfactants to validate existing and new modifications to the fragment method.

A baseline survey of dissolved methane in aquifers of Great Britain.

Interest in dissolved methane (CH4) concentrations in aquifers in England, Scotland and Wales ('Great Britain' or GB) has grown concurrently with interest in the exploitation of unconventional gas sources (UGS). Experience, mainly from North America, has shown the importance of a pre-production baseline against which changes possibly due to UGS extraction can be compared. The British Geological Survey, aided by water utilities, private users and regulators, has compiled a unique dataset for CH4 in groundwaters of GB. This focuses principally on areas where UGS exploration is considered more likely, as indicated by the underlying geology. All the main water supply aquifers (Principal aquifers) were targeted, plus Secondary aquifers where locally important. The average dissolved CH4 concentration across GB in the aquifers sampled was 45µg/l. Out of a total of 343 sites, 96% showed dissolved CH4 concentrations <100µg/l, 80% <10µg/l, and 43%<1µg/l. No site had a CH4 concentration above the US Department of the Interior suggested risk action level of 10,000µg/l. While most sites were sampled only once, a subset was monitored quarterly to determine the magnitude of seasonal or other variations. Generally these variations were minor, with 84% of sites showing variations within the range 0.5-37µg/l, but some aquifers where the porosity was primarily fracture-related showed larger changes (0.5-264µg/l). This may have been due to the nature of sampling at these sites which, unlike the others, did not have installed pumps. Since the regulatory compliance monitoring attending UGS operations will include the measurement of parameters such as dissolved CH4, it is essential that sampling methods are tested to ensure that reliable and comparable datasets can be obtained.

Global patterns of nitrate storage in the vadose zone.

Global-scale nitrogen budgets developed to quantify anthropogenic impacts on the nitrogen cycle do not explicitly consider nitrate stored in the vadose zone. Here we show that the vadose zone is an important store of nitrate that should be considered in future budgets for effective policymaking. Using estimates of groundwater depth and nitrate leaching for 1900-2000, we quantify the peak global storage of nitrate in the vadose zone as 605-1814 Teragrams (Tg). Estimates of nitrate storage are validated using basin-scale and national-scale estimates and observed groundwater nitrate data. Nitrate storage per unit area is greatest in North America, China and Europe where there are thick vadose zones and extensive historical agriculture. In these areas, long travel times in the vadose zone may delay the impact of changes in agricultural practices on groundwater quality. We argue that in these areas use of conventional nitrogen budget approaches is inappropriate.

The changing trend in nitrate concentrations in major aquifers due to historical nitrate loading from agricultural land across England and Wales from 1925 to 2150.

Nitrate is necessary for agricultural productivity, but can cause considerable problems if released into aquatic systems. Agricultural land is the major source of nitrates in UK groundwater. Due to the long time-lag in the groundwater system, it could take decades for leached nitrate from the soil to discharge into freshwaters. However, this nitrate time-lag has rarely been considered in environmental water management. Against this background, this paper presents an approach to modelling groundwater nitrate at the national scale, to simulate the impacts of historical nitrate loading from agricultural land on the evolution of groundwater nitrate concentrations. An additional process-based component was constructed for the saturated zone of significant aquifers in England and Wales. This uses a simple flow model which requires modelled recharge values, together with published aquifer properties and thickness data. A spatially distributed and temporally variable nitrate input function was also introduced. The sensitivity of parameters was analysed using Monte Carlo simulations. The model was calibrated using national nitrate monitoring data. Time series of annual average nitrate concentrations along with annual spatially distributed nitrate concentration maps from 1925 to 2150 were generated for 28 selected aquifer zones. The results show that 16 aquifer zones have an increasing trend in nitrate concentration, while average nitrate concentrations in the remaining 12 are declining. The results are also indicative of the trend in the flux of groundwater nitrate entering rivers through baseflow. The model thus enables the magnitude and timescale of groundwater nitrate response to be factored into source apportionment tools and to be taken into account alongside current planning of land-management options for reducing nitrate losses.

In vivo evaluations of a new thromboresistant polyurethane for artificial heart blood pumps.

To reduce the risk of thromboembolic complications in prosthetic blood pumps, we have developed a new segmented polyurethane elastomer. This material is unique because its mechanical properties for long-term durability and surface properties for biocompatibility have been separated and developed in two distinct materials. Improved thromboresistance is then obtained by a 1% concentration of a new polymeric surface-modifying additive blended with the base polyurethane before fabrication of the blood pump. To evaluate this material in vivo, we performed 10 implants, in calves, of the Pierce-Donachy prosthetic ventricle with blood-pumping sacs and cannulas fabricated from the new surface-modifying additive copolymer blend (Thoratec's BPS-215M). In four control implants the blood sacs and cannulas were fabricated from Ethicon's Biomer segmented polyurethane, which is the present clinical standard for most artificial hearts and circulatory support devices. The blood pumps were connected from the apex of the left ventricle to the descending aorta in male Holstein calves weighing 82 to 108 kg and were driven pneumatically in the full-to-empty mode with flows averaging 5 to 6 L/min. Each calf was medicated with aspirin and dipyridamole throughout the study period and was electively put to death after 4 weeks for evaluation of explanted blood sacs and for examination of the kidneys for infarction. All 10 explanted blood sacs made with the surface-modifying additive copolymer blend were shiny and completely free of thrombus. Three of the four explanted Biomer blood sacs showed visible red thrombus, and all four showed small areas of white thrombus. The average surface area of the Biomer blood sacs covered with thrombus was 45 +/- 32 mm2. Use of a semiquantitative scale to assess renal infarction demonstrated that nine of 10 animals with a surface-modifying additive copolymer blend blood sac had infarction less severe than the mean infarct score of the animals with a Biomer sac. The surface-modifying additive copolymer blend has excellent mechanical and physical properties necessary for use in artificial heart blood pumps. From these experiments, we conclude that the surface-modified polyurethane blend is superior to Biomer polyurethane in blood compatibility and in freedom from thromboembolic risk. This material is now approved by the Food and Drug Administration for investigational device exemption studies in the Pierce-Donachy prosthetic ventricle.

Topical agents in burn and wound care.

With any open wound infection may occur. Many factors such as age and general health status may increase the likelihood of infection, but the size and depth of the wound are critical factors in determining the chronicity of any wound. Infection greatly adds to the morbidity associated with open wounds. An infected wound not only heals more slowly, there is also the risk of systemic infection and even death. Infected wounds also scar more severely and are associated with more prolonged rehabilitation. Topical therapeutic agents have been shown to be effective in the management of open skin wounds. These agents may assist less complicated healing and decrease the conversion of a partial-thickness injury to a full-thickness injury, and thereby reduce wound-related morbidity. Common topical agents with suggestions for application are discussed in this review.

The natural (baseline) quality of groundwater: a UK pilot study.

Knowledge of the natural baseline quality of groundwaters is an essential prerequisite for understanding pollution and for imposing regulatory limits. The natural baseline of groundwaters may show a range of concentrations depending on aquifer mineralogy, facies changes, flow paths and residence time. The geochemical controls on natural concentrations are discussed and an approach to defining baseline concentrations using geochemical and statistical tools is proposed. The approach is illustrated using a flowline from the Chalk aquifer in Berkshire, UK where aerobic and anaerobic sections of the aquifer are separately considered. The baseline concentrations for some elements are close to atmospheric values whereas others evolve through time-dependent water-rock interaction. Certain solutes (K, NH(4)(+)), often considered contaminants, reach naturally high concentrations due to geochemical controls; transition metal concentrations are generally low, although their concentrations may be modified by redox controls. It is recommended that the baseline approach be incorporated into future management strategies, notably monitoring.

Influence of pressure supports on joint range of motion.

Burn patients often complain of restricted mobility following application of elasticized nylon anti-burn-scar supports. This study was designed to analyse the influence of this type of pressure garment on joint range of motion (ROM). Data were compiled from 80 burn-affected joints of 17 burn patients placed in a support for the first time. Joint ROM was measured directly prior to, and again immediately following, the donning of the pressure support. ROM was measured using standard goniometric techniques. Range of motion increased in 26 joints (32.5 per cent), decreased in 26 joints (32.5 per cent) and showed no change in 28 joints (35 per cent) after application of the pressure garment. There were no correlations between ROM results and age, time postburn and per cent TBSA in this population. Patients were also asked if movement felt any different after the support was applied. Their varied comments, such as movement felt easier or more difficult, were consistent with the actual ROM data. It appears that there is no predictably detrimental change in joint ROM due to the application of pressure garments.

Rehabilitation of burn patients with concomitant limb amputation: case reports.

Burn patients with associated limb amputations present demanding rehabilitation problems, many of which might be expected to lead to chronic difficulties. Therapeutic goals following limb amputation include oedema reduction, prevention of contracture (through positioning and range of motion), stump shaping, both pre- and post-prosthetic fitting strengthening exercises of the limb and trunk, and gait training. Some patients present problems that are associated with both the burn injury and the limb amputation that cause concern among the physical therapy staff. Some of these situations include intolerance of the stump to pressure or manipulation due to remaining open wounds or fragility of newly skin grafted areas on the residual limb or delayed gait or functional training due to wounds on other body surface areas. Delays in stump preparation or other treatment aims due to continued surgical procedures can be worrisome. A review of these patients indicates the possible difficulties that rehabilitation personnel may face when treating burn victims who required amputation. Effective rehabilitation of these patients can be achieved despite the noted concerns.

Development of a hybrid artificial pancreas with a dense polyurethane membrane.

We have synthesized a series of strong, elastomeric polyurethaneureas and have used them to fabricate non-porous film and hollow fiber membranes. The solvent cast membranes are non cytotoxic, angiogenic, and permeable to gases, nutrients, secretagogues, and cell products via purely concentration driven transport. Permeability to water, glucose, and protein increases monotonically with membrane water absorption above a threshold value. Water absorption increases with soft segment hydrophilicity, soft segment molecular weight, and soft segment volume fraction of the (dry) segmented polyurethanes. Cell lines (RAJI and MOPC-31C) and primary cells (porcine islets) contained within our membranes have been maintained in culture for up to 6 months with nutrients supplied only by the external media. Cells within membrane devices were protected from immune rejection when implanted into murine hosts. Simple, compact devices containing porcine islets restored normoglycemia and near normal response to glucose tolerance tests in diabetic mice for at least 2 months. Explants had a high degree of vascularization adjacent to the membrane, with little or no fibrous tissue. These properties, and the material's ability to support cell function and protect xenogeneic cells from immunologic rejection, suggest that it would be useful in the construction of hybrid artificial organs and in in vitro cell culture.

Pressure therapy for the control of hypertrophic scar formation after burn injury. A history and review.

Devastating functional problems can result from the formation of hypertrophic scar tissue after burn injury. Although a patient with burns may have several medical problems to contend with because of the injury, most ongoing rehabilitation difficulties are a consequence of the continual wound contraction that occurs in immature burn scars. Treatment of hypertrophic burn scar consists of several surgical options and of pressure therapy, which traditionally involves wearing garments made from elasticized fabric. This article reviews the treatment of hypertrophic scar tissue, with emphasis on its history and on nonsurgical methods of managing the burn scar.

Reasons for the selection of burn-scar-support suppliers by burn centers in the United States: a survey.

Several companies currently market anti-burn-scar pressure garments to burn centers. Because of the numerous available choices, decisions about the reasons for selecting a garment are often confusing to those who are responsible for ordering the supports. This study was conducted to assist in decision making about garment selection by determining the relative importance of various factors in selecting brands of anti-burn-scar supports. A survey questionnaire was sent to 101 randomly selected burn centers in the United States, asking about the reasons for their choice of pressure-support suppliers. Sixty-two survey (61%) respondents indicated factors used in selection of a manufacturer. The factors included ease of accessibility for orders (97%), ease of measurement methods (90%), reliability of fit with the first garment ordered (90%), ability to fashion either a nonstandard support (77%) or special options into a garment (76%), provision of measurement materials (65%), and costs of the support (63%). Availability of standard garment options (50%) and/or choice of colors (31%) were listed less frequently. Twenty-four burn centers (39%) use only one company for orders, whereas 20 (31%) use two, 9 (15%) use three, and 9 (15%) use four different suppliers. Industry responses to these findings were gathered and presented as well. The results of this survey would indicate that burn staff have viable options of pressure-garment suppliers to assist them in responding to the scar-control needs of their patients.

Quantitative threshold changes in cutaneous sensation of patients with burns.

Decreased cutaneous sensation is common after burn injury. This study was designed to quantitate threshold sensory loss with the use of a microcomputer-based sensory testing device that generated precisely controlled stimuli. Threshold evaluations of two-point discrimination, pinprick, warming, touch, and vibration were performed on patients with burns (n = 16) and on control subjects (n = 42). All threshold measures in patients with burns were elevated above those for control subjects; threshold measures that reached statistical significance were two-point discrimination, warming, touch, and vibration. Unburned sites on patients with burns had higher thresholds than sites on control subjects, though only vibration was significant. A significant correlation was found between the magnitude of touch and vibration thresholds in control subjects, but there was no similar correlation found in patients with burns. When controls for age were applied, touch and vibration thresholds remained significantly elevated above control levels, and decreases in significance for two-point discrimination and warming were noted. It was concluded that sensory function is reduced in patients with burns. Alternative mechanisms that may have caused the sensory changes were discussed.

Educational preparedness for physical therapists and occupational therapists in burn care.

The background of physical therapy (PT) and occupational therapy (OT) students in burn care training may be variable during their professional education. The purpose of this study was to evaluate whether professional programs in PT and OT are meeting the burn care educational needs of their students. PTs and OTs currently practicing in burn care were asked to give their opinion of the most important curricular topics related to burn care, report their perception of their own entry-level preparedness for burn care, recount therapy interns preparation for burn care internships, and recommend topics that should be included in a therapy program burn care curriculum. Therapists felt prepared in basic sciences and somewhat prepared in specific burn care practice topics. Study participants felt more prepared for burn practice if they completed an internship in burn care. Enhancing content on burn-related treatment interventions was the most common suggestion for curricular revision.

Cutaneous nerve distribution in adult rat hairy skin after thermal injury--an immunohistochemical study.

Regrowth of cutaneous nerves after thermal injury was examined in rat hairy skin with use of protein gene product 9.5, which has been shown to label nerves in skin preparations. Tissue biopsies were obtained from injured and control skin at postburn days 1, 7, 14, 28, and 120, fixed in 4% paraformaldehyde, cryoprotected, sectioned, and immunostained with rhodamine conjugated goat anti-rabbit immunoglobulin G. Immunoreactivity for protein gene product 9.5 was intense and illustrated the process of nerve regrowth in rat skin after thermal injury. No nerve growth was detectable in 1- and 7-day preparations. Variable regeneration was noted in 14-day preparations. The 28- and 120-day groups produced nerve counts that were similar to control sections. Results suggest that rat hairy skin has a capacity for nerve regrowth after thermal injury. Nerves were noted to regenerate from beneath the scar. Burn wounds in rats demonstrated vigorous cutaneous nerve regeneration.

Sensory loss over grafted areas in patients with burns.

We studied loss of cutaneous sensibility after grafting in 60 patients with burns who had applied for impairment assessment. Fifty-eight patients (97%) demonstrated markedly diminished or absent responses to sharp/dull, hot/cold, and light touch stimuli over grafted areas. However, all but one patient had intact perception over donor areas and over areas of healed (ungrafted) partial-thickness burns. Deep touch sensation was intact over both grafted and ungrafted areas in all patients. Loss of sensation was not related to patient age, burn size, or type of burn; nor did sensory loss correlate with the impairment rating received. Depth of burn injury appears to be the best predictor of altered sensation, and some abnormalities in patients appear inevitable after skin grafting. Patients should be counseled about possible outcomes. However, the decrease in sensation that was observed rarely contributed significantly to the long-term impairment rating of these burn victims.

Prosthetic use in patients with burns and associated limb amputations.

A review of 11 patients who sustained burns that were complicated by limb amputation was completed to determine their eventual ability to use prosthesis. Amputations included six below-elbow, four above-elbow, three below-knee, and three above-knee amputations. Ten of the 11 patients (91%) had open wounds on the stump limbs and nine patients (82%) required skin grafting procedures on the amputated limbs. Delays in prosthetic fitting because of continued surgeries, open wounds, skin grafts on the stump limb, and breakdown of the stump were identified. However, eight of these patients (73%) were eventually able to wear prosthetic devices. Fisher's exact test was used to test the influence of the number and site of the amputations and skin grafting on the stump on successful prosthesis use. None of these tested items were found to be significant. The results demonstrate that most patients with burns who require limb amputation can achieve successful prosthesis use.