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IntroductionHabitual smoking is highly prevalent in military populations despite its association with poorer training outcomes. Smoking imposes challenges on the immune and endocrine systems which could alter how smokers acutely respond to, and recover from, intensive exercise particularly over multiple days of training.MethodsOver a two-day period, 35 male British Army recruits (age 22±3 years; mass 76.9±8.0 kg; height 1.78±0.06 m; 15 smokers) completed a 16.1 km loaded march (19.1 kg additional mass) on the first morning and a best-effort 3.2 km‘log race’(carrying a 60 kg log between six and eight people) on the subsequent morning. Blood samples were obtained on waking and immediately postexercise on both days and analysed for C reactive protein (CRP), interleukin 6 (IL-6), testosterone to cortisol ratio and insulin-like growth factor 1 (IGF-1).ResultsIndependent of smoking group, the exercise bouts on both days evoked significant increases in IL-6 (p0.05).ConclusionsMilitary-specific tasks elicited inflammatory and endocrine responses, with systemic CRP and IGF-1 indicating that the physiological stress generated during the first training day was still evident on the second day. Despite the well-established impacts of smoking on resting levels of the markers examined, responses to two days of arduous military-specific training did not differ by smoking status.

Military personnel are required to complete physically demanding tasks when performing work and training, which may be quantified through the physical stress imposed (external load) or the resultant physiological strain (internal load). The aim of this narrative review is to provide an overview of the techniques used to monitor work and training load in military settings, summarise key findings, and discuss important practical, analytical, and conceptual considerations. Most investigations have focused upon measuring external and internal load in military training environments; however, limited data exist in operational settings. Accelerometry has been the primary tool used to estimate external load, with heart rate commonly used to quantify internal load. Supplemental to heart rate, psychophysiological and biochemical measures have also been investigated to elucidate aspects of internal load. Broadly, investigations have revealed that military training requires personnel to perform relatively large volumes of physical activity (e.g. averaging ∼15,000 steps·day

Military training is characterized by high daily energy expenditures which are difficult to match with energy intake, potentially resulting in negative energy balance (EB) and low energy availability (EA). The aim of this study was to quantify EB and EA during British Army Officer Cadet training. Thirteen (seven women) Officer Cadets (mean ± SD: age 24 ± 3 years) volunteered to participate. EB and EA were estimated from energy intake (weighing of food and food diaries) and energy expenditure (doubly labeled water) measured in three periods of training: 9 days on-camp (CAMP), a 5-day field exercise (FEX), and a 9-day mixture of both CAMP and field-based training (MIX). Variables were compared by condition and gender with a repeated-measures analysis of variance. Negative EB was greatest during FEX (−2,197 ± 455 kcal/day) compared with CAMP (−692 ± 506 kcal/day; p p −1·day−1) compared with FEX (1 ± 16 kcal·kg FFM−1·day−1; p = .002) and MIX (10 ± 7 kcal·kg FFM−1·day−1; p = .003), with no apparent difference between FEX and MIX (p = .071). Irrespective of condition, there were no apparent differences between gender in EB (p = .375) or EA (p = .385). These data can be used to inform evidenced-based strategies to manage EA and EB during military training, and enhance the health and performance of military personnel.

IntroductionThe purpose was to quantify physical performance in men and women during British Army Junior Entry (Army-JE), British Army Standard Entry (Army-SE) and Royal Air Force (RAF) basic training (BT).DesignProspective longitudinal study.Methods381 participants ((339 men and 42 women) n=141 Army-JE, n=132 Army-SE, n=108 RAF) completed a 2 km run, medicine ball throw (MBT) and isometric mid-thigh pull (MTP), pre-BT and post-BT. To examine changes in pre-BT to post-BT physical test performance, for each course, paired Student t-test and Wilcoxon test were applied to normally and non-normally distributed data, respectively, with effect sizes reported as Cohen’s D and with rank biserial correlations, respectively. A one-way between-subjects analysis of variance (ANOVA) (or Welch ANOVA for non-normally distributed data) compared performance between quartiles based on test performance pre-BT. Where the main tests statistic, p value and effect sizes identified likely effect of quartile, post hoc comparisons were made using Games-Howell tests with Tukey’s p value. Data are presented as mean±SD, with statistical significance set at pResultsDuring BT, 2 km run time improved by 13±46 s (−2.1%±8.1%), 30±64 s (−4.8%±12.3%) and 24±27 s (−4.5%±5.1%) for Army-JE, Army-SE and RAF, respectively (all pConclusionsChanges in physical performance were observed for the three fitness tests following the different BT courses, and recruits with the lowest strength and aerobic fitness experienced greatest improvements.

A plethora of empirical data support a positive (or “brighter”) pathway to optimal human functioning as specified within Basic Psychological Needs Theory (Ryan and Deci in Psychol Inq 11(4):319–33, 2000). Yet, far less is known about the negative (or “darker”) pathway, a process evoking of human dysfunction and ill-being (cf. Vansteenkiste and Ryan in J Psychother Integr 23(3):263, 2013). Further, debate surrounds the independence and interplay between psychological need satisfaction and psychological need frustration and how these dynamic constructs are experienced within individuals. In this work, variable and person-oriented analyses were employed to: (i) investigate the relationships between the basic psychological needs and symptoms of stress, depression and anxiety as well as with life satisfaction; and (ii) identify different psychological need profiles and their relationship with psychological function. Participants (N = 2236; M Age = 42.16 years; SD = 7.8) were UK-based operational firefighters who completed an online survey. Results of regression analyses showed a moderating effect of psychological need satisfaction on the relationship between need frustration and negative psychological symptoms. Latent profile analyses revealed five distinct basic psychological need profiles that carry implications for human psychological functioning. Some support for an asymmetrical relationship between need satisfaction and need frustration emerged (Vansteenkiste and Ryan in J Psychother Integr 23(3):263, 2013), yet, examples of above average need satisfaction and frustration scores were also observed. Worker profiles where psychological need frustration prevailed over need satisfaction had the poorest psychological health.

Dietary intake and physical activity impact performance and adaptation during training. The aims of this study were to compare energy and macronutrient intake during British Army Officer Cadet training with dietary guidelines and describe daily distribution of energy and macronutrient intake and estimated energy expenditure. Thirteen participants (seven women) were monitored during three discrete periods of military training for 9 days on-camp, 5 days of field exercise, and 9 days of a mixture of the two. Dietary intake was measured using researcher-led food weighing and food diaries, and energy expenditure was estimated from wrist-worn accelerometers. Energy intake was below guidelines for men (4,600 kcal/day) and women (3,500 kcal/day) during on-camp training (men = −16% and women = −9%), field exercise (men = −33% and women = −42%), and combined camp and field training (men and women both −34%). Carbohydrate intake of men and women were below guidelines (6 g·kg−1·day−1) during field exercise (men = −18% and women = −37%) and combined camp and field training (men = −33% and women = −39%), respectively. Protein intake was above guidelines (1.2 kcal·kg−1·day−1) for men and women during on-camp training (men = 48% and women = 39%) and was below guidelines during field exercise for women only (−27%). Energy and macronutrient intake during on-camp training centered around mealtimes with a discernible sleep/wake cycle for energy expenditure. During field exercise, energy and macronutrient intake were individually variable, and energy expenditure was high throughout the day and night. These findings could be used to inform evidenced-based interventions to change the amount and timing of energy and macronutrient intake around physical activity to optimize performance and adaptations during military training.

Wearable physical activity (PA) monitors have improved the ability to estimate free-living total energy expenditure (TEE) but their application during arduous military training alongside more well-established research methods has not been widely documented. This study aimed to assess the validity of two wrist-worn activity monitors and a PA log against doubly-labelled water (DLW) during British Army Officer Cadet (OC) training. For 10 days of training, twenty (10 male and 10 female) OCs (mean ± SD: age 23 ± 2 years, height 1.74 ± 0.09 m, body mass 77.0 ± 9.3 kg) wore one research-grade accelerometer (GENEActiv, Cambridge, UK) on the dominant wrist, wore one commercially-available monitor (Fitbit SURGE, USA) on the non-dominant wrist and completed a self-report PA log. Immediately prior to this 10-day period, participants consumed a bolus of DLW and provided daily urine samples, which were analysed by mass spectrometry to determine TEE. Bivariate correlations and limits of agreement (LoA) were employed to compare TEE from each estimation method to DLW. Average daily TEE from DLW was 4112 ± 652 kcal·day against which the GENEActiv showed near identical average TEE (mean bias ± LoA: -15 ± 851 kcal day ) while Fitbit tended to underestimate (-656 ± 683 kcal·day ) and the PA log substantially overestimate (+1946 ± 1637 kcal·day ). Wearable physical activity monitors provide a cheaper and more practical method for estimating free-living TEE than DLW in military settings. The GENEActiv accelerometer demonstrated good validity for assessing daily TEE and would appear suitable for use in large-scale, longitudinal military studies.

Aim: To develop evidence-based role-specific physical employment standards and tests for National Ambulance Resilience Unit (NARU) specialist paramedics.\ud \ud Methods: Sixty-two (53 men, 9 women) paramedics performed an array of (1) realistic reconstructions of critical job-tasks (criterion job performance); (2) simplified, easily-replicable simulations of those reconstructions and; (3) fitness tests that are portable and/or practicable to administer with limited resources or specialist equipment. Pearson’s correlations and ordinary least products regression were used to assess relationships between tasks and tests. Performance on reconstructions, subject-matter expert and participant ratings were combined to derive minimum acceptable job performance levels, which were used to determine cut-scores on appropriate correlated simulations and tests.\ud \ud Results: The majority of performance times were highly correlated with their respective simulations (range of r: 0.73-0.90), with the exception of those replicating water rescue (r range: 0.28-0.47). Regression compatibility intervals provided three cut-scores for each job-task on an appropriate simulation and fitness test.\ud \ud Conclusion: This study provides a varied and easily-implementable physical capability assessment for NARU personnel, empirically linked to job performance, with flexible options depending on organisational requirements.

OBJECTIVE: The aim of this paper was to describe an approach to implementing and integrating physical employment standards into an organizational procedure, to ensure the safe and effective supervision of physical fitness of workers in a physically demanding occupation, using a real-world example. METHODS: Using previously published cardiorespiratory, muscular strength, and endurance physical demands data from UK firefighters, a process to manage all levels of physical capability was developed with industry stakeholders. RESULTS: Performance standards and associated cut-scores relating to acceptable, uncertain, and unacceptable job performance, using a traffic-light style process, were agreed by stakeholders to ensure the safe and effective management of incumbent's physical fitness. CONCLUSIONS: This paper describes the processes involved in implementing a physical capability management procedure, for the administration of routine in-service physical employment standards and tests in the UK Fire & Rescue Service.

PURPOSE: To determine whether physical performance adaptation is impaired in smokers during early stages of military training, and to examine some of the putative mechanistic candidates that could explain any impairment.METHODS: We examined measures of oxidative stress (malondialdehyde (MDA), lipid hydroperoxides), inflammation (C-reactive protein (CRP), interleukin-6), antioxidants (Vitamins A, E and carotenes) and hormones (cortisol, testosterone, insulin-like growth factor-1) in 65 male British Army Infantry recruits (mean ± SD age: 21 ± 3 yr; mass: 75.5 ± 8.4 kg; height: 1.78 ± 0.07 m) at week 1, week 5 and week 10 of basic training. Physical performance (static lift, grip strength, jump height, 2.4 km run time and two-minute press up and sit up scores) was examined and lower-leg muscle and adipose cross-sectional area (CSA) and density measured by peripheral Quantitative Computed Tomography.RESULTS: Basic Military training, irrespective of smoking status, elicited improvement in all physical performance parameters (main time effect; P < 0.05) except grip strength and jump height, and resulted in increased muscle area and decreased fat area in the lower leg (P < 0.05). MDA was higher in smokers at baseline, and both MDA and CRP were greater in smokers during training (main group effect; P < 0.05), than non-smokers. Absolute performance measures, muscle characteristics of the lower leg and other oxidative stress, antioxidant, endocrine and inflammatory markers were similar in the two groups.CONCLUSIONS: Oxidative stress and inflammation were elevated in habitual smokers during basic military training, but there was no clear evidence that this was detrimental to physical adaptation in this population over the timescale studied.

Objective: To examine determinants of firefighting simulation test performance. Methods: Sixty-eight (63 male; 5 female) firefighters completed a firefighting simulation (eg, equipment carry, casualty evacuation) previously validated to test occupational fitness among UK firefighters. Multiple linear regression methods were used to determine physiological and physical attributes that best predicted completion time. Results: Mean (±SD) time taken to complete the simulation was 610 (±79) seconds. The prediction model combining absolute cardiorespiratory capacity (L min -1) and fat mass explained the greatest variance in performance and elicited the least random error (R = 0.765, R 2 = 0.585, standard error of the estimate [SEE]: ±52 seconds). Higher fitness and lower fat mass were associated with faster performance. Conclusions: Firefighter simulation test performance is associated with absolute cardiorespiratory fitness and fat mass. Fitter and leaner individuals perform the task more quickly. Work-based interventions should enhance these attributes to promote safe and effective operational performance.

Objective: To assess sensitivity and specificity of surrogate physical ability tests as predictors\ud of criterion firefighting task performance and to identify corresponding minimum muscular\ud strength and endurance standards. Methods: Fifty-one (26 male; 25 female) participants\ud completed three criterion tasks (ladder lift, ladder lower, ladder extension) and three\ud corresponding surrogate tests (One-repetition maximum (1RM) seated shoulder press; 1RM\ud seated rope pull-down; repeated 28 kg seated rope pull-down). Surrogate test standards were\ud calculated that best identified individuals who passed (sensitivity; true positives) and failed\ud (specificity; true negatives) criterion tasks. Results: Best sensitivity/specificity achieved were\ud 1.00/1.00 for a 35 kg seated shoulder press, 0.79/0.92 for a 60 kg rope pull-down and 0.83/0.93\ud for 23 repetitions of the 28 kg rope pull-down. Conclusions: These standards represent\ud performance on surrogate tests commensurate with minimum acceptable performance of\ud essential strength-based occupational tasks in UK firefighters.

OBJECTIVE: To assess the validity and reliability of a firefighting simulation test (FFST). METHODS: Sixty-nine operational firefighters completed a best-effort FFST on one occasion and 22 participants completed a further FFST. All participants completed a maximal treadmill test to determine cardiorespiratory fitness (VO2max). RESULTS: Time to complete the FFST demonstrated a strong inverse relationship with VO2max (r = -0.73), although the prediction error was high. Reliability of the FFST was high (r = 0.84, P = 0.01), demonstrating a coefficient of variation of 4.5%. CONCLUSIONS: The FFST demonstrated reasonable validity as a surrogate assessment of cardiorespiratory fitness for firefighting. The FFST also demonstrated good reliability. Given the apparent magnitude of the prediction error, the FFST would be best used as a training tool, rather than as a primary means of assessing cardiorespiratory fitness for firefighting.

Background: Aspects of the work environment influence employee well-being. However, it is unclear how employee lifestyle behaviours, health characteristics and well-being may differ within a broader occupational sector.Aims: To investigate the health characteristics, lifestyle behaviours and well-being of three Fire and Rescue Service (FRS) occupational groups that differ in shift work and occupational demands: operational firefighters (FF), emergency control (EC) and administrative support (AS) workers.Methods: Data were obtained via an online survey using previously validated questionnaires to assess health characteristics, lifestyle behaviours and perceived well-being. Differences between groups were explored, controlling for confounding variables, using analysis of covariance (ANCOVA) methods. Effect sizes are reported where appropriate to demonstrate clinical significance.Results: Four thousand five hundred and sixty-four FRS personnel volunteered, with 3333 (73%) completing the survey out of a total workforce of 60000 (8%). FF reported the lowest prevalence of chronic medical conditions (10%), compared with AS (21%) and EC (19%) workers. Total physical activity (PA) was 66% higher among FF compared with EC and AS workers. Components of sleep and self-rated health were independent predictors of well-being irrespective of FRS role.Conclusions: FF reported the highest levels of PA and highest perceptions of well-being, and the lowest prevalence of obesity and chronic medical conditions, compared with other FRS occupational groups. These findings may be used to inform FRS workplace intervention strategies.

Background: Habitual smoking is prevalent in military populations, but\ud whether smoking status influences physical fitness development during training is\ud not clear.\ud \ud Aims: We investigated the effect of smoking status on physical fitness\ud parameters during initial British Army Infantry training.\ud \ud Methods: Routine measures of physical fitness (2.4 km run time and\ud maximum number of press ups and sit ups in two minutes) were obtained in 1,182\ud male recruits (mean ± SD: age 20 ± 3 y, body mass 70.6 ± 9.8 kg, height 1.77 ± 0.07\ud m; 58% smokers) at weeks 1, 14 and 24 of initial military training. A linear mixed\ud model was used to identify differences in performance between smokers and nonsmokers over time.\ud \ud Results: Non-smokers performed significantly better than smokers in all\ud performance tests (P0.05). Run performance improved by 7% in non-smokers (estimated marginal\ud means with 95% confidence limits; 612 (608-616) s to 567 (562-572) s) and 8% in\ud smokers (622 (619-625) s to 571 (568-575) s). Press up performance improved by\ud 18% in non-smokers (48.3 (47.1-49.4) to 57.0 (55.6-58.3)) and 23% in smokers (44.1\ud (43.2-45.1) to 54.5 (53.3-55.6)) and sit up performance by 15% in non-smokers (57.3\ud (56.3-58.2) to 66.0 (64.9-67.2)) and 18% in smokers (53.8 (53.0-54.6) to 63.3 (62.3-\ud 64.3)).\ud \ud Conclusions: Smokers exhibited lower muscular and cardiorespiratory\ud endurance performance than non-smokers. Unexpectedly however, no significant\ud differences in improvement in performance indices were demonstrated between\ud smokers and non-smokers during military training.

Objective: To develop a systematic task analysis process for determination of minimum\ud acceptable job performance in arduous safety-related occupations. \ud \ud Methods: A task analysis\ud using modifications on established methods was completed in UK firefighters. Subject-matter\ud experts (all male) identified critical, physically arduous tasks generic to all UK firefighters\ud and developed individual, role-specific task simulations. Video footage and blinded voting\ud were used to determine minimum acceptable task performance. \ud \ud Results: Eight tasks were\ud identified in combination with role-specific variations, task simulations suitable for use in a\ud physical demands analysis and corresponding minimum acceptable performance.\ud \ud Conclusions: The bespoke steps highlighted here allow structured identification of taskspecific minimum performance standards and simulations from which physical employment\ud standards could be based. However, including a more divergent expert panel with respect to\ud age, sex and race would strengthen the applicability of this framework in future practice.

Background Injuries sustained by military recruits during initial training impede training progression and military readiness while increasing financial costs. This study investigated training-related injuries and injury risk factors among British Army infantry recruits.Methods Recruits starting infantry training at the British Army Infantry Training Centre between September 2008 and March 2010 were eligible to take part. Information regarding lifestyle behaviours and injury history was collected using the Military Pre-training Questionnaire. Sociodemographic, anthropometric, physical fitness and injury (lower limb and lower back) data were obtained from Army databases. Univariable and multivariable Cox regression models were used to explore the association between time to first training injury and potential risk factors.Results 58% (95% CI 55% to 60%) of 1810 recruits sustained at least 1 injury during training. Overuse injuries were more common than traumatic injuries (65% and 35%, respectively). The lower leg accounted for 81% of all injuries, and non-specific soft tissue damage was the leading diagnosis (55% of all injuries). Injuries resulted in 122 (118 to 126) training days lost per 1000 person-days. Slower 2.4 km run time, low body mass, past injury and shin pain were independently associated with higher risk of any injury.Conclusions There was a high incidence of overuse injuries in British Army recruits undertaking infantry training. Recruits with lower pretraining fitness levels, low body mass and past injuries were at higher risk. Faster 2.4 km run time performance and minimal body mass standards should be considered for physical entry criteria.

A minimum cardiorespiratory fitness standard was derived for firefighters following a metabolic demands analysis. Design and minimal acceptable performance of generic firefighting task simulations (i.e. hose running, casualty evacuation, stair climb, equipment carry, wild-land fire) were endorsed by a panel of operationally experienced experts. Sixty-two UK firefighters completed these tasks wearing a standard protective firefighting ensemble while being monitored for peak steady-state metabolic demand and cardiovascular strain. Four tasks, endorsed as valid operational simulations by ≥90% of participants (excluding wild-land fire; 84%), were deemed to be a sufficiently valid and reliable basis for a fitness standard. These tasks elicited an average peak steady-state metabolic cost of 38.1 ± 7.8 ml kg−1 min−1. It is estimated that healthy adults can sustain the total duration of these tasks (~16 min) at ≤90% maximum oxygen uptake and a cardiorespiratory fitness standard of ≥42.3 ml kg−1 min−1 would be required to sustain work. Practitioner Summary: A cardiorespiratory fitness standard for firefighters of ≥42.3 ml kg−1 min−1 was derived from monitoring minimum acceptable performance of essential tasks. This study supports the implementation of a routine assessment of this fitness standard for all UK operational firefighters, to ensure safe physical preparedness for occupational performance.

The growing awareness and concern over environmental problems associated with landfill has led to increased demand for incinerators to dispose of municipal waste. The design of an efficient incinerator requires fundamental knowledge of grate combustion and grate mixing, but for such a complex combustion problem, there has been no satisfactory model of the system as a whole. An experimental fixed bed reactor was used to investigate the incineration of simulated waste. Measurements of temperatures and gas compositions were made at several positions within the refuse bed. A mathematical model for combustion of the solid waste in a travelling grate incinerator was developed based on an unsteady-state static bed model. The predictions from the model were investigated and compared to the combustion experimental data carried out in the batch fixed bed incinerator. Although several simplifying assumptions were made during the model development, the final functional form of the predicted data corresponds relatively well with the measured data.

In the UK, about 30 million tonnes of Municipal Solid Waste (MSW) is generated each year and the disposal of this waste has become a national problem. The growing scarcity of landfill sites for municipal solid waste disposal and the increasing environmental problems with landfill waste has led to more stringent regulations and high cost of waste disposal. The landfill tax in the UK is designed to encourage energy efficient waste management strategies aimed at reducing the amount of waste to be landfilled through incineration while maximising the recovery of the waste energy. Efficient recovery of energy from waste is therefore an important aim for modern incinerator design. The incineration of MSW is known to be a very complex process since the waste is poorly specified and its composition varies from moment to moment. Hence, research into waste combustion is fundamental to rational incinerator operation and the evolution of innovative processes such as co-incineration and integrated incinerator/gas turbine plants. This paper reviews the current research activities at Sheffield University Waste Incineration Centre (SUWIC) in MSW incineration.

The safe disposal of municipal solid waste has now become an urgent environmental problem. The traditional method of landfilling waste has created so many environmental problems that countries including Denmark, Holland and Germany have imposed severe restrictions on landfilling burnable waste. With up to 1 tonne of municipal waste being generated by every individual annually in the UK, incineration is now at the forefront of combustion research, as developed countries recognize the environmentally friendly advantages of this technology. An efficient incinerator is not only assessed by the amount of heat recovery but also by the levels of emissions and quality of the ash it produces. Incinerator designs must therefore be fully optimized so that they can control emissions by reducing the production of harmful pollutants such as dioxins, furans, NOx and SOx. Hence, incinerator bed combustion is a vital area that urgently needs further investigation. At SUWIC, the present work concentrates on the development of a comprehensive and reliable model for the incinerator bed combustion process. The results from the incinerator burning bed model can then provide the much needed boundary conditions for Computational Fluid Dynamics (CFD) modelling of the gas phase reacting turbulent flow in the freeboard region of an incinerator. In addition to the development of the computational model, the work involves several parallel activities, including experimental investigations into waste combustion, solid mixing and prevention of slag formation and instrumentation development.

Der Bericht gibt einen Uberblick uber die Strahlungseigenschaften von Flammen und die z. Z. verfugbaren Verfahren zur Voraussage des Verhaltens von Feuerungen und Brennkammern. Es werden Angaben uber die Emissivitat von Gasen und Gas/Rus-Mischungen gemacht. Um die Emissivitat stark leuchtender Flammen befriedigend zu beschreiben, kann ein Naherungsverfahren mit Exponentialreihen verwendet werden. Vereinfachte mathematische Ansatze fur die Randbedingungen einschlieslich der Annahme idealer Durchmischung im Feuerraum und verschiedener Annahmen fur langgestreckte Brennraume werden benutzt, um den Einflus unterschiedlicher Konstruktionen und Betriebsweisen zu vergleichen. Detailliertere Voraussagen uber die Ortsabhangigkeit der Flammeneigenschaften konnen mit der Methode der zonenweisen Analyse gemacht werden. Es wird uber jungere Bemuhungen berichtet, mit denen diese Methode wesentlich erweitert werden konnte. Dazu werden Angaben uber den Vergleich gemessener und errechneter Gastemperatur- und Gesamtwarmestrom-Verteilungen gemacht. Die radialen Temperaturprofile in bestimmten axialen Abstanden vom Brenner sowie die Verteilung der Warmeubertragung von einer Gasflamme an die kuhle Brennraumwand, die mit Hilfe einer „Vier-Flus”-Naherung fur die Strahlungswarmeubertragung vorausberechnet wurden, stehen in guter Ubereinstimmung mit Versuchsergebnissen.

The first part of this work deals with the evaporation of inorganic materials suitable for making thin dielectric layers for capacitors. The evaporation of a mixture of oxides, for example a glass, is also discussed, and the electrical properties of some glasses are given. The stability of metal oxide compounds at high temperatures is considered in relation to their free energies of formation. The reported vapour pressures of the components of the more commonly used glasses show that their evaporation is not possible from a single vapour source without separation of the components by fractional distillation. The second part of the report describes an experimental investigation into the preparation and properties of dielectric films of silicon oxide in the thickness range 0.14 to 1.7 μ produced by the evaporation of silicon monoxide at varying rates. Capacitors of 0.001–0.01μF/cm 2 have been deposited on ‘Pyrex’ glass using evaporated aluminium films for the conducting-plates, and measurements of the electrical properties of the silicon oxide films have been made. The working voltage of capacitors in this range lies between about 12 and 60 V depending upon the thickness of the dielectric and upon the working temperature. At temperatures above 200°C the values of loss angle and leakage current are generally unacceptable. It is established that the rate of deposition of the oxide layer has a marked effect on the loss angle, dielectric constant and leakage current. Generally the lowest values of leakage current and loss angle are obtained with rates of deposition below 5A./s. The dielectric constant of slowly deposited silicon oxide films is less than that of bulk silica, which is attributed partly to their lower density. The work carried out with silicon oxide shows that satisfactory dielectric films for capacitors can be made by the evaporation technique.

Although vacuum-deposited thin metal films have been studied for many years, it is only recently that their anomalous electrical properties have been turned to practical account. In this work the most important requirements for the deposition of metal film resistors are discussed, and an annealing cycle up to 300-350° C in air is proposed to stabilize the resistance of nickel-chromium alloy films, preventing further large irreversible change within the temperature range of normal use. The stability of annealed unprotected films within the range 10-400 Ω/square was determined over a period of 2000 h on load (1 w/in2) and 8000 h at no load. Frequency diagrams show the number of resistors measured, and their percentage resistance change. Resistors at no load increased by an average of 1% compared with a very small mean decrease in the same resistors on load. The temperature coefficient of resistance of films in the range 100-150 Ω/square is shown to vary between 0.002 and 0.1% deg-1C and is related to the rate of film deposition. Starting with an alloy of 80/20 nickel-chromium, the lowest values of temperature coefficient of resistance are obtained for rates of deposition lower than 5 As-1 and this effect is discussed in terms of the oxidation of the film and the separation of the alloy during evaporation.

Some properties of metal resistance films on resin-bonded glass cloth have been investigated. Plastics laminates bonded with different polymers were coated with films of nickel-chromium alloy by vacuum evaporation and with sandwich films of gold between bismuth oxide layers deposited by sputtering. Glow discharge cleaning was essential before evaporation to make adherent films. Silicone resin bonded laminates were unsuitable for preparing stable resistors, because they had a large number of surface defects produced by strains arising during the curing process. Melamine bonded laminates were decomposed by ion bombardment during discharge cleaning or sputtering. The resistors were tested under a load of 1 W/in.2 of film area over a period of 3 months. Resistors which became non-conducting during the test were found to break down invariably along surface scratches in the base material. The most stable resistors on plastics bases were produced with epoxy or polyester resin bonded laminates, and with the metal films protected by a melamine lacquer. Nickel-chromium films up to 800 Ω/square and gold films up to 50 Ω/square reached a stable resistance value after an ageing period of about eight weeks.

the technique , termed reactive sputtering , of preparing thin films of metallic compounds, notably metal oxides, by sputtering from metallic cathodes in the presence of active gases is described and compared with other deposition processes. The oxidation mechanisms which may occur during the sputtering of a metal in an atmosphere containing oxygen are considered. The desirable performance features of a reactive sputtering plant are enumerated. Experience of producing a range of metal oxide coatings has shown that in order to obtain films of a specified chemical composition the concentration of the desorbed gases in the sputtering atmosphere must be reduced to a minimum. This can be achieved by the use of a vapour pump, having a sufficiently high speed at the sputtering pressure to permit a high rate of leakage of the desired gas into the sputtering chamber. The composition of films of metal oxides which do not obey the law of fixed proportions can be varied by sputtering in oxygen plus inert gas mixtures of different concentrations. A simple method for controlling the composition of such gas mixtures is described. Consistent control of the sputtering rate requires the provision of a stable glow discharge operating at a given applied voltage and current density. It is shown that a booster vapour pump used in conjunction with a high vacuum isolation valve of variable aperture permits fine control of the sputtering pressure on which the discharge voltage and current are dependent, also, that a stable glow discharge can be easily obtained if the high tension transformer is of the high reactance type.

Although much has been written on the theory of electroluminescence there is little practical data available which would assist in the construction of a panel. This report gives complete details of the manufacture of electroluminescent light sources, using vacuum deposited films for the conducting electrodes. Commencing with a glass base, which is made electrically conductive by sputtering a transparent cadmium oxide film, the phosphor is mixed with a resin based lacquer and sprayed on the semiconducting oxide film. This is followed by a second layer of insulating material upon which the top electrode of aluminium may be deposited by evaporation in vacuum. Upon applying an alternating field between the two conducting electrodes, the phosphor emits light through the transparent oxide film. Three power supplies have been made to supply alternating current at suitable voltage and frequency, and full details are given.