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1.
Br Poult Sci ; 2022 Aug 10.
Artículo en Inglés | MEDLINE | ID: mdl-35946320

RESUMEN

1. The following study was conducted to evaluate the tolerability of tall oil fatty acid (TOFA) to broiler chickens, at 3 graded levels as a nutritional additive in complete feed.2. 256 one-day-old female and male Cobb 500 broiler chickens were assigned to four dietary treatment groups with TOFA at 0 (control), 1.0, 3.0, or 5.0 g/kg complete feed for 45 days.3. Birds were weighed individually on days 0, 16, 31, and 45, and the feed intake, bird weight gain, and feed conversion ratio were calculated for the respective starter, grower and finisher phases and over the whole study. On day 45, blood samples were drawn from each bird for haematology and blood chemistry measurements. Two birds per pen were subjected to gross pathological examination and sampling of several tissues for histopathology, including weighing the liver.4. The dietary treatments did not affect zootechnical performance parameters or mortality over the whole study period. Bird performance was typical for the breed.5. Haematology, clinical chemistry and histopathology did not reveal any changes associated with dietary TOFA dosing. However, the 5.0 g/kg dose level increased the relative weight of the liver, as a percentage of final body weight, compared to the control group, but there was lack of corresponding histopathology findings.6. In conclusion, the study indicated that oral administration of TOFA for 45 days in feed was well tolerated by the birds at dietary levels of up to 5.0 g/kg.

2.
Br Poult Sci ; 63(2): 218-225, 2022 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-34404304

RESUMEN

1. The following experiments were conducted to evaluate the effects of nonanoic acid (NA) in broilers and laying hens, at practical levels as a flavouring in complete feed.2. In the first experiment, 1100, one-day-old Ross 308 chicks, half male and female, were randomly assigned to 50 floor pens containing 22 chicks each. Chicks were fed one of five treatment diets containing either 0 (control), 100, 300, 500 or 1,000 mg NA/kg complete feed for 42 days.3. The NA treatment had no effect on ADFI, but there was a linear relationship with ADG and FCR. No differences were observed in blood parameters or tissue pathology among treatment groups.4. In a second study, 150 Hyline hens aged 24 weeks old were randomly assigned to 50 pens containing three birds each. Laying hens were fed one of five treatment diets containing 0 (control), 100, 300, 500 or 1,000 mg NA/kg complete feed for 56 days.5. Treatment with NA has no effect on live weight, ADFI or egg production in laying hens, and there were no observed changes in tissue pathology.6. The results supported the toleration of NA in broilers or layers at dietary levels of up to 1,000 mg/kg.


Asunto(s)
Alimentación Animal , Pollos , Alimentación Animal/análisis , Animales , Dieta/veterinaria , Ácidos Grasos , Femenino , Masculino
3.
BMJ Mil Health ; 167(3): 163-167, 2021 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-32086264

RESUMEN

INTRODUCTION: Severe haemorrhage from the arm that is unresponsive to direct pressure necessitates the application of a tourniquet. Detachable arm protection, referred to as brassards, are used by the UK Armed Forces to protect the upper arm from fragmentation threats. However, the coverage they originally provided was based on limited medical evidence. Medical consensus has determined that the dimensions of arm protection should in future be related to how far up the arm a tourniquet can be applied. METHOD: CT scans of 120 male Armed Forces personnel were analysed to ascertain the vertical distances from acromion process to the point at which a tourniquet can applied, equating to the anterior axillary fold. These values were statistically compared with those derived from the 2007 UK Military anthropometric survey using a paired t-test. Additional distances were added to account for tourniquet width and slippage, with the total value compared with VIRTUS brassard length. RESULTS: No significant difference (p<0.01) was found in mean acromion to axilla length (114 mm) compared with that found in the anthropometric survey confirming sample validity. The deltoid insertion lay 24 mm below the axillary fold for the 50th percentile value from CT. Essential arm coverage for the 99th percentile male in this study was calculated as 201 mm. CONCLUSIONS: Based on this research, a single new brassard for the VIRTUS body armour and load carriage system was recommended and manufactured based on the 99th percentile. This is over 30% shorter than the existing VIRTUS brassard, reducing the overall weight burden for the soldier and improving heat dispersion, integration and interoperability. The new brassard has been issued to Armed Forces personnel since October 2018. The reduced mass of ballistic protective material in conjunction with requiring only a single size of brassard has already saved the Ministry of Defence £20 000 in procurement costs.


Asunto(s)
Tamaño Corporal , Ropa de Protección/normas , Extremidad Superior/fisiología , Adulto , Antropometría/métodos , Diseño de Equipo/métodos , Humanos , Modelos Lineales , Masculino , Ropa de Protección/estadística & datos numéricos , Tomografía Computarizada por Rayos X/métodos , Tomografía Computarizada por Rayos X/estadística & datos numéricos , Reino Unido
4.
BMJ Mil Health ; 2020 Oct 27.
Artículo en Inglés | MEDLINE | ID: mdl-33109734

RESUMEN

Developments in military personal armour have aimed to achieve a balance between anatomical coverage, protection and mobility. When death is likely to occur within 60 min of injury to anatomical structures without damage control surgery, then these anatomical structures are defined as 'essential'. However, the medical terminology used to describe coverage is challenging to convey in a Systems Requirements Document (SRD) for acquisition of new armour and to ultimately translate to the correct sizing and fitting of personal armour. Many of those with Ministry of Defence responsible for the procurement of personal armour and thereby using SRDs will likely have limited medical knowledge; therefore, the potentially complex medical terminology used to describe the anatomical boundaries must be translated into easily recognisable and measurable external landmarks. We now propose a complementary classification for ballistic protection coverage, termed threshold and objective, based on the feasibility of haemorrhage control within the prehospital environment.

5.
Int J Legal Med ; 134(2): 691-695, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-31970481

RESUMEN

INTRODUCTION: Edged weapons are a known domestic threat to the police forces of the UK. This threat is mitigated by wearing stab-resistant body armour that is either worn overtly or covertly depending on role. Although the UK military have traditionally focused their body armour design upon ballistic and fragmentation threats, future roles may require protection against an edged weapon threat. Since 2017, UK police body armour requirements for anatomical coverage for both edged weapon and ballistic threats are now based upon the requirements of UK military. This revised coverage may need additional research to determine minimum distances to essential structures. METHOD: Three entry locations and penetration vectors were chosen using the limited available information in the literature, in combination with a specialist in edged weapons defence. One hundred twenty CT trauma scans of male military service personnel were subsequently analysed to ascertain minimum distances from skin surface to the first structure encountered that is included in essential coverage (heart, aorta, vena cava, liver and spleen) at 3 specific entry points. RESULTS: Individuals ranged between 18 and 46 years, with a mean body mass index of 24.8. The absolute minimum depth from skin surface to a structure within the auspice of essential coverage was 17 mm to the liver in entry point 3 and 19 mm to the heart in entry point 2. CONCLUSIONS: Minimum distances to critical structures were significantly larger than those described in previous studies on civilians. This study will be used to supplement existing evidence to support existing UK police requirements for stab-resistant body armour. Using the weapon entry sites and vectors described in this study, overmatching to a behind armour depth of 17 mm would cover all of this population in this study.


Asunto(s)
Personal Militar , Ropa de Protección/normas , Tomografía Computarizada por Rayos X , Heridas Punzantes , Adolescente , Adulto , Diseño de Equipo/normas , Humanos , Masculino , Persona de Mediana Edad , Policia , Reino Unido , Armas , Adulto Joven
6.
Biochem Biophys Rep ; 12: 158-165, 2017 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-29090277

RESUMEN

Linker histones (H1) are the basic proteins in higher eukaryotes that are responsible for the final condensation of chromatin. In contrast to the nucleosome core histone proteins, the role of H1 in compacting DNA is not clearly understood. In this study ITC was used to measure the binding constant, enthalpy change, and binding site size for the interactions of H10, or its C-terminal (H10-C) and globular (H10-G) domains to highly polymerized calf-thymus DNA at temperatures from 288 K to 308 K. Heat capacity changes, ΔCp, for these same H10 binding interactions were estimated from the temperature dependence of the enthalpy changes. The enthalpy changes for binding H10, H10-C, or H10-G to CT-DNA are all endothermic at 298 K, becoming more exothermic as the temperature is increased. The ΔH for binding H10-G to CT-DNA is exothermic at temperatures above approximately 300 K. Osmotic stress experiments indicate that the binding of H10 is accompanied by the release of approximately 35 water molecules. We estimate from our naked DNA titration results that the binding of the H10 to the nucleosome places the H10 protein in close contact with approximately 41 DNA bp. The breakdown is that the H10 carboxyl terminus interacts with 28 bp of linker DNA on one side of the nucleosome, the H10 globular domain binds directly to 7 bp of core DNA, and shields another 6 linker DNA bases, 3 bp on either side of the nucleosome where the linker DNA exits the nucleosome core.

7.
Chem Commun (Camb) ; 53(76): 10500-10503, 2017 Sep 21.
Artículo en Inglés | MEDLINE | ID: mdl-28828448

RESUMEN

Light emitting semiconducting quantum dots show great promise as solar cells, optoelectronic devices and multimodal imaging probes. Here we demonstrate successful grafting of a thiol-functionalised GdIII MRI contrast agent onto the surface of core-multishell CdSe/CdS/ZnS quantum dots. The resulting nanoprobe exhibits intense photoluminescence and unprecedentedly large T1 relaxivity of 6800 mM-1 s-1 per nanoparticle due to secure implanting of ca. 620 magnetic centers per quantum dot unit.

8.
Chem Commun (Camb) ; 53(55): 7816-7819, 2017 Jul 06.
Artículo en Inglés | MEDLINE | ID: mdl-28653058

RESUMEN

Using a surface science approach, the selectivity in the Ullmann cross-coupling of aryl halides on Cu(111) has been understood and controlled. The binding strength of the reactants and repulsion between them dictates which organometallic intermediates form, and hence the product distribution. Cross coupling can be maximized at low reactant concentrations.

9.
Injury ; 47(9): 1932-8, 2016 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-27343133

RESUMEN

INTRODUCTION: Military body armour is designed to prevent the penetration of ballistic projectiles into the most vulnerable structures within the thorax and abdomen. Currently the OSPREY and VIRTUS body armour systems issued to United Kingdom (UK) Armed Forces personnel are provided with a single size front and rear ceramic plate regardless of the individual's body dimensions. Currently limited information exists to determine whether these plates overprotect some members of the military population, and no method exists to accurately size plates to an individual. METHOD: Computed Tomography (CT) scans of 120 male Caucasian UK Armed Forces personnel were analysed to measure the dimensions of internal thoraco-abdominal anatomical structures that had been defined as requiring essential medical coverage. The boundaries of these structures were related to three potential anthropometric landmarks on the skin surface and statistical analysis was undertaken to validate the results. RESULTS: The range of heights of each individual used in this study was comparable to previous anthropometric surveys, confirming that a representative sample had been used. The vertical dimension of essential medical coverage demonstrated good correlation to torso height (suprasternal notch to iliac crest) but not to stature (r(2)=0.53 versus 0.04). Horizontal coverage did not correlate to either measure of height. Surface landmarks utilised in this study were proven to be reliable surrogate markers for the boundaries of the underlying anatomical structures potentially requiring essential protection by a plate. CONCLUSIONS: Providing a range of plate sizes, particularly multiple heights, should optimise the medical coverage and thus effectiveness of body armour for UK Armed Forces personnel. The results of this work provide evidence that a single width of plate if chosen correctly will provide the essential medical coverage for the entire military population, whilst recognising that it still could overprotect the smallest individuals. With regards to anthropometric measurements; it is recommended, based on this work, that torso height is used instead of stature for sizing body armour. Coverage assessments should now be undertaken for side protection as well as for other non-Caucasian populations and females, with anthropometric surveys utilising the three landmarks recommended in this study.


Asunto(s)
Traumatismos por Explosión/prevención & control , Diseño Asistido por Computadora , Diseño de Equipo , Personal Militar , Ropa de Protección , Tomografía Computarizada por Rayos X , Heridas por Arma de Fuego/prevención & control , Antropometría , Aorta , Femenino , Corazón , Humanos , Hígado , Masculino , Bazo , Reino Unido
11.
Sci Rep ; 6: 20480, 2016 Feb 09.
Artículo en Inglés | MEDLINE | ID: mdl-26857581

RESUMEN

The development of simple routes to emissive solid-state materials is of paramount interest, and in this report we describe the biosynthesis of infrared emitting quantum dots in a living plant via a mutual antagonistic reaction. Exposure of common Allium fistulosum to mercury and tellurium salts under ambient conditions resulted in the expulsion of crystalline, non-passivated HgTe quantum dots that exhibited emissive characteristics in the near-infrared spectral region, a wavelength range that is important in telecommunications and solar energy conversion.


Asunto(s)
Allium/química , Rayos Infrarrojos , Puntos Cuánticos/química
12.
J R Army Med Corps ; 162(4): 270-5, 2016 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-26106013

RESUMEN

INTRODUCTION: Defining the minimum anatomical structural coverage required to protect from ballistic threats is necessary to enable objective comparisons between body armour designs. Current protection for the axilla and arm is in the form of brassards, but no evidence exists to justify the coverage that should be provided by them. METHOD: A systematic review was undertaken to ascertain which anatomical components within the arm or axilla would be highly likely to lead to either death within 60 min or would cause significant long-term morbidity. RESULTS: Haemorrhage from vascular damage to the axillary or brachial vessels was demonstrated to be the principal cause of mortality from arm trauma on combat operations. Peripheral nerve injuries are the primary cause of long-term morbidity and functional disability following upper extremity arterial trauma. DISCUSSION: Haemorrhage is managed through direct pressure and the application of a tourniquet. It is therefore recommended that the minimum coverage should be the most proximal extent to which a tourniquet can be applied. Superimposition of OSPREY brassards over these identified anatomical structures demonstrates that current coverage provided by the brassards could potentially be reduced.


Asunto(s)
Brazo , Axila , Hemorragia/prevención & control , Personal Militar , Ropa de Protección , Heridas por Arma de Fuego/prevención & control , Brazo/anatomía & histología , Traumatismos del Brazo/prevención & control , Axila/anatomía & histología , Axila/lesiones , Arteria Axilar/anatomía & histología , Arteria Axilar/lesiones , Arteria Braquial/anatomía & histología , Arteria Braquial/lesiones , Diseño de Equipo , Hemorragia/mortalidad , Humanos , Heridas por Arma de Fuego/mortalidad , Heridas Penetrantes/mortalidad , Heridas Penetrantes/prevención & control
13.
J R Army Med Corps ; 162(4): 284-90, 2016 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-26272950

RESUMEN

INTRODUCTION: Body armour is a type of equipment worn by military personnel that aims to prevent or reduce the damage caused by ballistic projectiles to structures within the thorax and abdomen. Such injuries remain the leading cause of potentially survivable deaths on the modern battlefield. Recent developments in computer modelling in conjunction with a programme to procure the next generation of UK military body armour has provided the impetus to re-evaluate the optimal anatomical coverage provided by military body armour against high energy projectiles. METHODS: A systematic review of the literature was undertaken to identify those anatomical structures within the thorax and abdomen that if damaged were highly likely to result in death or significant long-term morbidity. These structures were superimposed upon two designs of ceramic plate used within representative body armour systems using a computerised representation of human anatomy. RESULTS AND CONCLUSIONS: Those structures requiring essential medical coverage by a plate were demonstrated to be the heart, great vessels, liver and spleen. For the 50th centile male anthropometric model used in this study, the front and rear plates from the Enhanced Combat Body Armour system only provide limited coverage, but do fulfil their original requirement. The plates from the current Mark 4a OSPREY system cover all of the structures identified in this study as requiring coverage except for the abdominal sections of the aorta and inferior vena cava. Further work on sizing of plates is recommended due to its potential to optimise essential medical coverage.


Asunto(s)
Traumatismos Abdominales/prevención & control , Diseño de Equipo , Personal Militar , Ropa de Protección , Traumatismos Torácicos/prevención & control , Heridas por Arma de Fuego/prevención & control , Aorta/anatomía & histología , Aorta/lesiones , Corazón/anatomía & histología , Lesiones Cardíacas/prevención & control , Humanos , Hígado/anatomía & histología , Hígado/lesiones , Bazo/anatomía & histología , Bazo/lesiones , Heridas Penetrantes/prevención & control
14.
Injury ; 46(4): 629-33, 2015 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-25683212

RESUMEN

INTRODUCTION: There is a requirement in the Ministry of Defence for an objective method of comparing the area of coverage of different body armour designs for future applications. Existing comparisons derived from surface wound mapping are limited in that they can only demonstrate the skin entry wound location. The Coverage of Armour Tool (COAT) is a novel three-dimensional model capable of comparing the coverage provided by body armour designs, but limited information exists as to which anatomical structures require inclusion. The aim of this study was to assess the utility of COAT, in the assessment of neck protection, using clinically relevant injury data. METHOD: Hospital notes and post mortem records of all UK soldiers injured by an explosive fragment to the neck between 01 Jan 2006 and 31 December 2012 from Iraq and Afghanistan were analysed to determine which anatomical structures were responsible for death or functional disability at one year post injury. Using COAT a comparison of three ballistic neck collar designs was undertaken with reference to the percentage of these anatomical structures left exposed. RESULTS: 13/81 (16%) survivors demonstrated complications at one year, most commonly upper limb weakness from brachial plexus injury or a weak voice from laryngeal trauma. In 14/94 (15%) soldiers the neck wound was believed to have been the sole cause of death, primarily from carotid artery damage, spinal cord transection or rupture of the larynx. COAT objectively demonstrated that despite the larger OSPREY collar having almost double the surface area than the two-piece prototype collar, the percentage area of vulnerable cervical structures left exposed only reduced from 16.3% to 14.4%. DISCUSSION: COAT demonstrated its ability to objectively quantify the potential effectiveness of different body armour designs in providing coverage of vulnerable anatomical structures from different shot line orientations. To improve its utility, it is recommended that COAT be further developed to enable weapon and tissue specific information to be modelled, and that clinically significant injuries to other body regions are also incorporated.


Asunto(s)
Traumatismos por Explosión/prevención & control , Diseño Asistido por Computadora , Personal Militar , Traumatismos del Cuello/prevención & control , Ropa de Protección , Equipos de Seguridad/normas , Escala Resumida de Traumatismos , Adulto , Autopsia , Diseño de Equipo , Femenino , Humanos , Masculino , Reino Unido , Heridas por Arma de Fuego/prevención & control
15.
J R Army Med Corps ; 161(1): 22-6, 2015 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-24556749

RESUMEN

INTRODUCTION: Protecting the neck from explosively propelled fragments has traditionally been achieved through a collar attached to the ballistic vest. An Enhanced Protection Under Body Armour Combat Shirt (EP-UBACS) collar has been identified as an additional method of providing neck protection but limited evidence as to its potential medical effectiveness exists to justify its procurement. METHOD: Entry wound locations and resultant medical outcomes were determined using Abbreviated Injury Scale (AIS) for all fragmentation neck wounds sustained by UK soldiers between 01 January 2010 and 31 December 2011. Data were prospectively entered into a novel computerised tool base and comparisons made between three EP-UBACS neck collar designs in terms of predicted reduction in AIS scores. RESULTS: All collars reduced AIS scores, with the greatest reduction provided by designs incorporating increased standoff from the neck and an additional semi-circle of ballistic material underneath the collar at the front and back. DISCUSSION: This technique confirms that reinforcing the neck collar of an EP-UBACS would be expected to reduce injury severity from neck wounds. However, without knowledge of entry wound locations for injuries to other body areas as well as the use of AIS scores without clinical or pathological verification its further use in the future may be limited. The ability to overlay any armour design onto a standardised human was potentially the most useful part of this tool and we would recommend developing this technique using underlying anatomical structures and not just the skin surface.


Asunto(s)
Diseño Asistido por Computadora , Personal Militar , Traumatismos del Cuello/prevención & control , Equipos de Seguridad , Heridas por Arma de Fuego/prevención & control , Escala Resumida de Traumatismos , Traumatismos por Explosión/prevención & control , Diseño de Equipo , Humanos , Reino Unido
16.
Br J Oral Maxillofac Surg ; 53(1): 3-7, 2015 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-25441496

RESUMEN

The wearing of eye protection by United Kingdom soldiers in Afghanistan has reduced the morbidity caused by explosive fragments. However, the remaining face remains uncovered because there is a lack of evidence to substantiate the procurement of methods to protect it. Using a new computerised tool we entered details of the entry sites of surface wounds caused by explosive fragments in all UK soldiers who were injured in the face between 1 January 2010 and 31 December 2011. We compared clinical and predicted immediate and long term outcomes (as defined by the Abbreviated Injury Score (AIS) and the Functional Capacity Index (pFCI), respectively). We also used the tool to predict how additional protection in the form of a visor and mandible guard would affect outcomes. A soldier wearing eye protection was 9 times (1.03/0.12) less likely to sustain an eye injury than one without. However, 38% of soldiers in this series were not wearing eye protection at the time of injury. There was no significant difference between the AIS and pFCI scores predicted by the tool and those found clinically. There is limited evidence to support the use of a mandible guard; its greatest asset is better protection of the nose, but a visor would be expected to reduce long-term morbidity more than eye protection alone, and we recommend future trials to assess its acceptability to users. We think that use of this novel tool can help in the selection of future methods of ballistic facial protection.


Asunto(s)
Traumatismos por Explosión/prevención & control , Explosiones , Traumatismos Faciales/prevención & control , Personal Militar , Equipo de Protección Personal , Escala Resumida de Traumatismos , Traumatismos por Explosión/clasificación , Diseño Asistido por Computadora , Diseño de Equipo , Lesiones Oculares Penetrantes/clasificación , Lesiones Oculares Penetrantes/prevención & control , Dispositivos de Protección de los Ojos , Traumatismos Faciales/clasificación , Predicción , Dispositivos de Protección de la Cabeza , Humanos , Imagenología Tridimensional/métodos , Rayos Láser , Masculino , Traumatismos Mandibulares/prevención & control , Nariz/lesiones , Estudios Prospectivos , Sistema de Registros , Resultado del Tratamiento , Reino Unido
17.
Nanoscale ; 6(22): 13598-605, 2014 Nov 21.
Artículo en Inglés | MEDLINE | ID: mdl-25271696

RESUMEN

We report the controlled alloying, oxidation, and subsequent reduction of individual AgAu nanoparticles in the scanning transmission electron microscope (STEM). Through sequential application of electron beam induced oxidation and in situ heating and quenching, we demonstrate the transformation of Ag-Au core-shell nanoparticles into: AgAu alloyed, Au-Ag core-shell, hollow Au-Ag2O core-shell, and Au-Ag2O yolk-shell nanoparticles. We are able to directly image these morphological transformations in real-time at atomic resolution and perform energy dispersive X-ray (EDX) spectrum imaging to map changing elemental distributions with sub-nanometre resolution. By combining aberration corrected STEM imaging and high efficiency EDX spectroscopy we are able to quantify not only the growth and coalescence of Kirkendall voids during oxidation but also the compositional changes occurring during this reaction. This is the first time that it has been possible to track the changing distribution of elements in an individual nanoparticle undergoing oxidation driven shell growth and hollowing.

18.
Chem Commun (Camb) ; 50(70): 10035-7, 2014 Sep 11.
Artículo en Inglés | MEDLINE | ID: mdl-25051314

RESUMEN

The Ullmann coupling of bromobenzene to biphenyl on Co nanoparticles proceeds below room temperature via an intermediate in which phenyl groups are bound directly to metallic Co. A similar surface-bound benzyl intermediate is observed for coupling of benzylbromide to bibenzyl on Co.

19.
Ultramicroscopy ; 144: 1-8, 2014 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-24814008

RESUMEN

Energy-dispersive X-ray (EDX) spectroscopy in the scanning transmission electron microscope (STEM) has been used to demonstrate the presence of size-dependent compositional variation for L12-structured Ni3Al-type gamma-prime (γ') precipitates within a commercial RR1000 Ni-based superalloy. This semi-quantitative elemental analysis has been achieved using electrochemical extraction of the γ' precipitates from the γ matrix. The applicability of this approach to size-dependent compositional analysis of precipitates was confirmed by a comparison of the size distribution for the extracted precipitates with those present in traditional electropolished foil specimens in the size range 20-250nm. By applying suitable thickness-dependent absorption-corrections we have demonstrated that the composition of γ' precipitates in our material depends on the size of the precipitate in the range of 5nm to 3µm. In particular, the Al content was observed to increase in smaller γ' precipitates while Ti and Ta contents are constant for all sizes of precipitate. Hf was observed to be present only in the largest precipitates. This type of local compositional information provides invaluable input to assess the accuracy of microstructural modelling for these complex alloys and provides new evidence supporting the importance of anti-site diffusion.

20.
Chem Commun (Camb) ; 50(49): 6537-9, 2014 Jun 21.
Artículo en Inglés | MEDLINE | ID: mdl-24825772

RESUMEN

Using scanning tunnelling microscopy, we have visualized the segregation of carbon monoxide and hydrogen, the two reactants in Fischer-Tropsch synthesis, on cobalt nanoparticles at catalytically relevant coverages. Density functional theory was used to interrogate the relevant energetics.

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