92 research outputs found

    Manganese Disulfide (Hauerite) and Manganese Ditelluride. Thermal Properties from 5 to 350°K and Antiferromagnetic Transitions

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    The heat capacities of manganese disulfide and manganese ditelluride were determined by adiabatic calorimetry in the range 5–350°K. Lambda‐type transitions are present in both compounds with maxima at 47.93°K for MnS2 and at 83.0°K for MnTe2. Entropies, enthalpies, and Gibbs energy function values are calculated and tabulated. At 298.15°K they are: S°  =  23.88cal/mole⋅°K,H° − H0°  =  3384cal/mole,− [(G° − H0°) / T]  =  12.258cal/mole⋅°KS°=23.88cal∕mole⋅°K,H°−H0°=3384cal∕mole,−[(G°−H0°)∕T]=12.258cal∕mole⋅°K for MnS2 and 34.66, 4416, and 19.847 for MnTe2. The clearly cooperative entropy increments are only 0.71 cal/mole⋅°K for MnS2 and 0.80 for MnTe2. Available magnetic susceptibility data are interpreted in terms of zero‐field splitting of the 6S5/26S5∕2 state of the manganese 3d53d5 electrons. The resulting contributions to the heat capacity are evaluated. At 298°K the combined λ‐transitional and Schottky contributions to the entropy are 2.6 and 2.4 cal/mole⋅°K for MnS2 and MnTe2, respectively.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69763/2/JCPSA6-52-7-3820-1.pd

    Heat capacity and other thermodynamic properties of CoTe 2 from 5 to 1 030 K and of CoTe 2.315 from 300 to 1 040 K

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    The heat capacity of orthorhombic (marcasite-type structure) cobalt ditelluride has been measured from 5 to 1 030 K by adiabatic-shield calorimetry with alternate energy inputs and equilibrations. Above 900 K a marked increase in heat capacity occurs which probably signals a change in the composition of the CoTe 2 -phase towards higher tellurium content. Values at 298.15 and 1 000 K in J K −1 mol −1 of the heat capacity ( C p,m ), entropy [ S m ° (T) − S m ° (0)], and Gibbs energy function − [ G m ° (T) − H m ° (0)] T −1 are 75.23, 114.5, 49.93, and 132.4, 216.2, 139.17, respectively. Consistent with the metallic behavior of CoTe 2 , deviation of the heat capacity from the Debye T 3 -law was found at low temperatures. Comparison with the heat capacity of FeTe 2 shows a Schottky -like deviation with a maximum of 7.3 J K −1 mol −1 at 80 K and evidences the influence of the additional 3 d-electron in cobalt compared to iron. Heat capacity measurements were made on CoTe 2.33 to ascertain the existence range of the CoTe 2+ x -phase and the entropy of the associated structural disorder. Es wurde die WĂ€rmekapazitĂ€t des orthorhombischen Kobaltditellurids (Markasit-Typ) zwischen 5 und 1 030 K mittels adiabatisch abgeschirmter Kalorimetrie mit alternierender Energiezufuhr und Gleichgewichtseinstellung gemessen. Über 900 K tritt ein deutlicher Anstieg der WĂ€rmekapazitĂ€t ein, der möglicherweise einen Wechsel in der Zusammensetzung der CoTe 2 -Phase zu einem höheren Tellur-Gehalt anzeigt. Entsprechende Werte bei 298.15 bzw. 1 000 K in J K −1 mol −1 fĂŒr die WĂ€rmekapazitĂ€t ( C p, m ), die Entropie [ S m ° (T) − S m ° (0)] und die Gibbs Energiefunktion − [ G m ° (T) − H m ° (0)] T −1 sind 75.23, 114.5, 49.93 bzw. 132.4, 216.2, 139.17. In Übereinstimmung mit dem metallischen Verhalten von CoTe 2 wurde bei niedrigen Temperaturen eine Abweichung der WĂ€rmekapazitĂ€t vom Debye 'schen T 3 -Gesetz gefunden. Ein Vergleich mit der WĂ€rmekapazitĂ€t von FeTe 2 zeigt eine Schottky -gemĂ€ĂŸe Abweichung mit einem Maximum von 7.3 J K −1 mol −1 bei 80 K; dies zeigt den Einfluß der zusĂ€tzlichen 3 d-Elektronen im Kobalt, verglichen mit Eisen. Es wurden WĂ€rmekapazitĂ€tsmessungen an CoTe 2.33 durchgefĂŒhrt, um den Existenzbereich der CoTe 2+ x -Phase und die Entropie der damit zusammenhĂ€ngenden strukturellen Unordnung zu ermitteln.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41694/1/706_2004_Article_BF00810867.pd

    Heat capacity and thermodynamic properties of synthetic heazlewoodite, Ni3S2, and of the high-temperature phase Ni3±xS2

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    The heat capacity of synthetic heazlewoodite (Ni3S2) was measured over the temperature range 5 K to 350 K by equilibrium adiabatic calorimetry and compared with earlier results. High-temperature results on this phase and on (two-phase) Ni2.9S2 were obtained through the transition regions and up to about 1000 K. In addition to comparing the post-(834 K)-transitional heat capacity with that of fast ionic conductors it is discussed phenomenologically with Helmholtz-energy modelling for the phase transformation. Thermodynamic functions have been evaluated and selected values are, for R = 8.3144 J·K-1·mol-1:Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29536/1/0000624.pd

    Actinoid pnictides--I : Heat capacities from 5 to 950 K and magnetic transitions of U3As4 and U3Sb4. Ferromagnetic transitions

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    The heat capacities of triuranium tetraarsenide (U3As4) and triuranium tetraantimonide (U3Sb4), measured by adiabatic calorimetry over the temperature range 5-950 K, show sharp [lambda]-shaped transitions at 196.1 and 147.5 K, respectively. The maxima are related to the appearance of permanent magnetic moments below 198 and 148 K. Excess cooperative entropies associated with ferromagnetic ordering are tentatively estimated as 6.7 for U3As4 and 6.8 cal K-1 mole-1 for U3Sb4. These are larger than the two literature values reported for U3P4 (1.5 and 3.1 cal K-1 mole-1). The fact that these entropy of transition values are much smaller than would be expected from [Delta]St = R In (2J + 1) for the 3H4 ground term (J = 4) and that the observed heat capacities at high temperatures are much larger than would be expected from lattice plus dilational contributions are evidence of crystal field effects. The total electronic entropies to 950 K are estimated as 11.05 and 12.95 cal K-1 mole-1 for U3As4 and U3Sb4, respectively. Thermal functions for both U3As4 and U3Sb4 are integrated from the experimental data up to 950 K. At 298.15 K, the values of Cpo [So(T)-So(0)] and -{[Go(T)-Ho(0)]/T} in cal K-1 mole-1, are 44.82, 73.87 and 38.97, U3As4 and 44.98, 83.60 and 46.89, for U3Sb4.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/23080/1/0000655.pd

    Actinoid pnictides--II : Heat capacities of UAs2 and USb2 from 5 to 750 K and antiferromagnetic transitions

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    The heat capacities of uranium diarsenide (UAs2) and uranium diantimonide (USb2), with tetragonal structures of the anti-Cu2Sb-type, have been measured by adiabatic-shield calorimetry from 5 to about 750 K. Lambda-type transitions with maxima at 272.2 and 202.5 K for UAs2 and USb2, respectively, are related to maxima in the magnetic susceptibilities at 277 and 203 K, occasioned by transitions from antiferro- to paramagnetism in the compounds. Values of the heat capacities (Cp), entropies [S[deg](T) - S[deg](0)], and Gibbs energy functions -{[G[deg](T) - H[deg](o)]/T} at 298.15 K in cal K-1 mole-1 are 19.12, 29.41 and 15.05 for UAs2 and 19.16, 33.81 and 18.39 for USb2. Tentative resolutions of the cooperative magnetic heat capacities of UAs2 and USb2 lead to the magnetic entropies [Delta]S(mag) = 0.99 and 1.70 cal K-1 mole-1, respectively. The values for both are significantly lower than the spin-only magnetic entropy value R ln 3 = 2.18 cal K-1 mole-1.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22763/1/0000318.pd

    Trained facilitators’ experiences with structured advance care planning conversations in oncology : an international focus group study within the ACTION trial

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    Background In oncology, Health Care Professionals often experience conducting Advance Care Planning (ACP) conversations as difficult and are hesitant to start them. A structured approach could help to overcome this. In the ACTION trial, a Phase III multi-center cluster-randomized clinical trial in six European countries (Belgium, Denmark, Italy, the Netherlands, Slovenia, United Kingdom), patients with advanced lung or colorectal cancer are invited to have one or two structured ACP conversations with a trained facilitator. It is unclear how trained facilitators experience conducting structured ACP conversations. This study aims to understand how facilitators experience delivering the ACTION Respecting Choices (RC) ACP conversation. Methods A qualitative study involving focus groups with RC facilitators. Focus group interviews were recorded, transcribed, anonymized, translated into English, and thematically analysed, supported by NVivo 11. The international research team was involved in data analysis from initial coding and discussion towards final themes. Results Seven focus groups were conducted, involving 28 of in total 39 trained facilitators, with different professional backgrounds from all participating countries. Alongside some cultural differences, six themes were identified. These reflect that most facilitators welcomed the opportunity to participate in the ACTION trial, seeing it as a means of learning new skills in an important area. The RC script was seen as supportive to ask questions, including those perceived as difficult to ask, but was also experienced as a barrier to a spontaneous conversation. Facilitators noticed that most patients were positive about their ACTION RC ACP conversation, which had prompted them to become aware of their wishes and to share these with others. The facilitators observed that it took patients substantial effort to have these conversations. In response, facilitators took responsibility for enabling patients to experience a conversation from which they could benefit. Facilitators emphasized the need for training, support and advanced communication skills to be able to work with the script. Conclusions Facilitators experienced benefits and challenges in conducting scripted ACP conversations. They mentioned the importance of being skilled and experienced in carrying out ACP conversations in order to be able to explore the patients’ preferences while staying attuned to patients’ needs

    Shells and humans: molluscs and other coastal resources from the earliest human occupations at the Mesolithic shell midden of El Mazo (Asturias, Northern Spain)

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    Human populations exploited coastal areas with intensity during the Mesolithic in Atlantic Europe, resulting in the accumulation of large shell middens. Northern Spain is one of the most prolific regions, and especially the so-called Asturian area. Large accumulations of shellfish led some scholars to propose the existence of intensification in the exploitation of coastal resources in the region during the Mesolithic. In this paper, shell remains (molluscs, crustaceans and echinoderms) from stratigraphic units 114 and 115 (dated to the early Mesolithic c. 9 kys cal BP) at El Mazo cave (Asturias, northern Spain) were studied in order to establish resource exploitation patterns and environmental conditions. Species representation showed that limpets, top shells and sea urchins were preferentially exploited. One-millimetre mesh screens were crucial in establishing an accurate minimum number of individuals for sea urchins and to determine their importance in exploitation patterns. Environmental conditions deduced from shell assemblages indicated that temperate conditions prevailed at the time of the occupation and the morphology of the coastline was similar to today (rocky exposed shores). Information recovered relating to species representation, collection areas and shell biometry reflected some evidence of intensification (reduced shell size, collection in lower areas of exposed shores, no size selection in some units and species) in the exploitation of coastal resources through time. However, the results suggested the existence of changes in collection strategies and resource management, and periods of intense shell collection may have alternated with times of shell stock recovery throughout the Mesolithic.This research was performed as part of the project “The human response to the global climatic change in a littoral zone: the case of the transition to the Holocene in the Cantabrian coast (10,000–5000 cal BC) (HAR2010-22115-C02-01)” funded by the Spanish Ministry of Economy and Competitiveness. AGE was funded by the University of Cantabria through a predoctoral grant and IGZ was funded by the Spanish Ministry of Economy and Competitiveness through a Juan de la Cierva grant. We also would like to thank the University of Cantabria and the IIIPC for providing support, David Cuenca-Solana, Alejandro GarcĂ­a Moreno and Lucia Agudo PĂ©rez for their help. We also thank Jennifer Jones for correcting the English. Comments from two anonymous reviewers helped to improve the paper

    Atomic Layer Deposition of 2D Metal Dichalcogenides for Electronics, Catalysis, Energy Storage, and Beyond

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    2D transition metal dichalcogenides (TMDCs) are among the most exciting materials of today. Their layered crystal structures result in unique and useful electronic, optical, catalytic, and quantum properties. To realize the technological potential of TMDCs, methods depositing uniform films of controlled thickness at low temperatures in a highly controllable, scalable, and repeatable manner are needed. Atomic layer deposition (ALD) is a chemical gas-phase thin film deposition method capable of meeting these challenges. In this review, the applications evaluated for ALD TMDCs are systematically examined, including electronics and optoelectonics, electrocatalysis and photocatalysis, energy storage, lubrication, plasmonics, solar cells, and photonics. This review focuses on understanding the interplay between ALD precursors and deposition conditions, the resulting film characteristics such as thickness, crystallinity, and morphology, and ultimately device performance. Through rational choice of precursors and conditions, ALD is observed to exhibit potential to meet the varying requirements of widely different applications. Beyond the current state of ALD TMDCs, the future prospects, opportunities, and challenges in different applications are discussed. The authors hope that the review aids in bringing together experts in the fields of ALD, TMDCs, and various applications to eventually realize industrial applications of ALD TMDCs.Peer reviewe

    Integration of oncology and palliative care : a Lancet Oncology Commission

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    Full integration of oncology and palliative care relies on the specific knowledge and skills of two modes of care: the tumour-directed approach, the main focus of which is on treating the disease; and the host-directed approach, which focuses on the patient with the disease. This Commission addresses how to combine these two paradigms to achieve the best outcome of patient care. Randomised clinical trials on integration of oncology and palliative care point to health gains: improved survival and symptom control, less anxiety and depression, reduced use of futile chemotherapy at the end of life, improved family satisfaction and quality of life, and improved use of health-care resources. Early delivery of patient-directed care by specialist palliative care teams alongside tumour-directed treatment promotes patient-centred care. Systematic assessment and use of patient-reported outcomes and active patient involvement in the decisions about cancer care result in better symptom control, improved physical and mental health, and better use of health-care resources. The absence of international agreements on the content and standards of the organisation, education, and research of palliative care in oncology are major barriers to successful integration. Other barriers include the common misconception that palliative care is end-of-life care only, stigmatisation of death and dying, and insufficient infrastructure and funding. The absence of established priorities might also hinder integration more widely. This Commission proposes the use of standardised care pathways and multidisciplinary teams to promote integration of oncology and palliative care, and calls for changes at the system level to coordinate the activities of professionals, and for the development and implementation of new and improved education programmes, with the overall goal of improving patient care. Integration raises new research questions, all of which contribute to improved clinical care. When and how should palliative care be delivered? What is the optimal model for integrated care? What is the biological and clinical effect of living with advanced cancer for years after diagnosis? Successful integration must challenge the dualistic perspective of either the tumour or the host, and instead focus on a merged approach that places the patient's perspective at the centre. To succeed, integration must be anchored by management and policy makers at all levels of health care, followed by adequate resource allocation, a willingness to prioritise goals and needs, and sustained enthusiasm to help generate support for better integration. This integrated model must be reflected in international and national cancer plans, and be followed by developments of new care models, education and research programmes, all of which should be adapted to the specific cultural contexts within which they are situated. Patient-centred care should be an integrated part of oncology care independent of patient prognosis and treatment intention. To achieve this goal it must be based on changes in professional cultures and priorities in health care
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