Cross- and in-plane thermal conductivity of AlN thin films measured using differential 3-omega method

Thickness dependency and interfacial structure effects on thermal properties of AlN thin films were systematically investigated by characterizing cross-plane and in-plane thermal conductivities, crystal structures, chemical compositions, surface morphologies and interfacial structures using an extended differential 3ω method, X-ray diffraction (XRD) analysis, X-ray photoelectron spectroscopy, atomic force microscopy (AFM) and transmission electron microscopy. AlN thin films with various thicknesses from 100 to 1000 nm were deposited on p-type doped silicon substrates using a radio frequency reactive magnetron sputtering process. Results revealed that both the cross- and in-plane thermal conductivities of the AlN thin films were significantly smaller than those of the AlN in a bulk form. The thermal conductivities of the AlN thin films were strongly dependent on the film thickness, in both the cross- and in-plane directions. Both the XRD and AFM results indicated that the grain size significantly affected the thermal conductivity of the films due to the scattering effects from the grain boundary

Transparent Flexible Thermoelectric Material Based on Non-toxic Earth-Abundant p-Type Copper Iodide Thin Film

Thermoelectric devices that are flexible and optically transparent hold unique promise for future electronics. However, development of 'invisible' thermoelectric elements is hindered by the lack of p-type transparent thermoelectric materials. Here we present the superior room-temperature thermoelectric performance of p-type transparent copper iodide (CuI) thin films deposited by industrially applicable room-temperature sputtering techniques. The optical transmittance is 60–85% in the visible and near-infrared regions. Large Seebeck coefficients and power factors of the obtained CuI thin films are analyzed based on a single-band model. The low thermal conductivity of the CuI films is attributed to a combined effect of the heavy element iodine and strong phonon scattering. Accordingly, we achieve a large thermoelectric figure of merit of ZT = 0.21 at 300 K for the CuI films, which is three orders of magnitude higher compared with state-of-the-art p-type transparent materials. A transparent and flexible CuI-based thermoelectric element is demonstrated

Global patient outcomes after elective surgery: prospective cohort study in 27 low-, middle- and high-income countries.

BACKGROUND: As global initiatives increase patient access to surgical treatments, there remains a need to understand the adverse effects of surgery and define appropriate levels of perioperative care. METHODS: We designed a prospective international 7-day cohort study of outcomes following elective adult inpatient surgery in 27 countries. The primary outcome was in-hospital complications. Secondary outcomes were death following a complication (failure to rescue) and death in hospital. Process measures were admission to critical care immediately after surgery or to treat a complication and duration of hospital stay. A single definition of critical care was used for all countries. RESULTS: A total of 474 hospitals in 19 high-, 7 middle- and 1 low-income country were included in the primary analysis. Data included 44 814 patients with a median hospital stay of 4 (range 2-7) days. A total of 7508 patients (16.8%) developed one or more postoperative complication and 207 died (0.5%). The overall mortality among patients who developed complications was 2.8%. Mortality following complications ranged from 2.4% for pulmonary embolism to 43.9% for cardiac arrest. A total of 4360 (9.7%) patients were admitted to a critical care unit as routine immediately after surgery, of whom 2198 (50.4%) developed a complication, with 105 (2.4%) deaths. A total of 1233 patients (16.4%) were admitted to a critical care unit to treat complications, with 119 (9.7%) deaths. Despite lower baseline risk, outcomes were similar in low- and middle-income compared with high-income countries. CONCLUSIONS: Poor patient outcomes are common after inpatient surgery. Global initiatives to increase access to surgical treatments should also address the need for safe perioperative care. STUDY REGISTRATION: ISRCTN5181700

Thermal conductivity measurements of thin films using a novel 3 omega method

For most micro- and nanoelectronic devices based on thin films applied for effective heat dissipation and thermoelectric devices for energy harvesting, thermal management is a critical subject for their device performance and reliability. This thesis focuses on the investigation of the cross- and in-plane thermal conductivities of both high- and low-thermal conductive thin film materials. Aluminum nitride (AlN), with its high thermal conductivity, has been studied, as it is a promising candidate for effective heat conductors in microelectronic devices. Copper iodide (CuI) has also been investigated in this thesis, because of its great interest in novel energy harvesting applications with low thermal conductivity and outstanding thermoelectric properties. Thermal conductivities of thin films tend to be substantially different from those of their bulk counterparts, which is generally caused by oxygen impurities, dislocations, and grain boundary scattering, all of which can reduce the thermal conductivity of the films. These effects also influence cross- and in-plane heat conduction differently, so that the thermal conductivities of the thin films are generally anisotropic in these two directions. Therefore, experimental work and theoretical analysis have been conducted to understand the effects of crystallinity, grain sizes, and interfacial structures of AlN and CuI films on their thermal conductivities as a function of film thickness. An improved differential multi-heater 3ω method was established and used to study the thickness-dependency of cross- and in-plane thermal conductivities of CuI and AlN thin films sputtered on p-type doped silicon substrates with film thicknesses varied between 70 - 400 nm and 100 – 1000 nm, respectively. Furthermore, our newly proposed 3ω Microscopy method, which combines the advantages of both the conventional 3ω method and atomic force microscopy (AFM) technology, was applied to quantitatively measure the local thermal conductivities of CuI and AlN thin films, with a spatial resolution in sub-micrometer range. Results revealed that both the cross- and in-plane thermal conductivities of the CuI and AlN thin films were significantly smaller than those of their bulk counterparts. The cross- and in-plane thermal conductivities were strongly dependent on the film thickness. Both the X-ray diffraction and 3ω Microscopy results indicated that the grain size of thin films significantly affected their thermal conductivity due to the scattering effects from the grain boundaries. Finally, the 3ω Microscopy has been proven to provide additional experimental findings, which cannot be identified or detected using conventional thermal characterization methods such as the standard 3ω technique. Its good spatially-resolved resolution for quantitative local thermal characterization, its nondestructive characteristic and without a need for sample preparation, make the 3ω Microscopy a promising thermal characterization method

Differential 3ω method for measuring thermal conductivity of AlN and Si3N4 thin films

The thermal conductivity λ of plasma enhanced chemical vapor deposited Si3N4 and sputtered AlN thin films deposited on silicon substrates were obtained utilizing the differential 3ω method. A thin electrically conductive strip was deposited onto the investigated thin film of interest, and used as both a heater and a temperature sensor. To study the thickness dependent thermal conductivity of AlN and Si3N4 films their thickness was varied from 300 to 1000 nm. Measurements were performed at room temperature at a chamber pressure of 3.1 Pa. The measured thermal conductivity values of AlN and Si3N4 thin films were between 5.4 and 17.6 Wm− 1 K− 1 and 0.8 up to 1.7 Wm− 1 K− 1, respectively. The data were significantly smaller than that of the bulk materials found in literature (i.e., λAlN = 250–285 Wm− 1 K− 1, λSi3N4 = 30 Wm− 1 K− 1), due to the scaling effects, and also strongly dependent on film thickness, but were comparable with literature for the corresponding thin films

Bioavailability of extended-release nevirapine 400 and 300 mg in HIV-1 : a multicenter, open-label study

Nevirapine (NVP) is a widely used non-nucleoside reverse transcriptase inhibitor. A once-daily extended-release (XR) formulation would potentially increase adherence and thus efficacy

Seawater physics and chemistry along the Med-SHIP transects in the Mediterranean Sea in 2016

The Mediterranean Sea has been sampled irregularly by research vessels in the past, mostly by national expeditions in regional waters. To monitor the hydrographic, biogeochemical and circulation changes in the Mediterranean Sea, a systematic repeat oceanographic survey programme called Med-SHIP was recommended by the Mediterranean Science Commission (CIESM) in 2011, as part of the Global Ocean Ship-based Hydrographic Investigations Program (GO-SHIP). Med-SHIP consists of zonal and meridional surveys with different frequencies, where comprehensive physical and biogeochemical properties are measured with the highest international standards. The first zonal survey was done in 2011 and repeated in 2018. In addition, a network of meridional (and other key) hydrographic sections were designed: the first cycle of these sections was completed in 2016, with three cruises funded by the EU project EUROFLEETS2. This paper presents the physical and chemical data of the meridional and key transects in the Western and Eastern Mediterranean Sea collected during those cruises