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Coronavirus disease 2019 (COVID-19) is a clinical syndrome caused by infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Patients with severe disease show hyperactivation of the immune system, which can affect multiple organs besides the lungs. Here, we propose that SARS-CoV-2 infection induces a process known as immunothrombosis, in which activated neutrophils and monocytes interact with platelets and the coagulation cascade, leading to intravascular clot formation in small and larger vessels. Microthrombotic complications may contribute to acute respiratory distress syndrome (ARDS) and other organ dysfunctions. Therapeutic strategies aimed at reducing immunothrombosis may therefore be useful. Several antithrombotic and immunomodulating drugs have been proposed as candidates to treat patients with SARS-CoV-2 infection. The growing understanding of SARS-CoV-2 infection pathogenesis and how it contributes to critical illness and its complications may help to improve risk stratification and develop targeted therapies to reduce the acute and long-term consequences of this disease.

The controlled growth of chalcogenide nanoscaled phase change material structures can be important to facilitate integration and to enable complex architectures for phase change memory (PCM) and other microelectronic applications. Here, the growth of Sb-Te and In-Ge-Te alloys by Metal-Organic Chemical Vapour Deposition (MOCVD) on patterned substrates featured with an array of recesses (130 nm features width) was investigated. High selectivity, with preferential growth on a CoSi2 metallic layer at the recess bottom with respect to the surrounding SiO2 masking layer, was obtained, leading to a single-step fabrication of arrays of high-aspect-ratio chalcogenide nanostructures. The growth selectivity, as well as the morphology, composition and microstructure of the grown nanostructures, as a function of the different MOCVD process parameters, were investigated by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Energy Dispersive X-Ray (EDX) spectroscopy, Raman spectroscopy and Fourier Transformed Infrared (FTIR) spectroscopy. Thanks to the chosen substrates, the synthesized nanostructures were also directly electrically accessible, as proved by conductive- Atomic Force Microscopy (c-AFM).

A long-standing question for avant-garde data storage technology concerns the nature of the ultrafast photoinduced phase transformations in the wide class of chalcogenide phase-change materials (PCMs). Overall, a comprehensive understanding of the microstructural evolution and the relevant kinetics mechanisms accompanying the out-of-equilibrium phases is still missing. Here, after overheating a phase-change chalcogenide superlattice by an ultrafast laser pulse, we indirectly track the lattice relaxation by time resolved x-ray absorption spectroscopy (tr-XAS) with a sub-ns time resolution. The approach to the tr-XAS experimental results reported in this work provides an atomistic insight of the mechanism that takes place during the cooling process; meanwhile a first-principles model mimicking the microscopic distortions accounts for a straightforward representation of the observed dynamics. Finally, we envisage that our approach can be applied in future studies addressing the role of dynamical structural strain in PCMs.

The aims of this study were to evaluate: (1) the effect of cryopreservation on DNA fragmentation of canine epididymal spermatozoa, and (2) the potential protective effect of melatonin on post-thaw sperm quality (motility, morphology, acrosomal and DNA integrity). Epididymal spermatozoa were collected after orchiectomy of ten dogs. Sperm samples were frozen in the presence or absence of melatonin (1mM). DNA fragmentation index (percentage of spermatozoa with fragmented DNA) was similar in fresh samples (3.3±3.6) and samples frozen with (4.2±3.8) or without (3.6±3.7) melatonin. Sperm motility was significantly (p

Ubiquitin is a 8.5-kDa peptide that tags other proteins for proteasomal degradation. It has been proposed that ubiquitination might be responsible for the elimination of defective spermatozoa during transit through the epididymis in humans and cattle, but its exact biological function in seminal plasma has not yet been clarified. In the domestic cat (Felis catus), the percentage of immature, unviable, and abnormal spermatozoa decreases during the epididymal transit, indicating the existence of a mechanism that removes defective spermatozoa. Magnetic cell separation techniques, based on the use of magnetic beads coated with anti-ubiquitin antibodies, may allow the selective capture of ubiquitinated spermatozoa from semen, thus contributing to the identification of a potential correlation between semen quality and ubiquitination process. Moreover, the selective identification of all the ubiquitinated proteins in different epididymal regions could give a better understanding of the ubiquitin role in feline sperm maturation. The aims of this study were as follows: (1) to verify the possibility of separating ubiquitinated spermatozoa with magnetic ubiquitin beads and identify the morphological and acrosomal differences between whole sample and unbound gametes, (2) to characterize all the ubiquitinated proteins in spermatozoa retrieved in the three epididymal regions by a proteomic approach. The data indicated the presence of ubiquitinated proteins in cat epididymal semen. However, a correlation between abnormal and ubiquitinated spermatozoa has not been found, and ubiquitin cannot be considered as a biomarker of quality of epididymal feline spermatozoa. To the author's knowledge, this is the first identification of all the ubiquitinated proteins of cat spermatozoa collected from different epididymal regions. The proteomic pattern allows a further characterization of cat epididymal semen and represents a contribute to a better understanding of the ubiquitin role in feline sperm maturation.

Phase change memory (PCM) has reached the status of mature technology for stand-alone, embedded, and storage-class memory (SCM). A key requirement for these applications is stability at high temperature (T) during soldering, packaging and operation. To this aim, new materials and algorithms to improve reliability are essential. Here we demonstrate bipolar switching in PCM resulting in low-current operation and excellent high-T reliability. DC and pulsed switching characteristics are explained by ion migration in the chalcogenide layer, as supported by TEM and T-dependent studies. Excellent reliability at high T is demonstrated and explained by a physical model.

Phase change materials based on chalcogenides are key enabling technologies for optical storage, such as rewritable CD and DVD and recently also electrical nonvolatile memory, named phase change memory (PCM). In a PCM, the amorphous or crystalline phase affects the material band structure, hence the device resistance. Although phase transformation is extremely fast and repeatable, the amorphous phase suffers structural relaxation and crystallization at relatively low temperatures, which may affect the temperature stability of PCM state. To improve the time/temperature stability of the PCM, novel operation modes of the device should be identified. Here, we present bipolar switching operation of PCM, which is interpreted by ion migration in the solid state induced by elevated temperature and electric field similar to the bipolar switching in metal oxides. The temperature stability of the high resistance state is demonstrated and explained based on the local depletion of chemical species from the electrode region.

Volatile components of Teucrium marum from Corsica were investigated using a combination of analytical techniques. Analysis of essential oils obtained by hydrodistillation was performed using capillary GC-RI, GC-MS and 13C NMR spectroscopy after fractionation on column chromatography. The emitted volatile fractions from full aerial parts and separated organs of fresh T. marum were investigated using HS-SPME/GC-RI and HS-SPME/GC-MS. The intra-species variations of the chemical compositions of essential oils and volatile fractions from 25 Corsican sample locations were investigated using statistical analysis. The main essential oil components were caryophyllene oxide (0.4-20.5%), (E)-b-caryophyllene (0.9-18.9%), (E)-a-bergamotene (1.0-21.5%), (3Z,6E,10E)-a-springene (1.1-17.8%), b-bisabolene (0.4-14.7%), b-sesquiphellandrene (0.9-10.9%) and estragole (0.5-7.0%), while dolichodial (20.0-83.4%), (E)-a-bergamotene (0.2-20.6%), (E)-b-caryophyllene (0.3-23.1%), dolicholactone (0.4-20.9%), b-bisabolene (0.2-10.0%), estragole (1.1-10.5%) and b-sesquiphellandrene (0.2-8.3%)were the main volatiles emitted by the plant. The 13C-NMR data of (3Z,6E,10E)-a-springene and its occurrence in T. marum essential oils are reported for the first time. The importance of the sample preparation step is discussed through the absence/occurrence of dolichodial in both liquid and gaseous matrices studied, respectively.

A systematic design of practicable media suitable for rewritable, ultrahigh density (>;1Tbit/sq.in.), high data rate (>;1Mbit/s/tip) scanning-probe phase-change memories is presented. The basic design requirements were met by a Si/TiN/Ge2Sb2Te5 (GST)/diamond-like carbon structure, with properly tailored electrical and thermal conductivities. Various alternatives for providing rewritability were investigated. In the first case, amorphous marks were written into a crystalline starting phase and subsequently erased by recrystallization, as in other already established phase-change memory technologies. Results imply that this approach is also appropriate for probe-based memories. However, experimentally, the successful writing of amorphous bits using scanning electrical probes has not been widely reported. In light of this, a second approach has been studied, that of writing crystalline bits in an amorphous starting matrix, with subsequent erasure by reamorphization. With conventional phase-change materials, such as continuous films of GST, this approach invariably leads to the formation of a crystalline “halo” surrounding the erased (reamorphized) region, with severe adverse consequences on the achievable density. Suppression of the “halo” was achieved using patterned media or slow-growth phase-change media, with the latter seemingly more viable.

The thermal properties of the phase-change chalcogenide alloy Ge2Sb2Te5 in its three phases (amorphous, cubic, and hexagonal) and of Si3N4 and SiO2 have been studied to obtain reliable values for device modeling. Thermal conductivity was determined, along with a quantitative estimation of the thermal resistances of the layers’ interfaces, not negligible for highly scaled devices. Electrical resistivity of the chalcogenide material has also been investigated during the phase transition by in situ measurement at constant heating rate.

Brief low-energy helium plasma exposure of mercury cadmium telluride and indium antimonide results in oxide- and elemental-component-free, nearly stoichiometric surfaces. In these initial experiments, the only remaining residue is a topmost trace layer of carbon similar to that present on wet etched and reduced surfaces. The nature of these surfaces was determined by in situ Auger electron spectroscopy, monochromatic X-ray photoelectron, and ion scattering spectroscopy, and compared with established wet chemical and hydrogen argon plasma preparations.

The surface roughness of inductively coupled plasma (ICP)-etched CdTe is greater than that of electron cyclotron resonance (ECR)-etched CdTe. This greater roughness is undesirable for further processing of the material. Lower-frequency plasma excitation from the ICP is more efficient at cracking hydrogen than the high-frequency plasma excitation of ECR. In binary semiconductors it is important to balance removal of both constituents. Bombardment controls the removal of the metal constituent while hydrogen removes the tellurium. Research performed with ECR plasma processing on HgCdTe shows that reducing the pressure can greatly reduce hydrogen ionization. Applying this to ICP it can be shown that reduced pressure greatly improves the morphology of CdTe. This balanced etching also greatly improves etch rate and selectivity of HgCdTe.

Thin TiSiN flat films deposited by MOCVD have been analysed in order to evaluate their microstructure and physical properties. TEM, XRR and RBS techniques have been utilised as complementary analyses to evaluate thickness, density and composition. The main composition is Ti : N : Si = 0.9 : 1.1 : 0.14 with carbon and oxygen up to 5% as a result of organic residuals and oxidation. The analysis shows a layered structure which well correlates with deposition steps. TiN nanocrystals embedded in a SiN x -rich amorphous matrix result confined into each TiSiN deposited layer. The silane soak produces a low concentration silicon inclusion, mainly stabilising the grain boundaries and not affecting the TiN crystalline morphology. AES profiles show that the TiSiN film consists of Ti–N rich layers, separated by C and Si rich “interface” layers which are the result of the process sequence. Densification and crystallisation of the film were observed after high temperature annealing in vacuum, resulting in an electrical resistivity decrease. PECVD deposition of an oxide layer on TiSiN causes a strong oxidation and resistivity increase of the film.

High-density argon-hydrogen plasmas have been demonstrated to be very effective as etchants of CdTe, CdZnTe, and HgCdTe materials for focal plane array applications. Understanding the physical, chemical, and electrical characteristics of these surfaces is critical in elucidating the mechanisms of processing Hg1−xCdxTe. The ways in which these plasmas interact with HgCdTe, such as etch rates and loading, have been studied.1–11 However, little is known on how these plasmas affect the first few atomic layers of HgCdTe. In this study, the effects of high-density plasmas on the surface of HgCdTe were examined. The combination of argon and hydrogen plasma etch leaves a well-ordered, near-stoichiometric surface determined by both x-ray photoelectron spectroscopy and reflection high-energy electron diffraction (RHEED). Starting with Hg0.78Cd0.22Te, we were able to produce surfaces with x=0.4 and a RHEED pattern sharp enough to measure 2×1 reconstruction.

We have examined the formation and removal of native surface films on Hg1−xCdxTe (n-type, x=0.2). Samples were etched with a Br-based solution and then characterized by spectroscopic ellipsometry and X-ray photoelectron spectroscopy. A second set of measurements was acquired after these samples were exposed to air. The results confirm the formation of a surface layer consisting primarily of oxide(s) following an etch of the samples. It also appears that elemental Te may be a component of the postetch film. We presently believe that the predominant components of the oxide are TeO2 and CdO. Following the formation of the native oxide we examined its solubility by immersing the samples in several common liquids. While isopropanol and acetone had little effect, de-ionized water, methanol and ethylene glycol each removed significant portions of the HgCdTe surface oxide. Atomic force microscope images suggest that the removal of the surface film may not be entirely uniform. Additionally, it was shown that storage in de-ionized water, methanol, or isopropanol essentially preserves the postetch surface properties.

The surface of (111)A HgCdTe has been studied by reflection high-energy electron diffraction and atomic force microscopy (AFM). The as-grown liquid-phase epitaxy (LPE) surface has bilayer (3.7 ± 0.2 A) step/terrace structures, macro-steps, and cross-hatch patterns. Macro-steps occur about the \([11\bar 2]\) and are from 10–40 A in height. AFM and x-ray measurements indicate the as-grown epilayer is ≈0.2° off-cut (random polar angle) from the (111). 〈110〉 cross-hatch lines consistent with bilayer (step height=3.9 ± 0.2 A) {111} slip dislocation are observed. The native oxide/carbon layer for the as-grown LPE (111)A HgCdTe is ≈8 A. The experimental results suggest that the as-grown LPE surface approximates an equilibrium vicinal crystal structure. The 0.1% Br:ethylene glycol wet chemically etched surfaces retained the macro-step structure, but numerous small protrusions (10–100 A height, ≈300 A diameter) developed. The plasma-etched (111)A HgCdTe surface is crystalline, but exhibits surface disorder and is roughened.

High-performance 20-µm unit-cell two-color detectors using an n-p+-n HgCdTe triple-layer heterojunction (TLHJ) device architecture grown by molecular beam epitaxy (MBE) on (211)-oriented CdZnTe substrates with midwavelength (MW) infrared and long wavelength (LW) infrared spectral bands have been demonstrated. Detectors with nominal MW and LW cut-off wavelengths of 5.5 µm and 10.5 µm, respectively, exhibit 78 K LW performance with >70 % quantum efficiency, reverse bias dark currents below 300 pA, and RA products (zero field of view, 150-mV bias) in excess of 1×103 Ωcm2. Temperature-dependent current-voltage (I–V) detector measurements show diffusion-limited LW dark current performance extending to temperatures below 70 K with good operating bias stability (150 mV ± 50 mV). These results reflect the successful implementation of MBE-grown TLHJ detector designs and the introduction of advanced photolithography techniques with inductively coupled plasma (ICP) etching to achieve high aspect ratio mesa delineation of individual detector elements with benefits to detector performance. These detector improvements complement the development of high operability large format 640×480 and 1280×720 two-color HgCdTe infrared focal plane arrays (FPAs) to support third generation forward looking infrared (FLIR) systems.

(211) oriented silicon substrates were patterned and etched to give mesas of various sizes and shapes. Cadmium telluride epitaxial layers were deposited on the patterned substrates by molecular beam epitaxy (MBE). Dislocation termini in the epilayer were found to be concentrated in the trenches that formed the mesa boundaries. Mesa sizes up to 17 µm were found to be nearly free of threading dislocation termini. Threading dislocation termini are observed to congregate in lines parallel to the 〈321〉 crystallographic directions. Evidence of subsurface, horizontal dislocations running through the mesa is given.

The surface of (211)B HgCdTe has been studied by reflection high-energy electron diffraction (RHEED) and atomic force microscopy (AFM). RHEED analysis of the as-grown Hg-rich molecular beam epitaxy (MBE) (211)B HgCdTe suggests the surface reconstructs by additional Hg incorporation. The plasma-etched (211)B HgCdTe surface is crystalline but stepped and facetted. RHEED analysis indicates asymmetric pyramids (base dimensions ≈0.5×1.1 nm) are formed to minimize surface Hg concentration. The AFM examination of plasma-etched (211)B HgCdTe reveals oriented mesoscopic features.

Inductively coupled plasma (ICP) using hydrogen-based gas chemistry has been developed to meet requirements for deep HgCdTe mesa etching and shallow CdTe passivation etching in large format HgCdTe infrared focal plane array (FPA) fabrication. Large format 2048×2048, 20-µm unit-cell short wavelength infrared (SWIR) and 2560×512, 25-µm unit-cell midwavelength infrared (MWIR) double-layer heterojunction (DLHJ) p-on-n HgCdTe FPAs fabricated using ICP processing exhibit >99% pixel operability. The HgCdTe FPAs are grown by molecular beam epitaxy (MBE) on Si substrates with suitable buffer layers. Midwavelength infrared detectors fabricated from 4-in. MBE-grown HgCdTe/Si substrates using ICP for mesa delineation and CdTe passivation etching demonstrate measured spectral characteristics, RoA product, and quantum efficiency comparable to detectors fabricated using wet chemical processes. Mechanical samples prepared to examine physical characteristics of ICP reveal plasma with high energy and low ion angle distribution, which is necessary for fine definition, high-aspect ratio mesa etching with accurate replication of photolithographic mask dimensions.

We have examined the etching of HgCdTe (x=0.2) with bromine/ethylene glycol (Br/EG) solutions. Using a spectroscopic ellipsometer, we tracked the ellipsometric parameters (ψ and Δ) of the freshly etched HgCdTe surfaces. Parameters ψ and Δ were measured periodically as these values changed with the surface exposed to air. A second set of Br/EG-etched samples was stored in deionized (DI) water. We found that DI water effectively preserved the freshly etched HgCdTe surface for a period of several hours. Comparison with the literature on HgCdTe surface chemistry implies that oxide growth is inhibited on the etched HgCdTe samples immersed in DI water. Modeling results based on the measured ψ and Δ values agree with this assessment.

We report on the physical attributes of an argon-hydrogen plasma and the effects that induced changes in these attributes have on the physical and electrical characteristics of the plasma itself. Changes in the plasma conditions of these argon-hydrogen plasmas due to variations in microwave power, DC biasing, gas concentrations, and pressures were measured. We determined that increasing the hydrogen flow increases the sheath potential of the plasma, thereby increasing the arrival energy of ions at the surface of a sample placed in the plasma. Even with the decrease in plasma density from an increase in hydrogen input flow, we found the ion current is maintained in the predominately hydrogen plasma and is likely compensated by the high velocity and long mean free path of the hydrogen. We also observed that increasing total pressure also results in hydrogen ions dominating the total number of ions reaching the Langmuir probe and therefore the sample during processing. Last, a model based on the ion/electron energy ratio was developed and used to determine the relative ion concentrations of hydrogen and argon ions.

The heteroepitaxial growth of HgCdTe on large-area Si substrates is an enabling technology leading to the production of low-cost, large-format infrared focal plane arrays (FPAs). This approach will allow HgCdTe FPA technology to be scaled beyond the limitations of bulk CdZnTe substrates. We have already achieved excellent mid-wavelength infrared (MWIR) and short wavelength infrared (SWIR) detector and FPA results using HgCdTe grown on 4-in. Si substrates using molecular beam epitaxy (MBE), and this work was focused on extending these results into the long wavelength infrared (LWIR) spectral regime. A series of nine p-on-n LWIR HgCdTe double-layer heterojunction (DLHJ) detector structures were grown on 4-in. Si substrates. The HgCdTe composition uniformity was very good over the entire 4-in. wafer with a typical maximum nonuniformity of 2.2% at the very edge of the wafer; run-to-run composition reproducibility, realized with real-time feedback control using spectroscopic ellipsometry, was also very good. Both secondary ion mass spectrometry (SIMS) and Hall-effect measurements showed well-behaved doping and majority carrier properties, respectively. Preliminary detector results were promising for this initial work and good broad-band spectral response was demonstrated; 61% quantum efficiency was measured, which is very good compared to a maximum allowed value of 70% for a non-antireflection-coated Si surface. The R0A products for HgCdTe/Si detectors in the 9.6-µm and 12-µm cutoff range were at least one order of magnitude below typical results for detectors fabricated on bulk CdZnTe substrates. This lower performance was attributed to an elevated dislocation density, which is in the mid-106 cm−2 range. The dislocation density in HgCdTe/Si needs to be reduced to

Ion angular distribution (IAD) affects the width and aspect ratio in electron cyclotron resonance (ECR)-etched HgCdTe trenches. The IAD was determined by etching studies together with scanning electron microscopy (SEM) analysis. The results confirm that low-energy, large-angle ions contribute to the etching of the photoresist, while higher-energy, low-angle ions are responsible for HgCdTe etching. The HgCdTe ECR etching was further elucidated by sputter-bombardment theory. This model correctly predicts the nature and depth of the damage region in ECR-etched HgCdTe as well as the distribution and composition of the ejected material.

It has been observed in semiconductor processing that the etch rates for materials subjected to an electron-cyclotron resonance (ECR) plasma change with the total sample area. This phenomenon is known as loading. Loading effects can result in pattern definition errors during micromachining. In argon/hydrogen plasmas, designed to etch II–VI materials, loading appears to primarily affect photoresist deterioration. Using an 80% argon-20% hydrogen gas chemistry optimized for HgCdTe, we observe a factor of 2 variation in photoresist etch rate. Loading may also affect semiconductor etch rates to a lesser extent. The observed trends suggest that radical changes in the plasma are the likely cause of this phenomenon.

The flexible nature of molecular-beam epitaxy (MBE) growth is beneficial for HgCdTe infrared-detector design and allows for tailored growths at lower costs and larger focal-plane array (FPA) formats. Control of growth dynamics gives the MBE process a distinct advantage in the production of multicolor devices, although opportunities for device improvement still exist. Growth defects can inhibit pixel performance and reduce the operability in FPAs, so it is important to understand and evaluate their properties and impact on detector performance. The object of this paper is to understand and correlate the effects of macrodefects on two-color detector performance. We observed the location of single-crystal and polycrystalline regions on planar and cross-sectioned surfaces of two-color device structures when void defects were viewed by scanning electron microscopy (SEM). Compositional analysis via energy dispersive x-ray analysis (EDXA) of voids in the cross section showed elevated Te and reduced Hg when compared to defect-free growth areas. The second portion of this study examined the correlation of macrodefects with pixel operability and diode current-voltage (I–V) characteristics in mid-wavelength infrared (MWIR)/MWIR (M/M) and long wavelength infrared (LWIR)/LWIR (L/L) two-color devices. The probability of diode failure when a void is present is 98% for M/M and 100% for L/L. Voids in two-color detectors also impact diodes neighboring their location; the impact is higher for L/L detectors than M/M detectors. All void-containing diodes showed early breakdown in the I–V characteristics in one or both bands. High dislocation densities were observed surrounding voids; the high density spread further from the void for L/L detectors compared to M/M detectors.

A combination of mechanical experiments and fabrication of very-long-wavelength infrared (VLWIR) HgCdTe-infrared detectors has been used to investigate the interaction between various unit-cell design and dry-etch process variables on final unit-cell dimensions and detector performance. Etch rate, which determines the process time required to achieve a specified etch depth, was found to be a function of both the trench width opening used to delineate an individual detector element in a focal-plane array (FPA) and the mesa profile observed during etching. Current-voltage (I-V) probe data at 78 K demonstrated the successful fabrication of 30 µm unit-cell, VLWIR-HgCdTe diodes with mesa delineation performed by dry etching. The breakdown performance of these diodes is sensitive to trench width and dry-etch process time.

We have investigated the negative luminescence properties of a midwave-infrared (MWIR) HgCdTe photodiode (λco = 5.3 µm at 295 K) grown on a silicon substrate. The internal negative luminescence efficiencies measured using a self-referencing optical technique were 88% throughout the 3–5 µm spectral region and nearly independent of temperature in the 240–300 K range. This corresponds to an apparent temperature reduction of 53 K at room temperature and 35 K at 240 K. Efficiencies measured by an electrical modulation technique were consistent with the measured internal efficiencies and the measured reflectivity of the device. This is the highest efficiency and largest apparent reduction in temperature reported to date, and slightly higher than that measured earlier for photodiodes grown on CdZnTe despite a longer cut-off wavelength. These results provide further indication that the HgCdTe/Si photovoltaic device technology is capable of combining high quality with high yield.

Low-energy electron-enhanced etching (LE4) is applied to HgCdTe to eliminate ion-induced surface damage. First, LE4 results for patterned samples are illustrated. The LE4 mechanism is understood from a mechanistic study in terms of three etch variables: direct current (DC) bias, gas composition, and sample temperature. For this paper, the effects of DC bias (electron energy) and gas composition (CH4 concentration) are summarized qualitatively, followed by quantitative evidence. Etch rate, the amount of polymer, surface stoichiometry, and surface roughness have specific relations with each etch variable under competition between pure LE4 and polymer deposition.

Values of the aspect ratio for trenches etched into HgCdTe by an electron cyclotron resonance (ECR) plasma containing hydrogen and argon are limited by the phenomenon of etch lag. Modeling this plasma as an ion assisted, reactive-etching process leads to a set of conditions that greatly reduces etch lag. Use of these new process conditions produces trenches with aspect ratios greater than 3, widths less than 3 µm, and depths in excess of 15 µm.

Factors that affect width and aspect ratio in electron cyclotron resonance (ECR) etched HgCdTe trenches are investigated. The ECR etch bias and anisotropy are determined by photoresist feature erosion rate. The physical characteristics of the trenches are attributed to a combination of photoresist feature geometry and ECR plasma etch chemistry. This knowledge has led to production of trenches suitable for two-color, 20 µm pitch detectors.

The epitaxial oxidation of the (0 0 1)[1 0 0] textured Ni100−xVx tapes was studied because of the practical interest of NiO as a first buffer layer for the YBCO based coated conductors. The study revealed that the oxidation of the Ni–V alloy is rather complex, the less noble V being internally oxidized, while Ni undergoes an external oxidation. Moreover, the formation of the NiVO3 and of Ni7V5O17 compounds have negative effects on the epitaxial oxidation and on the surface morphology, as well. The role of vanadium on the epitaxial oxidation of Ni–V alloy has not been fully understood yet. The optimum conditions for the epitaxial oxidation have been found to be: 700 ° C, t

This paper presents the design, fabrication and performance of an uncooled micro-optomechanical infrared (IR) imaging system consisting of a focal-plane array (FPA) containing bi-material cantilever pixels made of silicon nitride (SiNx) and gold (Au), which serve as infrared absorbers and thermomechanical transducers. Based on wave optics, a visible optical readout system is designed to simultaneously measure the deflections of all the cantilever beams in the FPA and project the visible deflection map onto a visible charge-coupled device (CCD) imager. The IR imaging results suggest that the detection resolution of current design is 3-5 K, whereas noise analysis indicates the current resolution to be around 1 K. The noise analysis also shows that the theoretical noise-equivalent temperature difference (NETD) of the system can be below 3 mK.

We have developed the capability to grow HgCdTe mid-wave infrared radiation double-layer heterojunctions (MWIR DLHJs) on 4″ Si wafers by molecular beam epitaxy (MBE), and fabricate devices from these wafers that are comparable to those produced by mature technologies. Test data show that the detectors, which range in cutoff wavelength over 4–7 μm, are comparable to the trendline performance of liquid phase epitaxy (LPE)-grown material. The spectral characteristics are similar, with a slight decrease in quantum efficiency attributable to the Si substrate. With respect to R0A, the HgCdTe/Si devices are closer to the theoretical radiative-limit than LPE-grown detectors. Known defect densities in the material have been correlated to device performance through a simple model. Slight 1/f noise increases were measured in comparison to the LPE material, but the observed levels are not sufficient to significantly degrade focal plane array (FPA) performance. In addition to discrete detectors, two FPA formats were fabricated. 128×128 FPAs show MWIR sensitivity comparable to mature InSb technology, with pixel operability values in excess of 99%. A 640×480 FPA further demonstrates the high-sensitivity and high-operability capabilities of this material.

HgCdTe p-on-n double layer heterojunctions (DLHJs) for mid-wave infrared (MWIR) detector applications have been grown on 100 mm (4 inch) diameter (211) silicon substrates by molecular beam epitaxy (MBE). The structural quality of these films is excellent, as demonstrated by x-ray rocking curves with full widths at half maximum (FWHMs) of 80–100 arcsec, and etch pit densities from 1 106 to 7 106 cm−2. Morphological defect densities for these layers are generally less than 1000 cm−2. Improving Hg flux coverage of the wafer during growth can reduce void defects near the edges of the wafers. Improved tellurium source designs have resulted in better temporal flux stability and a reduction of the center to edge x-value variation from 9% to only 2%. Photovoltaic MWIR detectors have been fabricated from some of these 100mm wafers, and the devices show performance at 140 K which is comparable to other MWIR detectors grown on bulk CdZnTe substrates by MBE and by liquid phase epitaxy.

The objective of the present study was to examine the apparent work capacity of one of the two separate membrane systems (the blood-cerebrospinal fluid barrier) that isolate the mammalian brain extracellular fluid (and cerebrospinal fluid, CSF) from plasma. Digitized analyses of electron-microscopic images provided estimates of mitochondrial volumes, which were expressed as a percentage of the cell cytoplasm. We recorded a high mitochondrial content of 12-15% in the cuboidal epithelium of primate choroid plexus, which was consistent in vervet, rhesus, and squirrel monkeys, as well as in baboons. Similarly high mitochondrial contents were observed in the rabbit, rat, and mouse choroid plexus. It has been postulated that the high mitochondrial content of brain endothelium is associated with maintaining the ionic gradients within the central nervous system. We observed that the mitochondrial content of the choroid plexus (where CSF is produced) was slightly higher than in (prior measurements of) the blood-brain barrier (BBB). In addition, surface areas at the apical borders of the choroid plexus epithelia (where the Na+K+ATPase activity has been localized) were increased 7- to 13-fold over the basal borders, in the primate species examined. The observation of high mitochondrial volumes in choroid plexus cells is consistent with the suggestion that increased mitochondrial densities seen in choroidal epithelia and BBB capillaries provide a metabolic work capability for both secretory activities and maintaining ionic gradients across blood-CSF barriers.

Purpose: To investigate the intraocular pressure (IOP) reduction with prostaglandin analogs (PGAs)-timolol fixed combinations versus the unfixed combination of the same PGAs and timolol 0.1% in gel-forming carbomer. Methods: Patients with primary open-angle glaucoma (POAG) receiving for at least 4 weeks the fixed combinations of PGA-timolol, administered once a day in the evening (0.005% latanoprost with 0.5% timolol, 0.004% travoprost with 0.5% timolol, 0.03% bimatoprost with 0.5% timolol) were switched to an unfixed combination of the same PGA (once a day in the evening) with timolol 0.1% in gel-forming carbomer (once a day in the morning) for at least 4 weeks. The primary endpoint was to compare efficacy of fixed vs unfixed combinations in lowering IOP. The effects of both regimens on short-term IOP fluctuations were also assessed. Results: A total of 32 patients (64 eyes) fulfilled inclusion criteria: 17 patients received latanoprost-timolol fixed combination, 9 travoprost-timolol fixed combination, 6 bimatoprost-timolol fixed combination. For all considered time periods each unfixed combination induced an IOP reduction significantly higher than the corresponding fixed combination (paired t test: p

During normal operation of Phase Change Memory (PCM) cells active materials undergo very high electrical and thermal stresses that cause a motion of the different atoms leading to composition variation which has a fundamental impact on performance and reliability. In order to address this issue we introduce here a comprehensive 3D physical model for mass transport in chalcogenide materials. In addition to the driving force for atom diffusion coming from concentration gradient and electric field, the model also accounts for the effect of temperature gradient and phase segregation. This new diffusion model is coupled with a calibrated electro-thermal-phase change model, thus providing a unified framework for the self-consistent simulation of both the electro-thermal and the phase/material change problems. The model is applied to the study of different types of PCM cells showing good agreement with experiments and demonstrating in particular the fundamental role played by the temperature profile.

The negative luminescence of a midwave-infrared HgCdTe photodiode (cutoff wavelength=5.3 μm at 295 K) was investigated using a modulated, self-referencing, optical technique. Internal efficiencies were measured to be 88% throughout the 3–5-μm spectral region, nearly independent of temperature in the 240–300-K range. This corresponds to an apparent temperature reduction of greater than 50 K at room temperature and greater than 35 K at 240 K when the reverse bias is applied. The reverse saturation current density of 1.3 A/cm2 is lower than any reported previously for a negative luminescence device with cutoff wavelength beyond 4 μm.

The phase change active material exploration represents an important stage in order to further strengthen the know-how on the Phase Change Memory (PCM) technology. This work reports a path for PCM material exploration toward the tellurium poor region of the GeSbTe (GST) ternary compound system. Data retention enhancement is reported and associated to a factor 1.5 increase of the crystallization activation energy. A detailed description and discussion of the remarkable electrical and thermal parameters of the PCM cell as a function of GST composition is provided.

Chemical and genetic diversity of Teucrium scorodonia L. subsp. scorodonia from Corsica and T. scorodonia L. subsp. baeticum from western Algeria were investigated. Diversity within and among the two populations of subspecies was assessed according to the chemical composition of their essential oils, and genetic diversity was evaluated using three polymorphic genetic markers. Chemical analysis was performed using a combination of capillary GC-RI and GC/MS after fractionation using column chromatography. Genetic structures were mapped using two chloroplast markers ( RPL32-TRNL and TRNL-F ) and ribosomal nuclear markers (ITS region). The statistical analysis showed that the two subspecies were clearly distinguished by these chemical and genetic markers. The chemical composition of oil differed qualitatively and quantitatively between the subspecies. Corsican oil samples contained germacrene B (4.2–8.8%) and γ-elemene (2.6–5.7%), which were not detected in Algerian oil samples. The oils of the scorodonia and baeticum subspecies were dominated by sesquiterpene hydrocarbon compounds (75.6–82.9% and 69.6–79.4%, respectively), but they differed in oxygenated sesquiterpene content (3.1–8.9% and 8.4–20.3%, respectively). Neighbor-joining trees constructed from chloroplast DNA and ITS region sequences showed the existence of two groups associated with taxonomic and chemical characteristics. One group consisted of T. scorodonia subsp. scorodonia and the other of T. scorodonia subsp. baeticum , indicating that variation in the essential oil composition of T. scorodonia subspecies depends more on genetic background than environmental characteristics.

Silver wires of the superconducting phase (Hg 0.8 Re 0.2 )Ba 2 Ca 2 Cu 3 O 8+ δ (Hg,Re-1223), were prepared by the powder in tube technique followed by a post annealing treatment in a sealed quartz tube. The sintering reaction was carried out inside the quartz tube using a superconducting ceramic pellet and a drop of Hg(l) as external mercury sources. We have studied the amalgamation process in order to avoid the decomposition of the Hg,Re-1223 due to the imminent amalgamation between the silver and the Hg from the superconducting phase. Different annealing treatments of the wires were studied in order to increase the superconducting properties. We have found that using additional liquid Hg as an external source the amalgamation process can be controlled. The critical current density ( J c ) values obtained were similar to the bulk specimens.

The phase-change memory (PCM) technology is considered as one of the most attractive non-volatile memory concepts for next generation data storage. It relies on the ability of a chalcogenide material belonging to the Ge–Sb–Te compound system to reversibly change its phase between two stable states, namely the poly-crystalline low-resistive state and the amorphous high-resistive state, allowing the storage of the logical bit. A careful study of the phase-change material properties in terms of the set operation performance, the program window and the electrical switching parameters as a function of composition is very attractive in order to enlarge the possible PCM application spectrum. Concerning the set performance, a crystallization kinetics based interpretation of the observed behavior measured on different Ge–Sb–Te compounds is provided, allowing a physics-based comprehension of the reset-to-set transition.

The chemical composition of the fatty acid and unsaponifiable fractions of the leaves, stems and roots of Arbutus unedo L. were determined using gas chromatography and gas chromatography-mass spectrometry. The fatty acid fractions of the leaves, stems and roots contained 38.5%, 31.3% and 14.1% palmitic acid, respectively, along with other long-chain fatty acids (up to C22). The chemical composition of the unsaponifiable fractions differed: the leaf and stem fractions contained high levels of aliphatic (32.1% and 62.6%, respectively) and terpenic compounds (49.6% and 25.7%, respectively), and the root fraction mainly contained esters, of which the most abundant was benzyl cinnamate (36.6%). The antimicrobial activities of the unsaponifiable fractions against nine species of microorganisms were assessed. The unsaponifiable leaf and stem extracts inhibited the growth of Klebsiella pneumoniae, Enterococcus faecalis and Candida albicans.

The phase-change memory (PCM) technology represents one of the most attractive concepts for next generation data storage. PCM operation is based on the particular properties of a chalcogenide alloy, the ternary compound Ge 2 Sb 2 Te 5 , which is able to perform fast and reversible transitions between a crystalline, high-conductive phase and an amorphous, low-conductive one, thus enabling the binary data storage. Although the ternary alloy Ge 2 Sb 2 Te 5 is the best recognised solution to meet the device reliability and performance specifications, other alloys are being studied within the GeSbT e ternary compound system in order to investigate and to enlarge the possible spectrum of PCM applications. This work focuses both on the program parameters and on the write performances of a Sb-rich GST composition, suggesting a change in the physical properties of the PCM material and a transition from nucleation to growth-dominated crystallization mechanism, both controlled by the material composition engineering. This enables new challenging performance parameters.

Cistus creticus L., an aromatic species from the Mediterranean area, contains various diterpenes bearing the labdane skeleton. The production of essential oil from this species has potential economic value, but so far, it has not been optimized. In order to contribute to a better knowledge of this species and to its differentiation, the morphological characters, volatile chemical composition and genetic data of two subspecies (C. creticus subsp. eriocephalus and C. creticus subsp. corsicus) were investigated. The leaf trichomes were studied using scanning electron microscopy. The chemical composition of Corsican essential oil (C. creticus subsp. corsicus) has been reported using GC, GC/MS and 13C NMR; the main constituents were oxygenated labdane diterpenes (33.9%) such as 13-epi-manoyl oxide (18.5%). Using plant material (54 samples) collected from 18 geographically distinct areas of the islands of Corsica and Sardinia, the basis of variation in the headspace solid-phase microextraction volatile fraction and an inter-simple sequence repeat genetic analysis were also examined. It was shown that the two subspecies of C. creticus differed in morphology, essential oil production, volatile fraction composition and genetic data.

International audience; In this article we present the first results of a quite simple phenomenological model we have developed to simulate the cationic substitutions in Nd1+xBa2-xCu3O7+x/2-d (Nd123). Although elementary concepts from Statistical Mechanics had been used in it, significant results have been obtained, as the reconstruction of the substitution region limits and their dependence on temperature. Particularly interesting is the prediction of strong temperature dependence for the minimum of the substitution parameter x.

International audience; The aim of the present study was to investigate the association between coronary artery disease (CAD) and Cholesterol Ester Transfer Protein (CETP) (gaaa)n polymorphisms of the CETP gene in Central Corsica island (France). The study group was composed by 300 unrelated Corsican patients with angiographically documented CAD and 300 unrelated healthy blood donors. Significant differences were observed in the distribution of CETP (gaaa)n alleles between the groups under study (p=0.03; chi(2): 16.8, df: 8). The occurrence of a long allele (408 bp) was higher in cases (12%) than in control group (2%), showing a 6.75-fold increased risk for CAD in Corsica patients (p=0.0055; OR=6.750; 95% CIs=1.47-31.00). The correlation of this polymorphism with the lipid profile (cholesterol, low density lipoprotein-cholesterol, high density lipoprotein-cholesterol and triglycerides) in the patients group was determined. There was a significant association of the long alleles of CETP (gaaa)n with HDL-C levels. In the patient and in the control groups the LL genotypes had lower HDL-C compared with the SS and SL genotypes (p

The methylenetetrahydrofolate reductase (MTHFR) is a regulating enzyme in the remethylation pathway of the homocysteine metabolism. Elevated levels of homocysteine during acute Plasmodium falciparum infection suggests an imbalance in the folate cycle, which cod be a selection for the C677T MTHFR allele, driven by P. falciparum. The study of the genetic distribution of the MTHFR polymorphisms in different geographic areas at ex high past malaria prevalence could light up aboua possible selection for the MTHFR polymorphisms driven by malaria. Therefore, we investigated the distributions of the allele frequencies of both the C677T and A1298C mutations in different Mediterranean healthy populations: Sardinia and Sicily (Italy), Corsica and South France (France), Andalusia, Basques and Central Spain (Spain), Arabs from Middle-Western and Berber of Kenifra (North Africa).

Three different population samples from Corsica (France), Sardinia and Sicily (Italy) were studied using nine genetic markers. For the first time, allele distributions of FGA TaqI, FGB Bcl I, FGB Hind III, PAI-1 Hind III, PLAT TPA-25, GPIIIa Taq I, GPIIb I/D 9bp, FVII HVR4 and FVII -323 10 bp markers, which are thought to be associated with cardiovascular disease risk, were studied in the general population of the three islands. The frequencies of the markers analysed in the present work show some peculiarities: the locus FVII HVR4 is characterized by the presence of a rare allele (H5), found in Corsicans and in Sardinians; the locus FBG BcII shows a low frequency of the B1 allele and the absence of the B1B1 genotype. The frequencies of some alleles have a distribution that is in agreement with the low risk for cardiovascular diseases in south European countries. The results highlight a genetic differentiation between the three Mediterranean islands and the other European populations.