Fermi Surface and Anisotropic Spin-Orbit Coupling of Sb(111) studied by Angle-Resolved Photoemission Spectroscopy

High-resolution angle-resolved photoemission spectroscopy has been performed on Sb(111) to elucidate the origin of anomalous electronic properties in group-V semimetal surfaces. The surface was found to be metallic despite the semimetallic character of bulk. We clearly observed two surface-derived Fermi surfaces which are likely spin split, demonstrating that the spin-orbit interaction plays a dominant role in characterising the surface electronic states of group-V semimetals. Universality/disimilarity of the electronic structure in Bi and Sb is discussed in relation to the granular superconductivity, electron-phonon coupling, and surface charge/spin density wave.Comment: 4 pages, 3 figures. to be published in Phys. Rev. Let

Designing molecules to bypass the singlet-triplet bottleneck in the electroluminescence of organic light-emitting-diode materials

Electroluminescence in organic light emitting diode (OLED) materials occurs via the recombination of excitonic electrons-hole pairs Only the singlet excitons of commonly used OLED materials, e.g., Aluminum trihydroxyquinoline (AlQ$_3$), decay radiatively, limiting the external quantum efficiency to a maximum 25%. Thus 75% of the energy is lost due to the triplet bottleneck for radiative recombination. We consider molecules derived from AlQ$_3$ which bypass the triplet bottleneck by designing structures which contain strong spin-orbit coupling. As a first stage of this work, groundstate energies and vertical excitation energies of Al-arsenoquinolines and Al-boroarsenoquinolines are calculated. It is found that the substitution of N by As leads to very favourable results, while the boron substitution leads to no advantage.Comment: 4 pages, 4 figue

Magnetothermal Conductivity of Highly Oriented Pyrolytic Graphite in the Quantum Limit

We report on the magnetic field (0T$\le B \le 9$T) dependence of the longitudinal thermal conductivity $\kappa(T,B)$ of highly oriented pyrolytic graphite in the temperature range 5 K $\le T\le$ 20 K for fields parallel to the $c-$axis. We show that $\kappa(T,B)$ shows large oscillations in the high-field region (B > 2 T) where clear signs of the Quantum-Hall effect are observed in the Hall resistance. With the measured longitudinal electrical resistivity we show that the Wiedemann-Franz law is violated in the high-field regime.Comment: 4 Figures, to be published in Physical Review B (2003

Contribution to the understanding of tribological properties of graphite intercalation compounds with metal chloride

Intrinsic tribological properties of lamellar compounds are usually attributed to the presence of van der Waals gaps in their structure through which interlayer interactions are weak. The controlled variation of the distances and interactions between graphene layers by intercalation of electrophilic species in graphite is used in order to explore more deeply the friction reduction properties of low-dimensional compounds. Three graphite intercalation compounds with antimony pentachloride, iron trichloride and aluminium trichloride are studied. Their tribological properties are correlated to their structural parameters, and the interlayer interactions are deduced from ab initio bands structure calculations

The Impact of Lower Extremity Skeletal Muscle Atrophy and Myosteatosis on Revascularization Outcomes in Patients with Peripheral Arterial Disease

Background: This study investigated whether lower extremity muscle atrophy and myosteatosis in patients with peripheral arterial disease (PAD) are correlated to postoperative outcomes, such as reintervention or amputation-free survival. Methods: In this single-center retrospective cohort study of 462 patients treated for peripheral arterial disease scheduled for intervention, muscle mass and the presence of fattening of the lower extremity muscles were measured semiautomatically in a single computed tomography slice of the treated leg. Binary logistic regression models and Cox proportional hazards models were used to determine the effect of muscle atrophy and myosteatosis on reintervention and amputation. Results: Muscle atrophy and myosteatosis increased in PAD patients with Fontaine class IV compared with Fontaine class IIa. In PAD patients with muscle atrophy or myosteatosis, no association was found with the reintervention rate or reintervention-free survival, but an association was found with amputation-free survival, even after adjustment for patient-related, disease-severity, and comorbidities-related factors. Conclusion: Muscle atrophy and mysosteatosis increased in PAD patients with increasing disease severity. Lower extremity muscle atrophy and myosteatosis are associated with amputation rate and amputation-free survival in PAD patients. No association with reintervention rate or reintervention-free survival was found. Muscle atrophy and myosteatosis may serve as additional risk factors in decision making in the often frail vascular patient

Thermal conductivity of tin-doped bismuth between 50 mK and 7K

The authors report on the thermal conductivity of tin-doped bismuth between 50 mK and 27K. A quantitative interpretation of the data is presented. At the lowest temperatures the electronic thermal conductivity dominates, but above 0.1K lattice waves carry most of the heat. Below 1K phonons are scattered mostly by crystal boundaries, while near the dielectric maximum point defects are important. Their scattering rate is directly proportional to the atomic concentration of the tin impurity.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/48999/2/jcv18i15p3001.pd

Validation of a Length-Adjusted Abdominal Arterial Calcium Score Method for Contrast-Enhanced CT Scans

BACKGROUND: The Agatston score on noncontrast computed tomography (CT) scans is the gold standard for calcium load determination. However, contrast-enhanced CT is commonly used for patients with atherosclerotic cardiovascular diseases (ASCVDs), such as peripheral arterial occlusive disease (PAOD) and abdominal aortic aneurysm (AAA). Currently, there is no validated method to determine calcium load in the aorta and peripheral arteries with a contrast-enhanced CT. This study validated a length-adjusted calcium score (LACS) method for contrast-enhanced CT scans.METHOD: The LACS (calcium volume in mm 3/arterial length in cm) in the abdominal aorta was calculated using four-phase liver CT scans of 30 patients treated between 2017 and 2021 at the University Medical Center Groningen (UMCG) with no aortic disease. Noncontrast CT scans were segmented with a 130 Hounsfield units (HU) threshold, and a patient-specific threshold was used for contrast-enhanced CTs. The LACS was calculated and compared from both segmentations. Secondly, the interobserver variability and the influence of slice thickness (0.75 mm vs. 2.0 mm) was determined. RESULTS: There was a high correlation between the LACS from contrast-enhanced CT scans and the LACS of noncontrast CTs ( R 2 = 0.98). A correction factor of 1.9 was established to convert the LACS derived from contrast-enhanced CT to noncontrast CT scans. LACS interobserver agreement on contrast-enhanced CT was excellent (1.0, 95% confidence interval = 1.0-1.0). The 0.75 mm CT threshold was 541 (459-625) HU compared with 500 (419-568) HU on 2 mm CTs ( p = 0.15). LACS calculated with both thresholds was not significantly different ( p = 0.63). CONCLUSION: The LACS seems to be a robust method for scoring calcium load on contrast-enhanced CT scans in arterial segments with various lengths.</p

Association of iliofemoral calcium score and major vascular complications within the first year after lower limb endovascular revascularization

BACKGROUND: The accumulation of calcium load in peripheral lower extremity arteries has been associated with increased severity of peripheral arterial disease (PAD) and mortality. While calcium scores are commonly calculated from non-contrast computed tomography (CT) scans, patients with PAD often undergo contrast-enhanced CT scans. This study aims to explore the association between a length-adjusted calcium score (LACS) of the iliofemoral arteries, determined through pre-intervention contrast-enhanced CT, and major adverse events in patients with chronic limb-threatening ischemia (CLTI).METHODS: A cohort of CLTI patients subjected to endovascular revascularization between 2005 and 2017 at a tertiary referral center were categorized into two groups. The complication group experienced one of the composite outcomes (reintervention, above-the-ankle amputation, and/or all-cause mortality within one year of the primary endovascular procedure), while control patients did not encounter this composite endpoint. Patients from the complication group were matched one-to-one with controls based on sex and Fontaine classification. LACS was calculated (Ca volume[mm3]/length[cm]) at three arterial segments; 1. the common iliac artery (CIA), 2. the external iliac artery and common femoral artery (EIA+CFA), and 3. the superficial femoral artery plus the popliteal artery (SFA+PA). Binary logistic regression analysis was conducted to investigate the association between LACS in the different arterial segments and the occurrence of the composite binary outcome (complication and control) and LACS of the different segments, adjusting influences of age, sex, BMI &gt;25, Fontaine classification, diabetes mellitus type 1 &amp; 2, chronic kidney disease stage, and hemodialysis treatment.RESULTS: Sixty-four CLTI patients were included in this study (complication group [n=32], and control group [n=32]). A significant difference (higher LACS was found for the complication group in the CIA, the SFA+PA, as well as the total trajectory. CLTI patients with high LACS in the SFA+PA or the total trajectory were more likely to suffer adverse events (SFA+PA: OR: 1.010, 95% CI: 1.000-1.020, p=0.04; Total LACS: OR: 1.008, 95% CI: 1.000-1.017, p=0.05).CONCLUSIONS: Patients with a high calcium load in the ilio-femoral arteries are at increased risk of major adverse events during one year after endovascular revascularization. The calcium score, derived from contrast-enhanced CT scans, holds potential utility in decision making for CLTI patients.</p

Tubulinosema loxostegi sp. n. (Microsporidia: Tubulinosematidae) from the Beet Webworm Loxostege sticticalis L. (Lepidoptera: Crambidae) in Western Siberia

Adults of beet webworm Loxostege sticticalis were collected in Western Siberia in 2009 and 2010. A microsporidium was found infecting 12 of 50 moths in 2010. The parasite develops in direct contact with host cell cytoplasm, sporogony is presumably disporoblastic. The spores are ovoid, diplokaryotic, 4.2 × 2.4 μm in size (fresh), without a sporophorous vesicle. Electron microscopy showed: (a) tubules on the surface of sporoblasts and immature spores; (b) slightly anisofilar polar tube with 10–14 coils, last 2–3 coils of lesser electron density; (c) bipartite polaroplast with anterior and posterior parts composed of thin and thick lamellae, respectively; (d) an indentation in the region of the anchoring disc; (e) an additional layer of electron-dense amorphous matter on the exospore surface. The spore ultrastructure is characteristic of the genus Tubulinosema. Sequencing of small subunit and large subunit ribosomal RNA genes showed 98–99.6% similarity of this parasite to the Tubulinosema species available on Genbank. A new species Tubulinosema loxostegi sp. n. is established

Diameter-dependent thermopower of Bi nanowires

We present a study of electronic transport in individual Bi nanowires of large diameter relative to the Fermi wavelength. Measurements of the resistance and thermopower of intrinsic and Sn-doped Bi wires with various wire diameters, ranging from 150-480 nm, have been carried out over a wide range of temperatures (4-300 K) and magnetic fields (0-14 T). We find that the thermopower of intrinsic Bi wires in this diameter range is positive (type-p) below about 150 K, displaying a peak at around 40 K. In comparison, intrinsic bulk Bi is type-n. Magneto-thermopower effects due to the decrease of surface scattering when the cyclotron diameter is less than the wire diameter are demonstrated. The measurements are interpreted in terms of a model of diffusive thermopower, where the mobility limitations posed by hole-boundary scattering are much less severe than those due to electron-hole scattering.Comment: 32 pages, 12 figures. Previous version replaced to improve readabilit