Shell structure and electron-electron interaction in self-assembled InAs quantum dots

Using far-infrared spectroscopy, we investigate the excitations of self-organized InAs quantum dots as a function of the electron number per dot, 1<n<6, which is monitored in situ by capacitance spectroscopy. Whereas the well-known two-mode spectrum is observed when the lowest s - states are filled, we find a rich excitation spectrum for n=3, which reflects the importance of electron-electron interaction in the present, strongly non-parabolic confining potential. From capacitance spectroscopy we find that the electronic shell structure in our dots gives rise to a distinct pattern in the charging energies which strongly deviates from the monotonic behavior of the Coulomb blockade found in mesoscopic or metallic structures.Comment: 4 pages, 3 PostScript figure

Quantitative trait loci conferring grain mineral nutrient concentrations in durum wheat 3 wild emmer wheat RIL population

Mineral nutrient malnutrition, and particularly deficiency in zinc and iron, afflicts over 3 billion people worldwide. Wild emmer wheat, Triticum turgidum ssp. dicoccoides, genepool harbors a rich allelic repertoire for mineral nutrients in the grain. The genetic and physiological basis of grain protein, micronutrients (zinc, iron, copper and manganese) and macronutrients (calcium, magnesium, potassium, phosphorus and sulfur) concentration was studied in tetraploid wheat population of 152 recombinant inbred lines (RILs), derived from a cross between durum wheat (cv. Langdon) and wild emmer (accession G18-16). Wide genetic variation was found among the RILs for all grain minerals, with considerable transgressive effect. A total of 82 QTLs were mapped for 10 minerals with LOD score range of 3.2–16.7. Most QTLs were in favor of the wild allele (50 QTLs). Fourteen pairs of QTLs for the same trait were mapped to seemingly homoeologous positions, reflecting synteny between the A and B genomes. Significant positive correlation was found between grain protein concentration (GPC), Zn, Fe and Cu, which was supported by significant overlap between the respective QTLs, suggesting common physiological and/or genetic factors controlling the concentrations of these mineral nutrients. Few genomic regions (chromosomes 2A, 5A, 6B and 7A) were found to harbor clusters of QTLs for GPC and other nutrients. These identified QTLs may facilitate the use of wild alleles for improving grain nutritional quality of elite wheat cultivars, especially in terms of protein, Zn and Fe

Zero-field spin splitting in InAs-AlSb quantum wells revisited

We present magnetotransport experiments on high-quality InAs-AlSb quantum wells that show a perfectly clean single-period Shubnikov-de Haas oscillation down to very low magnetic fields. In contrast to theoretical expectations based on an asymmetry induced zero-field spin splitting, no beating effect is observed. The carrier density has been changed by the persistent photo conductivity effect as well as via the application of hydrostatic pressure in order to influence the electric field at the interface of the electron gas. Still no indication of spin splitting at zero magnetic field was observed in spite of highly resolved Shubnikov- de Haas oscillations up to filling factors of 200. This surprising and unexpected result is discussed in view of other recently published data.Comment: 4 pages, 3 figures, submitted to Phys. Rev.

Nanoemulsion stability: experimental evaluation of the flocculation rate from turbidity measurements

The coalescence of liquid drops induces a higher level of complexity compared to the classical studies about the aggregation of solid spheres. Yet, it is commonly believed that most findings on solid dispersions are directly applicable to liquid mixtures. Here, the state of the art in the evaluation of the flocculation rate of these two systems is reviewed. Special emphasis is made on the differences between suspensions and emulsions. In the case of suspensions, the stability ratio is commonly evaluated from the initial slope of the absorbance as a function of time under diffusive and reactive conditions. Puertas and de las Nieves (1997) developed a theoretical approach that allows the determination of the flocculation rate from the variation of the turbidity of a sample as a function of time. Here, suitable modifications of the experimental procedure and the referred theoretical approach are implemented in order to calculate the values of the stability ratio and the flocculation rate corresponding to a dodecane-in-water nanoemulsion stabilized with sodium dodecyl sulfate. Four analytical expressions of the turbidity are tested, basically differing in the optical cross section of the aggregates formed. The first two models consider the processes of: a) aggregation (as described by Smoluchowski) and b) the instantaneous coalescence upon flocculation. The other two models account for the simultaneous occurrence of flocculation and coalescence. The latter reproduce the temporal variation of the turbidity in all cases studied (380 \leq [NaCl] \leq 600 mM), providing a method of appraisal of the flocculation rate in nanoemulsions

Access, provision, and cost of routine eye care: A comparison of Oregon optometrists and ophthalmologists

A study was conducted among optometrists and ophthalmologists that practice in Oregon to measure the differences in several characteristics associated with the provision of routine eye exams, specifically: (1) fees, (2) availability of visual field testing, (3) appointment availability, (4) acceptance of Medicare, and {5) acceptance of Medicaid. A sample of the populations\u27 offices were phoned, a short interview completed, and demographics assessed. Significant differences were found in routine exam fees and availability, provision and fees for visual field testing, and Medicare and/or Medicaid acceptance. Access to optometric care is greater as measured by number of providers, appointment availability and cost. Therefore, optometrists are more accessible and cost effective than other vision care providers

Effect of anticoagulants on fibrin clot structure: a comparison between vitamin K antagonists and factor Xa inhibitors

Background Abnormal clot structure has been identified in patients with thrombotic disorders. Anticoagulant therapy offers clear benefits for thrombosis prevention and treatment by reducing blood clot formation and size; nevertheless, there are limited data on the effects of different anticoagulants, where clotting is initiated with different triggers, on clot structure. Objectives Our aim was to investigate the effects of vitamin K antagonists and factor Xa inhibitors on clot structure. Methods Clots from pooled plasma spiked with rivaroxaban, apixaban, or enoxaparin, as well as plasma from patients on warfarin, were compared to plasma without anticoagulation. The kinetic profile of polymerizing clots was obtained by turbidity, fiber density was determined by confocal microscopy, clot pore size was investigated by permeation, and fiber size was analyzed using scanning electron microscopy. Clotting agonist was either tissue factor or thrombin. Results Following clotting with tissue factor, all anticoagulated clots had a significantly increased lag time, with the exception of enoxaparin. Rivaroxaban additionally led to significantly less dense and more permeable clots, with thicker fibers. In contrast, turbidity analysis following initiation with thrombin showed few effects of anticoagulation, with only enoxaparin leading to a prolonged lag time. Enoxaparin clots made with thrombin were less dense and more permeable. Conclusion Our results show that anticoagulants modulate clot structure particularly when induced by tissue factor, most likely due to reduction of thrombin generation. We propose that the effects of different anticoagulants could be assessed with a global clot structure measurement such as permeation or turbidity, providing information on clot phenotype

Evaluación de aceites y harinas, para nutrición humana, obtenidos de semillas de uvas convencionales y orgánicas Bordô del sur de Brasil

The south of Brazil is one of the largest producers of grapes, and as a consequence there is a large generation of waste that can be used as a profitable alternative source. The aim of this work was to obtain and evaluate oil and the flour for human consumption from the residue of cold-pressed Bordô from conventional and organic grape seeds in a winery in the south of Brazil. By cold pressing, the organic oil obtained higher yield. The quality parameters of the conventional oil were better, although with a higher index of peroxides and iodine. The conventional flour presented better results for quality and centesimal composition, mainly due to the higher fiber content and the fact that it did not contain high acidity or humidity. Therefore, the results of products were similar for both crops, but the conventional one was better. However, traces in the agrochemical residue analysis found for the conventional crop might better qualify the organic products.El sur de Brasil es uno de los mayores productores de uva, por lo que existe una gran generación de residuos que se pueden utilizar como fuente alternativa y rentabilizar. El objetivo de este trabajo es obtener y evaluar los aceites y las harinas, para nutrición humana, del residuo de prensado en frío de las semillas de uva convencionales y orgánicas de Bordô en una bodega del sur de Brasil. Al presionar en frío, el aceite orgánico se obtuvo con gran rendimiento. Los parámetros de calidad del aceite convencional fueron mejores, aunque con un mayor índice de peróxidos y de yodo. La harina de semillas convencionales presentó mejores parámetros de calidad y composición centesimal, principalmente debido al mayor contenido en fibra y no tuvieron acidez alta o humedad. Por lo tanto, los resultados de los productos fueron similares para ambos cultivos, pero el convencional fue mejor. Por otro lado, el análisis de trazas de residuos agroquímicos podrían calificar los productos como orgánicos

Is the inflammasome a potential therapeutic target in renal disease?

The inflammasome is a large, multiprotein complex that drives proinflammatory cytokine production in response to infection and tissue injury. Pattern recognition receptors that are either membrane bound or cytoplasmic trigger inflammasome assembly. These receptors sense danger signals including damage-associated molecular patterns and pathogen-associated molecular patterns (DAMPS and PAMPS respectively). The best-characterized inflammasome is the NLRP3 inflammasome. On assembly of the NLRP3 inflammasome, post-translational processing and secretion of pro-inflammatory cytokines IL-1β and IL-18 occurs; in addition, cell death may be mediated via caspase-1. Intrinsic renal cells express components of the inflammasome pathway. This is most prominent in tubular epithelial cells and, to a lesser degree, in glomeruli. Several primary renal diseases and systemic diseases affecting the kidney are associated with NLRP3 inflammasome/IL-1β/IL-18 axis activation. Most of the disorders studied have been acute inflammatory diseases. The disease spectrum includes ureteric obstruction, ischaemia reperfusion injury, glomerulonephritis, sepsis, hypoxia, glycerol-induced renal failure, and crystal nephropathy. In addition to mediating renal disease, the IL-1/ IL-18 axis may also be responsible for development of CKD itself and its related complications, including vascular calcification and sepsis. Experimental models using genetic deletions and/or receptor antagonists/antiserum against the NLRP3 inflammasome pathway have shown decreased severity of disease. As such, the inflammasome is an attractive potential therapeutic target in a variety of renal diseases

Fibrinogen αC‐regions are not directly involved in fibrin polymerization as evidenced by a "Double‐Detroit" recombinant fibrinogen mutant and knobs‐mimic peptides

Background: Fibrin polymerization, following fibrinopeptides A and B (FpA, FpB) cleavage, relies on newly exposed α‐ and β‐chains N‐termini (GPR, GHR; A‐, B‐knobs, respectively) engaging pre‐existent a and b pockets in other fibrin(ogen) molecules' γ‐ and (B)β‐chains C‐terminal regions. A role for mostly disordered (A)α‐chains C‐terminal regions "bridging" between fibrin molecules/fibrils has been proposed. Objectives: Fibrinogen Detroit is a clinically observed mutation (AαR19→S) with non‐engaging GPS A‐knobs. By analogy, a similar Bβ‐chain mutation, BβR17→S, should produce non‐engaging GHS B‐knobs. A homozygous “Double‐Detroit” mutant (AαR19→S, BβR17→S; DD‐FG) was developed: with A‐a and B‐b engagements endogenously blocked, other interactions would become apparent. Methods: DD‐FG, wild‐type recombinant (WT‐FG), and human plasma (hp‐FG) fibrinogen self‐association was studied by turbidimetry coupled with fibrinopeptides release HPLC/mass spectrometry analyses, and by light‐scattering following size‐exclusion chromatography (SE‐HPLC). Results: In contrast to WT‐FG and hp‐FG, DD‐FG produced no turbidity increase, irrespective of thrombin concentration. The SE‐HPLC profile of concentrated DD‐FG was unaffected by thrombin treatment, and light‐scattering, at lower concentration, showed no intensity and hydrodynamic radius changes. Compared with hp‐FG, both WT‐FG and DD‐FG showed no FpA cleavage difference, while ~50% FpB was not recovered. Correspondingly, SDS‐PAGE/Western‐blots revealed partial Bβ‐chain N‐terminal and Aα‐chain C‐terminal degradation. Nevertheless, ~70% DD‐FG molecules bearing (A)αC‐regions potentially able to associate were available. Higher‐concentration, nearly‐intact hp‐FG with 500‐fold molar excess GPRP‐NH2/GHRP‐NH2 knobs‐mimics experiments confirmed these no‐associations findings. Conclusions: (A)αC‐regions interactions appear too weak to assist native fibrin polymerization, at least without knobs engagement. Their role in all stages should be carefully reconsidered