Tuning the thermoelectric response of silicene nanoribbons with vacancies

In this work, we present a thorough study of the thermoelectric properties of silicene nanoribbons in the presence of a random distribution of atomic vacancies. By using a linear approach within the Landauer formalism, we calculate phonon and electron thermal conductances, the electric conductance, the Seebeck coefficient and the figure of merit of the nanoribbons. We found a sizable reduction of the phonon thermal conductance as a function of the vacancy concentration over a wide range of temperature. At the same time, the electric properties are not severely deteriorated, leading to an overall remarkable thermoelectric efficiency. We conclude that the incorporation of vacancies paves the way for designing better and more efficient nanoscale thermoelectric devices.

Tunable Spin-Polarized Edge Currents in Proximitized Transition Metal Dichalcogenides

We explore proximity-induced ferromagnetism on transition metal dichalcogenides (TMDs), focusing on molybdenum ditelluride ribbons with zigzag edges, deposited on ferromagnetic europium oxide (EuO). A tight-binding model incorporates exchange and Rashba fields induced by proximity to EuO or similar substrates. For in-gap Fermi levels, electronic modes in the nanoribbon are localized along the edges, acting as one-dimensional (1D) conducting channels with tunable spin-polarized currents. TMDs on magnetic substrates can become very useful in spintronics, providing versatile platforms to study the proximity effects and electronic interactions in complex 1D systems.

Enhancement of thermoelectric efficiency by quantum interference effects in trilayer silicene flakes

In recent years, the enhancement of thermoelectric efficiencies has been accomplished in nanoscale systems by making use of quantum effects. We exploit the presence of quantum interference phenomena such as bound states in the continuum and Fano antiresonances in trilayer silicene flakes to produce sharp changes in the electronic transmission of the system. By applying symmetric gate voltages the thermoelectric properties can be tuned and, for particular flake lengths, a great enhancement of the figure of merit can be achieved. We show that the most favorable configurations are those in which the electronic transmission is dominated by the coupling of bound states to the continuum, tuned by an external gate.

A Mayan founder mutation is a common cause of deafness in Guatemala

Over 5% of the world's population has varying degrees of hearing loss. Mutations in GJB2 are the most common cause of autosomal recessive non-syndromic hearing loss (ARNHL) in many populations. The frequency and type of mutations are influenced by ethnicity. Guatemala is a multi-ethnic country with four major populations: Maya, Ladino, Xinca, and Garifuna. To determine the mutation profile of GJB2 in a ARNHL population from Guatemala, we sequenced both exons of GJB2 in 133 unrelated families. A total of six pathogenic variants were detected. The most frequent pathogenic variant is c.131G>A (p.Trp44*) detected in 21 of 266 alleles. We show that c.131G>A is associated with a conserved haplotype in Guatemala suggesting a single founder. The majority of Mayan population lives in the west region of the country from where all c.131G>A carriers originated. Further analysis of genome-wide variation of individuals carrying the c.131G>A mutation compared with those of Native American, European, and African populations shows a close match with the Mayan population.

Electron confinement induced by diluted hydrogen-like ad-atoms in graphene ribbons

We report the electronic properties of two-dimensional systems, which are patterned with ad-atoms in two separated regions. By applying band-folding procedures we are able to predict the energies and the spatial distribution of those impurity-induced states.

Pulse rate estimation using hydraulic bed sensor

We propose in this paper an effective method to obtain the pulse rate from a hydraulic sensor that is placed under the mattress. The sensor captures the superposition of the ballistocardiogram (BCG) and the respiration signals. The BCG is modeled as the j-peak with a frequency modulation component. The proposed method utilizes the Hilbert transform to effectively capture the j-peak, which allows the pulse rate information to come out distinctively in the frequency domain. Among the five subjects tested, the error in pulse rate estimation is less than 1%.

Molecular characterisation of KIR2DS2*005, a fusion gene associated with a shortened KIR haplotype

KIR2DS2 is an activating homologue of KIR2DL2, an inhibitory killer-cell immunoglobulin-like receptor (KIR) that surveys expression of major histocompatibility complex-C allotypes bearing a C1 epitope. We have studied here its allele KIR2DS2*005, which shows a hybrid structure-it is identical to other KIR2DS2 alleles in the ectodomain, but has transmembrane and cytoplasmic regions identical to those of KIR2DS3(*)001, a short-tailed KIR of uncertain expression and function. Our results reveal that KIR2DS2*005 is a fusion gene-the product of an unequal crossing over by which the genes KIR2DS2 and KIR2DS3 recombined within a 400 base pair region of complete identity in intron 6. Also resulting from that recombination was a shortened KIR haplotype of the B group, in which three genes commonly linked to KIR2DS2 (KIR2DL2, KIR2DL5B and KIR2DS3) are deleted. Population studies indicate that KIR2DS2*005 is still associated to such haplotype, and it can be found in approximately 1.2% of Caucasoids. Using a combination of two monoclonal antibodies, we also demonstrate that KIR2DS2*005 encodes a molecule expressed on the surface of natural killer- and T-lymphocytes.

Conductance gaps in graphene ribbons designed by molecular aggregations

The transport properties of graphene nanoribbons with linear benzene-based molecules pinned at the ribbon edges are studied. The systems are described by a single pi-band tight-binding Hamiltonian and by using the Green functions formalism based on real-space renormalization techniques. Different configurations have been considered, such as two and three attached molecules separated by a variable distance d, and the case of a finite array of molecules attached to the ribbon in different geometries (one-side and alternated sequence). In the latter case the conductance behavior is compared with the case of a molecular superlattice-like structure. In these hybrid systems of ribbons with a large number of regular attached foreign structures, we have shown the formation of well-defined energy gaps for which the conductance is completely suppressed. These gaps can be tuned by varying the number, relative distance, and length of the attached molecules. An analysis is performed to understand the nature of the conductance gap and its relation with the foreign molecular structures, providing a mechanism to delineate novel molecular sensors.

Analgesic, anti-inflammatory and antioxidant properties of Buddleja globosa, Buddlejaceae

ETHNOPHARMACOLOGICAL RELEVANCE

Buddleja globosa, known as "matico", is employed in Chile for wound healing.

AIM OF THE STUDY

To validate the traditional use of the crude drug through in vivo and in vitro evaluation of the anti-inflammatory, analgesic and antioxidant properties of its extracts.

MATERIALS AND METHODS

Sequential hexane, dichloromethane, methanol and total methanol extracts were studied using bioguided fractionation. The following activities were investigated: analgesic (writhing test), oral and topic anti-inflammatory (paw- and ear-induced edema), free radical scavenging and antioxidant activities (1,1-diphenyl-2-picrylhydrazyl, DPPH, superoxide anion, lipid peroxidation and xanthine oxidase inhibition). Sodium naproxen, nimesulide, indomethacin were used as reference drugs for in vivo, quercetin and allopurinol for in vitro assays.

RESULTS

A mixture of alpha- and beta-amyrins was isolated from the hexane extract that showed 41.2% of analgesic effect at 600 mg/kg, inhibited by 47.7 and 79.0% the arachidonic acid (AA) and 12-deoxyphorbol-13-decanoate (TPA)-induced inflammation at 3mg/20 microL/ear, respectively. A mixture of beta-sitosterol, stigmasterol, stigmastenol, stigmastanol and campesterol was isolated from the fraction CD4-N and beta-sitosterol-glycoside from the fraction CD5-N, reducing TPA-induced inflammation by 78.2 and 83.7% at 1mg/20 microL/ear, respectively. The fraction CD4-N at 300 mg/kg also showed analgesic activity (38.7%). The methanol extract at 600mg/kg per os showed anti-inflammatory effect (61.4%), topic anti-inflammatory (56.7% on TPA) and analgesic activity (38.5%). Verbascoside and luteolin-7-O-glucoside were the major components of the methanol extract; apigenin 7-O-glucoside was also detected. Inhibition of superoxide anion, lipoperoxidation, and DPPH bleaching effect was found in the methanol serial and global extracts.

CONCLUSIONS

The present report demonstrate the analgesic and anti-inflammatory properties of Buddleja globosa and validate its use in Chilean traditional medicine.

Transport properties of graphene nanoribbons with side-attached organic molecules

In this work we address the effects on the conductance of graphene nanoribbons (GNRs) of organic molecules adsorbed at the ribbon edge. We studied the case of armchair and zigzag GNRs with quasi-one-dimensional side-attached molecules, such as linear poly-aromatic hydrocarbons and poly(para-phenylene). These nanostructures are described using a single-band tight-binding Hamiltonian and their electronic conductance and density of states are calculated within the Green's function formalism based on real-space renormalization techniques. We found that the conductance exhibits an even-odd parity effect as a function of the length of the attached molecules. Furthermore, the corresponding energy spectrum of the molecules can be obtained as a series of Fano antiresonances in the conductance of the system. The latter result suggests that GNRs can be used as a spectrograph sensor device.

Phylogenetic comparison of the DEN-2 Mexican isolate with other flaviviruses

Recent attention has focused on the geographic variation of dengue viruses, since major epidemies may follow introduction of a new virus strain into susceptible populations. We cloned and sequenced a very interesting Mexican isolate (200787/1983) which is antigenically unique by signature analysis with respect to all other dengue-2 topotype viruses. This strain is also unique in biological behavior (neurotropism) and is of epidemiological significance in Mexico. The dengue-2 Mexican isolate sequence information was compared with that of other flaviviruses, analyzing the branching structure of the phylogenetic tree reconstructed from the E gene amino acid sequences. The E glycoprotein, is target for neutralizing antibodies and T-cell responses, and defines the tropism and virulence of flaviviruses. In the phylogram, our strain was located in the position of greatest dissimilarity within serotype-2. Also, frequency analysis of amino acids revealed a very different signature pattern from that found in viral serotype-2.

Blood flow distribution in sorbent beds: analysis of a new sorbent device for hemoperfusion

A new polymer-based sorbent cartridge has been recently developed for enhancing middle molecule removal during hemodialysis. The cartridge (Betasorb, Renaltech, New York, USA) has been designed to be placed in series with the dialyzer in the blood circuit. It is therefore important to evaluate the distribution of flow into the blood compartment of the device in order to assess if the surface of the sorbent is utilized to the best. For this purpose, a special imaging technique was utilized. Cartridges were analyzed during a simulated in vitro circulation at 250 and 350 ml/min of blood flow and 25% and 40% hematocrit. Cartridges were placed in vertical position and a cross longitudinal section 1 cm thick was analyzed in sequence by a helical scanner. Dye was injected into the arterial inlet and the progressive distribution was evaluated by sequential densitometrical measures carried out automatically by the machine. The sequential images analyzed by the scanner demonstrated excellent distribution of the flow in the blood compartment with minimal difference between the central and the peripheral regions of the compartment. In particular the following flow velocity pattern could be observed under the different experimental conditions tested. We may conclude that the cartridge design is adequate and no channelling effects could be detected in the blood compartment. The flow distribution is slightly affected by changes in flow rate and hematocrit showing an optimal utilization of the available surface for molecule adsorption.

[The autopsy findings in 51 cases of AIDS with cardiovascular damage]

We describe the cardiovascular abnormalities found at autopsy in patients with AIDS and a description of the opportunistic infections in these cases studied between January 1988 and August 1993. There were 51 cases with such diagnosis. Pericardial effusion appeared in 9, pleural effusion in 7, myocarditis in 5, 7 with pericarditis, endocarditis in 6, left ventricular hypertrophy in 20, right ventricular hypertrophy in 21 and evidence of atherosclerosis in 15. Thus, data of cardiovascular damage was present in 42.7% of our patients. The cardiovascular abnormalities in this group are common, in contrast to the paucity of clinical findings. Diagnosis of cardiac pathology was made in only 12% of them. So in every case with diagnosis of AIDS, a careful clinical examination and cardiac diagnostic oriented tests must be done for detection of these abnormalities.

Platelet viability following storage for 5 days. Influence of holding whole blood for 8 hours at 20 to 24 degrees C before concentrate preparation

Regional blood centers frequently need to hold units of whole blood at 20 to 24 degrees C for several hours after phlebotomy so that sufficient platelet concentrates can be prepared to meet the increasing need. We have evaluated the in vivo viability and in vitro properties of platelets that were prepared from whole blood drawn into citrate-phosphate-dextrose-adenine (CPDA-1) either immediately after phlebotomy or after an 8-hour hold at 20 to 24 degrees C. Platelet concentrates were stored for 5 days at 20 to 24 degrees C in polyolefin containers (PL 732, Fenwal) with end-over-end tumbler agitation. The autologous in vivo recovery (mean +/- SD) and one-half disappearance of 51Cr-labeled platelets prepared immediately after phlebotomy were 44.4 +/- 9.4 percent and 4.0 +/- 0.5 days, respectively. Platelets prepared after the delay of 8 hours showed a recovery of 44.5 +/- 8.4 percent and a one-half disappearance of 4.1 +/- 0.4 days. After 5 days of storage, platelet concentrates showed a mean pH of 7.21 +/- 0.20 when prepared immediately after phlebotomy, and of 7.22 +/- 0.15 when prepared after an 8-hour delay. Mean morphology scores were 280 +/- 33 and 302 +/- 27 for platelets from units prepared immediately after phlebotomy or after a holding period of 8 hours, respectively. Platelets underwent synergistic aggregation after 5 days of storage, independent of the length of time that the units of whole blood were held prior to centrifugation. These studies indicate that platelet concentrates prepared from units of whole blood held initially for 8 hours can be stored for 5 days at 20 to 24 degrees C and survive satisfactorily in vivo and retain in vitro characteristics.