Thermoelectric prospects of nanomaterials with spin-orbit surface bands

Nanostructured composites and nanowire arrays of traditional thermoelectrics like Bi, Bi(1-x)Sb(x) and Bi(2)Te(3) have metallic Rashba surface spin-orbit bands featuring high mobilities rivaling that of the bulk for which topological insulator behavior has been proposed. Nearly pure surface electronic transport has been observed at low temperatures in Bi nanowires with diameter around the critical diameter, 50 nm, for the semimetal-to semiconductor transition. The surface contributes strongly to the thermopower, actually dominating for temperatures T < 100 K in these nanowires. The surface thermopower was found to be -1 T microvolt/(K^2), a value that is consistent with theory. We show that surface electronic transport together with boundary phonon scattering leads to enhanced thermoelectric performance at low temperatures of Bi nanowire arrays. We compare with bulk n-BiSb alloys, optimized CsBi(4)Te(6) and optimized Bi(2)Te(3). Surface dominated electronic transport can be expected in nanomaterials of the other traditional thermoelectrics.Comment: 18 pages, 3 figure

Teriparatide and Pelvic Fracture Healing: A Phase 2 Randomized Controlled Trial

Purpose: To determine if teriparatide (20 ug/day; TPTD) results in improved radiologic healing, reduced pain and improved functional outcome vs. placebo over 3 months in pelvic fracture patients. Methods: This randomized-placebo-controlled study enrolled 35 patients (women and men ≥50 years old) within 4 weeks of pelvic fracture and evaluated the effect of blinded TPTD versus placebo over 3 months on fracture healing. Fracture healing from CT images at 0 and 3 months was assessed as cortical bridging using a 5-point scale. The numeric rating scale (NRS) for pain was administered monthly. Physical performance was assessed monthly by Continuous Summary Physical Performance Score (based on 4m walk speed, timed repeated chair stands, and balance) and the Timed Up and Go (TUG) test. Results: The mean age was 82 and >80% were female. The intention to treat analysis showed no group difference in cortical bridging score and 50% of fractures in TPTD-treated and 53% of fractures in placebo-treated patients were healed at 3 months, unchanged after adjustment for age, sacral fracture, and fracture displacement. Median pain score dropped significantly in both groups with no group differences. Both CSPPS and TUG improved in the teriparatide group, whereas there was no improvement in the placebo group (group difference p<0.03 for CSPPS at 2 and 3 months). Conclusion: In this small randomized, blinded study, there was no improvement in radiographic healing (CT at 3 months) or pain with TPTD vs placebo, however, there was improved physical performance in TPTD-treated subjects that was not evident in the placebo group

Получение компактной меди из карбонатной руды электрохимическим способом

Розглянуто процес електроекстракції міді з розчинів, отриманих вилуговуванням міді з карбонатної руди сульфатною кислотою. Показано, що обробку руди доцільно проводити 10 %-ною кислотою впродовж 30-40 хв при інтенсивному перемішуванні суміші. Здійснено процес електроекстракції міді з концентрованого розчину при ступеневому зниженні густини струму пропорційно до концентрації іонів міді, що зменшується в ході процесу. Виконано порівняння параметрів реального процесу і розрахованого за теоретично отриманими формулами. Встановлено, що прогнозування оптимального режиму електролізу можливо здійснювати за електрохімічними характеристиками, початковою концентрацією металу і геометричними параметрами електрохімічної комірки. Одержано експериментальну залежність напруги на електролізері від концентрації кислоти, іонів міді та густини катодного струму. Виявлено, що основною складовою напруги на електролізері є електрохімічна — різниця потенціалів електродів під струмом. Показано зменшення напруги в часі й розраховано питомі витрати електроенергії при отриманні міді методом електроекстракції.A process of compact copper electrowinning from the solution obtained by leaching copper from the ore by sulfuric acid was discussed. It was shown that the ore leaching is advisable to carry out with 10 % hydrochloric acid for 30-40 minutes with intensive stirring of the mixture. Copper electrowinning process was done from a concentrated solution with a stepped reduction of the current density which was proportional to the copper ion concentration decreasing during the process. The comparison of the parameters of the real and theoretical calculated processes was performed. It was found that the prediction of optimal electrolysis conditions can be achieved by electrochemical characteristics, initial metal concentration and geometric parameters of the electrochemical cell. An experimental cell voltage dependence of the acid concentration, copper ions and the cathode current density was determined. It was found that the main component of the cell voltage is electrochemical component — the difference potential at the electric current. The decreasing of the cell voltage in time was shown and the relative cost of electricity in the producing of copper by electrowinning was calculated.Рассмотрен процесс электроэкстракции меди из растворов, полученных выщелачиванием меди из карбонатной руды серной кислотой. Показано, что обработку руды целесообразно проводить 10 %-ной кислотой в течение 30-40 мин при интенсивном перемешивании смеси. Осуществлен процесс электроэкстракции меди из концентрированного раствора при ступенчатом снижении плотности тока пропорционально концентрации ионов меди, уменьшающейся в ходе процесса. Выполнено сравнение параметров реального процесса и теоретически рассчитанного по формулам. Установлено, что прогнозирование оптимального режима электролиза возможно осуществлять с использованием электрохимических характеристик, начальной концентрации металла и геометрических параметров электрохимической ячейки. Получена экспериментальна зависимость напряжения на электролизере от концентрации кислоты, ионов меди и плотности катодного тока. Определено, что основной составляющей напряжения на электролизере является электрохимическая — разность потенциалов электродов под током. Показано уменьшение напряжения во времени, рассчитаны дельные затраты электроэнергии при получении меди методом электроэкстракции

Untyping Typed Algebras and Colouring Cyclic Linear Logic

We prove "untyping" theorems: in some typed theories (semirings, Kleene algebras, residuated lattices, involutive residuated lattices), typed equations can be derived from the underlying untyped equations. As a consequence, the corresponding untyped decision procedures can be extended for free to the typed settings. Some of these theorems are obtained via a detour through fragments of cyclic linear logic, and give rise to a substantial optimisation of standard proof search algorithms.Comment: 21

Localization of Human RNase Z Isoforms: Dual Nuclear/Mitochondrial Targeting of the ELAC2 Gene Product by Alternative Translation Initiation

RNase Z is an endonuclease responsible for the removal of 3′ extensions from tRNA precursors, an essential step in tRNA biogenesis. Human cells contain a long form (RNase ZL) encoded by ELAC2, and a short form (RNase ZS; ELAC1). We studied their subcellular localization by expression of proteins fused to green fluorescent protein. RNase ZS was found in the cytosol, whereas RNase ZL localized to the nucleus and mitochondria. We show that alternative translation initiation is responsible for the dual targeting of RNase ZL. Due to the unfavorable context of the first AUG of ELAC2, translation apparently also starts from the second AUG, whereby the mitochondrial targeting sequence is lost and the protein is instead routed to the nucleus. Our data suggest that RNase ZL is the enzyme involved in both, nuclear and mitochondrial tRNA 3′ end maturation

: a cis antisense RNA operates in trans in S. aureus

International audienceAntisense RNAs (asRNAs) pair to RNAs expressed from the complementary strand, and their functions are thought to depend on nucleotide overlap with genes on the opposite strand. There is little information on the roles and mechanisms of asRNAs. We show that a cis asRNA acts in trans, using a domain outside its target complementary sequence. SprA1 small regulatory RNA (sRNA) and SprA1(AS) asRNA are concomitantly expressed in S. aureus. SprA1(AS) forms a complex with SprA1, preventing translation of the SprA1-encoded open reading frame by occluding translation initiation signals through pairing interactions. The SprA1 peptide sequence is within two RNA pseudoknots. SprA1(AS) represses production of the SprA1-encoded cytolytic peptide in trans, as its overlapping region is dispensable for regulation. These findings demonstrate that sometimes asRNA functional domains are not their gene-target complementary sequences, suggesting there is a need for mechanistic re-evaluation of asRNAs expressed in prokaryotes and eukaryotes

A survey of green plant tRNA 3'-end processing enzyme tRNase Zs, homologs of the candidate prostate cancer susceptibility protein ELAC2

<p>Abstract</p> <p>Background</p> <p>tRNase Z removes the 3'-trailer sequences from precursor tRNAs, which is an essential step preceding the addition of the CCA sequence. tRNase Z exists in the short (tRNase Z^S) and long (tRNase Z^L) forms. Based on the sequence characteristics, they can be divided into two major types: bacterial-type tRNase Z^Sand eukaryotic-type tRNase Z^L, and one minor type, <it>Thermotoga maritima </it>(TM)-type tRNase Z^S. The number of tRNase Zs is highly variable, with the largest number being identified experimentally in the flowering plant <it>Arabidopsis thaliana</it>. It is unknown whether multiple tRNase Zs found in <it>A. thaliana </it>is common to the plant kingdom. Also unknown is the extent of sequence and structural conservation among tRNase Zs from the plant kingdom.</p> <p>Results</p> <p>We report the identification and analysis of candidate tRNase Zs in 27 fully sequenced genomes of green plants, the great majority of which are flowering plants. It appears that green plants contain multiple distinct tRNase Zs predicted to reside in different subcellular compartments. Furthermore, while the bacterial-type tRNase Z^Ss are present only in basal land plants and green algae, the TM-type tRNase Z^Ss are widespread in green plants. The protein sequences of the TM-type tRNase Z^Ss identified in green plants are similar to those of the bacterial-type tRNase Z^Ss but have distinct features, including the TM-type flexible arm, the variant catalytic HEAT and HST motifs, and a lack of the PxKxRN motif involved in CCA anti-determination (inhibition of tRNase Z activity by CCA), which prevents tRNase Z cleavage of mature tRNAs. Examination of flowering plant chloroplast tRNA genes reveals that many of these genes encode partial CCA sequences. Based on our results and previous studies, we predict that the plant TM-type tRNase Z^Ss may not recognize the CCA sequence as an anti-determinant.</p> <p>Conclusions</p> <p>Our findings substantially expand the current repertoire of the TM-type tRNase Z^Ss and hint at the possibility that these proteins may have been selected for their ability to process chloroplast pre-tRNAs with whole or partial CCA sequences. Our results also support the coevolution of tRNase Zs and tRNA 3'-trailer sequences in plants.</p