Long dephasing time and high temperature ballistic transport in an InGaAs open quantum dot

We report on measurements of the magnetoconductance of an open circular InGaAs quantum dot between 1.3K and 204K. We observe two types of magnetoconductance fluctuations: universal conductance fluctuations (UCFs), and 'focusing' fluctuations related to ballistic trajectories between openings. The electron phase coherence time extracted from UCFs amplitude is larger than in GaAs/AlGaAs quantum dots and follows a similar temperature dependence (between T^-1 and T^-2). Below 150K, the characteristic length associated with 'focusing' fluctuations shows a slightly different temperature dependence from that of the conductivity.Comment: 6 pages, 4 figures, proceedings of ICSNN2002, to appear in Physica

SIMS study of deuterium distribution and thermal stability in ZMR SOI structures

SIMS measurements and thermal effusion experiments were performed to study the distribution and thermal stability of deuterium in SOI structures fabricated by zone melting recrystallization technique. It was found that the disordered structure at the silicon-buried oxide interfaces is directly related to the distribution of deuterium in the SOI system. The diffusion coefficient of deuterium in the top silicon layer at 250°C was determined. For the first time, the high-temperature (up to 600°C) stability of deuterium in the buried oxide was demonstrated, without any diffision into silicon layers.У роботі вивчались методами вторинної іонної мас-спектрометрії (ВІМС) і термостимульованої десорбції дейтерію розподілення дейтерію і його термічна стабільність у системі кремній-на-ізоляторі (КНІ), виготовленій за допомогою технології зонної лазерної рекристалізації полікремнію. Показано існування прямого зв.язку між розупорядкуванням структури на межах розподілу кремній-внутрішній діелектрик і розподіленням дейтерію у системі КНІ. Визначено коефіцієнт дифузії дейтерію у кремнієвій рекристалізованій плівці при 250°С. Вперше продемонстровано високотемпературну стабільність дейтерію (до 600°С включно) у внутрішньому діелектрику системи КНІ, за відсутності дифузії дейтерію до кремнієвих шарів.В работе методами вторичной ионной масс-спектрометрии (ВИМС) и термостимулированной десорбции дейтерия изучались распределение дейтерия и его термическая стабильность в структурах кремния-на-изоляторе (КНИ), изготовленных с помощью технологии зонной лазерной рекристаллизации поликремния. Показано существование прямой связи между разупорядочением структуры на границах кремний-внутренний окисел и распределением дейтерия в КНИ системе. Определен коэффициент диффузии дейтерия в рекристаллизованном слое кремния при 250°С. Впервые продемонстрирована высокотемпературная стабильность дейтерия (до 600°С включительно) во внутреннем окисле КНИ структуры при отсутствии диффузии дейтерия в кремниевые слои

Antioxidant, antibacterial and cell toxicity effects of polyphenols Fromahmeur bouamer grape seed extracts

In this work and for the first time, significant concentrations of total polyphenols and flavonoids from Vitis vinifera L. grape seed extracts were obtained (256.15 ± 17.40 mg GAE/gdm and 14.08 ± 0.64 mg CE/gdm, respectively).The LC/MS analysis revealed richness in procyanidins. For antioxidant, antimicrobial and antifungal effects, the grape seed extract (GSE) responded positively. At 100 μg/mL, GSE induced a moderate toxicity of the order of 3.88% on 3T6 cells at the first 24 hours of treatment, whereas, its prolonged effect to 48 hours reduced this toxicity to less than 0.5%. As for the anti-proliferative effect on tumoral cell lines, a cell death of 18.39% to 23.79% and 10.30% to 20.37% was registered respectively for HeLa and BCPAP cells during 24 and 48 hours of treatment. Consequently, it is possible to consider using GSE at lower concentrations as an anti-proliferative agent without losing sight of its benefic effect on healthy cells.Keywords: grape seed extract, 3T6 cell, antioxidant, antibacterial, anti-proliferation

JNK3 Is Required for the Cytoprotective Effect of Exendin 4.

Preservation of beta cell against apoptosis is one of the therapeutic benefits of the glucagon-like peptide-1 (GLP1) antidiabetic mimetics for preserving the functional beta cell mass exposed to diabetogenic condition including proinflammatory cytokines. The mitogen activated protein kinase 10 also called c-jun amino-terminal kinase 3 (JNK3) plays a protective role in insulin-secreting cells against death caused by cytokines. In this study, we investigated whether the JNK3 expression is associated with the protective effect elicited by the GLP1 mimetic exendin 4. We found an increase in the abundance of JNK3 in isolated human islets and INS-1E cells cultured with exendin 4. Induction of JNK3 by exendin 4 was associated with an increased survival of INS-1E cells. Silencing of JNK3 prevented the cytoprotective effect of exendin 4 against apoptosis elicited by culture condition and cytokines. These results emphasize the requirement of JNK3 in the antiapoptotic effects of exendin 4

Novel routes towards bioplastics from plants: elucidation of the methylperillate biosynthesis pathway from <i>Salvia dorisiana </i>trichomes

Plants produce a large variety of highly functionalized terpenoids. Functional groups such as partially unsaturated rings and carboxyl groups provide handles to use these compounds as feedstock for biobased commodity chemicals. For instance, methylperillate, a monoterpenoid found in Salvia dorisiana, may be used for this purpose, as it carries both an unsaturated ring and a methylated carboxyl group. The biosynthetic pathway of methylperillate in plants is still unclear. In this work, we identified glandular trichomes from S. dorisiana as the location of biosynthesis and storage of methylperillate. mRNA from purified trichomes was used to identify four genes that can encode the pathway from geranyl diphosphate towards methylperillate. This pathway includes a (–)-limonene synthase (SdLS), a limonene 7-hydroxylase (SdL7H, CYP71A76), and a perillyl alcohol dehydrogenase (SdPOHDH). We also identified a terpene acid methyltransferase, perillic acid O-methyltransferase (SdPAOMT), with homology to salicylic acid OMTs. Transient expression in Nicotiana benthamiana of these four genes, in combination with a geranyl diphosphate synthase to boost precursor formation, resulted in production of methylperillate. This demonstrates the potential of these enzymes for metabolic engineering of a feedstock for biobased commodity chemicals

How does a cadaver model work for testing ultrasound diagnostic capability for rheumatic-like tendon damage?

To establish whether a cadaver model can serve as an effective surrogate for the detection of tendon damage characteristic of rheumatoid arthritis (RA). In addition, we evaluated intraobserver and interobserver agreement in the grading of RA-like tendon tears shown by US, as well as the concordance between the US findings and the surgically induced lesions in the cadaver model. RA-like tendon damage was surgically induced in the tibialis anterior tendon (TAT) and tibialis posterior tendon (TPT) of ten ankle/foot fresh-frozen cadaveric specimens. Of the 20 tendons examined, six were randomly assigned a surgically induced partial tear; six a complete tear; and eight left undamaged. Three rheumatologists, experts in musculoskeletal US, assessed from 1 to 5 the quality of US imaging of the cadaveric models on a Likert scale. Tendons were then categorized as having either no damage, (0); partial tear, (1); or complete tear (2). All 20 tendons were blindly and independently evaluated twice, over two rounds, by each of the three observers. Overall, technical performance was satisfactory for all items in the two rounds (all values over 2.9 in a Likert scale 1-5). Intraobserver and interobserver agreement for US grading of tendon damage was good (mean κ values 0.62 and 0.71, respectively), with greater reliability found in the TAT than the TPT. Concordance between US findings and experimental tendon lesions was acceptable (70-100 %), again greater for the TAT than for the TPT. A cadaver model with surgically created tendon damage can be useful in evaluating US metric properties of RA tendon lesions

Molecular Characterization of a isoenzyme of the targeting peptide degrading protease, PreP2- catalysis, subcellular localization, expression and evolution

We have previously identified a zinc metalloprotease involved in the degradation of mitochondrial and chloroplast targeting peptides, the presequence protease (PreP). In the Arabidopsis thaliana genomic database, there are two genes that correspond to the protease, the zinc metalloprotease (AAL90904) and the putative zinc metalloprotease (AAG13049). We have named the corresponding proteins AtPreP1 and AtPreP2, respectively. AtPreP1 and AtPreP2 show significant differences in their targeting peptides and the proteins are predicted to be localized in different compartments. AtPreP1 was shown to degrade both mitochondrial and chloroplast targeting peptides and to be dual targeted to both organelles using an ambiguous targeting peptide. Here, we have overexpressed, purified and characterized proteolytic and targeting properties of AtPreP2. AtPreP2 exhibits different proteolytic subsite specificity from AtPreP1 when used for degradation of organellar targeting peptides and their mutants. Interestingly, AtPreP2 precursor protein was also found to be dual targeted to both mitochondria and chloroplasts in a single and dual in vitro import system. Furthermore, targeting peptide of the AtPreP2 dually targeted green fluorescent protein (GFP) to both mitochondria and chloroplasts in tobacco protoplasts and leaves using an in vivo transient expression system. The targeting of both AtPreP1 and AtPreP2 proteases to chloroplasts in A. thaliana in vivo was confirmed via a shotgun mass spectrometric analysis of highly purified chloroplasts. Reverse transcription–polymerase chain reaction (RT–PCR) analysis revealed that AtPreP1 and AtPreP2 are differentially expressed in mature A. thaliana plants. Phylogenetic evidence indicated that AtPreP1 and AtPreP2 are recent gene duplicates that may have diverged through subfunctionalization

Ecological and evolutionary consequences of anticancer adaptations

Cellular cheating leading to cancers exists in all branches of multicellular life, favoring the evolution of adaptations to avoid or suppress malignant progression, and/or to alleviate its fitness consequences. Ecologists have until recently largely neglected the importance of cancer cells for animal ecology, presumably because they did not consider either the potential ecological or evolutionary consequences of anticancer adaptations. Here, we review the diverse ways in which the evolution of anticancer adaptations has significantly constrained several aspects of the evolutionary ecology of multicellular organisms at the cell, individual, population, species, and ecosystem levels and suggest some avenues for future research

A stretchable and biodegradable strain and pressure sensor for orthopaedic application

The ability to monitor, in real time, the mechanical forces on tendons after surgical repair could allow personalized rehabilitation programmes to be developed for recovering patients. However, the development of devices capable of such measurements has been hindered by the strict requirements of biocompatible materials and the need for sensors with satisfactory performance. Here we report an implantable pressure and strain sensor made entirely of biodegradable materials. The sensor is designed to degrade after its useful lifetime, eliminating the need for a second surgery to remove the device. It can measure strain and pressure independently using two vertically isolated sensors capable of discriminating strain as small as 0.4% and the pressure exerted by a grain of salt (12 Pa), without them interfering with one another. The device has minimal hysteresis, a response time in the millisecond range, and an excellent cycling stability for strain and pressure sensing, respectively. We have incorporated a biodegradable elastomer optimized to improve the strain cycling performances by 54%. An in vivo study shows that the sensor exhibits excellent biocompatibility and function in a rat model, illustrating the potential applicability of the device to the real-time monitoring of tendon healing