1,105 research outputs found
Making ARPES Measurements on Corrugated Monolayer Crystals: Suspended Exfoliated Single-Crystal Graphene
Free-standing exfoliated monolayer graphene is an ultra-thin flexible
membrane, which exhibits out of plane deformation or corrugation. In this
paper, a technique is described to measure the band structure of such
free-standing graphene by angle-resolved photoemission. Our results show that
photoelectron coherence is limited by the crystal corrugation. However, by
combining surface morphology measurements of the graphene roughness with
angle-resolved photoemission, energy dependent quasiparticle lifetime and
bandstructure measurements can be extracted. Our measurements rely on our
development of an analytical formulation for relating the crystal corrugation
to the photoemission linewidth. Our ARPES measurements show that, despite
significant deviation from planarity of the crystal, the electronic structure
of exfoliated suspended graphene is nearly that of ideal, undoped graphene; we
measure the Dirac point to be within 25 meV of . Further, we show that
suspended graphene behaves as a marginal Fermi-liquid, with a quasiparticle
lifetime which scales as ; comparison with other graphene and
graphite data is discussed
A novel promoter controls Cyp19a1 gene expression in mouse adipose tissue
<p>Abstract</p> <p>Background</p> <p>Aromatase, the key enzyme in estrogen biosynthesis, is encoded by the Cyp19a1 gene. Thus far, 3 unique untranslated first exons associated with distinct promoters in the mouse Cyp19a1 gene have been described (brain, ovary, and testis-specific). It remains unknown whether aromatase is expressed in other mouse tissues via novel and tissue-specific promoters.</p> <p>Methods</p> <p>Real-time PCR was used to examine the aromatase expression levels in various C57BL/6 mouse tissues. 5'-rapid amplification of cDNA ends (5'-RACE) was used to determine the transcriptional start sites of Cyp19a1 transcripts. Promoter activity was measured using serial deletion mutants of DNA fused to the luciferase reporter gene. Primary mouse adipose fibroblasts were isolated and cultured from 16-week-old mouse gonadal fat pads.</p> <p>Results</p> <p>We systematically analyzed Cyp19a1 expression in a large number of mouse tissues, and demonstrated for the first time that aromatase was expressed in the male but not female gonadal fat pad. Subcutaneous and brown adipose tissue did not contain detectable Cyp19a1 mRNA. We used 5'-RACE to clone a novel gonadal fat-specific untranslated first exon, which is spliced onto a common junction 15 bp upstream of the translation start site. This adipose-specific first exon was mapped to approximately 75 kb upstream of the translation start site. Transfection of luciferase reporter gene plasmids containing the promoter region upstream of the adipose-specific first exon into murine 3T3-L1 adipose fibroblasts demonstrated significant basal promoter activity conferred primarily by the sequence located at -343/-1 bp. Dexamethasone significantly induced activity of this adipose-specific promoter region. Adipose-specific Cyp19a1 mRNA was expressed in primary mouse adipose fibroblasts and significantly induced by dexamethasone alone or serum plus dexamethasone.</p> <p>Conclusion</p> <p>Taken together, this research identified a novel, adipose-specific first exon of Cyp19a1 and its hormonally regulated promoter region in male murine gonadal fat. These results expand the known 5'-regulatory region of the murine Cyp19a1 gene to 75 kb upstream of the translation start site. Cyp19a1 expression in mouse adipose tissue may play an important role in reproductive biology and lipid metabolism.</p
Effects of adrenalin on ovarian injury formed by ischemia reperfusion in rats
In this study, the impacts of adrenalin on ovarian injury caused by ischemia reperfusion were investigated in rats. In addition, it’s been investigated whether there is a correlation between adrenergic receptors and oxidant/anti-oxidant and COX1/COX-2 levels. It’s been observed that the COX-2 level that is responsible for MDA and inflammatory reaction (which are the indicators of oxidative stress in ovarian tissue to which ischemia reperfusion was applied) increased and the COX-1 levels that are responsible for GSH (an endogenic anti-oxidant with protective impact) were depressed. Adrenalin has prevented an increase in MDA and COX-2 activity in the ovarian tissue, to which I/R was applied, and prevented a reduction in GSH and COX-1 activity. However, adrenalin failed to prevent an MDA increase in ovarian tissue, to which alpha-2 adrenergic receptor blocker yohimbine was given (I/R formed), and also failed to prevent a GSH and COX-1 decrease. Adrenalin also failed to inhibit the COX-2 activity increase in ovarian tissue, to which beta blocker was applied. As a result, stimulation of the alpha-2 adrenergic receptors in an ovarian tissue causes an anti-oxidant and protective effect, while stimulation of beta-2 adrenergic receptors causes an anti-inflammatory effect. It’s been thought that adrenalin protects the ovarian tissue against ischemia reperfusion by stimulating the alpha-2 and beta-2 adrenergic receptors.Colegio de Farmacéuticos de la Provincia de Buenos Aire
On heat transfer at microscale with implications for microactuator design
The dominance of conduction and the negligible effect of gravity, and hence free convection, are verified in the case of microscale heat sources surrounded by air at atmospheric pressure. A list of temperature-dependent heat transfer coefficients is provided. In contrast to previous approaches based on free convection, supplied coefficients converge with increasing temperature. Instead of creating a new external function for the definition of boundary conditions via conductive heat transfer, convective thin film coefficients already embedded in commercial finite element software are utilized under a constant heat flux condition. This facilitates direct implementation of coefficients, i.e. the list supplied in this work can directly be plugged into commercial software. Finally, the following four-step methodology is proposed for modeling: (i) determination of the thermal time constant of a specific microactuator, (ii) determination of the boundary layer size corresponding to this time constant, (iii) extraction of the appropriate heat transfer coefficients from a list provided and (iv) application of these coefficients as boundary conditions in thermomechanical finite element simulations. An experimental procedure is established for the determination of the thermal time constant, the first step of the proposed methodology. Based on conduction, the proposed method provides a physically sound solution to heat transfer issues encountered in the modeling of thermal microactuators
Dizajn maske za lice s UVC-LED zračenjem i njezina djelotvornost protiv uobičajenih klica
During the Covid-19 pandemic, one of the best means of personal protection was using face masks. In this context, the World Health Organization has declared the attempts to produce masks inactivating airborne virus species a welcome initiative. This preliminary study aimed to prove that airborne germs passing through a mask filter cartridge can be destroyed by the rays emitted from UVC LEDs placed in such cartridge. We therefore designed such a face mask and tested the efficiency of UVC LEDs placed in its cartridge against common contaminants, gram-positive Staphylococcus aureus, gram-negative Pseudomonas aeruginosa, and the influenza A/Puerto Rico/8/1934 virus because of its similarity with SARS CoV-2. Eight UVC LEDs with a total power of 75 mW provided sufficient germicidal effect for all three germs. In terms of safety, ozone production released during UVC LED emission was negligible. Our findings are promising, as they show that well-designed UVC-based face masks can be effective against airborne germs, but further research on a greater sample may help us learn more and optimise such face masks.Tijekom pandemije Covida-19 jedan od najboljih oblika osobne zaštite bilo je nošenje maski za lice. U tom je smislu Svjetska zdravstvena organizacija pozdravila pokušaje izrade maski koje ubijaju virusne vrste koje se prenose zrakom. Cilj je ovoga preliminarnog istraživanja bio dokazati da se zrakom nošene klice koje prolaze kroz filtarske uloške mogu uništiti zračenjem UVC ledica smještenih u takve uloške. Stoga smo osmislili masku za lice s tom namjenom i iskušali djelotvornost UVC ledica protiv uobičajenih izvora zaraza: gram-pozitivnoga Staphylococcus aureus, gram-negativnoga Pseudomonas aeruginosa i virusa influence A/Puerto Rico/8/1934 zbog njegove sličnosti s virusom SARS CoV-2. Osam UVC ledica ukupne snage 75 mW iskazale su dovoljan germicidni učinak protiv svih triju klica. U smislu sigurnosti primjene, ozon proizveden tijekom UVC-LED zračenja pokazao se zanemarivim. Naši su rezultati obećavajući jer pokazuju da dobro osmišljene maske za lice s UVC zračenjem mogu biti djelotvorne protiv zrakom nošenih klica, ali će tek daljnja istraživanja na većem uzorku pomoći da doznamo više i usavršimo takve maske za lice
Monolithic Integration of Silicon Nanowires With a Microgripper
Si nanowire (NW) stacks are fabricated by utilizing the scalloping effect of inductively coupled plasma deep reactive ion etching. When two etch windows are brought close enough, scallops from both sides will ideally meet along the dividing centerline of the windows turning the separating material column into an array of vertically stacked strings. Upon further thinning of these NW precursors by oxidation followed by oxide etching, Si NWs with diameters ranging from 50 nm to above 100 nm are obtained. The pattern of NWs is determined solely by photolithography. Various geometries ranging from T-junctions to circular coils are demonstrated in addition to straight NWs along specific crystallographic orientations. The number of NWs in a stack is determined by the number of etch cycles utilized. Due to the precise lithographic definition of NW location and orientation, the technique provides a convenient batch-compatible tool for the integration of NWs with MEMS. This aspect is demonstrated with a microgripper, where an electrostatic actuation mechanism is simultaneously fabricated with the accompanying NW endeffectors. Mechanical integrity of the NW–MEMS bond and the manipulation capability of the gripper are demonstrated. Overall, the proposed technique exhibits a batch-compatible approach to the issue of micronanointegration
Comparison of BNP and NT-proBNP in patients with heart failure and reduced ejection fraction
Both BNP (B-type natriuretic peptide) and NT-proBNP (N-terminal pro B-type natriuretic peptide) are widely used to aid diagnosis, assess the effect of therapy, and predict outcomes in heart failure and reduced ejection fraction. However, little is known about how these 2 peptides compare in heart failure and reduced ejection fraction, especially with contemporary assays. Both peptides were measured at screening in the PARADIGM-HF trial (Prospective Comparison of ARNI With ACEI to Determine Impact on Global Mortality and Morbidity in Heart Failure). Eligibility criteria in PARADIGM-HF included New York Heart Association functional class II to IV, left ventricular ejection fraction ≤40%, and elevated natriuretic peptides: BNP ≥150 pg/mL or NT-proBNP ≥600 pg/mL (for patients with HF hospitalization within 12 months, BNP ≥100 pg/mL or NT-proBNP ≥400 pg/mL). BNP and NT-proBNP were measured simultaneously at screening and only patients who fulfilled entry criteria for both natriuretic peptides were included in the present analysis. The BNP/NT-proBNP criteria were not different for patients in atrial fibrillation. Estimated glomerular filtration rate <30 mL/min per 1.73 m was a key exclusion criterion. The median baseline concentration of NT-proBNP was 2067 (Q1, Q3: 1217-4003) and BNP 318 (Q1, Q3: 207-559), and the ratio, calculated from the raw data, was ≈6.25:1. This ratio varied considerably according to rhythm (atrial fibrillation 8.03:1; no atrial fibrillation 5.75:1) and with age, renal function, and body mass index but not with left ventricular ejection fraction. Each peptide was similarly predictive of death (all-cause, cardiovascular, sudden and pump failure) and heart failure hospitalization, for example, cardiovascular death: BNP hazard ratio, 1.41 (95% CI, 1.33-1.49) per 1 SD increase, <0.0001; NT-proBNP, 1.45 (1.36-1.54); <0.0001. The ratio of NT-proBNP to BNP in heart failure and reduced ejection fraction appears to be greater than generally appreciated, differs between patients with and without atrial fibrillation, and increases substantially with increasing age and decreasing renal function. These findings are important for comparison of natriuretic peptide concentrations in heart failure and reduced ejection fraction
Statin pretreatment and risk of in-hospital atrial fibrillation among patients undergoing cardiac surgery: a collaborative meta-analysis of 11 randomized controlled trials
Aims Statin pretreatment in patients undergoing cardiac surgery is understood to prevent postoperative atrial fibrillation (AF).
However, this is based on observational and limited randomized trial evidence, resulting in uncertainty about any genuine
anti-arrhythmic benefits of these agents in this setting.We therefore aimed to quantify precisely the association between
statin pretreatment and postoperative AF among patients undergoing cardiac surgery.
Methods
and results
A detailed search of MEDLINE and PubMed databases (1st January 1996 to 31st July 2012)was conducted, followed by a
review of the reference lists of published studies and correspondence with trial investigators to obtain individual–
participant data for meta-analysis. Evidence was combined across prospective, randomized clinical trials that compared
the risk of postoperative AF among individuals randomized to statin pretreatment or placebo/control medication before
elective cardiac surgery. Postoperative AF was defined as episodes of AF lasting ≥5 min. Overall, 1105 participants from
11 trials were included; of them, 552 received statin therapy preoperatively. Postoperative AF occurred in 19% of these
participants when compared with 36% of those not treated with statins (odds ratio 0.41, 95% confidence interval
0.31–0.54, P , 0.00001, using a random-effects model). Atrial fibrillation prevention by statin pretreatmentwas consistent
across different subgroups.
Conclusion Short-term statin pretreatment may reduce the risk of postoperative AF among patients undergoing cardiac surgery
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