Normal and inverted hysteresis in perovskite solar cells

Hysteretic effects are investigated in perovskite solar cells in the standard FTO/TiO$_2$/CH$_3$NH$_3$PbI$_{3-x}$Cl$_x$/spiro-OMeTAD/Au configuration. We report normal (NH) and inverted hysteresis (IH) in the J-V characteristics occurring for the same device structure, the behavior strictly depending on the pre-poling bias. NH typically appears at pre-poling biases larger than the open circuit bias, while pronounced IH occurs for negative bias pre-poling. The transition from NH to IH is marked by a intermediate mixed hysteresis behavior characterized by a crossing point in the J-V characteristics. The measured J-V characteristics are explained quantitatively by the dynamic electrical model (DEM). Furthermore, the influence of the bias scan rate on the NH/IH hysteresis is discussed based on the time evolution of the non-linear polarization. Introducing a three step measurement protocol, which includes stabilization, pre-poling and measurement, we put forward the difficulties and possible solutions for a correct PCE evaluation.Comment: 11 pages, 10 figure

Arterial vascularization of the colon; a guide to surgical resection

Background. Colorectal cancer is a commonly diagnosed neoplasia in men and women worldwide. This study aims to rigorously map the arterial distribution of the colon in order to assess the implications of vascular patterns in surgical resection. Methods. Cadaveric dissections were performed to explore the arterial distribution (including collateral blood flow) of the colon. The study used standard dissection tools and photographic documentation to detail the vascular architecture supporting the large intestine. Results. The dissection revealed important arterial branches and anastomoses in the area of the superior and inferior mesenteric arteries, which are able to ensure continuous local blood supply especially in cases of arterial ischemia. An important arterial anastomosis was identified between the right branch of the middle colic artery and the ascending branch of the right colic artery, as well as the specific distribution of the marginal artery of Drummond and Haller-Riolan anastomotic arch. Conclusions. The blood supply of the colon derived from both mesenteric arteries includes redundant arterial anastomoses, but which are critical in specific situations such as the approach and results of surgical resection. Understanding these vascular patterns and collateral pathways, as well as careful intraoperative surgical exploration, are essential for oncologic surgeons to ensure successful colic resections with minimal complications and morbidity

Intraoperative Post-parathyroidectomy Correlation of PTH Hormone Values with Preoperative Scintigraphy

Preoperative parathyroid evaluation through nuclear medicine and intraoperative hormone monitoring has significantly increased the success of the surgical intervention. Material and method: Our study is descriptive, the database is retrospective but it is maintained prospectively. The preoperative protocol included single photon emission computed tomography (SPECT) with the use of technetium-99 sestamibi tracer. We preferred this approach as it allowed 3-D localization of the adenomas. PTH values were obtained from blood drawn from the ipsilateral jugular vein at the regular intervals of 5, 10 and 15 minutes post excision. Results: We had 6 cases with false negative which led to the necessary dissection of the contralateral neck. Two had previous surgery and 4 had tumors in other locations which were observed after the surgical intervention through methodical investigations. We encountered 3 patients with false positive results. 2 had intrathyroidal adenomas and 1 was diagnosed with thyroid papillary carcinoma. Causes of a misinterpretation are related to thyroid disease in association with hyperparathyroidism, a history of parathyroid surgery or multiple locations of hyperproductive parathyroid glands

Evaluation of endothelial dysfunction and its improvement after cardiac rehabilitation

Endothelial function is considered an independent predictor for risk of future cardiovascular events in cardiovascular and noncardiovascular patients. Given the prevalence of cardiovascular disease (CVD), preclinical detection may help modify atherosclerosis and prevent events. Although traditional cardiovascular risk factors relate to future CVD, the predictive value of these risk factors can be relatively limited. Contemporary scientific attention has focused on alternative direct measures of arterial function . Studies have provided unique insights into the pathophysiology of disease processes, the response to treatment and prognostic information that may be helpful in risk prediction. Peripheral measures of endothelial function are now established surrogate markers of vascular risk and have become important markers for clinical research. Cardiac rehabilitation (CR) is of critical importance in the secondary prevention of cardiovascular disease. It has been reported that CR was negatively related to reinfarction, cardiac morbidity and all-cause mortality. The beneficial influence of cardiac rehabilitation on endothelial dysfunction has been demonstrated in many studies, but the the mechanisms by which exercise improves endothelial function are not fully clarified

Enhancement of bone consolidation using high-frequency pulsed electromagnetic fields (HF-PEMFs): An experimental study on rats

In vitro studies showed that high-frequency pulsed electromagnetic fields (HF-PEMFs) increase the activity/expression of early and late osteogenic markers and enhance bone mineralization. The main aim of this study was to investigate the in vivo effects of HF-PEMFs on fracture healing using a rat model. A femur fracture was established by surgery in 20 male Wistar rats. Titanium nails were implanted to reduce and stabilize the fracture. After surgery, 20 rats were equally divided into untreated control and treated group (from the first postoperative day HF-PEMFs at 400 pulses/sec [pps] were applied for 10 minutes/day, for two weeks). Quantitative and qualitative assessment of bone formation was made at two and eight weeks following surgery and included morphological and histological analysis, serological analysis by ELISA, micro-computed tomography (micro-CT), and three-point bending test. At two weeks in HF-PEMF group, soft callus was at a more advanced fibrocartilaginous stage and the bone volume/total tissue volume (BV/TV) ratio in the callus area was significantly higher compared to control group (p = 0.047). Serum concentration of alkaline phosphatase (ALP) and osteocalcin (OC) was significantly higher in HF-PEMF group (ALP p = 0.026, OC p = 0.006) as well as the mechanical strength of femurs (p = 0.03). At eight weeks, femurs from HF-PEMF group had a completely formed woven bone with dense trabeculae, active bone marrow, and had a significantly higher BV/TV ratio compared to control (p = 0.01). HF-PEMFs applied from the first postoperative day, 10 minutes/day for two weeks, enhance bone consolidation in rats, especially in the early phase of fracture healing

Study of forward Z + jet production in pp collisions at √s=7 TeV

A measurement of the $Z(\rightarrow\mu^+\mu^-)$+jet production cross-section in $pp$ collisions at a centre-of-mass energy $\sqrt{s} = 7$ TeV is presented. The analysis is based on an integrated luminosity of $1.0\,\text{fb}^{-1}$ recorded by the LHCb experiment. Results are shown with two jet transverse momentum thresholds, 10 and 20 GeV, for both the overall cross-section within the fiducial volume, and for six differential cross-section measurements. The fiducial volume requires that both the jet and the muons from the Z boson decay are produced in the forward direction ($2.0<\eta<4.5$). The results show good agreement with theoretical predictions at the second-order expansion in the coupling of the strong interaction.A measurement of the $Z(\rightarrow\mu^+\mu^-)$+jet production cross-section in $pp$ collisions at a centre-of-mass energy $\sqrt{s} = 7$ TeV is presented. The analysis is based on an integrated luminosity of $1.0\,\text{fb}^{-1}$ recorded by the LHCb experiment. Results are shown with two jet transverse momentum thresholds, 10 and 20 GeV, for both the overall cross-section within the fiducial volume, and for six differential cross-section measurements. The fiducial volume requires that both the jet and the muons from the Z boson decay are produced in the forward direction ($2.0<\eta<4.5$). The results show good agreement with theoretical predictions at the second-order expansion in the coupling of the strong interaction

Modeling and Simulation of Auxetic Materials for Balistic Protection

A type of structural metamaterials known as auxetics has a negative Poisson's ratio. Auxetic structurals have been found to possess a number of better qualities when compared to traditional ones, including: greater energy absorption, stronger indentation resistance, and enhanced mechanical properties. As a result, auxetic structures are becoming more known as a high-performance, lightweight defensive construction that can survive collisions and blasts

Boala Parkinson. Tratamentul stereotactic neurochirurgical ca tratament combinat

Scientific coordinator: Dan Lîsii Institute of Neurology and NeurosurgeryPD is a chronic and progressive disorder of the central nervous system. For patients with Parkinson's disease who have become unresponsive to pharmacotherapy or have developed severe motor complications due to medical therapy, a number of symptomatic neurosurgical interventions are available: thalamotomy, thalamic stimulation and pallidotomy. Neurosurgical therapies may increasingly complement and extend pharmacologic management of Parkinson's disease. Boala Parkinson este o boală degenerativă a sistemului nervos central. Pentru pacienții cu BP ce nu prezintă un raspuns pozitiv la tratamentul conservator - medicamentos, iar dereglarile motorii sunt datorate tratamentului farmacoterapeutic, sunt recomandate câteva abordari neurochirurgicale de stimulare cerebrală profundă şi lezională, acestea fiind: talamotomia, stimularea talamică și palidotomia. Tratamentul neurochirurgical în BP eventual intensifica, potențează și complimentează tratamentul farmacologic

Advantages of Telescopic Screw in Slipped Capital Femoral Epiphysis Treatment: A Retrospective Study and Review of the Literature

Background: Slipped capital femoral epiphysis is due to proximal femur physis failure in adolescent patients. Early iatrogenic closure of proximal growth cartilage in children with significant residual growth potential causes complications such as coxa breva, coxa vara, and lower limb length inequalities. The Free-Gliding SCFE Screw System is a self-extending cannulated screw used in Slipped Capital Femoral Epiphysis (SCFE) fixation and femoral neck fractures. Materials and Method: We conducted a retrospective study on 16 patients. All patients under 11 years old were treated by telescopic cannulated screws fixation. The youngest patient was 7 years old. Results: Out of the 22 operated hips, 2 screws have failed, thus resulting in a lack of telescoping of the screw. We discovered an average lengthening of approximately 10 mm at 24 months postoperative check-up in 20 hips in which lengthening took place. According to the Notzli method, none of the patients had an alpha angle value greater than 48 degrees. Conclusion: Fixation with telescopic screw for SCFE in patients less than 11 years old, with mild to moderate slippage, allows the continuous growth and remodeling of the proximal femur, thus avoiding deformities such as coxa breva, coxa vara, FAI, AVN, limb length discrepancies and also allows good range of motion