Characterization of high-temperature PbTe p-n junctions prepared by thermal diffusion and by ion-implantation

We describe here the characteristics of two types of high-quality PbTe p-n-junctions, prepared in this work: (1) by thermal diffusion of In4Te3 gas (TDJ), and (2) by ion implantation (implanted junction, IJ) of In (In-IJ) and Zn (Zn-IJ). The results, as presented here, demonstrate the high quality of these PbTe diodes. Capacitance-voltage and current-voltage characteristics have been measured. The measurements were carried out over a temperature range from ~ 10 K to ~ 180 K. The latter was the highest temperature, where the diode still demonstrated rectifying properties. This maximum operating temperature is higher than any of the earlier reported results. The saturation current density, J0, in both diode types, was ~ 10^-5 A/cm2 at 80 K, while at 180 K J0 ~ 10^-1 A/cm2 in TDJ and ~ 1 A/cm2 in both ion-implanted junctions. At 80 K the reverse current started to increase markedly at a bias of ~ 400 mV for TDJ, and at ~550 mV for IJ. The ideality factor n was about 1.5-2 for both diode types at 80 K. The analysis of the C-V plots shows that the junctions in both diode types are linearly graded. The analysis of the C-V plots allows also determining the height of the junction barrier, the concentrations and the concentration gradient of the impurities, and the temperature dependence of the static dielectric constant. The zero-bias-resistance x area products (R0Ae) at 80 K are: 850 OHMcm2 for TDJ, 250 OHMcm2 for In-IJ, and ~ 80 OHMcm2 for Zn-IJ, while at 180 K R0Ae ~ 0.38 OHMcm2 for TDJ, and ~ 0.1 OHMcm2 for IJ. The estimated detectivity is: D* ~ 10^10 cmHz^(1/2)/W up to T=140 K, determined mainly by background radiation, while at T=180 K, D* decreases to 108-107 cmHz^(1/2)/W, and is determined by the Johnson noise

Teaching Medical Students Optimal Consulting Skills: The Challenge of Generating Better Referring Physicians.

Rationale and objectives We sought to incorporate a new teaching module into the traditional medical student radiology clerkship, to improve the necessary skills for future referring physicians. Materials and methods A new required and graded module was introduced in 2014 into the radiology clerkship in year three of medical school: the Mystery Case. Each student was provided a unique and undifferentiated case from a dedicated teaching file containing de-identified images and requisition data. Students were expected to complete three serial tasks over one week: 1) prepare a voice recognition-derived, structured radiological report utilizing appropriate and relevant vocabulary; 2) discuss pertinent additional clinical information; and 3) discuss appropriate follow-up imaging, in addition to information on how to best prepare patients for these potential patient exams (e.g., with or without contrast, bowel preparation, and length of study). Students were provided written examples and dedicated class instruction with interactive discussions covering specific cases and associated related cases through random pairing with radiology resident and attending mentors. At the close of the week, students gave brief oral presentations of their cases and submitted the tasks for a written evaluation. Upon completion of the clerkship, the students completed a Likert-type six-item survey to evaluate the perceived improvement in select skills. Results The survey was completed by 82% (54/66) of the enrolled students, with 85% finding the Mystery Case an effective use of time. Medical students perceived an improved awareness of the patient care process (77%), awareness of the medical imaging resources available (89%), ability to understand a radiology report (74%), and ability to advise patients (69%). Conclusion Introduction of the Mystery Case as a graded exercise in the medical school radiology clerkship was perceived by students as effective use of time, with an improvement in the skills essential for future referring physicians

Infrared detectors based on semiconductor p-n junction of PbSe

P-n junctions based on physical vapor deposition of thin PbSe films and conductivity type inversion from n- to p-type are developed and characterized over a wide range of temperatures and bias voltages. Photosensitivity and diode characteristics in the thin film PbSe diode structures were found at temperatures up to 300 K. The values of the measured and estimated parameters of these structures demonstrate their high photodetector performance and the potential for development of IR detectors with optimal sensitivity at the highest possible operating temperature

Minority carrier transport in p-ZnO nanowires

In this work, we explore the minority carrier diffusion length in zinc oxide nanowires, using the electron beam-induced current technique. Systematic measurements as a function of temperature were performed on p-type, Sb-doped ZnO film, containing a 4 mu m thick nanowire layer. The minority carrier diffusion length exhibits a thermally activated increase with the energy of 74 +/- 5 meV. Electron beam irradiation also causes the diffusion length increase with the activation energy of 247 +/- 10 meV, likely related to Sb(Zn)-2V(Zn) acceptor-complex

Polimerne mješavine obložene Eudragitom: Potencijalni sustav za kontroliranu peroralnu isporuku teofilina

Sustained release (SR) dosage forms enable prolonged and continuous deposition of the drug in the gastrointestinal (GI) tract and improve the bioavailability of medications characterized by a narrow absorption window. In this study, a new strategy is proposed for the development of SR dosage forms for theophylline (TPH). Design of the delivery system was based on a sustained release formulation, with a modified coating technique and swelling features aimed to extend the release time of the drug. Different polymers, such as Carbopol 71G (CP), sodium carboxymethylcellulose (SCMC), ethylcellulose (EC) and their combinations were tried. Prepared matrix tablets were coated with a 5 % (m/m) dispersion of Eudragit (EUD) in order to get the desired sustained release profile over a period of 24 h. Various formulations were evaluated for drug concentration and in vitro drug release. It was found that the in vitro drug release rate decreased with increasing the amount of polymer. Coating with EUD resulted in a significant lag phase in the first two hours of dissolution in the acidic pH of simulated gastric fluid (SGF) due to decreased water uptake, and hence decreased driving force for drug release. Release became faster in the alkaline pH of simulated intestinal fluid (SIF) owing to increased solubility of both the coating and matrixing agents. The optimized formulation was subjected to in vivo studies in rabbits and the pharmacokinetic parameters of developed formulations were compared with the commercial (Asmanyl®) formulation. Asmanyl® tablets showed faster absorption (tmax 4.0 h) compared to the TPH formulation, showing a tmax value of 8.0 h. The cmax and AUC values of TPH formulation were significantly (p < 0.05) higher than those for Asmanyl®, revealing relative bioavailability of about 136.93 %. Our study demonstrated the potential usefulness of eudraginated polymers for the oral delivery of the sparingly soluble drug theophylline.Pripravci za produljeno oslobađanje (SR) omogućavaju produljeno i kontinuirano oslobađanje lijeka u gastrointestinalnom (GI) traktu i poboljšavaju bioraspoloživost lijekova s uskim apsorpcijskim prozorom. U radu se predlaže nova strategija za razvoj formulacija s produljenim oslobađanjem teofilina (TPH), koja se temelji na sustavu za produljeno oslobađanje, kojem je u svrhu produljenja vremena oslobađanja modificiran način oblaganja i bubrenja. Korišteni su različiti polimeri, kao što su Carbopol 71G (CP), natrijeva karboksimetilceluloza (SCMC), etilceluloza (EC) i njihove kombinacije. Pripravljene matriks tablete obložene su 5-postotnom (m/m) disperzijom Eudragita (EUD) kako bi se postiglo produljeno oslobađanje tijekom 24 h. U pripravljenim formulacijama određena je koncentracija lijeka i in vitro oslobađanje. Rezultati pokazuju da se povećanjem udjela polimera smanjuje brzina oslobađanja in vitro. Oblaganje s EUD značajno je produljilo lag fazu tijekom prva 2 sata otapanja u kiselom pH simuliranog želučanog soka (SGF). Naime, oblaganje usporava ulazak vode i tako smanjuje pogonsku silu za oslobađanje lijeka. Zbog povećane topljivosti obložnog sloja i matriksa u lužnatom mediju, oslobađanje u simuliranoj intestinalnoj tekućini (SIF) je brže. Optimizirana formulacija ispitana je in vivo na zečevima. Farmakokinetički parametri novih formulacija uspoređivani su s komercijalnim pripravkom Asmanyl®. Asmanyl® tablete pokazuju bržu apsorpciju (tmax 4,0 h) u odnosu na TPH formulaciju (tmax 8,0 h). cmax i AUC vrijednosti TPH formulacije bile su značajno (p < 0,05) više od onih za Asmanyl®, što ukazuje na relativnu bioraspoloživost od oko 136,93 %. Stoga smatramo da su polimeri obloženi eudragitom potencijalno korisni za oralnu upotrebu teško topljivog lijeka teofilina

Течение и исходы острого коронарного синдрома в условиях новой коронавирусной инфекции COVID-19

Abstract We analyzed the clinical condition of patients with COVID-19 of varying severity, changes in instrumental and laboratory parameters, and assessed the impact of the severity of the course of a new coronavirus infection on the outcomes of acute coronary syndrome.AIM OF STUDY To study the mutual influence of acute coronary syndrome and the new coronavirus infection COVID-19 on the nature of the course and outcomes of the disease.Materia l and methods In March 21, 2020 – May 31, 2021, 3 625 patients were treated for COVID-19, including 131 patients with acute coronary syndrome due to COVID-19 disease. All patients underwent a number of studies: computed tomography of the chest, electrocardiography, echocardiography, monitoring of biomarkers of myocardial damage, diagnostic coronary angiography and, if necessary, intracoronary therapeutic intervention.Results Data on the distribution of patients with COVID-19 according to the presence or absence of ST segment elevation on the electrocardiogram and the degree of lung tissue damage, as well as information on mortality in these groups, are presented. The role of troponin I in the assessment of myocardial ischemia was analyzed. The direct dependence of its level on the volume of lung damage was found. The inverse relationship was shown between the degree of damage to the lung tissue and the indices of oxygen saturation in the blood. A poor prognostic value of low left ventricular ejection fraction in patients with COVID-19 disease has been described.Conclusions The development of acute coronary syndrome in the course of COVID-19 significantly worsens the prognosis of the disease, which requires the development of algorithms for providing medical care to patients in this category, as well as maximum vigilance in their treatment.ЦЕЛЬ ИССЛЕДОВАНИЯ Изучить взаимное влияние ОКС и НКИ COVID-19 на характер течения и исходы заболевания.МАТЕРИАЛ И МЕТОДЫ В ГБУЗ «НИИ СП им. Н.В. Склифосовского ДЗМ» с 21 марта 2020 по 31 мая 2021 года по поводу COVID-19 находились на лечении 3625 пациентов. В том числе по поводу ОКС на фоне заболевания COVID-19 госпитализирован 131 пациент. Всем больным был проведен ряд исследований: компьютерная томография органов грудной клетки, электрокардиография, эхокардиография, контроль биомаркеров повреждения миокарда, диагностическая коронароангиография и, при необходимости, интракоронарное лечебное вмешательство.РЕЗУЛЬТАТЫ Представлены данные о распределении больных COVID-19 по признаку наличия или отсутствия элевации сегмента ST на электрокардиограмме и степени поражения легочной ткани, а также сведения о летальности в данных группах. Проанализирована роль биомаркера тропонин I в оценке ишемии миокарда. Обнаружена прямая зависимость его уровня от объема повреждения легких. Показана обратная зависимость между степенью поражения легочной ткани и показателями сатурации кислорода в крови. Описано неблагоприятное прогностическое значение низкой фракции выброса левого желудочка у пациентов с заболеванием COVID-19.ЗАКЛЮЧЕНИЕ Развитие острого коронарного синдрома на фоне COVID-19 значительно ухудшает прогноз заболевания, что требует разработки алгоритмов оказания медицинской помощи больным этой категории, а также максимальной настороженности при их лечении

Studies Of Electron Trapping In Zno Semiconductor

It has been recently discovered that electron injection into Phosphorus-, Lithium-, Antimony- or Nitrogen-doped ZnO semiconductor, using electron beam from a Scanning Electron Microscope, as well as a forward bias application to the p-n junction or Schottky barrier, leads to a multiple-fold increase of minority carrier diffusion length and lifetime (1-4). It has also been demonstrated that forward biasing a ZnO-based photovoltaic detector results in a several-fold responsivity enhancement due to a longer minority carrier diffusion length in the detector\u27s p-region as a result of electron injection (5,6). The observed electron injection effects were attributed to the charging of the metastable centers associated with the above-referenced impurities. ©The Electrochemical Society