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1.
Medicina (Kaunas) ; 60(7)2024 Jun 30.
Artículo en Inglés | MEDLINE | ID: mdl-39064507

RESUMEN

Background and Objectives: Heart transplant is currently the final step in treating patients with heart failure. The success of this procedure is strongly connected to potential complications such as postoperative heart failure, infections, graft rejection, graft vasculopathy, and kidney failure. Thus, identifying potential prognostic factors for patients' outcome is of utmost importance. We investigated the prognostic role of the postoperative ratio between the tricuspid annular plane systolic excursion (TAPSE) and systolic pulmonary artery pressure (sPAP) in patients who underwent heart transplantation in our center. Materials and Methods: The study included 46 adult patients from the Emergency Institute for Cardiovascular Diseases and Transplant of Târgu Mureș, who underwent heart transplant between January 2011 and April 2023. By the use of receiver operating characteristic (ROC) analysis, we determined an optimal cut-off value for TAPSE/sPAP with regard to survival at 6 months. Differences in central tendencies of baseline characteristics in those who had a value lower than the cut-off value of TAPSE/sPAP and those who presented a value above it were investigated using the corresponding parametric or nonparametric tests. Results: A value for TAPSE/sPAP above 0.47 mm/mmHg was associated with 6-month survival (OR: 59.5, CI: 5.7-616.0). No significant differences in central tendencies for baseline characteristics were found between the patients who had a TAPSE/sPAP ratio below the cut-off and those who had a ratio above it. Conclusions: The TAPSE/sPAP ratio might prove to be valuable in the early identification of at-risk heart transplant patients. Further prospective studies with larger cohorts are required for validation.


Asunto(s)
Trasplante de Corazón , Arteria Pulmonar , Válvula Tricúspide , Humanos , Trasplante de Corazón/efectos adversos , Masculino , Femenino , Persona de Mediana Edad , Válvula Tricúspide/fisiopatología , Válvula Tricúspide/diagnóstico por imagen , Válvula Tricúspide/cirugía , Arteria Pulmonar/fisiopatología , Arteria Pulmonar/diagnóstico por imagen , Pronóstico , Adulto , Curva ROC , Anciano , Sístole/fisiología , Ecocardiografía/métodos , Estudios Retrospectivos , Insuficiencia Cardíaca/fisiopatología , Presión Sanguínea/fisiología
2.
Sensors (Basel) ; 23(16)2023 Aug 11.
Artículo en Inglés | MEDLINE | ID: mdl-37631663

RESUMEN

Digital Twins serve as virtual counterparts, replicating the characteristics and functionalities of tangible objects, processes, or systems within the digital space, leveraging their capability to simulate and forecast real-world behavior. They have found valuable applications in smart farming, facilitating a comprehensive virtual replica of a farm that encompasses vital aspects such as crop cultivation, soil composition, and prevailing weather conditions. By amalgamating data from diverse sources, including soil, plants condition, environmental sensor networks, meteorological predictions, and high-resolution UAV and Satellite imagery, farmers gain access to dynamic and up-to-date visualization of their agricultural domains empowering them to make well-informed and timely choices concerning critical aspects like efficient irrigation plans, optimal fertilization methods, and effective pest management strategies, enhancing overall farm productivity and sustainability. This research paper aims to present a comprehensive overview of the contemporary state of research on digital twins in smart farming, including crop modelling, precision agriculture, and associated technologies, while exploring their potential applications and their impact on agricultural practices, addressing the challenges and limitations such as data privacy concerns, the need for high-quality data for accurate simulations and predictions, and the complexity of integrating multiple data sources. Lastly, the paper explores the prospects of digital twins in agriculture, highlighting potential avenues for future research and advancement in this domain.


Asunto(s)
Agricultura , Suelo , Granjas , Tecnología , Exactitud de los Datos
3.
Sensors (Basel) ; 23(4)2023 Feb 14.
Artículo en Inglés | MEDLINE | ID: mdl-36850756

RESUMEN

BACKGROUND AND OBJECTIVES: In the early period after liver transplantation, patients are exposed to a high rate of complications and several scores are currently available to predict adverse postoperative outcomes. However, an ideal, universally accepted and validated score to predict adverse events in liver transplant recipients with hepatitis C is lacking. Therefore, we aimed to establish and validate a machine learning (ML) model to predict short-term outcomes of hepatitis C patients who underwent liver transplantation. MATERIALS AND METHODS: We conducted a retrospective observational two-center cohort study involving hepatitis C patients who underwent liver transplantation. Based on clinical and laboratory parameters, the dataset was used to train a deep-learning model for predicting short-term postoperative complications (within one month following liver transplantation). Adverse events prediction in the postoperative setting was the primary study outcome. RESULTS: A total of 90 liver transplant recipients with hepatitis C were enrolled in the present study, 80 patients in the training cohort and ten in the validation cohort, respectively. The age range of the participants was 12-68 years, 51 (56,7%) were male, and 39 (43.3%) were female. Throughout the 85 training epochs, the model achieved a very good performance, with the accuracy ranging between 99.76% and 100%. After testing the model on the validation set, the deep-learning classifier confirmed the performance in predicting postoperative complications, achieving an accuracy of 100% on unseen data. CONCLUSIONS: We successfully developed a ML model to predict postoperative complications following liver transplantation in hepatitis C patients. The model demonstrated an excellent performance for accurate adverse event prediction. Consequently, the present study constitutes the foundation for careful and non-invasive identification of high-risk patients who might benefit from a more intensive postoperative monitoring strategy.


Asunto(s)
Hepatitis C , Trasplante de Hígado , Adolescente , Adulto , Anciano , Niño , Femenino , Humanos , Masculino , Persona de Mediana Edad , Adulto Joven , Estudios de Cohortes , Hepacivirus , Aprendizaje Automático , Estudios Retrospectivos , Rumanía
4.
Eur Heart J ; 38(31): 2431-2439, 2017 Aug 14.
Artículo en Inglés | MEDLINE | ID: mdl-28821169

RESUMEN

AIMS: Patients receiving direct oral anticoagulants (DOACs) frequently undergo elective invasive procedures. Their management is challenging. We aimed to determine the optimal duration of DOAC discontinuation that ensures a minimal anticoagulant effect during the procedure. METHODS AND RESULTS: This prospective multicentre study included 422 DOAC-treated patients requiring an invasive procedure. Pre-procedural DOAC concentration ([DOAC]) and routine haemostasis assays were performed to determine i/the proportion of patients who achieved a minimal pre-procedural [DOAC] (≤30 ng/mL) according to the duration of DOAC discontinuation, ii/the predictors of minimal [DOAC] and, iii/the ability of routine assays to predict minimal [DOAC]. Lastly, we assessed the predictors of peri-procedural bleeding events. The duration of DOAC discontinuation ranged from 1 to 218 h and pre-procedural [DOAC] from ≤30 to 527 ng/mL. After a 49-72-h discontinuation, 95% of the [DOAC] were ≤30 ng/mL. A 72-h discontinuation predicted concentrations ≤30 ng/mL with 91% specificity. In multivariable analysis, duration of DOAC discontinuation, creatinine clearance <50 mL/min and antiarrhythmics were independent predictors of minimal pre-procedural [DOAC] (concordance statistic 0.869; 95% confidence interval: 0.829-0.912). Conversely, routine haemostasis assays were poor predictors. Last, creatinine clearance <50 mL/min, antiplatelets and high-bleeding risk procedures were predictors of bleeding events. CONCLUSION: A last DOAC intake 3 days before a procedure resulted in minimal pre-procedural anticoagulant effect for almost all patients. Moderate renal impairment, especially in dabigatran-treated patients, and antiarrhythmics in anti-Xa-treated patients should result in a longer DOAC interruption. In situations requiring testing, routine assays should not replace DOAC concentration measurement.


Asunto(s)
Anticoagulantes/administración & dosificación , Administración Oral , Adulto , Anciano , Anciano de 80 o más Años , Anticoagulantes/metabolismo , Pruebas de Coagulación Sanguínea , Femenino , Humanos , Masculino , Persona de Mediana Edad , Cuidados Preoperatorios , Estudios Prospectivos , Factores de Tiempo
5.
Nanomaterials (Basel) ; 14(6)2024 Mar 18.
Artículo en Inglés | MEDLINE | ID: mdl-38535683

RESUMEN

The main objective of this study was to determine the variation in the properties of cadmium telluride (CdTe) thin films deposited on a p-type Si substrate by the radio frequency magnetron sputtering technique at four different working powers (70 W, 80 W, 90 W, and 100 W). The substrate temperature, working pressure, and deposition time during the deposition process were kept constant at 220 °C, 0.46 Pa, and 30 min, respectively. To study the structural, morphological, and optical properties of the CdTe films grown under the mentioned experimental conditions, X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and optical spectroscopy were used. For a better analysis of the films' structural and optical properties, a group of films were deposited onto optical glass substrates under similar deposition conditions. The electrical characterisation of Ag/CdTe/Al "sandwich" structures was also performed using current-voltage characteristics in the dark at different temperatures. The electrical measurements allowed the identification of charge transport mechanisms through the structure. New relevant information released by the present study points towards 90 W RF power as the optimum for obtaining a high crystallinity of ~1 µm nanostructured thin films deposited onto p-Si and optical glass substrates with optical and electrical properties that are suitable for use as absorber layers. The obtained high-quality CdTe nanostructured thin films are perfectly suitable for use as absorbers in CdTe thin-film photovoltaic cells.

6.
Diagnostics (Basel) ; 14(16)2024 Aug 21.
Artículo en Inglés | MEDLINE | ID: mdl-39202312

RESUMEN

BACKGROUND: Pulmonary hypertension (PH) is a global health issue that has profound medical and research implications. METHODS: This retrospective study examined changes in renal and liver function, as well as lipid metabolism, over a 12-month period in 49 adult patients with pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH). All cases were admitted, managed, and followed up with in the PH Center, County Emergency Clinical Hospital of Targu Mures, Romania. RESULTS: Kidney dysfunction was observed in 12.24% of cases at baseline, decreasing to 8.16% at 12 months, and CTEPH patients were more affected. In particular, CTEPH patients exhibited an improvement in renal function, confirmed by an increase in their glomerular filtration rates. Hepatic impairment was present in 57.14% of subjects at baseline, declining to 42.86% at 12 months, with significant improvements noted in the PAH group. Lipid metabolic dysregulations were experienced by 22.45% of all patients at baseline, decreasing to 16.33% at 6 months, with a slow elevation to 24.49% at 12 months, but with no statistically significant differences. Pharmacological regimens were adjusted in accordance with the PH groups, a patient's functional and clinical response, and laboratory tests. CONCLUSIONS: Our results demonstrate the multi-organ damage in PH and the importance of individualized treatment approaches.

7.
J Pers Med ; 14(1)2024 Jan 16.
Artículo en Inglés | MEDLINE | ID: mdl-38248798

RESUMEN

Long COVID is a recently described entity that is responsible for significant morbidity and that has consequences ranging from mild to life-threatening. The underlying mechanisms are not completely understood, and treatment options are currently limited, as existing data focus more on risk factors and predictors. Smoking has been reported as a risk factor for poor outcomes of acute SARS-CoV-2 infection and seems to also play a role in mediating post-COVID-19 symptoms. We aimed to review relevant work addressing the interaction between smoking and long COVID in order to characterize smoking's role as a risk factor and possibly identify new research directions. Methods: The PubMed/MEDLINE database was searched using the keywords 'smoking', 'long COVID', and 'post-acute COVID' to identify relevant English-language articles published up to October 2023. Results and conclusions: From the 374 initial hits, a total of 36 papers were deemed relevant to the aim of the review. There was significant variability concerning the ways in which tobacco usage was quantified and reported; still, there is compelling evidence linking smoking to an increased risk of developing manifestations of post-acute-COVID disease. Some clinical conditions, such as dyspnea, cardiovascular symptoms, and cognitive or mental-health impairment, seem to be relatively strongly associated with smoking, while the connection between smoking and upper-airway involvement seems less certain. The available data support recommending smoking cessation as a clinical tool for the prevention of long COVID.

8.
Diagnostics (Basel) ; 13(2)2023 Jan 04.
Artículo en Inglés | MEDLINE | ID: mdl-36672985

RESUMEN

Metastatic lesions of the spine occur in up to 40% of cancer patients and are a frequent source of pain and neurologic deficit due to cord compression. Palliative radiotherapy is the main first-intent local treatment in the form of single-fraction radiotherapy or fractionated courses. Reirradiation is a viable option for inoperable patients where spinal decompression is needed but with an increased risk of radiation-induced myelopathy (RM) and subsequent neurologic damage. This review summarizes reported data on local treatment options after initial irradiation in patients with relapsed spine metastasis and key dosimetric correlations between the risk of spinal cord injury and reirradiation technique, total dose, and time between treatments. The Linear Quadratic (LQ) model was used to convert all the published doses into biologically effective doses and normalize them to EQD2. For 3D radiotherapy, authors used cumulative doses from 55.2 Gy2/2 to 65.5 Gy2/2 EQD2 with no cases of RM mentioned. We found little evidence of RM after SBRT in the papers that met our criteria of inclusion, usually at the median reported dose to critical neural tissue around 93.5 Gy2/2. There is a lack of consistency in reporting the spinal cord dose, which leads to difficulty in pooling data.

9.
Rom J Morphol Embryol ; 64(4): 517-525, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-38184832

RESUMEN

Pericardial cysts (PCs) or pleuropericardial cysts are rare congenital mediastinal lesions with an approximate incidence of one in 100 000 persons. Usually, they are asymptomatic, being incidentally discovered during a routine chest imaging examination or an autopsy exam. The study involved a retrospective evaluation of clinicopathological findings in a 6-year series of PCs, treated in the Clinic of Pulmonary Diseases, Iasi, Romania. A group of five cases of PCs, four females and one male, were evaluated. All patients displayed different symptoms, such as dyspnea, chest pain, chronic cough, fatigue, palpitation, and epigastric pain. The cystic lesions were located in the right and left cardiophrenic angle, in four cases, and in the central mediastinum in a single case. The lesions had a fluid content and a maximum diameter that ranged between 35 and 95 mm. The microscopic examination of the surgical resection tissues revealed a thin connective tissue wall without any associated smooth muscle cells. The loose connective tissue band was lined by a layer of mesothelial cells with no cellular atypia, which displayed discrete papillary projections, in one case. Although PCs are rare incidental findings, they should be considered in differential diagnoses of mediastinal cysts, especially as they are associated with non-specific symptoms. Furthermore, considering the possibility of development of severe complications, PCs should be thoroughly explored for suitable patients' management.


Asunto(s)
Quiste Mediastínico , Femenino , Humanos , Masculino , Quiste Mediastínico/diagnóstico , Estudios Retrospectivos , Diagnóstico Diferencial , Autopsia , Tos Crónica
10.
J Pers Med ; 13(11)2023 Nov 10.
Artículo en Inglés | MEDLINE | ID: mdl-38003904

RESUMEN

Interstitial lung diseases are respiratory diseases, which affect the normal lung parenchyma and can lead to significant pulmonary fibrosis, chronic respiratory failure, pulmonary hypertension, and ultimately death. Reuniting more than 200 entities, interstitial lung diseases pose a significant challenge to the clinician, as they represent rare diseases with vague and insidious respiratory symptoms. As such, there are many diagnostic errors that can appear along the journey of the patient with ILD, which leads to significant delays with implications for the prognosis and the quality of life of the patient.

11.
J Pers Med ; 13(6)2023 May 26.
Artículo en Inglés | MEDLINE | ID: mdl-37373889

RESUMEN

INTRODUCTION: We aimed to characterize the clinical features of moderate forms of COVID-19 requiring hospitalization and potentially identify predictors for unfavorable outcomes. METHODS: Pooled anonymized clinical data from 452 COVID-19 patients hospitalized in two regional Romanian respiratory disease centers during the Alpha and Delta variant outbreaks were included in the analysis. RESULTS: Cough and shortness of breath were the most common clinical features; older patients exhibited more fatigue and dyspnea and fewer upper airway-related symptoms such as smell loss or sore throat. The presence of confusion, shortness of breath and age over 60 years were significantly associated with worse outcomes (odds ratios 5.73, 2.08 and 3.29, respectively). CONCLUSION: The clinical picture on admission may have a prognostic role for moderate forms of COVID-19. Clear clinical definitions and developing adequate informational infrastructure allowing complex data sharing and analysis might be useful for fast research response should a similar outbreak occur in the future.

12.
Nanomaterials (Basel) ; 12(22)2022 Nov 15.
Artículo en Inglés | MEDLINE | ID: mdl-36432300

RESUMEN

This article presents a theoretical study of the electronic, impurity-related, and nonlinear optical properties of CdS/ZnS quantum dots subjected to electric and magnetic fields. The magnetic field is applied along the z-axis, with the donor impurity always located in the center of the quantum dot. In the case of the electric field, two situations have been considered: applied along the z-axis and applied in the radial direction (central electric field). In both cases, the azimuthal symmetry (around the z-axis) is preserved. In the absence of a magnetic field and considering a central electric field, the system preserves its spherical symmetry both in the presence and in the absence of the donor impurity. The study is carried out in the effective mass approximation and it uses the finite element method to find the eigenfunctions and their corresponding energies, both in the presence and in the absence of the impurity. This work investigates the optical absorption coefficient and the relative change of the refractive index, considering only intraband transitions between l = 0 states (states with azimuthal symmetry concerning the z-axis). Calculations are for z-polarized incident radiation. The study shows that the combined effects of a central electric field and a z-directed magnetic field can give rise to a typical core/shell-like quantum confinement with oscillations of the electron ground state. Additionally, it is shown that the presence of the donor impurity suppresses such oscillations and it is responsible for blue shifts in the optical properties and magnifications of the corresponding resonances.

13.
Med Pharm Rep ; 95(4): 475-485, 2022 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-36506604

RESUMEN

Introduction: Pulmonary rehabilitation is known as an effective therapy for patients with chronic obstructive pulmonary disease (COPD). This article is a brief introduction into the history of medical and pulmonary rehabilitation, presenting the evolution of applied therapies and methods from ancient to present times. It also highlights the role of physical effort in the prevention and treatment of lung diseases, with special consideration to COPD. Methods: For this literature review, the international databases Medline and Scopus were used to identify relevant articles, between January 1981 to December 2021; eighty articles were considered: thirty-six reviews, eight original research and six general articles which met the criteria for inclusion. A total of thirty references were excluded because they were not relevant. Results: Available published data suggest a rich history of rehabilitation reaching for thousands of years even though it was developed as a medical branch only in the 20th century. Pulmonary rehabilitation is currently an important component of the management of COPD patients, with a positive impact on symptoms, frequency of exacerbations, severity and mortality rates. Conclusions: Even though this type of intervention is known to be beneficial for this type of patients more studies need to be conducted in this field.

14.
Rom J Morphol Embryol ; 63(4): 607-613, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-36808195

RESUMEN

Pulmonary hamartomas (PHs) are the most common benign lung tumors. Usually, they are asymptomatic and incidentally discovered during assessment for other diseases or during the autopsy exam. In this context, we have performed a retrospective analysis of surgical resections in a 5-year series of patients diagnosed with PHs in the Clinic of Pulmonary Diseases, Iasi, Romania, aiming to evaluate their clinicopathological features. A total of 27 patients with PH (40.74% males and 59.26% females) were evaluated. 33.33% of patients were asymptomatic, while the others exhibited variable symptoms, such as chronic cough, dyspnea, chest pain or weight loss. In most cases, PHs presented as solitary nodules, predominantly disposed in the right upper lobe (40.74% of cases), followed by the right lower lobe (33.34%), and left lower lobe (18.51%). The microscopic examination revealed a mixture of mature mesenchymal tissue, such as hyaline cartilage, adipose tissue, fibromyxoid tissue, and smooth muscle bundles, in variable proportions, associated with clefts of entrapped benign epithelium. A dominant adipose tissue component was observed in one case. PH was associated with a history of extrapulmonary cancer diagnosis, in one patient. Although considered benign lung tumors, PHs diagnosis and therapy may be challenging. Having in mind the possibility of recurrence or their occurrence as a part of specific syndromes, PHs should be thoroughly investigated for an appropriate patients' management. Their complex significance and the correlation with other types of lesions, including malignancies, may be further studied, by more extensive studies of surgical and necroptic cases.


Asunto(s)
Hamartoma , Neoplasias Pulmonares , Masculino , Femenino , Humanos , Estudios Retrospectivos , Neoplasias Pulmonares/patología , Pulmón/patología , Hamartoma/diagnóstico , Hamartoma/patología , Hamartoma/cirugía , Rumanía
15.
J Pers Med ; 12(5)2022 Apr 26.
Artículo en Inglés | MEDLINE | ID: mdl-35629110

RESUMEN

Poor oral hygiene leads to the accumulation of dental plaque, thus contributing to the initiation of periodontal disease (PD). Local infections can lead to systemic inflammatory responses, which are essential mediators for the evolution of systemic conditions or cancer tumorigenesis. Often, patients hospitalized with life-threatening and incapacitating disorders such as gastric cancer (GC) might lose interest in keeping their mouth healthy. This study evaluates oral hygiene, periodontal status, and the need for oral care and medical personnel to assist in achieving it in patients hospitalized with GC. This study was carried out on 25 patients with a diagnosis of GC, divided into two groups (GP-14 patients from the Gastroenterology Department, and SP-11 patients from the 1st Department of Surgery). Patients were examined on the day of admission (T0), the day of the medical procedure of endoscopy or surgery (T1), and the day of discharge (T2), recording the number of absent teeth, dental plaque (PI), bleeding on probing (BOP), probing depths (PPD), frequency of toothbrushing, and if the oral hygiene had been self-performed or assisted. Data were subjected to statistical analysis. Our results showed that, in both the GP and the SP group, there were strong and statistically significant correlations between PI and BOP measured on the last day of hospitalization and the period of hospitalization after the medical procedure. Longer hospital stays and the presence of surgery were risk factors for changing toothbrushing frequency. Results also highlight the need for a dentist to diagnose and eventually treat periodontal disease before and after hospitalization, and for a trained nurse who should help take care of the patient's oral hygiene during hospitalization.

16.
J Nanosci Nanotechnol ; 11(10): 9095-101, 2011 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-22400308

RESUMEN

Wastewaters resulting from textile industry sector have a different chemistry compared with most of the other wastewaters. The different dyes in excess are usually very stable and even small quantities can have a major impact to the effluent. In order to treat these wastewaters, photodegradation is a largely investigated process that can be up-scaled. Photocatalysts based on wide band gap semiconductors can be used in heterogeneous photocatalysis and mostly reported are TiO2 and WO3. Under UV irradiation they form electron-hole pairs that produce active species that can oxidize the dye molecules. The electron-hole recombination represents the main cause for low efficiencies and is limited by the use of oxidant systems like H2O2. Doctor blade technique, a reproducible, up-scalable and low cost technique was used to obtain thin films. The reference dye, used in this experiment is methylorange in solution of 0.0125 mM, corresponding to average polluted water. In order to reduce the recombination in the catalysts, H2O2 is used. Another important aspect of the dye photocatalysis process, investigated in the paper is the adsorption of the dye molecule on the photocatalyst surface, strongly depending on pH which affects the dye's structure and the surface charge. Experiments are conducted at fixed pH values: 3, and respectively 7 covering values below and over the ZPC of the photocatalysts. The results show that TiO2/WO3 films have higher efficiency then the TiO2 and WO3 films, mainly due to the surface morphology of the films. By adding H2O2, higher efficiencies are obtained, confirming that the electron-hole pair recombination is reduced. From the point of view of pH, higher efficiencies are obtained in acidic solutions and the results are comparatively discussed considering the dye's ionic/neutral structure and the photocatalyst surface charge. The efficiency was calculated using UV-VIS spectrophotometer measurements of the solution and the thin films were characterized by AFM and XRD.

17.
Nanomaterials (Basel) ; 11(5)2021 May 05.
Artículo en Inglés | MEDLINE | ID: mdl-34063019

RESUMEN

Quantum wires continue to be a subject of novel applications in the fields of electronics and optoelectronics. In this work, we revisit the problem of determining the electron states in semiconductor quantum wires in a self-consistent way. For that purpose, we numerically solve the 2D system of coupled Schrödinger and Poisson equations within the envelope function and effective mass approximations. The calculation method uses the finite-element approach. Circle, square, triangle and pentagon geometries are considered for the wire cross-sectional shape. The features of self-consistent band profiles and confined electron state spectra are discussed, in the latter case, as functions of the transverse wire size and temperature. Particular attention is paid to elucidate the origin of Friedel-like oscillations in the density of carriers at low temperatures.

18.
Nanomaterials (Basel) ; 11(11)2021 Oct 25.
Artículo en Inglés | MEDLINE | ID: mdl-34835604

RESUMEN

Zinc selenide (ZnSe) thin films were deposited by RF magnetron sputtering in specific conditions, onto optical glass substrates, at different RF plasma power. The prepared ZnSe layers were afterwards subjected to a series of structural, morphological, optical and electrical characterizations. The obtained results pointed out the optimal sputtering conditions to obtain ZnSe films of excellent quality, especially in terms of better optical properties, lower superficial roughness, reduced micro-strain and a band gap value closer to the one reported for the ZnSe bulk semiconducting material. Electrical characterization were afterwards carried out by measuring the current-voltage (I-V) characteristics at room temperature, of prepared "sandwich"-like Au/ZnSe/Au structures. The analysis of I-V characteristics have shown that at low injection levels there is an Ohmic conduction, followed at high injection levels, after a well-defined transition voltage, by a Space Charge Limited Current (SCLC) in the presence of an exponential trap distribution in the band gap of the ZnSe thin films. The results obtained from all the characterization techniques presented, demonstrated thus the potential of ZnSe thin films sputtered under optimized RF plasma conditions, to be used as alternative environmentally-friendly Cd-free window layers within photovoltaic cells manufacturing.

19.
Nanomaterials (Basel) ; 11(11)2021 Oct 25.
Artículo en Inglés | MEDLINE | ID: mdl-34835595

RESUMEN

Using the effective mass approximation in a parabolic two-band model, we studied the effects of the geometrical parameters, on the electron and hole states, in two truncated conical quantum dots: (i) GaAs-(Ga,Al)As in the presence of a shallow donor impurity and under an applied magnetic field and (ii) CdSe-CdTe core-shell type-II quantum dot. For the first system, the impurity position and the applied magnetic field direction were chosen to preserve the system's azimuthal symmetry. The finite element method obtains the solution of the Schrödinger equations for electron or hole with or without impurity with an adaptive discretization of a triangular mesh. The interaction of the electron and hole states is calculated in a first-order perturbative approximation. This study shows that the magnetic field and donor impurities are relevant factors in the optoelectronic properties of conical quantum dots. Additionally, for the CdSe-CdTe quantum dot, where, again, the axial symmetry is preserved, a switch between direct and indirect exciton is possible to be controlled through geometry.

20.
J Med Life ; 3(4): 407-11, 2010.
Artículo en Inglés | MEDLINE | ID: mdl-21254739

RESUMEN

AIM: The aim of our study was to assess macro- and microscopically the knee cartilaginous lesions outcome treated by mosaicplasty. MATERIAL AND METHOD: Our study included 32 patients who underwent mosaicplasty for nondegenerative cartilaginous lesions of the knee and a second look arthroscopy. In 21 patients, minibiopsies from the repaired lesion were performed under arthroscopic control (from the cartilaginous region of the transplanted osteocartilaginous grafts and from the spaces between grafts). All repaired lesions were carefully examined during arthroscopy and all harvested minifragments were studied by optical microscopy (staining method - hematoxylin eosin). RESULTS: Macroscopically, the articular surface of the repaired cartilaginous lesions was smooth and congruent to the adjacent surfaces. The aspect and resistance to compression of grafted area was similar to those of the normal surrounding cartilage. The transferred cartilage maintained its height, being at the level of the neighboring cartilage. One year postoperatively, the limits of the cartilaginous autografts were still visible. Two years postoperatively, these limits were no longer visible. Microscopically, the region of the former lesion was constituted mainly by viable hyaline cartilage. Fibrous cartilaginous tissue was visualized in the spaces between the grafts. CONCLUSIONS: The second look arthroscopy showed that after mosaicplasty the repaired articular surface was smooth, leveled, homogenous and congruent to adjacent cartilage. The spaces between grafts are progressively covered by fibrous cartilaginous tissue with a more textured and uneven surface. Mosaicplasty is a biological surgical technique, which restores the normal osteocartilaginous architecture of the most part of the grafted area. The transplanted osteocartilaginous cylindrical grafts maintain its viability and mechanical properties.


Asunto(s)
Artroscopía/métodos , Fracturas Óseas/cirugía , Cartílago Hialino/trasplante , Artropatías/cirugía , Articulación de la Rodilla/cirugía , Adolescente , Adulto , Biopsia , Cartílago Articular/patología , Cartílago Articular/cirugía , Femenino , Fracturas Óseas/patología , Humanos , Artropatías/patología , Articulación de la Rodilla/patología , Masculino , Persona de Mediana Edad , Rótula/patología , Rótula/cirugía , Estudios Prospectivos , Trasplante Autólogo/métodos
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