Two-dimensional tellurium-based diodes for RF applications

The research of two-dimensional (2D) Tellurium (Te) or tellurene is thriving to address current challenges in emerging thin-film electronic and optoelectronic devices. However, the study of 2D-Te-based devices for high-frequency applications is still lacking in the literature. This work presents a comprehensive study of two types of radio frequency (RF) diodes based on 2D-Te flakes and exploits their distinct properties in two RF applications. First, a metal-insulator-semiconductor (MIS) structure is employed as a nonlinear device in a passive RF mixer, where the achieved conversion loss at 2.5 GHz and 5 GHz is as low as 24 dB and 29 dB, respectively. Then, a metal-semiconductor (MS) diode is tested as a zero-bias millimeter-wave power detector and reaches an outstanding linear-in-dB dynamic range over 40 dB, while having voltage responsivities as high as 257 V ⋅ W−1 at 1 GHz (up to 1 V detected output voltage) and 47 V ⋅ W−1 at 2.5 GHz (up to 0.26 V detected output voltage). These results show superior performance compared to other 2D material-based devices in a much more mature technological phase. Thus, the authors believe that this work demonstrates the potential of 2D-Te as a promising material for devices in emerging high-frequency electronics.MCIN/AEI/10.13039/501100011033European Union NextGenerationEU/PRTRGerman Research Foundation (DFG) under the projects GLECS2 (No. 653408)MOSTFLEX (653414),The Natural Sciences and Engineering Research Council (NSERC) (RGPIN-2017-05810 and ALLRP 577611-22)The European Commission under the Horizon 2020 projects Graphene Flagship (No. 785219 and 881603)PAIDI 2020 and European Social Fund Operational Programme 2014-2020 no. 20804Ministerio de UniversidadesGrant no. CAS21/ 00483Canada Foundation for Innovation (CFI)British Columbia Knowledge Development Fund (BCKDF)Western Economic Diversification Canada (WD)Simon Fraser Universit

Accelerated versus Standard Corneal Cross-linking for Progressive Keratoconus in Syria

Purpose: To compare the outcomes of accelerated versus standard corneal cross-linking for the treatment of progressive keratoconus. Methods: In this retrospective comparative study, 63 eyes of 40 patients with progressive keratoconus were divided into two groups; 27 eyes in group one were treated with an accelerated protocol (10 mW/cm2, 9 min) and 36 eyes in group two were treated with the standard method (3 mW/cm2, 30 min). Visual acuity, refraction, corneal topography, corneal tomography, and anterior and posterior corneal higher-order aberrations (HOAs) were assessed preoperatively and 18–30 months postoperatively. Results: The LogMAR uncorrected and corrected distance visual acuity values were improved in both groups postoperatively. However, the improvement was significantly higher in group one (P < 0.05, all). The flattening in the anterior keratometry readings, flat K, steep K, and average K were significantly higher in group two (P < 0.001, all). The maximum anterior keratometry (AKf) values significantly decreased in both groups, whereas the maximum posterior keratometry (AKb) values increased. The reduction in the minimum corneal thickness (ThKmin) was significantly greater (36.49um) in group two, compared to 10.85um in group one. There was a significant increase in the posterior average keratometry, and a significant decrease in the posterior astigmatism, along 3 mm meridian in S-CXL (P = 0.03, P = 0.008, respectively), while the corresponding values showed no statistical significance in group one (P > 0.05). The anterior corneal trefoil was significantly reduced in group one (P = 0.002), whereas anterior total HOAs and coma were significantly improved in group two (P < 0.0014, all). The posterior corneal spherical aberration decreased significantly in group one (P = 0.02), while group two revealed significant reduction in the posterior trefoil values (P = 0.011). The change in the anterior maximum keratometry was significantly and positively correlated to the preoperative maximum keratometry in group two (P = 0.53, P = 0.003). Conclusion: An accelerated cross-linking protocol using 10 mW/cm2 for 9 min showed more visual improvement and less pachymetric reduction when compared to the standard protocol, however, anterior corneal flattening, posterior corneal steepening, and the change in the posterior astigmatism were significantly higher in the standard protocol; while corneal HOAs were improved in both protocols

Impact of opioid-free analgesia on pain severity and patient satisfaction after discharge from surgery: multispecialty, prospective cohort study in 25 countries

Background: Balancing opioid stewardship and the need for adequate analgesia following discharge after surgery is challenging. This study aimed to compare the outcomes for patients discharged with opioid versus opioid-free analgesia after common surgical procedures.Methods: This international, multicentre, prospective cohort study collected data from patients undergoing common acute and elective general surgical, urological, gynaecological, and orthopaedic procedures. The primary outcomes were patient-reported time in severe pain measured on a numerical analogue scale from 0 to 100% and patient-reported satisfaction with pain relief during the first week following discharge. Data were collected by in-hospital chart review and patient telephone interview 1 week after discharge.Results: The study recruited 4273 patients from 144 centres in 25 countries; 1311 patients (30.7%) were prescribed opioid analgesia at discharge. Patients reported being in severe pain for 10 (i.q.r. 1-30)% of the first week after discharge and rated satisfaction with analgesia as 90 (i.q.r. 80-100) of 100. After adjustment for confounders, opioid analgesia on discharge was independently associated with increased pain severity (risk ratio 1.52, 95% c.i. 1.31 to 1.76; P < 0.001) and re-presentation to healthcare providers owing to side-effects of medication (OR 2.38, 95% c.i. 1.36 to 4.17; P = 0.004), but not with satisfaction with analgesia (beta coefficient 0.92, 95% c.i. -1.52 to 3.36; P = 0.468) compared with opioid-free analgesia. Although opioid prescribing varied greatly between high-income and low- and middle-income countries, patient-reported outcomes did not.Conclusion: Opioid analgesia prescription on surgical discharge is associated with a higher risk of re-presentation owing to side-effects of medication and increased patient-reported pain, but not with changes in patient-reported satisfaction. Opioid-free discharge analgesia should be adopted routinely

Two-dimensional tellurium-based diodes for RF applications

Abstract The research of two-dimensional (2D) Tellurium (Te) or tellurene is thriving to address current challenges in emerging thin-film electronic and optoelectronic devices. However, the study of 2D-Te-based devices for high-frequency applications is still lacking in the literature. This work presents a comprehensive study of two types of radio frequency (RF) diodes based on 2D-Te flakes and exploits their distinct properties in two RF applications. First, a metal-insulator-semiconductor (MIS) structure is employed as a nonlinear device in a passive RF mixer, where the achieved conversion loss at 2.5 GHz and 5 GHz is as low as 24 dB and 29 dB, respectively. Then, a metal-semiconductor (MS) diode is tested as a zero-bias millimeter-wave power detector and reaches an outstanding linear-in-dB dynamic range over 40 dB, while having voltage responsivities as high as 257 V ⋅ W−1 at 1 GHz (up to 1 V detected output voltage) and 47 V ⋅ W−1 at 2.5 GHz (up to 0.26 V detected output voltage). These results show superior performance compared to other 2D material-based devices in a much more mature technological phase. Thus, the authors believe that this work demonstrates the potential of 2D-Te as a promising material for devices in emerging high-frequency electronics

Continuous thoracic epidural versus continuous paravertebral analgesia in patients undergoing open renal surgery: Evaluation of pulmonary function; randomized double-blinded clinical trial

ABSTRACTBackground This study aimed to assess pulmonary functions after either continuous thoracic paravertebral block (cTPVB) or thoracic epidural block (cTEB) in open renal surgeries.Methodsː The double-blinded, randomized clinical trial included 40 patients scheduled for open renal surgeries at Urology Hospital-Assiut University, equally assigned into group E (n = 20) and group P (n = 20), both at the level of 7th-8th thoracic vertebra. Initially, 7.5–12 mL of bupivacaine 0.25% was started before the induction of general anesthesia, followed by bupivacaine 0.125% continuously at a rate of 5–15 ml/h. Forced vital capacity (FVC) measured every  6 hours postoperatively within the first 24 hours was the primary outcome. Secondary outcomes were peak expiratory flow rate (PEFR), forced expiratory volume in the first second (FEV1), diaphragmatic excursion (DE), postoperative analgesia, total opioid consumption, total local anesthetic dose, hemodynamics and complications.Resultsː FVC, FEV1 and DE were better preserved in cTPVB where the lowest postoperative readings as a fraction of preoperative control were 0.7 ± 0.11 vs 0.65 ± 0.11 L, 0.74 ± 0.11 vs 0.64 ± 0.10 L and 0.73 ± 0.1 vs 0.58 ± 0.1 cm, respectively. The lowest postoperative PEFR was reported in cTEB (p-value = 0.128). Analysis of numeric rating pain scale, total opioid consumption and time of first rescue analgesic request revealed a statistical nonsignificant difference. The total infused dose of local anesthetic was significantly higher in cTPVB group. Incidence of sympatholytic complications was higher in cTEB.Conclusion cTEB and cTPVB had convergent effect on respiratory function and diaphragmatic motility and equivalent analgesic efficacy after open renal surgeries. Although cTPVB was technically easier and less time-consuming than cTEB, higher dose of local anaesthetic was required in cTPVB

Multinuclear Magnetic Resonance Tracking of Hydro, Thermal, and Hydrothermal Decomposition of CH₃NH₃PbI₃

An NMR investigation of methylammonium lead iodide, the leading member of the hybrid organic–inorganic perovskite class of materials, and of its putative decomposition products as a result of exposure to heat and humidity, has been undertaken. We show that the ²⁰⁷Pb NMR spectra of the compound of interest and of the proposed lead-containing decomposition products, CH₃NH₃PbI₃·H₂O, (CH₃NH₃)₄PbI₆·2H₂O, and PbI₂, have distinctive chemical shifts spanning over 1400 ppm, making ²⁰⁷Pb NMR an ideal tool for investigating this material; further information may be gained from ¹³C and ¹H NMR spectra. As reported in many investigations of CH₃NH₃PbI₃ on films, the bulk material hydrates in the presence of high relative humidity (approximately 80%), yielding the monohydrated perovskite CH₃NH₃PbI₃·H₂O. This reaction is reversible by heating the sample to 341 K. We show that neither (CH₃NH₃)₄PbI₆·2H₂O nor PbI₂ is observed as a decomposition product and that, in contrast to many studies on CH₃NH₃PbI₃ films, the bulk material does not decompose or degrade beyond CH₃NH₃PbI₃·H₂O upon prolonged exposure to humidity at ambient temperature. However, exposing CH₃NH₃PbI₃ concurrently to heat and humidity, or directly exposing it to liquid water, leads to the irreversible formation of PbI₂. In spite of its absence among the decomposition products, the response of (CH₃NH₃)₄PbI₆·2H₂O to heat was also investigated. It is stable at temperatures below 336 K but then rapidly dehydrates, first to CH₃NH₃PbI₃·H₂O and then to CH₃NH₃PbI₃. The higher stability of the bulk material as reported here is a promising advance, since stability is a major concern in the development of commercial applications for this material