Biaxial strain tuned upconversion photoluminescence of monolayer WS2

Abstract Monolayer tungsten disulfide (1L-WS2) is a direct bandgap atomic-layered semiconductor material with strain tunable optical and optoelectronic properties among the monolayer transition metal dichalcogenides (1L-TMDs). Here, we demonstrate biaxial strain tuned upconversion photoluminescence (UPL) from exfoliated 1L-WS2 flakes transferred on a flexible polycarbonate cruciform substrate. When the biaxial strain applied to 1L-WS2 increases from 0 to 0.51%, it is observed that the UPL peak position is redshifted by up to 60 nm/% strain, while the UPL intensity exhibits exponential growth with the upconversion energy difference varying from − 303 to − 120 meV. The measured power dependence of UPL from 1L-WS2 under biaxial strain reveals the one photon involved multiphonon-mediated upconversion mechanism. The demonstrated results provide new opportunities in advancing TMD-based optical upconversion devices for future flexible photonics and optoelectronics

Transversus Abdominis Plane Block with or without Intravenous Diclofenac Sodium as a Component of Multimodal Postoperative Analgesia Following Laparoscopic Cholecystectomy: A Randomised Clinical Study

Introduction: Multimodal analgesia is the recommended approach for treating post-operative pain after laparoscopic cholecystectomy. The Transversus Abdominis Plane (TAP) block is a recently introduced technique showing promising results. To control visceral and somatic pain adequately and to avoid use of opioids intra-operative diclofenac sodium, combined with TAP block as part of a multimodal approach, may be beneficial. Aim: To evaluate the efficacy of TAP block with or without intraoperative diclofenac sodium aqueous injection for controlling post-operative pain following laparoscopic cholecystectomy. Materials and Methods: A randomised, double-blinded study was conducted from February 2022 to October 2022 at Nil Ratan Sircar Medical College, Kolkata, West Bengal, India. Forty American Society of Anaesthesiology (ASA) physical status-I and II patients aged 20-50 years scheduled for elective laparoscopic cholecystectomy were divided into two groups of 20 patients each. Group A patients received bilateral Ultrasonography (USG) guided TAP block using 20 mL of 0.125% Bupivacaine on each side of the abdomen at the end of surgery. Group B patients received intravenous injection of diclofenac sodium aqueous 75 mg intravenous, intraoperatively, along with bilateral USG guided TAP block using 0.125% Bupivacaine. The primary outcome was the duration of post-operative analgesia (measured by the first request for rescue analgesia after the end of the operation at a VAS score of 4). Secondary outcomes included the total post-operative analgesic requirement (diclofenac sodium), pain score (VAS) over 24 hours in the post-operative period, and the incidence of complications such as nausea, vomiting, hypotension, and bradycardia. Patient Satisfaction Score (PSS) was recorded for each patient before discharge. Statistical analysis was performed using Statistical Package for Social Sciences(SPSS) version 24.0 software. Continuous variables were expressed as mean and standard deviation, and categorical variables were expressed as percentages. Independent t-tests and chi-square tests were used for between-group comparisons, with a p-value ≤0.05 considered statistically significant. Results: Amongst total 40 patients included, divided into group A(mean age: 32.95±8.74 years, 6 males and 14 females) and group B(31.90±9.16 years, 5 males and 15 females) with 20 patients each, the demographic characteristics such as age, gender, height, and weight were similar in both groups. The duration of post-operative analgesia was longer in Group B (16.32±1.29 hours) than in Group A (7.85±1.04 hours). The total post-operative analgesic requirement was lower in Group B (32.95±20.9 mg) compared to Group A (58.33±17.14 mg). Visual Analogue Scale (VAS) scores were lower in Group B than in Group A. PSS was significantly higher in Group B patients (8.14±1.06) than in Group A patients (6.16±1.38). Conclusion: TAP block, along with intra-operative intravenous diclofenac sodium aqueous, as part of a multimodal regimen, provides superior post-operative analgesia compared to TAP block alone. It is also associated with improved patient satisfaction

Silver nanoflowers for single-particle SERS with 10 pM sensitivity

Surface-enhanced Raman scattering (SERS) has received considerable attention as a noninvasive optical sensing technique with ultrahigh sensitivity. While numerous types of metallic particles have been actively investigated as SERS substrates, the development of new SERS agents with high sensitivity and their reliable characterization are still required. Here we report the preparation and characterization of flower-shaped silver (Ag) nanoparticles that exhibit high-sensitivity single-particle SERS performance. Ag nanoflowers (NFs) with bud sizes in the range 220-620 nm were synthesized by the wet synthesis method. The densely packed nanoscale petals with thicknesses in the range 9-22 nm exhibit a large number of hot spots that significantly enhance their plasmonic activity. A single Ag NF particle (530-620 nm) can detect as little as 10(-11) M 4-mercaptobenzoic acid, and thus provides a sensitivity three orders of SERS magnitude greater than that of a spherical Ag nanoparticle. The analytical enhancement factors for single Ag NF particles were found to be as high as 8.0 x 10(9), providing unprecedented high SERS detectivity at the single particle level. Here we present an unambiguous and systematic assessment of the SERS performances of the Ag NFs and demonstrate that they provide highly sensitive sensing platforms by single SERS particle. © 2017 IOP Publishing Ltd Printed in the UK1341sciescopu

Not Available

Not AvailableNot AvailableNot Availabl

Near-field exciton imaging of chemically treated MoS2 monolayers

The exciton-dominated light emission of two-dimensional (2D) semiconductors is determined largely by the doping state and the formation of defects. Extensive studies have shown that chemical treatment critically modifies the doping state and defect state of chemical vapor deposition (CVD)-grown or exfoliated monolayer MoS2 (1L-MoS2), suggesting a promising possibility for engineering the optoelectronic properties of 2D semiconductors. However, chemical treatment inevitably modifies both the doping state and defect states, and their independent roles in the exciton emission of 1L-MoS2 have been difficult to study, significantly limiting the practical and reliable uses of chemical treatment to improve the optical properties of 1L-TMDs. Herein, we used near-field imaging and spectroscopy to investigate the effects of chemical treatment on the exciton emission of 1L-MoS2. CVD-grown 1L-MoS2 was treated with bis(trifluoromethane)-sulfonimide (TFSI) or 7,7,8,8-tetracyanoquinodimethane (TCNQ), and nanoscale maps of neutral exciton and trion emission before and after chemical treatment were obtained with 80 nm spatial resolution. A comparison of the local spatial and spectral compositions of neutral excitons and trions suggested that the p-doping effect of TFSI was especially strong around local defects, whereas electron depletion by TCNQ was spatially uniform. The specific reaction of TFSI to defect locations observed in our study provides the clue for the reason that TFSI is notably effective at improving the light emission of 1L-MoS2 © The Royal Society of Chemistry 20181

Efficacy of Erector Spinae Plane Block in Modified Radical Mastectomy for Postoperative Analgesia: A Randomised Controlled Study

Introduction: The Erector Spinae Plane Block (ESPB) is a recently introduced Ultrasound (US)-guided interfascial plane block commonly used for treating thoracic neuropathic pain. Although ESPB has been used for pain control after Modified Radical Mastectomy (MRM), which is a frequently performed operation nowadays, its efficacy compared to other methods of pain control is yet to be established. Aim: To evaluate the effectiveness of ESPB in controlling acute postoperative pain after MRM surgery. Materials and Methods: A total of 64 adult females aged between 18-60 years, with American Society of Anaesthesiologists (ASA) physical status I and II, scheduled to undergo elective MRM, were enrolled in the present randomised, double-blinded, controlled study conducted at Department of Anaesthesiology and Critical Care, Nil Ratan Sircar Medical College, Kolkata, West Bengal, India over a period of nine months (from March 2021 to November 2021). They were randomly assigned to two groups, with 32 patients in each group. Group A (n=32) received general anaesthesia only, while Group B (n=32) received US-guided ESPB in addition to general anaesthesia. Postoperative Visual Analogue Scale (VAS) scores, total intra and postoperative analgesic requirements for the first 24 hours, and duration of postoperative analgesia were recorded for each patient. Statistical analysis was performed using Statistical Package for Social Sciences (SPSS) version 24.0 software. Mean and Standard Deviation (SD) were used to express data for numerical variables, while count and percentages were used for categorical variables. Results: Demographic characteristics (age, weight), ASA status, and mean duration of surgery were similar between the groups. The duration of postoperative analgesia was significantly (p<0.05) prolonged in Group B patients (584.1±89.1 minutes) compared to Group A patients (78.0±53.1 minutes). Intra and postoperative analgesic requirements were significantly lower in Group B (fentanyl 87.0±16.8 mcg, tramadol 68.3±35.9 mg) compared to Group A patients (fentanyl 94.5±26.7 mcg, tramadol 158.3±32.3 mg). The postoperative VAS score was more favourable in Group B than in Group A (1.1±0.4 vs. 4.1±0.8 at rest). Conclusion: The US-guided ESPB is a simple and easy procedure that provides prolonged duration of postoperative analgesia with reduced overall analgesic requirement in the postoperative period after MRM surgery. Therefore, it can be concluded that ESPB is an effective method for controlling acute postoperative pain after MRM surgery

The fabrication and characterization of ZnO/NiCO2O4 nanowires synthesized by a hydrothermal method

The main functional part of the supercapacitors and nanogenerators made up of various types of nanostructured materials. The contemporary devices have been manufactured employing different kinds of nanomaterials based on nanoflake and nanowire structures. These hierarchical materials show high efficiency on engineering electrodes for supercapacitors as well as piezoelectric for nanogenerators. Here, we have successfully synthesized NiCo2O4 nanowires on ZnO nanoflakes by applying two-step hydrothermal method which is absent similar analogous to date. The microscopic analysis has shown the uniform growth of NiCo2O4 nanowires on ZnO nanoflakes. This fabricated material might be used in above mentioned purposes in the future