An aggregation-induced emission-based ratiometric fluorescent chemosensor for Hg(II) and its application in Caenorhabditis elegans imaging.

A chromone-based ratiometric fluorescent probe L2 was developed for the selective detection of Hg(II) in a semi-aqueous solution based on aggregation-induced emission (AIE) and chelation-enhanced fluorescence (CHEF) effect. The probe L2 fluoresced significantly at 498 nm in its aggregated state, and when chelated with Hg(II), the soluble state fluoresced 1-fold higher. In addition, Job's plot reveals that the probe forms a 1:1 stoichiometry complex with Hg(II) with an association constant of 9.10 × 103M-1 estimated by the BH plot. The probe L2 detects Hg(II) down to 22.47 nM without interference from other interfering ions. The FTIR, ESI mass, and DFT-based computational studies investigated the binding mechanism of probe L2 with Hg(II). Taking advantage of its AIE characteristics, the probe L2 was successfully applied for bio-capability analysis in Caenorhabditis elegans (a nematode worm) imaging of Hg(II) in a living model.

Thermal, dielectric, mechanical and structural behavior of 2-amino 4-methylpyridinium 4-nitrophenolate 4-nitrophenol bulk single crystal.

Applications in both science and industry have received increased attention as a result of bulk single crystals with particular orientations. However, due to the instability of organic crystals at high temperatures and stress, there is an interest in growing good-quality bulk single crystals with stable thermal and mechanical properties. Here, the 2-amino 4-methylpyridinium 4-nitrophenolate 4-nitrophenol (2A4MPPP) crystal was prepared employing a single-wall ampoule and the vertical Bridgman technique. Structure and functional groups were determined by XRD, NMR, and FTIR studies. More importantly, detailed thermal and kinetic properties such as activation energy, frequency factor, rate constant, and Avrami exponent are discussed. The mechanical stability and dielectric studies are also demonstrated for the title compound. According to the single crystal XRD investigation, 2A4MPPP is a member of the orthorhombic crystal system with the Pna21 space group. Through the TGA and DTA analyses, it was confirmed that the compound starts to melt at 98 °C and complete melting occurs at 103.3 °C. The dielectric experiments reveal the crystal's poor dielectric constant and high-frequency dielectric loss. Vickers microhardness investigations show that grown 2A4MPPP belongs to the soft materials group. As a result of these findings, the 2A4MPPP crystal should be well suited for usage in thermomechanical, microelectronic, optical communications, and nonlinear optical applications.

Synthesis, Structure, Morphology, Element composition, Electrochemical, and Optical studies of Zn0.98-XMn0.02CeX Quantum dots.

Quantum dots (QDs) are semiconductors whose size falls in a range between 1 and 10 nm; they are generally known as zero-dimension materials. It finds various applications in optical industries including light-emitting diodes, display technology, imaging, and labelling. ZnS is one of the excellent QDs in its class of II-VI semiconductors. In this paper, It is reported that the preparation of Mn-doped ZnS and Mn, Ce co-doped ZnS QDs using facile co-precipitation technique. XRD and HR-TEM results confirmed the cubic structure, particle size, and phase of the synthesized particles, and the crystallite is measured as âˆ¼ 2 nm. The surface morphology, elemental analysis, and FT-IR spectra revealed the purity of the samples and confirmed the presence of dopants as expected. Cyclic voltammetry studies expressed the electrochemical behaviour of the samples, which increased as a function of Ce3+ doping concentration. UV-visible absorbance and transmittance spectra disclosed the optical characteristics of the samples. A wide band gap (4.02 eV) was received for 2% Ce-doped Zn: MnS QDs. Week Blue and strong yellow emissions were received for 4% Ce-doped Zn:MnS QDs. Whereas, high intensity red-emission was received for 2% Ce-doped Zn:MnS QDs. The different colour emissions are discussed in terms of defects produced.

Sulfur deficiency mediated visible emission of ZnS QDs by magnesium dopant and their application in waste water treatment.

The photocatalyst with antimicrobial activity serves as a better candidate material for wastewater treatment, as wastewater contains microbes, hazardous dyes, and heavy metals. Hence, the present study extensively examines the photocatalytic and antibacterial activities against two waterborne bacterial strains, namely Salmonella typhi and Escherichia coli. Pure and Mg-doped ZnS (Mg:ZnS) quantum dots (QDs) were synthesized using a low-cost and simple co-precipitation method. The QDs' structural, surface morphology, chemical purity, and optical characteristics were analyzed through XRD, SEM, EDAX, TEM, UV-visible, and photoluminescence spectra. The incorporation of Mg dopants did not introduce significant alterations to the cubic blende structure of ZnS, nor did it induce substantial changes in the structural parameters. However, the QDs exhibited a slight sulfur deficiency, which was further increased by the presence of Mg dopant. The Mg dopant, due to its dominant compositional effect, reduced the band gap. Several optical emission bands were observed in the UV, violet, blue, and green regions, corresponding to NBE emission, sulfur-related defects, and Zn-related defects. Initially, Mg doping enhanced visible emission related to defects, while NBE emission was suppressed by the Mg dopant. However, increasing the concentration of the Mg dopant led to a slight increase in NBE emission. The Mg dopant enhanced the photocatalytic activity of the QDs, and a strong correlation was found between photocatalytic activity and NBE emission. The presence of the Mg dopant led to an increased rate of ROS-based decolorization by reducing the electron-hole recombination rate.

Understanding Auger recombination in perovskite solar cells.

Enhanced radiative efficiency, long carrier lifetimes, and high carrier mobilities are hallmarks of perovskite solar cells. Considering this, complete cells experience large nonradiative recombination losses that restrict their VOC considerably below the Shockley-Queisser limit. Auger recombination, which involves two free photo-induced carriers and a trapped charge carrier, is one potential mechanism. Herein, the effects of Auger capture coefficients in mixed-cation perovskites are analyzed employing SCAPS-1D computations. It is demonstrated that VOC and FF are severely decreased with an increase in the acceptor concentration and Auger capture coefficients of perovskites, thus reducing the device performance. When the Auger capture coefficient is increased to 10-20 cm6 s-1 under the acceptor concentration of 1016 cm-3, the performance is drastically lowered from 21.5% (without taking Auger recombination into account) to 9.9%. The findings suggest that in order to increase the efficiency of perovskite solar cells and prevent the effects of Auger recombination, the Auger recombination coefficients should be less than 10-24 cm6 s-1.

Simulation and analysis of lead-free perovskite solar cells incorporating cerium oxide as electron transporting layer.

The great demand for renewable energy has greatly contributed to the development of the solar cell industry. Recently, silicon solar cells have dominated the world market. The ease of processing gives perovskite solar cells (PSCs) an advantage over conventional silicon solar cells. Regular silicon photovoltaics require expensive, multi-step processes accomplished in a specialized ultraclean-chamber facility at an elevated temperature (>1000 °C) and highly vacuumed workspace. Hence, researchers and the solar cell industry have focused on PSC as a great rival to silicon solar cells. Despite this, the highest efficiency was obtained from lead-based PSC, which has a considerably high toxicity issue and low stability related to lead content, so the research field pays attention to lead-free perovskite solar cells. In this digital simulation, tin-based perovskite in this paper, methylammonium tin iodide (MASnI3) with the use of cerium oxide (CeO x ) as an electron transporting layer (ETL) with varying percentages of oxygen, which means different shallow donor densities (ND). The optimum value for the thickness of the absorber layer (perovskite) was made, and the current-voltage characteristics and efficiency calculations were also accomplished for the best cell. Then an improvement was made by changing the ND value of CeO x , and the best-optimized cell parameters were: open circuit voltage (V OC) of 0.92 V, short circuit current density (J SC) of 30.79 mA cm-2, power conversion efficiency (PCE) of 17.77%, and fill factor (FF) of 62.86%.

Synthesis, photophysical, electrochemical, and DFT examinations of two new organic dye molecules based on phenothiazine and dibenzofuran.

New dyes were developed and produced utilizing distinct electron donors (phenothiazine and dibenzofuran), a π-spacer, and an electron acceptor of cyanoacetohydrazide, and their structures were studied using FT-IR and NMR spectroscopy. Following the synthesis of dye molecules, the photophysical and photovoltaic characteristics were investigated using experimental and theoretical methods. The photosensitizers have been exposed to electrochemical and optical property experiments in order to study their absorption performance and also molecular orbital energies. The monochromatic optical conversion efficiency of (Z)-N-((5-(10H-phenothiazin-2-yl)furan-2-yl)methylene)-2-cyanoacetohydrazide (PFCH) was found higher than that of (Z)-2-cyano-N'-((5-(dibenzo[b,d]furan-4-yl)furan-2-yl)methylene)acetohydrazide (BFCH), with IPCEs of 58 and 64% for BFCH and PFCH, respectively. According to the photosensitizer molecular energy level diagram, the studied dye molecules have strong thermodynamically advantageous ground and excited-state oxidation potentials for electron injection into the conduction band of titanium oxide. It was observed that the ability to attract electrons correlated favorably with molecular orbital energy. While density functional theory calculations were used to examine molecule geometries, vertical electronic excitations, and frontier molecular orbitals, experimental and computed results were consistent. Natural bond orbital and nonlinear optical properties were also calculated and discussed.

Influence of Sn4+ ion on band gap tailoring, optical, structural and dielectric behaviors of ZnO nanoparticles.

II-VI semiconductors are being attracted due to excellent optical and electronic behaviors when they utilize for device fabrication. Among II-VI semiconductors, Zinc oxide finds cutting-edge results for various applications with a lack of toxicity. Sn4+ ion incorporated ZnO nanoparticles have been synthesized using a soft chemical route and characterized for the investigation of properties like structural, morphological, elemental, optical and dielectric responses. The prepared ZnO had a hexagonal structure and the particles size reduces by the influence of Sn4+ ion: this reduction rate increases for the increase of doping ratio. The average particles size was estimated within 24-34 nm. TEM, HRTEM and SEM results corroborate the structural aspects noticed using XRPD study. UV-vis study results showed that a blue shift on the optical band gap was received for high doping concentration (10 at.%) of Sn4+. PL peaks were observed in the UV region for 0 at.% and 2 at.% Sn4+ doped ZnO nanoparticles, and the peak position was shifted from UV to violet and blue region for 10 at.% Sn4+ doped ZnO nanoparticles. The dielectric permittivity was reduced due to the addition of Sn4+ ions. The AC conductivity was increased for higher doping concentrations. The Sn4+ ion incorporated ZnO nanoparticles shall be useful for various applications including LED fabrication for blue emission and also it is suitable to act as a buffer material in solar panel.

Preparation and Characterization of Mg Doped ZnAI2O4Spinel Nanoparticles.

In the present study, combustion technique is adopted to study the impact of Mg2+ ion doping on ZnAI2O4 nanoparticles (NPs). L-arginine is used as a fuel component. The Mg2+ ions play a pivotal role in persuading various characteristics of ZnAI2O4 NPs. Various characterization technqiues such as Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), energy dispersive X-ray analysis (EDX), high resolution scanning electron microscopy (HR-SEM), diffuse reflectance spectroscopy (DRS), Thermo-gravimetric/differential thermal analysis (TG-DTA) and vibrating sample magnetometer (VSM) were carried out in order to synthesize the nanoparticles. Single phase cubic spinel structure of ZnAl2O4 (gahnite) formation was confirmed from the XRD characterization process of the nanoparticles. Estimated average crystallite size range of 11.85 nm to 19.02 nm was observed from Debye-Scherrer. Spherical morphology with uniform distributions was observed from HR-SEM characterization images. From the band gap studies, the attained band gap values were found to lie within 5.41 eV-4.66 eV range. The ZnAl2O4 and Mg:ZnAl2O4 NPs exhibited super-paramagnetic nature confirmed by magnetic measurements. The obtained results make ZnAl2O 4and Mg:ZnAl2O4 NPs appropriate for various optical, catalytic, energy and data storage applications.

Silver decorated CeO2 nanoparticles for rapid photocatalytic degradation of textile rose bengal dye.

High quality silver (Ag) decorated CeO2 nanoparticles were prepared by a facile one-step chemical method. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), High resolution transmission electron microscopy (HR-TEM), fourier transform infrared spectrometer (FT-IR), electron paramagnetic resonance (EPR), X-ray photoelectron spectroscopy (XPS), UV-Visible absorption (UV-Vis), photoluminescence (PL) and thermogravimetric analysis. The decoration of Ag on CeO2 surface was confirmed by XRD, EPR and HR-TEM analysis. Harmful textile pollutant Rose Bengal dye was degraded under sunlight using the novel Ag decorated CeO2 catalyst. It was found that great enhancement of the degradation efficiency for Ag/CeO2 compared to pure CeO2, it can be ascribed mainly due to decrease in its band gap and charge carrier recombination rate. The Ag/CeO2 sample exhibited an efficient photocatalytic characteristic for degrading RB under visible light irradiation with a high degradation rate of 96% after 3 h. With the help of various characterizations, a possible degradation mechanism has been proposed which shows the effect of generation of oxygen vacancies owing to the decoration of Ag on the CeO2 surface.

Who is dying from COVID-19 and when? An Analysis of fatalities in Tamil Nadu, India.

BACKGROUND: As the number of COVID-19 cases continues to rise, public health efforts must focus on preventing avoidable fatalities. Understanding the demographic and clinical characteristics of deceased COVID-19 patients; and estimation of time-interval between symptom onset, hospital admission and death could inform public health interventions focusing on preventing mortality due to COVID-19. METHODS: We obtained COVID-19 death summaries from the official dashboard of the Government of Tamil Nadu, between 10th May and July 10, 2020. Of the 1783 deaths, we included 1761 cases for analysis. RESULTS: The mean age of the deceased was 62.5 years (SD: 13.7). The crude death rate was 2.44 per 100,000 population; the age-specific death rate was 22.72 among above 75 years and 0.02 among less than 14 years, and it was higher among men (3.5 vs 1.4 per 100,000 population). Around 85% reported having any one or more comorbidities; Diabetes (62%), hypertension (49.2%) and CAD (17.5%) were the commonly reported comorbidities. The median time interval between symptom onset and hospital admission was 4 days (IQR: 2, 7); admission and death was 4 days (IQR: 2, 7) with a significant difference between the type of admitting hospital. One-fourth of (24.2%) deaths occurred within a day of hospital admission. CONCLUSION: Elderly, male, people living in densely populated areas and people with underlying comorbidities die disproportionately due to COVID-19. While shorter time-interval between symptom onset and admission is essential, the relatively short time interval between admission and death is a concern and the possible reasons must be evaluated and addressed to reduce avoidable mortality.

Influence of Ag+ and Mn2+ ions on structural, optical and photoluminescence features of ZnS quantum dots.

The current study deals with the structural, morphological, elemental, optical and photoluminescence behaviors of Ag+, Mn2+ dual doped ZnS quantum dots (QDs). The X-ray diffraction (XRD) and Transmission Electron Microscope (TEM) studies confirmed the cubic structure and size of the crystallites (~2 nm). The Scanning Electron Microscope (SEM) photographs portrayed the surface and morphological structure of prepared samples. Energy dispersive X-ray (EDX) and Fourier Transform Infrared Spectra (FTIR) ensured the presence of Zn, Ag, Mn and, S in the samples as per the anticipated stoichiometry ratio. The UV-visible spectra showed a red shift in optical absorption and band gap gets narrowed due to the incorporation of Ag+ ions. The size effect has overcome the quantum confinement effect in this case. Through photoluminescence (PL) studies, a weak UV emission and strong red wavelength emissions were received and discussed on the basis of sulfur vacancies. This red emission was dealt in terms of d-electrons transition between host and dopant ions.

Automated Detection and Classification of Telemedical Retinopathy of Prematurity Images.

Background: Retinopathy of prematurity (ROP) is a retinal disorder of low birth weight infants and it is the leading cause of childhood blindness. The capability of wide field digital imaging systems to capture the clinical features of ROP has greatly helped the physicians to assess the severity of ROP and prevent childhood blindness due to ROP. Currently there is a lack of automated systems to assess the severity of ROP to assist the ROP specialist to make treatment decision. Objective: To present an automated detection and classification approach to assess the severity of ROP using wide field telemedical images. Materials and Methods: A total of 160 telemedical ROP (tele-ROP) images were collected out, of which 36 images were Normal, 79 images were Stage 2, and 45 images were Stage 3. Hessian analysis and support vector machine (SVM) classifier have been used to detect and classify the severity of ROP from tele-ROP images. Results: Classified the Normal, Stage 2, and Stage 3 images using SVM. Achieved accuracy of 91.8%, sensitivity of 90.37%, specificity of 94.65%, false positive rate of 5.35%, and false negative rate of 9.63%. Conclusions: The automated approach of detecting and classifying ROP would support pediatric ophthalmologists for early treatment decisions with optimal care.

Influence of Ni Doping in SnO2 Nanoparticles with Enhanced Visible Light Photocatalytic Activity for Degradation of Methylene Blue Dye.

In this article, Nickel doped rutile structure tin oxide (SnO2) nanoparticles have been prepared by simple chemical co-precipitation method and prepared samples were characterized by Powder X-ray Diffraction, Fourier transform infrared Spectroscopy, Microraman analysis, Photoluminescene Spectroscopy, UV-Visible Spectroscopy, Energy dispersive analysis and Field emission scanning electron microscope. XRD studies revealed the single phase tetragonal rutile structure with space group of P42/mnm. The average crystallite size of the particles was decreased from 27 to 22 nm with increasing Ni doping concentration. FTIR spectra confirmed the presence of various bands such as O-H, C-H, Sn-O-Sn. Raman modes Eg, A1g and B2g were assigned at 478, 630 and 740 cm-1 which confirmed the single phase of pure and Ni doped SnO2 nanoparticles. The photoluminescence spectra confirmed that the defect related emissions increased with increasing of Ni concentration. The UV absorption spectra showed that the absorption of the particles decreased with increasing Ni concentration and the band gap values decreased from 3.7 to 3.4 eV. EDX spectra confirmed the presence of Sn, Ni, O in pure and doped samples. The photocatalytic activity of the pure and Ni doped SnO2 nanoparticles were analyzed by using methylene blue dye under visible light irradiation. It is concluded Ni (7%) doped SnO2 nanoparticles have higher degradation efficiency compared to pure SnO2 nanoparticles.

Giant Sialolith of Submandibular Duct.

Sialolithiasis is one of the most common diseases of salivary glands and commonly involves submandibular gland and ducts. "Giant sialoliths" typically measure more than 15 mm in any dimension. Here, an unusual case of sialolith in submandibular duct is reported which progressed into a giant sialolith in six months' time is reported. A 42-year-old man presented with complaints of recurrent pain and swelling in the right submandibular area. A large stone was palpable intraorally within the Wharton's duct and intra-operatively, an elongated giant sialolith of 50 mm length was found which is the second largest to be published till date.

Acute Retropharyngeal Abscess Masquerading as Meningitis.

Retropharyngeal abscess is a potentially serious deep neck space infection occurring more frequently in children than in adults. The clinical picture of RPA is highly variable with paucity of physical findings. Prompt diagnosis of RPA especially in infants is mandatory to prevent potential fatal complications including airway obstruction. The diagnosis of RPA should be based on high index of clinical suspicion with supportive imaging studies like lateral X-ray of neck and CT. We present a case of acute retropharyngeal abscess which was initially misdiagnosed as meningitis and led to airway obstruction. This case is reported to create awareness among emergency physicians, paediatricians and otolaryngologists to have high index of suspicion in diagnosing RPA especially in infants.

Quality of life outcome measures using University of Washington questionnaire version 4 in early T1/T2 anterior tongue cancers with and without radiotherapy: A cross-sectional study.

CONTEXT: To evaluate the quality of life (QOL) outcome measures in disease-free survivors of pathological T1/T2 tongue cancers and to compare QOL in patients treated with only surgery and with adjuvant treatment. SETTINGS AND DESIGN: Cross-sectional survey. PATIENTS AND METHODS: All pathological T1/T2 anterior tongue cancer cases with follow-up from January 2011 till December 2015, who had locoregionally controlled disease with a minimum disease-free survival period of 1 year, were included in the study. RESULTS: A total of 36 patients, 28 are males and 8 are females with an age range of 24-66 years (median age of 43) were enrolled in the study. The patients were divided into two groups with (n = 26) and without adjuvant postoperative radiotherapy (RT) (n = 10) and the University of Washington-QOL questionnaire version 4 for physical and social domains, global questions and three important domains were analyzed. On the physical and social domain scores, the surgery-alone group outscored the combined modality group on all scales and the differences were statistically significant for specific physical domains such as saliva (0.0001), taste (P = 0.0001), chewing (P = 0.0004), swallowing (P = 0.0026), and social domains such as mood (0.0001), pain (P = 0.0001), and shoulder function (P = 0.0061). The overall global QOL scores were also better for the surgical group compared with group which received adjuvant RT but was not statistically significant. All patients chose saliva as their top priority domain in the group which received radiation, and 60% chose "swallowing ability" as the preferred top priority domain in the only surgical group. CONCLUSIONS: Although locoregional control and disease-free survival are the major treatment-related endpoints for cancer management, QOL outcome measures have to assess to determine the impact of a treatment modality on patients well-being and for better rehabilitation of cancer-free patients.

Pulmonary sarcoidosis is associated with high-level inducible co-stimulator (ICOS) expression on lung regulatory T cells--possible implications for the ICOS/ICOS-ligand axis in disease course and resolution.

Sarcoidosis is a granulomatous inflammatory disorder of unknown aetiology. The increased frequency of activated lung CD4(+) T cells with a T helper type 1 (Th1) cytokine profile in sarcoidosis patients is accompanied by a reduced proportion and/or impaired function of regulatory T cells (Tregs ). Here we evaluated the expression of the inducible co-stimulator (ICOS) on lung and blood CD4(+) T cell subsets in sarcoidosis patients with different prognosis, by flow cytometry. Samples from the deep airways were obtained by bronchoalveolar lavage (BAL). We show that Tregs from the inflamed lung of sarcoidosis patients were characterized by a unique ICOS(high) phenotype. High-level ICOS expression was restricted to Tregs from the inflamed lung and was absent in blood Tregs of sarcoidosis patients as well as in lung and blood Tregs of healthy volunteers. In addition, lung Tregs exhibited increased ICOS expression compared to sarcoid-specific lung effector T cells. Strikingly, ICOS expression on Tregs was in particularly high in the lungs of Löfgren's syndrome (LS) patients who present with acute disease which often resolves spontaneously. Moreover, blood monocytes from LS patients revealed increased ICOS-L levels compared to healthy donors. Sarcoidosis was associated with a shift towards a non-classical monocyte phenotype and the ICOS-L(high) phenotype was restricted to this particular monocyte subset. We propose a potential implication of the ICOS/ICOS-L immune-regulatory axis in disease activity and resolution and suggest to evaluate further the suitability of ICOS as biomarker for the prognosis of sarcoidosis.