A Facile Bottom-Up Approach to Construct Hybrid Flexible Cathode Scaffold for High-Performance Lithium–Sulfur Batteries

Lithium–sulfur batteries mostly suffer from the low utilization of sulfur, poor cycle life, and low rate performances. The prime factors that affect the performance are enormous volume change of the electrode, soluble intermediate product formation, poor electronic and ionic conductivity of S, and end discharge products (i.e., Li₂S₂ and Li₂S). The attractive way to mitigate these challenges underlying in the fabrication of a sulfur nanocomposite electrode consisting of different nanoparticles with distinct properties of lithium storage capability, mechanical reinforcement, and ionic as well as electronic conductivity leading to a mechanically robust and mixed conductive (ionic and electronic conductive) sulfur electrode. Herein, we report a novel bottom-up approach to synthesize a unique freestanding, flexible cathode scaffold made of porous reduced graphene oxide, nanosized sulfur, and Mn₃O₄ nanoparticles, and all are three-dimensionally interconnected to each other by hybrid polyaniline/sodium alginate (PANI–SA) matrix to serve individual purposes. A capacity of 1098 mAh g^–1 is achieved against lithium after 200 cycles at a current rate of 2 A g^–1 with 97.6% of initial capacity at a same current rate, suggesting the extreme stability and cycling performance of such electrode. Interestingly, with the higher current density of 5 A g^–1, the composite electrode exhibited an initial capacity of 1015 mA h g^–1 and retained 71% of the original capacity after 500 cycles. The <i>in situ</i> Raman study confirms the polysulfide absorption capability of Mn₃O₄. This work provides a new strategy to design a mechanically robust, mixed conductive nanocomposite electrode for high-performance lithium–sulfur batteries and a strategy that can be used to develop flexible large power storage devices

Ultrafast Carrier Dynamics of Photo-Induced Cu-Doped CdSe Nanocrystals

The understanding of ultrafast carrier relaxation process in doped semiconductor quantum dots (QDs) is very important for their potential applications in light-emitting diodes, optoelectronics. Here, we have studied the change in electronic properties of Cu-doped CdSe QDs upon light illumination. The light-induced effect leads to the enhancement of the band edge decay time and reduces the decay time of the dopant emission due to photocorrosion of Cu-doped CdSe QDs. The bleaching recovery kinetics and the hot electron cooling dynamics have been studied by using femtosecond transient absorption spectroscopy. It is observed that the electron cooling process of doped CdSe QDs is dependent on the dopant concentration and the cooling kinetics of doped CdSe QDs are found to be slower than undoped QDs. After light irradiation, the cooling processes of hot electron and recovery process in doped systems are modified

Chromoblastomycosis in India: Review of 169 cases

<div><p>Chromoblastomycosis (CBM) is a chronic, progressive, cutaneous and subcutaneous fungal infection following the traumatic implantation of certain dematiaceous fungi. The disease has worldwide prevalence with predominant cases reported from humid tropical and subtropical regions of America, Asia, and Africa. Diagnosis is often delayed or misdirected either due to poor degree of clinical suspicions or clinical simulation of dermatological conditions. The infection is not uncommon in India and several case reports from the sub-Himalayan belt and western and eastern coasts of India have been published; however, very few have reviewed the cases. We reviewed 169 cases published in English literature from India during 1957 through May 2016, including 2 recent cases from our institute. A tremendous increase in the number of reported cases was noticed since 2012, since which, more than 50% of the cases had been published. A majority of the patients (74.1%) were involved in various agricultural activities directly or indirectly. The mean age at presentation was 43.3 years ± 16.0, with male to female ratio of 4.2:1. The duration of disease at the time of presentation varied from 20 days to 35 years. Any history of trauma was recalled only in 33.8% of the studied cases. The lower extremity was the most common site afflicted, followed by the upper extremity. The culture was positive in 80.3% of the cases with <i>Fonsecaea pedrosoi</i>, isolated as the most common fungal pathogen, followed by <i>Cladophialophora carrionii</i>. Although all the commercially available antifungals were prescribed in these cases, itraconazole and terbinafine were the most commonly used, either alone or in combination with other drugs/physical methods, with variable degrees of outcome. Combinations of different treatment modalities (chemotherapy and physical methods) yielded a cure rate of 86.3%. CBM is refractory to treatment and no single antifungal agent or regimen has demonstrated satisfactory results. Increased awareness with early clinical suspicion of the disease and adequate therapy are necessary to improve the outcome. However, depending upon the causative agent, disease severity, and the choice of antifungals, variable outcomes can be observed.</p></div

Exciton Dynamics and Formation Mechanism of MEH-PPV Polymer-Based Nanostructures

The recent emergence of conjugated polymer-based nanostructured materials has stimulated a lot of interest in developing light harvesting systems. Here, we describe the formation of nanoparticles from polymer molecules [poly­[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) by adding a nonsolvent (water) and understand their collapsing mechanism from the extended form by using molecular dynamics simulations. Free energy calculations reveal that the thermodynamically stable state of the polymer in water and 75% (v/v) water/THF mixture is a collapsed state. The red shift of the absorption band of the collapsed state is found due to a change in polarity of the solvent. The change in intensity of the blue and red emission bands with a change in the solvent polarity is explained due to a change in conformation from the extended state to the collapsed state of the polymer. Ultrafast spectroscopic analysis reveals a systematic decrease of the faster component at 554 nm (33 to 2 ps), indicating the energy transfer process. The faster component (150 fs) of the time-resolved anisotropy decay due to the fast depolarization process confirms the interchain energy transfer in the collapsed state. The fundamental understanding of photophysics of conjugated polymer nanoparticles should pave the way for future development of light harvesting systems

Sulfur Copolymer: A New Cathode Structure for Room-Temperature Sodium–Sulfur Batteries

High-energy electrochemical storage containing earth abundant materials could be a choice for future battery development. Recent research reports indicated the possibility of room-temperature sodium-ion–sulfur chemistry for large storage including smart grids. Here, we report a room-temperature sodium–sulfur battery cathode that will address the native downsides of a sodium–sulfur battery, such as polysulfide shuttling and low electrical conductivity of elemental sulfur. In this Letter, we use a sustainable route which ensures a large sulfur confinement (i.e., ∼90 wt %) in the cathode structure. The sulfur-embedded polymer is realized via thermal ring-opening polymerization of benzoxazine in the presence of elemental sulfur (CS90) and later composite with reduced graphene oxide (rGO). The resulting CS90 allows a homogeneous distribution of sulfur due to in situ formation of the polymer backbone and allows maximum utilization of sulfur. This unique electrode structure bestows CS90–rGO with an excellent Coulombic efficiency (99%) and healthy cycle life

Size of CdTe Quantum Dots Controls the Hole Transfer Rate in CdTe Quantum Dots–MEHPPV Polymer Nanoparticle Hybrid

Design of light harvesting systems using inorganic–organic hybrid nanostructures is an emerging field of research. Here, we design hybrid nanostructures by using electrostatic attraction of negatively charged CdTe QDs with positively surface functionalized poly­[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEHPPV) polymer nanoparticles for developing an efficient light harvesting system. Interfacial charge transfer between QDs and polymer nanoparticles has been investigated by ultrafast spectroscopy which is crucial for designing an efficient light harvesting system. Interfacial charge transfer dynamics are being controlled by tuning the size of QDs which is eventually controlled by highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) levels of QDs. Femtosecond fluorescence upconversion and transient absorption spectroscopic studies reveal that the hole transfer process takes place from QDs to polymer nanoparticles and the rate of hole transfer process is size dependent on QDs. The fundamental understanding of the charge transfer dynamics opens up new possibilities to design an efficient light harvesting system based on an inorganic–organic hybrid system

A time line of the number of cases of chromoblastomycosis reported from India since 1957.

<p>A time line of the number of cases of chromoblastomycosis reported from India since 1957.</p

The map of India is depicted here with the state-wise distribution of cases.

<p>The map of India is depicted here with the state-wise distribution of cases.</p

The table shows the outcome of various treatment modalities.

<p>The table shows the outcome of various treatment modalities.</p

The figure shows age-wise distribution of cases with chromoblastomycosis in India.

<p>The figure shows age-wise distribution of cases with chromoblastomycosis in India.</p