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Surface/interface engineering of methylammonium lead bromide (MAPbBr3) single crystals (SCs) is crucial for carrier generation/recombination, separation, and transportation, thereby enabling superior optoelectronics. Herein, a surface‐engineered crystallization technique is presented in which a thin polycrystalline MAPbBr3 layer is in situ grown on the surface of bulk mm‐sized MAPbBr3 SCs. The growth direction and the atomic distribution of both the polycrystalline surface layer and the single crystalline core have been analyzed by damage‐free atomic‐resolution transmission electron microscopy (TEM). The polycrystalline nature of the crystals gives rise to bright green emission under UV light. Scanning probe microscopy results show that the current at the emissive MAPbBr3 film/MAPbBr3 SC surface is five times higher than that at a non‐emissive surface when illuminated. Lateral photodetectors based on MAPbBr3 film/MAPbBr3 SCs can achieve excellent detectivities (≈1013 Jones) and high photoresponsivities (≈20 A W−1). Furthermore, a semiconductor‐based fluorescence quick response (FQR) code is patterned on the same bright green‐emitting surface of the MAPbBr3 film/MAPbBr3 SC using a picosecond laser pulse, with a scalability of 3 × 3 mm2. An FQR code integrated with a photodetector may serve as a potential double security tag in bank cards, passports, door security, etc. [ABSTRACT FROM AUTHOR]

Atomic-scale examination of lead halide perovskites is currently a subject of growing interest for applications in the optimization of perovskite-based photovoltaic and optoelectronic devices. While transmission electron microscopy (TEM) is a powerful tool to characterize these electron-sensitive materials at the atomic scale, it induces structural and chemical modifications along with other undesirable artifacts. Here, we investigate the phase stability of nominally Cu-doped CsPbI3 nanocrystals, with enhanced structural stability as compared to their pristine counterparts, against electron irradiation using high-resolution TEM at ambient conditions. Our findings reveal a significant transformation from the cubic to the orthorhombic phase at a dose of ∼3 × 103 e–/Å2. Analysis of the beam energy deposited per unit cell, along with the evolution of lattice energy with varying cell dimensions, as obtained from density functional theory, provides valuable insights into the mechanisms governing the beam-induced phase decomposition process, corroborated by the phonon dispersion of the system, which is not yet reported. At a critical dose of ∼1.68 × 106 e–/Å2, the lattice undergoes complete and irreversible degradation. Thus, our study demonstrates real-time in situ beam-induced phase decomposition in Cu-doped CsPbI3 for the first time, with an estimation of the electron dose limits below which beam-induced alterations are minimal, allowing accurate imaging and analysis of perovskites. [ABSTRACT FROM AUTHOR]

For GNSS Real-Time Kinematic (RTK), the reference Base receiver operating at a precise location together with the wirelessly connected Rover receiver(s) provide(s) high-quality real-time position solutions. This work shows the potential of compact, low-cost, single-frequency (CLS) GNSS modules as the RTK Rover up to large baseline distances. A combination of the uBLOX M8T CLS module and the Tallysman TW2710 patch antenna is used in single and hybrid GNSS combinations for short-to-long single-baseline lengths with the open-source RTKLib as the processing software. The results show that, for up to 288 km baseline distance, GPS, GLONASS and Galileo standalone operation provides below 1, 3 and 2 m precisions, respectively and sub-0.5 m precision is achieved for GPS+GLONASS+Galileo and GPS+Galileo+QZSS operations. The work shows the advantages of CLS modules as Rover those exploits the multi-constellation signal availability from India using open-source RTK processing software for reduction of the overall RTK infrastructure cost. [ABSTRACT FROM AUTHOR]

Global Navigation Satellite System (GNSS) sensors are increasingly considered as major sources of precise Position, Navigation, and Timing (PNT) information. Android-based smartphones contain inbuilt GNSS sensors, and they now contribute to a major global GNSS market segment. Various hardware and Android-based applications (App) developments are witnessed to best exploit the current multi-constellation, multi-frequency GNSS environment. Since Android version 7.0 (Nougat) and Location Application Programming Interface (API) 24, recording GNSS raw data in the smartphone became possible. This paper describes the potential of commercial Smartphones and reviews the capabilities of Android Apps for cost-efficient GNSS measurements for the geospatial community and a novel classification of the Apps based on their capabilities and usability. Results on the positioning capability of common smartphones using real-time data show the achievable modest solution precision, and these are suitable for use of the devices in geomatics applications, improved App development, and for IoT-based system and infrastructure development. [ABSTRACT FROM AUTHOR]

Hot carrier extraction is crucial for efficient solar energy harvesting, and lead halide perovskite nanocrystals (NCs) are potential candidates for photovoltaic and light-emitting applications. Therefore, swift extraction of hot carriers is an immediate requirement to improve the energy conversion efficiency, which need longer thermalization time. To address this issue, we synthesized nominally Cu-doped CsPbI3 NCs with enhanced structural and optical characteristics compared to undoped CsPbI3 NCs. We investigated the hot carrier dynamics in both the NCs at different fluences using ultrafast transient absorption spectroscopy. Interestingly, we observed very fast thermalization at higher fluences that indicated breaking of the phonon bottleneck. On the contrary, doped NCs preserved the effects and decayed over a longer period of time possibly due to increase in size and introduction of shallow trap states of Cu 3d and Cu 4s electrons in the conduction band, as computed using density functional theory. Notably, as the carrier–carrier interaction increased, we observed a dominating bandgap renormalization in the doped system compared to the undoped system. Overall, our studies improve the understanding of Cu doping in enhancing the hot carrier dynamics in perovskites and open possibilities for further investigation in the quantum phenomenon of these materials. [ABSTRACT FROM AUTHOR]

From the beginning of World War II, dual-axis tracking radars have played an important role in the tracking of missiles in test ranges. These radars operate mostly in S- or C-band of frequencies. However, these Radars have associated problems with the costly maintenance budget, various errors that creep into the data, and inter-radar bias correction. The modern-day global navigation satellite system (GNSS) together with space-based augmentation systems (SBAS) have provided scope to obtain internally generated and telemetered trajectory data from the missile under test (MUT) from the onboard GNSS receiver with SBAS capabilities within comparable or better accuracies. This research presents a comparison of the precession parameters of the MUT's position solutions between data from several tracking radars and those from the enhanced GNSS data. Also, experiments have been conducted using various satellite navigation constellations including NavIC and SBAS augmentation to demonstrate the improvement in accuracy and precession parameters applicable to the Indian scenario. To compete with the outcomes of contemporary satellite-based navigation system together with the augmentation systems for trajectory generation of cooperative missile targets, radar manufacturers must reconsider their design philosophies for usage on missile test ranges. [ABSTRACT FROM AUTHOR]

Utilizing the remarkably high light absorption and long carrier diffusion length of inorganic perovskites, superior performance self‐powered broadband photodetectors using the vertical heterojunction of cesium lead iodide (CsPbI3) nanocrystals (NCs) and zinc oxide (ZnO) films on a flexible platform are reported. Here, the pure cubic or α‐phase of as‐synthesized CsPbI3 NCs facilitate the novelty of the present work in terms of their enhanced structural stability suitable for optical applications. The α‐CsPbI3/ZnO device exhibits superior performance with photoresponsivity of ≈8.2 AW−1, ON/OFF ratio of ≈2.4 × 104, and specific detectivity up to ≈1.4 × 1012 Jones. Furthermore, the piezo‐phototronic effect of ZnO has been exploited to enhance the device performance by utilizing the compressive strain‐induced piezoelectric charges for modulating the generation, separation, and transportation of charge carriers. By introducing an approximate −0.042% compressive strain in the hybrid heterostructure, the enhancement of photocurrent, spectral responsivity, and specific detectivity of the detector by ≈619%, ≈536%, and ≈506%, respectively, under visible light illumination has been successfully achieved. This work not only presents an inventive method for improving the performance of perovskite photodetectors through interface engineering, but it also provides a thorough understanding of the piezo‐phototronic effect on optoelectronic devices. [ABSTRACT FROM AUTHOR]

Global Navigation Satellite System (GNSS) provides precise Position, Velocity, and Timing (PVT) information. Various types of receivers of varying cost and complexity are used for collection and use of GNSS data. Currently, cost-effective, compact, low power consuming, multi-constellation enabled, single, or dual-frequency GNSS modules are being increasingly available having the capability of providing modest position solution accuracy. This paper presents the results of GPS, BeiDou, and GPS + BeiDou hybrid positioning capabilities of few commercially available modules based on systematic analysis from data collected during two time periods from two locations of India using geodetic and commercial patch antennas w.r.t. the reference points created through PPP (Precise Point Positioning). The results are compared with those provided a survey-grade GNSS receiver. It is witnessed that, selected single frequency module can provide 3-4m 2DRMS (Distance Root Means Square) precision and their dual frequency counterparts can provide 2DRMS solution precision around 3 m in GPS-only operation, around 7 m in BeiDou-only operation and around 3.5 m in case of GPS + BeiDou hybrid operation. The performance of the compact modules clearly presents the cost-performance benefit of the compact modules for real-time applications and the results of this study would help in understanding the capabilities of these modules for mass-market applications. [ABSTRACT FROM AUTHOR]

Real-time environmental data acquisition and monitoring is a significant aspect of IoT-enabled farming to overcome the constraints in present day's farming that includes regular monitoring of agricultural fields and adjacent weather-related information. Real-time monitoring can be achieved by measuring various parameters such as humidity, pressure, temperature and location data using sensors. The humidity, pressure and temperature data help in environmental monitoring of the farming zone, and the latitude and longitude data enable specific location-based farming. The measured parameters are to be communicated to the primary users efficiently in real time. This work showcases the concept of IoT-enabled farming in line with agriculture 4.0 where a hardware module consisting of a Raspberry Pi, SenseHat and low-cost, compact GPS receiver is implemented for agricultural applications. This idea would be useful for cost-effective IoT research, application development and for data recording in harsh and constrained environmental conditions with advantages of compact size and low power consumptions. The module design has a dimension of 20 × 11cm2 and has a temperature accuracy of ± 2 °C, humidity in the 20–80% RH range with an accuracy ± 4.5%, pressure sensor with 260–1260 hPa absolute range with ± 0.1 hPa under normal conditions, and the GPS sensor has an accuracy of 2.5 m. The proposed system is made Wi-Fi enabled to acquire data in the server for the primary users. [ABSTRACT FROM AUTHOR]

Although α‐CsPbI3 is regarded as an attractive optical luminophore, it is readily degraded to the optically inactive δ‐phase under ambient conditions. Here, we present a simple approach to revive degraded ("optically sick") α‐CsPbI3 through "medication" with thiol‐containing ligands. The effect of different types of thiols is systematically studied through optical spectroscopy. The structural reconstruction of degraded α‐CsPbI3 nanocrystals to cubic crystals in the presence of thiol‐containing ligands is visualized through high‐resolution transmission electron microscopy and supported by X‐ray diffraction analysis. We found that 1‐dodecanethiol (DSH) effectively revives degraded CsPbI3 and results in high immunity towards moisture and oxygen, hitherto unreported. DSH facilitates the passivation of surface defects and etching of degraded Cs4PbI6 phase, thus reverting them back to the cubic CsPbI3 phase, leading to enhanced PL and environmental stability. [ABSTRACT FROM AUTHOR]

Although α‐CsPbI3 is regarded as an attractive optical luminophore, it is readily degraded to the optically inactive δ‐phase under ambient conditions. Here, we present a simple approach to revive degraded ("optically sick") α‐CsPbI3 through "medication" with thiol‐containing ligands. The effect of different types of thiols is systematically studied through optical spectroscopy. The structural reconstruction of degraded α‐CsPbI3 nanocrystals to cubic crystals in the presence of thiol‐containing ligands is visualized through high‐resolution transmission electron microscopy and supported by X‐ray diffraction analysis. We found that 1‐dodecanethiol (DSH) effectively revives degraded CsPbI3 and results in high immunity towards moisture and oxygen, hitherto unreported. DSH facilitates the passivation of surface defects and etching of degraded Cs4PbI6 phase, thus reverting them back to the cubic CsPbI3 phase, leading to enhanced PL and environmental stability. [ABSTRACT FROM AUTHOR]

Galileo and NavIC, respectively, are two operational global and regional satellite-based navigation systems maintained by civilian authorities. Hybrid operation of a global and a regional system offers advantages for the user community within the service area of the regional system. In view of the signal structure similarity of Galileo and NavIC, hybrid operation of the two systems has been studied from India and surrounding regions to explore the possible complimentary benefits. Based on long-term, real-time observations from two locations within the NavIC central region and validated simulations, Galileo and NavIC constellations were found to supplement each other. In the central region, relatively poor Galileo availability is supplemented by NavIC and in the boundary areas Galileo supports inferior NavIC visibility. The time- and location-dependent low-elevation angle problem for the Galileo satellites is supplemented by NavIC signals transmitted from GEO and GSOs for seamless and improved operation. In terms of typical satellite visibility within the constrained satellite visibility conditions, satellite geometry and signal strength, the Galileo–NavIC hybrid operation offers user benefits over the Indian region as well as over the entire NavIC service area extending from east Africa to west Australia. Real-time data collected from survey grade GNSS receivers and compact GNSS module clearly indicates the improved solution quality of the hybrid operation compared to each of the individual constellations. The results would be beneficial for the user community in exploiting the benefits of the Galileo and NavIC concurrent operation. [ABSTRACT FROM AUTHOR]

Synthesis of monodispersed, stable halide, and mixed halide perovskite nanocrystals by hot‐injection approach is still challenging due to the fast reaction kinetics and unrevealed ligand chemistry. The atomic scale imaging of perovskite nanocrystals using transmission electron microscopy (TEM) is also challenging because of their structural degradation due to high electron dose and soft nature of perovskites. Here, a novel technique is proposed to synthesize pure cubic phase, monodispersed, stable CsPbX3 (X = I/Br) nanocrystals by simply modifying ligand chemistry using olive oil, which also leads to realization of tuneable composition mixed halide perovskites by simple physical mixing. Here, the atomic scale images and the probable distribution of Cs, Pb, and I/Br atoms in single halide and mixed halide perovskites via high‐resolution TEM microscopy are presented. The estimated atomic distance (PbPb and PbI/Br) is strongly corroborated with the VESTA structure. Interestingly, the lattice constant (d‐value) of the synthesized nanocrystals is smaller (≈3%) than the theoretical predicted one, leading to a higher phase stability in laboratory ambient conditions (45–55% humidity, 300 K). The theoretical analysis using density functional theory enlightens the understanding of higher stability of CsPbI2Br along with the maximum optical absorption in the visible regime, as a preferable material for the photovoltaic applications. [ABSTRACT FROM AUTHOR]

Geodetic or special purpose Global Navigation Satellite System (GNSS) receivers are used for ionosphere monitoring and research. Dual frequency, compact, low‐cost commercial GNSS modules can provide raw GNSS data and are commonly used for positioning applications. This paper presents the applicability of these compact modules for monitoring ionospheric activities. A comparative study between Javad Triumph LS, a costly geodetic receiver, and an Ublox ZED‐F9P, a low‐cost, dual‐frequency, compact module is carried out to explore the potential of the low‐cost devices for ionosphere probing. Studies are carried out on signal strength values (C/N0) and vertical total electron content (VTEC) values. From the concurrently collected GPS data, a bias of 2.2–4.9 dBHz in signal strength values are observed between the two types of receivers depending on the signal frequency band. The VTEC values calculated from the Ublox module are in close agreement with the values obtained from the Triumph LS receiver. Therefore, the compact module shows the potential for use in ionosphere monitoring with clear advantages in cost, size, and power consumption. However, the signal strength values obtained from such compact modules need to be calibrated using standard GNSS receivers. A GNSS‐based Ionosphere Monitoring Unit (GIMU) is also proposed in this manuscript by the integration of a compact, low‐cost GNSS module with a single‐board computer and a wireless data communication module. Real‐time, cost‐effective, concurrent ionosphere monitoring over a geographically distributed network is possible using a network of such units. Plain Language Summary: Navigation satellites provide position, velocity, and timing information. The navigation satellite signals while passing through the ionosphere are affected by it, and therefore, are also used for studying ionospheric characters. Geodetic or special purpose Global Navigation Satellite System (GNSS) receivers are usually used for the studies; the hardware is not affordable for all users and has the constraints of size and power requirement. Compact, low‐cost GNSS receivers are now commercially available and are primarily used for positioning purposes. Some of these modules operate in dual‐frequency and can provide raw data at a rate up to 5 Hz and therefore, have the potential for ionospheric monitoring and research. In this paper, favorable results on the usability of such dual‐frequency, compact, low‐cost GNSS receiver modules for ionospheric research are presented. Using concurrent data, comparative studies are made between geodetic and compact, low‐cost receivers on satellite signal strength values and VTEC. It is found that the low‐cost GNSS modules have the potential to be used in ionosphere studies with make and model‐specific calibration. Multiple such receivers can be deployed over a geographical region for networked, concurrent GNSS‐based ionosphere monitoring, and successful implementation of the idea will support the associated research community. Key Points: Navigation satellite signals are used for ionosphere monitoring; geodetic or special purpose navigation receivers are usually used for the purpose. Low‐cost, compact, dual‐frequency, commercial Global Navigation Satellite System (GNSS) modules have the potential for such applicationsSignal strength and vertical total electron content (VTEC) values obtained using concurrent GPS data from a geodetic GNSS receiver and a compact GNSS module are compared. The signal strength values from the two types of receivers show a similar variation pattern, and the VTEC values are found to be in extremely close agreementThe compact GNSS modules, thus, can be used for ionospheric research with distinct advantages of cost, size and power requirement. Use of the compact, low‐cost modules will help in developing a networked, concurrent GNSS‐based ionospheric monitoring system over a distributed geographical area [ABSTRACT FROM AUTHOR]

The synthesis of single‐crystalline β‐CsPbI3 perovskite nanorods (NRs) using a colloidal process is reported, exhibiting their improved photostability under 45–55% humidity. The crystal structure of CsPbI3 NRs films is investigated using Rietveld refined X‐ray diffraction (XRD) patterns to determine crystallographic parameters and the phase transformation from orthorhombic (γ‐CsPbI3) to tetragonal (β‐CsPbI3) on annealing at 150 °C. Atomic resolution transmission electron microscopy images are utilized to determine the probable atomic distribution of Cs, Pb, and I atoms in a single β‐phase CsPbI3 NR, in agreement with the XRD structure and selected area electron diffraction pattern, indicating the growth of single crystalline β‐CsPbI3 NR. The calculation of the electronic band structure of tetragonal β‐CsPbI3 using density functional theory (DFT) reveals a direct transition with a lower band gap and a higher absorption coefficient in the solar spectrum, as compared to its γ‐phase. An air‐stable (45–55% humidity) inverted perovskite solar cell, employing β‐CsPbI3 NRs without any encapsulation, yields an efficiency of 7.3% with 78% enhancement over the γ‐phase, showing its potential for future low cost photovoltaic devices. [ABSTRACT FROM AUTHOR]

Navigation with Indian Constellation (NavIC) is designed and deployed by Indian Space Research Organization (ISRO) as an indigenous, regional navigational system to provide precise PVT information over the Indian region and surrounding areas. This paper presents a detailed analysis of NavIC visibility under open sky and constrained condition over the service region using an in-house developed simulation tool, the effects of NavIC satellite geometry on single-point solution accuracy and NavIC single and dual frequency solution performances. The results show the potential of NavIC as an alternative navigation system for India and the neighbouring countries in south and south-east Asia, and over an economically important area containing major sea-routes. Even in constrained-visibility conditions, NavIC with its typical constellation design can offer seamless navigation solution over a large region of the globe; the unique S-Band NavIC signal supports enhanced accuracy for stand-alone operation. The results would be beneficial for understanding the potential of NavIC for the user community. [ABSTRACT FROM AUTHOR]

During the last decade, transition metal oxides have been actively investigated as hole- and electron-selective materials in organic electronics due to their low-cost processing. In this study, four transition metal oxides (V2O5, MoO3, WO3, and ReO3) with high work functions (>5 eV) were thermally evaporated as front p-type contacts in planar n-type crystalline silicon heterojunction solar cells. The concentration of oxygen vacancies in MoO3-x was found to be dependent on film thickness and redox conditions, as determined by X-ray Photoelectron Spectroscopy. Transfer length method measurements of oxide films deposited on glass yielded high sheet resistances (~109 Ω/sq), although lower values (~104 Ω/sq) were measured for oxides deposited on silicon, indicating the presence of an inversion (hole rich) layer. Of the four oxide/silicon solar cells, ReO3 was found to be unstable upon air exposure, while V2O5 achieved the highest open-circuit voltage (593 mV) and conversion efficiency (12.7%), followed by MoO3 (581 mV, 12.6%) and WO3 (570 mV, 11.8%). A short-circuit current gain of ~0.5 mA/cm² was obtained when compared to a reference amorphous silicon contact, as expected from a wider energy bandgap. Overall, these results support the viability of a simplified solar cell design, processed at low temperature and without dopants. [ABSTRACT FROM AUTHOR]

Background: Functional brace application for isolated humeral shaft fracture persistently yields good results. Nonunion though uncommon involves usually the proximal third shaft fractures. Instead of polyethylene bivalve functional brace four plaster sleeves wrapped and molded with little more proximal extension expected to prevent nonunion of proximal third fractures. Periodic compressibility of the cast is likely to yield a better result. This can be applied on the 1st day of the presentation as an outpatient basis. Comprehensive objective scoring system befitting for fracture humeral shaft is a need. Materials and Methods: Sixty six (male = 40, female = 26) unilateral humeral shaft fractures of mean age 34.4 years (range 11-75 years) involving 38 left and 28 right hands were included in this study during April 2008 to December 2012. Fractures involved proximal (n = 18), mid (n = 35) and distal (n = 13) of humerus. Transverse, oblique, comminuted and spiral orientations in 18, 35 and 13 patients respectively. One had segmental fracture and three had a pathological fracture with cystic bone lesion. Mechanisms of injuries as identified in this study were road traffic accidents 57.6% (n = 38), fall 37.9% (n = 25). 12.1% (n = 8) had radial nerve palsy 7.6% (n = 5) had Type I open fracture. Four plaster strips of 12 layers and 5-7.5 cm broad depending on the girth of arm were prepared. Arm was then wrapped with single layer compressed cotton. Lateral and medial strips were applied and then after molding anterior and posterior strips were applied in such a way that permits full elbow range of motion and partial abduction of the shoulder. Care was taken to prevent adherence of one strip with other except in the proximal end. Limb was then put in loose collar and cuff sling intermittently allowing active motion of the elbow ROM and pendular movement of the shoulder. Weekly tightening of the cast by fresh layers of bandage over the existing cast brace continued. Results: The results were assessed using 100 point scoring system where union allotted 30 points and 60 points allotted for angulations (10), elbow motion (10), shoulder abduction (10), shortening (5), rotation (5), absence of infection (10), absence of nerve palsy during treatment (10). Remaining 10 points were allotted for five items with two points each. They were the absence of skin sore, absence of vascular problem, absence of reflex sympathetic dystrophy (RSD), recovery of paralyzed nerve during injury and recovery of paralyzed nerve during treatment. Results were considered excellent with 90 and above, good with 80-89, fair with 70-79 and poor below 70 point. Results at 6 months were excellent in 43.94% ( n = 29), good in 42.42% ( n = 28), fair in 9.1% ( n = 6), poor in 4.55% ( n = 3). Union took place in 98.48% ( n = 65) with an average of 10.3 weeks (range 6-16 weeks). 87.5% ( n = 7) paralyzed radial nerve recovered. All wounds healed. Four patients had transient skin problem. One patient with mid shaft fracture had nonunion due to the muscle interposition. Conclusion: Modified functional cast brace is one of the options in treatment for humeral shaft fractures as it can be applied on the 1st day of the presentation in most of the situations. Simple objective scoring system was useful particularly in uneducated patients. [ABSTRACT FROM AUTHOR]