Possibility Of Further Enhancement Research Articles

Pushing the limit of BGO-based dual-ended Cherenkov PET detectors through photon transit time correction

Objective. The high production cost of commonly used lutetium-based fast scintillators and the development of silicon photomultipliers technology have made bismuth germanate (BGO) a promising candidate for time-of-flight positron emission tomography (TOF PET) detectors owing to its generation of prompt Cherenkov photons. However, using BGO as a hybrid scintillator is disadvantageous owing to its low photon statistics and distribution that does not conform well to a single Gaussian. To mitigate this, a proposal was made to increase the likelihood of detecting the first Cherenkov photons by positioning two photosensors in opposition at the entrance and exit faces of the scintillator and subsequently selectively picking an earlier timestamp. Nonetheless, the timing variation arising from the photon transit time remains affected by the entire length of the crystal, thereby presenting a possibility for further enhancement. Approach. In this study, we aimed to improve the timing performance of the dual-ended BGO Cherenkov TOF PET detector by capitalizing on the synergistic advantages of applying depth-of-interaction (DOI) information and crystal surface finishes or reflector properties. A dual-ended BGO detector was implemented using a 3 × 3 × 15 mm3 BGO crystal. Coincidence events were acquired against a 3 × 3 × 3 mm3 LYSO:Ce:Mg reference detector. The timing performance of the dual-ended BGO detectors was analyzed using conventionally proposed timestamp methods before and after DOI correction. Results. Through a DOI-based correction of photon transit time spread, we demonstrated a further improvement in the timing resolution of the BGO-based Cherenkov TOF PET detector utilizing a dual-ended detector configuration and adaptive arrival time pickoff. We achieved further improvements in timing resolution by correcting the offset spread induced by the fluctuation of timing signal rise time in the dual-ended detector. Significance. Although polishing the crystal surface was still favorable in terms of full-width-half-maximum value, incorporating DOI information from the unpolished crystal to compensate for photon travel time facilitated additional enhancement in the overall timing performance, thereby surpassing that achieved with the polished crystal.

Electrodynamic Model of Combustion Chamber With Initiated Subcritical Streamer Discharge

Various electrodynamic models of a combustion chamber with an initiated subcritical streamer discharge used to ignite a combustible air/fuel mixture are considered. To localize the discharge in the working chamber, initiators based on half-wave electromagnetic vibrators with resonant properties are applied. The dependencies of the structure of the electric field forming the discharge on the geometric parameters of the discharge initiator are obtained, and integration of the combustion chamber with the generator of microwave radiation is discussed. Calculations are performed for various orientations of the discharge initiator with respect to the optical axis of the chamber. Possibilities for further enhancement of the electric field at the poles of the initiator of a developed streamer discharge are discussed. The results obtained confirm the possibility of using subcritical streamer discharge in high-pressure combustion chambers. The ways of increasing the resulting electromagnetic field at the vibrator poles to form discharge with a developed streamer structure are determined. The results obtained are potentially important to study ignition and combustion of air/fuel mixtures induced by the subcritical streamer discharge.

Free-Spin Dominated Magnetocaloric Effect in Dense Gd3+ Double Perovskites

Frustrated lanthanide oxides with dense magnetic lattices are of fundamental interest for their potential in cryogenic refrigeration due to a large ground state entropy and suppressed ordering temperatures but can often be limited by short-range correlations. Here, we present examples of frustrated fcc oxides, Ba2GdSbO6 and Sr2GdSbO6, and the new site-disordered analogue Ca2GdSbO6 ([CaGd]A[CaSb]BO6), in which the magnetocaloric effect is influenced by minimal superexchange (J1 ∼ 10 mK). We report on the crystal structures using powder X-ray diffraction and the bulk magnetic properties through low-field susceptibility and isothermal magnetization measurements. The Gd compounds exhibit a magnetic entropy change of up to −15.8 J/K/molGd in a field of 7 T at 2 K, a 20% excess compared to the value of −13.0 J/K/molGd for a standard in magnetic refrigeration, Gd3Ga5O12. Heat capacity measurements indicate a lack of magnetic ordering down to 0.4 K for Ba2GdSbO6 and Sr2GdSbO6, suggesting cooling down through the liquid 4-He regime. A mean-field model is used to elucidate the role of primarily free-spin behavior in the magnetocaloric performance of these compounds in comparison to other top-performing Gd-based oxides. The chemical flexibility of the double perovskites raises the possibility of further enhancement of the magnetocaloric effect in the Gd3+fcc lattices.

Phasor Measurement Unit With Digital Inputs: Synchronization and Interoperability Issues

In recent years, the electrical substations are experiencing a rapid transition towards a fully digital measurement infrastructure, in terms of data acquisition, storage and processing. The IEC Std 61850-9-2 defines the data format, also known as Sampled Value (SV), to be employed by instrument transformers, merging units, and controller devices. In this scenario, it is reasonable to expect that also Phasor Measurement Units (PMUs) will be directly connected with digital instrument transformers and will be required to process directly the SV data stream. In this paper, we present the design and development of a stand-alone PMU based on digital inputs. The prototype has been characterized in terms of estimation accuracy and enriched with a novel functionality that allows for monitoring the time quality of the SV data stream. In this way, the device truly becomes an Intelligent Electronic Device (IED) that guarantees higher interoperability as well as a more robust management of sporadic synchronization issues. The proposed results confirm the potential of SV-based PMUs, and highlight the possibility of further enhancement for synchrophasor measurements based on digital inputs only.

Электродинамическая модель камеры сгорания, использующей инициированный подкритический стримерный разряд для поджигания топливной смеси

Various electrodynamic models of a combustion chamber, in which an initiated subcritical streamer discharge is used to ignite a combustible mixture, are considered. To localize the discharge in the working chamber, discharge initiators are used based on half-wave electromagnetic vibrators with resonant properties. The dependences of the structure of the electric fields that form the discharge on the geometric parameters of the discharge initiator are obtained on the basis of numerical calculations, and the issues of matching the chamber with the radiation generator are considered. Comparison of the calculation options for different positions of the initiator of the discharge in relation to the optical centreline of the camera. Possibilities for further enhancement of the field in the working zone at the poles of the microwave discharge initiator, which is required for the formation of discharges with a developed streamer structure at elevated gas pressures in the combustion chamber, are discussed. The ways of increasing the resulting electromagnetic field in the area of vibrators for the formation of discharges with a volumetric structure have been determined.

Electrodynamic model of combustion chamber using subcritical streamer discharge to ignite fuel mixture

Various electrodynamic models of a combustion chamber, in which an initiated subcritical streamer discharge is used to ignite a combustible mixture, are considered. To localize the discharge in the working chamber, discharge initiators are used based on half-wave electromagnetic vibrators with resonant properties. The dependences of the structure of the electric fields that form the discharge on the geometric parameters of the discharge initiator are obtained on the basis of numerical calculations, and the issues of matching the chamber with the radiation generator are considered. Comparison of the calculation options for different positions of the initiator of the discharge in relation to the optical centreline of the camera. Possibilities for further enhancement of the field in the working zone at the poles of the microwave discharge initiator, which is required for the formation of discharges with a developed streamer structure at elevated gas pressures in the combustion chamber, are discussed. The ways of increasing the resulting electromagnetic field in the area of vibrators for the formation of discharges with a volumetric structure have been determined. Keywords: microwave radiation, streamer discharge, electrodynamic model, plasma combustion, combustion chamber.

Structural vibration design of a pod structure including an optical system of a fighter aircraft

Structural vibration design of a pod structure including an optical system installed on a fighter aircraft is very significant in improving accuracy of targeting system to the target objects. To reduce and isolate the vibration generated during the flight, it is crucial to properly design the rubber mount between the pod and the aircraft. In this study, free vibration analysis of the pod is conducted through finite element analysis (FEA) and experiments. Correlations are performed with reasonably acceptable accuracy about the natural frequencies, mode shapes, and frequency response functions obtained by FEA and experiment. Then to optimize the structural dynamics of the pod, three variables are considered, which are mass of the dummies, the numbers of and positions of rubber mounts, and hyperelastic property of rubber mounts. In addition, the position of the pod on the fighter is analysed by FEM to estimate the possibility of further enhancement of its structural dynamics. Finally, forced vibration was undertaken using random signals of a shaker with 1Grms, 2Grms and 2.65Grms considering the test standard. It is found out that frequency responses of the pod are sensitive below 100 Hz to the values of the excitation signals. It is thus indeed to design appropriately the rubber mounts to improve structural dynamics of the pod, which results in the accuracy of targeting system.

Enhancement of thermal and mechanical properties of PMMA composites by incorporating mesoporous micro-silica and GO

The application of polymer-based composite materials is on the rise due to their enhanced thermal and mechanical properties compared to polymers themselves. For the first time in this study, the combination of graphene oxide (GO) and mesoporous micro-silica particles (with varying pore sizes) was used as fillers into PMMA matrices via in-situ bulk polymerization with ultrasonication. Two types of mesoporous silica were used at a fixed amount of 3 wt% with varying GO composition from 0.1 wt% to 1.2% to investigate the synergistic effect of GO and silica and increment of pore size of silica filler on the thermomechanical properties of the composites. The glass transition temperature Tg, thermal stability (the temperature at 10% and 60% weight loss) Td10 and Td60 of the same composite were increased by 21.5 °C, 46.5 °C, and 32.3 °C, respectively, compared to that of neat PMMA. Its tensile strength was increased remarkably by 329% compared with the PMMA. This work offers the possibility of further enhancement of thermal and mechanical properties of polymer-based composites by incorporating more than one filler with diverse properties.

Retrieval and Application of Rapid-Scan Atmospheric Motion Vectors Using an Infrared Channel of the INSAT-3DR Satellite

The advanced Indian meteorological satellite INSAT-3DR was configured in rapid-scan mode during the formation of tropical cyclone ‘Fani’ over the North Indian Ocean. This study is carried out to explore the possibility of further enhancement in atmospheric motion vectors (AMVs) to understand the extreme weather event using rapid-scan observations. A novel experiment has been performed to retrieve rapid-scan AMVs (RS-AMVs) with different tracer sizes at two different temporal scales (10 and 15 min) using the Thermal Infrared (TIR)-1 channel of the INSAT-3DR satellite. The RS-AMVs are able to capture small-scale variations of winds in rapid-scan mode, compared to AMVs retrieved by the operational INSAT-3D satellite available at 30-min intervals. Initial quality assessment of retrieved RS-AMVs is performed using winds from NCEP final analysis, ERA-5 reanalysis, and radiosonde observations. The number of wind vectors are enhanced significantly in RS-AMVs against operational AMVs from INSAT-3DR. An improvement of about 12% in RS-AMVs relative to operational 30-min INSAT-3D-retrieved AMVs has been achieved. Moreover, a sensitivity study has been performed using four-dimensional variational data assimilation experiments to understand the impact of newly retrieved RS-AMVs against operational INSAT-3D-retrieved AMVs for tropical cyclone Fani. Results suggest noteworthy improvements in track prediction when RS-AMVs are used for assimilation as compared to operational AMVs. The model-simulated surface wind structures are also compared with satellite observations for the radius of the maximum winds $$(R_{\max } )$$ and the maximum radial extent of surface winds.

Measuring performance of government-supported drug warehouses using DEA to improve quality of drug distribution

PurposeDrug warehouses (DWs) play a crucial role in drug distribution of government-supported healthcare supply chain as it controls both the cost and responsiveness of the logistics activities. The current study proposes a methodology using data envelopment analysis (DEA) to estimate the performance along different dimensions and was applied to 30 government-supported DWs.Design/methodology/approachThis study employs DEA to evaluate the performance and relative technical efficiency of DWs. In this research, four inputs and six outputs are identified based on intensive literature review and discussion with all stakeholders of DWs. The inputs are warehouse storage capacity, temperature-controlled storage capacity, number of skilled employees and operational cost, while the outputs are fill rate, number of generic drugs, volume of drugs, consumption points, inventory turns ratio and time efficiency.FindingsResults show that 30% DWs operate at the most productive scale size with 100% efficiency level while 47% DWs have a significant possibility for further enhancement in productive efficiency and 23% DWs should diminish their operational size to increase their productivity level. It was also found that achieving 100% operational productivity along warehouse space capacity needs significant effort, whereas other three inputs, namely temperature-controlled capacity, number of skilled employees and operational cost, require comparatively less effort. Similarly, it was observed that the performance along the fill rate and time efficiency is satisfactory, whereas the performance along other fours output variables (i.e. number of generic drugs, volume of drugs, consumption points and inventory turns ratio) needs to be improved.Practical implicationsThe findings offer insights on the inputs and outputs that significantly contribute to efficiencies so that inefficient DWs can focus on these factors.Originality/valueAlthough many issues related to DEA have been widely researched and reported, but no literature has been found for analysis of DWs in general and government-supported DWs specifically to find out efficiencies for supply chain performance improvement.

Influence of Processing Conditions on the Microstructure and Physical Properties in Infiltration Growth Processed Mixed REBCO Bulk Superconductors

In this paper, we investigated the effect of liquid phase (LP) source mass on crystal growth, structure, microstructure, and magnetic properties of infiltration growth processed (Gd, Dy)Ba2Cu3 $\text{O}_{{\rm{7}-\rm{x}}}$ ((Gd, Dy)BCO) bulk superconductors. The mixture of Er-123 + Ba3Cu5O8 (035) was chosen as the LP source and the ratio of 211: LP mass (wt%) was varied between 1:1 and 1:1.5. All samples were crystallized in ( 00l ) direction; however, the supply of excess liquids for (Gd, Dy)BCO sample exhibited nonsuperconducting phases. As LP mass increased, the nonsuperconducting inclusions had refined largely due to the availability of a sufficient amount of liquids for peritectic reaction. The 211: LP mass ratio of 1:1.4 was found to be the best relation. The onset of superconducting critical temperature was not influenced by the LP mass. However, the critical current density was gradually improved with the increase in LP mass. The possibilities for further enhancement of physical properties are discussed.

High-Responsivity Multilayer MoSe2 Phototransistors with Fast Response Time

There is a great interest in phototransistors based on transition metal dichalcogenides because of their interesting optoelectronic properties. However, most emphasis has been put on MoS2 and little attention has been given to MoSe2, which has higher optical absorbance. Here, we present a compelling case for multilayer MoSe2 phototransistors fabricated in a bottom-gate thin-film transistor configuration on SiO2/Si substrates. Under 650-nm-laser, our MoSe2 phototransistor exhibited the best performance among MoSe2 phototransistors in literature, including the highest responsivity (1.4 × 105 AW−1), the highest specific detectivity (5.5 × 1013 jones), and the fastest response time (1.7 ms). We also present a qualitative model to describe the device operation based on the combination of photoconductive and photogating effects. These results demonstrate the feasibility of achieving high performance in multilayer MoSe2 phototransistors, suggesting the possibility of further enhancement in the performance of MoSe2 phototransistors with proper device engineering.

Long-Distance Charge Carrier Funneling in Perovskite Nanowires Enabled by Built-in Halide Gradient.

The excellent charge carrier transportation in organolead halide perovskites is one major contributor to the high performance of many perovskite-based devices. There still exists a possibility for further enhancement of carrier transportation through nanoscale engineering, owing to the versatile wet-chemistry synthesis and processing of perovskites. Here we report the successful synthesis of bromide-gradient CH3NH3PbBrxI3-x single-crystalline nanowires (NWs) by a solid-to-solid ion exchange reaction starting from one end of pure CH3NH3PbI3 NWs, which was confirmed by local photoluminescence (PL) and energy dispersive X-ray spectroscopy (EDS) measurements. Due to the built-in halide gradient, the long-distance carrier transportation was driven by the energy funnel, rather than the spontaneous carrier diffusion. Indeed, local PL kinetics demonstrated effective charge carrier transportation only from the high-bandgap bromide-rich region to the low-bandgap iodine-rich region over a few micrometers. Therefore, these halide gradient NWs might find applications in various optoelectronic devices requiring long-distance and directional delivery of excitation energy.

Enhancement of the thermoelectric figure of merit in n-type Cu0.008Bi2Te2.7Se0.3 by using Nb doping

Doping with foreign atom has been shown to be an effective way to enhance the dimensionless figure of merit ZT of Bi2Te3-based thermoelectric raw materials. Herein, we report that doping with Nb is effective in enhancing the Seebeck coefficient of n-type Cu0.008Bi2Te2.7Se0.3 polycrystalline bulks. Considering compensation of the Seebeck coefficient due to decrease of the electrical conductivity in Nb-doped compositions, the absolute value of Seebeck coefficient rather increased benefiting from an enhancement of the density of states (DOS) effective mass m* from 1.09m 0 (Cu0.008Bi2Te2.7Se0.3) to 1.21m 0 − 1.27m 0 (Cu0.008Bi2−x Nb x Te2.7Se0.3) due to a DOS engineering effect. The values of ZT were 0.84 at 300 K and 0.86 at 320 K for Cu0.008Bi1.99Nb0.01Te2.7Se0.3. This compositional tuning approach highlights the possibility of further enhancement of ZT for n-type Bi2Te3-based compounds by using a combination of nanostructuring technologies to reduce the thermal conductivity.

Allergic manifestation by black gram (Vigna mungo) proteins in allergic patients, BALB/c mice and RBL-2H3 cells.

The prevalence of black gram (Vigna mungo) induced allergic reactions are reported from several parts of the world including Asia and Australia. But, a thorough exploration of the allergic reactions induced by black gram proteins is still lacking. Therefore, efforts have been made to explore black gram allergy using in vivo and in vitro approaches. In this study, Simulated Gastric Fluid (SGF) assay and IgE immunoblotting were carried out to identify clinically relevant allergens of black gram. BALB/c mice and RBL-2H3 cells were used for elucidation of allergenic reactions of black gram proteins. Further, this study was extended to screen black gram sensitive patients among nasobronchial allergic patients on the basis of clinical history, skin prick test (SPT), specific IgE levels and IgE immunoblotting. Enhanced levels of specific IgE, IgG1/IgG2a (p < 0.05), histamine (p < 0.05), clinical symptoms, pathological indications in the lungs, intestine and spleen were evident in black gram sensitized BALB/c mice. Moreover, the expression of Th2 cytokine transcripts and GATA-3/T-bet ratio was found enhanced in the treated group. In vitro studies on RBL-2H3 cells,showed increased release of β-hexosaminidase (p < 0.05), histamine (p < 0.05), cysteinyl leukotriene (p<0.05) and prostaglandin D2 (p < 0.05). Further, 8.5% of screened patients were found allergic to black gram and concomitant sensitization with other allergens has shown the possibility of further enhancement in allergenic problem. Conclusively, the present study suggested that black gram consumption may be responsible for inducing immediate type of allergic sensitization in susceptible subjects.

SiO2/carbon nitride composite materials: The role of surfaces for enhanced photocatalysis

The effect of SiO2 nanoparticles on carbon nitride (C3N4) photoactivity performance is described. The composite SiO2–C3N4 materials exhibit a higher activity in the photo degradation of RhB dye. A detailed analysis of the chemical and optical properties of the composite C3N4 materials shows that the photo activity increases with higher SiO2 concentration. We found out that the presence of SiO2 nanoparticles strongly affects the fluorescence intensity of the matrix and life time by the creation of new energy states for charge transfer within the C3N4. Furthermore, the use of SiO2 in the synthesis of C3N4 leads to new morphology with higher surface area which results in another, secondary improvement of C3N4 photoactivity. The effect of different surfaces within C3N4 on its chemical and electronic properties is discussed and a tentative mechanism is proposed. The utilization of SiO2 nanoparticles improves both photophysical and chemical properties of C3N4 and opens new possibilities for further enhancement of C3N4 catalytic properties by the formation of composites with many other materials.

The SUMER Data in the SOHO Archive

We have released an archive of all observational data of the VUV spectrometer Solar Ultraviolet Measurements of Emitted Radiation (SUMER) on SOHO that has been acquired until now. The operational phase started with 'first light' observations on 27 January 1996 and will end in 2014. Future data will be added to the archive when they become available. The archive consists of a set of raw data (Level 0) and a set of data that are processed and calibrated to the best knowledge we have today (Level 1). This communication describes step by step the data acquisition and processing that has been applied in an automated manner to build the archive. It summarizes the expertise and insights into the scientific use of SUMER spectra that has accumulated over the years. It also indicates possibilities for further enhancement of the data quality. With this article we intend to convey our own understanding of the instrument performance to the scientific community and to introduce the new, standard-FITS-format database.

Enhancing gold recovery from electronic waste via lixiviant metabolic engineering in Chromobacterium violaceum

Conventional leaching (extraction) methods for gold recovery from electronic waste involve the use of strong acids and pose considerable threat to the environment. The alternative use of bioleaching microbes for gold recovery is non-pollutive and relies on the secretion of a lixiviant or (bio)chemical such as cyanide for extraction of gold from electronic waste. However, widespread industrial use of bioleaching microbes has been constrained by the limited cyanogenic capabilities of lixiviant-producing microorganisms such as Chromobacterium violaceum. Here we show the construction of a metabolically-engineered strain of Chromobacterium violaceum that produces more (70%) cyanide lixiviant and recovers more than twice as much gold from electronic waste compared to wild-type bacteria. Comparative proteome analyses suggested the possibility of further enhancement in cyanogenesis through subsequent metabolic engineering. Our results demonstrated the utility of lixiviant metabolic engineering in the construction of enhanced bioleaching microbes for the bioleaching of precious metals from electronic waste.

Zero Resistivity above 150 K in HgBa2Ca2Cu3O8+δat High Pressure

We measured the electrical resistivity of a HgBa2Ca2Cu3O8+δ (Hg-1223) polycrystalline sample under high pressure. Owing to the improved sample quality and the nearly hydrostatic pressure, we successfully observed zero resistivity, which is the unambiguous signature of superconductivity, up to the unprecedented temperature of 153.0 K at 15 GPa. This temperature surpasses the previous records by more than 10 K. Referring to the experimental results, we established the exact pressure (\(P\)) vs superconducting transition temperature (\(T_{\text{c}}\)) relationship. \(T_{\text{c}}\) increases with \(P\) up to 15 GPa, suggesting the possibility of further enhancement of \(T_{\text{c}}\) at higher pressures.

High current proton source based on ECR discharge sustained by 37.5 GHz gyrotron radiation

Formation of hydrogen ion beams with high intensity and low transverse emittance is one of the key challenges in accelerator technology. Present work is devoted to experimental investigation of proton beam production from dense plasma (Ne > 1013 cm−3) of an ECR discharge sustained by 37.5 GHz, 100 kW gyrotron radiation at SMIS 37 facility at IAP RAS. The anticipated advantages of the SMIS 37 gasdynamic ion source over the current state-of-the-art proton source technology based on 2.45 GHz hydrogen discharges are described. Experimental result obtained with different extraction configurations i.e. single- and multi-aperture systems are presented. It was demonstrated that ultra bright proton beam with approximately 4.5 mA current and 0.03 π·mm·mrad normalized emittance can be produced with the single-aperture (1 mm in diameter) extraction, the corresponding brightness being 5 A/(π·mm·mrad)2. For production of high current beams a multi-aperture extractor was used resulting to a record of 200 mA / 1.1 π·mm·mrad normalized emittance proton beam. The species fraction i.e. the ratio of H+ to H2+ current was recorded to be > 90 % for all extraction systems. A possibility of further enhancement of the beam parameters by improvements of the extraction system and its power supply is discussed.