Abstract
Spinning black holes in the centres of galaxies can release powerful magnetised jets. When the jets are observed at angles of less than a few degrees to the line-of-sight, they are called ...blazars, showing variable non-thermal emission across the electromagnetic spectrum from radio waves to gamma rays. It is commonly believed that shock waves are responsible for this dissipation of jet energy. Here we show that gamma-ray observations of the blazar 3C 279 with the space-borne telescope Fermi-LAT reveal a characteristic peak-in-peak variability pattern on time scales of minutes expected if the particle acceleration is instead due to relativistic magnetic reconnection. The absence of gamma-ray pair attenuation shows that particle acceleration takes place at a distance of ten thousand gravitational radii from the black hole where the fluid dynamical kink instability drives plasma turbulence.
Functionalized multiwalled carbon nanotubes (CNTs) are coated with a 4–5 nm thin layer of V2O5 by controlled hydrolysis of vanadium alkoxide. The resulting V2O5/CNT composite has been investigated ...for electrochemical activity with lithium ion, and the capacity value shows both faradaic and capacitive (nonfaradaic) contributions. At high rate (1 C), the capacitive behavior dominates the intercalation as 2/3 of the overall capacity value out of 2700 C/g is capacitive, while the remaining is due to Li-ion intercalation. These numbers are in agreement with the Trasatti plots and are corroborated by X-ray photoelectron spectroscopy (XPS) studies on the V2O5/CNTs electrode, which show 85% of vanadium in the +4 oxidation state after the discharge at 1 C rate. The cumulative high-capacity value is attributed to the unique property of the nano V2O5/CNTs composite, which provides a short diffusion path for Li+-ions and an easy access to vanadium redox centers besides the high conductivity of CNTs. The composite architecture exhibits both high power density and high energy density, stressing the benefits of using carbon substrates to design high performance supercapacitor electrodes.
Solar Photovoltaic (PV) cells can absorb up to 80% of the incident solar radiation obtained from the solar band, however, only a small amount of this absorbed incident energy is transformed into ...electricity depending on the conversion efficiency of the PV cells and part of remainder energy increases the temperature of PV cell. High solar radiation and ambient temperature lead to an elevated photovoltaic cell operating temperature, which affects its lifespan and power output adversely. Number of techniques have been attempted to maintain the temperature of photovoltaic cells close to their nominal operating value. In the present review various cooling techniques such as natural and forced air cooling, hydraulic cooling, heat pipe cooling, cooling with phase change materials and thermoelectric cooling of PV panels are discussed at length. It is important to note that, though cooling techniques are highly needed to regulate the PV module temperature, especially for mega installations, these should be economically viable too.
In recent years the thermal energy storage applications with phase change materials have attracted wide interest. This has motivated a number of R&D efforts to develop novel materials and design new ...applications based on PCM. The efficient design of the new applications majorly depends on the quality of PCM employed. Numbers of reviews, reports have been written to compile the wide range of PCMs made available for different applications. This paper focuses on the development of next generation PCMs through the enhancement of thermophysical properties namely thermal conductivity, latent heat of fusion and sensible heat. The paper presents a detailed review of the research updates in this direction so as to produce PCMs with enhanced efficiency in terms of thermal energy storage and efficient heat transfer.
•Nanotechnology can be very helpful in developing thermal energy storage materials.•Thermal modeling of nano particle with phase change materials (PCM) is carried out.•These studies are crucial to ...enhance the thermal conductivity of PCM.•Graphene used as a nano particle, dispersed in CaCl2.6H2O, Capric acid and n-octadecane as PCM.
The thermal conductivity of commonly used phase change materials (PCM) for thermal energy storage (TES), such as, fatty acids, paraffin etc., is relatively poor, which is one of the main drawbacks for limiting their utility. In the recent past, few attempts have been made to enhance the thermal conductivity of PCM by mixing different additives in the appropriate amount. Graphene nanoparticles, having higher thermal conductivity may be a potential candidate for the same, when mixed appropriately with different PCM. In present study authors have carried out the numerical investigation for the melting of graphene nano-particles dispersed PCM filled in an aluminum square cavity heated from one side. In this work, the graphene nanoparticles are mixed in three different volumetric ratios (1%, 3%, and 5%), with three different commonly used categories of organic, inorganic and paraffin PCM (namely, Capric Acid, CaCl2·6H2O, and n-octadecane) to see the effect on melting of composite PCM developed. The resulting transient isotherms, velocity fields, and melting front and melt fractions thus have been deliberated in detail. These results clearly indicate that the addition of graphene nanoparticles increases melting rate but can also hamper the convection heat transfer within large cavities. The study also shows that such enhanced PCM can be effectively used for different TES applications in different fields. The prediction of temperature variation and rate of melting or solidification may be found useful especially for designing such TES devices.
•Numerical investigation of building brick containing phase change materials has been carried out.•The effect of various PCM on heat transfer in building brick has been investigated.•The addition of ...phase change materials reduced heat transfer in building brick.
The present study deals with the thermal analysis of building bricks containing phase change materials (PCM) when subjected to ambient weather conditions such as solar radiation and ambient temperature. Thermal modelling of building bricks containing PCM has been carried out to utilise the high latent heat of fusion for indoor comfort in buildings. In the thermal model presented in this paper, the PCM is filled in the cylindrical cavity of the bricks. The two-dimensional numerical study has been carried out using finite element analysis method considering heat and mass transfer in the PCM. The effectiveness of PCM in the building bricks has been evaluated by comparing the three different cases - the normal bricks, bricks with air filled in the cylindrical cavity and bricks with PCM filled in the cylindrical cavity. Additionally, the study has also been carried out considering different PCMs, with a varying quantity of single PCM as well as multiple PCM. The obtained results indicate that the Capric acid is more effective PCM in comparison to the Paraffin and RT-25. The maximum heat flux reduction is found to be 8.31% with Capric acid filled in three cylindrical cavities. From the present study, it is also evident that the application of PCM in building brick could be an effective technique for passive thermal control of buildings.
•IoT based architecture for smart irrigation using field sensors and weather forecast.•Machine-learning based Soil moisture prediction algorithm with higher accuracy.•Smart irrigation scheduling ...algorithm using predicted soil moisture and rain forecast.
The scarcity of clean water resources around the globe has generated a need for their optimum utilization. Internet of Things (IoT) solutions, based on the application specific sensors’ data acquisition and intelligent processing, are bridging the gaps between the cyber and physical worlds. IoT based smart irrigation management systems can help in achieving optimum water-resource utilization in the precision farming landscape. This paper presents an open-source technology based smart system to predict the irrigation requirements of a field using the sensing of ground parameter like soil moisture, soil temperature, and environmental conditions along with the weather forecast data from the Internet. The sensing nodes, involved in the ground and environmental sensing, consider soil moisture, soil temperature, air temperature, Ultraviolet (UV) light radiation, and relative humidity of the crop field. The intelligence of the proposed system is based on a smart algorithm, which considers sensed data along with the weather forecast parameters like precipitation, air temperature, humidity, and UV for the near future. The complete system has been developed and deployed on a pilot scale, where the sensor node data is wirelessly collected over the cloud using web-services and a web-based information visualization and decision support system provides the real-time information insights based on the analysis of sensors data and weather forecast data. The system has a provision for a closed-loop control of the water supply to realize a fully autonomous irrigation scheme. The paper describes the system and discusses in detail the information processing results of three weeks data based on the proposed algorithm. The system is fully functional and the prediction results are very encouraging.
Abstract
Blocking temperature (θ
B
) holds utmost significance in magnetic devices. A novel approach to ascertain the θ
B
for bulk materials has been propounded. The θ
B
has been correlated with the ...magnetic entropy change (ΔS) during zero-field cooled (ZFC) and field cooled (FC) magnetization. The values of ΔS have been calculated in µ
B
/f.u.K. The θ
B
has been investigated for two distinct cases – (I) with ZFC magnetization reversal and (II) without ZFC magnetisation reversal. Based on the reported experimental approach, a novel definition of θ
B
has been propounded for bulk materials. The combined analysis of ZFC and FC magnetization behaviour provides a better approximation of θ
B
for bulk materials.
How the genomic landscape of a tumor shapes and is shaped by anti-tumor immunity has not been systematically explored. Using large-scale genomic data sets of solid tissue tumor biopsies, we ...quantified the cytolytic activity of the local immune infiltrate and identified associated properties across 18 tumor types. The number of predicted MHC Class I-associated neoantigens was correlated with cytolytic activity and was lower than expected in colorectal and other tumors, suggesting immune-mediated elimination. We identified recurrently mutated genes that showed positive association with cytolytic activity, including beta-2-microglobulin (B2M), HLA-A, -B and -C and Caspase 8 (CASP8), highlighting loss of antigen presentation and blockade of extrinsic apoptosis as key strategies of resistance to cytolytic activity. Genetic amplifications were also associated with high cytolytic activity, including immunosuppressive factors such as PDL1/2 and ALOX12B/15B. Our genetic findings thus provide evidence for immunoediting in tumors and uncover mechanisms of tumor-intrinsic resistance to cytolytic activity.
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•Analysis of 18 TCGA tumor types shows genomic correlates of immune cytolytic activity•Multiple tumor types demonstrate strong link between mutation load and local immunity•Infiltrated tumors are enriched for probable escape lesions affecting CASP8, HLA, B2M•Copy number changes in suppressive PDL1, ALOX12B/15B are also tied to immune activity
A systematic survey of 18 TCGA tumor types reveals how the mutational load of tumors shapes and is shaped by the ongoing immune response, identifying sequence changes and copy number amplifications that favor immune evasion, as well as point mutations that are associated with high cytolytic activity and can be explored as targets for immunotherapy.
Clonal evolution is a key feature of cancer progression and relapse. We studied intratumoral heterogeneity in 149 chronic lymphocytic leukemia (CLL) cases by integrating whole-exome sequence and copy ...number to measure the fraction of cancer cells harboring each somatic mutation. We identified driver mutations as predominantly clonal (e.g., MYD88, trisomy 12, and del(13q)) or subclonal (e.g., SF3B1 and TP53), corresponding to earlier and later events in CLL evolution. We sampled leukemia cells from 18 patients at two time points. Ten of twelve CLL cases treated with chemotherapy (but only one of six without treatment) underwent clonal evolution, predominantly involving subclones with driver mutations (e.g., SF3B1 and TP53) that expanded over time. Furthermore, presence of a subclonal driver mutation was an independent risk factor for rapid disease progression. Our study thus uncovers patterns of clonal evolution in CLL, providing insights into its stepwise transformation, and links the presence of subclones with adverse clinical outcomes.
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► Whole-exome analysis of clonal heterogeneity in 149 chronic lymphocytic leukemias ► Earlier and later mutations in the temporal evolution of CLL are identified ► Clonal evolution is commonly seen with treatment, typically in a branched pattern ► A subclonal driver in a pretreatment sample is associated with adverse outcome
The intratumoral heterogeneity in 149 chronic lymphocytic leukemia (CLL) cases was evaluated by whole-exome sequencing. The evolutionary patterns of distinct clones enabled a temporal ordering of mutations in CLL, revealed the association of clonal evolution with chemotherapy, and linked the presence of subclonal driver mutations with adverse clinical outcomes.
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