A Machine Learning Framework for Optimising File Distribution Across Multiple Cloud Storage Services

Storing data using a single cloud storage service may lead to several potential problems for the data owner. Such issues include service continuity, availability, performance, security, and the risk of vendor lock-in. A promising solution is to distribute the data across multiple cloud storage services , similarly to the manner in which data are distributed across multiple physical disk drives to achieve fault tolerance and to improve performance . However, the distinguishing characteristics of different cloud providers, in term of pricing schemes and service performance, make optimising the cost and performance across many cloud storage services at once a challenge. This research proposes a framework for automatically tuning the data distribution policies across multiple cloud storage services from the client side, based on file access patterns. The aim of this work is to explore the optimisation of both the average cost per gigabyte and the average service performance (mainly latency time) on multiple cloud storage services . To achieve these aims, two machine learning algorithms were used: 1. supervised learning to predict file access patterns. 2. reinforcement learning to learn the ideal file distribution parameters. File distribution over several cloud storage services . The framework was tested in a cloud storage services emulator, which emulated a real multiple-cloud storage services setting (such as Google Cloud Storage, Amazon S3, Microsoft Azure Storage, and Rack- Space file cloud) in terms of service performance and cost. In addition, the framework was tested in various settings of several cloud storage services. The results of testing the framework showed that the multiple cloud approach achieved an improvement of about 42% for cost and 76% for performance. These findings indicate that storing data in multiple clouds is a superior approach, compared with the commonly used uniform file distribution and compared with a heuristic distribution method

CaO impregnated highly porous honeycomb activated carbon from agriculture waste: symmetrical supercapacitor study

This study presents the electrochemical studies of activated carbon prepared from palm kernel shell (ACPKS), with CaO impregnation. The CaO is obtained from chicken eggshell waste to produce CaO/ACPKS, which shows highly porous honeycomb structure with homogeneous distribution of CaO nanoparticles (30–50 nm in size). The prepared materials are evaluated as supercapacitor electrodes by testing their electrochemical characteristics. A high specific capacitance value of 222 F g−1 at 0.025 A g−1 is obtained for CaO/ACPKS, which is around three times higher than that for ACPKS (76 F g−1). In addition, electrochemical impedance data show lower impedance for CaO/ACPKS. Lastly, a practical symmetrical supercapacitor is fabricated by CaO/ACPKS and its performance is discussed

One-step production of pyrene-1-boronic acid functionalized graphene for dopamine detection

A facile molecular wedging method is used to exfoliate graphite flakes into graphene sheets, with concurrent functionalization to form pyrene-1-boronic acid functionalized graphene (PBA/G). Different techniques are used to characterize the prepared materials such as field emission scanning electron microscope, energy dispersive X-ray analyzer, Raman, Fourier transformed infrared spectroscopy and fluorescence spectroscopy to evaluate their structural and morphological characteristics. The intercalation of PBA into graphite sheets, followed by exfoliation can be observed under the electron microscope. Elemental analyses show that the PBA acts more than intercalant, it is functionalized onto the graphene sheets upon exfoliation to form PBA/G. Raman analysis indicates PBA/G has a lower number of graphene layers as a result of successful exfoliation by PBA. Electrochemical impedance studies show that the PBA/G possesses high affinity for dopamine through the diol groups interaction, which renders it to have enhanced detection for dopamine

Magnetic Electrodeposition of the Hierarchical Cobalt Oxide Nanostructure from Spent Lithium-Ion Batteries: Its Application as a Supercapacitor Electrode

In this study, electrodeposition of cobalt oxide (Co3O4) from spent lithium-ion batteries is successfully enhanced by the magnetic field effect. In the presence of magnetic field, well-defined hierarchical Co3O4 nanostructures with higher electroactive surface area are formed during the electrodeposition process. Electrochemical analysis shows that the enhanced Co3O4 nanostructures exhibit excellent charge storage capabilities of 1273 F g–1 at 1 A g–1, approximately 4 times higher than the electrodeposited Co3O4 that is formed without magnetic field effect. It also reveals the high cycling stability of enhanced Co3O4 nanostructures, with 96% capacitance retention at 5000 charge discharge cycles. The results manifest the enhancement of Co3O4 recovery from spent lithium-ion batteries, which can be the potential electrode material for supercapacitor application

Ferrocene functionalized multi-walled carbon nanotubes as supercapacitor electrodes

Modified multi-walled carbon nanotubes (MWCNTs) functionalized by a redox-active ferrocene (Fc-MWCNTs) were successfully synthesized to enhance the electrochemical performance of MWCNTs for supercapacitor application. The ferrocene moieties were attached to the surface of MWCNTs via a thiourea linker with anions-interacting capability. The Fc-MWCNTs were characterized using XPS, FTIR, SEM, TGA, DTG, and XRF methods. The electrochemical performance details were investigated using cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy. The Fc-MWCNTs electrode showed excellent capacity retention (90.8% over 5000 cycles) and a specific capacitance of 50 F g−1 at 0.25 A g−1 that is several times higher as compared to the pristine MWCNTs. The fabricated Fc-MWCNTs is proposed to be a suitable and promising candidate for energy storage material. de

Dual-functional single stranded deoxyribonucleic acid for graphene

This study reports a one-step process to produce single-stranded deoxyribonucleic acid (ssDNA) functionalized reduced graphene oxide (ssDNA/rGO). The ssDNA acts as a reducing agent for the reduction of GO into rGO and simultaneously performs functionalization onto rGO, which is confirmed by spectroscopic and microscopic analyses. Such reduction capability is not being observed in double-stranded DNA (dsDNA). The high charge density of ssDNA on rGO is investigated for its application in electrochemical supercapacitor, and it is revealed that the ssDNA/rGO exhibits a specific capacitance of 129 F g−1 with high stability (92%) up to 10,000 cycles. The findings open the gateway to develop a biomolecule-based energy storage system

Structural and shielding properties of NiO/xCo3O4 nanocomposites synthesized by microwave irradiation method

In the present study, nanocomposites with different ratios of NiO and Co3O4 (x = 0.3, 0.5, and 0.7) have been prepared via microwave oven and characterized using XRD. FLUKA code has been used to estimate the values of the mass attenuation coefficient (μm) for all samples. From the measurement, we found that when the thickness of the samples increases, the gamma transmission values decrease. Besides, the μm values increase as the Co3O4 content increase from 0.3 to 0.7%. At selected photon energy, the HVL, TVL, and MFP values decrease with increasing Co3O4 concentrations. At low energies (0.1–0.5 MeV), the linear decreasing trend in MAC values indication that photoelectric effect (PEA) (∝1/E3.5) dominance over this region. Afterward, at medium energy regions (0.5–1.33 MeV), the decrements in MAC values are insignificant as the Compton scattering (CS) (∝1/E) phenomenon dominates. As a conclusion, CoNi3 has superior effectiveness as a shielding material. © 2020 The Author(s)The authors express their gratitude to the Deanship of Scientific Research at King Khalid University for funding this work through research groups program under grant number R.G.P. 2/33/41 and Universiti Putra Malaysia for the research and publication funding

Room temperature magnetic phase transition in an electrically-tuned van der Waals ferromagnet

Finding tunable van der Waals (vdW) ferromagnets that operate at above room temperature is an important research focus in physics and materials science. Most vdW magnets are only intrinsically magnetic far below room temperature and magnetism with square-shaped hysteresis at room-temperature has yet to be observed. Here, we report magnetism in a quasi-2D magnet Cr1.2Te2 observed at room temperature (290 K). This magnetism was tuned via a protonic gate with an electron doping concentration up to 3.8 * 10^21 cm^-3. We observed non-monotonic evolutions in both coercivity and anomalous Hall resistivity. Under increased electron doping, the coercivities and anomalous Hall effects (AHEs) vanished, indicating a doping-induced magnetic phase transition. This occurred up to room temperature. DFT calculations showed the formation of an antiferromagnetic (AFM) phase caused by the intercalation of protons which induced significant electron doping in the Cr1.2Te2. The tunability of the magnetic properties and phase in room temperature magnetic vdW Cr1.2Te2 is a significant step towards practical spintronic devices.Comment: 18 pages, 4 figure

Avoidable emergency department visits among palliative care cancer patients: novel insights from Saudi Arabia and the Middle East

Background Several studies emerging from developed countries have highlighted a significant number of potentially avoidable emergency department (ED) visits by cancer patients during the end-of-life period. However, there is a paucity of information from developing nations regarding palliative care practices and the utilization of the ED by palliative care patients. Herein, we aim to characterize ED admissions among patients receiving palliative care at our tertiary center in Saudi Arabia. Methods This is a retrospective, cross-sectional study evaluating ED visits amongst adult patients with advanced cancer who were receiving treatment under the palliative care department. This study took place over a period of 12 months from July 2021 through to July 2022. Three palliative care specialist physicians independently and blindly reviewed each patient’s ED visits and determined whether the visit was avoidable or unavoidable. Results A total of 243 patients were included in the final analysis, of which 189 (78.1%) patients had unavoidable visits and 53 (21.9%) patient visits were classified as avoidable. A significantly higher proportion of breast cancer patients presented with unavoidable admissions (14.3% vs. 3.8%, P = 0.037) compared to other cancer types. The incidence of dyspnea (23.8% vs. 5.7%, P < 0.001) and fevers/chills (23.3% vs. 5.7%, P = 0.005) was significantly higher in patients with unavoidable visits. Patients with avoidable visits had a significantly greater proportion of visits for dehydration (13.2% vs. 2.1%, P = 0.002). Notably, although hospital stay was significantly longer in the unavoidable group (P = 0.045), mortality for palliative care patients—regardless of whether their ED visit was avoidable or unavoidable—was not statistically different (P=-0.069). Conclusion To our knowledge, this is the largest and most comprehensive study from Saudi Arabia and the Middle East providing insights into the utilization of palliative care services in the region and the propensity of advanced cancer patients towards visiting the ED. Future studies ought to explore interventions to reduce the frequency of avoidable ED visits

A robust computational investigation on C₆₀ fullerene nanostructure as a novel sensor to detect SCNˉ

This study explored on the adsorption properties and electronic structure of SCNˉ via density functional theory analysis on the exterior surfaces of C₆₀ and CNTs using B3LYP functional and 6-31G** standard basis set. Then adsorption of SCNˉ through nitrogen atom on the C60 fullerene is electrostatic (₋48.02 kJ molˉ1) in comparison with the C₅₉Al fullerene that shows covalently attached to fullerene surface (₋389.10 kJ mol̄ˉ1). Our calculations demonstrate that the SCNˉ adsorption on the pristine and Al-doped single-walled CNTs are ₋173.13 and ₋334.43 kJ molˉ1, indicating that the SCNˉ can be chemically bonded on the surface of Al-doped CNTs. Moreover, the adsorption of SCNˉ on the C₆₀ surface is weaker in comparison with C₅₉B, C₅₉Al, and C₅₉Ga systems but its electronic sensitivity improved in comparison with those of C₅₉B, C₅₉Al, and C₅₉Ga fullerenes. The evaluation of adsorption energy, energy gap, and dipole moment demonstrates that the pure fullerene can be exploited in the design practice as an SCNˉ sensor and C₅₉Al can be used for SCNˉ removal application