The Jamiołkowski Isomorphism and a Simplified Proof for the Correspondence Between Vectors Having Schmidt Number <Emphasis Type="Italic">k</Emphasis> and <Emphasis Type="Italic">k</Emphasis>-Positive Maps

Positive maps which are not completely positive are used in quantum information theory as witnesses for convex sets of states, in particular as entanglement witnesses and, more generally, as witnesses for states having Schmidt number not greater than k. Such maps and witnesses are related to k-positive maps, and their properties may be investigated by making use of the Jamiołkowski isomorphism. In this article we review the properties of this isomorphism, noting that there are actually two related mappings bearing that name. As a new result, we give a simplified proof for the correspondence between vectors having Schmidt number k and k-positive maps and thus for the Jamiołkowski criterion for complete positivity. Another consequence is a special case of a result by Choi, namely that k-positivity implies complete positivity, if k is the dimension of the smaller one of the Hilbert spaces on which the operators act.     

Fabrication of covalently bonded nanostructured thin films of epoxy resin and polydimethylsiloxane for oil adsorption

Thin films of architectures PEI(CNER_a/PDMS)_n, PEI(CNER_b/PDMS)_n, (PEI/CNER_b)_n and PEI(CNER_b/NH₂-MMT/PEI)_n have been fabricated via covalent layer-by-layer technique. Different film deposition parameters such as solvent type, polymer concentration, polymer ratio and dipping time have been optimized to achieve a uniform growth of layers. The effect of polymer concentration and dipping time on film thickness was also studied via ellipsometer. The optimized ratio of polymer concentration was 1:1 and 1:2 for PEI(CNER_a/PDMS)_n and PEI(CNER_b/PDMS)_n, respectively. AFM analysis indicated that the films were homogeneous while contact angle measurements revealed that although films were hydrophobic in nature yet they have wetting property due to the presence of hydroxyl groups formed during curing process. These epoxy-based multilayers have shown significant oil adsorption capacity. All the fabricated films qualify scotch tape test and were found resistant towards strong acids, bases and organic solvents.     

A Cloud-Manager-Based Re-Encryption Scheme for Mobile Users in Cloud Environment: a Hybrid Approach

Cloud computing is an emerging computing paradigm that offers on-demand, flexible, and elastic computational and storage services for the end-users. The small and medium-sized business organization having limited budget can enjoy the scalable services of the cloud. However, the migration of the organizational data on the cloud raises security and privacy issues. To keep the data confidential, the data should be encrypted using such cryptography method that provides fine-grained and efficient access for uploaded data without affecting the scalability of the system. In mobile cloud computing environment, the selected scheme should be computationally secure and must have capability for offloading computational intensive security operations on the cloud in a trusted mode due to the resource constraint mobile devices. The existing manager-based re-encryption and cloud-based re-encryption schemes are computationally secured and capable to offload the computationally intensive data access operations on the trusted entity/cloud. Despite the offloading of the data access operations in manager-based re-encryption and cloud-based re-encryption schemes, the mobile user still performs computationally intensive paring-based encryption and decryption operations using limited capabilities of mobile device. In this paper, we proposed Cloud-Manager-based Re-encryption Scheme (CMReS) that combines the characteristics of manager-based re-encryption and cloud-based re-encryption for providing the better security services with minimum processing burden on the mobile device. The experimental results indicate that the proposed cloud-manager-based re-encryption scheme shows significant improvement in turnaround time, energy consumption, and resources utilization on the mobile device as compared to existing re-encryption schemes.     

Incremental proxy re-encryption scheme for mobile cloud computing environment

Due to the limited computational capability of mobile devices, the research organization and academia are working on computationally secure schemes that have capability for offloading the computational intensive data access operations on the cloud/trusted entity for execution. Most of the existing security schemes, such as proxy re-encryption, manager-based re-encryption, and cloud-based re-encryption, are based on El-Gamal cryptosystem for offloading the computational intensive data access operation on the cloud/trusted entity. However, the resource hungry pairing-based cryptographic operations, such as encryption and decryption, are executed using the limited computational power of mobile device. Similarly, if the data owner wants to modify the encrypted file uploaded on the cloud storage, after modification the data owner must encrypt and upload the entire file on the cloud storage without considering the altered portion(s) of the file. In this paper, we have proposed an incremental version of proxy re-encryption scheme for improving the file modification operation and compared with the original version of the proxy re-encryption scheme on the basis of turnaround time, energy consumption, CPU utilization, and memory consumption while executing the security operations on mobile device. The incremental version of proxy re-encryption scheme shows significant improvement in results while performing file modification operations using limited processing capability of mobile devices.     

Pirax: framework for application piracy control in mobile cloud environment

Mobile cloud computing is an emerging technology that is gaining popularity as a means to extend the capabilities of resource-constrained mobile devices such as a smartphone. Mobile cloud computing requires specialized application development models that support computation offloading from a mobile device to the cloud. The computation offloading is performed by means of offloading application process, application component, entire application, or clone of the smartphone. The offloading of an entire application or clone of the smartphone to cloud may raise application piracy issues, which, unfortunately, have not been addressed in the existing literature. This paper presents a piracy control framework for mobile cloud environment, named Pirax, which prevents mobile applications from executing on unauthenticated devices and cloud resources. Pirax is formally verified using High Level Petri Nets, Satisfiability Modulo Theories Library and Z3 solver. Pirax is implemented on Android platform and analyzed from security and performance perspectives. The performance analysis results show that Pirax is lightweight and easy to integrate into existing mobile cloud application development models.     

Green and eco-friendly synthesis of cobalt-oxide nanoparticle: Characterization and photo-catalytic activity

Cobalt-oxide nanoparticles (NPs) were fabricated using Punica granatum peel extract from cobalt nitrate hexahydrate at low temperature. The synthesized cobalt-oxide NPs were characterized using X-ray powder diffraction, scanning electron microscopy, energy-dispersive X-ray, atomic force microscopy, fourier transform infrared spectroscopy and UV-visible techniques. The cobalt-oxide NPs were in highly uniform shape and size was in the size of 40–80 nm. Photo-catalytic activity (PCA) of the synthesized NPs was evaluated by degrading Remazol Brilliant Orange 3R (RBO 3R) dye and a degradation of 78.45% was achieved (dye conc. 150 mg/L) using 0.5 g cobalt-oxide NPs for 50 min irradiation time. In view of eco-benign and cost-effective nature, the present investigation revealed that P. granatum could be used for the synthesis of cobalt-oxide NPs for photo-catalytic applications.     

Optical measurements of nanoporous anodic alumina formed on Si using novel X-ray spectroscopy set up CLASSIX

We present X-ray spectroscopy measurements to investigate the chemistry and structure of nanoporous alumina using novel instrument CLASSIX [N.R.J. Poolton, B.M. Towlson, B. Hamilton, D.A. Evans, Nuclear Instruments and Methods in Physics Research B246 (2006) 445] (chemistry luminescence and structure of surfaces by micro-imaging X-ray absorption). X-ray excited optical luminescence (XEOL) measurements show that the porous anodic alumina (PAA) films obtained have blue emission band with a peak position at 2.63 eV (470 nm) which can be attributed to mixed emission from F and F⁺ centres. The L_Ш absorption edge of aluminium in porous anodic alumina has been observed at 76.64 eV that shows a chemical shift from pure aluminium.     

Ion implantation into aluminum and copper by a beam of carbon nanoparticles from regenerative sooting discharges

We present a new technique to generate light carbon nanoparticles from regenerative sooting discharges and its use for ion implantation on aluminum and copper surfaces at an energy of 40 keV. Films formed at fluences up to 3 × 10¹⁵ C⁺/cm² for aluminum and 10¹⁶ C⁺/cm² for copper are studied using Raman spectroscopy, X-ray diffraction and atomic force microscopy. Raman spectroscopy reveals the existence of graphite and diamond like structures in all samples. Precipitates of Al₄C₃ of rhombohedral and hexagonal types were found in the nanometer ranges from the X-ray diffraction pattern for aluminum samples and the probable formation of body-centered cubic diamond and hexagonal carbon in copper samples. The average grain sizes of Al₄C₃ were calculated ～40 nm for Al and ～35 nm for Cu. Mass spectra from a graphite hollow cathode duoplasmatron ion source are also presented. Atomic force microscopy images of a Cu sample also support the existence of 46 nm structures. Light carbon nanoparticles are readily available from the ion source in which a special carbonaceous environment creates regenerative soot. Support gas Ar produces more C₃ than Ne.     

Effect of temperature on the formation and dissolution of anodic oxide films on titanium in acid solutions

The effect of electrolyte and current density on the growth rate of the oxide film on titanium were studied by following the voltage-time characteristics. The barrier oxide grows to greater thickness at lower pH and higher current density. The growth of the oxide in acid medium is lowered by an increase in temperature. In 0.5n H₂SO₄ the oxide grows to greater thicknesses than that grown in 0.5n HCLO₄. This is due to a relatively higher rate of dissolution in HClO₄ during the oxide-growth/oxide-dissolution process during the anodization. The effect of temperature on the dissolution of the oxide previously grown to 12.5 V is followed in 0.5n H₂SO₄ by impedance and potential measurements. The oxide, which is of duplex nature, dissolves with a rate that increases with increasing temperature. The results indicate that the rate of dissolution of the outer layer is affected by temperature more than that of the inner layer, probably owing to higher porosity of the former. The heat of activation, -H, was estimated to be 110.5 kJ mol^–1.