Temperature and thickness dependence of tunneling anisotropic magnetoresistance in exchange-biased Py/IrMn/MgO/Ta stacks

Weinvestigate the thickness and temperature dependence of a series of Ni0.8Fe0.2/Ir0.2Mn0.8 bilayer samples with varying thickness ratio of the ferromagnet/antiferromagnet (tFM tAFM) in order to explore the exchange coupling strengths in tunneling anisotropic magnetoresistance (TAMR) devices. Specific values of tFM tAFM lead to four distinct scenarios with specific electric responses to moderate magnetic fields. The characteristic dependence of the measured TAMR signal on applied voltage allows us to confirm its persistence up to room temperature despite an overlapped contribution by a thermal magnetic noise

Ultrafast All-Polymer Paper-Based Batteries

Conducting polymers for battery applications have been subject to numerous investigations during the last two decades. However, the functional charging rates and the cycling stabilities have so far been found to be insufficient for practical applications. These shortcomings can, at least partially, be explained by the fact that thick layers of the conducting polymers have been used to obtain sufficient capacities of the batteries. In the present letter, we introduce a novel nanostructured high-surface area electrode material for energy storage applications composed of cellulose fibers of algal origin individually coated with a 50 nm thin layer of polypyrrole. Our results show the hitherto highest reported charge capacities and charging rates for an all polymer paper-based battery. The composite conductive paper material is shown to have a specific surface area of 80 m2 g-1 and batteries based on this material can be charged with currents as high as 600 mA cm-2 with only 6 % loss in capacity over 100 subsequent charge and discharge cycles. The aqueous-based batteries, which are entirely based on cellulose and polypyrrole and exhibit charge capacities between 25 and 33 mAh g-1 or 38-50 mAh g-1 per weight of the active material, open up new possibilities for the production of environmentally friendly, cost efficient, up-scalable and lightweight energy storage systems. There is currently a great interest in the development of thin, flexible, lightweight, and environmentally friendly batteries and supercapacitors.1 In this process, the preparation of novel redox polymer and electronically conducting polymer-base

Paintable Battery

If the components of a battery, including electrodes, separator, electrolyte and the current collectors can be designed as paints and applied sequentially to build a complete battery, on any arbitrary surface, it would have significant impact on the design, implementation and integration of energy storage devices. Here, we establish a paradigm change in battery assembly by fabricating rechargeable Li-ion batteries solely by multi-step spray painting of its components on a variety of materials such as metals, glass, glazed ceramics and flexible polymer substrates. We also demonstrate the possibility of interconnected modular spray painted battery units to be coupled to energy conversion devices such as solar cells, with possibilities of building standalone energy capture-storage hybrid devices in different configurations

Ciphertext-Policy Attribute Based Encryption Supporting Access Policy Update

Attribute-based encryption (ABE) allows one-to-many encryption with static access control. In many occasions, the access control policy must be updated and the original encryptor might be required to re-encrypt the message, which is impractical, since the encryptor might be unavailable. Unfortunately, to date the work in ABE does not consider this issue yet, and hence this hinders the adoption of ABE in practice. In this work, we consider how to efficiently update access policies in Ciphertext-policy Attribute-based Encryption (CP-ABE) systems without re-encryption. We introduce a new notion of CP-ABE supporting access policy update that captures the functionalities of attribute addition and revocation to access policies. We formalize the security requirements for this notion, and subsequently construct two provably secure CP-ABE schemes supporting AND-gate access policy with constant-size ciphertext for user decryption. The security of our schemes are proved under the Augmented Multi-sequences of Exponents Decisional Diffie-Hellman assumption

Synthesis of air‐stable, odorless thiophenol surrogates via Ni‐Catalyzed C−S cross‐coupling

Thiophenols are versatile synthetic intermediates whose practical appeal is marred by their air sensitivity, toxicity and extreme malodor. Herein we report an efficient catalytic method for the preparation of S-aryl isothiouronium salts, and demonstrate that these air-stable, odorless solids serve as user-friendly sources of thiophenols in synthesis. Diverse isothiouronium salts featuring synthetically useful functionality are readily accessible via nickelcatalyzed C-S cross-coupling of (hetero)aryl iodides and thiourea. Convenient, chromatography-free isolation of these salts is achieved via precipitation, allowing the methodology to be translated directly to large scales. Thiophenols are liberated from the corresponding isothiouronium salts upon treatment with a weak base, enabling an in situ release / S-functionalization strategy that entirely negates the need to isolate, purify or manipulate these noxious reagent

SMC complexes differentially compact mitotic chromosomes according to genomic context

Structural maintenance of chromosomes (SMC) protein complexes are key determinants of chromosome conformation. Using Hi-C and polymer modelling, we study how cohesin and condensin, two deeply conserved SMC complexes, organize chromosomes in the budding yeast Saccharomyces cerevisiae. The canonical role of cohesin is to co-align sister chromatids, while condensin generally compacts mitotic chromosomes. We find strikingly different roles for the two complexes in budding yeast mitosis. First, cohesin is responsible for compacting mitotic chromosome arms, independently of sister chromatid cohesion. Polymer simulations demonstrate that this role can be fully accounted for through cis-looping of chromatin. Second, condensin is generally dispensable for compaction along chromosome arms. Instead, it plays a targeted role compacting the rDNA proximal regions and promoting resolution of peri-centromeric regions. Our results argue that the conserved mechanism of SMC complexes is to form chromatin loops and that distinct SMC-dependent looping activities are selectively deployed to appropriately compact chromosomes