Improved lithium cyclability and storage in a multi-sized pore (''differential spacers'') mesoporous SnO2

A wide pore distribution mesoporous morphology stabilizes SnO2 structure during lithium insertion and removal and in the process remarkably enhances the lithium storage and cyclability.

On the performance of stabilized ?-nickel hydroxide as a nickel-positive electrode in alkaline storage batteries

The internal resistance of a stabilized alpha-nickel hydroxide electrode is found to be lower than that of a beta-nickel hydroxide electrode as shown from studies of the open-circuit potential-time transients at all states-of-charge. Nevertheless, the self-discharge rates of the former is higher. Gasometric studies reveal that the charging efficiency of the alpha-nickel hydroxide electrode is higher than that of the beta-nickel hydroxide electrode.

Advances in storage batteries

Over the years, new power requirements for telecommunication, space, automotive and traction applications have arisen which need to be met. Although lead-acid and nickel-cadmium storage batteries continue to be the work horses with limited advances, associated environmental hazards and recycling are still the issues to be resolved. As a result, lead-acid and nickel-cadmium storage batteries have declined in importance whilst nickel-metal hydride and lithium secondary batteries with superior performances have shown greater acceptability in newer applications. These developments are reflected in this article.

Influence of cadmium on lipid peroxidation and antioxidant enzymes in isolated rat hepatocytes

Cadmium (Cd) influences lipid peroxidation (LPO) by enhancing peroxidation of membrane lipids and by disturbing the antioxidant system of cells. In isolated rat hepatocytes, LPO was observed in cells incubated with Cd (50-250 mu M) for various time periods up to 90 min. The antioxidant enzymes such as superoxide dismutase (SOD) and catalase (CAT) were inhibited along with depletion of glutathione (GSH) in hepatocytes treated with Cd. The results show that Cd influences LPO in rat hepatocytes due to decrease in antioxidant status.

Characterization of alkyl chain conformation in an intercalated cationic lipid bilayer by IR spectroscopy

A structural analysis of alkyl chain conformation of an intercalated cationic lipid bilayer is described. Dialkyl dimethylammonium ions (di-C(n)DA) were ion exchanged into the galleries of layered cadmium thiophosphate to give Cd0.83PS3(di-C(n)DA)(0.34). The grafting density and interlayer expansions were identical to those for the intercalated single chain alkyl trimethylammonium (C(n)TA) bilayers. The increased methylene chain density in the galleries, however, forces the intercalated lipid to adopt a more trans ordered structure. Progression bands arising from the coupling of vibrational modes of trans methylene units are used to establish the extent of trans registry. Two types of ordered structures of the intercalated cationic lipid may be distinguished. One in which both alkyl chains adopt an all-trans geometry, and one in which the methylene bond adjacent to the headgroup on one of the alkyl chains is gauche. The latter structure is typically found in the crystalline state of these cationic lipids. The concentrations of the two structures were determined from the ratio of the intensities of the progression bands and were found to remain unchanged with temperature.

Explicit codes uniformly reducing repair bandwidth in distributed storage

A distributed storage setting is considered where a file of size B is to be stored across n storage nodes. A data collector should be able to reconstruct the entire data by downloading the symbols stored in any k nodes. When a node fails, it is replaced by a new node by downloading data from some of the existing nodes. The amount of download is termed as repair bandwidth. One way to implement such a system is to store one fragment of an (n, k) MDS code in each node, in which case the repair bandwidth is B. Since repair of a failed node consumes network bandwidth, codes reducing repair bandwidth are of great interest. Most of the recent work in this area focuses on reducing the repair bandwidth of a set of k nodes which store the data in uncoded form, while the reduction in the repair bandwidth of the remaining nodes is only marginal. In this paper, we present an explicit code which reduces the repair bandwidth for all the nodes to approximately B/2. To the best of our knowledge, this is the first explicit code which reduces the repair bandwidth of all the nodes for all feasible values of the system parameters.

Explicit codes minimizing repair bandwidth for distributed storage

We consider the problem of minimizing the bandwidth required to repair a failed node when data is stored across n nodes in a distributed manner, so as to facilitate reconstruction of the entire data by connecting to any k out of the n nodes. We provide explicit and optimal constructions which permit exact replication of a failed systematic node.

Thermal Lipid Order−Disorder Transitions in Mixtures of Cationic Cholesteryl Lipid Analogues and Dipalmitoyl Phosphatidylcholine Membranes

Two types of cationic cholesteryl amphiphiles, one where the headgroup is attached to the steroid by an ester linkage and the second by an ether linkage, were synthesized. A third type of cholesteryl lipid bearing an oligoethylene glycol segment was also prepared. Each of these synthetic lipids generated vesicle-like aggregates with closed inner aqueous compartments from their aqueous suspensions. We examined their interaction with L-α-dipalmitoyl phosphatidylcholine (DPPC) membranes using fluorescence anisotropy, transmission electron microscopy (TEM), and differential scanning calorimetry (DSC). When included in membranes, the synthetic cholesteryl lipids were found to quench the chain motion of the acyl chains of DPPC. This suggests that these cationic cholesteryl derivatives act as filler molecules despite modification at the headgroup level from the molecular structure of natural cholesterol. Careful analyses of DSC and fluorescence anisotropy data suggest that the nature of perturbation induced by each of these cationic cholesterol derivatives is dependent on the details of their molecular structure and provides significant information on the nature of interaction of these derivatives with phospholipid molecules. In general, amphiphiles that support structured water at the interfacial region tend to rigidify the fluid phase more than others. Importantly, these cholesteryl amphiphiles behave less like cholesterol in that their incorporation in DPPC not only abolishes the phase transition but also depresses the phase transition temperature.

Calcium-Decorated Carbyne Networks as Hydrogen Storage Media

Among the carbon allotropes, carbyne chains appear outstandingly accessible for sorption and very light. Hydrogen adsorption on calcium-decorated carbyne chain was studied using ab initio density functional calculations. The estimation of surface area of carbyne gives the value four times larger than that of graphene, which makes carbyne attractive as a storage scaffold medium. Furthermore, calculations show that a Ca-decorated carbyne can adsorb up to 6 H(2) molecules per Ca atom with a binding energy of similar to 0.2 eV, desirable for reversible storage, and the hydrogen storage capacity can exceed similar to 8 wt %. Unlike recently reported transition metal-decorated carbon nanostructures, which suffer from the metal clustering diminishing the storage capacity, the clustering of Ca atoms on carbyne is energetically unfavorable. Thermodynamics of adsorption of H(2) molecules on the Ca atom was also investigated using equilibrium grand partition function.

Synthesis and characterization of novel cationic lipid and cholesterol-coated gold nanoparticles and their interactions with dipalmitoylphosphatidylcholine membranes

Novel gold nanoparticles bearing cationic single-chain, double-chain, and cholesterol based amphiphilic units have been synthesized. These nanoparticles represent size-stable entities in which various cationic lipids have been immobilized through their thiol group onto the gold nanoparticle core. The resulting colloids have been characterized by UV-vis, (1)H NMR, FT-IR spectroscopy, and transmission electron microscopy. The average size of the resultant nanoparticles could be controlled by the relative bulkiness of the capping agent. Thus, the average diameters of the nanoparticles formed from the cationic single-chain, double-chain, and cholesterol based thiolate-coated materials were 5.9,2.9, and 2.04 nm, respectively. We also examined the interaction of these cationic gold nanoparticles with vesicular membranes generated from dipalmitoylphosphatidylcholine (DPPC) lipid suspensions. Nanoparticle doped DPPC vesicular suspensions displayed a characteristic surface plasmon band in their UV-vis spectra. Inclusion of nanoparticles in vesicular suspensions led to increases in the aggregate diameters, as evidenced from dynamic light scattering. Differential scanning calorimetric examination indicated that incorporation of single-chain, double-chain, and cholesteryl-linked cationic nanoparticles exert variable effects on the DPPC melting transitions. While increased doping of single-chain nanoparticles in DPPC resulted in the phases that melt at higher temperatures, inclusion of an incremental amount of double-chain nanoparticles caused the lowering of the melting temperature of DPPC. On the other hand, the cationic cholesteryl nanoparticle interacted with DPPC in membranes in a manner somewhat analogous to that of cholesterol itself and caused broadening of the DPPC melting transition.

Interference Alignment as a Tool in Network Coding as Applied to Distributed Storage

In this paper, we outline an approach to the task of designing network codes in a non-multicast setting. Our approach makes use of the concept of interference alignment. As an example, we consider the distributed storage problem where the data is stored across the network in n nodes and where a data collector can recover the data by connecting to any k of the n nodes and where furthermore, upon failure of a node, a new node can replicate the data stored in the failed node while minimizing the repair bandwidth.

Explicit Codes Uniformly Reducing Repair Bandwidth in Distributed Storage

A distributed storage setting is considered where a file of size B is to be stored across n storage nodes. A data collector should be able to reconstruct the entire data by downloading the symbols stored in any k nodes. When a node fails, it is replaced by a new node by downloading data from some of the existing nodes. The amount of download is termed as repair bandwidth. One way to implement such a system is to store one fragment of an (n, k) MDS code in each node, in which case the repair bandwidth is B. Since repair of a failed node consumes network bandwidth, codes reducing repair bandwidth are of great interest. Most of the recent work in this area focuses on reducing the repair bandwidth of a set of k nodes which store the data in uncoded form, while the reduction in the repair bandwidth of the remaining nodes is only marginal. In this paper, we present an explicit code which reduces the repair bandwidth for all the nodes to approximately B/2. To the best of our knowledge, this is the first explicit code which reduces the repair bandwidth of all the nodes for all feasible values of the system parameters.