Sustainable Synthesis of Co@NC Core Shell Nanostructures from Metal Organic Frameworks via Mechanochemical Coordination Self‐Assembly: An Efficient Electrocatalyst for Oxygen Reduction Reaction

Herein, a new type of cobalt encapsulated nitrogen‐doped carbon (Co@NC) nanostructure employing Zn_xCo_1?x(C₃H₄N₂) metal–organic framework (MOF) as precursor is developed, by a simple, ecofriendly, solvent‐free approach that utilizes a mechanochemical coordination self‐assembly strategy. Possible evolution of Zn_xCo_1?x(C₃H₄N₂) MOF structures and their conversion to Co@NC nanostructures is established from an X‐ray diffraction technique and transmission electron microscopy analysis, which reveal that MOF‐derived Co@NC core–shell nanostructures are well ordered and highly crystalline in nature. Co@NC–MOF core–shell nanostructures show excellent catalytic activity for the oxygen reduction reaction (ORR), with onset potential of 0.97 V and half‐wave potential of 0.88 V versus relative hydrogen electrode in alkaline electrolyte, and excellent durability with zero degradation after 5000 potential cycles; whereas under similar experimental conditions, the commonly utilized Pt/C electrocatalyst degrades. The Co@NC–MOF electrocatalyst also shows excellent tolerance to methanol, unlike the Pt/C electrocatalyst. X‐ray photoelectron spectroscopy (XPS) analysis shows the presence of ORR active pyridinic‐N and graphitic‐N species, along with CoN_x? C_y and Co? N_x ORR active (M–N–C) sites. Enhanced electron transfer kinetics from nitrogen‐doped carbon shell to core Co nanoparticles, the existence of M–N–C active sites, and protective NC shells are responsible for high ORR activity and durability of the Co@NC–MOF electrocatalyst.     

Prioritization of satellite-derived potential fishery grounds: an analytical hierarchical approach-based model using spatial and non-spatial data

Forecast of potential fishing grounds can save considerable amounts of fuel and time involved in marine fishing operations, making the operation more profitable. This study investigates the prospects of using a decision support system for forecasting potential fishery zones and prioritizing them according to profitability using multi-criteria analysis. Ocean Colour Monitor-derived chlorophyll concentration and National Oceanic and Atmospheric Administration Advanced Very High Resolution Radiometer-derived sea surface temperature maps were integrated to demarcate the potential fishery zones (PFZs). QuickSCAT (NASA) scatterometer wind data obtained from the global 25 km × 25 km gridded dataset were used for updating the locations of PFZ features. An analytical hierarchy process-based prioritization model, which considers different parameters favouring a targeted species, distance to the zone and historical catch per unit effort as the major decision-making parameters, was used to rank the zones based on feasibility. A software package was developed incorporating the above-mentioned functionalities for automatic data processing and PFZ map generation.     

A SAS-based solution to evaluate study design efficiency of phase I pediatric oncology trials via discrete event simulation

Previous exploration of oncology study design efficiency has focused on Markov processes alone (probability-based events) without consideration for time dependencies. Barriers to study completion include time delays associated with patient accrual, inevaluability (IE), time to dose limiting toxicities (DLT) and administrative and review time. Discrete event simulation (DES) can incorporate probability-based assignment of DLT and IE frequency, correlated with cohort in the case of DLT, with time-based events defined by stochastic relationships. A SAS-based solution to examine study efficiency metrics and evaluate design modifications that would improve study efficiency is presented. Virtual patients are simulated with attributes defined from prior distributions of relevant patient characteristics. Study population datasets are read into SAS macros which select patients and enroll them into a study based on the specific design criteria if the study is open to enrollment. Waiting times, arrival times and time to study events are also sampled from prior distributions; post-processing of study simulations is provided within the decision macros and compared across designs in a separate post-processing algorithm. This solution is examined via comparison of the standard 3 + 3 decision rule relative to the “rolling 6” design, a newly proposed enrollment strategy for the phase I pediatric oncology setting.     

Studies on Aluminum Agglomeration and Combustion in Catalyzed Composite Propellants

Combustion, Explosion, and Shock Waves - Composite propellants are tested using the quench particle collection bomb (QPCB) for the pressure ranging from 2 to 8 MPa to estimate the particle...     

Modified RED gateways under bursty traffic

We propose modified random early detection (MRED) gateways for congestion avoidance in TCP/IP networks. MRED aims at providing better control over the burstiness level while remaining the advantages of RED. We use ns2 to simulate a series of network configurations and the numerical results demonstrate that MRED can achieve higher link utilization compared to RED without sacrificing its advantages in all simulation scenarios. The improvement becomes more significant under bursty traffic.     

Comment, on `A 1/f noise technique to extract the oxidetrap density near the conduction band edge of silicon' [and reply]

For the original article see ibid., vol.36, no.9, p.1773-82 (1989). The commenters show that, contrary to the calculations in the above-titled paper by R. Jayaraman and C.G. Sodini, the correlated noise power spectra of number and surface mobility fluctuations in n-channel MOSFETs are functions of the relative densities of the positive and neutral traps at the Si-SiO₂ interface. The authors, along with B.J. Gross, disagree with the commenters' assessment and support their calculations. The contend that the distribution of active traps assumed by the commenters is not representative of the distribution active in real MOSFET devices     

Tensile behaviour of borosilicate glass matrix-Nicalon (silicon carbide) fibre composites

Unidirectional composites consisting of a borosilicate glass (Corning 7740) matrix reinforced with Nicalon (silicon carbide) fibres were fabricated and tested in monotonic tension at temperatures ranging from room temperature to 650 °C. The ultimate tensile strength showed little dependence on temperature up to about 425 °C and failed by longitudinal splitting. There was a significant increase in strength at 540 °C and a slight decrease in strength when tested above this temperature, and the failure involved extensive fibre pull-out. The elastic modulus (stiffness) was found to decrease progressively with increasing temperature. The matrix consists of borosilicate glass within the plies and very fine grains of alpha (low) cristobalite in the inter-ply regions. The behaviour of the composite as a whole was found to be dependent upon the behaviour of the matrix at the temperature of testing.     

The human type 1 inositol 1,4,5-trisphosphate receptor from T lymphocytes. Structure, localization, and tyrosine phosphorylation

Inositol 1,4,5-trisphosphate receptors (IP3R) are intracellular calcium release channels involved in diverse signaling pathways. An IP3R is thought to play a role in mobilizing calcium required for activation of T lymphocytes. The IP3R is a tetrameric structure comprised of four approximately 300-kDa subunits encoded by a approximately 10-kilobase mRNA. In the present study we determined the structure of the human type 1 IP3R expressed in T lymphocytes (Jurkats). The IP3R in human T cells had a predicted molecular mass of 308 kDa and was most similar to the non-neuronal form of the rodent type 1 IP3R. Two putative tyrosine phosphorylation sites were identified, one near the amino terminus and one near the putative channel pore at the carboxyl terminus. During T cell activation the IP3R was tyrosine phosphorylated. A site-specific anti-IP3R antibody was used to localize the carboxyl terminus of the IP3R to the cytoplasm in T cells.     

Technical note: thyratron performance--dependence on mounting in a medical linear accelerator

A thyratron is an important component of a medical linear accelerator. The working life of a thyratron has been found to be dependent on its physical orientation in the accelerator. This observation is a result of maintaining accelerators for over 15 years.