Room temperature ammonia sensor based on jaw like bis-porphyrin molecules

A jaw-like bis-porphyrin (bis-TPP) molecule was synthesized anchoring of two porphyrin molecules to a benzene ring at the meta positions through the ester linkage. The bis-TPP molecule and its zinc-derivative (Zn-bis-TPP) were spin-coated on glass surfaces to construct two chemiresistive room temperature NH₃ gas sensors. Both the films showed high selectivity, reproducibility and reversibility in sensing NH₃ gas (5–40 ppm) in air. The sensing characteristics of the Zn-bis-TPP films (response (2 s) and recovery (2.5 min) times; linear response (952%)) were better than that of the bis-TPP films (response (8 s) and recovery (7.5 min) times; linear response (131%)). This is attributed to the amorphous nature of the former.     

Effect of Reinforcement with Ceramic Microparticles on Structure and Properties of Composites with an Aluminum Matrix

Metal Science and Heat Treatment - The effect of reinforcement with ceramic microparticles of SiC, B4C and Al2O3 on the microstructure and mechanical properties of composite materials with an...     

Structural and Optical Properties of Tunable Warm‐White Light‐Emitting ZrO2:Dy3+–Eu3+ Nanocrystals

A series of Dy³⁺–Eu³⁺‐codoped ZrO₂ nanocrystals with tetragonal and cubic symmetry was synthesized via a wet chemical reaction. When the Eu³⁺‐doping content was fixed, the crystal structure could be stabilized from the mixed phase to single cubic phase by simply adjusting the content of Dy³⁺. The cubic ZrO₂:Dy³⁺–Eu³⁺ nanoparticles exhibited spherical and nonagglomerated morphology. The effective phonon energy of cubic ZrO₂:5%Dy³⁺–5%Eu³⁺ was calculated to be 445 cm^?1, which is lower than the previously reported results. Extensive luminescence studies of ZrO₂:Dy³⁺–Eu³⁺ as a function of Dy³⁺ content demonstrated that the dopant concentration and its site symmetry play an important role in the emissive properties. Under 352 nm excitation, the increment of Dy³⁺ concentration in ZrO₂:Dy³⁺–Eu³⁺ led to an increase in orange (590 nm) and red (610 nm) emissions of Eu³⁺ ions, which are attributed to the ⁵D₀→⁷F_J(J = 1, 2) transitions of Eu³⁺ ions. This increment is possibly due to the efficient energy transfer (ET) ⁴F_9/2:Dy³⁺→⁵D₀:Eu³⁺. The phosphors can generates light from yellow through near white and eventually to warm white by properly tuning the concentration of Dy³⁺ ions through the ET and change in site symmetry. These phosphors may be promising as warm‐white‐/yellow‐emitting phosphors.     

Influence of cationic flocculant properties on the flocculation of yeast suspensions

In this study four different cationic polyelectrolytes of different molecular weight and charge densities were used to flocculate yeast suspensions to determine the effect of flocculant dose, molecular weight and charge density on the resulting floc size, morphology and charge. The zeta potential of the negatively charged yeast flocs was observed to increase with flocculant dose. As the flocculant dose was increased the charge of the floc was observed to reverse; the actual dose at which charge reversal occurs being dependent on the flocculant charge density and molecular weight. Floc size and morphology, measured with a video camera, showed that higher molecular weight flocculants produced larger flocs for the same dose. The results obtained here suggest that that flocculants may be screened by determining the charge, size and morphology of the resulting floc particles which is less time-consuming.     

Binary Galois field based asynchronous scheduling protocol for delay tolerant networks

Wireless Networks - Neighbour discovery plays a crucial role for communication in sparsely dense mobile networks, especially in delay tolerant networks, where neighbour discovery latency is...     

Cluster Based Localization Scheme with Backup Node in Underwater Wireless Sensor Network

Wireless Personal Communications - The localization is a process of finding out the exact location of sensor nodes. For underwater, it is very difficult task to locate sensor nodes as the...     

A network based mechanism for managing decomposable tasks via crowdsourcing

If a task is decomposable in a competitive crowdsourcing environment, thereby allowing collaboration, rational workers may choose to divide it into multiple sub-tasks among themselves. But as the winners are selected independently, there is no benefit out of this decomposition. We show that by the appropriate combination of such decomposed solutions, obtained from multiple workers, we can achieve a better solution for a given task. We present a network based mechanism to choose the best mixture of sub-tasks in a competitive environment for selecting collaborating winners.     

$$C^3$$-index: a PageRank based multi-faceted metric for authors’ performance measurement

Ranking scientific authors is an important but challenging task, mostly due to the dynamic nature of the evolving scientific publications. The basic indicators of an author’s productivity and impact are still the number of publications and the citation count (leading to the popular metrics such as h-index, g-index etc.). H-index and its popular variants are mostly effective in ranking highly-cited authors, thus fail to resolve ties while ranking medium-cited and low-cited authors who are majority in number. Therefore, these metrics are inefficient to predict the ability of promising young researchers at the beginning of their career. In this paper, we propose \(C^3\)-index that combines the effect of citations and collaborations of an author in a systematic way using a weighted multi-layered network to rank authors. We conduct our experiments on a massive publication dataset of Computer Science and show that—(1) \(C^3\)-index is consistent over time, which is one of the fundamental characteristics of a ranking metric, (2) \(C^3\)-index is as efficient as h-index and its variants to rank highly-cited authors, (3) \(C^3\)-index can act as a conflict resolution metric to break ties in the ranking of medium-cited and low-cited authors, (4) \(C^3\)-index can also be used to predict future achievers at the early stage of their career.     

Synthesis and some properties of PVC-bound dimethylglyoxime complexes of Co(II), Ni(II), and Cu(II)

Poly(vinyl chloride) (PVC) has been reacted with dimethylglyoxime (DMG) in THF to form the PVC–DMG comples, which has been characterized by spectroscopic and elemental analyses. The latter indicate that there is one DMG moiety anchored on the PVC chain by displacing every 12th Cl atom in the chain. PVC–DMG has further been reacted with alcoholic solutions of Co(II), Ni(II), and Cu(II) to form the intensely colored PVC–DMG–M(II) complexes. The structures of these complexes have been analyzed by elemental and IR spectral analyses. The overall thermal stability of PVC–DMG–M(II) increases in the order: PVC < PVC–DMG–Cu(II) < PVC–DMG–Ni(II) < PVC–DMG–Co(II). The electrical conductivities are also significantly enhanced in the same order. The permittivities of these complexes are high relative to PVC at low frequency falling gradually with increasing frequency and the dielectric loss-frequency behavior is very broad.