Densely Interconnected Porous BN Frameworks for Multifunctional and Isotropically Thermoconductive Polymer Composites

Ideal materials for modern electronics packaging should be highly thermoconductive. This may be achieved through designing multifunctional polymer composites. Such composites may generally be achieved via effective embedment of functional inorganic fillers into desirable polymeric bodies. Herein, two types of high‐performance 3D h‐BN porous frameworks (3D‐BN), namely, h‐BN nanorod‐assembled networks and nanosheet‐interconnected frameworks, are successfully created via an in situ carbothermal reduction chemical vapor deposition substitution reaction using carbon‐based nanorod‐interconnected networks as templates. These 3D‐BN porous materials with densely interlinked frameworks, excellent mechanical robustness and integrity, highly isotropous and multiple heat transfer paths, enable reliable fabrications of diverse 3D‐BN/polymer porous composites. The composites exhibit combinatorial multifunctional properties, such as excellent mechanical strength, light weight, ultralow coefficient of thermal expansion, highly isotropic thermal conductivities (≈26–51 multiples of pristine polymers), relatively low dielectric constants and super‐low dielectric losses, and high resistance to softening at elevated temperatures. In addition, the regarded 3D‐BN frameworks are easily recycled from their polymer composites, and may be reliably reutilized for multifunctional reuse. Thus, these materials should be valuable for new‐era advanced electronic packaging and related applications.     

Optimizing the NIR Fluence Threshold for Nanobubble Generation by Controlled Synthesis of 10–40 nm Hollow Gold Nanoshells

The laser fluence to trigger nanobubbles around hollow gold nanoshells (HGN) with near infrared light is examined through systematic modification of HGN size, localized surface plasmon resonance (LSPR), HGN concentration, and surface coverage. Improved temperature control during silver template synthesis provides monodisperse, silver templates as small as 9 nm. 10 nm HGN with <2 nm shell thickness are prepared from these templates with a range of surface plasmon resonances from 600 to 900 nm. The fluence of picosecond near infrared (NIR) pulses to induce transient vapor nanobubbles decreases with HGN size at a fixed LSPR wavelength, unlike solid gold nanoparticles of similar dimensions that require an increased fluence with decreasing size. Nanobubble generation causes the HGN to melt with a blue shift of the LSPR. The nanobubble threshold fluence increases as the irradiation wavelength moves off the nanoshell LSPR. Surface treatment does not influence the threshold fluence. The threshold fluence increases with decreasing HGN concentration, suggesting that light localization through multiple scattering plays a role. The nanobubble threshold to rupture liposomes is four times smaller for 10 nm than for 40 nm HGN at a given LSPR, allowing us to use HGN size, LSPR, laser wavelength and fluence to control nanobubble generation.     

Synthesis of nanocrystalline nitrogen-rich carbon nitride powders at high pressure

Nitrogen-rich carbon nitride powders with composition close to C₄N_2.8–3.3 were synthesized by using a chemical reaction between sodium azide and hexachlorobenzene under high pressure (7.7 GPa) and a temperature of 500 °C for 30 min. The final black powders were relatively hard materials with high resistance to hot acids and common organic solvents. Analytical electron microscopy and X-ray diffraction studies showed that the powders are predominantly amorphous, containing nanometer-sized crystallites. Carbon and nitrogen K-edge structures obtained by electron energy-loss spectroscopy suggest the existence of chemical bonding between C and N, and that the amorphous carbon nitride matrix is primarily sp²-bonded. Raman and infrared features of the carbon nitride powders closely resemble those in carbon and diamond-like films and also characterize the powders as strongly disordered, sp²-bonded carbon nitride exhibiting graphite-like microdomains with dimensions of approximately 1 nm.     

Why We Distort in Self‐Report: Predictors of Self‐Report Errors in Video Game Play

Using Cognitive Dissonance and Balance Theory, this study investigates factors that predict how and why MMO players inaccurately report their game playing time. It was hypothesized that players belonging to categories other than the stereotypical game player (e.g. younger, less educated, male) would be likely to underreport playing time. It was also hypothesized that those players who held less positive attitudes toward the game would be more likely to underreport their playing time. Comparing people's self‐reported weekly usage of an MMO, EverQuest II, with their actual average weekly usage of the game, data showed that age, education, lack of enjoyment playing the game, and lack of an online sense of community predicted greater levels of underreporting.     

Object segmentation in cluttered and visually complex environments

Object segmentation is essential for systems that acquire object models online for robotic grasping. However, it remains a major technical challenge in visually complex and uncontrolled environments. Segmentation algorithms that rely on image features alone can perform poorly under certain lighting conditions, or if the object and the background have similar appearance. In parallel, known object segmentation algorithms that rely exclusively on three dimensional (3D) geometric data are derived under strong assumptions about the geometry of the scene. A promising approach to performing object segmentation is to use a combination of appearance and 3D features. In this paper, an object segmentation algorithm is presented that combines multiple appearance and geometric cues. The segmentation is formulated as a binary labeling problem. The Conditional Random Fields (CRF) framework is used to model the conditional probability of the labeling given the appearance and geometric data. The maximum a posteriori estimation of the labeling is obtained by minimizing the energy function corresponding to the CRF using graph cuts. A simple and efficient method for initializing the proposed algorithm is also presented. Experimental results have demonstrated the effectiveness of the proposed algorithm.     

Process of preparing hydrocellulose fibres and films from aqueous solutions of cellulose in zinc chloride

Conclusions The possibility of preparing concentrated solutions of cellulose in zinc chloride and the properties of the concentrated solutions have been investigated.Experimental hydrocellulose fibres and films have been spun on laboratory and experimental units; these had properties close to those of ordinary viscose fibres and films, and excelled them in a number of characteristics (elastic modulus, knot strength).Translated from Khimicheskie Volokna, No. 6, pp. 6–9, November–December, 1988.     

QoSPlan: A Measurement Based Quality of Service aware Network Planning Framework

In this article we present QoSPlan—a measurement based framework for preparing information relevant to Quality of Service (QoS)-aware IP network planning, which aims at reducing a core operational expenditure for the network operator. QoSPlan is designed to reduce the cost of deployment and maintenance of network monitoring systems. The process involves analysis of pre-existing accounting data to estimate a network-wide traffic matrix. Part of this estimation process relates to the generalization of QoS-related effective bandwidth coefficients taken from traffic analyzed on the network. We offer recommendations on how to appropriately realize QoSPlan to maximize its accuracy and effectiveness when applied to different network traffic scenarios. This is achieved through a thorough sensitivity analysis of the methods proposed using real traffic scenarios and indicative network topologies. We also provide an economic analysis of the deployment and maintenance costs associated with QoSPlan in comparison to a direct measurement approach, demonstrating cost savings of up to 60 % given different topology sizes.     

Super-EGO: fast multi-dimensional similarity join

Efficient processing of high-dimensional similarity joins plays an important role for a wide variety of data-driven applications. In this paper, we consider $\varepsilon $ -join variant of the problem. Given two $d$ -dimensional datasets and parameter $\varepsilon $ , the task is to find all pairs of points, one from each dataset that are within $\varepsilon $ distance from each other. We propose a new $\varepsilon $ -join algorithm, called Super-EGO, which belongs the EGO family of join algorithms. The new algorithm gains its advantage by using novel data-driven dimensionality re-ordering technique, developing a new EGO-strategy that more aggressively avoids unnecessary computation, as well as by developing a parallel version of the algorithm. We study the newly proposed Super-EGO algorithm on large real and synthetic datasets. The empirical study demonstrates significant advantage of the proposed solution over the existing state of the art techniques.     

A remark on the configurational entropy of a liquid solution with a weak tendency to association

A weak tendency to association may significantly increase the molar configurational entropy of a liquid solution. This circumstance should not be overlooked if one intends to use a positive excess entropy to describe experimental data within the framework of the CALPHAD method.     

Laser powered heating stage in a scanning electron microscope for microstructural investigations at elevated temperatures

A laser powered heating stage designed for application in high vacuum environment of a scanning electron microscope (SEM) is presented. It was developed to observe and characterize microstructural changes in crystalline materials at elevated temperatures up to 1000 degrees C. The approach utilizes the power output of a commercial infrared diode laser in order to heat up specimens without interference with the electronic system of the SEM. The heating stage can be used in combination with any standard characterization technique applicable for SEMs--electron backscatter diffraction, orientation contrast imaging, x-ray energy dispersive spectrometry, etc. The results of test measurements are presented.