Spark plasma sintering to restrict sintering reactions and enhance properties of hydroxyapatite–mullite biocomposites

Herein, we demonstrate how spark plasma sintering (SPS) can be useful in restricting the sintering reactions and faster densification in Hydroxyapatite–Mullite system, which otherwise shows extensive sintering reactions during conventional pressureless sintering, as reported in a recent study [Nath et al. J. Am. Ceram. Soc. 93 (2010) 1639–1649]. The microstructure of SPSed Hydroxyapatite (HAp)-20 wt% mullite composites was characterized by submicron sized HAp and equiaxed mullite grains. Another important result has been the achievement of higher hardness of 7 GPa, which is much higher than pressureless sintered composites. The cell culture study including cellular viability using MTT analysis establishes good cytocompatibility of SPSed composites.     

Active learning: an empirical study of common baselines

Most of the empirical evaluations of active learning approaches in the literature have focused on a single classifier and a single performance measure. We present an extensive empirical evaluation of common active learning baselines using two probabilistic classifiers and several performance measures on a number of large datasets. In addition to providing important practical advice, our findings highlight the importance of overlooked choices in active learning experiments in the literature. For example, one of our findings shows that model selection is as important as devising an active learning approach, and choosing one classifier and one performance measure can often lead to unexpected and unwarranted conclusions. Active learning should generally improve the model’s capability to distinguish between instances of different classes, but our findings show that the improvements provided by active learning for one performance measure often came at the expense of another measure. We present several such results, raise questions, guide users and researchers to better alternatives, caution against unforeseen side effects of active learning, and suggest future research directions.     

Velocardiofacial syndrome patients with a heterozygous chromosome 22q11 deletion have giant platelets

OBJECTIVE: To evaluate the pregnancy potential of frozen-thawed surgically retrieved epididymal sperm when used with intracytoplasmic sperm injection (ICSI). PATIENTS AND METHODS: From August 1994 to January 1997, 20 thawed samples of sperm from 19 patients, surgically retrieved and frozen after percutaneous or open epididymal aspiration, were used for ICSI. The results were compared with those obtained using fresh sperm obtained at the same procedure. RESULTS: Of the specimens of surgically retrieved sperm which had been frozen, stored and thawed, 15 had sufficient motile sperm for use with ICSI. The fertilization, cleavage and pregnancy rates in those cycles were similar to the same couples' previous cycle using fresh sperm from the same collection and to the overall results in the NURTURE ICSI programme obtained with fresh epididymal sperm. CONCLUSION: Scrotal exploration for diagnostic testicular biopsy and/or reconstructive surgery without having access to sperm-freezing and storage facilities could represent a lost opportunity for the patient.     

Effect of cold plasma on different polyphenol compounds: A review

Thermal processing has been predominantly used in the food industry to improve food safety and shelf life. However, heat treatment induces detrimental effects like cooked flavor, texture change, and alteration in sensory attributes. These disadvantages encouraged the food industry to adopt non-thermal food processing technologies. Cold plasma is a promising non-thermal food processing method that uses charged, highly reactive gaseous molecules and species to inactivate contaminating microorganisms present in foods. Thus, it has attracted the attention of scientists globally. This review gives the reader an overview of cold plasma technology fundamentals and the detailed mechanism of interaction of reactive plasma species with the polyphenol compounds (simple phenolic acid, individual phenolic compounds, flavonoids, and anthocyanin) present in food. The impact of cold plasma on polyphenol compounds mainly depends on the food matrix and plasma process parameters, viz. voltage, feed gas, and treatment time. Among various polyphenols, flavonoids are degraded faster because of their high ability to scavenge plasma-generated free radicals. The reactive species cause oxidative degradation, double bond cleavage of polyphenol compounds, and aid in the extraction of phenolic compounds. The cold plasma technology has both positive and negative impacts on polyphenol concentration.     

The Governance of Local Urban Climate Adaptation: Towards Participation,Collaboration and Shared Responsibilities

This paper focuses on understanding the institutional determinants of adaptive capacity to illustrate emerging challenges and opportunities for climate adaptation in the context of urban pluvial flood risk management. The paper explores and compares the formal-legal as well as the perceived roles and responsibilities of key actor groups in the context of adaptation to urban pluvial flooding in the Dutch city Arnhem. The concluding section questions the assumed power of formal-legal rules and institutions in motivating key stakeholders to take action. It poses that, in order to stimulate participation and collaboration in local climate adaptation, more attention should be paid to the informal institutional context, in particular to the perception of responsibilities.     

Electrical,Thermal and Spectroscopic Characterization of Bulk Bi<Subscript>2</Subscript>Se<Subscript>3</Subscript> Topological Insulator

We report the electrical (angular magneto-resistance and Hall), thermal (heat capacity) and spectroscopic (Raman, X-ray photoelectron, angle-resolved photoelectron) characterization of a bulk Bi₂Se₃ topological insulator, which was grown by self-flux method through solid-state reaction from high-temperature (950^°C) melt and slow cooling (2^°C/h) of constituent elements. Bi₂Se₃ exhibited metallic behaviour down to 5 K. Magneto-transport measurements revealed linear up to 400 and 30% magneto-resistance (MR) at 5 K under a 14-T field in perpendicular and parallel field directions, respectively. We noticed that the MR of Bi₂Se₃ is very sensitive to the angle of the applied field. The MR is maximum when the field is normal to the sample surface, while it is minimum when the field is parallel. The Hall coefficient (R _H) is seen nearly invariant with a negative carrier sign down to 5 K albeit having near-periodic oscillations above 100 K. The heat capacity (C _p) versus temperature plot is seen without any phase transitions down to 5 K and is well fitted (C _p = γ T + β T ³) at low temperature with a calculated Debye temperature (?? _D) value of 105.5 K. Clear Raman peaks are seen at 72, 131 and 177 cm^?1 corresponding to A\(_{\mathrm {1g}}^{1}\), E\(_{\mathrm {g}}^{2}\) and A\(_{1\mathrm {g}}^{2}\), respectively. Though two distinct asymmetric characteristic peak shapes are seen for Bi 4f_7/2 and Bi 4f_5/2, the Se 3d region is found to be broad, displaying the overlapping of spin-orbit components of the same. Angle-resolved photoemission spectroscopy (ARPES) data of Bi₂Se₃ revealed distinctly the bulk conduction bands (BCB), surface state (SS), Dirac point (DP) and bulk valence bands (BVB), and 3D bulk conduction signatures are clearly seen. Summarily, a host of physical properties for the as-grown Bi₂Se₃ crystal are reported here.     

Crystal Growth and Magneto-transport of Bi<Subscript>2</Subscript>Se<Subscript>3</Subscript> Single Crystals

In this letter, we report on the growth and characterization of bulk Bi ₂Se ₃ single crystals. The studied Bi ₂Se ₃ crystals are grown by the self-flux method through the solid-state reaction from high-temperature (950 °C) melt of constituent elements and slow cooling (2 ℃/h). The resultant crystals are shiny and grown in the [00l] direction, as evidenced from surface XRD. Detailed Reitveld analysis of powder X-ray diffraction (PXRD) of the crystals showed that these are crystallized in the rhombohedral crystal structure with a space group of R3m (D5), and the lattice parameters are a = 4.14 (2), b = 4.14 (2), and c = 28.7010 (7) Å. Temperature versus resistivity (ρ?T) plots revealed metallic conduction down to 2 K, with typical room temperature resistivity (ρ _{300 K}) of around 0.53 m Ω-cm and residual resistivity (ρ _{0 K}) of 0.12 m Ω-cm. Resistivity under magnetic field [ ρ(T)H] measurements exhibited large + ve magneto-resistance right from 2 to 200 K. Isothermal magneto-resistance [ ρH] measurements at 2, 100, and 200 K exhibited magneto-resistance (MR) of up to 240 %, 130 %, and 60 %, respectively, at 14 T. Further, the MR plots are nonsaturating and linear with the field at all temperatures. At 2 K, the MR plots showed clear quantum oscillations at above say 10 T applied field. Also, the Kohler plots, i.e., Δρ/ ρ _oversus B/ ρ, were seen consolidating on one plot. Interestingly, the studied Bi ₂Se ₃ single crystal exhibited the Shubnikov-de Haas (SdH) oscillations at 2 K under different applied magnetic fields ranging from 4 to 14 T.     

Principal components analysis of multienergy X-ray computedtomography of mineral samples

Principal components analysis (PCA) of X-ray transmission tomography images made at several different energies can produce images that allow individual materials to be distinguished more clearly than in single-energy images. Computer simulations and tests on a five-band mineral data set demonstrate the application of PCA