Enhancing the liquid phase exfoliation of graphite in both aqueous and organic mixtures

Two different solvent mixtures, aqueous and organic, were used in the graphite liquid phase exfoliation. These solvent mixtures were selected through a detailed study of Hansen Solubility Parameters. Different operational sonication parameters (sonication temperature, cycle, amplitude and time) were studied in order to analyze their influence over the exfoliation process. Exfoliated graphite obtained after different sonication conditions were further characterized by RAMAN spectroscopy and thermogravimetric techniques. Obtained results showed that, among all the studied sonication parameters, time is the most important one due to its influence over characteristics of the final exfoliated product. Thus, it was evidenced the defect formation at higher sonication times, being dominant the growth of bulk defects in the structure of exfoliated samples at sonication times superior to 5 hours. As consequence, a careful tuning of the sonication parameters is necessary in order to obtain exfoliated samples with low disorder.Se utilizaron dos mezclas de disolventes diferentes, acuosa y orgánica, en la exfoliación en fase líquida de grafito. Estas mezclas de disolventes se seleccionaron mediante un estudio detallado de los parámetros de solubilidad de Hansen. Se estudiaron diferentes parámetros operativos de sonicación (temperatura, ciclo, amplitud y tiempo de sonicación) para analizar su influencia sobre el proceso de exfoliación. El grafito exfoliado obtenido después de diferentes condiciones de sonicación se caracterizó aún más mediante espectroscopia RAMAN y técnicas termogravimétricas. Los resultados obtenidos mostraron que, entre todos los parámetros de sonicación estudiados, el tiempo es el más importante debido a su influencia sobre las características del producto final exfoliado. Así, se evidenció la formación de defectos a mayores tiempos de sonicación, siendo dominante el crecimiento de defectos de volumen en la estructura de muestras exfoliadas a tiempos de sonicación superiores a 5 horas. Como consecuencia, es necesario un ajuste cuidadoso de los parámetros de sonicación para obtener muestras exfoliadas con bajo desorde

Self-help groups challenge health care systems in the US and UK

Purpose: This research considers how self-help groups (SHGs) and self- help organizations (SHOs) contribute to consumerist trends in two different societies: United States and United Kingdom. How do the health care systems and the voluntary sectors affect the kinds of social changes that SHGs/SHOs make? Methodology/approach: A review of research on the role of SHGs/SHOs in contributing to national health social movements in the UK and US was made. Case studies of the UK and the US compare the characteristics of their health care systems and their voluntary sector. Research reviews of two community level self-help groups in each country describe the kinds of social changes they made. Findings: The research review verified that SHGs/SHOs contribute to national level health social movements for patient consumerism. The case studies showed that community level SHGs/SHOs successfully made the same social changes but on a smaller scale as the national movements, and the health care system affects the kinds of community changes made. Research limitations: A limited number of SHGs/SHOs within only two societies were studied. Additional SHGs/SHOs within a variety of societies need to be studied. Originality/value of chapter Community SHGs/SHOs are often trivialized by social scientists as just inward-oriented support groups, but this chapter shows that local groups contribute to patient consumerism and social changes but in ways that depend on the kind of health care system and societal context

Measurement of the CP-Violating Asymmetry Amplitude sin2β\beta

We present results on time-dependent CP-violating asymmetries in neutral B decays to several CP eigenstates. The measurements use a data sample of about 88 million Y(4S) --> B Bbar decays collected between 1999 and 2002 with the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. We study events in which one neutral B meson is fully reconstructed in a final state containing a charmonium meson and the other B meson is determined to be either a B0 or B0bar from its decay products. The amplitude of the CP-violating asymmetry, which in the Standard Model is proportional to sin2beta, is derived from the decay-time distributions in such events. We measure sin2beta = 0.741 +/- 0.067 (stat) +/- 0.033 (syst) and |lambda| = 0.948 +/- 0.051 (stat) +/- 0.017 (syst). The magnitude of lambda is consistent with unity, in agreement with the Standard Model expectation of no direct CP violation in these modes

A search for the decay B+→K+ννˉB^+ \to K^+ \nu \bar{\nu}

We search for the rare flavor-changing neutral-current decay $B^+ \to K^+ \nu \bar{\nu}$ in a data sample of 82 fb$^{-1}$ collected with the {\sl BABAR} detector at the PEP-II B-factory. Signal events are selected by examining the properties of the system recoiling against either a reconstructed hadronic or semileptonic charged-B decay. Using these two independent samples we obtain a combined limit of ${\mathcal B}(B^+ \to K^+ \nu \bar{\nu})<5.2 \times 10^{-5}$ at the 90% confidence level. In addition, by selecting for pions rather than kaons, we obtain a limit of ${\mathcal B}(B^+ \to \pi^+ \nu \bar{\nu})<1.0 \times 10^{-4}$ using only the hadronic B reconstruction method.Comment: 7 pages, 8 postscript figures, submitted to Phys. Rev. Let

High-reflectivity broadband distributed Bragg reflector lattice matched to ZnTe

We report on the realization of a high quality distributed Bragg reflector with both high and low refractive index layers lattice matched to ZnTe. Our structure is grown by molecular beam epitaxy and is based on binary compounds only. The high refractive index layer is made of ZnTe, while the low index material is made of a short period triple superlattice containing MgSe, MgTe, and ZnTe. The high refractive index step of Delta_n=0.5 in the structure results in a broad stopband and the reflectivity coefficient exceeding 99% for only 15 Bragg pairs.Comment: 4 pages, 3 figure

Measurement of the electron energy spectrum and its moments in inclusive B -> Xe nu decays

We report a measurement of the inclusive electron energy spectrum for semileptonic decays of B mesons in a data sample of 52 million Y(4S)-->B(B) over bar decays collected with the BABAR detector at the PEP-II asymmetric-energy B-meson factory at SLAC. We determine the branching fraction, first, second, and third moments of the spectrum for lower cutoffs on the electron energy between 0.6 and 1.5 GeV. We measure the partial branching fraction to be B(B-->Xenu,E-e>0.6 GeV)=[10.36+/-0.06(stat.)+/-0.23(sys.)]%

Improved measurement of CP asymmetries in B-0 ->(c(c)over-bar)K0((*)) decays

We present results on time-dependent CP asymmetries in neutral B decays to several CP eigenstates. The measurements use a data sample of about 227x10(6) Upsilon(4S)-> B (B) over bar decays collected by the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. The amplitude of the CPasymmetry, sin2 beta in the standard model, is derived from decay-time distributions from events in which one neutral B meson is fully reconstructed in a final state containing a charmonium meson and the other B meson is determined to be either a B-0 or (0) from its decay products. We measure sin2 beta=0.722 +/- 0.040(stat)+/- 0.023(syst) in agreement with the standard model expectation

Human seminal fluid as a source of prostate cancer-specific microRNA biomarkers

Research letterLuke A Selth, Matthew J Roberts, Clement W K Chow, Villis R Marshall, Suhail A R Doi, Andrew D Vincent, Lisa M Butler, Martin F Lavin, Wayne D Tilley and Robert A Gardine