Characterization of the Percival detector with soft X-rays.

In this paper the back-side-illuminated Percival 2-Megapixel (P2M) detector is presented, along with its characterization by means of optical and X-ray photons. For the first time, the response of the system to soft X-rays (250 eV to 1 keV) is presented. The main performance parameters of the first detector are measured, assessing the capabilities in terms of noise, dynamic range and single-photon discrimination capability. Present limitations and coming improvements are discussed.

Self-assembling chiral gelators for fluorinated media.

Formulations involving partially and fully fluorinated media represent a technological challenge given the lipophobic and hydrophobic nature of such liquids. The identification of self-associating materials with which to control the viscosity and solubilizing characteristics of fluorinated solvents is a particularly interesting area of research. It is shown here that the presence of the stereogenic centers inherent in a family of bis-(alpha,beta-dihydroxy ester)s is an essential requirement for the thermoreversible gelation of mixtures of partially fluorinated liquids 2H,3H-perfluoropentane (HPFP) and 1H,1H-heptafluorobutanol (HFB). Gelation is driven by hydrogen bonding, which induces a nonpreferred conformation around the bis-(alpha,beta-dihydroxy ester) structural motif. An analysis of the melting temperature yields an enthalpy of melting that is consistent with three to four hydrogen bonds, commensurate with the end-group structure of the gelator. Small-angle neutron scattering demonstrated the existence of the common fibrillar structures whose dimensions showed no obvious correlation with the molecular structure of the gelator.

Survival, hemodynamics, and tissue oxygenation after head trauma.

BACKGROUND: The aims of this study were to describe the early time course of hemodynamic and tissue perfusion and oxygenation patterns in survivors and nonsurvivors after head injury; to suggest physiologic mechanisms responsible for the observed patterns; and to evaluate postinjury parameters that might be useful for treatment. The hypothesis was that reduced hemodynamics and tissue oxygenation and reduced arterial oxygen saturation affect outcomes. STUDY DESIGN: Sixty patients with head trauma were noninvasively monitored on arrival in the emergency department to assess the temporal hemodynamic patterns associated with head injury; patients who were brain dead were excluded because they have very different hemodynamic patterns. Cardiac index, mean arterial pressure, and heart rate were monitored to assess cardiac function, pulse oximetry to reflect changes in pulmonary function, and transcutaneous oxygen and carbon dioxide to reflect tissue perfusion function. Patients were stratified by inhospital survival outcomes, the Glasgow Coma Scale, and the presence or absence of associated somatic injuries. RESULTS: When all head injured patients were considered together, the predominant findings were high cardiac index, hypertension, mild tachycardia, normal pulmonary function, and reduced tissue oxygenation. The subset of survivors and those with high Glasgow Coma Scale had greater than normal cardiac index responses (4.02 +/- 0.01 (SEM) L/min/m2, p < 0.01 versus normal) and better tissue oxygenation (217 +/- 2 mmHg PtcO2/FiO2) than nonsurvivors (70 +/- 3 mmHg, p < 0.01) and those with low Glasgow Coma Scale (160 +/- 2, p < 0.05). Patterns of patients with associated somatic injuries were similar to those with isolated head injury. CONCLUSIONS: The study suggested that survivors' cardiac index, tissue oxygenation, and arterial oxygen saturation may be considered as markers of resuscitation. Nonsurvivors of head injury had normal blood flow with reduced tissue oxygenation that might have contributed to unfavorable outcomes.