Myocardial injury after hypoxia in immature, adult and aged rats

We evaluated the abilities of isolated perfused hearts from immature (IM) (2.5-3 months), ADULT (11-13 months) and OLD (24-26 months) Fischer 344 rats to tolerate and recover from oxygen deprivation. Hearts were perfused at 60 mmHg for a 30-minute prehypoxic period with oxygenated buffer supplemented with 10 mM glucose (+insulin) and 2 mM acetate, then 30 minutes with substrate-free, hypoxic buffer gassed with 95% N2:5% CO2, and finally reoxygenated for an additional 45 minutes with the same buffer used during the prehypoxic period. During prehypoxia, all groups were similar in ventricular mechanical function, glycogen content, high-energy phosphates (HEP), reduced glutathione (GSH), Ca+2 content, and mitochondrial state 3 rates. At the end of the hypoxic period, glycogen levels were similar and almost completely depleted in all groups, HEP were lower (p < 0.05) in ADULT vs other groups, mitochondrial state 3 rates were decreased (24%, p < 0.05) only in ADULT, and GSH was depleted by 34% in IM vs only 13% in OLD (p < 0.05). After 45 minutes of reoxygenation, IM and OLD had recovered 48% and 45% of their respective prehypoxic function which was two-fold greater than the 23% recovery by ADULT. Loss of cytosolic enzymes, an indicator of sarcolemmal damage, was estimated by measuring lactate dehydrogenase (LDH) release. LDH release and Ca+2 content during reoxygenation in IM were only about half of that observed in ADULT or OLD. We conclude that immature and aged hearts tolerate and recover from hypoxia better than hearts from adults, and that the sarcolemmal membranes of immature rat hearts are less susceptible to damage from hypoxic stress than those of either older group.     

The roles of perforin- and Fas-dependent cytotoxicity in protection against cytopathic and noncytopathic viruses

In vitro, T cell-dependent cytotoxicity is mediated by two distinct mechanisms, one being perforin-, the other Fas-dependent. The contribution of both of these mechanisms to clearance of viral infections was investigated in mice for the non-cytopathic lymphocytic choriomeningitis virus (LCMV) and the cytopathic vaccinia, vesicular stomatitis (VSV) and Semliki forest (SFV) viruses. Clearance of an acute LCMV infection was mediated by the perforin-dependent mechanism without measurable involvement of the Fas-dependent pathway. For the resolution of vaccinia virus infection and for resistance against VSV and SFV, however, neither of the two pathways was required. These data suggest that perforin-dependent cytotoxicity mediated by T cells is crucial for protection against non-cytopathic viruses, whereas infections with cytopathic viruses are controlled by nonlytic T cell-dependent soluble mediators such as cytokines (IFN-gamma against vaccinia virus) and neutralizing antibodies (against VSV and SFV).     

纵观3G基站开发的变化

基站接口规范在如何进行3G基站开发方面，2004年被证明是具有显著变化的一年。通用公共无线接口组织(CPRI)和开放式基站结构同盟(OBSAI)分别提出了两个标准，用来规范基站内开放的、标准化的接口。两个组织已经公布了它们的技术规范，支持新标准的产品也开始出现。图1为OBSAI标准定义的开放接口实例。     

Modeling of crack bridging in a unidirectional metal matrix composite

The effective fatigue crack driving force and crack opening profiles were determined analytically for fatigue tested unidirectional composite specimens exhibiting fiber bridging. The crack closure pressure due to bridging was modeled using two approaches; the fiber pressure model and the shear lag model. For both closure models, the Bueckner weight function method and the finite element method were used to calculate crack opening displacements and the crack driving force. The predicted near crack tip opening profile agreed well with the experimentally measured profiles for single edge notch SCS-6/Ti-15-3 metal matrix composite specimens. The numerically determined effective crack driving force, K _eff, was calculated using both models to correlate the measured crack growth rate in the composite. The calculated K _eff from both models accounted for the crack bridging by showing a good agreement between the measured fatigue crack growth rates of the bridged composite and that of unreinforced, unbridged titanium matrix alloy specimens.     

Interface design on cabin pressurization system affecting pilot's situation awareness: The comparison between digital displays and pointed displays

The fundamental approach to improve pilots’ situation awareness (SA) would be to reorganize and restructure the presentation of information to fit pilot's cognitive model on the flight deck. This would facilitate pilots’ perception, understanding, and projection, hence making it easier to find the relevant targets. Sixty pilots (30 B‐737 pilots and 30 B‐777 pilots) participated in this study to investigate pilots’ SA while interacting with digital displays and moving pointed needle displays on cabin pressurization system. The results have shown significant differences on pilots’ perception, understanding, and overall SA between digital display and pointed display on the flight deck. Pilots significantly preferred the digital design cabin pressurization system, which is consistent with the proximity compatibility principle, and the position of the display on the center instrument panel is easily accessible to both pilots and does not require large head movements. There are some recommendations on the cabin pressurization design including the size of outflow valve position indicator, which should be significantly increased to provided saliency of information; color coding should be used on cabin altitude and differential pressure indicator to mark critical cabin altitude; and standard operating procedures shall include cabin altitude and differential pressure reading by pilot monitoring. The final and completed solution to the issues on the cabin pressurization system is to redesign the scattered pointed displays as integrated digital displays to fit the human‐centered principle.     

Robustness analysis of uncertain discrete‐time systems with dissipation inequalities and integral quadratic constraints

This paper presents a connection between dissipation inequalities and integral quadratic constraints (IQCs) for robustness analysis of uncertain discrete‐time systems. Traditional IQC results derived from homotopy methods emphasize an operator‐theoretic input–output viewpoint. In contrast, the dissipativity‐based IQC approach explicitly incorporates the internal states of the uncertain system, thus providing a more direct procedure to analyze uniform stability with non‐zero initial states. The standard dissipation inequality requires a non‐negative definite storage function and ‘hard’ IQCs. The term ‘hard’ means that the IQCs must hold over all finite time horizons. This paper presents a modified dissipation inequality that requires neither non‐negative definite storage functions nor hard IQCs. This approach leads to linear matrix inequality conditions that can provide less conservative results in terms of robustness analysis. The proof relies on a key J‐spectral factorization lemma for IQC multipliers. A simple numerical example is provided to demonstrate the utility of the modified dissipation inequality. Copyright © 2016 John Wiley & Sons, Ltd.     

Conversion of methanol to hydrocarbons on zeolite HZSM‐5 investigated by in situ MAS NMR spectroscopy under flow conditions and on‐line gas chromatography

In situ MAS NMR spectroscopy under flow conditions and on‐line gas chromatography have been applied to study the onset of the conversion of methanol on zeolite HZSM‐5 at temperatures between 373 and 573 K. In the steady states of methanol conversion at T ⩾ 523 K, by on‐line gas chromatography mainly the formation of ethene and propene was observed. Simultaneously recorded in situ ¹³C MAS NMR spectra show signals at 12–25 ppm and at ca. 125–131 ppm indicating the presence of adsorbed C₄–C₆ olefins. The observation of these adsorbates on a working catalyst supports the “hydrocarbon pool” mechanism previously proposed for the methanol‐to‐hydrocarbon conversion on acidic zeolites. Methanol conversion at 473 and 573 K and subsequent purging of the catalyst with dry nitrogen at 293 K led to a ¹³C MAS NMR signal at 59 ppm due to methoxy groups. No hints to the presence of ethoxy, propoxy or butoxy groups and the formation of alkyl oxonium ions were found by in situ ¹³C MAS NMR spectroscopy under flow conditions. This revised version was published online in July 2006 with corrections to the Cover Date.     

Attenuation of green fluorescent protein half-life in mammalian cells

The half-life of the green fluorescent protein (GFP) was determinedbiochemically in cultured mouse LA-9 cells. The wild-type proteinwas found to be stable with a half-life of ~26 h, but couldbe destabilized by the addition of putative proteolytic signalsequences derived from proteins with shorter half-lives. A C-terminalfusion of a PEST sequence from the mouse ornithine decarboxylasegene reduced the half-life to 9.8 h, resulting in a GFP variantsuitable for the study of dynamic cellular processes. In anN-terminal fusion containing the mouse cyclin B1 destructionbox, it was reduced to 5.8 h, with most degradation taking placeat metaphase. The combination of both sequences produced a similarGFP half-life of 5.5 h. Thus, the stability of this marker proteincan be controlled in predetermined ways by addition of the appropriateproteolytic signals.