Characterization of Stiction Accrual in a MEMS

Stiction remains one of the chief reliability concerns for microelectromechanical systems (MEMS) devices. In this paper, we quantify and analyze the rate of accrual of stiction in a standard MEMS device under a set of controlled temperature and humidity splits. An accelerated aging system was employed to more rapidly induce stiction in the MEMS. Optical characterization techniques were used to study the progression of stiction. The stiction accrual was quantified in terms of stiction equivalent energy, which provides compensation for mechanical fatigue in the devices due to long periods of operation. The fastest accrual of stiction was seen in the 90degC, 80% relative humidity (RH) split with approximately 80% of the MEMS elements failing within 4.4 times 10⁹ cycles (10 h) with 2.7 times 10^-14 Joules of stiction equivalent energy while the 60degC, 20% RH showed the least stiction accrual rate with less than 2% failure for 2.26 times 10¹² cycles (1500 h). In general, the stiction was seen to increase with an increase in humidity while mechanical fatigue showed an increase with an increase in temperature. Atomic force microscopy topography imaging was used to assess physical wear at the contacting areas. The results revealed that there were not any discernable changes in the surface profile due to long periods of actuation.     

Peptides from the Intestinal Tract of Breast Milk-Fed Infants Have Antimicrobial and Bifidogenic Activity

For bioactive milk peptides to be relevant to infant health, they must be released by gastrointestinal proteolysis and resist further proteolysis until they reach their site of activity. The intestinal tract is the likeliest site for most bioactivities, but it is currently unknown whether bioactive milk peptides are present therein. The purpose of the present study was to identify antimicrobial and bifidogenic peptides in the infant intestinal tract. Milk peptides were extracted from infant intestinal samples, and the activities of the bulk peptide extracts were determined by measuring growth of Escherichia coli, Staphylococcus aureus, and Bifidobacterium longum spp. infantis after incubation with serial dilutions. The peptide profiles of active and inactive samples were determined by peptidomics analysis and compared to identify candidate peptides for bioactivity testing. We extracted peptides from 29 intestinal samples collected from 16 infants. Five samples had antimicrobial activity against S. aureus and six samples had bifidogenic activity for B. infantis. We narrowed down a list of 6645 milk peptides to 11 candidate peptides for synthesis, of which 6 fully inhibited E. coli and S. aureus growth at concentrations of 2500 and 3000 µg/mL. This study provides evidence for the potential bioactivity of milk peptides in the infant intestinal tract.     

Interactions of Oligomeric Procyanidins in Model Wine Solutions Containing Malvidin-3-Glucoside and Acetaldehyde

Interactions of grape seed flavanols, dimeric, galloylated dimeric and trimeric procyanidins with malvidin-3-glucoside and acetaldehyde were studied in wine-like model solutions. Malvidin-3-glucoside and oligomeric procyanidins reacted very slowly, with eventual formation of yellow xanthylium salts. The concentrations of malvidin-3-glucoside and oligomeric procyanidins decreased faster in the presence of acetaldehyde and the colour augmentation with shift towards violet was attributed to the formation of new coloured compounds, detectable by HPLC and linked at different positions by CH₃CH bridges. The rate of loss of procyanidins in the presence of malvidin-3-glucoside and acetaldehyde varied according to the complexity of the components. Monomeric (+)-catechin and (-)-epicatechin reacted more slowly than dimer procyanidins B₁, B₂ and B₃ while trimer C₁ (epicatechin 4β→8 epicatechin 4β→8 epicatechin) presented the highest degradative reaction rate.     

Inactivation of hepatitis A virus and a calicivirus by high hydrostatic pressure

Potential application of high hydrostatic pressure processing (HPP) as a method for virus inactivation was evaluated. A 7-log10 PFU/ml hepatitis A virus (HAV) stock, in tissue culture medium, was reduced to nondetectable levels after exposure to more than 450 MPa of pressure for 5 min. Titers of HAV were reduced in a time- and pressure-dependent manner between 300 and 450 MPa. In contrast, poliovirus titer was unaffected by a 5-min treatment at 600 MPa. Dilution of HAV in seawater increased the pressure resistance of HAV, suggesting a protective effect of salts on virus inactivation. RNase protection experiments indicated that viral capsids may remain intact during pressure treatment, suggesting that inactivation was due to subtle alterations of viral capsid proteins. A 7-log10 tissue culture infectious dose for 50% of the cultures per ml of feline calicivirus, a Norwalk virus surrogate, was completely inactivated after 5-min treatments with 275 MPa or more. These data show that HAV and a Norwalk virus surrogate can be inactivated by HPP and suggest that HPP may be capable of rendering potentially contaminated raw shellfish free of infectious viruses.     

γ-linolenic acid-containing diet attenuates bleomycin-induced lung fibrosis in hamsters

Although bleomycin (BLM), an antineoplastic drug, is used in the treatment of a variety of tumors, the mechanism(s) that contribute to its induced lung injury and fibrosis are not fully elucidated. Since alterations in the levels of certain fatty acid metabolites have been associated with BLM-induced lung injury, we tested the effects of dietary γ-linolenic acid (GLA)-containing evening primrose oil on BLM-induced morphological alterations in the hamster lung, the marked elevation of tissue hydroxyproline (a marker for collagen synthesis), and elevated generation of arachidonic acid metabolites (marker of inflammatory mediators). Our data revealed that after 14 d of dietary GLA-containing oil (i) BLM-induced elevation of lung hydroxyproline was suppressed (P<0.05), (ii) the marked BLM-induced elevation of lung leukotriene B₄ (LTB₄) (a marker of polymorphonuclear generation of proinflammatory LTB₄) was significantly suppressed (P<0.05). The decrease in LTB₄ was accompanied by marked elevations (P<0.05) of lung prostaglandin E₁ (PGE₁) and 15-hydroxyeicosatrienoic acid (15-HETrE), both with known antiinflammatory properties. Taken together, data from these studies suggest that dietary GLA-containing oil contributes to tissue elevation of PGE₁ and 15-HETrE, which in vivo may attenuate lung inflammation and fibrosis.     

Effect of Antioxidant Solubility and Concentration on Discoloration of Beef Vertebrae Marrow during Display

ABSTRACT:  Two experiments were conducted to assess the role of aqueous- and lipid-based antioxidants in preventing or limiting beef lumbar vertebrae marrow discoloration. In experiment 1, lumbar vertebrae ( n = 8 replications) were treated with either 0%, 1.5%, or 2.5% (wt/wt) of ascorbic acid or ascorbate-6-palmitate. Vertebrae color (visual and L*a*b*) was evaluated during 5 d of display at 1 °C in high-oxygen modified atmosphere packaging (MAP; 80% oxygen/20% carbon dioxide). Ascorbic acid treatments minimized ( P < 0.05) discoloration compared with ascorbate-6-palmitate. In experiment 2, lumbar vertebrae ( n = 8 replications) were treated with 0, 0.06 M, or 0.10 M ascorbic acid and ascorbate-6-palmitate, packaged in high-oxygen MAP, and displayed for 5 d (1 °C). During display, vertebrae treated with ascorbic acid had a redder color ( P < 0.05) than those treated with ascorbate-6-palmitate, and both treatments were redder ( P < 0.05) than untreated controls. To better understand the mechanism of beef bone marrow discoloration, future work might address the hydrophobic antioxidants' lack of effectiveness and the potential localization of components responsible for bone discoloration within the aqueous phase of erythropoietic marrow.     

Polypyrrole/MWNT nanocomposites synthesized through interfacial polymerization

Polypyrrole/carbon nanotubes (CNTs) composites were synthesized by dispersion of organically modified multiwall carbon nanotubes during an interfacial polymerization of pyrrole. During the polymerization, the carbon nanotubes are entrapped by the polymer chains and the nanocomposite is formed in the interphase between two immiscible solvents. The method favours a better dispersion of the nanotubes in the polypyrrole offering enhanced electrical properties. The characterisation of the composite material has been established by XRD, TGA analysis and electron microscopy techniques.     

Flow cytometric analyses of antibody binding to Chinese hamster ovary cells expressing human thyrotropin receptor

To develop a method that can be used to directly detect binding of antibodies to TSH receptor (TSHr), we employed Chinese hamster ovary (CHO) cells permanently transfected with a human TSHr complementary DNA (CHOR). These cells showed increased cAMP production when treated with either human TSH or thyroid-stimulating antibodies and decreased TSH-mediated cAMP production when treated with stimulation-blocking antibodies. We employed flow cytometry and rabbit antibodies against the extracellular domain of the TSHr (ETSHr) to test whether these cells can be used to directly detect and quantitate the binding of anti-TSHr antibodies. Rabbit anti-ETSHr bound specifically to CHOR cells, and the binding could be blocked with purified ETSHr. To test the feasibility of using these cells for epitope mapping, we tested the binding of rabbit antibodies raised against several synthetic TSHr peptides. Rabbit antipeptide 92 (amino acids 12-30) and 91 (amino acids 32-46) showed little or no binding to the CHOR cells. In contrast, antibodies raised against peptides 93 (amino acids 316-330), 95 (aa 325-345), 3A (aa 357-372), 367 (aa 367-386), and 1B (aa 362-376) showed significant binding to the CHOR cells. The specificity of binding of antipeptide antibodies was demonstrated by a complete inhibition of binding by corresponding peptides. When TSH-binding inhibitory Ig-positive sera from 15 patients with hyperthyroidism were tested, 8 of them showed specific binding to the CHOR cells compared to their relative binding to normal CHO cells; sera from all normal individuals tested did not exhibit specific binding to CHOR cells. These studies showed the usefulness of CHOR cells and flow cytometry in epitope mapping using sera with known specificities and the potential usefulness of the technique to detect anti-TSHr antibodies in patient sera.     

Computing P-values for a class of permutation tests of equal survival functions

Dallas and Rao (Biometrics 56 (2000) 154) proposed a class of permutation tests for testing the equality of two survival distributions based on randomly right censored survival time data consisting of both paired and unpaired observations. Data sets of this type can occur frequently in medical settings. Two members of this class were advocated for use due to their generally high power for detecting scale and location shifts in the exponential and log-logistic distributions for the survival times, and improved power over paired data test procedures that disregard unpaired observations. Because the computations for the tests become quite laborious as the sample sizes increase, computing routines are required for practical implementation of these tests. This paper provides computing routines to execute the tests.     

Semantic processing of non-attended visual information.

In 2 experiments, with 28 university students, reaction time (RT) to name 1 of 2 rows of letter material was measured. The reported row was always a word. In Exp I, the nonreported row contained either a word semantically related to the reported word, a nonassociated word, or a nonword. Nonwords were not used in Exp II. Attentional selectivity was varied by presenting a report cue either 250 msec prior to display onset or 250 msec after display onset. RT was faster when the report cue preceded the display, indicating that this cue induced selective attention. In both the selective and nonselective conditions, RT to name the target word was faster when the nonreported row contained a word associated with the target than when it contained a nonassociated word. However, this facilitation of RT produced by associated nonreported words was greater under the nonselective condition. While semantic information was extracted from both nonattended and attended visual material a larger semantic interaction occurred when attention was directed to both rows of a visual display. Results also indicate that the presence of nonwords influenced the strategy used to analyze a visual display. (French summary) (19 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)