On the reliability of electrostatic NEMS/MEMS devices: Review of present knowledge on the dielectric charging and stiction failure mechanisms and novel characterization methodologies

This paper reviews the state of the art knowledge related to critical failure mechanisms in electrostatic micro- and nano-electromechanical systems (MEMS and NEMS) which are the dielectric charging and stiction. It describes also the recent employed nanoscale characterization techniques for these phenomena based on Kelvin probe force microscopy (KPFM) and force–distance curve measurements. The influence of relative humidity and dielectric deposition conditions on the charging/discharging processes is discussed. Moreover, different stiction mechanisms induced by electrostatic force and/or meniscus formation are analyzed. Finally, novel characterization methods are presented and used to correlate between the results from MEMS devices and metal–insulator–metal (MIM) capacitors. These methods are employed in view of application in electrostatic capacitive MEMS switches and could be easily extended to explore other NEMS/MEMS devices. The study provides an accurate understanding of the charging and stiction related failure mechanisms, presents guidelines for a proper packaging environment, and reveals precise explanations for the literature reported device level measurements of electrostatic MEMS devices.     

The Advanced Glaucoma Intervention Study (AGIS): 5. Encapsulated bleb after initial trabeculectomy

PURPOSE: To compare the incidence of encapsulated bleb after trabeculectomy in eyes with and without previous argon laser trabeculoplasty and to assess other risk factors for encapsulated bleb development. METHODS: After medical treatment failure, eyes enrolled in the Advanced Glaucoma Intervention Study (AGIS) were randomly assigned to sequences of interventions starting with either argon laser trabeculoplasty or trabeculectomy. In the present study we compared the clinical course for 1 year after trabeculectomy in 119 eyes with failed argon laser trabeculoplasty with that of 379 eyes without previous argon laser trabeculoplasty. Data on bleb encapsulation were collected at the time that the encapsulation was diagnosed, and 3 and 6 months later. RESULTS: Of multiple factors examined in the AGIS data for the risk of developing encapsulated bleb, only male gender and high school graduation without further formal education were statistically significant. Encapsulation occurred in 18.5% of eyes with previous argon laser trabeculoplasty failure and 14.5% of eyes without previous argon laser trabeculoplasty (unadjusted relative risk, 1.27; 95% confidence limits = 0.81, 2.00; P = .23). After adjusting for age, gender, educational achievement, prescribed systemic beta-blockers, diabetes, visual field score, and years since glaucoma diagnosis, this difference remains statistically not significant. Four weeks after trabeculectomy, mean intraocular pressure was 7.5 mm Hg higher in eyes with (22.5 mm Hg) than without (15.0 mm Hg) encapsulated bleb; at 1 year after trabeculectomy and the resumption of medical therapy when needed, this excess was reduced to 1.4 mm Hg. CONCLUSIONS: This study, as did two previous studies, found male gender to be a risk factor for bleb encapsulation. Four studies, including the present study, have reported a higher rate of encapsulation in eyes with previous argon laser trabeculoplasty; in two of the studies, one of which was the present study, the rate was not statistically significantly higher; in the other two studies the rate was significantly higher. The 4-week postoperative mean intraocular pressure was higher in eyes with than without encapsulated bleb; with the resumption of medical treatment the two means converged after 1 year.     

Effect of orientation on the high-temperature superelasticity in Co49Ni21Ga30 single crystals

The temperature interval ΔT _SE of superelasticity in [001]-, [$ \bar 1 $ \bar 1 23]-, and [$ \bar 1 $ \bar 1 24]-oriented Co₄₀Ni₂₁Ga₃₀ (at. %) single crystals strained at compression has been studied. It is established that ΔT _SE in the [001]-oriented single crystal amounts to 441 K and the reversible B2-L1₀ martensite transformations in loaded samples take place at T ₂ = 698 K. In [$ \bar 1 $ \bar 1 23]- and [$ \bar 1 $ \bar 1 24]-oriented samples, ΔT _SE decreases to 233 K and the superelasticity is observed up to T ₂ = 523 K.     

A new bronchoscopic technique for the diagnosis of bacterial pneumonia in HIV-positive patients

The aim of the present study was to evaluate in HIV-positive patients with bacterial pneumonia, the diagnostic value of a new endoscopic technique that uses a single catheter to perform a telescopic plugged catheter (TPC) followed by a modified protected bronchoalveolar lavage (mpBAL). Fifty-eight HIV-positive patients with respiratory infection were included in the study. Samples from TPC and mpBAL were cultured quantitatively. Standard bronchoalveolar lavage was performed to rule out opportunistic infections. According to the clinical and microbiological results, patients were classified in the study group (27 with bacterial pneumonia) or the control group (31 without bacterial pneumonia). Sensitivity of TPC was 56% [95% confidence intervals (CI) 37-75%] and its specificity was 100%; these figures were 56% (CI, 37-75%) and 94% (CI, 86-100%) for mpBAL. When both techniques were assessed together, sensitivity increased to 70% (CI, 53-87%). The use of a single catheter reduced the cost of the originally described pBAL procedure by approximately 50%. The use of a single catheter to perform a TPC followed by a mpBAL can improve the diagnostic yield in HIV-positive patients with bacterial pneumonia, and reduces its cost.     

Multiplexed DNA sequencing and diagnostics by hybridization with enriched stable isotope labels

A new DNA diagnostic and sequencing system has been developed that uses time-of-flight resonance ionization mass spectrometry (TOF-RIMS) to provide a rapid method of analyzing stable isotope-labeled oligonucleotides in form 1 sequencing by hybridization (SBH). With form 1, the DNA is immobilized on a nylon membrane and enriched isotope-labeled individual oligonucleotide probes are free to seek out complementary DNAs during hybridization. The major advantage of this new approach is that multiple oligonucleotides can be labeled with different enriched isotopes and can all be simultaneously hybridized to the genosensor matrix. The probes can then be simultaneously detected with TOF-RIMS with high selectivity, sensitivity, and efficiency. By using isotopically enriched tin labels, up to 10 labeled oligonucleotides could be examined in a single hybridization to the DNA matrix. Greater numbers of labels are available if rare earth isotopes are employed. In the present study, matrices containing three different DNAs were prepared and simultaneously hybridized with two different probes under a variety of conditions. The results show that DNAs, immobilized on nylon surfaces, can be specifically hybridized to probes labeled with different enriched in isotopes. Discrimination between complementary and noncomplementary sites of better than 100 was obtained in multiplexed samples. This new SBH method, which employs stable isotopic labels to locate target DNAs and TOF-RIMS to detect the labels, will be a very versatile and extensive multiplexing method.     

Mechanism of adsorption of human albumin to titanium in vitro

1. This study explored the hypothesis that atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), and C-natriuretic peptide (CNP) have differing antiproliferative and antihypertrophic effects on pulmonary artery (PA) and thoracic aorta (TA) smooth-muscle cells (SMCs). 2. Cultured cells were exposed to 5% fetal calf serum (FCS) and angiotensin II (A-II) to induce DNA and protein synthesis, respectively. 3. ANP (10(-7) M) significantly reduced thymidine uptake in TA by 31% +/- 2% (P < or = 0.01) but not in PA (P > or = 0.05). 4. In parallel experiments, BNP (10(-7) M) significantly reduced thymidine uptake in TA (-22% +/- 5%, P < or = 0.01), but not in PA cells (P > or = 0.05). 5. CNP (10(-7) M) did not significantly alter thymidine uptake in TA cells exposed to FCS, but it did significantly reduce uptake in PA (-28.5% +/- 4%) 2(P < or = 0.05). 6. Blunting by ANP (10(-7) M) of the A-II (10(-8) M)-induced increase in protein synthesis was significantly greater in PA than in TA cells. 7. However, BNP and CNP (10(-7) M) exerted similar antihypertrophic effects on TA and PA cells exposed to A-II. 8. The antiproliferative effects of BNP and ANP exceed those of CNP in TA SMCs, but CNP appears to be the most effective antiproliferative agent in PA SMCs. In addition, PA-derived SMCs are more sensitive to the antihypertrophic effects of ANP than TA-derived cells, suggesting phenotypic differences. The findings indicate that the natriuretic peptides may play complementary roles in modulating SMC proliferation and protein synthesis.     

Replication checkpoint enforced by kinases Cds1 and Chk1

Cdc2, the kinase that induces mitosis, is regulated by checkpoints that couple mitosis to the completion of DNA replication and repair. The repair checkpoint kinase Chk1 regulates Cdc25, a phosphatase that activates Cdc2. Effectors of the replication checkpoint evoked by hydroxyurea (HU) are unknown. Treatment of fission yeast with HU stimulated the kinase Cds1, which appears to phosphorylate the kinase Wee1, an inhibitor of Cdc2. The protein kinase Cds1 was also required for a large HU-induced increase in the amount of Mik1, a second inhibitor of Cdc2. HU-induced arrest of cell division was abolished in cds1 chk1 cells. Thus, Cds1 and Chk1 appear to jointly enforce the replication checkpoint.     

Reduced nicotinamide adenine dinucleotide phosphate-diaphorase activity in the paraventricular nucleus of the rat hypothalamus is modulated by estradiol

Leiomyomas represent 2% of gastric tumors. Commonly, gastric leiomyomas are clinically silent. Most often they become clinically apparent due to bleeding from ulceration of the overlying gastric mucosa. Surgical extirpation of the tumor is the standard treatment. Gastric leiomyomectomy was done routinely through open laparotomy until availability of laparoscopic equipment and techniques. Recently, there have been a few published reports regarding laparoscopic or laparoscopic-assisted removal of smooth muscle gastric tumors. There is little data, however, describing or discussing a laparoscopic approach to gastric leiomyomas located on the posterior gastric wall. We describe two different laparoscopic approaches to posterior wall gastric leiomyomas that we used in two patients. The postoperative recovery of both patients was remarkably quick and uneventful.