Cantilever beam microactuators with electrothermal and electrostatic drive

Microfabrication provides a powerful tool for batch processing and miniaturization of mechanical systems into dimensional domain not accessible easily by conventional machining. CMOS IC process compatible design is definitely a big plus because of tremendous know-how in IC technologies, commercially available standard IC processes for a reasonable price, and future integration of microma-chined mechanical systems and integrated circuits. Magnetically, electrostatically and thermally driven microactuators have been reported previously. These actuators have applications in many fields from optics to robotics and biomedical engineering. At NJIT cleanroom, mono or multimorph microactuators have been fabricated using CMOS compatible process. In design and fabrication of these microactuators, internal stress due to thermal expansion coefficient mismatch and residual stress have been considered, and the microactuators are driven with electro-thermal power combined with electrostatical excitation. They can provide large force, and in- or out-of-plane actuation. In this work, an analytical model is proposed to describe the thermal actuation of in-plane (inchworm) actuators. Stress gradient throughout the thickness of monomorph layers is modeled as linearly temperature dependent Δσ. The nonlinear behaviour of out-of-plane actuators under electrothermal and electrostatic excitations is investigated. The analytical results are compared with the numerical results based on Finite Element Analysis. ANSYS, a general purpose FEM package, and IntelliCAD, a FEA CAD tool specifically designed for MEMS have been used extensively. The experimental results accompany each analytical and numerical work. Micromechanical world is three dimensional and 2D world of IC processes sets a limit to it. A new micromachining technology, reshaping, has been introduced to realize 3D structures and actuators. This new 3D fabrication technology makes use of the advantages of IC fabrication technologies and combines them with the third dimension of the mechanical world. Polycrystalline silicon microactuators have been reshaped by Joule heating. The first systematic investigation of reshaping has been presented. A micromirror utilizing two reshaped actuators have been designed, fabricated and characterized

Combined surgical treatment for missed rupture of triceps tendon associated with avulsion of the ulnar collateral ligament and flexor-pronator muscle mass

Triceps tendon ruptures are rare injuries. Coexistence of ipsilateral ulnar collateral ligament injury is even rarer. Here, we describe an unusual combination injury to elbow of a 39-year-old male construction worker consisting of triceps tendon rupture, avulsion of elbow ulnar collateral ligament and flexor pronator muscle origin ipsilaterally. A simultaneous repair and reconstruction of all damaged structures was proposed with individualized postoperative rehabilitation. Return to pre-injury level of activities obtained with this treatment protocol. High degree of suspicion and careful examination were needed to prevent missed diagnosis and prolonged instability which may be inevitable after inappropriate treatment of such injury

Ocean current connectivity propelling the secondary spread of a marine invasive comb jelly across western Eurasia

Aim: Invasive species are of increasing global concern. Nevertheless, the mechanisms driving furtherdistribution after the initial establishment of non-native species remain largely unresolved, especiallyin marine systems. Ocean currents can be a major driver governing range occupancy, but this hasnot been accounted for in most invasion ecology studies so far. We investigate how well initialestablishment areas are interconnected to later occupancy regions to test for the potential role ofocean currents driving secondary spread dynamics in order to infer invasion corridors and thesource–sink dynamics of a non-native holoplanktonic biological probe species on a continental scale.Location: Western Eurasia.Time period: 1980s–2016.Major taxa studied: ‘Comb jelly’ Mnemiopsis leidyi.Methods: Based on 12,400 geo-referenced occurrence data, we reconstruct the invasion historyof M. leidyi in western Eurasia. We model ocean currents and calculate their stability to match thetemporal and spatial spread dynamics with large-scale connectivity patterns via ocean currents.Additionally, genetic markers are used to test the predicted connectivity between subpopulations.Results: Ocean currents can explain secondary spread dynamics, matching observed range expansionsand the timing of first occurrence of our holoplanktonic non-native biological probe species,leading to invasion corridors in western Eurasia. In northern Europe, regional extinctions after coldwinters were followed by rapid recolonizations at a speed of up to 2,000 km per season. SourceJASPERS ET AL. | 815areas hosting year-round populations in highly interconnected regions can re-seed genotypes overlarge distances after local extinctions.Main conclusions: Although the release of ballast water from container ships may contribute tothe dispersal of non-native species, our results highlight the importance of ocean currents drivingsecondary spread dynamics. Highly interconnected areas hosting invasive species are crucial forsecondary spread dynamics on a continental scale. Invasion risk assessments should considerlarge-scale connectivity patterns and the potential source regions of non-native marine species

Seismic evidence of shallow gas in the sediment on the shelf off Trabzon, southeastern Black Sea

High-resolution seismic surveys carried out on the shelf off Trabzon (southeastern Black Sea) show that the sub-bottom stratigraphy consists of two main depositional sequences (A and B) one of which contains zones of acoustic turbidity. Of these, the upper depositional sequence (A) is thought to comprise Holocene sediments, while the lower depositional sequence (B) is interpreted as approximating to the Pleistocene. The boundary between these sequences is defined by a reflector (R), which is interpreted as the pre-Holocene erosional surface. The acoustic turbidity observed on seismic profiles is interpreted as representing gas accumulations in the sediments of the upper depositional sequence. Previous geochemical investigations in the area indicate that acoustic turbidity implies biogenic methane gases in bubble form. On the basis of published hypotheses on the generation of the methane gases, it is suggested that the upper boundary of the zone of acoustic turbidity on seismic profiles in this study corresponds to the boundary between a biogenic sulfate-reducing zone and the underlying carbonate-reducing zone. Apart from acoustic turbidity, some bright spot anomalies which are also interpreted to arise from the presence of methane gases within the upper depositional sequence are observed on the seismic records collected from the shelf off Trabzon

Sea-floor sediments and bedforms around Turkey, revealed by side-scan sonar imagery

The use of side-scan sonar imagery to construct facies and bedform maps of an area of sea floor has been known for some considerable time. Such maps reveal the type of sediments and bottom morphology, allowing sedimentologists to infer the sedimentation processes.The use of side-scan sonar imagery to construct facies and bedform maps of an area of sea floor has been known for some considerable time. Such maps reveal the type of sediments and bottom morphology, allowing sedimentologists to infer the sedimentation processes. Side-scan sonar imageries presented here were collected by an EG and G Mark lB Side Scan Sonar System from the Mersin Bay, Akkuyu Bay, Anamur Bay, Teknecik Bay and the Strait of Bosphorus. The distribution of the sea-floor sediments in the bays was found to be closely related to local sediment supply, waves and current dynamics, as well as the topography of the sea floor. The presence of bedforms such as sand dunes and sand patches indicates bedload transport of sediment. Relict features, such as gravel patches, beachrock outcrops and sinkholes, were believed to have been formed during lowstand of the sea level. In the strait, gravelly sediments cover a great part of the sea floor. Sandy sediments are mainly concentrated in the channels on both sides of the sill. Occurrences of rocky surfaces and gravel patches indicate strong current activities

SEISMIC STRATIGRAPHY OF THE SOUTHEASTERN BLACK-SEA SHELF FROM HIGH-RESOLUTION SEISMIC RECORDS

High-resolution seismic reflection profiles obtained from the shelves off the Samsun and Trabzon coasts (southeastern Black Sea) have revealed the existence of two distinct reflectors (R and T)