Mum In Diameter Research Articles

A further Observation of the Structural Changes of Microvessels in the Extensor Digitorum Longus Muscle of the Aged Rat

We further examined the structural changes of microvessels in the extensor digitorum longus muscle of the aged (18 months) rat. Muscle bundles in this aged muscle constantly consisted of numerous large muscle fibers 50-60 mum in diameter and a few small muscle fibers <30 mum in diameter. Neuromuscular junctions (NMJs) in large muscle fibers often showed degenerative figures, thus degenerating muscle fibers. On the other hand, NMJs in small muscle fibers were mainly characterized by sparse and short junctional folds, being possibly in the course of regeneration. In some muscle bundles, the extracellular matrix was a little widened. Microvascular networks from arterioles to venules via capillaries seemed to vary in structural features between muscle bundles. In addition to the normal microvascular network consisting of microvessels with a round or oval vascular lumen during their course, two different types of microvascular networks were found. One type was characterized by the constriction of arterioles, capillaries and venules, probably representing a degenerative process of the microvascular network. In fact, uneven and compressed scaffolds of basal laminae of capillaries were often observed around these constricted microvessels. The other type consisted of arterioles and capillaries with an irregular slit-like vascular lumen and venules with a round or oval vascular lumen, and these capillaries had thick or two-layered basal laminae, being probably in the course of remodeling of the microvascular network. From these findings, it is suggested that the constriction and/or contraction of microvessels by smooth muscle cells and pericytes may be involved in the degeneration and remodeling of the microvascular network in the muscle bundles following degeneration and regeneration of the muscle fibers.

Electrosonic ejector microarray for drug and gene delivery

We report on development and experimental characterization of a novel cell manipulation device-the electrosonic ejector microarray-which establishes a pathway for drug and/or gene delivery with control of biophysical action on the length scale of an individual cell. The device comprises a piezoelectric transducer for ultrasound wave generation, a reservoir for storing the sample mixture and a set of acoustic horn structures that form a nozzle array for focused application of mechanical energy. The nozzles are micromachined in silicon or plastic using simple and economical batch fabrication processes. When the device is driven at a particular resonant frequency of the acoustic horn structures, the sample mixture of cells and desired transfection agents/molecules suspended in culture medium is ejected from orifices located at the nozzle tips. During sample ejection, focused mechanical forces (pressure and shear) are generated on a microsecond time scale (dictated by nozzle size/geometry and ejection velocity) resulting in identical "active" microenvironments for each ejected cell. This process enables a number of cellular bioeffects, from uptake of small molecules and gene delivery/transfection to cell lysis. Specifically, we demonstrate successful calcein uptake and transfection of DNA plasmid encoding green fluorescent protein (GFP) into human malignant glioma cells (cell line LN443) using electrosonic microarrays with 36, 45 and 50 mum diameter nozzle orifices and operating at ultrasound frequencies between 0.91 and 0.98 MHz. Our results suggest that efficacy and the extent of bioeffects are mainly controlled by nozzle orifice size and the localized intensity of the applied acoustic field.

Cell Shape-dependent Control of Ca2+ Influx and Cell Cycle Progression in Swiss 3T3 Fibroblasts

The ability of adherent cells such as fibroblasts to enter the cell cycle and progress to S phase is strictly dependent on the extent to which individual cells can attach to and spread on a substratum. Here we have used microengineered adhesive islands of 22 and 45 mum diameter surrounded by a nonadhesive substratum of polyhydroxyl methacrylate to accurately control the extent to which individual Swiss 3T3 fibroblasts may spread. The effect of cell shape on mitogen-evoked Ca2+ signaling events that accompany entry into the cell cycle was investigated. In unrestricted cells, the mitogens bombesin and fetal calf serum evoked a typical biphasic change in the cytoplasmic free Ca2+ concentration. However, when the spreading of individual cells was restricted, such that progression to S phase was substantially reduced, both bombesin and fetal calf serum caused a rapid transient rise in the cytoplasmic free Ca2+ concentration but failed to elicit the normal sustained influx of Ca2+ that follows Ca2+ release. As expected, restricting cell spreading led to the loss of actin stress fibers and the formation of a ring of cortical actin. Restricting cell shape did not appear to influence mitogen-receptor interactions, nor did it influence the presence of focal adhesions. Because Ca2+ signaling is an essential component of mitogen responses, these findings implicate Ca2+ influx as a necessary component of cell shape-dependent control of the cell cycle.

Optofluidic trapping and transport on solid core waveguides within a microfluidic device

In this work we demonstrate an integrated microfluidic/photonic architecture for performing dynamic optofluidic trapping and transport of particles in the evanescent field of solid core waveguides. Our architecture consists of SU-8 polymer waveguides combined with soft lithography defined poly(dimethylsiloxane) (PDMS) microfluidic channels. The forces exerted by the evanescent field result in both the attraction of particles to the waveguide surface and propulsion in the direction of optical propagation both perpendicular and opposite to the direction of pressure-driven flow. Velocities as high as 28 mum/s were achieved for 3 mum diameter polystyrene spheres with an estimated 53.5 mW of guided optical power at the trapping location. The particle-size dependence of the optical forces in such devices is also characterized.

On-Demand DNA Synthesis on Solid Surface by Four Directional Ejectors on a Chip

This paper presents a synthesis technique for any random deoxyribonucleic acid (DNA) sequences on different substrates such as glass, plastic or silicon by an array of directional droplet ejectors. Any DNA sequence can be synthesized by ejecting droplets of DNA bases by an ultrasonic transducer having lens with air-reflectors (LWARs) that requires no nozzle. The LWAR is capable of ejecting liquid droplets around 80 mum in diameter, and reduces the amount of reagents needed for the synthesis from most of conventional microarray techniques. One major advantage of the nozzleless ejector is that it can eject droplets in any direction, so that a spot can be inked by four ejectors (carrying four DNA bases) without moving the ejector. The directional ejection of the droplets removes the need for aligning the substrate with the ejector, and minimizes the automation and control circuitry. To demonstrate the DNA synthesis capability of the directional droplet ejectors, four LWAR ejectors were used to synthesize a 15-mer 5'-CGCCAAGCAGTTCGT-3' on a substrate surface. This paper describes the concept and scheme of the on-demand DNA synthesis (with MEMS ejector integrated with microfluidic components) along with experimental results of an actual DNA synthesis by four directional droplet ejectors.

Continuous Inkjet Drop Generators Fabricated From Plastic Substrates

Fabrication of a functional continuous inkjet drop generator from plastic substrates by exclusively using micro- electromechanical systems (MEMS) processing steps is reported. Polyimide and poly(ethylene naphthalate) sheets that are laminated to a silicon carrier wafer are investigated as the drop generator substrate, and the MEMS processing methods used and associated challenges are discussed in detail. Successful generation of drops in a 600-nozzles-per-inch array that are as small as 2.4 pL in volume (16.5 mum in diameter) at drop velocities of 15.5 m/s is realized with these devices.

Electrical and Optical Chip I/O Interconnections for Gigascale Systems

This paper describes fully compatible, high-density, electrical, and optical chip input/output (I/O) interconnect networks for gigascale systems. All optical I/O interconnects are based on the use of low-loss microscopic polymer pins (pillars). Their compatibility with electrical solder-bump fabrication and assembly are demonstrated. Moreover, we describe the use of metal-coated polymer pins to provide both an electrical path and an optical path between the chip and the substrate. Such I/O interconnects are called dual-mode I/Os. The tradeoffs between the electrical resistance and mechanical compliance of the dual-mode pins are reported. Moreover, the minimum thickness of metal needed to enable each I/O to operate at its electrical bit-rate limit is derived. A chip containing dual-mode I/Os is assembled on a substrate containing electrical and optical interconnects and demonstrates the dual-mode functionality of the I/Os. Dual-mode polymer pins that are 55 mum in diameter and 110 mum in height are measured to have an electrical resistance of approximately 50 mOmega and attenuate the optical intensity by less than 0.15 dB (632.8-nm wavelength). The use of an optical-bonding polymer is shown to improve optical coupling efficiency by up to 2 dB. Lateral and vertical compliance measurements of the polymer pin are also reported.

Haptic guidance for improved task performance in steering microparticles with optical tweezers

We report the manipulation of 4-5 mum diameter polymer microspheres floating in water using optical tweezers (OT) and a haptic device (i.e. force-reflecting robotic arm). Trapped microspheres are steered using the end-effector of a haptic device that is virtually coupled to an XYZ piezo-scanner controlling the movements of the fluid bed. To help with the manipulations, we first calculate a collision-free path for the particle and then display artificial guidance forces to the user through the haptic device to keep him/her on this path during steering. Experiments conducted with 8 subjects show almost two-fold improvements in the average path error and average speed under the guidance of haptic feedback.

Decoupling of the Liquid Response of a Superhydrophobic Quartz Crystal Microbalance

Recent reports using particle image velocimetry and cone-and-plate rheometers have suggested that a simple Newtonian liquid flowing across a superhydrophobic surface demonstrates a finite slip length. Slippage on a superhydrophobic surface indicates that the combination of topography and hydrophobicity may have consequences for the coupling at the solid--liquid interface observed using the high-frequency shear-mode oscillation of a quartz crystal microbalance (QCM). In this work, we report on the response of a 5 MHz QCM possessing a superhydrophobic surface to immersion in water--glycerol mixtures. QCM surfaces were prepared with a layer of SU-8 photoresist and lithographically patterned to produce square arrays of 5 mum diameter circular cross-section posts spaced 10 microm center-to-center and with heights of 5, 10, 15, and 18 microm. Non-patterned layers were also created for comparison, and both non-hydrophobized and chemically hydrophobized surfaces were investigated. Contact angle measurements confirmed that the hydrophobized post surfaces were superhydrophobic. QCM measurements in water before and after applying pressure to force a Cassie-Baxter (non-penetrating) to Wenzel (penetrating) conversion of state showed a larger frequency decrease and higher dissipation in the Wenzel state. QCM resonance spectra were fitted to a Butterworth-van Dyke model for the full range of water-glycerol mixtures from pure water to (nominally) pure glycerol, thus providing data on both energy storage and dissipation. The data obtained for the post surfaces show a variety of types of behavior, indicating the importance of the surface chemistry in determining the response of the quartz crystal resonance, particularly on topographically structured surfaces; data for hydrophobized post surfaces imply a decoupling of the surface oscillation from the mixtures. In the case of the 15 microm tall hydrophobized post surfaces, crystal resonance spectra become narrower as the viscosity-density product increases, which is contrary to the usual behavior. In the most extreme case of the 18 microm tall hydrophobized post surfaces, both the frequency decrease and bandwidth increase of the resonance spectra are significantly lower than that predicted by the Kanazawa and Gordon model, thus implying a decoupling of the oscillating surface from the liquid, which can be interpreted as interfacial slip.

Description of a new lung fluke species, Paragonimus vietnamensis sp. nov. (Trematoda, Paragonimidae), found in northern Vietnam

Based on morphology of metacercariae and adult worms together with molecular data from our previous study, we describe herein a new lung fluke species named Paragonimus vietnamensis sp. nov. Metacercariae of this new species is round and extremely large in size (nearly 800 mum in diameter) having a fragile outer cyst of variable thickness and a thin fragile inner cyst. There are little or no space between metacercaria and the inner cyst wall. These and other morphological features of metacercariae of P. vietnamensis sp. nov. are not completely identical with but have some similarities with those of P. microrchis, P. proliferus, or P. menglaensis. On the other hand, adult worms obtained by experimental infection of these large metacercariae are oval in shape, having a ventral sucker slightly larger than the oral one, and having singly arranged relatively short cuticular spines. These morphological features of adult worms are partly similar to but not identical with those of P. microrchis, P. skrjabini, P. yunnanenis, P. xiangshanensis, or P. harinasutai. Taken these morphological data and our previous molecular phylogenetic analyses of ITS2 and CO1 sequences of metacercariae and adult worms together, P. vietnamensis sp. nov. is different from any other known Paragonimus spp.

Transport Properties up to 1000 A of ${\rm Nb}_{3}{\rm Sn}$ Wires Under Transverse Compressive Stress

The effect of transverse compressive stress on the superconducting transport currents of multifilamentary Nb3Sn wires have been measured at 19 T using a newly developed probe allowing gauge lengths as long as 125 mm. Two different wire types have been studied: an experimental Bronze Route wire (from our laboratory) with 14'641 filaments of 4.5 mum diameter and a RRP internal Sn wire (from OST), with 60 filament bundles, each having a diameter of 70 mum. It was found that the RRP wire exhibits higher stress sensitivity. For the Bronze Route wire our data also comprise a comparison of the Ic behavior for rectangular and round cross sections. The problem of current transfer has been solved using a new type of Walters spring (one turn). The spring has been cut parallel to the wire sample into two parts so the measured sample length covers a whole turn. One part can be moved axially and forces up to 40 kN are applicable. The new device will be used for the investigation of various types of superconducting wires, comprising Nb3Sn and Nb3Al, in view of their application in systems with high transverse compressive forces, in particular high field dipoles (e.g. NED).

Superferric Quadrupole Magnet With a Pulse Repetition Rate of 10 Hz for High Energy Particle Accelerators

The study of superferric synchrotron magnets with a pulse repetition rate up to 20 Hz is performed at the Laboratory of High Energies of the JINR during the last years. The magnet feature is a low inductance superconducting coil made of a high current hollow cable, cooled with two-phase helium flow at 4.5 K. After the successful tests of fast-cycling 1.4 m model dipoles at the field ramp up to 7 T/s, a proper quadrupole is under design and construction. The new magnet yoke length is about 420 mm and the distance between the pole shoes is 90 mm. The cable comprises 24 wires of 0.73 mm diameter are wound around a copper-nickel tube with an outer diameter of 5 mm. The wire consists of 10374 NbTi filaments of 4.2 mum diameter. It is expected that the new 32 T/m quadrupole magnet will operate at pulse repetition rate up to 10 Hz providing the field gradient ramp of 600 T/m per second. The first tests have been carried out in August 2006. Status of the work and obtained results are presented and discussed.

Development of SFQ Multi-Chip Modules for Quantum Bits

We developed a multi-chip module (MCM) system of superconducting quantum bits with single-flux quantum (SFQ) interface circuits. The MCM system consists of chips with quantum bits and chips with SFQ circuits mounted on a base chip by flip-chip bonding (FCB) with superconducting solder. We report on a reliability test of the MCM system. The test was done using a resistance measurement of an MCM with 30 mum diameter bumps. Tested samples showed good durability against thermal cycles between room temperature and 4.2 K. At 4.2 K, the resistance measured through more than two hundred bumps in a series was less than 1 mOmega. Along with achieving a high reliability, reducing thermal interference from SFQ circuits to quantum bits is important. We must understand the thermal conductance between and within the chips to design a system with minimum interference. An MCM on-chip thermometer which is based on the Johnson noise thermometry, has been designed and fabricated to achieve this desired level. The preliminary results of the thermal measurement are reported.

Simultaneous Addition of B$_{4}$C$+$SiC to MgB$_{2}$ Wires and Consequences for ${\rm J}_{\rm c}$ and ${\rm B}_{\rm irr}$

The simultaneous addition of various carbon based additives (in the present case B4C + SiC) to Mg and B powders has been introduced as a new concept in view of enhancing the superconducting parameters Bc2, Birr and Jc values of in situ Fe/MgB2 wires. A series of Fe sheathed monofilamentary wires of 1.1 mm diameter with a MgB2 core of 600 mum diameter was prepared with various B4C : SiC ratios, the relation being 2.5:7.5, 5:5, 7.5:2.5 and 7.5:7.5 (values in wt.%). After reaction of 1 hour at 760degC, the wire containing 7.5 wt.% B4C and 2.5 wt.% SiC powders exhibited a Jc value of 1 times 104 A/cm2 at 11.3 T and 4.2 K. Although only 2.5 wt.% SiC were added, these values are considerably above those of ternary wires with B4C additions, where the same Jc value is obtained at 10 T. The slope Jc vs. B for the B4C + SiC wires is steeper than for SiC additives, the Jc values at 4.2 K being superior at fields below 9 T. The lattice parameters a of the B4C + SiC added wires exhibit lower values than ternary wires with the same nominal C content, suggesting a higher C content in the MgB2 phase. The disorder in the MgB2 structure has been characterized as a partial substitution of B by Carbon. A reduction of the domain sizes in the c direction as well as in-plane to 250 Aring and 124 Aring has been determined from the FWHM and the breath values of the (110) and (002) peaks. With the simultaneous introduction of B4C + SiC, a strong improvement of Jc and Birr has been obtained with respect to B4C additions. A further enhancement of Jc is expected when using different combinations of additives with and without carbon, aiming for a further raise of Jc in wires with multiple additives, as a result of the combination of different mechanisms.

Characterization of a new SUMO-1 nuclear body (SNB) enriched in pCREB, CBP, c-Jun in neuron-like UR61 cells

The neuron-like UR61 cell is a stable PC12 subline that contains a mouse N-ras oncogene. Dexamethasone (Dex) treatment induces a neuron-like differentiation, which is associated with neuritogenesis and nuclear expression of the glucocorticoid receptor and c-Jun. In differentiated UR61 cells, small ubiquitin-like modifiers 1 (SUMO-1) is concentrated in a new category of SUMO-1 nuclear bodies (SNBs) distinct from promyelocytic leukemia (PML) bodies by their large size and absence of PML protein. SNBs are 1 to 3 mum in diameter and exhibit a fine granular texture by electron microscopy. They are free of splicing factors and transcription foci and show spatial associations with Cajal bodies. In addition to SUMO-1 and the E2-conjugating enzyme Ubc9, which is essential for sumoylation, SNBs concentrate the transcriptional regulators CBP, CREB, and c-Jun. Moreover, transfection experiments demonstrate that SNBs accumulate the active conjugating form of SUMO-1 but not the conjugation defective variant of SUMO-1, supporting that SNBs are sites of sumoylation. Our results suggest that SNBs play a role in the control of the nucleoplasmic concentration of transcription regulators involved in neuroprotection and survival of the UR61 cells.

Parametric imaging of contrast ultrasound for the evaluation of neovascularization in liver tumors

To assess the efficacy of parametric imaging for the diagnosis of neovascularization in liver tumors. The subjects were 17 rabbits (five with normal liver and 12 with VX2 tumor implanted in the liver). The contrast agents used were SonoVue (Bracco, Milan, Italy). A diagnostic ultrasound system was used with a programmable replenishment sequence. The images obtained between the initial frame after the high mechanical index (MI) scan, which diminishes microbubbles in the scan volume, and the current frame were coded in color according to the arrival and peak times. After the experiment, the tumors were excised and sectioned. Sections were prepared for light microscopy with hematoxylin-eosin (HE) staining and CD31 staining to evaluate vascular density. Arrival time imaging (ATI) delineated the fine blood vessels (100-200 mum in diameter) in all of the rabbits. Tortuous and meandering tumor vessels were visualized in the VX2 tumors. Differences of perfusion velocity between tumor tissue and tumor-free areas were shown in peak time imaging (PTI). Vascularity evaluated on the ATI and perfusion speed recognized on the ATI and PTI were related to the vascular density measured by pathological investigation. Parametric imaging is a promising new method for the visualization of perfusion and the estimation of tumor blood vessels.

Treatment of Resistant Port-Wine Stains with a Variable-Pulse Pulsed Dye Laser

The conventional pulsed dye laser (PDL), operating at a wavelength of 585 nm and a pulse duration of 0.45 ms, usually does not achieve complete clearance in the majority of port-wine stains (PWSs). In this study, we demonstrate the efficacy of a variable-pulse pulsed dye laser (VPPDL) equipped with cryogen spray cooling (CSC) in the treatment of PWS that have become resistant to PDL treatment. Forty Asian patients with Fitzpatrick skin types III to IV were enrolled in this study. All patients had previously been treated by the PDL at least eight times (mean, 12.8+/-5.9) and had reached a treatment plateau. A VPPDL with a wavelength of 595 nm and a spot size of 7 mm was used. The patients were treated with fluences between 9 and 15 J/cm(2) and pulse durations of 1.5 to 10 ms. Four treatments were administered at 8-week intervals for each lesion. Three months after the last treatment, all patients were evaluated for the degree of improvement by two independent clinicians. Eight patients had excellent improvement, 9 had good improvement, 11 had fair improvement, and 12 had poor improvement. No complications were observed during the course of laser treatment. Vessels larger than 30 microm were not seen in the biopsy specimens obtained after the final treatment. The VPPDL is more effective than the PDL and the VPPDL should be used for treating PDL-resistant PWSs. Nonetheless, vessels less than 30 mum in diameter are resistant to both PDL and VPPDL treatment.

Lung Function Growth in Children with Long-Term Exposure to Air Pollutants in Mexico City

Although short-term exposure to air pollution has been associated with acute, reversible lung function decrements, the impact of long-term exposure has not been well established. To evaluate the association between long-term exposure to ozone (O(3)), particulate matter less than 10 mum in diameter (PM(10)), and nitrogen dioxide (NO(2)) and lung function growth in Mexico City schoolchildren. A dynamic cohort of 3,170 children aged 8 years at baseline was followed from April 23, 1996, through May 19, 1999. The children attended 39 randomly selected elementary schools located near 10 air quality monitoring stations and were visited every 6 months. Statistical analyses were performed using general linear mixed models. After adjusting for acute exposure and other potential confounding factors, deficits in FVC and FEV(1) growth over the 3-year follow-up period were significantly associated with exposure to O(3), PM(10), and NO(2). In multipollutant models, an interquartile range (IQR) increase in mean O(3) concentration (IQR, 11.3 ppb) was associated with an annual deficit in FEV(1) of 12 ml in girls and 4 ml in boys, an IQR range (IQR, 36.4 microg/m(3)) increase in PM(10) with an annual deficit in FEV(1) of 11 ml in girls and 15 ml in boys, and an IQR range (IQR, 12.0 ppb) increase in NO(2) with an annual deficit in FEV(1) of 30 ml in girls and 25 ml in boys. We conclude that long-term exposure to O(3), PM(10), and NO(2) is associated with a deficit in FVC and FEV(1) growth among schoolchildren living in Mexico City.

Towards woven logic from organic electronic fibres

The use of organic polymers for electronic functions is mainly motivated by the low-end applications, where low cost rather than advanced performance is a driving force. Materials and processing methods must allow for cheap production. Printing of electronics using inkjets or classical printing methods has considerable potential to deliver this. Another technology that has been around for millennia is weaving using fibres. Integration of electronic functions within fabrics, with production methods fully compatible with textiles, is therefore of current interest, to enhance performance and extend functions of textiles. Standard polymer field-effect transistors require well defined insulator thickness and high voltage, so they have limited suitability for electronic textiles. Here we report a novel approach through the construction of wire electrochemical transistor (WECT) devices, and show that textile monofilaments with 10-100 mum diameters can be coated with continuous thin films of the conducting polythiophene poly(3,4-ethylenedioxythiophene), and used to create micro-scale WECTs on single fibres. We also demonstrate inverters and multiplexers for digital logic. This opens an avenue for three-dimensional polymer micro-electronics, where large-scale circuits can be designed and integrated directly into the three-dimensional structure of woven fibres.

A Complex Muscle Fiber Network in the Cricothyroid Muscle: A Scanning Electron Microscopic Study

To examine the three-dimensional ultrastructure of cricothyroid (CT) muscle fibers to elucidate their morphologic characteristics with regard to the specific functions of the muscle. An anatomic animal study. The CT muscles of five adult rats were processed using the HCl-hydrolysis method to remove the peri- and intramuscular connective tissue components. The fine muscle fiber arrangements were observed by scanning electron microscopy. Complex muscle fiber interconnections (myomyous junctions) were identified in the muscles. Myomyous junctions were characterized by the connection of many villous processes that were 1 to 2 mum in diameter and 2 to 4 mum in length with a serrated appearance at the ends of a lateral branch or a bifurcating trunk of the muscle fibers. Myomyous junctions form a complex muscle fiber network, which is thought to synchronize the activity of the CT muscle fibers. This is the first three-dimensional demonstration of the muscle fiber network in the CT muscle; this network may play a major role in the functional specificity of the CT muscle.