Tubular Device Research Articles

Tubular 3D Resistive Random Access Memory Based on Rolled-Up h-BN Tube.

Due to their advantages compared with planar structures, rolled-up tubes have been applied in many fields, such as field-effect transistors, compact capacitors, inductors, and integrative sensors. On the other hand, because of its perfect insulating nature, ultrahigh mechanical strength and atomic thickness property, 2D hexagonal boron nitride (h-BN) is a very suitable material for rolled-up memory applications. In this work, a tubular 3D resistive random access memory (RRAM) device based on rolled-up h-BN tube is realized, which is achieved by self-rolled-up technology. The tubular RRAM device exhibits bipolar resistive switching behavior, nonvolatile data storage ability, and satisfactorily low programming current compared with other 2D material-based RRAM devices. Moreover, by releasing from the substrate, the footprint area of the tubular device is reduced by six times. This tubular RRAM device has great potential for increasing the data storage density, lowering the power consumption, and may be applied in the fields of rolled-up systems and sensing-storage integration.

Synthetic bioresorbable poly-α-hydroxyesters as peripheral nerve guidance conduits; a review of material properties, design strategies and their efficacy to date.

Implantable tubular devices known as nerve guidance conduits (NGCs) have drawn considerable interest as an alternative to autografting in the repair of peripheral nerve injuries. At present, there exists a lack of biodegradable, biocompatible materials for the fabrication of NGCs with physical properties which suitably match the native nerve tissue. Most of the existing reports have been confined to the traditional synthetic aliphatic polyesters due to their naturally-occurring degradation by-products, suitably slow in vivo resorption timeframes and relatively diverse and tailorable range of material properties. Moreover, these thermoplastic polymers can be processed into NGCs from various methods and further tweaking of physical properties can be achieved during fabrication. Although there have been many successful reports of nerve gap repair using NGCs made from these materials, the majority have been confined to basic tubular designs across short to medium nerve gaps with at best equivalent outcomes to autografts. This article reviews the performance of poly-α-hydroxyester tubes to date (including modifications to basic hollow conduits) and is intended to aid researchers as they aim to create biomimetic NGCs capable of bridging larger nerve gaps with superior results to autografting. Based on the existing reports, a next-generation bioresorbable NGC should involve a highly flexible poly-α-hydroxyester outer tube, most suitably from a lactide-caprolactone co-polymer, with some combination of internal lumen contact guidance and bioactive neurotrophic factors. However, detailed further experimentation and an interdisciplinary approach will be required to arrive at an ideal final configuration.

Targeting nucleolin to obstruct vasculature feeding with an intelligent DNA nanorobot.

A prototype of DNA nanorobot with the ability to transport molecular payloads was designed to target cancer cells in tissue culture. Moreover, a further step was taken to succeed in the first in vivo application of the DNA nanorobot for cancer therapy. The robot was constructed using aptamer and DNA origami to fold a 90‐nm tubular device to carry the blood coagulation protease thrombin inside, shielded from circulating platelets and plasma fibrinogen. The recognition and binding of the aptamer to its tumour‐specific target molecule triggered the robot unfolding to expose thrombin to the blood, which in turn activated coagulation at the local tumour site, resulting in tumour necrosis and inhibition of tumour growth. Since all solid‐tumour feeding vessels are virtually the same, this strategy could be effective against many types of malignant diseases.

A novel tribo-electrostatic device for the treatment of granular waste plastics mixtures

ABSTRACT The main objective of this work is the design, manufacture and functional validation of a tribo-electrostatic separator for granular mixtures, equipped with a grounded metal-belt conveyor electrode. Triboelectric charging of the materials was done using a rotary tubular device. The separation experiments were performed on a granular mixture composed of three different plastic materials polycarbonate, high-density polyethylene and polyvinyl chloride. The particles previously charged were deposited on the metal-belt conveyor that carried them through the separation region. The results obtained have shown the efficiency of this installation, which is useful for the treatment of mixtures composed of three different plastic materials.

Enteral Stenting: An Overview of Gastrointestinal Luminal Endoprostheses

Enteral stents are tubular devices that can reestablish the patency of the gastrointestinal (GI) lumen in the setting of high-grade obstruction. Although they have been more commonly used in the palliation of malignant obstruction, they now have expanding roles for benign luminal strictures and stenoses. Familiarity with the indications and contraindications for enteral stent placement can enable consideration of a less invasive and morbid therapeutic option for many patients with symptomatic obstructions. The development of self-expandable metal stents and the subsequent emergence of lumen-apposing coaxial metal stents have expanded the role of enteral stents in the management of various GI disorders. This review contains 49 references, 5 figures, and 5 tables. Key Words:coaxial, enteral, gastrointestinal malignancy, lumen-apposing, obstruction, palliation, stent

Investigating the mitigation effects of radon progeny by composite radon removal device

In this study, a tubular radon removal device and a movable one were prepared and investigated. The tubular radon removal device in an air conditioning return air system reduced the radon progeny by more than 84%. The radon progeny concentration reached equilibrium after 4 h when it was used only for a ventilation at the rate of 10 h−1. Radon progeny removal efficiency was above 95% for the movable radon removal device, when the ventilation rate was 17 h−1. The results showed that the radon removal devices can effectively remove the radon progeny in the air.

Suspension flow behavior and particle residence time distribution in helical tube devices

Manufacturing of fine chemicals and pharmaceuticals often comprises the handling of solid/liquid suspensions both in upstream and downstream processing. Continuous manufacturing of such products is promising compared to conventional batch production, even though, flow processes in tubular devices usually suffer from particle settling and clogging. The isothermal suspension flow behaviors of various solid/liquid systems, i.e., crystalline l-alanine/saturated aqueous solution, PVC beads/water, and glass beads/water, with up to 10 wt-% of particles were investigated and successfully operated in horizontal helical coil tubes without blockage. The densimetric Froude number is used to describe the flow behavior in the coiled tubes in which three different regimes were observed, i.e., homogeneous suspension flow, moving sediment flow, and stagnant sediment. Empirical correlations based on the tube diameter, the mean particle size, the particle mass fraction, the fluid flow rate, the pulsation characteristics of the utilized peristaltic pump, and the physical properties of the system were developed for the critical densimetric Froude number to define the transition between these regimes. Based on this, the particle residence time distributions (RTDS) in the different flow regimes were investigated by step-response experiments from 0 to 1 wt-% of PVC particle tracers in aqueous suspension in a horizontal coiled flow inverter (CFI). A narrow RTDS close to ideal plug flow was found. These results enable both equipment and process design in existing equipment on a short-cut model level.

Low-Voltage, Flexible, and Self-Encapsulated Ultracompact Organic Thin-Film Transistors Based on Nanomembranes.

Organic thin-film transistors (OTFTs) are an ever-growing subject of research, powering recent technologies such as flexible and wearable electronics. Currently, many studies are being carried out to push forward the state-of-the-art OTFT technology to achieve characteristics that include high carrier mobility, low power consumption, flexibility, and the ability to operate under harsh conditions. Here, we tackle this task by proposing a novel OTFT architecture exploring the so-called rolled-up nanomembrane technology to fabricate low-voltage (<2 V), ultracompact OTFTs. As the OTFT gate electrode, we use strained nanomembranes, which allows all transistor components to be rolled-up and confined into a tubular-shaped tridimensional device structure with reduced footprint (ca. 90% of their planar counterpart), without any lossof electrical performance. Such an innovative architecture endows the OTFTs high mechanical flexibility (bending radius of <30 μm) and robustness-the devices can be reversibly deformed, withstanding more than 500 radial compression/decompression cycles. Additionally, the tubular device design possesses an inherent self-encapsulation characteristic that protects the OTFT active region from degradation by UV-light and hazardous vapors. The reported strategy is also shown to be compatible with different organic semiconductor materials. All of these characteristics contribute to further extending the potentialities of OTFTs, mainly toward rugged electronics.

Enteral Stenting: An Overview of Gastrointestinal Luminal Endoprostheses

Enteral stents are tubular devices that can reestablish the patency of the gastrointestinal (GI) lumen in the setting of high-grade obstruction. Although they have been more commonly used in the palliation of malignant obstruction, they now have expanding roles for benign luminal strictures and stenoses. Familiarity with the indications and contraindications for enteral stent placement can enable consideration of a less invasive and morbid therapeutic option for many patients with symptomatic obstructions. The development of self-expandable metal stents and the subsequent emergence of lumen-apposing coaxial metal stents have expanded the role of enteral stents in the management of various GI disorders. This review contains 49 references, 5 figures, and 5 tables. Key Words: coaxial, enteral, gastrointestinal malignancy, lumen-apposing, obstruction, palliation, stent

The Impact of Intraocular Pressure Elevation on Optic Nerve Head and Choroidal Blood Flow.

To use laser speckle flowgraphy (LSFG) to assess blood flow (BF) in the optic nerve head (ONH) tissue and choroid during elevated intraocular pressure (IOP). This prospective study included 20 eyes of 20 healthy volunteers. The testing protocol had a baseline phase, two elevated IOP phases (+10 and +20 mm Hg), and a recovery phase. IOP was elevated by pushing against the eyelid with a novel tubular device attached to the LSFG apparatus. Measurement parameters in each phase included: LSFG-derived mean blur rate (MBR) and flow acceleration index (FAI); systemic parameters, and IOP. The % change against baseline was calculated for each phase. The protocol was repeated five times to calculate the coefficient of variation (CV) for % change MBR and to determine the effect of mydriasis on % change MBR. We compared % change MBR and FAI and evaluated the relationship between % change ocular perfusion pressure (OPP) and MBR in the choroid and ONH tissue. The % change MBR was highly reproducible (CV: 6.1-8.7%) and not affected by mydriasis (P = 0.57-0.96). The % change MBR and FAI were higher in the ONH tissue than choroid during IOP elevation (P = 0.04). The % change OPP and MBR showed positive linear correlations and two-segmental linear correlations in the choroid and ONH tissue, respectively (P < 0.01). Hemodynamics during IOP elevation differ in the choroid and ONH tissue. LSFG enables highly reproducible assessment of the dynamic autoregulation of ocular BF in the ONH tissue.

Chiral anisotropic magnetoresistance of ferromagnetic helices

We investigate the anisotropic magnetoresistance (AMR) of ferromagnetic CoNi microhelices fabricated by electrodeposition and laser printing. We find that the geometry of the three-dimensional winding determines a characteristic angular and field-dependence of the AMR due to the competition between helical shape anisotropy and an external magnetic field. Moreover, we show that there is an additional contribution to the AMR that scales proportionally to the applied current and depends on the helical chirality. We attribute this contribution to the self-magnetic field induced by the current, which modifies the orientation of the magnetization relative to the current flow along the helix. Our results underline the interest of three-dimensional curved geometries to tune the AMR and realize tubular magnetoresistive devices.

Reconfigurable Vanadium Dioxide Nanomembranes and Microtubes with Controllable Phase Transition Temperatures.

Two additional structural forms, free-standing nanomembranes and microtubes, are reported and added to the vanadium dioxide (VO2) material family. Free-standing VO2 nanomembranes were fabricated by precisely thinning as-grown VO2 thin films and etching away the sacrificial layer underneath. VO2 microtubes with a range of controllable diameters were rolled-up from the VO2 nanomembranes. When a VO2 nanomembrane is rolled-up into a microtubular structure, a significant compressive strain is generated and accommodated therein, which decreases the phase transition temperature of the VO2 material. The magnitude of the compressive strain is determined by the curvature of the VO2 microtube, which can be rationally and accurately designed by controlling the tube diameter during the rolling-up fabrication process. The VO2 microtube rolling-up process presents a novel way to controllably tune the phase transition temperature of VO2 materials over a wide range toward practical applications. Furthermore, the rolling-up process is reversible. A VO2 microtube can be transformed back into a nanomembrane by introducing an external strain. Because of its tunable phase transition temperature and reversible shape transformation, the VO2 nanomembrane-microtube structure is promising for device applications. As an example application, a tubular microactuator device with low driving energy but large displacement is demonstrated at various triggering temperatures.

A novel merging Tubular Daylight Device with Solar Water Heater – Experimental study

Abstract Tubular Daylight device (TDD) and solar water heater (SWH) are two power saving solutions that are commonly employed individually in residential and industrial premises. This paper proposed a novel merged power saving system consisting of TDD and SWH in one model, which is the first attempt to integrate these two systems. The idea of merging the TDD with SWH is based on utilizing the existing area around the TDD to implement the SWH around the TDD tube through a serpentine collector. The main purpose for such integration is to enhance solar energy saving, space area saving, and to decrease the fabrication cost. The illumination and thermal performance of the new proposed model were tested and analysed experimentally in different seasons in Cairo - Egypt to assess its performance in practical use. The obtained results indicated that the merged system succeeded in transferring an acceptable illumination rate and increasing the water temperature. The transferred internal illuminance has reached approximately to 6.5 W/m2 that fulfils the required needs of lighting. Additionally, the system increased the water temperature up to 62 °C, with a performance instantaneous efficiency that reached 21.17% which is very satisfactory. Furthermore, the performance of thermosyphon SWH with different serpentine collector coil number of turns has been evaluated. The results proved that, the collector number of turns has significantly affected the SWH performance in a directly proportional relation.

Proposal of the Tubular Daylight System Using Acrylonitrile Butadiene Styrene (ABS) Metalized with Aluminum for Reflective Tube Structure

In the search for alternatives to reduce the consumption of electric energy, the possibility of using natural light for lighting through TDD (tubular daylight devices) or TDGS (tubular daylight guidance systems) appears. These natural luminaires are used in rooms where you want to save electricity and enjoy the benefits of natural light. The present work proposes the construction of a tubular system for the conduction of natural light that replaces aluminum with silver (currently marketed by several companies) by polymer metallized with aluminum, offering a low cost. The polymer acrylonitrile butadiene styrene (ABS), coated with aluminum by physical vapor deposition (ionization), was evaluated for some tests to verify characteristics of the structure and the metallized surface. After the tests, the construction of the reflective tube was performed and validated in a real scale of application. The results proved the technical viability of the proposed tube construction for the realization of direct sunlight for illumination using polymeric material. Although it has produced 35% less than the reference tube, it can be marketed at an estimated cost of 50% less.

Effect of different carrier gases on productivity enhancement of a novel multi-effect vertical concentric tubular solar brackish water desalination device

A novel multi-effect vertical concentric tubular solar brackish water desalination device is introduced in present study. The device consists of four closely spaced concentric pipes, in which the feed water gets preheated by hot brine water to guarantee the evaporation efficiency. An experimental investigation and analytical analysis were carried out to signify the effect of carrier gas-water vapor mixture on productivity enhancement of the device. Different carrier gases were used in the performance evaluation: carbon dioxide, helium, nitrogen, oxygen, air and argon. The water yield and the top/bottom temperature values of condensation surface of the device with different carrier gases were tested. In addition, the present investigation is presented an approach to predict the theory yield based on the internal heat and mass transfer mechanism. The experimental results indicate that, when the heating temperature is 80 °C and the carrier gas is helium, the water productivity rate can reach to 1.19 kg/h. It is increased by 30.76% than the carrier gas of air. The numerical results had been calculated and a consistent agreement with the experimental results had been obtained of different operation temperatures. The Dv under different heating temperature were obtained according to the experimental results.

INFLUENCE OF GLICEROL ON FUNCTIONAL-MORPHOLOGICAL INDICATORS OF KIDNEYS AT MODELLING RENAL INSUFFICIENCY IN RATS

It is known, that after acute damage of kidney there is a risk of development of chronic kidney desease and death rate from its complications.&#x0D; Material and methods. Research are spent on 40 not purebred rats at modelling of acute damage of the kidneys caused by toxic doses of glycerol. To evaluate histopathologal changes , we used cuts of fabrics painted gematoksilin- eozinom. Ultrathin preparations analyzed in electronic microscope PЕМ-125К.&#x0D; Results. Administration of glycerol leads to uremia with dystrophic changes in tubular device and glomerular hypertrophy. At a stage of chronic renal insufficiency reduction of the glomerular sizes, tubulointerstitial fibrosis and glomerulosclerosis is observed.&#x0D; Conclusion. At modelling of a nephritic pathology by introduction of 50 % glycerol infringement of function of kidneys has phasic character with probable development of chronic kidney desease in 8 weeks.

Axial Backmixing and Residence Time Distribution in a Miniaturized, Stirred‐Pulsed Extraction Column

AbstractAxial backmixing is an important issue in extraction columns since it heavily affects the mass transfer performance. A miniaturized, stirred‐pulsed column was investigated regarding its backmixing characteristics in the continuous phase, using the system water/n‐butyl acetate. Residence time distributions were determined through pulse experiments with potassium chloride, which was detected via electrical conductivity. To perform the conductivity measurement without distortion of the two‐phase flow, electrodes with an annular design that precisely line up with the inner column wall were manufactured. This design is a promising alternative for use in small‐scale tubular devices where commercial electrodes do not fit and in applications where interference with the flow must be avoided.

3D Printing of Flexible Electronic Devices

AbstractCompared to traditional , simple, planar or tubular flexible devices fabricated by spin‐coating, casting, or extrusion, 3D‐printed flexible electronic devices possess complicated geometries with precisely prescribed microarchitectures and excellent mechanical properties for satisfying all kinds of individual requirements. However, the full utilization of 3D‐printing technology to realize 3D‐printed flexible electronic devices remains limited by the flexibility and conductivity of 3D‐printing materials. To achieve 3D‐printed flexible electronic devices, the flexibility of 3D‐printed flexible devices and functionalization of conductive materials or hard silicon‐based electronic devices are combined. These 3D‐printed flexible electronic devices can be applied widely in the fields of personal wearable devices, prosthetic organs for the disabled, and human–computer interfaces. To further promote the rapid advent of 3D‐printed flexible electronic devices, the recent strategies and future developmental directions of fabricating these complex electronic devices are discussed here.

Fiber-reinforced silicone for tracheobronchial stents: An experimental study.

A trachea is a tubular structure composed of smooth muscle that is reinforced with cartilage rings. Some diseases can cause sagging in smooth muscle and cartilaginous tissue. The end result is reduction (narrowing) of the trachea diameter. A solution to this problem is the use of tracheal stents, which are small tubular devices made of silicone. One is inserted into the trachea to prevent or correct its constriction. The purpose of tracheal stent use is to maintain cartilage support that would otherwise be lost in the airway. Current tracheal stent models present limitations in terms of shape and characteristics of the silicone used in their production. One of the most important is the large thickness of the wall, which makes its placement difficult; this mainly applies to pediatric patients. The wall thickness of the stent is closely related to the mechanical properties of the material. This study aims to test the reinforcement of silicone with three kinds of fibers, and then stents that were produced using fiber with the best compressive strength characteristics. Silicone samples were reinforced with polypropylene (PP), polyamide (PA), and carbon fiber (CF) at concentrations of 2% and 4% (vol%), which then underwent tensile strength and Shore A hardness testing. Samples with fiber showed good characteristics; surface analyses were carried out and they were used to produce stents with an internal diameter of 11 or 13mm and a length of 50mm. Stents underwent compression tests for qualitative evaluation. Samples with 2% and 4% CF blends showed the best mechanical performance, and they were used to produce stents. These samples presented similar compressive strengths at low deformation, but stents with a 4% CF blend exhibited improved compressive strength at deformations greater than 30-50% of their diameter (P ≤ 0.05). The addition of 2% and 4% CF blends conferred greater mechanical strength and resistance to the silicone matrix. This is particularly true at low deformation, which is the condition where the stent is used when implanted. In the finite element compression strength tests, the stent composite showed greater compression strength with the addition of fiber, and the results were in accordance with mechanical compression tests performed on the stents. In vivo tests showed that, after 30 days of post-implantation in sheep trachea, an inflammatory process occurred in the region of the trachea in contact with the stent composite and with the stent without fiber (WF). This response is a common process during the first few days of implantation.

A novel ultra-thin-walled ZnO microtube cavity supporting multiple optical modes for bluish-violet photoluminescence, low-threshold ultraviolet lasing and microfluidic photodegradation

ZnO optical microcavities have shown great promise as a potential core component material/structure for ultraviolet lasers, light-emitting diodes and photonic sensors because of their outstanding optoelectronic properties. Here, we report a novel ultra-thin-walled ZnO (UTW-ZnO) microtube cavity with a wall thickness of ~750 nm, supporting multiple types of optical modes, including in-tube Fabry–Perot modes, in-wall Fabry–Perot modes and wave-guided whispering gallery modes (WG-WGMs). The free-exciton recombination rate and exciton–exciton collisions are promoted in the cavity. The intensities of near-band edge (ultravoilet (UV) light) and X-band (blue light) emission are therefore increased at least one order of magnitude in the temperature range of 0–500 °C. Meanwhile, the temperature-sensitive multicolor luminescence of the UTW-ZnO microtubes in the visible band from near-white to bluish-violet is demonstrated for the first time. Low-threshold UV lasing is also achieved in the UTW-ZnO microtube by WG-WGMs, where the excitation threshold is down to 5.50 μW. Furthermore, light harvesting in the microtube cavity is beneficial to boosting the ZnO catalytic performance for photodegradation of organic dyes. The UTW-ZnO microtube exhibits compatibility to microfluidic channels for recyclable on-chip degradation. The present work provides new opportunities to design novel tubular wide-bandgap semiconductor devices for a variety of optoelectronic applications in micro/nanophotonics.