Concave Tip Research Articles

Immediate effect of extracorporeal shockwave therapy in patients with chronic non-specific low back pain: A randomised placebo-controlled triple-blind trial

Objective To compare the immediate effects of shockwave therapy using two different tips in patients with chronic non-specific low back pain. Design Randomised placebo-controlled study with three intervention groups. Setting The patients recruited for this study were sent for physiotherapy treatment at primary care between May and July 2022. Participants Eighty-one patients with chronic non-specific low back pain aged 18–80 years with pain for ≥3 months and pain intensity ≥3 were randomly recruited for the study. Intervention The patients received a single intervention of radial shockwave therapy with 2000 discharges at 100 mJ energy and 5 Hz frequency using concave or convex tips or placebo treatment. Main measures The primary outcome was pain intensity immediately post-intervention. The secondary outcomes were pressure pain threshold, temporal summation of pain, and functional performance. Data were collected at baseline and post-intervention. Results The post-intervention pain intensity in the concave tip group is an average of two points lower (95% CI = −3.6, −0.4; p < 0.01) than that in the placebo group. The post-intervention pressure pain threshold for the concave tip group was an average of 62.8 kPa higher (95% CI = 0.4, 125.1; p < 0.05) than for the convex tip group and 76.4 kPa higher (95% CI = 14, 138.7; p < 0.01) than in the placebo group. Conclusion The concave tip shockwave therapy is effective in reducing pain and local hyperalgesia in patients with chronic non-specific low back pain.

A Shock Loss Reduction Method Using a Concave Suction Side Profile for a Zero Inlet Swirl Turbine Rotor

Abstract A zero inlet swirl turbine rotor (ZISTR) works with axial inlet gas flow directly exhausted from a combustion chamber without any upstream vanes. The suction side trailing edge shock of the ZISTR generates a significant amount of aerodynamic loss. A shock loss reduction method is presented for the ZISTR. The principle of the method is to replace the single shock by double shocks. For minimizing the shock loss, the strength of the double shocks is set to be equal. This is based on a design criterion that multiple shocks should be with equal strength to achieve the minimum shock loss. This design criterion has been widely used for supersonic inlet design, but it is first extended to the transonic turbine design in the present article. A shock model, using aerodynamic relations of oblique shock, is put forward to quantitatively determine the shape of the concave suction-side profile. Numerical simulations indicate that the concave suction-side profile induces a new shock upstream of the suction-side trailing edge shock, and these two shocks are with nearly equal strength in the improved ZISTR. The shock loss of the improved ZISTR is obviously reduced. The concave tip profile would redistribute the blade load on the tip and increase the tip leakage flow loss. Hence, it is suggested that the concave profiles should be designed between 0% and 80% blade span, and the tip profile should keep unchanged. The improved ZISTR with an unchanged tip profile achieves an improvement of turbine efficiency by 0.8% at the design condition.

Focused Electric Field Ablation: A Novel Technology to Increase Ablation Lesion Depth With Improved Safety

Background: RF ablation is limited in its ability to deliver deep lesions, as most of the energy delivered to the tissue is dissipated in the first few millimeters from the catheter tip. Focused Electric Field (FEF) is a novel technology with the potential to ablate much deeper than current RF catheters. This work is the first proof of concept of FEF technology. Objective: To introduce FEF technology and demonstrate its feasibility as an ablation tool. Methods: We constructed an FEF catheter with a hemispherical concave tip. We performed ablation ex vivo in porcine hearts and examined ablation characteristics using both tissue sectioning and real-time thermal imaging. Results: RF lesions were 9.1{plus minus}1.0mm wide by 6.1{plus minus}1.1mm deep with ablation using an irrigated tip catheter (Thermocool SF). In contrast, lesions created using FEF ablation were 16.1{plus minus}2mm wide and 15.2{plus minus}1.1mm deep. Steam pops were much less frequent with FEF technology (6.7% incidence for FEF vs. 38% with Thermocool). Thermal imaging demonstrated that in contrast to an irrigated tip RF catheter, the FEF catheter generated a uniform temperature profile down to a maximum depth exceeding 15mm. Conclusion: This study is the first proof of concept of FEF technology. Using a novel concave catheter tip design the electric field remains confined to a narrow tissue region thus avoiding the rapid fall off in energy delivery from the tissue surface that is inherent to current RF technology. FEF ablation has the potential to allow significantly deeper ablation than current RF catheter technologies with an improved safety margin.

Parametric study of 3D printed microneedle (MN) holders for interstitial fluid (ISF) extraction

The need for novel, minimally invasive diagnostic, prognostic, and therapeutic biomedical devices has garnered increased interest in recent years. Microneedle (MN) technology has stood out as a promising new method for drug delivery, as well as extraction of interstitial fluid (ISF). ISF comprises a large portion of the extracellular fluid in living organisms yet remains inadequately characterized for clinical applications. Current MN research has focused on the fabrication of needles with different materials like silicone, carbon, and metals. However, little effort has been put forth into improving MN holders and patches that can be used with low cost MNs, which could effectively change how MNs are attached to the human body. Here, we describe different 3D-printed MN holders, printed using an MJP Pro 2500 3D printer, and compare the ISF extraction efficiencies in CD Hairless rats. We varied design parameters that may affect the skin-holder interface, such as throat thickness, tip curvature, and throat diameter. MN arrays, with insertion depths of 1500 μm, had extraction efficiencies of 0.44 ± 0.35, 0.85 ± 0.64, 0.32 ± 0.21, or 0.44 ± 0.46 µl/min when designed with flat, concave, convex, or bevel profile geometries, respectively. Our results suggest ISF extraction is influenced by MN holder design parameters and that a concave tip design is optimal for extracting ISF from animals. The future direction of this research aims to enable a paradigm in MN design that maximizes its efficiency and engineering performance in terms of volume, pressure, and wearability, thereby automatizing usage and reducing patient intervention to ultimately benefit remote telemedicine.

Selective Liquid Sliding Surfaces with Springtail-Inspired Concave Mushroom-Like Micropillar Arrays.

Herein, a mushroom-like reentrant structure is proposed, inspired by springtails, to create a selective liquid sliding surface by implementing a simple yet sturdy silicon fabrication and lithography method. The fabricated arrays display high structural fidelity, presenting a novel geometry of a concave tip. The mushroom-like head shape of these structures is found to have superomniphobicity, which is independent of a variation of temperatures for even low surface tension liquids such as mineral oil. A design rule for the novel cap of the proposed structures, which results in a selective liquid sliding property with deionized (DI) water and mineral oil, is also investigated. It is demonstrated that oil starts to slide at a roll-off angle (ROA) 10° and then DI water rolls off at ROA 15° on the same fabricated transparent and flexible surface with repeatable durability.

Intracellular offspring released from SFB filaments are flagellated.

The gut commensal segmented filamentous bacterium (SFB) attaches to the ileal epithelium and potently stimulates the host immune system. Using transmission electron microscopy (TEM), we show that mouse and rat SFB are flagellated above the concave tip at the unicellular intracellular offspring (IO) stage and that flagellation occurs prior to full IO differentiation and release of IOs from SFB filaments. This finding adds a missing link to the SFB life cycle.

A New Subcritical Nanostructure of Graphene—Crinkle-Ruga Structure and Its Novel Properties

AbstractHere, we report an experimental characterization of a new subcritical graphene nanostructure termed a crinkle ruga. Multilayer graphene forms crinkles as a periodic mode of buckling if the ratio of periodic buckling span to thickness is smaller than a critical value. Otherwise, it forms wrinkles. The crinkles have sawtooth-shaped profiles with their faces perfectly flat and the tips of the peaks and valleys highly curved. Our AFM measurements show that the width of the curvature focusing band at the tip is very narrow, e.g. smaller than 16 nm for a 6o crinkle, indicating a strong influence of flexoelectric coupling in crinkle formation. We also found that concavity or convexity of crinkle tips, i.e. parity of the crinkle, can be controlled. Due to the flexoelectric coupling, the concave tip at the crinkle valley is positively charged, and the convex tip at the crinkle peak negatively charged. In addition, here, we demonstrate that the charges at the crinkle tips can attract macromolecules in adsorption experiments. We show linearly-aligned adsorption of C60 along crinkle valleys on an HOPG surface. In another experiment, we exhibit period-doubled adsorption of lambda DNA on an HOPG surface, possibly caused by ion kinetics involved in the DNA adsorption along the crinkle valleys.

A Surgical Cryoprobe for Targeted Transcorneal Freezing and Endothelial Cell Removal.

Purpose To examine the effects of transcorneal freezing using a new cryoprobe designed for corneal endothelial surgery. Methods A freezing console employing nitrous oxide as a cryogen was used to cool a series of different cryoprobe tip designs made of silver for high thermal conductivity. In vitro studies were conducted on 426 porcine corneas, followed by preliminary in vivo investigations on three rabbit corneas. Results The corneal epithelium was destroyed by transcorneal freezing, as expected; however, the epithelial basement membrane remained intact. Reproducible endothelial damage was optimally achieved using a 3.4 mm diameter cryoprobe with a concave tip profile. Stromal edema was seen in the pre-Descemet's area 24 hrs postfreeze injury, but this had been resolved by 10 days postfreeze. A normal collagen fibril structure was seen 1 month postfreeze, concurrent with endothelial cell repopulation. Conclusions Transcorneal freezing induces transient posterior stromal edema and some residual deep stromal haze but leaves the epithelial basement membrane intact, which is likely to be important for corneal re-epithelialization. Localized destruction of the endothelial monolayer was achieved in a consistent manner with a 3.4 mm diameter/concave profile cryoprobe and represents a potentially useful approach to remove dysfunctional corneal endothelial cells from corneas with endothelial dysfunction.

Surface properties of bionic micro-pillar arrays with various shapes of tips

Gecko-inspired micro-pillar arrays with various tip structures including spatular, spherical and concave tips were fabricated by a facile soft-molding method. The tip structures of micro-pillar arrays strongly depend on different curing processes in soft-molding using the same template. The adhesion and the wetting properties of these micro-pillar arrays are investigated by means of triboindenter and optical contact angle measurement. The results suggest that the surface properties are determined by different tip structures of micro-pillars. The spatular tip and concave tip are helpful for the adhesion enhancement and the shape of tip can control the contact angles and stabilities of water droplets on the micro-pillar arrays. In addition, the procedures demonstrate that the present route to fabricate gecko-inspired micro-pillar arrays with various tip structures is reliable and convenient. We believe that this research may pave the road to further understanding the gecko-inspired attachment systems and designing new artificial structures for dry adhesives.

Tailoring Gaussian Laser Beam Shape Through Controlled Etching of Single-Mode and Multimode Fibers: Simulation and Experimental Studies

A new class of all-fiber beam shaping devices has been realized by inverse etching the end face of single-mode and multimode fibers to form a concave cone tip. Concave tip fiber can convert a Gaussian beam profile to a flat top beam profile with a uniform intensity distribution. A flat top beam with intensity variation of approximately 5% and flat top diameter to spot diameter ratio of 67% has been achieved. This device can also change the beam shape from a Gaussian to a donut by moving the observation plane. A flat top multimode fiber beam delivery is attractive for applications which require high power and uniform intensity distribution. In single-mode fiber, concave tips could be used to reduce the beam spot size diameter, enabling efficient light coupling from a single-mode fiber to an integrated optical waveguide.

Design of a Pressure-Sensing Laparoscopic Grasper

This paper describes a magnetic, nonoperative device and control system designed to treat long-gap esophageal atresia LEA. This congenital disorder occurs in approximately 100 newborn infants every year and is characterized by a discontinuity in the esophagus between the mouth and stomach. Our device builds upon previous work investigating the use of internal permanent magnets to stretch the proximal and distal esophageal pouches together until anastomosis occurs. We implement a hydraulic standoff device for the proximal magnet assembly to control the distance between the two magnets independent of the esophageal gap size. The standoff allows for controllable, intermittent force between the two pouches and provides a layer of safety from runaway magnetic forces that could potentially damage delicate esophageal tissue. The proximal device comes in two variations: a convex tip for stretching the esophagus and a concave mating tip for meeting the distal end during anastomosis. A light emitting diode LED and phototransistor pair estimates the esophageal gap size for the duration of the procedure, and a fluid pressure sensor enables the force on the esophageal tissue to be calculated. The external control circuitry, physician interface, and pump are described that demonstrate the core functionality of the system.

Intraocular pressure in keratoconus

This study aimed to investigate intraocular pressure (IOP) measurements taken using the dynamic contour tonometer (DCT) and the non-contact tonometer (NCT) in subjects with keratoconus. Intraocular pressure was measured in 20 keratoconus subjects and 20 age-matched control subjects using the DCT and NCT instruments. Central and off-centre measures were taken with the DCT in order to highlight any systematic errors associated with corneal biomechanical factors. Measures of anterior and posterior corneal topography and thickness were also taken in each subject. No significant difference was found between the central and off-centre DCT IOP readings for the keratoconus subjects and age-matched controls (p > 0.05). The average DCT IOP was 14.2 ± 1.4 mmHg in the keratoconus subjects and 14.2 ± 1.6 mmHg in the controls. However, the average NCT readings differed significantly (p < 0.001) between the keratoconus subjects (9.2 ± 1.5 mmHg) and the controls (12.9 ± 2.4 mmHg). Intraocular pressure measurements taken with the DCT showed no significant (p > 0.05) correlation with the severity of keratoconus as determined through measures of corneal topography and thickness. Equivalent IOP measurements taken with the NCT correlated significantly with certain measures of corneal curvature and thickness in the keratoconus population. The difference between DCT and NCT IOP was strongly correlated with measures of corneal topography and thickness, with differences increasing in more advanced keratoconus. The measurements obtained with the DCT do not appear to be dependent upon corneal factors, unlike those taken with the NCT. The presence or severity of keratoconus was not correlated with DCT IOP values.

Laser beam shaping and mode conversion in optical fibers

A new class of all-fiber beam shaping devices has been realized by inverse etching the end face of single mode and multimode fibers to form a concave cone tip. Concave tip fiber can convert a Gaussian beam profile to a flat top beam profile with a uniform intensity distribution. A flat top beam with intensity variation of approx. 5% and flat top diameter to spot diameter ratio of 67% has been achieved. This device can also change the beam shape from a Gaussian to a donut by moving the observation plane. A flat top multimode fiber beam delivery is attractive for applications which require high power and uniform intensity distribution. In single mode fiber, concave tips could be used to reduce the beam spot size diameter, enabling efficient light coupling from a single mode fiber to an integrated optical waveguide.

A Novel Route to the Synthesis of Silica Nanowires without a Metal Catalyst at Room Temperature by Chemical Vapor Deposition

Silica nanowires were synthesized by employing inherent directionality of chemical vapor reaction between bis(ethylmethylamino)silane (H(2)Si[N(C(2)H(5))(CH(3))](2)) precursor and water without a metal catalyst at room temperature. The difference in the oxidation reactivity between Si-H and Si-N bonds with water leads to the formation of silica nanowires. The mean diameter and length of the silica nanowires grown for 10 min were 60-80 nm and 1.9 μm, respectively. Transmission electron microscopy revealed that the obtained nanowires had the concave tip, differing from other silica nanowires produced by a conventional vapor-liquid-solid method, and were amorphous. Energy dispersive X-ray spectroscopy, Fourier transform infrared, and X-ray photoelectron spectroscopy results also proved that the nanowires have a close composition to stoichiometric SiO(2). Silica nanowires were successfully synthesized on a poly(ethylene terephthalate) film. The nanowires can emit strong blue light and ultraviolet light under excitation at 266 nm.

Characteristics of Premixed Flames Stabilized in an Axisymmetric Curved-Wall Jet Burner with Tip Modification

The stabilization characteristics of premixed flames in an axisymmetric curved-wall jet burner have been experimentally investigated. This burner utilized the Coanda effect on top of a burner tip. The initially spherical burner tip was modified to a flat tip and a concave tip in order to improve flame stabilization by providing enough space for flow recirculation above the burner tip region. The flow characteristics have been visualized using a schlieren technique. Small-scale turbulence structure has been observed mainly in the interaction jet region (located downstream of the recirculation region) for large jet velocity (Reynolds number > 11,500). An appreciable amount of air entrainment was exhibited from the half-angle of the jet spread, approximately 20°. The averaged planar laser-induced fluorescence images of the flames for this large velocity demonstrated that the strong signal of OH radicals, representing reaction zones, existed in the recirculation zone, while it was weak in the interaction jet region due to intermittency and local extinction by the generation of small scale turbulence. The OH radical signals strengthened again in the merged jet region (downstream of the interaction jet region). In extreme cases of Reynolds number over 19,000, a unique flame exhibiting OH radicals only in the recirculation zone was observed for the concave tip. The flame stabilization has been mapped by varying jet velocity and equivalence ratio, and the result showed that the stabilization characteristics were improved appreciably from the initial spherical tip design, especially for rich mixtures. The flow fields measured by a laser Doppler velocimetry confirmed the existence of recirculation zone and the expansion of the recirculation zones for the modified tips. The temperature profile measured by a coherent anti-Stokes Raman spectroscopy exhibited an intermittent nature, especially near the recirculation zone.

Tunable growth of ZnO nanorods synthesized in aqueous solutions at low temperatures

Highly arrayed ZnO nanorods were fabricated on the Si substrate buffered with patterned ZnO film (ZnOf∕Si) via wet-chemical process. The growth behavior and morphology of single-crystal ZnO nanorods (ZNs) were investigated in terms of the annealing temperatures of the sputtered ZnO film. We found that the growth morphology of ZnO nanorods is strongly dominated by the grain size of the ZnO film on the Si substrate. The ZnOf∕Si substrate was annealed at above a critical temperature to promote the crystallization of ZnO phase, and high-resolution transmission electron microscopy demonstrated that both ZNs and ZnOf on Si substrate are coherent. Furthermore, the ZNs seem to nucleate from the concave tip near the grain boundary between two ZnO grains in the ZnO film because of higher surface energy. However, a higher annealing temperature may lead to the formation of a larger ZnO crystal due to the coplanar coalescence behavior of several individual ZnO nanorods.

Capillary force with a concave probe-tip for micromanipulation

This letter describes the measurement of capillary force with a concave probe-tip for micromanipulation. Using an electric balance, we measure the capillary force for a given gap distance between a spherical object and a concave surface coaxially fabricated on a cylinder. We used three different materials (glass, stainless steel, and polytetrafluoroethylene) to check the influence of contact angles. The results are in good agreement with the theoretical prediction expressed in the normalized form; these indicate that a concave tip can generate a much larger capillary force than a flat one, provided the tip is designed to fit the convex surface of the object; moreover the results clarify that the more wettable a material is, the greater capillary force it can generate. This suggests micromanipulation by capillary force should be more practical by using probes with concave tips specifically designed for the object.

Variation, heredity and selection of effective ingredients inMagnolis officinalis of different provenances

Bark samples ofMagnolis officinalis were collected from a 7-year-old trial plantation with 13 provenances in Jingning County of Zhejiang Province on June 25, 2000. The contents of magnolol and honokiol ofM. officinalis were analyzed by the method of HPLC (High Performance Liquid Chromatogram). The results showed that such qualitave traits as the content of magnolol, content of honokiol, total content of key phenol, and the ratio of magnolo to honokiol differ significantly between the provenances. The provenances with a sharpened leaf tip from the western part of Hubei Province has a highest content of phenols, and that with a concave leaf tip from the Lushan Mountain has a lowest content of phenol. All these four qualitative traits were genetically controlled, with a heritability between 0.8342 and 0.9871 in terms of provenance. In addition, both longitudinal and latitudinal geographical variations could be found, with longitudinal variations being dominant. As a result, 3 superior provenances from Wufeng, Enshi and Hefeng of the western part of Hubei as well as 10 high-quality individuals were

The life‐history and anatomy of Lepinotus patruelis Pearman (Psocoptera–Atropidae)

Summary. An outline of the life history of Lepinotus patruelis Pearman, (Atropidae) is given. The method of antennal growth differs from that of other psoeids described in that new segments are added to the flagellum at each moult. The anatomy of L. patruelis was investigated and the following points of particular interest are recorded:– Pigment (melanin?) granules are deposited in certain regions of the ectoderm including the wall of the stomodaeum. The midgut is the region of both food storage and digestion. The ends of the four Malpighian tubes are attached to the heart. The heart is very small, consisting of only a single chamber. There are two groups of pericardial cells near the heart and several others along the aorta. There are two pairs of labial glands, called here the basophile and acidophile labial glands, whose ducts fuse below the sub‐oesophageal ganglion to form a common median duct. The basophile glands are dorsal but do not vary in position as they do in Hyperetes. The reproductive organs of the female consist of two ovaries with five polytrophic ovarioles, two lateral oviducts, a common oviduct and a vagina with a papilla on its dorsal wall from which runs a very narrow duct to a sac‐like spermatheca. The two spermathecal “maculae” of Pearman have been shown to be the clusters of papilla bearing the individual openings of the cells of the two spermathecal glands. The reproductive organs of the male consist of two pyriform testes, two vasa deferentia, two large bipartite glandular seminal vesicles (or accessory glands) and a median ejaculatory duct with a terminal penis which is probably invaginated in the resting condition. The external genitalia of the male are adapted for gripping the papilla on which opens the spermathecal duct of the female, and the penis has a shallow concave tip which fits against the papilla. Spermatophores are complex structures which are injected in liquid form through the very narrow spermathecal duct and solidify in the spermatheca. Sperms remain stored in the spermatophores until fertilization. As first suggested by Snodgrass (1905), the Psocoptera are probably closely allied to the Anoplura. This theory is supported by similarities between the labial glands, the heart and pericardial cells and the male and female reproductive organs of the two groups.