Symmetric Tip Research Articles

Long-term Results and Efficacy of Intermediate Rhinoplasty in Patients With Unilateral Cleft Lip: A Single Surgeon's Experience.

Intermediate rhinoplasty, the correction of cleft lip nose deformities, is performed between the time of primary and secondary rhinoplasties, which is at ~6 years of age. Although intermediate rhinoplasty reduces psychological stress in school-aged children through improvements in appearance, studies on intermediate rhinoplasty are scarce. Hence, in this study, we aimed to evaluate the long-term outcomes of intermediate rhinoplasty in patients with unilateral cleft lip. Twenty-three patients with unilateral cleft lip who underwent intermediate rhinoplasty without primary rhinoplasty from 1997 to 2004 were enrolled in this retrospective study. They were categorized into total, male, and female groups. Photogrammetric analysis of 9 proportional, 5 angular, and 6 nostril-related parameters was performed using photographs that were taken after skeletal maturity had been reached; these parameters were compared with those of normal controls. The cleft group had significantly lower dome-to-columellar ratio, nasal sill ratio, labial-columellar angle, nostril width ratio, nostril height (base) ratio, nostril one-fourth medial part ratio, and nostril area ratio measurement and significantly higher alar width/mouth width ratio, columella height/alar width ratio, nasal tip protrusion/alar base width ratio, nasal dorsum angle, and nostril dimension in the cleft side values than the control group. After intermediate rhinoplasty, significant nasal improvement was achieved, including sufficient nasal tip projection, nasal height, nasal protrusion, and a relatively symmetric nasal tip without tip deviation. Intermediate rhinoplasty may contribute to reducing the psychosocial stress of school-aged children with unilateral cleft lip.

Broadband and easily fabricated double-tip edge coupler based on thin-film lithium niobate platform

Due to the significant difference in spot size between lithium-niobate-on-insulator (LNOI) waveguide and fiber, there is a substantial coupling loss between them, which limits the interconnection and application of LN photonic chips. Although some LNOI edge couplers have been designed and fabricated with low coupling loss between chip and fiber, they require high etching accuracy. In this paper, a low-loss, broadband and easily fabricated edge coupler is designed and fabricated on the LNOI platform. To reduce the etching requirement for tip width, a design has been adopted with symmetrical double tips at the edge. Additionally, a multimode interferometer (MMI) is introduced to ensure large fabrication tolerance. The proposed design only requires a single full etching step, significantly reducing stringent requirements for process with high precise. Experimental results demonstrate that the device exhibits a coupling loss less than 3.5 dB/facet in the wavelength range of 1500–1640 nm, while achieving a low coupling loss of 2.71 dB/facet at 1550 nm.

Structure of the siphophage neck–Tail complex suggests that conserved tail tip proteins facilitate receptor binding and tail assembly

Siphophages have a long, flexible, and noncontractile tail that connects to the capsid through a neck. The phage tail is essential for host cell recognition and virus–host cell interactions; moreover, it serves as a channel for genome delivery during infection. However, the in situ high-resolution structure of the neck–tail complex of siphophages remains unknown. Here, we present the structure of the siphophage lambda “wild type,” the most widely used, laboratory-adapted fiberless mutant. The neck–tail complex comprises a channel formed by stacked 12-fold and hexameric rings and a 3-fold symmetrical tip. The interactions among DNA and a total of 246 tail protein molecules forming the tail and neck have been characterized. Structural comparisons of the tail tips, the most diversified region across the lambda and other long-tailed phages or tail-like machines, suggest that their tail tip contains conserved domains, which facilitate tail assembly, receptor binding, cell adsorption, and DNA retaining/releasing. These domains are distributed in different tail tip proteins in different phages or tail-like machines. The side tail fibers are not required for the phage particle to orient itself vertically to the surface of the host cell during attachment.

Tunneled Hemodialysis Catheter Tip Design and Risk of Catheter Dysfunction: An Australian Nationwide Cohort Study

Rationale & ObjectiveHemodialysis catheter dysfunction is an important problem for patients with kidney failure. The optimal design of the tunneled catheter tip is unknown. This study evaluated the association of catheter tip design with the duration of catheter function. Study DesignObservational cohort study using data from the nationwide REDUCCTION trial. Setting& Participants: 4722 adults who each received hemodialysis via one or more tunneled central venous catheters in 37 Australian nephrology services from December 2016 to March 2020. ExposureDesign of tunneled hemodialysis catheter tip, classified as symmetrical, step, or split. OutcomeTime to catheter dysfunction requiring removal due to inadequate dialysis blood flow assessed by the treating clinician. Analytical ApproachMixed, three-level accelerated failure time model, assuming a log-normal survival distribution. Secular trends, the intervention, and baseline differences in service, patient, and catheter factors were included in the adjusted model. In a sensitivity analysis, survival times and proportional hazards were compared among participants’ first tunneled catheters. Results355 of 3871 (9.2%), 262 of 1888 (13.9%), and 38 of 455 (8.4%) tunneled catheters with symmetrical, step, and split tip designs, respectively, required removal due to dysfunction. Step tip catheters required removal for dysfunction at a rate 52% faster than symmetrical (adjusted time ratio = 0.48, 95% CI = 0.34-0.69), and 76% faster than split tip catheters (adjusted time ratio = 0.24, 95% CI = 0.11-0.52) in the adjusted accelerated failure time models. Only symmetrical tip catheters had performance superior to step tip catheters in unadjusted and sensitivity analyses. Split tip catheters were infrequently used and had risks of dysfunction similar to symmetrical tip catheters. The cumulative incidence of other complications requiring catheter removal, routine removal, and death prior to removal were similar across the three tip designs. LimitationsTip design was not randomized. ConclusionsSymmetrical and split tip catheters had a lower risk of catheter dysfunction requiring removal than step tip catheters.Funding: Grants from government (Queensland Health, Safer Care Victoria, Medical Research Future Fund, National Health and Medical Research Council, Australia), academic (Monash University), and not-for-profit (ANZDATA Registry, Kidney Health Australia) sources. Trial RegistrationRegistered at ANZCTR with study number ACTRN12616000830493.

Diffusion-Mediated Nucleation and Growth of fcc and bcc Nanocrystal Superlattices with Designable Assembly of Freestanding 3D Supercrystals.

Diffusion-mediated assembly of octahedral PbS nanocrystals (NCs) in a confined antisolvent environment displays a primary burst nucleation and Ostwald ripening growth of rhombic bcc supercrystals, followed by a secondary seed-based nucleation and oriented attachment growth of triangle fcc supercrystals. As the diffusion proceeds from ethanol across a sharp interface into NC-suspended toluene, a burst nucleation of supercrystal seeds occurs, and such supercrystals are quickly developed into rhombic grains that have a bcc structure. At a critical size of 10 μm, an Ostwald ripening event appears to guide the supercrystal growth. Upon grain growth above 30 μm, the fcc supercrystals start a nucleation at two symmetrical tips of individual rhombic crystals. Such fcc supercrystals are developed with a triangle shape, and two triangles are combined with one bcc rhombus in-between to form a butterfly-like bowtie stacking structure. The fcc triangle wings grow larger at a reduction of bcc rhombus cores. As the bcc cores gradually fade, such butterfly-like bowtie crystals aggregate and undergo an oriented attachment process, leading to the formation of freestanding 3D triangle crystals that have a single fcc lattice. Analysis of experimental observations and defined diffusion parameters reveals that fast solvent diffusion and high-NC concentration promote the growth of rhombic bcc supercrystals, while slow solvent diffusion and low-NC concentration accelerate the development of triangle fcc supercrystals. Upon succeeding in designable growth of 3D fcc supercrystals, this study provides designing principles for controlled fabrication of supercrystals with desired superlattices for additional engineering and applications.

A bi-stable nonlinear energy sink using the cantilever bi-stable hybrid symmetric laminate

This paper develops a new bi-stable nonlinear energy sink (BNES) only consisting of the cantilever bi-stable hybrid symmetric laminate (BHSL) and tip masses. This BNES has advantages of light weight, simple and reliable structure, since it does not need external devices or magnets to maintain its bi-stable characteristic. A finite element model (FEM) is developed to perform static and dynamic analyses of a harmonically excited linear oscillator coupled with BNES. An equivalent theoretical model is developed to model the coupled system based on the relationship between the restoring force and the displacement of BHSL. The Runge-Kutta method is used to perform direct numerical solutions. Different types of the steady-state response for BNES contain the local and global periodic motions, the local and global strongly modulated responses and chaos, while the primary object exhibits the periodic motion and the strongly modulated response. The effects of the excitation amplitude, the tip mass of BNES, the lay-up design and the length of BHSL are considered on the dynamic responses and vibration suppression efficiency of BNES. The results show adjusting these parameters and lay-up designs can improve the vibration suppression efficiency of BNES. In addition, the experimental prototype is prepared and verifies the rightness of the finite element model and theoretical model.

A New Method for Symmetrical Nasal Tip Plasty: The Role of the Location and Caudal Relations

A New Method for Symmetrical Nasal Tip Plasty: The Role of the Location and Caudal Relations

Thermoelectric and stress distributions around a smooth cavity in thermoelectric material

• In this paper the thermoelectric coupling problem of an infinite homogeneous isotropic thermoelectric material with a smooth cavity and exerting a uniform current density and/or uniform energy flux is studied. • New analytical solutions are completely exact, and operable for complex shapes. • New solutions have a finite form for cavity characterized by Laurent polynomial. • The curvature of the cavity contour affects the distribution of the fields. • The maximum stress concentration appears near the points with extremal curvature. Thermoelectric materials have attracted more and more attention since they are friendly to the environment and have potentials for sustainable and renewable energy applications. As typically brittle semiconductors with low mechanical strength and always subjected to defects and damages, to clarify the stress concentration is very important in the design and implement of thermoelectric devices. The two-dimensional thermoelectric coupling problem due to a cavity embedded in an infinite isotropic homogeneous thermoelectric material, subjected to uniform electric current density or uniform energy flux, is studied, where the shape of the cavity is characterized by the Laurent polynomial, and the electric insulated and adiabatic boundary around the cavity are considered. The explicit analytic solutions of Kolosov-Muskhelishvili (K-M) potentials and rigid-body translation are carried out through a novel tactic. Comparing with the reported results, the new obtained are completely exact and possess a finite form. Some results of three typical cavities are presented to analyze the electric current densities (energy fluxes) and stresses around the tips. The main conclusions include: the distribution of thermoelectric field and stress at the tip obviously depends on the curvature of the contour and load directions; for triangle and square with symmetrical tips, the thermoelectric and stress concentration reach the maximum or minimum when the load direction is parallel to or perpendicular to the symmetry axis of the tip, which is distinct to the extremum characteristics of pentagram with bimodal of curvature around the tip; the maximum thermoelectric and stress concentration appear near the maximum curvature point for most load directions, but not at the maximum curvature point.

Characterising Penetrometer Tip Contact during Concrete Condition Assessment.

Concrete condition-assessing penetrometers need to be able to distinguish between making contact with a hard (concrete) surface as opposed to a semi-solid (corroded concrete) surface. We investigated whether different shaped tips of a cylindrical penetrometer were better than others at maintaining contact with concrete and not slipping. We designed a range of simple symmetric tip shapes, controlled by a single superellipse parameter. We performed a finite element analysis of these parametric models in SolidWorks before machining in stainless steel. We tested our penetrometer tips on a concrete paver cut to four angles at 20 increments. The results indicate that the squircle-shaped tip had the least slippage when used for concrete condition assessment.

A Case of Wellens Syndrome Combined with De Winter Syndrome

This paper reports a typical case of Wellens syndrome combined with De Winter syndrome. The male patient was admitted with "one day chest pain". He is 64 years old. He had chest pain without obvious inducement. Preliminary diagnosis: coronary heart disease unstable angina pectoris. The Electrocardiogram of this case is typical of Wellens syndrome. The patient's Electrocardiogram pseudonormalized during the onset of chest pain, and no significant ST-T changes were observed. After being admitted to hospital, chest pain was relieved. In the case of this case, when the chest pain occurred again, the electrocardiogram of the patient showed a 1-3mm depression of J point in lead V2-V6, followed by symmetrical high tip of T wave and normal ECG changes in QRS wave. Which was in line with the characteristics of electrocardiogram changes in De Winter syndrome. Coronary angiography results: right dominant type, no stenosis in LM, LCX and RCA, and 90%-95% stenosis in the middle part of LAD. The Electrocardiogram of the patient showed dynamic evolution of ST-T. Wellens syndrome and De Winter syndrome successively appeared. It suggests that severe proximal stenosis of the anterior descending artery is accompanied by coronary spasm and the possibility of spontaneous remission. Which will lead to changes of electrocardiograph in ST-T. For these patients, it is necessary to observe the changes of the condition closely and monitor the changes of electrocardiogram dynamically. It is likely to progress to acute extensive anterior wall myocardial infarction without further treatment. So it is necessary perform coronary intervention in time.

Initial Clinical Experience with a Symmetric Tip Tunneled Hemodialysis Catheter Without Side Holes.

The purpose of this article is to assess the performance and safety of a novel, symmetric, side-hole–free tunneled cuffed catheter hypothesized to sustain adequate flow without the need for side holes. Between November 2016 and January 2019, Pristine hemodialysis catheters were placed de novo in 45 end-stage renal disease patients (27 males and 18 females) at a single investigational site. Forty-one catheters were placed in the right and four in the left internal jugular vein. There were no incidents of insertion failure. Patients had dialysis three times per week and were followed at four investigational sites. Nominal catheter flows, incidence of poor flow, and catheter-related infections were recorded at each dialysis session and analyzed. The average follow-up time was 161.69 days for a total of 7116 catheter days. Nine patients died from reasons unrelated to the catheter and one patient switched to fistula. Four patients had poor flows necessitating catheter replacement. Four patients had catheter-related bloodstream infections which resolved with antibiotics. These equate to 0.56 events per 1000 catheter days. Catheter survival was 100%, 97.6%, and 89.7% at 30, 90, and 180 days, respectively. The initial clinical assessment of the symmetric Pristine hemodialysis catheter featuring a Y-tip devoid of side holes revealed good catheter performance and survival and a low complication rate.

Kinematics and geometrical admissibility conditions of balanced vane pumps with twin lip vanes

The present work is devoted to analyze the kinematics of twin lip vanes adopted in balanced vane pumps. The work provides the analytical description of the vane motion according to its geometrical parameters and the cam ring profile. Attention is given to the duality of the solution, an intrinsic property of twin lip vanes that may be considered as followers with two symmetrical half-circular tips. Based on the linkage kinematics, the analytical dissertation is further deepened to define the geometrical admissibility of the vane design and its mathematical domain. In order to evaluate the proposed approach, an extended parametric study is performed on the basis of the Buckingham theorem, detailing how the twin lip configuration affects the machine kinematics. Additional calculations are proposed to determine the vane design configurations that satisfy the fundamental law of cam design and to highlight how this requirement dramatically reduces the subset of available choices in presence of cam ring with a precompression profile. Finally, design guidelines are proposed in order to overcome these drawbacks and expand the admissibility domain.

Study on Soot Emission Characteristics of Methane/Oxygen Inverse Diffusion Flame.

Inverse diffusion flame (IDF) is an effective and widely used reaction form in the process of noncatalytic partial oxidation (NC-POX) of gaseous hydrocarbons (such as natural gas and coke oven gas). However, soot is generated in the combustion chamber in the case of unreasonable feeding conditions, and thus causes serious damage to the wall and nozzle. In this study, the effects of the equivalence ratio ([O/C]e), the oxygen flow rate, and the Reynolds number on the soot and CH* emission characteristics of CH4/O2 inverse diffusion flame were comprehensively analyzed based on a hyperspectral imaging system. In addition, the relationship between CH* and soot is explored using Ansys Fluent simulation. The experimental results show that the soot radiation core generation area is located in the outer ring of the flame, and the radial distribution of the radiation intensity is bimodal. With the increase in [O/C]e, the initial position for soot radiation and the overall radiation intensity of soot decrease. In addition, the CH* radiation intensity decreases as [O/C]e increases, and CH* exists in the whole flame. The simulation results clearly show that the existence of CH* is conducive to soot production. The emission intensity and the core area of soot formation increase with the increase in the oxygen velocity. Additionally, the soot emission region increases and the flame tip changes from a round blunt to symmetrical tip with the increase in the Reynolds number.

Development of New Hemodialysis Catheter Using Numerical Analysis and Experiments.

A hemodialysis (HD) catheter, especially one with a symmetric tip design, plays an important role in the long-term treatment of patients with renal failure. It is well known that the design of the HD catheter has a considerable effect on blood recirculation and thrombus formation around it, which may cause inefficiencies or malfunctions during HD. However, hemodynamic analyses through parametric studies of its designs have been rarely performed; moreover, only comparisons between the existing models have been reported. In this study, we numerically analyzed the design of the HD catheter's side hole and distal tip for evaluating their effects on hemodynamic factors such as recirculation rate (RR), shear stress, and blood damage index (BDI). The results indicated that a larger side hole and a nozzle-shaped distal tip can significantly reduce the RR and shear stress around the HD catheter. Furthermore, based on these hemodynamic insights, we proposed three new HD catheter designs and compared their performances with existing catheters using numerical and in vitro methods. These new designs exhibited lower RRs and BDI values, thus providing better performance than the existing models. These results can help toward commercialization of more efficient HD catheters.

Impact of side-hole geometry on the performance of hemodialysis catheter tips: A computational fluid dynamics assessment.

Hemodialysis catheters are used to support blood filtration, yet there are multiple fundamentally different approaches to catheter tip design with no clear optimal solution. Side-holes have been shown to increase flow rates and decrease recirculation but have been associated with clotting/increased infection rates. This study investigates the impact of changing the shape, size and number of side-holes on a simple symmetric tip catheter by evaluating the velocity, shear stress and shear rate of inflowing blood. A platelet model is used to examine the residence time and shear history of inflowing platelets. The results show that side-holes improve the theoretical performance of the catheters, reducing the maximum velocity and shear stress occurring at the tip compared to non-side-hole catheters. Increasing the side-hole area improved performance up to a point, past which not all inflow through the hole was captured, and instead a small fraction slowly ‘washed-out’ through the remainder of the tip resulting in greater residence times and increasing the likelihood of platelet adhesion. An oval shaped hole presents a lower chance of external fibrin formation compared to a circular hole, although this would also be influenced by the catheter material surface topology which is dependent on the manufacturing process. Overall, whilst side-holes may be associated with increased clotting and infection, this can be reduced when side-hole geometry is correctly implemented though; a sufficient area for body diameter (minimising residence time) and utilising angle-cut, oval shaped holes (reducing shear stress and chances of fibrin formation partially occluding holes).

A gold foil covered fused silica capillary tip as a sheathless interface for coupling capillary electrophoresis-mass spectrometry

A method for the preparation of an on-column ESI emitter used as the sheathless interface for coupling capillary electrophoresis (CE) with mass spectrometry (MS) was developed. The emitter was directly fabricated at the outlet end of the separation capillary which was etched with HF solution to a symmetrical tip. The tip was covered with a small piece of gold foil which was fixed by epoxy resin glue for electrical contact. Such a prepared ESI emitter can produce a stable ESI signal over the wide range of flow rate from 50 nL/min to 800 nL/min. The performance of the CE-MS with the sheathless interface was evaluated by using the separation of four alkaloids. It was found that the strong electroosmotic flow produced by the multiple polyelectrolyte coating on the capillary is necessary for maintaining a stable MS signal. Effect of the running buffer composition, concentration and the CE separation voltages on the ESI signal strength were investigated. The absolute detection limits for the alkaloids was determined as fmol level. Moreover, the CE-MS was applied for the analyses of trypsin digestion of cytochrome C and small molecular organic anions. The emitter performed very stable with a lifetime of at least 180 h.

Asymmetrical Paleolithic wooden spear tips: Expediency or design?

Paleolithic wooden spears provide rare but unique insights into early hunting technology. Examples from Schöningen, Germany indicate that spear tips were sometimes asymmetrical. This asymmetry has previously been interpreted as evidence for planning depth. A more parsimonious explanation, however, is that asymmetrical tips could be more efficiently produced (i.e., took less time to make) than symmetrical ones. Here, we experimentally investigated two different manufacturing processes, producing asymmetrical and symmetrical spear tips, while also testing the influence of biometric factors on spear-tip manufacturing efficiency (measured by time). One group of experimental participants sliced the wooden stave into an asymmetrical shape (slicing on one side of the stave with a steel blade), while the other group created a symmetrical shape (slicing on multiple sides of the stave). Based on time taken, results demonstrated no significant difference in efficiency between symmetrical and asymmetrical spear-tip manufacture. Conversely, some biometric characteristics (specifically pinch strength) present a more dominant influence in explaining time variation. These results demonstrate that the asymmetrical tips at Schöningen were not merely a byproduct of maximizing efficiency during the manufacturing process, but rather are evidence of planning and the associated cognitive capacities of these later Middle Pleistocene hominins.

Optimization of an optrode microdevice for infrared neural stimulation.

Infrared light is a promising candidate for the treatment of neurodegenerative diseases. Optimizing the device parameters to achieve the best optical and mechanical performance is essential for reliable in vivo operation. In this work, mechanical strength simulations and coupled optical and thermal model were used to determine optimal design parameters for maximizing overall device efficiency. Our analysis reveals that minimizing the number of integrated optical elements and optimizing the optical path leads to a 33% relative in-coupling efficiency improvement at equal mechanical robustness. Using a symmetric optrode tip with an angle of 15°, the efficiency showed a further 17% relative improvement due to the enhancement of out-coupling at the tip. To investigate the temperature rise of the brain tissue during the infrared stimulation in the case of the optimized device, a thermal simulation with pulsed infrared excitation was developed. Our results show that the optimized device provides a temperature rise of 4.42°C as opposed to 3°C for the original setup.

Atomic force microscopy analysis of the effect of plasma treatment on gas permeable contact lens surface topography.

Using atomic force microscopy (AFM) to investigate anterior surface topography (AST) in worn and unworn, plasma surface-treated (PST) and untreated (UT) gas permeable (GP) lenses, and influence of surface topography on in vivo comfort. GP lens AST evaluated with AFM in tapping mode, using an uncoated, 40 nm symmetric tip (sampling frequency: 300 kHz), at five randomised locations, over a 100μm2 area, to produce mean average roughness (Ra) and root mean square (RMS) values for each sample. Four unworn lenses (two PST, two UT) were examined (Quasar/Boston EO material). Twenty worn lenses (ten PST, ten UT) of same design and material as unworn lenses collected after 3 months lens wear. General wearing comfort reported by visual analogue scale (VAS) at 3 months visit. For sample preparation, two worn UT GP lenses were divided into four segments; each segment underwent a different lens rinse and drying method. Unworn: UT lenses had significantly higher mean RMS and Ra values compared to PST (Mann-Whitney, p < 0.05). Worn: UT Median RMS values were significantly higher than PST (Mann-Whitney, p < 0.05). Comfort: no correlation found between general comfort and RMS or Ra scores. Sample preparation: Method 4 (purified, distilled water rinse/nitrogen gas dry) produced optimum median RMS and Ra values. Unworn PST GP lenses had lower Ra and RMS values compared with unworn UT GP lenses. After 3 months wear, PST lenses had smoother surface topographies than UT lenses. No relationship was found between surface topography and lens wear comfort. Sample preparation protocol directly impacts AFM results.

Symmetrical and unsymmetrical tip clearances on cavitation performance and radial force of a mixed flow pump as turbine at pump mode

Abstract Transient cavitating flows of a mixedflow PAT (pump as turbine) at pump mode are investigated experimentally and numerically. Radial force on principal axis is recorded and compared between pump with symmetrical and unsymmetrical tip clearance. Numerical simulation with improved cavitation model by modifying the vapor pressure is conducted, and the simulation results agree well with the experiments. Tip clearance has great influence on pump cavitation performance. The pump energy performance will deteriorate with tip clearance increasing. In addition, in comparison with the symmetrical tip clearance, the unsymmetrical tip clearance makes the pump cavitation performance worse. As the cavitation develops, the unsymmetrical tip clearance simultaneously influences the magnitude and direction of radial force, while the symmetrical tip clearance only influences the magnitude of radial force. The dominant frequencies of radial force of symmetrical and unsymmetrical tip clearances are related to the blade number and guide vane number, respectively. The maximum amplitude of force fluctuation for unsymmetrical tip clearance is 7 times that for symmetrical tip clearance.