Conventional Tip Research Articles

Investigations into heat transfer and film cooling effect on a squealer-winglet blade tip

Numerical investigations of heat transfer and film cooling effect on the conventional squealer tip, no P.S. rim squealer tip and P.S. winglet squealer tip have been performed at three different cooling-hole arrangements (i.e. no film cooling, only tip holes, and both tip and pressure side holes) and two tip clearances. The flow structures, as well as the total pressure loss, in the cascades with three tip configurations (i.e. conventional squealer tip, no P.S. rim tip and P.S. winglet tip) were obtained and compared to analyze the effect of tip pressure-side geometries on the aerodynamic performance near the tip gap. With the existed experimental data for the conventional squealer tip, the numerical methods were carefully validated with respect to the turbulence model and mesh independency. The results indicate that the total pressure loss in the cascade with P.S. winglet tip is lower than that with conventional squealer tip by 5.0–6.7%, and the no P.S. rim tip shows a very close aerodynamic performance with the P.S. winglet tip configuration. In no film cooling case, the area-averaged heat transfer coefficient on the P.S. winglet tip surface is lower than that on the conventional squealer tip by 14.1–15.6%. In the tip holes only case, the area-averaged heat transfer coefficient on the P.S. winglet tip can be reduced by about 10% compared with the conventional squealer tip. As the tip clearance increases, the area-averaged heat transfer coefficient on no P.S. rim tip is getting lower than that on the P.S. winglet tip. With both tip and pressure side holes, the no P.S. rim and P.S. winglet tips still exhibit better film coolant coverage on the cavity floor than on conventional squealer tip, especially near the cavity pressure side. As the clearance gap increases, the film cooling effects on no P.S. rim and P.S. winglet tips become even better than that on the conventional squealer tip. As the clearance gap increases from 1% to 2.5% of blade span, the area-averaged film cooling effectiveness on the P.S. winglet and no P.S. rim tips are higher than the conventional squealer tip by 7.1–57.8%.

Gynecomastia: glandular-liposculpture through a single transaxillary one hole incision

Gynecomastia is characterized by the benign proliferation of breast tissue in men. Herein, we present a new method for the treatment of gynecomastia, using ultrasound-assisted liposuction with both conventional and reverse-cutting edge tip cannulas in combination with a pull-through lipectomy technique with pituitary forceps through a single transaxillary incision. Thirty patients were treated with this technique at the author’s institution from January 2010 to January 2015. Ten patients were treated with conventional surgical excision of the glandular/fibrous breast tissue combined with liposuction through a periareolar incision before January 2010. Medical records, clinical photographs and linear analog scale scores were analyzed to compare the surgical results and complications. The patients were required to rate their cosmetic outcomes based on the linear analog scale with which they rated their own surgical results; the mean overall average score indicated a good or high level of satisfaction. There were no incidences of skin necrosis, hematoma, infection and scar contracture; however, one case each of seroma and nipple inversion did occur. Operative time was reduced overall using the new technique since it is relatively simple and straightforward. According to the evaluation by the four independent researchers, the patients treated with this new technique showed statistically significant improvements in scar and nipple-areolar complex (NAC) deformity compared to those who were treated using the conventional method. Glandular liposculpture through a single transaxillary incision is an efficient and safe technique that can provide aesthetically satisfying and consistent results.

Minimally invasive dynamic hip screw for intertrochanteric fractures: comparison with conventional method and surgical tips

<p class="abstract"><strong>Background:</strong> <span lang="EN-IN">Intertrochantric fractures of the proximal femur are one of the most common injuries of the elderly. Prolonged duration and peroperative blood loss in this elderly frail population is one of the major problems in using the DHS. We performed minimally invasive DHS (MIDHS) implantation for such patients and compared results with conventional technique, hypothesising better perioperative outcomes.</span></p><p class="abstract"><strong>Methods:</strong> <span lang="EN-IN">We operated upon 30 cases as the case group from June 2013 to August 2016 with this technique. Patients older than 60 years of age with BMI less than 25 with stable AO type fractures which were easily reducible without sag of the distal fragment were included. In a control group 30 patients who had their hip fracture fixed with a DHS placed through the conventional approach were included. These groups were matched for sex, age, ASA grade and fracture type according to the AO classification. All surgeries were performed within 3 weeks of injury. We studied the patients in terms of time taken for surgery, peroperative blood loss, postoperative pain scores, need for analgesics and improvement in postoperative mobilization and rehabilitation by HHS</span>.<strong></strong></p><p class="abstract"><strong>Results:</strong> <span lang="EN-IN">Blood loss, duration of surgery and average pain score were significantly lower (p <0.0001) for MIDHS group due to a smaller incision and less muscle dissection. The HHS was also significantly better at 10 days in the MIDHS group. </span></p><p class="abstract"><strong>Conclusions:</strong> <span lang="EN-IN">Minimally invasive DHS is a simple and effective technique for fixation of intertrochantric fractures, especially in elderly, with reduced operative time, blood loss and postoperative pain scores leading to a more effective postoperative rehabilitation.</span></p><p align="left"> </p>

The mechanical properties of as-grown noncubic organic molecular crystals assessed by nanoindentation

Abstract

Removal of artificial dental calculus by use of conventional and diamond ultrasound tips.

Introduction: Periodontal disease is considered a public health problem and may lead to serious complications as the general health of patient. The main therapeutic procedure is scaling and root planing, which can be performed by a variety of techniques and instruments
 Objective:The aim of the present study was to evaluate the removal of calculus, produced artificially, by using a conventional ultrasonic tip and a diamond – CVD tip.
 Method: The calculus was produced with artificial sawdust and glue-based cyanoacrylate and distributed in twenty areas also standardized on two plates of acrylic resin (chemical activated), holding 10 samples per plate. Standards / samples were divided by lot into two simple groups, being A (treated with conventional tip) and B (treated with CVD tip).
 Results:The treatment in Group A, promoted an average area of 20.48 ± 4.20 mm2 free of artificial calculus which is significantly higher (p <0.05) than the area removed in Group B (15.37 ± 5.29 mm2).
 Conclusion:The results showed that the conventional tip presented higher results than CVD tip for efficacy in the removal of calculus.

Reduced hemidiaphragmatic paresis with extrafascial compared with conventional intrafascial tip placement for continuous interscalene brachial plexus block: a randomized, controlled, double-blind trial

BackgroundThe incidence of hemidiaphragmatic paresis with continuous interscalene brachial plexus block (CISB) can approach 100%. We tested the hypothesis that extrafascial placement of the catheter tip reduces the rate of hemidiaphragmatic paresis compared with intrafascial tip placement for CISB while providing effective analgesia. MethodsSeventy patients undergoing elective major shoulder surgery under general anaesthesia were randomized to receive an ultrasound-guided CISB plexus block for analgesia with the catheter tip placed either within (intrafascial group) or immediately outside (extrafascial group) the brachial plexus sheath midway between the levels of C5 and C6. Catheters were bolus dosed with ropivacaine 0.5% 20 ml before surgery, followed by an infusion of ropivacaine 0.2% at 4 ml h−1 for the first 2 days after surgery. The primary outcome was hemidiaphragmatic paresis measured by M-mode ultrasonography on postoperative day (POD) 1. Secondary outcomes included forced vital capacity, forced expiratory volume in 1 s, and rest pain scores. ResultsThe incidence of hemidiaphragmatic paresis on POD 1 was significantly reduced in the extrafascial group {intrafascial, 41% [95% confidence interval (CI) 25–59%]; extrafascial, 15% (95% CI 5–32%); P=0.01}. We were unable to detect a difference between groups in any of the functional respiratory outcomes or in rest pain scores [numerical rating scale (1–10): intrafascial, 3 (95% CI 2–3); extrafascial, 3 (95% CI: 2–4); P=0.93] on POD 1. ConclusionsPlacement of the catheter tip immediately outside of the brachial plexus sheath reduced the incidence of hemidiaphragmatic paresis on POD 1 associated with ultrasound-guided CISB while providing effective analgesia after major shoulder surgery. Our results do not support the routine placement of the catheter tip within the brachial plexus sheath for CISB. Clinical trial registrationNCT02433561.

Evidence provided for the use of oscillating instruments in restorative dentistry: A systematic review.

Oscillating diamond instruments are considered gentle sources for the removal of demineralized tooth hard tissues and the preparation of cavity angles and margins needed in minimally invasive dentistry. However, there is a question if literature provides enough evidence for their efficacy in restorative dentistry procedures. A literature search until May 2016 was conducted, using PubMed, Scopus, and The Cochrane Central Register of Controlled Trials databases. The quality of the studies was assessed using the recommendation of the Oxford Centre for Evidence-based Medicine. Fifty-five studies were finally included in the study. Of which, 78.2% of them were laboratory studies and only 21.8% were clinical studies. The strength of recommendation was 5 for most of them and D their grade of evidence. Bond strength of adhesives on surfaces prepared with these instruments, effective caries removal and cutting characteristics of the oscillating instruments were the main targets of the studies. Conventional diamond, steel, and chemical vapor deposition diamond tips and systems based on abrasive slurry were the oscillating tips, used in different studies. The strength of recommendation and grade of evidence of the studies were low. Although these devices seem to be useful for many clinical situations, there is a need for more well-structured evidence-based studies with more widely accepted procedures and common devices, to have more meaningful results and conclusions of higher strength.

Doubly Resonant Photonic Antenna for Single Infrared Quantum Dot Imaging at Telecommunication Wavelengths.

Colloidal quantum dots (CQDs) have drawn strong interest in the past for their high prospects in scientific, medical, and industrial applications. However, the full characterization of these quantum emitters is currently restricted to the visible wavelengths, and it remains a key challenge to optically probe single CQDs operating in the infrared spectral domain, which is targeted by a growing number of applications. Here, we report the first experimental detection and imaging at room temperature of single infrared CQDs operating at telecommunication wavelengths. Imaging was done with a doubly resonant bowtie nanoaperture antenna (BNA) written at the end of a fiber nanoprobe, whose resonances spectrally fit the CQD absorption and emission wavelengths. Direct near-field characterization of PbS CQDs reveal individual nanocrystals with a spatial resolution of 75 nm (λ/20) together with their intrinsic 2D dipolar free-space emission properties and exciton dynamics (blinking phenomenon). Because the doubly resonant BNA is strongly transmissive at both the CQD absorption and the emission wavelengths, we are able to perform all-fiber nanoimaging with a standard 20% efficiency InGaAs avalanche photodiode (APD). The detection efficiency is predicted to be 3000 fold larger than with a conventional circular aperture tip of the same transmission area. Double resonance BNA fiber probes thus offer the possibility of exploring extreme light-matter interaction in low band gap CQDs with current plug-and-play detection techniques, opening up new avenues in the fields of infrared light-emitting devices, photodetectors, telecommunications, bioimaging, and quantum information technology.

A differential evolution algorithm for maximizing heat dissipation in stepped fins

In this work, a differential evolution (DE)-based inverse analysis has been reported for maximizing the heat transfer rate from a rectangular stepped finned surface satisfying a given volume. The temperature dependency in all modes of heat transfer has been taken into the consideration, thereby making the problem highly nonlinear. In addition to conventional insulated tip assumption that signifies a linear case, nonlinear analysis with fin tip comprising simultaneous convection and radiation is also carried out. Furthermore, a numerical analysis of the transient behavior is done with the aid of the finite difference method. Due to unavailability of inverse analysis of stepped fins (literature supports this claim), for solving the problem using the DE, the concept of multiplicity of solutions satisfying a given criterion is used to search appropriate step configurations satisfying a fixed fin volume. Thereafter, step dimensions meeting the highest possible rate of heat transfer have been realized. During the DE-based optimization process, approximate analytical solutions formulated on the Adomian decomposition method (ADM) have been used for updating the pertinent fin temperature distribution. The proposed ADM-DE combination is observed to converge into a unique solution that yields the optimized design conditions under the imposed constraints.

Apertureless Near-Field Scanning Probes Based on Graphene Plasmonics

We present a novel approach in designing high-throughput high-resolution apertureless near-field scanning probes with enhanced nanofocusing based on graphene plasmonics. Extremely localized plasmons on graphene are mingled with nanofocusing of surface plasmon polaritons to confine and steer the plasmon waves into the apex of a near-field scanning optical microscopy tip. The Fermi level, localized emission sites on graphene, and the angle of excitation play a critical role in exciting graphene surface plasmons on the lateral walls of the designed conical probes. The optimized probes feature full-width at half-maximum (FWHM) around 25 nm, which is at least two times smaller than conventional metallic plasmonic tips. The near-field electromagnetic properties of the designed probes are characterized in detail and compared to the conventional single-aperture and typical apertureless metallic plasmonic (silver and gold) probes. Over three orders of magnitude electric field enhancement compared to metallic probes on SiO 2 substrate has been achieved.

The Mesoporous Porphyrinic Zirconium Metal-Organic Framework for Pipette-Tip Solid-Phase Extraction of Mercury from Fish Samples Followed by Cold Vapor Atomic Absorption Spectrometric Determination

In this study, the highly stable mesoporous porphyrinic zirconium metal-organic framework, namely PCN-222/MOF-545 (Zr-MOF), was prepared and used for pipette-tip solid-phase extraction of Hg(II). As a high-capacity sorbent, 4 mg of the Zr-MOF was placed into a conventional pipette tip and used, for the first time, for the fast extraction and preconcentration of mercury ions. For desorption, 50 μL of 10% HCl was used by 15 repeated aspirating/dispensing cycles, and Hg ions in elusion were measured by a cold vapor atomic absorption spectrometer. Affecting parameters on extraction efficiency were studied, and optimum conditions were established as amount of sorbent 2 mg, pH was adjusted to 5.0, the eluting volume was 15 μL, and extraction was performed on 1.8 mL of the sample. The optimal number of aspirating/dispensing cycles for extraction and desorption of analytes was found to be 10 and 15 cycles, respectively. The limit of detection of the method was found to be 20 ng L−1 with a relative standard deviation of ≤3.1% (for seven replicate analyses of 20 μg L−1 of mercury). Adsorption capacity and enrichment factor were 35.5 mg g−1 and 120-fold, respectively. The proposed method was successfully applied for the determination of Hg(II) ions in fish samples.

Effect of balanced phacoemulsification tip on the outcomes of torsional phacoemulsification using an active-fluidics system

To compare the outcomes of torsional phacoemulsification with a new balanced tip (Intrepid) and a conventional tip (Kelman) using a single active-fluidics torsional phacoemulsification machine (Centurion). Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India. Prospective comparative case-control study. Patients with senile cataract had torsional phacoemulsification with the Kelman conventional tip or the new Intrepid balanced tip using the active-fluidics torsional machine. Intraoperative parameters, such as cumulative dissipated energy (CDE), total ultrasound (US) time, torsion use time, torsion amplitude, aspiration time, and fluid use, were noted and compared. Endothelial cell loss and central corneal thickness (CCT) changes were evaluated at 1month. The new tip showed significantly less CDE, total US time, torsion amplitude, aspiration time, and fluid use (8.55±6.9 [SD], 33.59±28.12seconds, 37.8±13.42, 173.19±47.26seconds, and 66.59±20.44mL, respectively) than the conventional tip (13.47±10.65, 42.8±33.46seconds, 42.58±16.38, 202.25±71.28seconds, and 97.14±36.86mL, respectively) (P<.01), especially in higher grades of cataract. Anterior capsulorhexis margin tear occurred in 2 patients with the new tip. There were no corneal burns in either group. The mean endothelial cell loss and the percentage change in CCT were not significantly different at 1month. The new balanced tip performed phacoemulsification more efficiently, especially in hard cataracts requiring higher energy and prolonged phacoemulsification time.

Literature Review: Biomimetic and Conventional Aircraft Wing Tips

This paper is an attempt to summarize the effect of wing tip devices employed by birds, as well as aeronautical engineers in the past to improve the performance characteristics of aircraft. The focus is on reduction of the induced drag or drag due to lift also known as inviscid drag. This paper will provide an insight on both biomimetic & conventional wing tip approaches to reduce the induced drag. Prior analysis and experiments on the aerodynamics of airplane performance due to both these separate studies have been discussed. The needs of the industry and their past inventions have been described briefly as well as new areas to be explored have been highlighted.

Fabrication of atomic force microscope spherical tips and its application in determining the mechanical property of cancer cells

The process of cancer metastasis is closely related to the mechanical property of cells. Using the atomic force microscope (AFM)-based nanoindentation technique, the mechanical properties of cancer cells can be measured in liquid and at 37°C. However, the conventional AFM tip is too sharp to finish this process. The AFM tip with a microsphere at the end is usually used. How to adhere a microsphere to the tip apex has become a big concern up to now. In this work, an easy and simple method based on the employment of carbon nanotube bundles is presented. The microsphere is successfully adhered to the tip and the elastic constant of the cantilever is calibrated with the Cleveland method. Using the developed tip, the nanoindentation tests on two kinds of lung cancer cells (Anip-973 and AGZY-83a), which exhibit different metastatic properties, are carried out in liquid and at 37°C. Based on the Hertz contact equation between the spherical tip and the cell, the stress relaxation model is used to calculate the Young's modulus and viscoelastic properties of the cells. Experimental results confirm the feasibility of the method proposed in this work.

Controlled tip wear on high roughness surfaces yields gradual broadening and rounding of cantilever tips.

Tip size in atomic force microscopy (AFM) has a major impact on the resolution of images and on the results of nanoindentation experiments. Tip wear is therefore a key limitation in the application of AFM. Here we show, however, how wear can be turned into an advantage as it allows for directed tip shaping. We studied tip wear on high roughness polycrystalline titanium and diamond surfaces and show that tip wear on these surfaces leads to an increased tip size with a rounded shape of the apex. Next, we fitted single peaks from AFM images in order to track the changes in tip radius over time. This method is in excellent agreement with the conventional blind tip reconstruction method with the additional advantage that we could use it to demonstrate that the increase in tip size is gradual. Moreover, with our approach we can shape and control the tip size, while retaining identical chemical and cantilever properties. This significantly expands the reproducibility of AFM force spectroscopy data and is therefore expected to find a wide applicability.

Numerical investigations into the effect of squealer–winglet blade tip modifications on aerodynamic and heat transfer performance

Numerical investigations have been performed to investigate the heat transfer characteristic on the squealer–winglet tip, which is also compared with the conventional squealer tip and squealer tip without pressure-side rim. The validations and verifications of the numerical methods are carried out based on the existing experimental data. At a range of winglet leading edge angles and winglet coverage percentages, the total pressure losses in the cascade, as well as the flow structures in the tip gap, are analyzed in detail. The numerical results show that, by removing the pressure side rim from the conventional squealer tip, the high heat transfer area on the tip cavity floor near leading edge has disappeared, and the total pressure loss in the cascade has been reduced. If the conventional squealer tip is modified into a full-coverage of pressure side winglet configuration, the area-averaged total pressure loss in the cascade can be reduced by 12.2%, and the area-averaged heat transfer coefficient on the tip can be reduced by about 10% (PR=1.236). For the squealer tip configured with pressure-side winglet, the heat transfer distributions as well as the total pressure loss in the blade are not sensitive to the winglet leading edge angle. By choosing proper winglet leading edge angle and winglet coverage percentage, the area-averaged heat transfer coefficient on the tip can be reduced by 15.8%, and the area-averaged total pressure loss in the blade can be reduced by 13.8%, in contrast to the conventional squealer tip.

A Novel Endoscopic Catheter for "Laparoscopy-Like" Irrigation and Suction: Its Research and Development Process and Clinical Evaluation.

Inspired by natural orifice translumenal endoscopic surgery (NOTES), the authors launched a development of novel endoscopic irrigation and suction (I/S) catheter for "laparoscopy-like" I/S in flexible gastrointestinal (GI) endoscopy. The aims were to describe its basic research and development (R&D) process and to estimate its performance in both preclinical and clinical settings. In basic R&D phase, a layout of side hole at apex nozzle of endoscopic I/S (EIS) catheter were theoretically calculated and designed. Material of nozzle was selected based on the strength analysis. The performance of final prototype EIS catheter was then assessed preclinically in the porcine stomach, to compare with conventional endoscopic "tip irrigation" and "tip suction" as control. After regulatory clearance, safety and feasibility of I/S using EIS catheter were clinically assessed by endoscopists in small number of patients. Bench tests revealed 0.4 mm in diameter, 24 holes, and 6-8 holes per circumference as most suitable layout of side holes, and polyetheretherketone as an optimal nozzle material, respectively. Time to inject 500 mL saline with the EIS catheter was significantly shorter than tip irrigation (101 ± 3.1 seconds versus 154 ± 3.1 seconds; P < .05). The EIS suction was significantly weaker than conventional endoscopic tip suction, though it remained within the practical range. No mucosal injuries were noted in the EIS suction. In clinical assessments for human use, no adverse events were observed, and high degree of satisfaction for endoscopists was obtained. The newly developed EIS catheter is safely used with satisfactory performance in flexible GI endoscopy.

Closed-form solution for a rectangular stepped fin involving all variable thermal parameters and nonlinear boundary conditions

In this paper, the implementation of the Adomian decomposition method is demonstrated to solve a nonlinear heat transfer problem for a stepped fin involving all temperature-dependent means of heat transfer and nonlinear boundary conditions. Unlike conventional insulated tip assumption, to make the present problem more practical, the fin tip is assumed to disperse heat by convection and radiation. Thermal parameters such as the thermal conductivity, the surface heat transfer coefficient and the surface emissivity are considered to be temperature-dependent. Adomian polynomials are first obtained and then a set of Adomian decomposition method results is validated with pertinent results of the differential transformation method reported in the literature. Effects of different thermo-physical parameters on the temperature distribution and the efficiency have been exemplified. The study reveals that for a given set of conditions, the stepped fin may perform better than the straight fin.

Generating Electrospray Ionization on Ballpoint Tips.

In this study, we report a simple and economical ballpoint electrospray ionization mass spectrometry (BP-ESI-MS) technique. This combines a small ballpoint tip with a syringe pump for the direct loading and ionization of various samples in different phases (including solution, semisolid, and solid) and allows for additional applications in surface analysis. The tiny metal ball on the ballpoint tip exhibits a larger surface for ionization than that of a conventional sharp tip end, resulting in higher ionization efficiency and less sample consumption. The adamant properties of the ballpoint tip allow sampling by simply penetrating or scraping various surfaces, such as a fruit peel, paper, or fabric. Complex samples, such as fine herbal powders and small solid samples, could be stored in the hollow space in the ballpoint socket and subsequently extracted online, which greatly facilitated MS analysis with little to no sample preparation. Positive ion mode was attempted, and various compounds, including amino acids, carbohydrates, flavonoids, and alkaloids, were detected from different types of samples. The results demonstrated that the special and excellent physical characteristics of ballpoint tips allowed for fast and convenient sampling and ionization for mass spectrometry analysis by the BP-ESI-MS method.

Microsphere-based cantilevers for polarization-resolved and femtosecond SNOM

We present a cantilever-based near-field probe with integrated Mie scattering dielectric SiO2 microsphere (MSDM) for near-field optical imaging as well as femtosecond spectroscopy applications. In contrast to the state-of-the-art transmissive near-field probes, the MSDM reveals a transmission of almost unity known from far-field microscopy configuration. For proper handling, the microsphere is integrated at the apex of a conventional pyramidal aperture tip carried by an atomic force microscopy cantilever. It proved to be mechanically robust during the scanning process even if operating it in the contact mode. The spherical symmetry provides on the one hand a well-defined mechanical contact point with the sample irrespective of its inclination angle to the sample surface. On the other hand, the symmetry of the device preserves the polarization of light proving to be useful for the investigation of the polarization dependent behavior of plasmonic nanostructures. The high transmission combined with low dispersion renders spectroscopic investigations on the femtosecond timescale with a moderate lateral resolution. Second order autocorrelation experiments on a BBO crystal reveals a time resolution well below \(100\, {\hbox{fs at }} 191\, {\hbox{nm}}\) spatial resolution.