Tip Surface Area Research Articles

Change in root morphology, growth, and P transfer: Does foliar P application restrain root P-foraging behavior of Cunninghamia lanceolata seedlings in P-deficient environments?

Although foliar phosphorus application (FPA) is a fertilization method that can rapidly supplement nutrient elements in plants, it remains unclear whether it significantly affects the response strategy of roots under environmental stress. In this study, changes in plant growth, biomass allocation, and P use efficiency (PUE) of Chinese fir in different P environments were analyzed by FPA and root P application (RPA) treatments. The effects of FPA on P-foraging behavior of Chinese fir root system in P-deficient environment were then discussed. The root biomass with RPA was more significant at 0.03-0.25mmol·L-1 P concentrations than that with FPA; however, the PUE was significantly reduced by 28.89–29.41%. With an increase in the P application concentration, under the effect of FPA, the Chinese fir roots mainly reduced root proliferation by decreasing the tip number, surface area and volume but increasing in diameter, as well as the PUE of root, aboveground. As a result, the entire plant was improved. However, the degree of morphological adjustment of the root system was lower than that under RPA. In summary, both FPA and RPA can alleviate P starvation in Chinese fir to a certain extent, thereby improving PUE. Compared with RPA, FPA had a more significant impact on the behavior of Chinese fir roots in sensing and responding to soil P content, and the roots could more quickly sense changes in P content in the body. This mechanism provides valuable insights into the root response strategies of plants in P-deficient environments.

Defining Spatial and Temporal Resolution of Edema following Rhinoplasty: A Three-Dimensional Topographical Analysis.

Defining Spatial and Temporal Resolution of Edema following Rhinoplasty: A Three-Dimensional Topographical Analysis.

Steam and electrical power generation by a hybrid photovoltaic/parabolic dish concentrator using beam splitter technology

The parabolic dish is considered the most performant concentrating solar power (CSP) technology since it fits a wide range of domestic and industrial processes and offers better modular deployment than other CSP technologies such as thermal power receivers. The parabolic dish has been widely employed to produce steam and electricity especially when it works in conjunction with Stirling engines; however, the extreme complexity of the latter makes the power generation cost of this technology unfavorable against other competing solutions. In this paper, a comprehensive and detailed optical and thermal performance analysis and optimization study of a hybrid photovoltaic/parabolic dish concentrator with a conical thermal receiver using a beam splitter filter (PV/PDC-CTR-BSF) are carried out. A complete modeling module is developed to assess and optimize the overall yields of the PV/PDC-CTR-BSF. The present work is unique since it encompasses a sophisticated simulation tool enabling performance potential assessment of a novel PV/PDC-CTR-BSF system coupled with a novel conical-shaped helical coiled-tube heat exchanger for steam production and paves the avenue for higher electrical yield using single-junction PV cells mounted over the tip surface area of the paraboloid mirrors. The concentrated solar density (CSD) distribution, optical efficiency, temperature distribution, and steam fraction have particular interest in the performance assessment of the innovative PV/PDC-CTR-BSF package system. As a result, the maximum value of the CSD at the conical cavity receiver and the PV cells is 40 and 8 kW/m2, respectively. The optical efficiency of the proposed design has a breakthrough in the record of the typical hybrid designs reaching the value of 67%. Moreover, the maximum surface solar cells temperature was 80°C, while the temperature reached 170°C at the conical cavity receiver. The optical new hybrid design has maximized the steam productivity up to a steam volume fraction of 98%.

Use of a larger surface area tip on bipolar radiofrequency wands in hip arthroscopy is associated with significantly lower traction and total surgery times.

ABSTRACTClinical outcomes in arthroscopic hip preservation surgery have improved over the past two decades due to many factors, including advancements in technique and instrumentation. Complications following hip arthroscopy are associated with increased traction and overall surgical times. The purpose of this study was to compare traction and surgical times during hip arthroscopy using two different radiofrequency ablation wands produced by the same manufacturer. The authors hypothesized that the wand with a larger surface area would result in significantly less traction and surgical times. This study was a retrospective comparative investigation on patients who underwent arthroscopic surgery of the central, peripheral, peritrochanteric and/or deep gluteal space compartments of the hip. Both wands are 50-degree-angled probes, but the tip and shaft diameters are 3 and 3.75 mm for Wand A (Ambient Super MultiVac 50; tip surface area 7.1 mm2) compared to 4.7 and 4.7 mm for Wand B (Ambient HipVac 50; tip surface area 17.3 mm2), respectively. There was no difference (P = 0.16) in mean age of Wand A patients (30 females, 20 males; 35.2 years) versus Wand B patients (31 females, 19 males; 32.7 years). Traction time was significantly less in the Wand B group (41 ± 6 versus 51 ± 18 min; P < 0.001), as was surgical time (102 ± 13 versus 118 ± 17 min; P < 0.001). There were no significant differences in the number of labral anchors used or Current Procedural Terminology codes performed between groups. In conclusion, it was observed that the use of a larger surface area wand was associated with significantly less traction and surgical times during hip arthroscopy.

Designing bioinspired conical surfaces for water collection from condensation

In arid deserts, water supply is supplemented by water from fog and condensation. Once the droplets are collected, they are transported to a location where they are consumed or stored before they evaporate. Conical geometries or triangular patterns are known to create Laplace pressure gradient inside droplets which facilitates droplet transport. Water collection by fog on conical and triangular patterns have been studied. The research on the water collection by condensation exist only on flat triangular patterns. These flat surfaces have limitations for practical purposes, such as the Laplace pressure gradient does not act of droplets unless they touch the border. That is not the case in cones, which makes them superior for practical water collection. In this study, for the first time, water collection from condensation on cones have been studied. Cones of different tip angle, cone length, and surface area were used. Effect of inclination angle and array was also characterized. The results are compared to water collection by fog.

Optimization of bioinspired conical surfaces for water collection from fog

Desert beetles, desert grass and cacti use different mechanisms to transport the collected water. It is transported to a location where it is consumed or stored. The mechanisms include heterogeneous wettability, grooves, and Laplace pressure gradient due to conical geometry, respectively. A systematic study is presented which investigates the effect of conical geometry for water collection purposes. Parameters including tip angle, cone length, surface area, and inclination angle were varied. The effect of grooves, heterogeneous wettability, and array were also investigated. Force due to the Laplace pressure gradient and gravity were found to be the two primary forces driving the droplets.

Effect of Charge Delivery on Thromboembolism During Radiofrequency Ablation in Canines.

This study investigated whether delivering negative charge to catheter tips reduces thromboembolism during catheter ablation. Radiofrequency (RF) ablation prevents atrial fibrillation that can cause stroke or death. However, ablation itself can cause stroke (2%) or silent ischemia (2% to 41%), possibly via particulate debris that embolizes after coagulum adherence to catheter surfaces. Coagulum formation on RF catheters can be prevented by applying negative charge, but it is unknown if charge reduces peripheral thromboembolism. Paired (Charge ON vs. OFF) endocardial RF ablations were performed in 9 canines using nonirrigated RF catheters. Continuous negative charge was delivered via-100 μA of DC current applied to ablation catheter electrodes. Intracardiac echocardiography was used to navigate the catheter and to monitor coagulum formation. In a subset of 5 canines, microemboli flowing through polyester tubing between the femoral artery and vein (extracorporeal loop) were monitored with bubble counters and inline filter fabric. After each ablation, catheter-tip coagulum and blood particles deposited on the filters were quantified using photography and imaging software (ImageJ, U.S. National Institutes of Health, Bethesda, Maryland). Negative charge significantly decreased the extracorporeal loop median filter area covered by particles (n=19 pairs) by 10.2 mm2 (p= 0.03), and decreased median filter particles by 349 (p= 0.03). Negative charge also decreased the percentage of the catheter tip surface area covered by coagulum (n= 39 pairs) by 7.2% (p= 0.03). Negative charge delivery to ablation catheter tips during RF ablation can reduce particulate embolizationmaterial in an extracorporeal loop, and potentially reduce thromboembolic risk associated with RF ablation.

Combination of plastic film mulching and AMF inoculation promotes maize growth, yield and water use efficiency in the semiarid region of Northwest China

Plastic film mulching (PFM) plays a critical role in improving crop production and sustainable development of agroecosystem in semiarid agriculture. Arbuscular mycorrhizal fungi (AMF) can form a mutualistic symbiosis with the vast majority of plant roots and have been shown to contribute to host growth in harsh conditions. Yet, whether the integrated application of PFM and AMF inoculation have an interactive effect on crop growth and production in semiarid regions with poor soil nutrients and water shortage has received rather less attention. Therefore, we performed a two-year field study to investigate the effects of PFM and AMF inoculation on spring maize growth, yield and water use efficiency (WUE). Four treatments, including non-mulching and non-AMF inoculation (CK), plastic film mulching (PFM), arbuscular mycorrhizal fungi inoculation (AMF) and combination of plastic film mulching and arbuscular mycorrhizal fungi inoculation (PAMF), were compared in 2014 and 2015 at Shenmu Country on the semiarid Loess Plateau of Northwest China. Our results indicated that AMF inoculation contributed to increased plant biomass and height, although its effectiveness was lower than PFM alone or combined practice. Compared with the non-mulched control (CK), the mulched treatments significantly increased the average soil water content by 43.2% at the depth of 0–60 cm in 2014 and by 30.3% at the depth of 0–30 cm in 2015. The combination of PFM and AMF inoculation had the greatest soil water content at different soil depths in both years. AMF inoculation significantly improved root mycorrhizal colonization and external hyphal length in both years. Meanwhile, mycorrhizal plants under PFM had significantly greater root tip number and surface area when compared with the control. PAMF treatment had the highest yield and WUE among all treatments. Compared with the CK, PAMF treatment increased the yield and WUE by55.6% and 43.1% in 2014 and by 39.3% and 45.6% in 2015, respectively. Moreover, the mycorrhizal dependency of maize yield was more notable in mycorrhizal plants grown in mulched soils than in bare soils. In conclusion, the combined application of PFM and AMF inoculation is an effective and favorable agricultural practice in nutrition-deficiency soil in semiarid regions of China because of improved root morphological traits and enhanced topsoil water content that increase crop productivity.

A Novel Suction-Side Winglet Design Philosophy for High-Pressure Turbine Rotor Tips

Winglet tips are promising candidates for future high-pressure turbine rotors. Many studies found that the design of the suction-side winglet is the key to the aerodynamic performance of a winglet tip, but there is no general agreement on the exact design philosophy. In this paper, a novel suction-side winglet design philosophy in a turbine cascade is introduced. The winglets are obtained based on the near-tip flow field of the datum tip geometry. The suction-side winglet aims to reduce the tip leakage flow particularly in the front part of the blade passage. It is found that on the casing endwall, the pressure increases in the area where the winglet is used. This reduces the tip leakage flow in the front part of the blade passage and the pitchwise pressure gradient on the endwall. As a result, the size of the tip leakage vortex reduces. A surprising observation is that the novel optimized winglet tip design eliminates the passage vortex and results in a further increasing of the efficiency. The tip leakage loss of the novel winglet tip is 18.1% lower than the datum cavity tip, with an increase of tip surface area by only 19.3%. The spanwise deflection of the winglet due to the centrifugal force is small. The tip heat load of the winglet tip is 17.5% higher than that of the cavity tip. Numerical simulation shows that in a turbine stage, this winglet tip increases the turbine stage efficiency by 0.9% mainly by eliminating the loss caused by the passage vortex at a tip gap size of 1.4% chord compared with a cavity tip.

分離形熱サイフォンを用いた血液凝固付着抑制電気メスの開発

Radio knives are common tools in surgery. The adhesion of the tip of a radio knife to the human body through the coagulation of blood is a severe problem. A solution to this problem, suggested by other authors, is to cool the tip of the radio knife. However, introducing a cooling system, such as circulating water inside the tip with a pump, requires additional wires and pipes and may also distract the surgeons. To overcome these issues, we consider the possibility of embedding a separate type thermosyphon to cool the radio knife tip without any additional wires and pipes. The important parameters are the tip length, tip diameter, inner tip diameter, enclosure ratio of the working fluid, and grip length. First, to clarify the heat-transport possibilities, the top of the tip of a separate type thermosyphon radio knife was heated by a ceramic heater; this was done to measure the temperature difference between the radio knife tip surface and a heat release part. Second, suitable values for the tip length, diameter and other important parameters were considered. It was concluded that the highest cooling efficiency is obtained when the heating area is limited between 200 and 250 mm2 of the knife tip surface area. The inner pipe was indispensable to transport generated heat from the tip to the radio knife end. Consequently, it was revealed that the effective diameter of inner pipe was 0.48 mm in this research. To simulate the conventional surgery situations, the radio knife tip was immersed to blood and applied voltage to generate heat at the tip. It demonstrated 45.9 degree C at the maximum temperature while it was activated. Furthermore, the coagulation at the peripheral of the tip was observed, accordingly, the separate type thermosyphon radio knife exhibited a stop bleeding ability.

The effects of ultrasound on micromixing

The Villermaux–Dushman reaction is a widely used technique to study micromixing efficiencies with and without sonication. This paper shows that ultrasound can interfere with this reaction by sonolysis of potassium iodide, which is excessively available in the Villermaux–Dushman solution, into triiodide ions. Some corrective actions, to minimize this interference, are proposed. Furthermore, the effect of ultrasonic frequency, power dissipation, probe tip surface area and stirring speed on micromixing were investigated. The power and frequency seem to have a significant impact on micromixing in contrast to the stirring speed and probe tip surface area. Best micromixing was observed with a 24kHz probe and high power intensities. Experiments with different frequencies but a constant power intensity, emitter surface, stirring speed, cavitation bubble type and reactor design showed best micromixing for the highest frequency of 1135kHz. Finally, these results were used to test the power law model of Rahimi et al. This model was not able to predict micromixing accurately and the addition of the frequency, as an additional parameter, was needed to improve the simulations.

Effect of Dietary Exogenous Enzyme Supplementation on Enteric Mucosal Morphological Development and Adherent Mucin Thickness in Turkeys.

Anti-nutritional factors (ANFs) in feed ingredients can challenge gut health and reduce nutrient utilization. Birds typically activate their innate immune system as a protective response against the adverse effects of ANF, which often involves the secretion of mucin. Although dietary supplementation of exogenous enzymes are commonly used to alleviate the adverse effects of ANF on apparent nutrient digestibility, little is known about how they affect gut health, particularly in relation to the morphological development and mucin secretion of enteric mucosa. We carried out two trials to examine the effect of dietary supplementation of different types of exogenous enzymes on gut health of by accessing the effect of jejunum morphological development and ileal enteric adherent mucin thickness layer in turkeys. Dietary β-mannanase supplementation reduced ileal adherent mucin thickness layer (804 vs 823 μg/g; p < 0.05), while a commercial blend of xylanase, amylase, and protease (XAP) reduced ileal adherent mucin layer thickness (589 vs 740 μg/g; p < 0.05); thus reducing the apparent endogenous loss of nutrients. Both enzyme supplements also affected gut morphological characteristics. In comparison to the control treatment, dietary β-mannanase supplementation improved the jejunum tip width (219 vs 161; p < 0.05), base width (367 vs 300; p < 0.05), surface area (509,870 vs 380, 157; p < 0.05) and villi height/crypt depth ratio (7.49 vs 5.70; p < 0.05), and XAP improved the crypt depth (p < 0.05). In conclusion, dietary supplementation of exogenous enzymes may help alleviate the adverse effects of ANF on nutrient utilization by directly or indirectly removing the mucosal irritation that stimulates enteric mucin secretion.

Effect of skew angle on main precursor of frictional ignition in bench-scale simulation of excavation processes

•Temperature changes (ΔT) of cutting tool driven against a rock wheel were examined.•Long-duration tests increased ΔT at non-zero skew angles.•Heavier bits with larger tip surface area are more sensitive to ΔT increase due to skew angle.•ΔT at a zero skew angle was higher for lighter bits.•The results suggest how bits and bit tips should be designed for safer excavation.

Elucidating the variables affecting accelerated fatigue crack growth of steels in hydrogen gas with low oxygen concentrations

The objective of this study was to quantify the effects of mechanical and environmental variables on oxygen-modified accelerated fatigue crack growth of steels in hydrogen gas. Experimental results show that in hydrogen gas containing up to 1000v.p.p.m. oxygen fatigue crack growth rates for X52 line pipe steel are initially coincident with those measured in air or inert gas, but these rates abruptly accelerate above a critical ΔK level that depends on the oxygen concentration. In addition to the bulk gas oxygen concentration, the onset of hydrogen-accelerated crack growth is affected by the load cycle frequency and load ratio R. Hydrogen-accelerated fatigue crack growth is actuated when threshold levels of both the inert environment crack growth rate and Kmax are exceeded. The inert environment crack growth rate dictates the creation of new crack tip surface area, which in turn determines the extent of crack tip oxygen coverage and associated hydrogen uptake, while Kmax governs the activation of hydrogen-assisted fracture modes through its relationship to the crack tip stress field. The relationship between the inert environment crack growth rate and crack tip hydrogen uptake is established through the development of an analytical model, which is formulated based on the assumption that oxygen coverage can be quantified from the balance between the rates of new crack tip surface creation and diffusion-limited oxygen transport through the crack channel to this surface. Provided Kmax exceeds the threshold value for stress-driven hydrogen embrittlement activation, this model shows that stimulation of hydrogen-accelerated crack growth depends on the interplay between the inert environment crack growth increment per cycle, load cycle frequency, R ratio and bulk gas oxygen concentration.

Increased small intestinal and colonic permeability, and loss of villus tip surface area, correlates with microbial translocation and immune activation in HIV (71.5)

Abstract As early diagnosis and viremic control of HIV becomes more prevalent, the clinical focus has turned to preventing co-morbidities that include cardiovascular, hepatic, neurological, and metabolic abnormalities and immune exhaustion. Immune activation, as measured by leukocyte activation and soluble inflammatory mediators in circulation, is increased in HIV patients, even those on effective HAART therapy, and is a better predictor of disease progression and of all-cause mortality than viral load. Intestinal permeability, which often leads to microbial products in the bloodstream, may provide a cause for chronic inflammation in HIV patients. Here, we provide corroborating evidence of small intestinal and colonic permeability in a cohort of HIV patients with increased LPS, determined by measuring the excretion of various saccharides. Levels of lactulose and mannitol (small intestinal permeability) and sucralose (colonic permeability) were elevated (p=0.0014 and p&amp;lt;0.001, respectively) in the urine of HIV patients, independent of HAART status. Further analysis of the saccharide excretion profile revealed that HIV patients have a loss of villus tip surface area in the small intestine as compared to controls (p&amp;lt;0.001). These results were correlated to markers of bowel damage and microbial translocation (LPS Binding Protein, EndoCAb, sCD14, I-FABP) and immune activation (CRP, IL-6, IFN-α) and to clinical parameters in hopes of identifying key risk factors for disease progression.

Modeling cutting edge geometry for plane and curved needle tips

Hollow needles are commonly used in many areas of medicine, yet there has been limited research on needle tip geometry. A better understanding of needle tip geometry can lead to the creation of an optimized needle tip geometry design which would greatly benefit the procedure of biopsy, where a needle is used to cut and remove tissue from the body. The present research develops mathematical models to calculate the inclination and rake angle along the cutting edges of needle tips generated by curved surfaces. The parameters of needle insertion length and inner needle tip surface area are also examined. Needle insertion force is predicted based on needle geometry and calculated for curved and flat plane tip needles. A concave needle produced lower cutting forces than the convex and bias bevel needles. It is found that utilizing curved surface needle tip geometry, as opposed to flat plane geometry, allows for greater control in varying rake and inclination angles on the needle. This greater flexibility allows for more control in designing an optimized needle tip.

Initial design of a novel suction enteroscope for endoscopic locomotion in the small bowel (with video)

The upper GI tract and the colon are readily accessible endoscopically, but the small intestine is relatively difficult to evaluate. To demonstrate the feasibility of using suction as a means of locomotion and to assess the initial design of a suction enteroscope. Feasibility study. Animal laboratory. Various prototype suction devices designed in our laboratory were tested in swine small intestine in a force test station. For in vivo experiments in live anesthetized animals, two suction devices (1 fixed tip and 1 movable tip) were attached to the outside of the endoscope. By creating suction in the fixed tip, the endoscope was anchored while the movable tip was advanced. Suction was then applied to the extended tip to attach it to the distal bowel. Suction on the fixed tip was then released and the movable tip with suction pulled back, resulting in advancement of the endoscope. These steps were sequentially repeated. Intestinal segments were sent for pathologic assessment after testing. Force generated ranged from 0.278 to 4.74 N with 64.3 to 88 kPa vacuum pressure. A linear relationship was seen between the pull force and vacuum pressures and tip surface area. During in vivo experiments, the endoscope was advanced in 25-cm segmental increments with sequential suction-and-release maneuvers. No significant bowel trauma was seen on pathology and necropsy. The enteroscopy system requires further refinement. A novel suction enteroscope was designed and tested. Suction tip characteristics played a critical role impacting the functionality of this enteroscopy system.

Response of root morphology and distribution in maize to alternate furrow irrigation

a b s t r a c t After measuring root morphological indices, such as the length, diameter, volume density, surface area and tip number of both living and dead roots on the ridge and slope under alternate furrow irrigation (AFI) and conventional furrow irrigation (CFI, control treatment) using Minirhizotrons, the responses of root morphology and distribution in maize to AFI were analyzed. Results show that root morphological indices of living or dead roots were lower on the ridge than on the slope under AFI, whereas root mor- phological indices of living or dead roots were higher on the ridge than on the slope under CFI. Compared to CFI, AFI significantly increased root tip number and surface area of fine roots (with the diameter of ≤2.5 × 10 −1 mm) and promoted roots to deeper soil on the slope, and then simulated root water uptake. AFI only decreased the grain yield by 0.9%, but increased water use efficiency on seed yield by 8.3%. Thus AFI promoted root growth and metabolism on the slope, increased the effective absorption area of root system and improved water use efficiency without significant reduction of grain yield.

Evaluations of carbon nanotube field emitters for electron microscopy

Brightness of carbon nanotube (CNT) emitters was already reported elsewhere. However, brightness of electron emitter is affected by a virtual source size of the emitter, which strongly depends on electron optical configuration around the emitter. In this work, I – V characteristics and brightness of a CNT emitter are measured under a practical field emission electron gun (e-gun) configuration to investigate availability of CNT for electron microscopy. As a result, it is obtained that an emission area of MWNT is smaller than its tip surface area, and the emission area corresponds to a five-membered-ring with 2nd nearest six-membered-rings on the MWNT cap surface. Reduced brightness of MWNT is measured as at least 2.6 × 1 0 9 A/m 2 sr V. It is concluded that even a thick MWNT has enough brightness under a practical e-gun electrode configuration and suitable for electron microscopy.

Form-function relations in cone-tipped stimulating microelectrodes

Metal microelectrodes are widely used in neuroscience research, and could potentially replace macroelectrodes in various neuro-stimulation applications where their small size, specificity, and their ability to also measure unit activity are desirable. The design of stimulating microelectrodes for specific applications requires knowledge on how tip geometry affects function, but several fundamental aspects of this relationship are not yet well understood. This study uses a combined experimental and physical finite elements simulation approach to formulate three new relationships between the geometrical and electrical properties of stimulating cone-tipped tungsten microelectrodes: (1) The empirical relationship between microelectrode 1-kHz impedance and the exposed tip surface area is best approximated by an inverse square-root function (as expected for a cone-tipped resistive interface). (2) Tip angle plays a major role in determining current distribution along the tip, and as a consequence crucially affects the charge injection capacity of a microelectrode. (3) The critical current for the onset of corrosion is independent of tip surface area in sharp microelectrodes.