Secondary Orifice Research Articles

Static and Dynamic Performances of Novel Aerostatic Bearings with Primary and Secondary Orifice Restrictors

Aerostatic bearings are crucial support components in ultra−precision manufacturing equipment. However, improvements in the load−carrying capability (LCC) of aerostatic bearings often lead to higher intensity nano−vibrations. This paper introduces a novel primary and secondary orifice restrictor (PSOR) designed to simultaneously enhance the LCC and mitigate nano−vibrations in aerostatic bearings. The static performance of complex turbulent flows occurring within the chamber of aerostatic bearings with PSORs was investigated. The dynamic performance of the turbulent flows was analyzed through 3D transient numerical simulation using the large eddy simulation method. The LCC and nano−vibration acceleration were measured experimentally, and the results indicated that the design of the secondary orifice diameter could enhance LCC and mitigate nano−vibrations, consistent with theoretical predictions. The accuracy of the proposed model was validated, confirming the effectiveness of PSOR. In the experiments, an aerostatic bearing with a secondary orifice diameter of 0.1 mm exhibited the lowest LCC and largest nano−vibration. Conversely, an aerostatic bearing with a secondary orifice diameter of 0.26 mm exhibited the highest LCC and weakest nano−vibration. This study provides insights into the formation mechanism of turbulent vortex and interaction mechanism among the primary orifice and secondary orifices in aerostatic bearings with a PSOR.

Interception of fistulous tract and application of Kshara Sutra: Boon for anal fistulae with scrotal extension: A case series

Abstract Anal fistula primarily occurs due to infection of intersphincteric anal glands. In some cases, the anal fistula can extend into the scrotum. Fistula-in-ano with scrotal extension is a rare condition, and at first glance, such a presentation may be confused with acute scrotal diseases. It is commonly a congenital disorder in children characterized by painful swelling, redness, and pus discharge from the scrotum’s external opening (secondary orifice). Acharya Sushruta mentioned Ksharasutra therapy for managing Bhagandara (fistula-in-ano), a popular method for fistula-in-ano management with a reasonable success rate. Further, to fasten the recovery period in complex anal fistula cases, a modified technique of Ksharasutra is adopted, known as interception of fistulous tract with the application of Ksharasutra (IFTAK) technique. This case series describes three patients diagnosed with anal fistulae with scrotal extension. All patients had previously undergone a failed surgical procedure to cure their fistula. The patients were operated on with the IFTAK technique after proper preoperative evaluation. The postoperative fistulous wound in two cases was cured entirely within 5 weeks, and the third case within 6 weeks of treatment. IFTAK technique has shown promising outcomes in patients with anal fistula with scrotal extension. The success of the treatment with IFTAK is due to the eradication of sepsis by proper interception of the fistula tract. However, the efficacy of the IFTAK technique should be validated through well-planned randomized controlled clinical trials for its implementation as a standard treatment for complex anal fistulae.

Two new species of the cheilostome bryozoan Cheilopora from the Aleutian Islands.

Two new species of Cheilopora-C. peristomata and C. elfa-are described from the shallow water around Adak and Amchitka of the Andreanof and Rat island groups of the Aleutian Islands. Zooids of both new species have cormidial peristomes, composed by the distal (originating from neighbouring zooid) and proximal lappets. In contrast to previously described species, the strongly elevated peristomial lappets defining the secondary orifice confer the overall shape of an incomplete circle with deep U-shaped proximolateral pseudosinuses. Depending on angle of view, this gives a campanuliform or trifoliate outline to the secondary orifice, by which the new species differ from congeners. Together with previous discoveries from the Aleutians, these two new Cheilopora species are indicative of incomplete knowledge of the marine biodiversity of the region, including the distinctive character of the bryozoan fauna. There is a need for intensification of taxonomic effort along the island arc.

Minimally Invasive Surgical Approach to Complicated Recurrent Pilonidal Sinus.

Pilonidal sinus is considered as a simple and frequently occurring disease localized at the sacrococcygeal area. However, at the intergluteal region, it can often turn into a chronic and complicated disease. In some cases, it can fistulize up to the gluteal region and appear at the secondary orifices. Minimally invasive surgical techniques are becoming widespread in recent years due to the increased experience and development of new instruments. Limited excision of the pilonidal sinus tract can be a better treatment option compared with large excisions in terms of recovery time and patient's comfort. This case study reports the single-phase surgical treatment of complicated and recurrent pilonidal sinus localized at the gluteal area, with minimal tissue loss and inflammation.

A finite strain nonlinear human mitral valve model with fluid-structure interaction.

A computational human mitral valve (MV) model under physiological pressure loading is developed using a hybrid finite element immersed boundary method, which incorporates experimentally-based constitutive laws in a three-dimensional fluid-structure interaction framework. A transversely isotropic material constitutive model is used to characterize the mechanical behaviour of the MV tissue based on recent mechanical tests of healthy human mitral leaflets. Our results show good agreement, in terms of the flow rate and the closing and opening configurations, with measurements from in vivo magnetic resonance images. The stresses in the anterior leaflet are found to be higher than those in the posterior leaflet and are concentrated around the annulus trigons and the belly of the leaflet. The results also show that the chordae play an important role in providing a secondary orifice for the flow when the valve opens. Although there are some discrepancies to be overcome in future work, our simulations show that the developed computational model is promising in mimicking the in vivo MV dynamics and providing important information that are not obtainable by in vivo measurements. © 2014 The Authors. International Journal for Numerical Methods in Biomedical Engineering published by John Wiley & Sons Ltd.

The effect of using methylene blue in surgical treatments of pilonidal disease: a prospective randomized study

The aim of this study was to examine the effect of using intraoperative methylene blue (MB) in the treatment of pilonidal disease in the Karydakis flap practice on wound infection and recurrence and also by investigating other factors that affect wound infection and recurrence. In our research, the data of 231 patients, 129 of whom were in the MB [+] group and 102 of whom were in the MB [−] group, were obtained. Each patient’s age, gender, body mass index, whether they underwent pilonidal sinus surgery previously, the number of primary orifices, the number of secondary orifices, any preoperative infection, abscess drainage, and the use of antibiotic, if any, were recorded. The rate of postoperative wound infection in the entire group was found to be 25.1 %. While 19.4 % of the patients in MB [+] group had a wound infection, 32.4 % of the patients in the MB [−] group had a wound infection. The usage of MB was found to be a preventing factor in the occurrence of wound infection (p = 0.024). MB is beneficial owing to its reducing effect on wound infections, which in turn is associated with a lower recurrence rate and a fast postoperative recovery. We suggest the use of MB at the beginning of acute or chronic pilonidal sinus surgeries, as MB is nontoxic and is of very low cost.

Comparison of the short‐term results after Limberg and Karydakis procedures for pilonidal disease: randomized prospective analysis of 100 patients

The study was designed to compare the early postoperative results of the commonly used two surgical flap procedures in pilonidal disease: Karydakis and Limberg. One hundred patients were randomized into two groups and standard Limberg or Karydakis procedures were performed. All had primary sinus orifices. Infected cases and the ones with secondary orifices over 2 cm distant from primary were excluded. Data were recorded concerning complications, need for analgesia and wound dressing, periods of time off work and off driving. Patients were asked to classify their first defecation manner after the operation and also pain according to a Visual Analogue Scale with range of 1-10. There was a significantly higher wound infection rate in the Karydakis group than in the Limberg group (13/50 and 4/50 respectively). This also resulted in significantly higher values for wound dressings and need for analgesia. The time off work and off driving and also the Visual Analogue Scale scores were not significantly different between the two groups. Both procedures can be safely performed in pilonidal disease with a standard length of stay in hospital and a similar loss of productive power. However, the Karydakis flap seems to have a significant higher infection rate and this probably increases the cost.

602 キャビテーション促進用の二次的オリフィスを噴孔入口に有するホールノズルの微粒化・分散特性(二次的オリフィスが噴孔軸からオフセットした場合)(GS-7.8 噴霧微粒化・排気・CVT)

602 キャビテーション促進用の二次的オリフィスを噴孔入口に有するホールノズルの微粒化・分散特性(二次的オリフィスが噴孔軸からオフセットした場合)(GS-7.8 噴霧微粒化・排気・CVT)

Hemolytic anemia with porcine xenograft aortic and mitral valves

Severe hemolytic anemia occurred in a 30-year-old man 12 months after insertion of 23 mm and 31 mm Hancock porcine xenografts in the aortic and mitral positions respectively. At catheterization the mean transvalvular aortic xenograft gradient was 63 mm Hg, and at operation the stents of the aortic xenograft were bent inward, causing a supravalvular secondary orifice obstruction. One year later the patient has only subclinical hemolysis consistent with Björk-Shiley aortic and mitral prostheses.

Combustion Response Function Measurements by the Rotating Valve Method

A study has been conducted to evaluate the rotating valve method of measuring the combustion response of solid propellants to small amplitude pressure oscillations. The method is based on producing pressure oscillations in a small rocket motor by varying the area of a secondary exhaust nozzle in a periodic manner. This is accomplished by using a rotating valve as the secondary orifice. The valve apparatus operates concurrently with a primary nozzle which controls the steady-state pressure. The frequency of the oscillations is determined by the rotational speed of the valve. A theoretical analysis was conducted to relate the combustion response function to measurable ballistic properties of the combustion chamber. Assuming that the combustion chamber is small in comparison to the acoustic wavelength, the combustion response function can be calculated from the amplitude of the oscillating pressure and the phase angle between the oscillating pressure and oscillating nozzle area. Cold flow tests were conducted using nitrogen and helium to test the validity of the analysis. Excellent agreement was found between the measured and predicted amplitudes and phase angles. Combustion tests then were conducted using two aluminized propellant formulations and three nonaluminized formulations. There was excellent agreement between the T-burner and rotating valve tests conducted on the same batch of propellant. For two nonaluminized propellants, the comparisons were based on different batches of propellant. Differences in combustion response and variations in burning rate and characteristic exhaust velocity were observed for these two formulations. It was concluded that the rotating valve method is a valid substitute for the T-burner. Substantial reductions in the cost of characterizing propellants also were obtained using this new approach.

Observations on Living Diastoporidae (Bryozoa Cyclostomata), with Special Regard to Polymorphism

The Diastoporidan colony consists of three zones: The marginal common bud, a narrow middle zone with erect peristomes and active polypides nourishing the whole colony, and a large central zone where the erect peristomes are detached, the secondary orifices thus formed are closed by terminal diaphragms, and the feeding polypides have degenerated. In many Diastoporidae the terminal closure is complete, but in several species the diaphragm is raised into a narrow, open tubule. In the latter type a dwarfed polypide with one tentacle only is regenerated: The autozooid is transformed into a heterozooid (“secondary nanozooid”), a unique phenomenon. Its function is unknown. The single tentacle of the “true nanozooids” of Diplosolen performs sweeping movements indicating a cleaning function. In two Plagioecia species “occasional nanozooids” were found, induced by disturbances of the colony growth. The function, if any, is unknown.

Hemodynamic studies in patients with 2M and 3M Starr-Edwards Prostheses: evidence of obstruction to left atrial emptying.

The hemodynamic findings in 28 patients with small (2M uncovered, 2M and 3M covered) Starr-Edwards mitral prostheses are compared with the findings in 12 patients with larger (3M and 4M uncovered) prostheses. Although most patients with the smaller prostheses evidenced both clinical and hemodynamic improvement after operation, the majority continued to have a significant left atrial-left ventricular pressure gradient and an elevated left atrial pressure at rest. During exercise the gradient increased, and left atrial pressure was abnormally elevated in each patient. The hemodynamic findings were decidedly less satisfactory in patients with smaller prostheses than in patients in whom it had been possible to insert larger prostheses. It is concluded that the major site of obstruction to left atrial emptying in patients with smaller prostheses is the small primary orifice of the prosthesis present at the time of insertion. Further narrowing of the primary or secondary orifices by thrombus and/or tissue ingrowth probably contributes to the obstruction in some patients.