Small Outer Diameter Research Articles

Plug Your Way Through Downhole Restrictions

_ Unable to successfully deploy plug-and-perf bottomhole assemblies (BHA) to the desired depth has resulted in significant nonproductive time (NPT) in unconventional completions. These instances of NPT are primarily attributed to casing deformation, rather than plug presets. To address these downhole restrictions, frac plugs with smaller outer diameters (OD) were introduced for stage isolation. This reduction in plug OD minimizes the risk of getting stuck in tight spaces, but it also compromises pressure ratings. This raises the risk of skidding (slip losses, anchoring) and leads to increased fluid usage for pumpdown. These challenges not only risk well productivity, but also escalate completion time and costs. For a comprehensive solution, a smaller-OD frac plug is necessary to pass through tight spots, while maintaining anchoring, sealing, and reducing required pumped-fluid volume. The Gap The annular clearance between the plug OD and casing inner diameter (ID) significantly influences plug-and-perf operations. A smaller gap leads to advantages such as lower expansion rates for isolation, better anchoring, and reduced pumped-fluid volume, but it also heightens the risk of obstructions. Conversely, a larger gap requires higher expansion rates for isolation, resulting in weaker anchoring, lower pressure rating, and increased fluid consumption, but reduces the likelihood of obstructions. In some frac operations, higher pressure is needed to break down the formation; thus, frac plugs with higher pressure ratings (smaller gap) are commonly favored. For instance, in 5.5-in., 20-lb/ft casing, typical frac plugs have an average OD of 4.4 in., an expansion rate of 8–12%, and a pressure rating of 10,000 psi. In many 5.5-in., 20 lb/ft casedhole completions across the US and parts of China, the annular clearance between casing ID and frac plug OD is approximately 0.2 in. on the x-axis and 0.4 in. on the y-axis (Fig. 1). In this confined space, encountering debris, sand accumulation, or a deformed section during pumpdown can obstruct or fully trap the plug. To mitigate these uncertainties, smaller-OD plugs are used for such “emergency” scenarios. Smaller-OD plugs have improved chances of navigating through tight spots, but they necessitate higher expansion rates for isolation, resulting in lower pressure ratings. For example, in 5.5-in., 20 lb/ft casing, reduced OD plugs have an average OD of 3.8 in., an expansion rate of 20–25%, and a pressure rating of 5,000 psi. They are more likely to fail due to their pressure limitations and use more fluid for pumpdown. In cases where the use of normal-OD plugs is not feasible, opting for smaller-OD plugs, even though they might have a higher risk of failure, can be a valuable last resort. This approach is sometimes favored over entirely skipping the problematic stages without any form of stimulation.

Carbon nanotube yarn with small outer diameter to maximize the electrochemical performance of artificial muscles

Electrochemically powered carbon nanotube (CNT) artificial muscles have garnered significant attention owing to their chemical stability, low operating voltage, and impressive actuation performance. Notably, twist-based CNT artificial muscles have demonstrated superior actuation performance by maximizing untwisting motion of the CNT yarn. However, the microscopic design of CNTs is yet to be reported, although CNTs comprising CNT yarn muscles are key determinants of performance. Here, we first establish a correlation between the diameter of CNTs and the actuation performance of artificial muscles. The structural reason for the higher deformability is elucidated employing molecular dynamics simulations. The obtained computational simulation results were consistent with the experimentally fabricated yarn. Remarkably, the CNT yarn muscle composed of small-diameter CNTs exhibited a work capacity of 3.57 J/g, significantly higher than previously reported ones. Our findings provide a fundamental design range of CNT diameters that can significantly enhance the performance of electrochemically powered artificial muscles.

Research on mechanism and experimental effect of tubular electrode dimensions on electric arc electrochemical composite machining

ABSTRACTThis research discusses the effect of typical characteristic dimensions of electrodes on electric arc electrochemical composite machining (EAECM). The flow rate and debris removal capability of electrodes with different characteristic dimensions were investigated by flow field simulation. Single-factor machining experiments were conducted. The discharge characteristics, process indicators and machined surfaces of electrodes were analyzed it was found that the tubular electrode has a demarcation phenomenon that affects the surface quality. The results indicate that the use of electrodes with large inner diameters is favorable to improve the surface consistency. The use of electrodes with small outer diameters improves the overall surface quality but increases the electrode wear. Finally, the fracture mechanism of thin-walled electrodes was revealed by stress field simulations and experiments. In conclusion, in order to improve the machining effect of EAECM, large-diameter (inner and outer diameter) electrodes with wall thickness greater than 2 mm should be selected.

Fabrication of highly catalytic active α-Fe2O3-carbon nanotube composites for thermal decomposition of ammonium perchlorate by light and temperature control strategy

For alleviating agglomeration of α-Fe2O3 nanoparticles and improving their catalytic activities as burning rate catalysts (BRCs) in solid propellants, Fe(CO)5 as the iron source was encapsulated into the inner space and/or loaded onto the outer surface of carbon nanotubes (CNTs) via ultrasonication with visible light and temperature control strategy. The Fe(CO)5-CNTs composites were subsequently transformed into α-Fe2O3-CNTs nanocomposites by Fe(CO)5 pyrolysis. The as-synthesized α-Fe2O3-CNTs composites were utterly characterized by HRTEM, SEM, BET, XPS, FTIR, Raman, and XRD. The catalytic combustion results show that the nanocomposites are highly active in boosting the thermal degradation of ammonium perchlorate (AP). α-Fe2O3&CNTs(S1) nanocomposite, the most excellent one, shifts left the peak temperature of the high-temperature decomposition (HTD) region of AP by 103.7 °C and increases its release heat by 190 %. Moreover, a carbon nanotube with a smaller outer diameter and higher iron content is conducive to enhancing AP thermal deterioration. A possible mechanism of AP decomposition with the addition of the nanocomposites was investigated by thermal decomposition dynamics, in-situ solid-state FTIR, and gas phase FTIR-MS technique. The mechanistic research implies that the produced NH3 and HClO4 gases can be absorbed on the nanocomposite surfaces to form more superoxide anions (O2−) during AP decomposition, accelerating the generation of NO from N2O and facilitating AP disintegration at a lower temperature. A tentative AP decomposition mechanism in the presence of the α-Fe2O3-CNTs nanocomposites is therefore proposed.

Abstract 197: Mechanical Thrombectomy Of Basilar Artery Occlusion On A Hypoplastic Vertebrobasilar Circulation

Introduction Basilar artery occlusion (BAO) is one of the most severe acute ischemic strokes which carries high mortality and morbidity risk. Mechanical thrombectomy (MT) has been used as a promising treatment for BAO. However, the vertebral‐basilar anatomy is more challenging for MT compared to the anterior circulation due to several congenital variants such as hypoplastic vertebral artery, fenestration on the vertebrobasilar junction, or chronic asymptomatic occlusions of vertebral arteries, and tortuous subclavian arteries and vertebral arteries (VAs). Here, we described a BAO case with hypoplastic vertebrobasilar arteries, which was successfully treated with thrombectomy using the direct aspiration technique. Methods Electronic Medical Records review of a patient with acute basilar artery occlusion stroke. Results 55‐year‐old healthy gentleman presented to ER with acute onset with confusion, dysarthria, left‐sided weakness, and right facial droop. Initial NIHSS was 12. CT angiography (CTA) head and neck showed basilar artery was occluded in the distal one third segment. Because of the right fetal posterior cerebral artery and prominent left posterior communicating artery, his bilateral VAs and basilar artery were underdeveloped. The left VA appeared to be slightly bigger than the right one. After the patient received IV tPA, he was taken for mechanical thrombectomy. A Ballast catheter was placed in the left subclavian artery near the left VA origin. The conventional angiography showed the left VA was 2.8 mm and proximal basilar was about 2.1 mm. The Zoom 35 aspiration catheter was then used for mechanical thrombectomy. A complete basilar recanalization was achieved on the first pass. The patient improved after the MT. His NIHSS on discharge was 0. Conclusion The benefits of MT on BAO remain unknown despite several clinical trials. One of the reasons is due to more challenged vascular anatomy compared to anterior circulation. Underdevelopment of unilateral VA was commonly seen in posterior circulation ischemic strokes. But the underdevelopment of bilateral VAs with basilar arteries in BAO cases was rare and more difficult to treat. The Zoom 35 aspiration catheter provided a great advantage for this case with its smaller outer diameter, good navigation ability, and great aspiration efficacy. Our experience suggested a direct aspiration first pass technique (ADAPT) has an advantage on BAO, especially in the congenitally underdeveloped vertebrobasilar arteries.

Incidence of Distal Radial Artery Occlusion and its Influencing Factors After Cardiovascular Intervention Via the Distal Transradial Access.

One of the important advantages of the distal transradial access (dTRA) is the significant reduction in the incidence of radial artery occlusion (RAO). There are few reports on the influencing factors for distal radial artery occlusion (dRAO) after cardiovascular interventions via the dTRA. This retrospective analysis included the clinical data of patients who underwent a cardiovascular intervention via the dTRA. The dRAO was evaluated by ultrasound within 24 hours after the procedure. Multivariate logistic analysis was used to explore the influencing factors for dRAO. The incidence of dRAO was 3.5% (28/805) at 24 hours follow-up after the procedure. In the comparison between the 2 groups, the preoperative distal radial artery (DRA) internal diameter in the dRAO group was significantly smaller than that in the non-dRAO group (p=0.001). The prevalence of DRA inner diameter/sheath outer diameter <1 was significantly higher in the dRAO group than in the non-dRAO group (p=0.013). The number of puncture attempts was significantly greater in the dRAO group than in the non-dRAO group (p=0.007). Multivariate logistic analysis showed that DRA inner diameter/sheath outer diameter <1 was an independent risk factor for dRAO (OR=4.827, 95% CI=1.087-21.441, p=0.039). The incidence of dRAO 24 hours after cardiovascular intervention via the dTRA was 3.5%, and a DRA inner diameter/sheath outer diameter <1 was an independent risk factor for dRAO. Preoperative ultrasound assessment of vessel inner diameter and selection of a sheath with a smaller outer diameter may reduce the risk of dRAO. The incidence of distal radial artery occlusion after cardiovascular intervention was 3.5%. The distal radial artery inner diameter/sheath outer diameter <1 was an independent risk factor for distal radial artery occlusion. Preoperative ultrasound assessment of vessel inner diameter and selection of a sheath with a smaller outer diameter may reduce the risk of distal radial artery occlusion. The number of puncture attempts and compression time were not related to distal radial artery occlusion.

Comprehensive thermal energy storage analysis of ceramic foam-enhanced molten salt in a shell-and-tube unit

Ceramic foam can be used to enhance the energy storage efficiency of molten salt for high-temperature solar thermal applications. However, its performance in a shell-and-tube unit is not fully understood. In this study, the energy storage performance of ceramic foam-enhanced molten salt in a shell-and-tube unit is investigated. The effects of ceramic foam configurations such as the filling height, porosity and outer diameter are studied. The results show that when the ceramic foam reaches the inner tube, the enhancement performance is remarkable, while it is insignificant in the case of below the inner tube. Although the total stored energy of the full foam-filled case is decreased by 13.6% compared to the no foam-filled case, the energy storage rate is improved by 54.9%. The variation of energy storage rate with porosity is generally regular. Ceramic foam with a small outer diameter has great enhancement performance; as the outer diameter increases, the difference in the enhancement gets less remarkable. The three factors are compared through a normalised effective porosity and the ceramic foam with varying outer diameters shows the best performance including the shortest melting time, the largest total stored energy and the highest energy storage rate. It is attributed that the ceramic foam surrounds the tube completely and concentrates around the tube, so its performance of conducting the heat of the tube is the best. The corrosion resistance of ceramic foams and the cost advantage make it a suitable thermal enhancer for molten salt in high-temperature solar thermal energy storage applications.

Economic and heating efficiency analysis of double-shell downhole electric heater for tar-rich coal in-situ conversion

Downhole electric heater studied in this paper is used for tar-rich coal in-situ conversion, and the closed double-shell structure is proposed to improve the performance and economy of heater. In this paper, four downhole electric heaters were experimentally studied, and the single-shell heater was used as the control. According to the experimental results, it can be seen that the mass flow rate has a great impact on the total cost, and the parallel double-shell downhole electric heater has the highest total cost. In addition, the larger the helical pitch or the heater shell diameter, the lower the heater shell surface temperature, and thermal radiant is the main way of heater shell to lose heat, which is accounts for 78.91%–92.91%. Moreover, from the perspective of heat transfer quality, heater with closed double-shell structure is more efficient than the single-shell heater, and the energy utilization efficiency of heater with closed double-shell structure achieves 97.38%–99.59%. Finally, taking the comprehensive cost of in-situ exploitation of tar-rich coal into account, the small outer shell diameter is an optimal choice for the heater with closed double-shell structure.

Feasibility of Rescue Colonoscopy Using a Short-type Enteroscope (SIF-H290S) without Overtube after Incomplete Colonoscopy: A Single-center Retrospective Pilot Study.

Recently, a newly designed short-type single-balloon enteroscope (SBE), SIF-H290S, has been developed with a smaller outer diameter and a longer working length than conventional colonoscopes. It has passive bending and high-force transmission, making insertion easier. However, it is difficult to perform rescue colonoscopy with an SBE after incomplete colonoscopy in the same session. Therefore, this study evaluated the feasibility of consecutive rescue colonoscopy using SIF-H290S without overtube after incomplete colonoscopy. This was a single-center retrospective study. We included 19 rescue colonoscopies (19 patients) with SIF-H290S without overtube performed by 11 endoscopists in the SIF group and 38 rescue colonoscopies (38 patients) using a small-caliber colonoscope (PCF-PQ260L) were randomly selected for the control group from procedures performed by the same 11 endoscopists. We compared the cecal intubation rate and other outcomes, such as insertion time, between the two groups. The median age of the patients was 72 and 69 years, with 8 and 26 males in the SIF and control groups, respectively. The median body mass index was 21.6 and 22.7 kg/m2 in the SIF and control groups, respectively. There were no significant differences in the patient backgrounds between the groups, except for the reason for incomplete colonoscopy (p = 0.048). The cecal intubation rate was 78.9% (15/19 procedures) and 92.1% (35/38 procedures) in the SIF and control groups, respectively. This study revealed the real-world experience and feasibility of rescue colonoscopy using SIF-H290S, which could be a potential rescue device option after incomplete colonoscopy.

Converting polyolefin plastics into few-walled carbon nanotubes via a tandem catalytic process: Importance of gas composition and system configuration

Polyolefins such as polyethylene (PE) and polypropylene (PP) are abundant components of plastic waste. Chemical recycling of PE and PP via pyrolysis followed by chemical vapor deposition typically results in the growth of multi-walled carbon nanotubes (CNTs). Here, a tandem catalytic system for the growth of few-walled CNTs is reported. The successful synthesis of few-walled CNTs in the system relies on the catalytic processing of pyrolysis gas from plastics into intermediate gas mixtures containing mainly paraffins and hydrogen (700 °C, catalyst: 40 wt% Co, 10 wt% Mo and 50 wt% MgO). Under appropriate conditions (1000 °C, catalyst: Co 3 wt%, Mo 2 wt% and MgO 95 wt%, synthesis time: 20 min), the obtained intermediate gas mixture was selectively converted into few-walled CNTs with > 95% CNTs having small outer diameters of 1–7 nm, containing CNTs with as little as three walls and having distinct radial breathing mode in Raman spectra at wave lengths 100–400 cm−1. The proposed synthesis process opens new opportunities for production of high value few-walled CNTs from plastic waste.

Tailoring Fe2O3–Al2O3 catalyst structure and activity via hydrothermal synthesis for carbon nanotubes and hydrogen production from polyolefin plastics

Fe2O3–Al2O3 catalysts applied for conversion of polyolefin plastic waste into multi-walled carbon nanotubes (MWCNTs) and H2 are typically produced by impregnation, co-precipitation or sol-gel synthesis at atmospheric pressure and temperatures below 100 °C. This study utilized hydrothermal conditions and established the role of precipitating agents (urea, N-methylurea and N,N′-dimethylurea) on properties and catalytic activity of Fe2O3–Al2O3 catalysts (Fe-u, Fe-mu and Fe-dmu, respectively). The precipitating agent played a key role in tailoring the properties, such as crystallization degree, surface area and reducibility. The precipitating agents influenced the yield and outer diameters of MWCNTs but did not affect graphitization degree. Among the synthesized catalysts, Fe-u had the largest surface area and preferential formation of the highly reducible α-Fe2O3 crystalline phase. As a result, Fe-u had the highest activity during conversion of pyrolysis gas from low-density polyethylene (LDPE) into MWCNTs, yielding 0.91 g·g−1-catalyst MWCNTs at 800 °C as compared to 0.42 and 0.14 g·g−1-catalyst using Fe-dmu and Fe-mu, respectively. Fe-dmu favored the growth of MWCNTs with smaller outer diameters. Fe-u demonstrated high efficiency during operation using a continuous flow of pyrolysis gas from a mixture of polyolefins (70 wt% polypropylene, 6 wt% LDPE and 24 wt% high density polyethylene) producing 4.28 g·g−1-catalyst MWCNTs at 3.2% plastic conversion efficiency and a stable H2 flow for 155 min (25–32 vol%). The obtained data demonstrate that the selection of an appropriate precipitating agent for hydrothermal synthesis allows for the production of highly active Fe2O3–Al2O3 catalysts for the upcycling of polyolefin plastic waste into MWCNTs and H2.

Study on the Mechanical Extended-Reach Limit Prediction Model of Horizontal Drilling with Dual-Channel Drillpipes

Extended-reach horizontal wells are critical for the development of unconventional reservoirs. Dual-channel drill pipe drilling has a great advantage in improving the horizontal section length, while the research on its mechanical extended-reach limit prediction model is insufficient. In this paper, the torque and drag model is built considering the additional axial force of the sliding piston on the dual-channel drillpipe. Based on the torque and drag model, the mechanical extended-reach limit model for dual-channel drilling is established. A case study including a comparison to the conventional drilling method and sensitivity analysis is conducted. The result shows that under the same conditions, the mechanical extended-reach limit of the dual-channel drilling method is 10,592.2 m, while it is 9030.6 m of the conventional drilling method. The dual-channel drilling method achieves a further mechanical extended-reach limit than the conventional drilling method. To improve the mechanical extended-reach limit of dual-channel drilling, a higher back pressure on the sliding piston, a deeper measured depth of the sliding piston, a higher density of the passive drilling fluid, a smaller outer diameter of the outer pipe, a lower weight on bit and rate of penetration should be adopted. The work in this paper completes the extended-reach limit theory of dual-channel drilling, providing a guide for better use in unconventional reservoir development.

Abstract P170: Similarities And Differences In The Vascular Impact Of Estrogen Loss Versus G Protein-coupled Estrogen Receptor Deletion

Women in their postmenopausal years have an increased risk of cardiovascular disease, and recent research suggests that increased vascular stiffness can be detected within a year of the onset of menopause. We have previously demonstrated that the G Protein-Coupled Estrogen Receptor (GPER) protects the vasculature without noticeable changes in blood pressure, but little is known about the underlying structural changes that provide protection. In this study we assessed the impact of estrogen and the G protein-coupled estrogen receptor (GPER) on vascular health, with the hypothesis that loss of estrogen or deletion of smooth muscle cell (smc)-GPER would similarly increase vascular stiffness. Female mice were separated into three cohorts: intact wildtype, ovariectomized (OVX), and GPER smc-KO. OVX occurred at 8 weeks of age and 8 weeks later blood pressure was measured via tail-cuff plethysmography, arterial stiffness was measured as pulse wave velocity (PWV) via high resolution ultrasound, and carotids were excised for biaxial pressure myography and imaging. Uterine weight in OVX mice (0.03 g) was significantly lower than intact mice (0.1 g; p=0.0002) confirming the loss of estrogen. No difference was observed in systolic blood pressure, however, both the OVX (1.5 m/s) and smc-KO (1.9 m/s) groups had significantly higher PWV than intact controls (1.2 m/s; p=0.02 and p=0.03, respectively). Carotids of OVX (366 μm) and smc-KO (389 μm) mice had a smaller outer diameter versus controls (441 μm; p &gt;0.05) without a difference in thickness. Despite the similar responses of OVX and smc-KO groups, Masson’s trichrome staining of carotid sections showed significantly more smooth muscle area fraction in OVX (p=0.005), but not KO mice, and no difference in collagen area fraction. These data indicate that while estrogen loss and smc-KO of GPER both increase arterial stiffness, increased smooth muscle due to estrogen loss is likely not modulated through GPER. Future experiments will aim to understand how other components, such as extracellular matrix genes, may be affected by loss of GPER.

Cuffed endotracheal tubes in neonates and infants of less than 3kg body weight-A retrospective audit.

Large prospective clinical studies have shown that modern cuffed pediatric tracheal tubes can be used safely, even in children weighing ≥3kg. There is a growing interest in their use in children weighing <3kg so that they, too, can benefit from the potential advantages, particularly the high probability of these tubes fitting into and sealing the pediatric airway at the first intubation attempt. This study aimed to find a cut-off body weight for procedures requiring a cuffed tracheal tube to seal the airway in children weighing <3kg and to evaluate the frequency and predictive factors for the requirement to place a cuffed instead of an uncuffed tracheal tube. This study was a retrospective analysis of 269 children weighing 2000-2999g, primarily intubated by pediatric anesthetists. Frequency of intubation with uncuffed Sheridan tubes versus cuffed Microcuff® Pediatric Endotracheal Tube (PET) 3.0mm ID was studied. Predictive variables were assessed by means of logistic regression analysis. The ROC curve for weight at intubation time and Youden index was calculated. The 149 (55.4%) children were finally intubated with a cuffed tracheal tube. Logistic regression demonstrated that body weight at tracheal intubation and birth weight were the strongest predictors for the appropriateness of cuffed/uncuffed tracheal tubes. The threshold weight at tracheal intubation was 2700g for a probability >50% of using a cuffed tracheal tube. Half of the children weighing 2000-2999g received a Microcuff® PET 3.0mm ID, especially those with a body weight above 2700g. Because of the anatomical dimensions in patients with a body weight of 2000-2999g, cuffed tracheal tubes with smaller outer diameters may be required to better fit their airways.

Новый способ проведения комбинированной двухуровневой спинально-эпидуральной анестезии при оперативном лечении переломов шейки бедра

We describe the technique of combined two-level spinal-epidural anesthesia with the use of a new method of fixing an epidural catheter in the subcutaneous canal using a modified spinal needle in the surgical treatment of hip fractures. The quality of this method of anesthesia and postoperative anesthesia depends on the reliability and safety of fixing the epidural catheter. We have developed and tested in clinical practice a method of conducting and fixing an epidural catheter in the subcutaneous canal using a modified spinal needle. The peculiarity of this method is that the modified spinal needle used can be used to conduct and fix the epidural catheter in the subcutaneous canal. The characteristics of this needle, such as small outer diameter, sharp sharpening and length from 88 to 120 mm, made the tunneling of the epidural catheter safe and fixation reliable. The new method of fixing the epidural catheter in the subcutaneous canal has reduced the number of cases with clinically significant dislocation of the epidural catheter by 2.7 times, and cases with catheter loss from the epidural space by 3 times compared to the method of fixing the epidural catheter with a patch sticker, which is the most common in anesthesiological practice.

Spherical submicron YAG:Ce particles with controllable particle outer diameters and crystallite sizes and their photoluminescence properties.

The purpose of this study was to demonstrate the preparation of spherical submicron YAG:Ce particles with controllable particle outer diameters and crystallite sizes and their photoluminescence (PL) properties, which were produced using a flame-assisted spray-pyrolysis method followed by the annealing process. The correlation of particle outer diameter, crystallite size, and PL performance of the prepared particles was also investigated. Experimental results showed that the increases in the particle outer diameters have an impact on the obtainment of higher PL performance. Large particle outer diameters permitted the crystallites to grow more, whereas this is in contrast to the condition for small particle outer diameter having limitations in crystallite growth. This study also found that too large outer diameter (>557 nm) was not effective since crystallites cannot grow anymore and it permits possible scattering problems. This study provides significant information for optimizing synthesis parameters for controlling particle outer diameters and crystallite sizes, which could be relevant to other functional properties, especially for lens, solar cell, and LED applications.

DEVELOPMENT OF CARBON NANOTUBE AS HIGHLY ACTIVE PHOTOCATATLYTIC ADSORBENT FOR TREATMENT OF ACID RED 88 DYE

In recent years, photocatalysts have been used in various fields, and are particularly attracting attention in the fields of environment, medicine, and agriculture. A large number of catalytic active sites are required to produce a more efficient photocatalyst, and for that purpose, a large specific surface area is desired. Therefore, in this study, in order to develop a highly active photocatalytic material, the outer diameter of titanium oxide nanotubes was controlled by a template synthesis method using carbon nanotubes with different outer diameters to increase the specific surface area. Characterization was carried out by using diffent analytical instruments such as UV-Spectrophotomoter, XRD, SEM, TEM, BET. Results show using titanium oxide nanotubes with a smaller outer diameter tended to have higher photocatalytic activity (almost complete degradation was obtained when 10-20nm was used).

Типы и стадии сосудистого ремоделирования при контрактуре Дюпюитрена (анализ 506 артерий в операционном материале 111 пациентов)

Purpose Analysis of the severity and staging of pathomorphological changes in the arteries of palmar aponeurosis in patients with Dupuytren's contracture of different age groups Materials and methods Analysis of case records of patients younger than 50 years old (n = 19, group 1), from 50 to 65 years old (n = 60, group 2) and over 65 years old (n = 32, group 3). Light microscopy of paraffin sections of palmar aponeurosis fragments resected in partial fasciectomy and histomorphometry of palmar aponeurosis arteries of three calibers: small (outer diameter less than 150 microns), medium (150–300 microns), large (more than 300 microns). Control samples – fragments of the aponeurosis of three patients younger than 50 years old with hand injuries. Results Groups 1–3 arecomparable in terms of fibromatosis duration, frequency of lesions in both hands, and the number of fingers with impaired function, but in group 3 the frequency of contractures in advanced stages and cardiovascular diseases was higher (p less 0.05). In arteries of small caliber, obliterating lesions and signs of expansive remodeling were also encountered; in arteries of medium caliber, expansive remodeling prevailed; in arteries of large caliber, constrictive remodeling was expressed. Discussion The types of remodeling identified were found in all age groups. Based on the results of the study and the data obtained earlier, 6 stages of pathomorphological changes in the vessels of the palmar aponeurosis were identified in Dupuytren's contracture. Conclusion Dupuytren's contracture refers to diseases mediated by vascular remodeling, affecting mainly the arterial bed, the severity and staging of which does not depend on the age of a patient

Classification and modeling of flooding in vertical narrow rectangular and annular channels according to channel-end geometries

In this study, data classification and modeling of the flooding phenomenon were performed in a narrow channel with a gap thickness of several millimeters. To implement the conventional classification study to a narrow channel case, three key ideas for two-phase flow in a narrow channel were proposed; characteristic length, the flow path for each phase and a concept of unit-cell that can unify both narrow rectangular and annular channels including large outer diameter. Based on the ideas, 330 flooding data points for both narrow rectangular and annular channels including large outer diameter were classified into exit flooding and entrance flooding according to the geometries of the liquid inlet. In order to develop the prediction model for flooding in a narrow channel, the hyperbolicity breaking concept was introduced. The present flooding model was derived based on the hyperbolicity breaking of the two-fluid model and produced the Root Mean Square Errors (RMSE) of 30.02% in terms of the superficial gas velocity against the 330 flooding data points from narrow rectangular and annular channels with relatively small outer diameter. Moreover, the proposed model was applied to a case of narrow-large diameter annuli with the introduction of the number of the unit-cells producing the RMSE of 26.11% against 91 flooding data points. The RMSEs of the existing models for narrow rectangular and narrow large-diameter annuli were 38.25% and 31.10%, respectively. Different from the existing models, the proposed model turned out that it is applicable to various narrow channel-types; a rectangular, an annular and an annulus with a large diameter.

Thin-diameter polarization maintaining hollow-core photonic bandgap fiber for fiber optic gyroscope

Abstract PBGFs (photonic bandgap fibers) are superior to traditional optical fiber in terms of reduced optical nonlinearity, enhanced thermal stability, and insensitivity against radiation and magnetic field, which are key to improve the performance of fiber optical gyroscopes (FOG). For application in FOG, PBGF of small outer diameter is preferred to effectively increase the cavity length while maintaining the volume of device. In this paper, a special design of PBGFs is explored and a loss of about 15 dB/km at 1550 nm wavelength with birefringence of 1.2 × 10−4 can be obtained when the bare fiber outer diameter is 80 μm. This small outer diameter PBG design shows a promising potential for FOG application.