Sealed System Research Articles

Two-Year Outcomes of the Nellix EndoVascular Aneurysm Sealing System for Treatment of Abdominal Aortic Aneurysms

Purpose: To analyze the 2-year outcomes of endovascular aneurysm sealing (EVAS) according to 2 versions of the instructions for use (IFU). Methods: A retrospective study was conducted involving 355 consecutive patients treated with the first-generation EVAS device from April 2013 to December 31, 2015, at 3 high-volume centers. Out of 355 patients treated with EVAS, 264 were elective asymptomatic infrarenal EVAS procedures suitable for analysis. In this cohort, 168 (63.3%) patients were treated within the IFU 2013 criteria; of these 48 (18.2%) were in compliance with the revised IFU 2016 version. Results: Overall technical success was 98.2% (165/168) in the IFU 2013 group and 97.9% (47/48) in the IFU 2016 subgroup (p=0.428). The 2-year freedom from reintervention estimates were 89.7% (IFU 2013) and 95.7% (IFU 2016), with significantly more reinterventions in the first 45 cases (p=0.005). The stenosis/occlusion estimates were 6.5% (IFU 2013) and 4.2% (IFU 2016; p=0.705). Nine (5.4%) endoleaks (8 type Ia and 1 type Ib) were observed within the IFU 2013 cohort; 3 (2.1%) were in the IFU 2016 subgroup (p=0.583). Migration ≥10 mm or ≥5 mm requiring intervention was reported in 12 (7.1%) patients in the IFU 2013 cohort but none within the IFU 2016 subgroup. Ten (6.0%) patients demonstrated aneurysm growth in the IFU 2013 cohort, of which 2 (4.2%) were in the IFU 2016 subgroup. Overall survival and freedom from aneurysm-related death estimates at 2 years were 90.9% and 97.6% in the IFU 2013 cohort (IFU 2016: 95.5% and 100.0%). The prevalence of complications seemed lower within IFU 2016 without significant differences. Conclusion: This study shows acceptable 2-year results of EVAS used within the IFU, without significant differences between the 2 IFU versions, though longer follow-up is indicated. The refined IFU significantly reduced the applicability of the technique.

Micromechanical processes in consolidated granular salt

Granular salt is likely to be used as backfill material and a seal system component within geologic salt formations serving as a repository for long-term isolation of nuclear waste. Pressure from closure of the surrounding salt formation will promote consolidation of granular salt, eventually resulting in properties comparable to native salt. Understanding dependence of consolidation processes on stress state, moisture availability, temperature, and time is important for demonstrating sealing functions and long-term repository performance. This study characterizes laboratory-consolidated granular salt by means of microstructural observations. Granular salt material from mining operations was obtained from the bedded Salado Formation hosting the Waste Isolation Pilot Plant and the Avery Island salt dome. Laboratory test conditions included hydrostatic consolidation of jacketed granular salt with varying conditions of confining isochoric stress to 38 MPa, temperature to 250 °C, moisture additions of 1% by weight, time duration, and vented and non-vented states. Resultant porosities ranged between 1% and 22%. Optical and scanning electron microscopic techniques were used to ascertain consolidation mechanisms. From these investigations, samples with 1% added moisture or unvented during consolidation, exhibit clear pressure solution processes with tightly cohered grain boundaries and occluded fluid pores. Samples with only natural moisture content consolidated by a combination of brittle, cataclastic, and crystal plastic deformation. Recrystallization at 250 °C irrespective of moisture conditions was also observed. The range and variability of conditions applied in this study, combined with the techniques used to display microstructural features, are unique, and provide insight into an important area of governing deformation mechanism(s) occurring within salt repository applications.

Female harbor seal (Phoca vitulina) behavioral response to playbacks of underwater male acoustic advertisement displays.

During the breeding season, male harbor seals (Phoca vitulina) make underwater acoustic displays using vocalizations known as roars. These roars have been shown to function in territory establishment in some breeding areas and have been hypothesized to be important for female choice, but the function of these sounds remains unresolved. This study consisted of a series of playback experiments in which captive female harbor seals were exposed to recordings of male roars to determine if females respond to recordings of male vocalizations and whether or not they respond differently to roars from categories with different acoustic characteristics. The categories included roars with characteristics of dominant males (longest duration, lowest frequency), subordinate males (shortest duration, highest frequency), combinations of call parameters from dominant and subordinate males (long duration, high frequency and short duration, low frequency), and control playbacks of water noise and water noise with tonal signals in the same frequency range as male signals. Results indicate that overall females have a significantly higher level of response to playbacks that imitate male vocalizations when compared to control playbacks of water noise. Specifically, there was a higher level of response to playbacks representing dominant male vocalization when compared to the control playbacks. For most individuals, there was a greater response to playbacks representing dominant male vocalizations compared to playbacks representing subordinate male vocalizations; however, there was no statistical difference between those two playback types. Additionally, there was no difference between the playbacks of call parameter combinations and the controls. Investigating female preference for male harbor seal vocalizations is a critical step in understanding the harbor seal mating system and further studies expanding on this captive study will help shed light on this important issue.

Microwave-assisted transesterification of glycerol with dimethyl carbonate over sodium silicate catalyst in the sealed reaction system

Microwave-assisted transesterification of glycerol to glycerol carbonate (GC) using calcined sodium silicate (Na2SiO3) as a catalyst in the sealed reaction system was studied in this work. Effects of the parameters, including the molar ratio of dimethyl carbonate (DMC) to glycerol, the reaction temperature, the amount of the catalyst, the reaction time and, especially, the microwave-assisted reaction modes on glycerol conversion and GC yield were carefully investigated. It was found that the microwave-assisted reaction modes, namely, the temperature constant mode (TCM) and the power constant mode (PCM), greatly influenced the reaction. When the reaction was conducted in TCM, with the catalyst amount of 5 wt%, reaction temperature of 95 °C, DMC-to-glycerol molar ratio of 4:1, and reaction time of 15 min, the glycerol conversion and the GC yield reached 96.7% and 94.3%, respectively. Similar glycerol conversion and GC yield were also obtained under the condition of the catalyst amount of 1 wt%, DMC-to-glycerol molar ratio of 4:1, microwave irradiation input power of 175 W and reaction time of 50 s in PCM. The reaction in PCM showed much more advantages in reducing the amount of the catalyst and shortening the reaction time than that in TCM. Meanwhile, the transesterification of glycerol with DMC in PCM catalyzed by Na2SiO3 exhibited much higher reaction rate than that catalyzed by CaO. Moreover, in terms of the reaction in PCM, energy consumption could be reduced with the increase of the irradiation power. The investigation on the reusability of the Na2SiO3 catalyst in PCM showed that this catalyst could be reused in five reaction cycles without significant deactivation.

Lightweight, compact, and high-performance 3T MR system for imaging the brain and extremities.

To build and evaluate a small-footprint, lightweight, high-performance 3T MRI scanner for advanced brain imaging with image quality that is equal to or better than conventional whole-body clinical 3T MRI scanners, while achieving substantial reductions in installation costs. A conduction-cooled magnet was developed that uses less than 12 liters of liquid helium in a gas-charged sealed system, and standard NbTi wire, and weighs approximately 2000 kg. A 42-cm inner-diameter gradient coil with asymmetric transverse axes was developed to provide patient access for head and extremity exams, while minimizing magnet-gradient interactions that adversely affect image quality. The gradient coil was designed to achieve simultaneous operation of 80-mT/m peak gradient amplitude at a slew rate of 700 T/m/s on each gradient axis using readily available 1-MVA gradient drivers. In a comparison of anatomical imaging in 16 patients using T2 -weighted 3D fluid-attenuated inversion recovery (FLAIR) between the compact 3T and whole-body 3T, image quality was assessed as equivalent to or better across several metrics. The ability to fully use a high slew rate of 700 T/m/s simultaneously with 80-mT/m maximum gradient amplitude resulted in improvements in image quality across EPI, DWI, and anatomical imaging of the brain. The compact 3T MRI system has been in continuous operation at the Mayo Clinic since March 2016. To date, over 200 patient studies have been completed, including 96 comparison studies with a clinical 3T whole-body MRI. The increased gradient performance has reliably resulted in consistently improved image quality.

Numerical study of transient flow in the preliminary design of fusion power shutdown system

The FPSS (fusion power shutdown system) provides a safety emergency shutdown system terminating the ITER (international thermonuclear experimental reactor). It has a reservoir of impurity gas and a dedicated tube for the impurity gas injection. In the preliminary design stage, the FPSS is studied as a sealed gas injection system, it is a supersonic and high pressure flow field. The transient flow of the system is analyzed with a commercial CFD code, ANSYS® FLUENT in this paper. To satisfy the functional requirement, the injected gas volume of the VV (vacuum vessel) is predicted from a series of tank pressures in 3s. The influence of initial tank pressures, vessel pressure and flow times of the FPSS is quantified. CFD data is compared with the experimental activities and the discrepancy is acceptable. All the results will be used for optimized design of the FPSS.

Greater Compliance within Instruction for Use for Concomitant Iliac Aneurysms and Adverse Aneurysm Characteristics–Initial Experience with the Nellix Endovascular Aneurysm Sealing System at a Single Institution

The Nellix was introduced to Asia in 2014. Data in Asians have been sparse. Twoballoon-expandable stents, each surrounded by a polymer-filled endobag, are deployed in parallel to obliterate and seal the aneurysm. This paradigm shift to treating abdominal aortic aneurysms confers advantages for certain adverse aneurysm morphology that is outside the instruction-for-use (IFU) for standard endovascular aneurysm repair (EVAR) devices. We examine outcomes of 15 Asian patients with concomitant infrarenal aortic and iliac artery aneurysms treated with the Nellix at our institution. Between July 2014 and August 2016, 15 male patients underwent elective EVAS at a single tertiary center by the same team of vascular surgeons and interventional radiologists. Patient demographics, clinical presentations, aneurysm morphology, perioperative complications, and follow-up imaging according to the standardized protocol were studied. Preoperative CT images were analyzed using validated automatic 3-dimensional sizing software EndoSize. The novel stent-graft deployment proves consistent and achieved a 100% technical success. Eleven patients (70%) complied within specified Nellix IFU, as compared to 20% if standard endovascular aneurysm repair (EVAR) IFU was applied. The difference is due to the presence of concurrent common iliac aneurysms (n=5), short neck length (n=3), and angulated necks (n=3). Adjunct procedures included 3 open access endarterectomy with embolectomy, 1 coil embolization of internal iliac artery, 1 bilateral renal artery chimneys, and 1 proximal stent deployment. There was no conversion to open surgery. Average operative time was 133min. Median length of stay was 4days. Thirty-day mortality was 0%. Perioperative morbidity included exacerbation of pre-existing renal impairment (n=6), peripheral vascular disease (n=3), and postimplantation syndrome (n=5). One endoleak (7%) and 2 instances of stent migration (14%) were detected. There was no complication of aneurysm or endobag rupture, limb thromboses, or fracture. Early data in our center are encouraging and highlight high procedural success with minimal complications despite challenging patient anatomy.

Prolonged Corrosion Stability of a Microchip Sensor Implant during In Vivo Exposure.

A microelectronic biosensor was subjected to in vivo exposure by implanting it in the vicinity of m. trapezii (Trapezius muscle) from cattle. The implant is intended for the continuous monitoring of glucose levels, and the study aimed at evaluating the biostability of exposed semiconductor surfaces. The sensor chip was a microelectromechanical system (MEMS) prepared using 0.25 µm complementary metal–oxide–semiconductor CMOS/BiCMOS technology. Sensing is based on the principle of affinity viscometry with a sensoric assay, which is separated by a semipermeable membrane from the tissue. Outer dimensions of the otherwise hermetically sealed biosensor system were 39 × 49 × 16 mm. The test system was implanted into cattle in a subcutaneous position without running it. After 17 months, the device was explanted and analyzed by comparing it with unexposed chips and systems. Investigations focused on the MEMS chip using SEM, TEM, and elemental analysis by EDX mapping. The sensor chip turned out to be uncorroded and no diminishing of the topmost passivation layer could be determined, which contrasts remarkably with previous results on CMOS biosensors. The negligible corrosive attack is understood to be a side effect of the semipermeable membrane separating the assay from the tissue. It is concluded that the separation has enabled a prolonged biostability of the chip, which will be of relevance for biosensor implants in general.

Status of Endovascular Aneurysm Sealing After 5 Years of Commercial Use

Endovascular aneurysm sealing (EVAS) using the Nellix Endovascular Sealing System was introduced commercially in 2013 with the aim of reducing the incidences of reintervention and late complications observed after conventional endovascular aneurysm repair (EVAR). In the 5 years since its commercial launch, the Nellix system has evolved in terms of its structure, instructions for use, and delivery technique. Complications, including migration and proximal endoleak, have been recognized and treatment strategies developed, although durability remains to be demonstrated. Prospective multicenter trials have shown a low incidence of type I endoleak and reintervention at 1-year follow-up, comparable to conventional EVAR with modern devices. Since the aneurysm sac is “actively managed” with EVAS, similar to open surgical repair, type II endoleaks are rare with the Nellix system. Unexpected benefits of active sac management with EVAS include reduced incidences of postimplantation syndrome and cardiac complications, with low all-cause mortality at 1 year. Less neck dilatation compared to EVAR has also been observed. The Nellix device and procedure continue to evolve, and further prospective studies are indicated. This article analyzes the current EVAS evidence to update our knowledge of this technique in the management of abdominal aortic aneurysm.

A Member of Fluorooxoborates: Li2Na0.9K0.1B5O8F2 with the Fundamental Building Block B5O10F2 and a Short Cutoff Edge.

A new member of fluorooxoborates, Li2Na0.9K0.1B5O8F2, was obtained in the sealed system, and single-crystal X-ray diffraction was used to determine its structure. It contains a three-dimensional framework stacking of [B5O8F2]3- layers extending into the ac plane. Detailed structural comparisons among all of the fluorine-containing alkali-metal borates suggest that the [B5O8F2]3- layer composed of the new fundamental building blocks B5O10F2 represents a new structure type of fluorooxoborate. The IR spectrum verifies its structural validity. The deep-ultraviolet spectral measurement shows that it has no obvious absorption in the range of 180-300 nm, and its cutoff edge is under 180 nm. In addition, theoretical calculations were done to help us understand its electronic structure and optical properties.

A guard to reduce the accidental oxidation of PbTe nanocrystals.

In the synthesis of lead telluride nanocrystals (PbTe NCs), oxidized PbTe is commonly regarded as a waste material as this will reduce the performance of pure PbTe NCs. The waste is normally thrown away, leading to potential environment risks and is less economical in terms of atom usage. Conventional anti-oxidation methods such as inert gas flow or sealed systems cannot deal with leaking or accidental contamination. To solve this problem, by simulating accidental oxidation, we utilized a cheap and easily-performed strategy to reduce the oxidation to a very low level. Further analysis indicates that this anti-oxidation effect should be due to interactions between the double bonds from the coating ligands and the extended π bonds from the benzene rings. This strategy increases the synthesis efficiency of the reactants and reduces the environmental pollution risk.

Thermal-Mechanical Coupled FE Analysis for Rotary Shaft Seals

The aim of this paper is to model the steady-state condition of a rotary shaft seal (RSS) system. For this, an iterative thermal-mechanical algorithm was developed based on incremental finite element analyzes. The behavior of the seal’s rubber material was taken into account by a large-strain viscoelastic, so called generalized Maxwell model, based on Dynamic Mechanical Thermal Analyses (DMTA) and tensile measurements. The pre-loaded garter spring was modelled with a bilinear material model and the shaft was assumed to be linear elastic. The density, coefficient of thermal expansion and the thermal conductance of the materials were taken into consideration during simulation. The friction between the rotary shaft seal and the shaft was simplified and modelled as a constant parameter. The iterative algorithm was evaluated at two different times, right after assembly and 1 h after assembly, so that rubber material’s stress relaxation effects are also incorporated. The results show good correlation with the literature data, which state that the permissible temperature for NBR70 (nitrile butadiene rubber) material contacting with ~80 mm shaft diameter, rotating at 2600/min is 100°C. The results show 107°C and 104°C for the two iterations. The effect of friction induced temperature, changes the width of the contact area between the seal and the shaft, and significantly reduces the contact pressure.

Mainstreaming Sustainable Investing

“Mainstreaming Sustainable Investing” is the title, tagline, and guiding principle of the annual Sustainable Investing Seminars run by CFA Society Boston since 2013. In that first year, the idea of “mainstreaming” sustainable investing seemed wildly aspirational to many. Yet by the time the society held its fourth annual seminar in November 2016, aspiration had been surpassed by reality, as the increasing attendance and diversity of the audience reflected the change that was underway in the industry. To put this development into perspective, though, it is necessary to more clearly articulate what is meant by both “mainstreaming” and “sustainable investing.” A simple and widely used definition of sustainability is taken from a 1987 report on sustainable development prepared for the United Nations by the Brundtland Commission: “Sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs.” This definition will sound familiar to investment professionals involved with endowments and families as the concept of intergenerational equity. The purpose of investing is to apply capital to productive use, addressing opportunities and challenges facing societies and economies, thereby building value over time for the investors supplying that capital. But that value-building economic activity does not take place within a hermetically sealed financial system. Value creation takes place in and depends on environmental, social, and governance systems. It requires the assets and resources those systems provide. Economic activity that is not sustainable degrades those systems, diminishing their future viability and value. Sustainable economic activity maintains or enhances those systems, increasing their future viability and value. The future value of the investment depends heavily on the future state of those systems. The investment profession has a well-developed language and formal system for measuring and assessing the value created (or destroyed) by financial capital. We use these financial factors and indicators in this work. But we do not yet have a similarly robust system for assessing the value created or destroyed by the use or misuse of environmental, social, and governance (ESG) capital. What we do have is an evolving language of ESG issues, factors, and indicators. The core of sustainable investing is incorporating these ESG issues, factors, and indicators into the investment process. Viewed through this lens, considering the ESG impacts on future value contributes to fulfilling our mandate as investment professionals. As Erika Karp, the opening speaker at the first Sustainable Investing Seminar in 2013, observed, “Sustainable investing is just investing.”

Reliability improvement of compressors based on asset fleet reliability data

Physical assets of the process industries include compressors, pumps, heat exchangers, batch reactors and many more. A large company that operates over many sites typically manages such assets in a coordinated way as an asset fleet. Strategic planning of maintenance and scheduling requires information about reliability, availability and maintainability of the assets in an asset fleet.The work presented in this paper assesses the reliability of centrifugal compressors based on the data collected in OREDA (Offshore and onshore REliability DAta project). The fault tree (a top-down approach to illustrate all subsystems in a system) has been modeled by focusing on the six main subsystems of the compressor (power transmission, compressor, control and monitoring, lubrication system, shaft seal system, and miscellaneous). All the maintainable items described in ISO 14224 are considered. Based on the failure rates collected in OREDA, the most prevalent failures have been identified via a Pareto analysis. The article gives recommendations which subsystems should be prioritized for maintenance and which types of faults are likely to occur. The main contribution of this paper is an industry-based statistical analysis of the failure mechanisms in centrifugal compressor systems. It is expected to improve the reliability of centrifugal compressor systems and can be implemented in industrial settings with a similar documentation system like OREDA.

Ligasure versus EndoGIA Stapler for Hilar Vascular Control During Laparoscopic Splenectomy for Adult Chronic ITP

Background: The major procedural risk associated with laparoscopic splenectomy (LS) for adult chronic immune thrombocytopenia (ITP), is uncontrollable intraoperative bleeding, requiring conversion to laparotomy. There are several methods of achieving hemostasis, including clips, sutures, Ligasure and EndoGIA stapler. Patients and methods: Between April 2015 and May 2017, 32 adult patients with chronic ITP indicated for LS, were divided into two equal groups, according to the method of hilar vascular control (group 1, Ligasure Vessel Sealing System; group 2, EndoGIA stapler). The perioperative course was documented and the follow up data were recorded. Results: Two patients (6.25%) were converted to open splenectomy. Four patients (12.5%) had persistent thrombocytopenia after surgery. The cost was higher in group B. No significant difference was found between both groups regarding post-operative complications. Conclusion: For adult chronic ITP, both Ligasure and EndoGIA stapler are safe and effective for hilar vascular control during LS. The results are similar and comparable, but Ligasure is less costly than EndoGIA stapler.

0.65 MPa高水压盾构机新型盾尾密封系统设计与研究

0.65 MPa高水压盾构机新型盾尾密封系统设计与研究

Adhesion of Sickle RBCs to Heme-Activated Endothelial Cells Correlates with Patient Clinical Phenotypes

Severe hemolysis and associated high levels of hemolytic biomarkers, including LDH and heme, are among major constituents of the pathophysiology of sickle cell disease (SCD). Elevated extracellular heme due to hemolysis overwhelms endogenous detoxification mechanisms and leads to oxidative stress, triggering systemic endothelium activation, vascular dysfunction, and end organ damage. To understand the role of red blood cells (RBC) in this process, we assessed sickle RBC adhesion to heme-activated endothelial cells utilizing an endothelialized microfluidic platform in a clinically diverse patient population.Human umbilical vein endothelial cells (HUVECs) were seeded into fibronectin (FN) functionalized microfluidic channels and incubated for 4 hours in a 37°C and 5% CO2 environment. Next, the confluent monolayers were loaded and incubated for 45 minutes with fresh culture medium or at one of two concentrations of heme solutions: (1) 20 μM that corresponds to physiological heme levels in SCD patients, and (2) 40 μM. SCD blood samples, collected from 8 patients (7 HbSS and 1 HbS/β0 thal; 3 males and 5 females), were centrifuged to remove the plasma and washed with PBS thrice prior to flow experiments. RBCs were re-suspended in culture medium at a hematocrit of 25%. A total volume of 15 µl RBC suspension was perfused into the microchannels followed by rinsing with fresh culture medium at 1 dyne/cm2, which corresponds to the typical shear stress value observed in post-capillary venules. The fully closed and hermetically sealed microfluidic system design ensured the stability of gas composition in the culture medium during the experiments.Endothelialized microchannels supported sickle RBC adhesion to non-treated, 20 µM heme-activated, and 40 µM heme-activated HUVECs (Fig. 1A, B, C). Adhesion results suggested that activation of HUVECs by heme mediated RBC adhesion in a concentration-dependent manner, with a significant difference observed at 40 µM (Fig. 1D, paired t-test, p<0.05). Notably, a heterogeneous heme-mediated adhesion profile was seen among patients. Sickle RBC adhesion to 20 μM heme-activated HUVECs was significantly increased in patients with higher LDH levels (Fig. 1E, p=0.024, ANOVA), higher absolute reticulocyte counts (Fig. 1F, p=0.002, ANOVA), and lower total hemoglobin (Fig. 1G, p=0.016, ANOVA), which are indicative of elevated hemolysis. All patients in the high adhesion group (>200 adherent RBCs) had elevations in serum LDH levels and in absolute reticulocyte counts. Moreover, patients with a recent transfusion had higher RBC adhesion to 40 µM heme-activated HUVECs compared to patients with no transfusion in the last 3 months (Fig. 1H, p<0.05, ANOVA).Here, we report a direct link between heme-driven endothelial activation and RBC adhesion in a patient-specific manner. In patients with a more severe clinical phenotype, as reflected in LDH, total hemoglobin, and absolute reticulocyte or recent blood transfusions, we found greater RBC adhesion to heme-activated HUVECs. These findings suggest that RBCs from those patients most likely to experience hemolysis in vivo may also be those RBCs most likely to adhere to heme-activated endothelium.Acknowledgments: This work was supported by grants #2013126 and #2015191 from the Doris Duke Charitable Foundation, National Heart Lung and Blood Institute R01HL133574, and National Science Foundation CAREER Award 1552782.Figure 1: Sickle RBC adhesion to heme-activated HUVECs and clinical associations. Sickle RBCs adherent to immobilized HUVECs in (A) non-activated, (B) 20 µM heme-activated, and (C) 40 µM heme-activated microchannels. The microscope images illustrate a small portion of the full microchannel surface. (D) RBC adhesion to HUVECs increased depending on the heme concentration, with a significant difference at the 40 µM level (paired t test, p<0.05). Patients with higher LDH (E) as well as absolute reticulocyte counts (F), and lower total hemoglobin (G) showed significantly greater RBC adhesion to 20 µM heme-activated HUVECs (ANOVA). (H) Furthermore, patients with a recent transfusion history displayed elevated RBC adhesion to 40 µM heme-activated HUVECs compared to non-transfused patients (ANOVA). The dashed rectangles indicate the normal clinical values for healthy individuals, while all patients had total hemoglobin levels lower than normal. Scale bars represent 30 µm. [Display omitted] DisclosuresLittle:Hemex Health: Equity Ownership. Gurkan:Hemex Health: Employment, Equity Ownership.

Effects of chlorhexidine preprocedural rinse on bacteremia in periodontal patients: a randomized clinical trial.

Objective:Single dose of systemic antibiotics and short-term use of mouthwashes reduce bacteremia. However, the effects of a single dose of preprocedural rinse are still controversial. This study evaluated, in periodontally diseased patients, the effects of a pre-procedural mouth rinse on induced bacteremia.Material and Methods:Systemically healthy individuals with gingivitis (n=27) or periodontitis (n = 27) were randomly allocated through a sealed envelope system to: 0.12% chlorhexidine pre-procedural rinse (13 gingivitis and 13 periodontitis patients) or no rinse before dental scaling (14 gingivitis and 15 periodontitis patients). Periodontal probing depth, clinical attachment level, plaque, and gingival indices were measured and subgingival samples were collected. Blood samples were collected before dental scaling, 2 and 6 minutes after scaling. Total bacterial load and levels of P. gingivalis were determined in oral and blood samples by real-time polymerase chain reaction, while aerobic and anaerobic counts were determined by culture in blood samples. The primary outcome was the antimicrobial effect of the pre-procedural rinse. Data was compared by Mann-Whitney and Signal tests (p<0.05).Results:In all sampling times, polymerase chain reaction revealed higher blood bacterial levels than culture (p<0.0001), while gingivitis patients presented lower bacterial levels in blood than periodontitis patients (p<0.0001). Individuals who experienced bacteremia showed worse mean clinical attachment level (3.4 mm vs. 1.1 mm) and more subgingival bacteria (p<0.005). The pre-procedural rinse did not reduce induced bacteremia.Conclusions:Bacteremia was influenced by periodontal parameters. In periodontally diseased patients, pre-procedural rinsing showed a discrete effect on bacteremia control.

How Can Autonomous and Connected Vehicles, Electromobility, BRT, Hyperloop, Shared Use Mobility and Mobility-As-A-Service Shape Transport Futures for the Context of Smart Cities?

A smarter transport system that caters for social, economic and environmental sustainability is arguably one of the most critical prerequisites for creating pathways to more livable urban futures. This paper aims to provide a state-of-the-art analysis of a selection of mobility initiatives that may dictate the future of urban transportation and make cities smarter. These are mechanisms either recently introduced with encouraging uptake so far and much greater potential to contribute in a shift to a better transport paradigm or still in an embryonic stage of their development and yet to be embraced as powerful mechanisms that could change travel behaviour norms. Autonomous and connected vehicles are set to revolutionise the urban landscape by allowing machines to take over driving that for over a century has been exclusively a human activity, while electrical vehicles are already helping decarbonising the transport sector. Bus rapid transit has been steadily reinventing and rebranding conventional bus services revitalising the use of the humblest form of public transport, while hyperloop is an entirely new, disruptive, and somewhat provocative, travel mode proposition based on the use of sealed tube systems through which pods could travel free of air resistance with speeds exceeding 1000 km/h. Shared use mobility mechanisms like car-sharing, ride-sharing, ride-sourcing and public bicycles can help establishing a culture for using mobility resources on an as-needed basis, while mobility-as-a-service will take this sharing culture a step further, offering tailored mobility and trip planning packages that could entirely replace the need for privately owned modes of transport.

Experimental and Optimization Design of Offshore Drilling Seal

Abstract Three-cone bit is the key equipment in the exploration of the oil in offshore drilling and exploration, the bearing system and the seal system are the critical components for the bit. Especially in the offshore drilling environment, the seal design need to be carefully considered. A multi-objective optimization design including orthogonal design method and F-test with finite element analysis for a three-cone bit seal is proposed. Firstly, the calculation method of optimization targets are given, including the minimization of maximum contact pressure and leakage rate analyzed by ANSYS and MATLAB respectively, to maximize seal life and reliability. Then, an orthogonal experiment approach is used to investigate the effects of the eleven parameters on the seal performance, and the influence degrees of the seal factors on the optimization targets have been confirmed by F-test, and the reasonable factors can be determined by the trend of the targets. Finally, in order to validate the analysis results, a new seal was designed and tested on a seal tester compared to the previous seal. In this test, the seal maximum interface temperature that reflects the position of maximum contact pressure can be obtained by using three high precision thermocouples. Both the experiment results and the numerical analyses proved that the maximum contact pressure and leakage rate of the improved seal have been reduced compared to the previous.