Sealed System Research Articles

A triphos-modified tungsten piano-stool complex for the homogeneous (conjugate) hydrogenation of ketones and esters

We disclose the synthesis, characterization, and catalytic application of a triphos-tagged, non-pincer-type tungsten complex. The pertinent W-based half-sandwich compound was used in the homogeneous hydrogenation of ketones and esters to afford the corresponding alcohols. Furthermore, the introduced base metal catalyst facilitated the conjugate reduction of enoates to yield the respective CC-bond-free esters. Most of the applied substrate ketones were convertible under very mild reaction conditions (room temperature, 5 bar H2) in the presence of t–BuONa. The exchange of the cation in the auxiliary base from Na+ to Li+ turned out to be crucial for the successful reduction of the carbonyl ester group. The deployed organometallic complex is readily weighable and can be handled on the laboratory bench outside a sealed glove box system.

DEVELOPMENT OF A DEVICE AND SOFTWARE COMPLEX FOR ACOUSTIC DIAGNOSTICS OF PROCESSES OCCURRING IN THE SUPERCRITICAL STATE OF A LIQUID AND MONITORING THE WORK OF A MAGNETIC DRIVE UNIT

There is a problem of studying the processes that occur during the transition of a liquid to a supercritical state and in the process of studying and conducting experiments. There is also a problem of controlling the operation of the electromagnetic device system. Since mechanical, electronic, and other control methods are complicated by the conditions (extremely high pressure, high temperature, location of a part that needs control inside a sealed metal system and is under radiation), an acoustic research method was chosen. As a result of the development, a device based on STM32F407VGT6, DP83848, MAX9814 was created that allows you to receive acoustic data and transmit them over considerable distances using an Ethernet network. Also, applications were developed that enable visualization, storage and processing of acoustic data: a TCP server for data exchange, an operator application that helps to visually control the operation of the magnetic drive and save acoustic data in CSV format, an application for visualization and processing of stored data using methods of statistical and spectral analysis.

Phase II/III trial of hyperimmune anti-COVID-19 intravenous immunoglobulin (C-IVIG) therapy in severe COVID-19 patients: study protocol for a randomized controlled trial

BackgroundCOVID-19 poses a global health challenge with more than 325 million cumulative cases and above 5 million cumulative deaths reported till January 17, 2022, by the World Health Organization. Several potential treatments to treat COVID-19 are under clinical trials including antivirals, steroids, immunomodulators, non-specific IVIG, monoclonal antibodies, and passive immunization through convalescent plasma.The need to produce anti-COVID-19 IVIG therapy must be continued, alongside the current treatment modalities, considering the virus is still mutating into variants of concern. In this context, as the present study will exploit pooled diversified convalescent plasma collected from recovered COVID-19 patients, the proposed hyperimmune Anti-COVID-19 intravenous immunoglobulin (C-IVIG) therapy would be able to counter new infectious COVID-19 variants by neutralizing the virus particles. After the successful outcome of the phase I/II clinical trial of C-IVIG, the current study aims to further evaluate the safety and efficacy of single low dose C-IVIG in severe COVID-19 patients for its phase II/III clinical trial.MethodsThis is a phase II/III, adaptive, multi-center, single-blinded, randomized controlled superiority trial of SARS-CoV-2 specific polyclonal IVIG (C-IVIG). Patients fulfilling the eligibility criteria will be block-randomized using a sealed envelope system to receive either 0.15 g/Kg C-IVIG with standard of care (SOC) or standard of care alone in 2:1 ratio. The patients will be followed-up for 28 days to assess the primary and secondary outcomes.DiscussionThis is a phase II/III clinical trial evaluating safety and efficacy of hyperimmune anti-COVID-19 intravenous immunoglobulin (C-IVIG) in severe COVID-19 patients. This study will provide clinical evidence to use C-IVIG as one of the first-line therapeutic options for severe COVID-19 patients.Trial registrationRegistered at clinicaltrial.gov with NCT number NCT04891172 on May 18, 2021.

A Novel Two-Chamber Setup for Containment Investigations with Special Focus on the Dustiness of Pharmaceutical Powders Depending on the Airflow.

In the present study, it was shown that a newly developed two-chamber setup (TCS) for containment investigations consisting of an emission and a detection chamber may serve to predict the dustiness of HPAPIs in a sealed system at different flow conditions. These flow conditions include the plain diffusive transport and the diffusive transport with the oppositely directed convective flow of airborne particles of the safe surrogate substance acetaminophen (ACAM). A linear correlation was found between an atomized amount of up to 400 mg of ACAM and the resulting dust emissions. The dust emission was reduced significantly by an oppositely directed convective flow. The results from the examinations, using either atomized ACAM or smoke for the determination of the evacuation time of the detection chamber, indicated that both methods are comparable. Furthermore, computational fluid dynamics (CFD) simulations were performed to determine the evacuation time. A time period of 9 min was sufficient for a reproducible evacuation and a reliable detection of most airborne ACAM particles within the detection chamber. CFD simulations were also carried out to simulate the air velocity resulting from various pressure differences and to visualize the flow of the airborne particles within the detection chamber.

Design, Construction and Characterization of Sealed Tube Medium Power CO2 Laser System

A low-cost medium-power carbon dioxide (CO2) laser system is designed, constructed, and characterized to produce coherent, monochromatic laser radiation in the infrared region. The laser cavity is simulated and designed by using ZEMAX optic studio. A switch-mode high-tension pump source is designed and constructed using a flyback transformer and simulated using NI Multisim to study the voltage behavior at different node points. A prototype cooling system/chiller is designed and built using thermo-electric coolers (TEC) to remove the excess heat produced during laser action. Various parameters, such as pumping mechanism, chiller stability, efficiency, output power, and current at different applied voltages, are studied. The chiller efficiency at different output powers of the laser is analyzed, which clearly shows that the chiller’s cooling rate is good enough to compensate for the heat generated by the laser system. The center wavelength of the carbon dioxide laser is 10.6 μm with an FWHM of 1.2 nm simulated in the ZEMAX optic studio. The output beam penetration through salt rock (NaCl), wood, and acrylic sheet (PMMA) at various output powers is analyzed to measure the penetration depth rate of the CO2 laser.

Observation of External Wounding on Green Ash (Fraxinus pennsylvanica Marshall) Trees Associated with Tree Injection Systems

Field observations of external wounds associated with two common tree injection methods compared open (plug-less) and sealed (plug) systems in green ash (Fraxinus pennsylvanica Marshall) trees. A wound from any cause within 1.37 m above the ground was common with 28.8% of all trees. The open system had statistically fewer (p < 0.001) trees with at least one wound (11.6% of trees) than the sealed system (47.4% of trees). The open system had fewer (p < 0.001) wounds (0.17, 0.04 SE) per tree and a smaller (p < 0.001) total wound area (25.5 cm2, 8.7 SE) per tree, compared to the sealed system wounds (1.14, 0.13 SE) per tree and the total wound area (99.7 cm2, 16.2 SE) per tree. The incidence of a tree with a wound(s) within 1.37 m above the ground was 7.2 times more likely with trees treated though the sealed system. Wounds in the sealed system were observed to appear to have a high rate of improper application of plugs, which was associated in 77% of the cases to explain the wounds. Implications of study results are further provided to best protect ash trees, while at the same time reducing the incidence external wounding on ash trees.

Simplification of the potassium ferrioxalate actinometer through carbon dioxide monitoring

Chemical actinometry can be used to determine photons absorbed for a photochemical reaction, which is required to calculate the quantum yield. A photochemical reaction with a known quantum yield can be used as a relative standard for the determination of an unknown quantum yield for a light-driven reaction. Herein, we have developed a simplified approach to using the popular potassium ferrioxalate actinometer. Traditionally, the photoreduction of Fe(III) to Fe(II) is monitored by following the absorbance of Fe(II) by reacting aliquots of the actinometry solution with 9,10-phenanthroline to form a red colored complex. The multiple steps for this method make it tedious and vulnerable to errors, especially inadvertent light exposure. In lieu of spectroscopic measurements of the Fe(II) concentration, the production of CO2 was measured to determine the number of photons absorbed over time. CO2 production was measured in two different ways: by the pressure increase in a sealed system and the volume change by trapping the CO2. Both methods were considerably less laborious and showed agreeable results compared with the traditional spectroscopic method.

Dynamic Characteristics of Metal Seals in Roller Cone Bits

During the drilling process, the sealing performance of the roller cone bits is severely challenged by the complex downhole environment and frequent vibrations. In this paper, a comprehensive thermal–fluid–solid–dynamic multi-field coupling numerical model of new-generation single energizer metal seals (SEMS2) is developed. The instantaneous sealing performance of SEMS2 is studied under periodic vibration, instantaneous shock, and random vibration. Time-domain and frequency-domain changes in the sealing parameters with environmental pressures and rotational speeds under different vibrations are analyzed and compared. The results show that the liquid film distribution and lubrication state on the sealing end faces change constantly as the drill bit vibrates, which in turn affects the sealing performance of the SEMS2. The instantaneous leak rate fluctuates alternately between positive and negative under the three kinds of vibrations, aggravating the tendency of lubricant oil leakage and drilling mud invasion. With increasing environmental pressure and rotational speed, the fluctuation amplitudes of the maximum temperature increase, leakage rate, and friction torque under random vibration and instantaneous shock are significantly larger than those under periodic vibration. Our model and results have important theoretical significance for improving the design system of metal seals for drill bits.

In situ behaviour of an instrumented ring subjected to active eccentric tail seal passage

With common TBM configurations, the last assembled ring is contemporarily loaded by the thrust jacks and a generally off-centered tail seal system. In active eccentric scenarios of tail seal passage, significant tail-ring eccentricities can be locked by the opposing action of sealing pressures and thrust jacks (Gil Lorenzo, 2022). In this paper, the in situ response of the CAM3 instrumented ring in the Crossrail’s Thames tunnel (CTT) during active eccentric tail seal passage is examined in detail. The field data comprises selected TBM data, the distributed strain measurements of a Brillouin Optical Time Domain Reflectometer (BOTDR), plus the output quantities of vibrating wire strain gauges (VWSGs) and biaxial micro-electro-mechanical system (MEMS) tiltmeters. The field data was completed with relevant analytical models (Gil Lorenzo, 2019a; 2022) and compared with the outputs of the finite element (FE) model conducted alongside (Gil Lorenzo, 2021a; 2021b), showing good agreement with the FE-computed deformational quantities. It was found that the eccentric tail seal passage was the main cause of the high and uneven lining pressures detected at the early stages of tunnelling. The active eccentric tail seal passage, with upwards seal pressure gradients and downwards transverse jack forces, triggered the ring deformations in the unsupported tunnel, which became essentially irrecoverable. The radial rotations of the outer springline segment were largely affected by the interfacial quality between ram shoe and segment first, and between segments once the next ring was erected. The high sealing pressure gradients yielded a 0.12% ring distortion ratio increment already close to recommended construction limits. The top half of the non-bedded ring behaved as an arch-like structure with the crown segment supported by the neighbouring rings. At the lower segments, the hoop curvatures were the result of the ring ovalisation whereas, at the upper segments, the hoop curvatures were primarily induced by the inward radial jack forces. The outer springline segment worked under considerable torsion in the first TBM cycle. Initial in-plane angularities in longitudinal joints with contact at the rear can be accentuated by the advance of the sealing pressures from rear to front and become irreversible. Longitudinal cracking is more likely in the first TBM cycle while the ring is radially loaded at the rear only. In addition, a field example of concrete cracking in a segment with a defective packer support after ring erection is provided.

How Wetting Properties Influence the Wear of Radial Lip Sealing Systems

AbstractIncreased wear on radial lip seal systems is observed when sealing modern lubricants, such as polyglycols and esters. This can impair the function of the sealing system and ultimately lead to leakage. This work, carried out within the AiF research project “Welleneinlauf” (wear of counter faces) [1], shows methods to identify and predict excessive wear of radial lip sealing systems based on their wetting properties and pumping rate. The knowledge gained will support users by providing faster and more cost‐effective testing methods early in the design process, thus enables a significant increase in the service life of radial lip sealing systems.

Modeling, Nonlinear Dynamics, and Bifurcation Analysis of the Rotor–Seal System Using a Subharmonic Sampling Strategy

Abstract Rotors are used to transfer power from one component to the other component in various rotor dynamics applications like steam turbines, aerospace systems, and power generators. In certain applications, the seal is an important and inevitable component of the rotor dynamic system. The linear dynamics of the rotor is converted into nonlinear in the presence of a seal. The presence of a seal, can sometimes, trigger self-excited vibrations in rotor/seal systems. Generally, the amplitude of vibration during such vibrations is several times higher than normal steady-state vibrations. Due to this, other faults like transverse crack initialization and rotor/stator rub get accelerated. The rotating machinery working at high spinning speeds is more prone to this type of instability. Hence, the stability limits of the rotor/seal system must be known in advance for the safe operation of the rotating machinery. The dynamic behavior of such a system qualitatively varies corresponding to different system parameters of the rotating machinery. Cumbersome analytical methods have been used in the past for bifurcation analysis of rotor/seal systems. In the present work, system bifurcations have been investigated using a subharmonic sampling rate strategy. The proposed method is easy to implement and numerically efficient. The effect of various parameters like the spinning speed of the rotor, unstable mass, and seal clearance is investigated for the stability of the rotor/seal system. Experimental testing is done to verify the simulation results.

Air refiner breather/disinfection unit (water seal system) is a clinically useful and cost-effective device for COVID-19 patients

Coronavirus disease-2019 (COVID- 19) pandemic declared by the World Health Organization (WHO) on 11th March 2020, caused by the SARS-CoV-2 virus is at an exponentially rising state across the globe. Bangladesh is also facing the toll of this highly transmissible zoonotic disease with community transmission (at a different rate) across the country. This is a new coronavirus, still evolving, and has put the scientific authority in a puzzle. Prevention of transmission and contamination (especially via air-borne route) is the main aim here. Moreover, prevention of contamination of Intensive care unit (ICU) and operation theater (OT) equipment and environment is an optimal target. Gas and smoke evacuation during laparoscopy and pneumoperitoneum is also a big question. Cost-effectiveness is another important aspect. Different processes, techniques, devices, etc. have been tried so far. Here, a new device is going to be reported in this paper in such relation. Mediscope 2022;9(2): 81-84

Investigating Al-Si base abradable material removal mechanism with axial movement in labyrinth seal system

Modern aeroengines employ labyrinth seal systems to seal the clearance between the blade tip and surrounding engine casing. Understanding of the wear mechanism between labyrinth fins and abradable coatings on the casing is necessary to help the aeroengine achieve higher efficiency. In this study, multiple tests with different types of fin geometries are conducted on a high-speed test rig with a fin tip speed of 100m/s. Two motorized stages are used to simulate the axial movement of the labyrinth fin in an aeroengine. The wear mechanism is investigated over a range of incursion rates from 2μm/pass to 10μm/pass, with in-situ force and temperature measurements along with high-speed imaging recorded on the side in each case. The surface examination of the wear track is also employed by using microscopy post-test. The main abradable material removal mechanism is extruding from the fin side. Also, adhesion of abradable material to the fin is found in each test and the adhesion amount is affected by both fin geometry and incursion rate.

Comparative Study of Bilateral Versus Unilateral Strabismus Surgery in the Management of Lateral Incomitance in Intermittent Exotropia.

To evaluate and compare bilateral asymmetric lateral rectus recession versus unilateral resection-recession surgery in the management of lateral incomitance in intermittent exotropia. A prospective randomized interventional comparative study was conducted consisting of 80 patients with intermittent exotropia (older than 7 years) having significant lateral incomitance. They were equally divided into two groups by a sealed envelope system. The bilateral group underwent bilateral asymmetric lateral rectus recession and the unilateral group underwent unilateral lateral rectus recession and medial rectus resection based on post-patch deviation. Parameters assessed were change in horizontal deviation, change in lateral incomitance, binocularity, motility limitation, and complications, if any. Surgical outcome was considered successful if the primary deviation was within ±8 prism diopters (PD) and lateral incomitance was less than 5 PD. The mean lateral incomitance preoperatively and postoperatively was 8.3 ± 1.6 and 2.8 ± 2.4 PD in the bilateral group and 8.9 ± 1.4 and 3.7 ± 2.5 PD in the unilateral group, respectively. There was no statistically significant difference in the postoperative lateral incomitance between the two groups (P = .25), but a statistically significant difference was observed between preoperative and postoperative lateral incomitance in each group (P < .0001). Both procedures are equally efficacious in achieving acceptable ocular alignment and improving significant lateral incomitance in patients with intermittent exotropia with deviations between 15 and 35 PD without causing significant motility limitation. [J Pediatr Ophthalmol Strabismus. 2023;60(4):277-281.].

Influence of the operation strategy on the energy consumption of an autonomous sensor node

Abstract. Motivated by the application of industry 4.0 and Internet of Things (IoT) technologies, the development of cyber physical systems (CPS) is gaining momentum. As CPS require multiple measurement technologies to drive the intended function, e.g., condition monitoring and in situ measurement, the integration of measurement systems into industrial processes or individual products becomes a critical activity within the development process. Development methods like the V-Model support developers with methodological guidelines, but the related methods and models do not provide sufficient information regarding the energy supply of embedded systems. If the measurement system, consisting of sensor, calculation and communication unit is integrated inside an either sealed or moveable system, e.g., in a gearbox, ensuring a reliable communication and energy supply is a challenging task. This contribution therefore focuses on the energy supply, in particular the electric power consumption of autarchic measurement systems, referred to as sensor nodes. Based on a literature review of existing physical principles determining the energy consumption of semiconductors, a simple estimation model is derived. Estimation models in the current literature mainly focus on the effects of source code or software in general without analyzing a possible impact of operation strategies, such as generic data processing logics in practical applications. The model presented in this contribution is therefore used to identify the energy consumption of sensor nodes influenced by ambient and operating conditions of sensor nodes. Strategies are examined experimentally using an exemplary sensor node, a climatic chamber and a sensor-integrated gearbox as the system to be observed. An analysis of the conducted experiments leads to a more precise model, which is evaluated regarding its significance for predicting the energy consumption and the underlying simplifications. Finally, general relations influencing the energy consumption are presented and necessary research suggested.

To compare effects of pretreatment with two doses of dexmedetomidine on etomidate induced myoclonus and attenuation of stress response at intubation

Etomidate’s haemodynamic stability is due to its unique lack of effect on the sympathetic nervous system and on baroreceptor function. Even in cardiac patients an induction dose of etomidate results in very stable haemodynamics. Etomidate also has minimal effects on respiratory system as compared to other induction agents. Since it causes minimal histamine release, this gives an advantage in patients with reactive airway disease, making it less likely that they will have bronchospasm. However, pain on injection and myoclonus are two most common side effects of this drug. Pain on injection has disappeared after the new fat emulsion of etomidate, but the new solvent has not reduced the incidence of myoclonus.1): To compare the effects of pretreatment with two doses of Dexmedetomidine on the incidence of Etomidate induced myoclonus using numerical based grading; 2): To compare the effects of pretreatment with two doses of Dexmedetomidine on attenuation of stress response at laryngoscopy and intubation after induction with Etomidate.Study area: The proposed study was carried out in the Department of Anesthesiology and Intensive care at a tertiary care teaching hospital, after seeking clearance from the college ethical committee and obtaining written informed consent from patient. Study design: Prospective Interventional Randomized Comparative Study Study period: 1 year It was a prospective and interventional randomized comparative study where 180 patients with age group 18-65 years, of either sex,ASA grade I &amp; II, BMI, undergoing elective surgical procedures under general anaesthesia with endotracheal intubation were included in the study. They were divided into three groups where patients were randomly allocated into one of the three groups using Block Randomization with sealed envelope system. In Group 2 and 3, 78.3% and 76.6% patients did not have myoclonus during induction with etomidate. Stress response to intubation was suppressed by dexmedetomidine. Based on the observations of our study, we conclude that pretreatment with 0.5µg/kg and1µg/kg Dexmedetomidine significantly reduce etomidate induced myoclonus and stress response at intubation. However, dexmedetomidine in dose of 0.5µg/kg is associated with fewer side effects of bradycardia and hypotension.

Cryogenic and hermetically sealed packaging of photonic chips for optomechanics.

We demonstrate a hermetically sealed packaging system for integrated photonic devices at cryogenic temperatures with plug-and-play functionality. This approach provides the ability to encapsulate a controlled amount of gas into the optical package allowing helium to be used as a heat-exchange gas to thermalize photonic devices, or condensed into a superfluid covering the device. This packaging system was tested using a silicon-on-insulator slot waveguide resonator which fills with superfluid 4He below the transition temperature. To optimize the fiber-to-chip optical integration 690 tests were performed by thermally cycling optical fibers bonded to various common photonic chip substrates (silicon, silicon oxide and HSQ) with a range of glues (NOA 61, NOA 68, NOA 88, NOA 86H and superglue). This showed that NOA 86H (a UV curing optical adhesive with a latent heat catalyst) provided the best performance under cryogenic conditions for all the substrates tested. The technique is relevant to superfluid optomechanics experiments, as well as quantum photonics and quantum optomechanics applications.

Design and Development of Solar Powered 360degree Automatic Air Cooler

Abstract: Evaporative coolers lower the temperature of air using the principle of evaporative cooling, unlike typical air conditioning systems which use vapor-compression refrigeration or absorption refrigerator. Evaporative cooling is the conversion of liquid water into vapor using the thermal energy in the air, resulting in a lower air temperature. The energy needed to evaporate the water is taken from the air in the form of sensible heat, which affects the temperature of the air, and converted into latent heat, the energy present in the water vapor component of the air, whilst the air remains at a constant enthalpy value. Vapor-compression refrigeration uses evaporative cooling, but the evaporated vapor is within a sealed system, and is then compressed ready to evaporate again, using energy to do so. Simple evaporative coolers water is evaporated into the environment, and not recovered. In an interior space cooling unit, the evaporated water is introduced into the space along with the now-cooled air; in an evaporative tower the evaporated water is carried off in the airflow exhaust. To Develop the Energy efficient, environment friendly direct evaporative air conditioning system having low operating cost suitable for hot and dry regions To Manufacture advanced 360-degree Rotating air cooler which rotates and provide air cooling in all directions. It can be used for domestic as well as Industrial applications. The temperature of dry air can be dropped significantly through the phase transition of liquid water to water vapor (evaporation). This can cool air using much less energy than refrigeration. In extremely dry climates, evaporative cooling of air has the added benefit of conditioning the air with more moisture for the comfort of building occupants

Numerical Model of Mixed Lubrication and Experimental Study of Reciprocating Seal Based on Inverse Lubrication Theory

Based on the sealing mechanism of the reciprocating seal, the inverse-hydrodynamic-lubrication (IHL) method was adopted in this study to solve the Reynolds equation, and a multi-field coupled reciprocating seal mixed lubrication numerical model was established. Considering seals used for aircraft actuators as an example, we obtained sealing performance parameters such as leakage and friction at different oil pressures, reciprocating speeds, and temperatures. According to the actual situation, the influence of different working condition parameters on the sealing performance of the reciprocating seal system were analyzed. A reciprocating seal test bench was designed and built, and the friction data for the reciprocating seal system under different working conditions were experimentally obtained. Through a comparative analysis of experimental data and theoretical numerical results, the numerical model and calculation results for reciprocating seal mixed lubrication were verified.

Evaluation of the Sustainability of Phoenicultural and Market Gardening Production Systems of the Development in the Ouargla Region (Southern Algeria)

The aim of our work is to study the sustainability of seal and market gardening production systems. This study was carried out in two study areas N'goussa and Hassi Ben Abdellah in the region of Ouargla (Algeria), through 75 surveys in different farms where we elaborated a typology of evolution in order to know the determining elements of the trajectories. The Ouargla region's Farm Sustainability Indicator (IDEA) is important. The assessment of agro-ecological, socio-territorial and economic indicators indicates that the agro-ecological indicator is the most represented by (the indicator of fertilizer and agricultural practices) by 46 out of 100. The work was followed by statistical analyses (using Excel stat) to study sustainability constraints. The results show that the polyculture system (date palm, market gardening, etc.) is the most dynamic in terms of cultivation practices. The market gardening production system is economically profitable in the two study areas due to the evolution of market gardening under shelter. The stability of the seal farming system and its uniqueness indicate that it shows the most signs of sustainability.