Double Stage Research Articles

Efficacy of commercial nasal bridle use in reducing feeding tube dislodgements in pediatric patients following double stage laryngotracheoplasty

IntroductionMaintaining placement of the nasogastric feeding tube (NGT) is imperative in the double stage laryngotracheoplasty (dsLTP) patient because of concerns for adequate nutrition and hydration in the postoperative period. Additionally, multiple reinsertions due to displacement potentiate surgical morbidities. The purpose of this study was to compare NGT dislodgment rates in children with and without a commercial nasal bridle following a dsLTP surgical procedure and to determine if the use of a commercial nasal bridle decreases accidental tube dislodgements. MethodsMedical records of pediatric patients with NGT insertion for dsLTP between Jan 1, 2012 and June 15, 2018 were reviewed for nasal bridle use, demographics, feeding tube and bridle complications, x-rays to check NGT placement, length of stay (LOS), length of bridle use and accidental feeding tube dislodgements. ResultsA total of 67 patients (34 unbridled and 33 bridled) received an NGT after dsLTP. No differences in demographics were noted, except the bridled group was older (median age 6.5 [IQR: 3.7, 14.3] than the unbridled group (median age 3.2 [IQR: 2.2, 6.8], p = 0.05). There were 24 episodes of NGT dislodgement in 16 patients in the unbridled group and zero displacements in the bridled patients resulting in an incidence of 9.4 [95%CI: 6.0, 14.0] and 0.0 [95%CI: 0.0, 1.9] pullouts per 100 days for unbridled versus bridled patients, respectively. Those with displacement had significantly more x-rays to check placement (p = 0.0004) and LOS was longer (p = 0.06) with a mean (SD) of 10.9 (7.0) vs. no displacement 7.0 (3.6) days. Of those bridled, 67% were discharged with a bridle and 86% returned with the NGT and bridle in place (mean bridle placement of *** ± days) at the time of stent removal. No feeding tube or bridle complications were reported for either group. ConclusionThe commercial nasal bridle significantly reduced NGT displacements without complication in the examined pediatric sample s/p dsLTP. Bridle use was associated with decreased radiology exposure and LOS and was successfully used in the outpatient setting.

Numerical investigation on parameter influence in double-stage Vuilleumier type pulse tube cryocooler (VM-DPTC)

The double stage Vuilleumier type pulse tube cryocooler (VM-DPTC) is a modified 4 K-class pulse tube cryocooler form the Vuilleumier hybrid pulse tube cryocooler in TIPC, CAS. Besides its compact size and low-frequency working pattern eliminating the moving parts in cryogenic temperature (<77 K) will improve the working stability and reduce the inherited losses. To design a proper double stage pulse tube cryocooler under a certain thermal compressor to work below 5 K, a numerical model based on Sage 10 software was established and the geometry of phase shifter was optimized firstly. Then the influence of working parameters on no-load temperature, cooling power and the heat rejection of the thermal compressor were studied.

Performance analysis of a new double stage compressor helium liquefaction cycle

Large scale helium liquefaction/refrigeration plant plays a vital role in advanced large equipment such as fusion reactors and accelerators. A new helium liquefaction cycle with double stage compressor is proposed in this paper, which is different from the Collins cycle. The helium gas from the compressor is divided into two parts. The medium-pressure helium gas as one part flows through the heat exchangers and is liquefied by throttling in the valve. The other part, high-pressure helium gas flows into the turbine for adiabatic expansion with decrease of its temperature and pressure. Both high-temperature helium gas streams become low-temperature and low-pressure. In this paper, the new cycle is parametrically analysed to demonstrate the effect of each parameter on the performance of the cycle. The results of the liquefaction capacity are obtained in different working conditions. Exergy analysis, which is an effective way to analyse thermodynamic cycles, is performed on the liquefaction process and the result is significant for the appropriate design of helium liquefaction system.

Two Stage Text Encryption Using a Private Table of the Sumerian System

The massive use of the internet in our contemporary life relates to the increase of the exchange of information through the Internet networks. Due to the importance of the information and to preserve its confidentiality, it protects using theories as well as strategies from attack or abuse. The aim of the research is to design an algorithm to encrypt text symbols to understandable symbols using private table that contains representation of ASCII of English characters with their suitable Sumerian system numbers. Each letter of the text is converted to ASCII code then encoded as an image using the private table, After that these images are combined together and saved as a new image as a Sumerian image. This image is encrypted first with unintelligible key image that is generated from three external key’s (kr, kg, and kb) to be the first stage encryption image. Then the second stage image generates from encrypting the first stage image with another input key image using XOR function which increases image security. The proposed algorithm gives double stage encryption and high degree of security level because of using Sumerian system and using different keys and security methods. Through using the histograms on all tested images, the result image demonstrate the efficiency of the system visually.

Thermal analysis and cryogenics of the Baby-IAXO magnet

Baby-IAXO is a new helioscope, a demonstration version of the proposed full-size IAXO, the International Axions Observatory. It is currently under design and once installed it will search via the Primakoff effect for axions or axion-like particles (ALPs) originating in the Sun. Axions can transform into photons in the presence of a significant magnetic field, and then be detected. The superconducting magnet for Baby-IAXO comprises two 10 m long racetrack coils, spaced by 0.8 m, operated in a quadrupole configuration and generating an average magnetic field of 2.1 T in the two 700 mm diameter free bores for axion-to-photons decay positioned in between the coils. Cool down and operational cryogenic requirements are handled by a combination of single and double stage cryocoolers. For the cool down of the 18.5 t cold mass within 22 days and for current leads cooling, the use of powerful single stage cryocoolers is of paramount importance. The cooling power is distributed across the cold mass and thermal shield using helium gas flow enforced by cryocirculators. The design of the 10 kA conduction cooled current leads is presented as well, since at 70 K these represent the dominant heat load. The cryogenic system allows for a constant heat load of 1.2 kW at the first stage and 8.5 W at the 4.2 K cold mass. Alternatively, the magnet may be operated in persistent mode, thereby reducing the heat load and the number of cryocoolers. It requires a more complex cooling circuit, implementation of a 10 kA persistent mode switch, and a delicate balance of energizing and operational heat loads.

Mathematical Simulation of Fourth Generation Refrigerant R1243zf in Single Stage and Double Stage Vapour Compression Refrigeration System

In this paper a new fourth generation, environment friendly refrigerant R1243zf has been used in performance analysis between single stage and double stage vapour compression refrigeration system working between the same minimum and maximum pressure limits. The analysis has been done by mathematical simulation in Engineering Equation Solve (EES 10.439D, 2019). Results show that in low temperature cooling applications, a single stage vapour compression system does not perform well and a cascade system is the best optimum solution. In the given pressure limit, with the use of double stage vapour compression system, the increase in COP is 14% and decrease in compression work is 11.49%. The effects of evaporator temperature and condenser temperature have been seen on COP for both the systems and results show that with decrease in evaporator temperature, COP is decreasing, where as with decrease in condenser temperature COP is increasing.

Influence of feeding position and post-combustion air arrangement on NOx emission from circulating fluidized bed combustion with post-combustion

To explore the influences of different feeding position and post-combustion air (PCA) arrangement on combustion and original NOx emission characteristics of Shenmu semi-coke, the experiments were carried out on a new circulating fluidized bed (CFB) test platform, which was composed of a CFB and a post-combustion chamber (PCC). The experimental results showed that the feeding position of loop seal could effectively reduce original NOx emission and CO emission concentration in comparison to the conventional coal feeding position of furnace. The NOx emission concentration was 60.3 mg/m3 with single stage PCA. As the grading number of PCA increased, NOx emission can be gradually reduced, eventually falling to 49.6 mg/m3 with triple stages PCA. However, for CO emission, the double stages PCA were able to minimize CO emission. In addition to grading number of PCA, an appropriate injection position of PCA was also helpful for CO burnout. For double stages PCA, the two PCA nozzles should be arranged in the middle of the PCC. According to the above research results, the best feeding position and PCA distribution mode to achieve ultra-low original NOx emission (<50 mg/m3) were obtained.

Reduction of Peak Average Power Ratio for FBMC Waveform with P-PTS Technique

Background: In this work, Peak Average Power Ratio (PAPR) reduction is achieved in Filter Bank Multi-Carrier (FBMC) by using a Pretreated Partial Transmit Sequence (P-PTS) technique. High PAPR is seen as unitary of the major problems in FBMC. Aim: The proposed work present a double stage optimization technique termed P-PTS. Methods: In the first step, several overlying signals cooperative optimization method that the phase angle sequences of current signal is intended and improved according to preceding overlapped signals. An efficient PTS scheme for PAPR reduction is put through in the second form. Results: The suggested technique is carried out by changing the value of U and V to analyze the BER and PAPR performance of the system. It is likewise noted that increasing the value of V can significantly lessen the peak power. Conclusion: Simulation results reveal that the performance of the proposed P-PTS technique is better than conventional PAPR reduction techniques with simple computations and the design complication can be traded off further compliantly with PAPR diminution.

AFLL-Based Control Technique for Grid Interfaced Three Phase PV System

This work deals with an advanced frequency locked loop (AFLL)-based control algorithm for a three phase double stage grid interfaced solar photovoltaic (PV) system. This AFLL-based algorithm extracts fundamental component of the load current and eliminates harmonics, performs grid currents balancing, improves the system performance during distorted grid conditions, and isolates the system during the occurrence of a grid fault. In a long radial network, the far away ends have the problem of voltage quality but this controller maintains the grid power quality by providing required reactive and active powers to the grid. The voltage source converter (VSC) of the PV system supplies the PV energy to the grid even under the worst situations of dc offset, solar insolation variation, load unbalancing, grid faults, voltage distortion, voltage unbalance, and voltage swell/sag. The VSC switching losses are reduced using an adaptive dc link voltage. This system is modeled and simulated in MATLAB and tests are conducted on a prototype built in the research laboratory under various odd states as stated earlier. Even during the disturbance, the harmonics level in the grid currents is seen in limits as suggested in the IEEE Standard-519.

Experimental characterization of ID-Hall, a double stage Hall thruster with an inductive ionization stage

We present experimental results on the characterization of ID-Hall, a double stage Hall thruster with an inductively coupled magnetized ionization stage. This first experimental prototype of ID-Hall operates in a low power regime, typically below 400 W. The purpose of this work is not only to study the properties of ID-Hall and provide directions for optimization but also, and more generally, to study the relevance of the double stage concept with respect to important physical issues such as current oscillations and anomalous electron transport. We present experimental measurements of the current–voltage characteristics, extracted ion beam current (Faraday cup measurements), and ion energy and angular distribution functions (RPA measurements) in single and double stage regimes of operation, as a function of DC voltage and RF power. The results demonstrate that ions can be extracted from the inductive RF ionization stage even under conditions where the applied DC voltage is not sufficient to ionize the gas flow, i.e., ID-Hall can indeed operate in a double stage regime. At intermediate voltages, the overshoot observed in the current–voltage characteristics of single stage thrusters disappears in double stage operation, indicating a decrease in anomalous electron transport. Time-resolved and time-averaged ion energy distribution measurements show a coupling between ion energy, breathing mode oscillations, and the magnetic configuration of ID-Hall.

Conversion of coal fly ash into nanozeolite Na-X by applying ultrasound assisted hydrothermal and fusion-hydrothermal alkaline activation

This research is emphasized on the synthesis of micro-mesoporous nanozeolite Na-X from coal fly ash wastes (CFA) by ultrasound assisted hydrothermal and double stage fusion-hydrothermal alkaline activation. The products from CFA zeolitization were studied with respect to their morphology by scanning electron microscopy (SEM), chemical and phase composition by energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD), respectively. Their thermal properties were investigated by thermogravimetry (TG), derivative thermogravimetry (DTG) and differential scanning calorimetry (DSC) and surface characteristics by nitrogen adsorption. The effects of the ultrasound agitation and additives on the zeolitization process were studied. Sonicated CFA Na-X zeolites possess nanocrystalline morphology and mixed micro-mesoporous structures with higher external specific surface area as compared to microcrystalline zeolite Na-X prepared by magnetic stirring. CFA nanozeolites of Na-X type are expected to behave excellent adsorption potential and catalytic activity due to the enlarged surface and fine morphology with uniformly distributed particles of iron oxides transferred from the raw material.

Sustainable Solvent Extraction Process for Fe Analysis in Radioactive Samples Based on Microfluidic Tools

ABSTRACTThe decommissioning and dismantling of nuclear plants and the subsequent management of the wastes require a large number of radiochemical analyses in the timeline of the operations. Validated analytical methods for radionuclides measurements are employed to ensure reliable sample characterizations. The radioactivity of the samples, which induces handling and shipment constraints, and the use of harmful chemical reactants in some analytical procedures, are among the motivations to use miniaturized techniques that would considerably lower the amounts of samples and chemicals. Moreover the decrease of the analytical time is a major concern considering the increasing demand for radiochemical analyses. The purpose of this work is to develop a microsystem-based protocol for the recovery of 55Fe from samples. Analytical solvent extraction protocols adapted to co-flow glass microsystems, were developed and tested on iron extraction into ethyl acetate. A first extraction protocol consists of the partitioning of the Fe(cupferrate)3 chelate, from the aqueous phase to the organic phase. A second extraction protocol is based on the reactive transfer of iron using the cupferron in the organic phase. The two protocols were tested on a single Y-junction and a double stage Y-junction glass microsystems. After optimization of the liquid flow rates, the iron extraction was achieved within about 2 s or less. While the best extraction yield of (60.3 ± 4.9) % was obtained with the former protocol in the double stage Y-junction, higher values of (83.1 ± 5.2) % and (81.7 ± 2.0) % were obtained with the single and double stage microsystems, respectively, with the second protocol. These last results compare well with the yield of (93.0 ± 2.3) % measured in batch and could even be optimized by using slightly longer microchannels. Such microsystem-based extractions will be further applied to the analysis of 55Fe by liquid scintillation.

The effect of boundary or interface on stress-induced martensitic transformation in a Fe-Ni alloy

The boundary effect on mechanical stability of metastable austenite (γ) in the Fe-Ni steels is characterized using a combination of nanoindentation and transmission electron microscopy (TEM). When load (P) - penetration depth (h) is converted to a P/h versus h plot in a nanoindentation-induced loading curve, the result of metastable γ exhibits double stages; martensitic transformation in stage I, and subsequent plastic deformation with dislocation glide in the transformed martensite (α') in stage II. The two quantitative parameters associated with transformation behavior can be obtained from the P/h versus h plot: (i) the slope a of the plot in stage I, which proportionally increases as the nanohardness and corresponds to resistance to martensitic transformation, and (ii) the critical load Pt that corresponds to the transition from stage I to II, namely the end of martensitic transformation. Both slope a in stage I and Pt become lower for the γ/α' interface, γ/γ grain boundary, and γ grain interior, in turn. Furthermore, the plots of slope a in stage I and Pt as a function of distance from the γ/γ grain boundary DGB show that both parameters decrease with increasing DGB. TEM observations of microstructures in the vicinity of the γ/γ grain boundary show that transformed α' is only observed in the indented γ grain and no transformation occurs in the adjacent γ grain. These results indicate that martensitic transformation is significantly retarded by boundaries, and retardation presumably depends on the character of boundaries due to a constraint against volume expansion of the transformation from γ to α'.

Opposed type double stage cell for Mbar pressure experiment with large sample volume

ABSTRACTA new opposed type double-stage large volume cell has been developed to compress large volume samples to more than 100 GPa (Mbar) pressure. A pair of second-stage diamond anvils is introduced into the first-stage Paris–Edinburgh press. The double-stage large volume cell allows the generation of ultrahigh pressures using a large culet diameter of the second-stage diamond anvils (diameters of 0.5–1.2 mm). Pressure generation up to 131 GPa has been achieved by using the culet diameter of 0.5 mm. Sample volume of the double-stage large volume cell can be more than ∼100 times larger than that of conventional Mbar experiment using a diamond anvil cell. The double-stage large volume cell has a large opening in the horizontal plane for X-ray measurements, which is particularly suited for the multi-angle energy dispersive X-ray diffraction measurement, thus opening a new way of in situ structural determinations of amorphous materials at Mbar pressures.

Negative selection of human T cells recognizing a naturally-expressed tissue-restricted antigen in the human thymus

During T cell development in mice, thymic negative selection deletes cells with the potential to recognize and react to self-antigens. In human T cell-dependent autoimmune diseases such as Type 1 diabetes, multiple sclerosis, and rheumatoid arthritis, T cells reactive to autoantigens are thought to escape negative selection, traffic to the periphery and attack self-tissues. However, physiological thymic negative selection of autoreactive human T cells has not been previously studied. We now describe a human T-cell receptor-transgenic humanized mouse model that permits the study of autoreactive T-cell development in a human thymus. Our studies demonstrate that thymocytes expressing the autoreactive Clone 5 TCR, which recognizes insulin B:9–23 presented by HLA-DQ8, are efficiently negatively selected at the double and single positive stage in human immune systems derived from HLA-DQ8+ HSCs. In the absence of hematopoietic expression of the HLA restriction element, negative selection of Clone 5 is less efficient and restricted to the single positive stage. To our knowledge, these data provide the first demonstration of negative selection of human T cells recognizing a naturally-expressed tissue-restricted antigen. Intrathymic antigen presenting cells are required to delete less mature thymocytes, while presentation by medullary thymic epithelial cells may be sufficient to delete more mature single positive cells. These observations set the stage for investigation of putative defects in negative selection in human autoimmune diseases.

Effect of double cleavage stage versus sequential cleavage and blastocyst stage embryo transfer on clinical pregnancy rates

Objective: To compare clinical pregnancy rates following sequential day-3 and day-5 embryo transfer with double or sequential cleavage-stage transfers.Methods: This study enrolled 242 patients undergoing gonadotropin-releasing hormone antagonist protocol and fresh embryo transfer. Basal follicle stimulating hormone, luteinizing hormone, serum estradiol and anti-Müllerian hormone levels and controlled ovarian stimulation outcomes were noted. Of 242 women, 135 underwent double embryo transfer on day 2 or day 3 (the double group), 54 women underwent sequential embryo transfer on day 2 and day 3 (the D2/D3 group), and 53 underwent sequential embryo transfer on day 3 and day 5 (the D3/D5 group). Clinical pregnancy rates were compared among the groups.Results: Female age, body mass index, basal follicle stimulating hormone, luteinizing hormone and estradiol levels were similar among the groups (P>0.05). The D3/D5 group had a significantly higher number of metaphase II oocytes, fertilized oocytes and good quality embryos on day 3 compared with the double group and the D2/D3 group (P < 0.001). Clinical pregnancy rates in the double, D2/D3 and D3/D5 groups were 26.6% (36/135), 16.6% (9/54) and 37.7% (20/53), respectively. There was no significant difference in clinical pregnancy rates between the double group and the D2/D3 group (P =0.204) or the D3/D5 group (P =0.188). The D3/D5 group had significantly higher clinical pregnancy rates compared with the D2/D3 group (P =0.025).Conclusions: Sequential cleavage-stage transfer (D2/D3) or cleavage stage and blastocyst transfer (D3/D5) does not improve clinical pregnancy rates compared with double cleavage-stage embryo transfer. Although sequential transfer seems to be an effective option in certain patient populations, routine application of this technique might not be a suitable approach in an unselected population to improve assisted reproductive technology outcomes.

RNA editing enzyme ADAR1 is required for early T cell development.

The RNA editing enzyme ADAR1 has been shown to be an essential molecule for hematopoietic cell differentiation, embryonic development, and regulation of immune responses. Here, we present evidence in a T-cell-specific gene knockout mouse model that ADAR1 is required for early T cell development. Loss of ADAR1 led to cell death of the progenitors at the double negative stage and prevented T cell maturation in the thymus. Furthermore, ADAR1 deletion in pre-T cells preferentially affected TCRβ-expressing cells causing TCRβ positive cell depletion. Interruption of IFN signaling occurred in the premature T cells, indicating a role of IFN signaling in the survival of TCRβ-expressing cells regulated by ADAR1. This study demonstrated an essential role for the RNA editing enzyme ADAR1 as a potential regulator for T-cell fate determination during clonal selection, which, in turn, contributes to immunologic homeostasis.

Design and implementation of interleaved high gain DC-DC converter

DC-DC converters have played a vital role in solar power system. They reduce the problem of shadow effect on solar panels. Different converter topologies help to reduce the shadow effect. This paper has presented a topology for high voltage gain. This paper presents two topologies of DC-DC converter for high gain with fewer ripples on output side. Topology 1 is related to single stage amplification with various components, while topology 2 presents double stage amplification. The proposed topology 2 gives voltage gain of about 12% and the efficiency of this converter is about 85%. This converter has been designed for 34 V input and 407 V output. This topology has been also compared with two existing topologies with voltage gain, efficiency and voltage ripples. A 224 watt, 34 V input and 407 V output converter has been developed in this paper.

Numerical and Experimental Investigations on a Dimpled Savonius Vertical Axis Wind Turbine

This research deals with the design and fabrication of novel designs as a mean to harness wind energy using a ‘Savonius’ Turbine. It is generally employed to harvest the low to very low wind speed potentials. They can particularly be of high use in the regions where the wind speeds are not high enough for installing conventional horizontal axis wind turbines. The paper introduces a novel concept of testing a Savonius wind turbine with dimple structures on its blades and investigating its effect on the turbine’s efficiency. The study also deals with the experimental validation of the effect of using a converging ducted structure with a single stage and double stage configurations of Savonius wind turbine, apart from comparing the turbine’s performance with and without endplates. The results of the study proves that power coefficient increases with the addition of dimple structures on the blades and it can be further augmented by using a ducted structure with the Savonius turbine.

A Well-Organized Safeguarded Access on Key Propagation by Malleable Optimization in Blend With Double Permutation

With the rapid developments occurring in cloud computing and services, there has been a growing trend of using the cloud for large-scale data storage. This has led to a major security dispute on data handling. Thus, the process can be overcome by utilizing an efficient shielded access on a key propagation (ESAKP) technique along with an adaptive optimization algorithm for password generation and performing double permutation. The password generation is done by adaptive ant lion optimization (AALO) which tackles the problem of ineffiency. This build has stronger security which needs an efficient selection property by eliminating the worst fit in each iteration. The optimized password is utilized by an adaptive vignere cipher for efficient key generation in which adaptiveness is employed to prevent the dilemma of choosing the first letter of alphabet which in turn reduces the computation time and improves the security. Additionally, there is a need to encrypte the symmetric key asymmetrically with a Elliptic Curve-Diffie Hellman algorithm (EC-DH) with a double stage permutation which produces a scrambling form of data adding security to the data.