Zeitschriftenartikel: „Viscous synergy“

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Ting, Tiew Wei, Yew Mun Hung und Ningqun Guo. „Field-synergy analysis of viscous dissipative nanofluid flow in microchannels“. International Journal of Heat and Mass Transfer 73 (Juni 2014): 483–91. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2014.02.041.

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Herráez, J. V., und R. Belda. „Viscous Synergy of Pure Monoalcohol Mixtures in Water and Its Relation to Concentration“. Journal of Solution Chemistry 33, Nr. 2 (Februar 2004): 117–29. http://dx.doi.org/10.1023/b:josl.0000030279.67143.ac.

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Yan, Yajing, Chongfang Song, Wuxuan Pan, Jie Wang und Yifan Bai. „Analysis of Resistance Characteristics and Research into Resistance Reduction of a Tee Based on Field Synergy“. Buildings 14, Nr. 5 (01.05.2024): 1271. http://dx.doi.org/10.3390/buildings14051271.

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The resistance loss and energy consumption when fluid flows through a tee in an HVAC system are severe. To improve energy efficiency and reduce carbon emissions, a novel tee with a U-shaped deflector is proposed, supported by experiments and numerical simulations. The resistance reduction mechanism of the U-shaped deflector was analyzed according to the viscous dissipation principle and the field synergy principle. The resistance reduction of the novel tee with different deflector angles and a traditional tee were compared. The results show that the resistance loss of the tee was mainly due to the flow separation and deformation of the fluid in the main branch. The relationship between the local resistance coefficient and the diameter ratio of the main-branch pipe was exponential, and the relationship between the local resistance coefficient and the diameter ratio of the main straight pipe was linear. The total resistance loss reduction rate of the tee with the addition of a 26° deflector was the highest, reaching 72.4%, the volume-weighted average synergy angle increased by 1°, and the viscous dissipation decreased by 21.7%. This study provides a reference for the resistance reduction design of complex local components such as tees in HVAC systems.

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Craig, Michael, Jay Raval, Bruce Tai, Albert Patterson und Wayne Hung. „Effect of Channel Roughness on Micro-Droplet Distribution in Internal Minimum Quantity Lubrication“. Dynamics 2, Nr. 4 (14.10.2022): 336–55. http://dx.doi.org/10.3390/dynamics2040019.

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This research studied the effect of channel roughness on micro-droplet distributions in internal minimum quantity lubrication for effective machining. Mixtures of different oils and air were flown though internal channels with simulated different roughness: as fabricated, partially threaded, and fully threaded. The airborne droplets were collected, analyzed, and compared with simulated results by computational fluid dynamics. For low-viscous lubricant, the rough channel surface helped to break large droplets in the boundary layer into smaller droplets and reintroduce them into the main downstream flow. The opposite trend was found for the higher viscous lubricant. The study also performed chemical etching to roughen selected surfaces of carbide cutting tools. The synergy of hand and ultrasonic agitation successfully roughened a carbide surface within twelve minutes. Scanning electron microscopy examination showed deep etching that removed all grinding marks on a WC–Co cutting tool surface.

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Aiyer, Aditi, Simone K. Visser, Peter Bye, Warwick J. Britton, Gregory S. Whiteley, Trevor Glasbey, Frederik H. Kriel, Jessica Farrell, Theerthankar Das und Jim Manos. „Effect of N-Acetylcysteine in Combination with Antibiotics on the Biofilms of Three Cystic Fibrosis Pathogens of Emerging Importance“. Antibiotics 10, Nr. 10 (27.09.2021): 1176. http://dx.doi.org/10.3390/antibiotics10101176.

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Cystic fibrosis (CF) is a genetic disorder causing dysfunctional ion transport resulting in accumulation of viscous mucus that fosters chronic bacterial biofilm-associated infection in the airways. Achromobacter xylosoxidans and Stenotrophomonas maltophilia are increasingly prevalent CF pathogens and while Burkholderia cencocepacia is slowly decreasing; all are complicated by multidrug resistance that is enhanced by biofilm formation. This study investigates potential synergy between the antibiotics ciprofloxacin (0.5–128 µg/mL), colistin (0.5–128 µg/mL) and tobramycin (0.5–128 µg/mL) when combined with the neutral pH form of N-Acetylcysteine (NACneutral) (0.5–16.3 mg/mL) against 11 cystic fibrosis strains of Burkholderia, Stenotrophomonas and Achromobacter sp. in planktonic and biofilm cultures. We screened for potential synergism using checkerboard assays from which fraction inhibitory concentration indices (FICI) were calculated. Synergistic (FICI ≤ 0.5) and additive (0.5 > FICI ≥ 1) combinations were tested on irreversibly attached bacteria and 48 h mature biofilms via time-course and colony forming units (CFU/mL) assays. This study suggests that planktonic FICI analysis does not necessarily translate to reduction in bacterial loads in a biofilm model. Future directions include refining synergy testing and determining further mechanisms of action of NAC to understand how it may interact with antibiotics to better predict synergy.

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Somigliana, Alice, Leonardo Testi, Giovanni Rosotti, Claudia Toci, Giuseppe Lodato, Benoît Tabone, Carlo F. Manara und Marco Tazzari. „The Time Evolution of Md/Ṁ in Protoplanetary Disks as a Way to Disentangle between Viscosity and MHD Winds“. Astrophysical Journal Letters 954, Nr. 1 (29.08.2023): L13. http://dx.doi.org/10.3847/2041-8213/acf048.

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Abstract As the classic viscous paradigm for protoplanetary disk accretion is challenged by the observational evidence of low turbulence, the alternative scenario of MHD disk winds is being explored as being potentially able to reproduce the same observed features traditionally explained with viscosity. Although the two models lead to different disk properties, none of them has been ruled out by observations—mainly due to instrumental limitations. In this work, we present a viable method to distinguish between the viscous and MHD framework based on the different evolution of the distribution in the disk mass (M d )–accretion rate ( M ̇ ) plane of a disk population. With a synergy of analytical calculations and 1D numerical simulations, performed with the population synthesis code Diskpop, we find that both mechanisms predict the spread of the observed ratio M d / M ̇ in a disk population to decrease over time; however, this effect is much less pronounced in MHD-dominated populations compared with purely viscous populations. Furthermore, we demonstrate that this difference is detectable with the current observational facilities: we show that convolving the intrinsic spread with the observational uncertainties does not affect our result, as the observed spread in the MHD case remains significantly larger than in the viscous scenario. While the most recent data available show a better agreement with the wind model, ongoing and future efforts to obtain direct gas mass measurements with Atacama Large Millimeter/submillimeter Array and next-generation Very Large Array will cause a reassessment of this comparison in the near future.

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Roy, Mahendra Nath, und Biswajit Sinha. „Viscous synergy and isentropic compressibility of some monoalkanols and cyclic ethers in water at 298.15 K“. Journal of Molecular Liquids 133, Nr. 1-3 (März 2007): 89–99. http://dx.doi.org/10.1016/j.molliq.2006.07.009.

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Zhang, Lufeng, Haibo Wang, Fujian Zhou und Jianye Mou. „Numerical Simulation of Wormhole Propagation with Foamed-Viscoelastic-Surfactant Acid in Carbonate Acidizing“. Processes 11, Nr. 6 (19.06.2023): 1839. http://dx.doi.org/10.3390/pr11061839.

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Successful matrix acidizing for extremely thick carbonate reservoirs with long horizontal well sections and strong heterogeneity requires efficient temporary plugging and diverting of acid fluid, ensuring acid fluid distribution to each production layer. Foamed-viscoelastic-surfactant (Foamed-VES) acid combines the benefits of both foam acid and viscoelastic surfactant (VES) acid, integrating foam plugging and viscous plugging. It can achieve uniform acid distribution in highly heterogeneous reservoirs. However, little research has been conducted on the wormhole propagation law of foamed-VES acid. To address this gap, this study established a mathematical model of foamed-VES acid wormhole propagation based on the dual-scale model. The model was coupled with a random porosity distribution generated with geological statistical software. The effects of different factors on foamed-VES acid etching were simulated. Numerical results show that foamed-VES acid can stimulate low-permeability reservoirs with a permeability differential of 20. Its inherent mechanism lies in the synergy of foam plugging and VES viscous plugging. This study enhances our understanding of the acid diversion mechanism of foamed-VES acid, providing a theoretical foundation for on-site acidizing treatment.

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Ren, Diandong, Rong Fu, Robert E. Dickinson, Lance M. Leslie und Xingbao Wang. „Aviation Impacts on Fuel Efficiency of a Future More Viscous Atmosphere“. Bulletin of the American Meteorological Society 101, Nr. 10 (01.10.2020): E1761—E1780. http://dx.doi.org/10.1175/bams-d-19-0239.1.

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AbstractAircraft cruising near the tropopause currently benefit from the highest thermal efficiency and the least viscous (sticky) air, within the lowest 50 km of Earth’s atmosphere. Both advantages wane in a warming climate, because atmospheric dynamic viscosity increases with temperature, in synergy with the simultaneous engine efficiency reduction. Here, skin friction drag, the dominant term for extra aviation fuel consumption in a future warming climate, is quantified by 34 climate models under a strong emissions scenario. Since 1950, the viscosity increase at cruising altitudes (∼200 hPa) reaches ∼1.5% century‒1, corresponding to a total drag increment of ∼0.22% century‒1 for commercial aircraft. Meridional gradients and regional disparities exist, with low to midlatitudes experiencing greater increases in skin friction drag. The North Atlantic corridor (NAC) is moderately affected, but its high traffic volume generates additional fuel cost of ∼3.8 × 107 gallons annually by 2100, compared to 2010. Globally, a normal year after 2100 would consume an extra ∼4 × 106 barrels per year. Intermodel spread is <5% of the ensemble mean, due to high inter–climate model consensus for warming trends at cruising altitudes in the tropics and subtropics. Because temperature is a well-simulated parameter in the IPCC archive, with only a moderate intermodel spread, the conclusions drawn here are statistically robust. Notably, additional fuel costs are likely from the increased vertical shear and related turbulence at NAC cruising altitudes. Increased flight log availability is required to confirm this apparent increasing turbulence trend.

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Roy, Mahendra Nath, und Anuradha Sinha. „Viscous synergy and antagonism and isentropic compressibility of ternary mixtures containing 1,3-dioxolane, water and monoalkanols at 303.15K“. Fluid Phase Equilibria 243, Nr. 1-2 (Mai 2006): 133–41. http://dx.doi.org/10.1016/j.fluid.2006.02.023.

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Liu, Xiaoshuang, Yazhe Wang, Xi Zhang, Yunhao Lu, Rong Wang, Deren Yang und Xiaodong Pi. „Crack healing behavior of 4H-SiC: Effect of dopants“. Journal of Applied Physics 133, Nr. 14 (14.04.2023): 145704. http://dx.doi.org/10.1063/5.0140922.

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We investigate the crack-healing mechanism of 4H silicon carbide (4H-SiC) and reveal the effect of dopants on the crack-healing behavior of 4H-SiC. Vickers indentation tests and thermal annealing are utilized to generate cracks and heal cracks in 4H-SiC, respectively. High-temperature thermal annealing in the air atmosphere is found to be capable of effectively healing indentation-induced cracks and releasing indentation-induced stress in undoped 4H-SiC by the formation and viscous flow of glass phase SiO2. Nitrogen (N) doping is found to assist the atomic diffusion of 4H-SiC. The crack healing of N-doped 4H-SiC is realized by the synergy of host solid diffusion and the padding of glassy SiO2. In contrast, vanadium (V) doping hinders the viscous flow of SiO2 and results in the incomplete healing of cracks in V-doped 4H-SiC. Although the generation of cracks lowers the bending strength of 4H-SiC, the healing of cracks by the padding of glassy SiO2 is found to effectively recover the bending strength of indented 4H-SiC samples. Our work opens a pathway to design thermal processing technologies to heal the cracks and enhance the mechanical properties of 4H-SiC wafers.

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Yin, Yifei, Angui Li, Xiaoqi Wen, Jiawei Zhang, Xin Zhang, Jinnan Guo, Jiaxing Li, Wanqing Zhang und Jigang Che. „Resistance reduction of an elbow with a guide vane based on the field synergy principle and viscous dissipation analysis“. Journal of Building Engineering 54 (August 2022): 104649. http://dx.doi.org/10.1016/j.jobe.2022.104649.

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Caicedo, Carolina, und Heidy Lorena Calambás Pulgarin. „Study of the Physical and Mechanical Properties of Thermoplastic Starch/Poly(Lactic Acid) Blends Modified with Acid Agents“. Processes 9, Nr. 4 (26.03.2021): 578. http://dx.doi.org/10.3390/pr9040578.

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In this work, we present a functionalization strategy of starch-poly(lactic acid) (PLA) blends with organic acids. Lactic and acetic acid were used as acid agents, and oleic acid was also included in the previous acids, with the aim of finding a synergy that thermodynamically benefits the products and provides hydrophobicity. The ratio of starch and sorbitol was 70:30, and the added acid agent replaced 6% of the plasticizer; meanwhile, the thermoplastic starch (TPS)–PLA blend proportion was 70:30 considering the modified TPS. The mixtures were obtained in a torque rheometer at 50 rpm for 10 min at 150 °C. The organic acids facilitated interactions between TPS and PLA. Although TPS and PLA are not miscible, PLA uniformly dispersed into the starch matrix. Furthermore, a reduction in the surface polarity was achieved, which enabled the wettability to reach values close to those of neat PLA (TPS–L-PLA increased by 55% compared to TPS–PLA). The rheological results showed a modulus similar to that of TPS. In general, there were transitions from elastic to viscous, in which the viscous phase predominated. The first and second-order thermal transitions did not show significant changes. The structural affinity of lactic acid with biopolymers (TPS–L-PLA) allowed a greater interaction and was corroborated with the mechanical properties, resulting in a greater resistance with respect to pure TPS and blended TPS–PLA (28.9%). These results are particularly relevant for the packaging industry.

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Pillai, Krishna, Ahmed H. Mekkawy, Javed Akhter und David L. Morris. „Effect of Nebulized BromAc on Rheology of Artificial Sputum: Relevance to Muco-Obstructive Respiratory Diseases“. Advances in Respiratory Medicine 91, Nr. 2 (14.04.2023): 146–63. http://dx.doi.org/10.3390/arm91020013.

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Respiratory diseases such as cystic fibrosis, COPD, and COVID-19 are difficult to treat owing to viscous secretions in the airways that evade mucocilliary clearance. Earlier studies have shown success with BromAc as a mucolytic agent. Hence, we tested the formulation on two gelatinous airway representative sputa models, to determine whether similar efficacy exist. Sputum lodged in an endotracheal tube was treated to aerosol N-acetylcysteine, bromelain, or their combination (BromAc). After measuring the particle size of aerosolized BromAc, the apparent viscosity was measured using a capillary tube method, whilst the sputum flow was assessed using a 0.5 mL pipette. Further, the concentration of the agents in the sputa after treatment were quantified using chromogenic assays. The interaction index of the different formulations was also determined. Results indicated that the mean particle size of BromAc was suitable for aerosol delivery. Bromelain and N-acetylcysteine affected both the viscosities and pipette flow in the two sputa models. BromAc showed a greater rheological effect on both the sputa models compared to individual agents. Further, a correlation was found between the rheological effects and the concentration of agents in the sputa. The combination index using viscosity measurements showed synergy only with 250 µg/mL bromelain + 20 mg/mL NAC whilst flow speed showed synergy for both combinations of bromelain (125 and 250 µg/mL) with 20 mg/mL NAC. Hence, this study indicates that BromAc may be used as a successful mucolytic for clearing airway congestion caused by thick mucinous immobile secretions.

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BAKAS, NIKOLAOS A. „Mechanisms underlying transient growth of planar perturbations in unbounded compressible shear flow“. Journal of Fluid Mechanics 639 (16.10.2009): 479–507. http://dx.doi.org/10.1017/s0022112009991273.

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Non-modal mechanisms underlying transient growth of propagating acoustic waves and non-propagating vorticity perturbations in an unbounded compressible shear flow are investigated, making use of closed form solutions. Propagating acoustic waves amplify mainly due to two mechanisms: growth due to advection of streamwise velocity that is typically termed as the lift-up mechanism leading for large Mach numbers to an almost linear increase in streamwise velocity with time and growth due to the downgradient irrotational component of the Reynolds stress leading to linear growth of acoustic wave energy for large times. Synergy between these mechanisms along with the downgradient solenoidal component of the Reynolds stress produces large and robust energy amplification.On the other hand, non-propagating vorticity perturbations amplify due to kinematic deformation of vorticity by the mean flow. For weakly compressible flows, an initial vorticity perturbation abruptly excites acoustic waves with exponentially small amplitude, and the energy gained by vorticity perturbations is transferred back to the mean flow. For moderate Mach numbers, a strong coupling between vorticity perturbations and acoustic waves is found with the energy gained by vorticity perturbations being transferred to acoustic waves that are abruptly excited by the vortex.Calculation of the optimal perturbations for a viscous flow shows that for low Mach numbers, acoustic wave excitation by vorticity perturbations and the subsequent growth of acoustic waves leads to robust energy growth of the order of Reynolds number, while for large Mach numbers, synergy between the lift-up mechanism and the downgradient solenoidal component of the Reynolds stress dominates the growth and leads to a comparable large amplification of streamwise velocity.

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Sun-Sheng, Yang, Punit Singh und Hui Zhang. „Flow investigations of reverse running volute pumps with backward vanes in comparison to forward type turbine vanes“. Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 233, Nr. 1 (09.04.2018): 111–31. http://dx.doi.org/10.1177/0957650918768354.

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The use of centrifugal pumps as turbines in the recent years has come as a boon to small and micro power application given its simplicity and robustness. However, attempts are continuously being made to improve the performance by modifying the geometry, and yet to retain its simpleness. This paper proposes a new design to the impeller of an existing pump with forward-shaped vanes in an unchanged volute that is in complete contrast to the conventional backward vanes. Three methodologies are involved in the analysis starting with classical theory, experiment and simulations. The theory entails the focus on optimizing the nozzle shape of the impeller to reduce viscous and eddies. The forward vane having shorter nozzle length has proved to be more efficient compared to the longer backward vane impeller, with an efficiency increase of nearly 5%. The experimental and CFD analysis to study the internal flow saw similitude in the streamline change in Euler moment. It also showed that there were not only increased viscous effects but also enhanced flow separation in the backward vanes at overload flows. The study also found radial clearance losses to be unacceptable for both the shapes. The overall conclusion was to move ahead with the forward design and convince the industry to adopt them for there have been greater strides in cost-effective manufacturing processes. The paper also recommends more study of intermediate blade angles since there was still persistence of small degree of vorticities in the forward blade nozzle. The optimization of volute-impeller interface along with the influence of non-flow zone would be other areas for future investigation. Synergy of academia and industry is also welcome to lend improved understanding in pumps as turbines and better translation to praxis.

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Marushko, Yu V., T. V. Hyshchak, S. I. Yesipova, O. V. Dolynna und T. V. Iovitsa. „Efficacy and safety of inhalation 6% N-acetylcysteine in 3% NaCl solution in clinical practice (literature review)“. Modern pediatrics. Ukraine, Nr. 6(126) (29.10.2022): 120–26. http://dx.doi.org/10.15574/sp.2022.126.120.

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The article summarizes the literature on the use of N-acetylcysteine and its combination with 3% NaCl solution (FLU-ACYL broncho) in clinical practice. Studies show that N-acetylcysteine is currently effective in the treatment of respiratory diseases due to its multicomponent effects on the respiratory system and the immune system. Hypertonic (3%) NaCl solution potentiates the action of N-acetylcysteine by inhalation and allows to achieve good results in the treatment of acute and chronic respiratory diseases in the optimal time. One of the well-known in Ukraine products for fast and effective evacuation of viscous sputum is FLU-ACIL broncho, sterile solution for nebulizer and instillation. One 5 ml ampoule contains 300 mg of NAC, which has a mucolytic effect in direct contact with mucus, and 150 mg of hypertonic NaCl solution, which draws water from the intracellular space into the extracellular space by osmosis and increases the proportion of water in the bronchial secretion, dilutes it and thus facilitates its removal. The combination of NAC with hypertonic NaCl solution creates synergy and allows to obtain optimal treatment results with minimal side effects. This combination has mucolytic, anti-film, antiviral, antioxidant, anti-inflammatory and immunomodulatory effects, making it promising in a pandemic SARS-CoV-2. No conflict of interests was declared by the authors.

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Pradhan, Prasanna, und Mahendra Nath Roy. „Viscous synergy and antagonism, excess molar volume, isoentropic compressibility and excess molar refraction of ternary mixtures containing tetrahydrofuran, methanol and six membered cyclic compounds at 298.15 K“. Physics and Chemistry of Liquids 49, Nr. 3 (Mai 2011): 286–301. http://dx.doi.org/10.1080/00319100903147886.

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Melnikova, I. M., und Yu L. Minernitsky. „Individually orientated choice of mucolytic drug for coughing in a child with acute respiratory viral infections“. Medical Council, Nr. 2 (16.02.2019): 224–30. http://dx.doi.org/10.21518/2079-701x-2019-2-224-230.

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Coughing in acute respiratory infections, regardless of the level of infection: upper or lower respiratory tract is a frequent clinical symptom in childhood. The analysis of the modern literature and the data of the authors’ own researches testify to the fact that the prescription of mucoactive therapy in a complex of therapeutic measures (etiotropic, basic therapy, bronchopulmonary drainage, etc.).) should be differentiated and determined not only by the nature and severity of coughs, separated sputum, but also by individual characteristics of the patient, the severity and course of bronchopulmonary pathology, the age of the child, the presence of adverse environmental factors (in particular, passive smoking), the level of compliance with the patient. The use of combined medications simultaneously influencing various pathogenetic mechanisms of inflammation and coughing becomes a promising direction of mucoactive therapy. One of them is Eucabal® syrup containing liquid extracts of thyme and plantain. Due to the synergy of its components, Eucabal® syrup has an expectorant and anti-inflammatory effect, which is important in the initial period of acute respiratory viral infections (tracheitis, bronchitis tracheobronchitis), especially in dry, painful cough with hard-to-remove sputum. In case of acute respiratory viral infections accompanied by a wet cough with a viscous, difficult to separate sputum, mucolytic agents are shown first of all. One of the modern widely used drugs of this group is acetylcysteine (ESPA-NAC®) in a convenient dosage form.

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Shi, Bin, Guangming Zhang, Lei Zhang, Chengjun Wang, Zhonghui Li und Fangping Chen. „Study on a Strong Polymer Gel by the Addition of Micron Graphite Oxide Powder and Its Plugging of Fracture“. Gels 10, Nr. 5 (30.04.2024): 304. http://dx.doi.org/10.3390/gels10050304.

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It is difficult to plug the fracture water channeling of a fractured low-permeability reservoir during water flooding by using the conventional acrylamide polymer gel due to its weak mechanical properties. For this problem, micron graphite powder is added to enhance the comprehensive properties of the acrylamide polymer gel, which can improve the plugging effect of fracture water channeling. The chemical principle of this process is that the hydroxyl and carboxyl groups of the layered micron graphite powder can undergo physicochemical interactions with the amide groups of the polyacrylamide molecule chain. As a rigid structure, the graphite powder can support the flexible skeleton of the original polyacrylamide molecule chain. Through the synergy of the rigid and flexible structures, the viscoelasticity, thermal stability, tensile performance, and plugging ability of the new-type gel can be significantly enhanced. Compared with a single acrylamide gel, after adding 3000 mg/L of micrometer-sized graphite powder, the elastic modulus, the viscous modulus, the phase transition temperature, the breakthrough pressure gradient, the elongation at break, and the tensile stress of the acrylamide gel are all greatly improved. After adding the graphite powder to the polyacrylamide gel, the fracture water channeling can be effectively plugged. The characteristics of the networked water flow channel are obvious during the injected water break through the gel in the fracture. The breakthrough pressure of water flooding is high. The experimental results are an attempt to develop a new gel material for the water plugging of a fractured low-permeability reservoir.

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Roy, Mahendra Nath, Gargi Ghosh und Lovely Sarkar. „Viscous synergic behaviour and solvent–solvent interactions occurring in liquid mixtures of aqueous alkanols with some alkanoic acids“. Physics and Chemistry of Liquids 48, Nr. 5 (Oktober 2010): 564–79. http://dx.doi.org/10.1080/00319100903161507.

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Miana, P., L. Grando, G. Caravello und M. Fabris. „Microthrix parvicella foaming at the Fusina WWTP“. Water Science and Technology 46, Nr. 1-2 (01.07.2002): 499–502. http://dx.doi.org/10.2166/wst.2002.0524.

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The Fusina WWTP receives civil and industrial wastewater from Venice and its hinterland. Its treatment capacity is in the range of 4,000–5,000 m3/h. In winter the Fusina WWTP is subjected to brown and viscous foams developed on the surface of the aeration basins and of the clarifiers. The microscopic observation of biological foams and activated sludge samples showed high concentration of the filamentous organism Microthrix parvicella. This paper investigates the growth of M. parvicella from January 1998 to January 1999 and relates it to foams developed on the aeration basins and clarifiers, to temperature, surfactants, BOD5, NH4, NO3, NO2, DO, PO4 and pH of the wastewater influent, to SVI and the other species of filamentous organisms of mixed liquor. The results demonstrate the strong connection of the foams developed with M. parvicella abundance, the synergic action with surfactants, the dependence of M. parvicella on temperature and no relation to the other chemical and physical parameters investigated.

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Martínez-Martí, Joana, Amparo Quiles, Gemma Moraga, Empar Llorca und Isabel Hernando. „High Internal Phase Emulsions Preparation Using Citrus By-Products as Stabilizers“. Foods 11, Nr. 7 (29.03.2022): 994. http://dx.doi.org/10.3390/foods11070994.

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The citrus juice industry produces about 50% of by-products. Citrus pomace (CP) contains many polysaccharides (mainly cellulose and pectin), which could act as stabilizers and emulsifiers. The aim of this work was to obtain high internal phase emulsions (HIPEs) using unmodified CP at different concentrations to valorize citrus by-products. The synergic effect of pea protein isolate (PPI) with CP to stabilize the HIPEs was also studied. HIPEs structure was analyzed using rheological and microscopy studies as well as color and physical stability of the emulsions. According to rheological data, all samples exhibited a solid-like behavior, as elastic modulus (G’) was higher than viscous modulus (G’’) within the viscoelastic linear region; as % CP and % PPI increased, greater values of G’ and apparent viscosity (η) were achieved. Microscopic images showed that oil droplets had a polyhedral shape and were enclosed by a thin layer of CP and PPI. Increasing concentrations of CP and PPI enhanced oil droplets packaging. Emulsions’ physical stability was better when adding PPI. The results showed that stable HIPEs with 1.25% of CP and PPI over 0.5% can be obtained. These HIPEs could be used to formulate emulsions for food applications, such as mayonnaises, fillings, or creams.

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Begovic, Ermina, Carlo Bertorello, Raffaele Ponzini und Francesco Salvadore. „Planing Hull Hydrodynamic Performance Prediction Using LincoSim Virtual Towing Tank“. Journal of Marine Science and Engineering 12, Nr. 5 (09.05.2024): 794. http://dx.doi.org/10.3390/jmse12050794.

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This work shows the performance of LincoSim, a web-based virtual towing tank enabling automated and standardized calm water computational fluid dynamics (CFD) data sampling, extending previous published applications to the case of a high-speed hull. The calculations are performed for a 1:10 scale model of a 43 ft powerboat hull form in the Froude number range from 0.3 to 2.0. The counterpart physical model is the experimental fluid dynamics (EFD) campaign performed at the University of Naples Federico II, where the resistance, sinkage and trim data have been measured. The EFD/CFD data comparison is performed and shown with a discussion of the spotted differences. The average percentage differences between the EFD and CFD data for the whole speed range are 1.84, 6.87 and 6.94 for the resistance, dynamic trim, and sinkage, respectively. These results confirm the maturity of the standardized and automated CFD modeling for calm water hydrodynamic analysis included in LincoSim, even at very high Froude numbers. The wetted length of the keel and chine and the wetted surface are calculated from numerical data using the advanced post-processing. Finally, as a work in progress, we test a first comparison for the same hull of the EFD and CFD data, considering two seakeeping conditions for head waves at a given wavelength for two velocity conditions. Also, this kind of analysis confirms the tight correlation between the measured and computed outcomes. This synergic interplay of EFD and CFD can link the advantages of both methods to support hull design but also requires experiment planning and final data analysis to obtain physical parameters not easily measurable in laboratory, such as the wetted surface, wetted lengths, proper viscous contribution, and pressure distribution both in calm water and in waves.

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Yin, Hanshuo, Yonggang Lei, Angui Li, Chongfang Song und Baocun Du. „Field synergy principle for compressible laminar flow and the application for drag reduction in microchannel“. Physics of Fluids, 13.10.2022. http://dx.doi.org/10.1063/5.0110710.

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Considering the density variation of compressible fluid, the field synergy principle for compressible laminar flow is presented based on the incompressible flow field synergy principle. The flow resistance is related to the synergy of velocity field and density logarithmic gradient field. Based on the principle of minimum mechanical energy dissipation, the compressible laminar flow field synergy equation is derived. The field synergy principle is verified by an example of the microchannel with expansion cross-section, and the structure is optimized. The results indicate that the viscous dissipation value in the entire flow domain of the optimized structure can be reduced by 13.5%, and the angle between the velocity vector and the gradient field of logarithm of density increases. In fluid flows, it will reduce the fluid flow drag to decrease the synergy angle between the velocity vector and the gradient field of logarithm of density.

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Shao, Ziyi, und Junfeng Wang. „Synergy principle and its application of endwall loss analyses in the turbine stator“. Physics of Fluids 35, Nr. 11 (01.11.2023). http://dx.doi.org/10.1063/5.0173692.

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The endwall flow significantly impacts the turbine performance behavior, and it is necessary to investigate the development of endwall secondary vortices and relevant losses. Inspired by the field synergy principle, the synergy between the velocity and the pressure gradient established by the three-dimensional mechanical energy conservation equation is innovatively applied to the endwall loss analysis in the stator of an axial-inflow turbine. In terms of the synergy equation, the loss is not only related to the viscous dissipation, but also the included angle (or the synergy angle) between the velocity vector and the pressure gradient vector. The physical content of the synergy angle suggests that the larger synergy angle is (i.e., the worse synergy), the higher losses should be. This conclusion has been validated by present numerical results, and an apparent positive correlation between the synergy angle and the losses could be perceived under time-averaged and transient conditions. The worse synergy could be observed at the passage rear part and the wake, where complex passage vortices and local separation exist. In these regions, the local velocity vector is not aligned with the bulk pressure gradient of the mainstream. Hence, the synergy angle has a marked rise, corresponding to the local high losses.

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Shao, Ziyi, Haiyan Zhang und Ruonan Wang. „Development and loss mechanism of turbine secondary flows at a low Reynolds number: A synergy analysis“. Physics of Fluids 35, Nr. 10 (01.10.2023). http://dx.doi.org/10.1063/5.0166644.

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To further explore the development of turbine secondary flows and associated losses at a low Reynolds number, a synergy analysis was developed and implemented. Loss is defined in terms of entropy generation in the present study. Inspired by the field synergy principle in convective heat transfer, the synergy between velocity and pressure gradient was derived from the three-dimensional mechanical energy conservation in a rotating frame. The loss of mechanical energy is not only related to the viscous dissipation but also the included angle (i.e., the synergy angle) between the velocity vector and the pressure gradient vector. A larger synergy angle (i.e., a worse synergy) is found to result in a higher loss for a fixed flow rate and pressure difference. This has been verified by both time-averaged and time-resolved numerical results. It is demonstrated that a worse synergy could be observed in high-loss regions, such as the turbine end wall, the suction-side separation and the wake. The velocity vector is not aligned with the pressure gradient vector in the vicinity of the reverse flow or the adverse pressure gradient, and the synergy angle could be employed as an indicator of these flow deteriorations. It is hoped the synergy could offer the potential method of future turbomachinery aerodynamic optimizations.

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Yan, Yajing, Chongfang Song, Wuxuan Pan, Jie Wang, Fuqiang Liu und Yifan Bai. „Resistance reduction characteristics analysis of the tee based on field synergy and viscous dissipation“. Journal of Building Engineering, Mai 2024, 109625. http://dx.doi.org/10.1016/j.jobe.2024.109625.

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Scott, Thomas W., und Geoff Wild. „How to make an inclusive-fitness model“. Proceedings of the Royal Society B: Biological Sciences 290, Nr. 2008 (04.10.2023). http://dx.doi.org/10.1098/rspb.2023.1310.

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Social behaviours are typically modelled using neighbour-modulated fitness, which focuses on individuals having their fitness altered by neighbours. However, these models are either interpreted using inclusive fitness, which focuses on individuals altering the fitness of neighbours, or not interpreted at all. This disconnect leads to interpretational mistakes and obscures the adaptive significance of behaviour. We bridge this gap by presenting a systematic methodology for constructing inclusive-fitness models. We find a behaviour’s ‘inclusive-fitness effect’ by summing primary and secondary deviations in reproductive value. Primary deviations are the immediate result of a social interaction; for example, the cost and benefit of an altruistic act. Secondary deviations are compensatory effects that arise because the total reproductive value of the population is fixed; for example, the increased competition that follows an altruistic act. Compared to neighbour-modulated fitness methodologies, our approach is often simpler and reveals the model’s inclusive-fitness narrative clearly. We implement our methodology first in a homogeneous population, with supplementary examples of help under synergy, help in a viscous population and Creel’s paradox. We then implement our methodology in a class-structured population, where the advantages of our approach are most evident, with supplementary examples of altruism between age classes, and sex-ratio evolution.

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García, Monserrat, Werner E. van Zyl und Henk Verweij. „Hybrid nylon-6/silica nanocomposites with improved mechanical properties“. MRS Proceedings 740 (2002). http://dx.doi.org/10.1557/proc-740-i1.9.

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ABSTRACTThe study involves the development of new strategies to form technically interesting hybrid nanocomposites with improved mechanical properties. In particular, a new ‘dissolution’ preparative route was developed which incorporates silica nanoparticles (<30 nm) into a nylon-6 matrix. The procedure relies on the judicious choice of organic solvent and pH control. The synthesis involves the dissolution of nylon-6 in formic acid followed by silica particle addition (as an acidified, monodisperse sol) with stirring. Viscous solutions were prepared under cleanroom conditions and casted as thin films which are dried and vacuum treated at ∼60°C. TEM images revealed that the silica particles i.) retained their original shape and size (10–30 nm), ii.) are mono-dispersed and iii.) mainly non-agglomerated. The degree of crystallinity of the composites was determined with XRD as a function of percentage filler added. The nylon-6 phase is semi-crystalline while the silica phase is amorphous. Initial mechanical tests on the composites were conducted and showed with 1wt% silica addition, the E modulus was increased to ∼2600 MPa. The increase in mechanical properties may be a result of the nanosize filler particles which has good synergy with the nylon matrix. Friction and wear properties were also investigated on a pin on disk tribometer by running a flat pin of steel against the composite disc.

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Ellis, Michael D., Carolina Carmona, Justin Drogos und Julius P. A. Dewald. „Progressive Abduction Loading Therapy with Horizontal-Plane Viscous Resistance Targeting Weakness and Flexion Synergy to Treat Upper Limb Function in Chronic Hemiparetic Stroke: A Randomized Clinical Trial“. Frontiers in Neurology 9 (19.02.2018). http://dx.doi.org/10.3389/fneur.2018.00071.

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