Strength Of Force Research Articles

Atmospheric Forcing Dominates the Interannual Variability of Convection Strength in the Irminger Sea

AbstractTransformation of light to dense waters by atmospheric cooling is key to the Atlantic Meridional Overturning Circulation in the Subpolar Gyre. Convection in the center of the Irminger Gyre contributes to the formation of the densest waters east of Greenland. We present a 19‐year (2002–2020) weekly time series of hydrography and convection in the central Irminger Sea based on (bi‐)daily mooring profiles supplemented with Argo profiles. A 70‐year annual time series of shipboard hydrography shows that this mooring period is representative of longer‐term variability. The depth of convection varies strongly from winter to winter (288–1,500 dbar), with a mean March mixed layer depth (MLD) of 470 dbar and a mean maximum density reached of 27.70 ± 0.05 kg m−3. The densification of the water column by local convection directly impacts the sea surface height in the center of the Irminger Gyre and thus large‐scale circulation patterns. Both the observations and a Price‐Weller‐Pinkel mixed layer model analysis show that the main cause of interannual variability in MLD is the strength of the winter atmospheric surface forcing. Its role is three times as important as that of the strength of the maximum stratification in the preceding summer. Strong stratification as a result of a fresh surface anomaly similar to the one observed in 2010 can weaken convection by approximately 170 m on average, but changes in surface forcing will need to be taken into account as well when considering the evolution of Irminger Sea convection under climate change.

Mechanistic Insights Underlying the Drug Release and Skin Permeation of Guanfacine Transdermal Patch with Various Acrylic Pressure-Sensitive Adhesives.

Acrylic pressure-sensitive adhesives (PSAs) are widely applied in transdermal drug delivery systems (TDDS). However, the molecular mechanisms underlying the effect of functional groups of PSAs on drug release and transdermal permeation properties remain insufficiently clear. In this study, we investigated the effect of acrylic PSAs' functional groups on the in vitro release and transdermal permeation properties of a model drug guanfacine (GFC). The rates of release and permeation were hydroxyl PSA (PSA-OH) > non-functional group PSA (PSA-None) > carboxyl PSA (PSA-COOH). Thermal analysis, molecular modeling, Raman spectroscopy, and FTIR were employed to characterize the drug-PSA interactions. The strength of the interaction force between GFC and PSA-None was determined to be negligible. The primary amino of GFC formed a medium-strength hydrogen bond with the hydroxyl of PSA-OH and a strong ionic interaction with the carboxyl of PSA-COOH. Compared to PSA-None, PSA-OH featured a weaker mechanical strength, a higher rheological phase shift angle (δ), and a lower glass transition temperature (Tg), resulting in improved molecular mobility. Furthermore, PSA-OH exhibited higher tack, viscosity, and polarity, providing superior skin adhesion. Overall, it has been demonstrated that drug release and permeation were determined by a combination of interaction strength, molecular mobility, and skin adhesion. The novel discovery expands our understanding of the molecular mechanism of drug-PSA-skin interactions, offering a crucial point of reference for the development‌ of GFC transdermal patches.

정신병원에서의 신체적 제한

The societal image of mental illness is of violent, irrational beings, potential criminals, and people who need attention. As you can see from the previous words, we tend to stigmatize people with mental illness as people who need to be separated from the general social community. According to the Act on the Promotion of Mental Health and Support for Welfare Services for the Mentally Ill, a mentally ill person is a person who has significant limitations in leading an independent daily life due to delusions, hallucinations, disturbances in thinking or mood, etc. However, the existence of such limitations is not a reason for a person to be excluded from the rights that are universally enjoyed by all human beings. Psychiatric hospitals are closed spaces, even for those who choose to be admitted voluntarily, let alone involuntarily. In addition, the symptoms of mental illness can vary from patient to patient and can be highly variable. In these situations, medical staff can get caught up in the need to stabilize patients first and foremost and impose physical restraints without reflecting on familiar management practices. This is due in part to the fact that the criteria for physical compulsion are merely guidelines, which means that the strength of the normative force perceived by the offender is low, and the requirements for physical compulsion are not clear and specific, leaving much room for discretionary judgment by mental health practitioners. In order to ensure that physical restraints on mentally ill people are consistent with their human rights and access to mental health services, it will be necessary to strengthen the normative power of relevant laws and regulations, and to overhaul the system to ensure that the unilateral judgment of psychiatrists as to the need for physical restraints is based on consensus among various internal and external actors.

Performance research and structure optimization of quartz-covered alumina high-strength wear-resistant yarn

Improved abrasion resistance and shear performance of alumina fiber yarns is crucial to the weaving process. Herein, a series of novel SiO2@Al2O3 single-layer and double-layer covered yarns were prepared by winding 48 tex quartz yarn on the outer layer of 120–600 tex alumina yarn with wrapping twist of 50–500 twists/m. Wear resistance, shear force, and tensile fracture properties of the covered yarn were tested and analyzed. Wrapping twist ranges from 50 to 400 twists/m, with increased wrapping twist improving the SiO2@Al2O3 covered yarn's breaking strength, shear force, and wear resistance. As wrapping twist ranges from 400 to 500 twists/m, uneven winding and wear of quartz yarn weaken the breaking strength, wear resistance, and shear properties of SiO2@Al2O3 covered yarn. SiO2@Al2O3 double-layer covered yarn exhibits superior shear force, wear resistance, and tensile breaking strength compared with its single-layer counterpart. In comparison with the initial alumina yarn, wear resistance of SiO2@Al2O3 covered yarn improves by 50%, whereas the maximum shear strength and tensile breaking strength increase by 125% and 15%, respectively. High-strength, wear-resistant SiO2@Al2O3 covered yarn is suitable for alumina fabrics and braid structures, and is expected to be widely used in aerospace and the high-temperature insulation industry.

Peristaltic transport of ethylene glycol‐based graphene oxide non‐Newtonian nanofluid through an endoscope

AbstractEndoscopy, in medical sciences, is a modern mechanism for the examination of internal remote organs by the direct insertion of the illuminated tube inside the body. It also transports the fluid with the movement of contraction and relaxation. The current study aims to explore the peristaltic propulsion of ethylene glycol‐based graphene oxide nanofluid through an endoscope. The considered nanofluid depicts shear‐thinning aspects, which are described by the Carreau–Yasuda fluid model. The modified Darcy's law is employed to describe the porosity of the medium. For a precise calculation, the modified Buongiorno model is adopted with the incorporated Maxwell's model, Brownian motion parameter, and variable for the thermophoresis effect. The mathematical problem linearized under the lubrication approach is solved numerically through Mathematica. After using the experimentally found values of Carreau–Yasuda fluid parameters for different levels of nanoparticle proportion, It is concluded that there is a slight decline in the velocity and the temperature of the nanofluid. Furthermore, a larger Biot number contributes significantly to the heat transfer coefficient. Fluid flow is assisted by a rise in the Darcy porosity parameter. For an increment in the strength of the buoyancy forces, there is a significant uplift in the fluid's temperature and the velocity.

Pickering Emulsions: Role of Particle Wettability and Adhesive Force on Droplet Bridging.

This study demonstrates the engineering of bridged Pickering emulsion (PE) gels by tuning the particle position at the interface and adhesive forces. This is achieved through controlled surface modification of hematite particles using oleic acid in a water-decane system. Microscopy observations revealed that the droplets are stabilized through a bridging mechanism, where oil droplets are connected by a shared monolayer of particles, with an intervening water layer between them. The experimental observations reveal that the concentration of oleic acid affects both the position of particles with respect to the interface (wettability) and adhesive forces, leading to the formation of emulsions with bridged droplets at specific oleic acid concentration ranges. To investigate this, the particle position at the interface and the strength of adhesive force are measured as a function of oleic acid concentration by direct visualization and droplet stretching technique, respectively. These studies confirm that at low oleic acid concentrations, the particle position favors the bridging, as particles are preferentially wettable by the continuous phase (water) but adhesive forces are not strong. Thus, this condition promotes the formation of oil-in-water emulsions without bridging. While, at higher oleic acid concentrations, the position of particles with respect to the interface hinders bridging, despite sufficient adhesive forces, because the particle surface becomes preferentially wettable by dispersed phase (oil), thereby supporting the inversion of emulsions. Therefore, a precise amount of oleic acid is necessary to achieve stable bridging with both factors contributing to the bridge formation. Further, the versatility of the process is illustrated by using different types of oil and particle surface modifiers. In all of the cases, stable emulsions are obtained by droplet bridging at a precise concentration of the modifier. The effect of the particle concentration and water-to-decane volume ratio on the stability of these emulsions is also studied. These emulsions show remarkable stability under undisturbed conditions due to gel-like nature despite the droplets being partially covered with particles. Moreover, after such emulsions are destabilized by external stimuli, emulsions with similar features can be readily and reversibly formed.

Assessment of Microcirculation and Microrheological Parameters of Blood in Patients With Type 2 Diabetes Mellitus Using Biophotonics Techniques.

In this study, the parameters of blood microcirculation and microrheology were measured using the methods of laser aggregometry and optical tweezers invitro, as well as the method of digital capillaroscopy invivo. It was shown that in patients suffering from type 2 diabetes mellitus, an increase in the number of RBC aggregates passing through the narrow capillaries leads to a significant decrease in the velocity of the capillary blood flow, which can be explained by the increased viscosity of the whole blood and decreased deformability of RBCs. Also, for the group of patients, a statistically significant increase in the rate of RBC aggregation and the hydrodynamic strength of aggregates, RBC aggregation and disaggregation forces were observed compared to the control group. We have demonstrated the possibility of using these methods to assess changes in microrheological and microcirculatory parameters of the blood.

Plasticity of 3D Hydrogels Predicts Cell Biological Behavior.

Under 3D culture conditions, cells tend to spread, migrate, and proliferate better in more viscoelastic and plastic hydrogels. Here, we present evidence that the improved cell behavior is facilitated by the lower steric hindrance of a more viscoelastic and plastic matrix with weaker intermolecular bonds. To determine intermolecular bond stability, we slowly insert semispherical tipped needles (100-700 μm diameter) into alginate dialdehyde-gelatin hydrogels and measure stiffness, yield strength, plasticity, and the force at which the surface ruptures (puncture force). To tune these material properties without affecting matrix stiffness, we precross-link the hydrogels with CaCl2 droplets prior to mixing in NIH/3T3 fibroblasts and final cross-linking with CaCl2. Precross-linking introduces microscopic weak spots in the hydrogel, increases plasticity, and decreases puncture force and yield strength. Fibroblasts spread and migrate better in precross-linked hydrogels, demonstrating that intermolecular bond stability is a critical determinant of cell behavior under 3D culture conditions.

Structure, nonisothermal decomposition kinetics, thermal safety and mechanisms of improving stability and sensitivity of RDX/expanded graphite embedment composite

Abstract To understand structure, properties and mechanisms of improving safety of RDX/expanded graphite (EG) embedment composite further and promote the application of EG in energetic materials, embedment stability, formability, detonation velocity, thermal stability, thermal safety and microscopic mechanisms of improving stability and sensitivity of the composite were studied in depth as a supplement to our previous work. Embedment stability was good. Formability (charge density of 1.76 gcm−3) and detonation velocity (7577 ms−1) were acceptable considering the content of EG was 13 wt%. Thermal stability and safety were proved to be improved by kinetics parameters and self-accelerating decomposition temperature. The former was obtained by forty-one kinds of kinetics model functions and six kinetics equations from nonisothermal thermolysis process of RDX. Molecular dynamics were employed to understand microscopic mechanisms for improving safety. Results showed that after being embedded in EG, strength and number of intermolecular forces in RDX crystal increased by 5.45 % and 14.38 %, and N-NO2 maximum bond length of RDX molecule was shorted from 1.60 to 1.56 Å indicating a stronger intermolecular interaction and a safer trigger bond. All these results suggested that RDX/EG embedment composite was a more stable and insensitive system with a certain practical value.

Fabrication of Novel Polyurethane matrix-based Functional Composites with Enhanced Mechanical Performance

Thermoplastic polyurethane (TPU) has gained significant interest in several fields, including automobile steering wheels, and the electronics sector due to their easier processability, abrasive resistance, and self-lubricating performances. However, their strong inherent flammability and significant smoke and heat production during burning limit their industrial applications. Therefore, its applicability can be enhanced with the addition of high-strength reinforcement and making them antibacterial and flame-retardant. This research is designed to examine the influence of zirconium phosphate (ZrP) and zinc oxide (ZnO) nanoparticles on the novel polyurethane/glass fiber reinforced composites for flame retardant and antibacterial applications with improved mechanical performance. Three different types of novel polyurethane (PU1, PU2, PU3) matrices were prepared using different recipes, and 7% ZrP and 5% ZnO nanoparticles were added to the polyurethane matrices separately, and their corresponding composite samples were fabricated using glass reinforcement. Mechanical i.e., Charpy impact, hardness and tensile, and functional i.e., flame retardancy (FR) and antibacterial tests were performed to compare their performance. Mechanical testing results showed that PU3-based composite samples showed the highest values of impact force, hardness, and tensile strength in both ZrP and ZnO nanoparticle-based composite samples. Furthermore, 7% ZrP-PU3 composite exhibited the best performance of flame retardancy due to the presence of hexamethylene diisocyanates (HDI) content. Likewise, the 5% ZnO-PU3-based composite exhibited the highest antibacterial activity along with enhanced mechanical performance.

Comprehensive analysis of orofacial motor skills in children with obstructive sleep apnea.

The neuromuscular activity has a critical role in the permeability of the upper airways. The present study aimed to conduct a detailed and comparative investigation of the orofacial musculature and motor skills of children with obstructive sleep apnea (OSA). Children aged 7 to 12 years with OSA (OSA group, n = 12) and without OSA (Control group, n = 12) were compared. Orofacial appearance/posture and motor skills were assessed using the orofacial myofunctional evaluation protocol with scores. Bite force, tongue pressure measurements, and surface electromyography of swallowing were also performed. Compared to the control group, the OSA group obtained lower scores in appearance/posture, mobility, and orofacial functions (P < 0.0001), and lower values of bite force (P = 0.019) and tongue strength in protrusion (P = 0.008) and deglutition (P = 0.004). The OSA group also displayed lower values of maximum speed (P = 0.003) and peak activity (P = 0.0005) during spontaneous swallowing and higher relative energy expenditure (integral) of the muscles in the water swallowing task (50 mL) (P ≤ 0.01). Notably, the effect size ranged from moderate to large for all groups differences. The children with OSA showed impairments in orofacial musculature and motor skills, as evidenced by reduced muscle recruitment capacity and coordination in applying pressure/force and performing orofacial movements and functions. This study contributes to the understanding of non-anatomical factors associated with OSA in children and to the development of therapeutic strategies.

An introduction to the “balance of fear”: case studies of North Korea’s challenge to the United States and South Korea’s KMPR against North Korea

ABSTRACT In late 2023, North Korea announced its intention to attack and annex South Korea despite the US’ nuclear umbrella for South Korea. Simultaneously, South Korea has been threatening a its decapitation operation against the North Korean leader. How does a small nuclear state, North Korea, ignore the nuclear umbrella of the United States, the nuclear superpower, and a non-nuclear South Korea challenge North Korea? This article introduces the “balance of fear” concept to search for answers to these two questions. It argues that the conventional “balance of terror” concept and the “balance of resolve” concept as well cannot provide a sufficient answer. In contrast, the balance of fear concept explains that not the strength of nuclear forces, but the amount of fear decides the failure or success in deterrence: North Korean leaders may have less fear for US massive retaliation than the US leaders’ fear for North Korea’s suicidal nuclear attack on US cities.

Guiding onshore exchange rates with ‘free-market’ insights: discovery of a new predictor

ABSTRACT Under the managed floating exchange rate regime, onshore exchange rates often do not reflect the ‘free-market’ level due to regulation and intervention. In this paper, we derive the implied ‘free-market’ exchange rates from gold prices and quantify the strength of market force guiding the onshore exchange rates as a new predictor. Using machine learning methods to make forecasts, we find that the inclusion of this new predictor improves the forecasting performance of one-day-ahead onshore exchange rate returns across all models.

Effect of Laser Power on Weld Formability and Residual Stress of Unequal Thickness 410 Ferritic Stainless Steel/RCL540 Low-Carbon Alloy Steel.

In this paper, the butt joint of unequal thickness 410 ferritic stainless steel and RCL540 low-carbon alloy steel sheets are realized by laser welding. The effects of different laser powers on weld formability, mechanical properties, and residual stress in the welding process are investigated. It is observed that with increasing laser power, the heat accumulates at the bottom of the molten pool and weld metal, causing the ratios of upper and lower melt widths to decrease. The tensile test results show that all specimens fractured in the weak zone of the base metal on the stainless steel side at 10 mm from the weld seam. The residual stress distributions of the specimens are calculated using ABAQUS 2022 software and compared with the measurements of the blind-hole method. It is found that the stainless steel side produces tensile stresses, with the power increase offset by compressive stresses in the base metal. When the laser power is 1200 W, the welded joint has the best weld formability and mechanical properties and the least residual stress. The upper and lower melt width ratio is 1.17, the maximum microhardness of the weld metal is 374.7 HV, the maximum test force and tensile strength are 5617.5 N and 468.12 MPa, respectively, and the minimum values of the transverse and longitudinal stresses are -45.8 MPa and -106.4 MPa, respectively.

A computer simulation study of a chiral active ring polymer.

We investigate a ring polymer under the influence of chiral active Brownian forces in two dimensions using coarse-grained computer simulations. We observe a non-monotonic behavior of the radius of gyration of an active Brownian ring as a function of active force. However, the shrinkage of the ring in the intermediate strength of active forces becomes more pronounced in the presence of chiral active forces, and the shrinkage is monotonic at a given activity level as a function of the angular frequency controlling the direction of the active force. The distribution of radius of gyration, inter-monomer distance, and radial distribution suggest that the monomers come close to each other, eventually leading to the shrinkage of the ring. Moreover, the bond-correlation suggests that the chirality introduces a local folding of the monomers. Furthermore, using the diameter correlation function, we show that the ring performs tank-treading motion with a frequency following power-law relation with active force with exponent 3/2. The mean squared displacement of the monomers further assists the tank-treading dynamics by exhibiting oscillatory behavior.

The evolutionary landscape of prokaryotic chromosome/plasmid balance

The balance between chromosomal and plasmid DNAs determines the genomic plasticity of prokaryotes. Natural selections, acting on the level of organisms or plasmids, shape the abundances of plasmid DNAs in prokaryotic genomes. Despite the importance of plasmids in health and engineering, there have been rare systematic attempts to quantitatively model and predict the determinants underlying the strength of different selection forces. Here, we develop a metabolic flux model that describes the intracellular resource competition between chromosomal and plasmid-encoded reactions. By coarse graining, this model predicts a landscape of natural selections on chromosome/plasmid balance, which is featured by the tradeoff between phenotypic and non-phenotypic selection pressures. This landscape is further validated by the observed pattern of plasmid distributions in the vast collection of prokaryotic genomes retrieved from the NCBI database. Our results establish a universal paradigm to understand the prokaryotic chromosome/plasmid interplay and provide insights into the evolutionary origin of plasmid diversity.

Numerical modeling of the transfer length of 17.8 mm (0.7 in) diameter prestressing strands in pretensioned members

The bond between concrete and reinforcing steel bars in reinforced concrete structures is crucial. Prestressing strands with a diameter of 17.8 mm (0.7 in) transfer higher compression per unit area than smaller strands, improving moment capacity and shear strength and extending the girder span. However, limited research on the bond performance of these 17.8 mm diameter prestressing strands has restricted their widespread use despite their advantages. This study presents a methodology to determine the transfer length of pretensioned members numerically. The influence of pretension force and bond strength on a 17.8 mm diameter strand was assessed through the validation of a finite element model using experimental results from a standardized pretensioned pull-out test. Analytical calculations using different code formulas were also conducted, encompassing strands of varying diameters. Our finite element analysis suggests that a 50.8 mm spacing between adjacent 17.8 mm diameter strands is applicable, ensuring there is no stress overlap in the transfer zones, which can lead to concrete cracking and reduced structural integrity. Existing code formulas, such as ACI 318–19 and AASHTO LRFD 9th edition, require longer transfer lengths when compared with the numerical results. The fib MC 2010 and EC2 formulas offer closer results to numerical results of smaller diameter strands but underestimate the transfer length for the 17.8 mm diameter strand. Therefore, improvements to code formulations may be necessary for more accurate transfer length predictions for this specific strand size.

Combining in-situ quadrupole mass spectrometer analyses: Study on the structure–activity relationship and lubrication mechanisms of ammonium phosphate ionic liquids

Since the lubrication performances of ionic liquids are closely linked to their unique structures, four protic ionic liquids (PILs), [N44HH][DEHP], [N444H][DEHP], [N448H][DEHP] and [N4412H][DEHP], are designed to investigate the effect of cationic structures on the lubrication behaviors and lubrication mechanisms. Vacuum tribological tests were carried out to minimize the impact of the atmospheric environment. The structure–activity relationships and lubrication mechanisms of PILs were emphatically examined by in-situ quadrupole mass spectrometer (Q-MS) and XPS analyses. Results demonstrated that all four PILs exhibited outstanding lubrication performance under a vacuum condition. Unusually, extended alkyl chain cationic structures resulted in a changed lubrication mechanism, leading to a slight decrease in performance. In-situ Q-MS analyses and XPS further revealed that the length of the alkyl chain in cations influenced the strength of intermolecular forces in PILs, leading to changes in their lubrication performance and mechanisms.

High stability of charged particle clusters in protoplanetary disks

Context. The initial particle growth in protoplanetary disks is limited by a bouncing barrier at submillimeter wavelengths. Bouncing leads to tribocharging and the electrostatic attraction of tribocharged aggregates may eventually draw them into large clusters. A charge- mediated growth phase allows for the formation of larger entities, namely, clusters of aggregates that are more prone to further particle concentrations, such as the streaming instability. Aims. We aim to quantify the strength of the electrostatic forces. Methods. In laboratory experiments, we used an acoustic trap to levitate small aggregates of tribocharged submm grains. These aggregates spin up within the trap until they lose grains. Thus, we used the centrifugal force as a measure of the local force. Results. Grains are regularly bound strongly to their neighbors. In comparison, the force at ejection can be stronger than the attractive scattering forces of the trap and can therefore be several orders of magnitude larger than expected. We note that these forces are long- ranging, compared to van der Waals forces. Thus, charged aggregates are much more stable than uncharged ones. Conclusions. Particle aggregates in disks might grow to centimeter clusters or larger as tribocharging increases the effective binding forces. This allows for hydrodynamic concentration and planetesimal formation to eventually take place throughout a wide part of the disk.

The Mechanical Properties and the Threshing Damage and Its Effects on Nutritional Quality of Buckwheat Grains

Buckwheat grains will suffer varying degrees of damage during the threshing process. Damaged grains are prone to changes in nutritional quality during storage. To explore the relationship between the threshing damage mechanism and nutritional quality, the mechanical properties of buckwheat with different moisture contents were determined through compression and friction tests, obtaining some conventional mechanical property indicators. On this basis, a 3D collision model of buckwheat–nail tooth was established, and the dynamic process of collision was simulated with LS-DYNA. During collision, the changes in energy, von Mises stress, and critical damage velocity of grains with different moisture contents were analyzed. After the threshing test, the grains were observed and classified according to the degree of damage. The differences in nutritional components of different types of grains were analyzed through physicochemical experiments. The experimental results showed that the failure force, elastic modulus, and ultimate strength of buckwheat grains were negatively correlated with moisture content, while the deformation and friction coefficient were positively correlated with moisture content. During collision, the von Mises stress of the grains showed a pattern of increase and then decrease. The maximum stress value occurred at the contact area center, spreading along the periphery and gradually decreasing. The maximum von Mises stress decreased with increasing moisture content and increased with increasing collision velocity. The critical damage velocities of grains at moisture contents of 11.98%, 15.77%, 18.04%, 20.82%, and 25.22% were 13.07, 11.72, 10.94, 10.55, and 10.15 m/s, respectively. After threshing, grains were divided into three types: undamaged, surface cracked, and shell damaged. The nutritional quality of the last two damaged grains decreased during the storage process. These results are of great significance for optimizing buckwheat threshing parameters, reducing buckwheat damage, and improving the economic performance of the buckwheat industry.