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A new constant life diagram (CLD) model featuring asymmetric bilinear constant-life curves was proposed to better describe the longitudinal fatigue behavior of unidirectional laminae (UD) under a wide range of stress ratios. This model is able to predict S-N curves with satisfactory accuracy not only in tension-tension (T-T) fatigue mode but also in tensioncompression (T-C) and compression-compression (C-C) modes, whereas the conventional Goodman CLD model shows inferior performance especially in T-C and C-C modes. Apart from static tension and compression tests, high- and low-cycle fatigue tests at two stress ratios corresponding to T-T and C-C modes should be performed to determine the parameters in the proposed model. Fatigue test data of several different GFRP UDs at various stress ratios were utilized to validate the proposed model, and the S-N curves predicted by the proposed model agreed well with the experimental results. Compared with the Goodman CLD model, the proposed CLD model demonstrates an enhanced predictive capability without losing its simplicity.

This paper presents a novel micromechanical unit cell model for continuous fiber reinforced composites, which features a fiber with an octagonal cross-section embedded in surrounding matrix, and was named as octagonal fiber model. The cross-section of octagonal fiber model was subdivided into five by five sub-regions, and the conditions of equilibrium and deformation compatibility were applied to derive expression of effective ply properties, and stress amplification factors, which correlate microstresses in sub-regions with ply stresses. For E-glass/epoxy and carbon/epoxy material systems with different fiber volume fractions, effective ply properties and stress amplification factors in sub-regions were evaluated using derived formulae. Results from octagonal fiber model were then compared with those from multiple analytical methods and finite element unit cell model. It was shown that effective ply properties predicted by octagonal fiber model were generally in good agreement with those from finite element model, and octagonal fiber model outperformed other analytical counterparts in estimating stress amplification factors, demonstrating the potential of octagonal fiber model.

Since its first systematic study in 2004, graphene and their derivatives has treated as one of the most exotic materials for the scientific community, and its exceptional physical properties have produced huge research articles. Herein, we are reporting a sustainable route to neutralize the highly acidic graphene oxide (GO) solution obtained through chemical exfoliations of graphite. To achieve this, we have used 1N Ba(OH)2 solution to maintain/neutralize pH of acidic GO solution. By adding this step to Hummer’s and related methods we could save at least 10L distilled water for each 2g of pure GO productions in short time compared to other methods

Damage generated due to low velocity impact in composite plates was evaluated focusing on the design and structural integrity of wind turbine blades. Impact properties of composite plates manufactured with thermoplastic and thermoset resins for different energy levels were measured and compared. Specimens were fabricated using VARTM (vacuum assisted resin transfer molding), using both matrix systems in conjunction with carbon, glass and carbon/glass hybrid fibers in the NCF (non-crimp fabric) architecture. Resin systems used were ELIUM 188O (thermoplastic) from Arkema Co., Ltd. and a standard epoxy reference, EPR-L20 from Hexion Co., Ltd. (thermoset). Auxiliary numerical finite element analyses were performed to better understand the tests physics. These models were then compared with the experimental results to verify their predictive capacity, given the intrinsic limitations due to their simplicity. Based in the presented results, it is possible to observe that ELIUM is capable to replace a conventional thermoset matrix. The thermoplastic panels presented similar results compared to its thermoset counterparts, with even a trend of less impact damage. Additionally, for both thermoplastic and thermoset resin systems, glass layups showed the lowest levels of damage while carbon panels presented the highest damage levels. Hybrid laminates can be applied as a compromise solution.

The fatigue life of megawatt-scale composite wind turbine blades implemented with shallow-angled laminates is investigated. Full dynamic simulations of a 5-MW 3-bladed horizontal-axis wind turbine were carried out to estimate the incident fatigue loads. The fatigue stress histories experienced by lay up materials were then computed using a finite-element model of the composite blade developed to ply-level details. Thereafter, the fatigue life of blade was estimated considering the 100% availability of the turbine for the site-specific annual wind distribution related to the wind turbine class IB. It is demonstrated that the application of shallow-angled laminates leads to a more durable design.

Herein, we report the use of Multi Wall Carbon Nano Tubes (MWCNTs) as nano-compatibilizers based on their astonishing mechanical properties and ease of processing. To fabricate laminate samples, pure MWCNTs were homogeneously dispersed in the fiber-reinforced plastic (FRP) composite with 0, 0.5, 1 and 1.5 wt. % loading. The laminates were prepared with eight plies (4.0 ± 0.1 mm thickness) using the hand layup technique assisted by the compression moulding method. It was found that the tensile, compressive and inter-laminar shear strength (ILSS) increase by 103.81%, 139.78% and 36.06%, respectively corresponding to 1 wt. % loading of MWCNTs as compared to neat GFRP specimen. However, a rapid decrease in strength beyond 1 wt. % loading of MWCNTs has been noted. Interestingly, the maximum of the tensile strength was higher than that of the compressive strength, and the maximum of the tensile modulus was larger than that of the compressive modulus in the case of 1 wt. % loading of MWCNTs. It was observed that after a certain loading, the mechanical properties of such laminates can only reach the best value with an optimum loading of MWCNTs. In addition, the micromechanical failure modes and effect of MWCNTs loading on internal morphologies of the composites were also intensively explored with the help of Field Emission Scanning Electron Microscopic (FESEM) analysis. Keywords: Mechanical properties, MWCNTs, Fiber-reinforced plastic, Tensile strength, Compressive strength, ILSS properties, Failure modes

Titania decorated RGO/CNT hybrid electrode material was prepared for supercapacitor (SCs) application through facile hydrothermal approach. Combined act of 1D CNTs and 2D RGO assists the uniform in-situ growth of titania towards high surface area mesoporous self-assembled interconnected morphology which is confirmed from FESEM and BET surface area analysis. This interconnected porous network like structure can efficiently allow the better mass transport and decreased contact resistance towards high electrochemical utilization. Electrochemical measurements revealed the superior performance of hybrid nanocomposite comprising of titania/RGO/CNT (TG1C1) which exhibited maximum specific capacitance around 477 F/g at current density 1 A/g. However, this capacitance value was further enhanced up to 537 F/g after 1 hour of UV light irradiation. This enhancement could be ascribed to photo-catalytic effect of TiO2 and corresponding genesis of photo-excited electrons on TiO2 surface which further channelized through interconnected RGO and CNT morphology and hence results in improved specific capacitance. These observations were in good agreement with cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) analysis. The hybrid nanocomposite also showed satisfying energy density and power density. It was also found that prepared hybrid nanocomposites were stable up to 2000 cycles with maximum specific capacitance retention of 92% of initial value.

A hybrid multi-scale approach combining a virtual mesoscale volume element (representative volume element) and a microscale finite element representative unit cell is developed, for progressive failure prediction of short fiber reinforced composites. The representative volume element represents the fiber orientation and distribution of the whole composites, from which the global mechanical behavior can be estimated. The representative unit cell captures the local mechanical response of each short fiber by transforming global strains to local strains. The constituent strains of the fiber, matrix, and interface are calculated from local strains using representative unit cell. Correlations between mesoscale local strains and microscale constituent strains are established using strain amplification factors. After computing microscale stresses, a progressive damage model is employed to determine the damage status of all constituents. A homogenization method is employed to eliminate damage localization in the matrix and interface. The predicted stress–strain curves are compared with experimental results, and good agreement is also achieved.

The present paper intends to enhance the literature survey on the defect of fiber waviness generated during the manufacture of fiber reinforced polymer composites. In particular, the objective is to include areas previously neglected in the literature, adding new information and approaches that are of interest to researchers pursuing to investigate waviness. Analysis methodologies developed with the purpose of mechanical performance prediction are here collated and compared. Experimental techniques specially elaborated to investigate the effects of waviness in key structural properties are also investigated and debated, in light of the state-of-the art in this field of study. Ultimately an identification of which parameters are significant when dealing with a wavy laminate is proceeded, providing valuable information that narrows the domain of variables that could truly affect the mechanical response of a structure in the presence of waviness.

This two-part article scrutinizes the influence of metal layer distribution through the thickness of titanium-based fiber metal laminates (FMLs) on their high-velocity projectile impact response and damage. The four different layups of FMLs consist of layers of glass fiber/epoxy and Ti-6Al-4V titanium alloy sheets, exhibiting the thickness of the total metal layer the same. Part I presents the experimental investigations of fully clamped FMLs demonstrating performance parameters, damage mechanisms, and ballistic resistance. Part II concerns the ballistic impact behavior of FMLs using analytical modeling, which is based on test results obtained in an accompanying study. An equivalent mass-spring system is used to obtain the transient deformation, ballistic limit, and absorbed energy of the laminate by various mechanisms. Good agreement is obtained between experimental and analytical ballistic limit velocity. The foremost part of the total energy absorption is by bending and membrane energy absorption (68 % - 72 %), with FML 4/3-0.3 absorbing a higher percentage of aforementioned energies followed by that of both FMLs 3/2 and FML 2/1-0.6. The predicted total energy absorption by several damage mechanisms of FMLs at the ballistic limit displays a reasonable matching with experiments.

This two-part article examines the distribution of metallic layers through the thickness of fiber metal laminates (FMLs) on their response and damage when subjected to high-velocity projectile impact. Glass fiber/epoxy and Ti-6Al-4V titanium alloy sheets are used to obtain four different layups of FMLs fabricating by the hand layup process and exhibiting the same thickness of the total metal layer. Part I deals with experimental investigations of fully clamped square FMLs normally impacting at the center by hemispherical steel projectile using compressed air gun set up. Different parameters are considered to evaluate the FMLs’ performance, which includes damage degree, first cracking energy, crack length, deformation profile, and damage developed on the surface and inside the laminate. The results indicate that the highest permanent deformation and cracking are exhibited by FML 4/3-0.3, exhibiting separation of composite layers with different orientations by the metallic layer. The other FMLs exhibit lower and approximately similar permanent deformations. However, lower cracking and a relatively higher lateral delamination spread and opening of the interlayer are exhibited by FML 2/1-0.6 in which composite layers are arranged together than FML 4/3-0.3, signifying that the damage spreading laterally can be reduced by dispensing titanium layers. The ballistic resistance is found to be similar for FMLs. The levels of permanent deformation, cracking, and delamination with their opening and spreading are lesser for titanium-based FMLs than aluminium-based FMLs. The ballistic response of FMLs will be evaluated using analytical modeling in an accompanying study (Part II).

The objective of this paper is to unveil the background theory behind the universal master ply assumption, based on the invariant approach, to describe ply elastic properties. It was demonstrated that using ply-based constitutive relations, trace-normalized stiffness properties can be derived for different materials. Theoretical predictions for trace-normalized parameters were plotted as functions of the unidirectional ply longitudinal modulus ( Ex), which defines the particular material system. Ply stiffness extensive empirical data were obtained from literature for four types of material systems (high modulus carbon/epoxy, standard modulus carbon/epoxy, aramid/epoxy, and glass/epoxy) and correlated quite well to theoretical predictions. Theoretical curves presented a nonlinear region for low Ex which gradually evolves to a plateau as Ex increases. It was verified that the master ply concept averaging the trace-normalized ply stiffness matrix elements can be applied for high modulus carbon/epoxy, standard modulus carbon/epoxy, and aramid/epoxy material systems. However, glass/epoxy systems can not be represented by this concept. The exposed theoretical background supports trace-based approach and enhances its effectiveness as a design tool, encompassing all the consequent advantages.

Two simplified methods for progressive failure prediction of structures made of braided composites, mainly subjected to uniaxial in-plane loading or bending, were proposed, in order to bypass the complexity associated with meso- and micro-mechanics without losing much accuracy. One method models braided composites as equivalent one-dimensional material with different tensile and compressive strengths, for structures mainly subjected to uniaxial loading. The other more general method models braided composites using equivalent laminates, used together with Hashin’s progressive damage model. The parameters required in two methods were calibrated using stress-strain curves generated through the multi-scale approach, which combines micromechanics of failure (MMF) and meso-mechanical models describing the geometries of braided composites. Good agreement was observed in the moduli and strengths estimated using both proposed methods and the multi-scale approach, for braided composites with braiding angles ranging from 15 to 75 degrees subjected to uniaxial tension and compression. Finally, the proposed methods were utilized to predict the response of a landing gear structure fabricated using braided composites under bending. Reasonable agreement between experimentally acquired load-displacement curve and prediction was achieved.

Since the last 500 years, science is becoming more and more dominant in our civilization and continuously making the life of human beings more convenient. Along with the numerous fundamental discoveries and innovations, twenty-first century will be evoked as technological achievements for a long time. Among the many outstanding scientific achievements, the introduction of graphene can be considered as one of the most important breakthroughs for this century. This single-atom thin 2D carbon nanomaterial is the foundation of all graphitic structures. Owing to its amazing physical and chemical properties, graphene has found applications in many scientific and technological fields, from medical science to aerospace engineering. However, scientists of the various disciplines are working hard individually and in collaborations around the globe to utilize and explore application potentials of the graphene and its derivatives (graphene oxide, graphene quantum dot, graphene nanoribbon, functionalized graphene etc.). In this chapter, some novel discoveries and innovations closely related to the graphene-based advanced nanomaterials for the real-time applications have been reviewed in detail, especially in contest of high-performance polymer blends, nanocomposites for catalysis, water splitting and 3D printings. In addition, a brief outline for the fabrication of graphene-based polymer blends and nanocomposites has also been discussed with appropriate citations for the further reading.

Finite element representative unit cell models are established for the study of progressive failure of woven fabrics: plain weave, twill weave, and satin weave. A multi-scale approach ranging from the meso-scale to micro-scale regime is used, providing the failure observation inside the constituents. The constituent stresses of the fiber and matrix in the warp and fill tows of the woven fabric unit cell are calculated using micromechanics. Correlations between meso-scale tow stresses and micro-scale constituent stresses are established by using stress amplification factors. After calculating micro-scale stresses, the micromechanics of failure damage model is employed to determine the progressive damage statuses in each constituent of woven fabric composites. For the matrix of tows, a volume-averaging homogenization method is utilized to eliminate damage localization by smearing local damages over the whole matrix region of the unit cell. Subsequently, the ultimate strength is predicted for woven composites with different tow architectures. The prediction results are compared with the experimental values, and good agreement is observed.

A novel method of characterizing moisture effect on mechanical performance of epoxy resin is presented in this paper. A 50-µm-thick layer of cured epoxy resin was fabricated and cut into strips of 4 mm wide and 30 mm long as specimens to be tested on a dynamic mechanical analyzer equipped with thin-film tension clamp. Static tension and force-controlled tension–tension fatigue tests were first carried out using thin-film specimens made from Momentive 135/137 and BASF 5400/5440 epoxy resin systems without applying moisture, and results were compared with those obtained using conventional dog-bone specimens to validate the proposed testing method. Another batch of thin-film specimens were then immersed into deionized water, and the weight gain was recorded regularly until full saturation to obtain the absorption curve. Static and fatigue tests were performed using thin-film specimens made from BASF 5400/5440 with 55% and 100% saturation of moisture respectively, to evaluate moisture-induced material degradation. The aging effect on BASF 5400/5440 caused by cyclic water immersion and drying process was also assessed by performing static and fatigue tests using fully dried thin-film specimens after aging. It was concluded that the combination of thin-film specimen and dynamic mechanical analyzer would yield as good measurements of tensile strength and fatigue life as conventional dog-bone specimen does, and the small thickness of thin-film specimen would greatly reduce the time to reach a certain level of moisture content, facilitating further studies on effect of moisture ingression on polymeric matrix composites using multi-scale approaches.

The bend–twist coupling (BTC) is proven to be effective in mitigating the fatigue loads for large-scale wind turbine blades, but at the same time it may cause the risk of flutter instability. The BTC is defined as a feature of twisting of the blade induced by the primary bending deformation. In the classical flutter, the BTC arises from the aerodynamic loads changing with the angle of attack. In this study, the effects of the structural BTC on the flutter are investigated by considering the layup unbalances (ply angle, material and thickness of the composite laminates) in the NREL 5-MW wind turbine rotor blade of glass fiber/epoxy [02/+45/−45]S laminates. It is numerically shown that the flutter speed may decrease by about 5 percent with unbalanced ply-angle only (one side angle, from 45° to 25°). It was then demonstrated that the flutter performance of the wind turbine blade can be increased by using lighter and stiffer carbon fibers which ensures the higher structural BTC at the same time.

Background The aim of this multicenter study was to evaluate the safety and efficacy of tolvaptan (TLV) in Korean patients with the syndrome of inappropriate secretion of antidiuretic hormone (SIADH). Methods Of 51 enrolled patients with SIADH, 39 patients (16 female patients, aged 70.8 ± 11.3 years) were included in an intention to treat analysis. All patients received 15 mg/day as the initial dose, and the dose was then increased up to 60 mg/day (as needed) until day 4. Results Serum sodium increased significantly from baseline during the first 24 hours (126.8 ± 4.3 vs. 133.7 ± 3.8 mmol/L, P < 0.001), rose gradually between days 1 and 4 (133.7 ± 3.8 vs. 135.6 ± 3.6 mmol/L, P < 0.05), and then plateaued until day 11 (136.7 ± 4.5 mmol/L). The correlation between the change in serum sodium for the first 24 hours and initial serum sodium concentration was significant (r = −0.602, P < 0.001). In severe hyponatremia (< 125 mmol/L), the change was significantly higher (11.1 ± 4.8 mmol/L) than in moderate (6.4 ± 2.5 mmol/L, P < 0.05) or mild hyponatremia (4.3 ± 3.3 mmol/L, P < 0.01). In addition, logistic regression analysis showed that body weight (odds ratio [OR], 0.858; 95% confidence interval [CI], 0.775–0.976; P = 0.020) and body mass index (BMI) (OR, 0.692; 95% CI, 0.500–0.956; P = 0.026) were associated with rapid correction. No serious adverse events were reported, but in 13% of patients hyponatremia was overcorrected. Conclusion TLV is effective in correcting hyponatremia and well-tolerated in Korean patients with SIADH. However, those with low body weight, low BMI or severe hyponatremia, could be vulnerable to overcorrection with the initial dose of 15 mg TLV., Graphical Abstract

The application of shallow-angled skins with off-axis fiber angle less than 45°, increases the bending stiffness and strength of the large-scale wind turbine blade but reduces its torsional stiffnesses, making it susceptible to the classical flutter instability problem. Single-blade quasi-steady eigenvalue analyses using HAWCStab2 were performed to evaluate the flutter performance of a 5 MW pitch-regulated wind turbine blade with shallow-angled skins configurations. The results showed that the application of shallow-angled skin design concept to the 5 MW blade model does not pose the flutter instability problem.

The parametric study of unbalanced tri-axial non-crimp fabrics laminates, typically used in the blade skin layup, showed that the highest bend-twist coupling up to 0.56 was achieved when all three kinds of unbalances (i.e. ply-angle, ply-material and ply-thickness unbalances) were simultaneously present in the laminates. Based on aeroelastic tailoring via unbalanced laminates, the bend-twist coupling towards feather of various degrees was implanted to the skin layup of a variable-speed collective-pitch controlled 5 MW wind turbine rotor blades and fully-coupled aero-servo-elastic analyses were performed. The results showed that when the ply-thickness unbalance is added in the skin layup, in addition to already existing ply-angle and ply-material unbalances, an average increase in the coupling magnitude by approximately 51% along the blade length and a reduction in fatigue load and collective-pitch demand by approximately 1.6–2.9% and 5.5–19.9% across the range of applied stochastic winds ranging from 7 m/s to 23 m/s.

Two shallow-angled symmetric and asymmetric skins, with off-axis fiber angles of less than 45°, were proposed and employed to a 5 MW wind turbine blade. For the symmetric configuration, shallow-angled skins were applied to both the pressure and suction sides of the blade, while, for the asymmetric configuration, only the pressure side was implemented with a shallow-angled skin, keeping the conventional 45-degree-angled skin for the suction side. The blade tip deflection, modal frequencies, buckling stability, and failure index were computed for off-axis fiber angles of 45°, 35°, and 25°. The use of shallow-angled skins improved blade bending stiffness and strength. The buckling resistance decreased for symmetric skins and remained unchanged for asymmetric skins; the former case was compensated for by increasing the core thickness. For both skin configurations, a reduction in the blade failure index of up to 18% and 38%, and mass reductions of up to 8% and 13% were demonstrated for the 35° and 25° shallow-angled skins, respectively.

Hyperuricemia is known to be associated with the presence of cardiovascular and metabolic syndrome and with the development of incipient kidney disease and an accelerated renal progression. However, an elevated uric acid level was not generally regarded as a true etiology or mediator, but an indicator of these diseases. Uric acid has recently regained the clinical interest and popularity based on emerging data suggesting the causative role of hyperuricemia in cardiovascular and renal disease. Experimental data demonstrates oxidative stress is one of the earliest phenomena observed in vascular, renal, liver cells and adipocytes exposed to uric acid. Since uric acid is one of the major antioxidants of plasma acting as a free radical scavenger and a chelator of transitional metal ion, uric acid-induced oxidative stress seems paradoxical. Data regarding the clinical implication of hyperuricemia is even more confusing, which defines hyperuricemia as a useless parameter to be eliminated from routine follow-up or a major risk factor to be therapeutic target. With a review of experimental and epidemiologic data, the presence of molecular switch to regulate the role of uric acid as anti- or pro-oxidant in different compartment of our body is suggested, which may shed light on understanding the paradoxical role of uric acid and solving the "uric acid debate".

Finite element method based numerical simulations are performed to identify low-velocity impact-induced asymmetrically-located delamination in the [0/903]S and [0/90]2S composite plates, respectively, using a fundamental symmetric guided wave mode (S0). The wave attenuation effect due to the viscoelasticity of the composite material is modeled by calculating the Lamb wave attenuation constants and using the Rayleigh proportional damping model. The estimated sizes and locations of the delamination in both plates were in good agreement with the experimental measurements. Moreover, the analysis of wave structure of the impacted plates shows that when the S0 mode propagates through the damaged region, the delamination mouth opens up due to the presence of standing waves, which are generated as a consequence of multiple reflections of trapped waves with the delamination boundaries.

An experimental study describing the non-contact measurement of the coefficient of thermal expansion of an aluminum (Al-6061-T6) specimen with two fiber Bragg grating sensors using a pair of C-lens collimators was carried out. The collimators were used for the freespace coupling between the fiber Bragg sensors and the optical sensing interrogator. During the experiment, the wavelength distortion of the optical signals was observed. Consequently, the measured thermal strains were corrected using an estimated collimator correction factor of 0.8466. The coefficient of thermal expansion of the specimen was then calculated to be (22.0 ± 0.1)×10−6°C−1 for every 5°C step in the range 35°C∼75°C, which was in good agreement with the typical value of 23.6×10−6°C−1 for aluminum.

In this paper, the strength of braided textile composites is predicted using a multi-scale approach bridging the mesoscale and microscale regimes. Mesoscale finite element models of representative unit cells of biaxial and triaxial braided composites are developed for predicting strength. The constituent stresses of tows inside the braided unit cell are calculated using micromechanics. Correlations between mesoscale stresses and microscale constituent stresses are established by using stress amplification factors. After calculating microscale stresses, a micromechanics-based progressive damage model is employed to determine the damage statuses of braided composites. A volume-averaging homogenization method is utilized to eliminate damage localization in the matrix of tows, and a parametric study is performed to evaluate the effects of damage homogenization. Subsequently, the ultimate strength is predicted for braided composites in which the braiding angle ranges from 15° to 75°. The prediction results are compared with the experimental values, and good agreement is observed.

A composite hub was successfully designed and fabricated for a flywheel rotor of 51 kWh energy storage capacities. To be compatible with a rotor, designed to expand by 1% hoop strain at a maximum rotational speed of 15,000 rpm, the hub was flexible enough in the radial direction to deform together with the inner rotor surface. This hub is also stiff in the conical deformation mode to increase the vibration frequency for high rotational speed. A dome type hub of carbon-glass/epoxy has been developed to be press-fitted into the rotor with interference in order to offset the hoop strain. A series of parametric study were sequentially performed to determine fiber fractions, layer thickness, winding angles, interference, and the shape of the geodesic dome contour. A safety factor of two was secured in the final design to take into consideration a long term fatigue life of the hub. The hub was fabricated by wet filament windingprocess, followed by press-fitting into a surrogated rotor, which has the same inner and outer diameters and stress states as those of original rotor except height. The strains were measured during the press-fit and found to be in agreement with the stress analysis results.

A forced vibration model of a rail system was established using the Timoshenko beam theory to determine the dynamic response of a rail under time-varying load considering the damping effect and stiffness of the elastic foundation. By using a Fourier series and a numerical method, the critical velocity and dynamic response of the rail were obtained. The forced vibration model was verified by using FEM and Euler beam theory. The permanent deformation of the rail was predicted based on the forced vibration model. The permanent deformation and wear were observed through the experiment. Parametric studies were then conducted to investigate the effect of five design factors, i.e., rail cross-section shape, rail material density, rail material stiffness, containment stiffness, and damping coefficient between rail and containment, on four performance indices of the rail, i.e., critical velocity, maximum deflection, maximum longitudinal stress, and maximum shear stress.

Potassium is abundant in the ICF compartment in the body and its excretion primarily depends on renal (about 90%), and to a lesser extent (about 10%) on colonic excretion. Total body potassium approximated to 50mmol/kg body weight and 2% of total body potassium is in the ECF compartment and 98% of it in the intracellular compartment.Dyskalemia is a frequent electrolyte imbalance observed among the maintenance hemodialysis patients. In case of hyperkalemia, it is frequently "a silent and a potential life threatening electrolyte imbalance" among patients with ESRD under maintenance hemodialysis. The prevalence of hyperkalemia in maintenance HD patients was reported to be about 8.7-10%. Mortality related to the hyperkalemia has been shown to be about 3.1/1,000 patient-years and about 24% of patients with HD required emergency hemodialysis due to severe hyperkalemia. In contrast to the hyperkalemia, much less attention has been paid to the hypokalemia in hemodialysis patients because of the low prevalence under maintenance hemodialysis patients. Severe hypokalemia in the hemodialysis patients usually was resulted from low potassium intake (malnutrition), chronic diarrhea, mineralocorticoid use, and imprudent use of K-exchange resins. Recently, the numbers of the new patients with advanced chronic kidney disease undergoing maintenance hemodialysis are tremendously increasing worldwide. However, the life expectancy of these patients is still much lower than that of the general population. The causes of excess mortality in these patients seem to various, but dyskalemia is a common cause among the patients with ESRD undergoing hemodialysis.

Supplemental Digital Content is available in the text, Glycated albumin (GA) exhibits atherogenic effects and increased serum GA levels are associated with the development of cardiovascular complications in diabetic patients. GA production also increases with aging, oxidative stress, and renal dysfunction. We performed this study to further ascertain the association between GA and arterial stiffness in nondiabetic chronic kidney disease (CKD) patients. We enrolled 129 nondiabetic CKD patients. Arterial stiffness was measured by brachial-ankle pulse wave velocity (baPWV) using a volume plethysmographic instrument along with simultaneous measurements of GA. Insulin resistance was determined with the homeostatic model assessment. The estimated glomerular filtration rate was calculated using serum creatinine and cystatin C according to the CKD-EPI Creatinine-Cystatin C equation adjusted for age, sex, and race (eGFRcr-cys). Nondiabetic CKD patients with arterial stiffness (baPWV ≥1400 cm/s) showed higher GA levels than those without arterial stiffness (14.2 [8.7–20.2]% vs 13.0 [8.8–18.9]%, P = 0.004). In the subgroup analysis, the patients who had both a higher GA level and a lower eGFRcr-cys, showed the highest baPWV compared with patients with a higher GA or a lower GFR alone. By Spearman's correlation analysis, GA correlated significantly with baPWV (r = +0.291, P = 0.001) and fasting serum glucose level (r = +0.191, P = 0.030), whereas The homeostatic model assessment of insulin resistance did not show any significant correlation with baPWV. Systolic blood pressure (r = +0.401 P

OBJECTIVE Hemodialysis patients may have psychological distress and reduced quality of life (QoL) related to chronic physical health problems. Genetic polymorphisms associated with reduced QoL in hemodialysis patients. The aim of this study was to investigate the relationship between genetic polymorphisms and variation in health-related QoL in Korean hemodialysis patients. METHODS The 36-item Short-Form Health Survey and the Korean Hospital Anxiety and Depression Scale were used to assess health-related QoL and psychological distress, respectively. Twenty hundred and five clinically stable patients from 6 hemodialysis centers have participated with informed consents. Sociodemographic factors, clinical factors, and genotypes of serotonin 1A receptor, brain-derived neurotrophic factors, and glucocorticoid receptor were assessed. Independent t-tests, correlation analyses, multiple regression analyses were performed for statistical analyses. RESULTS The serotonin 1A receptor CC genotype group showed significantly higher physical and mental QoL levels than those with the GG/GC genotypes. In the final linear regression analysis, serotonin 1A receptor CC genotype was significantly associated with positive physical and mental QoL levels. CONCLUSION ConclusionaaSerotonin 1A receptor polymorphism, as well as age and depression, were significantly associated with mental and physical QoL in hemodialysis patients. Functional activity in the serotonin receptor system may have a modulating effect on health-related QoL in hemodialysis patients.