Specific Strength Research Articles

Sex/gender differences in general cognitive abilities: an investigation using the Leiter-3.

Research has shown that differences between males and females are not in general intelligence, but only in some specific factors and tasks. We used the Italian standardization of the Leiter-3, which is a completely nonverbal cognitive battery, to investigate the nature of sex/gender (we used sex/gender to reflect the awareness that the effects of biological 'sex' and socially constructed 'gender' cannot be easily separated and that most individuals' identities are informed by both sex and gender) differences. In doing so we used a multigroup confirmatory factor analysis approach. Results confirmed that males and females perform similarly in general intelligence, but present with some specificities. Males perform better on some, but not all, tasks requiring the spatial manipulation of the stimuli, but females consistently outperform males in tasks such as the nonverbal Stroop, requiring inhibition and attention control to a larger extent. The clinical and practical implications of our findings are considerable. The identification of specific cognitive strengths and weaknesses in males and females underscores the importance of tailored approaches in clinical assessments and interventions.

An integrated experimental and analytical approach on mechanical characterization of advanced powder metallurgy aluminium metal matrix composites reinforced with different particulates

Abstract Over the last few decades, “Discontinuously Reinforced Particulate Composites (DRPCs)” are a popular class of composite materials with considerable challenge in processing, characterization and machinability because of their increased strength-weight ratio, stiffness, specific strength and oxidization when compared to various metals and their alloys. This paper discusses experimental and numerical investigation on mechanical characteristics of aluminum metal matrix reinforced with various reinforcement particulates such as silicon carbide, aluminium oxide, and zirconium oxide, compaction pressure (kN) and hold time (s) based on Design of Experiments (DOE) and Finite Element Analysis. Initially this paper discusses the process optimization of Aluminum Matrix reinforced with different particulates experimentally to identify the favourable processing conditions by varying reinforcement materials, compaction pressure (kN) and hold time (s) based on TDOE (Taguchi’s Design of Experiments). Further, this paper concentrates to determine “maximum principal stress, equivalent elastic strain and equivalent (von-mises) stress” based on Finite Element Analysis (ANSYS Workbench-2023R1). The results of the experimentation showed that the highest hardness values were achieved with ZrO2 reinforcement material. Increasing the compaction pressure from 8 to 12 kN resulted in a slight decrease in surface roughness and porosity. Higher compaction pressures have assumed to facilitate better particle distribution and improved interfacial bonding, leading to smoother surfaces and lower void content. The simulation results showed that the maximum principal stress achieved were (2235.8 Mpa) SiC, (3444.4 Mpa) Al2O3, and (3582.5 MPa) ZrO2. The equivalent elastic strain achieved was (0.2488) SiC, (0.2421) Al2O3 and (0.262) ZrO2. The equivalent (Von Mises) stress achieved was (28751 MPa) for SiC, (24880 MPa) for ZrO2 and (26972 Mpa) for Al2O3. This experimentation and simulation demonstrated that the PM process can be used to fabricate DRAMMC with different reinforcement particulates.

An experimental and numerical investigation into compressive failure of pyramidal lattice sandwich structures fabricated using stereolithography technology

AbstractThe pyramid lattice sandwich structure, characterized by high load‐bearing capacity, lightweight nature, and fully open internal space, is considered an extremely promising super‐strong structure. Stereolithography technology was utilized to achieve the monolithic formation of single‐layer multi‐cell pyramidal lattice sandwich structures. Quasi‐static compression tests and finite element simulations were conducted to characterize the compressive properties and failure modes. Results indicate that the compressive strength, compressive modulus, specific strength, and specific stiffness of the single‐layer multi‐cell pyramidal lattice sandwich structure increase as the relative density increases. Moreover, fracture failure was observed in the structures with various relative densities. Additionally, the compressive failure of multi‐layer density gradient pyramidal lattice sandwich structures was investigated. Experimental and numerical findings indicate that the optimal density gradient scheme for the ZCMLG structure is I‐III‐II, resulting in a peak compression force that is 342.14% and 288.55% higher than that of the ZAMLG and ZBMLG structures, respectively.

Frailty and depressive symptoms in older kidney transplant recipients: opportunities for collaboration between transplant nephrologists and geriatricians

BackgroundFrailty is one of the key syndromes in geriatric medicine and an important factor for post-transplant outcomes. We aimed to describe the prevalence of frailty and examine the correlates of frailty and depressive symptoms in older kidney transplant recipients (KTRs).MethodsThis cross-sectional study involved 112 kidney transplant recipients (KTRs) aged 70 and above. Frailty syndrome was assessed using the Fried frailty criteria, and patients were categorized as frail, pre-frail, or non-frail based on five frailty components: muscle weakness, slow walking speed, low physical activity, self-reported exhaustion, and unintentional weight loss. Depressive symptoms were measured using the 15-item Geriatric Depression Scale (GDS). The relationship between frailty and depressive symptoms was evaluated using multinomial logistic regression, with the three frailty categories as the dependent variable and the severity of depressive symptoms as the independent variable, while controlling for age, gender, renal graft function, and time since transplant surgery.ResultsThe participants had a mean age of 73.3 ± 3.3 years, and 49% were female. The prevalence of frailty syndrome was 25% (n = 28), pre-frailty was 46% (n = 52), and 29% (n = 32) of the KTRs were non-frail. The mean score for depressive symptoms was 3.1 ± 2.4 points, with 18% scoring above the clinical depression cutoff. Depressive symptoms were positively correlated with frailty (r = .46, p < .001). Among the frailty components, self-reported exhaustion (r = .43, p < .001), slow walking speed (r = .26, p < .01), and low physical activity (r = .44, p < .001) were significantly positively correlated with depressive symptoms, while muscle strength (p = .068) and unintentional weight loss (p = .050) were not. A multinomial logistic regression adjusted for covariates indicated that, compared to being non-frail, each additional point on the GDS increased the odds of being pre-frail by 39% (odds ratio [OR] = 1.39, 95% confidence interval [CI] 1.01–1.96) and roughly doubled the odds of being frail (OR = 2.01, 95% CI 1.39–2.89).ConclusionThere is a strong association between frailty and depression in KTRs aged 70 years and older. Targeted detection has opened up a new avenue for collaboration between geriatricians and transplant nephrologists.

Thermal‐mechanical properties of bamboo charcoal/recycled low‐density polyethylene composites

AbstractBamboo fiber has garnered considerable attention owing to its high specific strength and renewability. However, the hydrophilic nature of the material must be carefully managed to create a bamboo composite with usable thermal‐mechanical properties. Herein, the NaOH‐treated bamboo fiber (particle size ≤200 μm) was used to produce bamboo charcoal (BC). Then, recycled low‐density polyethylene containing BC composites was fabricated by varying the BC composition (between 2 and 8 wt%). Effects of different BC wt% in the BC/recycled low‐density polyethylene composites (denoted as xBCPE, where x indicates BC wt% in the composites) were analyzed for tensile strength, morphology, and thermal properties. In addition, the water absorption capacities of the BCPE composites were compared. These xBCPE composites showed excellent thermal stability and low water absorption properties. Therefore, they are potential candidate materials for electrical device packaging with partial degradability.Highlights Bamboo charcoal (BC) was prepared via low‐temperature pyrolysis of alkaline‐treated bamboo fiber. BC displayed strong interfacial interaction with recycled low‐density polyethylene. Proportion of BC on the composite properties was investigated and furnished. The xBCPE composites demonstrate low water absorption and excellent thermal stability. The reinforced composite (4BCPE) shows great promise as a functional material.

Effects of the Mesoporous Filler and Oleophilic Property on the Tribological Behavior of Polyetheretherketone Composites.

Porous composites, such as polyimide and polyetheretherketone (PEEK) polymer composites, became more attractive as a result of excellent specific strength, lightweightness, and smart lubrication. However, revealing the influence of a porous filler on the friction behaviors of polymer composites remains a challenge. The current work examines the effects of the pore structure and wettability on the mechanical and tribological performances of polymer composites reinforced with fillers. Three kinds of particles (non-porous, porous, and oleophobic porous) act as fillers within PEEK, respectively. It was identified that adding porous zeolite particles into PEEK slightly decreased the mechanical property. The zeolite particles significantly increased the oil adsorption of the composite, leading to a significant increase in the friction coefficient at 10 wt % content. However, the friction coefficient of the PEEK composite filled with 20 wt % modified zeolite was relatively low as a result of the weak adsorption. The interface analyses indicated that the thickness of the oil film was controlled via porous structures, changing the lubrication regime of the tribopair. The reason is the appropriate adsorption of oil and the release of zeolite from the composites during the friction process. These results can offer technical guidance to control the friction behaviors of composites under oil-lubricating conditions by a porous particle and pore modification.

An MCDA composite index of bank stability using CAMELS ratios and shannon entropy

AbstractThis study uses the multi-criteria decision-analysis (MCDA) approach to construct a composite performance index (CPI) directly from the CAMELS financial ratios. The CPI has several promising characteristics, such as (i) being an absolute measure of performance that allows for adding or removing data without affecting the existing scores; (ii) employing CAMELS ratios directly in its calculation without the need for normalization or imputation of positive values; (iii) employing the dynamic weighting system of data envelopment analysis (DEA); (iv) providing more robust insights on the Vietnamese banking system under the Shannon entropy approach; and (v) can be an alternative measure of bank stability, compared to the CAMELS ratings and z-scores. Based on a rich dataset of 45 Vietnamese banks spanning from 2002 to 2020, our findings suggest that the proposed CPI could offer an overall view consistent with other approaches for measuring banking sector performance and stability and identifying specific strengths and weaknesses of banks.

A Comprehensive Review on Advanced Control Methods for Floating Offshore Wind Turbine Systems above the Rated Wind Speed

This paper presents a comprehensive review of advanced control methods specifically designed for floating offshore wind turbines (FOWTs) above the rated wind speed. Focusing on primary control objectives, including power regulation at rated values, platform pitch mitigation, and structural load reduction, this paper begins by outlining the requirements and challenges inherent in FOWT control systems. It delves into the fundamental aspects of the FOWT system control framework, thereby highlighting challenges, control objectives, and conventional methods derived from bottom-fixed wind turbines. Our review then categorizes advanced control methods above the rated wind speed into three distinct approaches: model-based control, data-driven model-based control, and data-driven model-free control. Each approach is examined in terms of its specific strengths and weaknesses in practical application. The insights provided in this review contribute to a deeper understanding of the dynamic landscape of control strategies for FOWTs, thus offering guidance for researchers and practitioners in the field.

Mechanical Properties of Selective Laser Melting‐Processed Multihierarchical Lattice Structure Based on Body‐Centered‐Cubic Unit Cell

Herein, three types of multihierarchical lattice structures (MHLSs) with different configurations are designed based on the body‐centered‐cubic (BCC) unit cell. The designed lattice structures are fabricated using Ti‐6Al‐4 V powder as feedstock material through selective laser melting (SLM) technology. The microstructure and surface morphology of the SLM‐formed samples are observed by optical microscopy and scanning electron microscopy, respectively. Theoretical calculation and quasistatic compression experiment are carried out to investigate their mechanical properties. The result shows that the size error of slave cell with small strut diameters is greater than that of master cell with larger strut diameters. All MHLSs exhibit superior mechanical properties compared to the BCC lattice structure. Moreover, the specific elastic modulus and specific yield strength of MHLSs with the best mechanical properties are 70.1% and 51.0% higher than that of BCC lattice structure, respectively. Meanwhile, theoretical calculation results of the elastic modulus and yield strength are consistent with the results of quasi‐static compression testing. The fracture morphology analysis indicates that the struts of the MHLSs samples exhibit a mixed brittle–plastic fracture mode, while the nodes exhibit a plastic fracture mode.

Minimal-noise estimation of noncommuting rotations of a spin

We propose an analogue of SU(1,1) interferometry to measure rotation of a spin by using two-spin squeezed states. Attainability of the Heisenberg limit for the estimation of the rotation angle is demonstrated for maximal squeezing. For a specific direction and strength an advantage in sensitivity for all equatorial rotation axes (and hence non-commuting rotations) over the classical bound is shown in terms of quadratic scaling of the single-parameter quantum Fisher information for the corresponding rotation angles. Our results provide a method for measuring magnetic fields in any direction in the x-y-plane with the same optimized initial state.

THE EFFECT OF LASER OSCILLATING WELDING ON FORMATION AND PROPERTIES OF TITANIUM ALLOY

Titanium alloys are widely used in aerospace and other fields due to their advantages of low density, high specific strength and good corrosion resistance. Laser oscillating welding is an innovative process in the realm of welding technology. In this study, two laser oscillating welding methods (circular and linear) were employed to analyze the influence of different oscillation parameters on the formation of titanium alloy. The results indicate that the oscillation frequency has a significant impact on weld formation. The laser scanning trajectory also affects weld formation, with circular and linear scanning trajectories resulting in better weld quality. Finally, the effects of oscillation modes on the microstructure and properties of laser oscillating welding titanium alloy were investigated based on optimized process parameters. Among them, circular laser oscillating welding of titanium alloy exhibits higher tensile strength, with a maximum tensile strength of up to 1188.3[Formula: see text]MPa.

Shape recovery and energy absorption properties of 3D printed continuous ramie fiber reinforced thin‐walled biocomposite structures

AbstractContinuous fiber reinforced composites are widely used in thin‐walled structures due to their high specific strength and stiffness. In this work, continuous natural fiber was introduced into thin‐walled biocomposite structures via 3D printing technique to enhance energy absorbing properties and promote ecological compatibility. The effects of varying configurations of printing speed, layer thickness, and path optimization on the deposition quality of continuous ramie fiber and polylactic acid matrix were explored. The results showed that reduced printing speed (100 mm/min) and optimal layer thickness (0.25 mm) effectively minimized structural forming defects. In addition, further enhancements in the printing quality could be achieved by smoothing the path with rounded corners. Based on optimal printing strategies, different configurations of thin‐walled biocomposite structures were fabricated. Lateral monotonic and cyclic load tests were performed to investigate their energy absorption and shape recovery capacities. When the loading displacement was 10 mm (strain was 20%), the circular structure presented good shape recovery capability, with measured recovery ratio remaining above 89%. The hexagonal structure showed a similar variation in shape recovery ratio as the quadrangular structure, both remaining above 75%. Moreover, the specific energy absorption of all the structures converged after two cycles, indicating their remarkable and stable repeatable load‐bearing capacity.Highlights Continuous ramie fiber reinforced thin‐walled structures were prepared. The deformation patterns of structures under lateral compression were analyzed. Energy absorption and shape recovery radio were studied under cycle loading. Printed structures exhibited great and stable repeatable load‐bearing capacity.

A review of the application of FRP materials in Asia-Pacific region

FRP (Fiber Reinforced Polymers) materials are being increasingly used in various engineering fields due to their high specific strength, designability and durability. Having been rapidly developing in recent years, the Asia-Pacific region is also equipped with a continuously expanding demand for the research and application of FRP materials. This paper summarizes the application of FRP materials in the Asia-Pacific region through literature and case analysis. Some of the current issues existing in the procedure of FPR materials application are discussed, and predictions on the development and application prospects of this kind of materials in the Asia-Pacific region are also briefly suggested. It is found that FRP materials have been widely utilized in various fields including concrete structures reinforcement, bridge engineering construction and new energy facilities in the Asia-Pacific region, where is equipped with a relatively broad and promising market. Meanwhile, the shortcomings relevant to this kind of materials in several aspects, such as expensive unit prices and imperfect technical specification systems, also restricted the application of FRP materials in this region.

Influence of density and chemical additives on paper mechanical properties

AbstractIn this work we have investigated the effect of surface modification of fibres on the overall mechanical properties of high-density papers. Paper sheets were prepared by a combination of heat-pressing and polyelectrolyte Layer-by-Layer (LbL) modification of different softwood fibres. LbLs of Polyallylamine Hydrochloride (PAH) and Hyaluronic Acid (HA) were adsorbed onto unbleached kraft fibres and bleached Chemo-ThermoMechanical Pulp (CTMP) to improve the strength of the fibre–fibre joints in papers made from these fibres. Additionally, different sheet-making procedures were used to prepare a range of network densities with different degrees of fibre–fibre interaction in the system. The results demonstrate that interfacial adhesion within fibre–fibre joints plays a pivotal role in the network's performance, even at higher paper densities. Hygroexpansion measurements and fracture zone imaging with Scanning Electron Microscopy (SEM) further support the claim that stronger interactions between the fibres allow for a better utilisation of the inherent fibre properties. Surface treatments and network densification significantly improved the paper sheets' mechanical properties. Specifically, LbL-treatments alone increased specific stiffness up to 60% and specific strength by over 100%. This improvement is linked to the build-up of residual stresses during drying. Due to a high interaction between the fibres during water removal the fibres become constrained, leading to increased stretching of fibre segments. Strengthened fibre joints intensify this constraint, further increasing the stretch and, consequently, the paper's strength.

Encouraging Invasive Acacia Control Strategies by Repurposing Their Wood Biomass Waste for Pulp and Paper Production

Concerns on the expanding infestation of several Acacia species in the southern Mediterranean European countries have triggered an ever-growing requirement for costly targeted control actions. Valorizing biomass waste produced could help promote and better finance these actions. For that purpose, wood wastes from invasive control actions were tested regarding their pulp and paper potential, aiming to entice cellulose industries to partake in future conservation actions. Wood waste from the five most pervasive Acacia species was studied (Acacia dealbata Link, Acacia longifolia Willd, Acacia mearnsii De Wild, Acacia melanoxylon R.Br, and Acacia saligna Labill) regarding physical and chemical characteristics, and a central composite design was used to optimize alkali charge and reaction temperature on pulping yield and delignification. Bleached kraft pulps were produced with each species’ optimized conditions and for an equitable mixture of all species. Optimized pulp yields (52.6%–53.5%) and pulp polymerization degree (2867–3690) of Acacia species were higher than those of Eucalyptus globulus Labill (used as reference). Optimized bleached pulps were refined and fiber, pulp, and handsheet properties determined. Acacia dealbata and A. longifolia presented high specific wood consumption and lower handsheet strength properties, pointing to overall lower pulping potential, while A. melanoxylon and A. mearnsii characteristics were equal to or higher than those of E. globulus. A. saligna pulp and handsheet characteristics appear more suited for tissue paper. The Acacia mixture achieved acceptable characteristics, enabling the indiscriminate use of Acacia wood regardless of the species. As a shortcoming, the Acacia pulps showed the worst optical characteristics, with brightness dropping substantially with beating (64%–76%) when compared to E. globulus (81%).

Design, Manufacturing, and Analysis of Periodic Three-Dimensional Cellular Materials for Energy Absorption Applications: A Critical Review

Cellular materials offer industries the ability to close gaps in the material selection design space with properties not otherwise achievable by bulk, monolithic counterparts. Their superior specific strength, stiffness, and energy absorption, as well as their multi-functionality, makes them desirable for a wide range of applications. The objective of this paper is to compile and present a review of the open literature focusing on the energy absorption of periodic three-dimensional cellular materials. The review begins with the methodical cataloging of qualitative and quantitative elements from 100 papers in the available literature and then provides readers with a thorough overview of the state of this research field, discussing areas such as parent material(s), manufacturing methods, cell topologies, cross-section shapes for truss topologies, analysis methods, loading types, and test strain rates. Based on these collected data, areas of great and limited research are identified and future avenues of interest are suggested for the continued maturation and growth of this field, such as the development of a consistent naming and classification system for topologies; the creation of test standards considering additive manufacturing processes; further investigation of non-uniform and non-cylindrical struts on the performance of truss lattices; and further investigation into the performance of lattice materials under the impact of non-flat surfaces and projectiles. Finally, the numerical energy absorption (by mass and by volume) data of 76 papers are presented across multiple property selection charts, highlighting various materials, manufacturing methods, and topology groups. While there are noticeable differences at certain densities, the graphs show that the categorical differences within those groups have large overlap in terms of energy absorption performance and can be referenced to identify areas for further investigation and to help in the preliminary design process by researchers and industry professionals alike.

Highly stretchable alginate/methylcellulose hydrogels for 3D bio-printing: photopolymerization approach enhancing structural integrity

In recent years, 3D hydrogels based on alginate (Alg) have undergone substantial advancements, holding transformative potential for biomedicine and regenerative medicine. Nevertheless, the viscosity of Alg needs to be further increased, in order to print complex 3D structures. Attempts to adjust printability often employ rheological modifiers like methylcellulose (MC), but these still lack mechanical integrity for broader biomedical applications. Our study sought to chemically modify Alg/MC to create a photopolymerizable hydrogel by incorporating acrylate-based monomers, which would enhance the curing ability of the base hydrogel, leading to better mechanical properties of Alg/MC, such as stretchability and stability with shape recovery. Comprehensive mechanical assessments unveiled remarkable tensile properties, achieving a notable specific strength benchmark of 44.72 kPa/(g.cm-3) before reaching the point of fracture. This represents a substantial 250 % improvement compared to samples lacking the acrylate monomer. Biomedical assessments confirmed the hydrogel's promising potential, especially with the MG-63 cell line, underscoring its suitability for advanced applications like tissue engineering.

Feasibility Study of Single-Point Incremental Forming for Discontinuous-Fiber CFRP Using Oil-Bath Heating

Although, three-dimensional printing has several advantages, however there are currently many limitations. In particular, printed products using composite materials such as fiber-reinforced plastic have yet to achieve the same mechanical properties as those obtained from conventional manufacturing methods. In addition, fabricating thin plates or thin shell shapes with sufficient strength is challenging. Incremental forming enables high-mix, low-volume production of thin sheets. This method applies incremental deformation to thin sheets, the desired shape is obtained by accumulating the deformation, and no dies are required. Carbon-fiber-reinforced plastic (CFRP) materials have high specific strength. Discontinuous-fiber CFRP is capable of large plastic deformation under appropriate conditions due to the discontinuity of the reinforcement, and its mechanical properties are nearly isotropic due to the random fiber arrangement. The authors focused on this property and studied the application of single-point incremental forming to discontinuous carbon-fiber-reinforced polyamides. In this study, the workpiece was formed by heating it locally to a deformable temperature by the frictional heat between the rotating tool and the workpiece. The forming experiment was also conducted in an oil bath to keep the entire material at a suitable forming temperature. The results showed that the spindle speed affected forming results even in an oil bath and that heating using an oil bath suppressed deviations from the sine law for thickness and wall angle due to elastic deformation.

Evaluation of precipitation extremes in ERA5 reanalysis driven regional climate simulations over the CORDEX-Australasia domain

Reanalysis-driven regional climate simulations using the Weather Research and Forecasting (WRF) model in New South Wales (NSW) and Australian Regional Climate Modelling (NARCliM) Version 2.0 are assessed for capturing precipitation extreme indices. Seven configurations of the WRF model driven by ECMWF (European Centre for Medium-Range Weather Forecasts) Reanalysis v5 (ERA5) for Australia from 1979 to 2020 at 20 km resolution are evaluated. We assess the spatiotemporal patterns of six selected Expert Team on Sector-Specific Climate Indices (ET-SCI) precipitation extremes by comparing regional climate model (RCM) simulations against gridded observations. The RCMs evaluated have varying levels of accuracy in simulating precipitation extremes. While they capture climatology and coefficient of variation of precipitation extremes relatively well, temporal correlation and trend reproduction present challenges. Some RCMs perform more effectively for specific extreme indices, while others encounter challenges in accurately replicating them. No single RCM excels in all aspects, highlighting the need to consider specific strengths when selecting RCMs for global climate model (GCM) driven simulations.

On the influence of iron and silicon content on the phase composition of the Al-Fe-Si system

Increasing interest in intermetallic phases of the Al-Fe-Si system is associated with their high specific strength, corrosion and wear resistance, as well as the low cost of their production. To exhibit the most successful combination of properties, it is necessary to impart a specific compact morphology to the precipitated intermetallic phases. It is important to create an alloy with a composition capable of accepting plastic deformation. The purpose of the work is to develop the composition of an Al-Fe-Si system alloy capable of withstanding plastic deformation and determining the corresponding deformation interval. Based on computer modeling, an alloy composition capable of accepting plastic deformation was developed and the corresponding deformation interval was determined. The simulation was carried out in the ThermoCalc software package, TCAL8 database. It has been revealed that alloys with a high content of both silicon and iron are not characterized by the formation of a single-phase region, however, with a certain combination of alloy components, it is possible to achieve a quasi-single-phase structure, when the content of one phase is observed to be more than 90%. The solidus temperatures for different alloy compositions and the boundary conditions for the existence of phases have been determined. The α phase is present in the system from a temperature of 770°C up to a temperature of 446°C. In composition, it is found in the range from 5 to 35% iron with an amount of silicon of 10% and from 0 to 15% silicon with an iron content of 30%. The maximum amount of α phase was obtained for the Al60-65 alloy; Fe30-32; and Si5-10%, deformation temperature range is 600-450°C. Deformation in this region will ensure processing in a quasi-single-phase region without melting.