Search Results (128)

Isothermal hot compression tests were performed on an Al-4.8Cu-0.25Mg-0.32Mn-0.17Si alloy using a Gleeble-3500 thermomechanical simulator within the temperature range of 350–510 °C and strain rate range of 0.001–10 s⁻¹, achieving a true strain of 0.9. The constitutive equation and hot processing maps were established to predict the flow behavior of the alloy. The hot deformation mechanisms were investigated through microstructural characterization using inverse pole figure (IPF), grain boundary (GB), and grain orientation spread (GOS) analysis. The results demonstrate that both dynamic recovery (DRV) and dynamic recrystallization (DRX) occur during hot deformation. At high lnZ values (high strain rates and low deformation temperatures), discontinuous dynamic recrystallization (DDRX) dominates. Under middle lnZ conditions (low strain rate or high deformation temperature), both continuous dynamic recrystallization (CDRX) and DDRX are the primary mechanisms. Conversely, at low lnZ values (low strain rates and high temperatures), CDRX and geometric dynamic recrystallization (GDRX) become predominant. The DRX process in the Al-Cu-Mg alloy is controlled by the deformation temperature and strain rate. Full article

The current study explores the applicability of a single constitutive equation, based on the Arrhenius hyperbolic sine model, to a wide range of chemical compositions and test conditions by using a unique approximation. To address this challenge, a mixed model is proposed, integrating a physical model with phenomenological expressions to capture the strain and strain rate hardening, forming temperature, dynamic recovery (DRV) and dynamic recrystallization (DRX). The investigation combines high-temperature mechanical testing with modeling in order to understand the hot deformation mechanisms. Hot torsion tests were conducted on ten different low-carbon steels with distinct microalloying additions to capture their responses under diverse initial austenite grain sizes, deformation temperatures and strain rate conditions (d₀ = 22–850 µm, T = 800–1200 °C and $\dot{\epsilon }$= 0.1–10 s⁻¹). The developed constitutive equation has resulted in a robust expression that effectively simulates the hot behavior of various alloys across a wide range of conditions. The application of an optimization tool has significantly reduced the need for adjustments across different alloys, temperatures and strain rates, showcasing its versatility and effectiveness in predicting the flow behavior in a variety of scenarios with excellent accuracy. Moreover, the model has been validated with experimental torsion data from the literature, enhancing the applicability of the developed expression to a broader spectrum of chemical compositions. Full article

The thermal deformation behaviour of a spray-formed 7055 as-forged aluminium alloy was studied using isothermal hot-press tests under different deformation conditions (strain rates of 0.01, 0.1, 1, and 10 s⁻¹, temperatures of 340, 370, 400, 430, and 460 °C). An Arrhenius constitutive model was developed using flow stress data corrected for friction and temperature, yielding a correlation coefficient (R) of 0.9877, an average absolute relative error (AARE) of 4.491%, and a deformation activation energy (Q) of 117.853 kJ/mol. Processing maps integrating instability criteria and power dissipation efficiency identified appropriate processing parameters at 400–460 °C/0.08–0.37 s⁻¹. Furthermore, this study investigated how strain rate and temperature influence microstructural evolution. Microstructural characterization revealed that both dynamic recovery (DRV) and dynamic recrystallization (DRX) occur simultaneously during thermal deformation. At low temperatures (≤400 °C), DRV and continuous dynamic recrystallization (CDRX) dominated; at 430 °C, deformation microstructures and recrystallized grains coexisted, whereas abnormal grain growth prevailed at 460 °C. The prevailing mechanism of dynamic softening was influenced by the applied strain rate. At lower strain rates (≤0.1 s⁻¹), discontinuous dynamic recrystallization (DDRX) was the primary mechanism, whereas CDRX became dominant at higher strain rates (≥1 s⁻¹), and dislocation density gradients developed within adiabatic shear bands at 10 s⁻¹. Full article

Background: Data on the use of dolutegravir (DTG) plus boosted darunavir (DRV/b) in people with 4-class drug-resistant HIV (4DR-PWH) are limited. This study assessed the virological effectiveness of DTG + DRV/b in this population using real-world data from the PRESTIGIO Registry. Methods: We compared three regimen groups: dual DTG + DRV/b (DODA), DTG + DRV/b plus an additional antiretroviral drug (DODA + Other), and regimens excluding DTG + DRV/b (NO-DODA). Virological failure (VF) was defined as ≥2 HIV-RNA values ≥ 50 copies/mL or 1 ≥ 1000 copies/mL. Mixed-effects logistic regression was used to assess VF, adjusting for antiretroviral therapy (ART) duration, age, number of fully active drugs, sex at birth, and nadir CD4+. Individuals could switch regimens during follow-up. Results: Among 249 4DR-PWH (median follow-up: 8.7 years), 844 ART regimens were analyzed: 72 (8.5%) DODA, 264 (31.3%) DODA + Other, and 508 (60.2%) NO-DODA. Compared to NO-DODA, the odds of VF were 77% and 35.9% lower with DODA and DODA + Other, respectively. Notably, in the DODA group, DTG and DRV/b were fully active in only 63.9% and 47.2% of the cases, respectively. Conclusions: DTG + DRV/b regimens were associated with a significantly lower risk of virological failure, even when drug activity was partial. This strategy remains a valuable option for managing multi-drug-resistant HIV. Full article

This study investigates the hot deformation behaviour and microstructural evolution of two AISI 430 ferritic stainless steel variants: 0A (basic) and 1C (modified). These variants primarily differ in chemical composition, with 0A containing higher austenite-stabilizing elements (C, N) compared to 1C, which features lower interstitial content and slightly higher Si and Cr. This research aimed to optimize hot rolling conditions for enhanced forming properties. Uniaxial hot compression tests were conducted using a Gleeble thermo-mechanical system between 850 and 990 °C at a strain rate of 3.3 s⁻¹, simulating industrial finishing mill conditions. Analysis of flow curves, coupled with detailed microstructural characterization using electron backscatter diffraction, revealed distinct dynamic restoration mechanisms influencing each material’s response. Thermodynamic simulations confirmed significant austenite formation in both materials within the tested temperature range, notably affecting their deformation behaviour despite their initial ferritic state. Material 0A consistently exhibited a strong tendency towards dynamic recrystallization (DRX) across a wider temperature range, particularly at 850 °C. DRX led to a microstructure with a high concentration of low-angle grain boundaries and sharp deformation textures, actively reorienting grains towards energetically favourable configurations. However, under this condition, DRX did not fully complete the recrystallization process. In contrast, material 1C showed greater activity of both dynamic recovery and DRX, leading to a much more advanced state of grain refinement and recrystallization compared to 0A. This indicates that the composition of 1C helps mitigate the strong influence of the deformation temperature on the crystallographic texture, leading to a weaker texture overall than 0A. Full article

This study investigates the hot deformation behaviour and flow stress prediction of metastable β-Ti-15Mo alloy, a promising material for biomedical applications requiring strength–modulus optimisation and thermomechanical tunability. Isothermal compression tests were performed within the temperature range of 923–1173 K and at strain rates of 0.17, 1.72, and 17.2 ${\mathrm{s}}^{-1}$ to assess the material’s response under industrially relevant hot working conditions. The alloy showed significant sensitivity to temperature and strain rate, with dynamic recovery (DRV) and dynamic recrystallisation (DRX) dominating the softening behaviour depending on the conditions. A strain-compensated Arrhenius-type constitutive model was developed and validated, resulting in an apparent activation energy of approximately 234 kJ/mol. Zener–Hollomon parameter analysis confirmed a transition in deformation mechanisms. Although microstructural and diffraction data suggest possible contributions from nanoscale phase transformations, including ω-phase dissolution at high temperatures, these aspects remain to be fully elucidated. The model offers reliable predictions of flow behaviour and supports optimisation of thermomechanical processing routes for biomedical β-Ti alloys. Full article

Background: There is little information about the effectiveness of oral nutritional supplements (ONS) in combatting nutrient inadequacies in primary care, where most malnutrition exists. Aim: To examine the extent to which readymade ONS add or displace the nutrients consumed in the diet and their impact on combatting dietary inadequacies. Methods: 308 free-living people >50 years with medium + high risk of malnutrition (Malnutrition Universal Screening Tool) were randomised to receive readymade low volume (2.4 kcal/mL), liquid ONS plus dietary advice (ONS + DA) or dietary advice alone (DA). Intake was assessed at baseline (24 h recall) and 4-weekly for 12 weeks (3-day diet record). Total nutrient intake was benchmarked against UK and European dietary reference values (DRVs). The proportion of energy and nutrients from the ONS that added or displaced those from the diet (net addition/displacement) was calculated. Results: ONS + DA led to significantly greater total energy and nutritional intakes, with 25/29 nutrient intakes significantly higher than with DA alone. There were no significant differences in dietary energy and nutrient intakes from food between the groups. There was little or no displacement of nutrients from the diet, with over 90% of the energy and nutrients consumed in the ONS additive to the diet. ONS + DA more than halved the number of people with nutrient intakes that failed to meet DRVs and the number of nutrients per person that did not meet DRVs compared to DA alone. Conclusions: Supplementation with readymade, low volume (2.4 kcal/mL) liquid ONS overcomes most nutrient intake inadequacies in malnourished older people in primary care without significantly reducing intake from the diet. This makes ONS an effective way to improve nutritional intakes above dietary advice alone to improve the outcomes for the management of older people at risk of malnutrition. Full article

In the Direct Energy Deposition (DED) process, the deposited material experiences intricate thermo-mechanical processes. Subsequent thermal cycling can trigger Dynamic Recrystallization (DRX) under suitable conditions, with specific strain and temperature parameters facilitating grain refinement and homogenization. While prior research has examined the impact of thermal cycling in continuous wave (CW) lasers on DRX in 316 L stainless steel deposits, this study delves into the effects of pulsed wave (PW) laser thermal cycling on DRX. Here, the thermo-mechanical response to PW cyclic thermal loading is empirically assessed, and the evolution of microstructure, grain morphology, geometric dislocation density (GND), and misorientation map during PW DED of 316 L stainless steel is scrutinized. Findings reveal that DRX is activated between the 8th and 44th thermal cycles, with temperatures fluctuating in the range of 680 K–750 K–640 K and grains evolving within a 5.6%–6.2%–5.2% strain range. After 90 thermal cycles, the grain microstructure undergoes significant alteration. Throughout the thermal cycling, dynamic recovery (DRV) occurs, marked by sub-grain formation and low-angle grain boundaries (LAGBs). Continuous dynamic recrystallization (CDRX) accompanies discontinuous dynamic recrystallization (DDRX), with LAGBs progressively converting into high-angle grain boundaries (HAGBs). Elevated temperatures and accumulated strain drive dislocation movement and entanglement, augmenting GND. The study also probes the influence of frequency and duty cycle on grain microstructure, finding that low pulse frequency spurs CDRX, high pulse frequency favors DRV, and the duty cycle has minimal impact on grain microstructure under PW cyclic thermal load. Full article

In a global context marked by food insecurity and the increasing prevalence of non-communicable diseases, this study proposes a healthy food basket (HFB) model tailored to the demographic, cultural, and economic specificities of the Republic of Moldova which is aligned with international standards. The research employed a comprehensive methodology, including estimations of daily energy requirements using revised Harris–Benedict equations, food selection based on nutritional value, economic availability, and cultural relevance, and nutritional validation through the mean adequacy ratio (MAR), which was derived from nutrient adequacy ratios (NARs) and dietary reference values (DRVs) established by the EFSA. Nutrient intake calculations were based on food composition data and not population-level dietary surveys. Fat-soluble vitamins were excluded due to insufficient available data. The results indicate adequate intake levels of vitamins (B₁, B₂, B₃, and C) and minerals (iron, magnesium, phosphorus, and potassium) while highlighting deficiencies in calcium and sodium that require dietary adjustments. The inclusion of traditional foods, such as kefir and salted or raw pork fat, underscores the model’s cultural acceptability and economic relevance, strengthening the integration of global nutritional principles with regional dietary habits. This study’s limitations, including the use of secondary data and the lack of empirical validation, highlight the need for longitudinal studies. The HFB model offers a replicable solution for other regions facing similar challenges, contributing to global efforts to reduce malnutrition and promote sustainable diets. Full article

In order to accurately obtain the deformation characteristics and suitable thermal deformation conditions of TA15N titanium alloy and guide the design of deformation process parameters, a Gleeble 1500D was used to conduct hot compression tests on the thermal deformation behavior of a deformed TA15N titanium alloy under the condition of a strain rate of 0.01–10 s⁻¹ and a deformation temperature of 850–1090 °C. The constitutive equations for the deformed TA15N titanium alloy based on the Arrhenius formula were developed, and the reliability of the constitutive equations was verified. A thermal processing map of the deformed TA15N titanium alloy was established by using the dynamic materials model (DMM). The research results show that the flow stress of the TA15N alloy decreased with an increase in deformation temperature and a decrease in strain rate. By utilizing electron backscattered diffraction (EBSD), the microstructural evolution and deformation process were analyzed. As the value of η decreased, dynamic recovery (DRV) gradually replaced dynamic recrystallization (DRX). This study supplies a relatively reliable processing interval for the new TA15N titanium alloy. Full article

In this study, the high-temperature thermal deformation behavior of the TA4 alloy was investigated by thermal compression experiments. The effects of deformation temperature and strain rate on the rheological stress are described by analyzing the variation of stress–strain curves with different parameters and establishing the constitutive equation based on the dynamic material theory model. Thermal processing diagrams were established and plotted to analyze the optimal processing zone and the destabilization zone under different strains. From the thermal machining diagram, it can be concluded that the optimum machining zone at a strain of 0.9 is 1040~1133 K/0.01~0.7 s⁻¹. The optimum machining zone at a strain of 0.6 is 940~1000 K/0.01~0.04 s⁻¹. The optimum machining zone at a strain of 0.3 is 940~1000 K/0.01~0.08 s⁻¹. The effects of different deformation conditions on the thermal deformation mechanism were analyzed in conjunction with EBSD characterization. The results showed that dynamic recrystallization (DRX) was the main deformation softening mechanism when at low strain rate (≤0.1 s⁻¹). At higher strain rates (>0.1 s⁻¹) and lower temperatures (<1083 K and ≥933 K), the main deformation softening mechanism was DRV; at higher temperatures (≥1083 K and ≤1133 K), the main deformation softening mechanism was DRX. Full article

Background: Epidemiological evidence suggests a link between the risk of IBD and diet. Macro- and micro- nutrient intake, diet quality and dietary patterns may play a pivotal role in disease pathogenesis. We aimed to study the dietary intake of newly diagnosed IBD patients compared to non-IBD controls. Methods: A cohort of newly diagnosed IBD patients were invited to complete the Scottish Collaborative Group Food Frequency Questionnaire (SCGFFQ) at their first clinic visit. Controls were recruited from non-IBD ambulatory patients, university students, and healthcare workers. The SCGFFQ estimates habitual diet over a 3-month period. Component nutrient data were calculated based on previous validation studies, deriving nutrient data by comparison of the SCGFFQ to actual weighted food records. Data on age, gender, ethnicity, and disease phenotype were collected. The intake of macro- and micro-nutrients was expressed as mean and standard deviation and compared using the Kruskal–Wallis test. Dietary patterns were derived using principal component analysis. Differences in the dietary patterns for age, gender, and ethnicity were analysed by logistic regression analysis. The diet quality was compared to the dietary recommendation values (DRVs) and measured using the diet quality index. Results: We enrolled 160 IBD cases (114 UC and 46 CD) and 126 non-IBD controls, and in the study, with a median age across the groups of 40 years (IQR = 24) for UC, 34 years (IQR = 29) for CD, and 36 years (IQR = 24) for non-IBD controls. The diet quality indexes for both UC and CD were low compared to controls: 59.0% (SD 18.0) for UC, 46.0% (SD 17.7) for CD, and 63.2% (SD 17.1) controls. UC patients had excessive total energy consumption (>2500 kcal/day) compared to the DRVs. UC patients reported higher retinol, vitamin D, riboflavin, niacin, vitamin B6, vitamin B12, and panthanoic acid intake, consistent with a diet rich in animal products and low in fruit/vegetable intake. This is likely driven by higher consumption of dietary patterns 2 (rich in carbohydrates, refined sugar and low fibre) and 5 (refined sugar and saturated fat) in the UC cohort. Dietary pattern 1 (variety of food items and oily fish) was less likely to be consumed by the CD population. CD patients tended to have a lower overall intake of both macro- and micro-nutrients. Conclusions: The dietary patterns identified here are a proof of concept, and the next phase of the study would be to ideally monitor these patterns in a case–control cohort prospectively, and to further understand the mechanisms behind which dietary patterns influence IBD. Patients with newly diagnosed CD have low dietary quality and lower overall intake of macro- and micro-nutrients. This finding supports the role for dietetic attention early in newly diagnosed CD. Full article

Background/Objectives: Limited evidence links maternal macronutrient intake to gestational diabetes mellitus (GDM) risk. Therefore, we evaluated these intakes both before and during pregnancy, comparing macronutrient data against the European Food and Safety Authorities’ (EFSA) Dietary Reference Values (DRVs). Methods: Data were prospectively collected from the Greek BORN2020 epidemiologic pregnant cohort, which included 797 pregnant women, of whom 14.7% were diagnosed with GDM. A multinomial logistic regression model assessed the association between macronutrient intake and GDM, adjusting for maternal, lifestyle, and pregnancy-related factors. Results: Women with GDM had higher maternal age (34.15 ± 4.48 vs. 32.1 ± 4.89 years), higher pre-pregnancy BMI (median 23.7 vs. 22.7 kg/m²), and were more likely to smoke during mid-gestation (17.95% vs. 8.82%). Pre-pregnancy energy intake exceeding EFSA recommendations was associated with increased GDM risk (aOR = 1.99, 95%CI: 1.37–2.86). During mid-gestation, higher dietary fiber intake (aOR = 1.05, 95%CI: 1.00–1.10), higher protein intake (aOR = 1.02, 95% CI: 1.00–1.04), and higher protein percentage of energy intake (aOR = 1.08, 95%CI: 1.01–1.17) were all significantly associated with increased GDM risk. Changes from pre-pregnancy to pregnancy showed significant increases in dietary fiber intake (aOR = 1.07, 95%CI: 1.04–1.10), protein (aOR = 1.00, 95%CI: 1.00–1.01), fat (aOR = 1.00, 95%CI: 1.00–1.01), vegetable protein (aOR = 1.01, 95%CI: 1.00–1.03), animal protein (aOR = 1.00, 95%CI: 1.00–1.01), and monounsaturated fatty acid (MUFA) intake (aOR = 1.01, 95%CI: 1.00–1.02), all of which were associated with increased GDM risk. Conclusions: Energy intake above upper levels set by EFSA, as well as increased protein, MUFA, and fiber intake, although beneficial in balanced intakes, may negatively affect gestation by increasing GDM likelihood when consumed beyond requirements. Full article

As the global concern over greenhouse gas emissions grows, CO₂ storage in deep saline aquifers and depleted reservoirs has become crucial for climate change mitigation. This study evaluates the feasibility of Lithuanian deep saline aquifers, specifically, Syderiai and Vaskai, for effective CO₂ storage. Unlike previous theoretical analyses, it provides experimental data on static and dynamic reservoir parameters that impact CO₂ injection and retention. Using micro X-ray computed tomography (MXCT) and multi-resolution scanning at 8 µm and 22 µm, digital rock volumes (DRVs) from core samples were created to determine porosity and permeability. The method, validated against analogous samples, identified a representative element volume (REV) within sub-volumes, showing a homogeneous distribution of petrophysical properties in the Lithuanian samples. The results show that DRVs can accurately reflect pore-scale properties, achieving 90–95% agreement with lab measurements, and offer a rapid, efficient means for analyzing storage potentials. These insights confirm that Lithuanian aquifers are promising for CO₂ sequestration, with recommendations for further long-term monitoring and applications of this technique across the region. Full article

The present study prepared 7075Al composites reinforced with vapor-phase-grown carbon nanofibers (VGCNFs) using the spark plasma sintering (SPS) method. Constitutive equations of the composites were calculated, and thermal processing maps were constructed by performing thermal compression tests on the VGCNF/7075Al composites at deformation temperatures ranging from 300 to 450 °C and strain rates from 0.01 to 1 s⁻¹. This study analyzed the microstructural evolution of the VGCNF/7075Al composites during the thermomechanical processing. The experimental results demonstrated that dynamic recrystallization (DRX) primarily governed the softening mechanism of VGCNF/7075Al composites during thermomechanical processing. At high strain rates, a combination of dynamic recovery (DRV) and DRX contributed to the softening behavior. The incorporation of VGCNFs results in higher dislocation density and a larger orientation deviation within the 7075Al matrix during the thermomechanical deformation process, providing stored energy that facilitated DRX. The activation energy for deformation of VGCNF/7075Al composites was 175.98 kJ/mol. The constitutive equation of the flow stress showed that a hyperbolic sinusoidal form could effectively describe the relationship between flow stress, strain, strain rate, and temperature of VGCNF/7075Al composites. The optimal thermomechanical deformation parameters for VGCNF/7075Al composites were 400–450 °C and 0.01–0.1 s⁻¹ when the strain ranged from 0.05 to 0.15. For strains between 0.25 and 0.35, the optimal thermomechanical parameters were 380–430 °C and 0.01–1 s⁻¹. Full article