The increasing demand for compact and energy-efficient heat exchangers has accelerated the development of passive heat transfer enhancement techniques and intelligent predictive tools for improved thermal system design. In the present study, an experimental and machine learning-based investigation was conducted to evaluate the thermo-hydraulic performance of a counter-flow double-pipe heat exchanger equipped with helical wire coil (WC) inserts under turbulent flow conditions. The novelty of this work lies in the systematic assessment of fifteen insert configurations by combining three wire diameters (1.0, 1.5, and 2.0 mm) with five pitch ratios (P/Dc = 0.625, 1.25, 1.875, 2.5, and 3.125). Experiments were performed over a Reynolds number range of 5500-15000, and the experimental setup was validated against established Nusselt number and friction factor correlations. The thermo-hydraulic performance was evaluated using the heat transfer coefficient, Nusselt number, friction factor, pressure drop, and thermal performance factor. The results showed that the wire coil inserts generated strong swirl flow and secondary vortices, which enhanced fluid mixing and suppressed thermal boundary layer development, resulting in a maximum Nusselt number enhancement of 126.7% compared with the plain tube. The highest Nusselt number (180.24) was achieved using a 2 mm wire diameter with a P/Dc of 0.625. Although the friction factor increased by 156.5-410.8% due to greater flow resistance, the thermal performance factor remained above unity (1.01-1.35) for all configurations, confirming the overall thermo-hydraulic effectiveness of the inserts. Furthermore, Linear Regression, Ridge Regression, Random Forest, and Gradient Boosting models were developed to predict the heat transfer and flow characteristics. Among them, the Gradient Boosting model demonstrated the highest prediction accuracy, achieving R2 values of 0.9984 and 0.9971 for the Nusselt number and friction factor, respectively, highlighting the potential of machine learning for the rapid design and optimization of advanced heat exchanger systems.
In grasses, almost all species belong to two evenly sized clades: BOP (Bambusoideae, Oryzoideae and Pooideae) and PACMAD (Panicoideae, Arundinoideae, Chloridoideae, Micrairoideae, Aristidoideae and Danthonioideae). Yet the >20 independent origins of C4 photosynthesis are confined to the PACMAD lineage. This pattern suggests that PACMAD grasses may harbour genetic features that primed them for the repeated evolution of this trait. To investigate this possibility, we examine gene turnover to identify genetic components that potentially facilitated the repeated evolution of C4 photosynthesis and were present at the base of the PACMAD clade, representing the last common ancestor of all C4 grasses. We generated the first reference genomes for Aristidoideae species (Aristida adscensionis and Stipagrostis hirtigluma), the sister lineage of all other PACMAD grasses. In combination with 34 other Poales genomes, we identify genes gained at the base of the PACMAD clade and genes lost in the sister BOP lineage. Gene expansion at the base of the PACMAD lineage includes one with a known C4 function (beta-carbonic anhydrase), as well as genes involved in amino acid and nitrate transport, carbon metabolism, oxidative stress management and transcription regulation. Gene turnover in the PACMAD stem lineage generated novel variation in the last common ancestor of all C4 grasses. Although this predates the emergence of C4 photosynthesis itself, these changes may have generated the genetic substrate and requirements for the repeated emergence of C4 photosynthesis in this clade.
The presence of toxic heavy metals such as cadmium and lead in wastewater poses a serious environmental and health risk due to their persistence and bioaccumulation. In this study, a novel polystyrene/sulfonated bentonite nanocomposite (PS/NSB) was synthesized from low-cost materials and applied as an efficient adsorbent for Cd(II) and Pb(II) removal from aqueous solutions. Structural and morphological characterizations (TEM, FTIR, TGA, SEM, and EDX) confirmed successful functionalization and enhanced surface area. Batch adsorption experiments demonstrated high uptake capacities (200 mg/g for Cd(II) and 135.13 mg/g for Pb(II)), with kinetics following the pseudo-second-order model and equilibrium fitting the Langmuir isotherm, indicating monolayer chemisorption. The nanocomposite exhibited good regeneration over successive cycles, underscoring its reusability. After treatment, residual concentrations of Cd(II) and Pb(II) were reduced to below 0.01 mg/L, meeting WHO/FAO discharge standards. These findings highlight the novelty and practical potential of PS/NSB as a cost-effective and sustainable material for wastewater treatment.
This study reports a one-step paste-coated ZnO–PANI MSM photodetector decorated with Ag NPs via photodeposition. The undeposited device achieved a Responsivity of 1.40 A/W, Detectivity of 3.51 × 1013 Jones, and an EQE of 476
This study investigates the effect of aluminosilicate nanotubes (ANTs) on the fresh, mechanical, durability, and microstructural properties of thermally cured geopolymer concrete (GPC) synthesised using Class F fly ash (FA) and metakaolin (MK). ANTs were incorporated at dosages of 0-3.0% by binder weight, and the specimens were cured at 80 degrees C to replicate geothermal conditions. The experimental program included tests for slump flow, compressive and tensile strength (from 3 h to 28 days), water absorption, drying shrinkage, and pore size distribution. To elucidate the geopolymerization process and the role of ANTs in gel evolution and matrix densification, microstructural analyses were performed using X-ray diffraction (XRD), Fourier transform infra-red spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and derivative thermogravimetry (DTG). Furthermore, a one-way Analysis of Variance (ANOVA) and Tukey's HSD analysis were conducted to evaluate the statistical significance of the findings. The inclusion of ANTs reduced workability, with slump decreasing from 122 mm at 1.0% ANT to 89 mm at 3.0%, due to enhanced internal friction and water adsorption. Compressive strength at 1 day peaked at 55.95 MPa with 2.0% ANTs, 32.77% higher than the control. Likewise, splitting tensile strength improved by up to 191% at early ages with 2.0% ANTs but declined at 3.0% due to agglomeration. Drying shrinkage was minimised in the GPC-ANT_2 mix (3967 & micro;m/m), while maximum porosity refinement was observed in GPC-ANT_3. Mercury intrusion porosimetry confirmed significant pore structure densification, and capillary absorption dropped by over 35% with optimal ANT content. TGA/DTG and XRD results revealed enhanced geopolymer gel formation and thermal stability in ANT-modified GPC, while FTIR and SEM confirmed improved bonding and microstructural compactness at 2.0% ANTs. These findings highlight that an optimum ANT dosage of 2.0% enhances early-age strength, durability, and structural integrity of heat-cured geopolymer concrete.
