Search Results (512)

In an effort to evaluate the performance of a 5-gallon pot still in separating yeast-derived congeners during the distillation of a grain-based distiller’s beer, the distillates of a fermented mash of cracked corn, malted barley, and wheat were characterized using ¹H NMR spectroscopy and GC-MS. A quantitative comparison using these two techniques is uncommon. Results revealed significant variation in congener concentrations across runs, with a notable discrepancy in the third run possibly due to bacterial contamination, as indicated by high 1-propanol levels. Key congeners, such as acetaldehyde, ethyl acetate, furfural, phenylethanol, and 1,1-diethoxyethane, showed expected distillation behavior across ten fractions, based on their respective boiling points. However, methanol and 1-propanol showed a fairly flat concentration profile across all ten fractions, while those for ethyl octanoate and ethyl hexanoate decreased rapidly and were undetected at fraction 5. White dog (unaged whiskey) fractions from column and combination stills were also analyzed, and the results demonstrate that the small 5-gallon still separates congeners as well as these stills. Finally, a comparison of congener concentrations demonstrates that NMR and GC-MS do not yield identical concentrations of congeners, despite exhibiting similar trends in congener concentrations in the fractions from the still, with GC-MS suggesting higher levels. Full article

This paper investigates the rotational lift production of translating and rotating wings within a small insect’s Reynolds number range. Using the Reynolds number 1200 of a bumblebee, three wing section profiles were studied: a circular cylinder model as a reference for a blunt body for which the well-known Magnus effect will occur, a flat plate model as a reference for a sharp body for which the Kramer effect will occur, and finally, an elliptical cylinder model as a transition case. Direct force measurement and particle image velocimetry (PIV) experiments were performed to measure the lift produced and the surrounding flow velocity, and the Kutta–Joukowski theorem was applied to analyze the PIV results. The Kutta–Joukowski theorem gives the relationship between lift and circulation on a body moving at constant speed in a real fluid with some constant density. The experimental results were analyzed and verified by comparing them to the computational results. In general, there is reasonable agreement between the experimental and computational results, confirming that the Magnus effect is observed for the circular cylinder model and no Kramer effect is observed for the flat plate model. The elliptical cylinder model does not appear to be blunt enough for the Magnus effect to occur, and it is not sharp enough for the Kramer effect to occur. Full article

Closed-section composite structures with corners present significant challenges during forming and molding for achieving the desired thickness distribution over the profile. The experimental investigation in the present work was designed to compare laminates constructed entirely from twill-weave carbon fabric prepregs with different hybrid laminates constructed by combining unidirectional (UD) carbon fiber prepregs around the flat and twill-weave fabric prepregs around the curved section. Although the UD fiber prepregs were found to be more compressible than the twill-weave prepregs, the desired thickness distribution (to within 2% of design geometry), along with the proper level of consolidation, was obtained only with the hybrid construction that had an equal number of UD plies around the flat and twill-weave plies around the curved section. In contrast, the thickness distribution obtained with the all-twill prepreg laminate deviated from the design geometry by 5.4%. Forming simulations incorporating experimentally derived compaction behavior of different plies were used to predict the local compaction, tool–ply contact pressures, and thickness profile of the molded part. The simulation results for thickness profiles showed similar trends to those observed in experiments. Full article

The industrial cultivation of microalgae for high-value products faces significant challenges, particularly in maintaining long-term, cost-effective operations. Semi-continuous cultivation presents a promising solution to this problem. In this study, the green alga Chlorella sorokiniana IPPAS C-1 was cultivated in a flat-panel 5 L photobioreactor under optimized conditions, with three biological replicates. We evaluated batch mode against three semi-continuous dilution fractions (50%, 75%, and 87.5%). The 75% dilution fraction demonstrated superior performance, achieving the highest biomass productivity with an average specific productivity of 1.36 g DW L⁻¹ day⁻¹ over seven harvest cycles. Furthermore, this regime ensured stable biochemical composition—including proteins, lipids, carbohydrates, and pigments—as well as a consistent lipid profile and sustained photosynthetic activity throughout the cultivation. These findings are useful for the development of scalable and efficient technological protocols for the industrial production of Chlorella in flat-panel photobioreactors. Full article

To avoid dependence on conventional raw materials, global emphasis has been placed on obtaining alternative plant celluloses and the chemical synthesis of cellulose. The use of synthetically derived cellulose as a precursor for cellulose nitrates (NCs) is currently absent in global practice, which underscores the undoubted relevance of this research. Cellulose nitrate (NC) was synthesized in a 138% actual yield by nitration of synthetic cellulose (SC)—a new type of cellulose—prepared by electropolymerization from an aqueous glucose solution in the presence of catalytic tungsten–vanadium heteropolyacid of the 1–12 series with the chemical formula H₆[PW₁₀V₂O₄₀]: a nitrogen content of 11.83%, a viscosity of 198 mPa·s, a high solubility of 91% in an alcohol–ether solvent, and an ash content of 0.05%. SEM provided a general concept of the morphological structure of SC and SC-derived NC. The initial SC consisted of flat, curly fibers with a smooth surface approximately 10–20 μm wide, with no aggregation observed. The fibers of SC-derived NC had a cylindrical shape with a diameter of up to 25 μm and a rough surface. FT-IR spectroscopy revealed that SC and SC-derived NC have the main functional groups characteristic of classical cellulose (3346, 2901, 1644, 1429, 1162, and 1112 cm⁻¹) and nitrate esters of cellulose (1650, 1278, 832, 747, and 689 cm⁻¹), respectively. For the first time, a full-profile analysis discovered that SC is made up of the monoclinic phase of cellulose Iβ with an antiparallel chain arrangement. SC with a crystallinity index (CrI) of 81–86% was shown to undergo amorphization upon nitration, with the CrI declining to 17% and the crystallite sizes decreasing from 44 × 62 × 59 × 94 Å to 29 × 62 × 26 × 38 Å. Coupled TGA/DTA revealed that SC exhibits a high-temperature endothermic peak of decomposition of 374 °C, with a weight loss of 84%. The thermostable SC-derived NC exhibits a high onset temperature of intense decomposition of 200 °C and an exothermic peak of 208 °C, with a weight loss of 88%, and is characterized by a high specific heat of decomposition of 7.74 kJ/g. This study provides new insights into the functionalization of SC with a high degree of polymerization, expanding the classical concepts of cellulose nitration. Full article

The roll-to-plate (R2P) hot-embossing process is a newly developed molding technique for the high-throughput, high-efficiency fabrication of large-area microstructured optical elements. However, this technology is limited to flat surfaces, because the thickness of the freeform optical plate varies constantly due to its specific optical design, while the roll stays cylindrical during rolling. Therefore, we developed a new profile-tunable roll with several groups of semiconductor heater/coolers (SHCs) attached around the inside wall of the roll. These SHCs can achieve tunable roll profiles at desirable positions by regulating the current for the semiconductor and then the roll temperature, thereby producing optics with a selected freeform. In this paper, the circumferential bulging profiles and corresponding roll temperature fields were thoroughly investigated under various heater/cooler layouts and roll sizes. A circumferential finite element model of the profile-tunable roll was established using the finite element software MSC.MARC 2020 and then verified on the experimental platform. In addition, the fundamental relationship between the bulging values and temperature distributions of the roll and parameters, such as the outer diameter and inner diameter of the roll, the temperature of the semiconductor heater/cooler, and the single piece influence angle, was eventually established. This paper offers a unique fabrication method for high-volume optical freeform plates at extremely low cost and builds a foundation for further research on the axial deformation and temperature distribution of the developed roll for freeform optics and R2P hot-embossing experiments for freeform optical components. Full article

GCr15 bearing steel sliding friction pairs, as key components in mechanical engineering applications, often undergo severe friction and wear under starved lubrication, which restricts their service life and reliability significantly. To solve this problem, this study investigates the effect of laser surface texturing on the tribological performance of GCr15 bearing steel under starved lubrication conditions. A laser marking machine is used to fabricate pit textures on GCr15 sliding surfaces, exploring the effects of processing speed, laser power, and frequency on texture integrity. Friction and wear tests under starved lubrication conditions are conducted using a vertical universal tester, and worn surfaces are characterized using a 3D surface profiler. The results show that high-integrity flat-bottom pits form at 200 mm/s, 10 W, and 80 kHz. These textures collect debris, retain lubricant, and provide secondary lubrication. At a depth-to-diameter ratio of 0.083 and area ratio of 14.9%, the friction coefficient (0.076) and wear loss (2.27 mg) decrease by 27.6% and 63.7%, respectively, compared to those of smooth samples (0.105, 6.25 mg). This study clarifies the regulatory mechanisms and provides references for improving key components’ lifespan and reliability. Full article

This study proposes a “zonal inversion–fusion mosaicking” technical framework to address the challenge of acquiring continuous full-profile topography data in coastal wetland intertidal zones. The framework integrates and synergistically analyzes data from multi-platform sensors, including satellite, unmanned aerial vehicle (UAV), and ground-based instruments. Applied to the Min River Estuary wetland, this framework employs zone-specific optimization strategies: in the inundated zone, the topography was inverted using Landsat-9 OLI imagery and a Random Forest algorithm (R² = 0.79, RMSE = 2.08 m); in the bare flat zone, a linear model was developed based on Sentinel-2 time-series imagery using the inundation frequency method, and it achieved an accuracy of R² = 0.86 and RMSE = 0.34 m; and in the vegetated zone, high-precision topography was derived from UAV oblique photography with Kriging interpolation (RMSE = 0.10 m). The key innovation is the successful generation of a seamless full-profile digital elevation model (DEM) with an overall RMSE of 0.54 m through benchmark unification and precision-weighted fusion algorithms from the sensor data fusion perspective. This study demonstrates that the synergistic sensors framework effectively overcomes the limitations of single-sensor observations, providing a reliable and generalizable integrated solution for the full-profile topographic monitoring of tidal flats, which offers crucial support for coastal wetland research and management. Full article

Deep-ultraviolet (DUV, 193 nm) tools for lithography and precision micromachining are often limited by beam-profile nonuniformity, which degrades critical-dimension control, line-edge roughness, and process windows. Conventional phase-dependent homogenizers can lose performance under realistic phase noise and pointing jitter. We investigate two complementary, energy–space-modulation routes to robust homogenization: (i) a metalens-based microlens array (MLA) that forms a flat-top via controlled beamlet overlap and (ii) a chromium-on-sapphire attenuator that equalizes intensity purely by amplitude shaping. Coupled FDTD and optical modeling guide a graded-transmittance Cr design (target transmittance 0.8–0.9) that converts a Gaussian input into a flat-top plateau. Experiments at 193 nm verify that both approaches achieve high static uniformity (Urms <3.5%). Under dynamic conditions, the MLA exhibits sensitivity to transverse-mode hops and phase fluctuations due to its reliance on coherent overlap, leading to reduced uniformity and fill factor. In contrast, the Cr attenuator remains phase-insensitive and maintains stable output under jitter, offering a power-robust, low-maintenance alternative for industrial DUV systems. We discuss design trade-offs and outline hybrid MLA + attenuation schemes that preserve MLA-level flatness while approaching the robustness of amplitude-shaping solutions. Full article

The successful establishment of young chestnut orchards is increasingly challenged by drought stress and limited irrigation availability, especially in areas with limited water access. This study evaluated the effects of ridge planting and plastic foil mulching, individually and in combination, on the early growth and stress physiology of vegetatively propagated Castanea sativa × C. crenata ‘Marsol’ trees under rainfed conditions. Over a two-year field trial, vegetative traits, photosynthetic pigments, and leaf phenolic profiles were assessed to determine treatment effects. Ridge planting combined with foil mulching significantly improved tree growth, leading to a 2.6-fold increase in leaf number and 1.6-fold increase in height compared to control (flat planting without foil). This treatment also minimized stress indicators, such as chlorosis and elevated phenolic content. Notably, the ellagitannin chestanin emerged as a dominant stress-related metabolite in the first year, suggesting its potential as an early biochemical marker of transplantation stress. Over time, a compositional shift in phenolic groups, from hydroxycinnamic acids and flavanols to flavonols and hydroxybenzoic acids, was observed, reflecting the plant’s transition from acute stress response to developmental acclimation. These results support ridge planting with foil as a practical, climate-adaptive solution for chestnut orchard establishment and highlight chestanin as a candidate marker for stress monitoring in young trees. Full article

High-speed and broadband waveform generation based on using a Sinc² sampled fiber grating (SFG) combined with a femtosecond laser source is investigated. The Sinc² SFG provides linear wavelength divided multiplexing (WDM) time delay lines (TDLs) with sub-picosecond delay steps, and two types of reflectivity spectrum with flat-top and linear profiles for a large number of wavelength channels. The femtosecond laser is used as a broadband source. Simulation results demonstrate that the generation of rectangular and sawtooth waveforms is achieved through numerical modeling based on wavelength-to-time mapping using a grating TDL and an ultrafast laser. Results show, for example, that a rect waveform is generated with a repetition frequency (f_rep) of 125 GHz, a period (T) of 8 ps, and a rise-fall time of 4% T; a sawtooth waveform is generated with a f_rep of 69.5 GHz, a period of 14.39 ps, a rise time of 2.8% T, and a ramp linearity of 0.1% standard deviation. Full article

The current study investigates the effect of terrain features on wind resources in a region with extremely diverse terrain. To that end, a case study of Nepal based on annual wind data collected from 10 different sites is performed. The evaluation of mean wind speeds using Weibull probability density functions (PDFs) shows that complex-terrain sites exhibit greater variability in 10-min average wind speeds relative to the annual average wind speeds. This pattern is also evident in comparisons of short- and long-term average wind speeds. At the complex-terrain sites, the wind speeds exhibited strong short-term variations, suggesting that local terrain effects dominate over seasonal wind variation. Terrain complexity also strongly affected turbulence. The flat-terrain sites showed turbulence intensities below the lowest IEC category turbulence profile, while the complex-terrain sites exceeded the highest IEC profile. This indicates that the IEC standard may require modification based on site complexity parameters, such as the standard deviation of elevation fluctuations. The power law exponent ($\alpha$), used to extrapolate wind speeds to higher elevations, deviated notably from the typical 1/7 value, even in flat terrain. Finally, a power potential analysis indicated that three sites with higher mean wind speeds achieved higher capacity factors. Full article

This work shows that the length of single-walled carbon nanotubes is critical in governing the trade-off among the rate, efficiency, and stability of pressure-driven water transport. A critical length of 1.06 nm marks the transition in the transport mechanism from a thermal-fluctuation-dominated regime to an ordered water-chain mode. This transition is driven by the evolution of the potential of mean force with tube length, which progresses from a flat landscape to a high-barrier profile and ultimately forms a low-resistance tunnel in long nanotubes. Notably, this tunnel endows the water chain with an enhanced ability to restore its continuity, allowing it to bridge fracture gaps as wide as 7 Å even in the absence of an external pressure difference. These insights reveal a length-dependent mechanism that could revolutionize CNT–hydrogel hybrids for biomedical applications. Full article

Understanding suspended sediment transport in macrotidal embayments is crucial for assessing water quality, ecosystem function, and long-term morphological stability. This study provides a high-resolution, localized estimate of suspended sediment flux and examines the empirical relationship between turbidity (NTU, nephelometric turbidity unit) and total suspended matter (TSM, mg·L⁻¹) in the main tidal channel of Gomso Bay, a UNESCO-designated tidal flat on the west coast of Korea. A 13 h high-resolution fixed-point observation was conducted during a semi-diurnal tidal cycle using a multi-instrument platform, including an RCM, CTD profiler, tide gauge, and water sampling for gravimetric TSM analysis. Vertical measurements at the surface, mid, and bottom layers, taken every 15–30 min, revealed a strong linear correlation (R² = 0.94) between turbidity and TSM, empirically validating the use of optical sensors for real-time sediment monitoring under the highly dynamic conditions of Korean west-coast tidal channels. The net suspended sediment transport load was estimated at approximately 5503 kg·m⁻¹, with ebb-dominant residual currents indicating a net seaward sediment flux at the observation site. Residual flows over macrotidal channels are known to vary laterally, with landward fluxes often occurring over shoals. Importantly, the results from this single-station, short-duration observation indicate a predominantly seaward suspended sediment transport during the study period, which should be interpreted as a localized and time-specific estimate rather than a bay-wide characteristic. Nevertheless, these findings provide a baseline for assessing sediment flux and contribute to future applications in digital twin modeling and coastal management. Gomso Bay is part of the UNESCO-designated ‘Getbol, Korean Tidal Flats’, underscoring the global significance of preserving and monitoring this dynamic coastal system. Full article

Nanostructured targets are increasingly used as key components in high-power laser–matter interaction experiments due to their ability to substantially enhance laser absorption, increase ion/electron generation, or boost the secondary radiation (THz, X-ray, etc.) in accordance with the actual scientific requirements in ultraintense regimes. Their tailored surface features influence the way the energy is deposited in the material, leading to significantly enhanced interaction effects compared to the flat conventional targets. In this study, we numerically investigate the mechanisms of laser field intensification occurring in the interaction between an ultraintense laser pulse and a nanostructured conical target. In order to provide a complex spatio-temporal description of the laser intensity evolution in the interaction area, we developed a 2D finite-difference time-domain model in accordance with the relative spatial extension of the pulse. The laser field intensification is numerically investigated in the vicinity of the laser matter interaction point considering four different materials of the nanopatterned conical targets and variable laser beam parameters in order to determine the optimum conditions to streamline the laser field enrichment in the laser solid targets interaction area. The numerical results show that the designed nanostructured profile of the internal cone target walls under imposed particular conditions induces a highly controllable increase in laser field intensity. Consequently, this enhanced field localization highlights the essential role of nanostructured design in advancing ultraintense laser applications that require efficient energy coupling and extreme field concentrations. Full article