Search Results (262)

Meat juice leakage is a natural phenomenon, evident in culinary meat packaging, and is a key indicator of meat quality. This study aimed to evaluate the amount of meat juice leakage into the packaging during culinary pork, beef, and chicken storage in a refrigerated display case simulating retail conditions (2–4 °C, 12 days). The study included 1800 high-quality culinary meat samples, i.e., free of technological defects, packaged in vacuum (VAC) and modified atmosphere (MAP), with and without absorbent pads, obtained from meat processing plants. On the 12th day of storage, the leakage was determined in the meat portions using the gravimetric method, and pH and color (CIEL*a*b*) were measured using instrumental methods. It was found that the leakage level from culinary meat ranged from 2.10% for pork shoulder VAC to 10.70% for pork loin VAC, in slices, being influenced (p < 0.01) by each grouping factor: meat type, meat cut, and package type. Regardless of the packaging method, culinary chicken meat had a lower pH (p < 0.001) than pork and beef. The study also found significant negative correlations between pH and leakage in most culinary meat cuts, as shown by the results for ham VAC (r = −0.66), ham MAP (r = −0.59), and heel of round MAP (r = −0.50). Among meat color parameters, the most significant variability was observed for lightness (L*), whose mean value differed significantly depending on the type of meat (p < 0.001) and the meat cut (p < 0.001), and within the same culinary cut—except beef tenderloin and chicken breast fillet–also depending on the type of packaging (p < 0.05). Based on the results obtained in this study, covering a large number of culinary meat samples, it was suggested that recommended leakage levels, i.e., those that raise no concerns regarding meat quality, could range from 2% for shoulder and pork neck (both VAC) to just over 10% for tenderloin slices (packaged using the MAP and VAC methods). Our findings can be used by both meat producers and quality control authorities to monitor the quality of culinary meat, e.g., they may help determine maximum permissible leakage levels and design meat packaging methods to reduce leakage. Ultimately, these measures will enhance consumer confidence in meat production and quality. Additionally, the results systematize knowledge on meat leakage, providing valuable insights for scientists who support producers and retailers in their efforts to minimize this issue. Full article

In the present work, we report daytime latent heat flux profile measurements in the convective boundary layer (CBL) obtained from the combined use of a wind lidar and a thermodynamic Raman lidar. Water vapour flux profiles and, consequently, latent heat flux profiles were obtained as the covariance between the vertical profiles of the water vapour mixing ratio and vertical wind fluctuations. Profile measurements of the water vapour mixing ratio were carried out by the thermodynamic Raman lidar CONCERNING, while simultaneous profile measurements of the vertical wind speed were carried out by a co-located Doppler wind lidar. The considered dataset was collected in the frame of the international field campaign “Water Vapor Lidar Network Assimilation” (WaLiNeAs). Three cloud-free time intervals on 31 October, 28 November, and 8 December 2022 were selected as case studies. Measurements of turbulent kinetic energy (TKE) were also carried out over the same time intervals based on the use of wind lidar data. The three selected case studies were characterised by different atmospheric stability conditions and, consequently, by a different potential for the occurrence of convective activity. More specifically, the atmospheric conditions on 31 October 2022 were very unstable, with intensive convective activity taking place in the area and ultimately leading to relatively intense thunderstorms and rainfall events. The atmospheric conditions on 28 November 2022 were moderately unstable, ultimately leading to light convective activity, with scattered rain episodes observed throughout the day but with no severe thunderstorms taking place. Stratiform precipitations were present on 8 December 2022, with weak embedded convective processes taking place within stratiform clouds and leading to moderate additional precipitation. In all three selected case studies, representative of pre-convective conditions, both latent heat flux and TKE profiles are characterised by values increasing with altitude up to approx. 500 m, while both latent heat flux and TKE are found to decrease, with a steeper negative gradient up to approx. 600 m and more gradually above this altitude, returning to zero just above the top of the CBL. In all three cases, peak values of TKE appear to be strongly correlated with corresponding peak values of the latent heat flux; the higher the maximum values of TKE and latent heat flux, the more intense the following precipitation events. Full article

Catalytic upgrading of vacuum residue (VR) is critical for enhancing fuel yield and reducing waste in petroleum refining. This study explores VR cracking over a novel cerium-loaded acidified metakaolinite catalyst (MKA800–20%Ce) prepared via calcination at 800 °C, acid leaching, and wet impregnation with 20 wt.% Ce. The catalyst was characterized using FTIR, BET, XRD, TGA, and GC–MS to assess structural, textural, and thermal properties. Catalytic cracking was carried out in a fixed-bed batch reactor at 350 °C, 400 °C, and 450 °C. The MKA800@Ce20% catalyst showed excellent thermal stability and surface activity, especially at higher temperatures. At 450 °C, the catalyst yielded approximately 11.72 g of total liquid product per 20 g of VR (representing a ~61% yield), with ~3.81 g of coke (~19.1%) and the rest as gaseous products (~19.2%). GC-MS analysis revealed enhanced production of light naphtha (LN), heavy naphtha (HN), and kerosene in the 400–450 °C range, with a clear temperature-dependent shift in product distribution. Structural analysis confirmed that cerium incorporation enhanced surface acidity, redox activity, and thermal stability, promoting deeper cracking and better product selectivity. Kinetics were investigated using an eight-lump first-order model comprising 28 reactions, with kinetic parameters optimized through a genetic algorithm implemented in MATLAB. The model demonstrated strong predictive accuracy taking into account the mean relative error (MRE = 9.64%) and the mean absolute error (MAE = 0.015) [MAE: It is the absolute difference between experimental and predicted values; MAE is dimensionless (reported simply as a number, not %). MRE is relative to the experimental value; it is usually expressed as a percentage (%)] across multiple operating conditions. The above findings highlight the potential of Ce-modified kaolinite-based catalysts for efficient atmospheric pressure VR upgrading and provide validated kinetic parameters for process optimization. Full article

A variety of factors, such as absorption, reflection, and attenuation by atmospheric elements, influence the quantity of solar energy that reaches the surface of the Earth. This, in turn, impacts photovoltaic (PV) power generation. In light of this, a digital assessment of solar energy variability through short-term measurements was conducted to enhance PV power output. The clear-sky index $\left(K_t^{*}\right)$ methodology was employed, effectively eliminating any indications of solar energy obstruction and comparing the measured radiation to the theoretical clear-sky radiation. The solar energy data were gathered in Mozambique, specifically in the southern region at Maputo–1, Massangena, Ndindiza, and Pembe, in the mid-region at Chipera, Nhamadzi, Barue–1, and Barue–2, as well as in the northern region at Nipepe-1, Nipepe-2, Nanhupo-1, Nanhupo-2, and Chomba, over the period from 2005 to 2024, with measurement intervals ranging from 1 to 10 min and 1 h during the measurement campaigns conducted by FUNAE and INAM, with additional data sourced from the PVGIS, Meteonorm, NOAA, and NASA solar databases. The analysis indicates a $K_t^{*}$ value with a density approaching 1 for clear days, while intermediate-sky days exhibit characteristics that lie between those of clear and cloudy days. It can be inferred that there exists a robust correlation among sky types, with values ranging from 0.95 to 0.89 per station, alongside correlated energies, which experience a regression with coefficients between 0.79 and 0.95. Based on the analysis of the sample, the region demonstrates significant potential for solar energy utilization, and similar sampling methodologies can be applied in other locations to optimize PV output and other solar energy projects. Full article

This study investigates the dynamics and sources of atmospheric mercury in Qinhuangdao (QHD), a coastal urban area significantly impacted by both marine and terrestrial sources. Sampling of gaseous elemental mercury (GEM), fine particle-bound mercury (PBM_2.5), and coarse particle-bound mercury (PBM_2.5–10) was conducted from September 2022 to August 2023. The annual mean concentrations of GEM, PBM_2.5, and PBM_2.5–10 were 2.66, 1.01, and 0.73 ng m⁻³, respectively, with PBM levels among the highest reported for coastal cities in eastern China. GEM displayed a pronounced midday peak (12:00–14:00) with correlations to temperature (R² = 0.25–0.65) and a significant winter association with SO₂ (R² = 0.52), suggesting the combined influence of surface re-emission and coal combustion. Seasonal variations in the GEM/CO ratio (spring: 7.12; winter: 2.62) further reflected the shift between natural and combustion-related sources. PBM_2.5 exhibited elevated concentrations (1.0–1.4 ng m⁻³) under westerly winds (~3 m s⁻¹), indicating inputs from traffic, shipping, and light industries, while PBM_2.5–10 (0.5–1.1 μg m⁻³) was strongly linked to coal-handling activities at QHD port and soil resuspension. Backward trajectory analysis showed continental air masses dominated in winter (53–100%) and maritime air masses in summer (30–50%), whereas high Hg/Na ratios in PM_2.5 (3.22 × 10⁻⁴) and PM_2.5–10 (2.17 × 10⁻⁴), far exceeding typical marine aerosol values (10⁻⁷–10⁻⁵), indicated negligible marine contributions to PBM. These findings provide new insights into the processes driving mercury pollution in coastal urban environments and highlight the critical role of port-related activities in regional mercury management. Full article

The present work is aimed at shedding light on the evolution of surface chemistry of a commercial activated carbon (AC) support during the preparation of supported metal oxide (MO) catalysts by the conventional wet impregnation method. Particular attention is paid to the chemical changes of oxygen-containing surface functionalities across three preparation stages of impregnation, oven-drying, and thermal treatment. AC was impregnated with aqueous solutions of several MO precursors (Al(NO₃)₃, Fe(NO₃)₃, Zn(NO₃)₂, SnCl₂, and Na₂WO₄) at 80 °C for 5 h, oven-dried at 120 °C for 24 h, and heat-treated at 200 °C and 850 °C for 2 h under an inert atmosphere. The surface chemistry of the resulting catalyst samples, classified in three series by the thermal treatment, was mainly studied by FT-IR spectroscopy, complemented by elemental analysis and pH of the point of zero charge (pH_pzc) measurements. During impregnation, phenolic hydroxyl and carboxylic acid groups were predominantly formed by wet oxidation of chromene, 2-pyrone, and ether-type structures found in the pristine AC. The extent of these oxidations correlated with the oxidising power of the precursor solutions. As expected, thermal treatment at 850 °C brought about markedly stronger chemical changes, with most of the above oxygen functionalities decomposing and forming less acidic structures, such as 4-pyrone groups, metal carboxylates, and C-O-M atomic groupings. All these surface chemical modifications result in a lowering of the strong basicity of the raw carbon support (pH_pzc ≈ 10.5), thus leading to pH_pzc values for the catalysts widely ranging from 1.6 to 9.7. Full article

Impaired visibility, a major global environmental threat, is a result of light scattering by atmospheric particulate matter. While digital photographs are increasingly used for daytime visibility estimation, such methods are largely ineffective at night owing to the different scattering effects. Here, we introduce an image-based algorithm for inferring nighttime visibility from a single photograph by analyzing the forward scattering index and optical thickness retrieved from glow effects around light sources. Using photographs crawled from social media platforms across mainland China, we estimated the nationwide visibility for one year using the proposed algorithm, achieving high goodness-of-fit values (R² = 0.757; RMSE = 4.318 km), demonstrating robust performance under various nighttime scenarios. The model also captures both chronic and episodic visibility degradation, including localized pollution events. These results highlight the potential of using ubiquitous smartphone photography as a low-cost, scalable, and real-time sensing solution for nighttime atmospheric monitoring in urban areas. Full article

The wastewater treatment (WWT) industry is currently facing challenges imposed by the revised urban WWT directive, particularly in terms of nitrogen (N) and phosphorus (P) removal. This implies the need for mandatory tertiary treatment, for which microalgae cultivation shows great sustainability promise. This study investigated the impact of hydraulic retention time (HRT) on nutrient removal in open-air microalgae cultivation for tertiary WWT under winter conditions. Two pilot-scale semi-continuous raceway systems were operated with indigenous microalgae, natural sunlight, and no pH control. HRT values of 4, 5.5, and 7 days were tested, and N, P, and carbon (C) removal and recovery were measured. All conditions allowed nitrogen removal, complying with the revised urban WWT directive. Regarding P, only the 7-day HRT condition consistently complied with the directive’s lowest limit (<0.5 mg P·L⁻¹) in the treated water, while 5.5 and 4 days left up to 0.7 and 1.0 mg P·L⁻¹, respectively, in up to 25% of the samples. A stable microalgae consortium was established under variable light, pH, and dissolved oxygen conditions, albeit with variable biomass productivity. Elemental mass balances revealed that nutrients were mostly recovered in the produced biomass, particularly at high HRT, including effective CO₂ capture from the atmosphere. Full article

Daylighting plays a pivotal role in mosques, shaping their sacred atmosphere and enhancing the spiritual experience for worshippers. Beyond a mere architectural consideration, the integration of natural light into mosque design fundamentally influences the ambiance and functionality of these religious spaces. This study investigates the key factors that enhance daylight levels and visual comfort within prayer halls. It specifically evaluates illuminance levels, light distribution, and glare in four domed mosques located in Saudi Arabia. Field measurements were conducted beneath the domes of these prayer spaces, each featuring clerestory windows of varying forms and dimensions. Based on architectural specifications and material properties, daylight simulations and modeling were performed using the RADIANCE engine integrated with Grasshopper. The simulation results were validated against on-site illuminance measurements to ensure model accuracy and reliability. The primary objective was to assess whether the existing daylighting conditions comply with the recommended illuminance standards for reading and prayer, typically ranging from 150 to 500 lux. This study revealed that the illuminance levels in the central dome area exceeded the recommended values, reaching over 3000 lux. To improve daylight distribution, shading systems such as flat and curved shelves were added to the drum’s windows. This research concludes that the light shelves and vacuum double glazing significantly improved indoor daylight performance by preventing direct sunlight entry into the prayer hall and redirecting it towards the dome. This intervention successfully reduced excessive illuminance levels to a more optimal level of around 447–774 lux during the noon prayer period, ensuring a balanced and comfortable environment for worshippers. Full article

This study investigates the use of a Random Forest (RF), an artificial intelligence (AI) model, to estimate the planetary boundary layer height (PBLH) over Central Amazonia from climatic elements data collected during the GoAmazon experiment, held in 2014 and 2015, as it is a key metric for air quality, weather forecasting, and climate modeling. The novelty of this study lies in estimating PBLH using only surface-based meteorological observations. This approach is validated against remote sensing measurements (e.g., LIDAR, ceilometer, and wind profilers), which are seldom available in the Amazon region. The dataset includes various meteorological features, though substantial missing data for the latent heat flux (LE) and net radiation (Rn) measurements posed challenges. We addressed these gaps through different data-cleaning strategies, such as feature exclusion, row removal, and imputation techniques, assessing their impact on model performance using the Root Mean Square Error (RMSE), Mean Absolute Error (MAE), and $r^2$ metrics. The best-performing strategy achieved an RMSE of 375.9 m. In addition to the RF model, we benchmarked its performance against Linear Regression, Support Vector Regression, LightGBM, XGBoost, and a Deep Neural Network. While all models showed moderate correlation with observed PBLH, the RF model outperformed all others with statistically significant differences confirmed by paired t-tests. SHAP (SHapley Additive exPlanations) values were used to enhance model interpretability, revealing hour of the day, air temperature, and relative humidity as the most influential predictors for PBLH, underscoring their critical role in atmospheric dynamics in Central Amazonia. Despite these optimizations, the model underestimates the PBLH values—by an average of 197 m, particularly in the spring and early summer austral seasons when atmospheric conditions are more variable. These findings emphasize the importance of robust data preprocessing and higtextight the potential of ML models for improving PBLH estimation in data-scarce tropical environments. Full article

To address the concerns of contrast deterioration, detail loss, and color distortion in images produced under haze conditions in scenarios such as intelligent driving and remote sensing detection, an algorithm for image defogging that combines Retinex theory and the dark channel prior is proposed in this paper. The method involves building a two-stage optimization framework: in the first stage, global contrast enhancement is achieved by Retinex preprocessing, which effectively improves the detail information regarding the dark area and the accuracy of the transmittance map and atmospheric light intensity estimation; in the second stage, an a priori compensation model for the dark channel is constructed, and a depth-map-guided transmittance correction mechanism is introduced to obtain a refined transmittance map. At the same time, the atmospheric light intensity is accurately calculated by the Otsu algorithm and edge constraints, which effectively suppresses the halo artifacts and color deviation of the sky region in the dark channel a priori defogging algorithm. The experiments based on self-collected data and public datasets show that the algorithm in this paper presents better detail preservation ability (the visible edge ratio is minimally improved by 0.1305) and color reproduction (the saturated pixel ratio is reduced to about 0) in the subjective evaluation, and the average gradient ratio of the objective indexes reaches a maximum value of 3.8009, which is improved by 36–56% compared with the classical DCP and Tarel algorithms. The method provides a robust image defogging solution for computer vision systems under complex meteorological conditions. Full article

Cordyceps sinensis (C. sinensis) is widely recognized for its bioactive compounds and associated health benefits. However, due to its delicate nature, conventional chilled storage often results in the rapid degradation of valuable compounds, leading to loss of nutritional value and overall quality. This study integrated and evaluated comprehensive strategies: three gas-conditioning and two light-based preservation methods for maintaining both quality and nutritional integrity during 12-day chilled storage at 4 °C. The results revealed that vacuum packaging significantly inhibited weight loss (3.49%) compared to in the control group (10.77%) and preserved sensory quality (p < 0.05). UV-based interventions notably suppressed polyphenol oxidase and tyrosinase activities by 36.4% and 29.7%, respectively (p < 0.05). Modified atmosphere packaging (MAP) with 80% N₂ and 20% CO₂ (MAP-N₂CO₂) maintained higher levels of cordycepin (1.77 µg/g) and preserved energy charge above 0.7 throughout storage. The results suggest that MAP-based treatments are superior methods for the chilled storage of C. sinensis, with diverse advantages and their corresponding shelf lives associated with different gas compositions. Full article

The shelf life of minimally processed fresh (MPF) pears is affected by raw material characteristics and production factors. This study evaluated the effect of raw material storage (3 months in regular atmosphere [RA], 3 and 6 months in controlled atmosphere [CA]) on the organoleptic and functional quality of MPF pears packaged in polypropylene (PP) and low-density polyethylene (LDPE) for 0, 10, and 15 days at 0 °C. Wedges from 3-month CA showed the lowest respiratory activity (about 8.31 mg CO₂ kg⁻¹ h⁻¹), and those from 6-mounth CA maintained higher firmness after 15 days. Lightness decreased during storage, less so in harvest samples, which also showed less browning. Nevertheless, polyphenol oxidase (PPO) activity increased fivefold after 15 days. Total polyphenol content decreased by about 50% during storage. Wedges in PP packaging exhibited higher total antioxidant capacity (TAC) measured by DPPH than those in LDPE (15.55 and 13.77 mg EAA 100 g⁻¹ FW, respectively). In both, the contents were reduced after 15 days (15–38%). No differences in TAC were observed in the FRAP assay, where values remained unchanged. Significant correlations between PPO activity, TAC, and color variables suggest ongoing oxidative processes. In contrast to the effect of raw material storage, the type of packaging did not significantly affect any of the measured variables. Full article

Cementing operations are among the most critical steps in oil-well construction. When performed improperly, the integrity and useful life of the well can be significantly compromised. Light cement pastes are used to cement formations with a low fracture gradient to ensure zonal isolation and maintain the integrity of the casing. Extenders are additives used to reduce the density of cement pastes, ensuring that the paste has desirable properties before and after setting. This work aimed to evaluate the application of palygorskite clay as an additive in lightweight cement pastes for oil wells, highlighting how its fibrous morphology influences the microstructure and enhances the macroscopic properties of the hardened cement matrix. For this, the clay sample was initially characterized regarding its physicochemical properties using X-ray diffraction (XRD), X-ray fluorescence (XRF), thermogravimetry (TG), textural analysis (BET/N₂), and scanning electron microscopy (SEM). Lightweight pastes (1.56 g/cm³) were then formulated, varying the clay concentration by 1%, 3%, and 6% of the total mass. Cement pastes using bentonite were also formulated for comparison. Technological tests of atmospheric consistency, rheological behavior, free water, and stability were applied. It can be noted that the pastes formulated with palygorskite had lower viscosity, reflected in the reduced plastic viscosity and yield stress values, indicating easier flow behavior when compared with bentonite-based pastes. The pastes formulated with 6% palygorskite and 3% bentonite showed satisfactory stability and drawdown results. Therefore, applying palygorskite satisfies the minimum requirements for acting as an extending agent for lightweight cement pastes and is an option for application in oil-well cementing operations. Full article

In this study, Mn²⁺ and Eu²⁺-codoped Sr_3−xBa_xMgSi₂O₈ (x = 0–1.5) phosphors were synthesized at 1400 °C under a reducing atmosphere composed of 5% H₂ and 95% N₂ to produce materials with blue light emission. The resulting powders were characterized using several analytical techniques: X-ray diffraction (XRD) was employed to identify the crystalline phases, scanning electron microscopy (SEM) was used to observe the microstructure, and photoluminescence excitation (PLE) and emission (PL) spectra were measured using a fluorescence spectrophotometer. The results revealed several key findings. XRD analysis showed that the Sr₃MgSi₂O₈ (Sr_3−xBa_xMgSi₂O₈) phase coexisted with secondary phases of Sr₂SiO₄ and Sr₂MgSi₂O₇. SEM observations indicated that the synthesized powders exhibited a distinctive needle-like structure anchored on the surfaces of the particles. The PL and PLE intensities increased sharply as the BaO content increased from x = 0 to x = 0.6, followed by a more gradual increase, reaching a peak at x = 1.2. Additionally, as the value of x increased, the wavelengths corresponding to maximum PL and PLE intensities exhibited a blue shift, moving to shorter wavelengths. Further investigation focused on the excitation behavior by replotting the PLE spectra using energy (eV) as the x-axis. A Gaussian fitting function was applied to deconvolute the excitation bands, enabling an in-depth analysis of how compositional variations influenced the Stokes shift. Full article