Sulfites play imperative roles in food crops and food products, serving as sulfur nutrients for food crops and as food additives in various foods. It is necessary to develop an effective method for the on-site quantification of sulfites in food samples. Here, 7-(diethylamino) quinoline is used as a fluorescent group and electron donor, alongside the pyridinium salt group as an electron acceptor and the C=C bond as the sulfite-specific recognition group. We present a novel fluorescent sensor based on a mechanism that modulates the efficiency of intramolecular charge transfer (ICT), CY, for on-site quantitative measurement of sulfite in food. The fluorescent sensor itself exhibited fluorescence in the near-infrared light (NIR) region, effectively minimizing the interference of background fluorescence in food samples. Upon exposure to sulfite, the sensor CY displayed a ratiometric fluorescence response (I447/I692) with a high sensitivity (LOD = 0.061 μM), enabling accurate quantitative measurements in complex food environments. Moreover, sensor CY also displayed a colorimetric response to sulfite, making sensor CY measure sulfite in both fluorescence and colorimetric dual-signal modes. Sensor CY has been utilized for quantitatively measuring sulfite in red wine and sugar with recoveries between 99.65% and 101.90%, and the RSD was below 4.0%. The sulfite concentrations in live cells and zebrafish were also monitored via fluorescence imaging. Moreover, the sulfite assimilated by lettuce leaves was monitored, and the results demonstrated that excessive sulfite in leaf tissue could lead to leaf tissue damage. In addition, the sulfate-transformed sulfite in lettuce stem tissue was tracked, providing valuable insights for evaluating sulfur nutrients in food crops. More importantly, to accomplish the on-site quantitative measurement of sulfite in food samples, a portable sensing system was prepared. Sensor CY and the portable sensing system were successfully used for the on-site quantitative measurement of sulfite in food.

Quality and safety monitoring in the dairy industry is required to ensure products meet a high-standard based on legislation and customer requirements. The need for non-destructive, low-cost and user-friendly process analytical technologies, targeted at operators (as the end-users) for routine product inspections is increasing. In recent years, the development and advances in sensing technologies have led to miniaturisation of near infrared (NIR) spectrometers to a new era. The new generation of miniaturised NIR analysers are designed as compact, small and lightweight devices with a low cost, providing a strong capability for on-site or on-farm product measurements. Applying portable and handheld NIR spectrometers in the dairy sector is increasing; however, little information is currently available on these applications and instrument performance. As a result, this review focuses on recent developments of handheld and portable NIR devices and its latest applications in the field of dairy, including chemical composition, on-site quality detection, and safety assurance (i.e., adulteration) in milk, cheese and dairy powders. Comparison of model performance between handheld and bench-top NIR spectrometers is also given. Lastly, challenges of current handheld/portable devices and future trends on implementing these devices in the dairy sector is discussed.

The characteristics of heat transfer load from the non-air-conditioned (NAC) area can help to understand the complex airflow movement and thermal physical mechanisms inside large space buildings. Based on building energy modeling, the indoor thermal environment and building energy consumption of a plant for computerized numerical control (CNC) machine tools are studied. Considering the form of the stratified air-conditioning system and the phenomenon of heat retention near the roof in the plant, the double zone and triple zone models are established. The vertical air temperature, the parameters of the terminal of the air-conditioning system and the heat/cool source system of the plant in summer and winter were measured on site, which verifies the accuracy of the established model. Based on the validated model, the proportion of heat transfer load from the NAC area is calculated, at the range of about 60%-85%. The positive influence of the roof heat transfer coefficient on the sensible heat load in the NAC area is revealed. The recommended value of the non-dimensional zone-mixing flow rate between the air-conditioned (AC) and NAC areas is given, with 30% (in summer). The results of this work can help understand the composition of the stratified air-conditioning load in large spaces and optimize the design of air distribution.

Estimation of construction waste generation (CWG) at the field scale is a crucial but challenging task for effective construction waste management (CWM). Extant field-scale CWG modeling approaches have faced difficulties in obtaining accurate results due to a lack of detailed CWG data, and most of them fail to consider the complex relationship among predictive variables. This study attempts to tackle this issue by proposing a novel CWG modeling approach that integrates improved on-site measurement (IOM) and a support vector machine (SVM)-based prediction model. To achieve this goal, 206 ongoing commercial construction sites were investigated to obtain the predictor values and waste generation rates (WGRs) of five types of waste (i.e., inorganic nonmetallic waste, organic waste, metal waste, composite waste, and hazardous waste) generated at three construction stages (i.e., the understructure stage, superstructure stage, and finishing stage). The data were introduced to the SVM to develop the relationships between predictive variables and WGRs. An actual commercial building under construction was used to demonstrate the applicability of the proposed approach. The results showed that the superiority of the IOM can be used as a basis to implement robust CWG data collection. In addition, the SVM-based WGR prediction model (SWPM) can obtain more accurate prediction results (R2 = 86.87%) than the back-propagation neural network (R2 = 75.14%) and multiple linear regression (R2 = 61.93%).

Recently, there has been a growing demand to develop portable devices for the fast detection of contaminants in food safety, healthcare, and environmental fields. Herein, two biosensing methods were designed by the use of nicotinamide adenine dinucleotide phosphate (NAD(P)H)-dependent TetX2 enzyme activity and thionine as an excellent electrochemical and colorimetric mediator/probe to monitor tetracycline (TC) in milk. The nanoporous glassy carbon electrode (NPGCE) modified with polythionine was first prepared by electrochemically and then TetX2 was immobilized onto the NPGCE using polyethyleneimine. The prepared biosensor provided a high electrocatalytic response toward NAD(P)H by significantly reducing its overpotential. The proposed biosensor exhibited a detection limit of 40 nM with a linear range of 0.1-0.8 μM for TC determination. Besides, the thionine probe was used to develop a novel colorimetric assay using a simple enzymatic color reaction within a few minutes. The limit of detection for TC was experimentally achieved as 60 nM, which was lower than the safety levels established by the World Health Organization (225 nM). The correlation between change in the color of the solution and the concentration of TC was used for quality control of milk samples, as confirmed by the standard high-performance liquid chromatography method. The results show the great potential of the proposed assays as portable instruments for on-site TC measurements.

Airborne transmission is a main spread mode of respiratory infectious diseases, whose frequent epidemic has brought serious social burden. Identifying possible routes of the airborne transmission and predicting the potential infection risk are meaningful for infectious disease control. In the present study, an internal spread route between horizontal adjacent flats induced by air infiltration was investigated. On-site measurements were conducted, and tracer gas technique was employed. Two measurement scenarios, closed window mode and open window mode, were compared. Using the calculated air change rate and mass fraction, the cross-infection risk was estimated using the Wells-Riley model. It found that tracer gas concentrations in receptor rooms are one order lower than the source room, and the infection risks are also one order lower. Opening windows results in larger air change rate on the one hand, but higher mass fraction on the other hand. Higher mass fraction not necessarily results in higher infection risk as the pathogen concentration in the source room is reduced by the higher air change rate. In the present study, opening windows could significantly reduce the infection risk of the index room but slightly reduce the risks in receptor rooms. The mass fraction of air originated from the index room to the receptor units could be 0.28 and the relative cross-infection risk through the internal transmission route could be 9%, which are higher than the external spread through single-sided window flush. The study implicates that the horizontal transmission route induced by air infiltration should not be underestimated.

This study conducted on-site measurements of indoor volatile organic compounds (VOCs) in 251 occupied residences in China, with multiple visits throughout a whole year. Over 1000 samples were collected for measurement of VOCs in 8 cities, covering different climate regions. Overall, the concentrations of total VOCs (TVOCs) in occupied residences are in the range of 104-1151 μg/m3, with 20% of the samples over the Chinese standard of 600 μg/m3. A higher concentration was evident in the summer (mean = 705 μg/m3) compared to other seasons, especially winter (mean = 289 μg/m3). The TVOCs of residences in areas with central heating (severe cold regions and cold regions) are generally higher than those in areas without central heating. In winter, temperature was the dominant factor, whereas in summer, the building infiltration rate was the key factor influencing the indoor TVOC levels. The TVOCs concentration was also found to be directly proportional to the city economy level. Twenty-nine VOC species with a detection frequency higher than 40% were identified in all samples. Toluene is the most common VOC, with the highest detection rate (90%). The median concentration for a single VOC was between 1 and 14 μg/m3. Aldehydes were found to be the largest contributors to total VOCs in the Chinese residential buildings (mass proportion 22%), followed by benzene series (20%), alkenes (18%), and alkanes (15%). Aldehydes, especially long-chain saturated carbonyls, are likely to be the characteristic VOCs in the Chinese dwellings, with Chinese cooking as the major emission source. In addition, n-butane/i-butane showed maximum concentration in some residences (approximately 105 μg/m3 higher than other VOCs) owing to cooking fuel.

The magnitude of the thermal stresses that originate in an acrylic-based repair material used for the reprofiling of natural sandstone is analyzed. This kind of artificial stone was developed in the late 1970s for its peculiar property of reversibility in an organic solvent. However, it displays a high thermal expansion coefficient, which can be a matter of concern for the durability either of the repair or of the underlying original stone. To evaluate this risk we propose an analytical solution that considers the viscoelasticity of the repair layer. The temperature profile used in the numerical evaluation has been measured in a church where artificial stone has been used in a recent restoration campaign. The viscoelasticity of the artificial stone has been characterized by stress relaxation experiments. The numerical analysis shows that the relaxation time of the repair mortar, originating from a low T g , allows relief of most of the thermal stresses. It explains the good durability of this particular repair material, as observed by the practitioners, and provides a solid scientific basis for considering that the problem of thermal expansion mismatch is not an issue for this type of stone under any possible conditions of natural exposure.

Carbamazepine is an antiepileptic drug that can be used as a marker for the cleaning efficiency of wastewater treatment plants. Here, we present the optimization of a fast and easy on-site measurement system based on fluorescence polarization immunoassay and the successful application to wastewater. A new monoclonal highly specific anti-carbamazepine antibody was applied. The automated assay procedure takes 16 min and does not require sample preparation besides filtration. The recovery rates for carbamazepine in wastewater samples were between 60.8 and 104% with good intra- and inter-assay coefficients of variations (less than 15 and 10%, respectively). This automated assay enables for the on-site measurement of carbamazepine in wastewater treatment plants.