Solids Content Research Articles

NIR spectroscopy for quality assessment and shelf-life prediction of kiwifruit

In this study, a non-destructive quality testing method along with shelf-life prediction of Xu Xiang ready-to-eat kiwifruit were developed using near-infrared spectroscopy (NIR) techniques. Several traditional quality indicators (hardness, soluble solids content, and dry matter) were evaluated. Partial least squares regression (PLS) was used to predict the intrinsic quality attributes of the samples. Competitive adaptive reweighted sampling algorithm (CARS) and uninformative variable elimination (UVE) algorithm were used to select the characteristic wavelengths. Prediction models for hardness, soluble solids content and dry matter were developed. The results showed that the prediction ability of the models could be improved by screening the characteristic wavelengths of CARS and UVE. Among them, the CARS-SNV-PLS model based on soluble solids had the best prediction ability (RMSEP of 0.430 and Rp2 of 0.958). Then, an NIR-based residual shelf-life prediction model was obtained by linking the measured quality indicators to the residual shelf-life, which was well validated with an RMSEP of 1.64 and an Rp2 of 0.939. Therefore, this study demonstrated the potential of combining CARS, SNV, and PLS for the non-destructive testing of ready-to-eat kiwifruit to provide technical support and solution.

Research on model transfer strategies based on the fusion of NIR-MIR spectral data

This study investigated the impact of different data fusion strategies on the performance of soluble solids content (SSC) prediction models based on near-infrared and mid-infrared spectroscopic techniques. In the data-level fusion approach, we applied standard normal variate and multiplicative scatter correction for pre-processing the NIR and MIR data. For the feature-level fusion, we utilized successive projections algorithm and competitive adaptive reweighted sampling to select informative wavelengths, and then applied direct orthogonal projection (DOP) for model transfer. The study employed a dataset of 150 honey samples to evaluate the impact of different data fusion strategies on model performance. To effectively evaluate model performance, we utilized the coefficient of R2 and RMSEP as evaluation metrics. By comparing the results of data-level fusion, feature-level fusion and single-spectrum model transfer, the results showed that spectral data fusion improved the model transfer performance compared to the single-spectrum approach, with feature-level fusion exhibiting the most significant advantages. The effective variable selection techniques in feature-level fusion successfully removed a substantial amount of interfering data and significantly reduced noise influence, thereby improving the model accuracy. Specifically, the use of feature-level fusion improved the predictive model’s R2 from 0.319 to 0.878 and reduced the RMSEP from 1.974 to 0.613°Brix, demonstrating the significant advantages of this approach in enhancing model transfer performance. The research findings provide important reference and theoretical support for future studies in the field of food quality assessment and other near-infrared spectroscopic data applications. This not only validates the effectiveness of the feature-level fusion approach, but also lays the foundation for establishing efficient and reliable predictive models.

Thermal chemical pretreatment of waste-activated sludge for enhanced solubilization and biogas production: a review

ABSTRACT Waste-activated sludge (WAS) generation is increasing due to the increased generation of wastewater owing to industrialization and urbanization. The disposal of WAS is a significant environmental and financial concern that can be offset by stabilization and valorization via anaerobic digestion (AD). However, the biodegradation is limited due to microbial cells and extracellular polymeric substances (EPS). Physical, chemical, biological, and hybrid pretreatments and the addition of accelerant materials for enhancing direct interspecies electron transfer (DIET) are among the strategies to overcome the poor biodegradation of WAS. Alkaline pretreatment disintegrates the floc structure of WAS by increasing the osmotic pressure, while microwave irradiation has thermal and a-thermal effects and increases the availability of organics for biodegradation. Moreover, the combination of alkaline and thermal pretreatments has synergic effects on solubilization, biogas production, and dewaterability. The disintegration of WAS is recognized by alteration in volatile solid (VS) content, sCOD, BOD/sCOD, turbidity, nutrients solubilization, dewaterability, particle size, specific surface area, change functional group, alteration in microorganism community, microorganism abundance, color, moisture content, lag phase, and biogas production. Higher doses of pretreatment increase COD solubilization but not biodegradable COD. Maximum COD solubilization ranged from 2 to 37% in alkaline, 21 to 260% in the microwave (MW), and 28 to 624% in hybrid pretreatments.

Phosphoproteomic Analysis Indicates Phosphorylated Proteins in Response to Postharvest Blueberries Fruit Softening during Shelf Life.

Postharvest blueberry fruit is prone to softening. Protein phosphorylation is an important post-translational modification that was involved in fruit softening. However, little is known about protein phosphorylation in postharvest blueberry fruit softening. The firmness, the apparent morphology, and cell structures of blueberry fruit were changed. As the decay rate of postharvest blueberry fruit increased, the soluble solid and titrable acid contents decreased significantly. Phosphoproteomic sequencing results showed that there were 4100 phosphorylated peptides, 5635 phosphorylated sites, and 1437 phosphorylated proteins and showed significant differences on 0 and 8 d. The GO database and KEGG pathway results indicated that these phosphorylated proteins were mainly involved in "biological process", "molecular function", "plant hormone signal transduction", and "metabolic pathways". Besides, a number of phosphorylated proteins were found in cell wall metabolism, plant hormone signaling, primary metabolism, energy metabolism, membrane and transport, ubiquitination-based proteins, and other metabolisms.

Characterization of flowback and produced water from shale oil and gas wells fractured with different levels of recycled water

ABSTRACT Hydraulic fracturing requires large volumes of water, and it is therefore crucial to establish sustainable water sources. We analyzed the flowback and water produced from three wells using different fresh-to-recycled water ratios for hydraulic fracturing: freshwater only, 20% recycled water, and one-seventh (∼15%) recycled water. Water samples were collected over a 36-day period (flowback started on day 0). There were no significant differences between the total organic carbon (TOC) levels of the wells, but the total dissolved solid (TDS) concentrations increased for all wells over time, and there were significant differences among the wells. The TDS level of the well fractured with 20% recycled water was significantly higher than that of the other wells. Liquid chromatography quadruple time-of-flight mass spectrometry revealed ethoxylated functional groups in all three wells. Agilent qualitative analysis software B.06.00 was used to perform a qualitative analysis based on the exact mass of organic compounds within 1 ppm mass accuracy. The results of this study provide new insights into the quality of flowback and produced water from wells fractured using different fresh-to-recycled water ratios and can be used as a reference for improving the reusability of treated water and reducing wastewater discharge.

Enhancing fruit SSC detection accuracy via a light attenuation theory-based correction method to mitigate measurement orientation variability

Nondestructive online detection and sorting for fruit quality has gradually attracted attention in the global agro-product industry. However, the detection accuracy is influenced by many factors, such as fruit orientation, fruit shape, and environmental fluctuations. This study aimed to explore the impact of measurement orientation variation on spectra and soluble solids content (SSC) detection in apples and propose a correction method to mitigate the effect. Firstly, the visible/near-infrared (Vis/NIR) spectra ranging from 550 to 950 nm were collected in four orientations. Then, calibration models were developed for each orientation separately (local models) and all orientations corporately (global models) to evaluate and compensate for the effect of orientation. After that, the novel method based on the light attenuation theory was introduced to correct the acquired raw spectra and establish corrected orientation models. Results showed that measurement orientation significantly altered spectral intensity due to variations in surface curvature and optical path, thus declining models’ predictive power and robustness. Global models proved to be less susceptible to orientation variation compared with local models. The performance of both local and global models considerably improved post-orientation correction, attributed to the decrease of spectral distribution difference, with their average Rp2 and RPD increased by 93.38 % and 8.11 %, 10.56 % and 10.57 %, respectively, while the average RMSEP decreased by 16.01 % and 10.78 %, respectively. Overall, this work provides a more cost-effective and universal approach to impair the influence of measurement orientation and improve the accuracy and reliability of fruit quality online detection.

A simple EMMS drag model for the simulation of bubbling fluidized beds using mesoscience-based structural model

State-of-the-art EMMS drag model for bubbling fluidization needs an empirical correlation for bubble diameter. In this short communication, an EMMS drag model is developed to predict the effective drag coefficient without the use of an empirical correlation for bubble diameter. The model is then coupled with mesoscience-based structural model to simulate the hydrodynamics of three bubbling fluidized beds, it is shown that the bed hydrodynamics can be predicted reasonably well, in terms of axial and radial solid concentration profiles. Present study establishes an effective and simple model for simulating bubbling fluidization using mesoscience-based structural model.

Performance of oriented strand board bonded with a hybrid phenol-formaldehyde/polymeric methylene diphenyl diisocyanate adhesives system

A hybrid adhesive system composed of phenol-formaldehyde (PF) resin and polymeric methylene diphenyl diisocyanate (pMDI), modified with two types of alkaline catalysts, namely NaOH and CaCO3 at 20% (w/v), was used for manufacturing the oriented strand board (OSB) from sengon (Paraserianthes falcataria L. Nielsen) wood. The catalyst was added at a concentration of 1% of the solids content of PF adhesive, and pMDI was added at 2.5% and 5.0% of the PF adhesive solids content. Adding catalysts and cross-linking agents increased the solids content and viscosity of the adhesive and accelerated the gelation time. The water absorption of OSB increased with the addition of catalysts and crosslinking agents compared to the control PF. Still, the CaCO3 catalyst worked optimally in reducing the thickness swelling of OSB. The mechanical properties of the laboratory-fabricated OSB panels increased with the addition of catalyst and cross-linker, except for the modulus of elasticity parallel to the grain. The optimal performance of OSB was obtained by adding 1% CaCO3 and 2.5% pMDI based on the PF’s solids content.

Energy recovery of residual yeast via hydrothermal liquefaction with multi-cycle reuse of the post-HTL wastewater and subsequent anaerobic digestion

Coupling hydrothermal liquefaction (HTL) with anaerobic digestion (AD) could be an interesting alternative for the energetic reuse of residual yeast derived from ethanol production, generating two valuable biofuels to diversify the global energy matrix. A central composite rotational design 23 optimized residual yeast HTL. The independent variables were temperature (300–400 °C), retention time (30–60 min), and solid content (5–12 wt%). The principal response variable was bio-oil yield. Three recirculation cycles of post-HTL wastewater (PHW) into the HTL reaction were investigated to enhance the energy recovery. The methanogenic potential of PHWs from recirculation cycles was then determined at mesophilic temperatures. During HTL, the bio-oil yield remained constant, while the volume of PHW decreased with recirculation cycles. The organic matter and total nitrogen present in the PHW were reduced until Cycle 2. The highest energy recovery in HTL was achieved at Cycle 0. However, the highest energy recovery in AD was attained at AD-Cycle 2, showing an approximately ∼14 % increase compared to AD-Cycle 0 (no recirculation). The total energy recovery for HTL-AD was higher in both Cycle 0 and Cycle 2, with Cycle 0 being more advantageous regarding net energy recovery from the products. In contrast, Cycle 2 offered more significant energy recovery and sustainability benefits.

Distribution of microplastics between ice and water in aquatic systems: The influence of particle properties, salinity and freshwater characteristics

Microplastics (MPs) are an anthropogenic emerging pollutant, with global contamination of both marine and freshwater systems extensively documented. The interplay of MP particle properties and environmental conditions needs to be understood in order to assess the environmental fate and evaluate mitigation measures. In cold climate, ice formation has appeared to significantly affect the distribution of MPs, but so far, limited research is available comparing different aquatic systems, especially freshwater. Experiments often rely on artificial water and specific MP model particles. This study used laboratory tests to investigate the ice-water distribution of a variety of environmentally relevant MP particle types (PP, PE, PS and PVC fragments (25–1000 μm), PET fibers (average length 821 μm, diameter 15 μm)) across different water types, including artificial water of high and low salinity, as well as natural water from a lake and a treatment wetland. Overall, ice entrapment of MPs occurred in almost all tests, but the ice-water distribution of MPs differed across the different water types tested. Among the tests with artificial water, salinity clearly increased MP concentrations in the ice, but it cannot be resolved whether this is caused by increased buoyancy, changes in ice structure, or thermohaline convection during freezing. In the natural freshwater tests, the partition of MPs was shifted towards the ice compared to what was seen in the artificial freshwater. The influence of different types of dissolved and particulate substances in the different waters on MPs fate should be considered important and further explored. In this study, the higher content of suspended solids in the lake water might have enhanced MP settling to the bottom and thereby contributed to the absence of MPs in the ice of the lake test, compared to the wetland test with low suspended solids and considerably more MPs in the ice. Furthermore, the higher negative charge in the lake water possibly stabilized the negatively charged MPs in suspension, and reduced ice entrapment. Regarding particle properties, shape had a distinct effect, with fibers being less likely incorporated into ice than fragments. No fibers were found in freshwater ice. However, it became clear that ice entrapment of MPs depends on factors other than the particles' buoyancy based on density differences and particle size and shape alone.

Combined application of the endophyte Bacillus K1 and sodium dehydroacetate alleviates postharvest gray mold in grapes

Botrytis cinerea, which causes postharvest gray mold, is a primary pathogen that limits grape shelf-life and consumption and causes substantial yield loss worldwide. The combined use of biocontrol agents and food additives has attracted increasing interest. The effects of combined treatment with the endophyte Bacillus subtilis K1 and sodium dehydroacetate (SD) on the occurrence of gray mold and maintenance of grape fruit quality were studied. Treatment with a K1 suspension (1 × 108 CFU/ml) combined with 0.32 g/L SD resulted in markedly improved control of B. cinerea on grapes. The disease incidence and severity in the groups treated with K1 alone or in combination with SD were significantly lower than those in the control groups (P < 0.05) when the mixtures were applied 2 h after pathogen inoculation. Moreover, application of the mixture could maintain the appearance, firmness, total soluble solid (TSS) content and titratable acidity (TA) of grape fruit. Furthermore, the combination triggered increases in the activities of defense-related enzymes such as peroxidase (POD), phenylalanine ammonia lyase (PAL), catalase (CAT), superoxide dismutase (SOD) and polyphenol oxidase (PPO). Additionally, it could increase the vitamin C content. Thus, appropriate combinations of biocontrol agents and chemical reagents can provide effective protection against postharvest decay.

New insights in the flavor and chemistry of Huanglongbing tolerant citrus hybrids with/without Poncirus trifoliata in their pedigree

IntroductionCitrus hybrids with Poncirus trifoliata L. Raf. introgression have gained interest due to their tolerance to Huanglongbing (HLB), a devastating disease for Florida citrus agriculture. While these hybrids inherit disease tolerance from P. trifoliata, they sometimes also suffer from undesirable off-flavors.MethodsA selection of thirteen genotypes were harvested over the 2020-2021 and 2021-2022 seasons. Their juices were evaluated by a trained sensory panel and were comprehensively analyzed for their chemical makeup, including soluble solids content (SSC), titratable acidity (TA), volatiles, flavonoids and limonoids.Results &amp;amp; discussionOverall, along with the commercial orange cultivars ‘Valencia’ and ‘Hamlin’, the HLB-tolerant Poncirus hybrid ‘US SunDragon,’ and the mandarin hybrids Sugar Belle®, FF-5-51-2, and ‘US Superna’ had positive citrus flavor quality. Esters, some sesquiterpenes, along with flavonoids, eriocitrin and quercetin-3-(3R-glucosylrutinoside), were positively correlated with orange flavor while β-ionone and eucalyptol were highly abundant in the mandarins. The flavonoid linarin, was more abundant in Poncirus hybrids with off-flavors than in the Poncirus hybrid ‘US SunDragon’, having high orange flavor. Two mandarin hybrids, FF-5-6-36 and FTP-6-32-67, were not bitter at harvest, but the juice exhibited delayed bitterness after storage at -20°C, which was associated with significant increases of limonin, nomilin, naringenin, and prunin. Interestingly, during freezer storage, a newly identified flavonoid in citrus, tricin-C-hexoside, increased dramatically across all of the genotypes. The identification of disease-tolerant hybrids with satisfactory flavor quality at juicing as well as after storage where delayed bitterness may develop, has great significance for future breeding efforts for fresh fruit or for use in stand-alone juice/juice blends.

Salicylic Acid Treatment Ameliorates Postharvest Quality Deterioration in 'France' Prune (Prunus domestica L. 'Ximei') Fruit by Modulating the Antioxidant System.

The potential of salicylic acid (SA) in delaying postharvest fruit senescence has been extensively documented; nevertheless, its effect on antioxidant activity and quality of 'France' prune fruit is largely unknown. The study investigated the effects of SA (0.5 mM) on postharvest quality deterioration of 'France' prune fruit. Results indicated that SA impeded the increase in respiration rate and weight loss, and mitigated the decrease of soluble solids content (SSC), titratable acidity (TA) content, firmness, and hue angle. SA sustained the ascorbate-glutathione cycle by inducing the production of ascorbic acid (AsA) and glutathione (GSH) and attenuates flavonoids, total phenols, and anthocyanins degradation by inhibiting polyphenol oxidase (PPO) activity and PdPPO. Moreover, SA significantly improved superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), peroxidase (POD), and glutathione reductase (GR) activities and gene expression levels, sustained higher 2,2'-Azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS) and 1,1-diphenyl-2-picryl-hydrazyl (DPPH) free radical scavenging capacity, ferric reducing antioxidant power (FRAP), and hydroxyl radical (·OH) inhibition capacity, and impeded the production of hydrogen peroxide (H2O2) and superoxide anion (O2•-). Overall, SA improved the antioxidant capacity by inducing the synthesis of defense response-related substances and promoting antioxidant enzyme activities to sustain the storage quality of 'France' prune fruit.

Development of Flexible and Partly Water-Soluble Binder Systems for Metal Fused Filament Fabrication (MF3) of Ti-6Al-4V Parts.

Metal Fused Filament Fabrication provides a simple and cost-efficient way to produce dense metal parts with a homogenous microstructure. However, current limitations include the use of hazardous and expensive organic solvents during debinding for flexible filaments the stiffness of filaments made from partly water-soluble binder systems. In this study, the influence of various additives on different partly water-soluble binder systems, with regard to the flexibility and properties of the final parts, was investigated. Furthermore, a method using dynamic mechanical analysis to quantify the flexibility of filaments was introduced and successfully applied. For the first time, it was possible to produce flexible, partly water-soluble filaments with 60 vol.% solid content, which allowed the 3D printing of complex small and large parts with a high level of detail. After sintering, density values of up to 98.9% of theoretical density were achieved, which is significantly higher than those obtained with existing binder systems.

Ultrasound assessment of gastric content in elective surgery

Objective: To determine the prevalence of patients with ultrasound signs of a full stomach during surgery at the Sominé Dolo Hospital in Mopti. Methodology: Observational study investigated prospective, single-center over a period of one month include patients in surgery program aged 18 to 85 years. Our data was collected on individual survey sheets and analysed with the Epi info7 software. Result: Out of a total of 140 patients, 41 patients were included in our study, i.e. a frequency of 29.28%. The mean age of patients was 38 years +/-17. The average body mass index was 23+/- 4.65. Females predominated: 60.98% (n=25) compared to 39.02% (n=16) for males, with a sex ratio of 0.6/1. The ASA classification was rated at II in 51.22% of patients (n=21). The gastric antrum was visualized in 40 patients, i.e. an ultrasound sensitivity of 97.56%, of which seven (07) were difficult to see and not visualized in one patient. We found a relationship between high BMI and difficulty in visualizing gastric contents (P-value = 0.00001), but no relationship was found between BMI and Perlas score (P-Value = 0.75411). The Perlas score was rated at 0 in 85% (n=34), fluid content was found in 12.5% (n=5) of patients while one patient had solid content. Patients observed an estimated preoperative fasting duration of an average of 11 hours +/- 2.86. Conclusion: Despite the implementation of a preoperative fasting protocol, cases of full stomachs are still to be feared and the ultrasound at the bedside of patients is a simple, quick examination to best adjust the anesthesia protocol. Keywords: full stomach, gastric antrum, ultrasound, Perlas score, Mopti.

Regulation of crop load and quality in sweet cherry cv. ‘Sweet Heart’ using blossom thinning

ABSTRACT Self-fertile cultivars of sweet cherry (Prunus avium) produce heavy crop load that is often associated with small and poor-quality fruits. Therefore, a crop load-management strategy is required to improve the quality of the fruit. In this study, the effect of blossom thinners on fruit set, yield and quality of the fruits was evaluated. Three types of blossom thinners were used at three different concentrations viz., ammonium thiosulphate (ATS) (1, 1.5 and 2%), naphthaleneacetic acid (NAA) (20, 40 and 60 ppm) and corn oil emulsion (1, 2 and 3%). These were sprayed at 80% of the bloom stage. The vegetative, flowering, fruit set and yield parameters were observed and recorded. Fruit quality was evaluated by measuring the physical and chemical characteristics of the fruits at the harvest stage. Negative correlation was found between fruit set and quality of fruit. The reduction in the crop load was associated with enhanced vegetative growth, including higher leaf:fruit ratio, higher supply and availability of photosynthates to the remaining fruitlets and reduced fruit firmness and titratable acidity. Fruit size, weight, volume, hue value, chroma value, soluble solid content (SSC), total sugars, SSC/acid ratio, anthocyanin and ascorbic acid content were enhanced as a result of thinning. The foliar spray of ATS at 2% and NAA at 60 ppm, at 80% bloom proved to be the most effective in reducing crop load and enhancing the fruit quality.

Mitigation of Membrane Fouling in Membrane Bioreactors Using Granular and Powdered Activated Carbon: An Experimental Study

This experimental study explores the mitigation of membrane fouling in membrane bioreactors (MBRs) through the combined use of granular activated carbon (GAC) and powdered activated carbon (PAC). The research assesses the impact of these materials on the fouling resistance, critical flux, and permeate quality using various mixed liquor suspended solids concentrations and carbon dosages. The results indicate that the GAC-PAC combination significantly reduces the total filtration resistance, particularly the cake layer resistance, by 11.7% to 13.6% compared to setups without activated carbon or with the individual carbon types. The study also reveals that this combination decreased the fouling rate by 15% to 24% at critical flux steps, demonstrating substantial improvements in fouling mitigation and operational efficiency. Furthermore, the GAC-PAC combination, which produces an adsorption process, enhances the permeate quality, achieving the near-complete removal of organic matter, total nitrogen, and turbidity, with total phosphorus removal reaching 99%. These findings demonstrate that the combined use of GAC and PAC not only reduces membrane fouling but also improves the overall MBR performance, making it a viable strategy for enhancing the efficiency of wastewater treatment processes.

Technology of preparation and determination of the properties of kvas from table beet for use in bakery

In connection with the deterioration of the health of the population of Ukraine, the primary task should be to enrich the usual diet with products of functional purpose and to add natural biologically active additives that contribute to the removal of radionuclides, toxins, normalization of the body's systems and increased immunity. This work is devoted to the study of the process of beet processing and its further use in the bakery and confectionery industries. The refractometric method was used to determine the content of soluble solids. The content of trace elements was determined using the atomic adsorption method. When preparing kvass from table beets, additional raw materials were added: sprouted flax seeds, whey, yeast, viburnum powder, rye bread crackers. It was established that the variety of the Dutch selection Roket differs from the varieties Bordeaux 237 and Cylindra in terms of dry matter, organic acids, dyes and sugars. It is important to note that when improving kvass preparation technology, optimal fermentation conditions and dosing of additives are taken into account in order to maximize the shelf life of the product without losing its quality. In view of the increase in the number of genetic and complicated diseases, it is worth noting the introduction of specialized dietary programs, which are gaining more and more relevance. Such programs have been found to ensure food security and meet all essential nutrient needs. Considered the problem of the need for constant improvement of recipes of food products, study of new gluten-free alternatives and provision of access to high-quality gluten-free products. Studies have proven that the use of natural raw materials in the production of beet kvass is an effective means of improving its quality characteristics. Therefore, a promising direction in the production of flour products is the improvement of the recipe of the existing assortment due to the use of natural plant components of increased biological value. Kvass from table beet can be a source of natural biologically active substances (BAR). Table beets have a rich chemical composition. The nutritional value of beets is additionally balanced by the content of sugars and acids (citric and oxalic), the content of organic substances, minerals and vitamins. The production of bakery products using kvass from table beet as a natural food additive is relevant today.

3D inkjet printing of hybrid electroactive ink based on molecularly imprinted polymers for lipopolysaccharides detection

A hybrid electroactive ink based on molecularly imprinted polymer (MIP) hollow microparticles, zinc oxide nanoparticles (ZnO NPs) and conductive carbon paste (CP) is reported herein for the first time. The MIP/ZnO NPs/CP and corresponding non-imprinted NIP/ZnONPs/CP modified inks were screen-printed on plastic substrates via 3D inkjet technology to cover around 40 working screen-printed carbon electrodes (SPCE) pieces in a single batch. The custom-made electrochemical MIP/ZnONPs/CP@SPCE sensor was designed for the detection of bacterial endotoxins, i.e., lipopolysaccharides (LPS), derived from Pseudomonas aeruginosa. Hollow MIP silica microparticles with specific properties for 3D printing application, in terms of granulation and morphology, were synthesized via sol-gel method using tetraethyl orthosilicate and (3-aminopropyl) triethoxysilane as monomers. Following the structural and morphological characterization of microparticles, the evaluation of template rebinding indicated a clear specificity of MIPs for LPS compared to the NIPs. Hybrid MIP/ZnONPs/CP and NIP/ZnONPs/CP inks were characterized using morphological and structural methods, which confirmed a viscosity of 25.000 mPa.s, a granulation of <20 µm, and a solid powder content of <27 %, as well as a homogenous incorporation of MIP particles and ZnONPs in the conductive CP. Finally, the electrochemical evaluation of the modified MIP/ZnONPs/CP@SPCE sensor revealed a good sensitivity to LPS molecules in PBS at pH 7.4, in the linear working range 1 - 100 µM, where a 0.058 µM limit of detection (LOD) and a response time less than or equal to 1 min were determined. The selectivity of the MIP/ZnONPs/CP@SPCE sensor towards LPS from Salmonella enterica and Escherichia coli was also assessed, highlighting a clear difference between these structural resembling species.

Chitosan-graft-poly(vinyl acetate) for wood-adhesive applications

Poly(vinyl acetate), PVAc, adhesives are commonly used for wood bonding; however, they are fossil-based and the final products usually do not have a sufficient water resistance for more durable applications. In this study we prepared an adhesive formulation by grafting VAc from chitosan using emulsion polymerization, chitosan-graft-PVAc. Thereby, we could decrease the fossil-based content of the adhesive and at the same time significantly improve the water resistance. Chitosan by itself has very good bonding properties as a wood adhesive, especially regarding water resistance; however, very low solid contents of the adhesive formulation can be achieved due to a very high viscosity of chitosan adhesives. In our chitosan-graft-PVAc adhesives, we explored two chitosan samples with different molecular weights, by using as-received chitosan and hydrolyzing it to a lower molecular weight. The chitosan fractions in the adhesives prepared with a higher molecular weight chitosan were 15, 20 and 25 wt%. However, due to the high viscosity, a solid content higher than 17 wt% could not be achieved for these adhesives. Sufficient bond strengths were achieved when the adhesive was applied in 122 g/m2 solid spread rate. In order to decrease the viscosity, we used hydrolyzed chitosan, with a lower molecular weight, to allow for a higher adhesive solid content, 34 wt%, and for a higher chitosan fraction, 40 wt%. In the adhesive with 40 wt% chitosan and 17 wt% solid content, all VAc was grafted from chitosan. This decreased the molecular mobility of the chains, leading to a lower susceptibility to plastic creep in the adhesive which contributes to the final bond strength. The dry and wet strengths of the specimens bonded with adhesives containing chitosan were higher than the strength of the specimens bonded with the reference PVAc adhesive.