Changes In Physicochemical Properties Research Articles

Soil microbial community structure, function and network along a mangrove forest restoration chronosequence

Mangrove forests have high ecological, social and economic values, but due to environmental changes and human activities, natural mangrove forests have experienced serious degradations and reductions in distribution area worldwide. In the coastal zones of southern China, an introduced mangrove species, Sonneratia apetala, has been extensively used for mangrove restoration because of its rapid growth and strong environmental adaptability. However, little is known about how soil microorganisms vary with the restoration stages of the afforested mangrove forests. Here, we examined the changes in soil physicochemical properties and microbial biomass, community structure and function, and network in three afforested S. apetala forests with restoration time of 7, 12, and 18 years and compared them with a bare flat and a 60-year-old natural Kandelia obovata forest in a mangrove nature reserve. Our results showed that the contents of soil salinity, organic carbon, total nitrogen, ammonium nitrogen, and microbial biomass increased, while soil pH and bacterial alpha diversity decreased with afforestation age. Soil microbial community structure was significantly affected by soil salinity, organic carbon, pH, total nitrogen, ammonium nitrogen, available phosphorus, and available kalium, and susceptibility to environmental factors was more pronounced in bacterial than fungal community structure. The relative abundances of aerobic chemoheterotrophy were significantly higher in 12- and 18-year-old S. apetala than in K. obovata forest, while that of sulfate-reducing bacteria showed a decreasing trend with afforestation age. The abundance of dung saprotroph was significantly higher in 12- and 18-year-old S. apetala forests than in the natural forest. With the increasing afforestation age, the modularity of microbial networks increased, while stability and robustness decreased. Our results suggest that planting S. apetala contributes to improving soil fertility and microbial biomass but may make soil microbial networks more vulnerable.

Changes in physicochemical properties and formation process of colloidal nanoparticles (CNPs) during the lamb soup stewing

Colloidal nanoparticles (CNPs), as carriers of nutrients, naturally exist in food or form during cooking. In this study, the colloidal properties, structures, rheological properties, and chemical composition location of CNPs were analyzed during 15 min to 5 h lamb soup stewing. With the increasing stewing time, the particle size and absolute value of the zeta potential of CNPs increased, indicating that CNPs became more stable. As the stewing time increased, the blue-shifted Fourier transform infrared spectroscopy absorption peaks and the red-shifted fluorescence spectroscopy absorption peaks certificated the structural changes in CNPs. And α-helix and β-turn content decreased, while β-sheet and random coil content increased in processing, potentially resulting in the opening CNPs structures. In addition, our findings revealed that proteins were encapsulated within the lipids in the inner part, while carbohydrates were dispersed in the outermost layers of the CNPs with a phospholipid bilayer.

Anomalous Pressure Response of Temperature-Induced Spin Transition and a Pressure-Induced Spin Transition in Two-Dimensional Hofmann Coordination Polymers.

Spin transition (ST) compounds have been extensively studied because of the changes in rich physicochemical properties accompanying the ST process. The study of ST mainly focuses on the temperature-induced spin transition (TIST). To further understand the ST, we explore the pressure response behavior of TIST and pressure-induced spin transition (PIST) of the 2D Hofmann-type ST compounds [Fe(Isoq)2M(CN)4] (Isoq-M) (M = Pt, Pd, Isoq = isoquinoline). The TISTs of both Isoq-Pt and Isoq-Pd compounds exhibit anomalous pressure response, where the transition temperature (T1/2) exhibits a nonlinear pressure dependence and the hysteresis width (ΔT1/2) exhibits a nonmonotonic behavior with pressure, by the synergistic influence of the intermolecular interaction and the distortion of the octahedral coordination environment. And the distortion of the octahedra under critical pressures may be the common behavior of 2D Hofmann-type ST compounds. Moreover, ΔT1/2 is increased compared with that before compression because of the partial irreversibility of structural distortion after decompression. At room temperature, both compounds exhibit completely reversible PIST. Because of the greater change in mechanical properties before and after ST, Isoq-Pt exhibits a more abrupt ST than Isoq-Pd. In addition, it is found that the hydrostatic properties of the pressure transfer medium (PTM) significantly affect the PIST due to their influence on spin-domain formation.

Assessing Lipid Nanoparticle Protein Corona Formation and Cytocompatibility

Lipid nanoparticles(LNPs) represent an emerging new modality for mRNA delivery. Following administration and interaction with blood constituents, LNPs form a corona complex consisting of proteins adsorbed on the surface altering their stability, biological identity, and fate. Cytocompatibility of the LNPs is an important factor when considering their safety efficacy in delivering the encapsulated drug dose, lipid choice and the specific target cells. The aim of this study was to investigate the changes in LNP physical parameters in physiologically-relevant media. Key attributes such as particle size, polydispersity index and zeta-potential were measured using Dynamic Light Scattering (DLS) and Nanoparticle Tracking Analysis (NTA). Cytocompatibility was assessed via CellTiter-Glo® assay. Following 24-hour incubation of LNPs with Bovine Serum Albumin (BSA), the LNP z-average increased from 92.4 (± 49.0) nm to 131.4 (± 64.9) nm indicating interaction between LNPs and BSA. A decrease in percentage cell viability was demonstrated with increased lipid concentration for MCF-7 and A549 cell lines. This work shows changes in LNP physicochemical properties in the presence of protein and biologically relevant conditions consistent with protein surface adsorption. The cytocompatibility of LNPs can be associated with the type of lipids used in the synthesis of LNPs.

Study on the dynamic changes of nutrient components and flavor compounds during the fermentation process of high-quality highland barley wine

The purpose of this study was to comprehensively understand the formation mechanism of nutrient components and flavor compounds during the fermentation process of high-quality highland barley wine (HHBW). The dynamic changes of physicochemical properties, non-volatile compounds and volatile flavor compounds in HHBW at different fermentation times were investigated. The results indicated that the nutrient components and physiologically active substances in HHBW, such as proteins, β-glucan, total phenols and total flavonoids were higher than those in commercial highland barley wine (HBW). In addition, the analysis results of HS-SPME-GC-MS revealed significant differences in flavor compounds at each fermentation stage, with alcohol being the main flavor compound. The contents of aldehydes and ketones decreased rapidly with the progress of fermentation. Lactic acid was the most important organic acid in HHBW. Correlation analysis revealed a negative association between citric acid and most alcohols and esters, while tartaric acid and succinic acid exhibited positive correlations with alcohols. Bitter amino acids, such as valine, isoleucine, leucine, arginine and lysine, were positively correlated with most of the ester flavor compounds. The study can provide a reference for a deep understanding of the mechanism of the formation of the characteristic flavor of HHBW.

Effects of ovotransferrin-chitosan composite coating agent on the storage quality of heavy metals-free preserved eggs

Heavy metals-free preserved eggs (HMFPEs) are prepared by adjusting the sodium hydroxide and temperature during the pickling process, without heavy metals such as copper and zinc compared with traditional methods in the pickling solution. Due to the absence of plugging effect by heavy metals, there is a sharp drop in quality during storage. In order to guarantee the quality of HMFPEs during storage, a unique blend of ovotransferrin-chitosan composite coating solution was evenly spread over the shells, and the changes of physicochemical, sensory, and microbial properties during different storage periods were studied. The results showed that after 182 days of storage at 25 °C, coating group with citric acid as crosslinker could effectively prevent moisture loss, lipid oxidation and microbial growth, and consequently maintain desirable color and flavor of HMFPEs.

Physicochemical and Microbiology Characteristics of Beverage Powder Based on Tempe Protein Concentrate at Various Storage Temperatures

A typical Indonesian food, tempe, is made by fermenting soybeans by the mold Rhizopus spp. Oneeffort to develop products and diversify food is to use tempe as the main ingredient in making tempe drink powder (TDP). Processing tempe into drink powder will increase tempe consumption and meet people’s protein needs. Over time, the quality of food products will decrease. Therefore, to ensure that the product remains fit for consumption, it is essential to know about changes in its physicochemical and microbiological properties. This research aimed to determine changes in physicochemical and microbiological properties of TDP products during storage at various temperatures. The physicochemical characteristics tested were proximate value, aw, pH, antioxidant activity, and whiteness. Microbiological characteristics included total mold and total plate count. The water content value increased at storage temperatures of 35 °C and 45 °C, but tended to decrease at 55 °C. During storage, the protein and fat content tended to be stable. Antioxidant activity increased at 25, 35, and 45 °C and decreased at 55 °C. Ash content, aw, pH, whiteness, and total plate decreased at each storage temperature.

Impact of Ecological Restoration on the Physicochemical Properties and Bacterial Communities in Alpine Mining Area Soils.

Ecological restoration has notably impacted microbe and soil characteristics in abandoned open pit mines, especially in alpine regions. Yet, the adaptive responses of microbial communities in the initial years of mine site restoration remain largely unexplored. This study endeavors to offer a thorough comprehension of soil properties and microbial dynamics during the initial phases of alpine mining land reclamation. It places emphasis on physicochemical properties and microbial community composition and evaluates the feasibility of phytoremediation, along with proposing subsequent measures. Our study employs spatial sequence instead of time-sequenceal sequence to investigate early-stage changes in soil microbes and physicochemical properties in alpine mining land reclamation. We used high-throughput sequencing for the 16S rRNA amplicon study. Over time, soil physicochemical properties improved noticeably. Soil pH shifted from neutral to alkaline (7.04-8.0), while soil electrical conductivity (EC) decreased to 77 μS·cm-1 in R_6a. Cation exchange capacity (CEC) initially decreased from R_2a (12.30-27.98 cmol·kg-1) and then increased. Soil organic matter increased from 17.7 to 43.2 g·kg-1 over time during mine reclamation and restoration. The dominant bacterial community consisted of Proteobacteria (33.94% to 52.09%), Acidobacteriota (4.94% to 15.88%), Bacteroidota (6.52% to 11.15%), Actinobacteriota (7.18% to 9.61%), and Firmicutes (4.52% to 16.80%) with varying relative abundances. Gene annotation of sequences from various reclamation years revealed general function prediction, translation, ribosome structure, cell wall/membrane/envelope biogenesis, nucleotide translocation, and metabolism, along with other related functions. Mine reclamation improved soil fertility and properties, with the R_6a treatment being the most effective. Starting in the 2nd year of reclamation, the effective phosphorus content and the dominance of microbial bacteria, notably the Bacillus content, decreased. Firmicute fertilization promoted phosphorus and bacterial growth. In conclusion, employing a blend of sequencing and experimental approaches, our study unveils early-stage enhancements in soil microbial and physicochemical properties during the reclamation of alpine mining areas. The results underscore the beneficial impacts of vegetation restoration on key properties, including soil fertility, pore structure, and bacterial community composition. Special attention is given to assessing the effectiveness of the R_6a treatment and identifying deficiencies in the R_2a treatment. It serves as a reference for addressing the challenges associated with soil fertility and microbial community structure restoration in high-altitude mining areas in Qinghai-Tibet. This holds great significance for soil and water conservation as well as vegetation restoration in alpine mining regions. Furthermore, it supports the sustainable restoration of local ecosystems.

Age-related changes on physicochemical properties of the artificial vitreous humor: A practical tool for enhancing ex vivo studies

The vitreous humor (VH) is a hydrophilic, jelly-like ocular fluid, which is located in the posterior chamber of the eye. The rheological, structural, and chemical properties of VH change significantly during aging, which further causes eye-associated diseases and could be a potential indicator for various diseases. In this study, artificial VH (A-VH) samples were created by taking into account different age groups to observe age-related changes in the physicochemical properties of these samples. This study aimed to measure the physicochemical properties of age-dependently prepared A-VH samples to determine the changes with aging in the physicochemical properties of A-VH samples.Phosphate-buffered saline (PBS)-based A-VH samples were prepared in three types representing adult, middle-aged, and elder individuals. Age-related changes in physicochemical properties (surface tension, osmolality, pH, relative viscosity, density, and refractive index) were analyzed by related equipment.The A-VH samples, prepared using PBS, showed strong similarity to authentic VH in terms of physicochemical properties. While the age-related changes studies have revealed some discrepancies between age-dependently prepared A-VH samples in terms of surface tension, osmolality, relative viscosity, and pH with high correlation coefficients (r2 > 0,94), density and refractive index values did not show any significant differences and correlation between types of A-VH representing 3 age groups.In conclusion, age-dependent A-VH samples were created successfully to use ex vivo method development studies, and the influence of aging on the physicochemical properties of VH was demonstrated as well.

Effects of progressive freeze concentration on craft beer: Volatile compounds, sensory profile, and physicochemical characteristics

Craft beers are becoming increasingly popular due to their developed and complex flavours, and there is a potential market for developing concentrated products; thus, freeze concentration can exploit this opportunity. In this work, the changes in physicochemical properties, volatile organic compounds, and sensory profiles of three craft beers (Witbier, Bitter, and Porter) after applying progressive stirred freeze concentration (PSFC) were evaluated, both on the concentrated liquid fraction and the ice fraction. After freeze concentration, increasing the concentration of all physicochemical characteristics in the three beers was possible. It was also possible to preserve the distribution of the volatile components in the liquid fractions and change it in the ice fractions. Significant differences were found in the sensory analysis of the concentrated liquid and the recovered ice fractions, and they were associated with the changes in the volatiles and the physicochemical properties. PSFC presents an opportunity to develop new beer products since both fractions show the potential to be commercialized.

General Equation to Estimate the Physicochemical Properties of Aliphatic Amines.

Changes in various physicochemical properties (P(n)) of aliphatic amines (including primary, secondary, and tertiary amines) can be roughly divided into nonlinear (P(n)) and linear (PLC(n)) changes. In our previous paper, nonlinear and linear change properties of noncyclic alkanes all were correlated with four parameters, n, SCNE, ΔAOEI, and ΔAIMPI, indicating number of carbon atoms, sum of carbon number effects, average odd-even index difference, and average inner molecular polarizability index difference, respectively. To date, there has been no general equation to express changes in the properties of substituted alkanes. This work, based on the molecular structure characteristics of aliphatic amine molecules, proposes a general equation to express nonlinear changes in their physicochemical properties, named as the "NPAA equation" (eq 12), ln(P(n)) = a + b(n) + c(SCNE) + d(ΔAOEI) + e(PEI) + f(APEI) + g(GN), and proposes a general equation to express linear changes in the physicochemical properties of them, named as the "LPAA equation" (eq 13), PLC(n) = a + b(n) + c(SCNE) + d(ΔAOEI) + e(PEI) + f(APEI) + g(GN). In NPAA and LPAA equations, a, b, c, d, e, f, and g are coefficients, and PEI, APEI, and GN represent the polarizability effect index, average polarizability effect index, and N atomic influence factor, respectively. The results show that nonlinear and linear change properties of aliphatic amines all can be correlated with six parameters, n, SCNE, ΔAOEI, PEI, APEI, and GN. NPAA and LPAA equations have the advantages of uniform expression, high estimation accuracy, and usage of fewer parameters. Further, by employing the above six parameters, a quantitative correlation equation can be established between any two properties of aliphatic amines. Using the obtained equations as model equations, the property data of aliphatic amines were predicted, involving 107 normal boiling points, 10 refractive indexes, 11 liquid densities, 54 critical temperatures, 54 critical pressures, 62 liquid thermal conductivities, 59 surface tensions, 56 heat capacities, 55 critical volumes, 54 gas enthalpies of formation, and 57 gas Gibbs energies of formation, a total of 579 values, which have not been experimentally determined yet. This work not only provides a simple and convenient method for estimating or predicting the properties of aliphatic amines but can also provide new perspectives for quantitative structure-property relationships of substituted alkanes.

Effects of rapeseed protein addition on soybean protein-based textured protein produced by low-moisture extrusion: Changes in physicochemical attributes, structural properties and barrel flow behaviors

This study investigated the potential of rapeseed protein as a novel alternative protein source in meat analogs produced by extrusion cooking technology. To study the substitutability of rapeseed protein to soybean protein, the addition ratios of rapeseed protein to soybean protein in the extrusion experiment were 0:50, 10:40, 20:30, 30:20, 40:10 and 50:0 (w/w), respectively. The results showed that adding 0–20% rapeseed protein not only decreased the specific mechanical energy and mass flow rate of the mixture during extrusion, but also enhanced the hardness and chewiness of the extrudates while reducing their elasticity and resilience. In addition, increasing the amount of rapeseed protein may lead to decreased expansion characteristics, internal pore structure, and water absorption rate of the extrudates, as well as a decrease in brightness and an increase in redness on the surface. Weibull model could well describe the rehydration behavior for dynamic fitting of the extrusion rehydration process. Moreover, with the increase of rapeseed protein substitution, the content of disulfide bonds, and the proportion of relatively ordered protein secondary structures with high stability increased, and the degree of protein denaturation decreased. Besides, the degree of starch gelatinization reduced and the thermal stability of extrudates improved. Interaction analysis indicated that disulfide bonds are the primary force maintaining protein-mediated interactions in the extrudates. The incorporation of rapeseed protein shortened the mean residence time of molten feedstock and shifted the flow state to plug flow. Overall, our investigation suggests that within low levels of addition (≤20%, w/w), rapeseed protein has the potential to partially substitute for the soybean protein-based textured proteins. High substitution levels or complete substitution are not feasible due to the relatively low expansion and rehydration rates.

Effect of Lactiplantibacillus plantarum fermentation on the physicochemical, antioxidant activity and immunomodulatory ability of polysaccharides from Lvjian okra

Okra polysaccharides exhibits a range of biological activities. To date, its processing using microbial fermentation has not been explored. This study investigated the fermentation of okra juice with various lactic acid bacteria, followed by the extraction and characterization of crude polysaccharides (termed OPS-F), in contrast to their non-fermented counterpart (OPS). Changes in physicochemical properties, antioxidant activity and immunomodulatory ability were noted. The results demonstrated that OPS-F had a 7.42–12.53 % increase in total polysaccharides content compared to OPS. However, high-performance size-exclusion chromatography indicated a reduction in the molecular weight of OPS-F (7.9–9.5 × 105 Da) relative to OPS (1.66 × 106 Da). Compared to OPS, OPS-F had reduced levels of mannose, glucose, glucuronic acid and arabinose, but increased rhamnose, galacturonic acid and galactose, exhibiting enhanced solubility and lower apparent viscosity. Fourier transform infrared spectroscopy and nuclear magnetic resonance analysis showed minimal changes in polysaccharide structure post-fermentation. Moreover, despite a decrease in antioxidant activity post-fermentation, OPS-F exhibited superior immunomodulatory potential. In conclusion, fermenting okra juice with lactic acid bacteria alters the physicochemical properties of crude polysaccharides and enhances their immunomodulatory activity, offering a promising approach for developing new functional food resources.

Changes in Physico-Chemical Properties of a Sandy Loam Soil Depending on the Particle Size of Hazelnut Shell-Derived Biochar

This study evaluated the effects of hazelnut shell-derived biochar particle sizes on the soil’s physical and chemical properties, and on various nutrient contents present in the sandy loamy soils. For this purpose, an incubation experiment in the plastic high tunnel has been performed under sixteen treatments (control-only soil), and at four incubation times (30, 60, 90, and 120 d), by using three different biochar sizes (≤ 1, 1 - 2, and 2 - 4 mm). The addition of 1 - 2 and 2 - 4 mm biochar during the incubation time decreased the bulk density in the soil by 26%. The particle size ≤ 1 mm on the other hand, increased the available water content, percentage of aeration porosity, and macropore, but decreased the micropore percentage in the soil. The soil’s pH has been the highest at 1 - 2 mm, 120 d sample, organic matter content at ≤ 1 mm, 120 d sample, and total nitrogen at ≤ 1 mm, 60 d sample. Regarding the available phosphorus and extractable potassium contents, the most effective particle size has been ≤ 1 mm and the incubation period has been 90 d for P and 60 d for K. The reduction in biochar particle size decreased the soil’s micro element content. The results showed that among all applications ≤ 1 mm biochar particle size was the most effective size on many physico-chemical properties of sandy loam soils. Also, a potential study related to the subject of this research focusing on the effects of different textures of particle sizes derived from hazelnut shell biochars.

High‐throughput experimental techniques for corrosion research: A review

AbstractHigh‐throughput experimental techniques can accelerate and economize corrosion evaluation, and thus, have great potential in the development of new materials for corrosion protection such as corrosion‐resistant metals, corrosion inhibitors, and anticorrosion coatings. This concise review highlights high‐throughput experimental techniques that have been recently applied for corrosion research, including (i) the high‐throughput preparation of metal samples in the form of thin films or bulk materials, (ii) high‐throughput experiments based on corrosive solutions with independent or gradient parameters, (iii) high‐throughput evaluation of changes in physicochemical properties, and (iv) high‐throughput corrosion evaluation by electrochemical methods. To advance automated and intelligent corrosion research, future directions for the development of the high‐throughput corrosion experimental and characterization techniques are also discussed.

Effect of the nature of the chelated metal on the photodynamic activity of metalloporphyrins

Coordination of metal ions by the tetrapyrrolic macrocyclic ring of porphyrin-based photosensitizers (PSs) affects their photophysical properties and consequently, their photodynamic activity. Diamagnetic metals increase the singlet oxygen quantum yield while paramagnetic metals have the opposite effect. Since singlet oxygen is considered the main cell-damaging species in photodynamic therapy (PDT), the nature of the chelated cation would directly affect PDT efficacy. This expectation, however, is not always supported by experimental results and numerous exceptions have been reported. Understanding the effect of the chelated metal is hindered because different chelators were used. The aim of this work was to investigate the effect of the nature of chelated cation on the photophysical and photodynamic properties of metalloporphyrins, using the same tetrapyrrole core as a chelator of Ag(II), Cu(II), Fe(III), In(III), Mn(III), or Zn(II). Results demonstrated that with the exception of Ag(II), all paramagnetic metalloporphyrins were inefficient as generators of singlet oxygen and did not act as PSs. In contrast, the coordination of diamagnetic ions produced highly efficient PSs. The unexpected photodynamic activity of the Ag(II)-containing porphyrin was attributed to reduction of the chelated Ag(II) to Ag(I) or to demetallation of the complex, caused by cellular reductants and/or by exposure to light. Our results indicate that in biological systems, where PSs localize to various organelles and are subjected to the action of enzymes, reactive metabolites, and reducing or oxidizing agents, their physicochemical and photosensitizing properties change. Consequently, the photophysical properties alone cannot predict the anticancer efficacy of a PS.

An insight into the quality formation of egg-white sufu based on the dynamic changes of protease activity, physicochemical properties and texture

Sufu is a delicious traditional Chinese food, mainly produced by fermentation using soybeans as raw material. Egg white is rich in protein and is theoretically an excellent material for sufu processing, however there are few reports on egg-white sufu (EWS) currently, and no such product is available on the market. In this paper, a novel sufu was processed with egg white as main material, and the formation mechanism of its unique quality was explored by monitoring the dynamic changes in the pre-fermentation and post-fermentation stages. The dynamic change curve of protease activity showed an “S” shape, with a peak of 32.33 U/mL on the 4th day of pre-fermentation stage. After a 4-day pre-fermentation and 90-day post-fermentation, most of the proteins in the EWS had been hydrolyzed, and the sufu was moderately soft and delicate in texture, with a hardness of 950.3 g and a total free amino acid content of 19.863 mg/g. SEM and SDS-PAGE detections suggested that the proteins in EWS had been extensively degraded, which led to the formation of its unique texture and flavor. The EWS was slightly better than soybean sufu in terms of texture, fragrance and mouthfeel, with flavor compounds mainly composed of aldehydes and alcohols, resulting in a slightly higher total sensory evaluation score.

The effects of physical treatment on physicochemical and biological properties of water and aqueous solutions

Objectives. Changes to the properties of water caused by factors such as pressure or temperature, can only be explained by its structural changes. Scientists study changes to the properties of water due to various physical stimuli only without the addition of any substances. Examples of stimuli are acoustic exposure, thermal exposure, pressure variation, shaking, intensive vibration treatment followed by dilutions, vortexing, bubble generation, inter alia.The aim of the present review article is to summarize the available data on how the above processes affect the physicochemical and biological properties of water and aqueous solutions.Results. It has been shown that heating makes water less compressible and decreases air solubility in water, while cooling enhances its viscosity. Acoustic exposure makes the structure of water become coarse-grained, followed by an increase the number of large clusters, pH and temperature inside a cavitation bubble. High pressure enhances the viscosity, self-diffusion, and compressibility of water. For bubble processed water, there are changes in the spin-spin and spin-lattice relaxation times. Reactive oxygen species are formed, as well as increased solubility of gases in liquids and reduced friction. Vortex process technology causes an increase of electrical conductivity of water and reduced viscosity. Intensive vibration treatment and dilution processes result in changes in electrical conductivity of water, dissolved gas concentration, ultrasonic wave velocity, рН, surface tension, dielectric constant, and spectral response. There is also data to support the biological effects of different types of physical treatment of solutions.Conclusions. This review shows that physical treatment of water can induce changes both in physicochemical and biological properties of water and aqueous solutions.

An integrated approach to testing and assessment (IATA) to support grouping and read-across of nanomaterials in aquatic systems

Even small changes in physicochemical properties of nanoforms (NFs), can drive differences in their environmental fate and hazard. The large number of new materials being developed means it will not be feasible to test and characterise the fate, behaviour and (eco)toxicity of each individual NF. This is further amplified by transformations of NFs over their lifecycle, changing the processes governing their risk. A common complexity arises from dissolution, where the combined toxicity of the exposure arises from both the solutes and any remaining particles contribution to the overall toxicity of the exposure. For efficient and effective risk assessment, it is the most relevant form of the NF for a given exposure that should be targeted for testing and assessment. In aquatic systems, functional fate processes (including dissolution, dispersion stability and chemical and biological transformations) determine the NF’s exposure relevant form. Whilst transformations in the environment alter the initial properties of an NF, different NFs may follow a shared functional fate pathway and ultimately present a similar fate and hazard profile in the environment. Therefore, these processes may be used to scientifically justify grouping NFs and read-across for specific endpoints from data rich NF(s) to verified members of the group that have not been tested yet. Integrated Approaches to Testing and Assessment (IATA) have been used in other regulatory contexts to support the collection and integration of relevant existing information as well as the targeted generation of new data to support grouping and read-across. Here, a new IATA is presented consisting of decision nodes focused on dissolution, dispersion stability, chemical transformations and the relative contribution to toxicity of the particle and dissolved component of the overall exposure. The IATA focuses on the fate of NFs in aquatic systems outside of the body, but it can be considered a template for future assessment of in vivo kinetics, which will require further development. Guidance on tiered testing approaches and thresholds for grouping within each decision node are critically discussed. Worked examples for ecotoxicity of metal oxide NFs in aqueous systems (in microbial communities isolated from soils and for lettuce plants in hydroponic systems) demonstrate successful identification of the exposure relevant form of the NF in these case studies and allows for different grouping of NFs through application of the IATA.

Dynamic Changes in Microbial Communities, Physicochemical Properties, and Flavor of Kombucha Made from Fu-Brick Tea.

In this study, Fu-brick tea (FBT) was used for kombucha preparation. The succession of microbial community structures, changes in physicochemical properties, and the volatiles were investigated during the kombucha fermentation. The sequencing analysis showed that Komagataeibacter was the most predominant bacterium. Aspergillus and Zygosaccharomyces were the dominant fungi before fermentation whereas Zygosaccharomyces and Derkella were the dominant fungi after 3 days of fermentation. The physicochemical analysis revealed that acetic acid, glucuronic acid, and polyphenols increased by 10.22 g/L, 0.08 g/L, and 177.40 mg/L, respectively, by the end of fermentation. The GC-MS analysis showed that a total of 49 volatile compounds were detected during the fermentation. Moreover, there were great differences in volatile components among the kombucha samples with different fermentation times. Furthermore, the relevance among microbial community and volatile compounds was evaluated through correlation network analysis. The results suggested that Komagataeibacter, Aspergillus, Zygosaccharomyces, and Dekkera were closely related to the main volatile compounds of FBT kombucha. The results in this study may provide deep understanding for constructing the microbiota and improving the quality of FBT kombucha.