Agitation Conditions Research Articles

Reactive Crystallization Kinetics Study of Boehmite in Ammonia Solution by Adding Ammonium Aluminum Sulfate

As an important intermediate product in new techniques for extracting alumina from coal fly ash, boehmite is obtained by the reaction between ammonium aluminum sulfate and ammonia. The reactive crystallization kinetics of boehmite is investigated using a continuous steady-state method. The Mydlarz and Jones (MJ3) models are in considerable agreement with the experimental results by a non-linear regression method; furthermore, crystal nucleation and growth rate equations are proposed. The results revealed that the suspension density and agitation rates present considerable influence on nucleation. Additionally, high levels of supersaturation are not conducive for crystal growth, and the supersaturation index for crystal growth was small due to its poor water solubility. Moreover, the maximum d0.5 (average particle size) was 27.968 μm under the agitation condition and the feed rates of 250 r/s and 0.5 g/10 min. Fast crystal growth speed is associated with the crystal structure’s high AlO6-unit and bulk-oxygen content. Our study on crystal nucleation and growth kinetics will be beneficial to the industrial production of boehmite.

Screening and Characterization of Polycyclic Aromatic Hydrocarbons Tolerant Fungi from Petrochemical Refinery Effluent

Fungi were isolated from effluent released by petrochemical refinery and screened for their tolerance to 50 mg/L concentration of naphthalene, phenanthrene and pyrene under agitation condition of 150 rpm and ambient temperature over a period of 21 days. Samples were analysed for residual PAH concentrations using HPLC and tolerance ability were calculated in percentages. Fungal growth in mineral salt medium supplemented with PAH was measured in dry weight of mycelial biomass was used as index for assessing their tolerance ability. Out of the 22 fungi isolated, only four were identified as Aspergillus, Talaromyces, Fusarium and Trichoderma species to exhibit tolerance to naphthalene (94.6, 96.9, 99.7 and 99.8%), phenanthrene (91.1, 92.2, 99.5 and 99.8%) and pyrene (89.4, 90.5, 92,6 and 94.2%) respectively. Low molecular weight PAHs (naphthalene and phenanthrene) were better tolerated compared to high molecular weight pyrene. Based on findings made in this study, the four isolates with higher tolerance to PAHs could be recommended for bioremediation of PAH contaminated environments.

Green Synthesis of Silver Nanoparticles Using the Cell-Free Supernatant of Haematococcus pluvialis Culture.

The green synthesis of silver nanoparticles (AgNPs) using the cell-free supernatant of a Haematococcus pluvialis culture (CFS) was implemented in the current study, under illumination conditions. The reduction of Ag+ to AgNPs by the CFS could be described by a pseudo-first-order kinetic equation at the temperature range tested. A high reaction rate during synthesis and stable AgNPs were obtained at 45 °C, while an alkaline pH (pH = 11.0) and a AgNO3 aqueous solution to CFS ratio of 90:10 (v/v) proved to be the most effective conditions in AgNPs synthesis. A metal precursor (AgNO3) at the concentration range tested (1-5 mM) was the limited reactant in the synthesis process. The synthesis of AgNPs was accomplished under static and agitated conditions. Continuous stirring enhanced the rate of reaction but induced aggregation at prolonged incubation times. Zeta potential and polydispersity index measurements indicated stable AgNPs and the majority of AgNPs formation occurred in the monodisperse phase. The X-ray diffraction (XRD) pattern revealed the face-centered cubic structure of the formed AgNPs, while TEM analysis revealed that the AgNPs were of a quasi-spherical shape with a size from 30 to 50 nm. The long-term stability of the AgNPs could be achieved in darkness and at 4 °C. In addition, the synthesized nanoparticles showed antibacterial activity against Escherichia coli.

Experimental Peloid Formulation Using a Portuguese Bentonite and Different Mineral-Medicinal Waters Suitable for Therapeutic and Well-being Purposes

The identification of raw materials and an effective maturation process for the development of peloids is essential to ensure consistent comparisons between commonly used peloids in ‘thermal centers’ (places that offer a variety of health and wellness treatments, also known as spas) and their therapeutic and well-being effects. The present study supports the need for scientific research which examines the variations in physicochemical, technological, and biological properties of peloids resulting from varying maturation conditions. These studies are necessary for establishing quality and safety standards and expanding our understanding of the therapeutic significance of peloids. The objective of the present study was to characterize an experimental maturation procedure using a specific Portuguese clay (bentonite) sourced from Benavila—Avis, which has particular physico-chemical characteristics, in conjunction with two distinct Portuguese mineral-medicinal waters (Hotel Cró and Thermal Spa, and Caldas da Rainha Thermal Hospital) as raw materials. The main aim of the study was to assess and characterize the resulting peloids by evaluating their physicochemical, technological, and biological properties. The experiment was conducted over a period of 90 days under carefully controlled lighting and agitation conditions. The rheological, mineralogical, and chemical properties relevant to a peloid intended for topical application and its potential transdermal delivery of elements were characterized. Additionally, the study investigated the biological activity within the maturation habitat, including chlorophyll, microalgae, and microorganisms. Eight samples, representing the four maturation conditions (stirring with light; stirring without light; no stirring with light, and no stirring and no light), were examined for 30, 60, and 90 days. The study showcased the influence of different mineral-medicinal waters on maturation conditions and on the final bentonite characteristics. Furthermore, it reinforced the importance of establishing quality-control procedures throughout the maturation cycle for bentonitic peloids, as well as the importance of monitoring their usage, reutilization, and disposal.

Effects often overlooked in lipid oxidation in oil‐in‐water emulsions: Agitation conditions and headspace‐to‐emulsion ratio

AbstractThe effects of the agitation conditions and headspace‐to‐emulsion volume ratio on lipid oxidation in emulsions can be considerable, but have not been systematically investigated yet. In the current paper, lipid oxidation was monitored in model oil‐in‐water (O/W) emulsions at pH 4.0 and 25°C in the presence of 200 μM iron sulfate. The formation of primary (conjugated dienes and hydroperoxides) and secondary (p‐anisidine value and TBARS) oxidation products confirmed that using rotating or shaking devices doubled the rate of oxidation product formation compared to a non‐agitated system, as a result of enhanced oxygen transfer. Furthermore, we found that a higher headspace‐to‐emulsion volume ratio at least doubled the rate of lipid oxidation due to a higher amount of oxygen available per mass of oil, which is in agreement with the kinetics of the reaction. This indicates that the variation in literature data on lipid oxidation in emulsions can be attributed to differences in mixing conditions and volume ratios. These factors are crucial and should be reported systematically along with the agitation conditions, and sampling method. This will enable a better comparison of literature information.

Effects of disturbance modes and carbon sources on the physiological traits and nutrient removal performance of microalgae (S. obliquus) for treating low C/N ratio wastewater

Wastewater treatment with microalgae is an ecologically sustainable process. In this study, the growth characteristics, nutrient removal, and spectral changes of dissolved organic matter (DOM) in microalgae bioreactors were investigated for treating low C/N ratio wastewater under different disturbance modes (agitation and aeration) and carbon sources (sucrose and humic acid). The results showed that the biomass and chlorophyll-a contents of Scenedesmus obliquus in the aeration condition (725.32–811.16 × 104 cells mL−1, 1.58–1.69 mg L−1) were higher than those in the agitation condition (426.06–465.14 × 104 cells mL−1, 1.48–1.61 mg L−1). The better removal of nutrients (TN, 29.62–36.39 mg L−1, TP, 1.84–2.30 mg L−1) by microalgae in sucrose-containing wastewater under agitation conditions occurred on the second day, with removal efficiencies of 21.33–30.67% and 44.84–58.51%, respectively; while it was on the fifth day both in sucrose and humic acid-containing wastewater under aeration conditions (TN, 19.56–31.20 mg L−1, TP, 0.26–0.30 mg L−1), with removal efficiencies of 13.92–46.75% and 88.36–90.50%, respectively. The wastewater DOM primarily consisted of humic-like substances under agitation and aeration conditions characterized by high levels of aromaticity, molecular weight and humification. Furthermore, the aromatization and humification properties of DOM in humic acid wastewater were higher than those in sucrose wastewater, which was corresponding with the lower removal and availability of pollutants by algae. Microalgae showed good biomass accumulation and nutrients removal at incubation time of 2 days (agitation condition) and 5 days (aeration condition), respectively. Consequently, a technical reference is provided for the microalgae coupled with other treatment processes.

Kemampuan Dekolorisasi Zat Pewarna Sintetis Menggunakan Jamur Aspergillus niger : Review

Waste from the textile industry is dominated by synthetic dyes. Synthetic dyes are complex organic components that are quite resistant to environmental conditions so they are very damaging to ecological systems. The decolorization process can be carried out with the help of biological agents. One biological agent that also has potential for the decolorization process of synthetic dyes is the brown rot fungus, Aspergillus niger. The information and literature review explained in this article refers to the latest research regarding the potential decolorization of synthetic dyes by the fungus Aspergillus niger. The literature review was carried out by analyzing qualitative data, making observations, and drawing conclusions from research journals. The results of the study show that the Aspergillus niger fungus has quite good potential, even the percent removal of synthetic dyes can reach ± ​​90% through biodegradation and biosorption processes that work simultaneously. There are several factors that influence the removal mechanism, such as: pH, agitation conditions, temperature, initial dye concentration, and nutrient composition.

Solid state culture conditions for improved conidial production of the mycoparasitic fungus Escovopsis weberi

ABSTRACT We evaluated culture conditions (temperature, substrate moisture content, agitation and light conditions) for optimising conidia production of Escovopsis weberi Ew1 using solid state culture. In addition, several substrates such as agricultural waste and food industry by-products were evaluated with the aim of reducing spore production costs in a strategic way towards circular bioeconomy. Finally, we selected substrate combinations in order to achieve a suitable system for the production of conidia.

Experimental and Modelling Study of Pt, Pd, and 2E+Au Flotation Kinetics for Platreef Ore by Exploring the Influence of Reagent Dosage Variations

This study investigates the flotation kinetics of individual platinum-group elements (PGEs) and gold, namely Pt, Pd, and 2E+Au (i.e., Pt+Pd+Au), in the context of Platreef ore flotation. Experimental tests were conducted on a Platreef ore feed using various dosages of depressants, frothers, and collectors under controlled agitation and pH conditions. The recoveries of the individual PGEs were analysed using six kinetic models, with the modified Kelsall model identified as the most suitable for accurately describing the flotation kinetics and predicting elemental recovery. Notably, the model incorporates two rate constants (kfast and kslow) to account for the distinct flotation behaviours of the PGEs. The results indicate that Pt has the fastest floatability, followed by Pd and 2E+Au. The modified Kelsall model demonstrates high effectiveness in predicting the recovery of these PGEs. Three empirical correlations for Pt, Pd, and 2E+Au recoveries based on the modified Kelsall model are proposed, enhancing the understanding and optimisation of PGE recovery in Platreef ore flotation.

Agitation role (Dissolved Oxygen) in production of laccase from newly identified Ganoderma multistipitatum sp. nov. and its effect on mycelium morphology

BackgroundAgitation speed influenced the production rate of laccase. Orbital speed not only influenced the enzyme production, but was also effective to dissolve the oxygen during growth of mycelium, spores, and chlamydospores. Shear effects of speed greatly influenced the morphology of mycelium.MethodsGanoderma multistipitatum was identified by ITS marker. Phylogenetic tree was constructed for species identification. Qualitatively by plate method contained guaiacol indicator, while quantitatively by submerged fermentation and Central Composite Design applied on agitation parameter for maximum laccase potential of this species. The effects of agitation speed on mycelium morphology were observed under compound and scanning electron microscope.ResultsStatistical optimization of agitation conditions were performed by using response surface methodology to enhance the production of laccase from Ganoderma multistipitatum sp. nov. Maximum laccase yield (19.44 × 105 ± 0.28 U/L) was obtained at 150 rpm grown culture, which was higher than predicted value of laccase production (19.18 × 105 U/L) under aerobic conditions (150 rpm). The 150 rpm provided the continuous flush of oxygen. The DO (dissolved oxygen) was maximum (65%) for “27 h” incubation at 150 rpm during laccase synthesis. The statistical value of laccase production was minimum under anaerobic or nearly static condition of 50 rpm. The predicted (12.78 × 105 U/L) and obtained (12.82 × 105 U/L) yield was low at 50 rpm. Optimization of orbital shaking for aeration conditions were performed by the use of “Response Surface Methodology”. The submerged shaking flasks were utilized as a nutrients growth medium to maximize the production of laccase from G. multistipitatum. The minimum incubation time highly influenced the laccase yield from 7 to 15 days via utilization of less cost-effective medium under a promising and eco-friendly method. The morphological effects of rpm on mycelium were examined under compound and scanning electron microscopy. Higher rpm (200, 230) shear the mycelium, while 150 to 200 rpm exhibited smoother and highly dense branches of mycelia.ConclusionThe shear forces of 200 rpm caused the damages of mycelium and cells autolysis with less laccase production. This study concluded that 150 rpm saved the life of mycelium and enhanced the production rate of enzymes.

L-Asparaginase from an acrylamide degrader, Cupriavidus oxalaticus ICTDB921: Production, kinetic modelling, purification and characterization

In the present study, a novel soil isolate and previously reported acrylamide degrader, Cupriavidus oxalaticus ICTDB921, was found to have better and significantly higher l-asparaginase (LAase) activity than other bacterial strains that were screened for the same. The medium and fermentation conditions were optimized for maximizing LAase production followed by its purification and biochemical characterization. The optimum conditions of pH (7), temperature (30 °C) and agitation (180 rpm), showed the highest biomass accumulation (DCW 3.15 g/L) and LAase activity (22.94 IU/mL) after 12 h at 160 mM l-asparagine. Kinetic modelling of optimized batch data showed the biomass accumulation, LAase formation and l-asparagine utilization to best fit with the logistic model, Leudeking-Piret model and exponential decay model, respectively. The crude LAase from this isolate showed high potency at pH 7 to 9, and temperatures from 30 to 40 °C with reasonable pH (6–9) and thermal (up to 50 °C) stability. The LAase was stable against most amino acids and metal ions, and it could degrade aliphatic amides like urea and formamide. A sequential purification by ammonium sulphate precipitation, thermal treatment and chromatographic separation achieved approximately 8-fold purity. The purified subunit showed a molecular weight of 78 kDa, and km and Vmax of 24.1 mM and 40 μmol/min, respectively. The study demonstrates the potential of LAase from Cupriavidus oxalaticus in the mitigation of asparagine in food as well as for therapeutic applications.

Submerged cultivation of selected macro-fungi to produce mycelia rich in β-glucans and other bioactive compounds, valorizing side streams of the food industry

This study reports the valorization of four side-streams derived from the food industry as fermentation media to cultivate edible and medicinal macrofungi of the genera Cyclocybe sp., Ganoderma sp., Grifola sp., Hericium sp., Morchella sp., Pleurotus sp., Schizophyllum sp. and Trametes sp.. Initial screening experiments revealed the suitability of brewer’s spent grain extract (BSGE) and diluted wine distillery effluent (WDE) as the sole carbon sources for significant mycelial mass production. Subsequent fermentations investigated the effect of static and agitated conditions on biomass production, protein content and glucan content of fungal biomass. Considerably higher biomass and concentrations of total glucans, α-glucans and β-glucans were determined in macrofungi cultivated in BSGE compared to WDE. Agitated BSGE-based cultures of Schizophyllum commune resulted in the maximum biomass synthesis (27.6 g/L), while the highest total glucans of 70.8 % w/w with a β-glucan content of 57.2 % w/w were determined for G. lingzhi, when the culture was also agitated. The protein content of mycelia ranged from 12.3 up to 26.5 % w/w in the strains that were examined. ATR-FTIR spectra of the mycelia demonstrated the characteristic bands associated with fungal polysaccharides.

Mutagenesis enhances gellan gum production by a novel Sphingomonas spp.: upstream optimization, kinetic modeling, and structural and physico-functional evaluation.

Gellan gum (GG) has gained tremendous attention owing to its diversified applications. However, its high production and hence market cost are still a bottleneck in its widespread utilization. In the present study, high GG producing mutant of Sphingomonas spp. was developed by random mutagenesis using ethyl methylsulphonate (EMS) for industrial fermentation and identified as Sphingomonas trueperi after 16S rRNA and matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF-MS) analysis. The fermentation conditions such as pH, temperature, and inoculum ratio were optimized by one factor at a time (OFAT) followed by screening of medium components by the Plackett-Burman statistical design. The most critical nutrients were further optimized by response surface methodology for maximizing GG production. The effect of dissolved oxygen tension in bioreactor on cell growth, substrate consumption, GG production, and batch productivity was elucidated. The highest GG titer (23 ± 2.4g/L) was attained in optimized medium at 10% inoculum (6.45 ± 0.5 log cfu/mL) under controlled fermentation conditions of pH (7), temperature (30°C), agitation (300-600rpm), and aeration (0.5-2.0 SLPM) at 22 ± 2% dissolved oxygen tension in a 10-L bioreactor. Kinetic modeling of optimized batch process revealed that logistic growth model could best explain biomass accumulation, while GG formation and substrate consumption were best explained by Luedeking-Piret and exponential decay model, respectively. Structural and physico-functional features of GG produced by mutant Sphingomonas spp. were characterized by HPLC, FTIR, NMR, DSC, TGA, GPC, SEM, and rheological analysis. The higher productivity (0.51g/L/h) under optimized fermentation conditions suggests potential consideration of mutant and process for commercial utilization.

Enhanced injectability of aqueous β-tricalcium phosphate suspensions through PAA incorporation, gelling and preshearing

The major shortcoming of aqueous calcium phosphate suspensions used in biomedical applications is their unstable flow during delivery by mechanical means. In this study, microstructural changes and the resulting flow instabilities of aqueous β-TCP suspensions are demonstrated under both pressure-induced and drag-induced flow regimes and then remedied with the incorporation and subsequent gelling and preshearing of Carbopol 940, a biocompatible hydrogel. Mixing and dispersion of calcium phosphate particles into the hydrogel matrix was not efficient under simple agitation conditions. Swelling of the polymer chains was induced at approximately pH = 9.0 by water and particle intrusion within the opened-up coil structure due to deprotonation of the carboxylic acid groups by NaOH. As a result the composite material underwent a rapid viscoplastic transition into a doughy state which was not amenable to further processing without preshearing. Manual kneading converted the material into viscous state and enhanced the flow behavior significantly. Preshearing and probing the microstructure by mechanical spectrometer revealed multiple microstructural mechanisms responsible for the observed stable flow behavior, including improved dispersion of the particles, attrition of the polymeric network into microgel domains, enhanced adhesion and lubrication between the solid and liquid phase, crosslinking of the polymeric network. The net effect of these probable mechanisms was stiffening of the composite matrix, mobilization of solid particles and a marked enhancement in the stability of pressure-induced flow. The resistance of the material to liquid phase migration and its ability to undergo wall-slip and relax under stress were confirmed by simultaneous capillary rheometry and thermogravimetric analyses. The processing method enables improvements in the delivery of this composite material for injection and direct ink writing of scaffolds.

Polydopamine particle in-situ assisted carbon fiber/CNTs brush with dynamic imine bonds for enhancing the interface properties of its polyamide 6 composites

Fabricating carbon fiber/carbon nanotubes (CF/CNTs) brush is regarded as an effective way to improve its composite interfacial and mechanical properties. Different from other reports, a novel fabrication method was developed in this work. Based on Schiff base reaction, polydopamine (PDA) particle with moderate size could in-situ assist CNTs hairs to be grafted onto carbon fibers surface under agitation condition. This method can guarantee thermal stability of modified layers and facilitate the interfacial compatibility of CF/PA6 due to dynamic imine bond exchanges under high temperature (240 °C) during the injection molding. The contact angle of modified CF with PA6 decreased to 34.2° from 53.6° of the untreated-CF. The results also showed both the interfacial and mechanical properties of the composites were improved. Compared with that of the untreated-CF/PA6 composites, the interfacial shear strength, tensile strength and tensile modulus of modified-CF/PA6 were increased by nearly 64.39%, 22.14% and 21.67%, respectively. This simple modification method would provide the premise to expand it to scale-up industry production of CF reinforced thermoplastic composites.

Complementary conjugated piezo-phototronic polarized blue TiO2 - KNN for piezophotocatalytic degradation of tetracycline enhanced under gentle oscillatory hydrodynamic disturbances

Recently, tetracycline (TC) is classified as an emerging contaminant due to its rapid discharge into the environment from anthropogenic sources. Piezophotocatalysis offers a unique solution to degrade TCs by collaboratively harnessing both solar and hydro energy. However, practical applications have been hampered by the necessitation of high energy requirement ultrasonic baths. In this work, BT-KNN conjugates were investigated for piezophotocatalytic TC degradation. Under agitation conditions, characterization studies demonstrated an amplified photocurrent, diminished charge transfer resistance and reduced radiative recombination. Concomitantly, BT-KNN composites exhibit enhanced TC degradation and apparent rate constant with increased fluid disturbance frequencies, illustrating 91.3% degradation in 3 h under gentle 4 Hz oscillations. These hydrodynamic disturbances engender a propitious piezopolarization which modulated the junction band bending and ameliorated the interfacial charge transfer, intensifying its performance. Optimization studies further illustrates the tradeoff dynamics between high photoactivity of BT and high piezo-enhancement of KNN.

Influence of carbon sources on the physicochemical properties and yield of bacterial cellulose production

Bacterial cellulose (BC) is a biopolymer of great interest for application in various industrial and medical areas, due to its peculiar characteristics of biocompatibility, tensile strength, high water retention capacity and crystallinity. CB can be produced using culture media with different nutrient sources, under static or agitated cultivation conditions. The objectives of this work were to produce CB membranes, using the bacterial strain Komagateibacter hansenii ATCC 23769, in static cultivation, using media containing different sources of carbon (glucose, fructose, glycerol and ethanol) and nitrogen (yeast extract and peptone), aiming to study the influence on the physicochemical properties of the BC produced and its possible biomedical application. The obtained BC were comparatively evaluated for dry mass yield, swelling capacity, and characterized by Field emission gun-scanning electron microscopy (FEG-SEM), and Fourier transform spectroscopy (FTIR). Membranes with significant swelling capacity were obtained, demonstrating that the composition of the culture medium influences the physicochemical properties of BC. The results of this work also demonstrate that the BC has great possibilities in several areas, including biomedical applications.

Particle-tracking-based strategy for the optimization of agitation conditions in a suspension culture of human induced pluripotent stem cells in a shaking vessel

Suspension cultures are widely used for cell expansion in regenerative medicine and production. Shaking culture is one of the useful suspension culture methods that ensures gentle agitation. There are other shaking methods, including orbital shaking, reciprocating, and rocking; however, optimizing the shaking conditions for each method to meet cell culture requirements is time-consuming. In this study, we used a particle-tracking-based strategy for optimizing the agitation conditions. When the average accelerations of aggregates were calculated, high acceleration occurred periodically, and acceleration of the aggregates in orbital shaking was stable. Furthermore, the number of dead cells correlated with the average time of acceleration. We observed that cell growth was ideally maintained by factors such as optimal acceleration, aggregate formation, and cell death. These results indicate that the image-based analyses of aggregates help optimize the agitation conditions for the shaking suspension culture of induced pluripotent stem cells (iPSCs).

PRODUCTION OF BACTERIAL NANOCELLULOSE IN ALTERNATIVE CULTURE MEDIA UNDER STATIC AND DYNAMIC CONDITIONS

Bacterial nanocellulose (BNC) was produced in three different culture media: the standard HS medium, and the alternative much less costly analytical glycerol/corn steep liquor (AG-CSL) and glycerol remaining from biodiesel production/corn steep liquor (BG-CSL) media. Both static and agitated conditions were assessed, and the effect of the culture medium, agitation speed and cultivation time used was evaluated on BNC production and selected products characteristics (morphology, specific surface area and crystallinity). Results showed that the cheaper alternative culture media assayed led to increased production of BNC, and that agitation speed modulation allowed producing either BNC pellicles or BNC pellets with varying size, shape, crystallinity and cellulose nanofibers packing.

Optimized Conditions for the Long-Term Maintenance of Precision-Cut Murine Myocardium in Biomimetic Tissue Culture

Organotypic heart slices from mice might provide a promising in vitro model for cardiac research because of the vast availability of genetically modified specimens, combined with the unrestricted feasibility of experimental interventions. However, murine heart slices undergo rapid degeneration in culture. Therefore, we developed optimal conditions to preserve their structure and function in culture. Mouse ventricular heart samples were transversely cut into 300 µm thick slices. Slices were then cultured under various conditions of diastolic preload, systolic compliance and medium agitation. Continuous stimulation was performed either by optical stimulation or by electrical field stimulation. Contractility was continuously measured, and cellular survival, structure and gene expression were analyzed. Significant improvements in viability and function were achieved by elastic fixation with the appropriate diastolic preload and the rapid shaking of a ß-mercaptoethanol-supplemented medium. At 1 Hz pacing, mouse heart slices maintained stable contractility for up to 48 h under optogenetic pacing and for one week under electrical pacing. In cultured slices, the native myofibril structure was well preserved, and the mRNAs of myosin light chain, titin and connexin 43 were constantly expressed. Conclusions: Adult murine heart slices can be preserved for one week and provide a new opportunity to study cardiac functions.