Subsequent Immersion Research Articles

Surface Modification of Anodized Titanium Surfaces with Chitosan/ε-Polylysine Coating, Aiming for an Improved Bioactivity, Biocompatibility, and Anti-Bacterial Properties for Orthopedic Applications

The increasidng demand for implants due to the aging populations highlights the necessity for applying highly functional coatings on the surface of implants. This study investigates the implications of applying a chitosan/polylysine composite coating on anodized titanium surfaces, aiming for improved biocompatibility, bioactivity, and anti-bacterial properties. Titanium substrates were anodized at 40 volts for a duration of two hours, followed by dip coating with the chitosan/polylysine composite. Fourier-transform infrared (FTIR) analysis was employed to characterize the polymer structure, while field emission scanning electron microscopy (FESEM) and energy-dispersive X-ray spectroscopy (EDS) techniques were utilized to evaluate nanotube morphology and the coating structure. Results showed that samples containing 1.5% polylysine exhibited noticeable anti-bacterial properties and cell viability above fifty percent. Subsequent immersion in simulated body fluid (SBF) for a duration of two weeks revealed the formation of apatite crystals on the coated samples, indicating that the samples are bioactive. Furthermore, polylysine contributed to enhanced resistance against degradation in phosphate-buffered saline (PBS) solution. Overall, the chitosan/polylysine composite coating exhibited promising mechanical and biomedical characteristics, suggesting its potential for applications in orthopedic implants.

Effects of silver diammine fluoride with/without potassium iodide on enamel and dentin carious lesions in primary teeth.

To assess the effects of SDF and SDF+KI treatment on enamel and dentin carious lesions in primary teeth using x-ray Microtomography (XMT) and back scattered scanning electron microscopy (BSE-SEM). Artificial enamel caries of 3 caries free primary teeth were created by immersion of the samples in 50 ml demineralization solution for 72 h. Three other teeth with natural dentin caries were selected. Both groups were divided into 3 subgroups: EC-Enamel Control; ES-Enamel with SDF application; ESK-Enamel with SDF followed by KI application; DC-Dentin Control; DS-Dentin with SDF application; DSK-Dentin with SDF followed by KI application. Each tooth was imaged using XMT at 3 time points: (1) Pretreatment; (2) after immersion in remineralization solution for 120 h, with or without SDF or SDF+KI; (3) after subsequent immersion in demineralization solution for 72 h. The change of radiopacities of the lesions in these time points were assessed from the XMT images. After the XMT scans, all teeth were investigated microscopically using BSE-SEM. In EC, no change in linear attenuation coefficient (LAC) was observed after remineralization, but LAC reduction was observed after subsequent demineralization. For ES, thin layer of high LAC material was deposited on the enamel surface after remineralization, and further reduction of LAC was observed after demineralization. In ESK, the surface layer was lost after SDF+KI, and small reduction of LAC was observed after demineralization. In DC, no LAC change was observed after remineralization, but reduction of LAC was detected after demineralization. In DS, high LAC material was formed on the carious dentin surface and randomly inside the lesion. No further LAC change was found after demineralization. In DSK, thick layer of high LAC material was deposited on the carious surface and inside the dentinal tubules. No further LAC reduction was found after subsequent demineralization. SDF and SDF+KI did not protect artificial enamel under acid attack even though Ag products were deposited in the porous enamel. However, SDF and SDF+KI shows protective properties against acid challenges and Ag products are deposited in carious dentin lesion without tubular structure randomly; and within dentinal tubules when these structures are retained.

Effect of thiol adsorption on the electrical resistance of copper ultrathin films

The impact of thiol adsorption on thin copper films, covered with a copper oxide layer, was investigated using electrical resistance measurements at various stages: during film growth, aging, exposure to air, and immersion in thiol solutions. Thin copper films (20 nm) were thermally evaporated, with variations in substrate temperature (RT, 330 and 390 K). Films deposited at 330 K exhibited the smallest percolation thickness and aging rates due to their compact morphology, showcasing lower surface roughness and correlation length. Exposure to air led to the formation of a Cu2O layer on the film surface. Subsequent immersion in a dodecanethiol solution in ethanol resulted in a resistance increase, ranging from 0.1 % to 0.4 %. This change was dependent on the substrate temperature, with the largest difference observed at 330 K. This observation suggests that samples grown at this temperature exhibited the highest electron-surface scattering. Moreover, by depositing a chromium surfactant layer, the impact of this scattering mechanism was amplified, leading to a resistance increase of up to 1.2 %. Mayadas-Shatzkes theory provided a good description of these resistance changes. The negatively charged S-head of the adsorbed thiols alters the electric field experienced by conduction electrons in the Cu2O/Cu interface, modifying the electron-surface scattering.

Study of the Chemical Endurance of Particulate Reinforced Thermoplastic Composites

Polylactic acid (PLA) is a biodegradable thermoplastic made from lactic acid monomers obtained through fermented glucose in crops like wheat and corn. PLA has numerous applications, including industrial packaging, biomedical equipment, and membranes, due to its low toxicity, biodegradability, and recycling potential. However, little is known about the short-term aging effects of particulate reinforced PLA composites in complex environments. This study investigates the chemical endurance of various PLA composites before and after exposure to different chemicals and hygrothermal conditions. The results reveal that the fabrication processing method greatly affects the degradation rate. The PLA/Carbon Fiber Powder (CFP) samples had the highest chemical resistance towards degradation in 1% HNO₃ followed by 2% NaOH with a maximum mass increase of 2.8% and 3.9% respectively. The PLA/CFP samples showed lowest chemical resistance under a combination of water and aging temperature, with an average maximum weight gain of 9.64% throughout the three CFP loadings. Continuous test for 15wt% CFP sample under subsequent liquid immersion and hot air exposure had an insignificant mass loss of 0.76% but a very brittle surface with severe micro and macro cracks were present on the sample surface. In conclusion, while PLA/CFP composites demonstrate notable chemical resistance under certain conditions, the short-term aging effects, particularly under hygrothermal conditions, reveal the significance of fabrication processing methods and the potential brittleness induced by continuous exposure to specific environments, emphasizing the need for a comprehensive understanding of material behaviors.

Characterization of Porous β-Type Tricalcium Phosphate Ceramics Formed via Physical Foaming with Freeze-Drying.

Porous β-tricalcium phosphate (Ca3(PO4)2; β-TCP) was prepared via freeze-drying and the effects of this process on pore shapes and sizes were investigated. Various samples were prepared by freezing β-TCP slurries above a liquid nitrogen surface at -180 °C with subsequent immersion in liquid nitrogen at -196 °C. These materials were then dried under reduced pressure in a freeze-dryer, after which they were sintered with heating. Compared with conventional heat-based drying, the resulting pores were more spherical, which increased both the mechanical strength and porosity of the β-TCP. These materials had a wide range of pore sizes from 50 to 200 µm, with the mean and median values both approximately 100 µm regardless of the freeze-drying conditions. Mercury porosimetry data showed that the samples contained small, interconnected pores with sizes of 1.24 ± 0.25 µm and macroscopic, interconnected pores of 25.8 ± 4.7 µm in size. The effects of nonionic surfactants having different hydrophilic/lipophilic balance (HLB) values on foaming and pore size were also investigated. Materials made with surfactants having lower HLB values exhibited smaller pores and lower porosity, whereas higher HLB surfactants gave higher porosity and slightly larger macropores. Even so, the pore diameter could not be readily controlled solely by adjusting the HLB value. The findings of this work indicated that high porosity (>75%) and good compressive strength (>2 MPa) can both be obtained in the same porous material and that foaming agents with HLB values between 12.0 and 13.5 were optimal.

Study on the strength deterioration characteristic and damage model of coal pillar dams with repeated water immersion in underground reservoirs

The continuous operation of coal mine underground reservoirs exposes the coal pillar dams to mining disturbances and prolonged water immersion, resulting in the deterioration of coal pillars' mechanical properties and posing a serious threat to the dam stability. To this end, coal samples from the proposed pillar dam in the 5–2 coal seam of Daliuta Mine in Shendong Mining Area were selected for conducting water absorption tests and triaxial compression tests under conditions of repeated water immersion, in order to study the deterioration of the mechanical properties and acoustic emission damage characteristic of coal samples as well as the mechanism behind the deterioration of coal samples under the water–rock interaction. The results indicated that: (1) the saturated water content of coal samples exhibited a progressive increase as the water immersion times increased, but with a diminishing rate of growth. (2) As the water immersion times increased, the compressive strength, cohesive force, and internal friction angle of coal samples gradually decreased. Notably, the deterioration effect was more pronounced in compressive strength and cohesive force, while the decline in internal friction angle was relatively minor, and the total deterioration degree and the stage deterioration degree of the above three had evident cumulativity and non-uniformity. The progressive rise in water immersion times led to a gradual attenuation of the deterioration effect. Meanwhile, the confining pressure exhibited a certain inhibitory impact on the strength deterioration of coal samples. (3) Compared to the dry coal samples, the average AE count rate of coal samples subjected to a single water immersion exhibited a significant decrease, and subsequent water immersion for two, three, and four times resulted in a very minor decrease in the average AE count rate. (4) The AE cumulative ringing counts in coal samples exhibited varying degrees of reduction as water immersion times increased. Specifically, the most significant decrease in AE cumulative ringing counts occurred after the initial water immersion, followed by a gradual decrease thereafter. The energy-releasing capacity of coal samples decreased, while their plasticity exhibited a gradual increase. (5) A damage model was developed for coal samples based on the water immersion times. The model indicated that the damage to coal samples increased as the water immersion times increased, and the damage rate gradually decreased and eventually stabilized. (6) The deterioration mechanism of coals under the water–rock interaction was explained. Through repeated water immersion, the physical, chemical, and mechanical interactions between water and coal induced alterations in the internal microstructure of coal samples, resulting in the deterioration of mechanical properties such as compressive strength, cohesive force, and internal friction angle, which was a cumulative damage process from the microscopic to the macroscopic level.

Droplet‐Directed Anisotropic Assembly of Semifootball‐Like Carbon Nanoparticles with Multimodal Pore Architectures

AbstractHierarchical porous carbon nanoparticles, with tailored asymmetric morphologies and pore structures, have great implications in high‐performance electrode materials. However, the controlled synthesis of anisotropic carbon nanoparticles with tailored multimodal pore structures remains a challenge. Herein, a droplet‐directed anisotropic assembly approach to synthesize asymmetric carbon nanoparticles with macro/mesopores is demonstrated. This synthesis relies on the anisotropic growth of mesoporous polydopamine (PDA) seeds on the emulsion interfaces and the subsequent immersion of 1,3,5‐trimethylbenzene (TMB) droplets into the seeds. The obtained carbon nanoparticles present a semifootball‐shaped morphology with a high surface area (383 m2 g−1), well‐controlled macropores (≈105 nm), and mesopores (≈3.8 nm). By tuning the polarity of the oil phase, the morphologies transform from non‐porous spheres to semifootball‐like architectures and finally to nano‐ellipsoid with meso‐channels. The pore structures are further optimized by ZnCl2 activation, and the semifootball‐like carbon nanoparticles with modulated pore compositions deliver a high reversible capability, excellent rate performance (215 F g−1 at 0.05 A g−1 and 143 F g−1 at 20 A g−1 in organic electrolyte), and enhanced energy density (53.4 Wh Kg−1). Simulation results elucidate the structure–activity relationship between the multistage pore structure and electrochemical performance, i.e., pore hierarchy enhances ion diffusion flux, and large‐mesopore structure facilitates rate performance.

Dentin erosive wear is reduced by fluoride varnishes containing nanosized sodium trimetaphosphate in vitro.

This study evaluated the effect of fluoride varnishes containing micrometric or nanosized sodium trimetaphosphate (TMP) on dentin erosive wear in vitro. Bovine root dentin blocks were selected by surface hardness and randomly divided into five experimental groups/varnishes (n = 20/group): placebo, 5% sodium fluoride (NaF); 5% NaF+5% micrometric TMP; 5% NaF+2.5% nanosized TMP; and 5% NaF+5% nanosized TMP. Half of the surface of all blocks received a single application of the assigned varnish, with subsequent immersion in artificial saliva for 6 h. Varnishes were then removed and the blocks were immersed in citric acid (90 s, 4×/day, 5 days). After each erosive cycle, ten blocks of each group were immersed in a placebo dentifrice for 15 s (ERO), while the other ten blocks were subjected to abrasion by brushing (ERO+ABR). Dentin erosive wear was assessed by profilometry. Data were submitted to 2-way ANOVA and to the Holm-Sidak test (p<0.05). Dentin erosive wear was significantly higher for ERO+ABR than for ERO for all varnishes. TMP-containing varnishes promoted superior effects against dentin erosive wear compared with 5% NaF alone; and 5% nanosized TMP led to the lowest wear among all varnishes. In conclusion, the addition of TMP to conventional fluoride varnish (i.e., varnish containing only NaF) enhanced its protective effects against bovine root dentin erosion and erosion+abrasion. Additionally, the use of 5% nanosized TMP led to superior effects in comparison to 5% micrometric TMP, both for erosion and erosion+abrasion in vitro.

Surface Properties of Ti65Zr Alloy Modified with TiZr Oxide and Hydroxyapatite.

Titanium-zirconium dioxide nanostructures loaded by hydroxyapatite were produced on the surface of Ti65Zr alloy. The alloy was treated by anodization with the subsequent immersion in calcium glycerophosphate (CG) solutions. The resulting surfaces present TiO2-ZrO2 nanotubular (TiZr-NT) structures enriched with hydroxyapatite (HAP). The nanotube texture is expected to enhance the surface's corrosion resistance and promote integration with bone tissue in dental implants. The TiZr-NT structure had a diameter of 73 ± 2.2 nm and a length of 10.1 ± 0.5 μm. The most favorable result for the growth of HAP in Hanks' balanced salt solution (Hanks' BSS) was obtained at a CG concentration of 0.5 g/L. Samples soaked in CG at a concentration of 0.5 g/L demonstrated in a decrease of the contact angles to 25.2°; after 3 days of exposure to Hanks' BSS, the contact angles further reduced to 18.5°. The corrosion studies also showed that the TiZr-NT structure soaked in the CG = 0.5 g/L solution exhibited the best corrosion stability.

Synergistic strengthening of PVA ionic conductive hydrogels using aramid nanofibers and tannic acid for mechanically robust, antifreezing, water-retaining and antibacterial flexible sensors

Ion-conductive hydrogels with multi-functionality have gained significant attraction as flexible sensors in various fields such as wearable health monitoring and human motion detection, owing to their high ion conductivity, excellent flexibility and stretchability, and easy availability. In this work, multifunctional ion-conductive hydrogel with excellent mechanical properties, antifreezing properties, water retention and antibacterial performance was fabricated by the freeze–thaw crosslinking between polyvinyl alcohol (PVA) and aramid nanofibers (ANF), and the subsequent solution immersion crosslinking in a mixture of tannic acid (TA) and CaCl2 solution (DMSO/H2O as co-solvent). The rational engineering of a multi-spatial distributed hydrogen bond and Ca2+ coordination bond networks within the hydrogel led to a significant improvement in mechanical properties. Furthermore, through the introduction of TA and binary solvents (DMSO/H2O), the hydrogel had witnessed a substantial enhancement in its antimicrobial properties and water retention capacity. The resultant PAT5/CaCl2-5% (DMSO/H2O) hydrogel exhibited outstanding elongation at break (754.73%), tensile strength (6.25 MPa), electrical conductivity (3.09 S/m), which can be employed in flexible sensors to monitor real-time functional motion for human under diverse conditions. As such, this innovation opens up a novel pathway for envisioning flexible sensor devices, particularly in the realm of human activity monitoring.

Biodegradable Nanofiber/Metal-Organic Framework/Cotton Air Filtration Membranes Enabling Simultaneous Removal of Toxic Gases and Particulate Matter.

The typical filters that protect us from harmful components, such as toxic gases and particulate matter (PM), are made from petroleum-based materials, which need to be replaced with other environmentally friendly materials. Herein, we demonstrate a route to fabricate biodegradable and dual-functional filtration membranes that effectively remove PM and toxic gases. The membrane was integrated using two layers: (i) cellulose-based nanofibers for PM filtration and (ii) metal-organic framework (MOF)-coated cotton fabric for removal of toxic gases. Zeolitic imidazolate framework (ZIF-8) was grown from the surface of the cotton fabric by the treatment of cotton fabric with an organic precursor solution and subsequent immersion in an inorganic precursor solution. Cellulose acetate nanofibers (NFs) were deposited on the MOF-coated cotton fabric via electrospinning. At the optimal thickness of the NF layer, the quality factor of 18.8 × 10-2 Pa-1 was achieved with a filtration efficiency of 93.1%, air permeability of 19.0 cm3/cm2/s, and pressure drop of 14.2 Pa. The membrane exhibits outstanding gas adsorption efficiencies (>99%) for H2S, formaldehyde, and NH3. The resulting membrane was highly biodegradable, with a weight loss of 62.5% after 45 days under standard test conditions. The proposed strategy should provide highly sustainable material platforms for practical multifunctional membranes in personal protective equipment.

Ru anchored on Co(OH)2 nanowire arrays as highly effective electrocatalyst for full water splitting

With the development of hydrogen energy, it is necessary to develop a cost-effective catalyst for electrochemical water splitting including hydrogen evolution reaction (HER) as well as oxygen evolution reaction (OER). Co-based composites are regarded as good catalysts toward OER, but weak H adsorption abilities lead to bad HER activities. Herein, Ru anchored on Co(OH)2 nanowire arrays (Ru/Co(OH)2 NWAs) as bifunctional catalysts for alkaline water splitting, are fabricated by hydrothermal process and subsequent immersion method. Ru/Co(OH)2 NWAs catalyst exhibits excellent activity for HER and OER, owing to strong electronic interaction of Ru participant and Co(OH)2 NWAs. To catalyze 10 mA cm−2 current density for HER and OER, Ru/Co(OH)2 NWAs catalyst only needs the overpotentials of 96 and 186 mV, respectively. An alkali electrolyzer assembled by bifunctional Ru/Co(OH)2 NWAs catalyst delivers 100 mA cm−2 at a cell voltage of 1.76 V, even superior than the couples of Pt/C and RuO2 electrodes (1.88 V).

Slow Freezing of Preserved Boar Sperm: Comparison of Conventional and Automated Techniques on Post-Thaw Functional Quality by a New Combination of Sperm Function Tests.

The slow freezing of boar sperm is the only way to preserve genetic material for extended periods; this can be achieved with exposure to liquid nitrogen vapors (conventional) or by using automated freezing equipment. The aim was to compare the effect of both techniques on post-thaw functionality. Boar sperm devoid of seminal plasma and resuspended in lactose-egg yolk-glycerol medium were cryopreserved. Conventional: straws were exposed to LN2 vapors; automated: using a drop curve of -39.82 °C·min-1 for 113 s from -5 to -80 °C during the critical period; and subsequent immersion in NL2. Cell viability, cholesterol flow, mitochondrial membrane potential (MMP), lipid peroxidation, peroxynitrite, superoxide anion levels, phosphatidylserine translocation, and caspase activation were evaluated by flow cytometry. In addition, total motility (TM) and progressive motility (PM) were determined by the SCA system immediately (T0), 60 (T60), and 120 min (T120) post-thawing. Automated freezing significantly reduces cholesterol flow and free radical and lipid peroxidation levels, making it possible to preserve motility for 120 min of incubation. At the same time, viability, acrosome integrity, MMP, and caspase activation did not differ from the conventional technique. In conclusion, controlling the temperature drop curve using automated freezing equipment reduces oxidative/nitrosative stress, preserving membrane fluidity and sperm motility.

Electrospinning is a potential way for preparing edible plant protein-based nanofibers with porous surface using safflower seed meal

Food microstructure design has become an important research area in artificial food manufacturing. The fibrous structure is one of the most critical elements since it is the fundamental building blocks constructing the structure of several important food matrices. However, at present, edible fibers at nanoscale are seldomly successfully manufactured due to technical difficulties when only food-grade materials are allowed to be used. In the current study, edible nanofiber consisting of a single component of safflower seed meal protein (SMP) was prepared based on a three-step protocol consisting of electrostatic spinning, protein-cinnamaldehyde cross-linking, and subsequent immersion in the citric acid buffer to remove none-protein components. Addition of pullulan (PUL) to SMP during electrospinning facilitated fibrous structure formation. Results of SEM demonstrated that SMP: PUL = 5:5 with combined ratio 20% (w/v) in water is the upper limit to obtain well-structured composite nanofiber with no addition of Tween 80. In the second step, protein-cinnamaldehyde cross-linking was implemented to stabilize the structure of SMP. In the last step, citric acid buffer with pH4.6 was used to remove pullulan residues and thereafter nanofibers with porous surfaces composed of only SMP were successfully obtained. Our results showed that SMP single-component nanofibers had high thermal stability and good water-holding capacity, and thus suggesting that electrospinning can be a potentially innovative strategy to manufacture food fibrous microstructures especially at nanoscale.

Controlling degradable activities of water oxidation anode via facile surface reconstruction

Robustness and efficiency are crucial factors for being a highly active electrocatalyst in water electrolysis system (WES). In the case of metal oxide catalysts, the thermodynamic instability under oxygen evolution reaction (OER) condition has been a bottleneck that degrades electrode activity. In this study, we provide a post-treatment that enables further improvement of electrode activity by restructuring metal oxides. The SS-based metal oxide electrode was synthesized through hydrothermal synthesis (HY) and subsequent post-acidic immersion process (HYAi) using earth-abundant stainless steel (SS) 304 plate as a substrate material. The HYAi electrode showed improved electrochemical activities with a lower charge transfer resistance (Rct) and higher surface roughness factor (RF) compared to HY when the prolonged OER potential was applied under alkaline media. Moreover, even after 10,000 cycles of rapid cycling, HYAi showed reduced overpotential of 276.7 mV at 10 mA cm−2, while HY degraded to 304 mV. The enhanced electrochemical activities were confirmed by observing catalytic surface that conversion of oxide to stable (oxy)hydroxide was observed. Our novel approach to rearranging catalytic surface will provide deeper insights for designing improved OER catalyst.

Effect of Sequential Thermal Aging and Water Immersion on Moisture Kinetics and SBS Strength of Wet Layup Carbon/Epoxy Composites

This paper presents results of specific cases of sequential exposure of wet layup ambient cured carbon/epoxy composites to thermal aging and immersion in deionized water. Thermal aging is conducted at temperatures between 66 °C and 260 °C for periods of time up to 72 h whereas immersion is up to 72 weeks. Effects are characterized in terms of moisture kinetics using a two-stage diffusion model, and through short beam shear (SBS) strength. The response is characterized by a competition between the mechanisms of postcure, which results in increased polymerization and increases in SBS strength and glass transition temperature; and thermally induced microcracking and polymer degradation as well as moisture-induced plasticization and hydrolysis accompanied by fiber-matrix debonding, which results in deterioration. Thermal aging by itself is not seen to negatively impact SBS strength until the highest temperatures of exposure are considered in the investigation. However, the subsequent immersion in deionized water is seen to have a greater deteriorative effect with the period of post-thermal aging immersion being the dominant deteriorative factor.

Lung Cancer in the Non-smoker: A Patient View Focused on the Hopes and Challenges Facing the Non-smoker Population

A patient view paper focused on hopes and challenges facing the never smoker lung cancer population – from lived experience, unexpected diagnosis, treatment and subsequent immersion in lung cancer research and patient advocacy over many years, citing examples, references and events organised to explore the subject by UK research institutions. Material/methodsBased on lived experience, invited patient perspective conference presentations including National Cancer Research Institute (NCRI) never smoker lung cancer research strategy event opening presentation and subsequent article, includes references to relevant papers/findings and points raised during research events/group discussions, alongside personal experiences and beliefs. ResultsDiscussions with clinicians, events, surveys, meetings and virtual discussions all revealed a dearth of evidence available to identify the best way to deal with this patient cohort at almost every aspect of their experience – from missed/late diagnosis, to screening potential (non-existent), mutation driven treatments (what about those ineligible?), and psychosocial/psychological aspects given their different life stage from older traditional lung cancer patients. ConclusionMore effort and focus are needed to better understand what is driving these cases, how best to detect them sooner and respond/refer to treatments as well as developing screening methods alongside increased public and healthcare professional awareness raising and tools to support clinicians in earlier detection.

CRYOPRESERVATION OF REPRODUCTIVE CELLS OF MALE RUSSIAN STURGEON

Currently, cryopreservation of sperm is recognized as one of the promising ways to preserve the genetic diversity of fish, not only rare and endangered species, but also aquaculture objects. Scientific research was carried out in the scientific research center "Fisheries" of the S. Seifullin Kazakh Agro Technical University and the JSC "Republican Center for livestock breeding "Asyl Tulik" in 2022. The purpose of the research was to study methods of cryopreservation of Russian sturgeon sperm using cryoprotectors using dimethyl sulfide oxide with a concentration of 5% and 10% and methanol with a concentration of 3% and 8%. In the course of the research, generally accepted methods for assessing and freezing the sperm of the studied object were used. During the experimental work, the method of freezing the reproductive cells of the Russian sturgeon with a 15-minute exposure to -21°C in a box with subsequent immersion in a Dewar vessel was studied. The survival and lifetime of spermatozoa after defrosting were also studied. According to the results of the assessment of the quality of defrosted sperm of the Russian sturgeon, it was found that the most effective cryoprotective medium for cryopreservation is based on methanol with a concentration of 8%. The number of spermatozoa with translational movements in the three groups ranged from 23.8% to 31.2%. At the same time, the lifetime of spermatozoa in this cryoprotective medium was 118s. Methanol with a concentration of 8% provides the best resistance to oxidative stress experienced by cells during freezing. The results of the research make it possible to create a cryobank of the Russian sturgeon gene pool at fish hatcheries to preserve genetic diversity.

Evaluation of Francisella orientalis ΔpdpA as a Live Attenuated Vaccine against Piscine Francisellosis in Nile Tilapia.

Francisella orientalis is an important bacterial pathogen of marine and freshwater fish with worldwide distribution. Fish francisellosis is a severe subacute to chronic granulomatous disease, with high mortalities and high infectivity rates in cultured and wild fish. To date, there is no approved vaccine for this disease. In this study, we evaluated the efficacy of a defined F. orientalis pathogenicity determinant protein A (pdpA) mutant (ΔpdpA) as a live attenuated immersion vaccine against subsequent immersion challenge with the wild-type organism. Immunized Nile tilapia Oreochromis niloticus were protected (45% relative percent survival) from the lethal challenges and presented significantly lower mortality than nonvaccinated and challenged treatments. Although serum IgM was significantly higher in immunized fish, similar bacterial loads were detected in vaccinated and nonvaccinated survivors. In conclusion, although the F. orientalis ΔpdpA is attenuated and effectively stimulated an adaptive immune response, the low relative percent survival and high bacterial persistence in survivors of immunized and challenged treatments indicates low suitability of ΔpdpA as a mucosal vaccine for tilapia under conditions used in this study.

Selected mechanical properties of human cancellous bone subjected to different treatments: short-term immersion in physiological saline and acetone treatment with subsequent immersion in physiological saline

BackgroundPhysiological saline (0.9% NaCl) and acetone are extensively used for storage (as well as hydration) and removal of bone marrow, respectively, of cancellous bone during preparation and mechanical testing. Our study aimed to investigate the mechanical properties of cancellous bone subjected to short-term immersion in saline and acetone treatment with subsequent immersion in saline.MethodsCylindrical samples (Ø6 × 12 mm) were harvested from three positions (left, middle, and right) of 1 thoracic vertebral body, 19 lumbar vertebral bodies, and 5 sacral bones, as well as from 9 femoral heads. All samples were divided into two groups according to the different treatments, (i) samples from the left and middle sides were immersed in saline at 4℃ for 43 h (saline-immersed group, n = 48); (ii) samples from the respective right side were treated with a combination of acetone and ultrasonic bath (4 h), air-dried at room temperature (21℃, 15 h), and then immersed in saline at room temperature (21℃, 24 h) (acetone and saline-treated group, n = 38). All samples were subjected, both before and after treatment, to a non-destructive compression test with a strain of 0.45%, and finally destructive tests with a strain of 50%. Actual density (ρact), initial modulus (E0), maximum stress (σmax), energy absorption (W), and plateau stress (σp) were calculated as evaluation indicators.ResultsBased on visual observation, a combination of acetone and ultrasonic bath for 4 h failed to completely remove bone marrow from cancellous bone samples. The mean values of ρact, σmax, W, and σp were significantly higher in the femoral head than in the spine. There was no significant difference in E0 between non-treated and saline-immersed samples (non-treated 63.98 ± 20.23 vs. saline-immersed 66.29 ± 20.61, p = 0.132). The average E0 of acetone and saline-treated samples was significantly higher than that of non-treated ones (non-treated 62.17 ± 21.08 vs. acetone and saline-treated 74.97 ± 23.98, p = 0.043).ConclusionShort-term storage in physiological saline is an appropriate choice and has no effect on the E0 of cancellous bone. Treatment of cancellous bone with acetone resulted in changes in mechanical properties that could not be reversed by subsequent immersion in physiological saline.