Changes In Ion Concentration Research Articles

Sodium and quantitative hydrogen parameter changes in muscle tissue after eccentric exercise and in delayed-onset muscle soreness assessed with magnetic resonance imaging.

The objective of the current study was to assess sodium (23 Na) and quantitative proton (1 H) parameter changes in muscle tissue with magnetic resonance imaging (MRI) after eccentric exercise and in delayed-onset muscle soreness (DOMS). Fourteen participants (mean age: 25 ± 4 years) underwent 23 Na/1 H MRI of the calf muscle on a 3-T MRI system before exercise (t0), directly after eccentric exercise (t1), and 48 h postintervention (t2). In addition to tissue sodium concentration (TSC), intracellular-weighted sodium (ICwS) signal was acquired using a three-dimensional density-adapted radial projection readout with an additional inversion recovery preparation module. Phantoms containing saline solution served as references to quantify sodium concentrations. The 1 H MRI protocol consisted of a T1 -weighted turbo spin echo sequence, a T2 -weighted turbo inversion recovery, as well as water T2 mapping and water T1 mapping. Additionally, blood serum creatine kinase (CK) levels were assessed at baseline and 48 h after exercise. The TSC and ICwS of exercised muscles increased significantly from t0 to t1 and decreased significantly from t1 to t2. In the soleus muscle (SM), ICwS decreased below baseline values at t2. In the tibialis anterior muscle (TA), TSC and ICwS remained at baseline levels at each measurement point. However, high-CK participants (i.e., participants with a more than 10-fold CK increase, n = 3) displayed different behavior, with 2- to 4-fold increases in TSC values in the medial gastrocnemius muscle (MGM) at t2. 1 H water T1 relaxation times increased significantly after 48 h in the MGM and SM. 1 H water T2 relaxation times and muscle volume increased in the MGM at t2. Sodium MRI parameters and water relaxation times peaked at different points. Whereas water relaxation times were highest at t2, sodium MRI parameters had already returned to baseline values (or even below baseline values, for low-CK participants) by this point. The observed changes in ion concentrations and water relaxation time parameters could enable a better understanding of the physiological processes during DOMS and muscle regeneration. In the future, this might help to optimize training and to reduce associated sports injuries.

Tortuous Cardiac Intercalated Discs Modulate Ephaptic Coupling.

Cardiac ephaptic coupling, a mechanism mediated by negative electric potentials occurring in the narrow intercellular clefts of intercalated discs, can influence action potential propagation by modulating the sodium current. Intercalated discs are highly tortuous due to the mingling of plicate and interplicate regions. To investigate the effect of their convoluted structure on ephaptic coupling, we refined our previous model of an intercalated disc and tested predefined folded geometries, which we parametrized by orientation, amplitude and number of folds. Ephaptic interactions (assessed by the minimal cleft potential and amplitude of the sodium currents) were reinforced by concentric folds. With increasing amplitude and number of concentric folds, the cleft potential became more negative during the sodium current transient. This is explained by the larger resistance between the cleft and the bulk extracellular space. In contrast, radial folds attenuated ephaptic interactions and led to a less negative cleft potential due to a decreased net cleft resistance. In conclusion, despite limitations inherent to the simplified geometries and sodium channel distributions investigated as well as simplifications regarding ion concentration changes, these results indicate that the folding pattern of intercalated discs modulates ephaptic coupling.

An organic artificial spiking neuron for in situ neuromorphic sensing and biointerfacing

The effective mimicry of neurons is key to the development of neuromorphic electronics. However, artificial neurons are not typically capable of operating in biological environments, which limits their ability to interface with biological components and to offer realistic neuronal emulation. Organic artificial neurons based on conventional circuit oscillators have been created, but they require many elements for their implementation. Here we report an organic artificial neuron that is based on a compact nonlinear electrochemical element. The artificial neuron can operate in a liquid and is sensitive to the concentration of biological species (such as dopamine or ions) in its surroundings. The system offers in situ operation and spiking behaviour in biologically relevant environments—including typical physiological and pathological concentration ranges (5–150 mM)—and with ion specificity. Small-amplitude (1–150 mV) electrochemical oscillations and noise in the electrolytic medium shape the neuronal dynamics, whereas changes in ionic (≥2% over the physiological baseline) and biomolecular (≥ 0.1 mM dopamine) concentrations modulate the neuronal excitability. We also create biohybrid interfaces in which an artificial neuron functions synergistically and in real time with epithelial cell biological membranes.

Demonstration of Extended-Gate Structure for Ion Sensors based on Amorphous Indium-Gallium-Zinc Oxide Thin-Film Transistors

This paper presents our work towards improving the reliability of high-sensitivity pH sensor based on the top-gate effect in an amorphous indium-gallium-zinc oxide thin-film transistor (a-InGaZnO TFT) and its application to the sensing of a sodium ion and a potassium ion. Here, we propose an extended-gate a-InGaZnO TFT pH sensor with an atomic layer deposition (ALD)-AlOx/sputtered-TaOx layered top-gate insulator and a Ti extended-gate electrode. We discuss our primary results for the extended-gate a-InGaZnO TFT pH sensor, including its pH sensitivity and ability to respond to a pH change of 0.001. The extended-gate a-InGaZnO TFT pH sensor resulted in over Nernstian pH sensitivity of 625 mV/pH. The pH sensor indicated the possibility of detecting a pH change of 0.001 with some signal processing techniques. Furthermore, we demonstrated the sensing of a sodium ion and a potassium ion with a-InGaZnO TFT and an ion-sensitive extended-gate electrode. The sensors indicated a clear response to the concentration changes of sodium and potassium ions with a sensitivity of 1030 mV/decade and 866 mV/decade, respectively. These results demonstrate that our extended-gate structure has the potential to detect with high sensitivity concentration changes in various ions just by replacing the extended-gate electrode with various ion-sensitive membranes.

MRI of Potassium and Sodium Enables Comprehensive Analysis of Ion Perturbations in Skeletal Muscle Tissue After Eccentric Exercise.

The aims were to investigate if potassium ( 39 K) magnetic resonance imaging (MRI) can be used to analyze changes in the apparent tissue potassium concentration (aTPC) in calf muscle tissue after eccentric exercise and in delayed-onset muscle soreness, and to compare these to corresponding changes in the apparent tissue sodium concentration (aTSC) measured with sodium ( 23 Na) MRI. Fourteen healthy subjects (7 female, 7 male; 25.0 ± 2.8 years) underwent 39 K and 23 Na MRI at a 7 T MR system, as well as 1 H MRI at a 3 T MR system. Magnetic resonance imaging data and blood samples were collected at baseline (t0), directly after performing eccentric exercise (t1) and 48 hours after exercise (t2). Self-reported muscle soreness was evaluated using a 10-cm visual analog scale for pain (0, no pain; 10, worst pain) at t0, t1, and t2. Quantification of aTPC/aTSC was performed after correcting the measured 39 K/ 23 Na signal intensities for partial volume and relaxation effects using 5 external reference phantoms. Edema volume and 1 H T 2 relaxation times were determined based on the 1 H MRI data. Participants were divided according to their increase in creatine kinase (CK) level into high (CK t2 ≥ 10·CK t0 ) and low CK (CK t2 < 10·CK t0 ) subjects. Blood serum CK and edema volume were significantly increased 48 hours after exercise compared with baseline ( P < 0.001). Six participants showed a high increase in blood serum CK level at t2 relative to baseline, whereas 8 participants had only a low to moderate increase in blood serum CK. All participants reported increased muscle soreness both at rest and when climbing stairs at t1 (0.4 ± 0.7; 1.4 ± 1.2) and t2 (1.6 ± 1.4; 4.8 ± 1.9) compared with baseline (0 ± 0; 0 ± 0). Moreover, aTSC was increased at t1 in exercised muscles of all participants (increase by 57% ± 24% in high CK, 73% ± 33% in low CK subjects). Forty-eight hours after training, subjects with high increase in blood serum CK still showed highly increased aTSC (increase by 79% ± 57% compared with t0). In contrast, aTPC at t2 was elevated in exercised muscles of low CK subjects (increase by 19% ± 11% compared with t0), in which aTSC had returned to baseline or below. Overall, aTSC and aTPC showed inverse evolution, with changes in aTSC being approximately twice as high as in aTPC. Our results showed that 39 K MRI is able to detect changes in muscular potassium concentrations caused by eccentric exercise. In combination with 23 Na MRI, this enables a more holistic analysis of tissue ion concentration changes.

Investigation of The Chemical Reactions of 2, 4, 6-Trinitrophenol with Thiocyanate Ion in Acidic Condition: Kinetic Approach

The rate and overall observed chemical change of the redox reaction between 2, 4, 6-trinitrophenol (TNP) and thiocyanate ion (SCN–) was investigated under a constant concentration of ionic strength, [????!] and λmax = 360 nm using a spectrophotometric titration method. The research aim is to study stoichiometry, order of reaction, the influence of acid, and the effect of change in ionic concentration on the reaction speed. The stoichiometry discovered gave a 1:2 molar proportion of TNP against SCN–. The reaction is 1st - order in relation to TNP and 1st – order in relation to SCN– hence, a 2nd -order overall for the system. An acid-dependence rate constant on TNP was positive for the TNP – SCN– system. A positive salt effect was observed in the system. An increase in the concentration of added cations and anions (Mn2+, NO3− and PO43−) had no influence on the speed of the reaction. The spectroscopic and kinetic results did not show any intermediate complex emergence all through the reaction. On grounds of the experimental results attained, a presumptive mechanism in favor of an outer-sphere mechanism has been recommended.

Effect of NaCl Solution and Simulated Concrete Pore Solution Environment on the Efficiency of Steel Bar Energized Corrosion.

As the main problem of the durability deterioration of concrete structures, the corrosion of steel bars is usually made by the method of electrified corrosion with a short cycle and low cost. However, there is a big difference between the actual corrosion depth and the theoretical corrosion depth after the reinforcement is electrified. In this paper, through the accelerated corrosion test of steel bars, the change law and influence factors of corrosion efficiency of steel bars in concrete simulated pore solution and NaCl solution are studied. The test results show that the corrosion efficiency of reinforcement in the NaCl solution is higher than that in the concrete simulated pore solution, and the corrosion efficiency in the NaCl solution changes in two stages with the corrosion degree of reinforcement. The corrosion efficiency of concrete in the simulated pore solution decreases with the increase of corrosion degree of reinforcement, which is more significant than that in the NaCl solution. Under the same conditions, the corrosion efficiency is higher in the chloride ion solution with high concentration, and the influence of chloride ion concentration change in the simulated pore solution of concrete on the corrosion efficiency is more significant. The corrosion efficiency of reinforcement under low current density is higher than that under high current density.

Temperature triggered ion-selective membranes for non-zero current electrochemical ion sensors

• A temperature triggered ion-selective membrane intended for non-zero current ion sensing is presented. • The liquid type membrane offers well developed electrochemical signals for changes of analyte ions concentration both in voltammetric and coulometric mode. • The solidified membrane is characterized by low electrochemical activity and offers easy storage. • The proposed system may be regarded as an electrochemical thermometer. A temperature triggered ion-selective membrane intended for non-zero current ion sensing is presented for the first time. At temperatures lower than 17 °C the membrane is in a solidified state, whereas above this temperature spontaneous transformation to a liquid state is observed. In the liquid state the diffusion coefficient of the analyte ions is higher than for a typical polymeric ion-selective membrane, resulting in higher current. Thus, the liquid type membrane offers well developed electrochemical signals for changes of analyte ions concentration both in voltammetric and coulometric mode, whereas the solidified type membrane is characterized by low electrochemical activity. Therefore, the herein proposed system may be regarded also as an electrochemical thermometer and it offers easy handling or storage while in the solidified form at low temperature, and benefits from liquid phase electrochemistry at room temperature.

Amperometric response of solid-contact ion-selective electrodes utilizing a two-compartment cell and a redox couple in solution

• The amperometric response of ion-selective electrodes (ISEs) was characterized utilizing a two-compartment cell. • ISEs served as potentiometric transducer when connected as reference electrode. • The amperometric response was reversible and reproducible. • The amperometric signal was optimized by applying a potential equal to the half-peak potential (E p/2 ) of the redox couple. An alternative transduction method for ion-selective electrodes (ISEs) is studied by utilizing oxidation/reduction of a Fe(CN) 6 3-/4- redox couple dissolved in solution. Two compartments are employed as electrochemical cell, connected by an Ag/AgCl bridge. A K + -selective solid-contact ISE (K + -SCISE) with reduced graphene oxide as solid contact works as reference electrode (RE) and is placed in the sample solution compartment. A gold electrode acting as working electrode (WE) and a platinum as counter electrode (CE) are placed in the detection compartment with a solution containing the Fe(CN) 6 3-/4- redox couple. As the primary ion (K + ) concentration changes, the potential of the K + -SCISE will change accordingly. Since the potential between WE and RE is kept constant by using a potentiostat, any change in the concentration of primary ion K + will result in an oxidation/reduction current from the Fe(CN) 6 3-/4- redox couple at the surface of the Au WE, causing a current flowing between the Au WE and Pt CE. The diffusion-limited current from oxidation/reduction of the Fe(CN) 6 3-/4- redox couple is linearly proportional to the logarithm of the activity of the primary ion within a certain concentration range of the primary ion. The reversibility and reproducibility of the amperometric response from oxidation/reduction of Fe(CN) 6 3-/4- is proven in this work. A unique feature of this method is that current signal can be enlarged by increasing the geometric surface area of the WE. The amperometric response of the Fe(CN) 6 3-/4- redox couple is highly dependent on the applied starting potential. The sensitivity of the amperometric response can be optimized by applying a potential equal to the half-peak potential (E p/2 ). Furthermore, the amperometric response is applied for determination of K + ion concentration in such a demanding matrix as human blood serum.

Role of Atmospheric Temperature and Seismic Activity in Spring Water Hydrogeochemistry in Urumqi, China.

Springs offer insight into the sources and mechanisms of groundwater recharge and can be used to characterize fluid migration during earthquakes. However, few reports provide sufficient annual hydrochemical and isotopic data to compare the variation characteristics and mechanisms with both atmospheric temperature and seismic effects. In this study, we used continuous δ2H, δ18O, and major ion data from four springs over 1 year to understand the groundwater origin, recharge sources, circulation characteristics, and coupling relationships with atmospheric temperature and earthquakes. We found that (1) atmospheric temperatures above and below 0 °C can cause significant changes in ion concentrations and water circulation depth, resulting in the mixing of fresh and old water in the aquifer, but it cannot cause changes in δ2H and δ18O. (2) Earthquakes of magnitude ≥ 4.8 within a 66 km epicentral distance can alter fault zone characteristics (e.g., permeability) and aggravate water–rock reactions, resulting in significant changes in δ2H, δ18O, and hydrochemical ion concentrations. (3) Hydrogen and oxygen isotopes are the most sensitive precursory seismic indicators. The results of this study offer a reference for the establishment of long-term hydrochemical and isotopic monitoring, with the potential for use in earthquake forecasting.

Changes in Ion Concentrations upon the Binding of Short Polyelectrolytes on Phospholipid Bilayers: Computer Study Addressing Interesting Physiological Consequences.

This computer study was inspired by the experimental observation of Y. Qian et al. published in ACS Applied Materials and Interfaces, 2018 that the short positively charged β-peptide chains and their oligomeric analogues efficiently suppress severe medical problems caused by antimicrobial drug-resistant bacteria despite them not penetrating the bacterial membrane. Our coarse-grained molecular dynamics (dissipative particle dynamics) simulations confirm the tentative explanation of the authors of the experimental study that the potent antimicrobial activity is a result of the entropically driven release of divalent ions (mainly magnesium ions essential for the proper biological function of bacteria) into bulk solution upon the electrostatic binding of β-peptides to the bacterial membrane. The study shows that in solutions containing cations Na+, Ca2+ and Mg2+, and anions Cl−, the divalent cations preferentially concentrate close to the membrane and neutralize the negative charge. Upon the addition of positively charged oligomer chains (models of β-peptides and their analogues), the oligomers electrostatically bind to the membrane replacing divalent ions, which are released into bulk solvent. Our simulations indicate that the entropy of small ions (which controls the behavior of synthetic polyelectrolyte solutions) plays an important role in this and also in other similar biologically important systems.

Acclimation of marine invertebrate osmolyte systems to low salinity: A systematic review &amp; meta-analysis

Salinity is a major environmental factor shaping the distribution and abundance of marine organisms. Climate change is predicted to alter salinity in many coastal regions due to sea level rise, evaporation, and changes in freshwater input. This exerts significant physiological stress on coastal invertebrates whose body fluid osmolality follows that of seawater (‘osmoconformers’). In this study, we conducted a systematic review and meta-analysis of osmolytes (both organic and inorganic) utilized by osmoconforming marine invertebrates during a &amp;gt;14-day acclimation to reduced salinity. Of the 2,389 studies screened, a total of 56 fulfilled the search criteria. Thirty-eight studies reported tissue osmolyte. Following acclimation to reduced salinity, tissue concentrations of six organic compounds and sodium were consistently reduced across phyla. This suggests that intracellular inorganic ions are not only utilized as a rapid response system during acute exposure to low salinity stress but also, in concert with reductions in organic osmolyte concentrations, during longer-term acclimation. Our systematic review demonstrates that only a few studies (n = 13) have quantified salinity-induced long-term changes in intracellular ion concentrations. In addition, no study has compiled a complete intracellular osmolyte budget. Alanine, betaine, glycine, and taurine are the major organic osmolytes that are universally employed across five phyla. The characterization of organic osmolytes was heavily weighted towards free amino acids (FAAs) and derivatives—neglecting methylamines and methylsulfonium compounds, which can be as important as FAAs in modulating intracellular osmolality. As a consequence, we suggest best-practice guidelines to streamline experimental designs and protocols in osmoregulation research in order to better understand the conserved mechanisms that define the limits of salinity acclimation in marine invertebrates. To our best knowledge, this is the first systematic review and meta-analysis on osmolyte concentrations in osmoconformers acclimated to low salinity. It creates a valuable baseline for future research and reveals large research gaps. Our meta-analysis suggests that there are common osmolyte actors employed across phyla but no uniform concept since osmolyte pool composition and proportions were taxon-specific. In light of future salinity changes and their potential consequences, it becomes more important to understand salinity tolerance capacities and limits.

Properties and stability of water-in-water emulsions stabilized by microfibrillated bacterial cellulose

The stabilization of food-grade water in water (W/W) emulsions, as a potential candidate for encapsulating water-soluble functional components, remain a significant challenge in food science research. The main purpose of the work was to find a suitable particle for the preparation of the novel W/W emulsion. This system was composed of two immiscible water-soluble biopolymers (dextran and maltodextrin), and stabilized by using bacterial cellulose (BC) nanofibrils. The BC-stabilized W/W emulsions were successfully fabricated with the 20 wt% dextran (DEX) and the 10 wt% maltodextrin (MAL). There was no significant change in the droplet size of the emulsion with increasing BC surface charge from 0.41 mmol/g to 1.41 mmol/g dry cellulose. Meanwhile, the apparent viscosity, storage modulus ( G′ ) and loss modulus ( G″ ) of the emulsions were decreased with increasing BC surface charge. The stabilization mechanism of the W/W emulsion was due to the formation of viscoelastic network structure by BC nanofibrils. When the BC content increased from 0.04 wt% to 0.16 wt%, the emulsion droplet size was decreased from 3.78 ± 0.79 μm to 2.01 ± 0.40 μm. Furthermore, the obtained W/W emulsion did not demulsify within 7 d, it had better stability than that of the reported W/W emulsion. Moreover, the BC-stabilized emulsion was insensitive to the change of ionic strength concentration (0–200 mM) and pH (3–11). In brief, it was the first report to use BC nanofibrils to stabilize the W/W emulsion, which enriched the type of W/W emulsion. • A novel W/W emulsion was developed in dextran-maltodextrin aqueous mixture. • Bacterial cellulose nanofibers could be utilized to stabilize the W/W emulsion. • A dense network structure was formed by cellulose nanofibers in the DEX phase. • The stable W/W emulsion could be stored at room temperature for more than 7 d.

Finite Element Analysis of Expansive Bedrock Considering Electro-chemo-mechanical Coupling Phenomena in Crystal Layers of Clay Minerals and Internal Structural Degradation

This research proposes a novel model targeting expansive bedrock by combining an elastoplastic model considering electro-chemo-mechanical phenomena with the Cam-clay model, based on considerations of cementation and its degradation owing to plastic deformation. Additionally, tunnel excavation and swelling analyses are demonstrated by incorporating the proposed model into a finite element analysis code. Specifically, swelling analysis is conducted by decreasing the bedrock ion concentration and by considering the groundwater supply to the tunnel. The simulation results indicate that considerable swelling occurs in a limited area, such as the bottom part of the tunnel, even though changes in ion concentration are uniformly set in the entire analysis area; moreover, swelling phenomena develop instantaneously analogous to the observational records. The simulation reveals that shear stress increases while excavating an area and that softening with plastic expansion occurs in bedrock skeleton owing to decreasing ion concentration. In addition, the yielding of the bedrock skeleton triggers a rapid internal structural degradation and swelling of the clay mineral interlaminar layers based on simulations. Thus, this study clarifies the tunnel swelling deformation mechanism as an interaction problem between coupled electro-chemo-mechanical phenomena occurring in crystal layers and a plastic phenomenon involving the internal structural degradation of the bedrock skeleton.

Focal seizures are organized by feedback between neural activity and ion concentration changes.

Human and animal EEG data demonstrate that focal seizures start with low-voltage fast activity, evolve into rhythmic burst discharges and are followed by a period of suppressed background activity. This suggests that processes with dynamics in the range of tens of seconds govern focal seizure evolution. We investigate the processes associated with seizure dynamics by complementing the Hodgkin-Huxley mathematical model with the physical laws that dictate ion movement and maintain ionic gradients. Our biophysically realistic computational model closely replicates the electrographic pattern of a typical human focal seizure characterized by low voltage fast activity onset, tonic phase, clonic phase and postictal suppression. Our study demonstrates, for the first time in silico, the potential mechanism of seizure initiation by inhibitory interneurons via the initial build-up of extracellular K+ due to intense interneuronal spiking. The model also identifies ionic mechanisms that may underlie a key feature in seizure dynamics, that is, progressive slowing down of ictal discharges towards the end of seizure. Our model prediction of specific scaling of inter-burst intervals is confirmed by seizure data recorded in the whole guinea pig brain in vitro and in humans, suggesting that the observed termination pattern may hold across different species. Our results emphasize ionic dynamics as elementary processes behind seizure generation and indicate targets for new therapeutic strategies.

A LoC Ion Imaging Platform for Spatio-Temporal Characterisation of Ion-Selective Membranes.

In this paper, a complete Lab-on-Chip (LoC) ion imaging platform for analysing Ion-Selective Membranes (ISM) using CMOS ISFET arrays is presented. An array of 128 × 128 ISFET pixels is employed with each pixel featuring 4 transistors to bias the ISFET to a common drain amplifier. Column-level 2-step readout circuits are designed to compensate for array offset variations in a range of up to ±1 V. The chemical signal associated with a change in ionic concentration is stored and fed back to a programmable gain instrumentation amplifier for compensation and signal amplification through a global system feedback loop. This column-parallel signal pipeline also integrates an 8-bit single slope ADC and an 8-bit R-2R DAC to quantise the processed pixel output. Designed and fabricated in the TSMC 180 nm BCD process, the System-on-Chip (SoC) operates in real time with a maximum frame rate of 1000 fps, whilst occupying a silicon area of 2.3 mm × 4.5 mm. The readout platform features a high-speed digital system to perform system-level feedback compensation with a USB 3.0 interface for data streaming. With this platform we show the first reported analysis and characterisation of ISMs using an ISFETs array through capturing real-time high-speed spatio-temporal information at a resolution of 16 μm in 1000 fps, extracting time-response and sensitivity. This work paves the way of understanding the electrochemical response of ISMs, which are widely used in various biomedical applications.

Resolution increase of ion-selective electrodes response by using a reversed amperometric setup

Typical ion-selective electrodes (ISEs) used in potentiometric mode suffer from low sensitivity, determined by Nernst (Nikolsky-Eisenman) equation. This limits resolution of potentiometric analysis, ultimately leading to significant problems in determination of relatively small changes of analyte ions concentration. A novel method was proposed using a ‘reversed’ amperometric setup with Ag|AgCl electrode as the working electrode and an ion-selective electrode as the reference one. Advantageously, the proposed approach does not require addition of other chemicals to the sample. A change of primary ions concentration results in change of the potential of the ISE used as the reference electrode and thus in the same change of Ag|AgCl electrode potential in amperometric (potentiostatic) mode. Due to high slope of the current vs. potential dependence for silver / silver chloride electrode small changes of ISE potential will result in significant changes of the recorded current, leading to high amplification of the analytical signal towards primary ions of the ISE. Additional unique advantage of herein proposed approach is a linear dependence of the current on analyte concentration, as tested on model examples of potassium- and calcium-selective ISEs.

High-dose radiation exposure of cold-stored whole blood does not affect hemostatic function.

Whole blood (WB) transfusion is routinely used to resuscitate severely injured military trauma patients. Blood can be stored refrigerated while still maintaining reasonable function but is susceptible to environmental influences, including radiation exposure. Immune-compromised patients are transfused with irradiated blood to inactivate donor lymphocyte function (25 Gy per Association for the Advancement of Blood and Biotherapies [AARB] standard 5.7.3.2). However, there is limited information on function of WB exposed to high radiation doses. This study aimed to determine if stored irradiated WB still retains function. This will be important if the stored blood supply is exposed to radiation in a combat situation or mass casualty incident when the need for blood will be high. Whole blood collected from healthy donors was irradiated at 0, 25, or 75 Gy and stored at 4°C. Blood cell count, blood gas chemistry, thromboelastometry, platelet aggregation, and reactive oxygen species were measured before irradiation and at 1, 7, and 14 days of storage. Irradiated WB was compared with nonirradiated WB controls. Irradiated WB stored for up to 14 days was not significantly different than nonirradiated WB in most of the parameters measured. Stored blood showed expected changes associated with functional decline at longer storage times, but irradiation did not hasten the decline. There was a significant change in potassium and sodium ion concentrations after irradiation, but the functional relevance is not clear. High-dose irradiation had little effect on stored WB. Although there were changes in plasma sodium and potassium levels, there was little to no effect on hemostasis and blood cell viability. This suggests that stored blood subjected to a radiation event generating at least a dose of 75 Gy is still suitable for transfusion, which could be particularly important in the event of a mass casualty event where a large amount of blood is needed.

Phosphorus recovery from municipal wastewater through struvite biomineralization using model gram-negative and gram-positive bacterial strains

The present study investigated struvite biomineralization potential of model gram-negative (Enterobacter cloacae) and gram-positive (Bacillus pumilus) bacterial strains in synthetic municipal wastewater. Both micro-organisms were able to precipitate struvite crystals and the growth pattern, change in pH, ammonium and phosphate ion concentration for both the cultures were comparable. The pH of the medium increased from 6.4 to 8.8 after 3 days of incubation when the cultures attained the saturation phase. The ammonium concentration increased from initial concentration of 40 mg/L to nearly 200 mg/L after 3 days of incubation for both the bacterial strains, whereas phosphate concentration decreased from initial 20 mg/L to 3.4 mg/L and 0.8 mg/L for Bacillus pumilus and Enterobacter cloacae respectively. The mechanism involved in struvite biomineralization was also explained in detail for Enterobacter cloacae and Bacillus pumilus. The precipitation of struvite by Enterobacter cloacae is due to biologically controlled mineralization while Bacillus pumilus mineralized struvite crystals through biologically induced mineralization mechanism. Results were further validated in real influent collected from a sequencing batch reactor of an influent treatment plant. Results demonstrated that Bacillus pumilus was able to precipitate crystals in real influent whereas no precipitation was observed by Enterobacter cloacae in real influent. This study gives an insight into bacterial biomineralization in wastewater to enable recovery of nutrients (phosphorus and nitrogen) and circularity in treatment plants. Further utilization of the recovered product as fertilizer can play a key role in contributing towards meeting global food security.

Preparation of a hydroxyapatite–silver gradient bioactive ceramic coating with porous structure by laser cladding: A study of in vitro bioactivity

Porous coatings play a critical role in osseointegration between the artificial joint implant and host bone. Herein, a previously developed hydroxyapatite–silver (HA-Ag) gradient bioactive ceramic coating with a three-layer structure is further improved. Through laser cladding, a bioactive porous ceramic coating was prepared by adding carboxyl multi-walled carbon nanotubes (CMWCNTs) to HA powder. In this study, the effects of the added amount of CMWCNTs on the pore size, porosity, and active substance content were investigated. The results showed that the porous structure of the bioactive surface layer was gradually changed from the round hole shape to the reticular porous shape when the addition amount of CMWCNTs was increased from 5 wt % to 20 wt %, and the most appropriate amount of CMWCNTs was 10 wt %. In addition, the biocompatibility of the porous ceramic coating, as well as its effect on the alkaline phosphatase (ALP) activity of osteoblasts, were evaluated in vitro. Simulated body fluid (SBF) soaking tests were applied to determine the changes in ion concentration and calculate the concentration quotient and transfer free energy of Ca2+ and PO43− during the soaking period in SBF. The effects of the porous ceramic coating on the nucleation and growth of HA were also validated. The results showed that the preparation of the gradient porous ceramic coating was beneficial to the nucleation and growth of apatite, further improving the bioactivity of the coating to achieve osseointegration between the artificial joint implant and host bone.