Anode Reaction Control for a Single-Compartment Electrochemical CO2 Reduction Reactor with a Surface-Activated Diamond Cathode.

The electrochemical reaction of carbon dioxide (CO2 ) in aqueous electrolyte solutions is attracting increasing attention for sustainable chemical production. Boron-doped diamond (BDD) electrodes have been previously shown to be very effective for the stable electrochemical production of formic acid from CO2 . Typically, the electrochemical production of formic acid by CO2 reduction (CO2 R) reaction is performed with a dual-compartment flow reactor equipped with a membrane separator. The problems caused by the membrane separator, such as scaling-up, complicated operational control and materials costs can be solved using a membrane free single-compartment reactor. Here we demonstrate anode reaction control for a single-compartment CO2 R flow reactor using a surface-activated BDD cathode and achieve a Faradaic efficiency for formic acid production of over 70 %.

Mitigating the impact of flip angle and orientation dependence in single compartment R2* estimates via 2-pool modeling.

PURPOSE: The effective transverse relaxation rate ( R 2 * $$ {\mathrm{R}}_2^{\ast } $$ ) is influenced by biological features that make it a useful means of probing brain microstructure. However, confounding factors such as dependence on flip angle (α) and fiber orientation with respect to the main field ( θ $$ \uptheta $$ ) complicate interpretation. The α- and θ $$ \uptheta $$ -dependence stem from the existence of multiple sub-voxel micro-environments (e.g., myelin and non-myelin water compartments). Ordinarily, it is challenging to quantify these sub-compartments; therefore, neuroscientific studies commonly make the simplifying assumption of a mono-exponential decay obtaining a single R 2 * $$ {\mathrm{R}}_2^{\ast } $$ estimate per voxel. In this work, we investigated how the multi-compartment nature of tissue microstructure affects single compartment R 2 * $$ {\mathrm{R}}_2^{\ast } $$ estimates. METHODS: We used 2-pool (myelin and non-myelin water) simulations to characterize the bias in single compartment R 2 * $$ {\mathrm{R}}_2^{\ast } $$ estimates. Based on our numeric observations, we introduced a linear model that partitions R 2 * $$ {\mathrm{R}}_2^{\ast } $$ into α-dependent and α-independent components and validated this in vivo at 7T. We investigated the dependence of both components on the sub-compartment properties and assessed their robustness, orientation dependence, and reproducibility empirically. RESULTS: R 2 * $$ {\mathrm{R}}_2^{\ast } $$ increased with myelin water fraction and residency time leading to a linear dependence on α. We observed excellent agreement between our numeric and empirical results. Furthermore, the α-independent component of the proposed linear model was robust to the choice of α and reduced dependence on fiber orientation, although it suffered from marginally higher noise sensitivity. CONCLUSION: We have demonstrated and validated a simple approach that mitigates flip angle and orientation biases in single-compartment R 2 * $$ {\mathrm{R}}_2^{\ast } $$ estimates.

Spiking Neural Networks and Mathematical Models.

Neural networks are applied in various scientific fields such as medicine, engineering, pharmacology, etc. Investigating operations of neural networks refers to estimating the relationship among single neurons and their contributions to the network as well. Hence, studying a single neuron is an essential process to solve complex brain problems. Mathematical models that simulate neurons and the way they transmit information are proven to be an indispensable tool for neuroscientists. Constructing appropriate mathematical models to simulate information transmission of a biological neural network is a challenge for researchers, as in the real world, identical neurons in terms of their electrophysiological characteristics in different brain regions do not contribute in the same way to information transmission within a neural network due to the intrinsic characteristics. This review highlights four mathematical, single-compartment models: Hodgkin-Huxley, Izhikevich, Leaky Integrate, and Fire and Morris-Lecar, and discusses comparison among them in terms of their biological plausibility, computational complexity, and applications, according to modern literature.

Dual expression of constitutively active Gαs-protein-coupled receptors differentially establishes the resting activity of the cAMP-gated HCN2 channel in a single compartment.

The hyperpolarization-activated cyclic nucleotide-gated 2 (HCN2) channel is a major subtype of the HCN channel family expressed in the nervous system that sets the membrane potential, regulates cell excitability and senses changes in the extracellular environment. Neurons express various Gαs-protein-coupled receptors (GPCRs), many of which show ligand-independent constitutive activity. These membrane-bound proteins are expressed in various subcellular compartments of neurons. Therefore, some proportion of HCN2 channels opens in response to the basal cAMP pool size produced by constitutively active GPCRs. Here, we employed an exogenous HEK293 expression system and voltage-clamp patch-clamp recordings to investigate basal HCN2 channel activity in the presence of two GPCRs with diverse basal activities in a single compartment. We utilized the ß2-adrenoceptor (ß2AR) together with odorant receptors (ORs), as both GPCR families are known to show strong basal activity. Consequently, ß2AR alone strongly enhanced the activity of HCN2 channels, and co-expression of ORs further diversified the HCN2 channel activity, which was totally abolished by an adenylate cyclase inhibitor. Thus, we conclude that the dual expression of constitutively active GPCRs establishes the diverse range of the basal cAMP pool size in resting cells through mutual additive or suppressive interactions, even in the absence of external stimulation.

Prospective observational study of single- or multi-compartment pressure ulcer prevention cushions: PRESCAROH project.

OBJECTIVE: In patients with reduced mobility, specialised pressure-relieving supports (mattresses, beds and cushions) are widely used to reduce or relieve the interface pressure between the skin and support surfaces to prevent incidence of pressure ulcers (PUs). The primary objective of these two observational studies was to assess the incidence of PUs in patients at high risk of PUs, seated in a wheelchair using a single- or multi-compartment air cushion. The level of patient satisfaction with the comfort and the views of the care team that used the air cushions were considered as secondary objectives. METHOD: The PRESCAROH project was two prospective observational studies conducted in patients free of PUs at baseline and at high risk of PUs (Braden score ≤13 or ≤16 for people with spinal cord injury). Patients had to spend more than eight hours a day in a wheelchair and use either a single-compartment air cushion (patient without asymmetry of support) for the first study or a multi-compartment air cushion (patient with asymmetry of support) for the second study. The primary end point was the percentage of patients in whom a PU (sacrum and/or ischium) developed over a 35-day period. The analysis was performed on the full-analysis set (FAS) of patients included with at least a second assessment. RESULTS: We recruited 152 patients, 78 seated on a single-compartment air cushion (SiCAC group) and 74 on a multi-compartment air cushion (MuCAC group), in the two independent studies. All patients were included in the FAS (n=152). Most patients had spinal cord injuries. The average time spent sitting was 10.2 (standard deviation (SD): 2.3) hours a day in the SiCAC group and 9.1 (SD: 1.9) hours a day in the MuCAC group. In the SiCAC group, 6.4% (5/78) of patients dropped out of the study (one patient because of pulmonary infection and four patients for cushion installation problems). In the MuCAC group, 8.1% (6/74) of patients dropped out of the study (three patients because of adverse events not related to cushions, two for onset of PU, one for cushion-related problem). Over the study period of 35 days, 2.6% (2/78) [95% confidence interval (CI): 0.3-9.0%] of patients in the SiCAC group and 4.0% (3/74) [95%CI: 0.8-11.4%] in the MuCAC group developed a PU. CONCLUSION: These two observational studies showed that in patients at high risk of PUs and seated for more than eight hours a day in a wheelchair, the use of a single-compartment or multi-compartment air cushion with telescopic cells was associated with a low incidence of PUs.

Outcomes of sacrocolpopexy/sacrohysteropexy with mesh placement targeted to affected compartment.

OBJECTIVE: No recommendation regarding the number of meshes to be implanted in laparoscopic genital prolapse surgery exists. Is it necessary to implant a mesh into a compartment that is not affected to prevent its prolapse in the follow-up? Our objective was to compare the long-term outcomes of laparoscopic sacrocolpopexy according to compartments where mesh was implanted. STUDY DESIGN: This is a retrospective cohort study of 328 patients after laparoscopic sacrocolpopexy at our centre in 7/2005 - 3/2021. 294 patients with perioperative data and POP-Q and/or prolapse symptoms in mean follow-up of 42.8 months was available for the outcome analysis. Surgical failure was defined as prolapse beyond hymen, subjective recurrence or retreatment. The women were divided into four groups depending on compartments, where the mesh was implanted. Group A - anterior, group P - posterior, Group AP - compound of patients with anterior or posterior single arm mesh placement and (B), with anterior and posterior arm placement. Groups AP and B were compared for feasibility of single compartment mesh implantation. Comparison of groups A and P allowed assessment of non-inferiority of single anterior vs. posterior compartment placement. The data were compared using Wilcoxon Two Sample test, Chi-square test or Fishers Exact test, p-value < 0.05 was considered statistically significant. RESULTS: A single compartment mesh implantation was associated with shorter operating time and hospital stay and comparable incidence of complications. A statistically significant difference in all POP-Q points in favour of group B was observed, however, with comparable rate of prolapse beyond hymen(6.3%AP vs. 7.8%B). Similar frequency of surgical failure (17.5%AP vs. 13.8%B) and incidence of de novo pelvic floor disorders or pain was observed. Comparison of groups A and P showed higher suspension of point C in group P(-2.6 vs. -4.0, p < 0.05) with no difference in points Ba, Bp, surgical failure rate and de novo pelvic floor disorders. CONCLUSION: Implantation of a single sheet of mesh was not associated with inferior outcome to implantation of mesh to both compartments. Laparoscopic sacrocolpopexy with a single mesh arm placed into the affected compartment along with apical suspension does not induce a de novo prolapse in unoperated compartment.

Phosphate recovery and simultaneous nitrogen removal from urine by electrochemically induced struvite precipitation.

The direct discharge of urine into water bodies leads to environmental pollution, and an increase in the water treatment cost, whereas recycling of the nutrients in urine is of significant economic value. A single-compartment reactor was investigated for the recycling of phosphate and simultaneous removal of nitrogen from urine wastewater by electrochemical magnesium induction, and electrochemical oxidation for the removal of residual nitrogen from the supernatant. The results demonstrated that phosphate recovery capacity was greater than 11 mg P cm-2 h-1 at a current density of 15 m A cm-2 and anodizing time of 20 min; the removal rates of ammonium and total nitrogen in the synchronous electrochemical oxidation were 80% and 75%, respectively, at a current density of 45 m A cm-2 and anodizing time of 60 min. The anodizing time and initial pH were determined to be critical control factors in the electrochemical struvite induction and nitrogen electrochemical oxidation. The on-site electrochemical nitrogen oxidation could rapidly utilize the alkaline supernatant following phosphate recovery. Thus, the integration of the single-compartment reactor, electrochemical magnesium dosage, and simultaneous nitrogen electrochemical oxidation demonstrates potential for application to decentralized reactors to treat source-separated urine.

Pharmacokinetics of metformin in patients with chronic kidney disease stage 4 and metformin-naïve type 2 diabetes.

The pharmacokinetics of metformin therapy in patients with chronic kidney disease stage 4 (CKD-4) were studied using data from the largest Phase I consecutive cohort trial yet performed in this population. Eighteen metformin-naïve men and women with Type 2 Diabetes and creatinine clearance (CrCl) in the range 18-49 mL/min (eGFR 15-29 mL/min/1.73 m2) were allocated to daily immediate-release metformin of 250 mg, 500 mg, or 1000 mg. A first-dose profile and trough concentrations for 4 weeks were taken on all patients. Pharmacokinetic (PK) parameters were estimated by fitting a first-order compartment model with absorption in a peripheral compartment to concentrations measured 24 hours post-first dose. Single-dose PK parameters time to maximum concentration (tmax) and maximum concentration (Cmax) were consistent with previous observations in patients with normal renal function (healthy and diabetic), as was the association between CrCl and apparent total oral clearance (Cl/F). However, patients with a CrCl below 32 mL/min had trough concentrations that were consistently above the steady-state minimum implied by the population PK model. This suggests the model may not apply to patients with CrCl below 32 mL/min. Metformin in doses of 500-1000 mg/day could be taken by CKD-4 patients. However, the single-compartment model breaks down as CrCl declines below 32 mL/min suggesting that metformin levels should be monitored regularly in progressive stage 4 CKD.

A Computational Framework for Realistic Retina Modeling.

Computational simulations of the retina have led to valuable insights about the biophysics of its neuronal activity and processing principles. A great number of retina models have been proposed to reproduce the behavioral diversity of the different visual processing pathways. While many of these models share common computational stages, previous efforts have been more focused on fitting specific retina functions rather than generalizing them beyond a particular model. Here, we define a set of computational retinal microcircuits that can be used as basic building blocks for the modeling of different retina mechanisms. To validate the hypothesis that similar processing structures may be repeatedly found in different retina functions, we implemented a series of retina models simply by combining these computational retinal microcircuits. Accuracy of the retina models for capturing neural behavior was assessed by fitting published electrophysiological recordings that characterize some of the best-known phenomena observed in the retina: adaptation to the mean light intensity and temporal contrast, and differential motion sensitivity. The retinal microcircuits are part of a new software platform for efficient computational retina modeling from single-cell to large-scale levels. It includes an interface with spiking neural networks that allows simulation of the spiking response of ganglion cells and integration with models of higher visual areas.

Single compartment drug delivery.

Drug design is built on the concept that key molecular targets of disease are isolated in the diseased tissue. Systemic drug administration would be sufficient for targeting in such a case. It is, however, common for enzymes or receptors that are integral to disease to be structurally similar or identical to those that play important biological roles in normal tissues of the body. Additionally, systemic administration may not lead to local drug concentrations high enough to yield disease modification because of rapid systemic metabolism or lack of sufficient partitioning into the diseased tissue compartment. This review focuses on drug delivery methods that physically target drugs to individual compartments of the body. Compartments such as the bladder, peritoneum, brain, eye and skin are often sites of disease and can sometimes be viewed as "privileged," since they intrinsically hinder partitioning of systemically administered agents. These compartments have become the focus of a wide array of procedures and devices for direct administration of drugs. We discuss the rationale behind single compartment drug delivery for each of these compartments, and give an overview of examples at different development stages, from the lab bench to phase III clinical trials to clinical practice. We approach single compartment drug delivery from both a translational and a technological perspective.