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Herein, we report the optimization of Pb(II) ions removal from soil by electrokinetic remediation, using the response surface methodology (RSM) based on central composite design (CCD) describing individual and interactive effects of three chosen variables: the current intensity (I), electrolyte concentration (C) and remediation time (t). Sulfuric acid was selected as the electrolyte medium. The physicochemical properties of the soil were well characterized. The electrokinetic remediation (EKR) experiments were performed in galvanostatic mode, at constant current intensity. The lead Pb(II) content was measured using the atomic absorption spectrophotometer (AAS). Designing and modeling of the experimental runs were done using the Design Expert software. The results establish that the quadratic polynomial model matches the experimental data between the removal efficiency (η %) and the influencing factors. The obtained p-values (<0.05) through ANOVA analysis reveal a significant term, suggesting that the model was satisfactory. The significance of influencing factors increases is in that order: I < C (H2SO4) < t; increasing the remediation time translates into higher removal efficiencies. The statistical optimization strategy used in this study was successful in attaining the maximal lead removal of 86.79% using current intensity of 0.05 A, H2SO4 concentration of 0.05 M, and remediation time of 24 h 38 min. Ultimately, besides the great potential of the electrokinetic remediation for efficient removal of Pb(II) species, the RSM-based CCD is a promising and valuable tool for modeling and optimizing their elimination from contaminated soils. [ABSTRACT FROM AUTHOR]

Autonomous locomotion is a ubiquitous phenomenon in biology and in physics of active systems at microscopic scale. This includes prokaryotic, eukaryotic cells (crawling and swimming) and artificial swimmers. An outstanding feature is the ability of these entities to follow complex trajectories, ranging from straight, curved (circular, helical...), to random-like ones. The non-straight nature of these trajectories is often explained as a consequence of the asymmetry of the particle or the medium in which it moves, or due to the presence of bounding walls, etc... Here, we show that for a particle driven by a concentration field of an active species, straight, circular and helical trajectories emerge naturally in the absence of asymmetry of the particle or that of suspending medium. Our proof is based on general considerations, without referring to an explicit form of a model. We show that these three trajectories correspond to self-congruent solutions. Self-congruency means that the states of the system at different moments of time can be made identical by an appropriate combination of rotation and translation of the coordinate space. We show that these solutions are exhibited by spherically symmetric particles as a result of a series of pitchfork bifurcations, leading to spontaneous symmetry breaking in the concentration field driving the particle motility. Self-congruent dynamics in one and two dimensions are analyzed as well. Finally, we present a simple explicit nonlinear exactly solvable model of fully isotropic phoretic particle that shows the transitions from a non-motile state to straight motion to circular motion to helical motion as a series of spontaneous symmetry-breaking bifurcations. Whether a system exhibits or not a given trajectory only depends on the numerical values of parameters entering the model, while asymmetry of swimmer shape, or anisotropy of the suspending medium, or influence of bounding walls are not necessary., (© 2023. The Author(s), under exclusive licence to EDP Sciences, SIF and Springer-Verlag GmbH Germany, part of Springer Nature.)

Mammalian cells developed two main migration modes. The slow mesenchymatous mode, like crawling of fibroblasts, relies on maturation of adhesion complexes and actin fiber traction, whereas the fast amoeboid mode, observed exclusively for leukocytes and cancer cells, is characterized by weak adhesion, highly dynamic cell shapes, and ubiquitous motility on two-dimensional and in three-dimensional solid matrix. In both cases, interactions with the substrate by adhesion or friction are widely accepted as a prerequisite for mammalian cell motility, which precludes swimming. We show here experimental and computational evidence that leukocytes do swim, and that efficient propulsion is not fueled by waves of cell deformation but by a rearward and inhomogeneous treadmilling of the cell external membrane. Our model consists of a molecular paddling by transmembrane proteins linked to and advected by the actin cortex, whereas freely diffusing transmembrane proteins hinder swimming. Furthermore, continuous paddling is enabled by a combination of external treadmilling and selective recycling by internal vesicular transport of cortex-bound transmembrane proteins. This mechanism explains observations that swimming is five times slower than the retrograde flow of cortex and also that lymphocytes are motile in nonadherent confined environments. Resultantly, the ubiquitous ability of mammalian amoeboid cells to migrate in two dimensions or three dimensions and with or without adhesion can be explained for lymphocytes by a single machinery of heterogeneous membrane treadmilling., (Copyright © 2020. Published by Elsevier Inc.)

The swimming of a rigid phoretic particle in an isotropic fluid is studied numerically as a function of the dimensionless solute emission rate (or Péclet number Pe). The particle sets into motion at a critical Pe. Whereas the particle trajectory is straight at a small enough Pe, it is found that it loses its stability at a critical Pe in favor of a meandering motion. When Pe is increased further, the particle meanders at a short scale but its trajectory wraps into a circle at a larger scale. Increasing even further, Pe causes the swimmer to escape momentarily the circular trajectory in favor of chaotic motion, which lasts for a certain time, before regaining a circular trajectory, and so on. The chaotic bursts become more and more frequent as Pe increases, until the trajectory becomes fully chaotic, via the intermittency scenario. The statistics of the trajectory is found to be of the run-and-tumble-like nature at a short enough time and of diffusive nature at a long time without any source of noise.

Rechargeable magnesium batteries (rMBs) are promising as the most ideal further energy storage systems but lack competent cathode materials due to sluggish redox reaction kinetics. Herein, developed is an anionic Se-substitution strategy to improve the rate capability and the cycling stability of 2D CuS 1- x Se x nanosheet cathodes through an efficient microwave-induced heating method. The optimized CuS 1- x Se x (X = 0.2) nanosheet cathode can exhibit high reversible capacity of 268.5 mAh g -1 at 20 mA g -1 and good cycling stability (140.4 mAh g -1 at 300 mA g -1 upon 100 cycles). Moreover, the CuS 1- x Se x (X = 0.2) nanosheet cathode can deliver remarkable rate capability with a reversible capacity of 119.2 mAh g -1 at 500 mA g -1 , much higher than the 21.7 mAh g -1 of pristine CuS nanosheets. The superior electrochemical performance can be ascribed to the enhanced reaction kinetics, enriched cation storage active sites, and shortened ion diffusion pathway of the CuS 1- x Se x nanosheet. Therefore, tuning anionic chemical composition demonstrates an effective strategy to develop novel cathode materials for rMBs., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Rechargeable magnesium batteries (rMBs) have been recognized as one of most promising next-generation energy storage devices with high energy and power density. However, the development of rMBs has been hampered by the lack of usable cathode materials with high capacity and cycling stability. Herein, we report an ultra-rapid, cost-effective, and scalable synthesis of ultrathin CuS hierarchical nanosheets by a one-step microwave-assisted preparation. Benefiting from the exceptional structural configuration, when used as the cathode material for rMBs at room temperature, the CuS hierarchical nanosheets deliver a high reversible discharge capacity of 300 mA h g -1 at 20 mA g -1 , remarkable rate capability (256.5 mA h g -1 at 50 mA g -1 and 237.5 mA h g -1 at 100 mA g -1 ), and excellent cycling stability (135 mA h g -1 at 200 mA g -1 over 200 cycles). To date, the obtained excellent electrochemical performances are superior to most results ever reported for cathode materials of rMBs.

We explore in this paper the phenomenon of photofocusing: a coupling between flow vorticity and biased swimming of microalgae toward a light source that produces a focusing of the microswimmer suspension. We combine experiments that investigate the stationary state of this phenomenon as well as the transition regime with analytical and numerical modeling. We show that the experimentally observed scalings on the width of the focalized region and the establishment length as a function of the flow velocity are well described by a simple theoretical model.

The effect of a fractional epidural blockade on acute pancreatitis was investigated in a prospective study. PATIENTS AND METHODS. Thoracic (20 patients) or lumbar (six patients) epidural blockade was carried out in 26 patients with severe abdominal conditions comprising sub-ileus in 100%, pancreatic edema indicated by sonography/computer tomography in 57.8%, and necrosis of the pancreas in 34.6%. RESULTS. On average, 3.4 (1-6) injections with single doses of 6-20 ml 0.25% bupivacaine were injected per day. In four patients, morphine (up to 4 mg per 24 h) was added to the local anesthetic. The duration of treatment was between 1 and 15 days. After 10.5% of the injections, the systolic pressure decreased by more than 20%, and after 12.8% of the injections the blood pressure decreased by more than 30%. Hypotension of more than 30% was treated with 0.3 to 0.5 ml theodrenaline (Akrinor) and/or 0.1 to 0.2 mg dihydro-ergotamine (Dihydergot). General analgesics had to be administered in addition on 21.8% of the treatment days and intensive care treatment (artificial ventilation) on 32% of the treatment days. The duration of epidural analgesia varied between 1 and 15 days depending on the intensity of symptoms (pain, ileus). Within 4 days, the enzyme activity of the lipase fell from 8120 to 427 IU, and that of alpha amylase fell from 1401 to 143 IU. In 3 patients laparotomy (for drainage) was performed. An ERCP was carried out in 16 patients. Cardiopulmonary failure necessitated artificial ventilation over a period of 1-15 days in 6 patients; the epidural blockade was continued during the artificial ventilation. Cholecystectomy was carried out as an interval operation in 6 patients. No neurological complications were observed. All patients survived and were discharged from hospital.

Spinal and peridural anesthesia are most useful in lower abdominal operations. For upper laparotomies needing analgesia, good relaxation and quiet ventilation, intercostal block and peridural anesthesia with light general anesthesia are suitable techniques to avoid hypertension and metabolic responses (hyperglycemia, cortisol). During the postoperative period, regional blocks improve lung function and bowel motility, and afford early ambulation.

Since the first paravertebral blockade was carried out by Sellheim in 1905, this method has proved effective for the isolated blockade of spinal nerves. The efficacy of preoperative intercostal blockade (ICB) in combination with neuroleptanalgesia (NLA) or Pentothal-pentazocine-N2O anesthesia (Pe-Pz) was studied (unilateral analgesia for cholecystectomy). Group 1: NLA; group 2: NLA with ICB; group 3: Pe-Pz; group 4: Pe-Pz with ICB. The analgesic requirement differed significantly between groups 1 (0.33 mg fentanyl) and 2 (0.15 mg fentanyl) and groups 3 (63.5 mg pentazocine) and 4 (31.5 mg pentazocine). There were also significant differences in circulatory responses. The maximum deviation from the initial value at the beginning of the operation in group 1 compared to group 2 was pulse rate + 28.7% vs + 2.4%, mean arterial pressure (Part) + 24.6% vs + 3.1%, and systolic pressure (Psyst) + 33% vs +/- 0%; group 3 compared to group 4: pulse rate + 16.4% vs + 3.2%, Part + 24.5% vs 0.0%, and Psyst + 26.5% vs + 196. The times of action of ICB extended from 7.54 h to 11.33 h for partial analgeisa, time to the first dose of analgesic from 12.3 h to 16.9 h (etidocaine 0.5% and 1% respectively without and with epinephrine). The mean blood levels after 100 mg bupivacaine-CO2 rose to 1.16 micrograms/ml after 5 min and reached a maximum after 15 min (1.29 micrograms/ml) as compared to 0.98 micrograms/ml after addition of ornithine-vasopressin. These values are very much higher than those after the use of bupivacaine-HCl solution. Etidocaine and bupivacaine-HCl have comparable durations of analgesia. Toxicologically, both substances can be applied safely with consideration of all pharmacological data for ICB. Of a total of 3,485 intercostal blockades, 2,775 were applied perioperatively (pre- and postoperatively); 265 were carried out for trauma patients (rib fractures) and 445 for therapeutic indications (herpes zoster neuralgia, tumor pain, costovertebral pain). In 8 blocks 10% ammonium sulfate, in 4 blocks absolute alcohol, and in 19 blocks 5% phenol were used for neurolysis. In 2 cases a marginal pneumothorax was seen, which was resorbed spontaneously (0.06%). Altogether 16,270 single intercostal nerves were blocked. Single-session intercostal blockade can be combined as unilateral analgesia with general anesthesia. This combination is characterized by stable circulatory conditions with avoidance of hypertensive reactions. The long-lasting analgesia allows early mobilization and physiotherapy both postoperatively and posttraumatically in patients with unilateral thoracic and abdominal pain.(ABSTRACT TRUNCATED AT 400 WORDS)

A 6 year old boy developed a rebound of anaesthesia with abolition of reflexes and spontaneous respiration 100 min after anorectal induction with methohexitone and 20 min after extubation. The role of reliable observation during postoperative period in this type of anaesthesia is emphasized.