Potassium Activity Research Articles

Low potassium activation of proximal mTOR/AKT signaling is mediated by Kir4.2

The renal epithelium is sensitive to changes in blood potassium (K+). We identify the basolateral K+ channel, Kir4.2, as a mediator of the proximal tubule response to K+ deficiency. Mice lacking Kir4.2 have a compensated baseline phenotype whereby they increase their distal transport burden to maintain homeostasis. Upon dietary K+ depletion, knockout animals decompensate as evidenced by increased urinary K+ excretion and development of a proximal renal tubular acidosis. Potassium wasting is not proximal in origin but is caused by higher ENaC activity and depends upon increased distal sodium delivery. Three-dimensional imaging reveals Kir4.2 knockouts fail to undergo proximal tubule expansion, while the distal convoluted tubule response is exaggerated. AKT signaling mediates the dietary K+ response, which is blunted in Kir4.2 knockouts. Lastly, we demonstrate in isolated tubules that AKT phosphorylation in response to low K+ depends upon mTORC2 activation by secondary changes in Cl- transport. Data support a proximal role for cell Cl- which, as it does along the distal nephron, responds to K+ changes to activate kinase signaling.

Multicriteria optimization of the composition, thermodynamic and strength properties of fly-ash as an additive in metakaolin-based geopolymer composites

This paper presents the construction of intelligent systems for selecting the optimum concentration of geopolymer matrix components based on ranking optimality criteria. A peculiarity of the methodology is replacing discrete time intervals with a sequence of states. Markov chains represent a synthetic property accumulating heterogeneous factors. The computational basis for the calculations was the digitization of experimental data on the strength properties of fly ashes collected from thermal power plants in the Czech Republic and used as additives in geopolymers. A database and a conceptual model of priority ranking have been developed, that are suitable for determining the structure of relations of the main factors. Computational results are presented by studying geopolymer matrix structure formation kinetics under changing component concentrations in real- time. Multicriteria optimization results for fly-ash as an additive on metakaolin-based geopolymer composites show that the optimal composition of the geopolymer matrix within the selected variation range includes 100 g metakaolin, 90 g potassium activator, 8 g silica fume, 2 g basalt fibers and 50 g fly ash by ratio weight. This ratio gives the best mechanical, thermal, and technological properties.

Paddy management controls potassium release from minerals in purple soils after 40 years of cultivation

AbstractThis study explored the mechanisms underlying the release and transformation of potassium from potassium‐rich minerals in paddy soils derived from purple soils. While potassium is abundant in these minerals, it is typically insoluble and inaccessible to plants. The agricultural practices employed in paddy soils may activate insoluble mineral potassium, potentially reducing potassium fertilizer applications. The activation of mineral potassium not only helps alleviate the dependence on soluble potassium fertilizers in rice cultivation, but also contributes to enhancing food security and sustainable agricultural development. Despite these potential benefits, the transformation pathways of mineral potassium in paddy soils remain unclear, posing an important science question that requires further investigation. This study collected data from a long‐term fertilizer experiment of paddy soils derived from purple soils with abundant potassium‐rich minerals (1982–2019, rice‐wheat rotation). The results revealed that paddy management could drive the transformation of potassium in illite minerals in paddy soils and meet the long‐term growth needs of crops. Submergence reduction significantly increased the concentration of positive ions such as Fe2+ and Ca2+ and provided a pathway for the free movement of ions, promoting the substitution of these ions with interlayer potassium of minerals. This substitution and alternating reduction and oxidation conditions played an important role in the transformation of potassium in illite minerals. The study indicates the promising potential for using crushed illite rocks in rice paddies as a substitute for traditional potassium fertilizers.

Metasomatism of mafic-intermediate rocks in the Motloutse Complex, Botswana: Effect on ore mineralization and implication for the Paleoproterozoic Large Alkali Metasomatic Province (LAMP) in southern Africa

Alkali metasomatism is a common overprint in Archean medium- to high-grade metamorphic terranes. Since mafic-intermediate rocks are able to host ore mineralization, it is important to understand the effect of metasomatism on its distribution. This study presents field, petrographic, mineralogical, geochemical, and U-Pb/40Ar-39Ar geochronologic characteristics of metasomatized amphibolite, amphibole gneiss and gabbro along a regional E-W section of the southeastern Motloutse Complex in eastern Botswana. The progressive metasomatism accompanies shear deformation and is visually manifested by varying degrees of pinkish discoloration of the host rocks. The metasomatic reactions in amphibolite, amphibole gneiss and gabbro are manifested in replacement of amphibole, clinopyroxene, ilmenite and plagioclase by the assemblages of chlorite, epidote, titanite, magnetite, sericite, albite and K-feldspar, up to near complete albitization and K-feldspathization with few relics of earlier minerals. Mineral compositions reflect the effects of a progressive metasomatic overprint. The metasomatic overprint resulted in the break down and dispersal of primary Cu-Ni sulphides. The pseudosection modelling (PERPLE_X) in terms of lg(aK2O) and lg(aH2O) parameters for representative compositions of leucocratic and melanocratic amphibolites, amphibole gneiss and gabbro indicates that the metasomatic process involved an increase of potassium activity followed by hydration. The modelling explains variable extent of metasomatism in different rock types. Whole-rock compositional variations indicate a general enrichment in Na2O, K2O and SiO2, and depletion in FeO and MgO in rocks during the metasomatism. 40Ar/39Ar amphibole and U-Pb titanite geochronology from metasomatized amphibolite and gabbro gave comparable ages of c.2.01–1.96 Ga. Alkaline fluids producing metasomatism were likely of crustal origin and moved along the reactivated regional c.2.01–1.95 Ga shear zones at the boundaries of the Motloutse-Limpopo complexes with the adjacent Zimbabwe and Kaapvaal cratons. Implications for a Paleoproterozoic Large Alkali Metasomatic Province (LAMP) in southern Africa, and its relation to the Bushveld large igneous province (LIP) is explored.

Unraveling the characteristics of geopolymer mortars: A deep dive into the impact of marble powder as fine aggregate and varied activators

This study addresses the literature gap by investigating the durability effects of potassium activators in metakaolin (MK) and granulated blast furnace slag (GBFS) based geopolymer mortars (GMs), particularly in freezing-thawing cycles and sulfate resistance. It explores enhancing GMs' strength and sustainability with marble powder (MP). The research evaluates GMs' resilience against high temperatures, freezing-thawing cycles, and sulfate exposure by assessing binders, activators, molarity optimization, and mechanical properties. Using NaOH+Na2SiO3 and KOH+K2SiO3 activators, GM formulations began with a 100% RILEM sand series (6–12 M). Compressive, flexural strength and UPVs were assessed at 7, 28, and 90 days. Optimal ratios were 0.9 for sodium-activated GMs and 0.8 for potassium-activated GMs. Maintaining a consistent 50% MK and 50% GBFS binder, MP was added to the mixture with optimum molarity. Using RILEM sand as a fine aggregate, GMs exhibited an optimum molarity of 10 M. Surpassing 50% MP adversely affected strength. Both activators excelled in the 100% RILEM sand series, reaching 45 MPa compressive strength at 28 days and 50 MPa at 90 days. High-temperature analyses showed a decrease at 300°C compared to the 90-day series, and the compressive strength of KOH+K2SiO3-activated GMs increased at 600°C. Analyses at 900°C revealed significant reductions, exacerbated by MP replacing RILEM sand. Freezing-thawing and sulfate resistance tests negatively impacted GMs when replacing RILEM sand with MP, with the KOH+K2SiO3 activator having a more pronounced influence. Incorporating MP into GMs enhances performance and promotes sustainable production, offering benefits in both performance and environmental aspects.

Assessment of primordial radionuclides and radon exhalation in granitic terrain of Bengaluru, India

This study delves into an investigation of primordial radionuclides and radon exhalation potential in natural soil and rock samples collected from the granitic terrain of Bengaluru, Karnataka, India. Employing a Smart RnDuo monitor and HPGe-based gamma spectrometry, the analysis reveals significantly elevated average specific radium, thorium, and potassium activities compared to the global averages documented by UNSCEAR. The research work evaluates radiological parameters in these samples, confirming compliance with global safety limits. Absorbed dose rates, hazard indices, and dose levels align with recommended standards, underscoring the safety of the assessed environment. Notably, the radon exhalation potential of these samples spans a range of 17 ± 1.3 mBq/kg/h to 179.42 ± 10.6 mBq/kg/h, accompanied by corresponding radon emanation factors varying from 5.1 ± 0.3 % to 45.4 ± 3.1 %, with an arithmetic mean of 18.0 ± 1.1 %. Intriguingly, a positive correlation emerges between the radon exhalation rate and both radium content and emanation factor. This research sheds light on the unique radiological characteristics of the Bengaluru granitic terrain, offering insights into the local radon risk and contributing to the broader understanding of radionuclide distribution in geologically diverse regions.

Estimation of 226Ra, 232Th and 40K activity from the Soil Samples of Ganderbal and Budgam Districts of Jammu and Kashmir, India

Abstract The study of radionuclides is very important in our daily life as these impose health implications to the general public. In present study the estimation of radionuclides in Ganderbal and Budgam districts of Kashmir Province using NaI(Tl) gamma-ray spectro-meter has been carried out. Radium, thorium, and potassium activity concentrations have been observed to range from 25±3 to 33±5 Bqkg−1, 3±2 to 11±3 Bqkg−1 and 415±63 to 601±80 Bqkg−1with average values of 29 Bqkg−1, 5 Bqkg−1 and 514 Bqkg−1, respectively. The radium equivalent activity (Raeq) for the soil samples has been evaluated and was found in the range of 107 to128 Bqkg−1 with the mean value of 116 Bqkg−1. It has been inferred that the radium equivalent activity (Raeq) lies in the permissible limits of 370 Bqkg−1 set by United Nations Scientific Committee on the Effects of Atomic Radiation. Absorbed dose and annual effective dose (indoor and outdoor) values were found to vary from 34 to 43 nGyh−1, 0.17 to 0.21 mSv and 0.04 to 0.05 mSv, respectively. Also, hazard indices (external and internal) are calculated from the specific concentration of radium, thorium and potassium which are found less than unity as recommended by organization for economic cooperation and development (OECD). Therefore, it can be concluded that the present study area does not pose any health implication to the general public.

Uridine as a Regulator of Functional and Ultrastructural Changes in the Brain of Rats in a Model of 6-OHDA-Induced Parkinson's Disease.

Using a model of Parkinson's disease (PD) induced by the bilateral injection of neurotoxin 6-hydroxydopamine (6-OHDA) into rat brain substantia nigra (SN), we showed uridine to exert a protective effect associated with activation of the mitochondrial ATP-dependent potassium (mitoK-ATP) channel. Injection of 4 µg neurotoxin evoked a 70% decrease in the time the experimental animal spent on the rod in the RotaRod test, an increase in the amount of lipid peroxides in blood serum and cerebral-cortex mitochondria and the rate of reactive oxygen species formation, and a decrease in Ca2+ retention in mitochondria. Herewith, lymphocytes featured an increase in the activity of lactate dehydrogenase, a cytosolic enzyme of glycolysis, without changes in succinate-dehydrogenase activity. Structural changes occurring in the SN and striatum manifested themselves in the destruction of mitochondria, degeneration of neurons and synapses, and stratification of myelin sheaths in them. Subcutaneous injections of 30 µg/kg uridine for 22 days restored the neurotoxin-induced changes in these parameters to levels close to the control. 5-Hydroxydecanoate (5 mg/kg), a specific mitoK-ATP channel inhibitor, eliminated the beneficial effect of uridine for almost all characteristics tested, indicating the involvement of the mitoK-ATP channel in the protective effect of uridine. The mechanism of the protective effect of uridine and its therapeutic applications for the prevention and treatment of PD are discussed.

Multi-criteria optimization of geopolymer foam composition

This study presents an approach to synthesizing a mathematical model for determining the composition of geopolymer foams. The focus is on improving the accuracy of multicriteria optimization for metakaolin-based geopolymer composite composition. Experimental data on the physical and mechanical properties of geopolymers are digitized to establish the computational basis for these calculations. Optimization criteria include density, porosity, compressive strength, flexural strength, Young's modulus, volumetric heat capacity, thermal diffusivity, and thermal conductivity. In addition, parameters such as shrinkage, processability, adsorption, adhesion, and economic aspects are also considered. The proposed format aims to fine-tune the geopolymer composite formulation by using the developed model for multi-criteria analysis of technological and physical-mechanical properties of foamed geopolymer composite materials (FGCM). A synthesis of mathematical models including the main criterion, suboptimization, generalized criterion, lexicographic optimization, sorting of alternatives, interval values, and decision tree methods was used to develop methods for multi-criteria optimization of the composition of foamed geopolymers. The study additionally uses the method of criteria convolution, in which the indices of specific criteria are modified in the form of a ratio scale to clarify the limits and boundaries of changes in the composition of the geopolymer mixture. This minimizes contradictory conclusions and expert opinions and highlights the extreme values for each group of parameters. By filtering the raw information, the accuracy of estimates is improved. The exclusivity of the proposed model for determining the composition of foamed geopolymers lies in the possibility of selecting the necessary formulation by mathematical processing of digitized information of the results of measurements of physical-mechanical and operational-technological properties according to the proposed innovative algorithms and schemes. Compared to existing methods, the focus of the proposed method allows for solving problems that are inaccessible to direct observation. This is due to the discovery of hidden information about the interaction of structural and strength parameters. Combining subjective and objective elements of the choice of the optimal geopolymer formulation, the proposed methodology of information processing allows for improving the quality of determining the optimal composition of the geopolymer mixture. The results of multicriteria optimization for foamed geopolymer indicate that the optimal component composition of the geopolymer matrix, within the selected range of variation, consists of 100g metakaolin, 90g potassium activator, 5g silica fume, 100g silica sand, 7g basalt fiber, and 3g aluminum. These proportions yield the best mechanical, thermal, and technological properties.

ATP-sensitive inward rectifier potassium channels regulate secretion of pro-feeding salivary proteins in the lone star tick (Amblyomma americanum)

Understanding the physiological and molecular regulation of tick feeding is necessary for developing intervention strategies to curb disease transmission by ticks. Pharmacological activation of ATP-gated inward rectifier potassium (KATP) channels reduced fluid secretion from isolated salivary gland and blood feeding in the lone star tick, Amblyomma americanum, yet the temporal expression pattern of KATP channel proteins remained unknown. KATP channels were highly expressed in type II and III acini in off-host stage and early feeding phase ticks, yet expression was reduced in later stages of feeding. We next assessed KATP channel regulation of the secreted proteome of tick saliva. LC-MS/MS analysis identified 40 differentially secreted tick saliva proteins after exposure to KATP activators or inhibitors. Secretion of previously validated tick saliva proteins that promote tick feeding, AV422, AAS27, and AAS41 were significantly reduced by upwards of 8 log units in ticks exposed to KATP channel activators when compared to untreated ticks. Importantly, activation of KATP channels inhibited tick feeding and vice versa for KATP channel inhibitors. Data indicate KATP channels regulate tick feeding biology by controlling secretion of pro-feeding proteins that are essential during early feeding phases, which provides insights into physiological and molecular regulation of tick feeding behavior.

ATP-gated potassium channels contribute to ketogenic diet-mediated analgesia in mice

Chronic pain is a substantial health burden and options for treating chronic pain remain minimally effective. Ketogenic diets are emerging as well-tolerated, effective therapeutic strategies in preclinical models of chronic pain, especially diabetic neuropathy. We tested whether a ketogenic diet is antinociceptive through ketone oxidation and related activation of ATP-gated potassium (KATP) channels in mice. We demonstrate that consumption of a ketogenic diet for one week reduced evoked nocifensive behaviors (licking, biting, lifting) following intraplantar injection of different noxious stimuli (methylglyoxal, cinnamaldehyde, capsaicin, or Yoda1) in mice. A ketogenic diet also decreased the expression of p-ERK, an indicator of neuronal activation in the spinal cord, following peripheral administration of these stimuli. Using a genetic mouse model with deficient ketone oxidation in peripheral sensory neurons, we demonstrate that protection against methylglyoxal-induced nociception by a ketogenic diet partially depends on ketone oxidation by peripheral neurons. Injection of tolbutamide, a KATP channel antagonist, prevented ketogenic diet-mediated antinociception following intraplantar capsaicin injection. Tolbutamide also restored the expression of spinal activation markers in ketogenic diet-fed, capsaicin-injected mice. Moreover, activation of KATP channels with the KATP channel agonist diazoxide reduced pain-like behaviors in capsaicin-injected, chow-fed mice, similar to the effects observed with a ketogenic diet. Diazoxide also reduced the number of p-ERK+ cells in capsaicin-injected mice. These data support a mechanism that includes neuronal ketone oxidation and activation of KATP channels to provide ketogenic diet-related analgesia. This study also identifies KATP channels as a new target to mimic the antinociceptive effects of a ketogenic diet.

A Novel Role of Uricosuric Agent Benzbromarone in BK Channel Activation and Reduction of Airway Smooth Muscle Contraction.

The uricosuric drug benzbromarone, widely used for treatment of gout, hyperpolarizes the membrane potential of airway smooth muscle cells, but how it works remains unknown. Here we show a novel role of benzbromarone in activation of large conductance calcium-activated K+ channels. Benzbromarone results in dose-dependent activation of macroscopic big potassium (BK) currents about 1.7- to 14.5-fold with an EC50 of 111 μM and shifts the voltage-dependent channel activation to a more hyperpolarizing direction about 10 to 54 mV in whole-cell patch clamp recordings. In single-channel recordings, benzbromarone decreases single BKα channel closed dwell time and increases the channel open probability. Coexpressing β1 subunit also enhances BK activation by benzbromarone with an EC50 of 67 μM and a leftward shift of conductance-voltage (G-V) curve about 44 to 138 mV. Site-directed mutagenesis reveals that a motif of three amino acids 329RKK331 in the cytoplasmic linker between S6 and C-terminal regulator of potassium conductance (RCK) gating ring mediates the pharmacological activation of BK channels by benzbromarone. Further ex vivo assay shows that benzbromarone causes reduction of tracheal strip contraction. Taken together, our findings demonstrate that uricosuric benzbromarone activates BK channels through molecular mechanism of action involving the channel RKK motif of S6-RCK linker. Pharmacological activation of BK channel by benzbromarone causes reduction of tracheal strip contraction, holding a repurposing potential for asthma and pulmonary arterial hypertension or BK channelopathies. SIGNIFICANCE STATEMENT: We describe a novel role of uricosuric agent benzbromarone in big potassium (BK) channel activation and relaxation of airway smooth muscle contraction. In this study, we find that benzbromarone is an activator of the large-conductance Ca2+- and voltage-activated K+ channel (BK channel), which serves numerous cellular functions, including control of smooth muscle contraction. Pharmacological activation of BK channel by the FDA-approved drug benzbromarone may hold repurposing potential for treatment of asthma and pulmonary arterial hypertension or BK channelopathies.

A selective inhibitor of the sperm-specific potassium channel SLO3 impairs human sperm function.

To fertilize an oocyte, the membrane potential of both mouse and human sperm must hyperpolarize (become more negative inside). Determining the molecular mechanisms underlying this hyperpolarization is vital for developing new contraceptive methods and detecting causes of idiopathic male infertility. In mouse sperm, hyperpolarization is caused by activation of the sperm-specific potassium (K+) channel SLO3 [C. M. Santietal.,FEBS Lett. 584, 1041-1046 (2010)]. In human sperm, it has long been unclear whether hyperpolarization depends on SLO3 or the ubiquitous K+ channel SLO1 [N. Mannowetz, N. M. Naidoo, S. A. S. Choo, J. F. Smith, P. V. Lishko, Elife2, e01009 (2013), C. Brenkeret al.,Elife 3, e01438 (2014), andS. A. Mansell, S. J. Publicover, C. L. R. Barratt, S. M. Wilson,Mol. Hum. Reprod. 20, 392-408 (2014)]. In this work, we identified the first selective inhibitor for human SLO3-VU0546110-and showed that it completely blocked heterologous SLO3 currents and endogenous K+ currents in human sperm. This compound also prevented sperm from hyperpolarizing and undergoing hyperactivated motility and induced acrosome reaction, which are necessary to fertilize an egg. We conclude that SLO3 is the sole K+ channel responsible for hyperpolarization and significantly contributes to the fertilizing ability of human sperm. Moreover, SLO3 is a good candidate for contraceptive development, and mutation of this gene is a possible cause of idiopathic male infertility.

Plant growth-enhancing traits of rhizobacteria isolated from brinjal, okra, and leaf mustard

Exploring new plant-associated rhizobacteria and reintroducing them to the crop-soil environment is among the strategies to reverse the declining quality of the agricultural soil environment. A total of 340 isolates were recovered from the rhizospheres of okra (Abelmoschus esculentus), leaf mustard (Brassica juncea), and brinjal (Solanum melongena). From among the total, 155 isolates (45.59%) were diazotrophs, and 122 (35.88%) and 127 (37.35%) were isolates with the solubilising activity of phosphate and potassium, respectively. Thirteen of the most promising isolates were identified by gas chromatography for their cellular fatty acid methyl esters: Escherichia vulneris (TC19), Klebsiella pneumoniae (BA5, SA19, SB22), Pantoea ananatis (TC22), Pseudomonas aeruginosa (BA46), Pseudomonas putida (BA29, BA37, SC5, SC14), Salmonella bongori (BC17), Salmonella enterica (BB2), and Shigella dysenteriae (BA16). Three Pseudomonas strains viz. P. aeruginosa BA46 and P. putida BA37 and SC5 were selected after enhancing root elongation and vigour of lettuce seedlings. The American lettuce growth performance in the non-circulating hydroponic system was established. The inoculation with rhizobacteria strains, SC5 and BA46, stimulated shoot and root biomass over uninoculated control plants. The inoculation of lettuce plants with isolates BA37, BA46 and SC5, produced significantly longer roots compared to uninoculated control plants. This study indicates the potential use of the strains BA46 and SC5 as candidates for the formulation and production of hydroponic nutrient solution fortified with beneficial bacteria.

Prenatal exposure to alcohol impairs responses of cerebral arterioles to activation of potassium channels: Role of oxidative stress.

Potassium channels play an important role in the basal tone and dilation of cerebral resistance arterioles in response to many stimuli. However, the effect of prenatal alcohol exposure (PAE) on specific potassium channel function remains unknown. The first goal of this study was to determine the influence of PAE on the reactivity of cerebral arterioles to activation of ATP-sensitive potassium (KATP ) and BK channels. Our second goal was to determine whether oxidative stress contributed to potassium channel dysfunction of cerebral arterioles following PAE. We fed Sprague-Dawley dams a liquid diet with or without alcohol (3% EtOH) for the duration of their pregnancy (21 to 23 days). We examined in vivo responses of cerebral arterioles in control and PAE male and female offspring (14 to 16 weeks after birth) to activators of potassium channels (Iloprost [BK channels] and pinacidil [KATP channels]), before and following inhibition of oxidative stress with apocynin. We found that PAE impaired dilation of cerebral arterioles in response to activation of potassium channels with iloprost and pinacidil, and this impairment was similar in male and female rats. In addition, treatment with apocynin reversed the impaired vasodilation to iloprost and pinacidil in PAE rats to levels observed in control rats. This effect of apocynin also was similar in male and female rats. PAE induces dysfunction in the ability of specific potassium channels to dilate cerebral arterioles which appears to be mediated by an increase in oxidative stress. We suggest that these alterations in potassium channel function may contribute to the pathogenesis of cerebral vascular abnormalities and/or behavioral/cognitive deficits observed in fetal alcohol spectrum disorders.

Vasoplegic Syndrome after Cardiopulmonary Bypass in Cardiovascular Surgery: Pathophysiology and Management in Critical Care.

Vasoplegic syndrome (VS) is a common complication following cardiovascular surgery with cardiopulmonary bypass (CPB), and its incidence varies from 5 to 44%. It is defined as a distributive form of shock due to a significant drop in vascular resistance after CPB. Risk factors of VS include heart failure with low ejection fraction, renal failure, pre-operative use of angiotensin-converting enzyme inhibitors, prolonged aortic cross-clamp and left ventricular assist device surgery. The pathophysiology of VS after CPB is multi-factorial. Surgical trauma, exposure to the elements of the CPB circuit and ischemia-reperfusion promote a systemic inflammatory response with the release of cytokines (IL-1β, IL-6, IL-8, and TNF-α) with vasodilating properties, both direct and indirect through the expression of inducible nitric oxide (NO) synthase. The resulting increase in NO production fosters a decrease in vascular resistance and a reduced responsiveness to vasopressor agents. Further mechanisms of vasodilation include the lowering of plasma vasopressin, the desensitization of adrenergic receptors, and the activation of ATP-dependent potassium (KATP) channels. Patients developing VS experience more complications and have increased mortality. Management includes primarily fluid resuscitation and conventional vasopressors (catecholamines and vasopressin), while alternative vasopressors (angiotensin 2, methylene blue, hydroxocobalamin) and anti-inflammatory strategies (corticosteroids) may be used as a rescue therapy in deteriorating patients, albeit with insufficient evidence to provide any strong recommendation. In this review, we present an update of the pathophysiological mechanisms of vasoplegic syndrome complicating CPB and discuss available therapeutic options.

Comparative study for Pb2+ adsorption from simulated wastewater of battery manufacture on activated carbon prepared from rice husk with different activation agents

This study contains a lab-scale investigation into the feasibility of applying an adsorption technique to treat wastewater polluted with lead metal simulated to that exhaust from a battery manufactory. Rice husks have been prepared for use in three forms; natural rice husks without any activation, activated carbon of rice husks pretreated with Sulfuric acid H2SO4, and the other pretreated with Potassium hydroxide KOH. Activated carbon using KOH provided the best condition for the removal of lead than carbon activated using H2SO4 and natural rice husks. The BET surface area and surface morphology by FESEM analysis were characterized. The values of surface area were (20, 561, 722) m2/g for natural rice husk, activated carbon pretreated with sulfuric acid, and potassium hydroxide respectively. The adsorption process was studied using Pb2+ at temperatures of (25-40)o C and for a concentration range of (20-100) mg/l. The maximum removal ratios of lead Pb2+ for natural rice husks and sulfuric acid or hydroxide potassium activation after 1h were 51.21%, 92.3%, and 97.25%, respectively. The maximum adsorption capacity of lead Pb2+ onto natural rice husks, rice husks pretreated with H2SO4 or KOH, and into activated carbons was (37, 86.2 and 94.6) mg/g respectively, at a concentration of 100 ppm and at 25oC. The equilibrium adsorption curves were obtained for Pb2+ and the data was fairly well fitted with Freundlich-isotherm with a confidence level of 0.99. The kinetic of adsorption was studied by using two kinetic models, pseudo first order and pseudo second order. The results showed the rapid increase in the rate of adsorption at the initial until equilibrium achieved. Pseudo second order model was represented the data very well with confidence level 0.99.

Understanding effects of potassium activator on the porous structure and adsorption performance of bluecoke-based porous powder during microwave heating

Improving the porous structure is one of the primary challenges for carbon adsorption. This study investigated the effects of different potassium source activators and different impregnation ratio on the porous structure of BPP and adsorption performance on methylene blue dye. Bluecoke-based porous powder (BPP) was prepared by microwave-assisted activation with KOH, K2CO3 or KHCO3 using bluecoke powder as sustainable precursor. Results showed that the morphology of the activated bluecoke powder by KHCO3, K2CO3 and KOH gradually tended to skeletonize, and the specific surface area and pore volume were increased. KOH exhibited the best activation effect, followed by K2CO3 and KHCO3. The carbon thermal reaction of KOH plays a key role in the activation of bluecoke powder. When the impregnation ratio was 3:1, BPP-3 had a BET specific surface area of 1060 m2/g and a high pore volume of 0.484 cm3/g due to the formation of micropores and mesopores. The adsorption process of BPP-3 on methylene blue was in accordance with the Langmuir model (R2 = 0.999), and its maximum adsorption capacity for this dye was 404.858 mg/g. Kinetic and thermodynamic studies showed that the adsorption process of BPP-3 for methylene blue with low concentration mainly involved physical adsorption and could be regarded as a spontaneous heat absorption process. The results of conventional potassium-derived activators on the pore structure and adsorption of precursors gained from this study can be used to design adsorbents with rich pores and to predict their adsorption performance on target pollutants.

Assessment of the Naturally Occurring Radioactive Materials (Norm) In Jos North, Nigeria. A Case Study of the Utan Artisanal Tin Mining Sites

Tin mining and milling can be an avenue for economic and technological development. Mining of this mineral contributes significantly to the distortion of the natural distribution of radioisotopes in the environment. This study assesses the concentration of natural radioactivity due to radioactive elements such as 40K, 238U and 232Th. Soil samples were taken from 20 distinct locations within the Utan mining sites, Jos North, Plateau State, Nigeria. Potassium, radium, and thorium in soil samples from mining sites were determined by measuring their concentration activities using the gamma-ray spectroscopy method. Activity concentrations of potassium, radium and thorium were determined. In soil samples, activity concentrations of 40K, 226Ra and 232Th were established. 40K 196.07±4.91 to 608.07±1.44 with an average of 386.48, 226Ra 0.71±0.02 to 5.11±0.07 with an average of 2.35 and 232Th 14.91±0.74 to 63.71±0.97 with average activity concentrations of 54.78. The average concentration activity of potassium and thorium was slightly above the world recommended average of 370.00 and 40.00 respectively, while radium was below the recommended average. The mines mean absorbed and annual effective dose rates were 14.27-nGy h−1and 18.62 μSvy-1, respectively. This average calculated absorbed dose rate in the air was found to be much less, than the global average of 57-nGy h−1. The absorbed dose is considered low compared to the external natural radiation of about 2000 μSv.y-1, to which no harmful effect is expected directly. However, the mean measured dose rate and calculated dose parameters for the mine were higher than the regulatory limit for public exposure.

Potassium Status of Soils under Three Different Parent Materials of the Oil palm (Elaeis guineensis Jacq)

Potassium quantity/intensity relations were studied in soils of three different parent materials of the oil palm to determine their potassium status and management. This was done by equilibrating 2.5g of the soil samples in 25 ml of 0.01M CaCl 2 at room temperature containing known concentrations of K. Potassium saturation was computed over ECEC. The quantity factor (Q) was determined as the difference in concentration between added K and soil solution K after equilibrating. The Q factor was plotted against the intensity factor. Results showed that the soils were generally acidic while organic matter and total nitrogen decreased with increasing soil depths in all the locations. Potassium activity ratio, its activity, its activity coefficient, ionic strength, free energy of replacement and potassium saturation differed due to the influence of the three different parent materials. In soils under alluvium, ECEC was significantly correlated with potassium activity (r = 0.941*), potassium activity coefficient (r = 0.925*), PBC K (r = 0.953*). In soils under basement complex rocks, ECEC had a significant correlation with potassium activity (r = 0.975**) and calcium activity (r = 0.996**). In soils under shale mixed with sandstone and clay, potassium saturation had a significant correlation with calcium activity coefficient while exchangeable acidity had a significant correlation with potassium activity coefficient. There were high values of potassium activity ratio but low values of ionic strength, free energy of replacement and labile K in all the locations. Conclusion: It follows that adequate maintenance of the ECEC status of soils under alluvium and Basement Complex Rocks through deliberate maintenance of cover cropping and frequent K fertilization could suffice in maintaining the soils K and Ca potential in contrast with soils under Shale Mixed with Sandstone and Clay that requires the application of K fertilizers blended with a little bit of lime. Keywords: Potassium status, potassium activity ratio, ionic strength, potential buffering capacity and labile K. DOI: 10.7176/CMR/14-2-01 Publication date: May 31 st 2022