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The Murun massif (Aldan shield, Russia) is particularly intriguing due to its group of alkali Ca-(K)-(Na) silicates, which includes many new and rare species. Additionally, it is also of interest for its beryllium mineralization. One of the unique beryllium Ca-(K)-(Na) silicates, odintsovite K2Na4Ca3Ti2Be4Si12O38, was investigated in this study. The aim of this study is to provide new insights into the crystal chemistry and spectroscopic properties of odintsovite. DFT modelling was used to interpret the experimental IR and Raman spectra. Determining the crystal-chemical formula of odintsovite is challenging due to the presence of atoms in different structural positions with varying valence states. The distribution of cations was determined by combining electron probe microanalysis with the results of crystal structure refinement. Luminescence of Eu3+ was observed in odintsovite upon excitation at around 532 nm. Analysis of the luminescence band splitting is related to the 4f–4f transitions in Eu3+ ions. Additionally, upon excitation at around 370 nm, luminescence with a peak at around 410 nm, associated with 5d–4f transitions in Ce3+ ions, was observed. [ABSTRACT FROM AUTHOR]

The synthesis of (p)ppGpp alarmones plays a vital role in the regulation of metabolism suppression, growth rate control, virulence, bacterial persistence, and biofilm formation. The (p)ppGpp alarmones are synthesized by proteins of the RelA/SpoT homolog (RSH) superfamily, including long bifunctional RSH proteins and small alarmone synthetases. Here, we investigated enzyme kinetics and dose-dependent enzyme inhibition to elucidate the mechanism of 4-(4,7-dimethyl-1,2,3,4-tetrahydronaphthalen-1-yl)pentanoic acid (DMNP) action on the (p)ppGpp synthetases RelMsm and RelZ from Mycolicibacterium smegmatis and RelMtb from Mycobacterium tuberculosis. DMNP was found to inhibit the activity of RelMtb. According to the enzyme kinetics analysis, DMNP acts as a noncompetitive inhibitor of RelMsm and RelZ. Based on the results of molecular docking, the DMNP-binding site is located in the proximity of the synthetase domain active site. This study might help in the development of alarmone synthetase inhibitors, which includes relacin and its derivatives, as well as DMNP – a synthetic analog of the marine coral metabolite erogorgiaene. Unlike conventional antibiotics, alarmone synthetase inhibitors target metabolic pathways linked to the bacterial stringent response. Although these pathways are not essential for bacteria, they regulate the development of adaptation mechanisms. Combining conventional antibiotics that target actively growing cells with compounds that impede bacterial adaptation may address challenges associated with antimicrobial resistance and bacterial persistence. [ABSTRACT FROM AUTHOR]

Highlights: The influence of specimen size and testing system on Skempton's B values is discussed. The use of stiff measuring systems and precise transducers provides accurate enough B values. The use of large specimens is rarely possible and can be disadvantageous. [ABSTRACT FROM AUTHOR]

Our analysis of the X-ray crystal structure of canthaxanthin (CAN) showed that its ketolated β-ionone rings can adopt two energetically equal, but structurally distinct puckers. Quantum chemistry calculations revealed that the potential energy surface of the β-ionone ring rotation over the plane of the conjugated π-system in carotenoids depends on the pucker state of the β-ring. Considering different pucker states and β-ionone ring rotation, we found six separate local minima on the potential energy surface defining the geometry of the keto-β-ionone ring—two cis and one trans orientation for each of two pucker states. We observed a small difference in energy and no difference in relative orientation for the cis-minima, but a pronounced difference for the position of trans-minimum in alternative pucker configurations. An energetic advantage of β-ionone ring rotation from a specific pucker type can reach up to 8 kJ/mol ( 669 cm - 1 ). In addition, we performed the simulation of linear absorption of CAN in hexane and in a unit cell of the CAN crystal. The electronic energies of S 0 → S 2 transition were estimated both for the CAN monomer and in the CAN crystal. The difference between them reached 690 cm - 1 , which roughly corresponds to the energy gap between A and B pucker states predicted by theoretical estimations. Finally, we have discussed the importance of such effects for biological systems whose local environment determines conformational mobility, and optical/functional characteristics of carotenoid. [ABSTRACT FROM AUTHOR]

Geologic carbon storage (GCS) has recently been drawing attention as an effective and sustainable method to reduce CO2 emissions to the atmosphere. The injection of CO2 is mainly conducted into brine-saturated reservoir formations, and assessment of the multiphase flow properties becomes essential to evaluate the injectivity and storage capacity for carbon storage. Characterization of the CO2/water flow system requires comprehensive knowledge of host rock's relative permeability, capillary pressure, and wettability that are related to each other. Moreover, chemical reactions between the mineral grains and acidic mixture of CO2 and water may significantly affect the flow properties. In this study, a comprehensive experimental approach to characterize the chemical effect on the multiphase flow of CO2 in water-saturated reservoir rock is presented. One silica-rich formation—Berea sandstone, and two calcite-rich formations—Apulian and Indiana limestones, are selected to represent the reservoir materials. Robust experimental techniques for measurements of the relative permeability and degree of saturation based on the changes in poroelastic response are introduced. The relative permeability curves are determined, as it is shown that the curvatures and maximum degree of CO2 saturation change after CO2 treatment, especially for the limestones. In addition, the apparent contact angle increases and surface roughness decreases due to the chemical effect of CO2 injection on limestones. Finally, the advantages and limitations of the presented measurements are discussed and reported flow properties are compared to those predicted from the pore-scale analyses. [ABSTRACT FROM AUTHOR]

CO2 injection for geologic carbon storage is commonly conducted into sedimentary reservoir rock and influences the stress state and pore pressure resulting in coupled hydro-mechanical processes. Consideration of the presence of aqueous fluids in reservoir formations is crucial for describing their mechanical response, both short- and long-term. As CO2 is injected into the reservoir, the chemical reaction of the acidic mixture of CO2 and water with rock minerals may alter the poromechanical and hydraulic responses that need to be appropriately characterized. We conduct laboratory experiments aimed at accurate measurements of the stress-dependent poroviscoelastic rock properties to describe short- and long-term deformations. The chemical effects of CO2 treatment on the poroviscoelastic and hydraulic properties are explored by duplicating each experiment before and after CO2 treatment, while Berea sandstone, Apulian limestone, and Indiana limestone are selected as representative reservoir materials. CO2 treatment increases the bulk compressibility of the sandstone and limestones by 15–20%. The undrained response is characterized through measurements of Skempton's B coefficient, which decreases for Berea sandstone, but increases for the limestones. For calcite-rich rock, the porosity and solid compressibility increase by 4–6% and 20%, respectively, while these parameters remain unchanged for silica-rich rock. As the time-dependent behavior is measured indirectly by monitoring the pore pressure buildup under an undrained condition, the CO2 treatment appears to significantly facilitate the viscous response by 50–60% for all materials. Additionally, CO2 injection causes an increase in permeability but does not change the porosity–permeability exponents for the tested rock. Porosimetry and microimaging analyses reveal that for the limestones the main effect is caused by the dissolution of calcite, but for the sandstone the main explanation for the observed results is stress corrosion cracking. This study outlines CO2 injection influence on the poroviscoelastic response of reservoir rock and emphasizes the importance of properly characterizing the time-dependent behavior for geologic storage projects. Highlights: CO2 injection affects short- and long-term hydro-mechanical response of reservoir rock. The adopted poroviscoelastic constitutive model combines Maxwell viscoelasticity with Biot's poroelasticity. Experimental methods are introduced to characterize the hydraulic and poroviscoelastic behavior of reservoir rock. CO2 treatment significantly alters the long-term behavior of reservoir rock, while the short-term response was less affected. The permeability and porosity–permeability relationship for reservoir rock are affected by the CO2 treatment. [ABSTRACT FROM AUTHOR]

Despite the progress made in the treatment of nephrolithiasis, the existing methods of renal calculi destruction are not ideal and have both advantages and disadvantages. Considering the process of high-frequency glow discharge formation on the surface of an electrode and in an electrolyte solution, we obtained the results on the destruction of renal calculi in vitro. It was shown that the destruction of kidney stones by glow discharge plasma was caused by several processes—the plasma induced effect of hydrated electrons and shock wave effect of the electrolyte stimulated by electrical breakdowns in the plasma. The plasma generation modes were configured by estimating the thickness of the vapor–gas layer in which the plasma burns. Thus, the average rate of contact destruction of renal calculi was measured depending on the plasma generator input power and time of plasma exposure. We conclude that the method of stone fragmentation by high-frequency electrolyte plasma is rather perspective and can be used in endoscopic urology for percutaneous and transurethral lithotripsy. [ABSTRACT FROM AUTHOR]

The lifetime of electric propulsion (EP) thrusters depends particularly on the erosion characteristics of operation relevant components, for instance, the grid hole erosion of gridded ion thrusters or the channel wall erosion of Hall effect thrusters. Here two tools for in situ erosion measurements are presented, a triangular laser head for surface profiling and a telemicroscope for high-resolution optical imaging. Both can give access to radial and axial erosion parameters. The measurements can be done in situ without the need for breaking the vacuum and dismounting the thruster, which reduces thruster testing time considerably. In situ measurements can also help to ensure reproducibility of thruster performance conditions and can improve statistics of thruster characterization. The present work describes the fundamentals of both techniques in detail, selected experimental setups are presented, their performance is characterized and critically evaluated. The capabilities and limitations related to erosion measurements of EP thrusters are, exemplary, demonstrated for a gridded ion thruster RIT-22 and a Hall effect thruster SPT-100D. [ABSTRACT FROM AUTHOR]

Right ventricle (RV) dysfunction is an independent predictor of patient survival in heart failure (HF). However, the mechanisms of RV progression towards failing are not well understood. We studied cellular mechanisms of RV remodelling in a rat model of left ventricle myocardial infarction (MI)-caused HF. RV myocytes from HF rats show significant cellular hypertrophy accompanied with a disruption of transverse-axial tubular network and surface flattening. Functionally these cells exhibit higher contractility with lower Ca2+ transients. The structural changes in HF RV myocytes correlate with more frequent spontaneous Ca2+ release activity than in control RV myocytes. This is accompanied by hyperactivated L-type Ca2+ channels (LTCCs) located specifically in the T-tubules of HF RV myocytes. The increased open probability of tubular LTCCs and Ca2+ sparks activation is linked to protein kinase A-mediated channel phosphorylation that occurs locally in T-tubules. Thus, our approach revealed that alterations in RV myocytes in heart failure are specifically localized in microdomains. Our findings may indicate the development of compensatory, though potentially arrhythmogenic, RV remodelling in the setting of LV failure. These data will foster better understanding of mechanisms of heart failure and it could promote an optimized treatment of patients. [ABSTRACT FROM AUTHOR]

Cyanobacterial photosystem I (PSI) constitutes monomeric and trimeric pigment–protein complexes whose optical properties are marked by the presence of long-wavelength absorption bands. In spite of numerous experimental studies, the nature of these bands is still under debate and requires intensive theoretical analysis. Collecting together the data of linear spectroscopy and single-molecule spectroscopy (SMS) of PSI from Arthrospira platensis, we performed quantum modeling of the optical response based on molecular exciton theory (ET) and the multimode Brownian oscillator model (MBOM). Applying MBOM, the spectra of the red antenna state were calculated considering a particular for each red state adjustment of the low-frequency vibronic modes. Within the framework of our PSI exciton model it was shown that the coupling energy between antenna chlorophylls cannot be a factor of the red states formation, thus the long-wavelength bands are calculated without attribution to so-called antenna red chlorophylls. By the fitting of Huang–Rhys factors and frequencies for the lowest vibronic modes, we were able to reproduce the effects of strong and weak electron–phonon coupling experimentally observed in SMS spectra of red antenna states. Based on our theoretical calculations and also analysis of existing crystal structures of cyanobacterial PSI, we assumed that long-wavelength Chls can be localized in the peripheral protein subunits containing one or two pigment molecules. [ABSTRACT FROM AUTHOR]

Proper characterization of the mechanical and flow properties of participating rock formations is crucial for subsurface geo-energy projects, including hydrocarbon extraction, geologic carbon storage, and enhanced geothermal systems. Application of mechanical and hydraulic pressures changes the porosity of rock and modifies flow paths. For low-permeable or "tight" rock that mainly contains nanoscale pores and serves as the confining layer for underground storage operations, a significant change in permeability may occur due to a small change in porosity. The pore volume changes in nanoporous geomaterials are extremely difficult to measure directly, but can be assessed from the knowledge of the hydro-mechanical response. Experimental methods to measure the stress-dependent permeability and poroelastic parameters of fluid-saturated tight rock are introduced. Eau Claire shale, Opalinus clay (claystone), and Charcoal granite are selected as representative materials for tight rock and their pore structure and material properties are carefully investigated. The porosity–permeability relationship for tight rock is established by adopting a power-law dependence with the exponent value in the range of 15–17, thus being significantly larger than that for a porous reservoir rock. Consequently, even small perturbations of porosity can cause orders of magnitude changes in permeability possessing a risk on the sealing capacity of the tight formations. [ABSTRACT FROM AUTHOR]

The funding statement in the first sentence of the Acknowledgements section in the original publication is incorrect. The corrected Acknowledgements section is printed below. [ABSTRACT FROM AUTHOR]

We analyze measurements of bottom currents and thermohaline properties of water north of the Vema Channel with the goal to find pathway continuations of Antarctic Bottom Water flow from the Vema Channel into the Brazil Basin. The analysis is based on CTD/LADCP casts north of the Vema Channel. The flow in the deep Vema Channel consists of two branches. The deepest current flows along the bottom in the center of the channel and the other branch flows above the western wall of the channel. We found two smaller channels of the northern continuation of the deeper bottom flow. These flows become weak and almost disappear at a latitude of 25° 30′ S. The upper current flows at a depth of 4100–4200 m along the continental slope. We traced this current up to 24° S over a distance exceeding 250 km. This branch transports bottom water that eventually fills the deep basins of the North Atlantic. [ABSTRACT FROM AUTHOR]