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1.
Food Chem ; 463(Pt 4): 141502, 2024 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-39368197

RESUMO

Liangpingyou, a well-known Chinese pomelo (Citrus grandis L.) variety, elicits a unique and uncharacterized numbing aftertaste. To understand the molecular bases and characteristics of the pomelo-induced numbing sensation, we first determined that hydroxyl sanshools, the major Sichuan pepper chemosensates, were not responsible via silylation-GC-MS analysis. Pomelo peel juice was then subjected to solid-phase extraction to form 4 fractions, and key sensory-active substances were screened via taste dilution analysis. Three simple coumarins, meranzin hydrate, isomeranzin, and marmin, were identified to induce numbing, which has not been previously reported. Sensory studies via extensively modified half-tongue tests and verification steps revealed recognition thresholds within 0.49-1.78, 0.32-1.56, and 0.43-1.46 µmol/L for numbness, pungency, and astringency, respectively. The temporal dominance trends showed the following taste notes: Meranzin hydrate-numbing dominated, isomeranzin-numbing and pungent, and marmin-astringent and numbing. Molecular docking analysis suggested that coumarins target the receptors TRPV1, TPRA1, and KCNK3.

2.
J Mol Model ; 30(11): 360, 2024 Oct 02.
Artigo em Inglês | MEDLINE | ID: mdl-39356315

RESUMO

CONTEXT: This research assesses the influence of polypropylene (PP) fibers, both homopolymer and hydroxylated (PPOH), on the tensile properties of calcium silicate hydrate (C-S-H) composites through molecular dynamics (MD) simulations. Our models explore C-S-H matrices integrated with PP and PPOH fibers at varying polymerization degrees. The results demonstrate that both PP and PPOH fibers significantly influence the tensile strength and Young's modulus of the composites. Notably, PPOH fibers contribute to more substantial mechanical enhancements than PP, attributed to the increased polarity and enhanced intermolecular interactions from the hydroxyl groups. The study reveals a nonlinear relationship between polymer additive content and mechanical performance, with optimal properties at a polymerization degree of 20. Additionally, stress-strain analysis indicates that PPOH composites exhibit superior ductility and fracture energy, particularly at polymerization degrees of 20, showing enhanced ultimate strain and fracture energy by up to 9.6% and 13.9%, respectively, compared to PP counterparts. These results highlight the crucial role of tailored polymer additive composition and chemical modifications in maximizing the mechanical efficacy of C-S-H-based materials, enhancing their durability and structural performance. METHODS: All MD simulations were conducted using LAMMPS. The models employed a combination of Clayff and Cvff force fields. During the entire tensile simulation, the system was configured under the NPT ensemble at 300 K.

3.
J Mol Graph Model ; 133: 108878, 2024 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-39369623

RESUMO

The energy and structure of Bjerrum defects in structure II gas hydrates were investigated by using first-principle calculations for finite-size clusters and periodic 3D lattice systems. The formation energies of these defects were calculated for the first time when the cages of the structure II structure were completely empty and the large cage was filled with a THF molecule. Analogous to findings in ice structures, one of the hydrogen atoms forming the D defect was noted to orient toward the cage. If the excess proton resides in the large cage, it acts as an attraction center for the polar guest molecule, i.e., THF. Therefore, the large cage guest THF molecule stabilizes the D/L defect pair and isolated D/L defect formation energies by forming hydrogen bonds with the D defect. In such cases, the defect structure representing a D/L defect pair containing a THF molecule interacting with one of the hydrogen atoms of the D defect mirrors the guest-induced ones. Notably, the classical Bjerrum defect and the guest-induced Bjerrum defect exhibit a similar phenomenon in defective structures. Contrary to existing literature, it is evident that guest-induced Bjerrum defects involve both the L and D components. The insights gained from this study could potentially offer an alternative perspective to understand various experimental observations, such as those related to dielectric and NMR properties.

4.
OTO Open ; 8(4): e70023, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-39351276

RESUMO

Objective: To compare sedation success rates between rectal (RCH) and oral chloral hydrate (OCH) administration in children undergoing auditory brainstem response (ABR) testing and assess the incidence of adverse effects. Study Design: Randomized controlled trial, performed between May 2023 and August 2023. Setting: Ear, Nose, and Throat Outpatient Department at tertiary care hospital. Methods: Pediatric patients aged 1 to 5 years, who were indicated for ABR testing were enrolled and randomly divided into 2 groups. The control group received 10% wt/vol chloral hydrate orally at a dose of 50 mg/kg, while the other group received the same dose through rectal administration. Onset of sedation, duration of sedation, recovery time, vital signs, and adverse effects were recorded and analyzed to assess sedative effectiveness and safety. Results: Eighty-eight children were randomly assigned to RCH or OCH administration groups, the sedation success rates of RCH and OCH groups were 84.09% and 90.91%, respectively (P = .33). Adverse effects were detected in 11 children (12.5%), with a vomiting rate of 20.45% in the oral group versus 0% in the rectal group (P = .002). The diarrhea rate was 4.55% in the rectal group versus 0% in the oral group (P = .16). In either group, no serious adverse effects were documented. Conclusion: RCH and OCH are both safe and effective for short-term sedation in pediatric patients during ABR testing. Interestingly, RCH administration offers a high success rate without vomiting or major adverse effects. This study established the effectiveness of RCH for sedation in children under specialized supervision.

5.
Molecules ; 29(17)2024 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-39275100

RESUMO

The objective of this research was to investigate natural products for their potential against pathogenic microorganisms. Sabinene hydrate (SH), a monoterpenoid, is synthesised by numerous different plants as a secondary metabolite. At present, there is a lack of definite investigations regarding the antimicrobial activity of SH itself and its different isomers. The antimicrobial effects of commercially available SH (composed mainly of trans-isomer) were evaluated within a range of concentrations in three types of contact tests: solid and vapor diffusion and the macro-broth dilution method. Moreover, the effects of SH on the rate of linear growth and spore germination were also examined. Ethanolic SH solutions were tested against an array of microorganisms, including blue-stain fungi (Ceratocystis polonica, Ophiostoma bicolor, O. penicillatum), frequently originating from bark beetle galleries; three fungal strains (Musicillium theobromae, Plectosphaerella cucumerina, and Trichoderma sp.) isolated from a sapwood underneath bark beetle galleries (Ips typographus) on spruce (Picea abies) stems; Verticillium fungicola, isolated from diseased I. typographus larvae; two Gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus), two Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa); five yeasts (Candida albicans, C. krusei, C. parapsilosis, Saccharomyces cerevisiae, and Rhodotorula muscilaginosa), and two saprophytic fungi (Aspergillus niger and Penicillium notatum). In solid agar disc diffusion tests, Gram-positive bacteria exhibited greater susceptibility to SH than Gram-negative bacteria, followed by yeasts and fungi. The most resistant to SH in both the disc diffusion and broth macro-dilution methods were P. aeruginosa, A. niger, and Trichoderma sp. strains. Blue-stain fungi and fungi isolated from the Picea sapwood were the most resistant among the fungal strains tested. The minimum inhibition concentrations (MICs) generated by SH and determined using a disc volatilization method were dependent on the fungal species and played an important role in the development of microorganism inhibition. The two Gram-positive bacteria, B. subtilis and S. aureus (whose MICs were 0.0312 and 0.0625 mg/mL, respectively), were the organisms most susceptible to SH, followed by the Gram-negative bacterium, E. coli (MIC = 0.125 mg/mL) and two yeasts, C. albicans and C. kruei (MIC was 0.125 mg/mL and 0.25 mg/mL, respectively). C. parapsilosis (MIC = 0.75 mg/mL) was the yeast most resistant to SH. The investigation of antimicrobial properties of plant secondary metabolites is important for the development of a new generation of fungicides.


Assuntos
Anti-Infecciosos , Testes de Sensibilidade Microbiana , Anti-Infecciosos/farmacologia , Anti-Infecciosos/química , Fungos/efeitos dos fármacos , Monoterpenos/farmacologia , Monoterpenos/química , Bactérias/efeitos dos fármacos , Bactérias/crescimento & desenvolvimento
6.
Sci Rep ; 14(1): 22678, 2024 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-39349717

RESUMO

Natural gas hydrate is a promising unconventional natural gas source due to its high energy density and huge global reserves. During exploitation, the drilling fluid may invade the hydrate formation and induce hydrate decomposition, causing reservoir damage. Herein, a novel reservoir protectant made by bio-degradable temporary plugging material (BDTPM) was developed in the form of polymer-ceramic composite microcapsules. As an additive to the drilling fluid, the BDTPM can minimize drilling fluid intrusion by plugging the reservoir during drilling and afterwards maximize permeability recovery by degrading the material. The particle size distribution was in the range of 1-130 µm. The optimal mass ratio between modified ceramic particles, ethyl cellulose and epoxy resin was found to be 4:2:1. The plugging rate was 100% when ethyl cellulose and epoxy resin were mixed to coat the ceramic particles to form BDTPM, and the plugging performance was the best. At a temperature close to the typical hydrate reservoir environment (5 °C), 0.02 wt% low-temperature complex enzyme can degrade BDTPM, and the permeability recovery rate is 64.66%. The efficient reservoir protectant developed in this work could play an important role in the successful drilling of natural gas hydrate reservoirs.

7.
Sci Total Environ ; 954: 176464, 2024 Sep 22.
Artigo em Inglês | MEDLINE | ID: mdl-39317260

RESUMO

Gas replacement method enables the simultaneous exploitation of natural gas and the realization of carbon capture, utilization, and storage (CCUS). Safe exploitation of hydrate-bearing sediments (HBS) has garnered significant attention, particularly concerning the engineering geological risks involved. Understanding deformation characteristics during shear after the replacement of HBS is crucial for safe and efficient exploitation. This study employs microfocus computer tomography and digital volume correlation (DVC) to investigate the deformation characteristics of HBS samples with varying replacement percentages. Key findings include: 1. An increase in failure strength of HBS is observed with higher replacement percentages due to improved hydrate cementation and consolidation under confining pressure. 2. DVC analysis shows that narrower radial displacement ranges are associated with increased pore compression, while wider ranges indicate greater particle repositioning. Frequent large axial displacements suggest significant pore compaction, whereas smaller axial displacements indicate particle movement and pore-filling phenomena. 3. The gas replacement process enhances the cementation structure of HBS without altering hydrate saturation, resulting in thinner shear bands and accelerated strain softening with higher replacement percentages. 4. The DVC approach effectively captures volumetric strain and deformation behaviors, offering valuable insights into sediment responses under shear. This study provides a theoretical reference for geological safety evaluation during gas replacement exploitation.

8.
Ren Fail ; 46(2): 2395449, 2024 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-39229929

RESUMO

Although it has been established that patients with chronic kidney disease and iron deficiency, as indicated by a transferrin saturation of < 20%, are at increased risk of all-cause mortality and cardiovascular events, the optimal management of such patients has not yet been determined. In this post hoc subgroup analysis, we aimed to clarify the effect of ferric citrate hydrate on transferrin saturation in patients with chronic kidney disease and low transferrin saturation (< 20%) undergoing hemodialysis. To accomplish this, we extracted the relevant data on a subset of patients drawn from two previous studies: the ASTRIO study (A Study examining the contribution to Renal anemia treatment with ferric citrate hydrate, Iron-based Oral phosphate binder, UMIN000019176) and a post-marketing surveillance study. The subset of patients used for the present study were those with baseline transferrin saturation < 20%. We found that administration of ferric citrate hydrate increased transferrin saturation and maintained transferrin saturation at approximately 30%. However, because we did not have access to data on all-cause mortality or cardiovascular events, we could not ascertain whether the frequency of these outcomes was reduced in parallel with improvements in transferrin saturation. Further large studies are required.


Assuntos
Compostos Férricos , Diálise Renal , Transferrina , Humanos , Masculino , Feminino , Compostos Férricos/uso terapêutico , Compostos Férricos/administração & dosagem , Transferrina/metabolismo , Transferrina/análise , Idoso , Pessoa de Meia-Idade , Insuficiência Renal Crônica/terapia , Insuficiência Renal Crônica/complicações , Insuficiência Renal Crônica/sangue , Anemia Ferropriva/tratamento farmacológico , Anemia Ferropriva/sangue
9.
J Environ Manage ; 370: 122560, 2024 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-39299108

RESUMO

The selective recovery of phosphate from wastewater can manage nutrients and realize the recycling of phosphorus resources. In this study, a novel konjac glucomannan/pectin/calcium silicate composite hydrogel (KP-CSH) was developed for efficient recovery of phosphate in aqueous solution. The amount of alkali released after the reaction of KP-CSH in a neutral solution was small (the pH of the solution after the reaction was < 9). In a wide initial pH range (3-10), the adsorption capacity of KP-CSH in 50 mg-P/L phosphate solution reached 39∼45 mg-P/g. Besides, even if the pH of the solution after the reaction was less than 8, it could still well adsorb phosphate. The kinetic and isothermal adsorption experiments indicated that the adsorption process of phosphate by KP-CSH was chemical adsorption, and the maximum adsorption capacity was 61.2 mg-P/g. KP-CSH preferentially adsorbed phosphate even in the presence of high concentrations of competitive ions. In the actual biogas slurry, KP-CSH also exhibited the strongest selectivity/affinity for phosphate, and its distribution coefficient (Kd) was significantly higher than that of other co-existing anions and cations. The adsorption mechanism analysis indicated that Ca was the main adsorption site of KP-CSH, and that the adsorption process of target pollutants mainly involved ligand exchange and the intra-sphere complexation. Further plant seed germination and seedling growth experiments suggested that KP-CSH after phosphate recovery did not exert a negative effect on the growth of plant seedlings, and increased the chlorophyll content of seedling leaves. These results demonstrate that KP-CSH is a potential adsorbent for efficient phosphate recovery, which can be used as a slow-release phosphate fertilizer after recovering phosphate.

10.
J Mol Graph Model ; 133: 108868, 2024 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-39293199

RESUMO

Hydrate-based CO2 storage is a cost-effective and environmentally friendly approach to reduce carbon emission, and the addition of hydrate promoters has shown a promising avenue for enhancing CO2 hydrate formation. In this work, the promotion mechanism and promotion performance of five different hydrate promoters (denoted as DIOX, CP, THF, THP, and CH) were investigated and compared by first-principles calculations and molecular dynamics simulations. The results show that the hydrate promoters prefer to singly occupy 51264 cages of the sII hydrate, and CO2 molecules can singly occupy 512 cage or multiply occupy 51264 cages. The cohesive energy density indicates that the optimum CO2 storage capacity can reach up to ∼28 wt%. The stabilization effects of hydrate promoters on the hydrate stability should follow the order of CP > CH > DIOX > THF ≈ THP. The hydrate promoters can increase the water-water interactions, and the molecular diffusivity shows that the dynamic stability of the hydrates is THP ≈ CH > CP > DIOX > THF. Further, the hydrate promoters can accelerate the hydrate formation kinetics, which reduce the induction time and increase the nucleation and growth process.

11.
Urolithiasis ; 52(1): 127, 2024 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-39237821

RESUMO

Calcium oxalate (CaOx) urolithiasis is a prevalent urinary disorder with significant clinical impact. This study investigates the therapeutic potential of Morin Hydrate (MH), a natural bioflavonoid, in preventing CaOx stone formation. Molecular docking studies revealed that MH binds strongly to glycolate oxidase (GO), suggesting its inhibitory effect on oxalate synthesis. In vitro assays demonstrated that MH effectively inhibits CaOx crystal nucleation, aggregation, and growth, altering crystal morphology to less stable forms. Diuretic activity studies in Wistar rats showed that MH substantially increased urine volume and ion excretion, indicating its moderate diuretic effect. In vivo experiments further supported these findings, with MH treatment improving urinary and serum markers, reducing oxidative stress, and protecting renal tissue, as evidenced by histopathological analysis. Notably, MH administration significantly decreased GO and lactate dehydrogenase activities in urolithiatic rats, indicating a reduction in oxalate production. These results suggest that MH is a promising candidate for the prevention and treatment of CaOx urolithiasis, with the potential for clinical application in reducing the risk and recurrence of kidney stones.


Assuntos
Oxalato de Cálcio , Flavonoides , Ratos Wistar , Animais , Flavonoides/farmacologia , Flavonoides/uso terapêutico , Oxalato de Cálcio/metabolismo , Oxalato de Cálcio/química , Ratos , Masculino , Simulação de Acoplamento Molecular , Cristalização , Urolitíase/prevenção & controle , Urolitíase/tratamento farmacológico , Estresse Oxidativo/efeitos dos fármacos , Modelos Animais de Doenças , Flavonas
12.
J Pharm Sci ; 113(10): 3065-3077, 2024 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-39122184

RESUMO

A variable or non-stoichiometric hydrate of GDC-4379 was developed into a formulated capsule with a 1% drug loading. The water content of this hydrate varied from 0-0.7 moles over the relative humidity (RH) range of 0-98% (25°C). Since a variable state of hydration coupled with rapid equilibration of lattice water with the environmental RH can lead to challenges in formulation development, an analytical method to directly and accurately determine the state of hydration of the active in such a low dose formulation was deemed necessary. Owing to its high selectivity and fast acquisition times, 19F solid-state NMR was effectively utilized to directly determine the lattice water content of the active in the formulated capsule. By correlating Δδ, the chemical shift difference between the isotropic peaks, with the relative humidity and ultimately the lattice water content, the state of hydration of GDC-4379 in the formulated capsule was experimentally determined as 0.63 moles of water/mole of anhydrate.


Assuntos
Umidade , Espectroscopia de Ressonância Magnética , Água , Espectroscopia de Ressonância Magnética/métodos , Água/química , Cápsulas/química , Química Farmacêutica/métodos , Composição de Medicamentos/métodos , Flúor/química
13.
Environ Sci Pollut Res Int ; 31(39): 51582-51592, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-39115736

RESUMO

In situ CO2 mixing technology is a potential technology for permanently sequestering CO2 during concrete manufacturing processes. Although it has been approved as a promising carbon capture and utilisation (CCU) method, its effect on the leachability of heavy metals from cementitious compounds has not yet been studied. This study focuses on the effect of in situ CO2 mixing of cement paste on the leaching of hexavalent chromium (Cr(VI)). The tank leaching test of the CO2 mixing cement specimen resulted in a Cr(VI) cumulative leaching of 0.614 mg/m2 in 28 d, which is ten times lower than that of the control mixing specimens. The results in thermogravimetric analysis indicated that a relatively significant amount of CrO42- is immobilised as CaCrO4 during the CO2-mixing, and a higher Cr-O extension is observed in the Fourier transform infrared spectra. Furthermore, a portion of the monocarboaluminate is inferred from microstructural analyses to incorporate CrO42- ions. These results demonstrate that in situ CO2 mixing is beneficial not only in reducing CO2 emissions, but also in controlling the leaching of toxic substances.


Assuntos
Dióxido de Carbono , Cromo , Materiais de Construção , Cromo/química , Dióxido de Carbono/química
14.
Mol Pharm ; 21(10): 5150-5158, 2024 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-39137015

RESUMO

Our previous work (Mol Pharm, 20 (2023) 3427) showed that crystalline excipients, specifically anhydrous dibasic calcium phosphate (DCPA), facilitated the dehydration of carbamazepine dihydrate (CBZDH) and the formation of an amorphous product phase during the mixing stage of continuous tablet manufacturing. Understanding the mechanism of this excipient-induced effect was the object of this study. Blending with DCPA for 15 min caused pronounced lattice disorder in CBZDH. This was evident from the 190% increase in the apparent lattice strain determined by the Williamson-Hall plot. The rapid dehydration was attributed to the increased reactivity of CBZDH caused by this lattice disorder. Lattice disorder in CBZDH was induced by a second method, cryomilling it with DCPA. The dehydration was accelerated in the milled sample. Annealing the cryomilled sample reversed the effect, thus confirming the effect of lattice disorder on the dehydration kinetics. The hardness of DCPA appeared to be responsible for the disordering effect. DCPA exhibited a similar effect in other hydrates, thereby revealing that the effect was not unique to CBZDH. However, its magnitude varied on a case-by-case basis. The high shear powder mixing was necessary for rapid and efficient powder mixing during continuous drug product manufacturing. The mechanical stress imposed on the CBZDH, and exacerbated by DCPA, caused this unexpected destabilization.


Assuntos
Fosfatos de Cálcio , Carbamazepina , Cristalização , Excipientes , Comprimidos , Excipientes/química , Carbamazepina/química , Fosfatos de Cálcio/química , Comprimidos/química , Composição de Medicamentos/métodos , Química Farmacêutica/métodos , Pós/química , Difração de Raios X
15.
Molecules ; 29(15)2024 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-39125008

RESUMO

The thermodynamic effect of octyl-ß-D-glucopyranoside (OGP) on the formation of methane-1,3-dimethylcyclohexane (DMCH) hydrate was studied in this work. The thermodynamic equilibrium hydrate formation pressures between 275.15 K and 283.15 K were measured by the isothermal pressure search method. Different OGP aqueous solutions (0, 0.1, and 1 wt%) were used in this work. The experimental results show that OGP had no obvious thermodynamic inhibition on methane-DMCH hydrate formation when its concentration was low (0.1 wt%), whereas it had an inhibition on methane-DMCH hydrate formation when its concentration was high (1 wt%). The phase equilibrium hydrate formation pressure of the methane-DMCH-OGP system is about 0.1 MPa higher than that of the methane-DMCH system. The dissociation enthalpies of methane hydrate in different solutions remained uniform, which indicates that OGP was not involved in methane-DMCH hydrate formation. This phenomenon is explained from the perspective of the molecular structure of OGP. As a renewable and biological nonionic surfactant, the concentration of OGP in the liquid phase is low, so OGP can be added to the methane-DMCH system without significant thermodynamic inhibition.

16.
Molecules ; 29(15)2024 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-39125118

RESUMO

The aim of this study was to determine the influence of four inorganic salts, KCl, NaCl, KBr and NaBr, on the thermodynamic conditions of methane hydrate formation. In order to achieve this, the vapor-liquid water-hydrate (VLWH) equilibrium conditions of methane (CH4) hydrate were measured in the temperature range of 274.15 K-282.15 K by the isothermal pressure search method. The results demonstrated that, in comparison with deionized water, the four inorganic salts exhibited a significant thermodynamic inhibition on CH4 hydrate. Furthermore, the inhibitory effect of Na+ on methane hydrate is more pronounced than that of K+, where there is no discernible difference between Cl- and Br-. The dissociation enthalpy (∆Hdiss) of CH4 hydrate in the four inorganic salt solutions is comparable to that of deionized water, indicating that the inorganic salt does not participate in the formation of hydrate crystals. The Chen-Guo hydrate model and N-NRTL-NRF activity model were employed to forecast the equilibrium conditions of CH4 hydrate in electrolyte solution. The absolute relative deviation (AARD) between the predicted and experimental values were 1.24%, 1.08%, 1.18% and 1.21%, respectively. The model demonstrated satisfactory universality and accuracy. This study presents a novel approach to elucidating the mechanism and model prediction of inorganic salt inhibition of hydrate.

17.
Front Chem ; 12: 1444448, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-39119519

RESUMO

In this work, the terahertz time-domain spectroscopy method analyzed solutions of bovine serum albumin (BSA) in two high concentrations (50 and 334 mg/mL) at three pH values (2.5, 6.5, 8.5) and the same solvents without protein, at 25°C. The spectra of dry BSA were also recorded. For the first time, a method for determining the complex dielectric permittivity of protein molecules in aqueous solutions, without the dielectric contribution of the aqueous phase, is proposed. It is shown that the dielectric permittivity of dissolved and dry BSA (lyophilized, in the native conformation) differ significantly in the terahertz frequency range. These differences are small near 70 cm-1, but they increase greatly with decreasing frequency. It was found that the dielectric losses of protein molecules in solution are close to the dielectric losses of the aqueous environment, which in this frequency range are determined by intermolecular relaxation processes of water. Since dielectric losses are directly related to molecular dynamics, this fact shows that the intramolecular dynamics of the protein completely adjusts to the intermolecular dynamics of the aqueous environment. It also indicates that the native conformation does not determine all the fundamental characteristics of a protein molecule, in particular, it does not determine the dynamics of the protein, which significantly depends on the water environment.

18.
ACS Nano ; 18(34): 23655-23671, 2024 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-39141799

RESUMO

Low flexural strength and toughness have posed enduring challenges to cementitious materials. As the main hydration product of cement, calcium silicate hydrate (C-S-H) plays important roles in the mechanical performance of cementitious materials while exhibiting random microstructures with pores and defects, which hinder mechanical enhancement. Inspired by the "brick-and-mortar" microstructure of natural nacre, this paper presents a method combining freeze casting, freeze-drying, in situ polymerization, and hot pressing to fabricate C-S-H nacre with high flexural strength, high toughness, and lightweight. Poly(acrylamide-co-acrylic acid) was used to disperse C-S-H and toughen C-S-H building blocks, which function as "bricks", while poly(methyl methacrylate) was impregnated as "mortar". The flexural strength, toughness, and density of C-S-H nacre reached 124 MPa, 5173 kJ/m3, and 0.98 g/cm3, respectively. The flexural strength and toughness of the C-S-H nacre are 18 and 1230 times higher than those of cement paste, respectively, with a 60% reduction in density, outperforming existing cementitious materials and natural nacre. This research establishes the relationship between material composition, fabrication process, microstructure, and mechanical performance, facilitating the design of high-performance C-S-H-based and cement-based composites for scalable engineering applications.

19.
Nano Lett ; 24(32): 9816-9823, 2024 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-39094116

RESUMO

Component modulation endows Mn-based electrodes with prominent energy storage properties due to their adjustable crystal structure characteristics. Herein, ZnMn2(PO4)2·nH2O (ZMP·nH2O) was obtained by a hydration reaction from ZnMn2(PO4)2 (ZMP) during an electrode-aging evolution. Benefiting from the introduction of lattice H2O molecules into the ZMP structure, the ion transmission path has been expanded along with the extended d-spacing, which will further facilitate the ZMP → ZMP·nH2O phase evolution and electrochemical reaction kinetics. Meanwhile, the hydrogen bond can be generated between H2O and O in PO43-, which strengthens the structure stability of ZMP·nH2O and lowers the conversion barrier from ZMP to ZMP·4H2O during the Zn2+ uptake/removal process. Thereof, ZMP·nH2O delivers enhanced electrochemical reaction kinetics with robust structure tolerance (106.52 mA h g-1 at 100 mA g-1 over 620 cycles). This high-energy aqueous Zn||ZMP·nH2O battery provides a facile strategy for engineering and exploration of high-performance ZIBs to realize the practical application of Mn-based cathodes.

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