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1.
Phys Chem Chem Phys ; 23(40): 22854-22873, 2021 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-34505589

RESUMO

Deep eutectic solvents (DESs) have become ubiquitous in a variety of industrial and pharmaceutical applications since their discovery. However, the fundamental understanding of their physicochemical properties and their emergence from the microscopic features is still being explored fervently. Particularly, the knowledge of transport mechanisms in DESs is essential to tune their properties, which shall aid in expanding the territory of their applications. This perspective presents the current state of understanding of the bulk/macroscopic transport properties and microscopic relaxation processes in DESs. The dependence of these properties on the components and composition of the DES is explored, highlighting the role of hydrogen bonding (H-bonding) interactions. Modulation of these interactions by water and other additives, and their subsequent effect on the transport mechanisms, is also discussed. Various models (e.g. hole theory, free volume theory, etc.) have been proposed to explain the macroscopic transport phenomena from a microscopic origin. But the formation of H-bond networks and clusters in the DES reveals the insufficiency of these models, and establishes an antecedent for dynamic heterogeneity. Even significantly above the glass transition, the microscopic relaxation processes in DESs are rife with temporal and spatial heterogeneity, which causes a substantial decoupling between the viscosity and microscopic diffusion processes. However, we propose that a thorough understanding of the structural relaxation associated to the H-bond dynamics in DESs will provide the necessary framework to interpret the emergence of bulk transport properties from their microscopic counterparts.

2.
Clin Exp Dermatol ; 2021 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-34236705

RESUMO

Tattoos with blue/black ink show good lightening of pigment after treatment with 1064 nm Q-switched (QS) neodymium-doped yttrium-aluminium-garnet (Nd:YAG) laser. In this randomized trial, we compared the efficacy of a novel three pass, one session procedure (R15 method) with a conventional method for treating blue/black tattoos in darker skin types. Tattoos were treated with 1064 nm QS Nd:YAG Laser with a spot size of 4 mm, fluence of 5 J/cm2 and frequency of 5 Hz. The tattoo pigment lightening was comparable with both methods. Thread-like tattoos had significantly better pigment lightening with fewer side effects than the broad band-like tattoos. We would like to recommend the R15 method of the QS Nd:YAG laser for thread-like tattoos, which can save patients' time, cut short the frequency of their hospital visits and, more importantly, decrease the cost involved in it.

3.
J Chem Phys ; 155(2): 024505, 2021 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-34266283

RESUMO

Deep eutectic solvents (DESs) have become a prevalent and promising medium in various industrial applications. The addition of water to DESs has attracted a lot of attention as a scheme to modulate their functionalities and improve their physicochemical properties. In this work, we study the effects of water on an acetamide based DES by probing its microscopic structure and dynamics using classical molecular dynamics simulation. It is observed that, at low water content, acetamide still remains the dominant solvate in the first solvation shell of lithium ions, however, beyond 10 wt. %, it is replaced by water. The increase in the water content in the solvent accelerates the H-bond dynamics by drastically decreasing the lifetimes of acetamide-lithium H-bond complexes. Additionally, water-lithium H-bond complexes are also found to form, with systematically longer lifetimes in comparison to acetamide-lithium complexes. Consequently, the diffusivity and ionic conductivity of all the species in the DES are found to increase substantially. Non-Gaussianity parameters for translational motions of acetamide and water in the DES show a conspicuous decrease with addition of water in the system. The signature of jump-like reorientation of acetamide is observed in the DES by quantifying the deviation from rotational Brownian motion. However, a notable decrease in the deviation is observed with an increase in the water content in the DES. This study demonstrates the intricate connection between H-bond dynamics and various microscopic dynamical parameters in the DES, by investigating the modulation of the former with addition of water.

5.
Rep Prog Phys ; 84(6)2021 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-33740783

RESUMO

Fluids exhibit remarkable variation in their structural and dynamic properties when they are confined at the nanoscopic scale. Various factors, including geometric restriction, the size and shape of the guest molecules, the topology of the host, and guest-host interactions, are responsible for the alterations in these properties. Due to their porous structures, aluminosilicates provide a suitable host system for studying the diffusion of sorbates in confinement. Zeolites and clays are two classes of the aluminosilicate family, comprising very ordered porous or layered structures. Zeolitic materials are important due to their high catalytic activity and molecular sieving properties. Guest molecules adsorbed by zeolites display many interesting features including unidimensional diffusion, non-isotropic rotation, preferred orientation and levitation effects, depending on the guest and host characteristics. These are useful for the separation of hydrocarbons which commonly exist as mixtures in nature. Similarly, clay materials have found application in catalysis, desalination, enhanced oil recovery, and isolation barriers used in radioactive waste disposal. It has been shown that the bonding interactions, level of hydration, interlayer spacing, and number of charge-balancing cations are the important factors that determine the nature of diffusion of water molecules in clays. Here, we present a review of the current status of the diffusion mechanisms of various adsorbed species in different microporous zeolites and clays, as investigated using quasielastic neutron scattering and classical molecular dynamics simulation techniques. It is impossible to write an exhaustive review of the subject matter, as it has been explored over several decades and involves many research topics. However, an effort is made to cover the relevant issues specific to the dynamics of different molecules in microporous zeolites and clay materials and to highlight a variety of interesting features that are important for both practical applications and fundamental aspects.

6.
J Colloid Interface Sci ; 590: 94-102, 2021 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-33524724

RESUMO

Bicontinuous microemulsions (BµEs) are a promising biomembrane mimetic system for investigating the behavior of antimicrobial peptides (AMPs) and their delivery to open wounds to combat antibiotic-resistant microorganisms. The properties of the BµE host are in turn affected by the guest AMP and can deviate from those of the unperturbed BµEs, especially at higher AMP concentrations. Here we report the effect of an archetypal AMP, melittin, over a wide range of concentrations, on the nanoscopic dynamics of BµEs formed by water/sodium dodecyl sulfate (SDS)/1-pentanol/dodecane, investigated using quasi-elastic neutron scattering (QENS). Two distinct motions are observed, namely, (i) the lateral motion of the surfactant on the surface of the oil channels and (ii) the internal motion of the surfactants. It is found that melittin restricts both the lateral and the internal motion, thereby acting as a stiffening agent. The lateral motion is more strongly affected, at low concentration of melittin. The lateral diffusion coefficient decreased sharply, approaching a constant value at higher melittin concentration. These results are in sharp contrast with the recent dynamic light scattering and neutron spin echo results which showed that at the length and time scales longer than those probed in the current work, melittin enhanced the long-range collective and local undulation motions of BµEs. Considered together, our results indicate that incorporation of melittin modulates the dynamics differently depending on the spatial and temporal regimes, in which the dynamics are being probed. The addition of melittin at low concentrations increased the magnitude of the zeta potential, but further increase of the melittin concentration decreased it. This suggests that addition of melittin at low concentrations led to increase in the surfactant concentration, but did not affect the negative charge per surfactant molecule, while further addition of melittin led to ion pairing of melittin with the oppositely charged surfactant. This study therefore demonstrates how the addition of melittin hinders the lateral motion of surfactants as a result of the strong association between melittin and SDS, suggesting that the release of AMPs from BµE-based delivery vehicles may be hindered.


Assuntos
Meliteno , Tensoativos , Emulsões , Dodecilsulfato de Sódio , Água
7.
QJM ; 114(5): 333-334, 2021 Aug 29.
Artigo em Inglês | MEDLINE | ID: mdl-32770245
8.
J Eur Acad Dermatol Venereol ; 35(2): 536-545, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32991767

RESUMO

BACKGROUND: The integration of machine learning algorithms in decision support tools for physicians is gaining popularity. These tools can tackle the disparities in healthcare access as the technology can be implemented on smartphones. We present the first, large-scale study on patients with skin of colour, in which the feasibility of a novel mobile health application (mHealth app) was investigated in actual clinical workflows. OBJECTIVE: To develop a mHealth app to diagnose 40 common skin diseases and test it in clinical settings. METHODS: A convolutional neural network-based algorithm was trained with clinical images of 40 skin diseases. A smartphone app was generated and validated on 5014 patients, attending rural and urban outpatient dermatology departments in India. The results of this mHealth app were compared against the dermatologists' diagnoses. RESULTS: The machine-learning model, in an in silico validation study, demonstrated an overall top-1 accuracy of 76.93 ± 0.88% and mean area-under-curve of 0.95 ± 0.02 on a set of clinical images. In the clinical study, on patients with skin of colour, the app achieved an overall top-1 accuracy of 75.07% (95% CI = 73.75-76.36), top-3 accuracy of 89.62% (95% CI = 88.67-90.52) and mean area-under-curve of 0.90 ± 0.07. CONCLUSION: This study underscores the utility of artificial intelligence-driven smartphone applications as a point-of-care, clinical decision support tool for dermatological diagnosis for a wide spectrum of skin diseases in patients of the skin of colour.


Assuntos
Aplicativos Móveis , Neoplasias Cutâneas , Inteligência Artificial , Humanos , Índia , Aprendizado de Máquina
10.
QJM ; 114(4): 275, 2021 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-32597977
11.
J Phys Chem Lett ; 11(22): 9669-9679, 2020 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-33135903

RESUMO

It is known that the organic units in hybrid halide perovskites are free to rotate, but it is not clear if this freedom is of any relevance to the structure-property relationship of these compounds. We have employed quasi-elastic neutron scattering using two different spectrometers, thus providing a wide dynamic range to investigate the cation dynamics in methylammonium lead bromide (MAPbBr3) and formamidinium lead bromide (FAPbBr3) over a large temperature range covering all known crystallographic phases of these two compounds. Our results establish a plastic crystal-like phase forming above 30 K within the orthorhombic phase of MAPbBr3 related to 3-fold rotations of MA units around the C-N axis with an activation energy, Ea, of ∼27 meV, which has no counterpart in the FA compound. MA exhibits an additional 4-fold orientational motion of the whole molecule via rotation of the C-N axis itself with an Ea of ∼68 meV common for the high-temperature tetragonal and cubic phases. In contrast, the FA compound exhibits only an isotropic orientational motion of the whole FA unit with Ea ≈ 106 meV within the orthorhombic phase and a substantially reduced common Ea of ∼62 meV for the high-temperature tetragonal and cubic phases. Our results suggest that the rotational dynamics of the organic units, crystallographic phases, and physical properties of these compounds are intimately connected.

12.
Struct Dyn ; 7(5): 051301, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32984433

RESUMO

Cationic lipid membranes have recently attracted huge attention both from a fundamental point of view and due to their practical applications in drug delivery and gene therapy. The dynamical behavior of the lipids in the membrane is a key parameter controlling various physiological processes and drug release kinetics. Here, we review the dynamical and thermotropic phase behavior of an archetypal cationic lipid membrane, dioctadecyldimethylammonium bromide (DODAB), as studied using neutron scattering and molecular dynamics simulation techniques. DODAB membranes exhibit interesting phase behavior, specifically showing coagel, gel, and fluid phases in addition to a large hysteresis when comparing heating and cooling cycles. The dynamics of the lipid membrane is strongly dependent on the physical state of the bilayer. Lateral diffusion of the lipids is faster, by an order of magnitude, in the fluid phase than in the ordered phase. It is not only the characteristic times but also the nature of the segmental motions that differ between the ordered and fluid phases. The effect of different membrane active molecules including drugs, stimulants, gemini surfactants, and unsaturated lipids, on the dynamical and thermotropic phase behavior of the DODAB membrane, is also discussed here. Various interesting features such as induced synchronous ordering between polar head groups and tails, sub diffusive behavior, etc., are observed. The results shed light on the interaction between these additives and the membrane, which is found to be a complex interplay between the physical state of the membrane, charge, concentration, molecular architecture of the additives, and their location within the membrane.

13.
J Chem Phys ; 153(10): 104505, 2020 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-32933283

RESUMO

Lithium based deep eutectic solvents (DESs) are excellent candidates as eco-friendly electrolytes for lithium ion batteries. While some of these DESs have shown promising results, a clear mechanism of lithium ion transport in DESs is not yet established. This work reports the study on the solvation and transport of lithium in a DES made from lithium perchlorate and acetamide using Molecular Dynamics (MD) simulation and inelastic neutron scattering. Based on hydrogen bonding (H-bonding) of acetamide with neighboring molecules/ions, two states are largely prevalent: (1) acetamide molecules that are H-bonded to lithium ions (∼36%) and (2) acetamide molecules that are entirely free (∼58%). Analyzing their stochastic dynamics independently, it is observed that the long-range diffusion of the former is significantly slower than that of the latter. This is also validated from the neutron scattering experiment on the same DES system. Furthermore, the analysis of the lithium dynamics shows that the diffusion of acetamide molecules in the first category is strongly coupled to that of lithium ions. On an average, the lithium ions are H-bonded to ∼3.2 acetamide molecules in their first solvation. These observations are further bolstered through the analysis of the H-bond correlation function between acetamide and lithium ions, which shows that ∼90% of lithium ionic transport is achieved by vehicular motion where the ions diffuse along with their first solvation shell. It is also observed that the ionic motions are largely uncorrelated and the conductivity of lithium ions in the DES is found to be 11 mS/cm. The findings of this work are an important advancement in understanding solvation and transport of lithium in the DES.

15.
Eur J Neurol ; 27(12): 2453-2462, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-32697894

RESUMO

BACKGROUND AND PURPOSE: Blood pressure (BP) variability has been associated with worse neurological outcomes in acute ischaemic stroke (AIS) patients receiving treatment with intravenous thrombolysis (IVT). However, no study to date has investigated whether pulse pressure (PP) variability may be a superior indicator of the total cardiovascular risk, as measured by clinical outcomes. METHODS: Pulse pressure variability was calculated from 24-h PP measurements following tissue plasminogen activator bolus in AIS patients enrolled in the Combined Lysis of Thrombus using Ultrasound and Systemic Tissue Plasminogen Activator for Emergent Revascularization (CLOTBUST-ER) trial. The outcomes of interest were the pre-specified efficacy and safety end-points of CLOTBUST-ER. All associations were adjusted for potential confounders in multivariable regression models. RESULTS: Data from 674 participants was analyzed. PP variability was identified as the BP parameter with the most parsimonious fit in multivariable models of all outcomes, and was independently associated (P < 0.001) with lower likelihood of both 24-h neurological improvement and 90-day independent functional outcome. PP variability was also independently related to increased odds of any intracranial bleeding (P = 0.011) and 90-day mortality (P < 0.001). Every 5-mmHg increase in the 24-h PP variability was independently associated with a 36% decrease in the likelihood of 90-day independent functional outcome (adjusted odds ratio 0.64, 95% confidence interval 0.52-0.80) and a 60% increase in the odds of 90-day mortality (adjusted odds ratio 1.60, 95% confidence interval 1.23-2.07). PP variability was not associated with symptomatic intracranial bleeding at either 24 or 36 h after IVT administration. CONCLUSIONS: Increased PP variability appears to be independently associated with adverse short-term and long-term functional outcomes of AIS patients treated with IVT.


Assuntos
Isquemia Encefálica , AVC Isquêmico , Acidente Vascular Cerebral , Administração Intravenosa , Pressão Sanguínea , Isquemia Encefálica/complicações , Isquemia Encefálica/tratamento farmacológico , Fibrinolíticos/uso terapêutico , Humanos , Acidente Vascular Cerebral/tratamento farmacológico , Terapia Trombolítica , Ativador de Plasminogênio Tecidual/uso terapêutico , Resultado do Tratamento
16.
J Food Sci Technol ; 57(6): 2251-2258, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32431351

RESUMO

Blueberry fruits are known for their high vitamin C, essential dietary fibre, antioxidant activity and anthocyanin pigments. Different blueberry varieties have been introduced in India but no attempt has been made for their nutritional profiling. Nutritional profiling of varieties helps us to know the unique varietal characters, which serves as a guideline for recommendation of a valuable variety for fresh consumption and/or processing. Therefore, the present study was conducted in eight different blueberry varieties such as 'Misty', 'Sharp Blue', 'Biloxi', 'Jewel', 'Gulf Coast', 'Blue Crop', 'Star', 'Legacy'. The results of the study revealed that all tested varieties differed significantly in physical attributes (10-berry weight, fruit firmness, roundness index, moisture content) and biochemical and functional attributes (ascorbic acid, total anthocyanin, total phenolic content, antioxidant activity, total sugars, organic acids) and mineral content. Regression analysis and Principal Component Analysis showed that antioxidant potential of blueberries was mainly contributed by phenolics followed by anthocyanins and ascorbic acid content. However for taste perception, fructose among sugars and succinic acid among sugars were the most influencing factors (p ≤ 0.05). Total phenolics and anthocyanins content were responsible for overall difference in functional attributes among the varieties. The attributes such as high fruit firmness, sensorial score, and appropriate shape and weight make 'Misty', the best variety for marketability and fresh consumption among all tested varieties.

17.
Eur J Neurol ; 27(6): 1039-1047, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32149450

RESUMO

BACKGROUND AND PURPOSE: We investigated the effectiveness of intravenous thrombolysis (IVT) in acute ischaemic stroke (AIS) patients with large vessel or distal occlusions and mild neurological deficits, defined as National Institutes of Health Stroke Scale scores < 6 points. METHODS: The primary efficacy outcome was 3-month functional independence (FI) [modified Rankin Scale (mRS) scores 0-2] that was compared between patients with and without IVT treatment. Other efficacy outcomes of interest included 3-month favorable functional outcome (mRS scores 0-1) and mRS score distribution at discharge and at 3 months. The safety outcomes comprised all-cause 3-month mortality, symptomatic intracranial hemorrhage (ICH), asymptomatic ICH and severe systemic bleeding. RESULTS: We evaluated 336 AIS patients with large vessel or distal occlusions and mild stroke severity (mean age 63 ± 15 years, 45% women). Patients treated with IVT (n = 162) had higher FI (85.6% vs. 74.8%, P = 0.027) with lower mRS scores at hospital discharge (P = 0.034) compared with the remaining patients. No differences were detected in any of the safety outcomes including symptomatic ICH, asymptomatic ICH, severe systemic bleeding and 3-month mortality. IVT was associated with higher likelihood of 3-month FI [odds ratio (OR), 2.19; 95% confidence intervals (CI), 1.09-4.42], 3-month favorable functional outcome (OR, 1.99; 95% CI, 1.10-3.57), functional improvement at discharge [common OR (per 1-point decrease in mRS score), 2.94; 95% CI, 1.67-5.26)] and at 3 months (common OR, 1.72; 95% CI, 1.06-2.86) on multivariable logistic regression models adjusting for potential confounders, including mechanical thrombectomy. CONCLUSIONS: Intravenous thrombolysis is independently associated with higher odds of improved discharge and 3-month functional outcomes in AIS patients with large vessel or distal occlusions and mild stroke severity. IVT appears not to increase the risk of systemic or symptomatic intracranial bleeding.


Assuntos
Isquemia Encefálica , Acidente Vascular Cerebral , Administração Intravenosa , Idoso , Isquemia Encefálica/tratamento farmacológico , Feminino , Fibrinolíticos/uso terapêutico , Humanos , Hemorragias Intracranianas , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Acidente Vascular Cerebral/tratamento farmacológico , Trombectomia , Terapia Trombolítica , Resultado do Tratamento
18.
J Phys Chem B ; 124(8): 1509-1520, 2020 02 27.
Artigo em Inglês | MEDLINE | ID: mdl-32017563

RESUMO

Over the last couple of decades, deep eutectic solvents (DESs) have emerged as novel alternatives to ionic liquids that are extensively used in the synthesis of innovative materials, metal processing, catalysis, etc. However, their usage is limited, primarily because of their large viscosity and poor conductivity. Therefore, an understanding of the molecular origin of these transport properties is essential to improve their industrial applicability. Here, we present the report of the nanoscopic diffusion mechanism of acetamide in a DES synthesized with lithium perchlorate as studied using neutron scattering and molecular dynamics (MD) simulation techniques. A diffusion model is constructed with the help of MD simulation data comprising two distinct processes, corresponding to long-range jump diffusion and localized diffusion within a restricted volume. This diffusion model is validated through the analysis of neutron scattering data in the acetamide based DES (ADES) and molten acetamide. Although ADES has a remarkably lower freezing point compared to pure acetamide, the molecular mobility is found to be enormously restricted in the former. Particularly, the long-range jump diffusion process of acetamide is slower by a factor of 3 in ADES in comparison with molten acetamide. Further, the geometry of localized diffusion is found to be unaltered, but the dynamics is observed to be slightly slower in ADES. The diffusion model is found to be consistent over a wide temperature range for the ADES. Both long-range and localized diffusion show Arrhenius dependence with temperature in ADES. MD simulation analysis reveals that the long-range diffusion in ADES is restricted mainly due to the formation of hydrogen bond mediated complexes between the ionic species of the salt and acetamide molecules. Hence, the origin of higher viscosity observed in ADES can be attributed to the complexation in the ADES. The complex formation also explains the inhibition of the crystallization process while cooling and thereby results in depression of the freezing point of ADES.

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