Abstract
Understanding the interplay between the inherent disorder and the correlated fluctuating-spin ground state is a key element in the search for quantum spin liquids. H
3
LiIr
2
O
6
is ...considered to be a spin liquid that is proximate to the Kitaev-limit quantum spin liquid. Its ground state shows no magnetic order or spin freezing as expected for the spin liquid state. However, hydrogen zero-point motion and stacking faults are known to be present. The resulting bond disorder has been invoked to explain the existence of unexpected low-energy spin excitations, although data interpretation remains challenging. Here, we use resonant X-ray spectroscopies to map the collective excitations in H
3
LiIr
2
O
6
and characterize its magnetic state. In the low-temperature correlated state, we reveal a broad bandwidth of magnetic excitations. The central energy and the high-energy tail of the continuum are consistent with expectations for dominant ferromagnetic Kitaev interactions between dynamically fluctuating spins. Furthermore, the absence of a momentum dependence to these excitations are consistent with disorder-induced broken translational invariance. Our low-energy data and the energy and width of the crystal field excitations support an interpretation of H
3
LiIr
2
O
6
as a disordered topological spin liquid in close proximity to bond-disordered versions of the Kitaev quantum spin liquid.
Tetracyclines are an amazing class of chemical agents with multiple therapeutic potential. Structural modification of the original natural tetracyclines led to the synthesis and development of ...doxycycline and minocycline, compounds with higher lipophilicity, better oral pharmacokinetics and higher potency. Due to diverse pharmacological properties, these drugs are now under extensive investigation for use in the treatment of various disparate diseases. In recent years, several studies have conclusively reported anti-inflammatory, immune-modulating and neuroprotective effects of these compounds. There are currently over 200 ongoing clinical trials on tetracyclines. These studies extend over a wide range of diseases including dermatological diseases, behavior and mental disorders, immune system disorders, cardiovascular diseases, and cancer. In this review we will discuss the chemistry and pharmacology of these agents, and describe how their inhibitory effect on matrix metalloproteinase and on pro-inflammatory cytokines has kindled renewed interest in them. Based on the reports from pre-clinical and clinical trials, the therapeutic potential and application of tetracyclines may well be redefined and extensively extended.
This study is devoted to a class of linear and nonlinear differential equations with fractional-order governing diffusion, Burger’s, Airy’s, KdV, gas dynamic and Fisher’s equations. These equations ...are used to describe the physical processes of models possessing memory. By employing classical and nonclassical Lie symmetry analysis and some technical calculations, new infinitesimal generators are obtained which give rise to derive the invariant solutions for this class of equations.
Terminal heat stress is one of the major constraints of cereal production. A two-year field investigation was performed to assess the response of Hordeum vulgare ssp. spontaneum genotypes to terminal ...heat stress using gas-exchange parameters, photosystem efficiency, proline accumulation, cell membrane leakage, and grain yield traits. Results of analysis of variance revealed the significant effects of heat stress (E), genotype (G), and G × E on the studied traits. The results of linear regression analysis showed that yield loss was inversely correlated with the maximum quantum yield of PSII photochemistry (Fv/Fm) and chlorophyll content. Path-coefficient analysis revealed that high Chl contents were either directly related to the grain yield or indirectly through the higher net photosynthetic rate and higher Fv/Fm values under high temperatures at the reproductive growth stage. Overall, the adapted wild genotypes exhibited physiological mechanisms capable of sustainable maintaining their yield capacity and plasticity flow, which could be exploited by crossing with cultivated barley to introgress heat tolerance.
In this study, we propose a method based on the direct and inverse fuzzy transforms (
F
-transforms) to approximate solutions of the system of linear differential–algebraic equations. We obtain an ...analytical solution to the initial value problem in terms of basic functions using this method. Since the basic functions have compact support, by employing fuzzy transform to the problem, we obtain the system of linear algebraic equations with lower Hessenberg coefficient matrix. We discuss the solvability of this system and give the error analysis using the consistency of the initial value. We present several examples to illustrate the efficiency and the performance of this new method.
Recently, many of the studies have illustrated that the new pandemic SARS-CoV-2 can affect Central Nervous System through the olfactory bulb. In addition to investigating anosmia or hyposmia induced ...by this virus, a quantitative analysis was needed to clarify the taste and smell disorder of the new coronavirus. The four basic taste quality with five concentrations for sweet, sour, bitter, and salty were administered to 75 subjects divided into three groups: COVID-19 patients with taste disorder, COVID-19 patients without taste disorder, and control group.
The results indicated the increment of sweet (2.68 ± 0.14), sour (3.34 ± 0.12) and bitter (3.39 ± 0.2) thresholds in COVID-19 patients with taste disorder in comparison with patients without taste disorder that the threshold were: 2 ± 0.16, 2.11 ± 0.2 and 2.55 ± 0.5 for sweet, sour, and bitter respectively. On the other hand, the patients inversely showed a significant decrease in the salty taste threshold (0.51 ± 0.03) compared to COVID-19 positive control groups (1.11 ± 0.11).
Additionally, despite taste disorder in almost all of the patients with smell deficiency, only 30% of cases with taste disorder reported smell deficiency. It may be concluded that some of the taste disorders in patients with COVID-19 disorder could be associated with taste receptors dysfunction or the spread of infection to the cranial nerves responsible for the conduction of tastes sensation.
The impact of graphene reinforcement on the mechanical properties of metals has been a subject of intense investigation over the last decade in surface applications to mitigate the impact of ...tribological loadings or for strengthening purposes when dispersed into a bulk material. Here, the effect on the plastic indentation response of a single graphene layer grown on copper is analyzed for two configurations: one with graphene at the surface, the other with graphene sandwiched under a 100 nm thick copper cap layer. Nanoindentation under both displacement and load control conditions show both earlier and shorter pop-in excursions compared to systems without graphene. Atomic force microscopy reveals much smoother pile-ups with no slip traces in the presence of a surface graphene layer. The configuration with the intercalated graphene layer appears as an ideal elementary system to address bulk hardening mechanisms by indentation testing. Transmission electron microscopy (TEM) cross-sections below indents show more diffuse and homogeneous dislocation activity in the presence of graphene. 3D dislocation dynamics simulations allow unraveling of the origin of these 3D complex phenomena and prove that the collective dislocation mechanisms are dominantly controlled by the strong back stress caused by the graphene barrier. These results provide a quantitative understanding of the impact of graphene on dislocation mechanisms for both surface and bulk applications, but with an impact that is not as large as anticipated from other studies or general literature claims.
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•Compare indentation of Cu films with or without graphene, with or without extra Cu cap layer.•Presence of graphene leads to smaller pop-ins and smoother pile ups.•TEM reveals more homogenous dislocation activity with graphene.•Discrete dislocation dynamics simulations show large back stress with graphene.•Effect of graphene on hardness is weak.
In the present work, the dependence of photovoltaic parameters of laboratory-scale dye sensitized solar cells (DSSCs) on photoanode active area (
A
) and also the effect of using current collector on ...this dependency were investigated. Current collectors were applied, in the form of silver strips, on the edges of electrodes. Electrochemical impedance spectroscopy (EIS) and current-voltage (
I
-
V
) curve measurement were employed as characterizing methods. The role of current collector was to decrease the resistance against current collection from the surface of electrodes and thus to decrease series resistance of DSSCs. It was observed that all photovoltaic parameters, i.e., short circuit current density (
J
sc
), open circuit voltage (
V
oc
), fill factor (
FF
), and power conversion efficiency (
η
), decrease with increasing
A
. Applying current collector had no influence on photovoltaic parameters of smallest DSSC, but it improved the performance of larger DSSCs. Also, applying current collector caused the photovoltaic parameters of DSSCs to be less dependent on
A
. It was shown that
A
dependence of photovoltaic parameters was due to the effect of
A
on area-specific series resistance (
r
s
) of DSSC. Also, the effect of current collector on
A
dependency of photovoltaic parameters was due to its effect on
A
dependency of
r
s
.
Lymphocytic infiltration of the lacrimal gland and ocular surface in autoimmune diseases such as Sjögren's syndrome (SS) causes an aqueous-deficient dry eye that is associated with significant ...morbidity. Previous studies from our laboratory and others have established autoimmune regulator (Aire)–deficient mice as a useful model to examine exocrinopathy and ocular surface disease associated with SS. Consistent with human SS, autoreactive CD4+ T cells play an indispensible role in the development of exocrine and ocular surface disease in Aire knockout mice. We report that in addition to CD4+ T cells, a large number of macrophages infiltrate the corneal stroma, limbus, and lacrimal glands of diseased mice. Adoptive transfer of autoreactive CD4+ T cells from Aire knockout mice led to local infiltration of macrophages and ocular surface damage in immunodeficient recipients. Depletion of local macrophages, through subconjunctival injection of clodronate liposome, attenuated lissamine green staining and improved ocular phenotype. Alternatively, systemic depletion of macrophages had no effect on ocular phenotype but led to significant improvements in lacrimal gland exocrinopathy and tear secretion. Our results suggested that autoreactive CD4+ T cells provoked macrophage infiltration to the eye and lacrimal gland, where they played a functional role in directing the development of autoimmune dry eye.
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