The inhibition of p38 MAPK blocked inflammation to restore the functions of rat meibomian gland epithelial cells.

Meibomian glands (MGs) are vital for ocular surface health. However, the roles of inflammation in the progression of meibomian gland dysfunction (MGD) are largely unknown. In this study, the roles of the inflammation factor interleukin-1ß (IL-1ß) via the p38 mitogen-activated protein kinases (MAPK) signaling pathway on rat meibomian gland epithelial cells (RMGECs) were explored. Eyelids from adult rat mice at 2 months and 2 years of age were stained with specific antibodies against IL-1ß to identify inflammation levels. RMGECs were exposed to IL-1ß and/or SB203580, a specific inhibitor of p38 MAPK signaling pathway, for 3 days. Cell proliferation, keratinization, lipid accumulation, and matrix metalloproteinases 9 (MMP9) expression were evaluated by MTT assay, polymerase chain reaction (PCR), immunofluorescence staining, apoptosis assay, lipid staining, and Western blot analyses. We found that IL-1ß was significantly higher in the terminal ducts of MGs in rats with age-related MGD than in young rats. IL-1ß inhibited cell proliferation, suppressed lipid accumulation and peroxisome proliferator activator receptor γ (PPARγ) expression, and promoted apoptosis while activating the p38 MAPK signaling pathway. Cytokeratin 1 (CK1), a marker for complete keratinization, and MMP9 in RMGECs were also up-regulated by IL-1ß. SB203580 effectively diminished the effects of IL-1ß on differentiation, keratinization, and MMP9 expression by blocking IL-1ß-induced p38 MAPK activation, although it also inhibited cell proliferation. The inhibition of the p38 MAPK signaling pathway blocked IL-1ß-induced differentiation reduction, hyperkeratinization, and MMP9 overexpression of RMGECs, which provides a potential therapy for MGD.

First Report of Damping-off on Sedum plumbizincicola Caused by Rhizoctonia solani AG 2-1 in China.

Sedum plumbizincicola X.H. Guo et S.B. Zhou sp. nov. is a plant species of the family Crassulaceae that has the ability to hyperaccumulate cadmium and zinc in high concentrations (Liu et al. 2017). In April of 2018 and 2019, a disease of damping-off was observed on S. plumbizincicola seedlings in a nursery in Changsha (28°13'N; 112°56'E), the Hunan Province of China, in which nearly 1 million seedlings were planted. Approximately 40% of the surveyed plants were infected. The affected plants displayed water-soaking on the shoots and stems, and chlorosis on the leaves. As the disease spread upward, leaf stalks or the whole plants became wilted and collapsed. Five diseased stem and leaf samples were collected. Symptomatic tissues were excised and surface sterilized with 70% ethanol for 10 s, and 0.1% HgCl2 for 2 min, washed with sterile distilled water for three times, and then cultured on potato dextrose agar (PDA) at 26°C in darkness. Fungal colonies were similar in morphology: white, light gray to brown, with hyphae branched at nearly right angles, septa near the branching point and constrictions at the base of hyphal branches. After 10 days, white-gray to brown sclerotia were produced. The morphological characteristics were consistent with those of Rhizoctonia solani J.G. Kühn (Sneh et al. 1991). Genomic DNA of a representative isolate was extracted using the cetyltrimethylammonium bromide method. The internal transcribed spacer (ITS) region of rDNA was amplified and sequenced with the primer pairs ITS4/ITS5 (White et al. 1990). When analyzed by the BLASTn program, the ITS sequence (GenBank Accession No. MN961664) had 100% identity to the corresponding gene sequence of R. solani anastomosis group (AG) 2-1(Accession Nos: LC202869.1 and MH862641.1). In addition, primers Rhsp1/ITS4B and Rhsp2/ITS1F specific for R. solani, and AG21sp/ITS4B specific for R. solani AG 2-1 were also used (Salazar et al. 2000). Results revealed that our isolate was R. solani AG 2-1. Pathogenicity was confirmed via in vivo inoculation of one-month-old S. plumbizincicola seedlings in sterilized nursery soil with four representative isolates. For each pot, five 5-mm-diameter mycelial plugs from 7-days old colonies on PDA were placed in the soil near the base of the stems. Plants inoculated with agar plugs without mycelium served as controls. The inoculated plants were kept in a growth chamber at 25°C with a 12/12 h light/dark cycle. Pathogenicity tests were performed twice, with three replicative potted plants for each isolate in each test. Approximately 25 days after inoculation, the damping-off symptoms resembling those observed in the field were displayed on the inoculated plants, while no obvious symptoms were observed on the control plants. R. solani was re-isolated from all infected plants and molecularly characterized, thus confirming Koch's postulates. R. solani has been previously reported as the pathogen of damping-off disease in many plants, such as canola (Paulitz et al. 2006) and oat (Zhang et al. 2016). However, to the best of our knowledge, this is the first report of R. solani causing damping-off of S. plumbizincicola in China. S. plumbizincicola is widely planted for heavy metal pollution treatment in China. The occurrence of this disease could seriously affect the production of the seedlings, and management strategies should be developed.

Adsorption of PTCDA and C60 on KBr(001): electrostatic interaction versus electronic hybridization.

The adsorption of functional molecules on insulator surfaces is of great interest to molecular and organic electronics. Here, we present a systematic investigation of the geometric and electronic properties of perylene-3,4,9,10-tetracarboxylic-3,4,9,10-dianhydride (PTCDA) and C60 on KBr(001) using density functional theory and non-contact atomic force microscopy to reveal the interplay of interactions between aromatic molecules and insulating substrates. Energetic and structural details are discussed, as well as electronic structures, e.g. local electronic density of states, (differential) charge density, and Bader charge analysis, were inspected. Electrostatics was found to be the primary interaction mechanism for systems of PTCDA and C60 adsorbed on KBr, which can be further promoted by electronic hybridizations of non-polar, but polarizable, molecules with substrates, e.g. C60/KBr(001). Electronic hybridization, depending on the polarizability of the π-system, may be suppressed by introducing high electron affinity atoms, e.g. O, into the molecule. Besides, we investigate molecules adsorbed on two-layer KBr(001) covered Cu(001), in which no hybridisation was found between PTCDA and the metal underneath, but a C-Br-Cu hybridized state in C60/KBr(001)/Cu(001). Since the interaction mechanism is dominated by electrostatics, it is concluded that alkali-halides are interesting and important materials for investigation, due to the minor influence on the molecular electronic structure, which may inspire new research fields of electronics.

Interlayer electronic hybridization leads to exceptional thickness-dependent vibrational properties in few-layer black phosphorus.

Stacking two-dimensional (2D) materials into multi-layers or heterostructures, known as van der Waals (vdW) epitaxy, is an essential degree of freedom for tuning their properties on demand. Few-layer black phosphorus (FLBP), a material with high potential for nano- and optoelectronics applications, appears to have interlayer couplings much stronger than graphene and other 2D systems. Indeed, these couplings call into question whether the stacking of FLBP can be governed only by vdW interactions, which is of crucial importance for epitaxy and property refinement. Here, we perform a theoretical investigation of the vibrational properties of FLBP, which reflect directly its interlayer coupling, by discussing six Raman-observable phonons, including three optical, one breathing and two shear modes. With increasing sample thickness, we find anomalous redshifts of the frequencies for each optical mode but a blueshift for the armchair shear mode. Our calculations also show splitting of the phonon branches, due to anomalous surface phenomena, and strong phonon-phonon coupling. By computing uniaxial stress effects, inter-atomic force constants and electron densities, we provide a compelling demonstration that these properties are the consequence of strong and highly directional interlayer interactions arising from the electronic hybridization of the lone electron-pairs of FLBP, rather than from vdW interactions. This exceptional interlayer coupling mechanism controls the stacking stability of BP layers and thus opens a new avenue beyond vdW epitaxy for understanding the design of 2D heterostructures.

Interface Coupling in Twisted Multilayer Graphene by Resonant Raman Spectroscopy of Layer Breathing Modes.

Raman spectroscopy is the prime nondestructive characterization tool for graphene and related layered materials. The shear (C) and layer breathing modes (LBMs) are due to relative motions of the planes, either perpendicular or parallel to their normal. This allows one to directly probe the interlayer interactions in multilayer samples. Graphene and other two-dimensional (2d) crystals can be combined to form various hybrids and heterostructures, creating materials on demand with properties determined by the interlayer interaction. This is the case even for a single material, where multilayer stacks with different relative orientations have different optical and electronic properties. In twisted multilayer graphene there is a significant enhancement of the C modes due to resonance with new optically allowed electronic transitions, determined by the relative orientation of the layers. Here we show that this applies also to the LBMs, which can be now directly measured at room temperature. We find that twisting has a small effect on LBMs, quite different from the case of the C modes. This implies that the periodicity mismatch between two twisted layers mostly affects shear interactions. Our work shows that ultralow-frequency Raman spectroscopy is an ideal tool to uncover the interface coupling of 2d hybrids and heterostructures.

High-mobility transport anisotropy and linear dichroism in few-layer black phosphorus.

Two-dimensional crystals are emerging materials for nanoelectronics. Development of the field requires candidate systems with both a high carrier mobility and, in contrast to graphene, a sufficiently large electronic bandgap. Here we present a detailed theoretical investigation of the atomic and electronic structure of few-layer black phosphorus (BP) to predict its electrical and optical properties. This system has a direct bandgap, tunable from 1.51 eV for a monolayer to 0.59 eV for a five-layer sample. We predict that the mobilities are hole-dominated, rather high and highly anisotropic. The monolayer is exceptional in having an extremely high hole mobility (of order 10,000 cm(2) V(-1) s(-1)) and anomalous elastic properties which reverse the anisotropy. Light absorption spectra indicate linear dichroism between perpendicular in-plane directions, which allows optical determination of the crystalline orientation and optical activation of the anisotropic transport properties. These results make few-layer BP a promising candidate for future electronics.

Role of the dispersion force in modeling the interfacial properties of molecule-metal interfaces: adsorption of thiophene on copper surfaces.

We present density functional theory calculations of the geometry, adsorption energy and electronic structure of thiophene adsorbed on Cu(111), Cu(110) and Cu(100) surfaces. Our calculations employ dispersion corrections and self-consistent van der Waals density functionals (vdW-DFs). In terms of speed and accuracy, we find that the dispersion-energy-corrected Revised Perdue-Burke-Enzerhof (RPBE) functional is the "best balanced" method for predicting structural and energetic properties, while vdW-DF is also highly accurate if a proper exchange functional is used. Discrepancies between theory and experiment in molecular geometry can be solved by considering x-ray generated core-holes. However, the discrepancy concerning the adsorption site for thiophene/Cu(100) remains unresolved and requires both further experiments and deeper theoretical analysis. For all the interfaces, the PBE functional reveals a covalent bonding picture which the inclusion of dispersive contributions does not change to a vdW one. Our results provide a comprehensive understanding of the role of dispersive forces in modelling molecule-metal interfaces.

[Analysis on the forms and release potential of nutrients in sediments from lakes in the West Jiangsu Province].

To probe the effect of nitrogen and phosphorus (P) in sediment on aqueous nutrient concentrations, forms of phosphorus, sediment water interface diffusion fluxes and phosphorus release and adsorption of 10 lakes in the west Jiangsu province were studied. Sediments were sequentially extracted by the modified Ruttenberg's method, and the result showed that inorganic phosphorus in sediments of the lakes was the major fraction of total phosphorus, but the proportion of bioavailable phosphorus was relatively low. Compared with the lakes in northern Jiangsu, the Fe-P was relatively high in sediments of lakes in southern Jiangsu. The diffusion fluxes of lakes were mainly based on NH4(+) -N diffusion in the west Jiangsu, and ions of most of lakes diffused from overlying water to sediment, NO3(-) -N diffused from sediment to overlying water in lakes except for Lake Hongze, Lake Shijiu and Lake Xuanwu. The condition leaning to acidic (pH < 4) or alkaline (pH > 10) was beneficial to phosphorus release, and except for Lake Xuanwu, the least amount of phosphorus released form sediment was higher in acidic condition than that in alkaline condition. The amount of phosphorus adsorption was increasing with temperature increase. Considering the phosphorus adsorption on native phosphorus polluted (NAP-polluted) sediments. All data of P adsorption on sediment samples collected from 7 lakes were fitted to the modified Langmuir model. And the values of the maximum adsorption capacity (Q(m)), phosphorus binding constant (k), native adsorbed exchangeable phosphorus (Q(NAP)), were subsequently obtained. The results showed that the adsorption amount of P in Lake Hongze and Lake Xuanwu was relatively low, which were liable to release P from sediments.

[Importation of wind-driven drift of mat-like algae bloom into Meiliang Bay of Taihu Lake in 2004 summer].

Driven by the prevailing south wind in summer, floating mat-like algal blooms in the open area of Taihu Lake would drift into Meiliang Bay located in the northern part of Taihu Lake. An exponential relationship between wind speed and algal drift velocity was found through controlled flume experiments and field observations. Then the relationship was applied to compute drift importation into Meiliang Bay in six dates when mat-like algal blooms were happening. During the six dates, except on 2004-07-31 the algal boom drifted outwards from Meiliang Bay with slight amounts of 0.05 km2; for the rest of dates, the importations were inwards positive, the maximum importation occurred on 2004-06-11, being 17.4 km2, and the minimum importation on 2004-07-30, being 4.8 km2; The results indicated importation of wind-driven algae drift during 24 hours accounts for 3.7% - 13.3% of the area of Meiliang Bay.