Tungsten-SiO2-Based Planar Field Emission Microtriodes with Different Electrode Topologies.

This study examines the electrical properties and layer quality of field emission microtriodes that have planar electrode geometry and are based on tungsten (W) and silicon dioxide (SiO2). Two types of microtriodes were analyzed: one with a multi-tip cathode fabricated using photolithography (PL) and the other with a single-tip cathode fabricated using a focused ion beam (FIB). Atomic force microscopy (AFM) analysis revealed surface roughness of the W layer in the order of several nanometers (Ra = 3.8 ± 0.5 nm). The work function values of the Si substrate, SiO2 layer, and W layer were estimated using low-energy ultraviolet photoelectron emission (PE) spectroscopy and were 4.71 eV, 4.85 eV, and 4.67 eV, respectively. The homogeneity of the W layer and the absence of oxygen and silicon impurities were confirmed via X-ray photoelectron spectroscopy (XPS). The PL microtriode and the FIB microtriode exhibited turn-on voltages of 110 V and 50 V, respectively, both demonstrating a field emission current of 0.4 nA. The FIB microtriode showed significantly improved field emission efficiency compared to the PL microtriode, attributed to a higher local electric field near the cathode.

Estimation of Thermal Stability of Si-SiO2-W Nanolayered Structures with Infrared Spectrometry.

Nanolayered coatings are proposed for use in microelectronic devices where the size/performance ratio is becoming increasingly important, with the aim to achieve existing quality requirements while reducing the size of the devices and improving their ability to perform stably over multiple cycles. Si-SiO2-W structures have been proposed as a potential material for the fabrication of microelectronic devices. However, before such materials can be implemented in devices, their properties need to be carefully studied. In this study, Si-SiO2-W nanolayered structures were fabricated and subjected to numerous thermal treatment cycles at 150 °C. A total of 33 heating cycles were applied, resulting in a cumulative exposure of 264 h. The changes in chemical bonds and microstructure were monitored using Fourier Transform Infrared spectrometry (FTIR) and scanning electron microscopy (SEM). The FTIR signal at 960 cm-1, indicating the presence of W deposited on SiO2, was selected to characterize the thermal stability during the heating cycles. The estimated signal intensity variation closely resembled the normal inhomogeneity of the nanolayers. The increase in slope intensity was estimated to be 1.7 × 10-5.

YABBY Genes in the Development and Evolution of Land Plants.

Mounting evidence from genomic and transcriptomic studies suggests that most genetic networks regulating the morphogenesis of land plant sporophytes were co-opted and modified from those already present in streptophyte algae and gametophytes of bryophytes sensu lato. However, thus far, no candidate genes have been identified that could be responsible for "planation", a conversion from a three-dimensional to a two-dimensional growth pattern. According to the telome theory, "planation" was required for the genesis of the leaf blade in the course of leaf evolution. The key transcription factors responsible for leaf blade development in angiosperms are YABBY proteins, which until recently were thought to be unique for seed plants. Yet, identification of a YABBY homologue in a green alga and the recent findings of YABBY homologues in lycophytes and hornworts suggest that YABBY proteins were already present in the last common ancestor of land plants. Thus, these transcriptional factors could have been involved in "planation", which fosters our understanding of the origin of leaves. Here, we summarise the current data on functions of YABBY proteins in the vegetative and reproductive development of diverse angiosperms and gymnosperms as well as in the development of lycophytes. Furthermore, we discuss a putative role of YABBY proteins in the genesis of multicellular shoot apical meristems and in the evolution of leaves in early divergent terrestrial plants.

The Huperzia selago Shoot Tip Transcriptome Sheds New Light on the Evolution of Leaves.

Lycopodiophyta-consisting of three orders, Lycopodiales, Isoetales and Selaginellales, with different types of shoot apical meristems (SAMs)-form the earliest branch among the extant vascular plants. They represent a sister group to all other vascular plants, from which they differ in that their leaves are microphylls-that is, leaves with a single, unbranched vein, emerging from the protostele without a leaf gap-not megaphylls. All leaves represent determinate organs originating on the flanks of indeterminate SAMs. Thus, leaf formation requires the suppression of indeterminacy, that is, of KNOX transcription factors. In seed plants, this is mediated by different groups of transcription factors including ARP and YABBY.We generated a shoot tip transcriptome of Huperzia selago (Lycopodiales) to examine the genes involved in leaf formation. Our H. selago transcriptome does not contain any ARP homolog, although transcriptomes of Selaginella spp. do. Surprisingly, we discovered a YABBY homolog, although these transcription factors were assumed to have evolved only in seed plants.The existence of a YABBY homolog in H. selago suggests that YABBY evolved already in the common ancestor of the vascular plants, and subsequently was lost in some lineages like Selaginellales, whereas ARP may have been lost in Lycopodiales. The presence of YABBY in the common ancestor of vascular plants would also support the hypothesis that this common ancestor had a simplex SAM. Furthermore, a comparison of the expression patterns of ARP in shoot tips of Selaginella kraussiana (Harrison CJ, etal. 2005. Independent recruitment of a conserved developmental mechanism during leaf evolution. Nature 434(7032):509-514.) and YABBY in shoot tips of H. selago implies that the development of microphylls, unlike megaphylls, does not seem to depend on the combined activities of ARP and YABBY. Altogether, our data show that Lycopodiophyta are a diverse group; so, in order to understand the role of Lycopodiophyta in evolution, representatives of Lycopodiales, Selaginellales, as well as of Isoetales, have to be examined.

Evolutionary aspects of non-cell-autonomous regulation in vascular plants: structural background and models to study.

Plasmodesmata (PD) serve for the exchange of information in form of miRNA, proteins, and mRNA between adjacent cells in the course of plant development. This fundamental role of PD is well established in angiosperms but has not yet been traced back to the evolutionary ancient plant taxa where functional studies lag behind studies of PD structure and ontogenetic origin. There is convincing evidence that the ability to form secondary (post-cytokinesis) PD, which can connect any adjacent cells, contrary to primary PD which form during cytokinesis and link only cells of the same lineage, appeared in the evolution of higher plants at least twice: in seed plants and in some representatives of the Lycopodiophyta. The (in)ability to form secondary PD is manifested in the symplasmic organization of the shoot apical meristem (SAM) which in most taxa of seedless vascular plants differs dramatically from that in seed plants. Lycopodiophyta appear to be suitable models to analyze the transport of developmental regulators via PD in SAMs with symplasmic organization both different from, as well as analogous to, that in angiosperms, and to understand the evolutionary aspects of the role of this transport in the morphogenesis of vascular plant taxa.

Epidemiology of fracture in the Russian Federation and the development of a FRAX model.

UNLABELLED: The incidence of hip, forearm and humeral fractures was studied in two cities from the Russian Federation. Fracture rates were used to create a FRAX model for Russia and to estimate the current and future burden of fracture. PURPOSE: There is scant information on the epidemiology of fracture in Russia. The aim of the study was to determine the incidence of major fractures in order to populate a new FRAX model and to characterise the burden and future burden of fractures. METHODS: The number of hip, forearm and humeral fractures was determined in two Russian cities with a well-defined catchment population over a 2-3-year period. Incidence rates for the two cities were merged and used to populate a FRAX model for Russia. Incidence rates were also applied to the general population in 2010 and 25 years later in 2035. RESULTS: A total of 6,012 fractures were documented. For hip fracture, 27 % of cases in Pervouralsk and 1.8 % in Yaroslavl were not registered in the hospital data base. The incidence of index fractures increased with age and was higher in women than in men. The lifetime probability of hip fracture at the age of 50 years was 4 % in men and 7 % in women. The total number of hip fractures estimated in 2010 (112,000) is expected to rise to 159,000 in 2035. The estimated number of major fractures will rise from 590,000 to 730,000 over the same time interval. CONCLUSIONS: Fragility fractures pose a serious health care problem in Russia. Urgent steps are needed to improve the acute management of hip fracture and long-term care of other osteoporotic fractures.

TNF-alpha and myocardial matrix metalloproteinases in heart failure: relationship to LV remodeling.

The cytokine tumor necrosis factor (TNF)-alpha has been causally linked to left ventricular (LV) remodeling, but the molecular basis for this effect is unknown. Matrix metalloproteinases (MMPs) have been implicated in cardiac remodeling and can be regulated by TNF-alpha. This study tested the central hypothesis that administration of a TNF-alpha blocking protein would prevent the induction of MMPs and alter the course of myocardial remodeling in developing LV failure. Adult dogs were randomly assigned to the following groups: 1) chronic pacing (250 beats/min, 28 days, n = 12), 2) chronic pacing with concomitant administration of a TNF-alpha blocking protein (TNF block) using a soluble p75 TNF receptor fusion protein (TNFR:Fc; administered at 0.5 mg/kg twice a week subcutaneously, n = 7), and 3) normal controls (n = 10). LV end-diastolic volume increased from control with chronic pacing (83 +/- 12 vs. 118 +/- 10 ml, P < 0.05) and was reduced with TNF block (97 +/- 9 ml, P < 0.05). MMP zymographic levels (92 kDa, pixels) increased from control with chronic pacing (36,848 +/- 9,593 vs. 87,247 +/- 12,912, P < 0.05) and was normalized by TNF block. Myocardial MMP-9 and MMP-13 levels by immunoblot increased with chronic pacing relative to controls (130 +/- 10% and 118 +/- 6%, P < 0.05) and was normalized by TNF block. These results provide evidence to suggest that TNF-alpha contributes to the myocardial remodeling process in evolving heart failure through the local induction of specific MMPs.