Impact cratering and the surface age of Venus: The Pre-Magellan controversy

The average surface age of a planet is a major indicator of the level of its geologic activity and thus of the dynamics of its interior. Radar images obtained by Venera 15/16 from the northern quarter of the Venus (lat 30 to 90 degs) reveal about 150 features that resemble impact craters, and they were so interpreted by Soviet investigators B. A. Ivanov, A. T. Basilevsky, and their colleagues. These features range in diameter from about 10 to 145 km. Their areal density is remarkably similar to the density of impact structures found on the American and European continental shields. The basic difference between the Soviet and American estimates of the average surface age of Venus's northern quarter is due to which crater-production rate is used for the Venusian environment. Cratering rates based on the lunar and terrestrial cratering records, as well as statistical calculations based on observed and predicted Venus-crossing asteroids and comets, have been used in both the Soviet and American calculations. The single largest uncertainty in estimating the actual cratering rates near Venus involves the shielding effect of the atmosphere

A Translation Initiation Element Specific to mRNAs with Very Short 5′UTR that Also Regulates Transcription

Transcription is controlled by cis regulatory elements, which if localized downstream to the transcriptional start site (TSS), in the 5′UTR, could influence translation as well. However presently there is little evidence for such composite regulatory elements. We have identified by computational analysis an abundant element located downstream to the TSS up to position +30, which controls both transcription and translation. This element has an invariable ATG sequence, which serves as the translation initiation codon in 64% of the genes bearing it. In these genes the initiating AUG is preceded by an extremely short 5′UTR. We show that translation in vitro and in vivo is initiated exclusively from the AUG of this motif, and that the AUG flanking sequences create a strong translation initiation context. This motif is distinguished from the well-known Kozak in its unique ability to direct efficient and accurate translation initiation from mRNAs with a very short 5′UTR. We therefore named it TISU for Translation Initiator of Short 5′UTR. Interestingly, this translation initiation element is also an essential transcription regulatory element of Yin Yang 1. Our characterization of a common transcription and translation element points to a link between mammalian transcription and translation initiation

Influence of herbicides, insecticides and fungicides on food consumption and body weight of Rossiulus kessleri (Diplopoda, Julidae)

Pesticides kill organisms harmful for the human organism, sometimes also harming beneficial ones. After treatment, pesticides remain on the soil surface in agrocenoses and adjacent plots for decades. For the laboratory experiment, we selected Rossiulus kessleri (Lochmander, 1927) – a species which lives 5–6 years on the soil surface and can dig in to soil to a depth of 30–40 cm. During a 20-day experiment we used herbicides (Roundup, Urahan Forte), insecticides (Omite, BI 58, Biotlin, Actellic, Nurelle D) and fungicides (Ridomil Gold, Thiovit Jet, Penncozeb 80 WP, Falcon, Tilt, Horus) which are often used in agrocenosises of Ukraine. Under the impact of Roundup and Urahan, body weight of R. kessleri reliably did not change, but food consumption and production of excrement increased. Pesticide-treated litter did not digest in the intestine of millipedes, but they survived to the end of the experiment (20 days). In the conditions of treating litter with insecticides Omite, BI 58, Biotlin, Actellic and Nurelle D, the amount of consumed food and body weight reliably did not change; most of these insecticides slowed the formation of feces in the millipedes. The highest studied concentrations of Actellic and Nurelle D preparations caused death to R. kessleri. Depending on the concentration in the litter, the studied fungicides Ridomil Gold, Thiovit Jet, Penncozeb, Falcon, Tilt, Horus had a varying effect on food consumption, body weight and the amount of excrement of R. kessleri. Thus, in agrocenoses and forest ecosystems adjacent to them (windbreaks, ravine and flood plain forests), R. kessleri can be significantly affected by the manufacturer-recommended doses of pesticides, as well as more than ten-fold lower doses

Tensile and nanoindentation tests analysis of Ti6Al4V alloy manufactured by laser powder bed fusion

Additive manufacturing (AM) technologies are widely used in the fabrication of topologically complex components with thin-walled features, such as lattice structures. In this context, Laser Powder Bed Fusion (L-PBF) is one of the most commonly used AM technologies for producing such components. In order to further expand and justify the application of these components in operation and to model their mechanical behavior, it is necessary to know the mechanical properties of the matrix material from which they are formed. Therefore, there is currently a high interest in studying the behavior of these materials when subjected to monotonic or cyclic loading. However, determining the mechanical properties of the matrix material of thin-walled structures using tensile tests is challenging on the required subsize specimens. As a micro- or even nano-scale technology, nanoindentation can be used to probe a small volume of specimen, thus allowing the mechanical properties such as Young modulus, of thin-walled structures to be determined. In this work, Young's modulus of L-PBF Ti6Al4V alloy produced using different laser power and scanning speed combinations, has been determined on nano and macro scale. By comparing obtained results at both scales, it is evident that Young's modulus values determined at nano scale are higher and more scattered when compared to results determined at macro scale. Furthermore, this study implies that a wider range or a higher number of L-PBF process parameters should be considered to model it's influence on Young's modulus with higher accuracy

Morphological and anatomical characterization of Actinidia kolomikta (Rupr. & Maxim.) Maxim. (C3) and Amaranthus tricolor L. (C4) leaves

Received: February 1st, 2022 ; Accepted: March 27th, 2022 ; Published: April 27th, 2022 ; Correspondence: [email protected] and anatomical features of new cultivars with photosynthesis of C3 (Actinidia kolomikta (Rupr. & Maxim.) Maxim. cv. ‘Narodnaya’) and C4 (Amaranthus tricolor L. cv. ‘Valentina’) were established by light and scanning electron microscopy, as well as energy-dispersive analysis. The leaf lamina of Actinidia kolomikta cv. ‘Narodnaya’ has a dorsoventral anatomical structure, anomocytic stomata on the abaxial epidermis and two types of trichomes: multicellular, uniseriate hairs and multicellular bristle-like protrusions, containing raphids. The needle-like raphides are located in subepidermal layers along the veins. A vascular system of petiole consists of two upper concentric bundles and the crescentic vascular strand. A starch sheat is present. Raphides (needle-shaped and rectangular) are located in phloem and cortical parenchyma cells, contain Ca, K, Mg, P and Si. The leaf lamina of Amaranthus tricolor cv. ‘Valentina’ have the kranz-anatomy, dorsiventral mesophyll and contain druses. Betacyanins are concentrated in the epidermis and mesophyll, but are not present in the bundle sheath. The number of vascular bundles in petioles is odd-numbered and variable (from 5 to 13). Trichomes are multicellular, uniseriate, ending in a large oval cell. Cells with betacyanins are present in the epidermis cortex, and, rarely, the collenchyma and phloem of the petiole. Cells with betaxanthins are absent. A starch sheat is brightly pigmented with betacyanins. The crystall sand is deposited in the parenchyma cells of the cortex and pith of the petiole and contains Ca (mainly) and K oxalates. Druses in the leaf lamina additionally contain Mg and P