The genus Synura (Synurales, Synurophyceae) in small urban rivers of Nizhniy Novgorod

2017 ◽  
Vol 51 ◽  
pp. 57-70 ◽  
Author(s):  
E. S. Gusev ◽  
O. S. Perminova ◽  
N. A. Startseva ◽  
A. G. Okhapkin
Keyword(s):  
Taxonomic Composition ◽  
Morphological Data ◽  
Small Rivers ◽  
Urban Rivers ◽  
Large Lakes ◽  
Volga River ◽  
Volga River Basin ◽  
Means Of Transmission ◽  
Special Studies ◽  
The City

The latest special studies of the genus Synura in Russia were conducted in the 1970s. In the last decade, 14 new species of the genus were described based on molecular and morphological data. The total number of valid taxa of the genus has increased to 49. Only 18 taxa of Synura are known in Russia up to date, and the diver sity of the genus on this huge territory is strongly underestimated. Previous studies of the genus were focused mainly on large lakes or reservoirs. To reveal a more complete flora, it is necessary to include other habitats into account. Small urban rivers can be prospective habitats for interesting taxa including synuralean algae. Our study focuses on the taxonomic composition of the genus Synura in four small rivers in Nizhniy Novgorod (European Russia): Chyornaya, Levinka, Borzovka and Rzhavka. All the rivers flow in the city and fall under strong anthropogenic impact. The genus Synura was studied by means of transmission and scanning electron microscopy during 2011, 2012, 2014, 2015. In total, eight species and one form of Synura have been found: S. conopea, S. curtispina, S. echinulata, S. glabra, S. macropora, S. petersenii, S. spinosa f. spinosa, S. spinosa f. longispina, S. uvella. All nine taxa were observed in the river Chyornaya. Five taxa were found in the rivers Levinka, Borzovka and Rzhavka. One species (Synura conopea) is a new record to the flora of Russia. It was found in all studied rivers. Four taxa (S. conopea, S. glabra, S. macropora, S. spinosa f. longispina) are new records to the Middle Volga river basin.

A new history of Ireland

1969 ◽  
Vol 16 (63) ◽  
pp. 241-257 ◽  
Author(s):  
T.W. Moody
Keyword(s):  
Scholarly Work ◽  
Irish History ◽  
New Knowledge ◽  
History Of ◽  
Special Studies ◽  
Source Materials

The completion in 1967 of thirty years of Irish Historical Studies has been the occasion for a stocktaking (still in progress) of the achievement of those years in Irish historiography. They are coming to be seen as an era of remarkable advances in specialist research, in professional technique, in historical organisation, and in the publication of special studies, source materials, bibliographies and aids to research. Though this research has been unevenly spread, it has produced an impressive body of new knowledge on many periods and topics. The conditions for scholarly work on Irish history have thus been transformed; and there is a world of difference between the prospects for Irish historiography in 1938 and now.

Improving the Strength of Abrasive Wheels and Optimizing the Control over the Strength of Composite Abrasive Materials

2019 ◽  
Vol 946 ◽  
pp. 380-385
Author(s):  
Boris A. Chaplygin ◽  
Viacheslav V. Shirokov ◽  
Tat'yana A. Lisovskaya ◽  
Roman A. Lisovskiy
Keyword(s):  
Mechanical Properties ◽  
Test Results ◽  
Key Factors ◽  
Special Equipment ◽  
Material Density ◽  
Factors Affecting ◽  
Control Factors ◽  
Reinforcing Material ◽  
Special Studies ◽  
First Time

The strength of abrasive wheels is one of the key factors affecting the performance of abrasive machining. The paper discusses ways to improve the strength of abrasive wheels. The stress-state mathematical model presented herein is a generalization of the existing models. It is used herein to find for the first time that there are numerous optimal combinations of the elastic modulus and reinforcing material density, which result in the same minimum value of the objective function. It is found out that increasing the radius of the reinforcing component while also optimizing the mechanical properties of its material may increase the permissible breaking speed of the wheel several times. We herein present a regression equation and a nomogram for finding the optimal combination of control factors. Conventional methods for testing the mechanical properties of materials, which have been proven reliable for testing metals and alloys, are not as reliable for testing abrasive materials, as the test results they generate are not sufficiently stable or accurate. We therefore propose an alternative method that does not require any special equipment or special studies.

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