scholarly journals Observations on the life cycles of aquatic Oligochaeta in aquaria

Zoosymposia ◽  
2020 ◽  
Vol 17 (1) ◽  
pp. 102-120
Author(s):  
TARMO TIMM
Keyword(s):  
Room Temperature ◽  
Elevated Temperatures ◽  
Life Cycles ◽  
Tubifex Tubifex ◽  
Lumbriculus Variegatus ◽  
Limnodrilus Hoffmeisteri ◽  
Mass Cultures ◽  
Potamothrix Hammoniensis ◽  
Observation Period ◽  
Made In

Observations on the life cycles of aquatic oligochaetes were made in the period 1962–2017 at the Võrtsjärv Limnological Station (Estonia) using small aquaria with sieved profundal mud covered with unaerated water. The aquaria were mostly inseminated with 10 juvenile worms and checked four times a year, changing the mud and eliminating the progeny, until the natural death of the original worms. Besides, mass cultures were kept in bigger aquaria. Many individuals of Tubifex tubifex, T. newaensis, Limnodrilus hoffmeisteri, L. udekemianus, Ilyodrilus templetoni, Psammoryctides barbatus, Spirosperma ferox, Potamothrix moldaviensis, P. vejdovskyi, P. bavaricus, Stylodrilus heringianus and Rhynchelmis tetratheca survived for several years, reproduced repeatedly, and died out one by one during the observation period. In some cases, the most longevous individuals reached an age of up to 8 years (I. templetoni), 10–12 years (T. tubifex), 15–17 years (L. hoffmeisteri, P. barbatus, S. heringianus), or even more than 20 years (L. udekemianus, S. ferox, T. newaensis). Criodrilus lacuum did not reproduce in aquaria, although the oldest individual spent 46 years there. Potamothrix hammoniensis, Lophochaeta ignota, Lamprodrilus isoporus, most naidines and some others did not thrive in aquaria and usually died without reproducing. In a cellar, where temperature conditions imitated seasonal fluctuations in lakes, or when the aquaria were maintained at continuously low temperature, the lifetime of worms was often longer than at room temperature. At elevated temperatures (+25° to +35°C) T. tubifex and L. hoffmeisteri formed cocoons mostly with only 1–2 eggs while their life span was then shorter. Architomic clones of Potamothrix bedoti, Bothrioneurum vejdovskyanum, Aulodrilus pluriseta and A. japonicus survived and propagated for years. The architomic Lumbriculus variegatus was thriving only when fed, e.g., with yeast. Uniparental reproduction by parthenogenesis was observed in T. tubifex, L. hoffmeisteri and S. heringianus kept or reared single. Two special races(?) were noted both within T. tubifex and L. udekemianus.

scholarly journals Profundal oligochaete faunas (Annelida, Clitellata) in Japanese lakes

Zoosymposia ◽  
2014 ◽  
Vol 9 (1) ◽  
pp. 24-35 ◽  
Author(s):  
AKIFUMI OHTAKA
Keyword(s):  
Trophic Status ◽  
Tubifex Tubifex ◽  
Lumbriculus Variegatus ◽  
Bottom Temperature ◽  
Eutrophic Lakes ◽  
Branchiura Sowerbyi ◽  
Limnodrilus Hoffmeisteri ◽  
Parallel Replacement ◽  
Main Factors ◽  
Japanese Islands

Thirty-eight species of oligochaetes (Annelida, Clitellata) belonging to five families were recorded from profundal bottoms of 50 freshwater lakes on Japanese islands. They were mostly widely distributed species, and the composition of fauna is basically explained by the scheme of Timm (2012), with parallel replacement of European species. Oxygen, temperature and surrounding fauna could be main factors determining the profundal fauna in the lakes. The lumbriculids (Styloscolex japonicus, Yamaguchia toyensis and Lumbriculus variegatus), haplotaxids (Haplotaxis gordioides) and enchytraeids (Marionina klaskisharum) were restricted to several deep and oligotrophic lakes located in Hokkaido and northern Honshu, where Rhyacodrilus komarovi often accompanied them. Limnodrilus hoffmeisteri was the commonest species, occurring irrespective of the trophic status and bottom temperature of the lake. Tubifex tubifex also occurred in wide trophic scale, but it has never been found in shallow eutrophic lakes where the bottom temperature exceeds 15°C, where L. hoffmeisteri, Branchiura sowerbyi and several Aulodrilus species were the main representatives.

Mechanical Properties and Dislocation Structure of Single Crystal Cdte Deformed in Compression at 300°C

1976 ◽  
Vol 34 ◽  
pp. 592-593
Author(s):  
Ernest L. Hall ◽  
J. B. Vander Sande
Keyword(s):  
Mechanical Properties ◽  
Single Crystal ◽  
Dislocation Structure ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Strain Curve ◽  
Optical Devices ◽  
Semiconductor Compound ◽  
Wide Range ◽  
Sample Orientation

The present paper describes research on the mechanical properties and related dislocation structure of CdTe, a II-VI semiconductor compound with a wide range of uses in electrical and optical devices. At room temperature CdTe exhibits little plasticity and at the same time relatively low strength and hardness. The mechanical behavior of CdTe was examined at elevated temperatures with the goal of understanding plastic flow in this material and eventually improving the room temperature properties. Several samples of single crystal CdTe of identical size and crystallographic orientation were deformed in compression at 300°C to various levels of total strain. A resolved shear stress vs. compressive glide strain curve (Figure la) was derived from the results of the tests and the knowledge of the sample orientation.

Spherulite Structures in a Melt Spun Fe-Ni Austenitic Steel

1985 ◽  
Vol 43 ◽  
pp. 52-53
Author(s):  
G. M. Michal ◽  
T. K. Glasgow ◽  
T. J. Moore
Keyword(s):  
Austenitic Steel ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Large Range ◽  
Amorphous Structure ◽  
Nucleation And Growth ◽  
Ni Alloys ◽  
Melt Spun ◽  
Crystal Fibers ◽  
Rapidly Solidified

Large additions of B to Fe-Ni alloys can lead to the formation of an amorphous structure, if the alloy is rapidly cooled from the liquid state to room temperature. Isothermal aging of such structures at elevated temperatures causes crystallization to occur. Commonly such crystallization pro ceeds by the nucleation and growth of spherulites which are spherical crystalline bodies of radiating crystal fibers. Spherulite features were found in the present study in a rapidly solidified alloy that was fully crysstalline as-cast. This alloy was part of a program to develop an austenitic steel for elevated temperature applications by strengthening it with TiB2. The alloy contained a relatively large percentage of B, not to induce an amorphous structure, but only as a consequence of trying to obtain a large volume fracture of TiB2 in the completely processed alloy. The observation of spherulitic features in this alloy is described herein. Utilization of the large range of useful magnifications obtainable in a modern TEM, when a suitably thinned foil is available, was a key element in this analysis.

DNA Inspirited Rational Construction of Nonconventional Luminophores with Efficient and Color-Tunable Afterglow

2020 ◽  
Author(s):  
Yunzhong Wang ◽  
Saixing Tang ◽  
Yating Wen ◽  
Shuyuan Zheng ◽  
Bing Yang ◽  
...  
Keyword(s):  
Rational Design ◽  
Room Temperature ◽  
Double Helix ◽  
Mechanical Grinding ◽  
Room Temperature Phosphorescence ◽  
Color Tunable ◽  
Potential Applications ◽  
Rational Construction ◽  
Double Helix Structure ◽  
Made In

<div>Persistent room-temperature phosphorescence (p-RTP) from pure organics is attractive </div><div>due to its fundamental importance and potential applications in molecular imaging, </div><div>sensing, encryption, anticounterfeiting, etc.1-4 Recently, efforts have been also made in </div><div>obtaining color-tunable p-RTP in aromatic phosphors5 and nonconjugated polymers6,7. </div><div>The origin of color-tunable p-RTP and the rational design of such luminogens, </div><div>particularly those with explicit structure and molecular packing, remain challenging. </div><div>Noteworthily, nonconventional luminophores without significant conjugations generally </div><div>possess excitation-dependent photoluminescence (PL) because of the coexistence of </div><div>diverse clustered chromophores6,8, which strongly implicates the possibility to achieve </div><div>color-tunable p-RTP from their molecular crystals assisted by effective intermolecular </div><div>interactions. Here, inspirited by the highly stable double-helix structure and multiple </div><div>hydrogen bonds in DNA, we reported a series of nonconventional luminophores based on </div><div>hydantoin (HA), which demonstrate excitation-dependent PL and color-tunable p-RTP </div><div>from sky-blue to yellowish-green, accompanying unprecedentedly high PL and p-RTP </div><div>efficiencies of up to 87.5% and 21.8%, respectively. Meanwhile, the p-RTP emissions are </div><div>resistant to vigorous mechanical grinding, with lifetimes of up to 1.74 s. Such robust, </div><div>color-tunable and highly efficient p-RTP render the luminophores promising for varying </div><div>applications. These findings provide mechanism insights into the origin of color-tunable </div><div>p-RTP, and surely advance the exploitation of efficient nonconventional luminophores.</div>

FANSTEEL 85 METAL

Alloy Digest ◽  
1981 ◽  
Vol 30 (6) ◽  
Keyword(s):  
High Temperature ◽  
Physical Properties ◽  
Creep Strength ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Base Alloy ◽  
Heat Treating ◽  
Good Combination ◽  
Bend Strength ◽  
Temperature Performance

Abstract FANSTEEL 85 METAL is a columbium-base alloy characterized by good fabricability at room temperature, good weldability and a good combination of creep strength and oxidation resistance at elevated temperatures. Its applications include missile and rocket components and many other high-temperature parts. This datasheet provides information on composition, physical properties, microstructure, hardness, elasticity, tensile properties, and bend strength as well as creep. It also includes information on low and high temperature performance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: Cb-7. Producer or source: Fansteel Metallurgical Corporation. Originally published December 1963, revised June 1981.

Strong Coupling: Polariton Bose Condensation

2017 ◽  
Author(s):  
Alexey V. Kavokin ◽  
Jeremy J. Baumberg ◽  
Guillaume Malpuech ◽  
Fabrice P. Laussy
Keyword(s):  
Strong Coupling ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Dissipative System ◽  
Bose Condensation ◽  
Einstein Condensation ◽  
Strong Coupling Regime ◽  
Stimulated Scattering ◽  
Exciton Polaritons ◽  
Bose Einstein

In this Chapter we address the physics of Bose-Einstein condensation and its implications to a driven-dissipative system such as the polariton laser. We discuss the dynamics of exciton-polaritons non-resonantly pumped within a microcavity in the strong coupling regime. It is shown how the stimulated scattering of exciton-polaritons leads to formation of bosonic condensates that may be stable at elevated temperatures, including room temperature.

On the use of Ozawa/Flynn/Wall method to determine aging activation energy for elastomers

2021 ◽  
pp. 009524432110203
Author(s):  
Sudhir Bafna
Keyword(s):  
Mechanical Properties ◽  
Activation Energy ◽  
Weight Loss ◽  
Oxygen Consumption ◽  
Dwell Time ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Degradation Mechanism ◽  
Kinetics Of ◽  
Wall Method

It is often necessary to assess the effect of aging at room temperature over years/decades for hardware containing elastomeric components such as oring seals or shock isolators. In order to determine this effect, accelerated oven aging at elevated temperatures is pursued. When doing so, it is vital that the degradation mechanism still be representative of that prevalent at room temperature. This places an upper limit on the elevated oven temperature, which in turn, increases the dwell time in the oven. As a result, the oven dwell time can run into months, if not years, something that is not realistically feasible due to resource/schedule constraints in industry. Measuring activation energy (Ea) of elastomer aging by test methods such as tensile strength or elongation, compression set, modulus, oxygen consumption, etc. is expensive and time consuming. Use of kinetics of weight loss by ThermoGravimetric Analysis (TGA) using the Ozawa/Flynn/Wall method per ASTM E1641 is an attractive option (especially due to the availability of commercial instrumentation with software to make the required measurements and calculations) and is widely used. There is no fundamental scientific reason why the kinetics of weight loss at elevated temperatures should correlate to the kinetics of loss of mechanical properties over years/decades at room temperature. Ea obtained by high temperature weight loss is almost always significantly higher than that obtained by measurements of mechanical properties or oxygen consumption over extended periods at much lower temperatures. In this paper, data on five different elastomer types (butyl, nitrile, EPDM, polychloroprene and fluorocarbon) are presented to prove that point. Thus, use of Ea determined by weight loss by TGA tends to give unrealistically high values, which in turn, will lead to incorrectly high predictions of storage life at room temperature.

Effects of Elevated Temperatures on the Compressive Strength of HFCC

2011 ◽  
Vol 261-263 ◽  
pp. 416-420 ◽  
Author(s):  
Fu Ping Jia ◽  
Heng Lin Lv ◽  
Yi Bing Sun ◽  
Bu Yu Cao ◽  
Shi Ning Ding
Keyword(s):  
Compressive Strength ◽  
Elevated Temperature ◽  
Fly Ash ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Relative Strength ◽  
Ordinary Concrete ◽  
Residual Compressive Strength ◽  
Fly Ash Concrete ◽  
The Relationship

This paper presents the results of elevated temperatures on the compressive of high fly ash content concrete (HFCC). The specimens were prepared with three different replacements of cement by fly ash 30%, 40% and 50% by mass and the residual compressive strength was tested after exposure to elevated temperature 250, 450, 550 and 650°C and room temperature respectively. The results showed that the compressive strength apparently decreased with the elevated temperature increased. The presence of fly ash was effective for improvement of the relative strength, which was the ratio of residual compressive strength after exposure to elevated temperature and ordinary concrete. The relative compressive strength of fly ash concrete was higher than those of ordinary concrete. Based on the experiments results, the alternating simulation formula to determine the relationship among relative strength, elevated temperature and fly ash replacement is developed by using regression of results, which provides the theoretical basis for the evaluation and repair of HFCC after elevated temperature.

Development of 8 mΩ-cm2, 1.8 kV 4H-SiC DMOSFETs

2006 ◽  
Vol 527-529 ◽  
pp. 1261-1264 ◽  
Author(s):  
Sei Hyung Ryu ◽  
Sumi Krishnaswami ◽  
Brett A. Hull ◽  
Bradley Heath ◽  
Mrinal K. Das ◽  
...  
Keyword(s):  
Threshold Voltage ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Gate Length ◽  
Gate Bias ◽  
Low Loss ◽  
Layer Resistance ◽  
Switching Characteristics ◽  
Mos Gate ◽  
Drift Layer

8 mΩ-cm2, 1.8 kV power DMOSFETs in 4H-SiC are presented in this paper. A 0.5 μm long MOS gate length was used to minimize the MOS channel resistance. The DMOSFETs were able to block 1.8 kV with the gate shorted to the source. At room temperature, a specific onresistance of 8 mΩ-cm2 was measured with a gate bias of 15 V. At 150 oC, the specific onresistance increased to 9.6 mΩ-cm2. The increase in drift layer resistance due to a decrease in bulk electron mobility was partly cancelled out by the negative shift in MOS threshold voltage at elevated temperatures. The device demonstrated extremely fast, low loss switching characteristics. A significant improvement in converter efficiency was observed when the 4H-SiC DMOSFET was used instead of an 800 V silicon superjunction MOSFET in a simple boost converter configuration.

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