Diet selection in Arctic lemmings (Lemmus sibericus and Dicrostonyx groenlandicus): food preferences

1985 ◽  
Vol 63 (5) ◽  
pp. 1161-1173 ◽  
Author(s):  
Arthur R. Rodgers ◽  
Martin C. Lewis
Keyword(s):  
Selection Process ◽  
Food Preferences ◽  
Secondary Compounds ◽  
Diet Selection ◽  
Caloric Content ◽  
Dicrostonyx Groenlandicus ◽  
In Captivity ◽  
Preference Patterns ◽  
The Stability ◽  
Physical And Chemical

Testing of hypotheses relating lemming population dynamics to their food supply requires a detailed understanding of several major components of the diet selection process such as requirements, availability, preference, and selectivity. In this study, food preferences of Arctic lemmings were determined in cafeteria trials: Lemmus preferred graminoids and moss, while Dicrostonyx preferred shrubs and herbs. The stability of these preference patterns in each species was tested in further experimental cafeteria trials. Individuals of both species were pretreated on one of several diets, and two main types of trial were conducted involving limited and unlimited availability of test foods. Naive animals of both species, born and raised in captivity on artificial diets, were also used in the trials. In all cases, preference patterns in each species were maintained, suggesting that they are strongly heritable. Comparison of preference indices to the physical and chemical characteristics of tundra plants indicates that preference patterns in both species are related primarily to macronutrients and caloric content. Differences between Lemmus and Dicrostonyx are determined by secondary compounds and the physical characteristics of the plant species preferred by each. Comparison of ingestion rates and digestibility coefficients indicate that Dicrostonyx has a greater capacity than Lemmus in dealing with the negative characteristics of plants, such as secondary compounds or the presence of plant "hairs."

Small-bioreactor platform technology as a municipal wastewater additive treatment

2013 ◽  
Vol 69 (3) ◽  
pp. 504-510 ◽  
Author(s):  
Ofir Menashe ◽  
Eyal Kurzbaum
Keyword(s):  
Biological Treatment ◽  
Municipal Wastewater ◽  
Selection Process ◽  
Study Results ◽  
Different Types ◽  
Selective Forces ◽  
The Stability ◽  
Physical And Chemical ◽  
The Impact ◽  
The Relationship

The bioaugmentation treatment approach presents both an economical and environmentally friendly solution for wastewater treatment. However, the use of exogenous bacterial cultures presents several limitations: negative interaction between microorganisms and adaptation to new physical and chemical composite environment. These selective forces create a significant challenge for the introduced culture to achieving the required biomass in order to conduct the target biological treatment. Small-bioreactor platform (SBP) technology is aimed at introducing exogenous bacterial culture with some protection to reduce some of the natural selection process. The current study was aimed at validating the use of SBP technology to improve biological treatment, especially during a stress period, by using macro-encapsulated bioaugmentation treatment. The study results indicate that the use of SBP technology elevates the stability of biological treatment, improving operational factors such as the reduction of foaming phenomena and sludge accumulation. Still, a significant study needs to be conducted to understand the potential of this technology; especially the impact on biological treatment by using different types of microorganisms for different types of wastewaters and the relationship between the biomass within the SBP capsules and the natural microorganisms.

Diet selection in Arctic lemmings (Lemmus sibiricus and Dicrostonyx groenlandicus): forage availability and natural diets

1986 ◽  
Vol 64 (8) ◽  
pp. 1684-1689 ◽  
Author(s):  
Arthur R. Rodgers ◽  
Martin C. Lewis
Keyword(s):  
Northwest Territories ◽  
Selection Process ◽  
Diet Selection ◽  
Population Fluctuations ◽  
Site Specific ◽  
Forage Availability ◽  
Dicrostonyx Groenlandicus ◽  
Salix Arctica ◽  
Winter Diets ◽  
Deciduous Shrub

We describe forage availability and diets of the lemmings Lemmus sibiricus and Dicrostonyx groenlandicus at Igloolik Island, Northwest Territories. Summer and winter diets of Dicrostonyx were dominated by the evergreen shrub Dryas integrifolia and supplemented by the deciduous shrub Salix arctica. Lemmus ate mainly graminoids and some mosses in summer but the reverse in winter. In both species, winter diets were similar in different habitats. Comparison with diets of lemmings in Alaska show sufficient similarity to explain the synchrony of population fluctuations over wide geographical areas. Site-specific differences occur, however, and these are accounted for by an examination of the diet selection process in each species. These differences have important implications for the demography of lemmings at different sites.

scholarly journals Combination of Self-Healing Butyl Rubber and Natural Rubber Composites for Improving the Stability

Polymers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 443
Author(s):  
Kunakorn Chumnum ◽  
Ekwipoo Kalkornsurapranee ◽  
Jobish Johns ◽  
Karnda Sengloyluan ◽  
Yeampon Nakaramontri
Keyword(s):  
Natural Rubber ◽  
Dynamic Mechanical Properties ◽  
Attenuated Total Reflection ◽  
Rubber Matrix ◽  
Self Healing ◽  
Mechanical And Electrical Properties ◽  
Natural Rubber Composites ◽  
Tan Δ ◽  
The Stability ◽  
Physical And Chemical

The self-healing composites were prepared from the combination of bromobutyl rubber (BIIR) and natural rubber (NR) blends filled with carbon nanotubes (CNT) and carbon black (CB). To reach the optimized self-healing propagation, the BIIR was modified with ionic liquid (IL) and butylimidazole (IM), and blended with NR using the ratios of 70:30 and 80:20 BIIR:NR. Physical and chemical modifications were confirmed from the mixing torque and attenuated total reflection-fourier transform infrared spectroscopy (ATR-FTIR). It was found that the BIIR/NR-CNTCB with IL and IM effectively improved the cure properties with enhanced tensile properties relative to pure BIIR/NR blends. For the healed composites, BIIR/NR-CNTCB-IM exhibited superior mechanical and electrical properties due to the existing ionic linkages in rubber matrix. For the abrasion resistances, puncture stress and electrical recyclability were examined to know the possibility of inner liner applications and Taber abrasion with dynamic mechanical properties were elucidated for tire tread applications. Based on the obtained Tg and Tan δ values, the composites are proposed for tire applications in the future with a simplified preparation procedure.

Micro-Ribbons and Micro-Wires Silica Synthesis Using Bottom-Top Technique

2020 ◽  
Vol 1008 ◽  
pp. 33-38
Author(s):  
Marwa Nabil ◽  
Hussien A. Motaweh
Keyword(s):  
Selection Process ◽  
Chemical Properties ◽  
Industrial Applications ◽  
Preparation Process ◽  
Pure Silica ◽  
One Step ◽  
Materials Used ◽  
Sonication Technique ◽  
Silica Synthesis ◽  
Physical And Chemical

Silica is one of the most important materials used in many industries. The basic factor on which the selection process depends is the structural form, which is dependent on the various physical and chemical properties. One of the common methods in preparing pure silica is that it needs more than one stage to ensure the preparation process completion. The goal of this research is studying the nucleation technique (Bottom-top) for micro-wires and micro-ribbons silica synthesis. The silica nanoand microstructures are prepared using a duality (one step); a combination of alkali chemical etching process {potassium hydroxide (3 wt %) and n-propanol (30 Vol %)} and the ultra-sonication technique. In addition, the used materials in the preparation process are environmentally friendly materials that produce no harmful residues. The powder product is characterized using XRD, FTIR, Raman spectrum and SEM for determining the shape of architectures. The most significant factor of the nucleation mechanism is the sonication time of silica powder production during the dual technique. The product stages are as follows; silica nanoparticles (21-38 nm), nanoclusters silica (46 – 67 nm), micro-wires silica (1.17 – 6.29 μm), and micro-ribbons silica (19.4 – 54.1 μm). It's allowing for use in environmental applications (multiple wastewater purification, multiple uses in air filters, as well as many industrial applications).

Formulation, Physical and Chemical Stability of Ocimum gratissimum L. Leaf Oil Nanoemulsion

2021 ◽  
Vol 901 ◽  
pp. 117-122
Author(s):  
Netnapa Ontao ◽  
Sirivan Athikomkulchai ◽  
Sarin Tadtong ◽  
Phuriwat Leesawat ◽  
Chuda Chittasupho
Keyword(s):  
Essential Oil ◽  
Zeta Potential ◽  
Chemical Stability ◽  
Polydispersity Index ◽  
Hydrodynamic Diameter ◽  
Potential Value ◽  
Yellow Color ◽  
Leaf Oil ◽  
The Stability ◽  
Physical And Chemical

Ocimum gratissimum L. leaf oil exhibited many pharmacological properties. This study aimed to formulate and evaluate the physical and chemical stability of O.gratissimum leaf oil nanoemulsion. O.gratissimum leaf oil was extracted by hydrodistillation. The major component of the essential oil eugenol, was analyzed by UV-Vis spectrophotometry. Nanoemulsions of O.gratissimum leaf oil were formulated using polysorbate 80, hyaluronic acid, poloxamer 188, and deionized water by phase inversion composition method. The hydrodynamic diameter, polydispersity index, and zeta potential value of O.gratissimum leaf oil nanoemulsion was evaluated by a dynamic light scattering technique. The %remaining of eugenol in the nanoemulsion was analyzed by UV-Vis spectrophotometry. The essential oil extracted from of O. gratissimum leaf oil was a clear, pale yellow color. The %yield of the essential oil was 0.15 ± 0.03% v/w. The size of the nanoemulsion was less than 106 nm. The polydispersity index of the nanoemulsion was ranging from 0.303 - 0.586 and the zeta potential value of the nanoemulsion was closely to zero, depending on the formulation component. O. gratissimum leaf oil at concentrations ranging from 0.002 - 0.012% v/v contained 35 - 41% of eugenol. The size of nanoemulsion was significantly decreased after storage at 4 °C, while significantly increased upon storage at 45 °C. The size of nanoemulsion stored at 30 °C did not significantly change. The %remaining of eugenol in the nanoemulsion was more than 90% after storage at 4 °C and 30 °C for 28 days. The percentage of eugenol remaining in the nanoemulsion stored at 45 °C was more than 85 - 90%, suggesting that the temperature affected the stability of eugenol in the nanoemulsion.

scholarly journals Physicochemical Stability of 5 mg/mL Pediatric Prednisone Oral Suspension in Syrspend® SF PH4

2018 ◽  
Vol 0 (0) ◽  
Author(s):  
Anne-Claire Bonnaure ◽  
Romain Bellay ◽  
Pauline Rault ◽  
Marie-Antoinette Lester ◽  
Pierre-Nicolas Boivin
Keyword(s):  
Degradation Product ◽  
Sodium Benzoate ◽  
High Performance ◽  
Room Temperature ◽  
Inflammatory Diseases ◽  
Oral Suspension ◽  
Stability Indicating Method ◽  
Physicochemical Stability ◽  
The Stability ◽  
Physical And Chemical

Abstract Background Prednisone is a corticosteroid used in several inflammatory diseases and cancers. In France, no available prednisone drinkable formulation exists. Instead, an oral syrup of prednisone with ethanol, sodium benzoate and simple syrup is produced. However, sodium benzoate can induce neonatal icterus and alcohol is not authorized for children below 3 years of age. The aim of this study was to determine the stability of 5 mg/mL prednisone oral suspension in a commercial compounding excipient: Syrspend® SF PH4. Methods Three batches of oral suspensions were prepared, using micronized prednisone and Syrspend® SF PH4. They were packaged in amber glass vials and stored at room temperature. On day 0, 1, 4, 10, 30, 60 and 90, we observed physical and chemical stability (pH measurement, osmolality measurement, residual concentrations of prednisone and degradation product identification). A stability indicating method was developed using high performance liquid chromatography with Ultraviolet detection at 254 nm. Results Prednisone concentrations remained stable within ± 5 % of nominal values for 60 days. No degradation product and change of physicochemical properties were detected. Conclusion This study showed that 5 mg/mL prednisone oral suspension in Syrspend® SF PH4 is stable for 60 days, at room temperature and protected from light.

Synthesis and Kinetic Investigations for the Isomerization Process of 2–Hydroxy Chalcone Derivatives

2019 ◽  
Vol 41 (6) ◽  
pp. 1046-1046
Author(s):  
Omar A Shareef Omar A Shareef ◽  
Said A Said and Ali Y Abdulrazaq Said A Said and Ali Y Abdulrazaq
Keyword(s):  
Biological Activities ◽  
Chemical Properties ◽  
Physical And Chemical Properties ◽  
Pseudo First Order Reaction ◽  
First Order ◽  
Steric Factors ◽  
Kinetic Investigations ◽  
The Stability ◽  
Physical And Chemical ◽  
And Chemical Properties

The wide biological activities of flavanones are mainly depends on their physical and chemical properties, thus a number of substituted 2-Hydroxy chalcones have been synthesized, and their isomerization to their corresponding flavanones was studied. In order to determine the rate constant, kinetic experiments were performed using HPLC technique in (9:1) (CH3CN:H2O) medium at different temperature (298-318) K. The obtained results were interpreted by four steps mechanism, which considered the existence of phenoxide ion as the key intermediate. This study performed with a pseudo first order ( reaction in which the rate for the studied compounds follow the sequence 5 andgt; 2 andgt; 1 andgt; 4 andgt; 3, the activation energy have the same sequence for these compounds .The effect of substituents on the rate showed that electronic and steric factors play reasonable role on the stability of the product .

The Establishment of the 3rd National Reference Standard for Tachypleus Tridentatus Lysate

2017 ◽  
Vol 6 (3) ◽  
pp. 50
Author(s):  
Tong Cai ◽  
Guolai Zhang ◽  
Yusheng Pei ◽  
Hua Gao
Keyword(s):  
Chemical Properties ◽  
Physical And Chemical Properties ◽  
Reference Standard ◽  
Tachypleus Tridentatus ◽  
National Reference ◽  
The Stability ◽  
Physical And Chemical ◽  
And Chemical Properties

<p><strong>Objective</strong>  To establish the 3rd national reference standard for Tachypleus Tridentatus Lysate Reagent. <strong>Method</strong> <strong>and Results</strong>  The candidates of reference standard were studied for the physical and chemical properties, and the stability. To determined its sensitivity by collaboration calibration. <strong>Conclusions</strong>  The sensitivity of the 3rd national reference standard for TAL is 0.06EU / ml, lot number is 150603-201003.</p>

Stability of Colloidal Dispersions: A Thermodynamic Approach

1993 ◽  
Vol 27 (10) ◽  
pp. 117-129 ◽  
Author(s):  
Raj Rajagopalan
Keyword(s):  
Virial Coefficient ◽  
Second Virial Coefficient ◽  
Colloidal Dispersions ◽  
Chemical Parameters ◽  
Interaction Forces ◽  
Colloidal Forces ◽  
Stability Diagrams ◽  
The Stability ◽  
Physical And Chemical ◽  
Interparticle Collisions

The classical theory of coagulation relies on relating the rate of interparticle collisions to the interaction forces, and thus to the physical and chemical parameters of the dispersion, through kinetic arguments, and is restricted to dilute systems. Here, we present a modern, thermodynamic theory capable of predicting stability diagrams for dense as well as dilute dispersions. Although based on statistical thermodynamics, the method is simple to use and requires only the second virial coefficient of osmotic pressure of the dispersion. All the information necessary for applying the model to arbitrary dispersions is given. The method is illustrated for a model colloidal potential, and it is shown how static light scattering measurements can be used for predicting the stability diagrams when information about the colloidal forces are not known in advance.

Aging and Fatigue of Aerosol Jet-Printed Nano-Ag Traces on Flexible Substrate

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Arun Raj ◽  
Rajesh Sharma Sivasubramony ◽  
Manu Yadav ◽  
Sanoop Thekkut ◽  
Gurvinder Singh Khinda ◽  
...  
Keyword(s):  
Fatigue Resistance ◽  
Selection Process ◽  
Flexible Substrate ◽  
Accelerated Aging ◽  
Organic Matrix ◽  
Subsequent Aging ◽  
Long Term Storage ◽  
Order Of Magnitude ◽  
Sintering Conditions ◽  
The Stability

Abstract Conducting traces on a flexible substrate often have to survive significant and repeated deformation, making their fatigue resistance and the stability of it during long-term storage and use a potential concern. The question of stability is obvious in the case of, for example, screen or ink jet-printed traces where the organic matrix remains a critical part of the structure. We show it also to be important for nano-Ag traces that are sintered to ensure metallic bonding between the particles while eliminating most of the organics. We also show conventional accelerated aging tests to be potentially confusing or misleading for such traces, depending among other on practical limitations on sintering conditions. Examples are presented of how the fatigue resistance of application relevant aerosol jet-printed nano-Ag traces may degrade relatively rapidly at moderate temperatures. Even after “optimized” sintering at a much higher temperature subsequent aging at 75 °C for only 100 h led to an order of magnitude reduction in the fatigue life in subsequent mild cycling. The rate of degradation is certain to vary with the design and the ink used as well as with sintering conditions, making it important to account for it all in materials selection, process optimization, and assessments of practical life.

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