Hillslope hydrology and wetland response of two small zero-order boreal catchments on the Precambrian Shield

2007 ◽  
Vol 21 (22) ◽  
pp. 2979-2997 ◽  
Author(s):  
M. D. Frisbee ◽  
C. J. Allan ◽  
M. J. Thomasson ◽  
R. Mackereth
Keyword(s):  
Zero Order ◽  
Hillslope Hydrology ◽  
Precambrian Shield ◽  
Small Zero

TRANSPORTABILITY OF IODIDE IN SOME ORGANIC SOIL MATERIALS FROM THE PRECAMBRIAN SHIELD OF ONTARIO

1987 ◽  
Vol 67 (2) ◽  
pp. 353-366 ◽  
Author(s):  
J. T. KOCH ◽  
B. D. KAY
Keyword(s):  
Rate Constant ◽  
Nuclear Power ◽  
Power Plants ◽  
Organic Soil ◽  
Zero Order ◽  
Organic Soils ◽  
Order Kinetic ◽  
Precambrian Shield ◽  
Zero Order Kinetics ◽  
Order Kinetic Model

Knowledge of the transportability of the long-lived and potentially hazardous nuclide 129I in organic soils is important for evaluating the concept of safely disposing of radioactive fuel waste from Canadian nuclear power plants. The current concept for the disposal of nuclear fuel waste in Canada involves its emplacement in a vault mined 500–1000 m deep in a stable plutonic rock formation in the Canadian Shield. Degradation over time of components of the vault could lead to the entry of 129I to organic soils from contaminated groundwater. Twelve samples from nine organic soils, widely different in degree of humification and in parent vegetation, were collected from the Precambrian Shield of Ontario. Batch reaction techniques were used to measure the kinetics of iodide loss from solution in the presence of the organic soil materials. All soil materials exhibited an initial constant rate of iodide loss from solution (zero-order kinetics). The rate constants for iodide loss for the different soil materials ranged from 1.44 to 36.0 mg iodide per kilogram soil per day. The natural I content for the organic soil samples was positively correlated to the measured rate constant. It is concluded that the rate constant for iodide, as measured in the laboratory, is related to the processes that operate in the field to immobilize I under natural conditions, and that a zero-order kinetic model is appropriate for describing the loss of iodide from the solution phase in an organic soil. Key words: Organic soils, iodide-129, groundwater, transport kinetics, immobilization

Strain measurement in In0.2Ga0.8As/GaAs quantum wires by convergent beam electron diffraction

1995 ◽  
Vol 53 ◽  
pp. 444-445
Author(s):  
S. Hillyard ◽  
Y.-P. Chen ◽  
J.D. Reed ◽  
W.J. Schaff ◽  
L.F. Eastman ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Semiconductor Lasers ◽  
Quantum Wire ◽  
Quantum Wires ◽  
Convergent Beam Electron Diffraction ◽  
Zero Order ◽  
Beam Electron ◽  
Local Lattice ◽  
Device Applications ◽  
Convergent Beam

The positions of high-order Laue zone (HOLZ) lines in the zero order disc of convergent beam electron diffraction (CBED) patterns are extremely sensitive to local lattice parameters. With proper care, these can be measured to a level of one part in 104 in nanometer sized areas. Recent upgrades to the Cornell UHV STEM have made energy filtered CBED possible with a slow scan CCD, and this technique has been applied to the measurement of strain in In0.2Ga0.8 As wires.Semiconductor quantum wire structures have attracted much interest for potential device applications. For example, semiconductor lasers with quantum wires should exhibit an improvement in performance over quantum well counterparts. Strained quantum wires are expected to have even better performance. However, not much is known about the true behavior of strain in actual structures, a parameter critical to their performance.

Study on Discrete Autonomous Traffic Flow Model with Zero-Order Hold

CICTP 2020 ◽  
2020 ◽  
Author(s):  
Lidong Zhang ◽  
Wenxing Zhu ◽  
Mengmeng Zhang ◽  
Cuijiao Chen
Keyword(s):  
Traffic Flow ◽  
Flow Model ◽  
Zero Order ◽  
Traffic Flow Model

A Multivariate Analysis of the Pathological Narcissism Inventory’s Nomological Network

2017 ◽  
Author(s):  
Elizabeth A. Edershile ◽  
Leonard Simms ◽  
Aidan G.C. Wright
Keyword(s):  
Multivariate Analysis ◽  
Zero Order ◽  
Hierarchical Regression ◽  
Nomological Network ◽  
Pathological Narcissism ◽  
Personality Variables ◽  
Unique Variance ◽  
Pathological Narcissism Inventory ◽  
Narcissistic Grandiosity

The Pathological Narcissism Inventory (PNI; Pincus et al., 2009) has enjoyed widespread use in the study of the narcissism. However, questions have been raised about whether the PNI’s grandiosity scale adequately captures narcissistic grandiosity as well as other popular measures do. Specifically, some have noted that PNI grandiosity shows a pattern of external associations that diverges from patterns for narcissistic grandiosity predicted by experts, and is more similar to the predictions for the vulnerability scale than is desirable. Previous research driving these critiques has relied on patterns of zero-order correlations to examine the nomological networks of these scales. The present study reexamines the nomological networks of PNI grandiosity and vulnerability scales using hierarchical regression. Results indicate that once accounting for overlapping variance of vulnerability and grandiosity, the unique variance in the PNI’s grandiosity scale closely matches contemporary expert conceptualizations of narcissistic grandiosity based on expected associations with other personality variables.

Formulation and Evaluation of Nelfinavir Extended Release Trilayer Matrix Tablets by Design of Experiment

2018 ◽  
Vol 11 (5) ◽  
pp. 4259-4268
Author(s):  
Nirmala Rangu ◽  
Gande Suresh
Keyword(s):  
Controlled Release ◽  
Drug Release ◽  
Hydroxypropyl Methylcellulose ◽  
Magnesium Stearate ◽  
Zero Order ◽  
Matrix Tablets ◽  
Drug Dissolution ◽  
Crystalline Cellulose ◽  
Dissolution Profile ◽  
Release Formulation

The present study was aimed to develop once-daily controlled release trilayer matrix tablets of nelfinavir to achieve zero-order drug release for sustained plasma concentration. Nelfinavir trilayer matrix tablets were prepared by direct compression method and consisted of middle active layer with different grades of hydroxypropyl methylcellulose (HPMC), PVP (Polyvinyl Pyrrolidine) K-30 and MCC (Micro Crystalline Cellulose). Barrier layers were prepared with Polyox WSR-303, Xanthan gum, microcrystalline cellulose and magnesium stearate. Based on the evaluation parameters, drug dissolution profile and release drug kinetics DF8 were found to be optimized formulation. The developed drug delivery system provided prolonged drug release rates over a period of 24 h. The release profile of the optimized formulation (DF8) was described by the zero-order and best fitted to Higuchi model. FT-IR studies confirmed that there were no chemical interactions between drug and excipients used in the formulation. These results indicate that the approach used could lead to a successful development of a controlled release formulation of nelfinavir in the management of AIDS.

Gastroretentive Floating Capsules of Risedronate Sodium: Development, Optimization, in vitro and in vivo Evaluation in Healthy Human Volunteers

2015 ◽  
Vol 8 (2) ◽  
pp. 2835-2842
Author(s):  
Bhikshapathi D. V. R. N. ◽  
Arun Kumar Jarathi ◽  
Suresh Gande ◽  
Viswaja Medipally ◽  
Ramesh Bomma
Keyword(s):  
Drug Release ◽  
Sustained Release ◽  
Zero Order ◽  
Wet Granulation ◽  
Capsule Formulation ◽  
In Vivo Evaluation ◽  
Healthy Human ◽  
X Ray ◽  
Human Volunteers

Background and the purpose of the study: Risedronate sodium inhibits osteoclast bone resorption and modulates bone metabolism. Risedronate has a high affinity for hydroxyapatite crystals in bone and is a potent antiresorptive agent. In the present investigation efforts were made to improve the bioavailability of risedronate sodium by increasing the residence time of the drug through sustained-release matrix capsule formulation via gastroretentive mechanism. Capsules were prepared by wet granulation technique. The influence of gel forming agents, amount of risedronate and total weight of capsules on physical properties, in vitro buoyancy, drug release, FTIR, DSC, X-ray studies were investigated. The release mechanisms were explored and explained by applying zero order, first order, Higuchi and Korsmeyer equations. The selected formulations were subjected to stability study at 40 °C/75% RH, 25 °C/60% RH for the period of three months. For all formulations, kinetics of drug release from capsules followed Higuchi’s square root of time kinetic treatment heralding diffusion as predominant mechanism of drug release. Formulation containing 25 mg HPMC K4M and 75 mg HPMC K100 LV (F-8) showed zero order release profile. There was no significant change in the selected formulation, when subjected to accelerated stability conditions over a period of three months. X-ray imaging in six healthy human volunteers revealed a mean gastric retention period of 5.60 ± 0.77 hrs for the selected formulation. Stable, sustained release effervescent floating capsules of risedronate sodium could be prepared by wet granulation technique.  

Chemical and Biological Changes in Nelson Lake, Ontario Following Experimental Elevation of Lake pH

1977 ◽  
Vol 12 (1) ◽  
pp. 213-232 ◽  
Author(s):  
N.D. Yan ◽  
W.A. Scheider ◽  
P.J. Dillon
Keyword(s):  
Heavy Metal ◽  
Lake Ontario ◽  
Background Concentrations ◽  
Precambrian Shield ◽  
Metal Levels ◽  
Zooplankton Communities ◽  
Shield Lakes

Abstract Intensive studies of Nelson Lake, a Sudbury area lake of intermediate pH ~5.7), were begun in 1975. The chemistry of the lake was typical of that of most PreCambrian Shield lakes except that low alkalinities and high sulphate concentrations were observed along with elevated heavy metal levels. After raising the pH of Nelson Lake to 6.4 by addition of Ca(OH)2 and CaCO3, the metals were reduced to background concentrations. Phytoplankton and Zooplankton communities, which at pH of 5.7 were typical of PreCambrian lakes, were not affected by the experimental elevation of lake pH.

Formulation Development and Characterization of controlled release core in cup matrix tablets of venlafaxine HCl

2020 ◽  
Vol 15 ◽  
Author(s):  
Balaji Maddiboyina ◽  
Vikas Jhawat ◽  
Gandhi Sivaraman ◽  
Om Prakash Sunnapu ◽  
Ramya Krishna Nakkala ◽  
...  
Keyword(s):  
Controlled Release ◽  
Drug Release ◽  
Release Rate ◽  
Zero Order ◽  
Water Soluble ◽  
Matrix Tablets ◽  
Drug Dissolution ◽  
Crystalline Cellulose ◽  
Hydrophobic Polymers

Background: Venlafaxine HCl is a selective serotonin reuptake inhibitor which is given in the treatment of depression. The delivery of the drug at a controlled rate can be of great importance for prolonged effect. Objective: The objective was to prepare and optimize the controlled release core in cup matrix tablet of venlafaxine HCl using the combination of hydrophilic and hydrophobic polymers to prolong the effect with rate controlled drug release. Methods: The controlled release core in cup matrix tablets of venlafaxine HCl were prepared using HPMC K5, K4, K15, HCO, IPA, aerosol, magnesium sterate, hydrogenated castor oil and micro crystalline cellulose PVOK-900 using wet granulation technique. Total ten formulations with varying concentrations of polymers were prepared and evaluated for different physicochemical parameters such FTIR analysis for drug identification, In-vitro drug dissolution study was performed to evaluate the amount of drug release in 24 hrs, drug release kinetics study was performed to fit the data in zero order, first order, Hixson–crowell and Higuchi equation to determine the mechanism of drug release and stability studies for 3 months as observed. Results: The results of hardness, thickness, weight variation, friability and drug content study were in acceptable range for all formulations. Based on the In vitro dissolution profile, formulation F-9 was considered to be the optimized extending the release of 98.32% of drug up to 24 hrs. The data fitting study showed that the optimized formulation followed the zero order release rate kinetics and also compared with innovator product (flavix XR) showed better drug release profile. Conclusion: The core-in-cup technology has a potential to control the release rate of freely water soluble drugs for single administration per day by optimization with combined use of hydrophilic and hydrophobic polymers.

Race and Sex Differences and Fear of Dying: A Test of Two Hypotheses — High Risk or Social Loss?

1987 ◽  
Vol 17 (3) ◽  
pp. 229-236 ◽  
Author(s):  
Alan Marks
Keyword(s):  
Sex Differences ◽  
High Risk ◽  
Mortality Rates ◽  
National Sample ◽  
Zero Order ◽  
Fear Of Death ◽  
Level Of Education ◽  
Social Loss ◽  
Education And Health ◽  
The Social

A national sample of noninstitutionalized adult Americans is used to test two hypotheses and their relation to fear of death, The first hypothesis, referred to as the high risk hypothesis (i.e., groups with higher mortality rates will express more fear of death than groups with lower rates of mortality), is rejected. The second hypothesis, referred to as the social loss hypothesis, is developed and tested across six status categories—race, sex, age, religion, level of education, and health status. Zero order differences did appear for sex and race, however, these differences were eliminated with the introduction of controls. Both hypotheses are rejected.

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