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1

Design and In vitro Evaluation of Oral Floating Matrix Tablets of Aceclofenac  

Microsoft Academic Search

The purpose of this research was to prepare floating matrix drug delivery system of aceclofenac.Floating matrix tablets of aceclofenac were developed to prolong gastric residence time and increase its bioavailability. Rapid gastrointestinal transit could result in incomplete drug release from the drug delivery system above the absorption zone leading to diminished efficacy of the administered dose. Floating matrix tablets containing

Ravi Kumar; Swati Patil; M. B. Patil; Sachin R. Patil; Mahesh S. Paschapur

2

Development and in vitro evaluation of an oral floating matrix tablet formulation of diltiazem hydrochloride.  

PubMed

The purpose of this research was to prepare a floating drug delivery system of diltiazem hydrochloride (DTZ). Floating matrix tablets of DTZ were developed to prolong gastric residence time and increase its bioavailability. Rapid gastrointestinal transit could result in incomplete drug release from the drug delivery system above the absorption zone leading to diminished efficacy of the administered dose. The tablets were prepared by direct compression technique, using polymers such as hydroxypropylmethylcellulose (HPMC, Methocel K100M CR), Compritol 888 ATO, alone or in combination and other standard excipients. Sodium bicarbonate was incorporated as a gas-generating agent. The effects of sodium bicarbonate and succinic acid on drug release profile and floating properties were investigated. A 3(2) factorial design was applied to systematically optimize the drug release profile. The amounts of Methocel K100M CR (X1) and Compritol 888 ATO (X2) were selected as independent variables. The time required for 50% (t50) and 85% (t85) drug dissolution were selected as dependent variables. The results of factorial design indicated that a high level of both Methocel K100M CR (X1) and Compritol 888 ATO (X2) favors the preparation of floating controlled release of DTZ tablets. Comparable release profiles between the commercial product and the designed system were obtained. The linear regression analysis and model fitting showed that all these formulations followed Korsmeyer and Peppas model, which had a higher value of correlation coefficient (r). While tablet hardness had little or no effect on the release kinetics and was found to be a determining factor with regards to the buoyancy of the tablets. PMID:17915823

Gambhire, Manoj N; Ambade, Kshitij W; Kurmi, Sushma D; Kadam, Vilasrao J; Jadhav, Kisan R

2007-09-07

3

Lornoxicam gastro retentive floating matrix tablets: Design and in vitro evaluation.  

PubMed

The objective of this present investigation is to prolong the gastric residence time of Lornoxicam by fabricating it into a floating sustained release matrix tablets. Lornoxicam, a potent oxicam group of non-steroidal anti-inflammatory drugs, suffers from relatively short half life of 2 to 3 hrs showing maximal absorption in proximal gastro intestinal tract region necessitating its need to be formulated as a floating sustained release matrix tablets. In this current investigation, hydroxyl propyl methyl cellulose K15M, a high viscous grade polymer with apparent viscosity of 15,000 cps, was kept as a variable (10-50%) and calcium carbonate (13%) was used as a gas generator. The prepared blends were subjected for its pre-formulation characterization. The directly compressed tablets were evaluated for physical parameters such as weight uniformity, hardness, friability, drug content, in-vitro buoyancy with axial and radial enlargement measurement, swelling index. From the investigation it was observed that the buoyancy lasted for up to 24 hrs. Fourier transform infra-red spectroscopy peaks assured the compatibility of the drug with excipients and confirmed the presence of pure drug in the formulation. It was supported by in-vitro dissolution studies; and the dissolution data was subjected to various release kinetic models to understand the mechanism of drug release. PMID:22171312

Sathiyaraj, S; Devi, Ramya D; Hari, Vedha B N

2011-07-01

4

Preparation and evaluation of novel metronidazole sustained release and floating matrix tablets.  

PubMed

In the present study, metronidazole was used for preparing floating dosage forms that are designed to retain in the stomach for a long time and have developed as a drug delivery system for better eradication of Helicobacter Pylori in peptic ulcer diseases. For this means, various formulations were designed using multi-factorial design. HPMC, psyllium and carbopol in different concentrations were used as floating agents, and sodium bicarbonate was added as a gas-forming agent. Hardness, friability, drug loading, floating ability and release profiles as well as kinetics of release were assessed. Formulations containing HPMC as filler showed prolonged lag times for buoyancy. Adding psyllium to these formulations had reduced relative lag times. Overall, selected formulations were able to float immediately and showed buoyancy for at least 8?h. Meanwhile, sustained profiles of drug release were also obtained. Kinetically, among the 10 assessed models, the release pattern of metronidazole from the tablets fitted best to Power law, Weibull and Higuchi models in respect overall to mean percentage error values of 3.8, 4.73 and 5.77, respectively, for calcium carbonate-based tablets and, 2.95, 6.39 and 3.9, respectively, for calcium silicate-based tablets. In general, these systems can float in the gastric condition and control the drug release from the tablets. PMID:20429828

Asnaashari, Solmaz; Khoei, Nazaninossadat Seyed; Zarrintan, Mohammad Hosein; Adibkia, Khosro; Javadzadeh, Yousef

2010-04-30

5

Formulation and evaluation of effervescent floating tablets of tizanidine hydrochloride.  

PubMed

Tizanidine hydrochloride is an orally administered prokinetic agent that facilitates or restores motility through-out the length of the gastrointestinal tract. The objective of the present investigation was to develop effervescent floating matrix tablets of tizanidine hydrochloride for prolongation of gastric residence time in order to overcome its low bioavailability (34-40 %) and short biological half life (4.2 h). Tablets were prepared by the direct compression method, using different viscosity grades of hydroxypropyl methylcellulose (HPMC K4M, K15M and K100M). Tablets were evaluated for various physical parameters and floating properties. Further, tablets were studied for in vitro drug release characteristics in 12 hours. Drug release from effervescent floating matrix tablets was sustained over 12 h with buoyant properties. DSC study revealed that there is no drug excipient interaction. Based on the release kinetics, all formulations best fitted the Higuchi, first-order model and non-Fickian as the mechanism of drug release. Optimized formulation (F9) was selected based on the similarity factor (f2) (74.2), dissolution efficiency at 2, 6 and 8 h, and t50 (5.4 h) and was used in radiographic studies by incorporating BaSO4. In vivo X-ray studies in human volunteers showed that the mean gastric residence time was 6.2 ± 0.2 h. PMID:21684848

Someshwar, Komuravelly; Chithaluru, Kalyani; Ramarao, Tadikonda; Kumar, K K Kalyan

2011-06-01

6

Gastro-floating tablets of cephalexin: preparation and in vitro/in vivo evaluation.  

PubMed

Gastro-floating tablets of cephalexin were developed to prolong the residence time in major absorption sites. Gastro-floating tablets were prepared and optimized using hydroxypropyl methylcellulose (HPMC K100M) as matrix and sodium bicarbonate as a gas-forming agent. The properties of the tablets in terms of floating lag time, floating time and in vitro release were evaluated. Furthermore, in vivo pharmacokinetic study in fed and fasted beagle dogs was performed. The gastro-floating tablets had short floating lag time and exhibited a satisfactory sustained-release profile in vitro. Compared with conventional capsules, the gastro-floating tablets presented a sustained-release behavior with a relative bioavailability of 99.4%, while the reference sustained-release tablets gave a relative bioavailability of only 39.3%. Meanwhile, the food had significant effect on the pharmacokinetics of sustained-release tablets. It was concluded that the gastro-floating tablets had a sustained-release effect in vitro and in vivo, as well as desired pharmacokinetic properties in both fed and fasted conditions. PMID:23680730

Yin, Lifang; Qin, Chao; Chen, Kaisheng; Zhu, Chunli; Cao, Hui; Zhou, Jianping; He, Wei; Zhang, Qiang

2013-05-13

7

Floating tablet of trimetazidine dihydrochloride: an approach for extended release with zero-order kinetics.  

PubMed

Trimetazidine dihydrochloride is an effective anti-anginal agent; however, it is freely soluble in water and suffers from a relatively short half-life. To solve this encumbrance, it is a prospective candidate for fabricating trimetazidine extended-release formulations. Trimetazidine extended-release floating tablets were prepared using different hydrophilic matrix forming polymers including HPMC 4000 cps, carbopol 971P, polycarbophil, and guar gum. The tablets were fabricated by dry coating technique. In vitro evaluation of the prepared tablets was performed by the determination of the hardness, friability, content uniformity, and weight variation. The floating lag time and floating duration were also evaluated. Release profile of the prepared tablets was performed and analyzed. Furthermore, a stability study of the floating tablets was carried out at three different temperatures over 12 weeks. Finally, in vivo bioavailability study was done on human volunteers. All tablet formulas achieved < 0.5 min of floating lag time, more than 12 h of floating duration, and extended t (1/2). The drug release in all formulas followed zero-order kinetics. T4 and T8 tablets contained the least polymer concentration and complied with the dissolution requirements for controlled-release dosage forms. These two formulas were selected for further stability studies. T8 exhibited longer expiration date and was chosen for in vivo studies. T8 floating tablets showed an improvement in the drug bioavailability compared to immediate-release tablets (Vastrel® 20 mg). PMID:20582493

Abdelbary, Ahmed; El-Gazayerly, Omaima N; El-Gendy, Nashwa A; Ali, Adel A

2010-06-26

8

Formulation and evaluation of non-effervescent floating tablets of losartan potassium.  

PubMed

The aim of the work is to modify the solubility and bioavailability of Losartan potassium, by employing noneffervescent floating drug delivery (tablet dosage forms). Non-effervescent systems are a type of floating drug delivery systems, that have been used to boost the gastric residence and the floatation time in the gastro intestinal tract. The study included formulation of floating tablets using polymers like Chitosan and Karaya gum as matrix forming agents. Accurel(®) MP 1000 was used as floating agent. The tablets were prepared by direct compression technique. FTIR, DSC studies conformed that there was no incompatibility between the polymer and the drug. Tablet preformulation parameters were within the Pharmacopoeial limit. Tablet showed zero lag time, contisnuance of buoyancy for >12 h. The tablet showed good in vitro release. Drug release was through swelling and abided by the gellation mechanism. In vivo X-ray studies depicted that tablets continued to float in the GIT for 12 h. Accelerated stability showed that, tablets were stable for over 6 month. Thus the prepared non-effervescent floating tablet of Losartan potassium can be used for the treatment of hypertension for more than 12 h with single dose administration. PMID:23286884

Getyala, Anil; Gangadharappa, H V; Prasad, M Sarat Chandra; Reddy, M Praveen Kumar; Kumar, T M Pramod

2013-10-01

9

Comparative evaluation of single and bilayered lamotrigine floating tablets  

PubMed Central

Aim: The purpose of this study was to prepare lamotrigine (LM) bilayered and single layered floating tablets and to compare their release profiles. Materials and Methods: LM floating tablets were prepared by direct compression method. Drug, hydroxy propyl methyl cellulose K4M, lactose monohydrate and polyvinylpyrrolidone K30 constitute controlled release layer components and floating layer components includes polymers and sodium bicarbonate. The prepared tablets were evaluated for physicochemical parameters such as hardness, friability, weight variation, thickness, floating lag time (FLT), floating time, in vitro buoyancy study, in vitro release studies. The drug-polymer interaction was studied by fourier transform infrared and differential scanning calorimetry. Results and Discussion: The FLT of all the formulations were within the prescribed limits (<3 min). When ethyl cellulose was used as floating layer component, tablets showed good buoyancy effect but eroded within 6-8 h. Hence it was replaced with hydroxypropyl cellulose -M hydrophilic polymer, which showed good FLT and floating duration for 16 h. Formulation LFC4 was found to be optimized with dissolution profile of zero order kinetics showing fickian diffusion. A comparative study of bilayered and single layered tablets of LM showed a highest similarity factor of 83.03, difference factor of 2.74 and t-test (P < 0.05) indicates that there is no significant difference between them. Conclusion: Though bilayered tablet possess many advantages, single layered tablet would be economical, cost-effective and reproducible for large scale production in the industry. However, the results of present study demonstrated that the in vitro development of bilayered gastro retentive floating tablets with controlled drug release profile for LM is feasible.

Lakshmi, PK; Sridhar, M; Shruthi, B

2013-01-01

10

Formulation and evaluation of novel coated floating tablets of bergenin and cetirizine dihydrochloride for gastric delivery.  

PubMed

A novel coated gastric floating drug-delivery system (GFDDS) of bergenin (BN) and cetirizine dihydrochloride (CET) was developed. First, the pharmacodynamic studies were performed and the results revealed that the new compounds of bergenin/cetirizine dihydrochloride had comparative efficacy as commercial products (bergenin/chlorphenamine maleate) but with fewer side effects on central nervous system (CNS). Subsequently, bergenin was formulated as an extended-release core tablet while cetirizine dihydrochloride was incorporated into the gastric coating film for immediate release. The formulation of GFDDS was optimized by CET content uniformity test, in vitro buoyancy and drug release. Herein, the effects of sodium bicarbonate (effervescent), hydroxypropyl methylcellulose (HPMC, matrix polymer) and coating weight gain were investigated respectively. The optimized GFDDS exhibited good floating properties (buoyancy lag time < 2?min; floating duration > 10?h) and satisfactory drug-release profiles (immediate release of CET in 10?min and sustained release of BN for 12?h). In vivo gamma scintigraphy proved that the optimized GFDDS could retain in the stomach with a prolonged gastric retention time (GRT) of 5?h, and the coating layer showed no side effect for gastric retention. The novel coated gastric floating drug-delivery system offers a new approach to enhance BN's absorption at its absorption site and the efficacy of both CET and BN. PMID:22206469

He, Shuang; Li, Feng; Zhou, Dan; Du, Junrong; Huang, Yuan

2011-12-30

11

High speed matrix processors using floating point representation  

SciTech Connect

The author describes the architecture of a high-speed matrix processor which uses a floating-point format for data representation. It is shown how multipliers and other LSI devices are used in the design to obtain the high speed of the processor.

Birkner, D.A.

1980-01-01

12

Development, characterization and permeability assessment based on caco-2 monolayers of self-microemulsifying floating tablets of tetrahydrocurcumin.  

PubMed

Novel self-microemulsifying floating tablets were developed to enhance the dissolution and oral absorption of the poorly water-soluble tetrahydrocurcumin (THC). Their physicochemical properties and THC permeability across Caco-2 cell monolayers were assessed. The self-microemulsifying liquid containing THC was adsorbed onto colloidal silicon dioxide, mixed with HPMC, gas-generating agents (sodium bicarbonate and tartaric acid), lactose and silicified-microcrystalline cellulose and transformed into tablets by direct compression. The use of different types/concentrations of HPMC and sodium bicarbonate in tablet formulations had different effects on the floating characteristics and in vitro THC release. The optimum tablet formulation (F2) provided a short floating lag time (?23 s) together with a prolonged buoyancy (>12 h). About 72% of THC was released in 12 h with an emulsion droplet size in aqueous media of 33.9±1.0 nm while that of a self-microemulsifying liquid was 29.9±0.3 nm. The tablet formulation was stable under intermediate and accelerated storage conditions for up to 6 months. The THC released from the self-microemulsifying liquid and tablet formulations provided an approximately three- to fivefold greater permeability across the Caco-2 cell monolayers than the unformulated THC and indicated an enhanced absorption of THC by the formulations. The self-microemulsifying floating tablet could provide a dosage form with the potential to improve the oral bioavailability of THC and other hydrophobic compounds. PMID:23319299

Sermkaew, Namfa; Wiwattanawongsa, Kamonthip; Ketjinda, Wichan; Wiwattanapatapee, Ruedeekorn

2013-01-15

13

Floating-Point Accumulation Circuit for Matrix Applications  

Microsoft Academic Search

Many scientific algorithms require floating-point reduction operations, or accumulations, including matrix-vector-multiply (MVM), vector dot-products, and the discrete cosine transform (DCT). Because FPGA implementations of each of these algorithms are desirable, it is clear that a high-performance, floatingpoint accumulation unit is necessary. However, this type of circuit is difficult to design in an FPGA environment due to the deep pipelining of

Michael R. Bodnar; John R. Humphrey; Petersen F. Curt; James P. Durbano; Dennis W. Prather

2006-01-01

14

Thermal analysis of gels and matrix tablets containing cellulose ethers  

Microsoft Academic Search

This paper reviews the use of thermal analysis in probing the performance of hydrophilic matrices. Thermomechanical analysis, in isothermal mode, can monitor the rate of gel formation around matrix tablets following their exposure to water; in expansion mode the technique can follow the swelling of matrices exposed to water. DSC can follow the moisture uptake by matrices containing hydrophilic polymers,

James L. Ford; Karen Mitchell

1995-01-01

15

[Hydrophilic gel matrix tablets for oral administration of drugs].  

PubMed

Matrix tablets with a dispersed active ingredient are the simplest concept in the design of dosage forms with modified drug release. If they contain a swelling polymer as an auxiliary substance, the release from these systems, after initial liberation of a portion of the active ingredient from the surface, takes place by diffusion, erosion, or a combination of both mechanisms in dependence on the solubility of the contained active ingredient. Although hydrophilic matrix tablets have become a well-tried and widely used dosage form with retarded effects, their research continues and new auxiliary substances and their combinations are being tested. The present paper reviews the knowledge published in this field in recent years. PMID:14619697

Rabisková, M; Vostalová, L; Medvecká, G; Horácková, D

2003-09-01

16

Development and Evaluation of Hydrophilic Colloid Matrix of Famotidine Tablets  

Microsoft Academic Search

The objective of the present study was to develop a once-daily sustained-release (SR) matrix tablet of famotidine. Nine different\\u000a formulations (F1–F9) were prepared by direct compression method using Avicel PH101 as filler\\/binder in the range of 41–27%\\u000a in F1–F3, 18–22% in F4–F7, and 16–18% in F8–F9 and hydroxypropyl methylcellulose (4,000 cps) as hydrophilic matrix was used\\u000a in F1–F3 from 19% to

Muhammad Harris Shoaib; Saniah Al Sabah Siddiqi; Rabia Ismail Yousuf; Kamran Zaheer; Muhammad Hanif; Saeed Rehana; Sabahat Jabeen

2010-01-01

17

Application of dynamic neural networks in the modeling of drug release from polyethylene oxide matrix tablets  

Microsoft Academic Search

The main objective of this study was to demonstrate the possible use of dynamic neural networks to model diclofenac sodium release from polyethylene oxide hydrophilic matrix tablets. High and low molecular weight polymers in the range of 0.9–5×106 have been used as matrix forming materials and 12 different formulations were prepared for each polymer. Matrix tablets were made by direct

Jelena Petrovi?; Svetlana Ibri?; Gabriele Betz; Jelena Paroj?i?; Zorica ?uri?

2009-01-01

18

Thermal sintering: a novel technique used in the design, optimization and biopharmaceutical evaluation of propranolol HCl gastric floating tablets.  

PubMed

Abstract The objective of the present investigation was to study the applicability of thermal sintering technique for the development of gastric floating tablets of propranolol HCl. Formulations were prepared using four independent variables, namely (i) polymer quantity, (ii) sodium bicarbonate concentration, (iii) sintering temperature and (iv) sintering time. Floating lag time and t(95) were taken as dependent variables. Tablets were prepared by the direct compression method and were evaluated for physicochemical properties, in vitro buoyancy and dissolution studies. From the drug release studies, it was observed that drug retarding property mainly depends upon the sintering temperature and time of exposure. The statistically optimized formulation (PTSso) was characterized by Fourier transform infrared spectroscopy and differential scanning calorimetry studies, and no significant chemical interaction between drug and polymer was observed. Optimized formulation was stable at accelerated conditions for a period of six months. PTSso was evaluated for in vivo buoyancy studies in humans for both fed and fasted states and found that gastric residence time of the floating tablets were enhanced by fed stage but not in fasted state. Optimized formulation PTSso and commercial formulation Ciplar LA 80 were subjected to bioavailability studies in healthy human volunteers by estimating pharmacokinetic parameters such as C(max), T(max), area under curve (AUC)(,) elimination rate constant (K(el)), biological half-life (t(1/2)) and mean residence time (MRT). There was a significant increase in the bioavailability of the propranolol HCl from PTSso formulation, which was evident from increased AUC levels and larger MRT values than Ciplar LA 80. PMID:23317339

Venkata Srikanth, Meka; Songa, Ambedkar Sunil; Nali, Sreenivasa Rao; Battu, Janaki Ram; Kolapalli, Venkata Ramana Murthy

2013-01-15

19

Development and evaluation of hydrophilic colloid matrix of famotidine tablets.  

PubMed

The objective of the present study was to develop a once-daily sustained-release (SR) matrix tablet of famotidine. Nine different formulations (F1-F9) were prepared by direct compression method using Avicel PH101 as filler/binder in the range of 41-27% in F1-F3, 18-22% in F4-F7, and 16-18% in F8-F9 and hydroxypropyl methylcellulose (4,000 cps) as hydrophilic matrix was used in F1-F3 from 19% to 30%, around 40% in F4-F7, and 42-45% in F8-F9. Talc and Aerosil were added in the ratio of 0.7-1.2%. The tablets were subjected to various physical parameters including weight variation test, hardness, thickness, diameter, friability, and in vitro release studies. Assay was also performed according to the USP 30 NF 25 procedure. The results of the physical parameters and assay were found to be within the acceptable range. In vitro dissolution results indicated that formulation F4-F7, having around 40% of rate control polymer, produced a SR pattern throughout 24 h. F1-F3 showed drug release at a faster rate, while F8-F9 released much slower, i.e., <80% in 24 h. Model-dependent and model-independent methods were used for data analysis and the best results were observed for F4 in zero order (r(2) = 0.984) and F6 in Korsmeyer and Higuchi (r(2) = 0.992 and 0.988). The parameter n indicated anomalous diffusion, while beta in Weibull showed a parabolic curve with higher initial slope. The f(2) similarity test was performed taking F4 as a reference formulation. Only the F5-F7 formulations were similar to the reference formulation F4. The mean dissolution time was around 10 h for the successful formulation. PMID:20422332

Shoaib, Muhammad Harris; Al Sabah Siddiqi, Saniah; Yousuf, Rabia Ismail; Zaheer, Kamran; Hanif, Muhammad; Rehana, Saeed; Jabeen, Sabahat

2010-04-27

20

Programmable drug release of highly water-soluble pentoxifylline from dry-coated wax matrix tablets.  

PubMed

The programmable release of pentoxifylline from a dry-coated wax matrix tablet containing behenic acid as wax matrix was investigated at 37 degrees C in Japanese Pharmacopeia XII 1st (pH 1.2) and 2nd (pH 6.8) fluids. The dry-coated tablet consisted of a low drug concentration (33% w/w) in the outer layer tablet and a high concentration (50-67% w/w) in the core. The drug release from the wax matrix significantly increased after penetrating the core; therefore, the drug release profiles showed specific biphasic curves. Because the contact angle of the wax matrix tablet increased with a decrease in the drug concentration, the fluid penetration in wax matrix tablet increased with an increase of the drug concentration. The time required for 75% drug release (T75) decreased with an increasing drug concentration in the core, and the T75 at pH 6.8 was slightly longer than that in pH 1.2. The larger core tablet had a shorter T75, indicating that the drug release rate was controlled by regulating the drug concentration and/or the weight of the core tablet. PMID:7629734

Otsuka, M; Matsuda, Y

1995-04-01

21

Formulation, Release Characteristics and Bioavailability Study of Oral Monolithic Matrix Tablets Containing Carbamazepine  

PubMed Central

This study examined the release of carbamazepine (CBZ) from hydrophobic (Compritol® 888 ATO) and hydrophilic-hydrophobic matrix combination (Compritol® 888 ATO-hydroxpropyl methylcellulose, HPMC). Hydrophobic matrix tablets were prepared by hot fusion technique, while hydrophilic-hydrophobic matrix tablets were prepared by wet granulation technique. The properties of the compressed matrix tablets were determined according to the US Pharmacopoeia. Both matrix formulations displayed a controlled-release profile when compared to the reference formulation (Tegretol® CR 200). The bioavailability of CBZ formulations and Tegretol® CR 200 were evaluated in beagle dogs. Carbamazepine presented a significant higher bioavailability from matrix tablets containing hydrophilic polymer (HPMC) than that obtained from Tegretol® CR200. The average inter-subject plasma concentration variability CV% was the least with tablet containing hydrophilic polymer (HPMC) and was the highest with Tegretol® CR 200 (33.8 and 54.1, respectively). Analysis of variance applied to log \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\text{AUC}}_{0 - \\alpha } $$\\end{document} and log C max showed statistical significant differences among the three formulations (P?matrix tablets examined.

Elbagory, Ibrahim M.; Almurshedi, Alanood S.

2008-01-01

22

Once-daily sustained-release matrix tablets of nicorandil: Formulation and in vitro evaluation  

Microsoft Academic Search

The objective of the present study was to develop once-daily sustained-release matrix tablets of nicorandil, a novel potassium\\u000a channel opener used in cardiovascular diseases. The tablets were prepared by the wet granulation method. Ethanolic solutions\\u000a of ethylcellulose (EC), Eudragit RL-100, Eudragit RS-100, and polyvinylpyrrolidone were used as granulating agents along with\\u000a hydrophilic matrix materials like hydroxypropyl methylcellulose (HPMC), sodium carboxymethylcellulose,

K. Raghuram Reddy; Srinivas Mutalik; Srinivas Reddy

2003-01-01

23

Adverse effects of iron supplementation: a comparative trial of a wax-matrix iron preparation and conventional ferrous sulfate tablets.  

PubMed

The acceptability of supplemental iron delivered from a wax-matrix tablet of ferrous sulfate was compared with that of a conventional ferrous sulfate tablet in a single-blind, parallel-group study. Both tablets were formulated to deliver 50 mg of elemental iron. The incidence of adverse effects was found to be significantly greater among 272 subjects taking the conventional tablets than among 271 subjects taking the wax-matrix preparation. Eighty-one percent of the subjects taking the wax-matrix preparation experienced no severe or moderate side effects as compared with only 50% of those taking the conventional tablets. PMID:4053146

Brock, C; Curry, H; Hanna, C; Knipfer, M; Taylor, L

1985-01-01

24

A Design and Evaluation of Layered Matrix Tablet Formulations of Metoprolol Tartrate  

PubMed Central

The aim of this paper was to evaluate the performance of different swellable polymers in the form of layered matrix tablets to provide controlled therapeutic effect of metoprolol tartrate for twice daily administration. Seven different swellable polymers (carrageenan, hydroxypropylmethyl cellulose, pectin, guar gum, xanthan gum, chitosan, and ethyl cellulose) were evaluated alone or in combination as release-retardant layer. Tablets were tested for weight variation, hardness, diameter/thickness ratio, friability, and drug content uniformity and subjected to in vitro drug-release studies. In addition, the target-release profile of metoprolol tartrate was plotted using its clinical pharmacokinetic data, and the release profiles of the tablets were evaluated in relation to the plotted target release profile. Carrageenan was determined as the best polymer in two-layered matrix tablet formulations due to its better accordance to the target release profile and was selected for preparing three-layered matrix tablets. Carrageenan formulations exhibited super case II release mechanism. Accelerated stability testing was performed on two- and three-layered matrix tablet formulations of carrageenan. The tablets were stored at 25°C/60% relative humidity and 40°C/75% relative humidity for 6 months and examined for physical appearance, drug content, and release characteristics. At the end of the storage time, formulations showed no change either in physical appearance, drug content, or drug-release profile. These results demonstrated the suitability of three-layered tablet formulation of carrageenan to provide controlled release and improved linearity for metoprolol tartrate in comparison to two-layered tablet formulation.

Senyigit, Taner

2010-01-01

25

EXPANDED STARCH AS A FLOATING DOSAGE MATRIX FOR THE CONTROLLED RELEASE OF MODEL DRUG COMPOUNDS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Starch-based materials were tested using model drug compounds to determine the feasibility of using starch as an oral floating dosage matrix. Oral controlled release systems require increased bio-availability, predictable release rates, and site-specific delivery. Starch and model drugs were compo...

26

In vitro Release Kinetics Study of Diltiazem Hydrochloride from Wax and Kollidon SR Based Matrix Tablets  

Microsoft Academic Search

Extended-release matrix tablets of diltiazem hydrochloride (DTZ) were prepared using waxy materials alone or in combination with Kollidon SR. Matrix waxy materials were carnauba wax (CW), bees wax (BW), cetyl alcohol (CA) and glyceryl monostearate (GMS). Dissolution studies were carried out by using a six stations USP XXII type 1 apparatus. The in vitro drug release study was done in

Mohammad Safiqul Islam; Selim Reza; Habibur Rahman

2008-01-01

27

Optimization of bilayer floating tablet containing metoprolol tartrate as a model drug for gastric retention.  

PubMed

The purpose of the present study was to develop an optimized gastric floating drug delivery system (GFDDS) containing metoprolol tartrate (MT) as a model drug by the optimization technique. A 2(3) factorial design was employed in formulating the GFDDS with total polymer content-to-drug ratio (X1), polymer-to-polymer ratio (X2), and different viscosity grades of hydroxypropyl methyl cellulose (HPMC) (X3) as independent variables. Four dependent variables were considered: percentage of MT release at 8 hours, T50%, diffusion coefficient, and floating time. The main effect and interaction terms were quantitatively evaluated using a mathematical model. The results indicate that X1 and X2 significantly affected the floating time and release properties, but the effect of different viscosity grades of HPMC (K4M and K10M) was nonsignificant. Regression analysis and numerical optimization were performed to identify the best formulation. Fickian release transport was confirmed as the release mechanism from the optimized formulation. The predicted values agreed well with the experimental values, and the results demonstrate the feasibility of the model in the development of GFDDS. PMID:16796352

Narendra, C; Srinath, M S; Babu, Ganesh

2006-04-07

28

Modulation of Venlafaxine Hydrochloride Release from Press Coated Matrix Tablet  

PubMed Central

The aim of present study was to prepare novel modified release press coated tablets of venlafaxine hydrochloride. Hydroxypropylmethylcellulose K4M and hydroxypropylmethylcellulose K100M were used as release modifier in core and coat, respectively. A 32 full factorial design was adopted in the optimization study. The drug to polymer ratio in core and coat were chosen as independent variables. The drug release in the first hour and drug release rate between 1 and 12 h were chosen as dependent variables. The tablets were characterized for dimension analysis, crushing strength, friability and in vitro drug release. A check point batch, containing 1:2.6 and 1:5.4 drug to polymer in core and coat respectively, was prepared. The tablets of check point batch were subjected to in vitro drug release in dissolution media with pH 5, 7.2 and distilled water. The kinetics of drug release was best explained by Korsmeyer and Peppas model (anomalous non-Fickian diffusion). The systematic formulation approach enabled us to develop modified release venlafaxine hydrochloride tablets.

Gohel, M. C.; Soni, C. D.; Nagori, S. A.; Sarvaiya, K. G.

2008-01-01

29

Effect of processing and sintering on controlled release wax matrix tablets of ketorolac tromethamine.  

PubMed

The objective of present study was to evaluate the effect of processing methods and sintering condition on matrix formation and subsequent drug release from wax matrix tablets for controlled release. Ketorolac tromethamine and compritol were processed with appropriate diluent using either dry blending, spray drying, partial melt granulation or melt granulation.The tablets were then sintered at 80 degrees . The sintered tablets were characterized by their physical parameters and in vitro dissolution tests. The micro-morphology and wettability of the tablets was also investigated. It was evident that different processing methods for identical formulation significant impact the release profile of drug. Sintering further retarded drug release and its effect was related to the manufacturing processes. Scanning electron microscopy showed that heat treatment redistributed the wax and formed a film-like structure covering drug and excipient particle. The contact angle of tablets made by dry blending, spray drying and partial melt granulation methods increased after sintering, while that of tablets made by melt granulation remained constant. Drug release from the wax tablets with or without heat treatment was best described by the Higuchi equation. Different processing methods produced different matrix structures that resulted in different drug release rates. Sintering retarded drug release mainly by decreasing the porosity of the matrix. Contact angle measurement and SEM analysis indicated that heat treatment caused the wax to melt, redistribute, coat the drug and diluents and form a network structure. Differential scanning calorimetry studies ruled out the occurrence of solid solution of the drug during sintering condition. PMID:20502573

Rao, Monica R P; Ranpise, Anuradha A; Thanki, K C; Borate, S G; Parikh, G N

2009-09-01

30

Controlled-Release Carbamazepine Matrix Granules and Tablets Comprising Lipophilic and Hydrophilic Components  

PubMed Central

The objective of this study was to investigate the effect of lipophilic (Compritol® 888 ATO) and hydrophilic components (combination of HPMC and Avicel) on the release of carbamazepine from granules and corresponding tablet. Wet granulation followed by compression was employed for preparation of granules and tablets. The matrix swelling behavior was investigated. The dissolution profiles of each formulation were compared to those of Tegretol® CR tablets and the mean dissolution time (MDT), dissolution efficiency (DE%), and similarity factor (f2 factor) were calculated. It was found that increase in the concentration of HPMC results in reduction in the release rate from granules and achievement of zero-order is difficult from the granules. The amount of HPMC plays a dominant role for the drug release. The release mechanism of CBZ from matrix tablet formulations follows non-Fickian diffusion shifting to Case II by the increase of HPMC content, indicating significant contribution of erosion. Increasing in drug loading resulted in acceleration of the drug release and in anomalous controlled-release mechanism due to delayed hydration of the tablets. These results suggest that wet granulation followed by compression could be a suitable method to formulate sustained release CBZ tablets.

Barakat, Nahla S.; Elbagory, Ibrahim M.; Almurshedi, Alanood S.

2009-01-01

31

Controlled-Release Carbamazepine Granules and Tablets Comprising Lipophilic and Hydrophilic Matrix Components  

PubMed Central

The objective of this study was to investigate the effect of lipophilic (Compritol® 888 ATO) and hydrophilic components (combination of HPMC and Avicel) on the release of carbamazepine from granules and corresponding tablet. Wet granulation followed by compression was employed for preparation of granules and tablets. The matrix swelling behavior was investigated. The dissolution profiles of each formulation were compared to those of Tegretol® CR tablets and the mean dissolution time (MDT), dissolution efficiency (DE %) and similarity factor (f2 factor) were calculated. It was found that increase in the concentration of HPMC results in reduction in the release rate from granules and achievement of zero-order is difficult from the granules. The amount of HPMC plays a dominant role for the drug release. The release mechanism of CBZ from matrix tablet formulations follows non-Fickian diffusion shifting to case II by the increase of HPMC content, indicating significant contribution of erosion. Increasing in drug loading resulted in acceleration of the drug release and in anomalous controlled-release mechanism due to delayed hydration of the tablets. These results suggest that wet granulation followed by compression could be a suitable method to formulate sustained release CBZ tablets.

Elbagory, Ibrahim M.; Almurshedi, Alanood S.

2008-01-01

32

The Role of Oral Controlled Release Matrix Tablets in Drug Delivery Systems  

PubMed Central

Formulations that are able to control the release of drug have become an integral part of the pharmaceutical industry. In particular oral drug delivery has been the focus of pharmaceutical research for many years. This type of drug delivery has been at the centre of research due to its many benefits over conventional dosage. The focus of this review is on matrix tablets due to their widely use and simplicity of the formulation. This includes the discussion of various types of matrix tablets and factors affecting the drug release from these formulations. The mechanism of drug release from HPMC matrices is also discussed.

Nokhodchi, Ali; Raja, Shaista; Patel, Pryia; Asare-Addo, Kofi

2012-01-01

33

Development of extended release divalproex sodium tablets containing hypdrophobic and hydrophilic matrix.  

PubMed

Bilayered tablets of Divalproex sodium for once-a-day administration were prepared using a hydrophilic and hydrophobic polymer as release retarding agents. This technology was found to be more effective than a simple matrix tablet with a mixture of the above polymers in order to retard the drug release for a period of 24 h. The drug release profile was strongly dependent on the presence of wicking agent, pathlength of hydrophobic layer, and hardness of tablet. f(1) value of 6.92 and f(2) value of 76.72 indicated similarity between the release profiles of batch BT3 and reference tablet (Depakote((R)) ER) with the target release of over 55% within 12 h and over 85% within 18 h. Mathematical modeling using Korsmeyer-Peppas equation indicated that the release followed a combination of diffusion and erosion mechanism. PMID:19604143

Chakraborty, S; Pandit, J K; Srinatha, A

2009-07-01

34

FORMULATION AND IN-VITRO EVALUATION OF DEXTRIN MATRIX TABLET OF IBUPROFEN FOR COLON SPECIFIC DRUG DELIVERY  

Microsoft Academic Search

The objective of the present study is to develop colon targeted drug delivery system by using dextrin (polysaccharide) as a carrier for ibuprofen. Matrix tablets containing various excipients and dextrin were prepared by wet granulation technique using different binder systems. The matrix tablets were evaluated by different IPQC tests, content uniformity and in vitro drug release study. Drug release profile

KISHOR SAHEBRAO SALUNKHE; MOHAN VINAYAK KULKARNI

35

Design and Development of Polyethylene Oxide Based Matrix Tablets for Verapamil Hydrochloride  

PubMed Central

In the present investigation an attempt has been made to increase therapeutic efficacy, reduced frequency of administration and improved patient compliance by developing controlled release matrix tablets of verapamil hydrochloride. Verapamil hydrochloride was formulated as oral controlled release matrix tablets by using the polyethylene oxides (Polyox WSR 303). The aim of this study was to investigate the influence of polymer level and type of fillers namely lactose (soluble filler), swellable filler (starch 1500), microcrystalline cellulose and dibasic calcium phosphate (insoluble fillers) on the release rate and mechanism of release for verapamil hydrochloride from matrix tablets prepared by direct compression process. Higher polymeric content in the matrix decreased the release rate of drug. On the other hand, replacement of lactose with anhydrous dibasic calcium phosphate and microcrystalline cellulose has significantly retarded the release rate of verapamil hydrochloride. Biopharmaceutical evaluation of satisfactory formulations were also carried out on New Zealand rabbits and parameters such as maximum plasma concentration, time to reach peak plasma concentration, area under the plasma concentration time curve(0-t) and area under first moment curve(0-t) were determined. In vivo pharmacokinetic study proves that the verapamil hydrochloride from matrix tablets showed prolonged release and were be able to sustain the therapeutic effect up to 24 h.

Vidyadhara, S.; Sasidhar, R. L. C.; Nagaraju, R.

2013-01-01

36

Design and development of polyethylene oxide based matrix tablets for verapamil hydrochloride.  

PubMed

In the present investigation an attempt has been made to increase therapeutic efficacy, reduced frequency of administration and improved patient compliance by developing controlled release matrix tablets of verapamil hydrochloride. Verapamil hydrochloride was formulated as oral controlled release matrix tablets by using the polyethylene oxides (Polyox WSR 303). The aim of this study was to investigate the influence of polymer level and type of fillers namely lactose (soluble filler), swellable filler (starch 1500), microcrystalline cellulose and dibasic calcium phosphate (insoluble fillers) on the release rate and mechanism of release for verapamil hydrochloride from matrix tablets prepared by direct compression process. Higher polymeric content in the matrix decreased the release rate of drug. On the other hand, replacement of lactose with anhydrous dibasic calcium phosphate and microcrystalline cellulose has significantly retarded the release rate of verapamil hydrochloride. Biopharmaceutical evaluation of satisfactory formulations were also carried out on New Zealand rabbits and parameters such as maximum plasma concentration, time to reach peak plasma concentration, area under the plasma concentration time curve(0-t) and area under first moment curve(0-t) were determined. In vivo pharmacokinetic study proves that the verapamil hydrochloride from matrix tablets showed prolonged release and were be able to sustain the therapeutic effect up to 24 h. PMID:24019567

Vidyadhara, S; Sasidhar, R L C; Nagaraju, R

2013-03-01

37

Formulation and in-vitro evaluation of dextrin matrix tablet of Ibuprofen for colon specific drug delivery.  

PubMed

The objective of the present study is to develop colon targeted drug delivery system by using dextrin (polysaccharide) as a carrier for ibuprofen. Matrix tablets containing various excipients and dextrin were prepared by wet granulation technique using different binder systems. The matrix tablets were evaluated by different IPQC tests, content uniformity and in vitro drug release study. Drug release profile was evaluated in simulated gastric, intestinal fluid and simulated colonic fluid. Best formulation was decided on the basis drug release profile in simulated gastric and intestinal fluid. The matrix tablet containing dextrin as a carrier and ethyl cellulose as binder was found to be suitable for targeting ibuprofen for local action in the colon as compare to other matrix tablets containing different binders because of fewer amounts (8-11%) of drug release in the simulated gastric and intestinal fluid. Matrix tablets containing dextrin released 95-98% of ibuprofen in simulated colonic fluid with 4% human fecal matter solution. Tablets containing dextrin showed no change in physical appearance and dissolution profile upon storage at 40 degrees C/75% relative humidity for three months. The results of in-vitro study indicate that matrix tablets containing dextrin as carrier and ethyl cellulose as binder are most suitable to deliver the drug specifically in colonic region as compare to matrix tablets of dextrin with other binder systems. PMID:18166513

Salunkhe, Kishor Sahebrao; Kulkarni, Mohan Vinayak

2008-01-01

38

Formulation and development of matrix tablets of tramadol using katira gum as release modifier.  

PubMed

The present study was aimed to study the drug release retardant property of katira gum in matrix tablets containing tramadol as a model drug. Katira gum was characterized in terms of pH, viscosity and swelling index. The tablets were evaluated for various physical tests viz. hardness, friability, tensile strength and drug content. In vitro dissolution studies were performed and different empirical models were applied to drug release data for evaluating the drug release mechanisms and kinetics. Owing to good swelling properties (swelling index 340% and 480% after 6 and 24 h hydration) of the gum, the n values (as computed from Korsmeyer-Peppas model) were found to be ranging between 0.453 to 0.710 indicating involvement of both polymeric hydration and relaxation in the diffusion of drug from the matrix tablet. PMID:20823680

Singh, Inderbir; Kumar, Pradeep; Kumar, Sanjeev; Rana, Vikas

2010-09-01

39

Colonic luminal surface retention of meloxicam microsponges delivered by erosion based colon-targeted matrix tablet.  

PubMed

The work was aimed at developing calcium-pectinate matrix tablet for colon-targeted delivery of meloxicam (MLX) microsponges. Modified quassi-emulsion solvent diffusion method was used to formulate microsponges (MS), based on 3(2) full factorial design. The effects of volume of dichloromethane and EudragitRS100 content (independent variables) were determined on the particle size, entrapment efficiency and %cumulative drug release of MS1-MS9. The optimized formulation, MS5 (d(mean)=44.47 ?m, %EE=98.73, %CDR=97.32 and followed zero order release) was developed into colon-targeted matrix tablet using calcium pectinate as the matrix. The optimized colon-targeted tablet (MS5T2) shielded MLX loaded microsponges in gastrointestinal region and selectively delivered them to colon, as vizualized by vivo fluoroscopy in rabbits. The pharmacokinetic evaluation of MS5T2 in rabbits, revealed appearance of drug appeared in plasma after a lag time of 7h; a t(max) of 30 h with Fr=61.047%, thus presenting a formulation suitable for targeted colonic delivery. CLSM studies provided an evidence for colonic luminal retentive ability of microsponges at the end of 8h upon oral administration of MS5T2. Thus calcium pectinate matrix tablet loaded with MLX microsponges was developed as a promising system for the colon-specific delivery that has potential for use as an adjuvant therapy for colorectal cancer. PMID:22306039

Srivastava, Rishabh; Kumar, Deepesh; Pathak, Kamla

2012-01-24

40

Gamma scintigraphy in the analysis of ketoprofen behaviour from matrix tablets.  

PubMed

The aim of this work was to study in vitro and in vivo the behaviour of matrix tablets (quick and extended release) containing ketoprofen (KTP) as a model drug and cellulose ether polymers, using gamma scintigraphy. The matrix tablets were prepared by the direct compression method and labelled by incorporating a drop of technetium ((99m)Tc). It was spectrophotometricaly confirmed that the radioisotope inclusion did not modify the kinetics of KTP release. In vitro studies were carried out for the tablets using the paddle method of the USP 35/NF30. The images were processed by defining regions of interest over the tablet (99m)Tc and the percentage of remaining activity/time curves were generated for both formulations. In vitro gamma scintigraphy studies showed significant differences (p<0.05) between both formulations. Identical results were obtained from the in vivo studies. In vivo tests were performed on five healthy volunteers. The scintigraphy images were acquired during 2.5 and 7.5h for quick and extended release formulations, respectively. The position of the extended release formulation tablet along the gastrointestinal tract (GIT) was assessed. The described results demonstrate the in vitro/in vivo correlation for the drug release profile and exhibit the importance of gamma scintigraphy for the drug location through the GIT. PMID:23541984

Vueba, M L; Rodrigues, A; Lourenço, P; Batista de Carvalho, L A E; Veiga, F; Sousa, J J; Pina, M E

2013-03-28

41

Design of Controlled Release Non-erodible Polymeric Matrix Tablet Using Microwave Oven-assisted Sintering Technique  

PubMed Central

The objective of the present study was to evaluate the effect of sintering condition on matrix formation and subsequent drug release from polymer matrix tablet for controlled release. The present study highlights the use of a microwave oven for the sintering process in order to achieve more uniform heat distribution with reduction in time required for sintering. We could achieve effective sintering within 8 min which is very less compared to conventional hot air oven sintering. The tablets containing the drug (propranolol hydrochloride) and sintering polymer (eudragit S-100) were prepared and kept in a microwave oven at 540 watt, 720 watt and 900 watt power for different time periods for sintering. The sintered tablets were evaluated for various tablet characteristics including dissolution study. Tablets sintered at 900 watt power for 8 min gave better dissolution profile compared to others. We conclude that microwave oven sintering is better than conventional hot air oven sintering process in preparation of controlled release tablets.

Patel, DM; Patel, BK; Patel, HA; Patel, CN

2011-01-01

42

Effect of two hydrophobic polymers on the release of gliclazide from their matrix tablets.  

PubMed

Gliclazide is an oral hypoglycemic agent, indicated in non insulin dependent diabetes mellitus and in patients with diabetic retinopathy. It has good tolerability and is a short acting sulfonyl urea that requires large dose to maintain the blood glucose level. So development of a sustained release formulation of gliclazide (GLZ) is required for better patient compliance. This study was conducted to assess the effects of different drug polymer ratios on the release profile of gliclazide from the matrix. Oral matrix tablets of gliclazide were prepared by hot melt method, using pure and blended mixture of glyceryl monostearate (GMS) and stearic acid (SA) in different ratios. In vitro release pattern was studied for 8 h in phosphate buffer media (pH 7.4). Different kinetic models including zero order, first order, Higuchi and Peppas were applied to evaluate drug release behavior. Drug excipient compatibility was evaluated by scanning with DSC and FTIR. Higuchi model was found the most appropriate model for describing the release profile of GLZ and non-Fickian release was found predominant mechanism of drug release. The release of drug from the matrix was greatly controlled by GMS while SA appeared to facilitate the release of drug from matrix tablets. FTIR results showed no chemical interaction between drug and the polymers, and DSC results indicated amorphous state of GLZ and polymers without significant complex formation. The results indicate that matrix tablets of gliclazide using glyceryl monostearate and stearic acid showed marked sustained release properties. PMID:23923399

Hussain, Talib; Saeed, Tariq; Mumtaz, Ahmad M; Javaid, Zeeshan; Abbas, Khizar; Awais, Azeema; Idrees, Hafiz Arfat

43

Matrix mini-tablets based on starch/microcrystalline wax mixtures.  

PubMed

Matrix mini-tablets based on a combination of microcrystalline waxes and starch derivatives were prepared using ibuprofen as a model drug. The production of mini-tablets was preferred over the production of pellets, as up-scaling of the pelletisation process seemed problematic. Prior to tabletting, melt granulation in a hot stage screw extruder and milling were required. The in vitro drug release was varied using microcrystalline waxes with a different melting range, the slowest drug release being obtained with a formulation containing a microcrystalline wax with a melting range between 68 and 72 degrees C. Generally speaking increasing the wax concentration resulted in a slower drug release. In vitro drug release profiles were also modified using different starches and mixtures of starches. Increasing the ibuprofen concentration to 70% resulted in a faster drug release rate. PMID:10802413

De Brabander, C; Vervaet, C; Fiermans, L; Remon, J P

2000-04-20

44

Modulation of drug release kinetics of shellac-based matrix tablets by in-situ polymerization through annealing process.  

PubMed

A new oral-controlled release matrix tablet based on shellac polymer was designed and developed, using metronidazole (MZ) as a model drug. The shellac-based matrix tablets were prepared by wet granulation using different amounts of shellac and lactose. The effect of annealing temperature and pH of medium on drug release from matrix tablets was investigated. The increased amount of shellac and increased annealing temperature significantly affected the physical properties (i.e., tablet hardness and tablet disintegration) and MZ release from the matrix tablets. The in-situ polymerization played a major role on the changes in shellac properties during annealing process. Though the shellac did not dissolve in acid medium, the MZ release in 0.1N HCl was faster than in pH 7.3 buffer, resulting from a higher solubility of MZ in acid medium. The modulation of MZ release kinetics from shellac-based matrix tablets could be accomplished by varying the amount of shellac or annealing temperature. The release kinetics was shifted from relaxation-controlled release to diffusion-controlled release when the amount of shellac or the annealing temperature was increased. PMID:18362064

Limmatvapirat, Sontaya; Limmatvapirat, Chutima; Puttipipatkhachorn, Satit; Nunthanid, Jurairat; Luangtana-anan, Manee; Sriamornsak, Pornsak

2008-02-05

45

Effect of cogrinding time on the release of pentoxifylline from waxy matrix tablets.  

PubMed

The release of pentoxifylline from matrix tablets containing palmitic or behenic acids, as waxes, and prepared via cogrinding was investigated. X-ray powder diffraction analysis of the ground drug-wax indicated that particle size could be reduced by grinding without polymorphic transformation. After the coground mixed powder was compressed at 1000 kg/cm2, the drug-release rate from the tablet was evaluated in pH 6.8 buffer at 37 degrees C. The drug-release profiles could be fitted to the Cobby model. The release rate decreased with an increased grinding time and increased significantly with an increased proportion of the drug. The drug-release rate constant from the matrix was calculated using the Cobby equation and the drug-release profiles. Scanning electron microphotographs of the coground product after dissolution tests suggested that mechanochemical energy had been used to cover the drug particles. PMID:7965674

Otsuka, M; Matsuda, Y

1994-07-01

46

Design and evaluation of matrix-based controlled release tablets of diclofenac sodium and chondroitin sulphate  

Microsoft Academic Search

The purpose of the present study was to develop and characterize an oral controlled release drug delivery system for concomitant\\u000a administration of diclofenac sodium (DS) and chondroitin sulfate (CS). A hydrophilic matrix-based tablet using different concentrations\\u000a of hydroxypropylmethylcellulose (HPMC) was developed using wet granulation technique to contain 100 mg of DS and 400 mg of\\u000a CS. Formulations prepared were evaluated

Amelia Avachat; Vikram Kotwal

2007-01-01

47

Influence of ?-cyclodextrin complexation on carbamazepine release from hydroxypropyl methylcellulose matrix tablets  

Microsoft Academic Search

The in vitro release profiles of carbamazepine and ?-cyclodextrin either complexed or simply mixed and subsequently incorporated in hydrophilic matrix tablets containing 15 or 30% hydroxypropyl methylcellulose were evaluated. Solubility studies revealed a linear relationship between the increase in carbamazepine solubility and the increase in ?-cyclodextrin concentration. Drying methods (spray-drying and freeze-drying) were used to obtain carbamazepine\\/?-cyclodextrin solid complexes in

Let??cia S Koester; Clarissa R Xavier; Paulo Mayorga; Valquiria L Bassani

2003-01-01

48

Comparative release profile of sustained release matrix tablets of verapamil HCl  

PubMed Central

Introduction: Verapamil hydrochloride (VH) is a calcium channel blocking agent used in the treatment of hypertension, cardiac arrhythmia and angina pectoris. The short half-life and high frequency of administration of VH makes it a suitable candidate for designing sustained drug delivery system. The aim of the present investigation was to develop a sustained release matrix tablet of verapamil hydrochloride (VH) using ethyl cellulose, methyl cellulose, Eudragit RS 100, hydroxypropyl methylcellulose and carboxymethyl cellulose and to evaluate the drug release kinetics. Materials and Methods: In order to achieve the required sustained release profile, the tablets were prepared by a wet granulation method using avicel PH 101 and magnesium stearate as binder and lubricant, respectively. Results: The formulated tablets were characterized for pre-compression and post-compression parameters and they were in the acceptable limits. The drug release data obtained after an in vitro dissolution study was fitted to various release kinetic models in order to evaluate the release mechanism and kinetics. The criterion for selecting the best fit model was linearity (coefficient of correlation). Drug release mechanism was found to follow a complex mixture of diffusion, swelling and erosion. Furthermore, to minimize the initial burst drug release, batches were coated by using Eudragit RS100 polymer. After coating the tablets, a better release profile of the formulated tablets was expected and the release rate of the drug was compared with the marketed SR tablet of VH. Conclusion: The dosage form holds the potential to control the release rate of drug and extend the duration of action of a drug.

Mathur, Vikas; Nagpal, Kalpana; Singh, Shailendra Kumar; Mishra, Dina Nath

2013-01-01

49

Three-layer guar gum matrix tablet formulations for oral controlled delivery of highly soluble trimetazidine dihydrochloride  

Microsoft Academic Search

The present study is carried out to design oral controlled drug delivery systems for highly water-soluble drugs using guar gum as a carrier in the form of three-layer matrix tablets. Trimetazidine dihydrochloride was chosen as a model drug because of its high water solubility. Matrix tablet granules containing 30% (M1), 40% (M2) or 50% (M3) of guar gum were prepared

Y. S. R. Krishnaiah; R. S. Karthikeyan; V. Gouri Sankar; V. Satyanarayana

2002-01-01

50

Formulation and in vitro, in vivo evaluation of extended- release matrix tablet of Zidovudine: Influence of combination of hydrophilic and hydrophobic matrix formers  

Microsoft Academic Search

The aim of the present study was to prepare and characterize extended-release matrix tablets of zidovudine using hydrophilic\\u000a Eudragit RLPO and RSPO alone or their combination with hydrophobic ethyl cellulose. Release kinetics was evaluated by using\\u000a United States Pharmacopeia (USP)-22 type I dissolution apparatus. Scanning electron microscopy was used to visualize the effect of dissolution medium on matrix\\u000a tablet surface.

Atul Kuksal; Ashok K. Tiwary; Narendra K. Jain; Subheet Jain

2006-01-01

51

Release from or through a wax matrix system. VI. Analysis and prediction of the entire release process of the wax matrix tablet.  

PubMed

Analysis of the entire release process of the wax matrix tablet was examined. Wax matrix tablet was prepared from a physical mixture of drug and wax powder to obtain basic or clear release properties. The release process began to deviate from Higuchi equation when the released amount reached at around the half of the initial drug amount. Simulated release amount increase infinitely when the Higuchi equation was applied. Then, the Higuchi equation was modified to estimate the release process of the wax matrix tablet. The modified Higuchi equation was named as the H-my equation. Release process was well treated by the H-my equation. Release process simulated by the H-my equation fitted well with the measured entire release process. Also, release properties from and through wax matrix well coincident each other. Furthermore, it is possible to predict an optional release process when the amount of matrix and composition of matrix system were defined. PMID:16079519

Yonezawa, Yorinobu; Ishida, Sumio; Sunada, Hisakazu

2005-08-01

52

Formulation and Evaluation of Hydroxypropyl Methylcellulose-based Controlled Release Matrix Tablets for Theophylline  

PubMed Central

The objectives of the study were to formulate hydroxypropyl methyl cellulose-based controlled release matrix tablets for theophylline with varying drug:polymer ratios (1:1 and 1:2) and differing tablet hardness (5, 6 and 7 kg/cm2), and to evaluate the tablet's physico-chemical properties such as hardness, uniformity of weight, friability, drug content and in vitro drug release. Initially, granules were made by wet granulation technique and evaluated for angle of repose, bulk density, tapped density, bulkiness, compressibility index and hausner ratio. The results indicate good flow property of the granules and thus, the evaluated tablet physical properties were within the acceptable limits. The FT-IR study for the F-6 formulation showed that there was no interaction between the drug and the polymer. In vitro release studies were performed using Disso-2000 (paddle method) in 900 ml of pH 7.4 at 50 rpm. The result indicated that at high drug:polymer ratio (1:2) and hardness value 7 kg/cm2, prolonged drug release was observed than the low drug: polymer ratio (1:1) and hardness values (5 and 6 kg/cm2). The release kinetics was found to follow korsmeyers-peppas model and the mechanism of drug release was by non-fickian or anomalous diffusion. The F-6 formulation was chosen for stability studies. F-6 formulation was stable when it was kept at different temperatures for a period of 6 months.

Sekharan, T. Raja; Palanichamy, S.; Tamilvanan, S.; Shanmuganathan, S.; Thirupathi, A. Thanga

2011-01-01

53

Influence of internal structure on kinetics of drug release from wax matrix tablets.  

PubMed

To examine the influence of the internal structure of a wax matrix tablet on in vitro drug release, the release rates of several tablets consisting of various proportions of drug and wax were compared with the water penetration rates from the compressed and lateral surfaces of the tablets. The penetration rates from the lateral surface were found to be much faster than those from the compressed surface in all cases. A theoretical equation involving a two-dissolving-direction was derived on the basis of the boundary retreating concept. The retreating rate constants deduced from the dissolution results were well coincident with the values directly determined by the needle penetration method, suggesting good applicability of the proposed equation. The results suggest that the tortuosity of the water channels created in a tablet during dissolution is generally smaller in the horizontal direction than that in the vertical direction. This would be caused by the drug particles or granules being elongated in the horizontal direction by compression. PMID:2092942

Ishino, R; Yoshino, H; Hirikawa, Y; Noda, K

1990-12-01

54

Elucidation of release characteristics of highly soluble drug trimetazidine hydrochloride from chitosan-carrageenan matrix tablets.  

PubMed

The aim of this study was to better understand the underlying drug release characteristics from matrix tablets based on the combination of chitosan (CS) and different types of carrageenans [kappa (?)-CG, iota (?)-CG, and lambda (?)-CG]. Highly soluble trimetazidine hydrochloride (TH) was used as a model drug. First, characteristics of drug release from different formulations were investigated, and then in situ complexation capacity of CG with TH and CS was studied by differential scanning calorimetry and Fourier transform infrared spectroscopy. Erosion and swelling of matrix were also characterized to better understand the drug-release mechanisms. Effects of pH and ionic strength on drug release were also studied. It was found that not only ?-CG and ?-CG could reduce the burst release of TH by the effect of TH-CG interaction, CS-?-CG- and CS-?-CG-based polyelectrolyte film could further modify the controlled-release behavior, but not CS-?-CG. High pH and high ionic strength resulted in faster drug release from CS-?-CG- and CS-?-CG-based matrix, but drug release from CS-?-CG-based matrix was less sensitive to pH and ionic strength. In conclusion, CS-?-CG-based matrix tablets are quite promising as controlled-release drug carrier based on multiple mechanisms. PMID:23754467

Li, Liang; Wang, Linlin; Shao, Yang; Tian, Ye; Li, Conghao; Li, Ying; Mao, Shirui

2013-06-10

55

Development of polysaccharide based colon targeted drug delivery system: design and evaluation of Assam Bora rice starch based matrix tablet.  

PubMed

The aim of this study was to develop a novel colon targeted matrix tablet containing Metronidazole (MTZ) as model drug. Matrix tablets were prepared using Assam Bora rice starch, which is essentially a natural polymer, by wet granulation technique. The granules prepared were subjected to evaluation for angle of repose, bulk density, compressibility index, Hausner's ratio, total porosity, and drug content. The developed tablets were also analysed for thickness, diameter, weight variation tests, tablet crushing strength, friability, and in vitro release studies. The granules displayed satisfactory flow properties, compressibility, Hausner's ratio and drug content. Almost all the tablet formulations showed acceptable pharmacotechnical properties and complied with the in-house developed specifications for the tested parameters. Drug release study confirmed to the initial fast release in the acidic environment of surface adhered drug followed by slow release in alkaline media subsequently leading to fast and major drug release in the caecal content. Furthermore, the release of drug was unaffected by the hostile environment of GIT which can be ascribed to microbial degradation, promptly followed by enzymatic degradation. Curve fitting proved that the drug release from the tablets followed the Higuchi model. In vitro bacterial inhibition studies illustrated that the released drugs were able to diffuse through agar medium, inhibiting MTZ sensitive Bacteroides fragilis. The selected MTZ matrix tablets (F1-F6) had zones of inhibition paralleling those of the marketed formulation. PMID:21696349

Ahmad, Mohammad Zaki; Akhter, Sohail; Ahmad, Iqbal; Rahman, Mahfoozur; Anwar, Mohammad; Jain, Gourav K; Ahmad, Farhan J; Khar, Roop Krishen

2011-09-01

56

Statistical Optimization of Sustained Release Venlafaxine HCI Wax Matrix Tablet.  

PubMed

The purpose of this research was to prepare a sustained release drug delivery system of venlafaxine hydrochloride by using a wax matrix system. The effects of bees wax and carnauba wax on drug release profile was investigated. A 3(2) full factorial design was applied to systemically optimize the drug release profile. Amounts of carnauba wax (X(1)) and bees wax (X(2)) were selected as independent variables and release after 12 h and time required for 50% (t(50)) drug release were selected as dependent variables. A mathematical model was generated for each response parameter. Both waxes retarded release after 12 h and increases the t(50) but bees wax showed significant influence. The drug release pattern for all the formulation combinations was found to be approaching Peppas kinetic model. Suitable combination of two waxes provided fairly good regulated release profile. The response surfaces and contour plots for each response parameter are presented for further interpretation of the results. The optimum formulations were chosen and their predicted results found to be in close agreement with experimental findings. PMID:20046773

Bhalekar, M R; Madgulkar, A R; Sheladiya, D D; Kshirsagar, S J; Wable, N D; Desale, S S

57

Mechanism of drug release from an acrylic polymer-wax matrix tablet.  

PubMed

An acrylic polymer-wax matrix system was evaluated for oral sustained-release tablets of diphenhydramine HCl. A desirable release profile of diphenhydramine was achieved by incorporating Eudragit L in a carnauba wax matrix. In this polymer-wax system, carnauba wax maintained the integrity of the matrix, whereas Eudragit L slowly eroded in the matrix as the drug was released. Thus, the area-to-volume ratio of the tablet remained constant over the duration of the drug release. In vitro drug release studies were conducted at physiological pHs that exist in the gastrointestinal tract. Drug release rates decreased as the polymer:drug ratio increased from 1:2 to 2:1. The drug release rate was faster in pH 7.5 phosphate buffer than in 0.1 N HCl solution. The drug release from these polymer-wax matrices is described by a combination diffusion/erosion mechanism. Based on the typical pH encountered in intestinal fluids, complete dissolution of the drug and polymer at pH 7.5 in 8-10 h would ensure good bioavailability of the drug following oral administration. PMID:9120808

Huang, H P; Mehta, S C; Radebaugh, G W; Fawzi, M B

1994-06-01

58

In vitro and in vivo evaluation of guar gum matrix tablets for oral controlled release of water-soluble diltiazem hydrochloride.  

PubMed

The objective of the study was to develop guar gum matrix tablets for oral controlled release of water-soluble diltiazem hydrochloride. Matrix tablets of diltiazem hydrochloride, using various viscosity grades of guar gum in 2 proportions, were prepared by wet granulation method and subjected to in vitro drug release studies. Diltiazem hydrochloride matrix tablets containing either 30% wt/wt low-viscosity (LM1), 40% wt/wt medium-viscosity (MM2), or 50% wt/wt high-viscosity (HM2) guar gum showed controlled release. The drug release from all guar gum matrix tablets followed first-order kinetics via Fickian-diffusion. Further, the results of in vitro drug release studies in simulated gastrointestinal and colonic fluids showed that HM2 tablets provided controlled release comparable with marketed sustained release diltiazem hydrochloride tablets (D-SR tablets). Guar gum matrix tablets HM2 showed no change in physical appearance, drug content, or in dissolution pattern after storage at 40 degrees C/relative humidity 75% for 6 months. When subjected to in vivo pharmacokinetic evaluation in healthy volunteers, the HM2 tablets provided a slow and prolonged drug release when compared with D-SR tablets. Based on the results of in vitro and in vivo studies it was concluded that that guar gum matrix tablets provided oral controlled release of water-soluble diltiazem hydrochloride. PMID:16353958

Al-Saidan, Saleh M; Krishnaiah, Yellela S R; Patro, Srinivas S; Satyanaryana, Vemulapalli

2005-07-14

59

Application of dynamic neural networks in the modeling of drug release from polyethylene oxide matrix tablets.  

PubMed

The main objective of this study was to demonstrate the possible use of dynamic neural networks to model diclofenac sodium release from polyethylene oxide hydrophilic matrix tablets. High and low molecular weight polymers in the range of 0.9-5 x 10(6) have been used as matrix forming materials and 12 different formulations were prepared for each polymer. Matrix tablets were made by direct compression method. Fractions of polymer and compression force have been selected as most influential factors on diclofenac sodium release profile. In vitro dissolution profile has been treated as time series using dynamic neural networks. Dynamic networks are expected to be advantageous in the modeling of drug release. Networks of different topologies have been constructed in order to obtain precise prediction of release profiles for test formulations. Short-term and long-term memory structures have been included in the design of network making it possible to treat dissolution profiles as time series. The ability of network to model drug release has been assessed by the determination of correlation between predicted and experimentally obtained data. Calculated difference (f(1)) and similarity (f(2)) factors indicate that dynamic networks are capable of accurate predictions. Dynamic neural networks were compared to most frequently used static network, multi-layered perceptron, and superiority of dynamic networks has been demonstrated. The study also demonstrated differences between the used polyethylene oxide polymers in respect to drug release and suggests explanations for the obtained results. PMID:19632323

Petrovi?, Jelena; Ibri?, Svetlana; Betz, Gabriele; Parojci?, Jelena; Duri?, Zorica

2009-07-24

60

Prolonged release matrix tablet of pyridostigmine bromide: formulation and optimization using statistical methods.  

PubMed

The aim of this study was to design and optimize a prolonged release matrix formulation of pyridostigmine bromide, an effective drug in myasthenia gravis and poisoning with nerve gas, using hydrophilic - hydrophobic polymers via D-optimal experimental design. HPMC and carnauba wax as retarding agents as well as tricalcium phosphate were used in matrix formulation and considered as independent variables. Tablets were prepared by wet granulation technique and the percentage of drug released at 1 (Y(1)), 4 (Y(2)) and 8 (Y(3)) hours were considered as dependent variables (responses) in this investigation. These experimental responses were best fitted for the cubic, cubic and linear models, respectively. The optimal formulation obtained in this study, consisted of 12.8 % HPMC, 24.4 % carnauba wax and 26.7 % tricalcium phosphate, had a suitable prolonged release behavior followed by Higuchi model in which observed and predicted values were very close. The study revealed that D-optimal design could facilitate the optimization of prolonged release matrix tablet containing pyridostigmine bromide. Accelerated stability studies confirmed that the optimized formulation remains unchanged after exposing in stability conditions for six months. PMID:22713949

Bolourchian, Noushin; Rangchian, Maryam; Foroutan, Seyed Mohsen

2012-07-01

61

Optimization of sustained release matrix tablet of metoprolol succinate using central composite design.  

PubMed

The present study was performed to optimize the formulation of metoprolol succinate (MS) sustained release tablets using hydroxypropyl methylcellulose (HPMC) and sodium alginate (SA) as the matrix combination. After investigating the effects of various parameters on drug release, a 2-factor, 5-level central composite design was employed, using the amount of HPMC K4M (A) and SA (318 cP) (B) as the independent variables and the drug percentage released at 1h, 4h, 8h, 20h (Q1, Q4, Q8, Q20) as the responses. Response surfaces were established to obtain the matrix ranges and the main factors affecting four responses. In order to validate the optimization study, six confirmatory runs were performed; indicating high predictability of response surface methodology for MS sustained release tablets. Data fitting to Peppas equation indicated that the mechanism of drug release could be diffusion along with erosion. This matrix combination can be used as a good alternative to the commercially pellet technology, which was complicated, time-consuming and energy-intensive. PMID:24035948

Li, Li; Sun, Huijuan; Gao, Jing; Jiang, Tao; Gao, Yuan; Zhang, Jianjun

2013-09-01

62

Modulation of drug release kinetics from hydroxypropyl methyl cellulose matrix tablets using polyvinyl pyrrolidone.  

PubMed

Hydrophilic matrix tablets are widely used to extend the release of a broad range of pharmaceutically active materials. The mechanism and kinetics of drug release are dependent on the solubility of the active moiety and the swelling and erosion properties of the polymer, with water soluble compounds released predominantly by diffusion. The swelling and erosion properties of hydroxypropyl methyl cellulose (HPMC), typically lead to a first order release rate for water soluble compounds as opposed to the more desirable zero-order kinetics. In addition, for compounds with differences in regional absorption within the gastrointestinal tract a dosage form with a bi-modal release profile may be required, which is difficult to achieve with a simple dosage form. The following paper presents a simple, cost effective and elegant solution for achieving a range of predictable release profiles from linear to bi-modal for a water soluble drug (caffeine) from HPMC matrices, through the inclusion of polyvinyl pyrrolidone (PVP). Mechanistic studies using gel rheology, excipient dissolution and near-infrared microscopy (NIR) microscopy are presented which show that the modulation of drug release kinetics is mediated through a reduction in HPMC viscosity in the presence of a critical concentration of PVP, which leads to a break-up of the extended release tablet. A validated mathematical model is also presented which allows drug release profiles to be reliably predicted based on the initial HPMC and PVP content in the tablet. PMID:17306477

Hardy, Ian J; Windberg-Baarup, Anne; Neri, Claudia; Byway, Paul V; Booth, Steven W; Fitzpatrick, Shaun

2007-01-20

63

Formulation and roentgenographic studies of naproxen-pectin-based matrix tablets for colon drug delivery.  

PubMed Central

A study has been carried out to assess the potential use of pectin in combination with two added hydrocolloids, i.e., hydroxy-propyl-methyl cellulose and hydroxyethyl cellulose in varied concentrations and coated with ethyl cellulose and cellulose acetate phthalate. The results of in vitro drug release showed that the matrix tablets prepared with pectin, hydroxy ethyl cellulose (20 percent) when coated with ethyl cellulose and cellulose acetate phthalate were found to be 63.0 percent, 8.4 percent, and 4.5 percent, respectively, in after eight hours during drug release study period. These results were confirmed with the results of roentgenographic studies in nine healthy human volunteers to find the shape and integrity of the dosage form. The X-ray photographs revealed that the enteric-coated tablet was visible only up to 5.5 hours and at the end of eighth hour, the photograph has not shown any presence of tablet indicating the loss of shape and size by the microflora present in the colon region. So, the results of in vitro and roentgenographic studies revealed that pectin, hydroxy ethyl cellulose (20 percent) base coated with ethyl cellulose and cellulose acetate phthalate was found to be a promising carrier for naproxen to colon.

Rao, K. Purushotham; Prabhashankar, B.; Kumar, Ashok; Khan, Azeemuddin; Biradar, S. S.; Srishail, S. Patil; Satyanath, B.

2003-01-01

64

Formulation and in vitro evaluation of Eudragit S-100 coated naproxen matrix tablets for colon-targeted drug delivery system  

PubMed Central

The purpose of the present investigation was to prepare matrix tablets of naproxen using a hydrophobic polymer, i.e., Eudragit RLPO, RSPO, and combination of both, by wet granulation method. The tablets were further coated with different concentrations of Eudragit S-100, a pH-sensitive polymer, by dip immerse method. In vitro drug release studies of tablets were carried out in different dissolution media, i.e., 0.1 N HCl (pH 1.2), phosphate buffers pH 6.8 and 7.4, with or without rat cecal content. The swelling studies of the optimized formulation were carried out. The physicochemical parameters of all the formulations were found to be in compliance with the pharmacopoeial standards. The effect of dissolution medium on the surface of matrix tablet was determined by using Scanning Electron Microscopy technique. The stability studies of all formulations were performed as per ICH guidelines. The results demonstrated that the tablets coated with Eudragit S-100 (2% w/v) showed a sustained release of 94.67% for 24 h, but drug release increased to about 98.60% for 24 h in the presence of rat cecal content while the uncoated tablets released the drug within 5 h. With regard to release kinetics, the data were best fitted with the Higuchi model with non-Fickian drug release kinetics mechanism. The stability studies of tablets showed less degradation during accelerated and room temperature storage conditions for 6 months. The enteric-coated Eudragit S-100 coated matrix tablets of naproxen showed promising site-specific drug delivery in the colon region.

Mehta, Rohit; Chawla, Anuj; Sharma, Pooja; Pawar, Pravin

2013-01-01

65

Formulation and in vitro evaluation of Eudragit S-100 coated naproxen matrix tablets for colon-targeted drug delivery system.  

PubMed

The purpose of the present investigation was to prepare matrix tablets of naproxen using a hydrophobic polymer, i.e., Eudragit RLPO, RSPO, and combination of both, by wet granulation method. The tablets were further coated with different concentrations of Eudragit S-100, a pH-sensitive polymer, by dip immerse method. In vitro drug release studies of tablets were carried out in different dissolution media, i.e., 0.1 N HCl (pH 1.2), phosphate buffers pH 6.8 and 7.4, with or without rat cecal content. The swelling studies of the optimized formulation were carried out. The physicochemical parameters of all the formulations were found to be in compliance with the pharmacopoeial standards. The effect of dissolution medium on the surface of matrix tablet was determined by using Scanning Electron Microscopy technique. The stability studies of all formulations were performed as per ICH guidelines. The results demonstrated that the tablets coated with Eudragit S-100 (2% w/v) showed a sustained release of 94.67% for 24 h, but drug release increased to about 98.60% for 24 h in the presence of rat cecal content while the uncoated tablets released the drug within 5 h. With regard to release kinetics, the data were best fitted with the Higuchi model with non-Fickian drug release kinetics mechanism. The stability studies of tablets showed less degradation during accelerated and room temperature storage conditions for 6 months. The enteric-coated Eudragit S-100 coated matrix tablets of naproxen showed promising site-specific drug delivery in the colon region. PMID:23662280

Mehta, Rohit; Chawla, Anuj; Sharma, Pooja; Pawar, Pravin

2013-01-01

66

In vitro release of ketoprofen from hydrophilic matrix tablets containing cellulose polymer mixtures.  

PubMed

The effect of cellulose ether polymer mixtures, containing both hydroxypropylcellulose (HPC) and hydroxypropylmethylcellulose (HPMC K15M or K100M), on ketoprofen (KTP) release from matrix tablets was investigated. In order to evaluate the compatibility between the matrix components, Raman spectroscopy, scanning electron microscopy (SEM), and X-ray powder diffraction (XRPD) experiments were performed. The results evidence the absence of significant intermolecular interactions that could eventually lead to an incompatibility between the drug and the different excipients. Formulations containing mixtures of polymers with both low and high viscosity grades were prepared by a direct compression method, by varying the polymer/polymer (w/w) ratio while keeping the drug amount incorporated in the solid dispersion constant (200?mg). The hardness values of different matrices were found within the range 113.8 to 154.9 N. HPLC analysis showed a drug content recovery between 99.3 and 102.1%, indicating that no KTP degradation occurred during the preparation process. All formulations attained a high hydration degree after the first hour, which is essential to allow the gel layer formation prior to tablet dissolution. Independent-model dissolution parameters such as t10% and t50% dissolution times, dissolution efficiency (DE), mean dissolution time (MDT), and area under curve (AUC) were calculated for all formulations. Zero-order, first-order, Higuchi, and Korsmeyer-Peppas kinetic models were employed to interpret the dissolution profiles: a predominantly Fickian diffusion release mechanism was obtained - with Korsmeyer-Peppas exponent values ranging from 0.216 to 0.555. The incorporation of HPC was thus found to play an essential role as a release modifier from HPMC containing tablets. PMID:23094867

Vueba, M L; Batista de Carvalho, L A E; Veiga, F; Sousa, J J; Pina, M E

2012-10-24

67

Pharmaceutical applications of shellac: moisture-protective and taste-masking coatings and extended-release matrix tablets.  

PubMed

Shellac is a natural polymer, which is used as enteric coating material in pharmaceutical applications. The major objective of the present study was to investigate the potential of shellac for other purposes, namely to provide moisture-protective and taste-masking coatings as well as extended-release matrix tablets. The efficiency of shellac to achieve moisture protection and taste masking was compared with that of hydroxypropyl methylcellulose (HPMC), which is most frequently used for these purposes. Shellac-coated tablets showed lower water uptake rates than HPMC-coated systems at the same coating level. The stability of acetylsalicylic acid was higher in tablets coated with shellac compared with HPMC-coated systems, irrespective of the storage humidity. Therefore, lower shellac coating levels were required to achieve the same degree of drug protection. Shellac coatings effectively masked the unpleasant taste of acetaminophen tablets. Compared to HPMC, again lower coating levels were required to achieve similar effects. The resulting drug release in simulated gastric fluid was not significantly altered by the thin shellac coatings, which rapidly ruptured due to the swelling of the coated tablet core. In addition, shellac was found to be a suitable matrix former for extended-release tablets. The latter could be prepared by direct compression or via wet granulation using ethanolic or ammoniated aqueous shellac binder solutions. The resulting drug-release patterns could effectively be altered by varying different formulation and processing parameters. PMID:14570313

Pearnchob, N; Siepmann, J; Bodmeier, R

2003-09-01

68

Formulation Development and Stability Studies of Norfloxacin Extended-Release Matrix Tablets  

PubMed Central

The aim of this research was to develop a new hydrophilic matrix system containing norfloxacin (NFX). Extended-release tablets are usually intended for once-a-day administration with benefits to the patient and lower discontinuation of the therapy. Formulations were developed with hydroxypropylmethylcellulose or poly(ethylene oxide) as hydrophilic polymers, with different molecular weights (MWs) and concentrations (20 and 30%). The tablets were found to be stable (6 months at 40 ± 2°C and 75 ± 5% relative humidity), and the film-coating process is recommended to avoid NFX photodegradation. The dissolution profiles demonstrated an extended-release of NFX for all developed formulations. Dissolution curves analyzed using the Korsmeyer exponential equation showed that drug release was controlled by both drug diffusion and polymer relaxation or erosion mechanisms. A more erosion controlled system was obtained for the formulations containing lower MW and amount of polymer. With the increase in both MW and amount of polymer in the formulation, the gel layer became stronger, and the dissolution was more drug-diffusion dependent. Formulations containing intermediate MW polymers or high concentration (30%) of low MW polymers demonstrated a combination of extended and complete in vitro drug release. This way, these formulations could provide an increased bioavailability in vivo.

Oliveira, Paulo Renato; Klein, Lilian; Sangoi, Maximiliano da Silva; Bernardi, Larissa Sakis; Silva, Marcos Antonio Segatto

2013-01-01

69

Release from or through a wax matrix system. IV. Generalized expression of the release process for a reservoir device tablet.  

PubMed

Generalization of the release process through the wax matrix layer was examined by use of a reservoir device tablet. The wax matrix layer of the reservoir device tablet was prepared from a physical mixture of lactose and hydrogenated castor oil to simplify the release properties. Release through the wax matrix layer showed zero-order kinetics in a steady state after a given lag time, and could be divided into two stages. The first stage was the formation process of water channel by dissolving the soluble component in the wax matrix layer. The lag time obtained by applying the square root law equation was well connected with the amount of the matrix layer and mixed weight ratio of components in this layer. The second stage was the zero-order release process of drug in the reservoir through the wax matrix layer, because the effective surface area was fixed. The release rate constants were connected with thickness of the matrix layer and permeability coefficient, and the permeability coefficients were connected with the diffusion coefficient of drug and porosity. Hence the release rate constant could be connected with the amount of matrix layer and the mixed weight ratio of components in the matrix layer. It was therefore suggested that the release process could be generalized using the amount of matrix layer and the mixed weight ratio of components in the matrix layer. PMID:12237539

Yonezawa, Yorinobu; Ishida, Sumio; Suzuki, Shinobu; Sunada, Hisakazu

2002-09-01

70

Controlled drug release of highly water-soluble pentoxifylline from time-limit disintegration-type wax matrix tablets.  

PubMed

A pulsatile drug release system with a dry-coated tablet containing pentoxifylline was investigated for controlling drug release in the gastrointestinal tract. The system consisted of a core tablet with disintegrator and outer layer, which obtained compression from the ground mixtures of pentoxifylline and behenic acid. Drug release from a dry-coated tablet was investigated at 37 degrees C in JPXII 2nd fluid at pH 6.8. The drug release from the outer layer was fitted to the Cobby model. The drug release from the wax matrix increased significantly after tablet distintegration; therefore, the drug release profiles showed typical sigmoidal curves. The disintegration time depended on the weight fraction of the core tablet, and the drug release rate after disintegration increased with increasing drug concentration in the core tablet. The relationship between the time required for 50% drug release and the disintegration time was linear, indicating that the drug release rate was controlled by regulating the disintegration time. PMID:8008697

Otsuka, M; Matsuda, Y

1994-03-01

71

[The control of drug release of heavy-soluble, weak basic drugs in matrix tablets using the example of medazepam].  

PubMed

According to ideas about the diffusion layer in the process of dissolving solids the release of medazepam as a model substance for heavy-soluble, weak alkaline substances is modified by incorporation of solid acids of different solubility and dissociation rate into the matrix. The determination of the solubility and a "virtual" pH-value within the matrix tablets leads to the evaluation of the liberation. A relatively continuous release of medazepam following different pH-values in the medium was obtained by microencapsulation of the citrus acid incorporated. Using the ideas of the diffusion layer to explain the conditions within the matrix it becomes possible to control and influence the drug release from the matrix tablet. PMID:2870512

Zessin, G; Fahr, F; Mank, R

1986-01-01

72

Release from or through a wax matrix system. V. Applicability of the square-root time law equation for release from a wax matrix tablet.  

PubMed

To obtain basic and clear release properties, wax matrix tablets were prepared from a physical mixture of drug and wax powder at a fixed mixing ratio. Properties of release from the single flat-faced surface, curved side surface, and/or whole surface of the wax matrix tablet were examined. Then tortuosity and the applicability of Higuchi's square-root time law equation were examined. The Higuchi equation well analyzed the release processes of different release manners. However, the region fitted to the Higuchi equation differed with the release manner. Tortuosity obtained with release from the single flat-faced surface and curved side surface was comparable with that obtained with the release from a reservoir device tablet, whereas tortuosity obtained with release from the whole surface was larger. As the wax matrix tablets were prepared at a fixed mixing ratio, their internal structures should be similar. Therefore changes in the matrix volume or volume fraction with release were examined, and an extra volume where dissolved drug stray becomes large with release time in the case of release from the whole surface. These factors should be taken into account for evaluation of applicability and release properties. Furthermore, the entire release process should be analyzed using a combination of the square-root time law and other suitable equations in accordance with release manner or condition. PMID:12913226

Yonezawa, Yorinobu; Ishida, Sumio; Sunada, Hisakazu

2003-08-01

73

Photoimages and the release characteristics of lipophilic matrix tablets containing highly water-soluble potassium citrate with high drug loadings.  

PubMed

Two types of the carnauba wax-based lipophilic matrix tablet using spray-dried granules (SDT) or directly compressible powdered mixtures (DCT) were prepared for sustained release. The model drug was a highly water-soluble potassium citrate and loaded about 74% of the total tablet weight. The SDT slowly eroded and disintegrated during the release study without showing sustained release when the hydrophilic excipients were added. In contrast, the DCT was more efficient for sustained release. The release rate decreased with increasing carnauba wax concentration. In particular, the sustained release rate was markedly pronounced when the lipophilic stearyl alcohol and stearic acid were combined with the carnauba wax. The surface of the intact DCT appeared to be smooth and rusty. The DCT rose to the surface from the bottom of the vessel during the release test, and numerous pores and cracks with no signs of disintegration were also observed after the release test. The release profile was dependent on the formulation composition and preparation method of the matrix tablet. Diffusion-controlled leaching through the channels of the pores and cracks of the lipophilic matrix tablet (DCT) is a key to the sustained release. PMID:17532156

Cao, Qing-Ri; Kim, Tae-Wan; Lee, Beom-Jin

2007-04-24

74

Effect of channeling agents on the release pattern of theophylline from kollidon SR based matrix tablets.  

PubMed

The purpose of the present study was to investigate the effect of channeling agent on the release profile of theophylline from Kollidon SR based matrix systems. Matrix tablets of theophylline using Kollidon SR which is plastic in nature were prepared by direct compression process. NaCl and PEG 1500 were used as channeling agents. Drug release study was evaluated for eight hours using USP 22 paddle-type dissolution apparatus using distilled water as the dissolution medium. The release mechanisms were explored and explained with zero order, Higuchi, first order and Korsmeyer equations. The release rate, extent and mechanisms were found to be governed by the type and content of the channeling agents. Increased rate and extent of the drug release were found by using higher content of channeling agent (42.49%) in the matrix due to increased porosity when compared with the formulation having no channeling agents. On the other hand decreased rate and extent of drug release were observed in the formulation having lower channeling agent content (19.76%). PEG 1500 ensures maximum release of drug from Kollidon SR than NaCl when other parameters were kept unchanged. It was found that type and amount of channeling agent significantly affect the time required for 50% of drug release (T50%), percentage drug release at 8 hours, release rate constant (K) and diffusion exponent (n). Kinetic modeling of dissolution profiles revealed drug release mechanism ranges from diffusion controlled or Fickian transport to anomalous type or non-Fickian transport, which was mainly dependent on the type and amount of channeling agents. These studies indicate that the proper balance between a matrix forming agent and a channeling agent can produce a drug dissolution profile similar to a desired dissolution profile. PMID:19553179

Ibn Razzak, Md Shaikhul Millat; Khan, Ferdous; Hossain, Masuma; Khan, Md Ziaur Rahman; Azad, Mohammad Abul Kalam; Reza, Md Selim

2009-07-01

75

Spray-dried O-carboxymethyl chitosan as potential hydrophilic matrix tablet for sustained release of drug.  

PubMed

Abstract Objective: The aim of the present investigation was to evaluate the use of spray-dried O-carboxymethyl chitosan (OCMCS) as potential hydrophilic matrix excipient for sustained release of drug. Methods: The polymer was synthesized from chitosan, then spray-dried and characterized. Tablets with different OCMCS concentrations (80, 50, 30, 5 and 2% w/w), containing diltiazem (DTZ) as model drug, were prepared for direct compression (DC) and after the wet granulation method (WG). Results: The spray-dried OCMCS powder was spherical, with a smooth surface and an average size of 2.2?µm. The tablets prepared for WG disintegrated in time less than 30?min. The tablets obtained for DC presented high retention of the drug, with zero order or Higuchi release kinetic. There was a direct relationship between the OCMCS concentration and the release ratio, swelling degree and water uptake behavior. DC tablets containing 80% OCMCS presented behavior as an effective swelling-control system. The DC tablets with 5% OCMCS showed a similar release profile at formulations with 30% HPMC. Conclusion: Spray-dried OCMCS showed great potential as hydrophilic matrices for drug-sustained release. PMID:23594298

Bresolin, José R; Largura, Maria-Claudia T; Dalri, Camila C; Hoffer, Geórgia; Rodrigues, Clóvis A; Lucinda-Silva, Ruth M

2013-04-17

76

Graft copolymers of ethyl methacrylate on waxy maize starch derivatives as novel excipients for matrix tablets: physicochemical and technological characterisation.  

PubMed

Nowadays, graft copolymers are being used as an interesting option when developing a direct compression excipient for controlled release matrix tablets. New graft copolymers of ethyl methacrylate (EMA) on waxy maize starch (MS) and hydroxypropylstarch (MHS) were synthesised by free radical polymerization and alternatively dried in a vacuum oven (OD) or freeze-dried (FD). This paper evaluates the performance of these new macromolecules and discusses the effect of the carbohydrate nature and drying process on their physicochemical and technological properties. Grafting of EMA on the carbohydrate backbone was confirmed by IR and NMR spectroscopy, and the grafting yields revealed that graft copolymers present mainly a hydrophobic character. The graft copolymerization also leads to more amorphous materials with larger particle size and lower apparent density and water content than carbohydrates (MS, MHS). All the products show a lack of flow, except MHSEMA derivatives. MSEMA copolymers underwent much plastic flow and less elastic recovery than MHSEMA copolymers. Concerning the effect of drying method, FD derivatives were characterised by higher plastic deformation and less elasticity than OD derivatives. Tablets obtained from graft copolymers showed higher crushing strength and disintegration time than tablets obtained from raw starches. This behaviour suggests that these copolymers could be used as excipients in matrix tablets obtained by direct compression and with a potential use in controlled release. PMID:19146956

Marinich, J A; Ferrero, C; Jiménez-Castellanos, M R

2008-12-25

77

Optimization and prediction of drug release from matrix tablets using response surface methodology and near infrared chemical imaging.  

PubMed

The purpose of this work was to understand the formulation effect on the drug release from a hydrophilic matrix tablet of niacin using a multivariate statistical technique and Near Infrared Chemical Imaging (NIR-CI). Tablets were composed of ethyl cellulose (EC) and polyethylene oxide (PEO) as release retarding polymers and lactose as the release modulator. D-optimal experimental design was composed of three formulation variables: the content of EC(X(1)), PEO (X(2)), and lactose (X(3)). Response surface methodology (RSM) and multiple response optimization utilizing the polynomial equation were used to predict the optimal formulation. Results showed that the interaction effect of lactose with the polymers PEO and EC and lactose by itself were the most influential factors on the drug release rate. While lactose enhances the drug release rate by forming pores it also promotes water penetration into the tablet core. This in turn helps the formation of the gel layer which acts as barrier to drug diffusion. NIR-CI showed that tablets with higher level of PEO swells at a faster rate and greater extent than formulations with higher level of EC. NIR-CI was thus found to be a very useful technique to predict the drug release rate from hydrophilic matrix systems. PMID:21222508

Bagchi, Saumitra; Li, Weiyong; Plakogiannis, Fotios

2011-01-11

78

Drug release phenomena within a hydrophobic starch acetate matrix: FTIR mapping of tablets after in vitro dissolution testing.  

PubMed

The aim of this study was to assess the utility of Fourier transform infrared mapping to study the drug release phenomena within a hydrophobic matrix tablet. Starch acetate with a degree of substitution (2.7) was used as a hydrophobic matrix former. Anhydrous caffeine and riboflavin sodium phosphate were used as water soluble model drugs. The USP (XXVIII) paddle-method was selected as an in vitro dissolution test. Mapping of the diluted tablets' cross-section was performed by attenuated total reflection mode. Fourier transform infrared mapping can distinguish drug particles from the bulk matrix and it can be considered as a valuable method for obtaining both quantitative and qualitative information on drug release processes. The physicochemical properties of the drug compound strongly contribute to its release behavior when the USP paddle in vitro dissolution test is used. Mapping of the riboflavin product revealed a more homogenous matrix distribution due to its smaller particle size. Consequently, its dissolution release profile was more uniform than caffeine which possessed a wider particle size distribution and lower solubility. Mapping showed that caffeine became localized in the lower part of the tablet unlike riboflavin. The hydrodynamic conditions during the in vitro release test might contribute to this differentiation. PMID:18085712

Pajander, Jari; Soikkeli, Anne-Marie; Korhonen, Ossi; Forbes, Robert T; Ketolainen, Jarkko

2008-08-01

79

Ultrasound Transmission Technique as a Potential Tool for Physical Evaluation of Monolithic Matrix Tablets  

PubMed Central

The aim of this study was to investigate the effects of tablet porosity and particle size fraction of compacted Starch acetate powders, with and without model drug caffeine, on acoustic properties of tablets. The ultrasound velocity was determined from the transmission measurements. Tablets of starch acetate (SA DS 2.7) powder with two particle size fractions of 0–53 and 0–710 ?m were compressed with a compaction simulator. Porosities of tablets varied in the range from 12% to 43% for both particle size fractions. Strong associations were found between the ultrasound velocity and physical properties of the tablets such as porosity and particle size fraction. Interestingly, ultrasound velocity was practically insensitive to inclusion of the model drug caffeine with the concentrations used. Based on this study ultrasound transmission method is a potential non-destructive tool for studying structural changes of tablets and other solid dosage forms.

Pajander, J.; Leskinen, J.; Ketolainen, J.; van Veen, B.; Niinimaki, K.; Pirskanen, K.; Poso, A.; Lappalainen, R.

2008-01-01

80

Ultrasound transmission technique as a potential tool for physical evaluation of monolithic matrix tablets.  

PubMed

The aim of this study was to investigate the effects of tablet porosity and particle size fraction of compacted Starch acetate powders, with and without model drug caffeine, on acoustic properties of tablets. The ultrasound velocity was determined from the transmission measurements. Tablets of starch acetate (SA DS 2.7) powder with two particle size fractions of 0-53 and 0-710 microm were compressed with a compaction simulator. Porosities of tablets varied in the range from 12% to 43% for both particle size fractions. Strong associations were found between the ultrasound velocity and physical properties of the tablets such as porosity and particle size fraction. Interestingly, ultrasound velocity was practically insensitive to inclusion of the model drug caffeine with the concentrations used. Based on this study ultrasound transmission method is a potential non-destructive tool for studying structural changes of tablets and other solid dosage forms. PMID:18446491

Hakulinen, M A; Pajander, J; Leskinen, J; Ketolainen, J; van Veen, B; Niinimäki, K; Pirskanen, K; Poso, A; Lappalainen, R

2008-01-09

81

Controlled Release Matrix Tablets of Zidovudine: Effect of Formulation Variables on the In Vitro Drug Release Kinetics  

Microsoft Academic Search

The purpose of this research was to design oral controlled release (CR) matrix tablets of zidovudine (AZT) using hydroxypropyl\\u000a methylcellulose (HPMC), ethyl cellulose (EC) and carbopol-971P (CP) and to study the effect of various formulation factors\\u000a on in vitro drug release. Release studies were carried out using USP type 1 apparatus in 900 ml of dissolution media. Release kinetics\\u000a were analyzed

Punna Rao Ravi; Udaya Kanth Kotreka; Ranendra Narayan Saha

2008-01-01

82

The application of generalized regression neural network in the modeling and optimization of aspirin extended release tablets with Eudragit ® RS PO as matrix substance  

Microsoft Academic Search

The objective of this work is to use a generalized regression neural network (GRNN) in the design of extended-release aspirin tablets. As model formulations, 10 kinds of aspirin matrix tablets were prepared. Eudragit® RS PO was used as matrix substance. The amount of Eudragit® RS PO and compression pressure were selected as causal factors. In-vitro dissolution–time profiles at four different

Svetlana Ibri?; Milica Jovanovi?; Zorica Djuri?; Jelena Paroj?i?; Ljiljana Solomun

2002-01-01

83

Dissolution behaviour of hydrophilic matrix tablets containing two different polyethylene oxides (PEOs) for the controlled release of a water-soluble drug. Dimensionality study  

Microsoft Academic Search

Hydrophilic matrix tablets containing polyethylene oxides as the retarding polymer have been successfully employed in the controlled release of drugs. To evaluate the relative influence of drug diffusion and polymer erosion mechanisms in the drug delivery process, we studied the hydration behaviour of matrix tablets containing a water-soluble drug and PEOs of two different molecular weights: Polyox WSRN 1105 (Mw=0.9×106)

L. Maggi; L. Segale; M. L. Torre; E. Ochoa Machiste; U. Conte

2002-01-01

84

Controlled release matrix tablets of olanzapine: influence of polymers on the in vitro release and bioavailability.  

PubMed

Controlled-release (CR) tablet formulation of olanzapine was developed using a binary mixture of Methocel® K100 LV-CR and Ethocel® standard 7FP premium by the dry granulation slugging method. Drug release kinetics of CR tablet formulations F1, F2, and F3, each one suitably compressed for 9-, 12-, and 15-kg hardness, were determined in a dissolution media of 0.1 N HCl (pH 1.5) and phosphate buffer (pH 6.8) using type II dissolution apparatus with paddles run at 50 rpm. Ethocel® was found to be distinctly controlling drug release, whereas the hardness of tablets and pH of the dissolution media did not significantly affect release kinetics. The CR test tablets containing 30% Methocel® and 60% Ethocel® (F3) with 12-kg hardness exhibited pH-independent zero-order release kinetics for 24 h. In vivo performance of the CR test tablet and conventional reference tablet were determined in rabbit serum using high-performance liquid chromatography coupled with electrochemical detector. Bioavailability parameters including C(max), T(max), and AUC(0-48 h) of both tablets were compared. The CR test tablets produced optimized C(max) and extended T(max) (P < 0.05). A good correlation of drug absorption in vivo and drug release in vitro (R(2) = 0.9082) was observed. Relative bioavailability of the test tablet was calculated as 94%. The manufacturing process employed was reproducible and the CR test tablets were stable for 6 months at 40 ± 2°C/75 ± 5% relative humidity. It was concluded that the CR test tablet formulation successfully developed may improve tolerability and patient adherence by reducing adverse effects. PMID:20824513

Badshah, Amir; Subhan, Fazal; Rauf, Khalid

2010-09-08

85

Wax-matrix tablet for time-dependent colon-specific delivery system of sophora flavescens Aiton: preparation and in vivo evaluation.  

PubMed

A wax-matrix time-dependent colon-specific tablet (WM-TDCS) was studied. Wax-matrix tablet core consisting of semi-synthetic glycerides, as a wax polymeric expanding agent, carboxymethyl starch sodium (CMS-Na), and NaCl was prepared, and Sophora flavescens Aiton (ASF, extracts of traditional Chinese medicine) was used as model drug. The wax-matrix ASF tablets core was coated with Eudragit NE 30 D as the inner coating materials and with Opadry OY-P-7171 as the outer coating materials. The in vitro release behaviors of the coated tablets were examined and then in vivo absorption kinetics of the coated tablets in dogs was further investigated. The volume of the tablet core was markedly increased at 37 degrees C because of the expand effect of polymer semi-synthetic glycerides and CMS-Na. The drug release from WM-TDCS was more stable than TDCS in vitro and in vivo. The lag time of ASF release was also controlled by the thickness of the inner coating layer. In vivo evaluation demonstrated that in vivo lag time of absorption was in a good agreement with in vitro lag time of release. ASF wax-matrix tablets coated with Eudragit NE 30 D and Opadry OY-P-7171 using the regular coating technique could be designed to achieve a lag time of 3 h in the small intestinal tract. PMID:18785039

Zou, Meijuan; Wang, Yue; Xu, Caihong; Cheng, Gang; Ren, Jungang; Wu, Gaolei

2009-02-01

86

Formulation and in vitro evaluation of theophylline matrix tablets prepared by direct compression: Effect of polymer blends.  

PubMed

The deformation mechanism of pharmaceutical powders, used in formulating directly compressed matrix tablets, affects the characteristics of the formed tablets. Three polymers of different deformation mechanisms were tested for their impact on theophylline directly compressed tablets namely Kollidon SR (KL SR, plastic deformation), Ethylcellulose (EC, elastic deformation) and Carnauba wax (CW, brittle deformation) at different compression forces. However, tablets based mainly on KL SR, the plastically deformed polymer (TN1) exhibited the highest hardness values compared to the other formulae which are based on either blends of KL SR with CW, the very brittle deformed polymer. The upper detected force for TN formulae and the lower punch force were found to dependent mainly on the powder deformation. This difference is attributed to the work done during the compression phase as well as the work lost during the decompression phase. Furthermore, the release profiles of TN from formulae TN2 and TN4 that are based on the composition (2KL SR:1EC) and (1KL SR:2EC), respectively, were consistent with different deformation mechanisms of KL SR and EC and on the physicochemical properties like the water absorptive capacity of EC. Upon increasing the weight ratio of KL SR (TN2), the release rate was greatly retarded (39.4%, 37.1%, 35.0% and 33.6% released after 8 h at 5, 10, 15 and 20 kN. PMID:24115902

El-Bagory, Ibrahim; Barakat, Nahla; Ibrahim, Mohamed A; El-Enazi, Fouza

2011-12-03

87

Artificial neural networks in the modeling and optimization of aspirin extended release tablets with Eudragit L 100 as matrix substance.  

PubMed

The purpose of the present study was to model the effects of the concentration of Eudragit L 100 and compression pressure as the most important process and formulation variables on the in vitro release profile of aspirin from matrix tablets formulated with Eudragit L 100 as matrix substance and to optimize the formulation by artificial neural network. As model formulations, 10 kinds of aspirin matrix tablets were prepared. The amount of Eudragit L 100 and the compression pressure were selected as causal factors. In vitro dissolution time profiles at 4 different sampling times were chosen as responses. A set of release parameters and causal factors were used as tutorial data for the generalized regression neural network (GRNN) and analyzed using a computer. Observed results of drug release studies indicate that drug release rates vary widely between investigated formulations, with a range of 5 hours to more than 10 hours to complete dissolution. The GRNN model was optimized. The root mean square value for the trained network was 1.12%, which indicated that the optimal GRNN model was reached. Applying the generalized distance function method, the optimal tablet formulation predicted by GRNN was with 5% of Eudragit L 100 and tablet hardness 60N. Calculated difference (f1 2.465) and similarity (f2 85.61) factors indicate that there is no difference between predicted and experimentally observed drug release profiles for the optimal formulation. This work illustrates the potential for an artificial neural network, GRNN, to assist in development of extended release dosage forms. PMID:12916918

Ibri?, Svetlana; Jovanovi?, Milica; Djuri?, Zorica; Parojci?, Jelena; Petrovi?, Slobodan D; Solomun, Ljiljana; Stupar, Biljana

2003-01-01

88

Sucrose esters with various hydrophilic-lipophilic properties: novel controlled release agents for oral drug delivery matrix tablets prepared by direct compaction.  

PubMed

Sucrose esters (SE) are esters of sucrose and fatty acids with various hydrophilic-lipophilic properties which have attracted interest from being used in pharmaceutical applications. This study aimed to gain insight into the use of SE as controlled release agents for direct compacted matrix tablets. The study focused on the effect of hydrophilic-lipophilic properties on tableting properties and drug release. Sucrose stearate with hydrophilic-lipophilic balance (HLB) values ranging from 0 to 16 was systematically tested. Tablet formulations contained SE, metoprolol tartrate as a highly soluble model drug and dibasic calcium phosphate dihydrate as a tablet formulation filler in the ratio 1:1:2. The compaction behaviour of matrix tablets was compared with the compacts of individual starting materials as reference. SE incorporation improved the plasticity, compressibility and lubricating property of powder mixtures. The hydrophilic-lipophilic properties of SE affected tableting properties, drug release rate and release mechanism. Increasing hydrophilicity corresponding to the increased monoesters in SE composition increased the relative porosity, elastic recovery and tensile strength of the tablets due to the increased hydrogen bonding between the monoesters. This also facilitated the swelling behaviour of SE, which sustained the drug release rate. A sustained release effect prevailed in tablets containing SE with HLB values of 3-16. The ability to improve the tableting properties as well as sustain the drug release rate of the highly soluble model drug via gelation of SE highlights SE as promising controlled release regulators for direct compacted matrix tablets comprising drugs with various solubilities according to the Biopharmaceutics Classification System. PMID:20132913

Chansanroj, K; Betz, G

2010-02-02

89

Formulation and Evaluation of Cephalexin Extended-release Matrix Tablets Using Hydroxy Propyl Methyl Cellulose as Rate-controlling Polymer  

PubMed Central

The present investigation reports the design and evaluation of six-hour extended release film-coated matrix tablets of cephalexin using different grades of hydrophilic polymer hydroxypropylmethylcellulose (HPMC) employing direct compression method. The preformulation studies performed included the physical compatibility studies, Differential Scanning Calorimetry analysis, drug characterization using Fourier Transform Infra Red spectroscopic analysis and particle size analysis using sieve method. The tablets were evaluated for weight variation, hardness, thickness and friability. Results of the studies indicate that the polymers used have significant release-retarding effect on the formulation. The dissolution profile comparison of the prepared batches P1 to P8 and market preparation (Sporidex AF 375) was done by using Food and Drug Administration-recommended similarity factor (f2) determination. The formulation P8 (10% HPMC K4M, 15% HPMC 15cps) with a similarity factor (f2) of 77.75 was selected as the optimized formulae for scale-up batches. The dissolution data of the best formulation P8 was fitted into zero order, first order, Higuchi and Korsemeyer-Peppas models to identify the pharmacokinetics and mechanism of drug release. The results of the accelerated stability study of best formulation P8 for three months revealed that storage conditions were not found to have made any significant changes in final formulation F3. The release of cephalexin was prolonged for 6 h by using polymer combinations of HPMC and a twice daily matrix tablet was formulated.

Vijay, J; Sahadevan, JT; Prabhakaran, R; Gilhotra, R Mehra

2012-01-01

90

Preparation and evaluation of sustained-release matrix tablets based on metoprolol and an acrylic carrier using injection moulding.  

PubMed

Sustained-release matrix tablets based on Eudragit RL and RS were manufactured by injection moulding. The influence of process temperature; matrix composition; drug load, plasticizer level; and salt form of metoprolol: tartrate (MPT), fumarate (MPF) and succinate (MPS) on ease of processing and drug release were evaluated. Formulations composed of 70/30% Eudragit RL/MPT showed the fastest drug release, substituting part of Eudragit RL by RS resulted in slower drug release, all following first-order release kinetics. Drug load only affected drug release of matrices composed of Eudragit RS: a higher MPT concentration yielded faster release rates. Adding triethyl citrate enhanced the processability, but was detrimental to long-term stability. The process temperature and plasticizer level had no effect on drug release, whereas metoprolol salt form significantly influenced release properties. The moulded tablets had a low porosity and a smooth surface morphology. A plasticizing effect of MPT, MPS and MPF on Eudragit RS and Eudragit RL was observed via DSC and DMA. Solubility parameter assessment, thermal analysis and X-ray diffraction demonstrated the formation of a solid solution immediately after production, in which H-bonds were formed between metoprolol and Eudragit as evidenced by near-infrared spectroscopy. However, high drug loadings of MPS and MPF showed a tendency to recrystallise during storage. The in vivo performance of injection-moulded tablets was strongly dependent upon drug loading. PMID:22965662

Quinten, T; Andrews, G P; De Beer, T; Saerens, L; Bouquet, W; Jones, D S; Hornsby, P; Remon, J P; Vervaet, C

2012-09-11

91

Microsphere-based once-daily modified release matrix tablets for oral administration in angina pectoris.  

PubMed

The objective of this research was to develop microsphere-based once-daily modified release tablet formulations of diltiazem hydrochloride (DH), a potent calcium channel blocker used in angina pectoris. For this purpose, DH-loaded microspheres were prepared by the solvent evaporation technique using Eudragit RS 100. The effect of variation in the drug/polymer ratio on the physical and release characteristics of the microspheres was investigated. After the selection of the suitable microspheres, tablets were compressed using Compritol 888 ATO, Ludipress and Cellactose 80 as different direct tableting agents and excipients. As a result, modified release tablet formulations of DH-loaded microspheres were designed successfully for oral administration once rather than two or three times a day in angina pectoris. PMID:18465309

Sengel-Türk, Ceyda T; Hasçicek, Canan; Gönül, Nur?in

2008-06-01

92

Properties of lipophilic matrix tablets containing phenylpropanolamine hydrochloride prepared by hot-melt extrusion  

Microsoft Academic Search

The objective of the present study was to investigate the influence of formulation factors on the physical properties of hot-melt extruded granules and compressed tablets containing wax as a thermal binder\\/retarding agent, and to compare the properties of granules and tablets with those prepared by a high-shear melt granulation (MG) method. Powder blends containing phenylpropanolamine hydrochloride, Precirol® and various excipients

Jiping Liu; Feng Zhang; James W McGinity

2001-01-01

93

Influence of layer position on in vitro and in vivo release of levodopa methyl ester and carbidopa from three-layer matrix tablets  

Microsoft Academic Search

A versatile oral controlled release system for the simultaneous delivery of levodopa methyl ester and carbidopa, consisting of a three-layer matrix tablet, has been studied and developed. Each individual layer of the matrix exhibited a different release mechanism, i.e. the first layer was swellable (S), the second one was erodible (E) and the third one was disintegrating (D). The three

R Bettini; D Acerbi; G Caponetti; R Musa; N Magi; P Colombo; D Cocconi; P Santi; P. L Catellani; P Ventura

2002-01-01

94

Properties of lipophilic matrix tablets containing phenylpropanolamine hydrochloride prepared by hot-melt extrusion.  

PubMed

The objective of the present study was to investigate the influence of formulation factors on the physical properties of hot-melt extruded granules and compressed tablets containing wax as a thermal binder/retarding agent, and to compare the properties of granules and tablets with those prepared by a high-shear melt granulation (MG) method. Powder blends containing phenylpropanolamine hydrochloride, Precirol and various excipients were extruded in a single-screw extruder at open-end discharge conditions. The extrudates were then passed through a 14-mesh screen to form granules. The extrusion conditions and the optimum amount of wax to function as the thermal binder were dependent on the properties of the filler excipients. At the same wax level, drug release from tablets decreased in the order of using microcrystalline cellulose (MCC), lactose and Emcompress as the filler excipient. The observed differences in the dissolution properties of the tablets were due to the differences in the solubility, swellability and density of the filler excipients. Replacing Precirol with Sterotex K, a higher melting point wax, resulted in slightly increased dissolution rates, when the extrusion was performed at the same temperature conditions. Hot-melt extruded granules were observed to be less spherical than high-shear melt granules and showed lower values of bulk/tap densities. However, tablets containing MCC or lactose granules prepared by hot-melt extrusion (HME) exhibited higher hardness values. Slower drug release rates were found for tablets containing MCC by HME compared with MG. Analysis of the hot-melt extruded granules showed better drug content uniformity among granules of different size ranges compared with high-shear melt granules, resulting in a more reproducible drug release from the corresponding tablets. PMID:11522484

Liu, J; Zhang, F; McGinity, J W

2001-09-01

95

The use of response surface methodology for the formulation and optimization of salbutamol sulfate hydrophilic matrix sustained release tablets.  

PubMed

The objective of this study was to develop a hydrophilic matrix formulation with in vitro release characteristics similar to Asthalin(®) tablets and that would sustain the release of salbutamol sulfate over a 12-h period. A central composite design was used as the framework for manufacturing formulations that may be used to understand the relationships between polymer levels and in vitro release characteristics. Tablets were manufactured using wet granulation with Surelease(®) as the granulating fluid and different levels of Methocel(®) K100M, xanthan gum, and Carbopol(®) 974P as matrix-forming materials. In vitro dissolution testing was conducted using USP Apparatus 3 and samples were analyzed using a validated reversed-phase HPLC method. The results revealed that the levels and types of polymers had a significant impact on the rate of drug release from these formulations and that it was possible to optimize the levels of matrix-forming polymers to achieve the desired release characteristics. Statistical design and response surface methodology have been successfully used to understand and optimize formulation factors and interactions that impact the in vitro release characteristics of salbutamol sulfate from a potential multisource sustained release dosage form. PMID:21428702

Chaibva, Faith A; Walker, Roderick B

2011-03-23

96

Porous carrier based floating granular delivery system of repaglinide.  

PubMed

A floating granular delivery system consisting of calcium silicate (CS) as porous carrier; repaglinide (Rg), an oral hypoglycemic agent; and hydroxypropyl methylcellulose K4M (HPMC K4M), ethyl cellulose (EC) and carbopol 940 (CP940) as matrix forming polymers was prepared and evaluated for its gastro-retentive and controlled release properties. The effect of various formulation and process variables on the particle morphology, micromeritic properties, in vitro floating behavior, drug content (%) and in vitro drug release was studied. The transit of floating granules of optimized formulation in the gastrointestinal (GI) tract was monitored by gamma scintigraphy in albino rabbits. The optimized formulation was compared in vivo with lactose granules (RgSCLG) prepared from identical polymers with their optimized composition ratio. Repaglinide-loaded optimized formulation was orally administered to albino rabbits and blood samples collected were used to determine pharmacokinetic parameters of Rg from floating granular formulation. Results were compared with pharmacokinetic parameters of marketed tablet formulation of Rg. The optimized formulation (RgSCG4) demonstrated favorable in vitro floating and release characteristics. Prolonged gastric residence time (GRT) of over 6 hr was achieved in all subjects for calcium silicate based floating granules of Rg. The relative bioavailability of Rg-loaded floating granules increased 3.8-fold in comparison to that of its marketed capsule. The designed system, combining excellent buoyant ability and suitable drug release pattern, offered clear advantages in terms of increased bioavailability of repaglinide. PMID:17523003

Jain, Sunil K; Agrawal, Govind P; Jain, Narendra K

2007-04-01

97

Controlled Release Matrix Tablets of Olanzapine: Influence of Polymers on the In Vitro Release and Bioavailability  

Microsoft Academic Search

Controlled-release (CR) tablet formulation of olanzapine was developed using a binary mixture of Methocel® K100 LV-CR and\\u000a Ethocel® standard 7FP premium by the dry granulation slugging method. Drug release kinetics of CR tablet formulations F1,\\u000a F2, and F3, each one suitably compressed for 9-, 12-, and 15-kg hardness, were determined in a dissolution media of 0.1 N\\u000a HCl (pH 1.5) and phosphate

Amir Badshah; Fazal Subhan; Khalid Rauf

2010-01-01

98

Formulation of controlled-release baclofen matrix tablets. II. Influence of some hydrophobic excipients on the release rate and in vitro evaluation.  

PubMed

The aim of this study was to investigate the influence of polymer level and type of some hydrophobic polymers, including hydrogenated castor oil (HCO); Eudragit RS100 (E-RS100); Eudragit L100 (E-L100), and some fillers namely mannitol [soluble filler], Dibasic calcium phosphate dihydrate (Emcompress) and anhydrous dibasic calcium phosphate [insoluble fillers] on the release rate and mechanism of baclofen from matrix tablets prepared by a hot-melt granulation process (wax tablets) and wet granulation process (E-RS100 and E-L100 tablets). Statistically significant differences were found among the drug release profile from different classes of polymeric matrices. Higher polymeric content (40%) in the matrix decreased the release rate of drug because of increased tortuosity and decreased porosity. At lower polymeric level (20%), the rate and extent of drug release was elevated. HCO was found to cause the strongest retardation of drug. On the other hand, replacement of Emcompress or anhydrous dibasic calcium phosphate for mannitol significantly retarded the release rate of baclofen, except for E-L100 (pH-dependent polymer). Emcompress surface alkalinity and in-situ increase in pH of the matrix microenvironment enhanced the dissolution and erosion of these matrix tablets. The release kinetics was found to be governed by the type and content of the excipients (polymer or filler). The prepared tablets showed no significant change in drug release rate when stored at ambient room conditions for 6 months. PMID:18500558

Abdelkader, Hamdy; Youssef Abdalla, Ossama; Salem, Hesham

2008-05-24

99

Study on sustained-release metformin hydrochloride from matrix tablet: Influence of hydrophilic polymers and in vitro evaluation  

PubMed Central

The overall objective of the present work was to develop an oral sustained-release (SR) metformin tablet prepared by the direct compression method, using hydrophilic hydroxylpropylmethylcellulose (HPMC) and Guar gum polymer alone and in combination at different concentrations. Metformin hydrochloride (HCl), a biguanide, has a relatively short plasma half-life and low absolute bioavailability. All the batches were evaluated for thickness, weight variation, hardness and drug content uniformity and in vitro drug release. Mean dissolution time is used to characterize the drug release rate from a dosage form, and indicates the drug release-retarding efficiency of the polymer. The hydrophilic matrix of HPMC alone could not control the Metformin release effectively for 12 h whereas when combined with Guar gum, it could slow down the release of drug and, thus, can be successfully employed for formulating SR matrix tablets. Fitting the data to the Korsmeyer equation indicated that diffusion along with erosion could be the mechanism of drug release. Similarity factor ƒ2 values suggest that the test and reference profiles are identical.

Wadher, Kamlesh J; Kakde, Rajendra B; Umekar, Milind J

2011-01-01

100

Formulation development and optimization of sustained release matrix tablet of Itopride HCl by response surface methodology and its evaluation of release kinetics.  

PubMed

The objective of this present investigation was to develop and formulate sustained release (SR) matrix tablets of Itopride HCl, by using different polymer combinations and fillers, to optimize by Central Composite Design response surface methodology for different drug release variables and to evaluate drug release pattern of the optimized product. Sustained release matrix tablets of various combinations were prepared with cellulose-based polymers: hydroxy propyl methyl cellulose (HPMC) and polyvinyl pyrolidine (pvp) and lactose as fillers. Study of pre-compression and post-compression parameters facilitated the screening of a formulation with best characteristics that underwent here optimization study by response surface methodology (Central Composite Design). The optimized tablet was further subjected to scanning electron microscopy to reveal its release pattern. The in vitro study revealed that combining of HPMC K100M (24.65 MG) with pvp(20 mg)and use of LACTOSE as filler sustained the action more than 12 h. The developed sustained release matrix tablet of improved efficacy can perform therapeutically better than a conventional tablet. PMID:23960836

Bose, Anirbandeep; Wong, Tin Wui; Singh, Navjot

2012-04-12

101

Formulation and in vitro studies of a fixed-dose combination of a bilayer matrix tablet containing metformin HCl as sustained release and glipizide as immediate release.  

PubMed

The emerging new fixed dose combination of metformin hydrocholride (HCl) as sustained release and glipizide as immediate release were formulated as a bilayer matrix tablet using hydroxy propyl methyl cellulose (HPMC) as the matrix-forming polymer, and the tablets were evaluated via in vitro studies. Three different grades of HPMC (HPMC K 4M, HPMC K 15M, and HPMC K 100M) were used. All tablet formulations yielded quality matrix preparations with satisfactory tableting properties. In vitro release studies were carried out at a phosphate buffer of pH 6.8 with 0.75% sodium lauryl sulphate w/v using the apparatus I (basket) as described in the United States Pharmacopeia (2000). The release kinetics of metformin were evaluated using the regression coefficient analysis. There was no significant difference in drug release for different viscosity grade of HPMC with the same concentration. Tablet thus formulated provided sustained release of metformin HCl over a period of 8 hours and glipizide as immediate release. PMID:18363146

Mandal, Uttam; Pal, Tapan Kumar

2008-03-01

102

Formulation development and optimization of sustained release matrix tablet of Itopride HCl by response surface methodology and its evaluation of release kinetics  

PubMed Central

The objective of this present investigation was to develop and formulate sustained release (SR) matrix tablets of Itopride HCl, by using different polymer combinations and fillers, to optimize by Central Composite Design response surface methodology for different drug release variables and to evaluate drug release pattern of the optimized product. Sustained release matrix tablets of various combinations were prepared with cellulose-based polymers: hydroxy propyl methyl cellulose (HPMC) and polyvinyl pyrolidine (pvp) and lactose as fillers. Study of pre-compression and post-compression parameters facilitated the screening of a formulation with best characteristics that underwent here optimization study by response surface methodology (Central Composite Design). The optimized tablet was further subjected to scanning electron microscopy to reveal its release pattern. The in vitro study revealed that combining of HPMC K100M (24.65 MG) with pvp(20 mg)and use of LACTOSE as filler sustained the action more than 12 h. The developed sustained release matrix tablet of improved efficacy can perform therapeutically better than a conventional tablet.

Bose, Anirbandeep; Wong, Tin Wui; Singh, Navjot

2012-01-01

103

Formulation and in vitro evaluation of ibuprofen-carbopol ® 974P-NF controlled release matrix tablets III: influence of co-excipients on release rate of the drug  

Microsoft Academic Search

In order to assess the potential of carbopol® 974P-NF as matrix material in hydrophilic matrix tablets containing a slightly water-soluble drug, ibuprofen (IBF), controlled release matrix tablets of ibuprofen and carbopol® 974P-NF, at different drug to polymer ratios, were prepared by the direct compression method. The influence of the concentration of the matrix material (carbopol® 974P) and several co-excipients (lactose,

Gul Majid Khan; Zhu Jiabi

1998-01-01

104

Gamma scintigraphic studies on guar gum matrix tablets for colonic drug delivery in healthy human volunteers  

Microsoft Academic Search

A novel colon-specific drug delivery system based on a polysaccharide, guar gum, was evaluated by conducting gamma scintigraphic studies using technetium-99m-DTPA as tracer, in six healthy male human volunteers. Scintigraphs taken at regular intervals have shown that some amount of tracer present on the surface of the tablets was released in stomach and small intestine and the bulk of the

Y. S. R Krishnaiah; S Satyanarayana; Y. V Rama Prasad; S Narasimha Rao

1998-01-01

105

Formulation development and evaluation of Diltiazem HCl sustained release matrix tablets using HPMC K4M and K100M.  

PubMed

The aim of this study was to develop a sustained release hydrophilic matrix tablet of Diltiazem HCl and evaluates the effect of formulation variables (e.g. lubricant, binder, polymer content and viscosity grades of HPMC) on drug release. Twelve different formulations (F1-F12) were prepared by direct compression. The results of the physical parameters and assay were found to be within the acceptable range. Rate of drug release was found to be slow as the fraction of the polymer was increased from 20-50%. The drug release rate from tablets containing K4M was effectively controlled by increasing the talc concentration, whereas the burst effect was reduced by increasing binder content. The drug release was higher with K4M as compare to K100M. Model-dependent and independent methods were used for data analysis and the best results were observed for K4M in Higuchi (R(2)=0.9903-0.9962) and K100M in Baker and Lonsdale (R(2)=0.9779-0.9941). The release mechanism of all formulations was non-Fickian. F7 (50% K4M, 2% talc, 10% Avicel PH101) and F11 (40% K100M) were very close to targeted release profile. F12 (50% K100M) exhibited highest degree of swelling and lowest erosion. The f1 and f2 test were performed taking F11 as a reference formulation. PMID:23811439

Qazi, Faaiza; Shoaib, Muhammad Harris; Yousuf, Rabia Ismail; Qazi, Tanveer Mustafa; Mehmood, Zafar Alam; Hasan, S M Farid

2013-07-01

106

Influence of admixed citric acid and physiological variables on the vinpocetine release from sodium alginate compressed matrix tablets.  

PubMed

In this study, the controlled release matrix tablets of vinpocetine were prepared by direct compression using sodium alginate (SAL) as hydrophilic polymer and different amounts of citric acid as hydrosoluble acidic excipient to set up a system bringing about zero-order release of this drug in distilled water containing 0.5% sodium dodecyl sulfate. At the critical content of admixed citric acid (60 mg/tab.), the lowest drug-release rate was observed. In order to explain the effect of this critical content on drug-release rate from SAL matrices, investigation of the possibility of interaction of citric acid with SAL was performed using differential scanning calorimetric analysis and infrared analysis, which confirmed the existence of direct citric acid-SAL interaction when these two excipients came in contact with water. A zero-order drug-release system could be obtained by regulating the ratio of citric acid-to-SAL and the capacity of this system in controlling drug-release rate depended on the extent of interaction between citric acid and SAL. It is worth noticing that pH and the ionic strength of the dissolution medium were found to exert an influence on the drug-release performance of SAL tablets. PMID:21417613

Nie, Shufang; Wu, Jie; Liu, Hui; Pan, Weisan; Liu, Yanli

2011-03-21

107

The consequence of the chemical composition of HPMC in matrix tablets on the release behaviour of model drug substances having different solubility  

Microsoft Academic Search

This study investigates the effect of the chemical heterogeneity of hydroxypropyl methylcellulose (HPMC) on the release of model drug substances from hydrophilic matrix tablets. The hypothesis was that the release of drug substances could be influenced by possible interactions with HPMC batches having different chemical heterogeneity. The cloud point of the most heterogeneous batch was more affected by the model

Anna Viridén; Bengt Wittgren; Anette Larsson

2011-01-01

108

Effect of formulation parameters and drug-polymer interactions on drug release from starch acetate matrix tablets.  

PubMed

The aim of this study was to determine, whether interactions between a drug and hydrophobic polymer matrix are present, and if so, how they affect the drug release. In addition, the most important formulation parameters, for example porosity or structure of the tablet, which have the greatest impact on drug release, were defined. Six different drug compounds, that is allopurinol, acyclovir, metronidazole, paracetamol, salicylamide and theophylline, were used in different formulations with hydrophobic starch acetate (DS 2.7) as a matrix forming polymer. Results indicate that the formulation parameters describing directly or indirectly the structure of the matrix, such as porosity, compaction force and the particle size fraction of the filler-binder, have the strongest impact on drug release. The contribution of drug property based variables is not as high as formulation parameters, but they cannot be overlooked. The contribution of water solubility and dissolution rate of the compound are obvious, but there are other significant parameters, which describe the hydrophobic and hydrophilic regions of the molecule, that also affect the drug release. This can be seen especially with the salicylamide: compound which appears to have a strong and sufficiently high hydrophobic region that interacts with starch acetate and impairs the drug release. PMID:19177516

Pajander, Jari; Korhonen, Ossi; Laamanen, Maria; Ryynänen, Eeva-Leena; Grimsey, Ian; van Veen, Bert; Ketolainen, Jarkko

2009-10-01

109

Evaluation of a matrix tablet prepared with polyacrylamide-g-sodium alginate co-polymers and their partially hydrolyzed co-polymers for sustained release of diltiazem hydrochloride.  

PubMed

Diltiazem hydrochloride (DTZ) matrix tablets were prepared using polyacrylamide-grafted sodium alginate (PAam-g-SA) co-polymers having different percentages of grafting and their partially hydrolyzed products with a view to achieve sustained release of the highly water-soluble drug. PAam-g-SA co-polymers having different percentages of grafting were synthesized by free radical polymerization using acrylamide (Aam) as monomer and ammonium persulphate (APS) as initiator, and the resulting co-polymers were subjected to alkaline hydrolysis to produce their corresponding partially hydrolyzed co-polymers. Matrix tablets of DTZ were prepared by wet granulation using either PAam-g-SA co-polymers or partially hydrolyzed PAam-g-SA co-polymers. The effect of percentage grafting, drug load and calcium gluconate (CG), used as excipient, was studied in simulated gastrointestinal fluid. While the tablets prepared using the co-polymer having higher percentages of grafting provided faster drug release (100% in 5.5 h), the tablets prepared with the corresponding hydrolyzed co-polymer released the drug slowly (71% in 12 h). This behaviour in release appeared to be controlled by the relative magnitude of the viscosity and the swelling capacity of the copolymers. Moreover, increase in drug load tended to decrease the drug release from all types of tablets and increase in the amount of CG increased the drug release. FT-IR and DSC studies revealed the absence of any interaction between the drug and the co-polymers. The matrix tablet made of partially hydrolyzed graft co-polymer having the highest percentage of grafting provided the most sustained release of the drug. PMID:20557689

Mandal, Sanchita; Ray, Rajat; Basu, Sanat K; Sa, Biswanath

2010-06-16

110

Physical properties and in vivo bioavailability in human volunteers of isradipine using controlled release matrix tablet containing self-emulsifying solid dispersion.  

PubMed

Poorly water-soluble drug with a short half-life such as isradipine (IDP) offer challenges in the controlled release formulation because of low dissolution rate and poor bioavailability. Self-emulsifying solid dispersions (SESD) of IDP consisted of surfactant and fatty acid in poloxamer 407 (POX 407) as a carrier and were manufactured by the melting method. Then, controlled release HPMC matrix tablet containing SESD were prepared via direct compression. The dissolution behaviors and in vivo bioavailability of controlled release matrix tablet in healthy human volunteers were investigated. The physical properties of solid dispersion were also examined using differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD) and scanning electron microscopy (SEM). It was shown that structure of IDP was amorphous in the solid dispersion. The dissolution rate of IDP from SESD was markedly enhanced because of increased solubility and wetting effect. Controlled release HPMC matrix tablets containing SESD released drug in a controlled manner and were stable during storage over 3 months at 40 °C/75% RH. Furthermore, the tablet containing 5mg IDP SESD showed significantly increased oral bioavailability and extended plasma concentration compared with the marketed 5 mg Dynacirc(®) capsule. A combined method of solid dispersion and controlled release technology could provide versatile dosage formulations containing IDP with poor water solubility and short half-life. PMID:23612354

Tran, Phuong Ha-Lien; Tran, Thao Truong-Dinh; Piao, Zong Zhu; Vo, Toi Van; Park, Jun Bom; Lim, Jisung; Oh, Kyung Teak; Rhee, Yun-Seok; Lee, Beom-Jin

2013-04-20

111

Regulating drug release behavior and kinetics from matrix tablets based on fine particle-sized ethyl cellulose ether derivatives: an in vitro and in vivo evaluation.  

PubMed

The design and fabrication of sustained/controlled release dosage forms, employing new excipients capable of extending/controlling the release of drugs from the dosage forms over prolonged periods, has worked well in achieving optimally enhanced therapeutic levels of the drugs. In this sense, the objective of this study was to investigate the suitability of selected cellulose ether derivatives for use in direct compression (DC) and as efficient drug release controlling agents. Controlled release matrix tablets of ciprofloxacin were prepared at different drug-to-polymer (D : P) ratios by direct compression using a fine particle sized ethylcellulose ether derivative (ETHOCEL Standard Premium 7FP) as rate controlling polymer. The tablets obtained were evaluated for various physico-chemical characteristics and in-vitro drug release studies were conducted in phosphate buffer (pH 7.4) using PharmaTest dissolution apparatus at constant temperature of 37 °C ± 0.1. Similarity factor f(2) was employed to the release profiles of test formulations and were compared with marketed ciprofloxacin conventional tablets. Drug release mechanism and the kinetics involved were investigated by fitting the release profile data to various kinetic models. It was found that with increasing the proportion of ethylcellulose ether derivative in the matrix, the drug release was significantly extended up to 24 hours. The tablets exhibited zero order or nearly zero order drug transport mechanism. In vivo drug release performance of the developed controlled release tablets and reference conventional tablets containing ciprofloxacin were determined in rabbit serum according to randomized two-way crossover study design using High Performance Liquid Chromatography. Several bioavailability parameters of both the test tablets and conventional tablets including C(max?), T(max?) and AUC(0-t) were compared which showed an optimized C(max?) and T(max?) (P < 0.05). A good correlation was obtained between in vitro drug release and in vivo drug absorption with correlation value (R(2) = 0.934). Relative bioavailability was found to be 93%. Reproducibility of manufacturing process and accelerated stability of the developed tablets were performed in stability chamber at 40 ± 2°C and 75 ± 5% relative humidity for a period of 6 months and were found to be stable throughout the stability period. PMID:22649325

Shah, Kifayat Ullah; Khan, Gul Majid

2012-04-29

112

Regulating Drug Release Behavior and Kinetics from Matrix Tablets Based on Fine Particle-Sized Ethyl Cellulose Ether Derivatives: An In Vitro and In Vivo Evaluation  

PubMed Central

The design and fabrication of sustained/controlled release dosage forms, employing new excipients capable of extending/controlling the release of drugs from the dosage forms over prolonged periods, has worked well in achieving optimally enhanced therapeutic levels of the drugs. In this sense, the objective of this study was to investigate the suitability of selected cellulose ether derivatives for use in direct compression (DC) and as efficient drug release controlling agents. Controlled release matrix tablets of ciprofloxacin were prepared at different drug-to-polymer (D?:?P) ratios by direct compression using a fine particle sized ethylcellulose ether derivative (ETHOCEL Standard Premium 7FP) as rate controlling polymer. The tablets obtained were evaluated for various physico-chemical characteristics and in-vitro drug release studies were conducted in phosphate buffer (pH 7.4) using PharmaTest dissolution apparatus at constant temperature of 37°C ± 0.1. Similarity factor f2 was employed to the release profiles of test formulations and were compared with marketed ciprofloxacin conventional tablets. Drug release mechanism and the kinetics involved were investigated by fitting the release profile data to various kinetic models. It was found that with increasing the proportion of ethylcellulose ether derivative in the matrix, the drug release was significantly extended up to 24 hours. The tablets exhibited zero order or nearly zero order drug transport mechanism. In vivo drug release performance of the developed controlled release tablets and reference conventional tablets containing ciprofloxacin were determined in rabbit serum according to randomized two-way crossover study design using High Performance Liquid Chromatography. Several bioavailability parameters of both the test tablets and conventional tablets including Cmax?, Tmax? and AUC0-t were compared which showed an optimized Cmax? and Tmax? (P < 0.05). A good correlation was obtained between in vitro drug release and in vivo drug absorption with correlation value (R2 = 0.934). Relative bioavailability was found to be 93%. Reproducibility of manufacturing process and accelerated stability of the developed tablets were performed in stability chamber at 40 ± 2°C and 75 ± 5% relative humidity for a period of 6 months and were found to be stable throughout the stability period.

Shah, Kifayat Ullah; Khan, Gul Majid

2012-01-01

113

Time-controlled pulse-drug release from dry-coated wax matrix tablets for colon drug delivery.  

PubMed

This study aimed to prepare a colon drug delivery system using dry-coated time-controlled disintegration wax matrix tablets. Indomethacin was used as a model drug. Behenic acid and lactose were used as coating materials. The effects of lactose content and pH of the dissolution medium on drug release were investigated. The porosity and the tortuosity of the surface matrix layer were calculated. Four formulations of wax matrices containing different percentages of lactose in the surface layer, i.e. 70, 65, 60 and 55, were prepared. The lag times of indomethacin release from the matrices in 0.05 M phosphate buffer pH 7.4 were 50, 162, 294 and 539 minutes for formulations containing 70, 65, 60 and 55% lactose, respectively. The release of drug from formulations containing lactose in the range of 60-70% in different media, i.e. 0.05 M phosphate buffer pH 7.4, 0.05 M alkaline borate buffer pH 8.5 and in the case of pH changed media from pH 1.3 to pH 7.4, was not different (p=0.1). This implies that the different environment in the gastro-intestinal tract will not affect the release of this delivery device. The required lag time period can be met by varying the amount of lactose. PMID:15299241

Peerapattana, Jomjai; Otsuka, Kuniko; Otsuka, Makoto

2004-01-01

114

Jejunal ulceration and stricture due to wax-matrix potassium chloride tablets and amitriptyline.  

PubMed

A 68-year-old woman presented with abdominal distention of several weeks duration and an acute small bowel obstruction. For several years she had been prescribed amitriptyline 150 mg/d, L-thyroxine 100 micrograms/d, and digoxin 0.25 mg/d. For the previous year she had been taking hydrochlorothiazide 50 mg/d and wax-matrix KCl 20 mEq/d for hypertension. At surgery a "napkin-ring" stricture of the midjejunum was found. It had microscopic features consistent with KCl local toxicity. It is speculated that delayed gastrointestinal motility secondary to amitriptyline predisposed this patient to wax-matrix KCl toxicity and that this potential side effect be considered when prescribing wax-matrix KCl. PMID:3429685

Bronson, D L; Gamelli, R L

1987-10-01

115

Controlled Drug Release of Highly Water-Soluble Pentoxifylline from Time-Limit Disintegration-Type Wax Matrix Tablets  

Microsoft Academic Search

A pulsatile drug release system with a dry-coated tablet containing pentoxifylline was investigated for controlling drug release\\u000a in the gastrointestinal tract. The system consisted of a core tablet with disintegrator and outer layer, which obtained compression\\u000a from the ground mixtures of pentoxifylline and behenic acid. Drug release from a dry-coated tablet was investigated at 37°C\\u000a in JPXII 2nd fluid at

Makoto Otsuka; Yoshihisa Matsuda

1994-01-01

116

Formulation of Controlled-Release Baclofen Matrix Tablets II: Influence of Some Hydrophobic Excipients on the Release Rate and In Vitro Evaluation  

Microsoft Academic Search

The aim of this study was to investigate the influence of polymer level and type of some hydrophobic polymers, including hydrogenated\\u000a castor oil (HCO); Eudragit RS100 (E-RS100); Eudragit L100 (E-L100), and some fillers namely mannitol [soluble filler], Dibasic\\u000a calcium phosphate dihydrate (Emcompress) and anhydrous dibasic calcium phosphate [insoluble fillers] on the release rate and\\u000a mechanism of baclofen from matrix tablets

Hamdy Abdelkader; Ossama Youssef Abdalla; Hesham Salem

2008-01-01

117

Development of novel sustained-release system, disintegration-controlled matrix tablet (DCMT) with solid dispersion granules of nilvadipine (II): In vivo evaluation  

Microsoft Academic Search

A novel sustained-release (SR) system, disintegration-controlled matrix tablet (DCMT), was developed for poorly water-soluble drugs. DCMT, consisting of wax and solid dispersion (SD) granules containing a disintegrant, could control the release of nilvadipine (NiD), a model compound, by its disintegration. In the present study, two DCMTs (DCMT-1 and DCMT-2) with different release rates of NiD were orally administered to beagle

Nobuyuki Tanaka; Keiji Imai; Kazuto Okimoto; Satoshi Ueda; Yuji Tokunaga; Rinta Ibuki; Kazutaka Higaki; Toshikiro Kimura

2006-01-01

118

Comparison of Release-Controlling Efficiency of Polymeric Coating Materials Using Matrix-type Casted Films and Diffusion-Controlled Coated Tablet  

PubMed Central

Polymeric coating materials have been widely used to modify release rate of drug. We compared physical properties and release-controlling efficiency of polymeric coating materials using matrix-type casted film and diffusion-controlled coated tablet. Hydroxypropylmethyl cellulose (HPMC) with low or high viscosity grade, ethylcellulose (EC) and Eudragit® RS100 as pH-independent polymers and Eudragit S100 for enteric coatings were chosen to prepare the casted film and coated tablet. Tensile strength and contact angle of matrix-type casted film were invariably in the decreasing order: EC> Eudragit S100> HPMC 100000> Eudragit RS100>HPMC 4000. There was a strong linear correlation between tensile strength and contact angle of the casted films. In contrast, weight loss (film solubility) of the matrix-type casted films in three release media (gastric, intestinal fluid and water) was invariably in the increasing order: EC?matrix-type casted films was EC?>?HPMC 100000?>?Eudragit RS100?>?HPMC 4000?>?Eudragit S100. Interestingly, diffusion-controlled coated tablet also followed this rank order except Eudragit S100 although release profiles and lag time were highly dependent on the coating levels and type of polymeric coating materials. EC and Eudragit RS100 produced sustained release while HPMC and Eudragit S100 produced pulsed release. No molecular interactions occurred between drug and coating materials using 1H-NMR analysis. The current information on release-controlling power of five different coating materials as matrix carrier or diffusion-controlled film could be applicable in designing oral sustained drug delivery.

Piao, Zong-Zhu; Lee, Kyoung-Ho; Kim, Dong-Jin; Lee, Hong-Gu; Lee, Jaehwi; Oh, Kyung Taek

2010-01-01

119

Floating Stones  

Microsoft Academic Search

IN reference to Dr. Nordenskiold's communication re ``Floating Stones'' (No. 1577, vol. lxi.) it is a common thing to see grains of sand and small shells floating upon the waters of seas and estuaries, &c, when the surfaces are unagitated. The sand-grains must be dry; they are, therefore, only lifted and floated off by a rising tide after exposure to

Cecil Carus-Wilson

1900-01-01

120

Preparation and Characterization of Nicotine–Magnesium Aluminum Silicate Complex-Loaded Sodium Alginate Matrix Tablets for Buccal Delivery  

Microsoft Academic Search

Nicotine (NCT) buccal tablets consisting of sodium alginate (SA) and nicotine–magnesium aluminum silicate (NCT–MAS) complexes\\u000a acting as drug carriers were prepared using the direct compression method. The effects of the preparation pH levels of the\\u000a NCT–MAS complexes and the complex\\/SA ratios on NCT release, permeation across mucosa, and mucoadhesive properties of the tablets\\u000a were investigated. The NCT–MAS complex-loaded SA tablets

Sopaphan Kanjanabat; Thaned Pongjanyakul

2011-01-01

121

Development of novel sustained-release system, disintegration-controlled matrix tablet (DCMT) with solid dispersion granules of nilvadipine (II): in vivo evaluation.  

PubMed

A novel sustained-release (SR) system, disintegration-controlled matrix tablet (DCMT), was developed for poorly water-soluble drugs. DCMT, consisting of wax and solid dispersion (SD) granules containing a disintegrant, could control the release of nilvadipine (NiD), a model compound, by its disintegration. In the present study, two DCMTs (DCMT-1 and DCMT-2) with different release rates of NiD were orally administered to beagle dogs, and in vivo absorption of NiD from DCMTs was compared with that from immediate-release (IR) tablets. DCMTs successfully sustained the absorption of NiD longer than IR tablets, while they did not decrease the bioavailability of NiD. DCMT-2, providing the slower release of NiD than DCMT-1, prolonged the absorption longer than DCMT-1. In vivo absorption profiles of NiD from DCMTs were significantly correlated with in vitro release profiles, suggesting that the release property from DCMTs would maintain regardless of the change in physiological condition through the gastrointestinal tract. Furthermore, the food intake did not affect the absorption of NiD after oral administration of DCMT-2. The present results strongly indicate that the DCMT system would be a promising SR system, which could improve the solubility and sustain the absorption of poorly water-soluble drugs. PMID:16545477

Tanaka, Nobuyuki; Imai, Keiji; Okimoto, Kazuto; Ueda, Satoshi; Tokunaga, Yuji; Ibuki, Rinta; Higaki, Kazutaka; Kimura, Toshikiro

2006-03-20

122

Development of Controlled-Release Matrix Tablet of Risperidone: Influence of Methocel®- and Ethocel®Based Novel Polymeric Blend on In Vitro Drug Release and Bioavailability  

Microsoft Academic Search

Controlled-release (CR) matrix tablet of 4 mg risperidone was developed using flow bound dry granulation–slugging method to\\u000a improve its safety profile and compliance. Model formulations F1, F2, and F3, consisting of distinct blends of Methocel® K100\\u000a LV-CR and Ethocel® standard 7FP premium, were slugged. Each batch of granules (250–1,000 ?m), obtained by crushing the slugs,\\u000a was divided into three portions after lubrication

Amir Badshah; Fazal Subhan; Khalid Rauf; Nadeem Irfan Bukhari; Kifayatullah Shah; Samiullah Khan; Zia Ahmed; Ihsanullah Khan

2011-01-01

123

Egg Float  

NSDL National Science Digital Library

In this activity, learners explore if an egg floats or sinks in salt water. Use this quick demonstration to illustrate how density affects whether things sink or float. Relate this lesson to why swimming in the ocean (saltwater) can be easier than swimming in a lake.

Houston, Children'S M.

2013-05-15

124

Floating Egg  

NSDL National Science Digital Library

In this activity, make an egg float in water, not by changing the egg itself, but by changing the water. Explore density, solutions, and why objects float easier in the Gulf of Mexico than in a bathtub. This activity guide includes a step-by-step instructional video.

Center, Saint L.

2013-01-17

125

Floating Stones  

Microsoft Academic Search

THE correspondence on ``Floating Stones'' brings to my mind a phenomenon I often noticed about ten years ago, when my work caused me to spend a good deal of time on the upper reaches of the River Mersey, of patches of earth floating down the river on the surface of the water. This occurred during the early part of the

A. W. Brightmore

1900-01-01

126

Optimization of metformin HCl 500 mg sustained release matrix tablets using Artificial Neural Network (ANN) based on Multilayer Perceptrons (MLP) model.  

PubMed

The aim of the present study was to apply the simultaneous optimization method incorporating Artificial Neural Network (ANN) using Multi-layer Perceptron (MLP) model to the development of a metformin HCl 500 mg sustained release matrix tablets with an optimized in vitro release profile. The amounts of HPMC K15M and PVP K30 at three levels (-1, 0, +1) for each were selected as casual factors. In vitro dissolution time profiles at four different sampling times (1 h, 2 h, 4 h and 8 h) were chosen as output variables. 13 kinds of metformin matrix tablets were prepared according to a 2(3) factorial design (central composite) with five extra center points, and their dissolution tests were performed. Commercially available STATISTICA Neural Network software (Stat Soft, Inc., Tulsa, OK, U.S.A.) was used throughout the study. The training process of MLP was completed until a satisfactory value of root square mean (RSM) for the test data was obtained using feed forward back propagation method. The root mean square value for the trained network was 0.000097, which indicated that the optimal MLP model was reached. The optimal tablet formulation based on some predetermined release criteria predicted by MLP was 336 mg of HPMC K15M and 130 mg of PVP K30. Calculated difference (f(1) 2.19) and similarity (f(2) 89.79) factors indicated that there was no difference between predicted and experimentally observed drug release profiles for the optimal formulation. This work illustrates the potential for an artificial neural network with MLP, to assist in development of sustained release dosage forms. PMID:18239298

Mandal, Uttam; Gowda, Veeran; Ghosh, Animesh; Bose, Anirbandeep; Bhaumik, Uttam; Chatterjee, Bappaditya; Pal, Tapan Kumar

2008-02-01

127

Preparation of controlled release tablets of TA-5707F with wax matrix type and their in vivo evaluation in beagle dogs.  

PubMed

Studies on controlled release dosage forms were conducted by using waxy materials for a newly developed anti-allergy drug, 6-methyl-N-(1H-tetrazol-5-yl)-2-pyridinecarboxamide (TA-5707F), which is not maintained at an effective level in blood for a long duration. Four kinds of tablets were prepared by changing the amount of hydrogenated oil (K3 wax) and polyethyleneglycol-6000 in the tablets. Then, they were administered orally to beagle dogs, and the TA-5707F concentration in the plasma was determined by a HPLC method. The pharmacokinetic parameters were estimated and compared with the results of the in vitro dissolution test determined by the JP paddle method and by the disintegration method. The linearity between the in vivo mean dissolution time (MDT) and in vitro MDT was good in both in vitro dissolution methods. However, the MDTs obtained by the disintegration method were one-third of the in vivo MDT, while those obtained by the paddle methods were 3 times higher. This suggests that both the diffusion of TA-5707F through the waxy matrix and the erosion of the wax matrix caused by the gastrointestinal (GI) tract mobility contributed to the in vivo dissolution mechanism. The blood levels were very low when the tablet was administered after giving food. The prolongation of resident time in the stomach and the low solubility of TA-5707F in an acidic medium seemed to be related to the phenomena. By the depression of GI motility using propantheline bromide, the blood levels could be markedly prolonged and the area under the plasma concentration-time curve (AUC) increased 1.3 times. PMID:7581255

Yamakita, H; Maejima, T; Osawa, T

1995-07-01

128

Controlled-release matrix tablets of ibuprofen using cellulose ethers and carrageenans: effect of formulation factors on dissolution rates  

Microsoft Academic Search

The study was conducted to investigate the effects of carrageenans, and cellulose ethers on the drug release rates of ibuprofen controlled-release tablet matrices prepared by direct compression. Polymer blends containing carrageenans or cellulose ethers were used for the formulation and the effect of varying the polymer concentration on the release of the drug was studied. Other factors such as changes

Jayanti Nerurkar; H. W. Jun; J. C. Price; M. O. Park

2005-01-01

129

The application of generalized regression neural network in the modeling and optimization of aspirin extended release tablets with Eudragit RS PO as matrix substance.  

PubMed

The objective of this work is to use a generalized regression neural network (GRNN) in the design of extended-release aspirin tablets. As model formulations, 10 kinds of aspirin matrix tablets were prepared. Eudragit RS PO was used as matrix substance. The amount of Eudragit RS PO and compression pressure were selected as causal factors. In-vitro dissolution-time profiles at four different sampling times, as well as coefficients n (release order) and log k (release constant) from the Peppas equation were estimated as release parameters. A set of release parameters and causal factors were used as tutorial data for the GRNN and analyzing using a computer. A GRNN model was constructed. The optimized GRNN model was used for prediction of formulation with desired in vitro drug release. For two tested formulations there was very good agreement between the GRNN predicted and observed in vitro profiles and estimated coefficients. Calculated difference (f(1)) and similarity (f(2)) factors indicate that there is no difference between predicted and experimental observed drug release profiles. This work illustrates the potential for an artificial neural network, GRNN, to assist in development of extended-release dosage forms. This method can be employed to achieve a desired in vitro dissolution profile. PMID:12175738

Ibri?, Svetlana; Jovanovi?, Milica; Djuri?, Zorica; Parojci?, Jelena; Solomun, Ljiljana

2002-08-21

130

Graft copolymers of ethyl methacrylate on waxy maize starch derivatives as novel excipients for matrix tablets: drug release and fronts movement kinetics.  

PubMed

A previous paper deals with the physicochemical and technological characterization of novel graft copolymers of ethyl methacrylate (EMA) on waxy maize starch (MS) and hydroxypropylstarch (MHS). The results obtained suggested the potential application of these copolymers as excipients for compressed non-disintegrating matrix tablets. Therefore, the purpose of the present study was to investigate the mechanism governing drug release from matrix systems prepared with the new copolymers and anhydrous theophylline or diltiazem HCl as model drugs with different solubility. The influence of the carbohydrate nature, drying procedure and initial pore network on drug release kinetics was also evaluated. Drug release experiments were performed from free tablets. Radial drug release and fronts movement kinetics were also analysed, and several mathematical models were employed to ascertain the drug release mechanisms. The drug release markedly depends on the drug solubility and the carbohydrate nature but is practically not affected by the drying process and the initial matrix porosity. A faster drug release is observed for matrices containing diltiazem HCl compared with those containing anhydrous theophylline, in accordance with the higher drug solubility and the higher friability of diltiazem matrices. In fact, although diffusion is the prevailing drug release mechanism for all matrices, the erosion mechanism seems to have some contribution in several formulations containing diltiazem. A reduction in the surface exposed to the dissolution medium (radial release studies) leads to a decrease in the drug release rate, but the release mechanism is not essentially modified. The nearly constant erosion front movement confirms the behaviour of these systems as inert matrices where the drugs are released mainly by diffusion through the porous structure. PMID:22210473

Marinich, J A; Ferrero, C; Jiménez-Castellanos, M R

2011-12-21

131

Design and optimization of floating drug delivery system of acyclovir.  

PubMed

The purpose of the present work was to design and optimize floating drug delivery systems of acyclovir using psyllium husk and hydroxypropylmethylcellulose K4M as the polymers and sodium bicarbonate as a gas generating agent. The tablets were prepared by wet granulation method. A 3(2) full factorial design was used for optimization of drug release profile. The amount of psyllium husk (X1) and hydroxypropylmethylcellulose K4M (X2) were selected as independent variables. The times required for 50% (t(50%)) and 70% (t(70%)) drug dissolution were selected as dependent variables. All the designed nine batches of formulations were evaluated for hardness, friability, weight variation, drug content uniformity, swelling index, in vitro buoyancy, and in vitro drug release profile. All formulations had floating lag time below 3 min and constantly floated on dissolution medium for more than 24 h. Validity of the developed polynomial equation was verified by designing two check point formulations (C1 and C2). The closeness of predicted and observed values for t(50%) and t(70%) indicates validity of derived equations for the dependent variables. These studies indicated that the proper balance between psyllium husk and hydroxypropylmethylcellulose K4M can produce a drug dissolution profile similar to the predicted dissolution profile. The optimized formulations followed Higuchi's kinetics while the drug release mechanism was found to be anomalous type, controlled by diffusion through the swollen matrix. PMID:21694992

Kharia, A A; Hiremath, S N; Singhai, A K; Omray, L K; Jain, S K

2010-09-01

132

Floating Boats  

ERIC Educational Resources Information Center

|The purpose of this article is to describe a simple laboratory activity in which students collect a series of measurements and then use graphical analysis to determine the nature of the relationship between an object's mass and the volume of water it displaces. In this activity, students explore the relationships between the mass of a floating

Waugh, Michael

2007-01-01

133

Floating Eggs  

Microsoft Academic Search

THE floating eggs which a correspondent in NATURE of July 14 (p. 245) describes and refers to Orthagoriscus, are apparently those of the angler or frog-fish (Lophius piscatorius), which are known to naturalists. They are laid, as Agassiz states (Proc. Amer. Acad. Arts and Sci., vol. xvii. part iii. p. 280), ``embedded in an immense ribbon-shaped band, from 2 to

Edward E. Prince

1887-01-01

134

Floating Boats  

ERIC Educational Resources Information Center

The purpose of this article is to describe a simple laboratory activity in which students collect a series of measurements and then use graphical analysis to determine the nature of the relationship between an object's mass and the volume of water it displaces. In this activity, students explore the relationships between the mass of a floating

Waugh, Michael

2007-01-01

135

Preparation of a Matrix Type Multiple-Unit Gastro Retentive Floating Drug Delivery System for Captopril Based on Gas Formation Technique: In Vitro Evaluation  

PubMed Central

A gastro retentive floating drug delivery system with multiple-unit minitab’s based on gas formation technique was developed in order to prolong the gastric residence time and to increase the overall bioavailability of the drug. The system consists of the drug-containing core units prepared by direct compression process, which are coated with three successive layers of an inner seal coat, effervescent layer (sodium bicarbonate) and an outer gas-entrapped polymeric membrane of an polymethacrylates (Eudragit RL30D, RS30D, and combinations of them). Only the system using Eudragit RL30D and combination of them as a gas-entrapped polymeric membrane could float. The time to float decreased as amount of the effervescent agent increased and coating level of gas-entrapped polymeric membrane decreased. The optimum system floated completely within 3 min and maintained the buoyancy over a period of 12 h. The drug release was controlled and linear with the square root of time. Increasing coating level of gas-entrapped polymeric membrane decreased the drug release. Both the rapid floating and the controlled release properties were achieved in the multiple-unit floating drug delivery system developed in this present study. The analysis of the parameter dissolution data after storage at 40 °C and 75% RH for 3 months showed, no significant change indicating the two dissolution profiles were considered to be similar (f2 value is more than 50).

Kesavan, Bhaskar; Chinnala, Krishna Mohan; Vobalaboina, Venkateswarlu; Yamsani, Madhusudan Rao

2008-01-01

136

The effect of storage and active ingredient properties on the drug release profile of poly(ethylene oxide) matrix tablets  

Microsoft Academic Search

Different molecular weight forms of poly(ethylene oxide) can be used successfully in controlled release drug delivery due to their excellent matrix forming properties. Drug release of these materials follows nearly zero order kinetics, and is mainly governed by polymer swelling and erosion and diffusion of drug molecules. Because of its partly amorphous structure, poly(ethylene oxide) undergoes structural changes caused by

Dorottya Kiss; Károly Süvegh; Romána Zelkó

2008-01-01

137

Preparation of a Matrix Type MultipleUnit Gastro Retentive Floating Drug Delivery System for Captopril Based on Gas Formation Technique: In Vitro Evaluation  

Microsoft Academic Search

A gastro retentive floating drug delivery system with multiple-unit minitab’s based on gas formation technique was developed\\u000a in order to prolong the gastric residence time and to increase the overall bioavailability of the drug. The system consists\\u000a of the drug-containing core units prepared by direct compression process, which are coated with three successive layers of\\u000a an inner seal coat, effervescent

Lingam Meka; Bhaskar Kesavan; Krishna Mohan Chinnala; Venkateswarlu Vobalaboina; Madhusudan Rao Yamsani

2008-01-01

138

Development of a floating dosage form of ranitidine hydrochloride by statistical optimization technique.  

PubMed

The objective of this study was to evaluate the effect of formulation variables on the release properties, floating lag time, and hardness, when developing floating tablets of Ranitidine hydrochloride, by the statistical optimization technique. The formulations were prepared based on 3(2) factorial design, with polymer ratio (HPMC 100 KM: Xanthan gum) and the amount of aerosil, as two independent formulation variables. The four dependent (response) variables considered were: percentage of drug release at the first hour, T(50%) (time taken to release 50% of the drug), floating lag time, and hardness of the tablet. The release profile data was subjected to a curve fitting analysis, to describe the release mechanism of the drug from the floating tablet. An increase in drug release was observed with an increase in the polymer ratio, and as the amount of aerosil increased, the hardness of the tablet also increased, without causing any change in the floating lag time. The desirability function was used to optimize the response variables, each having a different target, and the observed responses were in accordance with the experimental values. The results demonstrate the feasibility of the model in the development of floating tablets containing Ranitidine hydrochloride. PMID:21264091

Jain, S; Srinath, Ms; Narendra, C; Reddy, Sn; Sindhu, A

2010-10-01

139

Relationship between diffusivity of water molecules inside hydrating tablets and their drug release behavior elucidated by magnetic resonance imaging.  

PubMed

We reported previously that sustained release matrix tablets showed zero-order drug release without being affected by pH change. To understand drug release mechanisms more fully, we monitored the swelling and erosion of hydrating tablets using magnetic resonance imaging (MRI). Three different types of tablets comprised of polyion complex-forming materials and a hydroxypropyl methylcellulose (HPMC) were used. Proton density- and diffusion-weighted images of the hydrating tablets were acquired at intervals. Furthermore, apparent self-diffusion coefficient maps were generated from diffusion-weighted imaging to evaluate the state of hydrating tablets. Our findings indicated that water penetration into polyion complex tablets was faster than that into HPMC matrix tablets. In polyion complex tablets, water molecules were dispersed homogeneously and their diffusivity was relatively high, whereas in HPMC matrix tablets, water molecule movement was tightly restricted within the gel. An optimal tablet formulation determined in a previous study had water molecule penetration and diffusivity properties that appeared intermediate to those of polyion complex and HPMC matrix tablets; water molecules were capable of penetrating throughout the tablets and relatively high diffusivity was similar to that in the polyion complex tablet, whereas like the HPMC matrix tablet, it was well swollen. This study succeeded in characterizing the tablet hydration process. MRI provides profound insight into the state of water molecules in hydrating tablets; thus, it is a useful tool for understanding drug release mechanisms at a molecular level. PMID:22466738

Kikuchi, Shingo; Onuki, Yoshinori; Kuribayashi, Hideto; Takayama, Kozo

2012-01-01

140

FPGA-Based, Floating-Point Reduction Operations  

Microsoft Academic Search

Floating-point reduction operations are a vital part of scientific computational kernels, such as vector dot-products, discrete cosine transforms (DCT), and matrix-matrix multiplications. As FPGAs continue to gain popularity in custom and embedded computing platforms, implementations of these applications in such platforms are desirable. Due to the inherently deep pipelines of high-performance floating-point cores in FPGAs, reduction circuits require special feedback

MICHAEL R. BODNAR; JAMES P. DURBANO; JOHN R. HUMPHREY; PETERSEN F. CURT; DENNIS W. PRATHER

141

Floating electrode dielectrophoresis.  

PubMed

In practice, dielectrophoresis (DEP) devices are based on micropatterned electrodes. When subjected to applied voltages, the electrodes generate nonuniform electric fields that are necessary for the DEP manipulation of particles. In this study, electrically floating electrodes are used in DEP devices. It is demonstrated that effective DEP forces can be achieved by using floating electrodes. Additionally, DEP forces generated by floating electrodes are different from DEP forces generated by excited electrodes. The floating electrodes' capabilities are explained theoretically by calculating the electric field gradients and demonstrated experimentally by using test-devices. The test-devices show that floating electrodes can be used to collect erythrocytes (red blood cells). DEP devices which contain many floating electrodes ought to have fewer connections to external signal sources. Therefore, the use of floating electrodes may considerably facilitate the fabrication and operation of DEP devices. It can also reduce device dimensions. However, the key point is that DEP devices can integrate excited electrodes fabricated by microtechnology processes and floating electrodes fabricated by nanotechnology processes. Such integration is expected to promote the use of DEP devices in the manipulation of nanoparticles. PMID:17117384

Golan, Saar; Elata, David; Orenstein, Meir; Dinnar, Uri

2006-12-01

142

An approach to formulating an oral floating drug delivery system for dexchlorpheniramine maleate using factorial design.  

PubMed

The purpose of this research was to formulate and evaluate a floating tablet formulation of dexchlorpheniramine maleate (DCPM) using full factorial design. A 32 factorial design (nine runs) was utilized to optimize the formulation, the contents of hydroxypropyl methyl cellulose (HPMC) (X1) and Carbopol 934P (X2) being taken as independent variables and t50% (Y1), % drug release after 6 h (Y2), % drug release after 12 h (Y3), and floating lag time (FLT) (Y4) as the dependent variables. The tablets showed 99.2635 to 102.4709 of the labeled amount of dexchlorpheniramine maleate indicating uniformity of content. The tablets containing DCPM released 72.28 to 99.461% of drug at the end of 12 h by an in vitro release study. Hardness, friability, floating capacity, weight variation and content uniformity were also examined. In addition,the tablets were evaluated for in vitro release characteristics for 24 h. The optimal batch (F9) was selected by regression analysis and followed Higuchi kinetics. The drug release mechanism was found to be a complex mixture of diffusion, swelling and erosion. The floating tablets of DCPM developed may be used clinically for prolonged drug release for at least 16 hrs, thereby improving bioavailability and patient compliance. PMID:22888518

Alabazi, M Y; Elzein, H

2012-07-01

143

Positive seal float collar  

SciTech Connect

A device for insuring a positive fluid seal between a float collar valving element and valve seat therein is disclosed. The device comprises a rubberlike tension strap or compression steel spring positioned within the float collar valve assembly for urging the valving element against the upper valve seat. Fluid pressure from above the valve assembly will overcome the force exerted on the valving element by the urging device and permit fluid to flow in a downwardly direction through the float collar valve assembly. However, when this fluid pressure above the float collar is reduced, the urging device overcomes the force exerted thereby and again urges the valving element in positive sealing engagement with the upper valve seat to preclude flow of fluid in an upperwardly direction back through the float collar valve assembly.

Bolding, B.H.

1981-09-01

144

Float-type flowmeter  

SciTech Connect

This patent describes an improvement in a float-type flowmeter for measuring the rate of a given flow of fluid. It has a float chamber; and inlet opening; means for channeling the sampled portion of the flow into the first end of the float chamber; and outlet opening; a float, located in the float chamber; and flow rate indicating means. The improvement comprises: means for ratably mounting the inlet opening so that it can be rotated to face into the flow; a rotatably mounted deflection surface, mounted so it can be deflected by the flow so as to minimize its resistance to the flow; and means for mechanically linking the deflection surface and the inlet opening so that when the deflecting surface is rotated so as to minimize its resistance to the flow, the inlet opening faces into the flow.

Daly, D.C.

1990-01-01

145

Terahertz Technology: A Boon to Tablet Analysis  

PubMed Central

The terahertz gap has a frequency ranges from ?0.3 THz to ?10 THz in the electromagnetic spectrum which is in between microwave and infrared. The terahertz radiations are invisible to naked eye. In comparison with x-ray they are intrinsically safe, non-destructive and non-invasive. Terahertz spectroscopy enables 3D imaging of structures and materials, and the measurement of the unique spectral fingerprints of chemical and physical forms. Terahertz radiations are produced by a dendrimer based high power terahertz source and spectroscopy technologies. It resolves many of the questions left unanswered by complementary techniques, such as optical imaging, Raman and infrared spectra. In the pharmaceutical industries it enables nondestructive, internal, chemical analysis of tablets, capsules, and other dosage forms. Tablet coatings are a major factor in drug bioavailability. Therefore tablet coatings integrity and uniformity are of crucial importance to quality. Terahertz imaging gives an unparalleled certainty about the integrity of tablet coatings and the matrix performance of tablet cores. This article demonstrates the potential of terahertz pulse imaging for the analysis of tablet coating thickness by illustrating the technique on tablets.

Wagh, M. P.; Sonawane, Y. H.; Joshi, O. U.

2009-01-01

146

Concrete production floating platforms  

SciTech Connect

The floating production platforms operating in the North Sea are adapted from drilling semisubmersibles which allow only a limited payload capacity. Experience of concrete production platforms constructed for the North Sea has led Sea Tank Co. to propose a floating platform which offers large payload and oil storage capacities similar to those of existing fixed platforms. Sea Tank Co. and Institut Francais du Petrole joined forces in early 1976 to study the feasibility of a concrete floating production platform incorporating the structure and the production riser together. The results of this 3-yr program show that the concrete floating structure is economically attractive for permanent utilization on a production site. Furthermore, concrete has definite advantages over other materials, in its long term behavior.

Letourneur, O.; Falcimaigne, J.

1981-01-01

147

Floating Magnet Demonstration.  

ERIC Educational Resources Information Center

|A room-temperature demonstration of a floating magnet using a high-temperature superconductor is described. The setup and operation of the apparatus are described. The technical details of the effect are discussed. (CW)|

Wake, Masayoshi

1990-01-01

148

Floating Magnet Demonstration.  

ERIC Educational Resources Information Center

A room-temperature demonstration of a floating magnet using a high-temperature superconductor is described. The setup and operation of the apparatus are described. The technical details of the effect are discussed. (CW)

Wake, Masayoshi

1990-01-01

149

Floating-point tricks  

Microsoft Academic Search

The author discusses IEEE floating point representation that stores numbers in what amounts to scientific notation. He considers the sign bit, the logarithm function, function approximations, errors and refinements

J. F. Blinn

1997-01-01

150

Micromechanisms with floating pivot  

DOEpatents

A new class of tilting micromechanical mechanisms have been developed. These new mechanisms use floating pivot structures to relieve some of the problems encountered in the use of solid flexible pivots.

Garcia, Ernest J. (Albuquerque, NM)

2001-03-06

151

Stabilized floating platforms  

DOEpatents

The subject invention is directed to a floating platform for supporting nuclear reactors and the like at selected offshore sites. The platform is provided with a stabilizer mechanism which significantly reduces the effects of wave action upon the platform and which comprises a pair of relatively small floats attached by rigid booms to the platform at locations spaced therefrom for reducing wave pitch, acceleration, and the resonance period of the wave.

Thomas, David G. (Oak Ridge, TN)

1976-01-01

152

Clinical evaluation of sodium flouride chewable tablets in dental caries.  

PubMed

Chewable tablets containing low dosage flouride content were prepared using two varities of celluloses and their in vitro parameters were evaluated. An eighteen month clinical trial revealed that both these formulations were effective in controlling the caries. However, ethyl cellulose is proved to be superior to methylcellulose as a controlled release matrix material in controlling caries. Thus this study recommends ethylcellulose matrix tablets containing low flouride content is an efficacious and cost effective drug device in controlling dental caries. PMID:10865398

Maddi, S S; Tandon, S; Aithal, K S

153

What Floats Your Boat?  

NSDL National Science Digital Library

Students use modeling clay, a material that is denser than water and thus ordinarily sinks in water, to discover the principle of buoyancy. They begin by designing and building boats out of clay that will float in water, and then refine their designs so that their boats will carry as great a load (metal washers) as possible. Building a clay boat to hold as much weight as possible is an engineering design problem. Next, they compare amount of water displaced by a lump of clay that sinks to the amount of water displaced by the same lump of clay when it is shaped so as to float. Determining the masses of the displaced water allows them to arrive at Archimedes' principle, whereby the mass of the displaced water equals the mass of the floating clay boat.

Engineering K-Ph.d. Program

154

Effect of diluents on tablet integrity and controlled drug release.  

PubMed

The objective of this study was to evaluate the effect of diluents and wax level on tablet integrity during heat treatment and dissolution for sustained-release formulations and the resultant effect on drug release. Dibasic calcium phosphate dihydrate (DCPD), microcrystalline cellulose (MCC), and lactose were evaluated for their effect on tablet integrity during drug dissolution and heat treatment in wax matrix formulations. A newly developed direct compression diluent, dibasic calcium phosphate anhydrous (DCPA), was also evaluated. Compritol 888 ATO was used as the wax matrix material, with phenylpropanolamine hydrochloride (PPA) as a model drug. Tablets were made by direct compression and then subjected to heat treatment at 80 degrees C for 30 min. The results showed that MCC, lactose, and DCPA could maintain tablets intact during heat treatment above the melting point of wax (70 degrees C-75 degrees C). However, DCPD tablets showed wax egress during the treatment. MCC tablets swelled and cracked during drug dissolution and resulted in quick release. DCPD and lactose tablets remained intact during dissolution and gave slower release than MCC tablets. DCPA tablets without heat treatment disintegrated very quickly and showed immediate release. In contrast, heat-treated DCPA tablets remained intact through the 24-hr dissolution test and only released about 80% PPA at 6 hr. In the investigation of wax level, DCPD was used as the diluent. The drug release rate decreased as the wax content increased from 15% to 81.25%. The dissolution data were best described by the Higuchi square-root-of-time model. Diluents showed various effects during heat treatment and drug dissolution. The integrity of the tablets was related to the drug release rate. Heat treatment retarded drug release if there was no wax egress. PMID:10872095

Zhang, Y E; Schwartz, J B

2000-07-01

155

Hypocitraturia despite potassium citrate tablet supplementation.  

PubMed

Citrate supplementation is widely used in the prevention of recurrent nephrolithiasis with hypocitraturia. Potassium citrate is the most commonly used citrate agent for this indication. In patients with chronic diarrheal syndromes, the absorption of potassium citrate can be affected. We describe a patient who presented with recurrent nephrolithiasis and chronic diarrhea and was found to have severe hypocitraturia despite citrate supplementation with potassium citrate tablets, likely due to inadequate gastrointestinal absorption of citrate from the slow-release wax-matrix tablets. PMID:17406150

Shenoy, Chetan

2006-07-13

156

Sink or Float? Inquiry Investigation  

NSDL National Science Digital Library

Students explore and experiment with various objects to find which materials will float or sink. They record predictions and results, and generate ideas about the properties of materials that float or sink.

157

Floating Object Recovery Study.  

National Technical Information Service (NTIS)

A study was conducted to determine a method to recover floating objects from the surface of the ocean. Model test tank investigations conducted at Stevens Institute of generating a localized flow field which would refract waves were investigated for a pos...

R. J. Helgeson

1970-01-01

158

Traumatic floating clavicle.  

PubMed

We report a case of traumatic floating clavicula in a man aged 21 years. He was admitted to our emergency department with polytrauma sustained in a motor car accident, successfully treated 21 days after the accident with bipolar open reduction and wire stabilization. PMID:23158062

Yurdakul, Emre; Salt, Ömer; Uzun, Erdal; Do?ar, Fatih; Güney, Ahmet; Durukan, Polat

2012-11-01

159

Compound floating pivot micromechanisms  

DOEpatents

A new class of tilting micromechanical mechanisms have been developed. These new mechanisms use compound floating pivot structures to attain far greater tilt angles than are practical using other micromechanical techniques. The new mechanisms are also capable of bi-directional tilt about multiple axes.

Garcia, Ernest J. (Albuquerque, NM)

2001-04-24

160

Improved stability of Opalmon tablets under humid conditions IV: effect of polysaccharides and disintegrants on the stability and dissolution property of Opalmon tablets.  

PubMed

We studied the effects of dextran, dextrin, and disintegrants on the chemical stability of Opalmon tablets containing Limaprost-alfadex (Limaprost/alpha-cyclodextrin complex) and found that the addition of dextran or dextrin significantly improved the chemical stability of Opalmon tablets under high humidity, compared to lactose. We also examined how dextran stabilizes Limaprost in Opalmon tablets and studied the formulation of Opalmon tablets in order to achieve higher chemical stability, rapid dissolution and reduced stickiness. The results suggested that dextran increases stabilization after moisture adsorption by decreasing the dissociation of Limaprost-alfadex to the free drug and alpha-cyclodextrin in the dextran matrix, when compared with the lactose matrix. The stickiness of Opalmon tablets containing dextran and dextrin was negligible when dextran and dextrin amounted to less than 20% of the formulation. By selecting a proper disintegrant, we obtained Opalmon tablets with higher chemical stability and rapid dissolution properties. PMID:18175966

Sekiya, Noboru; Nishiwaki, Atsushi; Nishiura, Akio; Yamamoto, Masanobu; Takeda, Kazuhisa; Iohara, Daisuke; Hirayama, Fumitoshi; Arima, Hidetoshi; Uekama, Kaneto

2008-01-01

161

Innovations in education : tablets  

Microsoft Academic Search

In this group of three separate articles the authors discuss the use of tablet PCs in educational applications at their schools. In 'Tablets: the smart medicine for teaching and learning', Lee Bond explains how Immanuel Lutheran College on the Sunshine Coast in Queensland is using ICT to make real systemic change in the delivery of education in physics, chemistry, biology

Lee Bond

2009-01-01

162

Teaching with Tablet PC's  

Microsoft Academic Search

Tablet PC's are traditional notebook computers with the ability to process digital ink by writing with a stylus. They have recently attracted attention as a potential tool for educational use. This paper describes the author's experience using the Tablet PC to conduct a CS1 course and a software engineering (SWE) course. The SWE course consisted primarily of PowerPoint lectures while

Kenrick Mock

2004-01-01

163

Serial floating point formatter  

SciTech Connect

A floating point formatter for changing fixed point serial digital data, such as that received by a seismic data acquisition system, is disclosed wherein fixed point serial digital data is received and scaled to remove any bias added by preamplification. The scaled data is shifted a predetermined number of bits and a resulting exponent is calculated. The shifted data signal and corresponding exponent are combined and further scaled to permit stacking the data without exceeding the system capacity.

Peterson, R. D.; Penner, W. A.

1985-11-12

164

Float or Sink?  

NSDL National Science Digital Library

In this water activity, learners test which objects float and which sink. Learners discover that objects behave differently in water. Learners are also introduced to the idea of "predicting" and record their predictions and observations on a chart. This activity is part of the curriculum Explore Water, related to Peep and the Big Wide World, a preschool science series on public television. The activity starts on page 41 of the PDF.

Foundation, Wgbh E.

2005-01-01

165

Criteria for Floating I  

NASA Astrophysics Data System (ADS)

Conditions are determined under which solid bodies will float on a liquid surface in stable equilibrium, under the influence of gravity and of surface tension. These include configurations in which the density of the body exceeds the density of the ambient liquid, so that for an infinitely deep liquid in a downward gravity field there is no absolute energy minimum. Of notable interest are the results (a) that if a smooth body is held rigidly and translated downward into an infinite fluid bath through a family of fluid equilibrium configurations in a downward gravity field, the transition is necessarily discontinuous, and (b) a formal proof that there can be a free-floating locally energy minimizing configuration that does not globally minimize, even if the density of the body exceeds that of the liquid. The present work is limited to the two dimensional case corresponding to a long cylinder that is floating horizontally. The more physical three-dimensional case can be studied in a similar way, although details of behavior can change significantly. That work will appear in an independent study written jointly with T. I. Vogel.

Finn, Robert

2011-03-01

166

WindFloat: A floating foundation for offshore wind turbines  

Microsoft Academic Search

This manuscript summarizes the feasibility study conducted for the WindFloat technology. The WindFloat is a three-legged floating foundation for multimegawatt offshore wind turbines. It is designed to accommodate a wind turbine, 5 MW or larger, on one of the columns of the hull with minimal modifications to the nacelle and rotor. Potential redesign of the tower and of the turbine

Dominique Roddier; Christian Cermelli; Alexia Aubault; Alla Weinstein

2010-01-01

167

Cefuroxime Axetil tablet  

Center for Drug Evaluation (CDER)

Text Version... Contains Nonbinding Recommendations Draft Guidance on Cefuroxime Axetil ... Active ingredient: Cefuroxime Axetil Form/Route: Tablet/Oral ... More results from www.fda.gov/downloads/drugs/guidancecomplianceregulatoryinformation

168

Calcification Prevention Tablets.  

National Technical Information Service (NTIS)

Citric acid tablets, which slowly release citric acid when flushed with water, are under development by the Navy for calcification prevention. The citric acid dissolves calcium carbonate deposits and chelates the calcium. For use in urinals, a dispenser i...

G. A. Lindsay M. A. Hasting M. A. Gustavson

1991-01-01

169

Automatic Generation of Floating-Point Test Data  

Microsoft Academic Search

For numerical programs, or more generally for programs with floating-point data, it may be that large savings of time and storage are made possible by using numerical maximization methods instead of symbolic execution to generate test data. Two examples, a matrix factorization subroutine and a sorting method, illustrate the types of data generation problems that can be successfully treated with

Webb Miller; David L. Spooner

1976-01-01

170

The Floating Ball Paradox  

NASA Astrophysics Data System (ADS)

In capillary theory there are two kinds of surface tension. There is the surface tension at the interface between two immiscible fluids. Thomas Young [9] also allowed for there to be a surface tension associated with a liquid-solid interface. He proceeded to use a balance of forces argument to derive the well-known contact angle condition along a liquid-liquid-solid intersection. The validity of this argument has recently been called into question by R. Finn [6]. A floating ball experiment discussed in that paper leads to an apparent paradox. We address this issue.

Wente, Henry C.

2008-11-01

171

Will It Float?  

NSDL National Science Digital Library

Student preconceptions are one of the greatest challenges we face as science teachers. This Predict, Explain, Observe, and Explain (PEOE) activity challenges students? preconceived notions about why matter floats or sinks when placed in a liquid. The idea behind this model is to do a demonstration that first confirms student's conceptions followed by a second, similar demonstration that provides discrepant information creating cognitive dissonance. Learning happens as students are forced to modify their conceptions so that their view of how things work is not in conflict with what they are seeing.

Major, Jeff

2006-01-01

172

Effect of tablet integrity on the dissolution rate of sustained-release preparations.  

PubMed

The objective of this study was to evaluate the effect of tablet integrity on the dissolution rate. The model drug used for this study was aspirin. A dissolution study was performed with three commercially-available aspirin tablets (ZORprin, Bayer 8-h aspirin and Bayer aspirin), two of which were sustained-release tablets. For ZORprin, the average dissolution data indicated that the in vitro release rate of aspirin was consistent with the intended design of the sustained-release wax matrix tablets only when the tablets were intact. The split tablets showed a consistently higher release profile over time, with a 50% higher release at 6 h. However, the Bayer 8-h aspirin and plain aspirin tablet data showed that tablet integrity had no significant impact on the dissolution rate, because the intact and split tablets showed similar drug release profiles over time. In conclusion, care should be taken to administer sustained-release tablets, avoiding any breaking or crushing of the tablets unless this is directed by the manufacturer. PMID:8873848

Mandal, T K

1996-06-01

173

Pharmaceutical development of ondansetron tablets.  

PubMed

Ondansetron tablets contain ondansetron base as the hydrochloride dihydrate, lactose, microcrystalline cellulose, starch and magnesium stearate. Tablets sampled at the beginning and end of the compression process have good content uniformity and drug content, showing that there is no segregation or loss of the drug substance during tabletting. The release of drug substance is related to the tablet disintegration time. Tablets with disintegration times of 3 and 10 min release 85% of the drug substance in approximately 6 and 20 min respectively. Satisfactory bioavailability has been demonstrated. The tablets have good stability, and have a shelf life of 2 years when stored below 30 degrees C. PMID:2533901

Leak, R E; Woodford, J D

1989-01-01

174

Does It Sink or Float?  

ERIC Educational Resources Information Center

This activity is designed to teach prekindergarten to second grade students about the concept of sink or float through an inquiry activity. Students will use familiar objects to predict and test the properties of sink and float. Background information is offered to teachers to assist them with this activity. This lesson begins with an engaging…

McDonald, Judith Richards

2012-01-01

175

Development and evaluation of orally disintegrating tablets (ODTs) containing Ibuprofen granules prepared by hot melt extrusion  

Microsoft Academic Search

In the current study Ibuprofen was embedded in a methacrylate copolymer (Eudragit® EPO) matrix to produce solid dispersions by hot-melt extrusion (HME) processing. The obtained granules were incorporated in orally disintegrating tablets (ODTs). The tablets were developed by varying the ratio of superdisintegrants such as sodium croscarmellose and crosslinked polyvinylpyrrolidone grades while a direct compression process was used to compress

Andreas Gryczke; Silke Schminke; Mohammed Maniruzzaman; Julien Beck; Dennis Douroumis

2011-01-01

176

Chitosan and Sodium Sulfate as Excipients in the Preparation of Prolonged Release Theophylline Tablets  

Microsoft Academic Search

The major objectives of this study were to monitor the effect of cross-linking of cationic chitosan in acidic media with sulfate anion during granules preparation by wet granulation method prior tableting using theophylline (TPH) as a model drug. The prepared granules and the compressed tablets were subjected to in vitro evaluation. The properties of the prepared matrix granules and the

Ibrahim A. Alsarra; Ibrahim El-Bagory; Mohsen A. Bayomi

2005-01-01

177

Evaluation of Water Sterilizing Tablets.  

National Technical Information Service (NTIS)

Water sterilizing tablets were evaluated for efficiency of kill of micro-organisms, effect of inhibitors and palatability. The effect of long term use is discussed. The water sterilizing tablet recommended for disinfection of personal drinking water, on t...

G. F. Thomson K. W. James G. E. Driver A. T. Hancock

1985-01-01

178

Formulation and evaluation of floating oral in situ gelling system of amoxicillin.  

PubMed

Purpose. Effective Helicobacter pylori eradication requires delivery of the antibiotic locally in the stomach. High dose of amoxicillin (750 to 1000?mg) is difficult to incorporate in floating tablets but can easily be given in liquid dosage form. Keeping the above facts in mind, we made an attempt to develop a new floating in situ gelling system of amoxicillin with increased residence time using sodium alginate as gelling polymer to eradicate H. pylori. Methods. Floating in situ gelling formulations were prepared using sodium alginate, calcium chloride, sodium citrate, hydroxypropyl methyl cellulose K100, and sodium bicarbonate. The prepared formulations were evaluated for solution viscosity, floating lag time, total floating time, and in vitro drug release. The formulation was optimized using a 3(2) full factorial design. Dissolution data were fitted to various models to ascertain kinetic of drug release. Regression analysis and analysis of variance were performed for dependent variables. Results. All formulations (F(1)-F(9)) showed floating within 30?s and had total floating time of more than 24?h. All the formulations showed good pourability. It was observed that concentration of sodium alginate and HPMC K100 had significant influence on floating lag time, cumulative percentage drug release in 6?h and 10?h. The batch F(8) was considered optimum since it showed more similarity in drug release (f(2) = 74.38) to the theoretical release profile. Conclusion. Floating in situ gelling system of amoxicillin can be formulated using sodium alginate as a gelling polymer to sustain the drug release for 10 to 12?h with zero-order release kinetics. PMID:22389849

Patel, Dasharath M; Patel, Divyesh K; Patel, Chhagan N

2011-07-28

179

Floating treatment wetlands for domestic wastewater treatment.  

PubMed

Floating islands are a form of treatment wetland characterized by a mat of synthetic matrix at the water surface into which macrophytes can be planted and through which water passes. We evaluated two matrix materials for treating domestic wastewater, recycled plastic and recycled carpet fibers, for chemical oxygen demand (COD) and nitrogen removal. These materials were compared to pea gravel or open water (control). Experiments were conducted in laboratory scale columns fed with synthetic wastewater containing COD, organic and inorganic nitrogen, and mineral salts. Columns were unplanted, naturally inoculated, and operated in batch mode with continuous recirculation and aeration. COD was efficiently removed in all systems examined (>90% removal). Ammonia was efficiently removed by nitrification. Removal of total dissolved N was ?50% by day 28, by which time most remaining nitrogen was present as NO(3)-N. Complete removal of NO(3)-N by denitrification was accomplished by dosing columns with molasses. Microbial communities of interest were visualized with denaturing gradient gel electrophoresis (DGGE) by targeting specific functional genes. Shifts in the denitrifying community were observed post-molasses addition, when nitrate levels decreased. The conditioning time for reliable nitrification was determined to be approximately three months. These results suggest that floating treatment wetlands are a viable alternative for domestic wastewater treatment. PMID:22105133

Faulwetter, J L; Burr, M D; Cunningham, A B; Stewart, F M; Camper, A K; Stein, O R

2011-01-01

180

Application of Design of Experiment for Floating Drug Delivery of Tapentadol Hydrochloride  

PubMed Central

The aim of the present study was to apply design of experiment (DOE) to optimize floating drug delivery of tapentadol hydrochloride. Tapentadol hydrochloride is a synthetic opioid used as a centrally acting analgesic and effective in both experimental and clinical pain. The half-life of the drug is about 4 hours and oral dose is 50 to 250?mg twice a day. For optimization 32 full factorial design was employed for formulation of tapentadol hydrochloride tablets. Sodium bicarbonate was incorporated as a gas-generating agent. Combination of polymers Xanthan gum and Locust bean gum was used to achieve controlled release effect. The concentration of polymers was considered as the independent variables and dependent variables were floating lag time and swelling index of the tablets. From the factorial batches, it was observed that formulation containing combination of 20% sodium bicarbonate and 10% citric acid shows optimum floating ability whereas the formulation containing 20% Xanthan gum and 28% Locust bean gum shows optimum sustained drug release pattern with adequate floating.

Jagdale, Swati C.; Patil, Somnath; Kuchekar, Bhanudas S.

2013-01-01

181

Anchoring floating structural body in deep water  

Microsoft Academic Search

This patent describes a deep water anchoring system for oil drilling platforms and other deep water structures, comprising: a structural body floating at the surface of a body of water; an intermediate floating member directly under and spaced from the floating structural body; intermediate floating member submerged below the surface of the body of water a distance sufficient to be

Kalpins

1987-01-01

182

The Unified Floating Point Vector Coprocessor for Reconfigurable Hardware  

NASA Astrophysics Data System (ADS)

There has been an increased interest recently in using embedded cores on FPGAs. Many of the applications that make use of these cores have floating point operations. Due to the complexity and expense of floating point hardware, these algorithms are usually converted to fixed point operations or implemented using floating-point emulation in software. As the technology advances, more and more homogeneous computational resources and fixed function embedded blocks are added to FPGAs and hence implementation of floating point hardware becomes a feasible option. In this research we have implemented a high performance, autonomous floating point vector Coprocessor (FPVC) that works independently within an embedded processor system. We have presented a unified approach to vector and scalar computation, using a single register file for both scalar operands and vector elements. The Hybrid vector/SIMD computational model of FPVC results in greater overall performance for most applications along with improved peak performance compared to other approaches. By parameterizing vector length and the number of vector lanes, we can design an application specific FPVC and take optimal advantage of the FPGA fabric. For this research we have also initiated designing a software library for various computational kernels, each of which adapts FPVC's configuration and provide maximal performance. The kernels implemented are from the area of linear algebra and include matrix multiplication and QR and Cholesky decomposition. We have demonstrated the operation of FPVC on a Xilinx Virtex 5 using the embedded PowerPC.

Kathiara, Jainik

183

CES 2011: Tablet Crazy  

ERIC Educational Resources Information Center

|Ereaders are so last year. Tablets were the watchword at this year's annual Consumer Electronics Show (CES) in Las Vegas, January 6-9. This year, the show set new records, with some 2700 companies from around the world exhibiting at the multiple exhibition halls and 30,000 attendees gawking at the products. What did they see? There were still…

Rapp, David

2011-01-01

184

The Nebusarsekim Tablet  

Microsoft Academic Search

During the summer of 2007 an internet hype was unleashed by the breaking news that an Old Testament name of some importance, figuring in the Book of Jeremiah Ch. 39, had been positively identified on a cuneiform clay tablet, viz. a bill of receipt from the time of this prophet's floruit. Many a scholar of sorts was quick to claim

H. A. I. Stadhouders

2008-01-01

185

Equivalence of the floating frame of reference approach and finite element formulations  

Microsoft Academic Search

The floating frame of reference formulation which is widely used in flexible multibody simulations leads to a highly non-linear inertia matrix. This matrix which exhibits a strong inertia coupling between the reference motion and the elastic deformation can be expressed in terms of a unique set of inertia shape integrals that depend on the assumed displacement field. In this paper,

A. A. Shabana; R. Schwertassek

1998-01-01

186

Quantification, mechanism, and mitigation of active ingredient phase transformation in tablets.  

PubMed

Model tablet formulations containing thiamine hydrochloride [as a nonstoichiometric hydrate (NSH)] and dicalcium phosphate dihydrate (DCPD) were prepared. In intact tablets, the water released by dehydration of DCPD mediated the transition of NSH to thiamine hydrochloride hemihydrate (HH). The use of an X-ray microdiffractometer with an area detector enabled us to rapidly and simultaneously monitor both the phase transformations. The spatial information, gained by monitoring the tablet from the surface to the core (depth profiling), revealed that both DCPD dehydration and HH formation progressed from the surface to the tablet core as a function of storage time. Film coating of the tablets with ethyl cellulose caused a decrease in both the reaction rates. There was a pronounced lag time, but once initiated, the transformations occurred simultaneously throughout the tablet. Thus the difference in the phase transformation behavior between the uncoated and the coated tablets could not have been discerned without the depth profiling. Incorporation of hydrophilic colloidal silica as a formulation component further slowed down the transformations. By acting as a water scavenger it maintained a very "dry" environment in the tablet matrix. Finally, by coating the NSH particles with hydrophobic colloidal silica, the formation of HH was further substantially decelerated. The microdiffractometric technique not only enabled direct analyses of tablets but also provided the critical spatial information. This helped in the selection of excipients with appropriate functionality to prevent the in situ phase transformations. PMID:23869937

Thakral, Naveen K; Ragoonanan, Vishard; Suryanarayanan, Raj

2013-07-22

187

Evaluation of porous carrier-based floating orlistat microspheres for gastric delivery.  

PubMed

The purpose of this research was to prepare floating microspheres consisting of (1) calcium silicate as porous carrier; (2) orlistat, an oral anti-obesity agent; and (3) Eudragit S as polymer, by solvent evaporation method and to evaluate their gastro-retentive and controlled-release properties. The effect of various formulation and process variables on the particle morphology, micromeritic properties, in vitro floating behavior, percentage drug entrapment, and in vitro drug release was studied. The gamma scintigraphy of the optimized formulation was performed in albino rabbits to monitor the transit of floating microspheres in the gastrointestinal tract. The orlistat-loaded optimized formulation was orally administered to albino rabbits, and blood samples collected were used to determine pharmacokinetic parameters of orlistat from floating microspheres. The microspheres were found to be regular in shape and highly porous. Microsphere formulation CS4, containing 200 mg calcium silicate, showed the best floating ability (88% +/- 4% buoyancy) in simulated gastric fluid as compared with other formulations. Release pattern of orlistat in simulated gastric fluid from all floating microspheres followed Higuchi matrix model and Peppas-Korsmeyer model. Prolonged gastric residence time of over 6 hours was achieved in all rabbits for calcium silicate-based floating microspheres of orlistat. The enhanced elimination half-life observed after pharmacokinetic investigations in the present study is due to the floating nature of the designed formulations. PMID:17233542

Jain, Sunil K; Agrawal, Govind P; Jain, Narendra K

2006-11-10

188

Floating units cut production costs  

SciTech Connect

Nine operating semisubmersible and tanker production platform facilities are currently supplying the technology and experiential data necessary for development of floating production systems for depth applications of 1000 to 10,000 ft. Sedco-Hamilton Production Services has developed a 4-well deepwater system consisting of a floating tanker or semi moored on short lines to 4 permanent catenary moored springbuoys. The platform is linked to a seabed tree array through the hull centerline via a flexible, retrievable production riser bundle. Costs associated with floating production platforms normally are lower than those of fixed platforms. A major factor is the decision to convert an existing drilling rig into the production mode or alternatively opt for a new build.

Homer, A.

1983-05-01

189

Goodyear Scrap Tire Floating Breakwater Concepts.  

National Technical Information Service (NTIS)

Scrap tires are proposed as a construction material for building large floating breakwater devices. The Goodyear scrap tire floating breakwater assemblies are formed by securing together modular bundles of tightly interlocked scrap tires with high strengt...

R. D. Candle

1974-01-01

190

Battery Charging in Float vs. Cycling Environments.  

National Technical Information Service (NTIS)

In lead-acid battery systems, cycling systems are often managed using float management strategies. There are many differences in battery management strategies for a float environment and battery management strategies for a cycling environment. To complica...

G. P. Corey

2000-01-01

191

Unintended water mediated cocrystal formation in carbamazepine and aspirin tablets.  

PubMed

The water of crystallization released during dehydration of dibasic calcium phosphate dihydrate (DCPD) mediated the cocrystal formation between carbamazepine (CBZ) and nicotinamide (NMA) in intact tablets. The dehydration of DCPD, the disappearance of the reactants (CBZ and NMA) and the appearance of the product (CBZ-NMA cocrystal) were simultaneously monitored by quantitative powder X-ray diffractometry. In a second model system, the water of crystallization released by the dehydration of DCPD caused the chemical decomposition of aspirin. Salicylic acid, one of the decomposition products, reacted with CBZ to form CBZ-salicylic acid cocrystal in tablets. This is the first report of cocrystal formation in intact tablets, demonstrating water mediated noncovalent synthesis in a multicomponent matrix. While the potential implications of such transformations, on both the mechanical and biopharmaceutical properties, can be profound, their characterization, using conventional solution based analytical techniques, can be challenging. PMID:21548636

Arora, Kapildev K; Tayade, Nitin G; Suryanarayanan, Raj

2011-05-16

192

FINDING PIPING LEAKS WITH SEALED MILLICURIE FLOATS  

Microsoft Academic Search

A method is described in which a sealed radioisotopetagged float is used ; to find leaks in piping which runs under concrete floors or fills. The current ; caused by the leak causes the float to seek out the leak. Early studies with ; this method employed a sponge-rubber ball as a float. Spun stainless steel balls ; are being

R. E. Black; W. Kerwick

1960-01-01

193

Optimistic Parallelization of Floating-Point Accumulation  

Microsoft Academic Search

Floating-point arithmetic is notoriously non- associative due to the limited precision representation which demands intermediate values be rounded to fit in the available precision. The resulting cyclic dependency in floating-point ac- cumulation inhibits parallelization of the computation, including efficient use of pipelining. In practice, however, we observe that floating-point operations are \\

Nachiket Kapre; André Dehon

2007-01-01

194

Have Floating Rates Been a Success?  

ERIC Educational Resources Information Center

|Floating exchange rates have not lived up to all expectations, but neither have they performed as badly as some critics have suggested. Examined are the impact of floating rates on balance of payments adjustment, domestic economic policy, and inflation and the claim that floating rates have displayed excessive fluctuations. (Author/RM)|

Higham, David

1983-01-01

195

New directions in floating-point arithmetic  

Microsoft Academic Search

This article briefly describes the history of floating-point arithmetic, the development and features of IEEE standards for such arithmetic, desirable features of new implementations of floating-point hardware, and discusses work- in-progress aimed at making decimal floating-point arithmetic widely available across many architectures, operating systems, and programming languages.

Nelson H. F. Beebe

196

Unwrapping and Visualizing Cuneiform Tablets  

Microsoft Academic Search

Thousands of historically revealing cuneiform clay tablets, which were inscribed in Mesopotamia millenia ago, still exist today. Visualizing cuneiform writing is important when deciphering what is written on the tab- lets. It is also important when reproducing the tablets in papers and books. Unfortunately, scholars have found photographs to be an inadequate visualization tool, for two reasons. First, the text

Sean Eron Anderson; Marc Levoy

2002-01-01

197

Tablet PCs: The Write Approach  

ERIC Educational Resources Information Center

This article discusses the transforming effects of tablet PCs in the classroom. As 1-to-1 computing becomes the goal on K-12 campuses, school districts are turning to this newer, pen-based technology. Saint Mary's School's new Lenovo ThinkPad X41 tablet PCs had transformed the way Saint Mary's teachers did their jobs. Teachers created outlines for…

Milner, Jacob

2006-01-01

198

Application of ion exchange resin in floating drug delivery system.  

PubMed

The purpose of this study was to explore the application of low-density ion exchange resin (IER) Tulsion(R) 344, for floating drug delivery system (FDDS), and study the effect of its particle size on rate of complexation, water uptake, drug release, and in situ complex formation. Batch method was used for the preparation of complexes, which were characterized by physical methods. Tablet containing resin with high degree of crosslinking showed buoyancy lag time (BLT) of 5-8 min. Decreasing the particle size of resin showed decrease in water uptake and drug release, with no significant effect on the rate of complexation and in situ complex formation for both preformed complexes (PCs) and physical mixtures (PMs). Thus, low-density and high degree of crosslinking of resin and water uptake may be the governing factor for controlling the initial release of tablet containing PMs but not in situ complex formation. However, further sustained release may be due to in situ complex formation. PMID:18777244

Upadhye, Abhijeet A; Ambike, Anshuman A; Mahadik, Kakasaheb R; Paradkar, Anant

2008-10-01

199

The Floating Siphon - an Effective  

Microsoft Academic Search

A simple device, which can be used in place of a syringe pump, has been suggested for high dilution experiments. The flasks containing the solutions to be mixed are equipped with siphons and placed on the top of a styrofoam cylinder, or other floater. The styrofoam cylinder floats in a beaker containing water. A glass rod is threaded through a

Alexander Kolchinski

1997-01-01

200

40mm Floating Flare Development.  

National Technical Information Service (NTIS)

The 40mm Floating Flare can be launched from either the M79 or the M203 Grenade Launcher and provides troops with a standoff capability for marking a target or position in inundated areas during hours of darkness. The flotation capability is achieved by a...

D. W. Renfroe

1973-01-01

201

Flinking: Neither Floating nor Sinking.  

ERIC Educational Resources Information Center

Describes an activity that challenges students to make an object that, when released under water, does not float up or sink down. The main concept this activity investigates is the density of ordinary objects in comparison to the density of water. (PR)

Wilson, Roger B.

1993-01-01

202

Float It Down the River  

NSDL National Science Digital Library

Float it Down the River is an exciting design activity that involves students in a hands-on, creative project in which they use higher order thinking skills in a motivating setting. Students working in groups of four to six are challenged to design and bu

Orfan, Lucy; Schuhmacher, Robert; Brendzel, Sharon

2000-10-01

203

Status, trends of floating systems  

SciTech Connect

The design philosophy of floating production sytems is discussed briefly. Some of the major constraints and trade-offs involved in the design concept selection and development are discussed. Four concepts, single anchor leg, multibore riser floating production system, multibore riser floating production system/loading system, and tension leg platforms, are considered to be potentially the most attractive concepts and those that embrace all the relevant design features. The factors which determine which field development scenario, satellite wells or cluster/template wells (or perhaps a combination of these), is chosen for development of an offshore site, are discussed. Mechanical well-design requirements which must be met for either type of well development are considered. Other aspects of deepwater production that are discussed are: flowline system, installation method, riser behavior, floating unit, anchoring out, and offloading and storage. Certain foreseeable needs for the future trend of offshore drilling including technological advances to deal with deeper water, different products, and larger fields are set forth. (BLM)

Vincken, L.M.J.

1981-01-01

204

Tablet potency of Tianeptine in coated tablets by near infrared spectroscopy: model optimisation, calibration transfer and confidence intervals.  

PubMed

A near infrared (NIR) method was developed for determination of tablet potency of active pharmaceutical ingredient (API) in a complex coated tablet matrix. The calibration set contained samples from laboratory and production scale batches. The reference values were obtained by high performance liquid chromatography (HPLC) and partial least squares (PLS) regression was used to establish a model. The model was challenged by calculating tablet potency of two external test sets. Root mean square errors of prediction were respectively equal to 2.0% and 2.7%. To use this model with a second spectrometer from the production field, a calibration transfer method called piecewise direct standardisation (PDS) was used. After the transfer, the root mean square error of prediction of the first test set was 2.4% compared to 4.0% without transferring the spectra. A statistical technique using bootstrap of PLS residuals was used to estimate confidence intervals of tablet potency calculations. This method requires an optimised PLS model, selection of the bootstrap number and determination of the risk. In the case of a chemical analysis, the tablet potency value will be included within the confidence interval calculated by the bootstrap method. An easy to use graphical interface was developed to easily determine if the predictions, surrounded by minimum and maximum values, are within the specifications defined by the regulatory organisation. PMID:20965682

Boiret, Mathieu; Meunier, Loïc; Ginot, Yves-Michel

2010-10-01

205

Formulation, bioavailability, and pharmacokinetics of sustained-release potassium chloride tablets.  

PubMed

The release of potassium chloride incorporated into hydrogenated vegetable oil and hydroxypropyl methylcellulose matrix tablets was studied in vitro. The formulations containing 20% hydrogenated vegetable oil and hydroxypropyl methylcellulose showed a sustained-release profile comparable to that of a standard commercially available sustained-release preparation, containing 8 mEq potassium chloride embedded in a wax material. The formulated and standard sustained-release potassium chloride tablets were compared to a conventional enteric-coated potassium chloride tablet in 10 healthy subjects. Mean recoveries in 24-hr urine potassium levels from four dosage forms (after subtracting normal urine potassium excretion levels) were 76 +/- 32% from hydroxypropyl methylcellulose, 95 +/- 22% from hydrogenated vegetable oil-incorporated matrix tablets, 91 +/- 29% from commercially available sustained-release tablets, and 97 +/- 13% from enteric-coated tablets. There was no significant difference (P greater than 0.05) in the time to reach maximum excretion rates among the three sustained-release tablets. No significant adverse effect was experienced with any of the preparations. PMID:1796051

Senel, S; Capan, Y; Dalkara, T; Inanç, N; Hincal, A A

1991-10-01

206

Controlled release calcium silicate based floating granular delivery system of ranitidine hydrochloride.  

PubMed

The objective of the present investigation was to prepare and evaluate floating granular delivery system consisting of (i) calcium silicate (CS) as porous carrier; (ii) ranitidine hydrochloride (RH), an anti-ulcer agent; and (iii) hydroxypropyl methylcellulose K4M (HPMC) and ethylcellulose (EC) as matrix forming polymers. The effect of various formulation and process variables on the particle morphology, particle size, micromeritic properties, percent drug content, in vitro floating behavior, and in vitro drug release from the floating granules was studied. The scanning electron microscopy (SEM) of granules revealed that that more pores of CS in secondary coated granules (SCG) were covered by the polymer film than those in primary coated granules (PCG). The formulation demonstrated favorable in vitro floating and drug release characteristics. The in vivo evaluation for the determination of pharmacokinetic parameters was performed in albino rats. Higher plasma concentration was maintained throughout the study period from the floating granules of RH. The enhanced bioavailability and elimination half-life observed in the present study may be due to the floating nature of the dosage form. The results suggested that CS is a useful carrier for the development of floating and sustained release preparations. PMID:17076638

Jain, Ashish K; Jain, Sunil K; Yadav, Awesh; Agrawal, Govind P

2006-10-01

207

A CMOS floating point multiplier  

NASA Astrophysics Data System (ADS)

This paper describes a 32-bit CMOS floating point multiplier. The chip can perform 32-bit floating point multiplication (based on the proposed IEEE Standard format) and 24-bit fixed point multiplication (two's complement format) in less than 78.7 and 71.1 ns, respectively, and the typical power dissipation is 195 mW at 10 million operations per second. High-speed multiplication techniques - a modified Booth's allgorithm, a carry save adder scheme, a high-speed CMOS full adder, and a modified carry select adder - are used to achieve the above high performance. The chip is designed for compatibility with 16-bit microcomputer systems, and is fabricated in 2 micron n-well CMOS technology; it contains about 23000 transistors of 5.75 x 5.67 sq mm in size.

Uya, M.; Kaneko, K.; Yasui, J.

1984-10-01

208

Floating-Gate UVMOS inverter  

Microsoft Academic Search

This paper describes a novel technique for implementing low -voltage\\/low-power digital circuits. The threshold and supply voltage can be set to desired valueswhile exposing the chip to UV-light. UV-light activated conductances between the power supply- rails and the floating gates are used to program the desired threshold shift. The FGUVMOS inverter i s described and measurements are shown.

Yngvar Berg; Dag T. Wisland; Tor Sverre Lande

1997-01-01

209

Pipeline riser for floating platforms  

SciTech Connect

An unarticulated riser pipe for connecting a subsea pipeline to facilities on a floating platform. The riser pipe has a vertical section which is rigidly attached to a horizontal section which provides flexibility. Means are provided to maintain the tension on the vertical section. In one embodiment, a subsea frame aids in connecting the horizontal and vertical sections and then to set a limit on permitted motion of the riser pipe.

Beynet, P.A.; Williams, E.K.

1981-09-22

210

Dragging a floating horizontal cylinder  

NASA Astrophysics Data System (ADS)

A cylinder immersed in a fluid stream experiences a drag, and it is well known that the drag coefficient is a function of the Reynolds number only. Here we study the force exerted on a long horizontal cylinder that is dragged perpendicular to its axis while floating on an air-water interface with a high Reynolds number. In addition to the flow-induced drag, the floating body is subjected to capillary forces along the contact line where the three phases of liquid/solid/gas meet. We first theoretically predict the meniscus profile around the horizontally moving cylinder assuming the potential flow, and show that the profile is in good agreement with that obtained experimentally. Then we compare our theoretical predictions and experimental measurement results for the drag coefficient of a floating horizontal cylinder that is given by a function of the Weber number and the Bond number. This study can help us to understand the horizontal motion of partially submerged objects at air-liquid interface, such as semi-aquatic insects and marine plants.

Lee, Duck-Gyu; Kim, Ho-Young

2010-11-01

211

Can flexibility help you float?  

NASA Astrophysics Data System (ADS)

We consider the role of flexibility in the weight-bearing characteristics of bodies floating at an interface. Specifically, we develop a theoretical model for a two-dimensional thin floating plate that yields the maximum stable plate load and optimal stiffness for weight support. Plates small relative to the capillary length are primarily supported by surface tension, and their weight-bearing potential does not benefit from flexibility. Above a critical size comparable to the capillary length, flexibility assists interfacial flotation. For plates on the order of and larger than the capillary length, deflection from an initially flat shape increases the force resulting from hydrostatic pressure, allowing the plate to support a greater load. In this large plate limit, the shape that bears the most weight is a semicircle, which displaces the most fluid above the plate for a fixed plate length. Exact results for maximum weight-bearing plate shapes are compared to analytic approximations made in the limits of large and small plate sizes. The value of flexibility for floating to a number of biological organisms is discussed in light of our study.

Burton, L. J.; Bush, J. W. M.

2012-10-01

212

Genetics Home Reference: Floating-Harbor syndrome  

MedlinePLUS

... and Families Resources for Health Professionals What glossary definitions help with understanding Floating-Harbor syndrome? autosomal ; autosomal dominant ; brachydactyly ; cell ; clinodactyly ; cryptorchidism ; deficiency ; gene ; motor ; mutation ; ...

213

Wave Transmission and Mooring-Force Characteristics of Pipe-Tire Floating Breakwaters.  

National Technical Information Service (NTIS)

The results are presented of a series of prototype scale tests of a floating breakwater that incorporates massive cylindrical members (steel or concrete pipes, telephone poles, etc.) in a matrix of scrap truck or automobile tires, referred to as the Pipe-...

J. J. Westerink V. W. Harms

1980-01-01

214

Wave transmission and mooring-force characteristics of pipe-tire floating breakwaters  

Microsoft Academic Search

The results are presented of a series of prototype scale tests of a floating breakwater that incorporates massive cylindrical members (steel or concrete pipes, telephone poles, etc.) in a matrix of scrap truck or automobile tires, referred to as the Pipe-Tire Breakwater (PT-Breakwater). Tests were conducted in the large wave tank at the US Army Coastal Engineering Research Center (CERC).

V. W. Harms; J. J. Westerink

1980-01-01

215

Influence of Compression Force on The Behavior of Mucoadhesive Buccal Tablets  

PubMed Central

The purpose of this research was to study the compression force influence on polymers, tablet behavior and drug release rate. Several tablet batches were produced by varying the compression force and by using hydroxyethyl cellulose (HEC) and Carbopol 940 in the 1:1 ratio as matrix forming polymers. All batches were characterized by DSC and X-ray analyses and in terms of swelling, ex vivo and in vivo mucoadhesive time, ex vivo mucoadhesion force, and in vitro and in vivo release. No significant excipient–excipient or excipient–drug interactions were observed in any of the batches. All the tablets hydrated quickly and their high hydration percentage showed that the compression forces used did not remarkably affect the water penetration and the polymeric chain stretching. Mucoadhesion performances and drug release were mainly influenced by compression force; its increase produced higher ex vivo and in vivo mucoadhesion and the in vitro and in vivo drug releases were seen to decrease with the increase of the compression force. However tablets fabricated by using the lowest compression force showed the best in vivo mucoadhesive time and hydrated faster when compared to the others. Tablets 4 and 5, prepared with the highest forces, caused pain during in vivo application and gave rise to irritation needing to be detached by the volunteers while tablet 1, prepared with the lowest force, gave the best results because it was able to produce the highest drug salivary concentration and no pain. All tablets exhibited an anomalous release mechanism.

Ambrogi, Valeria; Giovagnoli, Stefano; Blasi, Paolo; Mancini, Alessandra; Ricci, Maurizio; Rossi, Carlo

2008-01-01

216

Floating platform well production apparatus  

SciTech Connect

A plurality of wells are clustered around a central riser which is maintained under tension from a floating platform. A plurality of spiders on the riser carry funnels in vertical alignment with the wells. The funnels are sufficiently large to permit the passage of wellhead connectors and master block valves, and the production risers include centralizers which brace the production riser from the funnels through a limited vertical range. Tensioning of the production riser is with a lower force and through a limited range which precludes disengagement of the centralizers from the funnel. Some centralizers are located to facilitate entry and attachment to the wellhead.

Nobileau, P.C.

1980-10-21

217

Wave drag on floating bodies  

PubMed Central

We measure the deceleration of liquid nitrogen drops floating at the surface of a liquid bath. On water, the friction force is found to be about 10 to 100 times larger than on a solid substrate, which is shown to arise from wave resistance. We investigate the influence of the bath viscosity and show that the dissipation decreases as the viscosity is increased, owing to wave damping. The measured resistance is well predicted by a model imposing a vertical force (i.e., the drop weight) on a finite area, as long as the wake can be considered stationary.

Le Merrer, Marie; Clanet, Christophe; Quere, David; Raphael, Elie; Chevy, Frederic

2011-01-01

218

A new approach combining different MRI methods to provide detailed view on swelling dynamics of xanthan tablets influencing drug release at different pH and ionic strength  

Microsoft Academic Search

The key element in drug release from hydrophilic matrix tablets is the gel layer that regulates the penetration of water and controls drug dissolution and diffusion. We have selected magnetic resonance imaging (MRI) as the method of choice for visualizing the dynamic processes occurring during the swelling of xanthan tablets in a variety of media. The aims were (i) to

Urša Mikac; Ana Sepe; Julijana Kristl; Saša Baumgartner

2010-01-01

219

E-Books and the Tablet PC.  

ERIC Educational Resources Information Center

|Highlights the emerging technologies of e-books, electronic versions of texts, and the Tablet PC, a new hybrid laptop computer and personal digital assistant that features a writing tablet and stylus-based input/navigation. (Author/VWL)|

Goodwin-Jones, Bob

2003-01-01

220

21 CFR 520.312 - Carnidazole tablets.  

Code of Federal Regulations, 2010 CFR

...Conditions of use â(1) Amount. Adult pigeons: 1 tablet (10 milligrams); newly weaned pigeons: 1/2 tablet (5 milligrams). (2...trichomoniasis (canker) in ornamental and homing pigeons. (3) Limitations. Not for...

2011-04-01

221

Galileo's Telescopy and Jupiter's Tablet  

NASA Astrophysics Data System (ADS)

A previous paper (BAAS 33:4, 1363, 2001) reported on the dramatic scene in Shakespeare's Cymbeline that features the descent of the deity Jupiter. The paper suggested that the four ghosts circling the sleeping Posthumus denote the four Galilean moons of Jupiter. The god Jupiter commands the ghosts to lay a tablet upon the prone Posthumus, but says that its value should not be overestimated. When Posthumus wakens he notices the tablet, which he calls a "book." Not only has the deity's "tablet" become the earthling's "book," but it appears that the book has covers which Posthumus evidently recognizes because without even opening the book he ascribes two further properties to it: rarity, and the very property that Jupiter had earlier attributed, viz. that one must not read too much into it. The mystery deepens when the Jovian gift undergoes a second metamorphosis, to "label." With the help of the OED, the potentially disparate terms "tablet," "book," and "label," may be explained by terms appropriate either to supernatural or worldly beings. "Tablet" may recognize the Mosaic artifact, whereas "book" and "label" are probably mundane references to Galileo's Sidereus Nuncius which appeared shortly before Cymbeline. The message of the Olympian god indicates therefore that the book is unique even as its contents have limited value. The first property celebrates the fact that Galileo's book is the first of its kind, and the second advises that all results except the discovery of Jupiter's moons have been reported earlier, in Hamlet.

Usher, P. D.

2003-12-01

222

Multispectral imaging of tablets in blister packaging  

Microsoft Academic Search

This experiment tested the hypothesis that using near-infrared (IR) imaging spectrometry on tablets through blister packs\\u000a permits the identification and composition of multiple individual tablets to be determined simultaneously. Aspirin was selected\\u000a for this study because its breakdown mechanism is well understood. Near-IR cameras were used to collect thousands of spectra\\u000a simultaneously from a field of packaged aspirin tablets. Tablets

Imran Malik; Mela Poonacha; Jennifer Moses; Robert A. Lodder

2001-01-01

223

[Preparation of sucking tablet of shengmei] off.  

PubMed

The Sucking Tablet of Shengmei is made from eight Chinese traditional drugs including Radix Adenophorae, Fructus Mume, etc. The effective rate of the tablet in treating chronic pharyngitis reaches up to 96 percent. The working mechanism related to the fact that the tablet is bacteria-resistant and helps to strengthen the body function. This paper presents the preparation process of the Sucking Tablet along with solutions for some problems encountered in the process and appropriate standards for quality control. PMID:1418578

Jiang, J; Shao, J; Zhu, Z; Dai, Y; Xu, C

1992-06-01

224

Whatever Floats Your Boat: A Design Challenge  

ERIC Educational Resources Information Center

|This article presents a simple design challenge, based on the PBS program "Design Squad's" "Watercraft" activity that will prove engaging to most technology and engineering students. In this floating boat challenge, students are to build a boat that can float and support 25 pennies for at least 10 seconds--without leaking, sinking, or tipping…

Kornoelje, Joanne; Roman, Harry T.

2012-01-01

225

Vertical penetration of floating ice sheets  

Microsoft Academic Search

Existing failure criteria for the bearing capacity of floating ice sheets predict the load for the occurrence of the first radial crack or a circumferential crack, when the maximum stress obtained from an elastic analysis in the ice equals the tensile strength. From full-scale and small-scale tests, the ultimate load to cause complete penetration of a floating ice sheet is

Devinder S. Sodhi

1998-01-01

226

Sinking Float-Operated Irrigation Gate.  

National Technical Information Service (NTIS)

The automatic check gate stops the flow of water in an irrigation ditch after the lapse of a predetermined time. A float is mounted to the gate and provided with a valve for admitting water at a controlled rate whereby the float loses its buoyancy and sin...

A. S. Humpherys

1965-01-01

227

Hydroelastic analysis of a large floating structure  

Microsoft Academic Search

An analytical approach to predict the bending vibration of a very large floating structure of thin and elongated rectangular plate configuration, floating on water of shallow depth and under the action of a monochromatic head wave, is presented. The horizontal size of the plate is huge compared with the wavelength of the incident waves, yet the wavelength is much larger

M. Ohkusu; Y. Namba

2004-01-01

228

Variable-correction truncated floating point multipliers  

Microsoft Academic Search

About half the hardware for floating point multipliers is needed only to guarantee correctly rounded results. For multimedia, graphics, and DSP systems, a significant reduction in area, delay, and power can be achieved by producing results that are not correctly rounded. This paper presents an efficient method for designing variable-correction truncated floating point multipliers that produce results with a maximum

Kent E. Wires; Michael J. Schulte; James E. Stine

2000-01-01

229

How to read floating point numbers accurately  

Microsoft Academic Search

Converting decimal scientific notation into binary floating point is nontrivial, but this conversion can be performed with the best possible accuracy without sacrificing efficiency.Consider the problem of converting decimal scientific notation for a number into the best binary floating point approximation to that number, for some fixed precision. This problem cannot be solved using arithmetic of any fixed precision. Hence

William D. Clinger

2004-01-01

230

How to read floating point numbers accurately  

Microsoft Academic Search

Consider the problem of converting decimal scientific notation for a number into the best binary floating point approximation to that number, for some fixed precision. This problem cannot be solved using arithmetic of any fixed precision. Hence the IEEE Standard for Binary Floating-Point Arithmetic does not require the result of such a conversion to be the best approximation.This paper presents

William D. Clinger

1990-01-01

231

Development of a multifunctional matrix drug delivery system surrounded by an impermeable cylinder  

Microsoft Academic Search

A multifunctional drug delivery system based on hydroxypropyl methylcellulose (HPMC)-matrices (tablets) placed within an impermeable polymeric cylinder (open at both ends) was developed. Depending on the configuration of the device, extended release, floating or pulsatile drug delivery systems could be obtained. The release behaviour of the different devices was investigated as a function of HPMC viscosity grade, HPMC content, type

I Krögel; R Bodmeier

1999-01-01

232

Sugar end-capped poly-D,L-lactides as excipients in oral sustained release tablets.  

PubMed

Sugar end-capped poly-D,L-lactide (SPDLA) polymers were investigated as a potential release controlling excipient in oral sustained release matrix tablets. The SPDLA polymers were obtained by a catalytic ring-opening polymerization technique using methyl alpha-D-gluco-pyranoside as a multifunctional initiator in the polymerization. Polymers of different molecular weights were synthesized by varying molar ratios of monomer/catalyst. The matrix tablets were prepared by direct compression technique from the binary mixtures of SPDLA and microcrystalline cellulose, and theophylline was used as a model drug. The tablet matrices showed in vitro reproducible drug release profiles with a zero-order or diffusion-based kinetic depending on the SPDLA polymer grade used. Further release from the tablet matrices was dependent on the molecular weight of the SPDLA polymer applied. The drug release was the fastest with the lowest molecular weight SPDLA grade, and the drug release followed zero-order rate. With the higher molecular weight SPDLAs, more prolonged dissolution profiles for the matrix tablets (up to 8-10 h) were obtained. Furthermore, the prolonged drug release was independent of the pH of the dissolution media. In conclusion, SPDLAs are a novel type of drug carrier polymers applicable in oral controlled drug delivery systems. PMID:19430908

Vuorinen, Sirpa; Heinämäki, Jyrki; Antikainen, Osmo; Lahcini, Mohammed; Repo, Timo; Yliruusi, Jouko

2009-05-09

233

Tablet - next generation sequence assembly visualization  

Microsoft Academic Search

Summary: Tablet is a lightweight, high-performance graphical viewer for next generation sequence assemblies and alignments. Supporting a range of input assembly formats, Tablet provides high- quality visualizations showing data in packed or stacked views, al- lowing instant access and navigation to any region of interest, and whole contig overviews and data summaries. Tablet is both multi- core aware and memory-efficient,

Iain Milne; Micha Bayer; Linda Cardle; Paul Shaw; Gordon Stephen; Frank Wright; David Marshall

2010-01-01

234

Guidance for Industry Orally Disintegrating Tablets.  

National Technical Information Service (NTIS)

This guidance provides pharmaceutical manufacturers of new and generic drug products with an Agency perspective on the definition of an orally disintegrating tablet (ODT)which is a different dosage form than, for example, a chewable tablet or a tablet tha...

2008-01-01

235

Mathematics instruction and the tablet PC  

Microsoft Academic Search

The use of tablet PCs in teaching is a relatively new phenomenon. A cross between a notebook computer and a personal digital assistant (PDA), the tablet PC has all of the features of a notebook with the additional capability that the screen can also be used for input. Tablet PCs are usually equipped with a stylus that allows the user

K. Renee Fister; Maeve L. McCarthy

2008-01-01

236

Using Tablet PCs in Engineering Education  

Microsoft Academic Search

This paper describes the experiences of using Tablet PCs along with associated software, such as Classroom Presenter and OneNote, in a course entitled Introduction to Computer Engineering. Twenty tablet PCs were distributed in a classroom of 40 students. Students used the tablets on a daily basis throughout the semester to take notes, to respond to in-class exercises, and to perform

Joseph G. Tront

237

Double-Layered Mucoadhesive Tablets Containing Nystatin  

Microsoft Academic Search

The objective of this work was to design a mucoadhesive tablet with a potential use in the treatment of oral candidosis. A 2-layered tablet containing nystatin was formulated. Lactose CD (direct compression), carbomer (CB), and hydroxypropylmethylcellulose (HPMC) were used as excipients. Tablets were obtained through direct compression. Properties such as in vitro mucoadhesion, water uptake, front movements, and drug release

Juan Manuel Llabot; Ruben Hilario Manzo; Alberto allemandi

2002-01-01

238

Condition and Error Estimates in Numerical Matrix Computations  

SciTech Connect

This tutorial paper deals with sensitivity and error estimates in matrix computational processes. The main factors determining the accuracy of the result computed in floating--point machine arithmetics are considered. Special attention is paid to the perturbation analysis of matrix algebraic equations and unitary matrix decompositions.

Konstantinov, M. M. [University of Architecture, Civil Engineering and Geodesy, 1046 Sofia (Bulgaria); Petkov, P. H. [Technical University of Sofia, 1000 Sofia (Bulgaria)

2008-10-30

239

Calcium phosphates in pharmaceutical tableting. 2. Comparison of tableting properties.  

PubMed

Ten calcium phosphates suitable for direct compression (dibasic calcium phosphate dihydrate, dibasic calcium phosphate anhydrous and hydroxylapatite) were investigated with respect to their compressional behaviour. Except for Di-Cafos A all products gave tablets with sufficient to good mechanical strength. Nevertheless, there were differences between the products. All tablets prepared from the different products showed a high friability. This seems to be a problem of the calcium phosphates in general. On the other hand, the influence of magnesium stearate on the mechanical strength of the tablets was negligible for all products investigated. Moreover, a considerable effect of the particle size on the tensile strength of the tablets was found. The ejection forces and residual pressures were high in general, but critical only in the case of hydroxylapatites. Heckel plots were used to differentiate between plastic deformation and brittle fracture of the particles. In the case of calcium phosphates the slope of the Heckel plots indicated the hardness of the particles rather than their deformation behaviour. PMID:8348107

Schmidt, P C; Herzog, R

1993-06-18

240

Encapsulation of floating carbon nanotubes in SiO2  

NASA Astrophysics Data System (ADS)

In many applications of carbon nanotubes (CNT), it is desirable to have them embedded in a dielectric such as SiO2, without significantly impacting their electronic properties. Here we study the CNT-SiO2 interface of an embedded CNT using first-principles calculations. Our results suggest that a carbon nanotube can be incorporated inside a SiO2 matrix that nucleates around it through the formation of Si-O-C bridges. The large distortion associated with the formation of these bridges can be alleviated by hydrogenation of the composite. Introduction of hydrogen in the vicinity of the bridges leads to their elimination, whereby the nanotube loses its anchoring to the matrix and it floats. For CNTs of suitable diameter, the final floating structure has electronic properties very close to the structure in vacuum. Overall, our results provide atomic-scale information that is relevant to a broad range of applications using embedded or adsorbed nanotubes, for example, sensors, electronics, actuators, and CNT coatings. This work was supported in part by DOE Grant DEFG0203ER46096.

Tsetseris, Leonidas; Pantelides, Sokrates

2007-03-01

241

Sustained release phenylpropanolamine hydrochloride from ATO 888 matrix.  

PubMed

Sustained release phenylpropanolamine HCl tablets were prepared with compritol as a retardant material. The effects of varying wax levels and methods of matrix formation on drug release were investigated. Also the compaction profiles were recorded for all formulations. The amount of drug in the formula was held constant (10% w/w), while the wax level was varied from 10% to 50% w/w. Two methods were used for the preparation of drug: wax systems; physical mixture and solid dispersion. The drug release from tablets containing 10% Compritol and prepared by solid dispersion was 97% after six hours of testing dissolution. Tablets prepared with 30% wax released 72% of the drug, while tablets containing 50% wax released only 30% of the drug after six hours. Tablets prepared by physical mixture gave higher drug release than tablets prepared by solid dispersion method. The incorporation of Compritol decreased the ejection forces of tablets during compaction. The drug release from tablets prepared by solid dispersion followed the diffusion controlled model described by Higuchi for inert porous matrix. PMID:8140204

Perez, M A; Ghaly, E S; Marti, A

1993-12-01

242

Relationship Between Gelation Rate of Controlled-release Acetaminophen Tablets Containing Polyethylene Oxide and Colonic Drug Release in Dogs  

Microsoft Academic Search

Purpose. We hypothesized that sufficient gelation of orally administered hydrophilic matrix tablets before they reach the colon could, as a result of continuous erosion of the gelated matrix, prevent the decrease in colonic drug release which normally occurs here. The purpose of this study was to elucidate the effect of gelation of hydrophilic matrices containing polyethylene oxide on colonic drug

Kazuhiro Sako; Hiroshi Nakashima; Toyohiro Sawada; Muneo Fukui

1996-01-01

243

Optimization and In vivo Pharmacokinetic Study of a Novel Controlled Release Venlafaxine Hydrochloride Three-Layer Tablet  

Microsoft Academic Search

Several matrix tablet formulations (hydrophilic-based, wax-based, and three-layer tablets) were designed for controlling the\\u000a release of the highly water soluble drug, venlafaxine hydrochloride (VenHCl) for once-daily administration. The three-layer\\u000a tablets consist of non-swellable, compritol-based middle layers containing the drug to which hydrophilic top and bottom barrier\\u000a layers were applied. A 23 full-factorial design was employed for optimization and to explore

Ahmed A. Aboelwafa; Emad B. Basalious

2010-01-01

244

Tablet PCs in undergraduate mathematics  

Microsoft Academic Search

Undergraduate students often struggle to learn mathematics because introductory classes are taught in large lectures that do not engage students in active problem-solving. These students do not connect mathematics to their lives and feel that learning mathematics is a solitary undertaking. We now use Tablet PCs in a networked classroom to address these challenges. Students in classes that use the

Carla A. Romney

2010-01-01

245

The Venus Tablet and Refraction  

Microsoft Academic Search

It is shown that the refraction near the horizon is introducing an additional bias into the Venus Tablet of Ammisaduqa, which is able to influence the interpretation of the data. We then discuss the attempts to link certain solar eclipses to the birth of Shamshi-Adad and conclude that a record of a single solar eclipse without description of details and\\/or

V. G. Gurzadyan

2003-01-01

246

Modeling of drug release from multi-unit dosage tablets of theophylline  

Microsoft Academic Search

-1 . The prompt release component (A) consisted of conventional granules of the drug while the sustained release component (B) was made up of matrix granules of the drug obtained by melt granulation i.e. granulating the drug powder with a melted wax (carnuba). To form the multi-unit dose tablets, granules of A and B were mixed together in various proportions

U. Uhumwangho Michael; S. Okor

2007-01-01

247

Determination of water in aluminum chlorohydrate and effervescent tablets by Karl Fischer Analysis.  

PubMed

A procedure was developed for the quantitative determination of loosely bound water in aluminum chlorohydrate and the water content in denture cleanser effervescent tablets. The basic method involves extracting the water from the sample into dioxane followed by titration of the dioxane in methanol with Karl Fischer Reagent. Matrix Ingredients did not interfere. PMID:758451

Spitz, H D

1979-01-01

248

FloatNet: An Intelligent Environment for Tobacco Transplants Production  

Microsoft Academic Search

A web environment has been designed for managing float system tobacco transplants cultivation. The environment is called FloatNET and includes an integrated interface supports Tobacco transplants cultivation. The float system is located in a greenhouse and consists of floor beds - so called 'wet beds' - were filled with nutrient solution. Transplants are developed on float Styrofoam trays filled with

Aglaia Liopa-Tsakalidis; Pantelis Barouchas; Athanasios Koulopoulos; Evangelos Sakkopoulos; Giannis Tzimas; Leonidas Panagiotopoulos

249

14 CFR 25.751 - Main float buoyancy.  

Code of Federal Regulations, 2010 CFR

...2009-01-01 2009-01-01 false Main float buoyancy. 25.751 Section 25.751 Aeronautics...Floats and Hulls § 25.751 Main float buoyancy. Each main float must haveâ (a) A buoyancy of 80 percent in excess of that...

2009-01-01

250

14 CFR 27.751 - Main float buoyancy.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 2013-01-01 false Main float buoyancy. 27.751 Section 27.751 Aeronautics...Floats and Hulls § 27.751 Main float buoyancy. (a) For main floats, the buoyancy necessary to support the maximum weight...

2013-01-01

251

14 CFR 25.751 - Main float buoyancy.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 2013-01-01 false Main float buoyancy. 25.751 Section 25.751 Aeronautics...Floats and Hulls § 25.751 Main float buoyancy. Each main float must haveâ (a) A buoyancy of 80 percent in excess of that...

2013-01-01

252

14 CFR 25.751 - Main float buoyancy.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Main float buoyancy. 25.751 Section 25.751 Aeronautics...Floats and Hulls § 25.751 Main float buoyancy. Each main float must haveâ (a) A buoyancy of 80 percent in excess of that...

2010-01-01

253

14 CFR 29.751 - Main float buoyancy.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 2013-01-01 false Main float buoyancy. 29.751 Section 29.751 Aeronautics...Floats and Hulls § 29.751 Main float buoyancy. (a) For main floats, the buoyancy necessary to support the maximum weight...

2013-01-01

254

14 CFR 23.751 - Main float buoyancy.  

Code of Federal Regulations, 2010 CFR

... 2009-01-01 false Main float buoyancy. 23.751 Section 23.751 Aeronautics...Floats and Hulls § 23.751 Main float buoyancy. (a) Each main float must haveâ (1) A buoyancy of 80 percent in excess of the...

2009-01-01

255

14 CFR 27.751 - Main float buoyancy.  

Code of Federal Regulations, 2010 CFR

...2009-01-01 2009-01-01 false Main float buoyancy. 27.751 Section 27.751 Aeronautics...Floats and Hulls § 27.751 Main float buoyancy. (a) For main floats, the buoyancy necessary to support the maximum weight...

2009-01-01

256

14 CFR 23.751 - Main float buoyancy.  

Code of Federal Regulations, 2010 CFR

... 2010-01-01 false Main float buoyancy. 23.751 Section 23.751 Aeronautics...Floats and Hulls § 23.751 Main float buoyancy. (a) Each main float must haveâ (1) A buoyancy of 80 percent in excess of the...

2010-01-01

257

14 CFR 23.751 - Main float buoyancy.  

Code of Federal Regulations, 2013 CFR

... 2013-01-01 false Main float buoyancy. 23.751 Section 23.751 Aeronautics...Floats and Hulls § 23.751 Main float buoyancy. (a) Each main float must haveâ (1) A buoyancy of 80 percent in excess of the...

2013-01-01

258

Programming floating-gate circuits with UV-activated conductances  

Microsoft Academic Search

A programming technique for controlling the floating gates (FGs) in ultra-low-voltage (ULV) floating-gate circuits is presented. Simple ULV PG current-scaling and level-shifting circuits are discussed. The current scaling and level shifting are accomplished using only minimum sized transistors and floating capacitors. Floating-gate current multiplier and divider circuits are described. Measured results are provided,

Yngvar Berg; Tor S. Lande; O. Naess

2001-01-01

259

Technical and economic aspects of a floating offshore wind farm  

Microsoft Academic Search

Development of the conceptual design for FLOAT – an offshore floating wind turbine – is described in this paper. This design represents a marriage of the wind power and offshore oil and gas technology. The objective of the FLOAT project is to develop a floating wind turbine system enabling the economic generation of electricity from wind power in offshore locations,

K. C Tong

1998-01-01

260

Characterization of spiral inductors with patterned floating structures  

Microsoft Academic Search

The impact of two different types of floating patterns on spiral inductors was investigated. Both patterned trench isolation with a floating p\\/n junction and floating metal poles were implemented underneath reference spiral inductors. All three types of inductors have an identical spiral geometry. Combination of patterned trench isolation with a floating p\\/n junction increases maximum quality factor (Qmax) by 17%

Chiaming Alex Chang; Sung-Pi Tseng; Jun Yi Chuang; Shiue-Shr Jiang; J. Andrew Yeh

2004-01-01

261

Properties of hot-melt extruded theophylline tablets containing poly(vinyl acetate).  

PubMed

The objectives of this study were to investigate the properties of poly(vinyl acetate) (PVAc) as a retardant polymer and to study the drug release mechanism of theophylline from matrix tablets prepared by hot-melt extrusion. A physical mixture of drug, polymer, and drug release modifiers was fed into the equipment and heated inside the barrel of the extruder. The cylindrical extrudates were either cut into tablets or ground into granules and compressed with other excipients into tablets. Due to the low glass transition temperature of the PVAc, the melt extrusion process was conducted at approximately 70 degrees C. Theophylline was used as the model drug in this study. Theophylline was present in the extrudate in its crystalline form and was released from the tablets by diffusion. The Higuchi diffusion model and percolation theories were applied to the dissolution data to explain the drug release properties of the matrix systems. The release rate was shown to be dependent on the granule size, drug particle size, and drug loading in the tablets. Water-soluble polymers were demonstrated to be efficient release rate modifiers for this system. PMID:10914317

Zhang, F; McGinity, J W

2000-09-01

262

Understanding and Improving Sorbents for Floating Oil.  

National Technical Information Service (NTIS)

Acquisition of floating oil by sorbents involves a balance between internal permeation processes and external phenomena occurring in the oil pool. As a basis for improving sorbents and sorbent systems, this program considers internal and external processe...

L. D. Nichols

1974-01-01

263

Prototype Performance Characteristics of a Floating Breakwater.  

National Technical Information Service (NTIS)

The characteristics, i.e., transmission coefficients, anchor forces, and accelerations in heave, roll, and sway are evaluated from measurements taken on a floating breakwater protecting a small boat harbor at Tenakee Springs, AL. The breakwater consists o...

D. R. Christensen E. P. Rickey

1974-01-01

264

Current Mirror with Programmable Floating Gate.  

National Technical Information Service (NTIS)

Systems and methods are discussed for using a floating-gate MOSFET as a programmable reference circuit. One example of the programmable reference circuit is a programmable voltage reference source, while a second example of a programmable reference circui...

G. J. Serrano P. E. Hasler

2006-01-01

265

Exploring Floating Concrete and Beam Design.  

ERIC Educational Resources Information Center

|Presents two construction activities that address both state and federal science standards and encourage students to consider career options in mathematics and science. Includes floating concrete and paper bridge activities. (YDS)|

Snell, Billie G.; Snell, Luke M.

2002-01-01

266

PLM Floating-Point Interface Program.  

National Technical Information Service (NTIS)

A major failing of Intel's PLM language is its inability to handle scientific notation (floating-point) calculations. An interface program that allows PLM to perform such calculations is described. A comparison of this modified PLM with an assembly langua...

C. Paoni M. Maples

1976-01-01

267

Floating patterns of metered dose inhalers.  

PubMed

As long as metered dose inhalers have existed, patients have sought a reliable method to determine if a given canister was still potent. Concerning beta agonists, the answer to this question may be lifesaving. Issues of compliance have made dating canisters or counting doses impractical. Likewise, previous claims of floating characteristics are unreliable. In tap water, we float-tested 13 commonly used inhalers three times each, observing variations as they were incrementally actuated, emptying their contents. One essential pattern was observed. Almost all prescription-size canisters sink when full; all float by the time one-third of their contents is gone. Orientation of prescription-size canisters changes in a distinct pattern especially near 90% depletion. Sample-size canisters showed some variance. Results suggest that the pharmaceutical industry should include individual floating characteristics as part of the package insert as they provide a reproducible means of gauging contents. PMID:9350161

Wolf, B L; Cochran, K R

1997-01-01

268

Instability of Thermocapillary Convection in Floating Zones.  

National Technical Information Service (NTIS)

Bifurcation theory combined with the finite difference method is applied to investigate the instability of thermocapillary convection in a model of the floating zone crystal growth process. Both axisymmetric (n = 0) and nonaxisymmetric (n greater than or ...

G. Chen B. Roux

1992-01-01

269

Pharmaceutical and analytical evaluation of triphalaguggulkalpa tablets  

PubMed Central

Aim of the Study: Development of standardized, synergistic, safe and effective traditional herbal formulations with robust scientific evidence can offer faster and more economical alternatives for the treatment of disease. The main objective was to develop a method of preparation of guggulkalpa tablets so that the tablets meet the criteria of efficacy, stability, and safety. Materials and Methods: Triphalaguggulkalpa tablet, described in sharangdharsanhita and containing guggul and triphala powder, was used as a model drug. Preliminary experiments on marketed triphalaguggulkalpa tablets exhibited delayed in vitro disintegration that indicated probable delayed in vivo disintegration. The study involved preparation of triphalaguggulkalpa tablets by Ayurvedic text methods and by wet granulation, dry granulation, and direct compression method. The tablets were evaluated for loss on drying, volatile oil content, % solubility, and steroidal content. The tablets were evaluated for performance tests like weight variation, disintegration, and hardness. Results: It was observed that triphalaguggulkalpa tablets, prepared by direct compression method, complied with the hardness and disintegration tests, whereas tablets prepared by Ayurvedic text methods failed. Conclusion: Direct compression is the best method of preparing triphalaguggulkalpa tablets.

Savarikar, Shreeram S.; Barbhind, Maneesha M.; Halde, Umakant K.; Kulkarni, Alpana P.

2011-01-01

270

Evaluation of the potential use of poly(ethylene oxide) as tablet- and extrudate-forming material.  

PubMed

The purpose of this study was to assess the potential use of poly(ethylene oxide) (PEO) as matrix-forming material for tablets and extrudates. Raw materials were characterized for size, size distribution, and shape. Tablets with 2- and 10-mm diameter were prepared by direct compression at both 13 and 38 MPa from mixtures with poly(ethylene oxide)s, a model drug (propranolol hydrochloride), and lactose. To these mixtures water was added (16%-43%) prior to extrusion in a ram extruder fit with different dies (1-, 3-, 6-, and 9-mm diameter and 4-mm length). Tablets and extrudates were characterized for work of compression or extrusion, respectively, relaxation, tensile strength, friability, and drug release. Both PEOs produced tablets easily and with different properties. Some relaxation was observed, particularly for tablets with higher amounts of PEOs. Release of the drug occurred after swelling of the matrix, and between 10% and 70% drug released, a quasi zero-order release was observed for large tablets. Extrusion was possible for formulations with PEO only with amounts of water between 16% and 50%. Both radial and axial relaxation of both plugs and extrudates were observed. Moreover, different extrusion profiles reflected the different behaviors of the different formulations. The model drug was released in the same fashion as observed for the tablets. It was possible to produce tablets by direct compression and extrudates or pellets from those extrudates from different formulations with PEO. Tablets and pellets have shown distinct properties depending upon the PEO considered. Extrusion was particularly complex with different formulations with PEO. PMID:15760045

Pinto, João F; Wunder, Kathrin F; Okoloekwe, Andrea

2004-04-14

271

Evaluation of the potential use of poly(ethylene oxide) as tablet- and extrudate-forming material.  

PubMed

The purpose of this study was to assess the potential use of poly(ethylene oxide) (PEO) as matrix-forming material for tablets and extrudates. Raw materials were characterized for size, size distribution, and shape. Tablets with 2- and 10-mm diameter were prepared by direct compression at both 13 and 38 MPa from mixtures with poly(ethylene oxide)s, a model drug (propranolol hydrochloride) and lactose. To these mixtures water was added (16%-43%) prior to extrusion in a ram extruder fit with different dies (1-, 3-, 6-, and 9-mm diameter and 4-mm length). Tablets and extrudates were characterized for work of compression or extrusion, respectively, relaxation, tensile strength, friability, and drug release. Both PEOs produced tablets easily and with different properties. Some relaxation was observed, particularly for tablets with higher amounts of PEOs. Release of the drug occurred after swelling of the matrix, and between 10% and 70% drug released, a quasi zero-order release was observed for large tablets. Extrusion was possible for formulations with PEO only with amounts of water between 16% and 50%. Both radial and axial relaxation of both plugs and extrudates were observed. Moreover, different extrusion profiles reflected the different behaviors of the different formulations. The model drug was released in the same fashion as observed for the tablets. It was possible to produce tablets by direct compression and extrudates or pellets from those extrudates from different formulations with PEO. Tablets and pellets have shown distinct properties depending upon the PEO considered. Extrusion was particularly complex with different formulations with PEO. PMID:18465267

Pinto, João F; Wunder, Kathrin F; Okoloekwe, Andrea

2004-01-01

272

Floating drug delivery systems: A review  

Microsoft Academic Search

The purpose of writing this review on floating drug delivery systems (FDDS) was to compile the recent literature with special\\u000a focus on the principal mechanism of floatation to achieve gastric retention. The recent developments of FDDS including the\\u000a physiological and formulation variables affecting gastric retention, approaches to design single-unit and multiple-unit floating\\u000a systems, and their classification and formulation aspects are

Shweta Arora; Javed Ali; Alka Ahuja; Roop K. Khar; Sanjula Baboota

2005-01-01

273

Gas transfer in floating-leaved plants  

Microsoft Academic Search

Pressurized gas transport with flow rates of 1.1 to 1.81 gas h-1 plant-1 have been detected in the floating-leaved aquatic macrophyte Euryale ferox on sunny days. The younger leaves gave the highest pressurization, but the gas flow was initiated mainly by the middle-aged leaves of the plants. The gas through-flow was shown to be highly beneficial for floating-leaved plants. It

W. Große; C. Bauch

1991-01-01

274

Decimal Floating-Point: Algorism for Computers  

Microsoft Academic Search

Decimal arithmetic is the norm in human calculations, and human-centric applications must use a decimal floating-point arithmetic to achieve the same results. Initial benchmarks indicate that some applications spend 50% to 90% of their time in decimal processing, because software decimal arithmetic suffers a 100× to 1000× performance penalty over hardware. The need for decimal floating-point in hardware is urgent.

Michael F. Cowlishaw; Coventry CV

2003-01-01

275

Studies of Marangoni convection in floating zones  

Microsoft Academic Search

Marangoni convection (MC) has been studied in a NaNO3-floating zone by flow visualization and temperature measurements under 1-g and under 0.4 g (sounding rocket TEXUS IIIa). The effects of surface tension forces and buoyant forces have been separated by suppression of MC with a surface contamination. MC is the dominating flow in small volumes. Time dependent MC in floating zones

D. Schwabe; A. Scharmann; F. Preisser

1982-01-01

276

Floating intake reduces pump damage  

SciTech Connect

The solution to a costly sand erosion problem at the Grande Dixence hydroelectric project in Switzerland turned out to be as simple as a floating pump. The 726-MW Grande Dixence project drains a 350-square-kilometer reach of the Zermatt and Herens valleys in the southwestern Swiss Alps. About half of the drainage area is covered by active glaciers. Because the glaciers in Zermatt Valley are so low in altitude, their water is collected in Z`mutt Reservoir at the base of the Matterhorn, then pumped up 500 meters for transport to the main Grande Disence Reservoir near Sion. The glacier water is heavily laden with sand. In spite of a gravel pass and a desilter, the 700,000-acubic-meter Z`mutt Reservoir receives large quantities of sand. The sand tends to remain in solution because of the low water temperatures (1 to 2 degrees Centigrade). In the original intake system, the sand would be sucked into the pump intakes, causing extensive erosion to the pump wheels and an expensive yearly program of repair. (Pump damage averaged 200,000 Swiss Francs ($284,000 U.S.) per year between 1980 and 1985.)

Kronig, A.

1993-12-31

277

Further improvement of orally disintegrating tablets using micronized ethylcellulose.  

PubMed

The aim of this study is to design a new orally disintegrating tablet (ODT) containing micronized ethylcellulose (MEC). The new ODT was prepared by physical mixing of rapidly disintegrating granules (RDGs) with MEC. To obtain RDGs, mannitol was spray-coated with a suspension of corn starch and crospovidone (9:1, w/w ratio) using a fluidized-bed granulator (suspension spray-coating method). The new ODTs were evaluated for their hardness, friability, thickness, internal structure (X-ray-CT scanning), in vivo disintegration time, and water absorption rate. Since MEC increases tablet hardness by increasing the contact frequency between the granules, the new ODTs could obtain high hardness (>50 N) and low friability (<0.5 %) with relatively low compression force. In addition, fine capillary channels formed in ODTs facilitated the wicking action and enabled rapid disintegration in vivo (<30 s). On the other hand, since MEC has low hygroscopicity, the tablet hardness of ODTs containing MEC remained high for 1 month in high-humidity conditions. In conclusion, the new ODTs containing MEC developed in this study possessed superior properties for clinical use and are expected to be applied for a wide range of functionally released drugs for bitter taste masking, sustained release, and controlled release (pH-dependent film coating, matrix, and microcapsule). PMID:22138608

Okuda, Yutaka; Irisawa, Yosuke; Okimoto, Kazuto; Osawa, Takashi; Yamashita, Shinji

2011-11-26

278

Fentanyl buccal tablet.  

PubMed

Studies of populations with chronic cancer pain have shown a high prevalence of breakthrough pain (BTP), defined as transitory, severe flares of pain that occur on a background of otherwise controlled, persistent pain. High BTP prevalence rates have also been reported in patients with chronic noncancer pain, although data in these patient populations are more limited. The incidence of BTP appears to be associated with progression of chronic disease, with more than 80% of patients reporting BTP with far-advanced, end-stage cancer and noncancer terminal conditions (1). The most widely accepted therapeutic approach for the management of BTP involves use of short-acting opioids taken as needed in addition to the around-the-clock opioid regimen being used for the continuous component of the persistent pain syndrome. For some patients, an optimal treatment outcome for BTP may be unattainable because of a mismatch between the time course of the BTP episode and the onset of analgesia of short-acting opioids. Breakthrough pain typically reaches peak intensity within a few minutes, whereas the onset of analgesia with traditional, orally administered short-acting opioids is between 30 and 60 minutes (2-7). Consequently, treatment outcomes for BTP are likely to be improved with agents that have a more rapid onset of analgesia. Fentanyl buccal tablet (FBT) is a new formulation of fentanyl indicated for the management of BTP in patients with cancer who are already receiving, and who are tolerant to, opioid therapy for their underlying persistent cancer pain. The FBT formulation uses OraVescent (Cephalon, Inc., Frazer, PA, USA) drug delivery technology to provide rapid absorption of fentanyl through the buccal mucosa. In pharmacokinetic studies in healthy volunteers, FBT demonstrated high, early systemic absorption. In addition, FBT delivered a larger proportion of the fentanyl dose transmucosally and produced a greater early systemic exposure than oral transmucosal fentanyl citrate (OTFC), which is also indicated for the management of BTP in opioid-tolerant cancer patients. A number of short-term studies have evaluated the efficacy, safety and tolerability of FBT in the management of BTP in opioid-tolerant patients with chronic pain. All these studies included an open-label dose-titration phase prior to randomized, placebo-controlled, double-blind treatment. Pain Intensity of a BTP episode was measured using an 11-point scale (0 = no pain, 10 = worst pain), and the primary outcome measure was the Summed Pain Intensity Difference (SPID) at a specified time point. Secondary efficacy measures included Pain Relief, Pain Intensity Differences, and the proportion of BTP episodes demonstrating >or=33% and >or=50% improvement in Pain Intensity scores at each time point postdose, and the proportion of BTP episodes requiring supplemental medication. In a pivotal study of opioid-tolerant patients with cancer-related chronic pain and BTP, the primary outcome measure, SPID at 30 minutes (SPID(30)), significantly favored FBT compared with placebo (mean +/- SE: 3.0 +/- 0.12 vs. 1.8 +/- 0.18, p<0.0001). Better efficacy was also observed with FBT compared with placebo for pain relief, Pain Intensity Differences, and the proportion of episodes showing >or=33% and >or=50% improvement in Pain Intensity Scores. Treatment with FBT was generally well tolerated. Most adverse events were mild to moderate in severity and typical of those associated with opioid use (e.g., nausea, dizziness) (8). Similar results have been observed in studies of opioid-tolerant patients with BTP in association with noncancer-related chronic pain. In a study of patients with chronic low back pain, the primary outcome measure, SPID(60), significantly favored FBT over placebo (mean +/- SE: 8.3 +/- 0.66 vs. 3.6 +/- 0.57, p <0.0001). All secondary efficacy measures were similarly improved, with Pain Intensity Differences and Pain Relief scores showing significant differences versus placebo as early as 10 and 15 minutes, respectively. As in the study of cancer patient

Messina, John; Darwish, Mona; Fine, Perry G

2008-01-01

279

In Vitro and in Vivo Evaluation in Dogs and Pigs of a Hydrophilic Matrix Containing Propylthiouracil  

Microsoft Academic Search

A hydrophilic matrix tablet containing 300 mg of propylthiouracil was formulated with several types of hydroxypropylmethylcellulose. The influence of polymer and drug granule particle size, polymer concentration, crystallinity and geometry of the polymer particles, the polymer incorporation outside or inside the granule, addition of a filler and tablet hardness were studied. Polymer concentration, polymer particle size and geometry, filler addition

Louis Kabanda; Romain Adelin Lefebvre; Henri Jacques Bree; Jean Paul Remon

1994-01-01

280

The Venus Tablet and Refraction  

Microsoft Academic Search

It is shown that the refraction near the horizon is introducing an additional\\u000abias into the Venus Tablet of Ammisaduqa, which is able to influence the\\u000ainterpretation of the data. We then discuss the attempts to link certain solar\\u000aeclipses to the birth of Shamshi-Adad and conclude that a record of a single\\u000asolar eclipse without description of details and\\/or

V. G. Gurzadyan

2003-01-01

281

Double-layered mucoadhesive tablets containing nystatin  

Microsoft Academic Search

The objective of this work was to design a mucoadhesive tablet with a potential use in the treatment of oral candidosis. A\\u000a 2-layered tablet containing nystain was formulated. Lactose CD (direct compression), carbomer (CB), and hydroxypropylmethylcellulose\\u000a (HPMC) were used as excipients. Tablets were obtained through direct compression. Properties such as in vitro mucoadhesion,\\u000a water uptake, front movements, and drug release

Juan Manuel Llabot; Ruben Hilario Manzo; Alberto allemandi

2002-01-01

282

BEYOND THE TABLET PC USING THE TABLET PC IN A COLLABORATIVE LEARNING ENVIRONMENT  

Microsoft Academic Search

This research focuses on the use of the Tablet PC in education. The research explores the development of the Tablet PC and introduces the Classroom Presenter software. Implementation efforts of both the Tablet PC and the Classroom Presenter software at Coastal Carolina University are explored.

JEAN H. FRENCH

283

Airship-floated wind turbine  

SciTech Connect

A wind turbine, by use of a tethered airship for support, may be designed for the economical recovery of power at heights of 2,000 feet or more above ground, at which height power density in the wind is typically three times the power density available to a conventionally supported wind turbine. Means can be added to such an airship-floated wind turbine which will permit its generators to be used to meet load demand even during periods of little or no wind. Described to this end is a wind turbine system which combines, among other novel features: a novel tether line system which provides access for men and materials to the supporting airship while in active service, a novel system for providing additional buoyant lift at the nose of the turbine-supporting airship to offset the vertical component of tension induced in the tether line by the downwind force exerted by the turbine blades, a novel bearing assembly at the nose of the supporting airship which permits the airship to rotate as a unit with the turbine it supports without causing a similar rotation of the tether line, a novel turbine airship structure which handles concentrated loads from the turbine efficiently and also permits the safe use of hydrogen for buoyancy, a novel ''space frame'' structure which supports the turbine blades and greatly reduces blade weight, a novel system for controlling turbine blade angle of incidence and for varying blade incidene in synchrony with blade angular position abut the turbine axis to provide greater control over airship movement, a novel system for locating propellor-driven generators out at the wind turbine perimeter and for using lightweight, high-RPM generators to produce electrical energy at a power line frequency, which greatly reduces the weight required to convert turbine blade torque into useful power, and a novel system for incorporating compressed air storage and combustion turbine components into the wind turbine's generator drive systems.

Watson, W. K.

1985-01-01

284

Formulation and optimization of mucoadhesive bilayer buccal tablets of atenolol using simplex design method  

PubMed Central

Introduction: In the present study, mucoadhesive buccal bilayer tablets of atenolol were fabricated with the objective of avoiding first pass metabolism and to improve its bioavailability with reduction in dosing frequency. Hence, the aim of this work was to design oral controlled release mucoadhesive tablets of atenolol and to optimize the drug release profile and bioadhesion. Materials and Methods: Bilayer buccal tablets of atenolol were prepared by direct compression method using simplex method of optimization to investigate the combined effect of hydroxypropyl methylcellulose 15 cps (X1), Carbopol (X2) and mannitol (X3); the in vitro drug release (Y1) and mucoadhesive strength (Y2) were taken as responses. The designed tablets were evaluated for various physical and biological parameters like drug content uniformity, in vitro drug release, short-term stability, and drug- excipient interactions (FTIR). Results: The formulation C containing hydroxypropyl methylcellulose 15 cps (10% w/w of matrix layer), Carbopol 934p (10% w/w of matrix layer) and mannitol (channeling agent, 40% w/w of matrix layer) was found to be promising. This formulation exhibited an in vitro drug release of 89.43% in 9 h along with satisfactory bioadhesion strength (7.20 g). Short-term stability studies on the promising formulation indicated that there are no significant changes in drug content and in vitro dissolution characteristics (P<0.05). IR spectroscopic studies indicated that there are no drug-excipient interactions.

Shirsand, SB; Suresh, Sarasija; Keshavshetti, GG; Swamy, PV; Reddy, P Vijay Prakash

2012-01-01

285

Optimization and in vivo pharmacokinetic study of a novel controlled release venlafaxine hydrochloride three-layer tablet.  

PubMed

Several matrix tablet formulations (hydrophilic-based, wax-based, and three-layer tablets) were designed for controlling the release of the highly water soluble drug, venlafaxine hydrochloride (VenHCl) for once-daily administration. The three-layer tablets consist of non-swellable, compritol-based middle layers containing the drug to which hydrophilic top and bottom barrier layers were applied. A 2(3) full-factorial design was employed for optimization and to explore the effect of different variables on the release rate of the drug from the three-layer tablets. The optimized levels of each independent variable were based on the criterion of desirability. The calculated values of f(1) and f(2) were 4.131 and 79.356, respectively; indicating that the release profile of the optimized PEO layered tablet formulation is comparable to that of the target release model. The pharmacokinetic parameters of VenHCl from the optimized three-layer tablet was compared to the marketed extended release capsule as a reference in healthy human subjects using a randomized crossover design. In this study, the 90% confidence interval for AUC(0-24) and AUC(0-?) are within (0.8-1.25), which satisfied the bioequivalence criteria. It could be concluded that a promising once-daily extended-release three-layer tablet of the highly water soluble drug, VenHCl, was successfully designed. PMID:20532709

Aboelwafa, Ahmed A; Basalious, Emad B

2010-06-08

286

Optimization and In vivo Pharmacokinetic Study of a Novel Controlled Release Venlafaxine Hydrochloride Three-Layer Tablet  

PubMed Central

Several matrix tablet formulations (hydrophilic-based, wax-based, and three-layer tablets) were designed for controlling the release of the highly water soluble drug, venlafaxine hydrochloride (VenHCl) for once-daily administration. The three-layer tablets consist of non-swellable, compritol-based middle layers containing the drug to which hydrophilic top and bottom barrier layers were applied. A 23 full-factorial design was employed for optimization and to explore the effect of different variables on the release rate of the drug from the three-layer tablets. The optimized levels of each independent variable were based on the criterion of desirability. The calculated values of f1 and f2 were 4.131 and 79.356, respectively; indicating that the release profile of the optimized PEO layered tablet formulation is comparable to that of the target release model. The pharmacokinetic parameters of VenHCl from the optimized three-layer tablet was compared to the marketed extended release capsule as a reference in healthy human subjects using a randomized crossover design. In this study, the 90% confidence interval for AUC0–24 and AUC0?? are within (0.8–1.25), which satisfied the bioequivalence criteria. It could be concluded that a promising once-daily extended-release three-layer tablet of the highly water soluble drug, VenHCl, was successfully designed.

Basalious, Emad B.

2010-01-01

287

Battery charging in float vs. cycling environments  

SciTech Connect

In lead-acid battery systems, cycling systems are often managed using float management strategies. There are many differences in battery management strategies for a float environment and battery management strategies for a cycling environment. To complicate matters further, in many cycling environments, such as off-grid domestic power systems, there is usually not an available charging source capable of efficiently equalizing a lead-acid battery let alone bring it to a full state of charge. Typically, rules for battery management which have worked quite well in a floating environment have been routinely applied to cycling batteries without full appreciation of what the cycling battery really needs to reach a full state of charge and to maintain a high state of health. For example, charge target voltages for batteries that are regularly deep cycled in off-grid power sources are the same as voltages applied to stand-by systems following a discharge event. In other charging operations equalization charge requirements are frequently ignored or incorrectly applied in cycled systems which frequently leads to premature capacity loss. The cause of this serious problem: the application of float battery management strategies to cycling battery systems. This paper describes the outcomes to be expected when managing cycling batteries with float strategies and discusses the techniques and benefits for the use of cycling battery management strategies.

COREY,GARTH P.

2000-04-20

288

Structured matrix methods for polynomial root-finding  

Microsoft Academic Search

In this paper we discuss the use of structured matrix meth- ods for the numerical approximation of the zeros of a univari- ate polynomial. In particular, it is shown that root-finding algorithms based on floating-point eigenvalue computation can benefit from the structure of the matrix problem to re- duce their complexity and memory requirements by an order of magnitude.

Luca Gemignani

2007-01-01

289

The floating-gate non-volatile semiconductor memory--from invention to the digital age.  

PubMed

In the past 45 years (from 1967 to 2012), the non-volatile semiconductor memory (NVSM) has emerged from a floating-gate concept to the prime technology driver of the largest industry in the world-the electronics industry. In this paper, we briefly review the historical development of NVSM and project its future trends to the year 2020. In addition, we consider NVSM's wide-range of applications from the digital cellular phone to tablet computer to digital television. As the device dimension is scaled down to the deca-nanometer regime, we expect that many innovations will be made to meet the scaling challenges, and NVSM-inspired technology will continue to enrich and improve our lives for decades to come. PMID:23421120

Sze, S M

2012-10-01

290

Blow-off float vehicle recovery apparatus  

US Patent & Trademark Office Database

The invention in one variation is a modular recovery apparatus for dispensing a tether spool having a tow line with a float, where the tow line can be used to retrieve an unmanned underwater vehicle and other underwater platforms. The modular recovery apparatus can be triggered underwater or on the surface, and being modular in configuration it is suitable to be fitted to a variety of unmanned underwater vehicles (UUVs). The apparatus has a tether spool that is spring loaded, such that when the tether spool is deployed, the spring expels the tether spool with sufficient force to clearly separate it from the UUV. One end of the tow line is typically fastened to a tow point on the UUV, and an opposing end is attached to the float. When the tether spool is deployed, the tow line unwinds from the float, providing a securable length.

Gibson; Robert (Panama City, FL); Hollis; Walt (Panama City, FL); Leasko; Robert A. (Panama City, FL)

2012-05-01

291

Anti-pollution and antifire floating barrier  

SciTech Connect

The barrier of this invention is formed by barrier sections and each of them can be wound up about a reel or bobbin, which is pivotably mounted within a main floating hollow element, which not only has the task of receiving, transporting, towing, launching and trawling the barrier section housed therein, but also it serves to provide anchoring points for this barrier. Each main barrier element is shaped in the form of a cage-like container provided with at least a side vertical entrance passage , through which a barrier section can be returned inside the container, or this section can be caused to come out, each main floating element thus serving as floating container for the transport of at least one of the barrier sections to or from their use place.

Bossa, E.D.

1981-07-21

292

Improved Packaging of Water Purification Tablet.  

National Technical Information Service (NTIS)

The new method of packaging the iodine tablets consists of sealing the individual tablets in a blister sheet and packaging two blister sheets in an overwrapper packet. The blister sheet measures 1 3/4 in x 2 1/8 in and contains 12 transparent blister unit...

J. L. Carney

1974-01-01

293

21 CFR 520.1870 - Praziquantel tablets.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Praziquantel tablets. 520.1870 Section 520...FORM NEW ANIMAL DRUGS § 520.1870 Praziquantel tablets. (a) Specifications ...contains: (1) 34 milligrams (mg) praziquantel. (2) 11.5 or 23 mg...

2013-04-01

294

Fluoride Tablets and Salivary Fluoride Levels  

Microsoft Academic Search

Mixed salivary fluoride levels have been measured after 9 subjects sucked or slowly dissolved three different brands of 1 mg F–– fluoride tablets. Results indicate that for all preparations the maximum salivary F–– concentration was obtained when a tablet was sucked rather than dissolved. However, salivary F–– retention was greatly enhanced under conditions which allowed undisturbed disintegration of each formulation.

D. McCall; K. W. Stephen; S. G. McNee

1981-01-01

295

Enhancing Student Performance Using Tablet Computers  

ERIC Educational Resources Information Center

|Tablet PCs have the potential to change the dynamics of classroom interaction through wireless communication coupled with pen-based computing technology that is suited for analyzing and solving engineering problems. This study focuses on how tablet PCs and wireless technology can be used during classroom instruction to create an Interactive…

Enriquez, Amelito G.

2010-01-01

296

Tablet computers in the veterinary curriculum.  

PubMed

Tablet computers offer a new method of information management in veterinary medical education. With the tablet computer, students can annotate class notes using electronic ink, search for keywords, and convert handwriting to text as needed. Additional electronic learning resources, such as medical dictionaries and electronic textbooks, can be readily available. Eleven first-year veterinary students purchased tablet computers and participated in an investigation of their working methods and perceptions of the tablet computer as an educational tool. Most students found the technology useful. The small size and portability of the tablet allowed easy transport and use in a variety of environments. Most students adapted to electronic notetaking by the second week of classes; negative experiences with the tablet centered on a failure to become comfortable with taking notes and navigating on the computer as opposed to writing and searching on paper. A few performance-related problems, including short battery life, were reported. Tablet software allowed conversion of faculty course notes from a variety of original formats, meaning that instructors could maintain their original methods of note preparation. Adopting a consistent naming convention for files helped students to locate the files on their computers, and smaller file sizes helped with computer performance. Collaboration between students was fostered by tablet use, which offers possibilities for future development of collaborative learning environments. PMID:15834829

Eurell, Jo Ann C; Diamond, Nancy A; Buie, Brandon; Grant, David; Pijanowski, Gerald J

2005-01-01

297

Putting Tablet PCs to the Test  

ERIC Educational Resources Information Center

Like many educators, the author and her colleagues (five faculty members and two IT techs) in the department of Media Communications and Technology at East Stroudsburg University in Pennsylvania were interested to find out the status of tablet PCs in education. Microsoft listed 10 manufacturers of tablet PCs following two forms: the slate and the…

Amirian, Susan

2004-01-01

298

Time to stop counting the tablets?  

Microsoft Academic Search

We attempted to assess compliance using both a pharmacologic indicator (low-dose phenobarbital) and a return tablet count in 225 patients who were taking part in three separate studies. There were 216 patients (96%) who kept a follow-up appointment after 28 days; 161 patients appeared to have good compliance (90% to 109%) by return tablet count. Of these 161 patients, 51

Thomas Pullar; Shubha Kumar; Hilary Tindall; Morgan Feely

1989-01-01

299

Using a Tablet PC for Classroom Instruction  

Microsoft Academic Search

An increasing trend for lecture-based courses is for instructors to convert their lecture notes to slides that can be projected electronically. While there are many advantages to electronic projection, a large drawback is the loss of interactivity and spontaneity that can result. The use of a tablet PC by the instructor promises to overcome this difficulty. The tablet PC, combined

Carol C. W. Hulls

2005-01-01

300

Analysis of fatty acids in ecstasy tablets  

Microsoft Academic Search

Fatty acids are the basis of so-called stearates which are frequently used as lubricants in the production of ecstasy tablets. Being a product added at the initial tablet production step its composition does not change once the compression is performed. The analysis of fatty acids can therefore provide useful information for a drug intelligence purpose. In this context an appropriate

Ines Baer; Pierre Margot

2009-01-01

301

The development and in vitro evaluation of sustained release tablet formulations of benzydamine hydrochloride and its determination.  

PubMed

A novel oral controlled delivery system for benzydamine hydrochloride (BN) was developed and optimized. Hydrophilic matrix tablets of BN were prepared by using hydroxypropylmethylcellulose (HPMC) and chitosan as polymer substance to achieve required sustained release profile. The matrix tablets were prepared both direct compression and wet granulation method. The influence of matrix forming agents and binary mixtures of them on BN release was investigated. The formulated tablets were characterized by hardness, friability, thickness, weight variation and in vitro drug release. The formulated tablets had acceptable physicochemical characters. The quantity of BN present in the tablets and the release medium were estimated by a simple, sensitive, rapid and validated HPLC method. The dissolution results show that increased amount of polymer resulted in reduced and extended drug release. F7 formulation containing 12.5% HPMC and 12.5 % chitosan with direct compression method is the optimum formulation due to its better targeting profile in terms of release. Higuchi (diffusion) and Hixon-Crowell (erosion) kinetic profiles were achieved and this codependent mechanism of drug release was established. This formulation may provide an alternative for oral controlled delivery of BN and be helpful in the future treatment of primary normoreactive types of inflammation. PMID:20426743

Kose-Ozkan, Cansel; Savaser, Ayhan; Tas, Cetin; Ozkan, Yalcin

2010-09-01

302

Inulin-based tablet in capsule device for variable multipulse delivery of aceclofenac: optimization and in vivo roentgenography.  

PubMed

The aim of the study was to develop single-unit tablet in capsule system of aceclofenac for the treatment of late night pain and morning stiffness associated with rheumatoid arthritis. The system was conceptualized as a three-component design (1) a hard gelatin enteric-coated capsule (for carrying two pulses), (2) first-pulse granules (for rapid release in intestine), and (2) second-pulse matrix tablet (for slow release in colon). An appropriate integration of pH-sensitive (Eudragit S100) and bacteria-responsive (inulin) functions, on the basis of 3(2) factorial design, led to formulation of TICS 1-9 that were screened for in vitro release. TICS 2 with biphasic drug release of 98.64% from first-pulse granules in simulated intestinal fluid (12 h) and 97.82% from second-pulse matrix tablet in simulated colonic fluid (24 h) was the optimized formulation that exhibited Fickian diffusion of drug (n=0.363). In vivo fluoroscopy in rats traced the intact tablet to colon in 7.5 h that got eroded at the tenth hour. This demonstrated the colon-specific delivery of the matrix tablet affirming the potential of the system to obviate the need for two-time administration of drug at odd hours. The experimental design was validated by extra design check point, and diffuse reflectance spectroscopy and DSC revealed absence of chemical interaction between the formulation excipients. PMID:23615771

Sharma, Puja; Pathak, Kamla

2013-04-25

303

Fast relief from migraine attacks using fast-disintegrating sublingual zolmitriptan tablets.  

PubMed

Zolmitriptan is a potent molecule for treatment of migraine. Its current oral therapies present drawbacks such as slow onset of action, low bioavailability and large inter-subject variability. Fast disintegrating sublingual zolmitriptan tablet (FDST) using freeze-drying technique has been developed to enhance tablet disintegration and dissolution with the intention of speeding drug absorption and onset of effect, hence mitigating the effects on the gastrointestinal dysmotility that typically accompanies the migraine attack. The FDSTs were prepared using different concentrations of gelatin as binder and mannitol or L-alanine as matrix supporting/disintegration enhancing agents. The effect of formulation variables on the physicochemical and solid-state properties, as well as the dissolution behaviour of the tablets, was studied. The formulated FDSTs disintegrated within 30 s and showed significantly faster dissolution rate of zolmitriptan compared to the zolmitriptan oral tablet. Tablet containing 2% gelatin and mannitol showed acceptable weight variation, drug content and friability values. Furthermore, it had a low in-vitro and in-vivo disintegration time (11 s) and it reached 100% of drug release within 30 s. This sublingual formulation gave faster and higher zolmitriptan plasma concentration in rabbits compared to the oral zolmetriptan market product. Zolmitriptan FDST may therefore constitute an advance in the management of acute migraine attacks. PMID:22023340

Mahmoud, Azza A; Salah, Salwa

2011-10-24

304

Gastric emptying of enteric-coated tablets  

SciTech Connect

To evaluate the gastric emptying time of pharmaceutical dosage forms in a clinical setting, a relatively simple dual-radionuclide technique was developed. Placebo tablets of six different combinations of shape and size were labeled with indium-111 DTPA and enteric coated. Six volunteers participated in a single-blind and crossover study. Tablets were given in the morning of a fasting stomach with 6 oz of water containing /sup 99m/Tc pertechnetate and continuously observed with a gamma camera. A scintigraph was obtained each minute. The results suggested that the size, shape, or volume of the tablet used in this study had no significant effect in the rate of gastric emptying. The tablets emptied erratically and unpredictably, depending upon their time of arrival in the stomach in relation to the occurrence of interdigestive myoelectric contractions. The method described is a relatively simple and accurate technique to allow one to follow the gastric emptying of tablets.

Park, H.M.; Chernish, S.M.; Rosenek, B.D.; Brunelle, R.L.; Hargrove, B.; Wellman, H.N.

1984-03-01

305

Controlled release formulation of tramadol hydrochloride using hydrophilic and hydrophobic matrix system  

Microsoft Academic Search

The effect of concentration of hydrophilic (hydroxypropyl methylcellulose [HPMC]) and hydrophobic polymers (hydrogenated castor\\u000a oil [HCO], ethylcellulose) on the release rate of tramadol was studied. Hydrophilic matrix tablets were prepared by wet granulation\\u000a technique, while hydrophobic (wax) matrix tablets were prepared by melt granulation technique and in vitro dissolution studies\\u000a were performed using United States Pharmacopeia (USP) apparatus type II.

Sandip B. Tiwari; T. Krishna Murthy; M. Raveendra Pai; Pavak R. Mehta; Pasula B. Chowdary

2003-01-01

306

Modulation of Tramadol Release from a Hydrophobic Matrix: Implications of Formulations and Processing Variables  

Microsoft Academic Search

In the present investigation, hydrogenated cottonseed oil (HCSO) was evaluated as a sustained release matrix for a freely\\u000a soluble drug, tramadol. Hydrophobic matrix tablets of tramadol, was evaluated by compression of physical mixture of drug and\\u000a wax, dispersion of drug in HCSO by hot fusion or solubilisation techniques. The method of preparation of tablet had a significant\\u000a effect on drug

B. S. Sudha; B. K. Sridhar; A. Srinatha

2010-01-01

307

Resistant starch as a carrier for oral colon-targeting drug matrix system  

Microsoft Academic Search

In this study, a novel tablet of protein drug matrix for colon targeting was developed using resistant starch as a carrier\\u000a prepared by pre-gelatinization and cross-linking of starch. The effects of pre-gelatinization and cross-linking on the swelling\\u000a and enzymatic degradation of maize starch as well as the release rate of drug from the matrix tablets were examined. Cross-linked\\u000a pre-gelatinized maize

Ling Chen; Xiaoxi Li; Yansheng Pang; Lin Li; Ximei Zhang; Long Yu

2007-01-01

308

Improvements in floating point addition/subtraction operations  

DOEpatents

Apparatus is described for decreasing the latency time associated with floating point addition and subtraction in a computer, using a novel bifurcated, pre-normalization/post-normalization approach that distinguishes between differences of floating point exponents.

Farmwald, P.M.

1984-02-24

309

14 CFR 29.757 - Hull and auxiliary float strength.  

Code of Federal Regulations, 2013 CFR

...hull, and auxiliary floats if used, must withstand the water loads prescribed by § 29.519 with a rational and conservative distribution of local and distributed water pressures over the hull and float bottom. [Amdt....

2013-01-01

310

Floating Breakwaters: State-of-the-Art Literature Review.  

National Technical Information Service (NTIS)

A multitude of conceptual models of floating breakwaters have been proposed without extensive or complete evaluation of most of these concepts. The technical literature regarding floating breakwater applicability and design procedures is fragmentary and s...

L. Z. Hales

1981-01-01

311

Exploiting Idle Floating-Point Resources for Integer Execution  

Microsoft Academic Search

In conventional superscalar microarchitectures with partitioned integer and floating-point resources, all floating-point resources are idle during execution of integer programs. Palacharla and Smith [26] addressed this drawback and proposed that the floating-point subsystem be augmented to support integer operations. The hardware changes required are expected to be fairly minimal.To exploit these idle floating resources, the compiler must identify integer code

S. Subramanya Sastry; Subbarao Palacharla; James E. Smith

1998-01-01

312

Teaching dynamics using interactive tablet PC instruction software  

Microsoft Academic Search

Is there an advantage of using interactive tablet PC software as opposed to more traditional teaching methods? This work is an innovative use of tablet PC technology to teach an introductory dynamics course. Each student in the classroom used a tablet PC as did the instructor. In addition to using the tablet PCs, each lecture was recorded using screen capture

David Fisher; Phillip Cornwell; Julia Williams

2007-01-01

313

Controlled release formulation of tramadol hydrochloride using hydrophilic and hydrophobic matrix system.  

PubMed

The effect of concentration of hydrophilic (hydroxypropyl methylcellulose [HPMC]) and hydrophobic polymers (hydrogenated castor oil [HCO], ethylcellulose) on the release rate of tramadol was studied. Hydrophilic matrix tablets were prepared by wet granulation technique, while hydrophobic (wax) matrix tablets were prepared by melt granulation technique and in vitro dissolution studies were performed using United States Pharmacopeia (USP) apparatus type II. Hydrophobic matrix tablets resulted in sustained in vitro drug release (>20 hours) as compared with hydrophilic matrix tablets (<14 hours). The presence of ethylcellulose in either of the matrix systems prolonged the release rate of the drug. Tablets prepared by combination of hydrophilic and hydrophobic polymers failed to prolong the drug release beyond 12 hours. The effect of ethylcellulose coating (Surelease) and the presence of lactose and HPMC in the coating composition on the drug release was also investigated. Hydrophobic matrix tablets prepared using HCO were found to be best suited for modulating the delivery of the highly water-soluble drug, tramadol hydrochloride. PMID:14621963

Tiwari, Sandip B; Murthy, T Krishna; Pai, M Raveendra; Mehta, Pavak R; Chowdary, Pasula B

2003-01-01

314

Design and optimization of sustained-release divalproex sodium tablets with response surface methodology.  

PubMed

Response surface methodology is defined as a collection of mathematical and statistical methods that are used to develop, improve, or optimize a product or process. In the present study, a statistical design (Mixture Design) was employed for formulation and optimization of a sustained-release hydrophilic divalproex sodium matrix tablet. Different excipients were used to improve the drug's poor flowability. The hardness of the prepared tablets and also their release pattern were tested. The formulation design was carried out employing mixture design using four excipients in three levels. The Carr's index of formulations and tensile strength were determined and analyzed using Minitab software. The suitable formulations regarding flowability and tablet tensile strength were selected by this software for subsequent drug release studies. The dissolution tests were carried out in acidic and basic phases which were previously proved to be biomimetic. Samples were analyzed using HPLC, and release data were compared to Depakine® (sustained-release divalproex from Sanofi). Release kinetics was also determined for selected formulations. Selected formulations were subjected to dissolution test and showed similar dissolution profiles with Depakine® based on difference and similarity factor calculations. The software selected an optimized formulation which had a slightly different release pattern in vitro compared to innovator but of nearly zero-order kinetics. It can be concluded that application of Mixture Design is a shortcut method to design suitable formulations of sustained-release divalproex sodium containing hydrophilic matrix tablets by direct compression method. PMID:23269542

Monajjemzadeh, Farnaz; Hamishehkar, Hamed; Zakeri-Milani, Parvin; Farjami, Afsaneh; Valizadeh, Hadi

2012-12-27

315

14 CFR 25.535 - Auxiliary float loads.  

Code of Federal Regulations, 2010 CFR

...load must be applied in the plane of symmetry of the float at a point three-fourths...the center of gravity and the plane of symmetry of the float to the radius of gyration...load must be applied in the plane of symmetry of the float at a point...

2009-01-01

316

14 CFR 23.535 - Auxiliary float loads.  

Code of Federal Regulations, 2010 CFR

...load must be applied in the plane of symmetry of the float at a point three-fourths...the center of gravity and the plane of symmetry of the float to the radius of gyration...load must be applied in the plane of symmetry of the float at a point...

2010-01-01

317

14 CFR 25.535 - Auxiliary float loads.  

Code of Federal Regulations, 2010 CFR

...load must be applied in the plane of symmetry of the float at a point three-fourths...the center of gravity and the plane of symmetry of the float to the radius of gyration...load must be applied in the plane of symmetry of the float at a point...

2010-01-01

318

14 CFR 23.535 - Auxiliary float loads.  

Code of Federal Regulations, 2010 CFR

...load must be applied in the plane of symmetry of the float at a point three-fourths...the center of gravity and the plane of symmetry of the float to the radius of gyration...load must be applied in the plane of symmetry of the float at a point...

2009-01-01

319

Repair of floating offshore units using bonded fibre composite materials  

Microsoft Academic Search

On ships, tankers and similar vessels structural defects such as cracks and corrosion damage are typically repaired by welding. However, welding is unwanted hotwork on floating offshore units (FOUs) such as floating, production, storage and offloading (FPSO) and floating, storage and offloading (FSO) vessels because it requires shutdown of parts of the vessel thus resulting in expensive production delays. Bonded

D. McGeorge; A. T. Echtermeyer; K. H. Leong; B. Melve; M. Robinson; K. P. Fischer

2009-01-01

320

Improving the performance of floating solar pool covers  

SciTech Connect

Experimental and analytical analyses are presented for the evaluation of heat transfer through floating solar swimming pool covers. Two improved floating solar swimming pool cover designs are proposed and investigated in this paper. The results conclusively show that both new cover designs should have significantly better performance than conventional floating solar swimming pool covers.

Cole, M.A.; Lowrey, P. (San Diego State Univ., CA (United States). Dept. of Mechanical Engineering)

1992-11-01

321

Low-voltage floating-gate current mirrors  

Microsoft Academic Search

In this paper we propose a novel design of low-voltage current mirrors using floating gates. Floating gate UV-light programmable MOS transistors (FGUVMOS) are used to design current mirrors in low-voltage\\/low-power analog applications. The capacitive divider inputs to the floating gates can he utilized to reduce current mismatch due to Early effect

Yngvar Berg; Tor Sverre Lande; S. Naess

1997-01-01

322

Insertion loss prediction of floating floors used in ship cabins  

Microsoft Academic Search

In this paper, vibration reduction in ship cabins by using floating floor is studied. Two theoretical models are developed and predicted insertion losses of floating floors are compared to experimental results, where measurements are done in the mock-up built for simulating typical ship cabins. The floating floor consists of upper board and mineral wool, which is in turn laid on

Sun-Il Cha; Ho-Hwan Chun

2008-01-01

323

External Resource: Why Do Astronauts Float in Space?  

NSDL National Science Digital Library

This NASA video segment explains why objects seem to float in space. Viewers learn that an apple that floats in space is really in a state of freefall. Since the whole space shuttle is also in freefall, the apple seems to float. An animation of a person i

1900-01-01

324

[Tramadol/acetaminophen combination tablets].  

PubMed

Tramadol/acetaminophen fixed-dose combination tablets (Tramse) combine tramadol, a centrally acting week opioid analgesic, with low-dose acetaminophen. The action of tramadol may be described as a weak agonist at the mu-opioid receptor, inhibition of serotonin reuptake, and inhibition of noradrenaline reuptake. The second component in these tablets, acetaminophen mainly appears to act through central mechanism. Chronic pain may be broadly classified into nociceptive, neuropathic and mixed. Tramset may exert additive or synergic benefits in treating the multiple mechanism of pain. Clinical studies have revealed its efficacy and safety for a variety of pain condition such as chronic low back pain, rheumatoid arthritis, fibromyalgia and painful diabetic peripheral neuropathy. It is expected that Tramset is going to induce pain relief and to improve disturbance of daily life in patients with intractable chronic pain. However overuse of Tramset may induce severe adverse effects such as addiction, abuse and hepatotoxicity. Therefore clinician should continuously assess pain intensity, activity of daily life, mode of its consumption, and adverse effects after prescription. PMID:23905401

Yokotsuka, Shoko; Kato, Jitsu

2013-07-01

325

A comparative study of the dissolution characteristics of capsule and tablet dosage forms of melt granulations of paracetamol--diluent effects.  

PubMed

The dissolution characteristics of melt granulations of paracetamol in capsule and tablet dosage form were compared to determine whether the dissolution characteristics of the granules can be actualized by formulating them as rapidly disintegrating tablets. The term melt granulation refers here to the wax-matrix granules that were formed by triturating the drug powder (paracetamol) with a melted carnauba wax. The matrix granules were admixed with diluents (lactose, alpha-cellulose or microcrystalline cellulose) also in granular form to prevent size separation during encapsulation or tableting. The granules were filled into hard gelatin capsules (mean content weight, 500 +/- 6.2 mg) or tableted (mean weight 500 +/- 5.1 mg, and tensile strength 1.36 +/- 0.2 to 1.7 +/- 0.3 MN/m2). The capsules and tablets were subjected to disintegration and in vitro dissolution tests. The dissolution data were analyzed on the basis of zero, first order rate kinetics and Higuchi square root of time relationship. The results showed that the dissolution profiles were generally consistent with a first order rate kinetics (r = 0.95). The first order dissolution rate constants of capsules and tablets of the matrix granules only (without diluents) were 0.31 +/- 0.02 min(-1) and 0.20 +/- 0.03 min(-1), respectively, indicating faster dissolution from the capsules. Therefore, the dissolution characteristics of the matrix particles were not intact after tableting. Addition of diluents to the capsule formulations had no effect on dissolution rates, whereas in the tablets, dissolution rates increased. For instance, inclusion of a diluent up to 50% w/w in the tablets increased the dissolution rate constants to 0.34 +/- 0.04 min(-1) (lactose), 0.42 +/- 0.02 min(-1) (alpha-cellulose), and 0.46 +/- 0.03 min(-1) (microcrystalline cellulose). Thus, alpha-cellulose and microcrystalline cellulose produced greater enhancer effect on the tablet dissolution rates compared to lactose. Both the capsules and the tablets disintegrated rapidly within 2 to 3 minutes. The dissolution enhancer effect of the diluents in the tablets only, relates to the aqueous swelling of the disintegrated particles. PMID:17665854

Uhumwangho, Michael U; Okor, Roland S

326

Floating reference frames for flexible spacecraft  

Microsoft Academic Search

Floating reference frames which move with the flexible body under dynamic analysis offer the advantages of a linear vibration analysis in the presence of large system rotations. When the deformations of an elastic continuum are expanded in terms of the free-free modes on an unconstrained system, the rigid body modes are found to be fixed in a reference frame called

J. R. Canavin; P. W. Likins

1977-01-01

327

24-Bit Floating-Point DSP.  

National Technical Information Service (NTIS)

The article reports on a new high-speed 24-bit floating point DSP (digital-signal processor) and its development tools. The DSP features a short 75ns instruction cycle and low 750m W power dissipation. Other features include a large memory space, internal...

T. Fujiyama Y. Shimazu T. Tokuda S. Tsujimichi

1989-01-01

328

Creep theory for a floating ice sheet  

Microsoft Academic Search

The problem investigated in this thesis is the prediction of the deflection and stresses in a floating ice sheet under loads which act over a long period of time. This problem is currently important for oil exploration offshore in the Arctic. A review of analytical methods for predicting the bearing capacity of an ice sheet is given. The problem is

D. E. Nevel

1976-01-01

329

The salinity of a floating forest  

Microsoft Academic Search

Joachim Scheven has proposed an interesting theory that the Euro-American coals have not grown in place but formed when a huge forest of floating aquatic plants was swept on shore and buried in the catastrophe of Noah's Flood. Scheven's video 1 and published material 2-5 indicates that the Lepidendron and Sigillaria species of the Carbon- iferous coals were aquatic plants.

Wesley Bruce

2002-01-01

330

The DSP decision: fixed point or floating?  

Microsoft Academic Search

The rapid expansion of the market in applications of the digital signal processor has unloosed a flood of diverse chips. Design engineers are being inundated with altogether too much information to absorb. Still, the problem does become more manageable once it is decided whether a fixed-point or a floating point math unit should be basic to the digital signal processor

C. Inacio; D. Ombres

1996-01-01

331

40MM Target Marker (Floating), TMF-1.  

National Technical Information Service (NTIS)

This is the Final Report of the 40MM Target Marker (Floating), TMF-1, program. The purpose of this program was to prove the feasibility of and to design, develop and test a floatable target marker in a 40mm configuration that can be fired from either the ...

J. A. D'Andrea

1971-01-01

332

On building mobility models for floating objects  

Microsoft Academic Search

We present a general framework for building mobility models for floating objects. Such models are useful for studying the behavior of wireless sensors that are deployed to drift along rivers, lakes, oceans, or debris flows. These sensors may be used to track toxic wastes in the water, to study hydrology, or to warn natural hazards. While existing mobility models concentrate

Huang-chen Lee; Chun-yu Lin; Shang-wen Hsu; Chung-ta King

2009-01-01

333

Heat recovery and floating condensing in supermarkets  

Microsoft Academic Search

Supermarkets are great energy users in many countries. The potential for increased energy efficiency is large. One option is to utilize heat recovery (or heat reclaim) from condensers to heat the premises. Obviously this option is only interesting in relatively cold areas such as northern Europe, Canada, etc. An alternative to heat recovery is floating condensing pressure, which improves the

Jaime Arias; Per Lundqvist

2006-01-01

334

An introduction to deepwater floating drilling operations  

Microsoft Academic Search

Deepwater drilling is discussed from selecting vessels and hardware to safety precautions and personnel. The contents include drilling from a floating vessel; planning and organizing deepwater drilling operations; drill vessels; drilling systems; mooring systems; auxiliary vessels; well-control and communications; subsea guide bases; subsea blowout preventers; marine-riser systems; drill-stem testing; safety and efficiency; and future developments. (JMT)

1972-01-01

335

Floating drilling rig apparatus and method  

Microsoft Academic Search

This patent describes an apparatus adapted for use with a floating drilling rig having a marine riser including a telescopic joint. The telescopic joint has a guide\\/index key. The joint has an upwardly facing unterminated connector for a riser choke\\/kill line. The apparatus comprises: a terminal end assembly, including: a frame, yoke means slidably disposed on the frame for securing

1987-01-01

336

[The theory of floating eye model].  

PubMed

Analytical construction of the eye floating was carried out. Buoyancy equations were deduced including the equation for dynamic equilibrium at various eye (head) orientations in space. Design formulae were derived for evaluating buoyancy force on the eye, negative pressure, stability and compensational (heeling) forces of the eye muscles. PMID:2346754

Galoian, V R

337

PLM floating-point interface program  

Microsoft Academic Search

A major failing of Intel's PLM language is its inability to handle scientific notation (floating-point) calculations. An interface program that allows PLM to perform such calculations is described. A comparison of this modified PLM with an assembly language program has shown PLM's effectiveness in reducing the cost of a project. (auth)

C. Paoni; M. Maples

1976-01-01

338

Daphnia (zoomed on floating blood cells)  

NSDL National Science Digital Library

These pin drops are the clearly defined blood cells of the Daphnia. We are only able to see the cells with use of a microscope. Keep in mind that the cells are not confined in any blood vessel (called an open circulatory system) and freely float throughout the body.

Katie Hale (CSUF;Biological Sciences)

2007-07-18

339

The Sea Peoples, from cuneiform tablets to carbon dating.  

PubMed

The 13(th) century BC witnessed the zenith of the Aegean and Eastern Mediterranean civilizations which declined at the end of the Bronze Age, ?3200 years ago. Weakening of this ancient flourishing Mediterranean world shifted the political and economic centres of gravity away from the Levant towards Classical Greece and Rome, and led, in the long term, to the emergence of the modern western civilizations. Textual evidence from cuneiform tablets and Egyptian reliefs from the New Kingdom relate that seafaring tribes, the Sea Peoples, were the final catalyst that put the fall of cities and states in motion. However, the lack of a stratified radiocarbon-based archaeology for the Sea People event has led to a floating historical chronology derived from a variety of sources spanning dispersed areas. Here, we report a stratified radiocarbon-based archaeology with anchor points in ancient epigraphic-literary sources, Hittite-Levantine-Egyptian kings and astronomical observations to precisely date the Sea People event. By confronting historical and science-based archaeology, we establish an absolute age range of 1192-1190 BC for terminal destructions and cultural collapse in the northern Levant. This radiocarbon-based archaeology has far-reaching implications for the wider Mediterranean, where an elaborate network of international relations and commercial activities are intertwined with the history of civilizations. PMID:21687714

Kaniewski, David; Van Campo, Elise; Van Lerberghe, Karel; Boiy, Tom; Vansteenhuyse, Klaas; Jans, Greta; Nys, Karin; Weiss, Harvey; Morhange, Christophe; Otto, Thierry; Bretschneider, Joachim

2011-06-08

340

Rapid drug-screening of clandestine tablets by MALDI-TOF mass spectrometry  

Microsoft Academic Search

A novel method for the rapid screening of clandestine tablets for drugs by MALDI-TOF mass spectrometry is described. In this method, cetrimonium bromide (CTAB), a surfactant, is added to the conventional ?-cyano-4-hydroxycinnamic acid (CHCA) matrix solution used in preparing the MALDI samples. This procedure allows very clean mass spectra to be collected for amphetamine, methamphetamine, 3,4-methylenedioxyamphetamine (MDA), 3,4-methylenedioxymethamphetamine (MDMA), caffeine,

An-Kai Su; Ju-Tsung Liu; Cheng-Huang Lin

2005-01-01

341

Formulation, Bioavailability, and Pharmacokinetics of Sustained-Release Potassium Chloride Tablets  

Microsoft Academic Search

The release of potassium chloride incorporated into hydrogenated vegetable oil and hydroxypropyl methylcellulose matrix tablets was studied in vitro. The formulations containing 20% hydrogenated vegetable oil and hydroxypropyl methylcellulose showed a sustained-release profile comparable to that of a standard commercially available sustained-release preparation, containing 8 mEq potassium chloride embedded in a wax material. The formulated and standard sustained-release potassium chloride

Sevda ?enel; Yilmaz Çapan; Turgay Dalkara; Neriman ?nanç; A. Atillâ Hincal

1991-01-01

342

21 CFR 520.804 - Enalapril tablets.  

Code of Federal Regulations, 2013 CFR

...HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.804 Enalapril tablets...maleate is administered as conjunctive therapy with furosemide and digoxin in...

2013-04-01

343

21 CFR 520.1380 - Methocarbamol tablets.  

Code of Federal Regulations, 2013 CFR

...HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.1380 Methocarbamol tablets...administered to dogs and cats as an adjunct to therapy for acute inflammatory and...

2013-04-01

344

21 CFR 520.531 - Cythioate tablets.  

Code of Federal Regulations, 2013 CFR

...tablet. (c) Special considerations. Cythioate is a cholinesterase inhibitor. Do not use this product in animals simultaneously...a few days before or after treatment with or exposure to cholinesterase-inhibiting drugs, insecticides, pesticides, or...

2013-04-01

345

21 CFR 520.812 - Enrofloxacin tablets.  

Code of Federal Regulations, 2013 CFR

...CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.812 Enrofloxacin tablets... Dogs and cats for management of diseases associated with bacteria susceptible to enrofloxacin. (3) Limitations...

2013-04-01

346

Fentanyl Buccal Tablets (marketed as Fentora) Information  

Center for Drug Evaluation (CDER)

... Fentora (fentanyl buccal tablets) is a an opioid pain medication used for the treatment of breakthrough pain in cancer patients receiving opioid ... More results from www.fda.gov/drugs/drugsafety/postmarketdrugsafetyinformationforpatientsandproviders

347

Chocolate Tablet Aspects of Cytherean Meshkenet Tessera.  

National Technical Information Service (NTIS)

Meshkenet Tessera structures were mapped from Magellan data and several resemblances to chocolate tablet boudinage were found. The complex fault sets display polyphase tectonic sequences of a few main deformation phases. Shear and tension have contributed...

J. Raitala

1993-01-01

348

Workshop - tablet PCs in engineering education & research  

Microsoft Academic Search

Tablet PCs are one of the newest innovations in computing and communications tools, offering an opportunity to positively impact the way in which students and faculty use technology to support teaching and learning. In this three hour workshop faculty will receive a hands-on introduction to the use of several tablet-based software tools including OneNote, Classroom Presenter, WriteOn, ChemPad, VectorPad and

J. G. Tront; J. C. Prey

2007-01-01

349

Twin countershaft transmission with floating main shaft  

SciTech Connect

A multi-speed transmission is described comprising, in combination: a housing; a pair of spaced parallel main countershafts mounted for rotation within the housing and being spatially fixed therein; means for supplying input power to both of the main countershafts; a plurality of pairs of driving gears mounted on the main countershafts, each gear of a pair being substantially identical and positioned on a respective one of the main countershafts at axially aligned locations along a floating mainshaft; the floating main shaft having input and output ends, the main shaft being located within the housing between and parallel to the main countershafts and having its output end extending beyond the main countershafts with no internal or external bearings or other support at or adjacent its ends under torque delivering conditions.

Loeffler, J.M.

1989-02-28

350

OCD metrology by floating n/k  

NASA Astrophysics Data System (ADS)

In this paper, one of the major contributions to the OCD metrology error, resulting from within-wafer variation of the refractive index/extinction coefficient (n/k) of the substrate, is identified and quantified. To meet the required metrology accuracy for the 65-nm node and beyond, it is suggested that n/k should be floating when performing the regression for OCD modeling. A feasible way of performing such regression is proposed and verified. As shown in the presented example, the measured CDU (3?) with n/k fixed and n/k floating is 1.94 nm and 1.42 nm, respectively. That is, the metrology error of CDU committed by assuming n/k fixed is more than 35% of the total CDU.

Yu, Shinn-Sheng; Huang, Jacky; Ke, Chih-Ming; Gau, Tsai-Sheng; Lin, Burn J.; Yen, Anthony; Lane, Lawrence; Vuong, Vi; Chen, Yan

2007-03-01

351

Floating behavior of hydrophobic glass spheres.  

PubMed

When a hydrophobic solid sphere is floating on water or salt solutions with different concentrations, it is at equilibrium under the impact of gravity, buoyancy force, and curvature force, the component of surface tension in the vertical direction. We have changed the diameters of the spheres and the concentrations of the two selected salts, NaCl and NaNO(3), to study the floating behaviors of these spheres and the contributions of surface tension and buoyancy force to their floatation. Generally speaking, the surface tension plays a more important role than the buoyancy force when the gravity is small, but the buoyancy force plays an identical or a more important role when the spheres are big enough. The wettability of the spheres significantly influences the height below the contact perimeter especially in salt solutions. The theoretical calculation meniscus slope angles at the sphere three-phase contact line are in agreement with experimental results. PMID:19464018

Liu, Xinjie; Wang, Xiaolong; Liang, Yongmin; Zhou, Feng

2009-04-16

352

Development and evaluation of controlled-release diclofenac microspheres and tabletted microspheres.  

PubMed

Diclofenac wax microspheres were prepared using the congealable dispersephase encapsulation method. Emulsifiers, glyceryl monostearate (GMS) and stearic acid, were added to improve the efficiency of emulsification. Microspheres containing either of the emulsifiers or both showed a high drug content (80-90%) and the particle size distribution was log-normal compared with microspheres without the emulsifiers. Increase in GMS concentration decreased the drug release and, in contrast, stearic acid appeared to channel the drug from the wax matrix. The addition of both emulsifiers at different concentrations modified drug release. Increase in dispersant (PVP) concentration, and decrease in microsphere size accelerated the rate of drug release. Higuchi/Baker Londsdale spherical matrix dissolution kinetics was followed. Disintegrating tableted microspheres were prepared with Avicel and Explotab. With the increase in compression pressure the crushing force and disintegrating time increased, but the thickness decreased, and the dissolution profile did not appear to be affected. Slightly faster release was noticed with tableted microspheres compared with that of uncompressed microspheres. Tablets containing 40 and 60% microsphere loadings had disintegration times of 5.12 +/- 0.63 and 57.73 +/- 3.53 min, respectively. In contrast, tablet formulation containing 80% microsphere load had a significant increase in disintegration time (130.83 +/- 4.26 min). The dissolution from this formulation also showed a lag time of 30 min in contrast with the other two formulations, which showed no lag time. Increased microsphere size from 215 to 630 microns had no effect on tableting properties (such as hardness and thickness); and only very little effect on dissolution. The microspheres appeared deformed but intact irrespective of compression pressures on scanning electron micrographs. PMID:7931945

Vilivalam, V D; Adeyeye, C M

353

A comparative study of dissolution characteristics of polymeric and wax granulations of theophylline and their tablets.  

PubMed

Matrix (non disintegrating) granules of theophylline have been formed and their dissolution characteristics investigated for sustained release application. The polymeric granulations were formed by massing the drug powder with a concentrated (40% w/w) ethanolic solution of an acrylatemethacrylate copolymer (ERS100R). Wax granulations were also formed by massing the drug powder with previously melted carnuba wax followed by screening and drying. The content of polymer or wax in the resulting granules was 16.7% w/w. Conventional granules of theophylline were formed by massing the drug powder with starch mucilage (20% w/v). Resulting granules were subjected to particle size analysis and in vitro dissolution tests. The granules were further compressed to tablets (weight 500+/-4.2 mg each) at a constant load (30 arbitrary units on the load scale). The tablets were subjected to hardness, disintegration and dissolution tests. The dissolution kinetics were also considered. The mean granule size was 646.5+/-4.3 microm (conventional), 821.4+/-4.8 microm (polymeric granulations) and 892.7+/-5.4 microm (wax granulations), the matrix granules were therefore larger than the conventional granules. Dissolution of the granules generally followed a first order rate kinetic. The rate constant (k(1)) for the conventional, polymeric and wax granulations were (h(-1)): 0.53, 0.31 and 0.27 respectively. Thus, the wax granulations appeared to be more effective than the polymeric granulations in retarding drug release from the granules but the difference was not statistically significant (p>0.05). The tensile strength of tablets derived from the conventional, polymeric and wax granulations were (MNm(-2)) 0.85, 1.68 and 1.96 respectively, indicating that the matrix granules (compared with the conventional granules) produced harder tablets at the same compression load. The corresponding first order dissolution rate constants were (h(-1)): 0.46, 0.28 and 0.21. Thus, tableting of the matrix granules produced a slight but significant decrease in dissolution rates, attributable to the disintegration of the tablets to more compact particles. PMID:18614417

Uhumwangho, Michael U; Okor, Roland S

2008-07-01

354

Modulation of drug (metoprolol succinate) release by inclusion of hydrophobic polymer in hydrophilic matrix.  

PubMed

The objective of this study was to develop sustained release (SR) matrix tablets of metoprolol succinate (MS), by using different polymer combinations and fillers, to optimize by response surface methodology and to evaluate biopharmaceutical parameters of the optimized product. Matrix tablets of various combinations were prepared with cellulose-based polymers: hydroxy propyl methyl cellulose (HPMC) and ethyl cellulose (EC); and lactose and dibasic calcium phosphate dihydrate (DCP) as fillers. Study of pre-compression and post-compression parameters facilitated the screening of a formulation with best characteristics that underwent here optimization study by response surface methodology (Central Composite Design). The optimized tablet was subjected to further study like scanning electron microscopy, swelling study and in vivo study in rabbit model. Both in vitro and in vivo study revealed that combining of HPMC K100M (21.95%) with EC (8.85%), and use of DCP as filler sustained the action up to 12 h. The in vivo study of new SR tablets showed significant improvement in the oral bioavailability of MS in rabbits after a single oral dose of 25 mg. The delayed T(max) and lower C(max) indicated a slow and SR of MS from the optimized matrix tablets in comparison with the immediate release dosage form. The developed SR (MS) tablet of improved efficacy can perform therapeutically better than conventional tablet. PMID:21401340

Siddique, Sabahuddin; Bose, Anirbandeep; Khanam, Jasmina

2011-04-20

355

Floating Ice: Grades K-1: Electronic Book  

NSDL National Science Digital Library

This informational text discusses the unique property of ice - that it floats in liquid water. Students focus on real-world examples and how ice is necessary for life in the polar regions. The text is written at a kindergarten through grade one reading level. This is an onscreen version that contains recorded narration allowing students to listen to the text as they read along. Highlighted vocabulary words have individually recorded definitions heard by clicking on the links.

Fries-Gaither, Jessica

356

Finite Element Analysis of a Floating Microstimulator  

PubMed Central

Analytical solutions for voltage fields in a volume conductor are available only for ideal electrodes with radially symmetric contacts and infinitely extending substrates. Practical electrodes for neural stimulation may have asymmetric contacts and finite substrate dimensions and hence deviate from the ideal geometries. For instance, it needs to be determined if the analytical solutions are adequate for simulations of narrow shank electrodes where the substrate width is comparable to the size of the contacts. As an extension to this problem, a “floating” stimulator can be envisioned where the substrate would be finite in all directions. The question then becomes how small this floating stimulator can be made before its stimulation strength is compromised by the decrease in the medium impedance between the contacts as the contacts are approaching each other. We used finite element modeling to solve the voltage and current profiles generated by these radially asymmetric electrode geometries in a volume conductor. The simulation results suggest that both the substrate size and the bipolar contact separation influence the voltage field when these parameters are as small as a few times the contact size. Both of these effects are larger for increasing elevations from the contact surface, and even stronger for floating electrodes (finite substrate in all directions) than the shank-type electrodes. Location of the contacts on the floating electrode also plays a role in determining the voltage field. The voltage field for any device size and current, and any specific resistance of the volume conductor can be predicted from these results so long as the aspect ratios are preserved.

Sahin, Mesut; Ur-Rahman, Syed S.

2011-01-01

357

Floating-Gate MOS Synapse Transistors  

Microsoft Academic Search

Our goal is to develop silicon learning systems. One impediment to achieving this goal has been the lack of a simple circuit\\u000a element combining nonvolatile analog memory storage with locally computed memory updates. Existing circuits [63, 132] typically\\u000a are large and complex; the nonvolatile floating-gate devices, such as EEPROM transistors, typically are optimized for binary-valued\\u000a storage [17], and do not

Chris Diorio; Paul Hasler; Bradley A. Minch; Carver Mead

358

Development and in vitro evaluation of buccoadhesive carvedilol tablets.  

PubMed

Buccoadhesive tablets of carvedilol were prepared using HPMC K4M, HPMC K15M and Carbopol 934 as mucoadhesive polymers. Fifteen formulations were developed with varying concentrations of polymers. Formulations of the BC or BD series were composed of HPMC K4M or HPMC K15M in ratios of 1:1 to 1:5 whereas in the BE series Carbopol 934 was used (1:0.25 to 1:1.50). The formulations were tested for in vitro drug release, in vitro bioadhesion, moisture absorption and in vitro drug permeation through porcine buccal mucosa. Formulation BC3 showed maximum release of the drug (88.7 +/- 0.4%) with the Higuchi model release profile and permeated 21.5 +/- 2.9% of the drug (flux 8.35 +/- 0.291 microg h(-1)cm(-2)) permeation coefficient 1.34 +/- 0.05 cm h(-1)) through porcine buccal membrane. BC3 formulation showed 1.62 +/- 0.15 N of peak detachment force and 0.24 +/- 0.11 mJ of work of adhesion. FTIR results showed no evidence of interaction between the drug and polymers. XRD study revealed that the drug is in crystalline form in the polymer matrix. The results indicate that suitable bioadhesive buccal tablets with desired permeability could be prepared. PMID:17507315

Yamsani, Vamshi Vishnu; Gannu, Ramesh; Kolli, Chandrasekhar; Rao, M E Bhanoji; Yamsani, Madhusudan Rao

2007-06-01

359

Float-thermostatic trap prevents steam loss  

SciTech Connect

This article focuses on the energy efficiency of a float-thermostatic steam trap which prevents steam loss. This float-thermostatic steam trap was awarded Top Honors in the steam traps category in the 1982 Chemical Processing Vaaler competition because of the trap's lack of steam loss, its in-line installation, and its ability to be maintained in-line. The energy efficient trap features a float operated mechanism that modulates with the load and always maintains a condensate level above the main valve to prevent steam leakage, and a balance pressure thermostatic air vent that immediately and continuously discharges all non-condensibles. Other features include resistance to dirt plugging and freeze damage for long reliable service; fail-safe operation; all-stainless steel corrosion resistant internals; light weight stainless steel case with forged cover; and convenient top and bottom inlet with 1/2'' threaded or socket weld connections. The traps will save from 2 to 5 lb/hr of steam, compared to conventional traps. Annual savings are estimated at between $175 and $438 per trap, with steam costing $10 per thousand pounds.

Not Available

1982-11-01

360

Pigmented Free-Floating Posterior Vitreous Cyst  

PubMed Central

Vitreous cysts are very rare ocular malformations. In this observational case study, we report on an unusual case of a pigmented free-floating vitreous cyst and discuss its differential diagnosis. A 14-year-old male was referred to ophthalmology for a pigmented lesion in his left eye. He complained of an intermittent floater in the left eye. Visual acuity was 20/20 in the right eye and 20/40 in the left eye. Fundus examination was unremarkable bilaterally, except for a piece of brownish oval material floating in the vitreous in the left eye. He had received a knock on the left side of his head a few days before the visual discomfort of the left eye. Real-time ultrasound of the left eye detected a piece of hyperechogenic spherical material with no internal reflectivity, floating in the middle of the vitreous. The first use of color Doppler ultrasound in this context indicated no arterial flow, ruling out the presence of a persistent hyaloid artery. Intraocular cysts are rare ocular disorders, which have been divided into clear and pigmented cysts, and into those that occupy the anterior chamber, the retrolental space, and the vitreous cavity. This last is extremely rare. We describe such a case.

Brue, Claudia; Mariotti, Cesare; De Franco, Edoardo; De Franco, Nicola; Giovannini, Alfonso

2012-01-01

361

Floating boom performance under waves and currents.  

PubMed

Floating booms constitute a fundamental tool for the protection of marine and coastal ecosystems against accidental oil spills. Their containment performances in exposed areas are often impaired by the action of waves, currents and winds in a manner which is dependent on the boom's response as a floating body, and which is not fully understood at present. In this work the relationship between the design parameters of a floating boom section and its efficiency against the mode of failure by drainage under a variety of wave and current combinations is investigated by means of physical modelling. Seven boom models with different geometries and buoyancy-weight ratios are tested with an experimental setup that allows them to have and rotate freely. The model displacements under waves (both regular and irregular) and currents, as well as those of the free surface adjacent to the model, are measured with a Computer Vision system developed ad hoc. Two efficiency parameters are defined-the significant and minimum effective boom drafts-and applied to the results of an experimental campaign involving 315 laboratory tests. Thus, the manner in which the design parameters influence the boom's efficiency under different wave and current conditions is established. PMID:19800166

Castro, A; Iglesias, G; Carballo, R; Fraguela, J A

2009-09-16

362

Tablet computer use by medical students in the United States.  

PubMed

The value of tablet computer use in education is an area of considerable interest. Preliminary investigations shows that medical students feel that tablet computers were a positive addition to the preclinical curriculum. To better understand how and why medical students use tablet computers, we conducted an online survey of medical students in the United States This study shows frequent tablet computer use by medical students. Students in clinical years of medical school are the most frequent users of tablet computers. The high frequency of tablet computer use suggest that this may be an important area for medical educators to explore. PMID:23832806

Robinson, Robert L; Burk, Martha S

2013-07-07

363

A single blind normal volunteer bioavailability study of a new microencapsulated potassium chloride tablet compared with two reference potassium formulations  

Microsoft Academic Search

Summary  A single blind placebo controlled, cross-over study comparing a new microencapsulated potassium chloride tablet (MET) with\\u000a two reference formulations of oral potassium, potassium chloride solution (PS) and potassium chloride wax-matrix tablets (WMT),\\u000a was performed in 12 normal healthy volunteers. Urinary potassium excretion was the main criterion of comparison.\\u000a \\u000a \\u000a Results showed that all three formulations have excellent bioavailability. This indicates that

H. Caplain; R. Dahan; R. Pamphile; J. J. Thebault

1991-01-01

364

Development of theophylline floating microballoons using cellulose acetate butyrate and/or Eudragit RL 100 polymers with different permeability characteristics  

PubMed Central

The objective of the present investigation was to design a sustained release floating microcapsules of theophylline using two polymers of different permeability characteristics; Eudragit RL 100 (Eu RL) and cellulose acetate butyrate (CAB) using the oil-in-oil emulsion solvent evaporation method. Polymers were used separately and in combination to prepare different microcapsules. The effect of drug-polymer interaction was studied for each of the polymers and for their combination. Encapsulation efficiency, the yield, particle size, floating capability, morphology of microspheres, powder X-ray diffraction analysis (XRD), and differential scanning calorimetry (DSC) were evaluated. The in vitro release studies were performed in PH 1.2 and 7.4. The optimized drug to polymer ratios was found to be 4:1 (F2) and 0.75:1 (F'2) with Eu RL and CAB, respectively. The best drug to polymer ratio in mix formulation was 4:1:1 (theophylline: Eu RL: CAB ratio). Production yield, loading efficiencies, and particle size of F2 and F’2 were found to be 59.14% and 45.39%, 73.93% and 95.87%, 372 and 273 micron, respectively. Microsphere prepared with CAB showed the best floating ability (80.3 ± 4.02% buoyancy) in 0.1 M HCl for over 12 h. The XRD and DSC showed that theophylline in the drug loaded microspheres was stable and in crystaline form. Microparticles prepared using blend of Eu RL and CAB polymers indicated more sustained pattern than the commercial tablet (P<0.05). Drug loaded floating microballoons prepared of combination of Eu RL and CAB with 1:1 ratio were found to be a suitable delivery system for sustained release delivery of theophylline which contained lower amount of polymer contents in the microspheres.

Jelvehgari, M.; Maghsoodi, M.; Nemati, H.

2010-01-01

365

Matrix Simulation  

NSDL National Science Digital Library

This applet simulates the operation of a 2x2 matrix geometrically. The simulation shows a 2D image of the transformation of unit vectors due to the matrix. It displays the values of the matrix coefficients, the eigenvectors and the determinant. The matrix can be transposed, inverted or rotated. The page also includes an extensive explanation, and the source.

Falstad, Paul

2004-07-23

366

Angular circulation speed of tablets in a vibratory tablet coating pan.  

PubMed

In this work, a single tablet model and a discrete element method (DEM) computer simulation are developed to obtain the angular circulation speed of tablets in a vibratory tablet coating pan for range of vibration frequencies and amplitudes. The models identify three important dimensionless parameters that influence the speed of the tablets: the dimensionless amplitude ratio (a/R), the Froude number (a?2/g), and the tablet-wall friction coefficient, where a is the peak vibration amplitude at the drum center, ? is the vibration angular frequency, R is the drum radius, and g is the acceleration due to gravity. The models predict that the angular circulation speed of tablets increases with an increase in each of these parameters. The rate of increase in the angular circulation speed is observed to decrease for larger values of a/R. The angular circulation speed reaches an asymptote beyond a tablet-wall friction coefficient value of about 0.4. Furthermore, it is found that the Froude number should be greater than one for the tablets to start circulating. The angular circulation speed increases as Froude number increases but then does not change significantly at larger values of the Froude number. Period doubling, where the motion of the bed is repeated every two cycles, occurs at a Froude number larger than five. The single tablet model, although much simpler than the DEM model, is able to predict the maximum circulation speed (the limiting case for a large value of tablet-wall friction coefficient) as well as the transition to period doubling. PMID:23325382

Kumar, Rahul; Wassgren, Carl

2013-01-17

367

Multiple-scored tablets. Weight and content uniformity of subdivisions and distribution of active constituent within and between tablets.  

PubMed

Using three brands of multiple-scored levodopa tablets, B.P. (500 mg) and one brand of sulphamethoxypyridazine tablets B.P. (500 mg) the weight and content uniformity of the subdivisions has been examined. It is shown that quartering of such tablets can result in subunits which do not conform to recognized standards of weight uniformity, and in some instances content uniformity may be questionable. The homogeneity of distribution of active constituent between tablets has been determined and compared with that within tablets (between quarters of individual tablets). Statistical evaluation of the results is presented. PMID:27603

Walker, J; Abdulsalam, A; Theobald, A E; Subrahmanyam, R; Verma, S K

1978-07-01

368

Submerged (under-liquid) floating of light objects.  

PubMed

A counterintuitive submerged floating of objects lighter than the supporting liquid was observed. Polymer plates with dimensions on the order of magnitude of the capillary length were hydrophilized with cold air plasma were floated in an "under-liquid" regime (totally covered by liquid) when immersed in water or glycerol. Profiles of liquid surfaces curved by polymer plates are measured. We propose a model explaining the phenomenon. The floating of Janus plates is reported. PMID:23906242

Bormashenko, Edward; Pogreb, Roman; Grynyov, Roman; Bormashenko, Yelena; Gendelman, Oleg

2013-08-15

369

The MIPS R3010 floating-point coprocessor  

Microsoft Academic Search

A description is given of the R3010 floating-point accelerator chip, a coprocessor that is based on advanced reduced-instruction-set-computer (RISC) architecture and VLSI design techniques and provides high-speed floating-point operation. The 75000-transistor hard-wired chip executes four instructions in parallel. Its performance is compared with that of available floating-point processors and its architecture is examined. The organization and implementation of the R3010

C. Rowen; M. Johnson; P. Ries

1988-01-01

370

Numerical simulation of transient hydroelastic response of a floating beam induced by landing loads  

Microsoft Academic Search

The dynamic response of a floating platform under the effects of impulsive and moving loads is of concern in various areas of engineering technology, such as floating airports, floating bridges and buoyant tunnels, among others. In the present work, the floating platform is simplified as a flexible beam floating in an infinite water domain. The water is assumed to be

Liu-chao Qiu

2007-01-01

371

GIS spatial analysis of floating population in Wenzhou, China: Implications for industrial restructuring  

Microsoft Academic Search

The paper analyses the spatial distribution of floating population in Wenzhou urban districts using the data gained from the fifth census (2000) and floating population statistics (2008). The floating population in Wenzhou urban districts clustered in geographic space and is three circling structure. More floating population settled in suburb in 2000, and the high clustering circle of floating population has

Jianguang Xu

2011-01-01

372

21 CFR 520.1200 - Ivermectin, fenbendazole, and praziquantel tablets.  

Code of Federal Regulations, 2010 CFR

...false Ivermectin, fenbendazole, and praziquantel tablets. 520.1200 Section 520...1200 Ivermectin, fenbendazole, and praziquantel tablets. (a) Specifications ...fenbendazole, and 57 milligrams (mg) praziquantel; or (2) 27 µg ivermectin,...

2009-04-01

373

21 CFR 520.1200 - Ivermectin, fenbendazole, and praziquantel tablets.  

Code of Federal Regulations, 2013 CFR

...false Ivermectin, fenbendazole, and praziquantel tablets. 520.1200 Section 520...1200 Ivermectin, fenbendazole, and praziquantel tablets. (a) Specifications ...fenbendazole, and 57 milligrams (mg) praziquantel; or (2) 27 µg ivermectin,...

2013-04-01

374

21 CFR 520.1199 - Ivermectin, pyrantel, and praziquantel tablets.  

Code of Federal Regulations, 2010 CFR

...false Ivermectin, pyrantel, and praziquantel tablets. 520.1199 Section 520...1199 Ivermectin, pyrantel, and praziquantel tablets. (a) Specifications ...mg) pyrantel pamoate, and 28.5 mg praziquantel; (2) 68 mcg ivermectin, 57...

2009-04-01

375

21 CFR 520.1409 - Methylprednisolone, aspirin tablets.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 false Methylprednisolone, aspirin tablets. 520.1409 Section 520... § 520.1409 Methylprednisolone, aspirin tablets. (a) Specifications. ...methylprednisolone and 300 milligrams of aspirin. (b) Sponsor. See No....

2009-04-01

376

Development and characterization of buccoadhesive nifedipine tablets.  

PubMed

The buccoadhesive controlled-release tablets for delivery of nifedipine were prepared by direct compression of carboxymethyl cellulose (CMC) with carbomer (CP), which showed superior bioadhesion properties compared to polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA), hydroxypropylmethyl cellulose (HPMC), and acacia in a modified tensiometry method in vitro. The tablets containing 30mg of nifedipine and various amounts of CMC and CP showed a zero-order drug release kinetic. The adhesion force was significantly affected by the mixing ratio of CP:CMC in the tablets. The weakest and highest adhesion force was observed at the mixing ratios of 1:0 and 8:2 of CP:CMC, respectively. The tablets containing 15% CMC and 35% CP adhered for over 8h to the upper gums of six healthy human volunteers. These tablets released about 56% of the loaded drug after 8h in vivo with a rate of 2.17h(-1) and were perfectly tolerated, while they released about 100% of their content after the same time with a rate of 3.49h(-1) in vitro. A good correlation (r(2)=0.989) was observed between drug-released in vitro and in vivo. PMID:12191683

Varshosaz, J; Dehghan, Z

2002-09-01

377

The tableting properties of melibiose monohydrate.  

PubMed

In this research, the tableting properties of ?-melibiose monohydrate were studied. Melibiose is a disaccharide which bears structural resemblance to lactose, because they both consist of galactose and glucose monosaccharide subunits. Compactibility and deformation behavior of two melibiose batches from different suppliers were studied and compared with ?-lactose monohydrate and some other typical tableting excipients. Differences in the deformation behavior were determined comparing the shape of the Heckel plots, the yield pressure values and the strain rate sensitivity (SRS) indexes. In addition, the effect of moisture on the tabletability was studied. According to the yield pressures and SRS indexes melibiose was concluded to be fragmenting, even at higher degree than lactose monohydrate. However, the overall deformation behavior of melibiose was found to be similar to that of lactose monohydrate. Increase in moisture content resulted in higher tensile strengths of tablets for both melibiose batches, but it seemed to have more effect on compactibility of the other batch. In conclusion, melibiose has potential to be used as an excipient in tablet formulations. PMID:23994759

Lakio, Satu; Sainio, Janne; Heljo, Petteri; Ervasti, Tuomas; Kivikero, Niina; Juppo, Anne

2013-08-28

378

Bulk Raman analysis of pharmaceutical tablets.  

PubMed

We compare and contrast two Raman collection geometries, backscattering and transmission, to identify their potential for monitoring the bulk chemical composition of turbid media. The experiments performed on pharmaceutical tablets confirm the expected strong bias of the backscattering Raman collection towards surface layers of the probed sample. However, this bias is largely absent with the transmission geometry, exhibiting gross insensitivity to the depth of impurities within the sample. The results are supported by Monte-Carlo simulations. The applicability of transmission geometry to tablets without any thinning is possible because of long migration times of Raman photons in non-absorbing powder media. The absolute measured intensity of the Raman signal was only 12 times lower in transmission geometry compared with backscattering geometry for a standard paracetamol tablet with a thickness of 3.9 mm. This makes detection relatively straightforward, and detectable Raman signals were observed even after propagation through three paracetamol tablets. Given its properties and instrumental simplicity, the transmission method is particularly well suited to the on-line analysis of bulk content of tablets in pharmaceutical applications. PMID:17217583

Matousek, P; Parker, A W

2006-12-01

379

Percolative drug diffusion from cylindrical matrix systems with unsealed boundaries.  

PubMed

Release of NaCl in both the axial and radial directions from cylindrical ethyl cellulose tablets were investigated by the alternating ionic current method. The pore structure of the investigated binary mixtures was examined by mercury porosimetry and scanning electron microscopy, and the nm range fractal surface dimension of tablet pore walls was extracted from krypton gas adsorption isotherms. The drug release was shown to consist of two overlapping processes of which the first was ascribed to dissolution of NaCl close to the tablet boundary followed by subsequent diffusion through a thin ethyl cellulose layer and a second from which a porosity percolation threshold of 0.22 could be extracted. As well, a cross-over to effective-medium behaviour at a porosity of approximately 0.44 was observed. The presented findings showed that drug release from matrix tablets with unsealed tablet walls substantially differs from earlier investigated release processes for which the drug has only been allowed to escape through one of the flat tablet surfaces. Thus, the present study brings forward knowledge important for the tailoring of controlled drug delivery vehicles with optimum release patterns. PMID:17721939

Brohede, U; Valizadeh, S; Strømme, M; Frenning, G

2007-11-01

380

Evaluation and floating enhancement of levodopa sustained release floating minitablets coated with insoluble acrylic polymer.  

PubMed

This article describes the in vitro evaluation and the enhancement of the floating properties of coated sustained release (SR) minitablets (MTs). The evaluated system consisted of a 3-mm drug-containing gas-generating core prepared by melt granulation and subsequent compression, which was then coated with a flexible polymeric membrane. Eudragit RL30D and acetyl triethylcitrate were used as a film former and a plasticizer, respectively. The coating level was fixed at 20% (wt/wt). The optimally coated floating MTs floated within 10 min and remained buoyant for more than 13 h, regardless of the pH of the test medium. By evaluating the dissolution profiles of levodopa at different pH, it was found that the release of levodopa was sustained for more than 12 h regardless of the pH, even if the coating did not cancel the effect of the pH-dependent solubility of the active drug. Finally, the robustness of the coated floating MTs was assessed by testing the drug release variability in function of the stirring conditions during dissolution tests. PMID:18618310

Goole, J; Amighi, K; Vanderbist, F

2008-08-01

381

On a comprehensive case for Managed Floating in Thailand: How much “managed” and how much “floating”?  

Microsoft Academic Search

This paper searches for an appropriate exchange rate regime and provide a broad guideline for exchange rate management for Thailand in the medium term. An appropriate exchange rate regime is defined to be a credible regime that is most desirable. Our findings are in agreement with the flexible exchange rate view, but not freely floating. Flexible exchange rate is associated

Ashvin Ahuja

2004-01-01

382

Calcium-silicate-based floating granular delivery system of ranitidine hydrochloride for effective management of peptic ulcer  

Microsoft Academic Search

The objective of the present investigation was to prepare and evaluate a floating granular delivery system for the treatment\\u000a of mucosal ulcer consisting of (i) calcium silicate (CS) as a porous carrier; (ii) ranitidine hydrochloride (RH), an anti-ulcer\\u000a agent; and (iii) hydroxypropyl methylcellulose K4M (HPMC) and ethylcellulose (EC) as matrix-forming polymers. The effect of\\u000a various formulation and process variables on

Ashish Jain; Prateek Jain; Sunil K. Jain; Ram K. Agrawal; Govind P. Agrawal

2008-01-01

383

Tried and True: Whatever floats your boat  

NSDL National Science Digital Library

Ever since Archimedes ran down the streets of ancient Greece shouting, "Eureka!," scientists have understood that a submerged body displaces a volume of water equalto its own volume. Scientists also came to realize that if a body weighed less than the water it displaced, the body would float. Although this knowledge has been aroundfor nearly 2,500 years, many students still have difficulty explaining how a vessel made of a heavier-than-water material, such as steel, remains afloat. The following triedand true activity provides students with a hands-on experience that explains the principle of buoyancy.

Mcbride, Susan L.

2003-03-01

384

Research effort aims at floating production technology  

SciTech Connect

This paper reports that a 3 year research and development program on floating production systems (FPS), instigated by the Royal Norwegian Council for Scientific and Industrial Research (NTNF), has refined and qualified technologies for North Sea and arctic conditions. The FPS 2000 program, which cost 58 million kroner ($10 million), concentrated mainly on mooring systems and pipeline technology, along with new system concepts and cost reduction measures. More than 30 projects have been completed within the scheme. The anchoring and positioning project concentrates on developing methods for simulating behavior of mooring systems for large volume structures in deep water. It also seeks ways to determine efficiency of dynamic positioning thrusters under extreme conditions.

Not Available

1992-08-17

385

Localized buckling of a floating elastica  

NASA Astrophysics Data System (ADS)

We study the buckling of a two-dimensional elastica floating on a bath of dense fluid, subjected to axial compression. The sinusoidal pattern predicted by the analysis of linear stability is shown to become localized above the buckling threshold. A nonlinear amplitude equation is derived for the envelope of the pattern. These results provide a simple interpretation to the wrinkle-to-fold transition reported by Pocivavsek [ScienceSCIEAS0036-807510.1126/science.1154069 320, 912 (2008)]. An analogy with the classical problem of the localized buckling of a strut on a nonlinear elastic foundation is presented.

Audoly, B.

2011-07-01

386

Formulation and in vivo evaluation of omeprazole buccal adhesive tablet  

Microsoft Academic Search

For the development of omeprazole buccal adhesive tablets, we studied the release and bioavailability of omeprazole delivered by buccal adhesive tablets composed of sodium alginate, hydroxypropylmethylcellulose (HPMC), magnesium oxide and croscarmellose sodium. Croscarmellose sodium enhanced the release of omeprazole from the tablets. The analysis of the release mechanism showed that croscarmellose sodium changed the release profile of omeprazole from first-

Han-Gon Choi; Jac-Hee Jung; Chul Soon Yong; Chong-Dal Rhee; Mi-Kyung Lee; Jeong-Hee Han; Kyung-Mi Park; Chong-Kook Kim

2000-01-01

387

Adhesive tablet effective for treating canker sores in humans  

Microsoft Academic Search

A new mucoadhesive tablet, which releases natural active agents for pain reduction and rapid healing of canker sores, has been prepared and characterized. Adhesive tablets were prepared by compression molding of mixed powders of crosslinked polyacrylic acid and hydroxypropyl cellulose, absorbed with citrus oil and magnesium salt. The rate of tablet erosion and the rates of citrus oil and magnesium

Boaz Mizrahi; Jacob Golenser; Joseph S. Wolnerman; Abraham J. Domb

2004-01-01

388

Issues and techniques in touch-sensitive tablet input  

Microsoft Academic Search

Touch-sensitive tablets and their use in human-computer interaction are discussed. It is shown that such devices have some important properties that differentiate them from other input devices (such as mice and joysticks). The analysis serves two purposes: (1) it sheds light on touch tablets, and (2) it demonstrates how other devices might be approached. Three specific distinctions between touch tablets

William Buxton; Ralph Hill; Peter Rowley

1985-01-01

389

The Tablet PC For Faculty: A Pilot Project  

Microsoft Academic Search

This paper describes a pilot project with the purpose of evaluating the usefulness of tablet PCs for university professors. The focus is on the value of tablets primarily with respect to teaching and learning (and not for research or administrative work). Sixty-four professors, distributed across the various schools of a university, were provided with tablet PCs and were trained in

Rob R. Weitz; Bert Wachsmuth; Danielle Mirliss

2006-01-01

390

Formulation and evaluation of bi-layer tablet of metoclopramide hydrochloride and ibuprofen.  

PubMed

The aim of this study was to prepare bi-layer tablet of Metoclopramide Hydrochloride (MTH) and Ibuprofen (IB) for the effective treatment of migraine. MTH and IB were formulated as immediate and sustained release layer respectively. MTH was formulated as immediate release layer by using various disintegrants like Ac-Di-Sol, Polyplasdone XL, Explotab, Agar and Gellan Gum. Treated form of gellan gum and agar was prepared and compared for their disintegrant efficiency with other disintegrants. IB was formulated as sustained release layer using hydrophilic matrix (hydroxypropylmethylcellulose [HPMC K(4)M]). The effect of concentration of hydrophilic matrix (HPMC K(4)M), binder (polyvinylpyrollidone [PVP K(30)]) and buffer (sodium bicarbonate) on IB release was studied. The dissolution study of sustained release layer showed that an increasing amount of HPMC or PVP K(30) results in reduced IB release. The inclusion of buffer (sodium bicarbonate) enhanced the release of IB from sustained release layer. The rational for formulation of bi-layer tablet of these two drugs in combination was (1) MTH increases the absorption of acidic non-steroidal anti-inflammatory drug (NSAID) by increasing gastric motility. So sequential release of MTH (as immediate release) and IB (as sustained release) was suitable for treatment of migraine. (2) MTH was degraded when prolonged contact with acidic NSAID. Bi-layer tablet was suitable for preventing direct contact of these two drugs and thus to maximize the efficacy of combination of two drugs for migraine. PMID:18612830

Shiyani, Bhavesh; Gattani, Surendra; Surana, Sanjay

2008-07-09

391

Spectrophotometric Estimation of Azithromycin in Tablets  

PubMed Central

The present manuscript describes a simple, sensitive, accurate, precise and economical visible spectrophotometric method for the estimation of azithromycin from tablet formulation. The method is based on the reduction of potassium permanganate in alkaline medium with azithromycin. The measurement of decrease in absorbance of potassium permanganate at 547 nm was done, as it decolourises upon reduction by azithromycin. The method was used to determine between 2 and 20 ?g/ml of azithromycin in the final measured solution. There is no interference from the ingredients commonly found in azithromycin tablets with this method. The results for the determination of azithromycin in tablets were in good agreement with the labelled quantities and related analytical parameters are calculated.

Jayanna, B. K.; Nagendrappa, G.; Arunkumar; Gowda, N.

2012-01-01

392

40 CFR 65.43 - Fixed roof with an internal floating roof (IFR).  

Code of Federal Regulations, 2013 CFR

...cover or gasketed lid. (iii) Each penetration of the internal floating roof shall...vent shall be gasketed. (v) Each penetration of the internal floating roof that allows...gasketed sliding cover. (vi) Each penetration of the internal floating roof...

2013-07-01

393

33 CFR 149.550 - What are the requirements for lights on a floating hose string?  

Code of Federal Regulations, 2013 CFR

...false What are the requirements for lights on a floating hose string? 149...AND EQUIPMENT Aids to Navigation Lights on Floating Hose Strings § 149.550 What are the requirements for lights on a floating hose string?...

2013-07-01

394

Floating bodies in two dimensions without gravity  

NASA Astrophysics Data System (ADS)

In this paper we study the stability of equilibrium configurations for two-dimensional smooth convex bodies in the absence of gravity, focusing on one example in particular, the ellipse. We also begin to consider the floating configurations of bodies which are not strictly convex; that is, bodies that have one or more linear sides. We will show that a body cannot float in a stable equilibrium with the fluid interface intersecting the interior of a straight side in a single point, and then using this result we will proceed to study the stability of convex bodies comprised of only straight sides consequently deriving a necessary and sufficient condition for stable equilibrium of polygonal bodies. We illustrate our findings using the square as an example. Finally, we prove several results concerning the number of stable and unstable configurations for an n-sided regular polygon (n>=3) including a result guaranteeing the existence of a stable global energy minimum provided the contact angle ? is not 0 or ?.

Kemp, Todd M.; Siegel, David

2011-04-01

395

Defining the IEEE-854 Floating-Point Standard in PVS.  

National Technical Information Service (NTIS)

A significant portion of the ANSI/IEEE-854 Standard for Radix-Independent Floating-Point Arithmetic is defined in PVS (Prototype Verification System). Since IEEE-854 is a generalization of the ANSI/IEEE-754 Standard for Binary Floating-Point Arithmetic, t...

P. S. Miner

1995-01-01

396

33 CFR 144.01-10 - Equipment for life floats.  

Code of Federal Regulations, 2013 CFR

...water light must be attached to the life float by a 12-thread manila or...12 feet) in length. The water light must be mounted on a bracket so that when the life float is launched, the water light will pull free of the bracket....

2013-07-01

397

33 CFR 144.01-10 - Equipment for life floats.  

Code of Federal Regulations, 2010 CFR

...water light must be attached to the life float by a 12-thread manila or...12 feet) in length. The water light must be mounted on a bracket so that when the life float is launched, the water light will pull free of the bracket....

2009-07-01

398

33 CFR 144.01-10 - Equipment for life floats.  

Code of Federal Regulations, 2010 CFR

...water light must be attached to the life float by a 12-thread manila or...12 feet) in length. The water light must be mounted on a bracket so that when the life float is launched, the water light will pull free of the bracket....

2010-07-01

399

33 CFR 144.01-15 - Alternates for life floats.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Alternates for life floats. 144.01-15 Section 144.01-15...Platforms § 144.01-15 Alternates for life floats. (a) Approved lifeboats, approved life rafts or approved inflatable life rafts...

2013-07-01

400

Maximum size of floating particles in different flotation cells  

Microsoft Academic Search

Two flotation models, particle at the liquid–gas interface and particle–bubble aggregate, both based on balance of forces, were used for evaluation of experimental data relating the maximum size of floating particles dmax and their advancing contact angle. It was noticed, by comparing the experimental and model data, that for a given flotation device and material the maximum size of floating

Przemyslaw B. Kowalczuk; Oktay Sahbaz; Jan Drzymala

2011-01-01

401

Tracking control in space robot grasping a floating object  

Microsoft Academic Search

Tracking control and active damping control was applied in space robot capturing a floating object. The grasping operation becomes quite complicated and important for the nonlinear characteristics, such as the dynamic coupling between the manipulator and the space base, the impact of grasping and so on while space robot captures a floating object. Firstly, the dynamic model of the space

Yang Zhao; Cheng Wei; Hongliu Wang

2009-01-01

402

22. Float located adjacent to entry stair in filtration bed. ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

22. Float located adjacent to entry stair in filtration bed. The float actuates a valve that maintains water level over the bed. - Lake Whitney Water Filtration Plant, Filtration Plant, South side of Armory Street between Edgehill Road & Whitney Avenue, Hamden, New Haven County, CT

403

Hydroelastic behaviour of compound floating plate in waves  

Microsoft Academic Search

The paper deals with the plane problem of the hydroelastic behaviour of floating plates under the influence of periodic surface water waves. Analysis of this problem is based on hydroelasticity, in which the coupled hydrodynamics and structural dynamics problems are solved simultaneously. The plate is modeled by an Euler beam. The method of numerical solution of the floating-beam problem is

T. I. Khabakhpasheva; A. A. Korobkin

2002-01-01

404

Surface characterization of float glass using Indus1  

Microsoft Academic Search

The production of window glass is through float technique, which causes diffusion of tin into glass surface in contact with molten tin. Using Indus-1 storage ring, angle dependent reflectivity of the top and the bottom surface of float glass were measured in vacuum ultra violet\\/ soft x-ray region. Remarkable differences in refractive index were observed between the two sides. Surface

G. S. Lodha; M. K. Tiwari; K. J. S. Sawhney; M. H. Modi; R. V. Nandedkar

405

Dynamic Characteristics of a Floating Squeeze Film Bearing.  

National Technical Information Service (NTIS)

A floating squeeze film bearing is a flexible support system used to attenuate the forces generated by a rotating unbalanced shaft. Since the journal translates instead of rotating, a floating squeeze film bearing develops twice the load of an ordinary jo...

G. C. Horner

1968-01-01

406

Dynamic characteristics of a floating squeeze film bearing  

Microsoft Academic Search

A floating squeeze film bearing is a flexible support system used to attenuate the forces generated by a rotating unbalanced shaft. Since the journal translates instead of rotating, a floating squeeze film bearing develops twice the load of an ordinary journal bearing. Hydrodynamic forces are generated in the fluid film of the squeeze film bearing which counteract the unbalanced force.

1968-01-01

407

Coupled Dynamic Modeling of Floating Wind Turbine Systems: Preprint  

Microsoft Academic Search

This article presents a collaborative research program that the Massachusetts Institute of Technology (MIT) and the National Renewable Energy Laboratory (NREL) have undertaken to develop innovative and cost-effective floating and mooring systems for offshore wind turbines in water depths of 10-200 m. Methods for the coupled structural, hydrodynamic, and aerodynamic analysis of floating wind turbine systems are presented in the

E. N. Wayman; P. D. Sclavounos; S. Butterfield; J. Jonkman; W. Musial

2006-01-01

408

Children's knowledge of hierarchical phrase structure: quantifier floating in Japanese.  

PubMed

The interpretation of floating quantifiers in Japanese requires knowledge of hierarchical phrase structure. However, the input to children is insufficient or even misleading, as our analysis indicates. This presents an intriguing question on learnability: do children interpret floating quantifiers based on a structure-dependent rule which is not obvious in the input or do they employ a sentence comprehension strategy based on the available input? Two experiments examined four- to six-year-old Japanese-speaking children for their interpretations of floating quantifiers in SOV and OSV sentences. The results revealed that no child employed a comprehension strategy in terms of the linear ordering of constituents, and most five- and six-year-olds correctly interpreted floating quantifiers when word-order difficulty was reduced. These facts indicate that children's interpretation of floating quantifiers is structurally dependent on hierarchical phrase structure, suggesting that this knowledge is a part of children's grammar despite the insufficient input available to them. PMID:22850618

Suzuki, Takaaki; Yoshinaga, Naoko

2012-07-31

409

Effect of a floating electrode on a plasma jet  

NASA Astrophysics Data System (ADS)

Two kinds of floating electrode, floating dielectric barrier covered electrode (FDBCE) and floating pin electrode (FPE), which can enhance the performance of plasma jet are reported. The intense discharge between the floating electrode and power electrode decreased the voltage to trigger the plasma jet substantially. The transition of plasma bullet from ring shape to disk shape in the high helium concentration region happened when the floating electrode was totally inside the powered ring electrode. The enhanced electric field between propagating plasma bullet and ground electrode is the reason for this transition. The double plasma bullets happened when part of the FDBCE was outside the powered ring electrode, which is attributed to the structure and surface charge of FDBCE. As part of the FPE was outside the powered ring electrode, the return stroke resulted in a single intensified plasma channel between FPE and ground electrode.

Hu, J. T.; Wang, J. G.; Liu, X. Y.; Liu, D. W.; Lu, X. P.; Shi, J. J.; Ostrikov, K.

2013-08-01

410

The implementation of an out-of-order execution floating point unit  

Microsoft Academic Search

The prRISC32 FPU (floating-point unit) is a RISC coprocessor for embedded system applications. It supports IEEE754 standard single\\/double precision floating-point addition, floating-point subtraction, floating-point multiplication, floating-point division, floating-point square root, floating-point\\/fix-point format conversion, and floating point load\\/store, etc. It also supports four IEEE compliant rounding mode, and precise exception. It can execute and complete instructions out of order under certain

Luo Min; Bai Yong-Qiang; Shen Xu-Bang; Gao De-Yuan

2004-01-01

411

Fast-disintegrating sublingual tablets: Effect of epinephrine load on tablet characteristics  

Microsoft Academic Search

The aim of this study was to evaluate the effect of increasing epinephrine load on the characteristics of fast-disintegrating\\u000a sublingual tablets for the potential emergency treatment of anaphylaxis. Four tablet formulations, A, B, C, and D, containing\\u000a 0%, 6%, 12%, and 24% of epinephrine bitartrate, respectively, and microcrystalline cellulose:low-substituted hydroxypropyl\\u000a cellulose (9?1), were prepared by direct compression, at a range

Mutasem M. Rawas-Qalaji; F. Estelle; R. Simons; Keith J. Simons

2006-01-01

412

Objective color classification of ecstasy tablets by hyperspectral imaging.  

PubMed

The general procedure followed in the examination of ecstasy tablets for profiling purposes includes a color description, which depends highly on the observers' perception. This study aims to provide objective quantitative color information using visible hyperspectral imaging. Both self-manufactured and illicit tablets, created with different amounts of known colorants were analyzed. We derived reflectance spectra from hyperspectral images of these tablets, and successfully determined the most likely colorant used in the production of all self-manufactured tablets and four of five illicit tablets studied. Upon classification, the concentration of the colorant was estimated using a photon propagation model and a single reference measurement of a tablet of known concentration. The estimated concentrations showed a high correlation with the actual values (R(2) = 0.9374). The achieved color information, combined with other physical and chemical characteristics, can provide a powerful tool for the comparison of tablet seizures, which may reveal their origin. PMID:23683098

Edelman, Gerda; Lopatka, Martin; Aalders, Maurice

2013-05-17

413

Dissolution of tablet-in-tablet formulations studied with ATR-FTIR spectroscopic imaging.  

PubMed

This work uses ATR-FTIR spectroscopic imaging to study the dissolution of delayed release and pH resistant compressed coating pharmaceutical tablets. Tablets with an inner core and outer shell were constructed using a custom designed compaction cell. The core of the delayed release tablets consisted of hydroxypropyl methylcellulose (HPMC) and caffeine. The shell consisted of microcrystalline cellulose (MCC) and glucose. The core of the pH resistant formulations was an ibuprofen and PEG melt and the shell was constructed from HPMC and a basic buffer. UV/vis spectroscopy was used to monitor the lag-time of drug release and visible optical video imaging was used as a complementary imaging technique with a larger field of view. Two delayed release mechanisms were established. For tablets with soluble shell sections, lag-time was dependent upon rapid shell dissolution. For tablets with less soluble shells, the lag-time was controlled by the rate of dissolution medium ingress through the shell and the subsequent expansion of the wet HPMC core. The pH resistant formulations prevented crystallization of the ibuprofen in the core during dissolution despite an acidic dissolution medium. FTIR imaging produced important information about the physical and chemical processes occurring at the interface between tablet sections during dissolution. PMID:23291036

Wray, Patrick S; Clarke, Graham S; Kazarian, Sergei G

2013-01-02

414

Tablet PC: blackboard to the web  

Microsoft Academic Search

The use of the Tablet PC® as a lecture aid allows for the best of both worlds: the ability to present prepared lectures with well thought out graphics and the ability to annotate and develop a lecture in real time as would be done on a conventional blackboard. As classroom presentations become more computer based, they generally become less flexible

Steven J. Timmins

2004-01-01

415

Safety alert for fentanyl buccal tablets.  

PubMed

On September 13, 2007, the United States Food and Drug Administration posted a safety alert for fentanyl buccal tablets (Fentora). The announcement and hyperlinks to the Dear Doctor and Dear Healthcare Professional Letters that were distributed by the sponsor are presented. PMID:19062355

2008-01-01

416

You May Now Open Your Test Tablets...  

ERIC Educational Resources Information Center

|Tony Alpert, chief operating officer for the Smarter Balanced Assessment Consortium (SBAC), ponders whether to allow tablet computers--and particularly iPads--to be used for summative testing online. As Alpert points out, not only would student cheating compromise the validity of the individual student's test event, "worse yet, it could expose…

Schaffhauser, Dian

2012-01-01

417

Touch Tablet Surprises: A Preschool Teacher's Story  

ERIC Educational Resources Information Center

|A year and a half ago, Rena, Cheri, and Cassandra were introduced to each other by a colleague because they shared an interest in exploring the impact newer technologies have on learning in early childhood classrooms. They meet regularly to share ideas and information on how to incorporate tablets using best practices. Cassandra's preschool…

Shifflet, Rena; Toledo, Cheri; Mattoon, Cassandra

2012-01-01

418

Fast dispersible\\/slow releasing ibuprofen tablets  

Microsoft Academic Search

Eight formulations were developed containing ibuprofen in the form of orally disintegrating tablets. To prevent bitter taste and side effects of the drug, the drug was associated with Phospholipon 80H, a saturated lecithin, by wet granulation. The granules were then coated using different film forming agents (Kollicoat SR 30, Amprac 01, Kollidon 90F, Eudragit RD 100) obtaining four lots 1–4.

Adamo Fini; Valentina Bergamante; Gian Carlo Ceschel; Celestino Ronchi; Carlos Alberto Fonseca de Moraes

2008-01-01

419

Comparative bioavailability: Eight commercial prednisone tablets  

Microsoft Academic Search

Two four-treatment crossover bioavailability studies were performed in panels of 12 adult male volunteers with eight different commercial prednisone tablets. Plasma samples from the first study were assayed by radioimmunoassay for both prednisone and prednisolone. Plasma samples from the second study were assayed for prednisolone only. Statistical analyses of the data showed significant differences in the rate of appearance of

Timothy J. Sullivan; Margarette R. Hallmark; Ermelinda Sakmar; Donald J. Weidler; Robert H. Earhart; John G. Wagner

1976-01-01

420

Tablet computers and the traditional lecture  

Microsoft Academic Search

A nationwide call has requested educators to emphasize methods that will encourage student participation and engagement during class. Concurrently, technology and ubiquitous computing have been making advancements onto campuses of higher education. This paper will discuss the research that is merging these two events and creating a platform using Tablet PCs that can be used in the traditional classroom setting.

Mitchell D. Theys; Kimberly Lawless; Stephen George

2005-01-01

421

Touch Tablet Surprises: A Preschool Teacher's Story  

ERIC Educational Resources Information Center

A year and a half ago, Rena, Cheri, and Cassandra were introduced to each other by a colleague because they shared an interest in exploring the impact newer technologies have on learning in early childhood classrooms. They meet regularly to share ideas and information on how to incorporate tablets using best practices. Cassandra's preschool…

Shifflet, Rena; Toledo, Cheri; Mattoon, Cassandra

2012-01-01

422

You May Now Open Your Test Tablets...  

ERIC Educational Resources Information Center

Tony Alpert, chief operating officer for the Smarter Balanced Assessment Consortium (SBAC), ponders whether to allow tablet computers--and particularly iPads--to be used for summative testing online. As Alpert points out, not only would student cheating compromise the validity of the individual student's test event, "worse yet, it could expose…

Schaffhauser, Dian

2012-01-01

423

MEASUREMENT OF BOUNDARIES USING A DIGITIZER TABLET  

EPA Science Inventory

The perimeter is the most error prone of the primary measurements (length, perimeter and area) made when using a device such as a digitizer tablet to trace profiles on micrographs. o allow for minimization of this error an expression is developed relating the error in the perimet...

424

Formulation of a extended release tablet containing dexibuprofen.  

PubMed

Dexibuprofen, or S(+)-ibuprofen, is the pharmacologically effective enantiomer of racemic ibuprofen. Since dexibuprofen has a low melting point, the amorphous form having a high melting point was prepared with the fused solid dispersion method. With the fused solid dispersion of dexibuprofen, immediate release tablets, extended release tablets, and dual release tablets were compressed and their dissolution profiles compared. The dissolution profiles of the extended release and the dual release tablet depended on the amount of used release modulators (PEO 5,000,000). The release profiles of extended release tablets and extended release part of dual release tablets were well fitted to zero-order release model. The correlation coefficient ranged from 0.982 to 0.995. A pharmacokinetic evaluation where healthy volunteers took tablets of DRT-1 (300 mg) once and the reference drug, two tablets of conventional immediate release tablet (Daxfen, 300 mg), with a 6-h interval between them was studied. The 90% confidence interval for the ratio of the logarithmically transformed AUC (0-24 h), Cmax (0-6 h), and Cmax (6-24 h) values of the dual release tablet compared to those of the conventional immediate release tablet were calculated to be between 0.9176 and 1.0007, 0.9240 and 1.1968, and 0.8713 and 1.1414, respectively. When the immediate release tablet was taken two times with a six hour interval between doses it showed a bioequivalent effect to taking the dual release tablet once within 12 h. The Cmax was reached due to the rapid absorption of the immediate release portion of the dual release tablet and the AUC was maintained due to continuous absorption of the extended release portion. PMID:19099235

Yi, Hong Gi; Chi, Moon Hyuk; Kim, Yong-Il; Woo, Jong Soo; Park, Eun-Seok

2008-12-20

425

Floating-zone and floating-solution-zone growth of GaSb under microgravity  

Microsoft Academic Search

Three GaSb single crystals have been successfully grown under microgravity on Spacehab-4 during the STS-77 Space Shuttle flight. Two Te-doped crystals with 16mm diameter and lengths of 31.5 and 18mm, respectively, were grown by the floating-zone method. From the transition of striated to striation-free material it was possible to determine the critical Marangoni number for the onset of time-dependent thermocapillary

A. Cröll; Th Kaiser; M Schweizer; A. N Danilewsky; S Lauer; A Tegetmeier; K. W Benz

1998-01-01

426

Floating drilling rig apparatus and method  

SciTech Connect

This patent describes an apparatus adapted for use with a floating drilling rig having a marine riser including a telescopic joint. The telescopic joint has a guide/index key. The joint has an upwardly facing unterminated connector for a riser choke/kill line. The apparatus comprises: a terminal end assembly, including: a frame, yoke means slidably disposed on the frame for securing a drape hose terminated by a downwardly facing stab connector; means for moving the yoke means between an outer position and an inner position upon the frame; and slot means disposed on the yoke means for accepting the guide/index key of the telescopic joint when the yoke means is in the inner position.

Burton, J.A.

1987-05-26

427

Floating recycle pan for ebullated bed reactors  

SciTech Connect

This patent describes an ebullated bed reactor. It comprises: a substantially enclosed vessel having a lower portion and an upper portion for processing oil; oil feed means connected to the vessel for feeding an oil feed comprising oil and hydrogen-rich gases into the lower portion of the vessel; fresh catalyst feed means connected to the vessel for feeding fresh hydrotreating catalyst into the vessel; ebullating pump means located in the lower portion of the vessel for circulating the oil feed in the vessel in the presence of the catalyst to hydrotreat the oil; a tubular downcomer extending generally upward above the pump means. The downcomer having an upper end and, a lower end in proximity to the pump means, and an inner surface and an outer surface; and a floating tubular recycle pan.

Cox, J.A.

1990-03-27

428

Modeling and control of a floating platform  

NASA Astrophysics Data System (ADS)

A platform with a rotating crane resting on three adjustable floats in a tub has been built on laboratory scale. Controller design is studied to prevent the platform from leaning due to crane movements. The system dynamics can be described primarily by a simple sixth order linear model. Model errors are then due mainly to unmodeled effects of waves that are essentially linear transfers. It is precisely under these conditions that H(sub infinity) design should perform well. Actual design and tests show that H(sub infinity) controllers do not substantially outperform LQG designs combined with feedforward controllers, but the combination of both feedforward and feedback controllers can easily be obtained by H(sub infinity) design techniques.

Damen, Ad A. H.; Falkus, Heinz M.; Bouwels, Jo P. H. M.

1994-05-01

429

Inexpensive, floating, insect-emergence trap  

SciTech Connect

The Environmental Sciences Division of Oak Ridge National Laboratory has been investigating the usefulness of aquarium microcosms and ponds for the quantification and predictions of toxicant effects on freshwater systems. Ideally, concepts and methods applicable to both 150-L microcosms and 15,000-L ponds would bridge the gap between the two. The effort of processing the benthic samples, as well as the destructiveness of the sampling in small ponds, limited the number of samples that could be taken. Therefore, the author developed an inexpensive emergence trap appropriate for use in small outdoor ponds, as one method of increasing sampling efficiency and economy. To prevent the possibility of trapping adults from adjacent ponds, which would confound the results, the traps had to be designed such that they could only trap insects from the ponds upon which they were floating. The design of this trap is described.

Cushman, R.M.

1983-11-01

430

First census of floating population in Beijing.  

PubMed

This study presents the findings of the first census of the floating population in Beijing, China, in 1997. The census was conducted in 18 urban districts and counties among migrants living or staying in Beijing with household registration elsewhere. In 1997, the floating population amounted to 2.86 million, of whom 2.30 million stayed in Beijing over 1 day. 66.1% were males; 33.9% were females. 1.38 million (59.9%) lived in institutional households. 755,000 (32.9%) formed their own family units; 166,000 (7.2%) lived with resident Beijing families. 12,000 lived in railway stations and 22,000 were homeless. In-migrants numbered 435,000 and out-migrants numbered 42,000 in the preceding 24 hours. 84,000 (a doubling since 1984) were from Hong Kong, Macao, and Taiwan. In-migration was lower by 436,000 persons than in 1994. The decline is attributed to government policy to limit migration and to economic recession. Better communication and transportation facilitate foreign migration. 1.81 million migrants out of 2.30 million lived in 4 urban and 4 suburban districts. The others lived in 10 remote suburban areas. Migrants accounted for 537,000 persons in Chaoyang District (23.3%), 493,000 in Haidan District (21.5%), and 315,000 in Fengtai District (13.7%). The ratio of in-migrants to residents was 1:8 in Beijing urban districts, 1:4 in suburban districts, and 1:10 in remote areas. Stays averaged 19.2 months. 1.81 million had jobs. About 74% came from Hebei, Henan, Zhejiang, Sichuan, Shandong, Jiangsu, and Anhui. Zhejiang migrants stayed the longest (24.9 months), while Jiangsu in-migrants stayed the shortest (16.6 months). PMID:12321925

1998-12-01

431

Modulation of tramadol release from a hydrophobic matrix: implications of formulations and processing variables.  

PubMed

In the present investigation, hydrogenated cottonseed oil (HCSO) was evaluated as a sustained release matrix for a freely soluble drug, tramadol. Hydrophobic matrix tablets of tramadol, was evaluated by compression of physical mixture of drug and wax, dispersion of drug in HCSO by hot fusion or solubilisation techniques. The method of preparation of tablet had a significant effect on drug release with higher release observed from direct compression matrices and slower release from matrix prepared by dispersion (hot-fused matrices). Influence of addition of hydroxypropylmethyl cellulose, sodium carboxymethyl cellulose, polyethylene glycol 4000 and surfactants like sodium lauryl sulphate and polysorbate 20 to HCSO matrix on drug release was investigated. The added excipients exhibited a propensity to enhance drug release from the HCSO matrix. NaCMC was effective at a lower ratio (<10% w/w) and when incorporated at higher level made HCSO matrix to erode and disintegrate in a short period. PMID:20300896

Sudha, B S; Sridhar, B K; Srinatha, A

2010-03-19

432

Effect of Food on the Multiple-Peak Behavior After a Single Oral Dose of Diclofenac Sodium Slow-Release Tablet in Humans.  

PubMed

This study evaluated the effect of a standard meal on the multiple-peak behavior of diclofenac sodium following oral administration of a 100-mg slow-release (SR) wax-matrix tablet. The study was a randomized, 3 × 3 Latin-square trial balanced for residual effects, in which 18 subjects were randomly assigned to treatment sequences consisting of three treatments: (A) one 100-mg SR tablet, fasted; (B) one 100-mg SR tablet, fed; and (C) 100-mg diclofenac sodium buffered aqueous solution, fasted. Blood samples were obtained over a 24-h period for Treatments A and B, and over an 8-h period for Treatment C. Food did not significantly affect the extent of absorption but generally delayed the onset of absorption from the SR tablet. The plasma concentration-time profile for the SR tablet under fasted conditions was characterized by multiple-peak behavior. Under fed conditions, the SR tablet showed a more consistent absorption pattern, with a single peak occurring usually between 5 and 6 h. The concentration-time profile of the buffered aqueous solution showed a very rapid absorption phase followed by a rapid decline and a terminal elimination half-life of approximately 1.8 h. A single peak was observed following the buffered aqueous solution. This observation, in conjunction with evidence from other studies, leads to the conclusion that gastrointestinal pH may be responsible for the multiple-peak behavior observed following diclofenac sodium dosing. As compared to the solution, the was-matrix tablet under both fasted and fed conditions showed slow-release, characteristics. PMID:11850655

Riad, Lillian E.; Sawchuk, Ronald J.; McAlary, Margaret M.; Chan, Keith K.H.

1995-04-01

433

Development and evaluation of a monolithic floating dosage form for furosemide.  

PubMed

The poor bioavailability of orally dosed furosemide (60%), a weakly acidic drug, is due to the presence of a biological window comprised of the upper gastrointestinal tract. The purpose of the present study was to develop and optimize in vitro a monolithic modified-release dosage form (MMR) for furosemide with increased gastric residence time and to evaluate the in vivo performance of the dosage form. The principle of floatation was used to restrict the MMR to the stomach. A two-factor three-level full factorial experimental design was employed for formulation development. A flow-through cell was designed to evaluate in vitro dissolution parameters. Quadratic regression models indicated the polymer viscosity and polymer:drug ratio to be significant (p < 0.05) formulation factors in determining the duration of buoyancy and the release profile. Statistical optimization using response surface methodology with certain physiological constraints relating to gastric emptying time predicted an optimal MMR. In vivo evaluation of the optimized MMR in beagle dogs resulted in a significant increase (p < 0.05) in the absolute bioavailability for the MMR dosage form (42.9%) as compared to the commercially available tablet (33.4%) and enteric product (29.5%). Significant in vitro/in vivo correlations (p < 0.05) were obtained for the MMR using deconvolution analysis normalized for bioavailability. The floating dosage form was found to be a feasible approach in delivering furosemide to the upper gastrointestinal tract to maximize drug absorption. PMID:8169797

Menon, A; Ritschel, W A; Sakr, A

1994-02-01

434

Compression-coated tablets of glipizide using hydroxypropylcellulose for zero-order release: in vitro and in vivo evaluation.  

PubMed

Compression coating, which presents some advantages like short manufacturing process and non-solvent residue over liquid coating, has been introduced to the oral administration systems for decades. The purpose of this study was to design a zero-order release of compression-coated tablets using hydroxypropylcellulose (HPC) as the coating layer and glipizide which was solubilized by manufacturing the inclusion complex of ?-cyclodextrin as a model drug. The effects of the weight ratio of drug and the viscosity of HPC on the release profile were investigated by "f2" factor with Glucotrol XL(®). The uptake and erosion study, the correlation coefficient (R) and the exponent (n) were used as indicators to justify drug release mechanism. Bioavailability in vivo was determined by administering the compression-coated tablets to rabbits in contrast with Glucotrol XL(®). It was found that the formulation presented a well zero-order behavior at the weight ratio of drug 11:14 (core:layer) and the combination of HPC-L (8.0 mPa s) and HPC-M (350 mPa s) (8:9), with the "f2" of 66.90. The mechanism for zero-order release of these compression-coated tablets was solvent penetration into the dosage form and drug dissolution from the erosion of the gelled HPC matrix. The parameter AUC0-? of the compression coated tablets and the market tablets were 37,255.93±1474.08 h ng/ml and 43265.40±1015.28 h ng/ml, while the relative bioavailability was 87.66±1.56%. These studies demonstrate that the designed compression-coated tablets may be a promising strategy for peroral controlled release delivery system of water-insoluble drugs. PMID:23370433

Huang, Haiqin; Wu, Zhenghong; Qi, Xiaole; Zhang, Huiting; Chen, Qin; Xing, Jiayu; Chen, Haiyan; Rui, Yao

2013-01-28

435

Recent advances in gastric floating drug delivery technology: a review.  

PubMed

Gastric floating drug delivery systems have been an avenue of considerable interest in terms of their immense potential for better pharmacotherapeutic interventions along with site-specific absorption. These buoyant systems significantly enhance the bioavailability and controlled delivery of several drug molecules. Scientific investigators have also carried out substantial research endeavours worldwide in order to design a more systematic and intellectual floating systems. The present manuscript is an attempt to highlight numerous recent advancements in the design of gastric floating drug delivery systems along with various available commercial preparations. Salient applications, characterization aspects and future perspectives of these multifarious systems have also been addressed. PMID:23808593

Pahwa, Rakesh; Bisht, Seema; Kumar, Vipin; Kohli, Kanchan

2013-06-01

436

Float level switch for a nuclear power plant containment vessel  

DOEpatents

This invention is a float level switch used to sense rise or drop in water level in a containment vessel of a nuclear power plant during a loss of coolant accident. The essential components of the device are a guide tube, a reed switch inside the guide tube, a float containing a magnetic portion that activates a reed switch, and metal-sheathed, ceramic-insulated conductors connecting the reed switch to a monitoring system outside the containment vessel. Special materials and special sealing techniques prevent failure of components and allow the float level switch to be connected to a monitoring system outside the containment vessel. 1 figures.

Powell, J.G.

1993-11-16

437

Altimeter and Argo float data assimilation in the Black Sea  

NASA Astrophysics Data System (ADS)

We analyse the thermo-haline characteristics in the Black Sea during the period 2002-2009 derived from numerical model simulations assimilating different observation data with the aim to improve the model skills. The Nucleus of European Modelling of the Ocean (NEMO) framework is used. In the experiment OI-1 we assimilate satellite altimetry and AVHRR data. In the experiment OI-2 we add also in-situ measurements from ARGO floats. Data assimilation uses the SESAM code and an optimal interpolation approach based on the static covariance matrix derived from the preliminary free model run, which converters the observations into basin temperature and salinity fields. Main attention in the analysis of simulations is been paid to the dominating characteristics of physical fields at seasonal and inter-annual time scales. Empirical orthogonal function (EOF) analysis of steric heights from simulations and their consistence with the ones from satellite altimetry is used to analyse the general characteristics in the thermo-haline signals. Results indicate that the free model run reproduces reasonably well the seasonal variability of Rim Current and the cold intermediate water mass formation. The assimilation of remote sensing observations only (OI-1) improves significantly the dynamics of steric heights, in particular as seen in the analysis of higher degree EOF-modes. However, in this experiment the simulation of profiles needs an improvement. This improvement is ensured by the assimilation of ARGO profiles in OI-2. However, because in the Black Sea ARGO measurements are sparse the benefit of their assimilation has to be considered carefully and is done by an objective analysis on model skills in the entire basin.

Grayek, Sebastian; Stanev, Emil; Schulz-Stellenfleth, Johannes

2010-05-01

438

Designs and applications for floating-hydro power systems in small streams  

Microsoft Academic Search

The project focuses on an appropriate technology for small-scale hydro power: floating waterwheels and turbines. For background, relic and existing systems such as early floating mills, traditional Amish waterwheels, and micro-hydro systems are examined. In the design phase of the project, new designs for Floating Hydro Power Systems include: an analysis of floatation materials and systems; a floating undershot waterwheel

Rehder

1983-01-01

439

Mucoadhesive Microparticles in a Rapidly Dissolving Tablet for Sustained Drug Delivery to the Eye  

PubMed Central

Purpose. To test the hypothesis that mucoadhesive microparticles formulated in a rapidly dissolving tablet can achieve sustained drug delivery to the eye. Methods. Mucoadhesive microparticles, smaller than 5 ?m were fabricated with poly(lactic-co-glycolic acid) and poly(ethylene glycol) as a core material and mucoadhesion promoter, respectively, and encapsulated pilocarpine as a model drug. These microparticles were embedded in a poly(vinyl alcohol) matrix to form a dry tablet designed to reduce rapid clearance of the microparticles on initial application to the eye. Results. This in vitro drug release study exhibited that for all formulations, approximately 90% of pilocarpine was released during the first 10 minutes, and the remaining 10% was released slowly for 3 hours. In vivo mucoadhesion test on the rabbit eye indicated that mucoadhesive microparticles adhered significantly better to the preocular surface than other formulations. To assess the pharmacodynamics, the most prolonged pilocarpine-induced pupil constriction was observed in rabbit eyes in vivo using a tablet with mucoadhesive microparticles; it lasted up to 330 minutes. Conclusions. The authors conclude that mucoadhesive microparticles formulated into a dry dosage form is a promising system for sustained drug delivery to the eye.

Choy, Young Bin; Patel, Samirkumar R.; Park, Jung-Hwan; McCarey, Bernard E.; Edelhauser, Henry F.

2011-01-01

440

Pfizer Announces Voluntary Nationwide Recall of Lo/Ovral-28 and Norgestrel/Ethinyl Estradiol Tablets Due to Possibility of Inexact Tablet Counts or Out of Sequence Tablets  

NASA Website

Pfizer Inc. announced today that it has voluntarily recalled 14 lots of Lo/Ovral-28 (norgestrel and ethinyl estradiol)Tablets and 14 lots of Norgestrel and Ethinyl Estradiol Tablets (generic)for customers in the U.S. market.

441

Simulation of quantum dot floating gate MOSFET memory performance using various high-k material as tunnel oxide  

NASA Astrophysics Data System (ADS)

In this paper, performance of quantum dot floating gate MOSFET memory is simulated by replacing the SiO2 tunnel oxide with high-? material. There are three high-k material simulated in this paper, HfO2, ZrO2, and Y2O3. As we know that high-? material is used nowadays to reduce leakage current, so this paper demonstrates the application of high-? material to reduce leakage current in non-volatile memory quantum dot based floating gate MOSFET. Simulation results of this paper show the leakage current can be suppressed by using high-? material as tunnel oxide up to 10 times. Furthermore, this paper also shows that the memory performance can be properly sustained. The writing and erasing time are depend on tunneling current probability which calculated using transfer matrix method. The writing time and erasing time for HfO2 and ZrO2 are 150 nanosecond and 15 nanosecond.

Aji, Adha Sukma; Darma, Yudi

2012-06-01

442

Biocidal efficacy of a flocculating emergency water purification tablet.  

PubMed

Chlor-Floc (CF) emergency water purification tablets were tested for bactericidal, virucidal, and cysticidal efficacy in water at temperatures ranging from 5 to 25 degrees C. The minimal required log reduction was achieved for bacteria, Giardia muris, and rotavirus, but CF did not achieve the required log reduction of poliovirus at any of the temperatures or times investigated. The biocidal properties of the CF tablet were equivalent to if not greater than those of the Globaline iodine tablet, and the CF tablet was a more rapid cysticide under several potential use conditions. Therefore, it is a suitable substitute for iodine tablets for emergency purification of drinking water. Clarification of turbid waters was effective, but filtration through a cloth is necessary to prevent flocculated sediment from entering the canteen. The CF tablets met military requirements for emergency water purification and are safe and acceptable for use by the military. PMID:16349318

Powers, E M; Hernandez, C; Boutros, S N; Harper, B G

1994-07-01

443

5. GENERAL VIEW LOOKING NORTHWEST. FENDER PREVENTS FLOATING DEBRIS FROM ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

5. GENERAL VIEW LOOKING NORTHWEST. FENDER PREVENTS FLOATING DEBRIS FROM DAMAGING TRUSSES DURING PERIODS OF HIGH WATER. - Ohio & Erie Canal, Tinker's Creek Aqueduct, Canal Road, South Tinkers Creek Road, Valley View, Cuyahoga County, OH

444

36. FLOAT WELL AND PIPE ENCASEMENT EAST CUTOFF WALL, ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

36. FLOAT WELL AND PIPE ENCASEMENT - EAST CUTOFF WALL, REINFORCEMENT DETAILS. Sheet A-17, October, 1940. File no. SA 342/2. - Prado Dam, Outlet Works, Santa Ana River near junction of State Highways 71 & 91, Corona, Riverside County, CA

445

Analog-to-Digital Converter with Programmable Floating Gate.  

National Technical Information Service (NTIS)

Systems and methods are discussed for using a floating-gate MOSFET as a programmable reference circuit. One example of the programmable reference circuit is a programmable voltage reference source, while a second example of a programmable reference circui...

2006-01-01

446

Digital-to-Analog Converter with Programmable Floating Gate.  

National Technical Information Service (NTIS)

Systems and methods are discussed for using a floating-gate MOSFET as a programmable reference circuit. One example of the programmable reference circuit is a programmable voltage reference source, while a second example of a programmable reference circui...

G. J. Serrano M. R. Kucic P. E. Hasler

2006-01-01

447

14 CFR 29.521 - Float landing conditions.  

Code of Federal Regulations, 2013 CFR

...TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Strength Requirements Water Loads § 29.521 Float landing conditions...the static level attitude, the resultant water reaction passes vertically through the...

2013-01-01

448

Coupled Dynamic Modeling of Floating Wind Turbine Systems.  

National Technical Information Service (NTIS)

This article presents a collaborative research program that the Massachusetts Institute of Technology (MIT) and the National Renewable Energy Laboratory (NREL) have undertaken to develop innovative and cost-effective floating and mooring systems for offsh...

E. N. Wayman P. D. Sclavounos

2006-01-01

449

40. VAL CONNECTING BRIDGE AND BARGES FLOATING ON RESERVOIR (PREVIOUSLY ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

40. VAL CONNECTING BRIDGE AND BARGES FLOATING ON RESERVOIR (PREVIOUSLY SUPPORTED MUZZLE END OF LAUNCHER BRIDGE). - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

450

16. EAST ELEVATION OF FLOAT HOUSE AND FISH WATER RELEASE ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

16. EAST ELEVATION OF FLOAT HOUSE AND FISH WATER RELEASE OUTLET. PART OF ENERGY DISSIPATING BAFFLE PIER SYSTEM IS VISIBLE AT LEFT. - Pit 4 Diversion Dam, Pit River west of State Highway 89, Big Bend, Shasta County, CA

451

Ultra-low-voltage floating-gate transconductance amplifiers  

Microsoft Academic Search

Ultra-low-voltage (ULV) floating-gate differential amplifiers are presented. In this paper, we present several different approaches to CMOS ULV amplifier design. Sinh-shaped and tanh-shaped transconductance amplifiers are described. Measured results are provided

YNGVAR BERG; TOR S. LANDE; O. Naess; Henning Gundersen

2001-01-01

452

Can Heavier Liquid Float on Top of a Lighter One?  

NASA Astrophysics Data System (ADS)

We report on a first observation of a floating spherical Hg (density 13 g/cm3) drop on top of a glycerin (density 1.26 g/cm3) drop, the latter is hemispherical and about four times larger in volume. This observation is clearly against nature's gravity law and has never been reported before. Here we present spectacular high resolution photos that clearly demonstrate this remarkable floating phenomenon. Using milli-Q water, the Hg drop would stay down adhered at the triple line. Instead, the coincidental use of tap water displays the same phenomenon. Increasing the volume of the supporting liquid to a certain value causes the Hg drop to sink. A 5-M NaCl aqueous solution is found enough to show the same floating phenomenon. This floating mercury as a phenomenon is puzzling. On this length scale it seems that surface tension and curvature dominate over gravity.

Ayyad, A. H.; Takrori, F.

2011-01-01

453

31. Floating original Ship Canal draw (in background) to University ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

31. Floating original Ship Canal draw (in background) to University Heights location. New Ship Canal draw in foreground. June 1906 photograph. - University Heights Bridge, Spanning Harlem River at 207th Street & West Harlem Road, New York, New York County, NY

454

Bowling Balls: Will they Sink or Will they Float?  

NSDL National Science Digital Library

Students investigate whether a bowling ball will float or sink in an aquarium of water after measuring the ball and determining the density. This is meant to be an investigative inquiry of the concepts of density and significant figures.

455

Thermal Marangoni Convection in a Floating Zone (TEXUS 3).  

National Technical Information Service (NTIS)

The Technological Experiments Under Microgravity (TEXUS) 3 Experiment to observe thermally induced Marangoni convection under microgravity conditions is summarized. A floating zone of silicone oil (10 mm high and 10 mm in diameter) was formed under microg...

C. Chun W. Wuest

1991-01-01

456

78 FR 1247 - Certain Electronic Devices, Including Wireless Communication Devices, Tablet Computers, Media...  

Federal Register 2010, 2011, 2012, 2013

...Tablet Computers, Media Players, and Televisions, and Components Thereof; Institution...tablet computers, media players, and televisions, and components thereof by reason of...tablet computers, media players, and televisions, and components thereof that...

2013-01-08

457

Blister Sheet and Pouch Overwrapper Package for the Iodine Water Purification Tablet.  

National Technical Information Service (NTIS)

The development and pilot production of a blister sheet and pouch overwrapper package for the iodine water purification tablet is described. The blister sheets are fabricated from a fluorohalocarbon film containing 12 tablets with each tablet isolated by ...

C. T. Derick D. F. Brown

1971-01-01

458

75 FR 61503 - Determination That AZDONE (Hydrocodone Bitartrate and Aspirin) Tablet, 5 Milligrams/500...  

Federal Register 2010, 2011, 2012, 2013

...That AZDONE (Hydrocodone Bitartrate and Aspirin) Tablet, 5 Milligrams/500 Milligrams...that AZDONE (hydrocodone bitartrate and aspirin) Tablet, 5 milligrams (mg)/ 500 mg...ANDAs) for hydrocodone bitartrate and aspirin tablet, 5 mg/500 mg, if all...

2010-10-05

459

77 FR 34063 - Certain Electronic Devices, Including Mobile Phones and Tablet Computers, and Components Thereof...  

Federal Register 2010, 2011, 2012, 2013

...Electronic Devices, Including Mobile Phones and Tablet Computers, and Components...electronic devices, including mobile phones and tablet computers, and components...electronics devices, including mobile phones and tablet computers, and...

2012-06-08

460

77 FR 27078 - Certain Electronic Devices, Including Mobile Phones and Tablet Computers, and Components Thereof...  

Federal Register 2010, 2011, 2012, 2013

...Electronic Devices, Including Mobile Phones and Tablet Computers, and Components...Electronic Devices, Including Mobile Phones and Tablet Computers, and Components...electronic devices, including mobile phones and tablet computers, and...

2012-05-08

461

78 FR 40171 - Certain Wireless Devices, Including Mobile Phones and Tablets; Notice Of Receipt of Complaint...  

Federal Register 2010, 2011, 2012, 2013

...Certain Wireless Devices, Including Mobile Phones and Tablets; Notice Of Receipt...Certain Wireless Devices, Including Mobile Phones and Tablets, DN 2964; the Commission...certain wireless devices, including mobile phones and tablets. The complaint...

2013-07-03

462

78 FR 47410 - Certain Wireless Devices, Including Mobile Phones and Tablets Institution of Investigation  

Federal Register 2010, 2011, 2012, 2013

...Certain Wireless Devices, Including Mobile Phones and Tablets Institution of Investigation...certain wireless devices, including mobile phones and tablets by reason of infringement...certain wireless devices, including mobile phones and tablets by reason of...

2013-08-05