21 CFR 184.1763 - Sodium hydroxide.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Sodium hydroxide. 184.1763 Section 184.1763 Food... Specific Substances Affirmed as GRAS § 184.1763 Sodium hydroxide. (a) Sodium hydroxide (NaOH, CAS Reg. No. 1310-73-2) is also known as sodium hydrate, soda lye, caustic soda, white caustic, and lye. The...

Patterns of streamwater acidity in Lye Brook Wilderness, Vermont, USA

Treesearch

John L. Campbell; Christopher Eagar; William H. McDowell

2002-01-01

Under the United States Clean Air Act Amendments of 1977, a class I designation safeguards wilderness areas from the negative effects of new sources of air pollution. We monitored streamwater chemistry in the class I Lye Brook Wilderness in southwestern Vermont from May 1994 through August 1995. Stream samples were collected biweekly at nine sampling locations...

21 CFR 184.1763 - Sodium hydroxide.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Sodium hydroxide. 184.1763 Section 184.1763 Food... GRAS § 184.1763 Sodium hydroxide. (a) Sodium hydroxide (NaOH, CAS Reg. No. 1310-73-2) is also known as sodium hydrate, soda lye, caustic soda, white caustic, and lye. The empirical formula is NaOH. Sodium...

Analysis of nitrogen dynamics in the Lye Brook Wilderness Area, Vermont, USA

Treesearch

John L. Campbell; Christopher Eagar; William H. McDowell; James W. Hornbeck

2000-01-01

Nitrogen (N) deposition and its impact on terrestrial and aquatic ecosystems is a concern facing federal land managers at the Lye Brook Wilderness in Vermont and other protected areas throughout the northeastern United States. In this study, we compared N production in soils with N concentrations and outputs in leachates to determine how forest cover types differ in...

Prevalence of Eosinophilic Esophagitis and Lymphocytic Esophagitis in Adults with Esophageal Food Bolus Impaction.

PubMed

Truskaite, Kotryna; Dlugosz, Aldona

2016-01-01

Background. The relation of esophageal food bolus impaction (FBI) to eosinophilic esophagitis (EoE) and lymphocytic esophagitis (LyE) is unclear. The aim of this study was to determine the prevalence of EoE and LyE among adults with FBI. Methods. In this retrospective study we analyzed data from all patients referred for gastroscopy during the past 5 years, because of a present or recent episode of FBI. Results. We found 238 patients with FBI (median age 51 (17-96), 71% males). Endoscopic therapy was required in 143 patients. Esophageal biopsies were obtained in 185 (78%) patients. All biopsies were assessed for numbers of eosinophils and lymphocytes. EoE was found in 18% of patients who underwent biopsy. We found 41 patients (22%) who fulfilled the criteria for both EoE and LyE (EoE/LyE). LyE was found in the 9% of patients with FBI. EoE together with EoE/LyE was the leading cause of FBI in patients ≤50 years (64%). GERD was the leading cause of FBI among patients older than 50 years (42%). Conclusions. Our study showed that EoE was the leading cause of FBI in particular among young adults. Our study highlights the need for esophageal biopsies in any patient with FBI.

Supervised resistance training results in changes in postural control in patients with multiple sclerosis.

PubMed

Huisinga, Jessie M; Filipi, Mary L; Stergiou, Nicholas

2012-01-01

Postural disturbances are one of the first reported symptoms in patients with Multiple Sclerosis (MS). The purpose of this study was to investigate the effect of supervised resistance training on postural control in MS patients. Postural control was assessed using amount of sway variability [Root Mean Square (RMS)] and temporal structure of sway variability [Lyapunov Exponent (LyE)] from 15 MS patients. Posture was evaluated before and after completion of three months of resistance training. There were significant differences between MS patients pretraining and healthy controls for both LyE (p = .000) and RMS (p = .002), but no differences between groups after training. There was a significant decrease in RMS (p = .025) and a significant increase in LyE (p = .049) for MS patients pre- to posttraining. The findings suggested that postural control of MS patients could be affected by a supervised resistance training intervention.

[Complex case with respiratory, endocrine and digestive manifestations--late complications after a colic replacement of the esophagus for lye ingestion].

PubMed

Bolca, Ciprian; Tănăsescu, Mihaela; Dănăilă, Olga; Paleru, Cristian; Cordoş, Ioan

2014-01-01

Long term complications after colic replacement of the esophagus are well known and their managment is known as being difficult, due to multiple associated comorbidities; we present the case of a 26-year-old patient with multiple late complications after a coloesophagoplaty for lye ingestion during childhood. The patient finally died despite all the eforts of treatement during a prolonged hospitalisation. We will try to analyse the key moments on patient's evolution and discuss other possible options in this case.

Level II scour analysis for Bridge 24 (MANCUS00070024) on U.S. Route 7, crossing Lye Brook, Manchester, Vermont

USGS Publications Warehouse

Olson, Scott A.

1997-01-01

This report provides the results of a detailed Level II analysis of scour potential at structure MANCUS00070024 on U.S. Route 7 crossing Lye Brook, Manchester, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of a Level I scour investigation also are included in Appendix E of this report. A Level I investigation provides a qualitative geomorphic characterization of the study site. Information on the bridge, gleaned from Vermont Agency of Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is found in Appendix D. The site is in the Taconic section of the New England physiographic province in southwestern Vermont. The 8.13-mi2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the primary surface cover consists of brush and trees. In the study area, Lye Brook has an incised, sinuous channel with a slope of approximately 0.03 ft/ft, an average channel top width of 66 ft and an average bank height of 11 ft. The channel bed material ranges from gravel to boulder with a median grain size (D50) of 90.0 mm (0.295 ft). The geomorphic assessment at the time of the Level I and Level II site visit on August 6, 1996, indicated that the reach was stable. Although, the immediate reach is considered stable, upstream of the bridge the Lye Brook valley is very steep (0.05 ft/ft). Extreme events in a valley this steep may quickly reveal the instability of the channel. In the Flood Insurance Study for the Town of Manchester (Federal Emergency Management Agency, January, 1985), Lye Brook’s overbanks were described as “boulder strewn” after the August 1976 flood. The U.S. Route 7 crossing of Lye Brook is a 28-ft-long, two-lane bridge consisting of one 25-foot concrete span (Vermont Agency of Transportation, written communication, September 28, 1995). The bridge is supported by vertical, concrete abutments with wingwalls. The channel is skewed approximately 45 degrees to the opening while the opening-skew-to-roadway is 55 degrees. At the time of construction, the downstream channel was relocated (written communication, Dan Landry, VTAOT, January 2, 1997). A levee on the downstream right bank was also constructed and is protected by type-4 stone-fill (less than 60 inches diameter) extending from the bridge to more than 300 feet downstream. Type-2 stone fill (less than 36 inches diameter) covers the downstream right bank from the bridge to more than 300 feet downstream. Type-2 stone-fill also extends from the bridge to 220 feet upstream on both upstream banks. Additional details describing conditions at the site are included in the Level II Summary and Appendices D and E. Scour depths and recommended rock rip-rap sizes were computed using the general guidelines described in Hydraulic Engineering Circular 18 (Richardson and others, 1995) for the 100- and 500-year discharges. In addition, the incipient roadway-overtopping discharge is analyzed since it has the potential of being the worst-case scour scenario. Total scour at a highway crossing is comprised of three components: 1) long-term streambed degradation; 2) contraction scour (due to accelerated flow caused by a reduction in flow area at a bridge) and; 3) local scour (caused by accelerated flow around piers and abutments). Total scour is the sum of the three components. Equations are available to compute depths for contraction and local scour and a summary of the results of these computations follows. Contraction scour for all modelled flows ranged from 1.0 to 1.6 ft. The worst-case contraction scour occurred at the 500-year discharge. Abutment scour computations for the left abutment ranged from 14.5 to 16.1 ft. with the worst-case occurring at the 100-year discharge. Abutment scour computations for the right abutment ranged from 6.9 to 10.4 ft. with the worst-case occurring at the 500-year discharge. Additional information on scour depths and depths to armoring are included in the section titled “Scour Results”. Scoured-streambed elevations, based on the calculated scour depths, are presented in tables 1 and 2. A cross-section of the scour computed at the bridge is presented in figure 8. Scour depths were calculated assuming an infinite depth of erosive material and a homogeneous particle-size distribution. It is generally accepted that the Froehlich equation (abutment scour) gives “excessively conservative estimates of scour depths” (Richardson and others, 1995, p. 47). Usually, computed scour depths are evaluated in combination with other information including (but not limited to) historical performance during flood events, the geomorphic stability assessment, existing scour protection measures, and the results of the hydraulic analyses. Therefore, scour depths adopted by VTAOT may differ from the computed values documented herein.

Development of a neutral embedding resin for optical imaging of fluorescently labeled biological tissue

NASA Astrophysics Data System (ADS)

Zhou, Hongfu; Gang, Yadong; Chen, Shenghua; Wang, Yu; Xiong, Yumiao; Li, Longhui; Yin, Fangfang; Liu, Yue; Liu, Xiuli; Zeng, Shaoqun

2017-10-01

Plastic embedding is widely applied in light microscopy analyses. Previous studies have shown that embedding agents and related techniques can greatly affect the quality of biological tissue embedding and fluorescent imaging. Specifically, it is difficult to preserve endogenous fluorescence using currently available acidic commercial embedding resins and related embedding techniques directly. Here, we developed a neutral embedding resin that improved the green fluorescent protein (GFP), yellow fluorescent protein (YFP), and DsRed fluorescent intensity without adjusting the pH value of monomers or reactivating fluorescence in lye. The embedding resin had a high degree of polymerization, and its fluorescence preservation ratios for GFP, YFP, and DsRed were 126.5%, 155.8%, and 218.4%, respectively.

Effect of the processing steps on compositions of table olive since harvesting time to pasteurization.

PubMed

Nikzad, Nasim; Sahari, Mohammad A; Vanak, Zahra Piravi; Safafar, Hamed; Boland-nazar, Seyed A

2013-08-01

Weight, oil, fatty acids, tocopherol, polyphenol, and sterol properties of 5 olive cultivars (Zard, Fishomi, Ascolana, Amigdalolia, and Conservalia) during crude, lye treatment, washing, fermentation, and pasteurization steps were studied. Results showed: oil percent was higher and lower in Ascolana (crude step) and in Fishomi (pasteurization step), respectively; during processing steps, in all cultivars, oleic, palmitic, linoleic, and stearic acids were higher; the highest changes in saturated and unsaturated fatty acids were in fermentation step; the highest and the lowest ratios of ω3 / ω6 were in Ascolana (washing step) and in Zard (pasteurization step), respectively; the highest and the lowest tocopherol were in Amigdalolia and Fishomi, respectively, and major damage occurred in lye step; the highest and the lowest polyphenols were in Ascolana (crude step) and in Zard and Ascolana (pasteurization step), respectively; the major damage among cultivars occurred during lye step, in which the polyphenol reduced to 1/10 of first content; sterol did not undergo changes during steps. Reviewing of olive patents shows that many compositions of fruits such as oil quality, fatty acids, quantity and its fraction can be changed by alteration in cultivar and process.

Liotrix

MedlinePlus

(lye' oh trix)Statement from Forest Laboratories Re: Availability of Thyrolar:[Posted 5/18/2012] U.S. Pharmacopeia, ... condition, and check for future updates on the availability of Thyrolar through the Forest product availability toll- ...

Sodium hydroxide poisoning

MedlinePlus

Sodium hydroxide is a very strong chemical. It is also known as lye and caustic soda. This ... poisoning from touching, breathing in (inhaling), or swallowing sodium hydroxide. This article is for information only. Do ...

In vitro characterization of the effectiveness of enhanced sewage treatment processes to eliminate endocrine activity of hospital effluents.

PubMed

Maletz, Sibylle; Floehr, Tilman; Beier, Silvio; Klümper, Claudia; Brouwer, Abraham; Behnisch, Peter; Higley, Eric; Giesy, John P; Hecker, Markus; Gebhardt, Wilhelm; Linnemann, Volker; Pinnekamp, Johannes; Hollert, Henner

2013-03-15

Occurrence of pharmaceuticals in aquatic ecosystems is related to sewage effluents. Due to the possible adverse effects on wildlife and humans, degradation and removal of pharmaceuticals and their metabolites during wastewater treatment is an increasingly important task. The present study was part of a proof of concept study at a medium sized country hospital in western Germany that investigated efficiency of advanced treatment processes to remove toxic potencies from sewage. Specifically, the efficiency of treatment processes such as a membrane bioreactor (MBR) and ozonation to remove endocrine disruptive potentials was assessed. Estrogenic effects were characterized by use of two receptor-mediated in vitro transactivation assays, the Lyticase Yeast Estrogen Screen (LYES) and the Estrogen Receptor mediated Chemical Activated LUciferase gene eXpression (ER CALUX(®)). In addition, the H295R Steroidogenesis Assay (H295R) was utilized to detect potential disruption of steroidogenesis. Raw sewage contained measurable estrogen receptor (ER)-mediated potency as determined by use of the LYES (28.9 ± 8.6 ng/L, 0.33× concentration), which was reduced after treatment by MBR (2.3 ± 0.3 ng/L) and ozone (1.2 ± 0.4 ng/L). Results were confirmed by use of ER CALUX(®) which measured concentrations of estrogen equivalents (EEQs) of 0.2 ± 0.11 ng/L (MBR) and 0.01 ± 0.02 ng/L (ozonation). In contrast, treatment with ozone resulted in greater production of estradiol and aromatase activity at 3× and greater concentrations in H295R cells. It is hypothesized that this is partly due to formation of active oxidized products during ozonation. Substance-specific analyses demonstrated efficient removal of most of the measured compounds by ozonation. A comparison of the ER-mediated responses measured by use of the LYES and ER CALUX(®) with those from the chemical analysis using a mass-balance approach revealed estrone (E1) to be the main compound that caused the estrogenic effects. Overall, treatment of sewage by use of MBR successfully reduced estrogenicity of hospital effluents as well as substances that are able to alter sex steroid production. However, after ozonation, effluents should undergo further investigations regarding the formation of endocrine active metabolites. The results obtained as part of this study demonstrated applicability of in vitro assays for monitoring of endocrine-modulating potency of treated sewage. Copyright © 2012 Elsevier Ltd. All rights reserved.

Investigation of potential endocrine disrupting effects of mosquito larvicidal Bacillus thuringiensis israelensis (Bti) formulations.

PubMed

Maletz, Sibylle; Wollenweber, Marc; Kubiak, Katharina; Müller, Annett; Schmitz, Stefan; Maier, Dieter; Hecker, Markus; Hollert, Henner

2015-12-01

Bti is successfully used as a biological control agent for mosquito control. It has proven to be ecological friendly, and thus, is used in ecologically sensitive habitats. Recent investigations of groundwater in Germany have detected estrogenic activity in five consecutive groundwater wells in a region where Bti is applied. Therefore, it was suspected that this compound can act as an environmental xenoestrogen. In the present study, five Bti formulations as well as the active ingredient, VectoBac® TP (TP), were investigated regarding their estrogenic activity using the LYES and ER CALUX® assays. Furthermore, their steroidogenesis disruption properties were studied using the H295R Steroidogenesis Assay. Additionally, field samples from a Bti application area as well as samples from an artificial pond were examined. Three of the Bti formulations and the active ingredient TP showed significant estrogenic activity in the LYES (up to 52 ng·l(-1) estradiol equivalents (EEQ) in the 18-fold concentration) and/or the ER CALUX® (up to 1 ng·EEQ·l(-1) in the 18-fold concentration). In the H295R significant but weak effects with no dose-response-relationship on the production of estradiol, and 21-hydroxyprogesterone (WDG) as well as testosterone (TP) by H295R cells could be observed. The field samples as well as the samples from the artificial pond showed no significant increase of estrogenic activity after application of TP or WDG in the ER CALUX®. With the exception of the controlled laboratory experiments with direct application of Bti to the utilized in vitro test systems the present study did not reveal any significant effects of Bti on endocrine functions that would indicate that the application of Bti could cause adverse endocrine effects to organisms in aquatic ecosystems. Instead, our results support previous studies that the use of Bti products against mosquitos would be safe even for sensitive habitats such as conservation areas. Copyright © 2015 Elsevier B.V. All rights reserved.

Development of Infrared Radiation Heating Method for Sustainable Tomato Peeling

USDA-ARS?s Scientific Manuscript database

Although lye peeling is the widely industrialized method for producing high quality peeled fruit and vegetable products, the peeling method has resulted in negative impacts by significantly exerting both environmental and economic pressure on the tomato processing industry due to its associated sali...

Development of infrared heating technology for tomato peeling

USDA-ARS?s Scientific Manuscript database

The commercial lye and steam peeling methods used in tomato processing industry are water- and energy-intensive and have a negative impact on the environment. To develop alternative peeling methods, we conducted comprehensive studies of using infrared (IR) heating for tomato peeling. The three major...

Installation Restoration Program Records Search for Alaska DEW Line Stations

DTIC Science & Technology

1982-06-01

Chlorinate hydrocarbons Radar components Calgon corrosion inhibitor 55 gallon drums (empty) Lye Lime Corrosives Antifreeze Paper Wood Plastics AVGAS...Factor Subsoare A I Persistence Vcor * Subaccro a C. Appl~y "yicaJ. state =iLtipiisr Sub•coce 3 X Physical State Mltipler - Waste Caracteristics

Effects of infrared radiation heating on peeling performance and quality attributes of clingstone peaches

USDA-ARS?s Scientific Manuscript database

Salinity and wastewater disposal problems associated with the conventional wet-lye method for peeling clingstone peaches result in considerable negative environment impacts. This study investigated the efficacy of using infrared (IR) heating as an alternative method for peach peel removal without us...

Predictive modeling of infrared radiative heating in tomato dry-peeling process: Part I. Model development

USDA-ARS?s Scientific Manuscript database

Infrared (IR) dry-peeling has emerged as an effective non-chemical alternative to conventional lye and steam methods of peeling tomatoes. Successful peel separation induced by IR radiation requires the delivery of a sufficient amount of thermal energy onto tomato surface in a very short duration. Th...

77 FR 11798 - Approval and Promulgation of Air Quality Implementation Plans; Rhode Island; Regional Haze

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-28

...; and Lye Brook Wilderness Area in Vermont. Through source apportionment modeling, MANE-VU assisted... sources and activities which are located across a broad geographic area and emit fine particles and their...., sulfates, nitrates, organic carbon, elemental carbon, and soil dust), which also impair visibility by...

Evaluation of Military Field-Water Quality. Volume 3. Opportunity Poisons

DTIC Science & Technology

1987-12-01

Acidic chemical cleaners fluoric acid, nitric acid, perchloric Spent acid acid, sulfuric acid Alkalies Miscellaneous caustic products Ammonia, lime...calcium oxide), potassium Alkaline battery fluid hydroxide, sodium hydroxide, sodium Caustic wastewater silicate Cleaning solutions Lye Nonhalogenated...Laboratory chemicals chloride, polychlorinated biphenyls, zinc Paint and varnish removers naphthenate , copper naphthenate , dichloro- Capacitors and

Demonstration tests of infrared peeling system with electrical emitters for tomatoes

USDA-ARS?s Scientific Manuscript database

Infrared (IR) dry-peeling is an emerging technology that could avoid the drawbacks of steam and lye peeling of tomatoes. The objectives of this research was to evaluate the performance of an IR peeling system at two tomato processing plants located in California and to compare product quality, peela...

Child maltreatment and neglect, or poverty and ignorance: An old case from the museum.

PubMed

Nikolić, Slobodan; Živković, Vladimir

2016-04-01

We present an old case, from the year 1928, of a girl who, as an 18-month-old, had ingested a small amount of lye, and over time oesophageal stenosis had developed. However, her parents had not taken her to hospital until 4 months after the event, after an episode of bloody vomiting. She spent the remaining time of her life in the hospital, where she died as a 3-year-old. Her parents did not visit once during that time. After the autopsy, the opinion about the cause and mechanism of death had five steps: the immediate cause of death was purulent pneumonia, which was a complication of small pox and severe undernourishment; the severe undernourishment was the consequence of a narrowed part of the oesophagus; this developed due to the ingestion of the corrosive agent; and it remained uncertain whether the ingestion of the corrosive agent was accidental or homicidal in manner. The presented case could be an example of possible child maltreatment and neglect in rural parts of society, from almost 90 year ago; at the time these cases were not recognized and treated as they would be today. This is also an example of how the forensic pathologist, via the conclusion about the cause of death, highlighted the parents' carelessness and neglect of the child. © The Author(s) 2015.

Comprehension Monitoring by Elementary Students: When Does It Occur?

ERIC Educational Resources Information Center

Pace, Ann Jaffe

The effect of passage topic and task demands on elementary school students' monitoring of their own comprehension was examined. Second, fourth, and sixth grade students read a short passage about a well-known event (playing checkers) or one about which they had little existing information (making lye soap). Half of the students in each grade were…

Air pollution indications and growth of spruce and pine near a sulfite plant

Treesearch

Lars Westman

1976-01-01

A preliminary study has been made around a sulfite plant in the north of Sweden. The emission of sulfur dioxide increased considerably in 1950 as a consequence of the introduction of lye-burning. Using the pH in pine bark and two common lichen epiphytes as indicators, the resistant Parmelia physodes and the very sensitive Alectoria implexa...

Variations on the "Blue-Bottle" Demonstration Using Food Items That Contain FD&C Blue #1

ERIC Educational Resources Information Center

Staiger, Felicia A.; Peterson, Joshua P.; Campbell, Dean J.

2015-01-01

Erioglaucine dye (FD&C Blue #1) can be used instead of methylene blue in the classic "blue-bottle" demonstration. Food items containing FD&C Blue #1 and reducing species such as sugars can therefore be used at the heart of this demonstration, which simply requires the addition of strong base such as sodium hydroxide lye.

Influence of chemical straightening on the stability of drugs of abuse in hair.

PubMed

Pritchett, Jeanita S; Phinney, Karen W

2015-01-01

Chemical straightening, also known as a relaxer, is ubiquitously used among African American women to obtain straighter hair compared with their natural tresses. This study focused on the stability of drugs of abuse in hair after a single application of the relaxer. Commercially available 'Lye' or 'No-Lye' chemical straightening products (Silk Elements™) were applied in vitro to drug-fortified hair (standard reference materials (SRM) 2379 and 2380) and hairs clipped from established drug users. Target analytes (cocaine (COC), benzoylecgonine (BZE), cocaethylene (CE), phencyclidine and tetrahydrocannabinol) were isolated using solid-phase extraction and then analyzed with isotope dilution gas chromatography-mass spectrometry with selective ion monitoring. After either treatment, drug concentrations were significantly (P < 0.05) decreased in both the SRM sample and the hair from authentic abusers. In the SRM groups, 6-67% of the original concentration remained after a single chemical treatment. Similarly, only 5-30% of the original concentration remained in authentic drug hairs that had formerly tested positive for COC, BZE and CE. Published by Oxford University Press 2014. This work is written by (a) US Government employee(s) and is in the public domain in the US.

9 CFR 95.26 - Railroad cars, trucks, boats, aircraft and other means of conveyance, equipment or containers...

Code of Federal Regulations, 2014 CFR

2014-01-01

... proportion of 1 pound to 3 gallons of water. (2) Sodium carbonate (4 percent) plus sodium silicate (0.1 percent) in the proportion of 1 pound of sodium carbonate plus sodium silicate to 3 gallons of water. (3) Sodium hydroxide (Lye) prepared in a fresh solution in the proportion of not less than 1 pound...

9 CFR 96.10 - Uncertified casings; transportation for disinfection; original shipping containers; disposition...

Code of Federal Regulations, 2011 CFR

2011-01-01

... hydroxide (Lye) prepared in a fresh solution in the proportion of not less than 1 pound avoirdupois of... in case any of the sodium hydroxide solution should come in contact with the body. (2) This solution...) Dissolve the salt in the proportion of 90 pounds of salt to 100 gallons of water. Add 23/4 gallons of C. P...

9 CFR 96.10 - Uncertified casings; transportation for disinfection; original shipping containers; disposition...

Code of Federal Regulations, 2014 CFR

2014-01-01

... hydroxide (Lye) prepared in a fresh solution in the proportion of not less than 1 pound avoirdupois of... in case any of the sodium hydroxide solution should come in contact with the body. (2) This solution...) Dissolve the salt in the proportion of 90 pounds of salt to 100 gallons of water. Add 23/4 gallons of C. P...

9 CFR 95.26 - Railroad cars, trucks, boats, aircraft and other means of conveyance, equipment or containers...

Code of Federal Regulations, 2012 CFR

2012-01-01

... proportion of 1 pound to 3 gallons of water. (2) Sodium carbonate (4 percent) plus sodium silicate (0.1 percent) in the proportion of 1 pound of sodium carbonate plus sodium silicate to 3 gallons of water. (3) Sodium hydroxide (Lye) prepared in a fresh solution in the proportion of not less than 1 pound...

9 CFR 96.10 - Uncertified casings; transportation for disinfection; original shipping containers; disposition...

Code of Federal Regulations, 2013 CFR

2013-01-01

... hydroxide (Lye) prepared in a fresh solution in the proportion of not less than 1 pound avoirdupois of... in case any of the sodium hydroxide solution should come in contact with the body. (2) This solution...) Dissolve the salt in the proportion of 90 pounds of salt to 100 gallons of water. Add 23/4 gallons of C. P...

9 CFR 95.26 - Railroad cars, trucks, boats, aircraft and other means of conveyance, equipment or containers...

Code of Federal Regulations, 2013 CFR

2013-01-01

... proportion of 1 pound to 3 gallons of water. (2) Sodium carbonate (4 percent) plus sodium silicate (0.1 percent) in the proportion of 1 pound of sodium carbonate plus sodium silicate to 3 gallons of water. (3) Sodium hydroxide (Lye) prepared in a fresh solution in the proportion of not less than 1 pound...

Lower extremity kinematics during walking and elliptical training in individuals with and without traumatic brain injury.

PubMed

Buster, Thad; Burnfield, Judith; Taylor, Adam P; Stergiou, Nicholas

2013-12-01

Elliptical training may be an option for practicing walking-like activity for individuals with traumatic brain injuries (TBI). Understanding similarities and differences between participants with TBI and neurologically healthy individuals during elliptical trainer use and walking may help guide clinical applications incorporating elliptical trainers. Ten participants with TBI and a comparison group of 10 neurologically healthy participants underwent 2 familiarization sessions and 1 data collection session. Kinematic data were collected as participants walked on a treadmill or on an elliptical trainer. Gait-related measures, including coefficient of multiple correlations (a measure of similarity between ensemble joint movement profiles; coefficient of multiple correlations [CMCs]), critical event joint angles, variability of peak critical event joint angles (standard deviations [SDs]) of peak critical event joint angles, and maximum Lyapunov exponents (a measure of the organization of the variability [LyEs]) were compared between groups and conditions. Coefficient of multiple correlations values comparing the similarity in ensemble motion profiles between the TBI and comparison participants exceeded 0.85 for the hip, knee, and ankle joints. The only critical event joint angle that differed significantly between participants with TBI and comparison participants was the ankle during terminal stance. Variability was higher for the TBI group (6 of 11 comparisons significant) compared with comparison participants. Hip and knee joint movement patterns of both participants with TBI and comparison participants on the elliptical trainer were similar to walking (CMCs ≥ 0.87). Variability was higher during elliptical trainer usage compared with walking (5 of 11 comparisons significant). Hip LyEs were higher during treadmill walking. Ankle LyEs were greater during elliptical trainer usage. Movement patterns of participants with TBI were similar to, but more variable than, those of comparison participants while using both the treadmill and the elliptical trainer. If incorporation of complex movements similar to walking is a goal of rehabilitation, elliptical training is a reasonable alternative to treadmill-based training.Video Abstract available (see Video, Supplemental Digital Content 1, http://links.lww.com/JNPT/A65) for more insights from the authors.

JPRS Report, Science & Technology, USSR: Life Sciences

DTIC Science & Technology

1987-07-09

87) 59 Prophylactic Effectiveness of Epsilon- Aminocaproic Acid (EACA) on Influenza in Mice (L.Ye. Puzis, V.P. Lozitskiy, et al.; ACTA VIROLOGICA...EFFECTIVENESS OF EPSILON- AMINOCAPROIC ACID (EACA) ON INFLUENZA IN MICE Bratislava ACTA VIROLOGICA in Russian Vol 30, No 1, Jan 86 (manuscript received 17...MEDITSINSKOY KHIMII, No 4, Jul-Aug 86) 59 Effects of Novel Antineoplastic Blastozole on Nucleic Acid Levels and DNA Synthesis in Cancer Cells (S.N

Design for Corrosion Control of Potable Water Distribution Systems

DTIC Science & Technology

1975-02-01

acrylics , vinyls, PVA latex or an acrylic latex, silicone alkyds , and zinc-rich primer systems. A zinc-rich primed coating system has a number of...some of the better weathering topcoats include the acrylics , silicone alkyds , and vinyl acrylics . 5.3.1.3 Interior Protection. The interiors of steel...alcohol (Methanol, wood alcohol). Alkali -- Caustic, such as sodium hydroxide, lye, etc. Alkyd plastics -- Plastics based on resins composed

Influence of California-style black ripe olive processing on the formation of acrylamide.

PubMed

Charoenprasert, Suthawan; Mitchell, Alyson

2014-08-27

Methods used in processing California-style black ripe olives generate acrylamide. California-style black ripe olives contain higher levels of acrylamide (409.67 ± 42.60-511.91 ± 34.08 μg kg(-1)) as compared to California-style green ripe olives (44.02 ± 3.55-105.79 ± 22.01 μg kg(-1)), Greek olives (<1.42 μg kg(-1)), and Spanish olives (not detected), indicating that the higher temperatures used to sterilize the California-style green ripe and black ripe olives are required for acrylamide formation. Preprocessing brine storage influenced the formation of acrylamide in a time-dependent manner. Acrylamide increased during the first 30 days of storage. Longer brine storage times (>30 days) result in lower acrylamide levels in the finished product. The presence of calcium ions in the preprocessing brining solution results in higher levels of acrylamide in finished products. Air oxidation during lye processing and the neutralization of olives prior to sterilization significantly increase the formation of acrylamide in the finished products. Conversely, lye-processing decreases the levels of acrylamide in the final product. These results indicate that specific steps in the California-style black ripe olive processing may be manipulated to mitigate the formation of acrylamide in finished products.

Interim Particulate Matter Test Method for the Determination of Particulate Matter from Gas Turbine Engines

DTIC Science & Technology

2011-07-29

Research Missouri University of Science and Technology G-7 Norwood Hall, 320 W 12th Street, Rolla, MO 65409 Scott C. Herndon, Michael T. Timko...and Richard C. Miake-Lye Aerodyne Research Inc. 45 Manning Road, Billerica, MA 01821 John S. Kinsey U. S. Environmental Protection Agency...Office of Research and Development National Risk Management Research Laboratory Research Triangle Park, NC 27711 Dave Gemmill Quality Assurance

Peptides: β-cyclodextrin inclusion compounds as highly effective antimicrobial and anti-epithelial proliferation agents.

PubMed

Consuegra, Jessika; de Lima, Maria Elena; Santos, Daniel; Sinisterra, Rubén Dario; Cortés, Maria Esperanza

2013-12-01

The use of antimicrobial peptides (AMPs) as therapeutic agents for periodontal infections has great advantages, such as broad spectrum of action, low toxicity, and limited bacterial resistance. However, their practical use is limited because of the large amount of peptide required to exercise the microbicidal function. LyeTxI, LL37f, and KR12 cationic peptides were prepared with β-cyclodextrin (βCD) at 1:1 molar ratios. The susceptibility of Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, and Fusobacterium nucleatum were assessed in anaerobic conditions. Cytotoxicity assays were performed using osteoblast and Caco-2 epithelial cells, and hemolytic activity was assessed on rabbit erythrocytes at an absorbance of 414 nm. Parameters of surface roughness and electrical charge were established by atomic force microscopy and zeta (ζ) potential, respectively. AMP/βCDs drastically decreased the peptide concentration required for activity against the bacteria tested. Moreover, AMPs associated with βCD were able to modify cell-surface parameters, such as roughness and ζ potential. On the other hand, AMP/βCD did not alter the degree of hemolysis induced by the pure AMPs. The effective concentration at half-maximum values of the peptides and compounds on osteoblasts were greater than the concentrations required to achieve inhibition of bacterial growth in all the species tested. AMP/βCDs inhibited the proliferation of Caco-2 epithelial cells in a more efficient manner than AMPs alone. AMP/βCD compounds more effectively inhibit periodontopathogenic bacteria than AMPs alone, with the additional ability of inhibiting the proliferation of epithelial cells at concentrations that are non-cytotoxic for osteoblasts and erythrocytes.

Waste Vegetable Oil as an Alternative Fuel for Diesel Vehicles

DTIC Science & Technology

2009-03-01

processor has a 160 gallon capacity, a fuel dryer , and features automatic mixing of the chemicals. The chemicals needed consist of lye (sodium...to distinguish it as tax-exempt. Fuel taxes are reported to the Internal Revenue Service ( IRS ) when the fuel is distributed to the “Service...collected in the commercial market. The refiner will pay the tax per gallon directly to the 22 IRS . When the fuel is sold, the end user pays the tax

Demonstration of Novel Sampling Techniques for Measurement of Turbine Engine Volatile and Non-Volatile Particulate Matter (PM) Emissions

DTIC Science & Technology

2017-03-06

WP-201317) Demonstration of Novel Sampling Techniques for Measurement of Turbine Engine Volatile and Non -volatile Particulate Matter (PM...Engine Volatile and Non -Volatile Particulate Matter (PM) Emissions 6. AUTHOR(S) E. Corporan, M. DeWitt, C. Klingshirn, M.D. Cheng, R. Miake-Lye, J. Peck...the performance and viability of two devices to condition aircraft turbine engine exhaust to allow the accurate measurement of total (volatile and non

Heterocyclic aromatic hydrocarbons show estrogenic activity upon metabolization in a recombinant transactivation assay.

PubMed

Brinkmann, Markus; Maletz, Sibylle; Krauss, Martin; Bluhm, Kerstin; Schiwy, Sabrina; Kuckelkorn, Jochen; Tiehm, Andreas; Brack, Werner; Hollert, Henner

2014-05-20

Heterocyclic aromatic hydrocarbons (hetero-PAHs) are increasingly studied at contaminated sites; especially at former industrial facilities where coal tar-oil was handled, e.g., wood treatment plants, high concentrations of hetero-PAHs are frequently detected in groundwater plumes. In previous studies, fractions of groundwater with high estrogenic activity contained hetero-PAHs and their hydroxylated metabolites. To evaluate this preliminary evidence, selected hetero-PAHs were screened for their estrogenic activity in lyticase yeast estrogen screen (LYES) and ER CALUX. All tested substances were inactive in the LYES. Hetero-PAHs such as acridine, xanthene, indole, 2-methylbenzofuran, 2,3-dimethylbenzofuran, dibenzofuran, dibenzothiophene, quinoline, and 6-methylquinoline were positive in the ER CALUX, with estradiol equivalence factors (EEFs) from 2.85 × 10(-7) to 3.18 × 10(-5). The EEF values of these substances were comparable to those of other xenoestrogens (e.g., alkylphenols or bisphenol A) that are sometimes found in surface water. Chemical analyses revealed that T47Dluc cells could metabolize most of the substances. Among the metabolites (tentatively) identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS) were hydroxides and their keto tautomers, sulfates, sulfoxides, and N-oxides. Because of their high concentrations measured in groundwater, we conclude that hetero-PAHs and metabolites may be a potential risk and should be the subject of further research.

Military Standard Transportation and Movement Procedures. Volume 1. Change 5

DTIC Science & Technology

1994-08-12

ANATA AMT JUNEAU JNU ANNAROO ANY KETCHIKAN INTL AIRPORT KTN ANDAMOOKA ADO KING SALMON AKN ANGUS DOWNS ANZ KODIAK ADQ ARARAT ARY KOTZEBUE OTZ ARGYLE DOWNS...ARX ASBURY PARK, NJ AUA ARUBA, ARUBA ARY ARARAT , AUSTRALIA AUB ITAUBA, BRAZIL ARZ N’ZETO, ANGOLA AUC ARAUCA, COLOMBIA F4-22 C5 DoD 4500.32-R Vol. I...CAYMAN, WEST INDIES MCI KANSAS CITY, MISSOURI-INTL. USA LYC LYCKSELE, SWEDEN MCK MCCOOK, NEBRASKA, USA LYE LYNEHAM, UNITED KINGDOM M04 MONTE CARLO

The Anomalous Magnetoresistance of Graphite at High Magnetic Fields,

DTIC Science & Technology

1983-05-01

magnetoresistance anomaly. In the present work, the unusual properties of this fine structure (which is periodic in magnetic field H ) is examined in more detail...structure associated with the magnetoresistance anomly is (AH/ H ) - 0.1 T/25 T or about 0.4 Z. Thus, for typical magnetic field sweep rates (10 T in 10...magnetoresistance above 12 T have been associated by lye at al.2 with a linear increase in carrier concentration with increasing H .1 The anomalous increase

[General aspects of planning and care in mental health].

PubMed

Saforcada, E

1976-09-01

This paper reviews some general concepts on Planning, especially in public and welfare sectors, stressing those concerning the major flaws in the argentine system of mental health. The author considers the definition of planning levels, and sets forth three: general plan, program and project. The correlative implementation is also considered. The importance of feed-back from adequate evaluation is stressed, emphasizing three aspects: a) evaluation of dynamics, rate and extent of decrease, increase or stagnation; b) assessment of efficacity of factors involved; c) control and stabilization of goals already attained. The necessity to develop a human ecology, encompassing socio-cultural and psycho-social factors is stressed, together with fostering theoretical research and the use of its results by implementation agents. Several differences among prevailing mental health actions are pointed out which allow a distinction between two typical models: clinical and sanitarist. The main differences between them lye on: standard location of working sites, nature of basic actions, field of action, hypothesis for working, including ethiological and ecological assumptions, theoretical and methodological framework. A series of criteria for evaluating sanitary techniques and strategies are set forth, among which: operative procedures, length of treatments, degree of therapeutic concentration, and general pragmatic criteria. The indicators reviewed are: degree of efficacity, covering, degree of perseverance in treatments, cultural barriers between patient and therapist, delegation of functions into special, first-rate sanitary agents, needs for the training of mental health workers. An attempt is made at developping general evaluation criteria for mental health planning, and several indicators are proposed, among which: a) cost/efficacity ratio, including in costs the use of economical, human and physical resources; b) preventive capacities of the community; c) capacities for the community to generate new types of organization and social dynamics able to cope with increasing mental health demands; first-rate personnel and mental health agents performance and training; e) assessment of "distances" between theoretical planning and actual implementation outlines; f) requirements of time for the implementation of programs.

The Lactose and Galactose Content of Cheese Suitable for Galactosaemia: New Analysis.

PubMed

Portnoi, P A; MacDonald, A

2016-01-01

The UK Medical Advisory Panel of the Galactosaemia Support Group report the lactose and galactose content of 5 brands of mature Cheddar cheese, Comte and Emmi Emmental fondue mix from 32 cheese samples. The Medical Advisory Panel define suitable cheese in galactosaemia to have a lactose and galactose content consistently below 10 mg/100 g. A total of 32 samples (5 types of mature Cheddar cheese, Comte and "Emmi Swiss Fondue", an emmental fondue mix) were analysed by high-performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD) technology used to perform lactose and galactose analysis. Cheddar cheese types: Valley Spire West Country, Parkham, Lye Cross Vintage, Lye Cross Mature, Tesco West Country Farmhouse Extra Mature and Sainsbury's TTD West Country Farmhouse Extra Mature had a lactose and galactose content consistently below 10 mg/100 g (range <0.05 to 12.65 mg). All Comte samples had a lactose content below the lower limit of detection (<0.05 mg) with galactose content from <0.05 to 1.86 mg/100 g; all samples of Emmi Swiss Fondue had lactose below the lower limit of detection (<0.05 mg) and galactose between 2.19 and 3.04 mg/100 g. All of these cheese types were suitable for inclusion in a low galactose diet for galactosaemia. It is possible that the galactose content of cheese may change over time depending on its processing, fermentation time and packaging techniques.

Hole Concentration vs. Mn Fraction in a Diluted (Ga,Mn)As Ferromagnetic Semiconductor

DTIC Science & Technology

2002-01-01

4785 (1999). 5. T. Hayashi , M. Tanaka, and T. Nishinaga, J. App!. Ph vs. 81, 4865 (1997). 6. H. Ohno and F. Matsukura, Solid State Commnin . 117, 179...off-set between the " and I bands, and the Fermi energy (EF) increases to the right. 231 REFERENCES I . H. Ohno , H. Munekata, T. Penney, S. von Moln...r, and L. L. Chang, Phys. Rev. Lett. 68, 2664 (1992). 2. H. Ohno , A. Shen, F. Matsukura. A. Oiwa, A. Endo, S. Katsumnoto, and Y. lye, Appl. Ph vs

A Balloon Design for 9000 Pounds at 90,000 Feet: Recommendations Based on Heavy-Load Balloon History.

DTIC Science & Technology

1983-03-09

10 20 30 40 STRAIN M%) The machine and traverse direction strenth ia1~t bo0th voJ 󈧏’, [𔃺 P"�A F7o arc, shown in) Figure A3: the machjinek...thlt lam ination muocess controls and dJue to normal fluctuations in the laminat ion ’I fvlo o. ihe influence of a _ihes lye is: additionally...that the model’ s ,gorelength was less. than 10 ft C5. Niccum, R. J. (1972) Comparison of polyester film -yarn composite balloon materials subjected

Acute colitis caused by caustic products.

PubMed

da Fonseca, J; Brito, M J; Freitas, J; Leal, C

1998-12-01

We report two cases of acute proctocolitis caused by rectal application of caustic products of domestic use. One 61-yr-old woman applied an ammonia solution enema; the other patient, a 63-yr-old woman, accidentally applied an enema containing lye. Both patients presented with intense anal pain, but the first patient also had abdominal pain with guarding, hematochezia, and leucocytosis. An acute proctocolitis was found at sigmoidoscopy in both patients. Only conservative and symptomatic measures were prescribed in both cases, and a clinical and endoscopic recovery was seen. In spite of persistent fibrosis in the lamina propria, no signs of stenosis were found.

Normal Modes of a Lagrangian System Constrained in a Potential Well.

DTIC Science & Technology

1983-12-01

A’ -137 948 NORMAL MODES OF A LFHbRANGIAN SYSTEM CONSTRAINED INvi P0TENTIAL WELL(U WISCONSNN UNIV-MADISON MATHEMATICS RESEARCH CENTER V EN DEC F1...Carolina 27709 DT FLE OP Y UNIVERSITY OF WISCONSIN-MADISON MATHEMATICS RESEARCH CENTER NORMAL MODES OF A LAGRANGIAN SYSTEM CONSTRAINED IN A POTENTIAL WELL...respect to the norm lYE [f i + 2 yi )dtl/ 0 Since H I(S’ 1 n’) C CO(S, fle ), then the set A 1 0 is an open set in H1 (lf’) The periodic solution of

Redox shuttle additives for lithium-ion batteries

DOEpatents

Zhang, Lu; Zhang, Zhengcheng; Amine, Khalil

2017-03-21

An electro lye includes a compound of Formula I or IA: where each instance of R.sup.1 is independently H, alkyl, alkoxy, alkenyl, aryl, heteroaryl, or cycloalkyl; each instance of R.sup.2 is independently H, alkyl, alkoxy, alkenyl, aryl, heteroaryl, or cycloalkyl; each instance of R.sup.3 is independently H, alkyl, alkenyl, aryl, or cycloalkyl; each instance of R.sup.4 is independently H, halogen, CN, NO.sub.2, phosphate, alkyl, alkenyl, aryl, heteroaryl, or cycloalkyl; x is 1, 2, 3, 4, or 5; y is 1 or 2; and z is 0, 1, 2, 3, or 4. ##STR00001##

'Relaxers' damage hair: evidence from amino acid analysis.

PubMed

Khumalo, Nonhlanhla P; Stone, Janet; Gumedze, Freedom; McGrath, Emily; Ngwanya, Mzudumile R; de Berker, David

2010-03-01

'Relaxers' are used by more than two thirds of African females to straighten hair, with easy grooming and increased length often cited as reasons. A recent study reported relaxed hair lengths much shorter than expected, suggesting increased fragility; the potential for scalp inflammation and scarring alopecia remains unclear. To investigate the biochemical effects of 'relaxers' on hair. With informed consent, included participants represented 3 groups: natural hair, asymptomatic relaxed hair, and symptomatic (brittle) relaxed hair. Biochemical analysis was performed by using a Biochrom 30 amino acid analyzer. Differences in amino acid levels were assessed using either Wilcoxon rank sum test or matched-pairs signed-rank test. There was a decrease in cystine, citrulline, and arginine; however, an increase in glutamine was found in all relaxed compared to natural hair. Cystine levels (milligram per gram amino acid nitrogen) were similar in natural proximal and distal hair: 14 mg/g (range, 4-15 mg/g) versus 14 mg/g (range, 12-15 mg/g); P = .139. In asymptomatic relaxed hair, cystine levels were higher in less frequently relaxed samples proximal to scalp: 7.5 mg/g (5.6-12) versus 3.3 mg/g (1.3-9.2); P = .005. Cystine levels in distal asymptomatic relaxed and symptomatic relaxed hair were similar to each other and to those in the genetic hair fragility disease trichothiodystrophy. It was not possible to analyze lye and no-lye 'relaxers' separately. 'Relaxers' are associated with reduced cystine consistent with fragile damaged hair. A decrease in citrulline and glutamine has been associated with inflammation; prospective studies are needed to investigate whether or how 'relaxers' induce inflammation. Copyright 2009 American Academy of Dermatology, Inc. Published by Mosby, Inc. All rights reserved.

Household cleaning product-related injuries treated in US emergency departments in 1990-2006.

PubMed

McKenzie, Lara B; Ahir, Nisha; Stolz, Uwe; Nelson, Nicolas G

2010-09-01

The goal was to examine comprehensively the patterns and trends of household cleaning product-related injuries among children treated in US emergency departments. Through use of the National Electronic Injury Surveillance System database, cases of unintentional, nonfatal, household cleaning product-related injuries were selected by using product codes for drain cleaners, ammonia, metal polishes/tarnish removers, turpentine, dishwasher detergents, acids, swimming pool chemicals, oven cleaners, pine oil cleaners/disinfectants, laundry soaps/detergents, toilet bowl products, abrasive cleaners, general-purpose household cleaners, noncosmetic bleaches, windshield wiper fluids, caustic agents, lye, wallpaper cleaners, room deodorizers/fresheners, spot removers, and dishwashing liquids. Products were categorized according to major toxic ingredients, mode of action, and exposure. An estimated 267 269 children

Experimental study on pore structure and performance of sintered porous wick

NASA Astrophysics Data System (ADS)

He, Da; Wang, Shufan; Liu, Rutie; Wang, Zhubo; Xiong, Xiang; Zou, Jianpeng

2018-02-01

Porous wicks were prepared via powder metallurgy using NH4HCO3 powders as pore-forming agent. The pore-forming agent particle size was varied to control the pore structure and equivalent pore size distribution feature of porous wick. The effect of pore-forming agent particle size on the porosity, pore structures, equivalent pore size distribution and capillary pumping performance were investigated. Results show that with the particle size of pore-forming agent decrease, the green density and the volume shrinkage of the porous wicks gradually increase and the porosity reduces slightly. There are two types of pores inside the porous wick, large-sized prefabricated pores and small-sized gap pores. With the particle size of pore-forming agent decrease, the size of the prefabricated pores becomes smaller and the distribution tends to be uniform. Gap pores and prefabricated pores inside the wick can make up different types of pore channels. The equivalent pore size of wick is closely related to the structure of pore channels. Furthermore, the equivalent pore size distribution of wick shows an obvious double-peak feature when the pore-forming agent particle size is large. With the particle size of pore-forming agent decrease, the two peaks of equivalent pore size distribution approach gradually to each other, resulting in a single-peak feature. Porous wick with single-peak feature equivalent pore size distribution possesses the better capillary pumping performances.

Water Quality Management Studies, Lake Seminole, February-December 1979. Phase II.

DTIC Science & Technology

1982-12-01

Carbon, Dissolved Organtc X X X X X X X Carbon. Total Organic I I X I X X" X Carbon Dioxide I X X X X X X I trogen. Total Amonia I X I X X X I Nitrogen...were less than 1 mg S04/1. During Phase I and Phase II there were no distinctive trends in measured carbon dioxide levels. However, there was a tendency...6. so 0 To CARSON DIOXIDE (MG C02.01. 0 1.3 Re 1. Re 0. 2* 0 NITROGEN. TOTAL AMMONIA IMG N/’LI 0.02 < 0.02 < 0.02 CO (002 ’ NITROG01. NITPATE.NITT2lYE

Fame emerges as a result of small memory

NASA Astrophysics Data System (ADS)

Bingol, Haluk

2008-03-01

A dynamic memory model is proposed in which an agent “learns” a new agent by means of recommendation. The agents can also “remember” and “forget.” The memory size is decreased while the population size is kept constant. “Fame” emerged as a few agents become very well known in expense of the majority being completely forgotten. The minimum and the maximum of fame change linearly with the relative memory size. The network properties of the who-knows-who graph, which represents the state of the system, are investigated.

Effects of Styrene-Acrylic Sizing on the Mechanical Properties of Carbon Fiber Thermoplastic Towpregs and Their Composites.

PubMed

Bowman, Sean; Jiang, Qiuran; Memon, Hafeezullah; Qiu, Yiping; Liu, Wanshuang; Wei, Yi

2018-03-01

Thermoplastic towpregs are convenient and scalable raw materials for the fabrication of continuous fiber-reinforced thermoplastic matrix composites. In this paper, the potential to employ epoxy and styrene-acrylic sizing agents was evaluated for the making of carbon fiber thermoplastic towpregs via a powder-coating method. The protective effects and thermal stability of these sizing agents were investigated by single fiber tensile test and differential scanning calorimetry (DSC) measurement. The results indicate that the epoxy sizing agent provides better protection to carbon fibers, but it cannot be used for thermoplastic towpreg processing due to its poor chemical stability at high temperature. The bending rigidity of the tows and towpregs with two styrene-acrylic sizing agents was measured by cantilever and Kawabata methods. The styrene-acrylic sized towpregs show low torque values, and are suitable for further processing, such as weaving, preforming, and winding. Finally, composite panels were fabricated directly from the towpregs by hot compression molding. Both of the composite panels show superior flexural strength (>400 MPa), flexural modulus (>63 GPa), and interlaminar shear strength (>27 MPa), indicating the applicability of these two styrene-acrylic sizing agents for carbon fiber thermoplastic towpregs.

Self-organized Segregation on the Grid

NASA Astrophysics Data System (ADS)

Omidvar, Hamed; Franceschetti, Massimo

2018-02-01

We consider an agent-based model with exponentially distributed waiting times in which two types of agents interact locally over a graph, and based on this interaction and on the value of a common intolerance threshold τ , decide whether to change their types. This is equivalent to a zero-temperature ising model with Glauber dynamics, an asynchronous cellular automaton with extended Moore neighborhoods, or a Schelling model of self-organized segregation in an open system, and has applications in the analysis of social and biological networks, and spin glasses systems. Some rigorous results were recently obtained in the theoretical computer science literature, and this work provides several extensions. We enlarge the intolerance interval leading to the expected formation of large segregated regions of agents of a single type from the known size ɛ >0 to size ≈ 0.134. Namely, we show that for 0.433< τ < 1/2 (and by symmetry 1/2<τ <0.567), the expected size of the largest segregated region containing an arbitrary agent is exponential in the size of the neighborhood. We further extend the interval leading to expected large segregated regions to size ≈ 0.312 considering "almost segregated" regions, namely regions where the ratio of the number of agents of one type and the number of agents of the other type vanishes quickly as the size of the neighborhood grows. In this case, we show that for 0.344 < τ ≤ 0.433 (and by symmetry for 0.567 ≤ τ <0.656) the expected size of the largest almost segregated region containing an arbitrary agent is exponential in the size of the neighborhood. This behavior is reminiscent of supercritical percolation, where small clusters of empty sites can be observed within any sufficiently large region of the occupied percolation cluster. The exponential bounds that we provide also imply that complete segregation, where agents of a single type cover the whole grid, does not occur with high probability for p=1/2 and the range of intolerance considered.

Metal and alloy nanoparticles by amine-borane reduction of metal salts by solid-phase synthesis: atom economy and green process.

PubMed

Sanyal, Udishnu; Jagirdar, Balaji R

2012-12-03

A new solid state synthetic route has been developed toward metal and bimetallic alloy nanoparticles from metal salts employing amine-boranes as the reducing agent. During the reduction, amine-borane plays a dual role: acts as a reducing agent and reduces the metal salts to their elemental form and simultaneously generates a stabilizing agent in situ which controls the growth of the particles and stabilizes them in the nanosize regime. Employing different amine-boranes with differing reducing ability (ammonia borane (AB), dimethylamine borane (DMAB), and triethylamine borane (TMAB)) was found to have a profound effect on the particle size and the size distribution. Usage of AB as the reducing agent provided the smallest possible size with best size distribution. Employment of TMAB also afforded similar results; however, when DMAB was used as the reducing agent it resulted in larger sized nanoparticles that are polydisperse too. In the AB mediated reduction, BNH(x) polymer generated in situ acts as a capping agent whereas, the complexing amine of the other amine-boranes (DMAB and TMAB) play the same role. Employing the solid state route described herein, monometallic Au, Ag, Cu, Pd, and Ir and bimetallic CuAg and CuAu alloy nanoparticles of <10 nm were successfully prepared. Nucleation and growth processes that control the size and the size distribution of the resulting nanoparticles have been elucidated in these systems.

Super enhanced permeability and retention (SUPR) effects in tumors following near infrared photoimmunotherapy

NASA Astrophysics Data System (ADS)

Kobayashi, Hisataka; Choyke, Peter L.

2016-06-01

To date, the delivery of nano-sized therapeutic agents to cancers largely relies on enhanced permeability and retention (EPR) effects that are caused by the leaky nature of cancer vasculature. However, nano-sized agents delivered in this way have demonstrated limited success in oncology due to the relatively small magnitude of the EPR effect. For achieving superior delivery of nano-sized agents, super-enhanced permeability and retention (SUPR) effects are needed. Near infrared photo-immunotherapy (NIR-PIT) is a recently reported therapy that treats tumors with light therapy and subsequently causes an increase in nano-drug delivery up to 24-fold compared with untreated tumors in which only the EPR effect is present. SUPR effects could enhance delivery into tumor beds of a wide variety of nano-sized agents including particles, antibodies, and protein binding small molecular agents. Therefore, taking advantage of the SUPR effects after NIR-PIT may be a promising avenue to utilize a wide variety of nano-drugs in a highly effective manner.

Blood-pool contrast agent for pre-clinical computed tomography

NASA Astrophysics Data System (ADS)

Cruje, Charmainne; Tse, Justin J.; Holdsworth, David W.; Gillies, Elizabeth R.; Drangova, Maria

2017-03-01

Advances in nanotechnology have led to the development of blood-pool contrast agents for micro-computed tomography (micro-CT). Although long-circulating nanoparticle-based agents exist for micro-CT, they are predominantly based on iodine, which has a low atomic number. Micro-CT contrast increases when using elements with higher atomic numbers (i.e. lanthanides), particularly at higher energies. The purpose of our work was to develop and evaluate a lanthanide-based blood-pool contrast agent that is suitable for in vivo micro-CT. We synthesized a contrast agent in the form of polymer-encapsulated Gd nanoparticles and evaluated its stability in vitro. The synthesized nanoparticles were shown to have an average diameter of 127 +/- 6 nm, with good size dispersity. Particle size distribution - evaluated by dynamic light scattering over the period of two days - demonstrated no change in size of the contrast agent in water and saline. Additionally, our contrast agent was stable in a mouse serum mimic for up to 30 minutes. CT images of the synthesized contrast agent (containing 27 mg/mL of Gd) demonstrated an attenuation of over 1000 Hounsfield Units. This approach to synthesizing a Gd-based blood-pool contrast agent promises to enhance the capabilities of micro-CT imaging.

Size effect of Au/PAMAM contrast agent on CT imaging of reticuloendothelial system and tumor tissue

NASA Astrophysics Data System (ADS)

Wang, Wei; Li, Jian; Liu, Ransheng; Zhang, Aixu; Yuan, Zhiyong

2016-09-01

Polyamidoamine (PAMAM)-entrapped Au nanoparticles were synthesized with distinct sizes to figure out the size effect of Au-based contrast agent on CT imaging of passively targeted tissues. Au/PAMAM nanoparticles were first synthesized with narrow distribution of particles size of 22.2 ± 3.1, 54.2 ± 3.7, and 104.9 ± 4.7 nm in diameters. Size effect leads no significant difference on X-ray attenuation when Au/PAMAM was ≤0.05 mol/L. For CT imaging of a tumor model, small Au/PAMAM were more easily internalized via endocytosis in the liver, leading to more obviously enhanced contrast. Similarly, contrast agents with small sizes were more effective in tumor imaging because of the enhanced permeability and retention effect. Overall, the particle size of Au/PAMAM heavily affected the efficiency of CT enhancement in imaging RES and tumors.

The impact of compaction, moisture content, particle size and type of bulking agent on initial physical properties of sludge-bulking agent mixtures before composting.

PubMed

Huet, J; Druilhe, C; Trémier, A; Benoist, J C; Debenest, G

2012-06-01

This study aimed to experimentally acquire evolution profiles between depth, bulk density, Free Air Space (FAS), air permeability and thermal conductivity in initial composting materials. The impact of two different moisture content, two particle size and two types of bulking agent on these four parameters was also evaluated. Bulk density and thermal conductivity both increased with depth while FAS and air permeability both decreased with it. Moreover, depth and moisture content had a significant impact on almost all the four physical parameters contrary to particle size and the type of bulking agent. Copyright © 2012 Elsevier Ltd. All rights reserved.

Effects of competition and cooperation interaction between agents on networks in the presence of a market capacity

NASA Astrophysics Data System (ADS)

Sonubi, A.; Arcagni, A.; Stefani, S.; Ausloos, M.

2016-08-01

A network effect is introduced taking into account competition, cooperation, and mixed-type interaction among agents along a generalized Verhulst-Lotka-Volterra model. It is also argued that the presence of a market capacity undoubtedly enforces a definite limit on the agent's size growth. The state stability of triadic agents, i.e., the most basic network plaquette, is investigated analytically for possible scenarios, through a fixed-point analysis. It is discovered that: (i) market demand is only satisfied for full competition when one agent monopolizes the market; (ii) growth of agent size is encouraged in full cooperation; (iii) collaboration among agents to compete against one single agent may result in the disappearance of this single agent out of the market; and (iv) cooperating with two rivals may become a growth strategy for an intelligent agent.

Effects of competition and cooperation interaction between agents on networks in the presence of a market capacity.

PubMed

Sonubi, A; Arcagni, A; Stefani, S; Ausloos, M

2016-08-01

A network effect is introduced taking into account competition, cooperation, and mixed-type interaction among agents along a generalized Verhulst-Lotka-Volterra model. It is also argued that the presence of a market capacity undoubtedly enforces a definite limit on the agent's size growth. The state stability of triadic agents, i.e., the most basic network plaquette, is investigated analytically for possible scenarios, through a fixed-point analysis. It is discovered that: (i) market demand is only satisfied for full competition when one agent monopolizes the market; (ii) growth of agent size is encouraged in full cooperation; (iii) collaboration among agents to compete against one single agent may result in the disappearance of this single agent out of the market; and (iv) cooperating with two rivals may become a growth strategy for an intelligent agent.

Impact of varying analytical methodologies on grain particle size determination.

PubMed

Kalivoda, J R; Jones, C K; Stark, C R

2017-01-01

The determination of particle size is an important quality control measurement for feed manufacturers, nutritionists, and producers. The current approved method for determining the geometric mean diameter by weight (d) and geometric standard deviation (S) of grains is standard ANSI/ASAE S319.4. This method controls many variables, including the suggested quantity of initial material and the type, number, and size of sieves. However, the method allows for variations in sieving time, sieve agitators, and the use of a dispersion agent. The objective of this experiment was to determine which method of particle size analysis best estimated the particle size of various cereal grain types. Eighteen samples of either corn, sorghum, or wheat were ground and analyzed using different variations of the approved method. Treatments were arranged in a 5 × 3 factorial arrangement with 5 sieving methods: 1) 10-min sieving time with sieve agitators and no dispersion agent, 2) 10-min sieving time with sieve agitators and dispersion agent, 3) 15-min sieving time with no sieve agitators or dispersion agent, 4) 15-min sieving time with sieve agitators and no dispersion agent, and 5) 15-min sieving time with sieve agitators and dispersion agent conducted in 3 grain types (ground corn, sorghum, and wheat) with 4 replicates per treatment. The analytical method that resulted in the lowest d and greatest S was considered desirable because it was presumably representative of increased movement of particles to their appropriate sieve. Analytical method affected d and S ( ≤ 0.05) measured by both standards. Inclusion of sieve agitators and dispersion agent in the sieve stack resulted in the lowest d, regardless of sieving time. Inclusion of dispersion agent reduced d ( ≤ 0.05) by 32 and 36 µm when shaken for 10 and 15 min, respectively, compared to the same sample analyzed without dispersion agent. The addition of the dispersion agent also increased S. The dispersion agent increased the quantity of very fine particles collected in the pan; therefore, S was significantly greater ( ≤ 0.05). Corn and sorghum ground using the same mill parameters had similar d ( > 0.05), but wheat ground using the same mill parameters was 120 to 104 µm larger ( ≤ 0.05) than corn and sorghum, respectively. Both sieve agitators and dispersion agent should be included when conducting particle size analysis. The results indicate that 10 and 15 min of sieving time produced similar results.

Station Climatic Summaries, North America. Volume 2. Alaska, Canada and Greenland

DTIC Science & Technology

1993-02-01

36 IZ50 NNE 13 5$ 9 J7 1 4 17 11 a a 13 4 ISO NNE 4 52 9 1 21 1 41 19. :5 :S 10 1, 𔃻:: Z. 1:9 1 4ý1 11 1 2 :07 165 E 7 67 V.c 1 9 1, . ý I IDECp 8 1...WP.T. SASKATOIEAN4 p11100 i8-t976 a $lueLye$ C429 ,"omber 197r ILOCA&130N 𔃾S 26 WIN7 40 9LX 184 1Im AN ISO US00 AW CLMATIC. BRE- --- L ItI of. o4 U1 99...JUN 62 45 33 14 4.1 3.1 57 W 7 55 8583 . 9003 1 014621 JUL 78 50 3725 3.0.0 _# #W 7 477972 35.21900 5 20 0 010153 5 0 6 AUG72 -318 5.3 4.9 1 4W 7 47875

Improved Escherichia coli Bactofection and Cytotoxicity by Heterologous Expression of Bacteriophage ΦX174 Lysis Gene E.

PubMed

Chung, Tai-Chun; Jones, Charles H; Gollakota, Akhila; Kamal Ahmadi, Mahmoud; Rane, Snehal; Zhang, Guojian; Pfeifer, Blaine A

2015-05-04

Bactofection offers a gene delivery option particularly useful in the context of immune modulation. The bacterial host naturally attracts recognition and cellular uptake by antigen presenting cells (APCs) as the initial step in triggering an immune response. Moreover, depending on the bacterial vector, molecular biology tools are available to influence and/or overcome additional steps and barriers to effective antigen presentation. In this work, molecular engineering was applied using Escherichia coli as a bactofection vector. In particular, the bacteriophage ΦX174 lysis E (LyE) gene was designed for variable expression across strains containing different levels of lysteriolysin O (LLO). The objective was to generate a bacterial vector with improved attenuation and delivery characteristics. The resulting strains exhibited enhanced gene and protein release and inducible cellular death. In addition, the new vectors demonstrated improved gene delivery and cytotoxicity profiles to RAW264.7 macrophage APCs.

Eosinophilic pneumonia presenting as life-threatening ARDS.

PubMed

Maia, José Miguel; Guedes, Fernando; Aragão, Irene; Cardoso, Teresa

2015-07-06

We present a case of a 25-year-old woman with sudden onset of shortness of breath, cough and malaise, 24 h after discharge from a psychiatric hospital. She had been there for 2 weeks after a suicide attempt with lye, and started treatment with paroxetin, alprazolam and valproic acid. She also started smoking 20 cigarettes/day during that hospital admission. Brought to the emergency department, she evolved in the first 24 h with respiratory failure and shock needing intensive care unit (ICU) admission, with mechanical ventilation and vasopressor support. Empiric antibiotic therapy was started (piperacillin-tazobactam and azithromycin) suspecting healthcare-associated pneumonia. The patient's chest radiography progressed with bilateral infiltrates. Peripheral blood eosinophilia was seen on the second day. A bronchoalveolar lavage was performed and had 50% of eosinophils. She was started on treatment with steroids and the next day no longer needed vasopressors; 4 days later she was extubated. 2015 BMJ Publishing Group Ltd.

The role of fanatics in consensus formation

NASA Astrophysics Data System (ADS)

Gündüç, Semra

2015-08-01

A model of opinion dynamics with two types of agents as social actors are presented, using the Ising thermodynamic model as the dynamics template. The agents are considered as opportunists which live at sites and interact with the neighbors, or fanatics/missionaries which move from site to site randomly in persuasion of converting agents of opposite opinion with the help of opportunists. Here, the moving agents act as an external influence on the opportunists to convert them to the opposite opinion. It is shown by numerical simulations that such dynamics of opinion formation may explain some details of consensus formation even when one of the opinions are held by a minority. Regardless the distribution of the opinion, different size societies exhibit different opinion formation behavior and time scales. In order to understand general behavior, the scaling relations obtained by comparing opinion formation processes observed in societies with varying population and number of randomly moving agents are studied. For the proposed model two types of scaling relations are observed. In fixed size societies, increasing the number of randomly moving agents give a scaling relation for the time scale of the opinion formation process. The second type of scaling relation is due to the size dependent information propagation in finite but large systems, namely finite-size scaling.

Discrete and Continuum Approximations for Collective Cell Migration in a Scratch Assay with Cell Size Dynamics.

PubMed

Matsiaka, Oleksii M; Penington, Catherine J; Baker, Ruth E; Simpson, Matthew J

2018-04-01

Scratch assays are routinely used to study the collective spreading of cell populations. In general, the rate at which a population of cells spreads is driven by the combined effects of cell migration and proliferation. To examine the effects of cell migration separately from the effects of cell proliferation, scratch assays are often performed after treating the cells with a drug that inhibits proliferation. Mitomycin-C is a drug that is commonly used to suppress cell proliferation in this context. However, in addition to suppressing cell proliferation, mitomycin-C also causes cells to change size during the experiment, as each cell in the population approximately doubles in size as a result of treatment. Therefore, to describe a scratch assay that incorporates the effects of cell-to-cell crowding, cell-to-cell adhesion, and dynamic changes in cell size, we present a new stochastic model that incorporates these mechanisms. Our agent-based stochastic model takes the form of a system of Langevin equations that is the system of stochastic differential equations governing the evolution of the population of agents. We incorporate a time-dependent interaction force that is used to mimic the dynamic increase in size of the agents. To provide a mathematical description of the average behaviour of the stochastic model we present continuum limit descriptions using both a standard mean-field approximation and a more sophisticated moment dynamics approximation that accounts for the density of agents and density of pairs of agents in the stochastic model. Comparing the accuracy of the two continuum descriptions for a typical scratch assay geometry shows that the incorporation of agent growth in the system is associated with a decrease in accuracy of the standard mean-field description. In contrast, the moment dynamics description provides a more accurate prediction of the evolution of the scratch assay when the increase in size of individual agents is included in the model.

Fabrication of Aluminum Foams with Small Pore Size by Melt Foaming Method

NASA Astrophysics Data System (ADS)

Cheng, Ying; Li, Yanxiang; Chen, Xiang; Shi, Tong; Liu, Zhiyong; Wang, Ningzhen

2017-04-01

This article introduces an improvement to the fabrication of aluminum foams with small pore size by melt foaming method. Before added to the melt, the foaming agent (titanium hydride) was pretreated in two steps. It firstly went through the traditional pre-oxidation treatment, which delayed the decomposition of titanium hydride and made sure the dispersion stage was controllable. Then such pre-oxidized titanium hydride powder was mixed with copper powder in a planetary ball mill. This treatment can not only increase the number of foaming agent particles and make them easier to disperse in the melt, which helps to increase the number of pores, but also reduce the amount of hydrogen released in the foaming stage. Therefore, the pore size could be decreased. Using such a ball-milled foaming agent in melt foaming method, aluminum foams with small pore size (average size of 1.6 mm) were successfully fabricated.

Enterprise Management Network Architecture Distributed Knowledge Base Support

DTIC Science & Technology

1990-11-01

Advantages Potentially, this makes a distributed system more powerful than a conventional, centralized one in two ways: " First, it can be more reliable...does not completely apply [35]. The grain size of the processors measures the individual problem-solving power of the agents. In this definition...problem-solving power amounts to the conceptual size of a single action taken by an agent visible to the other agents in the system. If the grain is coarse

A self-adapting herding model: The agent judge-abilities influence the dynamic behaviors

NASA Astrophysics Data System (ADS)

Dong, Linrong

2008-10-01

We propose a self-adapting herding model, in which the financial markets consist of agent clusters with different sizes and market desires. The ratio of successful exchange and merger depends on the volatility of the market and the market desires of the agent clusters. The desires are assigned in term of the wealth of the agent clusters when they merge. After an exchange, the beneficial cluster’s desire keeps on the same, the losing one’s desire is altered which is correlative with the agent judge-ability. A parameter R is given to all agents to denote the judge-ability. The numerical calculation shows that the dynamic behaviors of the market are influenced distinctly by R, which includes the exponential magnitudes of the probability distribution of sizes of the agent clusters and the volatility autocorrelation of the returns, the intensity and frequency of the volatility.

Preparation of gold nanoparticles and determination of their particles size via different methods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Iqbal, Muhammad; Usanase, Gisele; Oulmi, Kafia

Graphical abstract: Preparation of gold nanoparticles via NaBH{sub 4} reduction method, and determination of their particle size, size distribution and morphology by using different techniques. - Highlights: • Gold nanoparticles were synthesized by NaBH{sub 4} reduction method. • Excess of reducing agent leads to tendency of aggregation. • The particle size, size distribution and morphology were investigated. • Particle size was determined both experimentally as well as theoretically. - Abstract: Gold nanoparticles have been used in various applications covering both electronics, biosensors, in vivo biomedical imaging and in vitro biomedical diagnosis. As a general requirement, gold nanoparticles should be preparedmore » in large scale, easy to be functionalized by chemical compound of by specific ligands or biomolecules. In this study, gold nanoparticles were prepared by using different concentrations of reducing agent (NaBH{sub 4}) in various formulations and their effect on the particle size, size distribution and morphology was investigated. Moreover, special attention has been dedicated to comparison of particles size measured by various techniques, such as, light scattering, transmission electron microscopy, UV spectrum using standard curve and particles size calculated by using Mie theory and UV spectrum of gold nanoparticles dispersion. Particle size determined by various techniques can be correlated for monodispersed particles and excess of reducing agent leads to increase in the particle size.« less

Size-Tunable and Functional Core-Shell Structured Silica Nanoparticles for Drug Release

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chi, Fangli; Guo, Ya Nan; Liu, Jun

2010-02-18

Size-tunable silica cross-linked micellar core-shell nanoparticles (SCMCSNs) were successfully synthesized from a Pluronic nonionic surfactant (F127) template system with organic swelling agents such as 1,3,5-trimethylbenzene (TMB) and octanoic acid at room temperature. The size and morphology of SCMCSNs were directly evidenced by TEM imaging and DLS measurements (up to ~90 nm). Pyrene and coumarin 153 (C153) were used as fluorescent probe molecules to investigate the effect and location of swelling agent molecules. Papaverine as a model drug was used to measure the loading capacity and release property of nanoparticles. The swelling agents can enlarge the nanoparticle size and improve themore » drug loading capacity of nanoparticles. Moreover, the carboxylic acid group of fatty acid can adjust the release behavior of the nanoparticles.« less

Nano-sized Contrast Agents to Non-Invasively Detect Renal Inflammation by Magnetic Resonance Imaging

PubMed Central

Thurman, Joshua M.; Serkova, Natalie J.

2013-01-01

Several molecular imaging methods have been developed that employ nano-sized contrast agents to detect markers of inflammation within tissues. Renal inflammation contributes to disease progression in a wide range of autoimmune and inflammatory diseases, and a biopsy is currently the only method of definitively diagnosing active renal inflammation. However, the development of new molecular imaging methods that employ contrast agents capable of detecting particular immune cells or protein biomarkers will allow clinicians to evaluate inflammation throughout the kidneys, and to assess a patient's response to immunomodulatory drugs. These imaging tools will improve our ability to validate new therapies and to optimize the treatment of individual patients with existing therapies. This review describes the clinical need for new methods of monitoring renal inflammation, and recent advances in the development of nano-sized contrast agents for detection of inflammatory markers of renal disease. PMID:24206601

Non-immunogenic dextran-coated superparamagnetic iron oxide nanoparticles: a biocompatible, size-tunable contrast agent for magnetic resonance imaging.

PubMed

Unterweger, Harald; Janko, Christina; Schwarz, Marc; Dézsi, László; Urbanics, Rudolf; Matuszak, Jasmin; Őrfi, Erik; Fülöp, Tamás; Bäuerle, Tobias; Szebeni, János; Journé, Clément; Boccaccini, Aldo R; Alexiou, Christoph; Lyer, Stefan; Cicha, Iwona

2017-01-01

Iron oxide-based contrast agents have been in clinical use for magnetic resonance imaging (MRI) of lymph nodes, liver, intestines, and the cardiovascular system. Superparamagnetic iron oxide nanoparticles (SPIONs) have high potential as a contrast agent for MRI, but no intravenous iron oxide-containing agents are currently approved for clinical imaging. The aim of our work was to analyze the hemocompatibility and immuno-safety of a new type of dextran-coated SPIONs (SPIONdex) and to characterize these nanoparticles with ultra-high-field MRI. Key parameters related to nanoparticle hemocompatibility and immuno-safety were investigated in vitro and ex vivo. To address concerns associated with hypersensitivity reactions to injectable nanoparticulate agents, we analyzed complement activation-related pseudoallergy (CARPA) upon intravenous administration of SPIONdex in a pig model. Furthermore, the size-tunability of SPIONdex and the effects of size reduction on their biocompatibility were investigated. In vitro, SPIONdex did not induce hemolysis, complement or platelet activation, plasma coagulation, or leukocyte procoagulant activity, and had no relevant effect on endothelial cell viability or endothelial-monocytic cell interactions. Furthermore, SPIONdex did not induce CARPA even upon intravenous administration of 5 mg Fe/kg in pigs. Upon SPIONdex administration in mice, decreased liver signal intensity was observed after 15 minutes and was still detectable 24 h later. In addition, by changing synthesis parameters, a reduction in particle size <30 nm was achieved, without affecting their hemo- and biocompatibility. Our findings suggest that due to their excellent biocompatibility, safety upon intravenous administration and size-tunability, SPIONdex particles may represent a suitable candidate for a new-generation MRI contrast agent.

The fabrication of novel nanobubble ultrasound contrast agent for potential tumor imaging

NASA Astrophysics Data System (ADS)

Xing, Zhanwen; Wang, Jinrui; Ke, Hengte; Zhao, Bo; Yue, Xiuli; Dai, Zhifei; Liu, Jibin

2010-04-01

Novel biocompatible nanobubbles were fabricated by ultrasonication of a mixture of Span 60 and polyoxyethylene 40 stearate (PEG40S) followed by differential centrifugation to isolate the relevant subpopulation from the parent suspensions. Particle sizing analysis and optical microscopy inspection indicated that the freshly generated micro/nanobubble suspension was polydisperse and the size distribution was bimodal with large amounts of nanobubbles. To develop a nano-sized contrast agent that is small enough to leak through tumor pores, a fractionation to extract smaller bubbles by variation in the time of centrifugation at 20g (relative centrifuge field, RCF) was suggested. The results showed that the population of nanobubbles with a precisely controlled mean diameter could be sorted from the initial polydisperse suspensions to meet the specified requirements. The isolated bubbles were stable over two weeks under the protection of perfluoropropane gas. The acoustic behavior of the nano-sized contrast agent was evaluated using power Doppler imaging in a normal rabbit model. An excellent power Doppler enhancement was found in vivo renal imaging after intravenous injection of the obtained nanobubbles. Given the broad spectrum of potential clinical applications, the nano-sized contrast agent may provide a versatile adjunct for ultrasonic imaging enhancement and/or treatment of tumors.

Facile and green synthesis of highly stable L-cysteine functionalized copper nanoparticles

NASA Astrophysics Data System (ADS)

Kumar, Nikhil; Upadhyay, Lata Sheo Bachan

2016-11-01

A simple eco-friendly method for L-cysteine capped copper nanoparticles (CCNPs) synthesis in aqueous solution has been developed. Glucose and L-cysteine were used as reducing agent and capping/functionalizing agent, respectively. Different parameters such as capping agent concentration, pH, reaction temperature, and reducing agent concentration were optimized during the synthesis. The L-cysteine capped copper nanoparticle were characterized by ultraviolet-visible spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, Particle size and zeta potential analyser, and high resolution transmission electron microscopy. Spherical shaped cysteine functionalized/capped copper nanoparticles with an average size of 40 nm were found to be highly stable at room temperature (RT) for a period of 1 month

Optical Properties of Synthesized Nanoparticles ZnS Using Methacrylic Acid as the Capping Agent

NASA Astrophysics Data System (ADS)

Nazerdeylami, Somayeh; Saievar Iranizad, Esmaiel; Molaei, Mehdi

Optical analysis (UV-vis spectroscopy) of solution of ZnS nanoparticles prepared at room temperature by a chemical capping method using methacrylic acid (MAA) capping agent at concentration of 0.05, 0.2, 0.5 and 1.17 molar is investigated. The spectroscopy results indicate increasing of band gap of ZnS through increasing concentration of the methacrylic acid as capping agent in the solution. According to the relation of Effective Mass Approximation, it is concluded that the size of nanoparticles decreased with the increasing concentration of the capping agent in the tested solutions. The size of the particles is found to be in 1.77-2.05 nm range.

Submicron polycaprolactone particles as a carrier for imaging contrast agent for in vitro applications.

PubMed

Iqbal, Muhammad; Robin, Sophie; Humbert, Philippe; Viennet, Céline; Agusti, Geraldine; Fessi, Hatem; Elaissari, Abdelhamid

2015-12-01

Fluorescent materials have recently attracted considerable attention due to their unique properties and high performance as imaging agent in biomedical fields. Different imaging agents have been encapsulated in order to restrict its delivery to a specific area. In this study, a fluorescent contrast agent was encapsulated for in vitro application by polycaprolactone (PCL) polymer. The encapsulation was performed using modified double emulsion solvent evaporation technique with sonication. Fluorescent nanoparticles (20 nm) were incorporated in the inner aqueous phase of double emulsion. A number of samples were fabricated using different concentrations of fluorescent contrast agent. The contrast agent-containing submicron particle was characterized by a zetasizer for average particle size, SEM and TEM for morphology observations and fluorescence spectrophotometer for encapsulation efficiency. Moreover, contrast agent distribution in the PCL matrix was determined by confocal microscopy. The incorporation of contrast agent in different concentrations did not affect the physicochemical properties of PCL particles and the average size of encapsulated particles was found to be in the submicron range. Copyright © 2015 Elsevier B.V. All rights reserved.

Dynamics and fragmentation of thick-shelled microbubbles.

PubMed

May, Donovan J; Allen, John S; Ferrara, Katherine W

2002-10-01

Localized delivery could decrease the systemic side effects of toxic chemotherapy drugs. The unique delivery agents we examine consist of microbubbles with an outer lipid coating, an oil layer, and a perfluorobutane gas core. These structures are 0.5-12 microm in radius at rest. Oil layers of these acoustically active lipospheres (AALs) range from 0.3-1.5 microm in thickness and thus the agents can carry a large payload compared to nano-scale drug delivery systems. We show that triacetin-based drug-delivery vehicles can be fragmented using ultrasound. Compared with a lipid-shelled contrast agent, the expansion of the drug-delivery vehicle within the first cycle is similar, and a subharmonic component is demonstrated at an equivalent radius, frequency, and driving pressure. For the experimental conditions explored here, the pulse length required for destruction of the drug-delivery vehicle is significantly greater, with at least five cycles required, compared with one cycle for the contrast agent. For the drug-delivery vehicle, the observed destruction mechanism varies with the initial radius, with microbubbles smaller than resonance size undergoing a symmetric collapse and producing a set of small, equal-sized fragments. Between resonance size and twice resonance size, surface waves become visible, and the oscillations become asymmetrical. For agents larger than twice the resonance radius, the destruction mechanism changes to a pinch-off, with one fragment containing a large fraction of the original volume.

Effects of food processing on food allergens.

PubMed

Sathe, Shridhar K; Sharma, Girdhari M

2009-08-01

Food allergies are on the rise in Western countries. With the food allergen labeling requirements in the US and EU, there is an interest in learning how food processing affects food allergens. Numerous foods are processed in different ways at home, in institutional settings, and in industry. Depending on the processing method and the food, partial or complete removal of the offending allergen may be possible as illustrated by reduction of peanut allergen in vitro IgE immunoreactivity upon soaking and blanching treatments. When the allergen is discretely located in a food, one may physically separate and remove it from the food. For example, lye peeling has been reported to produce hypoallergenic peach nectar. Protein denaturation and/or hydrolysis during food processing can be used to produce hypoallergenic products. This paper provides a short overview of basic principles of food processing followed by examples of their effects on food allergen stability. Reviewed literature suggests assessment of processing effects on clinically relevant reactivity of food allergens is warranted.

Infants use relative numerical group size to infer social dominance

PubMed Central

Pun, Anthea; Birch, Susan A. J.; Baron, Andrew Scott

2016-01-01

Detecting dominance relationships, within and across species, provides a clear fitness advantage because this ability helps individuals assess their potential risk of injury before engaging in a competition. Previous research has demonstrated that 10- to 13-mo-old infants can represent the dominance relationship between two agents in terms of their physical size (larger agent = more dominant), whereas younger infants fail to do so. It is unclear whether infants younger than 10 mo fail to represent dominance relationships in general, or whether they lack sensitivity to physical size as a cue to dominance. Two studies explored whether infants, like many species across the animal kingdom, use numerical group size to assess dominance relationships and whether this capacity emerges before their sensitivity to physical size. A third study ruled out an alternative explanation for our findings. Across these studies, we report that infants 6–12 mo of age use numerical group size to infer dominance relationships. Specifically, preverbal infants expect an agent from a numerically larger group to win in a right-of-way competition against an agent from a numerically smaller group. In addition, this is, to our knowledge, the first study to demonstrate that infants 6–9 mo of age are capable of understanding social dominance relations. These results demonstrate that infants’ understanding of social dominance relations may be based on evolutionarily relevant cues and reveal infants’ early sensitivity to an important adaptive function of social groups. PMID:26884199

The influence of amphiphilic additional agents on the morphology and photoluminescence properties of calcium carbonate phosphor

NASA Astrophysics Data System (ADS)

Mou, Yongren; Kang, Ming; Liu, Min; Wang, Feng; Chen, Kexu; Sun, Rong

2017-06-01

In order to investigate the effect of amphiphilic additional agents on the morphology (particle shape, particle size and particle size distribution) and photoluminescence performance of calcium carbonate phosphor, the phosphors AA-CaCO3:Eu3+ (AA = glycerol or sodium dodecyl sulfate) were synthesized by the microwave-assisted co-precipitation method using glycerol (Gly) and sodium dodecyl sulfate (SDS) as amphiphilic additional agents (AA), respectively. The phase structure, morphology and luminescent properties of the as-synthesized samples were characterized by X-ray diffraction, scanning electron microscope, laser diffraction particle size analyzer and Fluorescence spectrophotometer, respectively. The results showed that the phase structure and morphology of AA-CaCO3:Eu3+ changed along with different types and amount of amphiphilic additional agents evidently. The particle size of Gly-CaCO3 decreased to 1.383 µm when the volume ratio reached 8:2 (Gly:H2O). Photoluminescence (PL) spectra show that all the AA-CaCO3:Eu3+ phosphors exhibit strong red emission peak originating from electric-dipole transition 5D0 → 7F2 (614 nm) of Eu3+ ions and the amphiphilic molecules (Gly and SDS) had a huge influence on photoluminescence intensity.

On-chip generation of microbubbles as a practical technology for manufacturing contrast agents for ultrasonic imaging

PubMed Central

Hettiarachchi, Kanaka; Talu, Esra; Longo, Marjorie L.; Dayton, Paul A.; Lee, Abraham P.

2007-01-01

This paper presents a new manufacturing method to generate monodisperse microbubble contrast agents with polydispersity index (σ) values of <2% through microfluidic flow-focusing. Micron-sized lipid shell-based perfluorocarbon (PFC) gas microbubbles for use as ultrasound contrast agents were produced using this method. The poly(dimethylsiloxane) (PDMS)-based devices feature expanding nozzle geometry with a 7 μm orifice width, and are robust enough for consistent production of microbubbles with runtimes lasting several hours. With high-speed imaging, we characterized relationships between channel geometry, liquid flow rate Q, and gas pressure P in controlling bubble sizes. By a simple optimization of the channel geometry and Q and P, bubbles with a mean diameter of <5 μm can be obtained, ideal for various ultrasonic imaging applications. This method demonstrates the potential of microfluidics as an efficient means for custom-designing ultrasound contrast agents with precise size distributions, different gas compositions and new shell materials for stabilization, and for future targeted imaging and therapeutic applications. PMID:17389962

Granular activated carbon as nucleating agent for aerobic sludge granulation: Effect of GAC size on velocity field differences (GAC versus flocs) and aggregation behavior.

PubMed

Zhou, Jia-Heng; Zhao, Hang; Hu, Miao; Yu, Hai-Tian; Xu, Xiang-Yang; Vidonish, Julia; Alvarez, Pedro J J; Zhu, Liang

2015-12-01

Initial cell aggregation plays an important role in the formation of aerobic granules. In this study, three parallel aerobic granular sludge reactors treating low-strength wastewater were established using granular activated carbon (GAC) of different sizes as the nucleating agent. A novel visual quantitative evaluation method was used to discern how GAC size affects velocity field differences (GAC versus flocs) and aggregation behavior during sludge granulation. Results showed that sludge granulation was significantly enhanced by addition of 0.2mm GAC. However, there was no obvious improvement in granulation in reactor amended with 0.6mm GAC. Hydraulic analysis revealed that increase of GAC size enhanced the velocity field difference between flocs and GAC, which decreased the lifecycle and fraction of flocs-GAC aggregates. Overall, based on analysis of aggregation behavior, GAC of suitable sizes (0.2mm) can serve as the nucleating agent to accelerate flocs-GAC coaggregation and formation of aerobic granules. Copyright © 2015 Elsevier Ltd. All rights reserved.

Low Temperature Synthesis of CdSe Quantum Dots with Amine Derivative and Their Chemical Kinetics

NASA Astrophysics Data System (ADS)

Seongmi Hwang,; Youngmin Choi,; Sunho Jeong,; Hakyun Jung,; Chang Gyoun Kim,; Teak-Mo Chung,; Beyong-Hwan Ryu,

2010-05-01

The chemical kinetics of growing CdSe nanocrystals was studied in order to investigate the effects of amine capping agents on the size of resulting quantum dots (QDs). CdSe QDs were prepared in phenyl ether, and the amine ligand dependence of QD size was determined. The results show that the size of CdSe nanocrystals can be regulated by controlling reaction rate, with smaller QDs being formed in slower processes. The results of photoluminescence (PL) studies show that the emission wavelengths of the QDs well correlate with particle size. This simple process for forming different-sized QDs, which uses a cheap solvent and various capping agents, has the potential for preparing CdSe nanocrystals more economically.

Preparation of carbon fiber unsaturated sizing agent for enhancing interfacial strength of carbon fiber/vinyl ester resin composite

NASA Astrophysics Data System (ADS)

Jiao, Weiwei; Cai, Yemeng; Liu, Wenbo; Yang, Fan; Jiang, Long; Jiao, Weicheng; Wang, Rongguo

2018-05-01

The practical application of carbon fiber (CF) reinforced vinyl ester resin (VE) composite was hampered seriously by the poor interfacial adhesion property. In this work, a novel unsaturated sizing agent was designed and prepared to improve the interfacial strength by covalently bonding CF with VE matrix. The main component of the sizing agent, N-(4‧4-diaminodiphenyl methane)-2-hydroxypropyl methacrylate (DMHM), was synthesized and confirmed by FTIR and NMR. XPS results of sized carbon fiber (SCF) showed that DMHM has adhered to desized fiber surface and reacted with some active functional groups on the surface. The SCF was characterized by high surface roughness and surface energy (especially the polar component), which means better wettability by VE. As a result, the interface shear strength and interlaminar shear strength of SCF/VE composite were enhanced by 96.56% and 66.07% respectively compared with CF/VE composite, benefited mainly from the strong and tough interphase.

Effects of the turnover rate on the size distribution of firms: An application of the kinetic exchange models

NASA Astrophysics Data System (ADS)

Chakrabarti, Anindya S.

2012-12-01

We address the issue of the distribution of firm size. To this end we propose a model of firms in a closed, conserved economy populated with zero-intelligence agents who continuously move from one firm to another. We then analyze the size distribution and related statistics obtained from the model. There are three well known statistical features obtained from the panel study of the firms i.e., the power law in size (in terms of income and/or employment), the Laplace distribution in the growth rates and the slowly declining standard deviation of the growth rates conditional on the firm size. First, we show that the model generalizes the usual kinetic exchange models with binary interaction to interactions between an arbitrary number of agents. When the number of interacting agents is in the order of the system itself, it is possible to decouple the model. We provide exact results on the distributions which are not known yet for binary interactions. Our model easily reproduces the power law for the size distribution of firms (Zipf’s law). The fluctuations in the growth rate falls with increasing size following a power law (though the exponent does not match with the data). However, the distribution of the difference of the firm size in this model has Laplace distribution whereas the real data suggests that the difference of the log of sizes has the same distribution.

Biosynthesis of spherical and highly stable gold nanoparticles using Ferulago Angulata aqueous extract: dual role of extract

NASA Astrophysics Data System (ADS)

Alizadeh, A.; Parsafar, S.; Khodaei, M. M.

2017-03-01

A biocompatible method for synthesizing of highly disperses gold nanoparticles using Ferulago Angulata leaf extract has been developed. It has been shown that leaf extract acts as reducing and coating agent. Various spectroscopic and electron microscopic techniques were employed for the structural characterization of the prepared nanoparticles. The biosynthesized particles were identified as elemental gold with spherical morphology, narrow size distribution (ranged 9.2-17.5 nm) with high stability. Also, the effect of initial ratio of precursors, temperature and time of reaction on the size and morphology of the nanoparticles was studied in more detail. It was observed that varying these parameters provides an accessible remote control on the size and morphology of nanoparticles. The uniqueness of this procedure lies in its cleanliness using no extra surfactant, reducing agent or any capping agent.

The Effects of Organic Solvents on the Physicochemical Properties of Human Serum Albumin Nanoparticles.

PubMed

Mohammad-Beigi, Hossein; Shojaosadati, Seyed Abbas; Morshedi, Dina; Mirzazadeh, Negar; Arpanaei, Ayyoob

2016-03-01

Recently, applications of albumin nanoparticles as drug delivery carriers have increased. Most toxicology studies have shown that surface chemistry and size of nanoparticles play an important role in biocompatibility and toxicity. The effect of desolvating agents with different chemical properties on the size of synthesized HSA NPs was investigated. Acetone, ethanol, methanol, and acetonitrile were used to synthesize HSA NPs with controllable size by desolvation method. Scanning electron microscopy (SEM), dynamic light scattering (DLS), and circular dichroism (CD) were employed to characterize produced particles. Finally, the toxicity of HSA NPs synthesized under different conditions was evaluated on PC-12 cells. The sizes of synthesized particles differed according to the different solvents used. The sizes were 275.3 nm, 155.3 nm, 100.11 nm, and 66.2 nm for acetonitrile, ethanol, acetone, and methanol, respectively. CD showed that larger NPs had more changes in the secondary structures. Finally, the toxicity monitored on the cultured PC-12 cells showed no significant toxic effect through treating with these NPs at different concentrations (0-500 μg.mL -1 ). The size of HSA NPs has a strong dependency on the desolvating agent. The mechanism in which the desolvating agent affects the size of HSA NPs is complex. Various factors such as dielectric constant, polarity, functional groups, and hydrogen bonding of the solvents have the potential to affect the size and structure of HSA NPs. CD analysis suggested that the solvent denaturing capability had a critical effect on the HSA particle size. The stronger denaturing capability of the solvent resulted in the larger HSA particle size.

Capping agents in nanoparticle synthesis: Surfactant and solvent system

NASA Astrophysics Data System (ADS)

Gulati, Shivani; Sachdeva, M.; Bhasin, K. K.

2018-05-01

The preparation of nanomaterials by organometallic precursors require a capping agent, which primarily acts as stabilizing agent and provide colloidal stability along with preventing agglomeration and stopping uncontrolled growth. Final morphology of nanocrystal largely depends on the type of capping agent which is adsorbed on the surface of nanocrystal. Thus capping agents are the keys to obtain the small-sized nanoparticles and are very frequently used in colloidal synthesis of nanoparticles to avoid its overgrowth.

Coating agents affected toward magnetite nanoparticles properties

NASA Astrophysics Data System (ADS)

Petcharoen, Karat; Sirivat, Anuvat

2012-02-01

Magnetite nanoparticles --MNPs-- are innovative materials used in biological and medical applications. They respond to magnetic field through the superparamagnetic behavior at room temperature. In this study, the MNPs were synthesized via the chemical co-precipitation method using various coating agents. Fatty acids, found naturally in the animal fats, can be used as a coating agent. Oleic acid and hexanoic acid were chosen as the surface modification agents to study the improvement in the suspension of MNPs in water and the magnetite properties. Suspension stability, particle size, and electrical conductivity of MNPs are critically affected by the modification process. The well-dispersed MNPs in water can be improved by the surface modification and the oleic acid coated MNPs possess excellent suspension stability over 1 week. The particle size of MNPs increases up to 40 nm using oleic acid coated MNPs. The electrical conductivity of the smallest particle size is 1.3x10-3 S/cm, which is 5 times higher than that of the largest particle, suggesting potential applications as a biomedical material under both of the electrical and magnetic fields.

Invasive Australian Acacia seed banks: Size and relationship with stem diameter in the presence of gall-forming biological control agents.

PubMed

Strydom, Matthys; Veldtman, Ruan; Ngwenya, Mzabalazo Z; Esler, Karen J

2017-01-01

Australian Acacia are invasive in many parts of the world. Despite significant mechanical and biological efforts to control their invasion and spread, soil-stored seed banks prevent their effective and sustained removal. In response South Africa has had a strong focus on employing seed reducing biological control agents to deal with Australian Acacia invasion, a programme that is considered as being successful. To provide a predictive understanding for their management, seed banks of four invasive Australian acacia species (Acacia longifolia, A. mearnsii, A. pycnantha and A. saligna) were studied in the Western Cape of South Africa. Across six to seven sites for each species, seed bank sizes were estimated from dense, monospecific stands by collecting 30 litter and soil samples. Average estimated seed bank size was large (1017 to 17261 seed m-2) as was annual input into the seed bank, suggesting that these seed banks are not residual but are replenished in size annually. A clear relationship between seed bank size and stem diameter was established indicating that mechanical clearing should be conducted shortly after fire-stimulated recruitment events or within old populations when seed banks are small. In dense, monospecific stands seed-feeding biological control agents are not effective in reducing seed bank size.

Side-by-Side Comparison of Commonly Used Biomolecules That Differ in Size and Affinity on Tumor Uptake and Internalization

PubMed Central

Leelawattanachai, Jeerapond; Kwon, Keon-Woo; Michael, Praveesuda; Ting, Richard; Kim, Ju-Young; Jin, Moonsoo M.

2015-01-01

The ability to use a systemically injected agent to image tumor is influenced by tumor characteristics such as permeability and vascularity, and the size, shape, and affinity of the imaging agent. In this study, six different imaging biomolecules, with or without specificity to tumor, were examined for tumor uptake and internalization at the whole body, ex-vivo tissue, and cellular levels: antibodies, antibody fragments (Fab), serum albumin, and streptavidin. The time of peak tumor uptake was dependent solely on the size of molecules, suggesting that molecular size is the major factor that influences tumor uptake by its effect on systemic clearance and diffusion into tumor. Affinity to tumor antigen failed to augment tumor uptake of Fab above non-specific accumulation, which suggests that Fab fragments of typical monoclonal antibodies may fall below an affinity threshold for use as molecular imaging agents. Despite abundant localization into the tumor, albumin and streptavidin were not found on cell surface or inside cells. By comparing biomolecules differing in size and affinity, our study highlights that while pharmacokinetics are a dominant factor in tumor uptake for biomolecules, affinity to tumor antigen is required for tumor binding and internalization. PMID:25901755

Production of morphology-controllable porous hyaluronic acid particles using a spray-drying method.

PubMed

Iskandar, Ferry; Nandiyanto, Asep Bayu Dani; Widiyastuti, W; Young, Lee Sin; Okuyama, Kikuo; Gradon, Leon

2009-05-01

Hyaluronic acid (HA) porous particles with controllable porosity and pore size, ranging from 100 to 300 nm, were successfully prepared using a colloidal templating and spray-drying method. HA powder and polystyrene latex (PSL) particles, which were used as the precursor and templating agent, respectively, were mixed in aqueous solution and spray-dried using a two-fluid nozzle system to produce HA and PSL composite particles. Water was evaporated during spray-drying using heated air with a temperature of 120 degrees C. This simple process was completed within several seconds. The prepared particles were collected and washed with an organic solvent to dissolve the PSL templating agent. The porosity and pore size of the resulting particles were easily controlled by changing the initial mass ratio of precursor to templating agent, i.e., HA to PSL, and by altering the size of the PSL template particles.

Bubble Jet agent release cartridge for chemical single cell stimulation.

PubMed

Wangler, N; Welsche, M; Blazek, M; Blessing, M; Vervliet-Scheebaum, M; Reski, R; Müller, C; Reinecke, H; Steigert, J; Roth, G; Zengerle, R; Paust, N

2013-02-01

We present a new method for the distinct specific chemical stimulation of single cells and small cell clusters within their natural environment. By single-drop release of chemical agents with droplets in size of typical cell diameters (d <30 μm) on-demand micro gradients can be generated for the specific manipulation of single cells. A single channel and a double channel agent release cartridge with integrated fluidic structures and integrated agent reservoirs are shown, tested, and compared in this publication. The single channel setup features a fluidic structure fabricated by anisotropic etching of silicon. To allow for simultaneous release of different agents even though maintaining the same device size, the second type comprises a double channel fluidic structure, fabricated by photolithographic patterning of TMMF. Dispensed droplet volumes are V = 15 pl and V = 10 pl for the silicon and the TMMF based setups, respectively. Utilizing the agent release cartridges, the application in biological assays was demonstrated by hormone-stimulated premature bud formation in Physcomitrella patens and the individual staining of one single L 929 cell within a confluent grown cell culture.

Designing clinical trials to test disease-modifying agents: application to the treatment trials of Alzheimer's disease.

PubMed

Xiong, Chengjie; van Belle, Gerald; Miller, J Philip; Morris, John C

2011-02-01

Therapeutic trials of disease-modifying agents on Alzheimer's disease (AD) require novel designs and analyses involving switch of treatments for at least a portion of subjects enrolled. Randomized start and randomized withdrawal designs are two examples of such designs. Crucial design parameters such as sample size and the time of treatment switch are important to understand in designing such clinical trials. The purpose of this article is to provide methods to determine sample sizes and time of treatment switch as well as optimum statistical tests of treatment efficacy for clinical trials of disease-modifying agents on AD. A general linear mixed effects model is proposed to test the disease-modifying efficacy of novel therapeutic agents on AD. This model links the longitudinal growth from both the placebo arm and the treatment arm at the time of treatment switch for these in the delayed treatment arm or early withdrawal arm and incorporates the potential correlation on the rate of cognitive change before and after the treatment switch. Sample sizes and the optimum time for treatment switch of such trials as well as optimum test statistic for the treatment efficacy are determined according to the model. Assuming an evenly spaced longitudinal design over a fixed duration, the optimum treatment switching time in a randomized start or a randomized withdrawal trial is half way through the trial. With the optimum test statistic for the treatment efficacy and over a wide spectrum of model parameters, the optimum sample size allocations are fairly close to the simplest design with a sample size ratio of 1:1:1 among the treatment arm, the delayed treatment or early withdrawal arm, and the placebo arm. The application of the proposed methodology to AD provides evidence that much larger sample sizes are required to adequately power disease-modifying trials when compared with those for symptomatic agents, even when the treatment switch time and efficacy test are optimally chosen. The proposed method assumes that the only and immediate effect of treatment switch is on the rate of cognitive change. Crucial design parameters for the clinical trials of disease-modifying agents on AD can be optimally chosen. Government and industry officials as well as academia researchers should consider the optimum use of the clinical trials design for disease-modifying agents on AD in their effort to search for the treatments with the potential to modify the underlying pathophysiology of AD.

Cooperation in N-person evolutionary snowdrift game in scale-free Barabási Albert networks

NASA Astrophysics Data System (ADS)

Lee, K. H.; Chan, Chun-Him; Hui, P. M.; Zheng, Da-Fang

2008-09-01

Cooperation in the N-person evolutionary snowdrift game (NESG) is studied in scale-free Barabási-Albert (BA) networks. Due to the inhomogeneity of the network, two versions of NESG are proposed and studied. In a model where the size of the competing group varies from agent to agent, the fraction of cooperators drops as a function of the payoff parameter. The networking effect is studied via the fraction of cooperative agents for nodes with a particular degree. For small payoff parameters, it is found that the small- k agents are dominantly cooperators, while large- k agents are of non-cooperators. Studying the spatial correlation reveals that cooperative agents will avoid to be nearest neighbors and the correlation disappears beyond the next-nearest neighbors. The behavior can be explained in terms of the networking effect and payoffs. In another model with a fixed size of competing groups, the fraction of cooperators could show a non-monotonic behavior in the regime of small payoff parameters. This non-trivial behavior is found to be a combined effect of the many agents with the smallest degree in the BA network and the increasing fraction of cooperators among these agents with the payoff for small payoffs.

Study on antibacterial alginate-stabilized copper nanoparticles by FT-IR and 2D-IR correlation spectroscopy

PubMed Central

Díaz-Visurraga, Judith; Daza, Carla; Pozo, Claudio; Becerra, Abraham; von Plessing, Carlos; García, Apolinaria

2012-01-01

Background The objective of this study was to clarify the intermolecular interaction between antibacterial copper nanoparticles (Cu NPs) and sodium alginate (NaAlg) by Fourier transform infrared spectroscopy (FT-IR) and to process the spectra applying two-dimensional infrared (2D-IR) correlation analysis. To our knowledge, the addition of NaAlg as a stabilizer of copper nanoparticles has not been previously reported. It is expected that the obtained results will provide valuable additional information on: (1) the influence of reducing agent ratio on the formation of copper nanoparticles in order to design functional nanomaterials with increased antibacterial activity, and (2) structural changes related to the incorporation of Cu NPs into the polymer matrix. Methods Cu NPs were prepared by microwave heating using ascorbic acid as reducing agent and NaAlg as stabilizing agent. The characterization of synthesized Cu NPs by ultraviolet visible spectroscopy, transmission electron microscopy (TEM), electron diffraction analysis, X-ray diffraction (XRD), and semiquantitative analysis of the weight percentage composition indicated that the average particle sizes of Cu NPs are about 3–10 nm, they are spherical in shape, and consist of zerovalent Cu and Cu2O. Also, crystallite size and relative particle size of stabilized Cu NPs were calculated by XRD using Scherrer’s formula and FT from the X-ray diffraction data. Thermogravimetric analysis, differential thermal analysis, differential scanning calorimetry (DSC), FT-IR, second-derivative spectra, and 2D-IR correlation analysis were applied to studying the stabilization mechanism of Cu NPs by NaAlg molecules. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of stabilized Cu NPs against five bacterial strains (Staphylococccus aureus ATCC 6538P, Escherichia coli ATCC 25922 and O157: H7, and Salmonella enterica serovar Typhimurium ATCC 13311 and 14028) were evaluated with macrodilution, agar dilution plate count, and well-diffusion methods. Results On the basis of the semiquantitative analysis, there was a direct correlation between the reducing agent ratio and the percentage of zerovalent Cu. This was confirmed with the statistical analysis of population of Cu NPs from TEM micrographs. At lower reducing agent ratios, two phases coexist (Cu2O and zerovalent Cu) due to incomplete reduction of copper ions by the reducing agent; however, at higher reducing agent ratios, the Cu NPs consist mainly of zerovalent Cu. Crystallite size and relative particle size of stabilized Cu NPs showed considerable differences in results and tendencies in respect to TEM analysis. However, the relative particle size values obtained from FT of XRD data agreed well with the histograms from the TEM observations. From FT results, the relative particle size and reducing agent ratio of stabilized Cu NPs showed an inverse correlation. The incomplete reduction of copper ions at lower reducing agent ratios was also confirmed by DSC studies. FT-IR and 2D-IR correlation spectra analysis suggested the first event involved in the stabilization of Cu NPs is their electrostatic interaction with –C=O of carboxylate groups of NaAlg, followed by the interaction with the available O–C–O−, and finally with the –OH groups. Bacterial susceptibility to stabilized nanoparticles was found to vary depending on the bacterial strains. The lowest MIC and MBC of stabilized Cu NPs ranged between 2 mg/L and 8 mg/L for all studied strains. Disk-diffusion studies with both E. coli strains revealed greater effectiveness of the stabilized Cu NPs compared to the positive controls (cloxacillin, amoxicillin, and nitrofurantoin). S. aureus showed the highest sensitivity to stabilized Cu NPs compared to the other studied strains. Conclusion Cu NPs were successfully synthesized via chemical reduction assisted with microwave heating. Average particle size, polydispersity, and phase composition of Cu NPs depended mainly on the reducing agent ratio. Likewise, thermal stability and antibacterial activity of stabilized Cu NPs were affected by their phase composition. Because of the carboxylate groups in polymer chains, the structural changes of stabilized Cu NPs are different from those of NaAlg. NaAlg acted as a size controller and stabilizing agent of Cu NPs, due to their ability to bind strongly to the metal surface. Our study on the stabilizing agent–dependent structural changes of stabilized NPs is helpful for wide application of NaAlg as an important biopolymer. PMID:22848180

Ferrimagnetic ferritin cage nanoparticles used as MRI contrast agent

NASA Astrophysics Data System (ADS)

Cai, Y.; Cao, C.; Zhang, T.; Xu, H.; Pan, Y.

2017-12-01

The nano-sized ferrimagnetic ferritin cage nanoparticles are ideal materials for understanding of superparamagnetism, biomimetic synthesis of ultrafine magnetic particles and their application in biomedicine. Ferrimagnetic M-HFn nanoparticles with size of magnetite cores in a mean size ranges from 2.7 nm to 5.3 nm were synthesized through loading different amount of iron into recombinant human H chain ferritin (HFn) shells. Both the saturation magnetization (Ms) and blocking temperature (Tb) were increased with the size of ferrimagnetic cores. In essence, magnetic resonance imaging (MRI) analysis showed that the synthesized M-HFn nanoparticles (5.3 nm magnetite core) has extremely high transverse relaxivity (r2) values up to 320.9 mM-1S-1, which indicate that M-HFn nanoparticles are promising negative contrast agent in early detection of tumors. In addition, the longitudinal relaxivity (r1) (10.4 mM-1S-1) and r2/r1 ratio ( 2.2) of M-HFn nanoparticles ( 2.7 nm magnetite core in diameter) will make it a considerable potential as a positive contrast agent in MRI. This means the M-HFn nanoparticles can be used as dual functional MR contrast agent. Acute toxicity study of M-HFn in rats showed that a dosage of 20 mg Fe/kg makes no abnormalities by serum biochemical and hematological analysis as well as histopathological examination. Compared with a similar commercial contrast agent, combidex (with a clinical dosage of 2.7 mg Fe/kg), it indicates that M-HFn nanoparticle is of a relative safe ferrimagnetic nanoparticle when used in vivo.

Clearance Properties of Nano-sized Particles and Molecules as Imaging Agents: Considerations and Caveats

PubMed Central

Longmire, Michelle; Choyke, Peter L.; Kobayashi, Hisataka

2009-01-01

Summary Nanoparticles possess enormous potential as diagnostic imaging agents and hold promise for the development of multimodality agents with both imaging and therapeutic capabilities. Yet, some of the most promising nanoparticles demonstrate prolonged tissue retention and contain heavy metals. This presents serious concerns for toxicity. The creation of nanoparticles with optimal clearance characteristics will minimize toxicity risks by reducing the duration of exposure to these agents. Given that many nanoparticles possess easily modifiable surface and interior chemistry, if nanoparticle characteristics associated with optimal clearance from the body were well established, it would be feasible to design and create agents with more favorable clearance properties. This paper presents a thorough discussion of the physiologic aspects of nanoparticle clearance, focusing on renal mechanisms, as well as provides an overview of current research investigating clearance of specific types of nanoparticles and nano-sized macromolecules, including dendrimers, quantum dots, liposomes and carbon, gold, and silica-based nanoparticles. PMID:18817471

Fabrication of NdCeCuO and effects of binding agents on the growth, micro-structural and electrical properties

NASA Astrophysics Data System (ADS)

Altin, S.; Aksan, M. A.; Turkoglu, S.; Yakinci, M. E.

2011-12-01

NdCeCuO superconducting samples were fabricated using ethyl alcohol, acetone and ethylenediaminetetraacetic acid (EDTA) as binding agents. For evaporation of binding agents, the samples were heat treated at 1050 °C for 24 h and then at 950 °C for 6-48 h under argon atmosphere to obtain the superconducting phase. The best superconducting performance was found in the sample heat treated at 1050 °C for 24 h and then 950 °C for 12 h which was fabricated by using acetone as binding agent. The T c and T 0 value was found to be ∼25 K and 23.4 K, respectively. Grain size in the samples fabricated was calculated using Scherer equation and SEM data. It was found that grain size strongly depends on the binding agents and heat treatment conditions. Some cracks and voids on the surface of the samples were observed, which influences the superconducting and electrical transport properties of the samples.

Method for rapid isolation of sensitive mutants

DOEpatents

Freyer, James P.

1997-01-01

Sensitive mammalian cell mutants are rapidly isolated using flow cytometry. A first population of clonal spheroids is established to contain both normal and mutant cells. The population may be naturally occurring or may arise from mutagenized cells. The first population is then flow sorted by size to obtain a second population of clonal spheroids of a first uniform size. The second population is then exposed to a DNA-damaging agent that is being investigated. The exposed second population is placed in a growth medium to form a third population of clonal spheroids comprising spheroids of increased size from the mammalian cells that are resistant to the DNA-damaging agent and spheroids of substantially the first uniform size formed from the mammalian cells that are sensitive to the DNA-damaging agent. The third population is not flow sorted to differentiate the spheroids formed from resistant mammalian cells from spheroids formed from sensitive mammalian cells. The spheroids formed from sensitive mammalian cells are now treated to recover viable sensitive cells from which a sensitive cell line can be cloned.

Method for rapid isolation of sensitive mutants

DOEpatents

Freyer, J.P.

1997-07-29

Sensitive mammalian cell mutants are rapidly isolated using flow cytometry. A first population of clonal spheroids is established to contain both normal and mutant cells. The population may be naturally occurring or may arise from mutagenized cells. The first population is then flow sorted by size to obtain a second population of clonal spheroids of a first uniform size. The second population is then exposed to a DNA-damaging agent that is being investigated. The exposed second population is placed in a growth medium to form a third population of clonal spheroids comprising spheroids of increased size from the mammalian cells that are resistant to the DNA-damaging agent and spheroids of substantially the first uniform size formed from the mammalian cells that are sensitive to the DNA-damaging agent. The third population is not flow sorted to differentiate the spheroids formed from resistant mammalian cells from spheroids formed from sensitive mammalian cells. The spheroids formed from sensitive mammalian cells are now treated to recover viable sensitive cells from which a sensitive cell line can be cloned. 15 figs.

Evidence of size-selective evolution in the fighting conch from prehistoric subsistence harvesting.

PubMed

O'Dea, Aaron; Shaffer, Marian Lynne; Doughty, Douglas R; Wake, Thomas A; Rodriguez, Felix A

2014-05-07

Intensive size-selective harvesting can drive evolution of sexual maturity at smaller body size. Conversely, prehistoric, low-intensity subsistence harvesting is not considered an effective agent of size-selective evolution. Uniting archaeological, palaeontological and contemporary material, we show that size at sexual maturity in the edible conch Strombus pugilis declined significantly from pre-human (approx. 7 ka) to prehistoric times (approx. 1 ka) and again to the present day. Size at maturity also fell from early- to late-prehistoric periods, synchronous with an increase in harvesting intensity as other resources became depleted. A consequence of declining size at maturity is that early prehistoric harvesters would have received two-thirds more meat per conch than contemporary harvesters. After exploring the potential effects of selection biases, demographic shifts, environmental change and habitat alteration, these observations collectively implicate prehistoric subsistence harvesting as an agent of size-selective evolution with long-term detrimental consequences. We observe that contemporary populations that are protected from harvesting are slightly larger at maturity, suggesting that halting or even reversing thousands of years of size-selective evolution may be possible.

Evidence of size-selective evolution in the fighting conch from prehistoric subsistence harvesting

PubMed Central

O'Dea, Aaron; Shaffer, Marian Lynne; Doughty, Douglas R.; Wake, Thomas A.; Rodriguez, Felix A.

2014-01-01

Intensive size-selective harvesting can drive evolution of sexual maturity at smaller body size. Conversely, prehistoric, low-intensity subsistence harvesting is not considered an effective agent of size-selective evolution. Uniting archaeological, palaeontological and contemporary material, we show that size at sexual maturity in the edible conch Strombus pugilis declined significantly from pre-human (approx. 7 ka) to prehistoric times (approx. 1 ka) and again to the present day. Size at maturity also fell from early- to late-prehistoric periods, synchronous with an increase in harvesting intensity as other resources became depleted. A consequence of declining size at maturity is that early prehistoric harvesters would have received two-thirds more meat per conch than contemporary harvesters. After exploring the potential effects of selection biases, demographic shifts, environmental change and habitat alteration, these observations collectively implicate prehistoric subsistence harvesting as an agent of size-selective evolution with long-term detrimental consequences. We observe that contemporary populations that are protected from harvesting are slightly larger at maturity, suggesting that halting or even reversing thousands of years of size-selective evolution may be possible. PMID:24648229

The Effects of Organic Solvents on the Physicochemical Properties of Human Serum Albumin Nanoparticles

PubMed Central

Mohammad-Beigi, Hossein; Shojaosadati, Seyed Abbas; Morshedi, Dina; Mirzazadeh, Negar; Arpanaei, Ayyoob

2016-01-01

Background Recently, applications of albumin nanoparticles as drug delivery carriers have increased. Most toxicology studies have shown that surface chemistry and size of nanoparticles play an important role in biocompatibility and toxicity. Objective The effect of desolvating agents with different chemical properties on the size of synthesized HSA NPs was investigated. Materials and Methods Acetone, ethanol, methanol, and acetonitrile were used to synthesize HSA NPs with controllable size by desolvation method. Scanning electron microscopy (SEM), dynamic light scattering (DLS), and circular dichroism (CD) were employed to characterize produced particles. Finally, the toxicity of HSA NPs synthesized under different conditions was evaluated on PC-12 cells. Results The sizes of synthesized particles differed according to the different solvents used. The sizes were 275.3 nm, 155.3 nm, 100.11 nm, and 66.2 nm for acetonitrile, ethanol, acetone, and methanol, respectively. CD showed that larger NPs had more changes in the secondary structures. Finally, the toxicity monitored on the cultured PC-12 cells showed no significant toxic effect through treating with these NPs at different concentrations (0-500 μg.mL-1). Conclusions The size of HSA NPs has a strong dependency on the desolvating agent. The mechanism in which the desolvating agent affects the size of HSA NPs is complex. Various factors such as dielectric constant, polarity, functional groups, and hydrogen bonding of the solvents have the potential to affect the size and structure of HSA NPs. CD analysis suggested that the solvent denaturing capability had a critical effect on the HSA particle size. The stronger denaturing capability of the solvent resulted in the larger HSA particle size. PMID:28959317

Development of a magnetic solid-phase extraction coupled with high-performance liquid chromatography method for the analysis of polyaromatic hydrocarbons.

PubMed

Ma, Yan; Xie, Jiawen; Jin, Jing; Wang, Wei; Yao, Zhijian; Zhou, Qing; Li, Aimin; Liang, Ying

2015-07-01

A novel magnetic solid phase extraction coupled with high-performance liquid chromatography method was established to analyze polyaromatic hydrocarbons in environmental water samples. The extraction conditions, including the amount of extraction agent, extraction time, pH and the surface structure of the magnetic extraction agent, were optimized. The results showed that the amount of extraction agent and extraction time significantly influenced the extraction performance. The increase in the specific surface area, the enlargement of pore size, and the reduction of particle size could enhance the extraction performance of the magnetic microsphere. The optimized magnetic extraction agent possessed a high surface area of 1311 m(2) /g, a large pore size of 6-9 nm, and a small particle size of 6-9 μm. The limit of detection for phenanthrene and benzo[g,h,i]perylene in the developed analysis method was 3.2 and 10.5 ng/L, respectively. When applied to river water samples, the spiked recovery of phenanthrene and benzo[g,h,i]perylene ranged from 89.5-98.6% and 82.9-89.1%, respectively. Phenanthrene was detected over a concentration range of 89-117 ng/L in three water samples withdrawn from the midstream of the Huai River, and benzo[g,h,i]perylene was below the detection limit. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Team Formation in Partially Observable Multi-Agent Systems

NASA Technical Reports Server (NTRS)

Agogino, Adrian K.; Tumer, Kagan

2004-01-01

Sets of multi-agent teams often need to maximize a global utility rating the performance of the entire system where a team cannot fully observe other teams agents. Such limited observability hinders team-members trying to pursue their team utilities to take actions that also help maximize the global utility. In this article, we show how team utilities can be used in partially observable systems. Furthermore, we show how team sizes can be manipulated to provide the best compromise between having easy to learn team utilities and having them aligned with the global utility, The results show that optimally sized teams in a partially observable environments outperform one team in a fully observable environment, by up to 30%.

Toughened uni-piece fibrous insulation

NASA Technical Reports Server (NTRS)

Leiser, Daniel B (Inventor); Smith, Marnell (Inventor); Churchward, Rex A. (Inventor); Katvala, Victor W. (Inventor)

1992-01-01

A porous body of fibrous, low density silica-based insulation material is at least in part impregnated with a reactive boron oxide containing borosilicate glass frit, a silicon tetraboride fluxing agent and a molybdenum silicide emittance agent. The glass frit, fluxing agent and emittance agent are separately milled to reduce their particle size, then mixed together to produce a slurry in ethanol. The slurry is then applied to the insulation material and sintered to produce the porous body.

The Most Effective Gold Nanorod Size for Plasmonic Photothermal Therapy: Theory and In Vitro Experiments

PubMed Central

2015-01-01

The development of new and improved photothermal contrast agents for the successful treatment of cancer (or other diseases) via plasmonic photothermal therapy (PPTT) is a crucial part of the application of nanotechnology in medicine. Gold nanorods (AuNRs) have been found to be the most effective photothermal contrast agents, both in vitro and in vivo. Therefore, determining the optimum AuNR size needed for applications in PPTT is of great interest. In the present work, we utilized theoretical calculations as well as experimental techniques in vitro to determine this optimum AuNR size by comparing plasmonic properties and the efficacy as photothermal contrast agents of three different sizes of AuNRs. Our theoretical calculations showed that the contribution of absorbance to the total extinction, the electric field, and the distance at which this field extends away from the nanoparticle surface all govern the effectiveness of the amount of heat these particles generate upon NIR laser irradiation. Comparing between three different AuNRs (38 × 11, 28 × 8, and 17 × 5 nm), we determined that the 28 × 8 nm AuNR is the most effective in plasmonic photothermal heat generation. These results encouraged us to carry out in vitro experiments to compare the PPTT efficacy of the different sized AuNRs. The 28 × 8 nm AuNR was found to be the most effective photothermal contrast agent for PPTT of human oral squamous cell carcinoma. This size AuNR has the best compromise between the total amount of light absorbed and the fraction of which is converted to heat. In addition, the distance at which the electric field extends from the particle surface is most ideal for this size AuNR, as it is sufficient to allow for coupling between the fields of adjacent particles in solution (i.e., particle aggregates), resulting in effective heating in solution. PMID:24433049

Green Synthesis of Ag and Pd Nanospheres, Nanowires, and Nanorods Using Vitamin B 2 : Catalytic Polymerisation of Aniline and Pyrrole

DOE PAGES

Nadagouda, Mallikarjuna N.; Varma, Rajender S.

2008-01-01

Formore » the first time, we report green chemistry approach using vitamin B 2 in the synthesis of silver (Ag) and palladium (Pd), nanospheres, nanowires, and nanorods at room temperature without using any harmful reducing agents, such as sodium borohydride ( NaBH 4 ) or hydroxylamine hydrochloride and any special capping or dispersing agent. Vitamin B 2 was used as reducing agent as well as capping agent due to its high-water solubility, biodegradability, and low-toxicity compared with other reducing agents. The average particle size of nanoprticle was found to be Ag (average size 6.1 ± 0.1 nm) and Pd (average size 4.1 ± 0.1 nm) nanoparticles in ethylene glycol and Ag (average size 5.9 ± 0.1 nm, and average size 6.1 ± 0.1) nanoparticles in acetic acid and NMP, respectively. The formation of noble multiple shape nanostructures and their self assembly were dependent on the solvent employed for the preparation. When water was used as solvent media, Ag and Pd nanoparticles started to self-assemble into rod-like structures and in isopropanol Ag and Pd nanoparticles yielded wire-like structures with a thickness in the range of 10 to 20 nm and several hundred microns in length. In acetone and acetonitrile medium, the Ag and Pd nanoparticles are self-assembled into a regular pattern making nanorod structures with thicknesses ranging from 100 to 200 nm and lengths of a few microns. The so-synthesized nanostructures were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray (EDX) analysis, and UV spectroscopy. The ensuing Ag and Pd nanoparticles catalyzed the reactions of aniline and pyrrole to generate polyaniline and polypyrrole nanofibers and may find various technological and biological applications. This single-step greener approach is general and can be extended to other noble metals and transition metal oxides.« less

Study of Microstructure and Mechanical Properties of Particulate Reinforced Aluminum Matrix Composite Foam

NASA Astrophysics Data System (ADS)

Kumar, Suresh; Pandey, O. P.

Metal foams cellular metals have gained an important role in the field of metallurgy, though barely a few decades old. Aluminum composite foam exhibit unique properties such as light weight, blast palliation, sound absorption, high energy absorption, and flame resistance. In the present investigation the effect of variation in the amount of CaCO3 as blowing agent on the microstructure and wear behavior of LM13 alloy foams has been studied. The blowing agent was blended in highly viscous semi-solid melt by stirring process. The process parameters that influence the formation of bubbles like the melt temperature, size and amount of blowing agent and its distribution has been optimized to get uniform size foams. The distribution behavior of blowing agent is influenced by the melt viscosity and stirring speed. For packaging application, the dry sliding wear behavior of the prepared foam was investigated by using a pin on disc method at applied loads of 9.8, 19.6 and 29.4 N at room temperature. The results indicate that the wear rate is dependent on the cell size and cell wall thickness of the foam.

Effects of solution concentration and capping agents on the properties of potassium titanyl phosphate noparticles synthesized using a co-precipitation method

NASA Astrophysics Data System (ADS)

Gharibshahian, E.; Jafar Tafershi, M.; Fazli, M.

2018-05-01

In this study, KTiOPO4 (KTP) nanoparticles were synthesized using a co-precipitation method. The effects of the solution concentration (M) and capping agents, such as PVA, oxalic acid, glycine, triethanolamine, and L-alanine, on the structural, microstructural, and optical properties of the products were investigated using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, ultraviolet-visible spectroscopy, field emission scanning electron microscopy, and transmission electron microscopy. Decreasing the solution concentration decreased the crystallite size from 53.07 nm (for M = 2) to 39.42 nm (for M = 0.5). After applying different capping agents to the sample at the optimum concentration (M = 0.5), the crystallite size decreased again and grains as small as 10.61 nm were obtained. XRD and FTIR analyses indicated the formation of KTP nanoparticles with an orthorhombic structure in all of the samples. The optical band gap increased as the crystallite size decreased. Different morphological patterns such as spherical, needle shaped, polyhedron, and tablet forms were observed in the nanoparticles, which were correlated with the effects of the capping agents employed.

Diethylenetriaminepentaacetic acid-gadolinium (DTPA-Gd)-conjugated polysuccinimide derivatives as magnetic resonance imaging contrast agents.

PubMed

Lee, Ha Young; Jee, Hye Won; Seo, Sung Mi; Kwak, Byung Kook; Khang, Gilson; Cho, Sun Hang

2006-01-01

Biocompatible polysuccinimide (PSI) derivatives conjugated with diethylenetriaminepentaacetic acid gadolinium (DTPA-Gd) were prepared as magnetic resonance imaging (MRI) contrast agents. In this study, we synthesized PSI derivatives incorporating methoxy-poly(ethylene glycol) (mPEG) as hydrophilic ligand, hexadecylamine as hydrophobic ligand, and DTPA-Gd as contrast agent. PSI was synthesized by the polycondensation polymerization of aspartic acid. All the synthesized materials were characterized by proton nuclear magnetic resonance (1H NMR). Critical micellization concentrations were determined using fluorescent probes (pyrene). Micelle size and shape were measured by electro-photometer light scattering (ELS) and atomic force microscopy (AFM). The formed micelle size ranged from 100 to 300 nm. The T1-weighted MR images of the phantom prepared with PSI-mPEG-C16-(DTPA-Gd) were obtained in a 3.0 T clinical MR imager, and the conjugates showed a great potential as MRI contrast agents.

Intrinsic dependence of the magnetic properties of CoFe2O4 nanoparticles prepared via chemical methods with addition of chelating agents

NASA Astrophysics Data System (ADS)

Mendonça, E. C.; Tenório, Mayara A.; Mecena, S. G.; Zucolotto, B.; Silva, L. S.; Jesus, C. B. R.; Meneses, C. T.; Duque, J. G. S.

2015-12-01

In this work, the effect of addition of different chelating agents on the magnetic properties of cobalt ferrite nanoparticles produced by the combining of both co-precipitation and hydrothermal methods is reported. The Rietveld analyses of X-ray diffraction patterns reveal that our samples are single phase (space group: Fd-3m) with small average sizes. The weight losses observed in the thermogravimetric measurements together with the M×H curves show that the organic contamination coming from chelating agent decomposition can give rise to misinterpretation of the magnetization measurements. Besides, analyses of the zero-field-cooled (ZFC) and field-cooled (FC) magnetization measurements and the M×H curves measured at room temperature allows us to state that both the average blocking temperature and particles size distribution are sensitive to the kind of chelating agent.

Physical and chemical properties of the transmissible mink encephalopathy agent.

PubMed

Marsh, R F; Hanson, R P

1969-02-01

The size of the transmissible mink encephalopathy (TME) agent is estimated to be less than 50 nm on the basis of its passage through membrane filters. The agent is sensitive to ether, relatively resistant to 10% Formalin, resistant to ultraviolet irradiation, and susceptible to proteolytic digestion with Pronase. Attempts to extract an infectious nucleic acid fraction with hot phenol were unsuccessful. The results of these studies indicate that the TME agent has biochemical properties which are similar to those described for the transmissible agent of scrapie.

New two-photon excitation chromophores for cellular imaging

NASA Astrophysics Data System (ADS)

D'Alfonso, Laura; Chirico, Giuseppe; Collini, Maddalena; Baldini, Giancarlo; Diaspro, Alberto; Ramoino, Paola; Abbotto, Alessandro; Beverina, Luca; Pagani, Giorgio A.

2003-10-01

The one photon and two photon excitation spectral properties (absorption, emission spectra, singlet lifetime) of a very efficient two photon absorber, dimethyl-pepep, have been measured in solution. The one photon excitation peak lye near 525 nm and the emission falls at 600 nm, where autofluorescence of cells is weak. The value of the singlet-triplet conversion rate, obtained by two-photon excitation fluorescence correlation spectroscopy, has a quadratic dependence on the excitation power and is comparable to that shown by the dye rhodamine. Preliminary results on stained cells from yeast Saccaromices cerevisiae and Paramecium primaurelia show that the dye preferentially stains DNA in the cell. A direct comparison with a DNA stainer, Dapi, is also performed. Some measurements of the dye functionalized to react with lysine and n-terminal residues of protein are presented. Moreover, this dye can be employed in order to follow in detail some cellular processes such as nuclei division. In vitro fluorescence titration of dimethyl-pepep with calf thymus DNA allowed to estimate the values of the dye-DNA association constant versus ionic strength, and an affinity close to that of ethidium bromide is found.

Temperature field for radiative tomato peeling

NASA Astrophysics Data System (ADS)

Cuccurullo, G.; Giordano, L.

2017-01-01

Nowadays peeling of tomatoes is performed by using steam or lye, which are expensive and polluting techniques, thus sustainable alternatives are searched for dry peeling and, among that, radiative heating seems to be a fairly promising method. This paper aims to speed up the prediction of surface temperatures useful for realizing dry-peeling, thus a 1D-analytical model for the unsteady temperature field in a rotating tomato exposed to a radiative heating source is presented. Since only short times are of interest for the problem at hand, the model involves a semi-infinite slab cooled by convective heat transfer while heated by a pulsating heat source. The model being linear, the solution is derived following the Laplace Transform method. A 3D finite element model of the rotating tomato is introduced as well in order to validate the analytical solution. A satisfactory agreement is attained. Therefore, two different ways to predict the onset of the peeling conditions are available which can be of help for proper design of peeling plants. Particular attention is paid to study surface temperature uniformity, that being a critical parameter for realizing an easy tomato peeling.

The mineral composition and the effect of particle size of carbonized rice straw as colorant of a traditional cake kue jongkong Surabaya

NASA Astrophysics Data System (ADS)

Murtini, E. S.; Yuwono, S. S.; Setyawan, H. Y.

2018-03-01

Carbonized rice straw (CRS) is a term defined for the residue of incomplete combustion of rice straw. Utilization of CRS as a natural food coloring agent has been the local Indonesian wisdom. However, study of this local food coloring agent is rare in the literature. This study was aimed to determine the mineral composition of the CRS, and to investigate the effect of particle size of the CRS to the black color intensity of a traditional Indonesian cake called kue jongkong Surabaya. The mineral content of the CRS was analyzed using X-ray fluorescence (XRF). The CRS was grounded and sieved passing through different screen sizes (40, 80, 100, 120 and 200 mesh).The particle size distribution was measured using particle size analyzer. The CRS with different particle sizes were then applied as a natural coloring agent of the kue jongkong, from which the intensity of black color was determined using a color reader. It was found that the dominant minerals of the CRS were SiO2, carbon, and K2O. Other trace elements found were Cl, CaO, Na2O, MgO, P, S, Fe, Al2O3 and Mn. The CRS which passed to the sieve of 40 mesh has particle size distribution of 28μm, 115μm, and 348μm for a standard of D10, D50, and D90, respectively. However, CRS that passing through the sieve of 60-200 mesh have similar particle sizes (D10: 12-14μm, D50: 49-60μm, and D90: 114-145 μm). The smaller of CRS particle size produced a darker color of the kue jongkong due to better molecule dispersion and wider surface area.

One-step synthesis of water-dispersible ultra-small Fe3O4 nanoparticles as contrast agents for T1 and T2 magnetic resonance imaging

NASA Astrophysics Data System (ADS)

Wang, Guannan; Zhang, Xuanjun; Skallberg, Andreas; Liu, Yaxu; Hu, Zhangjun; Mei, Xifan; Uvdal, Kajsa

2014-02-01

Uniform, highly water-dispersible and ultra-small Fe3O4 nanoparticles were synthesized via a modified one-step coprecipitation approach. The prepared Fe3O4 nanoparticles not only show good magnetic properties, long-term stability in a biological environment, but also exhibit good biocompatibility in cell viability and hemolysis assay. Due to the ultra-small sized and highly water-dispersibility, they exhibit excellent relaxivity properties, the 1.7 nm sized Fe3O4 nanoparticles reveal a low r2/r1 ratio of 2.03 (r1 = 8.20 mM-1 s-1, r2 = 16.67 mM-1 s-1) and the 2.2 nm sized Fe3O4 nanoparticles also appear to have a low r2/r1 ratio of 4.65 (r1 = 6.15 mM-1 s-1, r2 = 28.62 mM-1 s-1). This demonstrates that the proposed ultra-small Fe3O4 nanoparticles have great potential as a new type of T1 magnetic resonance imaging contrast agents. Especially, the 2.2 nm sized Fe3O4 nanoparticles, have a competitive r1 value and r2 value compared to commercial contrasting agents such as Gd-DTPA (r1 = 4.8 mM-1 s -1), and SHU-555C (r2 = 69 mM-1 s-1). In vitro and in vivo imaging experiments, show that the 2.2 nm sized Fe3O4 nanoparticles exhibit great contrast enhancement, long-term circulation, and low toxicity, which enable these ultra-small sized Fe3O4 nanoparticles to be promising as T1 and T2 dual contrast agents in clinical settings.Uniform, highly water-dispersible and ultra-small Fe3O4 nanoparticles were synthesized via a modified one-step coprecipitation approach. The prepared Fe3O4 nanoparticles not only show good magnetic properties, long-term stability in a biological environment, but also exhibit good biocompatibility in cell viability and hemolysis assay. Due to the ultra-small sized and highly water-dispersibility, they exhibit excellent relaxivity properties, the 1.7 nm sized Fe3O4 nanoparticles reveal a low r2/r1 ratio of 2.03 (r1 = 8.20 mM-1 s-1, r2 = 16.67 mM-1 s-1) and the 2.2 nm sized Fe3O4 nanoparticles also appear to have a low r2/r1 ratio of 4.65 (r1 = 6.15 mM-1 s-1, r2 = 28.62 mM-1 s-1). This demonstrates that the proposed ultra-small Fe3O4 nanoparticles have great potential as a new type of T1 magnetic resonance imaging contrast agents. Especially, the 2.2 nm sized Fe3O4 nanoparticles, have a competitive r1 value and r2 value compared to commercial contrasting agents such as Gd-DTPA (r1 = 4.8 mM-1 s -1), and SHU-555C (r2 = 69 mM-1 s-1). In vitro and in vivo imaging experiments, show that the 2.2 nm sized Fe3O4 nanoparticles exhibit great contrast enhancement, long-term circulation, and low toxicity, which enable these ultra-small sized Fe3O4 nanoparticles to be promising as T1 and T2 dual contrast agents in clinical settings. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr05550g

Construction of a microscopic agent-based model for firms' dynamics

NASA Astrophysics Data System (ADS)

Iyetomi, Hiroshi; Aoyama, Hideaki; Fujiwara, Yoshi; Ikeda, Yuichi; Kaizoji, Taisei; Soma, Wataru

2005-07-01

A workable microscopic model for firms' dynamics has been constructed. The model consists of firm agents and a bank agent dynamics of which are described by balance sheets. The size distribution of firms and the temporal evolution of the bank show critical dependence on whether or not firms use perfect information on their financial conditions to draw up next production plans.

Cooperative peer-to-peer multiagent-based systems

NASA Astrophysics Data System (ADS)

Caram, L. F.; Caiafa, C. F.; Ausloos, M.; Proto, A. N.

2015-08-01

A multiagent based model for a system of cooperative agents aiming at growth is proposed. This is based on a set of generalized Verhulst-Lotka-Volterra differential equations. In this study, strong cooperation is allowed among agents having similar sizes, and weak cooperation if agents have markedly different "sizes", thus establishing a peer-to-peer modulated interaction scheme. A rigorous analysis of the stable configurations is presented first examining the fixed points of the system, next determining their stability as a function of the model parameters. It is found that the agents are self-organizing into clusters. Furthermore, it is demonstrated that, depending on parameter values, multiple stable configurations can coexist. It occurs that only one of them always emerges with probability close to one, because its associated attractor dominates over the rest. This is shown through numerical integrations and simulations, after analytic developments. In contrast to the competitive case, agents are able to increase their capacity beyond the no-interaction case limit. In other words, when some collaborative partnership among a relatively small number of partners takes place, all agents act in good faith prioritizing the common good, when receiving a mutual benefit allowing them to surpass their capacity.

Cooperative peer-to-peer multiagent-based systems.

PubMed

Caram, L F; Caiafa, C F; Ausloos, M; Proto, A N

2015-08-01

A multiagent based model for a system of cooperative agents aiming at growth is proposed. This is based on a set of generalized Verhulst-Lotka-Volterra differential equations. In this study, strong cooperation is allowed among agents having similar sizes, and weak cooperation if agents have markedly different "sizes", thus establishing a peer-to-peer modulated interaction scheme. A rigorous analysis of the stable configurations is presented first examining the fixed points of the system, next determining their stability as a function of the model parameters. It is found that the agents are self-organizing into clusters. Furthermore, it is demonstrated that, depending on parameter values, multiple stable configurations can coexist. It occurs that only one of them always emerges with probability close to one, because its associated attractor dominates over the rest. This is shown through numerical integrations and simulations, after analytic developments. In contrast to the competitive case, agents are able to increase their capacity beyond the no-interaction case limit. In other words, when some collaborative partnership among a relatively small number of partners takes place, all agents act in good faith prioritizing the common good, when receiving a mutual benefit allowing them to surpass their capacity.

Rational Constraints and the Evolution of Fairness in the Ultimatum Game.

PubMed

Tomlin, Damon

2015-01-01

Behavior in the Ultimatum Game has been well-studied experimentally, and provides a marked contrast between the theoretical model of a self-interested economic agent and that of an actual human concerned with social norms such as fairness. How did such norms evolve, when punishing unfair behavior can be costly to the punishing agent? The work described here simulated a series of Ultimatum Games, in which populations of agents earned resources based on their preferences for proposing and accepting (or rejecting) offers of various sizes. Two different systems governing the acceptance or rejection of offers were implemented. Under one system, the probability that an agent accepted an offer of a given size was independent of the probabilities of accepting the other possible offers. Under the other system, a simple, ordinal constraint was placed on the acceptance probabilities such that a given offer was at least as likely to be accepted as a smaller offer. For simulations under either system, agents' preferences and their corresponding behavior evolved over multiple generations. Populations without the ordinal constraint came to emulate maximizing economic agents, while populations with the constraint came to resemble the behavior of human players.

Effect and removal mechanisms of 6 different washing agents for building wastes containing chromium.

PubMed

Xing-run, Wang; Yan-xia, Zhang; Qi, Wang; Jian-min, Shu

2012-01-01

With the building wastes contaminated by chromium in Haibei Chemical Plan in China as objects, we studied the contents of total Cr and Cr (VI) of different sizes, analyzed the effect of 6 different washing agents, discussed the removal mechanisms of 6 different washing agents for Cr in various forms, and finally selected applicable washing agent. As per the results, particle size had little impact on the contents of total Cr and Cr (VI); after one washing with water, the removal rate of total Cr and Cr (VI) was 75% and 78%, respectively, and after the second washing with 6 agents, the removal rate of citric acid was the highest, above 90% for total Cr and above 99% for hexavalent chromium; the pH of building wastes were reduced by citric acid, and under acid condition, hexavalent chromium was reduced to trivalent chromium spontaneously by organic acid, which led to better removal rate of acid soluble Cr and reducible Cr; due to the complexing action, citric acid had best removal rate for oxidizable trivalent chromium. In conclusion, citric acid is the most applicable second washing agent for building wastes.

Systematic review with network meta-analysis: the efficacy of anti-tumour necrosis factor-alpha agents for the treatment of ulcerative colitis.

PubMed

Stidham, R W; Lee, T C H; Higgins, P D R; Deshpande, A R; Sussman, D A; Singal, A G; Elmunzer, B J; Saini, S D; Vijan, S; Waljee, A K

2014-04-01

Antibodies against tumour necrosis factor-alpha (anti-TNF) are effective therapies in the treatment of ulcerative colitis (UC), but their comparative efficacy is unknown. To perform a network meta-analysis comparing the efficacy of anti-TNF agents in UC. After screening 506 studies, reviewers extracted information on seven studies. Traditional meta-analysis (TMA) was used to compare each anti-TNF agent to placebo. Bayesian network meta-analysis (NMA) was performed to compare the effects of anti-TNF agents to placebo. In addition, sample sizes for comparative efficacy trials were calculated. Compared to placebo, TMA revealed that anti-TNF agents result in a higher likelihood of induction of remission and response (RR: 2.45, 95% CI: 1.72-3.47 and RR: 1.65, 95% CI: 1.37-1.99 respectively) as well as maintenance of remission and response (RR: 2.00, 95% CI: 1.52-2.62 and RR: 1.76, 95% CI: 1.46-2.14 respectively). Individually, infliximab, adalimumab and goliumumab resulted in a higher likelihood of induction and maintenance for both remission and response. NMA found nonsignificant trends in comparisons of the individual agents. The required sample sizes for direct head-to-head trials between infliximab and adalimumab for induction and maintenance are 174 and 204 subjects respectively. This study demonstrates that, compared to placebo, infliximab, adalimumab and golimumab are all effective for the induction and maintenance of remission in ulcerative colitis. However, network meta-analysis demonstrates that no single agent is clinically superior to the others and therefore, other factors such as cost, safety, route of administration and patient preference should dictate our choice of anti-TNF agents. A randomised comparative efficacy trial between infliximab and adalimumab in UC is of practical size and should be performed. © 2014 John Wiley & Sons Ltd.

Predicting the size-dependent tissue accumulation of agents released from vascular targeted nanoconstructs

NASA Astrophysics Data System (ADS)

de Tullio, Marco D.; Singh, Jaykrishna; Pascazio, Giuseppe; Decuzzi, Paolo

2014-03-01

Vascular targeted nanoparticles have been developed for the delivery of therapeutic and imaging agents in cancer and cardiovascular diseases. However, at authors' knowledge, a comprehensive systematic analysis on their delivery efficiency is still missing. Here, a computational model is developed to predict the vessel wall accumulation of agents released from vascular targeted nanoconstructs. The transport problem for the released agent is solved using a finite volume scheme in terms of three governing parameters: the local wall shear rate , ranging from to ; the wall filtration velocity , varying from to ; and the agent diffusion coefficient , ranging from to . It is shown that the percentage of released agent adsorbing on the vessel walls in the vicinity of the vascular targeted nanoconstructs reduces with an increase in shear rate , and with a decrease in filtration velocity and agent diffusivity . In particular, in tumor microvessels, characterized by lower shear rates () and higher filtration velocities (), an agent with a diffusivity (i.e. a 50 nm particle) is predicted to deposit on the vessel wall up to of the total released dose. Differently, drug molecules, exhibiting a smaller size and much higher diffusion coefficient (), are predicted to accumulate up to . In healthy vessels, characterized by higher and lower , the largest majority of the released agent is redistributed directly in the circulation. These data suggest that drug molecules and small nanoparticles only can be efficiently released from vascular targeted nanoconstructs towards the diseased vessel walls and tissue.

Gas Release Behavior of Cu-TiH2 Composite Powder and Its Application as a Blowing Agent to Fabricate Aluminum Foams with Low Porosity and Small Pore Size

NASA Astrophysics Data System (ADS)

Cheng, Ying; Li, Yanxiang; Chen, Xiang; Liu, Zhiyong; Zhou, Xu; Wang, Ningzhen

2018-06-01

Compared to traditional pore structure with high porosity (≥ 80 pct) and large pore size (≥ 3 mm), aluminum foams with low porosity (60 to 70 pct) and small pore size (≤ 2 mm) possess higher compressive property and formability. In order to achieve the goal of reducing pore size, Cu-TiH2 composite powder prepared by ball milling preoxidized TiH2 with Cu powder was used as a blowing agent. Its gas release behavior was characterized by thermogravimetric analysis and differential scanning calorimetry. The results show that the ball milling treatment can advance the gas release process and slow the gas release rate at the same time. All these changes are favorable to the reduction of porosity and pore size. Such Cu-TiH2 composite powder provides an alternative way to fabricate aluminum foams with low porosity and small pore size.

Epoxy foams using multiple resins and curing agents

DOEpatents

Russick, Edward M.; Rand, Peter B.

2000-01-01

An epoxy foam comprising a plurality of resins, a plurality of curing agents, at least one blowing agent, at least one surfactant and optionally at least one filler and the process for making. Preferred is an epoxy foam comprising two resins of different reactivities, two curing agents, a blowing agent, a surfactant, and a filler. According to the present invention, an epoxy foam is prepared with tailorable reactivity, exotherm, and pore size by a process of admixing a plurality of resins with a plurality of curing agents, a surfactant and blowing agent, whereby a foamable mixture is formed and heating said foamable mixture at a temperature greater than the boiling temperature of the blowing agent whereby said mixture is foamed and cured.

Studying the effect of particle size and coating type on the blood kinetics of superparamagnetic iron oxide nanoparticles.

PubMed

Roohi, Farnoosh; Lohrke, Jessica; Ide, Andreas; Schütz, Gunnar; Dassler, Katrin

2012-01-01

Magnetic resonance imaging (MRI), one of the most powerful imaging techniques available, usually requires the use of an on-demand designed contrast agent to fully exploit its potential. The blood kinetics of the contrast agent represent an important factor that needs to be considered depending on the objective of the medical examination. For particulate contrast agents, such as superparamagnetic iron oxide nanoparticles (SPIOs), the key parameters are particle size and characteristics of the coating material. In this study we analyzed the effect of these two properties independently and systematically on the magnetic behavior and blood half-life of SPIOs. Eleven different SPIOs were synthesized for this study. In the first set (a), seven carboxydextran (CDX)-coated SPIOs of different sizes (19-86 nm) were obtained by fractionating a broadly size-distributed CDX-SPIO. The second set (b) contained three SPIOs of identical size (50 nm) that were stabilized with different coating materials, polyacrylic acid (PAA), poly-ethylene glycol, and starch. Furthermore, small PAA-SPIOs (20 nm) were synthesized to gain a global insight into the effects of particle size vs coating characteristics. Saturation magnetization and proton relaxivity were determined to represent the magnetic and imaging properties. The blood half-life was analyzed in rats using MRI, time-domain nuclear magnetic resonance, and inductively coupled plasma optical emission spectrometry. By changing the particle size without modifying any other parameters, the relaxivity r(2) increased with increasing mean particle diameter. However, the blood half-life was shorter for larger particles. The effect of the coating material on magnetic properties was less pronounced, but it had a strong influence on blood kinetics depending on the ionic character of the coating material. In this report we systematically demonstrated that both particle size and coating material influence blood kinetics and magnetic properties of SPIO independently. These data provide key information for the selection of a contrast agent for a defined application and are additionally valuable for other nano areas, such as hyperthermia, drug delivery, and nanotoxicology.

Studying the effect of particle size and coating type on the blood kinetics of superparamagnetic iron oxide nanoparticles

PubMed Central

Roohi, Farnoosh; Lohrke, Jessica; Ide, Andreas; Schütz, Gunnar; Dassler, Katrin

2012-01-01

Purpose: Magnetic resonance imaging (MRI), one of the most powerful imaging techniques available, usually requires the use of an on-demand designed contrast agent to fully exploit its potential. The blood kinetics of the contrast agent represent an important factor that needs to be considered depending on the objective of the medical examination. For particulate contrast agents, such as superparamagnetic iron oxide nanoparticles (SPIOs), the key parameters are particle size and characteristics of the coating material. In this study we analyzed the effect of these two properties independently and systematically on the magnetic behavior and blood half-life of SPIOs. Methods: Eleven different SPIOs were synthesized for this study. In the first set (a), seven carboxydextran (CDX)-coated SPIOs of different sizes (19–86 nm) were obtained by fractionating a broadly size-distributed CDX–SPIO. The second set (b) contained three SPIOs of identical size (50 nm) that were stabilized with different coating materials, polyacrylic acid (PAA), poly-ethylene glycol, and starch. Furthermore, small PAA–SPIOs (20 nm) were synthesized to gain a global insight into the effects of particle size vs coating characteristics. Saturation magnetization and proton relaxivity were determined to represent the magnetic and imaging properties. The blood half-life was analyzed in rats using MRI, time-domain nuclear magnetic resonance, and inductively coupled plasma optical emission spectrometry. Results: By changing the particle size without modifying any other parameters, the relaxivity r2 increased with increasing mean particle diameter. However, the blood half-life was shorter for larger particles. The effect of the coating material on magnetic properties was less pronounced, but it had a strong influence on blood kinetics depending on the ionic character of the coating material. Conclusion: In this report we systematically demonstrated that both particle size and coating material influence blood kinetics and magnetic properties of SPIO independently. These data provide key information for the selection of a contrast agent for a defined application and are additionally valuable for other nano areas, such as hyperthermia, drug delivery, and nanotoxicology. PMID:22927759

Synthesis, characterization and SERS activity of biosynthesized silver nanoparticles

NASA Astrophysics Data System (ADS)

Bindhu, M. R.; Sathe, V.; Umadevi, M.

2013-11-01

Silver nanoparticles were rapidly synthesized using Moringa oleifera flower extract as the reducing agent shows surface plasmon resonance peak at 439 nm. The size and shape of the nanoparticles controlled by varying the concentration of M. oleifera flower extract in the reaction medium. The synthesized silver nanoparticles were well-dispersed spherical nanoparticles with the average size of 14 nm. The retinoic acid present in M. oleifera flower extract used as reducing agent and proteins was responsible for capping of the bioreduced silver nanoparticles. The obtained nanoparticle shows size-dependent SERS activity. The SERS spectrum indicates that the pyridine adsorbed on the silver surface in a stand-on orientation via its nitrogen lone pair electrons.

Synthesis and characterization of a narrow size distribution of zinc oxide nanoparticles.

PubMed

Zak, A Khorsand; Razali, R; Majid, W H Abd; Darroudi, Majid

2011-01-01

Zinc oxide nanoparticles (ZnO-NPs) were synthesized via a solvothermal method in triethanolamine (TEA) media. TEA was utilized as a polymer agent to terminate the growth of ZnO-NPs. The ZnO-NPs were characterized by a number of techniques, including X-ray diffraction analysis, transition electron microscopy, and field emission electron microscopy. The ZnO-NPs prepared by the solvothermal process at 150°C for 18 hours exhibited a hexagonal (wurtzite) structure, with a crystalline size of 33 ± 2 nm, and particle size of 48 ± 7 nm. The results confirm that TEA is a suitable polymer agent to prepare homogenous ZnO-NPs.

Nanogels as imaging agents for modalities spanning the electromagnetic spectrum.

PubMed

Chan, Minnie; Almutairi, Adah

2016-01-21

In the past few decades, advances in imaging equipment and protocols have expanded the role of imaging in in vivo diagnosis and disease management, especially in cancer. Traditional imaging agents have rapid clearance and low specificity for disease detection. To improve accuracy in disease identification, localization and assessment, novel nanomaterials are frequently explored as imaging agents to achieve high detection specificity and sensitivity. A promising material for this purpose are hydrogel nanoparticles, whose high hydrophilicity, biocompatibility, and tunable size in the nanometer range make them ideal for imaging. These nanogels (10 to 200 nm) can circumvent uptake by the reticuloendothelial system, allowing longer circulation times than small molecules. In addition, their size/surface properties can be further tailored to optimize their pharmacokinetics for imaging of a particular disease. Herein, we provide a comprehensive review of nanogels as imaging agents in various modalities with sources of signal spanning the electromagnetic spectrum, including MRI, NIR, UV-vis, and PET. Many materials and formulation methods will be reviewed to highlight the versatility of nanogels as imaging agents.

Enhancement of Population Size of a Biological Control Agent and Efficacy in Control of Bacterial Speck of Tomato through Salicylate and Ammonium Sulfate Amendments

PubMed Central

Ji, Pingsheng; Wilson, Mark

2003-01-01

Sodium salicylate and ammonium sulfate were applied to leaf surfaces along with suspensions of the biological control agents Pseudomonas syringae Cit7(pNAH7), which catabolizes salicylate, and Cit7, which does not catabolize salicylate, to determine whether enhanced biological control of bacterial speck of tomato could be achieved. Foliar amendment with salicylate alone significantly enhanced the population size and the efficacy of Cit7(pNAH7), but not of Cit7, on tomato leaves. Application of ammonium sulfate alone did not result in enhanced population size or biological control efficacy of either Cit7(pNAH7) or Cit7; however, when foliar amendments with both sodium salicylate and ammonium sulfate were applied, a trend toward further increases in population size and biological control efficacy of Cit7(pNAH7) was observed. This study demonstrates the potential of using a selective carbon source to improve the efficacy of a bacterial biological control agent in the control of a bacterial plant disease and supports previous conclusions that the growth of P. syringae in the phyllosphere is primarily carbon limited and secondarily nitrogen limited. PMID:12571060

Gasification of algal biomass (Cladophora glomerata L.) with CO2/H2O/O2 in a circulating fluidized bed.

PubMed

Ebadi, Abdol Ghaffar; Hisoriev, Hikmat

2017-11-28

Gasification is one of the most important thermochemical routes to produce both synthesis gas (syngas) and chars. The quality of produced syngas wieldy depends on the operating conditions (temperature, residence time, heating rate, and gasifying agent), hydrodynamic properties of gasifier (particle size, minimum fluidization velocity, and gasifier size), and type of feedstock (coal, biomass, oil, and municipal solid wastes). In the present study, simulation of syngas production via circulating fluidized bed (CFB) gasification of algal biomass (Cladophora glomerata L.) at different gasifying agents and particle sizes was carried out, using Aspen Plus simulator. The model which has been validated by using experimental data of the technical literature was used to evaluate the influence of operating conditions on gas composition and performance parameters. The results show that biomass gasification using pure oxygen as the gasification agent has great potential to improve the caloric value of produced gas and performance indicators. It was also found that the produced gas caloric value, syngas yield, and performance parameters (CCE and CGE) increase with reaction temperature but are inversely proportional to the biomass particle size.

MOLECULAR BIOLOGY OF PHARMACOLOGIC VITREOLYSIS

PubMed Central

Sebag, J

2005-01-01

Purpose Pharmacologic vitreolysis is a promising new therapy to improve vitreoretinal surgery and, ultimately, prevent disease by mitigating the contribution of vitreous to retinopathy. The mechanism of action of the agents being developed for pharmacologic vitreolysis remains unclear. The experiments in this thesis test the hypothesis that pharmacologic vitreolysis agents break down vitreous macromolecules into smaller particles. Methods Microplasmin, hyaluronidase, and collagenase were tested in solutions of hyaluronan (n = 15) and collagen (n = 15), explants of bovine vitreous (n = 15), dissected porcine vitreous (n = 9), and intact porcine eyes (n = 18). There were also 21 controls, totaling 93 specimens. Vitreous macromolecule sizes were determined with dynamic light scattering (DLS), performed at intervals from 10 minutes to 24 hours following injections. Results Studies of DLS reproducibility showed a coefficient of variance of less than 3.3% in all but one specimen. Microplasmin decreased porcine vitreous macromolecule size in a dose-dependent manner (correlation coefficient r = 0.93), with an 85% reduction after a 30-minute exposure to the maximum dose. Hyaluronidase decreased vitreous macromolecule size in hyaluronan solutions by 50% at high (1,000 IU/mL, P < .001) doses and in bovine vitreous by 20%. Collagenase decreased macromolecule size in collagen solutions by 20% at both low (1 mg/mL, P < .001) and high (10 mg/mL, P < .001) doses, but not at all in bovine vitreous. Conclusions Pharmacologic vitreolysis can induce a significant decrease in vitreous macromolecule sizes, depending upon the pharmacologic agents and the experimental model. Broad-spectrum agents were more effective than substrate-specific enzymes. Defining the molecular biology of pharmacologic vitreolysis has implications for surgical developments and may impact upon the design of clinical trials to induce prophylactic posterior vitreous detachment. PMID:17057814

Autonomic Healing of Low-Velocity Impact Damage in Fiber-Reinforced Composites

DTIC Science & Technology

2010-01-01

formaldehyde) microencapsulation using the method described by Brown et al. [37]. Two different size ranges of microcapsules were employed to promote even...agent. The components for self-healing, urea–formaldehyde microcapsules containing dicyclopentadiene (DCPD) liquid healing agent and paraffin wax...impact damage is the employment of self-healing materials. In particular, the strat- egy using microencapsulated healing agent, demonstrated by White

Preparation and characterization of nanocrystalline CuO powders with the different surfactants and complexing agent mediated precipitation method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rajendran, V.; Gajendiran, J., E-mail: gaja.nanotech@gmail.com

2014-08-15

Highlights: • CuO nanostructures by surfactants mediated method. • Structural and optical properties of CuO nanostructures changes under the effect of surface modifier. • Citric acid assisted is the best, in terms of size, morphology and optical properties than that of CTAB, SDS and PEG-400. - Abstract: Nanostructures of copper oxide (CuO) was synthesized into crystallite sized ranging from 20 to 50 nm in the presence of different surfactants, and complex agent such as cityl tri methyl ammonium bromide (CTAB), sodium do decyl sulfate (SDS), poly ethylene glycol (PEG-400) and citric acid via a precipitation route. Variations in several parametersmore » and their effects on the structural and optical properties of CuO nanostructures (crystallite size, morphology and band gap) were investigated by XRD, FTIR, SEM and UV analysis. The UV–visible absorption spectra of the different surfactants and complexing agent assisted CuO nanostructures indicates that the estimated optical band gap energy value (1.94–1.98 eV) is higher than that of the bulk CuO value (1.4 eV), which is attributed to the quantum confinement effect. The formation mechanism of different surfactants and complexing agent assisted CuO nanostructures is also proposed.« less

The co-evolution of cultures, social network communities, and agent locations in an extension of Axelrod’s model of cultural dissemination

NASA Astrophysics Data System (ADS)

Pfau, Jens; Kirley, Michael; Kashima, Yoshihisa

2013-01-01

We introduce a variant of the Axelrod model of cultural dissemination in which agents change their physical locations, social links, and cultures. Numerical simulations are used to investigate the evolution of social network communities and the cultural diversity within and between these communities. An analysis of the simulation results shows that an initial peak in the cultural diversity within network communities is evident before agents segregate into a final configuration of culturally homogeneous communities. Larger long-range interaction probabilities facilitate the initial emergence of culturally diverse network communities, which leads to a more pronounced initial peak in cultural diversity within communities. At equilibrium, the number of communities, and hence cultures, increases when the initial cultural diversity increases. However, the number of communities decreases when the lattice size or population density increases. A phase transition between two regimes of initial cultural diversity is evident. For initial diversities below a critical value, a single network community and culture emerges that dominates the population. For initial diversities above the critical value, multiple culturally homogeneous communities emerge. The critical value of initial diversity at which this transition occurs increases with increasing lattice size and population density and generally with increasing absolute population size. We conclude that larger initial diversities promote cultural heterogenization, while larger lattice sizes, population densities, and in fact absolute population sizes promote homogenization.

ECCENTRIC ROLLING OF POWDER AND BONDING AGENT INTO SPHERICAL PELLETS

DOEpatents

Patton, G. Jr.; Zirinsky, S.

1961-06-01

A machine is described for pelletizing powder and bonding agent into spherical pellets of high density and uniform size. In this device, the material to be compacted is added to a flat circular pan which is moved in a circular orbit in a horizontal plane about an axis displaced from that of the pan's central axis without rotating the pan about its central axis. This movement causes the material contained therein to roll around the outside wall of the container and build up pellets of uniform shape, size, and density.

Percolation and cooperation with mobile agents: geometric and strategy clusters.

PubMed

Vainstein, Mendeli H; Brito, Carolina; Arenzon, Jeferson J

2014-08-01

We study the conditions for persistent cooperation in an off-lattice model of mobile agents playing the Prisoner's Dilemma game with pure, unconditional strategies. Each agent has an exclusion radius r(P), which accounts for the population viscosity, and an interaction radius r(int), which defines the instantaneous contact network for the game dynamics. We show that, differently from the r(P)=0 case, the model with finite-sized agents presents a coexistence phase with both cooperators and defectors, besides the two absorbing phases, in which either cooperators or defectors dominate. We provide, in addition, a geometric interpretation of the transitions between phases. In analogy with lattice models, the geometric percolation of the contact network (i.e., irrespective of the strategy) enhances cooperation. More importantly, we show that the percolation of defectors is an essential condition for their survival. Differently from compact clusters of cooperators, isolated groups of defectors will eventually become extinct if not percolating, independently of their size.

Targeted Gold Nanoparticle Contrast Agent for Digital Breast Tomosynthesis and Computed Tomography

DTIC Science & Technology

2011-03-01

injection series was repeated with an iodinated contrast agent, Omnipaque 320 (320 mg I/mL). Iodine enhancement was observed immediately post-injection...shape, size, growth rate, and expression level of cell-surface markers. Today, the most commonly used x-ray contrast agents are iodine-based...structural and radiographic properties of the AuNP. (iii) Evaluate the in vivo effect of the nanoparticles: tumor- enhancement , biodistribution, and

Design and Engineering of a Multi-Target (Multiplex) DNA Simulant to Evaluate Nulceic Acid Based Assays for Detection of Biological Threat Agents

DTIC Science & Technology

2006-11-01

mallei , Burkholderia pseudomallei and Variola virus (smallpox virus). A chimera of 2040 bp was engineered to produce PCR amplicons of different sizes...potential bio-warfare use have been completely sequenced, B. mallei , the etiologic agent of glanders , and B. pseudomallei, causative agent of... Burkholderia mallei Nierman et al, 2004 Burkholderia pseudomallei Holden et al, 2004 Burkholderia thailandensis

Solventless visible light-curable coating: I. Critical formulation and processing parameters.

PubMed

Bose, Sagarika; Bogner, Robin H

2010-06-30

Film coating is generally accomplished by spraying polymers dissolved in solvents onto a cascading bed of tablets. The limitations associated with the use of solvents (both aqueous and organic) can be overcome by the use of solventless coating technologies. In this proposed solventless photocurable film coating system, each layer of coating onto the pellets (non-pareil beads) was formed using liquid photocurable monomer, powdered pore-forming agents, photosensitizers and photoinitiators in a mini-coating pan and later cured by visible light. Yield, coating efficiency, variation in color, diameter and roundness were determined for each batch to evaluate process efficiency and coating quality. It was found that the ratio (S/L ratio) of the amount of solid (S) pore-forming agent to volume of liquid (L) monomer, particle size and type of the pore-forming agent, concentration of initiator, and total exposure (light intensity x exposure time) of light were critical formulation and processing parameters for the process. Using lactose as a pore-forming agent, an optimum ratio of pore-forming agent to photocurable polymer was 1.8-3.0 to achieve good process efficiency and uniformity. The ratio was sensitive to particle size and type of pore-forming agent. 2010 Elsevier B.V. All rights reserved.

Nanostructured Metal Oxides for Stoichiometric Degradation of Chemical Warfare Agents.

PubMed

Štengl, Václav; Henych, Jiří; Janoš, Pavel; Skoumal, Miroslav

2016-01-01

Metal oxides have very important applications in many areas of chemistry, physics and materials science; their properties are dependent on the method of preparation, the morphology and texture. Nanostructured metal oxides can exhibit unique characteristics unlike those of the bulk form depending on their morphology, with a high density of edges, corners and defect surfaces. In recent years, methods have been developed for the preparation of metal oxide powders with tunable control of the primary particle size as well as of a secondary particle size: the size of agglomerates of crystallites. One of the many ways to take advantage of unique properties of nanostructured oxide materials is stoichiometric degradation of chemical warfare agents (CWAs) and volatile organic compounds (VOC) pollutants on their surfaces.

77 FR 58747 - Small Business Size Standards: Real Estate and Rental and Leasing

Federal Register 2010, 2011, 2012, 2013, 2014

2012-09-24

... anchor size standards is appropriate in the current economy; whether there are gaps in SBA's methodology... independent agent), employee based costs (such as wages and payroll taxes), and material costs. For SBA's size... Estate and Rental and Leasing AGENCY: U.S. Small Business Administration. ACTION: Final rule. SUMMARY...

Microenvironment-Sensitive Multimodal Contrast Agent for Prostate Cancer Diagnosis

DTIC Science & Technology

2014-10-01

which serve as a contrast agent for Magnetic Resonance Imaging (MRI), coated with a biopolymer (i.e. starch ) to improve biocompatibility, and...size stability (i.e. resisted aggregation) and lower protein binding than the unmodified MNP. The MNPs were also incubated for varying time periods with

Biodegradable sizing agents from soy protein via controlled hydrolysis and dis-entanglement for remediation of textile effluents.

PubMed

Yang, Maiping; Xu, Helan; Hou, Xiuliang; Zhang, Jie; Yang, Yiqi

2017-03-01

Fully biodegradable textile sizes with satisfactory performance properties were developed from soy protein with controlled hydrolysis and dis-entanglement to tackle the intractable environmental issues associated with the non-biodegradable polyvinyl alcohol (PVA) in textile effluents. PVA derived from petroleum is the primary sizing agent due to its excellent sizing performance on polyester-containing yarns, especially in increasingly prevailing high-speed weaving. However, due to the poor biodegradability, PVA causes serious environmental pollution, and thus, should be substituted with more environmentally friendly polymers. Soy protein treated with high amount of triethanolamine was found with acceptable sizing properties. However, triethanolamine is also non-biodegradable and originated from petroleum, therefore, is not an ideal additive. In this research, soy sizes were developed from soy protein treated with glycerol, the biodegradable triol that could also be obtained from soy. The soy sizes had good film properties, adhesion to polyester and abrasion resistance close to PVA, rendering them qualified for sizing applications. Regarding desizing, consumption of water and energy for removal of soy size could be remarkably decreased, comparing to removal of PVA. Moreover, with satisfactory degradability, the wastewater containing soy sizes was readily dischargeable after treated in activated sludge for two days. In summary, the fully biodegradable soy sizes had potential to substitute PVA for sustainable textile processing. Copyright © 2016 Elsevier Ltd. All rights reserved.

The effects of surfactant and electrolyte concentrations on the size of nanochitosan during storage

NASA Astrophysics Data System (ADS)

Primaningtyas, Annisa; Budhijanto, Wiratni; Fahrurrozi, Mohammad; Kusumastuti, Yuni

2017-05-01

The nano-sized particle of chitosan (nanochitosan) is a potential natural preservative agent for fresh fish and fish product preservation. Theoretically, nano-sized particles exert strong van der Waals force to each other so that the problem associated with nanochitosan is agglomeration that leads to size instability during storage. Size stability is of importance in the application of nanochitosan as an antimicrobial agent because it considerably affects the antimicrobial activity of chitosan. In this study, the formulation of nanochitosan was optimized with respect to the two major factors in colloid dispersion theory, which were the presence of surfactant and electrolyte. Polysorbate-80 was chosen as the representative of food grade surfactant while NaCl was used as the electrolyte. The purposes of this study were to evaluate the effect of polysorbate-80 concentration and to determine the effect of NaCl ions on the particle size of nanochitosan for at least one month storage period. Data were analyzed using Analysis of Variance (ANOVA) to identify the factors significantly affect the size stability. The dynamics of particle size distribution during storage was measured by Particle Size Analyzer (PSA). The result showed that surfactant did not significantly affect the particle size stability. On the other hand, the addition of electrolyte into the colloidal dispersion of nanochitosan consistently stabilized and also narrowed the particle size distribution during storage in the range of 175-391 nm.

Cell and nuclear enlargement of SW480 cells induced by a plant lignan, arctigenin: evaluation of cellular DNA content using fluorescence microscopy and flow cytometry.

PubMed

Kang, Kyungsu; Lee, Hee Ju; Yoo, Ji-Hye; Jho, Eun Hye; Kim, Chul Young; Kim, Minkyun; Nho, Chu Won

2011-08-01

Arctigenin is a natural plant lignan previously shown to induce G(2)/M arrest in SW480 human colon cancer cells as well as AGS human gastric cancer cells, suggesting its use as a possible cancer chemopreventive agent. Changes in cell and nuclear size often correlate with the functionality of cancer-treating agents. Here, we report that arctigenin induces cell and nuclear enlargement of SW480 cells. Arctigenin clearly induced the formation of giant nuclear shapes in SW480, as demonstrated by fluorescence microscopic observation and quantitative determination of nuclear size. Cell and nuclear size were further assessed by flow cytometric analysis of light scattering and fluorescence pulse width after propidium iodide staining. FSC-H and FL2-W values (parameters referring to cell and nuclear size, respectively) significantly increased after arctigenin treatment; the mean values of FSC-H and FL2-W in arctigenin-treated SW480 cells were 572.6 and 275.1, respectively, whereas those of control cells were 482.0 and 220.7, respectively. Our approach may provide insights into the mechanism behind phytochemical-induced cell and nuclear enlargement as well as functional studies on cancer-treating agents.

Thermal, Morphological and Rheological Properties of Rigid Polyurethane Foams as Thermal Insulating Materials

NASA Astrophysics Data System (ADS)

Kim, Ji Mun; Han, Mi Sun; Kim, Youn Hee; Kim, Woo Nyon

2008-07-01

The polyurethane foams (PUFs) were prepared by polyether polyols, polymeric 4,4'-diphenylmethane diisocyanate (PMDI), silicone surfactants, amine catalysts and cyclopentane as a blowing agent. Solid and liquid type fillers were used as a nucleating agent to decrease a cell size of the PUFs as well as improve the thermal insulating properties of the PUFs. The PUFs were prepared by adding solid and liquid type fillers in the range of 1 to 3 wt%. For the liquid type fillers, the cell size of the PUFs showed minimum and found to decrease compared the PUF without adding fillers. Also, thermal conductivity of the PUFs with adding fillers showed minimum. For the solid type fillers, cell size and thermal conductivity of the PUFs were observed to decrease with the filler content up to 3 wt%. From these results, it is suggested that the thermal insulating property of the PUFs can be improved by adding fillers as a nucleating agent. Also, storage and loss modulus of the PUFs will be presented to study gelling points of the PUFs.

Using Improved Equation of State to Model Simultaneous Nucleation and Bubble Growth in Thermoplastic Foams

NASA Astrophysics Data System (ADS)

Khan, Irfan; Costeux, Stephane; Adrian, David; Cristancho, Diego

2013-11-01

Due to environmental regulations carbon-dioxide (CO2) is increasingly being used to replace traditional blowing agents in thermoplastic foams. CO2 is dissolved in the polymer matrix under supercritical conditions. In order to predict the effect of process parameters on foam properties using numerical modeling, the P-V-T relationship of the blowing agents should accurately be represented at the supercritical state. Previous studies in the area of foam modeling have all used ideal gas equation of state to predict the behavior of the blowing agent. In this work the Peng-Robinson equation of state is being used to model the blowing agent during its diffusion into the growing bubble. The model is based on the popular ``Influence Volume Approach,'' which assumes a growing boundary layer with depleted blowing agent surrounds each bubble. Classical nucleation theory is used to predict the rate of nucleation of bubbles. By solving the mass balance, momentum balance and species conservation equations for each bubble, the model is capable of predicting average bubble size, bubble size distribution and bulk porosity. The effect of the improved model on the bubble growth and foam properties are discussed.

Synthesis of Nanometric-Sized Barium Titanate Powders Using Acetylacetone as the Chelating Agent in a Sol-Precipitation Process

NASA Astrophysics Data System (ADS)

Hung, Kun Ming; Hsieh, Ching Shieh; Yang, Wein Duo; Tsai, Hui Ju

2007-03-01

Nanometric-sized barium titanate powders were prepared by using titanium isopropoxid as the raw material and acetylacetone as a chelating agent, in a strong alkaline solution (pH > 13) through the sol-precipitation method. The preparatory variables affect the extent of cross-linking in the structure, change the mode of condensation of the gels, and even control the particle size of the powder. The reaction rate of forming powder, at a higher temperature such as 100°C and more water content (the molar ratio of water to titanium isopropoxide is 25) or fewer acetylacetone (the molar ratio of acetylacetone to titanium isopropoxide is 1), is rapid and the particle size formed is finer at 60 80 nm. On the contrary, that of forming powder, at lower temperature (40°C) and less water content (molar ratio of water/titanium isopropoxide = 5) or higher acetylacetone (acetylacetone/titanium isopropoxide = 7), is slow and the particle size of the powder is larger. The optimal preparatory conditions were obtained by using the experimental statistical method; as a result, nanometric-sized BaTiO3 powder with an average particle size of about 50 nm was prepared.

Preparation and characterization of silver chloride nanoparticles as an antibacterial agent

NASA Astrophysics Data System (ADS)

Duong Trinh, Ngoc; Thanh Binh Nguyen, Thi; Hai Nguyen, Thanh

2015-12-01

Silver chloride nanoparticles were prepared by the precipitation reaction between silver nitrate and sodium chloride in an aqueous solution containing poly(vinyl alcohol) as a stabilizing agent. Different characteristics of the nanoparticles in suspension and in lyophilized powder such as size, morphology, chemical nature, interaction with stabilizing agent and photo-stability were investigated. Biological tests showed that the obtained silver chloride nanoparticles displayed antibacterial activities against Escherichia coli and Staphylococcus aureus.

Multifunctional curing agents and their use in improving strength of composites containing carbon fibers embedded in a polymeric matrix

DOEpatents

Vautard, Frederic; Ozcan, Soydan

2017-04-11

A functionalized carbon fiber having covalently bound on its surface a sizing agent containing epoxy groups, at least some of which are engaged in covalent bonds with crosslinking molecules, wherein each of said crosslinking molecules possesses at least two epoxy-reactive groups and at least one free functional group reactive with functional groups of a polymer matrix in which the carbon fiber is to be incorporated, wherein at least a portion of said crosslinking molecules are engaged, via at least two of their epoxy-reactive groups, in crosslinking bonds between at least two epoxy groups of the sizing agent. Composites comprised of these functionalized carbon fibers embedded in a polymeric matrix are also described. Methods for producing the functionalized carbon fibers and composites thereof are also described.

Studies on the chemical synthesis and characterization of lead oxide nanoparticles with different organic capping agents

NASA Astrophysics Data System (ADS)

Arulmozhi, K. T.; Mythili, N.

2013-12-01

Lead oxide (PbO) nanoparticles were chemically synthesized using Lead (II) acetate as precursor. The effects of organic capping agents such as Oleic acid, Ethylene Diamine Tetra Acetic acid (EDTA) and Cetryl Tri Methyl Butoxide (CTAB) on the size and morphology of the nanoparticles were studied. Characterization techniques such as X-ray diffraction (XRD), Fourier Transform-Infrared spectroscopy (FT-IR), Photoluminescence (PL) Field Emission Scanning Electron Microscopy (FE-SEM), Energy Dispersive Spectroscopy (EDS) and Transmission Electron Microscopy (TEM) were used to analyse the prepared nanoparticles for their physical, structural and optical properties. The characterization studies reveal that the synthesized PbO nanoparticles had well defined crystalline structure and sizes in the range of 25 nm to 36 nm for capping agents used and 40 nm for pure PbO nanoparticles.

Ultrasound imaging beyond the vasculature with new generation contrast agents.

PubMed

Perera, Reshani H; Hernandez, Christopher; Zhou, Haoyan; Kota, Pavan; Burke, Alan; Exner, Agata A

2015-01-01

Current commercially available ultrasound contrast agents are gas-filled, lipid- or protein-stabilized microbubbles larger than 1 µm in diameter. Because the signal generated by these agents is highly dependent on their size, small yet highly echogenic particles have been historically difficult to produce. This has limited the molecular imaging applications of ultrasound to the blood pool. In the area of cancer imaging, microbubble applications have been constrained to imaging molecular signatures of tumor vasculature and drug delivery enabled by ultrasound-modulated bubble destruction. Recently, with the rise of sophisticated advancements in nanomedicine, ultrasound contrast agents, which are an order of magnitude smaller (100-500 nm) than their currently utilized counterparts, have been undergoing rapid development. These agents are poised to greatly expand the capabilities of ultrasound in the field of targeted cancer detection and therapy by taking advantage of the enhanced permeability and retention phenomenon of many tumors and can extravasate beyond the leaky tumor vasculature. Agent extravasation facilitates highly sensitive detection of cell surface or microenvironment biomarkers, which could advance early cancer detection. Likewise, when combined with appropriate therapeutic agents and ultrasound-mediated deployment on demand, directly at the tumor site, these nanoparticles have been shown to contribute to improved therapeutic outcomes. Ultrasound's safety profile, broad accessibility and relatively low cost make it an ideal modality for the changing face of healthcare today. Aided by the multifaceted nano-sized contrast agents and targeted theranostic moieties described herein, ultrasound can considerably broaden its reach in future applications focused on the diagnosis and staging of cancer. © 2015 Wiley Periodicals, Inc.

Ultrasound Imaging Beyond the Vasculature with New Generation Contrast Agents

PubMed Central

Perera, Reshani H.; Hernandez, Christopher; Zhou, Haoyan; Kota, Pavan; Burke, Alan

2015-01-01

Current commercially available ultrasound contrast agents are gas-filled, lipid- or protein-stabilized microbubbles larger than 1 μm in diameter. Because the signal generated by these agents is highly dependent on their size, small yet highly echogenic particles have been historically difficult to produce. This has limited the molecular imaging applications of ultrasound to the blood pool. In the area of cancer imaging, microbubble applications have been constrained to imaging molecular signatures of tumor vasculature and drug delivery enabled by ultrasound-modulated bubble destruction. Recently, with the rise of sophisticated advancements in nanomedicine, ultrasound contrast agents, which are an order of magnitude smaller (100-500 nm) than their currently utilized counterparts, have been undergoing rapid development. These agents are poised to greatly expand the capabilities of ultrasound in the field of targeted cancer detection and therapy by taking advantage of the enhanced permeability and retention phenomenon of many tumors and can extravasate beyond the leaky tumor vasculature. Agent extravasation facilitates highly sensitive detection of cell surface or microenvironment biomarkers, which could advance early cancer detection. Likewise, when combined with appropriate therapeutic agents and ultrasound-mediated deployment on demand, directly at the tumor site, these nanoparticles have been shown to contribute to improved therapeutic outcomes. Ultrasound's safety profile, broad accessibility and relatively low cost make it an ideal modality for the changing face of healthcare today. Aided by the multifaceted nano-sized contrast agents and targeted theranostic moieties described herein, ultrasound can considerably broaden its reach in future applications focused on the diagnosis and staging of cancer. PMID:25580914

Acoustic bubble sorting for ultrasound contrast agent enrichment.

PubMed

Segers, Tim; Versluis, Michel

2014-05-21

An ultrasound contrast agent (UCA) suspension contains encapsulated microbubbles with a wide size distribution, with radii ranging from 1 to 10 μm. Medical transducers typically operate at a single frequency, therefore only a small selection of bubbles will resonate to the driving ultrasound pulse. Thus, the sensitivity can be improved by narrowing down the size distribution. Here, we present a simple lab-on-a-chip method to sort the population of microbubbles on-chip using a traveling ultrasound wave. First, we explore the physical parameter space of acoustic bubble sorting using well-defined bubble sizes formed in a flow-focusing device, then we demonstrate successful acoustic sorting of a commercial UCA. This novel sorting strategy may lead to an overall improvement of the sensitivity of contrast ultrasound by more than 10 dB.

Optimization of the fabrication of novel stealth PLA-based nanoparticles by dispersion polymerization using D-optimal mixture design

PubMed Central

Adesina, Simeon K.; Wight, Scott A.; Akala, Emmanuel O.

2015-01-01

Purpose Nanoparticle size is important in drug delivery. Clearance of nanoparticles by cells of the reticuloendothelial system has been reported to increase with increase in particle size. Further, nanoparticles should be small enough to avoid lung or spleen filtering effects. Endocytosis and accumulation in tumor tissue by the enhanced permeability and retention effect are also processes that are influenced by particle size. We present the results of studies designed to optimize crosslinked biodegradable stealth polymeric nanoparticles fabricated by dispersion polymerization. Methods Nanoparticles were fabricated using different amounts of macromonomer, initiators, crosslinking agent and stabilizer in a dioxane/DMSO/water solvent system. Confirmation of nanoparticle formation was by scanning electron microscopy (SEM). Particle size was measured by dynamic light scattering (DLS). D-optimal mixture statistical experimental design was used for the experimental runs, followed by model generation (Scheffe polynomial) and optimization with the aid of a computer software. Model verification was done by comparing particle size data of some suggested solutions to the predicted particle sizes. Results and Conclusion Data showed that average particle sizes follow the same trend as predicted by the model. Negative terms in the model corresponding to the crosslinking agent and stabilizer indicate the important factors for minimizing particle size. PMID:24059281

Optimization of the fabrication of novel stealth PLA-based nanoparticles by dispersion polymerization using D-optimal mixture design.

PubMed

Adesina, Simeon K; Wight, Scott A; Akala, Emmanuel O

2014-11-01

Nanoparticle size is important in drug delivery. Clearance of nanoparticles by cells of the reticuloendothelial system has been reported to increase with increase in particle size. Further, nanoparticles should be small enough to avoid lung or spleen filtering effects. Endocytosis and accumulation in tumor tissue by the enhanced permeability and retention effect are also processes that are influenced by particle size. We present the results of studies designed to optimize cross-linked biodegradable stealth polymeric nanoparticles fabricated by dispersion polymerization. Nanoparticles were fabricated using different amounts of macromonomer, initiators, crosslinking agent and stabilizer in a dioxane/DMSO/water solvent system. Confirmation of nanoparticle formation was by scanning electron microscopy (SEM). Particle size was measured by dynamic light scattering (DLS). D-optimal mixture statistical experimental design was used for the experimental runs, followed by model generation (Scheffe polynomial) and optimization with the aid of a computer software. Model verification was done by comparing particle size data of some suggested solutions to the predicted particle sizes. Data showed that average particle sizes follow the same trend as predicted by the model. Negative terms in the model corresponding to the cross-linking agent and stabilizer indicate the important factors for minimizing particle size.

Ultrasound Contrast Agents

NASA Astrophysics Data System (ADS)

Cachard, Christian; Basset, Olivier

While the use of contrast agents in other imaging modalities (X ray, MRI, PET, …) has been routinely accepted for many years, the development and commercialization of contrast agents designed specifically for ultrasound imaging has occurred only very recently. As in the other imaging modalities, the injection of contrast agents during an ultrasound examination is intended to facilitate the detection and diagnosis of specific pathologies. Contrast agents efficiency is based on the backscattering of ultrasound by microbubbles. These microparticules are intravenously injected in the blood flow. After an introduction and generalities on ultrasound contrast agents (UCA) the microbubble physics in an acoustic field will be developed. Second, physics characteristics of contrast agents will be compared (bubbles with or without shell, gas nature, size distribution). Influence of acoustic pressure on the behaviour of the microparticules (linear, non linear and destruction) will be discussed. Finally, a review of specific imaging adapted to contrast agent properties as harmonic imaging, pulse inversion imaging will be presented.

Daphnia swarms: from single agent dynamics to collective vortex formation

NASA Astrophysics Data System (ADS)

Ordemann, Anke; Balazsi, Gabor; Caspari, Elizabeth; Moss, Frank

2003-05-01

Swarm theories have become fashionable in theoretical physics over the last decade. They span the range of interactions from individual agents moving in a mean field to coherent collective motions of large agent populations, such as vortex-swarming. But controlled laboratory tests of these theories using real biological agents have been problematic due primarily to poorly known agent-agent interactions (in the case of e.g. bacteria and slime molds) or the large swarm size (e.g. for flocks of birds and schools of fish). Moreover, the entire range of behaviors from single agent interactions to collective vortex motions of the swarm have here-to-fore not been observed with a single animal. We present the results of well defined experiments with the zooplankton Daphnia in light fields showing this range of behaviors. We interpret our results with a theory of the motions of self-propelled agents in a field.

Chemical and Biological Sensor Standards Study

DTIC Science & Technology

2005-01-01

that is utilized in lieu of Bacillus anthracis in testing biological agent sensors; both are gram positive, spore forming bacteria that have similar...for a given agent dosage is as follows: C = D r 3 f B Tη4π 3 ρ See the table for the variable designation. Using Bacillus anthracis as an example...e.g., genetic similarity, aerosol dynamics, size, shape, etc.) of the agent of interest. For example, Bacillus globigii is a widely used bacterium

Effect of complexing agents on the electrochemical performance of LiFePO4/C prepared by sol-gel method

PubMed Central

2012-01-01

LiFePO4/C is synthesized via sol-gel method using Fe3+ as iron sources and different complexing agents, followed by sintering at high temperature for crystallization. The amount of carbon in these composites is less than 6.8 wt.%, and the X-ray diffraction experiment confirms that all samples are pure single phase indexed with the orthorhombic Pnma space group. The particle size of the LiFePO4/C synthesized by acetic acid as a complexing agent is very fine with a size of 200 nm. The electrochemical performance of this material, including reversible capacity, cycle number, and charge-discharge characteristics, is better than those of LiFePO4/C synthesized by other complexing agents. The cell of this sample can deliver a discharge capacity of 161.1 mAh g-1 at the first cycle. After 30 cycles, the capacity decreases to 157.5 mAh g-1, and the capacity fading rate is 2.2%. The mechanism is studied to explain the effect of a complexing agent on the synthesis of LiFePO4/C by sol-gel method. The results show that the complexing agent with a low stability constant may be proper for the synthetic process of LiFePO4/C via sol-gel method. PMID:22221711

Effect of crystals and fibrous network polymer additives on cellular morphology of microcellular foams

NASA Astrophysics Data System (ADS)

Miyamoto, Ryoma; Utano, Tatsumi; Yasuhara, Shunya; Ishihara, Shota; Ohshima, Masahiro

2015-05-01

In this study, the core-back foam injection molding was used for preparing microcelluar polypropylene (PP) foam with either a 1,3:2,4 bis-O-(4-methylbenzylidene)-D-sorbitol gelling agent (Gel-all MD) or a fibros network polymer additive (Metablen 3000). Both agent and addiive could effectively control the celluar morphology in foams but somehow different ways. In course of cooling the polymer with Gel-all MD in the mold caity, the agent enhanced the crystal nucleation and resulted in the large number of small crystals. The crystals acted as effective bubble nucleation agent in foaming process. Thus, the agent reduced the cell size and increased the cell density, drastically. Furthermore, the small crystals provided an inhomogenuity to the expanding cell wall and produced the high open cell content with nano-scale fibril structure. Gell-all as well as Metablene 3000 formed a gel-like fibrous network in melt. The network increased the elongational viscosity and tended to prevent the cell wall from breaking up. The foaming temperature window was widened by the presence of the network. Especially, the temperature window where the macro-fibrous structure was formed was expanded to the higher temperature. The effects of crystal nucleating agent and PTFE on crystals' size and number, viscoelsticity, rheological propreties of PP and cellular morphology were compared and thorougly investigated.

Effect of complexing agents on the electrochemical performance of LiFePO4/C prepared by sol-gel method

NASA Astrophysics Data System (ADS)

Yang, Rong; Kang, Erwei; Jiang, Bailing; Ahn, Jou-Hyeon

2012-01-01

LiFePO4/C is synthesized via sol-gel method using Fe3+ as iron sources and different complexing agents, followed by sintering at high temperature for crystallization. The amount of carbon in these composites is less than 6.8 wt.%, and the X-ray diffraction experiment confirms that all samples are pure single phase indexed with the orthorhombic Pnma space group. The particle size of the LiFePO4/C synthesized by acetic acid as a complexing agent is very fine with a size of 200 nm. The electrochemical performance of this material, including reversible capacity, cycle number, and charge-discharge characteristics, is better than those of LiFePO4/C synthesized by other complexing agents. The cell of this sample can deliver a discharge capacity of 161.1 mAh g-1 at the first cycle. After 30 cycles, the capacity decreases to 157.5 mAh g-1, and the capacity fading rate is 2.2%. The mechanism is studied to explain the effect of a complexing agent on the synthesis of LiFePO4/C by sol-gel method. The results show that the complexing agent with a low stability constant may be proper for the synthetic process of LiFePO4/C via sol-gel method.

Analytical solutions for tomato peeling with combined heat flux and convective boundary conditions

NASA Astrophysics Data System (ADS)

Cuccurullo, G.; Giordano, L.; Metallo, A.

2017-11-01

Peeling of tomatoes by radiative heating is a valid alternative to steam or lye, which are expensive and pollutant methods. Suitable energy densities are required in order to realize short time operations, thus involving only a thin layer under the tomato surface. This paper aims to predict the temperature field in rotating tomatoes exposed to the source irradiation. Therefore, a 1D unsteady analytical model is presented, which involves a semi-infinite slab subjected to time dependent heating while convective heat transfer takes place on the exposed surface. In order to account for the tomato rotation, the heat source is described as the positive half-wave of a sinusoidal function. The problem being linear, the solution is derived following the Laplace Transform Method. In addition, an easy-to-handle solution for the problem at hand is presented, which assumes a differentiable function for approximating the source while neglecting convective cooling, the latter contribution turning out to be negligible for the context at hand. A satisfying agreement between the two analytical solutions is found, therefore, an easy procedure for a proper design of the dry heating system can be set up avoiding the use of numerical simulations.

Identification of water soluble and particle bound compounds causing sublethal toxic effects. A field study on sediments affected by a chlor-alkali industry.

PubMed

Bosch, Carme; Olivares, Alba; Faria, Melissa; Navas, Jose M; del Olmo, Iván; Grimalt, Joan O; Piña, Benjamín; Barata, Carlos

2009-08-13

A combination of cost effective sublethal Daphnia magna feeding tests, yeast- and cell culture-based bioassays and Toxicity Identification Evaluation (TIE) procedures was used to characterize toxic compounds within sediments collected in a river area under the influence of the effluents from a chlor-alkali industry (Ebro River, NE Spain). Tests were designed to measure and identify toxic compounds in the particulate and filtered water fractions of sediment elutriates. The combined use of bioassays responding to elutriates and dioxin-like compounds evidenced the existence of three major groups of hazardous contaminants in the most contaminated site: (A) metals such as cadmium and mercury bound to sediment fine particles that could be easily resuspended and moved downstream, (B) soluble compounds (presumably, lye) able to alkalinize water to toxic levels, and (C) organochlorine compounds with high dioxin-like activity. These results provided evidence that elutriate D. magna feeding responses can be used as surrogate assays for more tedious chronic whole sediment tests, and that the incorporation of such tests in sediment TIE procedures may improve the ability to identify the toxicity of particle-bound and water-soluble contaminants in sediments.

An Experimental Study of Hafting Adhesives and the Implications for Compound Tool Technology

PubMed Central

Zipkin, Andrew M.; Wagner, Mark; McGrath, Kate; Brooks, Alison S.; Lucas, Peter W.

2014-01-01

Experimental studies of hafting adhesives and modifications to compound tool components can demonstrate the extent to which human ancestors understood and exploited material properties only formally defined by science within the last century. Discoveries of Stone Age hafting adhesives at archaeological sites in Europe, the Middle East, and Africa have spurred experiments that sought to replicate or create models of such adhesives. Most of these studies, however, have been actualistic in design, focusing on replicating ancient applications of adhesive technology. In contrast, this study tested several glues based on Acacia resin within a materials science framework to better understand the effect of each adhesive ingredient on compound tool durability. Using an overlap joint as a model for a compound tool, adhesives formulated with loading agents from a range of particle sizes and mineral compositions were tested for toughness on smooth and rough substrates. Our results indicated that overlap joint toughness is significantly increased by using a roughened joint surface. Contrary to some previous studies, there was no evidence that particle size diversity in a loading agent improved adhesive effectiveness. Generally, glues containing quartz or ochre loading agents in the silt and clay-sized particle class yielded the toughest overlap joints, with the effect of particle size found to be more significant for rough rather than smooth substrate joints. Additionally, no particular ochre mineral or mineral mixture was found to be a clearly superior loading agent. These two points taken together suggest that Paleolithic use of ochre-loaded adhesives and the criteria used to select ochres for this purpose may have been mediated by visual and symbolic considerations rather than purely functional concerns. PMID:25383871

An experimental study of hafting adhesives and the implications for compound tool technology.

PubMed

Zipkin, Andrew M; Wagner, Mark; McGrath, Kate; Brooks, Alison S; Lucas, Peter W

2014-01-01

Experimental studies of hafting adhesives and modifications to compound tool components can demonstrate the extent to which human ancestors understood and exploited material properties only formally defined by science within the last century. Discoveries of Stone Age hafting adhesives at archaeological sites in Europe, the Middle East, and Africa have spurred experiments that sought to replicate or create models of such adhesives. Most of these studies, however, have been actualistic in design, focusing on replicating ancient applications of adhesive technology. In contrast, this study tested several glues based on Acacia resin within a materials science framework to better understand the effect of each adhesive ingredient on compound tool durability. Using an overlap joint as a model for a compound tool, adhesives formulated with loading agents from a range of particle sizes and mineral compositions were tested for toughness on smooth and rough substrates. Our results indicated that overlap joint toughness is significantly increased by using a roughened joint surface. Contrary to some previous studies, there was no evidence that particle size diversity in a loading agent improved adhesive effectiveness. Generally, glues containing quartz or ochre loading agents in the silt and clay-sized particle class yielded the toughest overlap joints, with the effect of particle size found to be more significant for rough rather than smooth substrate joints. Additionally, no particular ochre mineral or mineral mixture was found to be a clearly superior loading agent. These two points taken together suggest that Paleolithic use of ochre-loaded adhesives and the criteria used to select ochres for this purpose may have been mediated by visual and symbolic considerations rather than purely functional concerns.

Agent-Based Models and Optimal Control in Biology: A Discrete Approach

DTIC Science & Technology

2012-01-01

different parts of the human body to cure diseases such as hypertension, cancer, or heart disease. And we need to control microbes for the efficient...antelope herd interacts with an aggregated prey agent such as cheetahs or lions, the size of each may expand or contract accordingly). Of course, such

Human-Centered Design for the Personal Satellite Assistant

NASA Technical Reports Server (NTRS)

Bradshaw, Jeffrey M.; Sierhuis, Maarten; Gawdiak, Yuri; Thomas, Hans; Greaves, Mark; Clancey, William J.; Swanson, Keith (Technical Monitor)

2000-01-01

The Personal Satellite Assistant (PSA) is a softball-sized flying robot designed to operate autonomously onboard manned spacecraft in pressurized micro-gravity environments. We describe how the Brahms multi-agent modeling and simulation environment in conjunction with a KAoS agent teamwork approach can be used to support human-centered design for the PSA.

Pharmacological activity and toxicity of some neurotropic agents under conditions of experimental hypodynamia

NASA Technical Reports Server (NTRS)

Kirichek, L. T.

1980-01-01

The indices of pharmacological range, risk coefficients, ED50, LD50, the size of the area of toxic activity, and maximal tolerated and absolute lethal doses were compared in hypodynamic mice. The pharmacological activity of the test neurotropic agents exhibiting a central action underwent change, but their toxicity remained unchanged.

Competition of information channels in the spreading of innovations

NASA Astrophysics Data System (ADS)

Kocsis, Gergely; Kun, Ferenc

2011-08-01

We study the spreading of information on technological developments in socioeconomic systems where the social contacts of agents are represented by a network of connections. In the model, agents get informed about the existence and advantages of new innovations through advertising activities of producers, which are then followed by an interagent information transfer. Computer simulations revealed that varying the strength of external driving and of interagent coupling, furthermore, the topology of social contacts, the model presents a complex behavior with interesting novel features: On the macrolevel the system exhibits logistic behavior typical for the diffusion of innovations. The time evolution can be described analytically by an integral equation that captures the nucleation and growth of clusters of informed agents. On the microlevel, small clusters are found to be compact with a crossover to fractal structures with increasing size. The distribution of cluster sizes has a power-law behavior with a crossover to a higher exponent when long-range social contacts are present in the system. Based on computer simulations we construct an approximate phase diagram of the model on a regular square lattice of agents.

Hybrid neural intelligent system to predict business failure in small-to-medium-size enterprises.

PubMed

Borrajo, M Lourdes; Baruque, Bruno; Corchado, Emilio; Bajo, Javier; Corchado, Juan M

2011-08-01

During the last years there has been a growing need of developing innovative tools that can help small to medium sized enterprises to predict business failure as well as financial crisis. In this study we present a novel hybrid intelligent system aimed at monitoring the modus operandi of the companies and predicting possible failures. This system is implemented by means of a neural-based multi-agent system that models the different actors of the companies as agents. The core of the multi-agent system is a type of agent that incorporates a case-based reasoning system and automates the business control process and failure prediction. The stages of the case-based reasoning system are implemented by means of web services: the retrieval stage uses an innovative weighted voting summarization of self-organizing maps ensembles-based method and the reuse stage is implemented by means of a radial basis function neural network. An initial prototype was developed and the results obtained related to small and medium enterprises in a real scenario are presented.

Competition of information channels in the spreading of innovations.

PubMed

Kocsis, Gergely; Kun, Ferenc

2011-08-01

We study the spreading of information on technological developments in socioeconomic systems where the social contacts of agents are represented by a network of connections. In the model, agents get informed about the existence and advantages of new innovations through advertising activities of producers, which are then followed by an interagent information transfer. Computer simulations revealed that varying the strength of external driving and of interagent coupling, furthermore, the topology of social contacts, the model presents a complex behavior with interesting novel features: On the macrolevel the system exhibits logistic behavior typical for the diffusion of innovations. The time evolution can be described analytically by an integral equation that captures the nucleation and growth of clusters of informed agents. On the microlevel, small clusters are found to be compact with a crossover to fractal structures with increasing size. The distribution of cluster sizes has a power-law behavior with a crossover to a higher exponent when long-range social contacts are present in the system. Based on computer simulations we construct an approximate phase diagram of the model on a regular square lattice of agents.

Preparation and evaluation of poly(2-hydroxyethyl aspartamide)-hexadecylamine-iron oxide for MR imaging of lymph nodes

PubMed Central

2014-01-01

The purpose of this study was to synthesize biocompatible poly(2-hydroxyethyl aspartamide)–C16-iron oxide (PHEA-C16-iron oxide) nanoparticles and to evaluate their efficacy as a contrast agent for magnetic resonance imaging of lymph nodes. The PHEA-C16-iron oxide nanoparticles were synthesized by coprecipitation method. The core size of the PHEA-C16-iron oxide nanoparticles was about 5 to 7 nm, and the overall size of the nanoparticles was around 20, 60, and 150 nm in aqueous solution. The size of the nanoparticles was controlled by the amount of C16. The 3.0-T MRI signal intensity of a rabbit lymph node was effectively reduced after intravenous administration of PHEA-C16-iron oxide with the size of 20 nm. The in vitro and in vivo toxicity tests revealed the high biocompatibility of PHEA-C16-iron oxide nanoparticles. Therefore, PHEA-C16-iron oxide nanoparticles with 20-nm size can be potentially useful as T2-weighted MR imaging contrast agents for the detection of lymph nodes. PMID:24438671

Size-dependent magnetic and inductive heating properties of Fe3O4 nanoparticles: scaling laws across the superparamagnetic size.

PubMed

Mohapatra, Jeotikanta; Zeng, Fanhao; Elkins, Kevin; Xing, Meiying; Ghimire, Madhav; Yoon, Sunghyun; Mishra, Sanjay R; Liu, J Ping

2018-05-09

An efficient heat activating mediator with an enhanced specific absorption rate (SAR) value is attained via control of the iron oxide (Fe3O4) nanoparticle size from 3 to 32 nm. Monodispersed Fe3O4 nanoparticles are synthesized via a seed-less thermolysis technique using oleylamine and oleic acid as the multifunctionalizing agents (surfactant, solvent and reducing agent). The inductive heating properties as a function of particle size reveal a strong increase in the SAR values with increasing particle size up to 28 nm. In particular, the SAR values of ferromagnetic nanoparticles (>16 nm) are strongly enhanced with the increase of ac magnetic field amplitude than that for the superparamagnetic (3-16 nm) nanoparticles. The enhanced SAR values in the ferromagnetic regime are attributed to the synergistic contribution from the hysteresis and susceptibility loss. Specifically, the 28 nm Fe3O4 nanoparticles exhibit an enhanced SAR value of 801 W g-1 which is nearly an order higher than that of the commercially available nanoparticles.

Antifungal activity of gold nanoparticles prepared by solvothermal method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahmad, Tokeer, E-mail: tahmad3@jmi.ac.in; Wani, Irshad A.; Lone, Irfan H.

2013-01-15

Graphical abstract: Gold nanoparticles (7 and 15 nm) of very high surface area (329 and 269 m{sup 2}/g) have been successfully synthesized through solvothermal method by using tin chloride and sodium borohydride as reducing agents. As-prepared gold nanoparticles shows very excellent antifungal activity against Candida isolates and activity increases with decrease in the particle size. Display Omitted Highlights: ► Effect of reducing agents on the morphology of gold nanoparticles. ► Highly uniform and monodisperse gold nanoparticles (7 nm). ► Highest surface area of gold nanoparticles (329 m{sup 2/}g). ► Excellent antifungal activity of gold nanoparticles against Candida strains. -- Abstract:more » Gold nanoparticles have been successfully synthesized by solvothermal method using SnCl{sub 2} and NaBH{sub 4} as reducing agents. X-ray diffraction studies show highly crystalline and monophasic nature of the gold nanoparticles with face centred cubic structure. The transmission electron microscopic studies show the formation of nearly spherical gold nanoparticles of average size of 15 nm using SnCl{sub 2}, however, NaBH{sub 4} produced highly uniform, monodispersed and spherical gold nanoparticles of average grain size of 7 nm. A high surface area of 329 m{sup 2}/g for 7 nm and 269 m{sup 2}/g for 15 nm gold nanoparticles was observed. UV–vis studies assert the excitations over the visible region due to transverse and longitudinal surface plasmon modes. The gold nanoparticles exhibit excellent size dependant antifungal activity and greater biocidal action against Candida isolates for 7 nm sized gold nanoparticles restricting the transmembrane H{sup +} efflux of the Candida species than 15 nm sized gold nanoparticles.« less

Synthesis of surface bound silver nanoparticles on cellulose fibers using lignin as multi-functional agent.

PubMed

Hu, Sixiao; Hsieh, You-Lo

2015-10-20

Lignin has proven to be highly effective "green" multi-functional binding, complexing and reducing agents for silver cations as well as capping agents for the synthesis of silver nanoparticles on ultra-fine cellulose fibrous membranes. Silver nanoparticles could be synthesized in 10min to be densely distributed and stably bound on the cellulose fiber surfaces at up to 2.9% in mass. Silver nanoparticle increased in sizes from 5 to 100nm and became more polydispersed in size distribution on larger fibers and with longer synthesis time. These cellulose fiber bound silver nanoparticles did not agglomerate under elevated temperatures and showed improved thermal stability. The presence of alkali lignin conferred moderate UV absorbing ability in both UV-B and UV-C regions whereas the bound silver nanoparticles exhibited excellent antibacterial activities toward Escherichia coli. Copyright © 2015 Elsevier Ltd. All rights reserved.

Antibacterial property of fabrics coated by magnesium-based brucites

NASA Astrophysics Data System (ADS)

Wang, Ying; Sha, Lin; Zhao, Jiao; Li, Qian; Zhu, Yimin; Wang, Ninghui

2017-04-01

A kind of environmental-friendly magnesium-based antibacterial agent was reported for the first time, which was composited by brucites with different particle sizes. The antibacterial fabrics were produced by coating the magnesium-based antibacterial agents on the 260T polyester pongee fabrics with waterborne polyurethane. The coating process was simple, low-cost, and harmless to human health and environment. Characteristics of the antibacterial agents and fabrics were studied by particulate size distribution analyzer (PSDA), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The results demonstrated that the coating layer was covered tightly on the fabrics and compositing of different particles by a certain proportion made full filling of the coating layer. Meanwhile, compositing did not change the structure of brucites. The antibacterial fabrics presented strong antibacterial properties against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), with the reduction percentage of 96.6% and 100%, respectively, and the antibacterial fabrics attained excellent washing durability.

Voter dynamics on an adaptive network with finite average connectivity

NASA Astrophysics Data System (ADS)

Mukhopadhyay, Abhishek; Schmittmann, Beate

2009-03-01

We study a simple model for voter dynamics in a two-party system. The opinion formation process is implemented in a random network of agents in which interactions are not restricted by geographical distance. In addition, we incorporate the rapidly changing nature of the interpersonal relations in the model. At each time step, agents can update their relationships, so that there is no history dependence in the model. This update is determined by their own opinion, and by their preference to make connections with individuals sharing the same opinion and with opponents. Using simulations and analytic arguments, we determine the final steady states and the relaxation into these states for different system sizes. In contrast to earlier studies, the average connectivity (``degree'') of each agent is constant here, independent of the system size. This has significant consequences for the long-time behavior of the model.

Effect of sacrificial agents on the dispersion of metal cocatalysts for photocatalytic hydrogen evolution

NASA Astrophysics Data System (ADS)

Cao, Shaowen; Shen, Baojia; Huang, Qian; Chen, Zhe

2018-06-01

Surface photodeposition of noble metal cocatalyst has been regarded as an effective approach to facilitate the separation of charge carriers and reduce the over-potential of water reduction, thus to enhance the photocatalytic H2-production activities of semiconductor photocatalyst. Herein, the influences of sacrificial agents used in the photodeposition process on the dispersion of noble metal nanoparticles are investigated, via a series of technique of photocatalytic hydrogen evolution test, microstructure analysis and photoelectrochemical measurement. As a result, the sacrificial agents are found to show large impact on the loading amount, particle size and distribution of different metals on the surface of g-C3N4. The real loading amount of Pt and Au is higher in methanol solution than that in triethanolamine solution. Better distribution and smaller size of Pt nanoparticles are achieved in the presence of methanol; while better distribution and smaller size of Au nanoparticles are achieved in the presence of triethanolamine. As a result, quite different charge transfer ability is achieved for the synthesized Pt and Au decorated g-C3N4, which subsequently leads to disparate photocatalytic activities of the same g-C3N4 photocatalyst under various conditions. The finding in this work indicates that the valid deposition content, particle size and distribution of metal cocatalysts should be carefully taken into account when comparing the photocatalytic activities among various samples.

Clinical study to know the efficacy of Amlexanox 5% with other topical Antiseptic, Analgesic and Anesthetic agents in treating minor RAS.

PubMed

Darshan, D D; Kumar, C N Vijay; Kumar, A D Manoj; Manikantan, N S; Balakrishnan, Dhanya; Uthkal, M P

2014-02-01

To evaluate the efficacy of topical antiinflammatory agent (amlexanox 5%), along with topical antiseptic, analgesic, and anesthetic agent (benzalkonium chloride 0.01%, choline salicylate 8.7% and lidocaine hydrochloride 2%), in promoting ulcer healing, decreasing ulcer size, erythema, pain and recurrence in minor RAS. A randomized control trial was conducted on 100 patients of RAS who fulfilled the inclusion criteria. The number, size, erythema and pain with the ulcer were recorded. Visual analogue scale (VAS) and erythema scale were used to record pain and erythema. 50 patients comprising the study group received anti inflammatory paste (amlexanox 5%) applied four times daily and the control group of 50 patients received topical antiseptic, analgesic, and anesthetic agent (benzalkonium chloride 0.01%, choline salicylate 8.7% and lidocaine hydrochloride 2%) paste, patients were evaluated after 3rd, 6th, 9th and on 30th, 60th day for recurrence. The study group had reduction in ulcer number, size; erythema, pain and frequency of ulcers during follow up. The healing period and recurrence of ulceration reduced in both the groups but the study group had significant reduction in 30th and 60th day follow up for recurrence of ulcers. Amlexanox 5% can reduce the frequency, duration and symptoms associated with the aphthous ulcers with no sideeffects attributed to the drug. How to cite the article: Darshan DD, Kumar CN, Kumar AD, Manikantan NS, Balakrishnan D, Uthkal MP. Clinical study to know the efficacy of Amlexanox 5% with other topical Antiseptic, Analgesic and Anesthetic agents in treating minor RAS. J Int Oral Health 2014;6(1);5-11.

Clinical study to know the efficacy of Amlexanox 5% with other topical Antiseptic, Analgesic and Anesthetic agents in treating minor RAS

PubMed Central

Darshan, D D; Kumar, C N Vijay; Kumar, A D Manoj; Manikantan, N S; Balakrishnan, Dhanya; Uthkal, M P

2014-01-01

Background: To evaluate the efficacy of topical antiinflammatory agent (amlexanox 5%), along with topical antiseptic, analgesic, and anesthetic agent (benzalkonium chloride 0.01%, choline salicylate 8.7% and lidocaine hydrochloride 2%), in promoting ulcer healing, decreasing ulcer size, erythema, pain and recurrence in minor RAS. Materials & Methods: A randomized control trial was conducted on 100 patients of RAS who fulfilled the inclusion criteria. The number, size, erythema and pain with the ulcer were recorded. Visual analogue scale (VAS) and erythema scale were used to record pain and erythema. 50 patients comprising the study group received anti inflammatory paste (amlexanox 5%) applied four times daily and the control group of 50 patients received topical antiseptic, analgesic, and anesthetic agent (benzalkonium chloride 0.01%, choline salicylate 8.7% and lidocaine hydrochloride 2%) paste, patients were evaluated after 3rd, 6th, 9th and on 30th, 60th day for recurrence. Results: The study group had reduction in ulcer number, size; erythema, pain and frequency of ulcers during follow up. The healing period and recurrence of ulceration reduced in both the groups but the study group had significant reduction in 30th and 60th day follow up for recurrence of ulcers. Conclusion: Amlexanox 5% can reduce the frequency, duration and symptoms associated with the aphthous ulcers with no sideeffects attributed to the drug. How to cite the article: Darshan DD, Kumar CN, Kumar AD, Manikantan NS, Balakrishnan D, Uthkal MP. Clinical study to know the efficacy of Amlexanox 5% with other topical Antiseptic, Analgesic and Anesthetic agents in treating minor RAS. J Int Oral Health 2014;6(1);5-11. PMID:24653596

Improvement of Technological Properties of a Vegetal Tanning Agent in Gas Discharge Plasma

NASA Astrophysics Data System (ADS)

Khairullin, A. K.; Voznesensky, E. F.; Rakhmatullina, G. R.; Sabirov, A. M.; Tikhonova, N. V.

2017-11-01

The article considers the possibility of modification of the vegetal tanning agent quebracho in the plasma of a radio-frequency induction discharge at low pressure. It is established that plasma treatment leads to a decrease in the size of colloid fractions and a decrease in the molecular weight, while the functionality of the vegetal tanning agent is preserved. Application of the obtained product in the process of leather retanning allows improving its physical, mechanical and consumer properties.

Development of polyimide foams with blowing agents

NASA Technical Reports Server (NTRS)

Gagliani, John (Inventor); Sorathia, Usman A. K. (Inventor); Lee, Raymond (Inventor)

1985-01-01

A method of preparing a polyimide foam which includes the steps of: preparing, foaming, and curing a precursor containing at least one alkyl ester of 3,3'4,4'-benzophenonetetracarboxylic acid; a meta- or para-substituted aromatic diamine; a heterocyclic diamine; an aliphatic diamine; and a solid blowing agent. The blowing agent is added to said precursor in a concentration which is sufficient to effect at least one of the following attributes of the foam: cell size, proportion of open cells, cell density, and indentation load deflection.

Gold Nanoparticles: An Efficient Antimicrobial Agent against Enteric Bacterial Human Pathogen

PubMed Central

Shamaila, Shahzadi; Zafar, Noshin; Riaz, Saira; Sharif, Rehana; Nazir, Jawad; Naseem, Shahzad

2016-01-01

Enteric bacterial human pathogens, i.e., Escherichia coli, Staphylococcus aureus, Bacillus subtilis and Klebsiella pneumoniae, are the major cause of diarrheal infections in children and adults. Their structure badly affects the human immune system. It is important to explore new antibacterial agents instead of antibiotics for treatment. This project is an attempt to explain how gold nanoparticles affect these bacteria. We investigated the important role of the mean particle size, and the inhibition of a bacterium is dose-dependent. Ultra Violet (UV)-visible spectroscopy revealed the size of chemically synthesized gold nanoparticle as 6–40 nm. Atomic force microscopy (AFM) analysis confirmed the size and X-ray diffractometry (XRD) analysis determined the polycrystalline nature of gold nanoparticles. The present findings explained how gold nanoparticles lyse Gram-negative and Gram-positive bacteria. PMID:28335198

Polyol-mediated thermolysis process for the synthesis of MgO nanoparticles and nanowires

NASA Astrophysics Data System (ADS)

Subramania, A.; Vijaya Kumar, G.; Sathiya Priya, A. R.; Vasudevan, T.

2007-06-01

The main aim of this work is to prepare MgO nanoparticles and nanowires by a novel polyol-mediated thermolysis (PMT) process. The influence of different mole concentration of magnesium acetate, polyvinyl pyrrolidone (PVP; capping agent) and ethylene glycol (EG; solvent as well as reducing agent) on the formation of nanoparticles and nanowires and the effect of calcination on the crystalline size of the samples were also examined. The resultant oxide structure, thermal behaviour, size and shape have been studied using x-ray diffraction (XRD) studies, thermal (TG/DTA) analysis and scanning electron microscopy (SEM)/transmission electron microscopy (TEM) respectively.

Ultrasmall water-soluble metal-iron oxide nanoparticles as T1-weighted contrast agents for magnetic resonance imaging.

PubMed

Zeng, Leyong; Ren, Wenzhi; Zheng, Jianjun; Cui, Ping; Wu, Aiguo

2012-02-28

Using an improved hydrolysis method of inorganic salts assisted with water-bath incubation, ultrasmall water-soluble metal-iron oxide nanoparticles (including Fe(3)O(4), ZnFe(2)O(4) and NiFe(2)O(4) nanoparticles) were synthesized in aqueous solutions, which were used as T(1)-weighted contrast agents for magnetic resonance imaging (MRI). The morphology, structure, MRI relaxation properties and cytotoxicity of the as-prepared metal-iron oxide nanoparticles were characterized, respectively. The results showed that the average sizes of nanoparticles were about 4 nm, 4 nm and 5 nm for Fe(3)O(4), ZnFe(2)O(4) and NiFe(2)O(4) nanoparticles, respectively. Moreover, the nanoparticles have good water dispersibility and low cytotoxicity. The MRI test showed the strong T(1)-weighted, but the weak T(2)-weighted MRI performance of metal-iron oxide nanoparticles. The high T(1)-weighted MRI performance can be attributed to the ultrasmall size of metal-iron oxide nanoparticles. Therefore, the as-prepared metal-iron oxide nanoparticles with good water dispersibility and ultrasmall size can have potential applications as T(1)-weighted contrast agent materials for MRI.

Portfolio of automated trading systems: complexity and learning set size issues.

PubMed

Raudys, Sarunas

2013-03-01

In this paper, we consider using profit/loss histories of multiple automated trading systems (ATSs) as N input variables in portfolio management. By means of multivariate statistical analysis and simulation studies, we analyze the influences of sample size (L) and input dimensionality on the accuracy of determining the portfolio weights. We find that degradation in portfolio performance due to inexact estimation of N means and N(N - 1)/2 correlations is proportional to N/L; however, estimation of N variances does not worsen the result. To reduce unhelpful sample size/dimensionality effects, we perform a clustering of N time series and split them into a small number of blocks. Each block is composed of mutually correlated ATSs. It generates an expert trading agent based on a nontrainable 1/N portfolio rule. To increase the diversity of the expert agents, we use training sets of different lengths for clustering. In the output of the portfolio management system, the regularized mean-variance framework-based fusion agent is developed in each walk-forward step of an out-of-sample portfolio validation experiment. Experiments with the real financial data (2003-2012) confirm the effectiveness of the suggested approach.

A challenge for theranostics: is the optimal particle for therapy also optimal for diagnostics?

NASA Astrophysics Data System (ADS)

Dreifuss, Tamar; Betzer, Oshra; Shilo, Malka; Popovtzer, Aron; Motiei, Menachem; Popovtzer, Rachela

2015-09-01

Theranostics is defined as the combination of therapeutic and diagnostic capabilities in the same agent. Nanotechnology is emerging as an efficient platform for theranostics, since nanoparticle-based contrast agents are powerful tools for enhancing in vivo imaging, while therapeutic nanoparticles may overcome several limitations of conventional drug delivery systems. Theranostic nanoparticles have drawn particular interest in cancer treatment, as they offer significant advantages over both common imaging contrast agents and chemotherapeutic drugs. However, the development of platforms for theranostic applications raises critical questions; is the optimal particle for therapy also the optimal particle for diagnostics? Are the specific characteristics needed to optimize diagnostic imaging parallel to those required for treatment applications? This issue is examined in the present study, by investigating the effect of the gold nanoparticle (GNP) size on tumor uptake and tumor imaging. A series of anti-epidermal growth factor receptor conjugated GNPs of different sizes (diameter range: 20-120 nm) was synthesized, and then their uptake by human squamous cell carcinoma head and neck cancer cells, in vitro and in vivo, as well as their tumor visualization capabilities were evaluated using CT. The results showed that the size of the nanoparticle plays an instrumental role in determining its potential activity in vivo. Interestingly, we found that although the highest tumor uptake was obtained with 20 nm C225-GNPs, the highest contrast enhancement in the tumor was obtained with 50 nm C225-GNPs, thus leading to the conclusion that the optimal particle size for drug delivery is not necessarily optimal for imaging. These findings stress the importance of the investigation and design of optimal nanoparticles for theranostic applications.Theranostics is defined as the combination of therapeutic and diagnostic capabilities in the same agent. Nanotechnology is emerging as an efficient platform for theranostics, since nanoparticle-based contrast agents are powerful tools for enhancing in vivo imaging, while therapeutic nanoparticles may overcome several limitations of conventional drug delivery systems. Theranostic nanoparticles have drawn particular interest in cancer treatment, as they offer significant advantages over both common imaging contrast agents and chemotherapeutic drugs. However, the development of platforms for theranostic applications raises critical questions; is the optimal particle for therapy also the optimal particle for diagnostics? Are the specific characteristics needed to optimize diagnostic imaging parallel to those required for treatment applications? This issue is examined in the present study, by investigating the effect of the gold nanoparticle (GNP) size on tumor uptake and tumor imaging. A series of anti-epidermal growth factor receptor conjugated GNPs of different sizes (diameter range: 20-120 nm) was synthesized, and then their uptake by human squamous cell carcinoma head and neck cancer cells, in vitro and in vivo, as well as their tumor visualization capabilities were evaluated using CT. The results showed that the size of the nanoparticle plays an instrumental role in determining its potential activity in vivo. Interestingly, we found that although the highest tumor uptake was obtained with 20 nm C225-GNPs, the highest contrast enhancement in the tumor was obtained with 50 nm C225-GNPs, thus leading to the conclusion that the optimal particle size for drug delivery is not necessarily optimal for imaging. These findings stress the importance of the investigation and design of optimal nanoparticles for theranostic applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr03119b

Intelligent systems in the context of surrounding environment.

PubMed

Wakeling, J; Bak, P

2001-11-01

We investigate the behavioral patterns of a population of agents, each controlled by a simple biologically motivated neural network model, when they are set in competition against each other in the minority model of Challet and Zhang. We explore the effects of changing agent characteristics, demonstrating that crowding behavior takes place among agents of similar memory, and show how this allows unique "rogue" agents with higher memory values to take advantage of a majority population. We also show that agents' analytic capability is largely determined by the size of the intermediary layer of neurons. In the context of these results, we discuss the general nature of natural and artificial intelligence systems, and suggest intelligence only exists in the context of the surrounding environment (embodiment).

Optimized dispersion of ZnO nanoparticles and antimicrobial activity against foodborne pathogens and spoilage microorganisms

NASA Astrophysics Data System (ADS)

Espitia, Paula Judith Perez; Soares, Nilda de Fátima Ferreira; Teófilo, Reinaldo F.; Vitor, Débora M.; Coimbra, Jane Sélia dos Reis; de Andrade, Nélio José; de Sousa, Frederico B.; Sinisterra, Rubén D.; Medeiros, Eber Antonio Alves

2013-01-01

Single primary nanoparticles of zinc oxide (nanoZnO) tend to form particle collectives, resulting in loss of antimicrobial activity. This work studied the effects of probe sonication conditions: power, time, and the presence of a dispersing agent (Na4P2O7), on the size of nanoZnO particles. NanoZnO dispersion was optimized by response surface methodology (RSM) and characterized by the zeta potential (ZP) technique. NanoZnO antimicrobial activity was investigated at different concentrations (1, 5, and 10 % w/w) against four foodborne pathogens and four spoilage microorganisms. The presence of the dispersing agent had a significant effect on the size of dispersed nanoZnO. Minimum size after sonication was 238 nm. An optimal dispersion condition was achieved at 200 W for 45 min of sonication in the presence of the dispersing agent. ZP analysis indicated that the ZnO nanoparticle surface charge was altered by the addition of the dispersing agent and changes in pH. At tested concentrations and optimal dispersion, nanoZnO had no antimicrobial activity against Pseudomonas aeruginosa, Lactobacillus plantarum, and Listeria monocytogenes. However, it did have antimicrobial activity against Escherichia coli, Salmonella choleraesuis, Staphylococcus aureus, Saccharomyces cerevisiae, and Aspergillus niger. Based on the exhibited antimicrobial activity of optimized nanoZnO against some foodborne pathogens and spoilage microorganisms, nanoZnO is a promising antimicrobial for food preservation with potential application for incorporation in polymers intended as food-contact surfaces.

Democracy versus dictatorship in self-organized models of financial markets

NASA Astrophysics Data System (ADS)

D'Hulst, R.; Rodgers, G. J.

2000-06-01

Models to mimic the transmission of information in financial markets are introduced. As an attempt to generate the demand process, we distinguish between dictatorship associations, where groups of agents rely on one of them to make decision, and democratic associations, where each agent takes part in the group decision. In the dictatorship model, agents segregate into two distinct populations, while the democratic model is driven towards a critical state where groups of agents of all sizes exist. Hence, both models display a level of organization, but only the democratic model is self-organized. We show that the dictatorship model generates less-volatile markets than the democratic model.

X-ray spatial frequency heterodyne imaging of protein-based nanobubble contrast agents

PubMed Central

Rand, Danielle; Uchida, Masaki; Douglas, Trevor; Rose-Petruck, Christoph

2014-01-01

Spatial Frequency Heterodyne Imaging (SFHI) is a novel x-ray scatter imaging technique that utilizes nanoparticle contrast agents. The enhanced sensitivity of this new technique relative to traditional absorption-based x-ray radiography makes it promising for applications in biomedical and materials imaging. Although previous studies on SFHI have utilized only metal nanoparticle contrast agents, we show that nanomaterials with a much lower electron density are also suitable. We prepared protein-based “nanobubble” contrast agents that are comprised of protein cage architectures filled with gas. Results show that these nanobubbles provide contrast in SFHI comparable to that of gold nanoparticles of similar size. PMID:25321797

Susceptibility of Legionella pneumophila to twenty antimicrobial agents.

PubMed Central

Edelstein, P H; Meyer, R D

1980-01-01

Thirty-three isolates of Legionella pneumophila, all except one of which were clinical isolates, were tested against 20 antimicrobial agents by using an agar dilution technique. Erythromycin, rifamp]in, and rosaramycin were the most active agents tested. Aminoglycosides, chloramphenicol, and cefoxitin also inhibited the organisms at low concentrations. Other agents, including moxalactam, cefoperazone, and cephalosporins, exhibited moderate to little activity. Tetracycline, doxycycline and minocyeline were apparently inactivated by charcoal-yeast extract medium. There was slight inoculum dependence noted with most of the antimicrobials tested, particularly the beta-lactam agents. There was no consistent difference in susceptibility between Center for Disease Control-supplied stock strains and recent clinical isolates, but there were marked differences with some agents. Susceptibility testing needs to be standardized in view of the influence of inoculum size, strain variation, and the medium used. PMID:7425611

Ecology Based Decentralized Agent Management System

NASA Technical Reports Server (NTRS)

Peysakhov, Maxim D.; Cicirello, Vincent A.; Regli, William C.

2004-01-01

The problem of maintaining a desired number of mobile agents on a network is not trivial, especially if we want a completely decentralized solution. Decentralized control makes a system more r e bust and less susceptible to partial failures. The problem is exacerbated on wireless ad hoc networks where host mobility can result in significant changes in the network size and topology. In this paper we propose an ecology-inspired approach to the management of the number of agents. The approach associates agents with living organisms and tasks with food. Agents procreate or die based on the abundance of uncompleted tasks (food). We performed a series of experiments investigating properties of such systems and analyzed their stability under various conditions. We concluded that the ecology based metaphor can be successfully applied to the management of agent populations on wireless ad hoc networks.

Imaging of vaporised sub-micron phase change contrast agents with high frame rate ultrasound and optics

NASA Astrophysics Data System (ADS)

Lin, Shengtao; Zhang, Ge; Jamburidze, Akaki; Chee, Melisse; Hau Leow, Chee; Garbin, Valeria; Tang, Meng-Xing

2018-03-01

Phase-change ultrasound contrast agent (PCCA), or nanodroplet, shows promise as an alternative to the conventional microbubble agent over a wide range of diagnostic applications. Meanwhile, high-frame-rate (HFR) ultrasound imaging with microbubbles enables unprecedented temporal resolution compared to traditional contrast-enhanced ultrasound imaging. The combination of HFR ultrasound imaging and PCCAs can offer the opportunity to observe and better understand PCCA behaviour after vaporisation captures the fast phenomenon at a high temporal resolution. In this study, we utilised HFR ultrasound at frame rates in the kilohertz range (5-20 kHz) to image native and size-selected PCCA populations immediately after vaporisation in vitro within clinical acoustic parameters. The size-selected PCCAs through filtration are shown to preserve a sub-micron-sized (mean diameter  <  200 nm) population without micron-sized outliers (>1 µm) that originate from native PCCA emulsion. The results demonstrate imaging signals with different amplitudes and temporal features compared to that of microbubbles. Compared with the microbubbles, both the B-mode and pulse-inversion (PI) signals from the vaporised PCCA populations were reduced significantly in the first tens of milliseconds, while only the B-mode signals from the PCCAs were recovered during the next 400 ms, suggesting significant changes to the size distribution of the PCCAs after vaporisation. It is also shown that such recovery in signal over time is not evident when using size-selective PCCAs. Furthermore, it was found that signals from the vaporised PCCA populations are affected by the amplitude and frame rate of the HFR ultrasound imaging. Using high-speed optical camera observation (30 kHz), we observed a change in particle size in the vaporised PCCA populations exposed to the HFR ultrasound imaging pulses. These findings can further the understanding of PCCA behaviour under HFR ultrasound imaging.

46 CFR 193.15-5 - Quantity, pipe sizes, and discharge rates.

Code of Federal Regulations, 2013 CFR

2013-10-01

... VESSELS FIRE PROTECTION EQUIPMENT Carbon Dioxide and Clean Agent Extinguishing Systems, Details § 193.15-5 Quantity, pipe sizes, and discharge rates. (a) General. The amount of carbon dioxide required for each.... A separate supply of carbon dioxide need not be provided for each space protected. The total...

46 CFR 193.15-5 - Quantity, pipe sizes, and discharge rates.

Code of Federal Regulations, 2014 CFR

2014-10-01

... VESSELS FIRE PROTECTION EQUIPMENT Carbon Dioxide and Clean Agent Extinguishing Systems, Details § 193.15-5 Quantity, pipe sizes, and discharge rates. (a) General. The amount of carbon dioxide required for each.... A separate supply of carbon dioxide need not be provided for each space protected. The total...

Determination and validation of six sunscreen agents in suncare products by UPLC and HPLC.

PubMed

Lee, So-Mi; Jeong, Hye-Jin; Chang, Ih Seop

2008-01-01

Methylene bis-benzotriazolyl tetramethyl butylphenol and bis-ethylhexyloxy phenol methoxyphenyl triazine are sunscreen agents that have hydrophobic behaviors in common. They were not normally assayed with the following four sunscreen agents that have hydrophilic behaviors in a single chromatographic run: ethylhexyl methoxycinnamate, isoamyl p-methoxycinnamate, ethylhexyl salicylate, and ethylhexyl triazone. For that reason, methylene bis-benzotriazolyl tetramethyl butylphenol and bis-ethylhexyloxy phenol methoxyphenyl triazine require much time in order to assay products with those materials. A rapid, selective, and reproducible determination method needs to be developed for the simultaneous examination of methylene bis-benzotriazolyl tetramethyl butylphenol and bis-ethylhexyloxy phenol methoxyphenyl triazine with the sunscreen agents, ethylhexyl methoxycinnamate, isoamyl p-methoxycinnamate, ethylhexyl salicylate, and ethylhexyl triazone. This new technique could reduce time in examining the sunscreen agents and be effective for quality control of suncare products. In this paper, the HPLC and UPLC system is used for developing the determination of the sunscreen agents. Several evaluations of some mixtures of eluents and columns were obtained for the optimal condition of separation. In HPLC, the optimal peak resolution was obtained through ethanol-water gradient elution and a 75-mm C18 column with a 3.5-microm-sized particle on a flow rate of 1.0 ml/min. In UPLC, the most distinctive peak resolution was obtained through methanol-water gradient elution and a 50-mm C18 column with a 1.7-microm-sized particle on a flow rate 0.4 ml/min. Both of those chromatographic determination methods could be used in the examination of six types of sunscreen agents without any interference from other product excipients in the agents. The proposed determination methods were validated for specificity, linearity, repeatability, system stability, intermediate precision, and accuracy. Consequently, HPLC and UPLC determination methods could be rapid, selective, and proper applications for the assay of sunscreen agents in suncare products.

Preparation and characterization of safe microparticles based on xylan.

PubMed

Cartaxo da Costa Urtiga, Silvana; Aquino Azevedo de Lucena Gabi, Camilla; Rodrigues de Araújo Eleamen, Giovanna; Santos Souza, Bartolomeu; Pessôa, Hilzeth de Luna Freire; Marcelino, Henrique Rodrigues; Afonso de Moura Mendonça, Elisângela; Egito, Eryvaldo Sócrates Tabosa do; Oliveira, Elquio Eleamen

2017-10-01

This work describes the preparation and evaluation of safe xylan-based microparticles prepared by cross-linking polymerization using sodium trimetaphosphate. The resulting microparticles were evaluated for morphology, particle size, polymer-cross-link agent interaction, and in vitro toxicity. The microparticles showed narrow monodisperse size distributions with their mean sizes being between 3.5 and 12.5 µm in dried state. FT-IR analyzes confirmed the interaction between sodium trimetaphosphate and xylan during the cross-linking process with formation of phosphate ester bonds. Additionally, the X-ray diffraction patterns and FT-IR analyzes suggested that little or no cross-linking agent remained inside the microparticles. Furthermore, the in-vitro studies using Artemia salina and human erythrocytes revealed that the microparticles are not toxic. Therefore, the overall results suggest that these xylan microparticles can be used as a platform for new drug delivery system.

The dispersion of fine chitosan particles by beads-milling

NASA Astrophysics Data System (ADS)

Rochima, Emma; Utami, Safira; Hamdani, Herman; Azhary, Sundoro Yoga; Praseptiangga, Danar; Joni, I. Made; Panatarani, Camellia

2018-02-01

This research aimed to produce fine chitosan particles from a crab shell waste by beads-milling method by two different concentration of PEG as dispersing agent (150 and 300 wt. %). The characterization was performed to obtain the size and size distribution, the characteristics of functional groups and the degree of deacetylation. The results showed that the chitosan fine particles was obtained with a milling time 120 minutes with the best concentration of PEG 400 150 wt. %. The average particle size of the as-prepared suspension is 584 nm after addition of acetic acid solution (1%, v/v). Beads milling process did not change the glucosamine and N-acetylglucosamine content on chitosan structure which is indicated by degree of deacetylation higher than 70%. It was concluded that beads milling process can be applied to prepare chitosan fineparticles by proper adjustment in the milling time, pH and dosage of dispersing agent.

Thermochromic microcapsules with highly transparent shells obtained through in-situ polymerization of urea formaldehyde around thermochromic cores for smart wood coatings.

PubMed

Zhu, Xiaodong; Liu, Yu; Li, Zhao; Wang, Weicong

2018-03-05

In this paper, thermochromic microcapsules were synthesized in situ polymerization with urea formaldehyde as shell material and thermochromic compounds as core material. The effects of emulsifying agent and conditions on surface morphology and particle size of microcapsules were studied. It was found that the size and surface morphology of microcapsules were strongly depending on stirring rate and the ratio of core to shell. The stable and small size spherical microcapsules with excellent transparency can be obtained at an emulsifying agent to core to shell ratio as 1:5:7.5 under mechanical stirring at 12 krpm for 15 min. Finally, the thermochromic property was discussed by loading microcapsules in wood and wood coatings. Results indicate that microcapsules can realize the thermochromic property while incorporated with wood and coatings, and could have high potential in smart material fabrication.

Entropic determination of the phase transition in a coevolving opinion-formation model.

PubMed

Burgos, E; Hernández, Laura; Ceva, H; Perazzo, R P J

2015-03-01

We study an opinion formation model by the means of a coevolving complex network where the vertices represent the individuals, characterized by their evolving opinions, and the edges represent the interactions among them. The network adapts to the spreading of opinions in two ways: not only connected agents interact and eventually change their thinking but an agent may also rewire one of its links to a neighborhood holding the same opinion as his. The dynamics, based on a global majority rule, depends on an external parameter that controls the plasticity of the network. We show how the information entropy associated to the distribution of group sizes allows us to locate the phase transition between a phase of full consensus and another, where different opinions coexist. We also determine the minimum size of the most informative sampling. At the transition the distribution of the sizes of groups holding the same opinion is scale free.

Hyper alginate gel microbead formation by molecular diffusion at the hydrogel/droplet interface.

PubMed

Hirama, Hirotada; Kambe, Taisuke; Aketagawa, Kyouhei; Ota, Taku; Moriguchi, Hiroyuki; Torii, Toru

2013-01-15

We report a simple method for forming monodispersed, uniformly shaped gel microbeads with precisely controlled sizes. The basis of our method is the placement of monodispersed sodium alginate droplets, formed by a microfluidic device, on an agarose slab gel containing a high-osmotic-pressure gelation agent (CaCl(2) aq.): (1) the droplets are cross-linked (gelated) due to the diffusion of the gelation agent from the agarose slab gel to the sodium alginate droplets and (2) the droplets simultaneously shrink to a fraction of their original size (<100 μm in diameter) due to the diffusion of water molecules from the sodium alginate droplets to the agarose slab gel. We verified the mass transfer mechanism between the droplet and the agarose slab gel. This method circumvents the limitations of gel microbead formation, such as the need to prepare microchannels of various sizes, microchannel clogging, and the deformation of the produced gel microbeads.

Exchanging large data object in multi-agent systems

NASA Astrophysics Data System (ADS)

Al-Yaseen, Wathiq Laftah; Othman, Zulaiha Ali; Nazri, Mohd Zakree Ahmad

2016-08-01

One of the Business Intelligent solutions that is currently in use is the Multi-Agent System (MAS). Communication is one of the most important elements in MAS, especially for exchanging large low level data between distributed agents (physically). The Agent Communication Language in JADE has been offered as a secure method for sending data, whereby the data is defined as an object. However, the object cannot be used to send data to another agent in a different location. Therefore, the aim of this paper was to propose a method for the exchange of large low level data as an object by creating a proxy agent known as a Delivery Agent, which temporarily imitates the Receiver Agent. The results showed that the proposed method is able to send large-sized data. The experiments were conducted using 16 datasets ranging from 100,000 to 7 million instances. However, for the proposed method, the RAM and the CPU machine had to be slightly increased for the Receiver Agent, but the latency time was not significantly different compared to the use of the Java Socket method (non-agent and less secure). With such results, it was concluded that the proposed method can be used to securely send large data between agents.

Effect of contrasting agents on survival, performance, and condition of larval hybrid striped bass Morone chrysops x M. saxatilis in tanks

USDA-ARS?s Scientific Manuscript database

Contrasting agents, either algae or inert soil, cause turbidity, which is important in the tank culture of larval cannibalistic fish. Optimization of turbidity is critical to successful tank culture of new larval fish, which should include 100 mg/L of sub 5 um particle size in the assessed range. ...

Effect of contrasting agents on survival, performance, and condition of larval hybrid striped bass Morone chrysops x M. saxatilis in tanks.

USDA-ARS?s Scientific Manuscript database

Turbidity is important in the tank culture of larval cannibalistic fish. The principal goal of these studies were to characterize the utility and feasibility of select contrasting agents, either algae or inert soil, at improving sunshine bass survival and uniformity of size at time of weaning to an ...

Preparation and characterization of coating sodium trisilicate (Na2O.nSiO2) at calcium carbonate (CaCO3) for blowing agent in Mg alloy foam

NASA Astrophysics Data System (ADS)

Erryani, Aprilia; Lestari, Franciska Pramuji; Annur, Dhyah; Kartika, Ika

2018-05-01

The role of blowing agent in the manufacture of porous metal alloys is very important to produce the desired pore. The thermal stability and speed of foam formation have an effect on the resulting pore structure. In porous metal alloys, uniformity of size and pore deployment are the main determinants of the resulting alloys. The coating process of calcium carbonate (CaCO3) has been done using Sodium trisilicate solution by sol-gel method. Foaming agent was pretreated by coating SiO2 passive layer on the surface of CaCO3. This coating aims to produce a more stable blowing agent so that the foaming process can produce a more uniform pore size. The microstructure of the SiO2 passive was observed using Scanning Electron Microscope (SEM) equipped by Energy Dispersive X-Ray Spectrometer (EDS) mapping. The results showed coating CaCO3 using sodium trisilicate was successfully done creating a passive layer of SiO2 on the surface of CaCO3. By the coating process, the thermal stability of coated CaCO3 increased compared to uncoated CaCO3.

The efficacy of nonestrogenic therapy to hot flashes in cancer patients under hormone manipulation therapy: a systematic review and meta-analysis.

PubMed

Yamaguchi, N; Okajima, Y; Fujii, T; Natori, A; Kobayashi, D

2013-10-01

The incidence of hot flashes under hormone manipulation therapy is so high that this symptom caused by sex hormone blocking agents has been bothering patients and has a negative impact on their quality of life. Venlafaxine and gabapentin are most promising novel nonestrogenic agents to control the symptom. We seek to quatitatively summarize the efficacy of these novel agents. We conducted a meta-analysis of randomized controlled studies on the efficacy of venlafaxine/gabapentin to hot flashes in cancer patient under hormone deprivation therapies. A search for Medline, Embase, Cochrane Central Register of Controlled Trials, Ichushi, and Google Scholar yielded 733 citations, which were independently assessed by two authors. We estimated overall effect sizes and its 95 % confidence intervals (CI) for the efficacy of these agents compared with the controls with standardized mean difference. A total of 5 studies involving 588 cancer patients with hot flashes finally fulfilled the predefined inclusion criteria. Overall effect size of the efficacy of venlafaxine/gabapentin was -0.630 (95 % CI [-0.801, -0.459]). Venlafaxine/gabapentin significantly improved hot flashes in cancer patients under hormone manipulation therapies.

Role of macromolecular crowding and salt ions on the structural-fluctuation of a highly compact configuration of carbonmonoxycytochrome c.

PubMed

Kumar, Rajesh; Sharma, Deepak; Jain, Rishu; Kumar, Sandeep; Kumar, Rajesh

2015-12-01

Carbonmonoxycytochrome c refolds to a native-like compact state (NCO-state), where the non-native Fe(2+)-CO interaction persists. Structural and molecular properties extracted from CD, fluorescence and NMR experiments reveal that the NCO-state shows the generic properties of molten globules. Slow thermal-dissociation of CO transforms the NCO-state to native-state (N-state), where the native Fe(2+)-M80 bond recovers. To determine the role of crowding agents and salt ions on the structural-fluctuation of NCO, the kinetic and thermodynamic parameters for CO-dissociation from NCO (NCO→N+CO) were measured at varying concentrations of crowding agents (dextran 70, dextran 40, ficoll 70) and salt ions (anion: ClO4(-), I(-), Br(-), NO3(-), Cl(-); cation: NH4(+), K(+), Na(+)). As [crowding agent] or [ion] is increased, the rate coefficient of CO-dissociation (kdiss) decreases exponentially. Furthermore, the extent of decrease in kdiss is found to be dependent on (i) size, charge density and charge dispersion of the ion, and (ii) size, shape, and viscosity of the crowding agent. Copyright © 2015 Elsevier B.V. All rights reserved.

Simpler grammar, larger vocabulary: How population size affects language

PubMed Central

2018-01-01

Languages with many speakers tend to be structurally simple while small communities sometimes develop languages with great structural complexity. Paradoxically, the opposite pattern appears to be observed for non-structural properties of language such as vocabulary size. These apparently opposite patterns pose a challenge for theories of language change and evolution. We use computational simulations to show that this inverse pattern can depend on a single factor: ease of diffusion through the population. A population of interacting agents was arranged on a network, passing linguistic conventions to one another along network links. Agents can invent new conventions, or replicate conventions that they have previously generated themselves or learned from other agents. Linguistic conventions are either Easy or Hard to diffuse, depending on how many times an agent needs to encounter a convention to learn it. In large groups, only linguistic conventions that are easy to learn, such as words, tend to proliferate, whereas small groups where everyone talks to everyone else allow for more complex conventions, like grammatical regularities, to be maintained. Our simulations thus suggest that language, and possibly other aspects of culture, may become simpler at the structural level as our world becomes increasingly interconnected. PMID:29367397

Impacts of memory on a regular lattice for different population sizes with asynchronous update in spatial snowdrift game

NASA Astrophysics Data System (ADS)

Shu, Feng; Liu, Xingwen; Li, Min

2018-05-01

Memory is an important factor on the evolution of cooperation in spatial structure. For evolutionary biologists, the problem is often how cooperation acts can emerge in an evolving system. In the case of snowdrift game, it is found that memory can boost cooperation level for large cost-to-benefit ratio r, while inhibit cooperation for small r. Thus, how to enlarge the range of r for the purpose of enhancing cooperation becomes a hot issue recently. This paper addresses a new memory-based approach and its core lies in: Each agent applies the given rule to compare its own historical payoffs in a certain memory size, and take the obtained maximal one as virtual payoff. In order to get the optimal strategy, each agent randomly selects one of its neighbours to compare their virtual payoffs, which can lead to the optimal strategy. Both constant-size memory and size-varying memory are investigated by means of a scenario of asynchronous updating algorithm on regular lattices with different sizes. Simulation results show that this approach effectively enhances cooperation level in spatial structure and makes the high cooperation level simultaneously emerge for both small and large r. Moreover, it is discovered that population sizes have a significant influence on the effects of cooperation.

Pinched flow fractionation of microbubbles for ultrasound contrast agent enrichment

NASA Astrophysics Data System (ADS)

Versluis, Michel; Kok, Maarten; Segers, Tim

2014-11-01

An ultrasound contrast agent (UCA) suspension contains a wide size distribution of encapsulated microbubbles (typically 1-10 μm in diameter) that resonate to the driving ultrasound field by the intrinsic relationship between bubble size and ultrasound frequency. Medical transducers, however, operate in a narrow frequency range, which severely limits the number of bubbles that contribute to the echo signal. Thus, the sensitivity can be improved by narrowing down the size distribution of the bubble suspension. Here, we present a novel, low-cost, lab-on-a-chip method for the sorting of contrast microbubbles by size, based on a microfluidic separation technique known as pinched flow fractionation (PFF). We show by experimental and numerical investigation that the inclusion of particle rotation is essential for an accurate physical description of the sorting behavior of the larger bubbles. Successful sorting of a bubble suspension with a narrow size distribution (3.0 +/- 0.6 μm) has been achieved with a PFF microdevice. This sorting technique can be easily parallelized, and may lead to a significant improvement in the sensitivity of contrast-enhanced medical ultrasound. This work is supported by NanoNextNL, a micro and nanotechnology consortium of the Government of the Netherlands and 130 partners.

The effect of nanoparticle size on theranostic systems: the optimal particle size for imaging is not necessarily optimal for drug delivery

NASA Astrophysics Data System (ADS)

Dreifuss, Tamar; Betzer, Oshra; Barnoy, Eran; Motiei, Menachem; Popovtzer, Rachela

2018-02-01

Theranostics is an emerging field, defined as combination of therapeutic and diagnostic capabilities in the same material. Nanoparticles are considered as an efficient platform for theranostics, particularly in cancer treatment, as they offer substantial advantages over both common imaging contrast agents and chemotherapeutic drugs. However, the development of theranostic nanoplatforms raises an important question: Is the optimal particle for imaging also optimal for therapy? Are the specific parameters required for maximal drug delivery, similar to those required for imaging applications? Herein, we examined this issue by investigating the effect of nanoparticle size on tumor uptake and imaging. Anti-epidermal growth factor receptor (EGFR)-conjugated gold nanoparticles (GNPs) in different sizes (diameter range: 20-120 nm) were injected to tumor bearing mice and their uptake by tumors was measured, as well as their tumor visualization capabilities as tumor-targeted CT contrast agent. Interestingly, the results showed that different particles led to highest tumor uptake or highest contrast enhancement, meaning that the optimal particle size for drug delivery is not necessarily optimal for tumor imaging. These results have important implications on the design of theranostic nanoplatforms.

Agent-Based Simulation for Interconnection-Scale Renewable Integration and Demand Response Studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chassin, David P.; Behboodi, Sahand; Crawford, Curran

This paper collects and synthesizes the technical requirements, implementation, and validation methods for quasi-steady agent-based simulations of interconnectionscale models with particular attention to the integration of renewable generation and controllable loads. Approaches for modeling aggregated controllable loads are presented and placed in the same control and economic modeling framework as generation resources for interconnection planning studies. Model performance is examined with system parameters that are typical for an interconnection approximately the size of the Western Electricity Coordinating Council (WECC) and a control area about 1/100 the size of the system. These results are used to demonstrate and validate the methodsmore » presented.« less

Agent-Based Simulation for Interconnection-Scale Renewable Integration and Demand Response Studies

DOE PAGES

Chassin, David P.; Behboodi, Sahand; Crawford, Curran; ...

2015-12-23

This paper collects and synthesizes the technical requirements, implementation, and validation methods for quasi-steady agent-based simulations of interconnectionscale models with particular attention to the integration of renewable generation and controllable loads. Approaches for modeling aggregated controllable loads are presented and placed in the same control and economic modeling framework as generation resources for interconnection planning studies. Model performance is examined with system parameters that are typical for an interconnection approximately the size of the Western Electricity Coordinating Council (WECC) and a control area about 1/100 the size of the system. These results are used to demonstrate and validate the methodsmore » presented.« less

Spontaneous formation of Au-Pt alloyed nanoparticles using pure nano-counterparts as starters: a ligand and size dependent process.

PubMed

Usón, Laura; Sebastian, Victor; Mayoral, Alvaro; Hueso, Jose L; Eguizabal, Adela; Arruebo, Manuel; Santamaria, Jesus

2015-06-14

In this work we investigate the formation of PtAu monodisperse alloyed nanoparticles by ageing pure metallic Au and Pt small nanoparticles (sNPs), nanoparticle size <5 nm, under certain conditions. We demonstrate that those bimetallic entities can be obtained by controlling the size of the initial metallic sNPs separately prepared and by selecting their appropriate capping agents. The formation of this spontaneous phenomenon was studied using HR-STEM, EDS, ionic conductivity, UV-Vis spectroscopy and cyclic voltammetry. Depending on the type of capping agent used and the size of the initial Au sNPs, three different materials were obtained: (i) AuPt bimetallic sNPs showing a surface rich in Au atoms, (ii) segregated Au and Pt sNPs and (iii) a mixture of bimetallic nanoparticles as well as Pt sNPs and Au NPs. Surface segregation energies and the nature of the reaction environment are the driving forces to direct the distribution of atoms in the bimetallic sNPs. PtAu alloyed nanoparticles were obtained after 150 h of reaction at room temperature if a weak capping agent was used for the stabilization of the nanoparticles. It was also found that Au atoms diffuse towards Pt sNPs, producing a surface enriched in Au atoms. This study shows that even pure nanoparticles are prone to be modified by the surrounding nanoparticles to give rise to new nanomaterials if atomic diffusion is feasible.

A Financial Market Model Incorporating Herd Behaviour.

PubMed

Wray, Christopher M; Bishop, Steven R

2016-01-01

Herd behaviour in financial markets is a recurring phenomenon that exacerbates asset price volatility, and is considered a possible contributor to market fragility. While numerous studies investigate herd behaviour in financial markets, it is often considered without reference to the pricing of financial instruments or other market dynamics. Here, a trader interaction model based upon informational cascades in the presence of information thresholds is used to construct a new model of asset price returns that allows for both quiescent and herd-like regimes. Agent interaction is modelled using a stochastic pulse-coupled network, parametrised by information thresholds and a network coupling probability. Agents may possess either one or two information thresholds that, in each case, determine the number of distinct states an agent may occupy before trading takes place. In the case where agents possess two thresholds (labelled as the finite state-space model, corresponding to agents' accumulating information over a bounded state-space), and where coupling strength is maximal, an asymptotic expression for the cascade-size probability is derived and shown to follow a power law when a critical value of network coupling probability is attained. For a range of model parameters, a mixture of negative binomial distributions is used to approximate the cascade-size distribution. This approximation is subsequently used to express the volatility of model price returns in terms of the model parameter which controls the network coupling probability. In the case where agents possess a single pulse-coupling threshold (labelled as the semi-infinite state-space model corresponding to agents' accumulating information over an unbounded state-space), numerical evidence is presented that demonstrates volatility clustering and long-memory patterns in the volatility of asset returns. Finally, output from the model is compared to both the distribution of historical stock returns and the market price of an equity index option.

Anti-inflammatory agents in the treatment of bipolar depression: a systematic review and meta-analysis.

PubMed

Rosenblat, Joshua D; Kakar, Ron; Berk, Michael; Kessing, Lars V; Vinberg, Maj; Baune, Bernhard T; Mansur, Rodrigo B; Brietzke, Elisa; Goldstein, Benjamin I; McIntyre, Roger S

2016-03-01

Inflammation has been implicated in the risk, pathophysiology, and progression of mood disorders and, as such, has become a target of interest in the treatment of bipolar disorder (BD). Therefore, the objective of the current qualitative and quantitative review was to determine the overall antidepressant effect of adjunctive anti-inflammatory agents in the treatment of bipolar depression. Completed and ongoing clinical trials of anti-inflammatory agents for BD published prior to 15 May 15 2015 were identified through searching the PubMed, Embase, PsychINFO, and Clinicaltrials.gov databases. Data from randomized controlled trials (RCTs) assessing the antidepressant effect of adjunctive mechanistically diverse anti-inflammatory agents were pooled to determine standard mean differences (SMDs) compared with standard therapy alone. Ten RCTs were identified for qualitative review. Eight RCTs (n = 312) assessing adjunctive nonsteroidal anti-inflammatory drugs (n = 53), omega-3 polyunsaturated fatty acids (n = 140), N-acetylcysteine (n = 76), and pioglitazone (n = 44) in the treatment of BD met the inclusion criteria for quantitative analysis. The overall effect size of adjunctive anti-inflammatory agents on depressive symptoms was -0.40 (95% confidence interval -0.14 to -0.65, p = 0.002), indicative of a moderate and statistically significant antidepressant effect. The heterogeneity of the pooled sample was low (I² = 14%, p = 0.32). No manic/hypomanic induction or significant treatment-emergent adverse events were reported. Overall, a moderate antidepressant effect was observed for adjunctive anti-inflammatory agents compared with conventional therapy alone in the treatment of bipolar depression. The small number of studies, diversity of agents, and small sample sizes limited interpretation of the current analysis. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Fabrication and evaluation of tumor-targeted positive MRI contrast agent based on ultrasmall MnO nanoparticles.

PubMed

Huang, Haitao; Yue, Tao; Xu, Ke; Golzarian, Jafar; Yu, Jiahui; Huang, Jin

2015-07-01

Gd(III) chelate is currently used as positive magnetic resonance imaging (MRI) contrast agent in clinical diagnosis, but generally induces the risk of nephrogenic systemic fibrosis (NSF) due to the dissociated Gd(3+) from Gd(III) chelates. To develop a novel positive MRI contrast agent with low toxicity and high sensitivity, ultrasmall MnO nanoparticles were PEGylated via catechol-Mn chelation and conjugated with cRGD as active targeting function to tumor. Particularly, the MnO nanoparticles with a size of ca. 5nm were modified by α,β-poly(aspartic acid)-based graft polymer containing PEG and DOPA moieties and, meanwhile, conjugated with cRGD to produce the contrast agent with a size of ca. 100nm and a longitudinal relaxivity (r1) of 10.2mM(-1)S(-1). Such nanoscaled contrast agent integrated passive- and active-targeting function to tumor, and its efficient accumulation behavior in tumor was verified by in vivo distribution study. At the same time, the PEG moiety played a role of hydrophilic coating to improve the biocompatibility and stability under storing and physiological conditions, and especially might guarantee enough circulation time in blood. Moreover, in vivo MRI revealed a good and long-term effect of enhancing MRI signal for as-fabricated contrast agent while cell viability assay proved its acceptable cytotoxicity for MRI application. On the whole, the as-fabricated PEGylated and cRGD-functionalized contrast agent based on ultrasmall MnO nanoparticles showed a great potential to the T1-weighted MRI diagnosis of tumor. Crown Copyright © 2015. Published by Elsevier B.V. All rights reserved.

Study of 2219 aluminum alloy using direct current A-TIG welding

NASA Astrophysics Data System (ADS)

Li, Hui; Zou, Jiasheng

2017-07-01

Direct current A-TIG (DCEN A-TIG) welding using special active agent had eliminated the pores and the oxidation of 2219 high-strength aluminum alloy in welding. Addition of AlF3-25% LiF active agent to DCEN A-TIG welding and arc morphology showed a trailing phenomenon. However, the change in arc morphology was not remarkable when AlF3-75% LiF active agent was added. Addition of AlF3-75% LiF active agent can refine the grain size of DCEN A-TIG joint. The mechanical properties of the weld were optimal at 10% AlF3-75% LiF active agent. Compared with AC TIG and AC A-TIG welding, DCEN A-TIG welding yielded better results for 2219 Al alloy.

Neem oil (Azadirachta indica) nanoemulsion--a potent larvicidal agent against Culex quinquefasciatus.

PubMed

Anjali, C H; Sharma, Yamini; Mukherjee, Amitava; Chandrasekaran, Natarajan

2012-02-01

Nanoemulsion composed of neem oil and non-ionic surfactant Tween 20, with a mean droplet size ranging from 31.03 to 251.43 nm, was formulated for various concentrations of the oil and surfactant. The larvicidal effect of the formulated neem oil nanoemulsion was checked against Culex quinquefasciatus. O/W emulsion was prepared using neem oil, Tween 20 and water. Nanoemulsion of 31.03 nm size was obtained at a 1:3 ratio of oil and surfactant, and it was found to be stable. The larger droplet size (251.43 nm) shifted to a smaller size of 31.03 nm with increase in the concentration of Tween 20. The viscosity of the nanoemulsion increased with increasing concentration of Tween 20. The lethal concentration (LC50) of the nanoemulsion against Cx. quinquefasciatus was checked for 1:0.30, 1:1.5 and 1:3 ratios of oil and surfactant respectively. The LC50 decreased with droplet size. The LC50 for the ratio 1:3 nanoemulsions was 11.75 mg L(-1). The formulated nanoemulsion of 31.03 nm size was found to be an effective larvicidal agent. This is the first time that a neem oil nanoemulsion of this droplet size has been reported. It may be a good choice as a potent and selective larvicide for Cx. quinquefasciatus. Copyright © 2011 Society of Chemical Industry.

Markov Tracking for Agent Coordination

NASA Technical Reports Server (NTRS)

Washington, Richard; Lau, Sonie (Technical Monitor)

1998-01-01

Partially observable Markov decision processes (POMDPs) axe an attractive representation for representing agent behavior, since they capture uncertainty in both the agent's state and its actions. However, finding an optimal policy for POMDPs in general is computationally difficult. In this paper we present Markov Tracking, a restricted problem of coordinating actions with an agent or process represented as a POMDP Because the actions coordinate with the agent rather than influence its behavior, the optimal solution to this problem can be computed locally and quickly. We also demonstrate the use of the technique on sequential POMDPs, which can be used to model a behavior that follows a linear, acyclic trajectory through a series of states. By imposing a "windowing" restriction that restricts the number of possible alternatives considered at any moment to a fixed size, a coordinating action can be calculated in constant time, making this amenable to coordination with complex agents.

Effect of Temperature on the Size Distribution, Shell Properties, and Stability of Definity®.

PubMed

Shekhar, Himanshu; Smith, Nathaniel J; Raymond, Jason L; Holland, Christy K

2018-02-01

Physical characterization of an ultrasound contrast agent (UCA) aids in its safe and effective use in diagnostic and therapeutic applications. The goal of this study was to investigate the impact of temperature on the size distribution, shell properties, and stability of Definity ® , a U.S. Food and Drug Administration-approved UCA used for left ventricular opacification. A Coulter counter was modified to enable particle size measurements at physiologic temperatures. The broadband acoustic attenuation spectrum and size distribution of Definity ® were measured at room temperature (25 °C) and physiologic temperature (37 °C) and were used to estimate the viscoelastic shell properties of the agent at both temperatures. Attenuation and size distribution was measured over time to assess the effect of temperature on the temporal stability of Definity ® . The attenuation coefficient of Definity ® at 37 °C was as much as 5 dB higher than the attenuation coefficient measured at 25 °C. However, the size distributions of Definity ® at 25 °C and 37 °C were similar. The estimated shell stiffness and viscosity decreased from 1.76 ± 0.18 N/m and 0.21 × 10 -6  ± 0.07 × 10 -6 kg/s at 25 °C to 1.01 ± 0.07 N/m and 0.04 × 10 -6  ± 0.04 × 10 -6 kg/s at 37 °C, respectively. Size-dependent differences in dissolution rates were observed within the UCA population at both 25 °C and 37 °C. Additionally, cooling the diluted UCA suspension from 37 °C to 25 °C accelerated the dissolution rate. These results indicate that although temperature affects the shell properties of Definity ® and can influence the stability of Definity ® , the size distribution of this agent is not affected by a temperature increase from 25 °C to 37 °C. Copyright © 2018 World Federation for Ultrasound in Medicine and Biology. Published by Elsevier Inc. All rights reserved.

Impacts of the Psyllid Arytinnis hakani (Homoptera: Psyllidae) on Invasive French Broom in Relation to Plant Size and Psyllid Density.

PubMed

Hogg, Brian N; Moran, Patrick J; Smith, Lincoln

2017-06-01

The impacts of weed biological control agents may vary with plant ontogeny. As plants grow, structural and chemical changes can alter plant resistance, which may reduce herbivory via chemical or structural defenses, and plant tolerance, which may enable plants to maintain fitness despite attack. Resistance and tolerance generally increase as plants grow. Nonetheless, prerelease tests of agent efficacy often overlook plant ontogeny. Here, we assess the performance and impacts of a candidate biocontrol agent, the psyllid Arytinnis hakani (Loginova), in relation to the age of its host plant, the invasive shrub French broom, Genista monspessulana. We also examined whether the psyllid can consistently kill plants when its densities are sufficiently high. Survival of psyllids to adulthood and the timing of adult emergence did not differ between plant sizes, indicating that performance of nymphs was not influenced by plant size. However, adult psyllid survival was reduced on small plants, suggesting that nymphs and adults responded differently to ontogenetic changes in plant quality. Psyllids affected the growth of small and large plants similarly; all measured plant growth parameters were lower in the presence of psyllids regardless of plant size. In a separate experiment, effects on plant survival depended on psyllid density, as higher realized densities of ∼9 psyllids per cm stem length were necessary to consistently kill plants. Thus, results suggest that the psyllid would be equally effective on a range of plant sizes, particularly at high densities, and show the potential of the psyllid to help control French broom in California. Published by Oxford University Press on behalf of Entomological Society of America 2017. This work is written by US Government employees and is in the public domain in the US.

LUBRICATING AND SIZING AGENT FOR GLASS FIBER,

DTIC Science & Technology

GLASS TEXTILES, SURFACE PROPERTIES), (*LUBRICANTS, GLASS TEXTILES), FIBERS , POLYVINYL ALCOHOL, STEARATES, CHROMIUM COMPOUNDS, ALUMINUM COMPOUNDS, MIXTURES, LACTATES, TITANIUM COMPOUNDS, MECHANICAL PROPERTIES, USSR

Nanoparticles speckled by ready-to-conjugate lanthanide complexes for multimodal imaging

NASA Astrophysics Data System (ADS)

Biju, Vasudevanpillai; Hamada, Morihiko; Ono, Kenji; Sugino, Sakiko; Ohnishi, Takashi; Shibu, Edakkattuparambil Sidharth; Yamamura, Shohei; Sawada, Makoto; Nakanishi, Shunsuke; Shigeri, Yasushi; Wakida, Shin-Ichi

2015-09-01

Multimodal and multifunctional contrast agents receive enormous attention in the biomedical imaging field. Such contrast agents are routinely prepared by the incorporation of organic molecules and inorganic nanoparticles (NPs) into host materials such as gold NPs, silica NPs, polymer NPs, and liposomes. Despite their non-cytotoxic nature, the large size of these NPs limits the in vivo distribution and clearance and inflames complex pharmacokinetics, which hinder the regulatory approval for clinical applications. Herein, we report a unique method that combines magnetic resonance imaging (MRI) and fluorescence imaging modalities together in nanoscale entities by the simple, direct and stable conjugation of novel biotinylated coordination complexes of gadolinium(iii) to CdSe/ZnS quantum dots (QD) and terbium(iii) to super paramagnetic iron oxide NPs (SPION) but without any host material. Subsequently, we evaluate the potentials of such lanthanide-speckled fluorescent-magnetic NPs for bioimaging at single-molecule, cell and in vivo levels. The simple preparation and small size make such fluorescent-magnetic NPs promising contrast agents for biomedical imaging.

The Impacts of Information-Sharing Mechanisms on Spatial Market Formation Based on Agent-Based Modeling

PubMed Central

Li, Qianqian; Yang, Tao; Zhao, Erbo; Xia, Xing’ang; Han, Zhangang

2013-01-01

There has been an increasing interest in the geographic aspects of economic development, exemplified by P. Krugman’s logical analysis. We show in this paper that the geographic aspects of economic development can be modeled using multi-agent systems that incorporate multiple underlying factors. The extent of information sharing is assumed to be a driving force that leads to economic geographic heterogeneity across locations without geographic advantages or disadvantages. We propose an agent-based market model that considers a spectrum of different information-sharing mechanisms: no information sharing, information sharing among friends and pheromone-like information sharing. Finally, we build a unified model that accommodates all three of these information-sharing mechanisms based on the number of friends who can share information. We find that the no information-sharing model does not yield large economic zones, and more information sharing can give rise to a power-law distribution of market size that corresponds to the stylized fact of city size and firm size distributions. The simulations show that this model is robust. This paper provides an alternative approach to studying economic geographic development, and this model could be used as a test bed to validate the detailed assumptions that regulate real economic agglomeration. PMID:23484007

An agent-based approach to financial stylized facts

NASA Astrophysics Data System (ADS)

Shimokawa, Tetsuya; Suzuki, Kyoko; Misawa, Tadanobu

2007-06-01

An important challenge of the financial theory in recent years is to construct more sophisticated models which have consistencies with as many financial stylized facts that cannot be explained by traditional models. Recently, psychological studies on decision making under uncertainty which originate in Kahneman and Tversky's research attract a lot of interest as key factors which figure out the financial stylized facts. These psychological results have been applied to the theory of investor's decision making and financial equilibrium modeling. This paper, following these behavioral financial studies, would like to propose an agent-based equilibrium model with prospect theoretical features of investors. Our goal is to point out a possibility that loss-averse feature of investors explains vast number of financial stylized facts and plays a crucial role in price formations of financial markets. Price process which is endogenously generated through our model has consistencies with, not only the equity premium puzzle and the volatility puzzle, but great kurtosis, asymmetry of return distribution, auto-correlation of return volatility, cross-correlation between return volatility and trading volume. Moreover, by using agent-based simulations, the paper also provides a rigorous explanation from the viewpoint of a lack of market liquidity to the size effect, which means that small-sized stocks enjoy excess returns compared to large-sized stocks.

Design of ultrasonically-activatable nanoparticles using low boiling point perfluorocarbons.

PubMed

Sheeran, Paul S; Luois, Samantha H; Mullin, Lee B; Matsunaga, Terry O; Dayton, Paul A

2012-04-01

Recently, an interest has developed in designing biomaterials for medical ultrasonics that can provide the acoustic activity of microbubbles, but with improved stability in vivo and a smaller size distribution for extravascular interrogation. One proposed alternative is the phase-change contrast agent. Phase-change contrast agents (PCCAs) consist of perfluorocarbons (PFCs) that are initially in liquid form, but can then be vaporized with acoustic energy. Crucial parameters for PCCAs include their sensitivity to acoustic energy, their size distribution, and their stability, and this manuscript provides insight into the custom design of PCCAs for balancing these parameters. Specifically, the relationship between size, thermal stability and sensitivity to ultrasound as a function of PFC boiling point and ambient temperature is illustrated. Emulsion stability and sensitivity can be 'tuned' by mixing PFCs in the gaseous state prior to condensation. Novel observations illustrate that stable droplets can be generated from PFCs with extremely low boiling points, such as octafluoropropane (b.p. -36.7 °C), which can be vaporized with acoustic parameters lower than previously observed. Results demonstrate the potential for low boiling point PFCs as a useful new class of compounds for activatable agents, which can be tailored to the desired application. Copyright © 2012 Elsevier Ltd. All rights reserved.

Enzyme-triggered size shrink and laser-enhanced NO release nanoparticles for deep tumor penetration and combination therapy.

PubMed

Hu, Chuan; Cun, Xingli; Ruan, Shaobo; Liu, Rui; Xiao, Wei; Yang, Xiaotong; Yang, Yuanyuan; Yang, Chuanyao; Gao, Huile

2018-06-01

Chemotherapy remains restricted by poor drug delivery efficacy due to the heterogenous nature of tumor. Herein, we presented a novel nanoparticle that could not only response to the tumor microenvironment but also modulate it for deep tumor penetration and combination therapy. The intelligent nanoparticle (IDDHN) was engineered by hyaluronidase (HAase)-triggered size shrinkable hyaluronic acid shells, which were modified with NIR laser sensitive nitric oxide donor (HN), small-sized dendrimeric prodrug (IDD) of doxorubicin (DOX) as chemotherapy agent and indocyanine green (ICG) as photothermal agent into a single nanoparticle. IDDHN displayed synergistic deep penetration both in vitro and in vivo, owing to the enzymatically degradable HN shell mediated by HAase and laser-enhanced NO release triggered deep penetration upon strong hyperthermia effect of ICG under the NIR laser irradiation. The therapeutic effect of IDDHN was verified in 4T1 xenograft tumor model, and IDDHN showed a much better antitumor efficiency with few side effects upon NIR laser irradiation. Therefore, the valid of this study might provide a novel tactic for engineering nanoparticles both response to and modulate the tumor microenvironment for improving penetration and heterogeneity distribution of therapeutic agents in tumor. Copyright © 2018 Elsevier Ltd. All rights reserved.

Size tunable elemental copper nanoparticles: extracellular synthesis by thermoanaerobic bacteria and capping molecules

DOE PAGES

Jang, Gyoung Gug; Jacobs, Christopher B.; Gresback, Ryan G.; ...

2014-11-10

Bimodal sized elemental copper (Cu) nanoparticles (NPs) were synthesized from inexpensive oxidized copper salts by an extracellular metal-reduction process using anaerobic Thermoanaerobacter sp. X513 bacteria in aqueous solution. The bacteria nucleate NPs outside of the cell, and they control the Cu2+ reduction rate to form uniform crystallites with an average diameter of 1.75 0.46 m after 3-day incubation. To control the size and enhance air stability of Cu NPs, the reaction mixtures were supplemented with nitrilotriacetic acid as a chelator, and the surfactant capping agents oleic acid, oleylamine, ascorbic acid, or L-cysteine. Time-dependent UV-visible absorption measurements and XPS studies indicatedmore » well-suspended, bimodal colloidal Cu NPs (70 150 and 5 10 nm) with extended air-stability up to 300 min and stable Cu NP films surfaces with 14% oxidation after 20 days. FTIR spectroscopy suggested that these capping agents were effectively adsorbed on the NP surface providing oxidation resistance in aqueous and dry conditions. Compared to previously reported Cu NP syntheses, this biological process substantially reduced the requirement for hazardous organic solvents and chemical reducing agents, while reducing the levels of Cu oxide impurities in the product. This process was highly reproducible and scalable from 0.01 to 1-L batches.« less

Disk diffusion antimicrobial susceptibility testing of members of the family Legionellaceae including erythromycin-resistant variants of Legionella micdadei.

PubMed Central

Dowling, J N; McDevitt, D A; Pasculle, A W

1984-01-01

Disk diffusion antimicrobial susceptibility testing of members of the family Legionellaceae was accomplished on buffered charcoal yeast extract agar by allowing the bacteria to grow for 6 h before placement of the disks, followed by an additional 42-h incubation period before the inhibitory zones were measured. This system was standardized by comparing the zone sizes with the MICs for 20 antimicrobial agents of nine bacterial strains in five Legionella species and of 19 laboratory-derived, erythromycin-resistant variants of Legionella micdadei. A high, linear correlation between zone size and MIC was found for erythromycin, trimethoprim, penicillin, ampicillin, carbenicillin, cephalothin, cefamandole, cefoxitin, moxalactam, chloramphenicol, vancomycin, and clindamycin. Disk susceptibility testing could be employed to screen Legionella isolates for resistance to any of these antimicrobial agents, of which only erythromycin is known to be efficacious in the treatment of legionellosis. With selected antibiotics, disk susceptibility patterns also appeared to accurately identify to the species level the legionellae. The range of the MICs of the legionellae for rifampin and the aminoglycosides was too small to determine whether the correlation of zone size with MIC was linear. However, laboratory-derived, high-level rifampin-resistant variants of L. micdadei demonstrated no inhibition zone around the rifampin disk, indicating that disk susceptibility testing would likely identify a rifampin-resistant clinical isolate. Of the antimicrobial agents tested, the only agents for which disk susceptibility testing was definitely not possible on buffered charcoal yeast extract agar were oxacillin, the tetracyclines, and the sulfonamides. PMID:6565706

Hydrothermal synthesis of alpha- and beta-HgS nanostructures

NASA Astrophysics Data System (ADS)

Galain, Isabel; María, Pérez Barthaburu; Ivana, Aguiar; Laura, Fornaro

2017-01-01

We synthesized HgS nanostructures by the hydrothermal method in order to use them as electron acceptors in hybrid organic-inorganic solar cells. We employed different mercury sources (HgO and Hg(CH3COO)2) and polyvinylpyrrolidone (PVP) or hexadecanethiol (HDT) as stabilizing/capping agent for controlling size, crystallinity, morphology and stability of the obtained nanostructures. We also used thiourea as sulfur source, and a temperature of 180 °C during 6 h. Synthesized nanostructures were characterized by powder X-Ray Diffraction, Diffuse Reflectance Infrared Fourier Transform and Transmission Electron Microscopy. When PVP acts as stabilizing agent, the mercury source has influence on the size -but not in morphology- of the beta-HgS obtained nansostructures. HDT has control over nanostructures' size and depending on the relation Hg:HDT, we obtained a mixture of alpha and beta HgS which can be advantageous in the application in solar cells, due their absorption in different spectral regions. The smallest nanostructures obtained have a mean diameter of 20 nm when using HDT as capping agent. Also, we deposited the aforementioned nanostructures onto flat glass substrates by the spin coating technique as a first approach of an active layer of a solar cell. The depositions were characterized by atomic force microscopy. We obtained smaller particle deposition and higher particle density -but a lower area coverage (5%) - in samples with HDT as capping agent. This work presents promising results on nanostructures for future application on hybrid solar cells. Further efforts will be focused on the deposition of organic-inorganic layers.

Aptamer-Targeted Gold Nanoparticles As Molecular-Specific Contrast Agents for Reflectance Imaging

PubMed Central

2008-01-01

Targeted metallic nanoparticles have shown potential as a platform for development of molecular-specific contrast agents. Aptamers have recently been demonstrated as ideal candidates for molecular targeting applications. In this study, we investigated the development of aptamer-based gold nanoparticles as contrast agents, using aptamers as targeting agents and gold nanoparticles as imaging agents. We devised a novel conjugation approach using an extended aptamer design where the extension is complementary to an oligonucleotide sequence attached to the surface of the gold nanoparticles. The chemical and optical properties of the aptamer−gold conjugates were characterized using size measurements and oligonucleotide quantitation assays. We demonstrate this conjugation approach to create a contrast agent designed for detection of prostate-specific membrane antigen (PSMA), obtaining reflectance images of PSMA(+) and PSMA(−) cell lines treated with the anti-PSMA aptamer−gold conjugates. This design strategy can easily be modified to incorporate multifunctional agents as part of a multimodal platform for reflectance imaging applications. PMID:18512972

Study of the thermal degradation mechanism of a composite propellant. [using electron microscopes

NASA Technical Reports Server (NTRS)

Schmidt, W. G.

1975-01-01

The current experimental program was designed to systematically investigate the role of the oxidizer in the thermal degradation process of composite propellants. The scanning electron microscope (SEM) was used to examine the failure sites in thermally degraded propellant samples. The formulation variables tested were oxidizer purity, oxidizer particle size, and oxidizer to binder bonding agent. The binder, a saturated hydrocarbon, was kept constant throughout the experiments. The oxidizers were: AP, chlorate-doped AP, arsenate-doped AP, and phosphate-doped AP. The oxidizer particle size distribution was 60% of the large fraction and 40% of the small fraction. The bonding agent, when present, was used at the 0.15% level. The data showed that both the oxidizer purity and particle size had an important affect on the thermal degradation process. The affect of the oxidizer particle size was more noticeable at the higher temperature and stress levels. An examination of the failure site, by SEM, of propellants subject to these latter conditions indicated that the fracturing of the large oxidizer particles led to the propellant cracking.

Aqueous phase preparation of ultrasmall MoSe2 nanodots for efficient photothermal therapy of cancer cells

NASA Astrophysics Data System (ADS)

Yuwen, Lihui; Zhou, Jiajia; Zhang, Yuqian; Zhang, Qi; Shan, Jingyang; Luo, Zhimin; Weng, Lixing; Teng, Zhaogang; Wang, Lianhui

2016-01-01

Photothermal therapy (PTT) is a promising cancer treatment with both high effectiveness and fewer side effects. However, an ideal PTT agent not only needs strong absorption of near-infrared (NIR) light and high photothermal conversion efficiency, but also needs good biocompatibility, stability, and small size, which makes the design and preparation of a novel PTT agent a great challenge. In this work, we developed an ultrasonication-assisted liquid exfoliation method for the direct preparation of ultrasmall (2-3 nm) MoSe2 nanodots (NDs) in aqueous solution and demonstrated their superior properties as a PTT agent. The as-prepared MoSe2 NDs have strong absorption of NIR light and high photothermal conversion efficiency of about 46.5%. In vitro cellular experiments demonstrate that MoSe2 NDs have negligible cytotoxicity and can efficiently kill HeLa cells (human cervical cell line) under NIR laser (785 nm) irradiation.Photothermal therapy (PTT) is a promising cancer treatment with both high effectiveness and fewer side effects. However, an ideal PTT agent not only needs strong absorption of near-infrared (NIR) light and high photothermal conversion efficiency, but also needs good biocompatibility, stability, and small size, which makes the design and preparation of a novel PTT agent a great challenge. In this work, we developed an ultrasonication-assisted liquid exfoliation method for the direct preparation of ultrasmall (2-3 nm) MoSe2 nanodots (NDs) in aqueous solution and demonstrated their superior properties as a PTT agent. The as-prepared MoSe2 NDs have strong absorption of NIR light and high photothermal conversion efficiency of about 46.5%. In vitro cellular experiments demonstrate that MoSe2 NDs have negligible cytotoxicity and can efficiently kill HeLa cells (human cervical cell line) under NIR laser (785 nm) irradiation. Electronic supplementary information (ESI) available: Characterization, size distribution and EDS spectrum of MoSe2 NDs, calculation of the extinction coefficient and photothermal conversion efficiency of MoSe2 NDs. See DOI: 10.1039/c5nr08166a

Europium-engineered iron oxide nanocubes with high T1 and T2 contrast abilities for MRI in living subjects

NASA Astrophysics Data System (ADS)

Yang, Lijiao; Zhou, Zijian; Liu, Hanyu; Wu, Changqiang; Zhang, Hui; Huang, Guoming; Ai, Hua; Gao, Jinhao

2015-04-01

Magnetic resonance imaging (MRI) contrast agents with both positive (T1) and negative (T2) contrast abilities are needed in clinical diagnosis for fault-free accurate detection of lesions. We report a facile synthesis of europium-engineered iron oxide (EuIO) nanocubes as T1 and T2 contrast agents for MRI in living subjects. The Eu(iii) oxide-embedded iron oxide nanoparticles significantly increase the T1 relaxivity with an enhanced positive contrast effect. EuIO nanocubes with 14 nm in diameter showed a high r1 value of 36.8 mM-1 s-1 with respect to total metal ions (Fe + Eu), which is about 3 times higher than that of Fe3O4 nanoparticles with similar size. Moreover, both r1 and r2 values of EuIO nanocubes can be tuned by varying their sizes and Eu doping ratios. After citrate coating, EuIO nanocubes can provide enhanced T1 and T2 contrast effects in small animals, particularly in the cardiac and liver regions. This work may provide an insightful strategy to design MRI contrast agents with both positive and negative contrast abilities for biomedical applications.Magnetic resonance imaging (MRI) contrast agents with both positive (T1) and negative (T2) contrast abilities are needed in clinical diagnosis for fault-free accurate detection of lesions. We report a facile synthesis of europium-engineered iron oxide (EuIO) nanocubes as T1 and T2 contrast agents for MRI in living subjects. The Eu(iii) oxide-embedded iron oxide nanoparticles significantly increase the T1 relaxivity with an enhanced positive contrast effect. EuIO nanocubes with 14 nm in diameter showed a high r1 value of 36.8 mM-1 s-1 with respect to total metal ions (Fe + Eu), which is about 3 times higher than that of Fe3O4 nanoparticles with similar size. Moreover, both r1 and r2 values of EuIO nanocubes can be tuned by varying their sizes and Eu doping ratios. After citrate coating, EuIO nanocubes can provide enhanced T1 and T2 contrast effects in small animals, particularly in the cardiac and liver regions. This work may provide an insightful strategy to design MRI contrast agents with both positive and negative contrast abilities for biomedical applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr00774g

Preparation of modified waterworks sludge particles as adsorbent to enhance coagulation of slightly polluted source water.

PubMed

Chen, Wei; Gao, Xiaohong; Xu, Hang; Wang, Kang; Chen, Taoyuan

2017-08-01

Without treatment, waterworks sludge is ineffective as an adsorbent. In this study, raw waterworks sludge was used as the raw material to prepare modified sludge particles through high-temperature calcination and alkali modification. The feasibility of using a combination of modified particles and polyaluminum chloride (PAC) as a coagulant for treatment of slightly polluted source water was also investigated. The composition, structure, and surface properties of the modified particles were characterized, and their capabilities for removing ammonia nitrogen and turbidity were determined. The results indicate that the optimal preparation conditions for the modified sludge particles were achieved by preparing the particles with a roasting temperature of 483.12 °C, a roasting time of 3.32 h, and a lye concentration of 3.75%. Furthermore, enhanced coagulation is strengthened with the addition of modified sludge particles, which is reflected by reduction of the required PAC dose and enhancement of the removal efficiency of ammonia nitrogen and turbidity by over 80 and 93%, respectively. Additional factors such as pH, temperature, dose, and dosing sequence were also evaluated. The optimum doses of modified particles and PAC were 40 and 15 mg/L, respectively, and adding modified particles at the same time as or prior to adding PAC improves removal efficiency.

GC-MS and LC-MS analysis of nerve agents in body fluids: intra-laboratory verification test using spiked plasma and urine samples.

PubMed

Koller, Marianne; Becker, Christian; Thiermann, Horst; Worek, Franz

2010-05-15

The purpose of this study was to check the applicability of different analytical methods for the identification of unknown nerve agents in human body fluids. Plasma and urine samples were spiked with nerve agents (plasma) or with their metabolites (urine) or were left blank. Seven random samples (35% of all samples) were selected for the verification test. Plasma was worked up for unchanged nerve agents and for regenerated nerve agents after fluoride-induced reactivation of nerve agent-inhibited butyrylcholinesterase. Both extracts were analysed by GC-MS. Metabolites were extracted from plasma and urine, respectively, and were analysed by LC-MS. The urinary metabolites and two blank samples could be identified without further measurements, plasma metabolites and blanks were identified in six of seven samples. The analysis of unchanged nerve agent provided five agents/blanks and the sixth agent after further investigation. The determination of the regenerated agents also provided only five clear findings during the first screening because of a rather noisy baseline. Therefore, the sample preparation was extended by a size exclusion step performed before addition of fluoride which visibly reduced baseline noise and thus improved identification of the two missing agents. The test clearly showed that verification should be performed by analysing more than one biomarker to ensure identification of the agent(s). Copyright (c) 2010 Elsevier B.V. All rights reserved.

Active extravasation of gadolinium-based contrast agent into the subdural space following lumbar puncture.

PubMed

Kothari, Pranay D; Hanser, Evelyn M; Wang, Harrison; Farid, Nikdokht

2016-01-01

A 38year-old male presented with cauda equina syndrome following multiple lumbar puncture attempts. Lumbar spine magnetic resonance imaging (MRI) showed a subdural hematoma and an area of apparent contrast enhancement in the spinal canal on sagittal post-contrast images. Axial post-contrast images obtained seven minutes later demonstrated an increase in size and change in shape of the region of apparent contrast enhancement, indicating active extravasation of the contrast agent. This is the first reported case of active extravasation of gadolinium-based contrast agent in the spine. Copyright © 2016 Elsevier Inc. All rights reserved.

Autonomous sensor manager agents (ASMA)

NASA Astrophysics Data System (ADS)

Osadciw, Lisa A.

2004-04-01

Autonomous sensor manager agents are presented as an algorithm to perform sensor management within a multisensor fusion network. The design of the hybrid ant system/particle swarm agents is described in detail with some insight into their performance. Although the algorithm is designed for the general sensor management problem, a simulation example involving 2 radar systems is presented. Algorithmic parameters are determined by the size of the region covered by the sensor network, the number of sensors, and the number of parameters to be selected. With straight forward modifications, this algorithm can be adapted for most sensor management problems.

Seed mediated synthesis of highly mono-dispersed gold nanoparticles in the presence of hydroquinone

NASA Astrophysics Data System (ADS)

Kumar, Dhiraj; Mutreja, Isha; Sykes, Peter

2016-09-01

Gold nanoparticles (AuNPs) are being studied for several biomedical applications, including drug delivery, biomedical imaging, contrast agents and tumor targeting. The synthesis of nanoparticles with a narrow size distribution is critical for these applications. We report the synthesis of highly mono-dispersed AuNPs by a seed mediated approach, in the presence of tri-sodium citrate and hydroquinone (HQ). AuNPs with an average size of 18 nm were used for the synthesis of highly mono-dispersed nanocrystals of an average size 40 nm, 60 nm, 80 nm and ˜100 nm; but the protocol is not limited to these sizes. The colloidal gold was subjected to UV-vis absorbance spectroscopy, showing a red shift in lambda max wavelength, peaks at 518.47 nm, 526.37 nm, 535.73 nm, 546.03 nm and 556.50 nm for AuNPs seed (18 nm), 40 nm, 60 nm, 80 nm and ˜100 nm respectively. The analysis was consistent with dynamic light scattering and electron microscopy. Hydrodynamic diameters measured were 17.6 nm, 40.8 nm, 59.8 nm, 74.1 nm, and 91.4 nm (size by dynamic light scattering—volume %); with an average poly dispersity index value of 0.088, suggesting mono-dispersity in the size distribution, which was also confirmed by transmission electron microscopy analysis. The advantage of a seed mediated approach is a multi-step growth of nanoparticle size that enables us to control the number of nanoparticles in the suspension, for size ranging from 24.5 nm to 95.8 nm. In addition, the HQ-based synthesis of colloidal nanocrystals allowed control of the particle size and size distribution by tailoring either the number of seeds, amount of gold precursor or reducing agent (HQ) in the final reaction mixture.

Quantum Speedup for Active Learning Agents

NASA Astrophysics Data System (ADS)

Paparo, Giuseppe Davide; Dunjko, Vedran; Makmal, Adi; Martin-Delgado, Miguel Angel; Briegel, Hans J.

2014-07-01

Can quantum mechanics help us build intelligent learning agents? A defining signature of intelligent behavior is the capacity to learn from experience. However, a major bottleneck for agents to learn in real-life situations is the size and complexity of the corresponding task environment. Even in a moderately realistic environment, it may simply take too long to rationally respond to a given situation. If the environment is impatient, allowing only a certain time for a response, an agent may then be unable to cope with the situation and to learn at all. Here, we show that quantum physics can help and provide a quadratic speedup for active learning as a genuine problem of artificial intelligence. This result will be particularly relevant for applications involving complex task environments.

METABOLIC AND MORPHOLOGICAL OBSERVATIONS ON THE EFFECT OF SURFACE-ACTIVE AGENTS ON LEUKOCYTES

PubMed Central

Graham, R. C.; Karnovsky, M. J.; Shafer, A. W.; Glass, E. A.; Karnovsky, Manfred L.

1967-01-01

Morphological and metabolic observations have been made on the effects of endotoxin, deoxycholate, and digitonin (at less than 50 µg/ml) on polymorphonuclear leukocytes and mononuclear cells. The agents stimulate the respiration and glucose oxidation of these cells in a manner similar to that seen during phagocytosis. Electron microscopy revealed no morphological changes with the first two agents, but dramatic membrane changes were seen in the case of digitonin. Here tubular projections of characteristic size and shape formed on and split off the membrane. All the agents stimulated uptake of inulin, but efforts to demonstrate increased pinocytosis by electron microscopy have not so far succeeded, probably due to limitations in present experimental techniques. PMID:6034482

One-pot exfoliation, functionalization, and size manipulation of graphene sheets: efficient system for biomedical applications.

PubMed

Bani, Farhad; Bodaghi, Ali; Dadkhah, Abbas; Movahedi, Soodabeh; Bodaghabadi, Narges; Sadeghizadeh, Majid; Adeli, Mohsen

2018-05-01

In this work, we reported a facile method to produce stable aqueous graphene dispersion through direct exfoliation of graphite by modified hyperbranched polyglycerol. Size of graphene sheets was manipulated by simultaneous exfoliation and sonication of graphite, and functionalized graphene sheets with narrow size distribution were obtained. The polyglycerol-functionalized graphene sheets exhibited highly efficient cellular uptake and photothermal conversion, enabling it to serve as a photothermal agent for cancer therapy.

T1 relaxivity of core-encapsulated gadolinium liposomal contrast agents--effect of liposome size and internal gadolinium concentration.

PubMed

Ghaghada, Ketan; Hawley, Catherine; Kawaji, Keigo; Annapragada, Ananth; Mukundan, Srinivasan

2008-10-01

Long circulating core-encapsulated gadolinium (CE-Gd) liposomal nanoparticles that have surface conjugated polyethylene glycol are a promising platform technology for use as blood pool T1-based magnetic resonance (MR) contrast agents. The objective of this study was to investigate the effect of liposome size and internal (core) Gd concentration on the T1 relaxivity of CE-Gd liposomes. Twelve different liposomal formulations were synthesized and characterized, resulting in a size (50, 100, 200, and 400 nm) and core Gd-concentration (200, 350, and 500 mM) "matrix" of test samples. Subsequently, CE-Gd liposomes were diluted in deionized water (four diluted samples) and molar T1 relaxivity (r1) measurements were performed at 2- and 7-T MR field strengths. The r1 of CE-Gd liposomes was inversely related to the liposome size. The largest change in r1 was observed between liposomes that were extruded through 50- and 100-nm filter membranes. At both field strengths, the variation in internal gadolinium concentration did not show any significant correlation (alpha < or = 0.05) with r1. The size of CE-Gd liposomal nanoparticles significantly affects the T1 relaxivity. An inverse relation was observed between liposome size and T1 relaxivity. The T1 relaxivity did not change significantly with core Gd concentration over the measured concentration range.

Calculation extinction cross sections and molar attenuation coefficient of small gold nanoparticles and experimental observation of their UV-vis spectral properties

NASA Astrophysics Data System (ADS)

Tang, Junqi; Gao, Kunpeng; Ou, Quanhong; Fu, Xuewen; Man, Shi-Qing; Guo, Jie; Liu, Yingkai

2018-02-01

Gold nanoparticles (AuNPs) have been researched extensively, such as applied in various biosensors, biomedical imaging and diagnosis, catalysis and physico-chemical analysis. These applications usually required to know the nanoparticle size or concentration. Researchers have been studying a simply and quick way to estimate the concentration or size of nanoparticles from their optical spectra and SPR feature for several years. The extinction cross-sections and the molar attenuation coefficient were one of the key parameters. In this study, we calculated the extinction cross-sections and molar attenuation coefficient (decadic molar extinction coefficient) of small gold nanoparticles by dipole approximation method and modified Beer-Lambert law. The theoretical result showed that the surface plasmon resonance peak of small gold nanoparticles was blueshift with an increase size. Moreover, small AuNPs (sub-10 nm) were prepared by using of dextran or trisodium citrate as reducing agent and capping agent. The experimental synthesized AuNPs was also shows a blueshift as increasing particle size in a certain range. And the concentration of AuNPs was calculated based on the obtained molar attenuation coefficient. For small nanoparticles, the size of nanoparticles and surface plasmon resonance property was not showed a positive correlation compared to larger nanoparticles. These results suggested that SPR peak depended not only on the nanoparticle size and shape but also on the nanoparticles environment.

Superparamagnetic iron oxide nanoparticles with variable size and an iron oxidation state as prospective imaging agents.

PubMed

Kucheryavy, Pavel; He, Jibao; John, Vijay T; Maharjan, Pawan; Spinu, Leonard; Goloverda, Galina Z; Kolesnichenko, Vladimir L

2013-01-15

Magnetite nanoparticles in the size range of 3.2-7.5 nm were synthesized in high yields under variable reaction conditions using high-temperature hydrolysis of the precursor iron(II) and iron(III) alkoxides in diethylene glycol solution. The average sizes of the particles were adjusted by changing the reaction temperature and time and by using a sequential growth technique. To obtain γ-iron(III) oxide particles in the same range of sizes, magnetite particles were oxidized with dry oxygen in diethylene glycol at room temperature. The products were characterized by DLS, TEM, X-ray powder diffractometry, TGA, chemical analysis, and magnetic measurements. NMR r(1) and r(2) relaxivity measurements in water and diethylene glycol (for OH and CH(2) protons) have shown a decrease in the r(2)/r(1) ratio with the particle size reduction, which correlates with the results of magnetic measurements on magnetite nanoparticles. Saturation magnetization of the oxidized particles was found to be 20% lower than that for Fe(3)O(4) with the same particle size, but their r(1) relaxivities are similar. Because the oxidation of magnetite is spontaneous under ambient conditions, it was important to learn that the oxidation product has no disadvantages as compared to its precursor and therefore may be a better prospective imaging agent because of its chemical stability.

New oil-in-water magnetic emulsion as contrast agent for in vivo magnetic resonance imaging (MRI).

PubMed

Ahmed, Naveed; Jaafar-Maalej, Chiraz; Eissa, Mohamed Mahmoud; Fessi, Hatem; Elaissari, Abdelhamid

2013-09-01

Nowadays, bio-imaging techniques are widely applied for the diagnosis of various diseased/tumoral tissues in the body using different contrast agents. Accordingly, the advancement in bionanotechnology research is enhanced in this regard. Among contrast agents used, superparamagnetic iron oxide nanoparticles were developed by many researchers and applied for in vive magnetic resonance imaging (MRI). In this study, a new oil-in-water magnetic emulsion was used as contrast agent in MRI, after being characterized in terms of particle size, iron oxide content, magnetic properties and colloidal stability using dynamic light scattering (DLS), thermal gravimetric analysis (TGA), vibrating sample magnetometer (VSM) and zeta potential measurement techniques, respectively. The hydrodynamic size and magnetic content of the magnetic colloidal particles were found to be 250 nm and 75 wt%, respectively. In addition, the used magnetic emulsion possesses superparamagentic properties and high colloidal stability in aqueous medium. Then, the magnetic emulsion was highly diluted and administered intravenously to the Sprague dawley rats to be tested as contrast agent for in vivo MRI. In this preliminary study, MRI images showed significant enhancement in contrast, especially for T2 (relaxation time) contrast enhancement, indicating the distribution of magnetic colloidal nanoparticles within organs, like liver, spleen and kidneys of the Sprague dawley rats. In addition, it was found that 500 microL of the highly diluted magnetic emulsion (0.05 wt%) was found adequate for MRI analysis. This seems to be useful for further investigations especially in theranostic applications of magnetic emulsion.

Functionalized multimodal ZnO@Gd2O3 nanosystems to use as perspective contrast agent for MRI

NASA Astrophysics Data System (ADS)

Babayevska, Nataliya; Florczak, Patryk; Woźniak-Budych, Marta; Jarek, Marcin; Nowaczyk, Grzegorz; Zalewski, Tomasz; Jurga, Stefan

2017-05-01

The main aim of this research was the synthesis of the multimodal hybrid ZnO@Gd2O3 nanostructures as prospective contrast agent for Magnetic Resonance Imaging (MRI) for bio-medical applications. The nanoparticles surface was functionalized by organosilicon compounds (OSC) then, by folic acid (FA) as targeting agent and doxorubicin (Dox) as chemotherapeutic agent. Doxorubicin and folic acid were attached to the nanoparticles surface by amino groups as well as due to attractive physical interactions. The morphology and crystallography of the nanostructures were studied by HRTEM and SAXS techniques. After ZnO nanoparticles surface modification by Gd3+ and annealing at 900 °C, ZnO@Gd2O3 nanostructures are polydispersed with size 30-100 nm. NMR (Nuclear Magnetic Resonance) studies of ZnO@Gd2O3 were performed on fractionated particles with size up to 50 nm. Fourier transform infrared spectroscopy (FTIR), UV-vis spectroscopy, zeta-potential measurements and energy dispersive X-ray analysis (EDX) showed that functional groups have been effectively bonded onto the nanoparticles surface. The high adsorption capacity of folic acid (up to 20%) and doxorubicin (up to 40%) on nanoparticles was reached upon 15 min of adsorption process in a temperature-dependent manner. The nuclear magnetic resonance (NMR) relaxation measurements confirmed that the obtained ZnO@Gd2O3 nanostructures could be good contrast agents, useful for magnetic resonance imaging.

Green synthesis of colloid silver nanoparticles and resulting biodegradable starch/silver nanocomposites.

PubMed

Cheviron, Perrine; Gouanvé, Fabrice; Espuche, Eliane

2014-08-08

Environmentally friendly silver nanocomposite films were prepared by an ex situ method consisting firstly in the preparation of colloidal silver dispersions and secondly in the dispersion of the as-prepared nanoparticles in a potato starch/glycerol matrix, keeping a green chemistry process all along the synthesis steps. In the first step concerned with the preparation of the colloidal silver dispersions, water, glucose and soluble starch were used as solvent, reducing agent and stabilizing agent, respectively. The influences of the glucose amount and reaction time were investigated on the size and size distribution of the silver nanoparticles. Two distinct silver nanoparticle populations in size (diameter around 5 nm size for the first one and from 20 to 50 nm for the second one) were distinguished and still highlighted in the potato starch/glycerol based nanocomposite films. It was remarkable that lower nanoparticle mean sizes were evidenced by both TEM and UV-vis analyses in the nanocomposites in comparison to the respective colloidal silver dispersions. A dispersion mechanism based on the potential interactions developed between the nanoparticles and the polymer matrix and on the polymer chain lengths was proposed to explain this morphology. These nanocomposite film series can be viewed as a promising candidate for many applications in antimicrobial packaging, biomedicines and sensors. Copyright © 2014 Elsevier Ltd. All rights reserved.

Design and Simulation of Material-Integrated Distributed Sensor Processing with a Code-Based Agent Platform and Mobile Multi-Agent Systems

PubMed Central

Bosse, Stefan

2015-01-01

Multi-agent systems (MAS) can be used for decentralized and self-organizing data processing in a distributed system, like a resource-constrained sensor network, enabling distributed information extraction, for example, based on pattern recognition and self-organization, by decomposing complex tasks in simpler cooperative agents. Reliable MAS-based data processing approaches can aid the material-integration of structural-monitoring applications, with agent processing platforms scaled to the microchip level. The agent behavior, based on a dynamic activity-transition graph (ATG) model, is implemented with program code storing the control and the data state of an agent, which is novel. The program code can be modified by the agent itself using code morphing techniques and is capable of migrating in the network between nodes. The program code is a self-contained unit (a container) and embeds the agent data, the initialization instructions and the ATG behavior implementation. The microchip agent processing platform used for the execution of the agent code is a standalone multi-core stack machine with a zero-operand instruction format, leading to a small-sized agent program code, low system complexity and high system performance. The agent processing is token-queue-based, similar to Petri-nets. The agent platform can be implemented in software, too, offering compatibility at the operational and code level, supporting agent processing in strong heterogeneous networks. In this work, the agent platform embedded in a large-scale distributed sensor network is simulated at the architectural level by using agent-based simulation techniques. PMID:25690550

Design and simulation of material-integrated distributed sensor processing with a code-based agent platform and mobile multi-agent systems.

PubMed

Bosse, Stefan

2015-02-16

Multi-agent systems (MAS) can be used for decentralized and self-organizing data processing in a distributed system, like a resource-constrained sensor network, enabling distributed information extraction, for example, based on pattern recognition and self-organization, by decomposing complex tasks in simpler cooperative agents. Reliable MAS-based data processing approaches can aid the material-integration of structural-monitoring applications, with agent processing platforms scaled to the microchip level. The agent behavior, based on a dynamic activity-transition graph (ATG) model, is implemented with program code storing the control and the data state of an agent, which is novel. The program code can be modified by the agent itself using code morphing techniques and is capable of migrating in the network between nodes. The program code is a self-contained unit (a container) and embeds the agent data, the initialization instructions and the ATG behavior implementation. The microchip agent processing platform used for the execution of the agent code is a standalone multi-core stack machine with a zero-operand instruction format, leading to a small-sized agent program code, low system complexity and high system performance. The agent processing is token-queue-based, similar to Petri-nets. The agent platform can be implemented in software, too, offering compatibility at the operational and code level, supporting agent processing in strong heterogeneous networks. In this work, the agent platform embedded in a large-scale distributed sensor network is simulated at the architectural level by using agent-based simulation techniques.

Synthesis of Zinc Oxide Nanoparticles using Anthocyanin as a Capping Agent

NASA Astrophysics Data System (ADS)

Septiani, N. L. W.; Yuliarto, B.; Iqbal, M.; Nugraha

2017-05-01

Zinc Oxide nanoparticles have been successfully synthesized by utilizing anthocyanin as a capping agent by thermal decomposition of precursor route. The influence of the high and low concentrations of the anthocyanin to the shape and size of ZnO was investigated in this work. The anthocyanin was obtained from Indonesia black rice extract with methanol as a solvent. The crystallinity and morphology properties were characterized by X-Ray Diffractometer (XRD), and Scanning Electron Microscope (SEM), respectively. XRD result showed that ZnO was formed with good crystallinity without any second phase and had a hexagonal wurtzite crystal structure. SEM result revealed that ZnO with a low concentration of anthocyanin has a spherical shape with a uniform size of about 16 nm while ZnO with a high concentration of anthocyanin has a rod-like shape. The size of spherical ZnO in this work is smaller than ZnO from the same method of synthesis without anthocyanin (~30 nm).

The antiviral agent cidofovir [(S)-1-(3-hydroxy-2-phosphonyl-methoxypropyl)cytosine] has pronounced activity against nasopharyngeal carcinoma grown in nude mice.

PubMed

Neyts, J; Sadler, R; De Clercq, E; Raab-Traub, N; Pagano, J S

1998-02-01

The effect of the antiviral agent (S)-1-(3-hydroxy-2-phosphonylmethoxypropyl) cytosine (cidofovir) on the EBV-associated tumor nasopharyngeal carcinoma (NPC) was evaluated in NPC xenografts in athymic mice. Intratumoral injection arrested tumor growth within 1 week, and by 4 weeks, tumors regressed to 8-75% (39 +/- 33%) of the original size, whereas control tumors injected with PBS grew to 282 +/- 25% of the original size. Ganciclovir slowed but did not arrest or cause regression of tumor growth. A striking antitumor effect was also produced by systemic administration; at 4 weeks, tumors were 79 +/- 49% of the original size, compared with 635 +/- 91% for the controls. Widespread apoptosis was detected after treatment for 2-6 days in C15 as well as two other NPC xenografts, C17 and C18; the latter NPCs have mutations in the p53 gene. These data indicate that cidofovir induces rapid cell death through apoptosis in EBV-transformed epithelial cells.

Interactions Among Latitude, Nematode Parasitization, and Female Sirex nigricornis (Hymenoptera: Siricidae) Fitness.

PubMed

Hartshorn, Jessica A; Chase, Kevin D; Galligan, Larry D; Riggins, John J; Stephen, Fred M

2016-12-01

Sirex nigricornis F. (Hymenoptera: Siricidae) is an innocuous pine-inhabiting woodwasp native to eastern North America, utilizing dead or dying pine trees as hosts. Although S. nigricornis F. does not cause economic damage, a closely related species, Sirex noctilio, was discovered in New York in 2004 and has continually spread throughout the northeastern United States and southern Canada, threatening the multi-billion-dollar pine timber industry of the southeastern United States and raising interest about potential interactions with native woodwasps and associated mortality agents. A non-sterilizing strain of the biological control agent, Deladenus siricidicola Bedding (Tylenchida: Neotylenchidae), was introduced along with S. noctilio but is not inhibiting the spread or establishment of S. noctilio A North American congener, Deladenus proximus Bedding, has been recently isolated from S. noctilio and shows promise as a biological control agent. To better understand the potential of D. proximus as a control agent for S. noctilio, we measured and dissected nearly 1,200 S. nigricornis females from Arkansas and Mississippi and evaluated differences among collection location with regard to nematode virulence, woodwasp body size, and egg load. Body size and egg load were related to collection location, and nematode infestation resulted in significantly smaller females who produced significantly fewer eggs. Female woodwasps, especially those collected in Arkansas, were often fully sterilized by nematodes, and a higher percent sterilization was inversely related to body size and fewer eggs. We propose field studies to test the nematode's ability to sterilize S. noctilio in the northeastern United States. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Nondestructive Intervention to Multi-Agent Systems through an Intelligent Agent

PubMed Central

Han, Jing; Wang, Lin

2013-01-01

For a given multi-agent system where the local interaction rule of the existing agents can not be re-designed, one way to intervene the collective behavior of the system is to add one or a few special agents into the group which are still treated as normal agents by the existing ones. We study how to lead a Vicsek-like flocking model to reach synchronization by adding special agents. A popular method is to add some simple leaders (fixed-headings agents). However, we add one intelligent agent, called ‘shill’, which uses online feedback information of the group to decide the shill's moving direction at each step. A novel strategy for the shill to coordinate the group is proposed. It is strictly proved that a shill with this strategy and a limited speed can synchronize every agent in the group. The computer simulations show the effectiveness of this strategy in different scenarios, including different group sizes, shill speed, and with or without noise. Compared to the method of adding some fixed-heading leaders, our method can guarantee synchronization for any initial configuration in the deterministic scenario and improve the synchronization level significantly in low density groups, or model with noise. This suggests the advantage and power of feedback information in intervention of collective behavior. PMID:23658695

Sarin Exposures in A Cohort of British Military Participants in Human Experimental Research at Porton Down 1945-1987.

PubMed

Keegan, Thomas J; Carpenter, Lucy M; Brooks, Claire; Langdon, Toby; Venables, Katherine M

2017-12-15

The effects of exposure to chemical warfare agents in humans are topical. Porton Down is the UK's centre for research on chemical warfare where, since WWI, a programme of experiments involving ~30000 participants drawn from the UK armed services has been undertaken. Our aim is to report on exposures to nerve agents, particularly sarin, using detailed exposure data not explored in a previous analysis. In this paper, we have used existing data on exposures to servicemen who attended the human volunteer programme at Porton Down to examine exposures to nerve agents in general and to sarin in particular. Six principal nerve agents were tested on humans between 1945 and 1987. Of all 4299 nerve agent tests recorded, 3511 (82%) were with sarin, most commonly in an exposure chamber, with inhalation being the commonest exposure route (85%). Biological response to sarin exposure was expressed as percentage change in cholinesterase activity and, less commonly, change in pupil size. For red blood cell cholinesterase, median inhibition for inhalation tests was 41% (interquartile range 28-51%), with a maximum of 87%. For dermal exposures the maximum inhibition recorded was 99%. There was a clear association between increasing exposure to sarin and depression of cholinesterase activity but the strength and direction of the association varied by exposure route and the presence of chemical or physical protection. Pupil size decreased with increased exposure but this relationship was less clear when modifiers, such as atropine drops, were present. These results, drawn from high quality experimental data, offer a unique insight into the effects of these chemical agents on humans. © The Author 2017. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

When more of the same is better

NASA Astrophysics Data System (ADS)

Fontanari, José F.

2016-01-01

Problem solving (e.g., drug design, traffic engineering, software development) by task forces represents a substantial portion of the economy of developed countries. Here we use an agent-based model of cooperative problem-solving systems to study the influence of diversity on the performance of a task force. We assume that agents cooperate by exchanging information on their partial success and use that information to imitate the more successful agent in the system —the model. The agents differ only in their propensities to copy the model. We find that, for easy tasks, the optimal organization is a homogeneous system composed of agents with the highest possible copy propensities. For difficult tasks, we find that diversity can prevent the system from being trapped in sub-optimal solutions. However, when the system size is adjusted to maximize the performance the homogeneous systems outperform the heterogeneous systems, i.e., for optimal performance, sameness should be preferred to diversity.

Chemical release from single-PMMA microparticles monitored by CARS microscopy

NASA Astrophysics Data System (ADS)

Enejder, Annika; Svedberg, Fredrik; Nordstierna, Lars; Nydén, Magnus

2011-03-01

Microparticles loaded with antigens, proteins, DNA, fungicides, and other functional agents emerge as ideal vehicles for vaccine, drug delivery, genetic therapy, surface- and crop protection. The microscopic size of the particles and their collective large specific surface area enables highly active and localized release of the functional substance. In order to develop designs with release profiles optimized for the specific application, it is desirable to map the distribution of the active substance within the particle and how parameters such as size, material and morphology affect release rates at single particle level. Current imaging techniques are limited in resolution, sensitivity, image acquisition time, or sample treatment, excluding dynamic studies of active agents in microparticles. Here, we demonstrate that the combination of CARS and THG microscopy can successfully be used, by mapping the spatial distribution and release rates of the fungicide and food preservative IPBC from different designs of PMMA microparticles at single-particle level. By fitting a radial diffusion model to the experimental data, single particle diffusion coefficients can be determined. We show that release rates are highly dependent on the size and morphology of the particles. Hence, CARS and THG microscopy provides adequate sensitivity and spatial resolution for quantitative studies on how singleparticle properties affect the diffusion of active agents at microscopic level. This will aid the design of innovative microencapsulating systems for controlled release.

Synthesis and study of catalytic application of l-methionine protected gold nanoparticles

NASA Astrophysics Data System (ADS)

Raza, Akif; Javed, Safdar; Qureshi, Muhammad Zahid; khan, Muhammad Usman; Khan, Muhammad Saleem

2017-10-01

Gold nanoparticle is growing class of nanotechnology due to large number of uses. We synthesized stable l-methionine protected gold nanoparticles (AuNps) by in situ reduction of HAuCl4 using sodium borohydrate as reducing and l-methionine as stabilizing agent in an aqueous medium. Different parameters (pH, capping agent, precursor salt, and heating time) were optimized to see the effect on the size of particles. Double beam spectrophotometer was used to carry out the spectroscopic studies. It was observed that pH and concentration of reducing salt are deciding factors in controlling the size and morphology of AuNps. Scanning electron microscopy (SEM) verified the formation of AuNPs as predicted by UV-Vis spectra. The interaction of AuNPs with l-methionine was confirmed by Fourier Transform Infrared (FTIR). The reduction of 4-nitrophenol acted as standard of reaction to check the response of AuNps catalyst. Complete reduction of 4-nitrophenol was accomplished by AuNps sol in just 60 s. Fastest reduction rate was observed with smaller spherical particles. This study concluded that size and shape of AuNps can be monitored by controlling the pH, concentration of capping and reducing agent. It also provides an economical solution to aquatic environment in terms of time saving and use of small volume of catalytic solution for reduction of several other toxic organic pollutants.

Biomimetic synthesis of silver nanoparticles using the fish scales of Labeo rohita and their application as catalysts for the reduction of aromatic nitro compounds

NASA Astrophysics Data System (ADS)

Sinha, Tanur; Ahmaruzzaman, M.; Sil, A. K.; Bhattacharjee, Archita

2014-10-01

In this article, a cleaner, greener, cheaper and environment friendly method for the generation of self assembled silver nanoparticles (Ag NPs) applying a simple irradiation technique using the aqueous extract of the fish scales (which is considered as a waste material) of Labeo rohita is described. Gelatin is considered as the major ingredient responsible for the reduction as well as stabilisation of the self assembled Ag NPs. The size and morphology of the individual Ag NPs can be tuned by controlling the various reaction parameters, such as temperature, concentration, and pH. Studies showed that on increasing concentration and pH Ag NPs size decreases, while on increasing temperature, Ag NPs size increases. The present process does not need any external reducing agent, like sodium borohydride or hydrazine or others and gelatin itself can play a dual role: a ‘reducing agent' and ‘stabilisation agent' for the formation of gelatin-Ag NPs colloidal dispersion. The synthesized Ag NPs were characterised by Ultraviolet-Visible spectroscopy (UV-Vis), Transmission electron microscopy (TEM) and Selected area electron diffraction (SAED) analyses. The synthesized Ag NPs was used to study the catalytic reduction of various aromatic nitro compounds in aqueous and three different micellar media. The hydrophobic and electrostatic interaction between the micelle and the substrate is responsible for the catalytic activity of the nanoparticles in micelle.

The dynamics of financial stability in complex networks

NASA Astrophysics Data System (ADS)

da Cruz, J. P.; Lind, P. G.

2012-08-01

We address the problem of banking system resilience by applying off-equilibrium statistical physics to a system of particles, representing the economic agents, modelled according to the theoretical foundation of the current banking regulation, the so called Merton-Vasicek model. Economic agents are attracted to each other to exchange `economic energy', forming a network of trades. When the capital level of one economic agent drops below a minimum, the economic agent becomes insolvent. The insolvency of one single economic agent affects the economic energy of all its neighbours which thus become susceptible to insolvency, being able to trigger a chain of insolvencies (avalanche). We show that the distribution of avalanche sizes follows a power-law whose exponent depends on the minimum capital level. Furthermore, we present evidence that under an increase in the minimum capital level, large crashes will be avoided only if one assumes that agents will accept a drop in business levels, while keeping their trading attitudes and policies unchanged. The alternative assumption, that agents will try to restore their business levels, may lead to the unexpected consequence that large crises occur with higher probability.

Improved Success of Sparse Matrix Protein Crystallization Screening with Heterogeneous Nucleating Agents

PubMed Central

Thakur, Anil S.; Robin, Gautier; Guncar, Gregor; Saunders, Neil F. W.; Newman, Janet; Martin, Jennifer L.; Kobe, Bostjan

2007-01-01

Background Crystallization is a major bottleneck in the process of macromolecular structure determination by X-ray crystallography. Successful crystallization requires the formation of nuclei and their subsequent growth to crystals of suitable size. Crystal growth generally occurs spontaneously in a supersaturated solution as a result of homogenous nucleation. However, in a typical sparse matrix screening experiment, precipitant and protein concentration are not sampled extensively, and supersaturation conditions suitable for nucleation are often missed. Methodology/Principal Findings We tested the effect of nine potential heterogenous nucleating agents on crystallization of ten test proteins in a sparse matrix screen. Several nucleating agents induced crystal formation under conditions where no crystallization occurred in the absence of the nucleating agent. Four nucleating agents: dried seaweed; horse hair; cellulose and hydroxyapatite, had a considerable overall positive effect on crystallization success. This effect was further enhanced when these nucleating agents were used in combination with each other. Conclusions/Significance Our results suggest that the addition of heterogeneous nucleating agents increases the chances of crystal formation when using sparse matrix screens. PMID:17971854

Life-history traits and parasitism rates of four phorid species (Diptera: Phoridae), parasitoids of Atta vollenweideri (Hymenoptera: Formicidae) in Argentina.

PubMed

Guillade, Andrea C; Folgarait, Patricia J

2011-02-01

Leaf-cutting ants in the genus Atta F. (Formicidae, Attini) are among the most important pest arthropods in Central and South America, consuming more vegetation than any other animal group. Among the organisms attacking ants in nature, flies of the family Phoridae have been proposed as the most promising biocontrol agents for pest ants. Four phorid species, Apocephalus setitarsus Brown, Myrmosicarius brandaoi Disney, Myrmosicarius gonzalezae Disney, and Eibesfeldtphora trilobata Disney, were reared from ants collected at Atta vollenweideri Forel nests and off foraging trails in Santa Fe province in Argentina. E. trilobata attacked larger ants and had bigger adults than the other species, also exhibiting the longest developmental time. Correlations between size of hosts and size of adults, as well as between size of adults and developmental times, could be established only in some cases. No differences were found between the sizes of the hosts from which males and females emerged. The natural percentage of parasitism varied throughout the seasons and seemed to be influenced by the extreme drought affecting the study site. We discuss why all four species would be suitable candidates for integrating an assemblage of biocontrol agents against A. vollenweideri.

In situ growth of metal particles on 3D urchin-like WO3 nanostructures.

PubMed

Xi, Guangcheng; Ye, Jinhua; Ma, Qiang; Su, Ning; Bai, Hua; Wang, Chao

2012-04-18

Metal/semiconductor hybrid materials of various sizes and morphologies have many applications in areas such as catalysis and sensing. Various organic agents are necessary to stabilize metal nanoparticles during synthesis, which leads to a layer of organic compounds present at the interfaces between the metal particles and the semiconductor supports. Generally, high-temperature oxidative treatment is used to remove the organics, which can extensively change the size and morphology of the particles, in turn altering their activity. Here we report a facile method for direct growth of noble-metal particles on WO(3) through an in situ redox reaction between weakly reductive WO(2.72) and oxidative metal salts in aqueous solution. This synthetic strategy has the advantages that it takes place in one step and requires no foreign reducing agents, stabilizing agents, or pretreatment of the precursors, making it a practical method for the controlled synthesis of metal/semiconductor hybrid nanomaterials. This synthetic method may open up a new way to develop metal-nanoparticle-loaded semiconductor composites. © 2012 American Chemical Society

Preliminary study of semi-refined carrageenan (SRC) as secondary gelling agent in natural rubber (NR) latex foam

NASA Astrophysics Data System (ADS)

Norhazariah, S.; Azura, A. R.; Azahari, B.; Sivakumar, R.

2017-12-01

Semi-refined carrageenan (SRC) product is considerably cheaper and easier to produce as a natural polysaccharide, which was utilized in food and other product application. However, the application in latex is limited. The aim of this work is to evaluate the SRC produced from low industrial grade seaweed (LIGS) in the latex foam application. The FTIR spectra showed the SRC produced as kappa type carrageenan with lower sulfur content compared to native LIGS. NR latex foam is produced by using the Dunlop method with some modifications. The effect of SRC loading as a secondary gelling agent in NR latex foam is investigated. The density and morphology of the NR latex foam with the addition of the SRC are analyzed. NR latex foam density increased with SRC loading and peaked at 1.8 phr SRC. The addition of SRC has induced the bigger cell size compared to the cell size of the control NR latex foam, as shown in the optical micrograph. It can be concluded that SRC LIGS could be acted as secondary gelling agent in NR latex foam.

Preparation and Structure Study of Water-Blown Polyurethane/RDX Gun Propellant Foams

NASA Astrophysics Data System (ADS)

Yang, Weitao; Yang, Jianxing; Zhao, Yuhua; Zhang, Yucheng

2018-01-01

Water-blown polyurethane/RDX foamed propellants were prepared using polyols and isocyanate as reactive binder system, hexogen (RDX) as energetic component, triethanolamine (TEA)/Ditin butyl dilaurate (T-12) as composite catalysts, and H2O as blowing agent. The influences of catalyst ratio, blowing agent amount, and solid filler content on the inner porous structure were studied. The results show that the balance of gel rate and cream rate that could be adjusted by catalyst ratio is a major influencing factor on porous structure of foamed propellants. When the ratio of TEA/T-12 was adjusted to 1/0.7, the morphology of the foamed propellant exhibited spherical and closed porous structure. Besides, when the water amount was increased from 0.1% to 0.5%, the pore size increased from 0.43 to 0.64 mm. The contents of RDX particles affected the cell nucleation and thus, the cell geometry. When the blowing agent amount was constant, the increased content of RDX filler led to a decreased pore size. The closed bomb test results showed that foamed propellants burned progressively in an in-depth combustion mode.

Iron-based ferritin nanocore as a contrast agent.

PubMed

Sana, Barindra; Johnson, Eric; Sheah, Kenneth; Poh, Chueh Loo; Lim, Sierin

2010-09-01

Self-assembling protein cages have been exploited as templates for nanoparticle synthesis. The ferritin molecule, a protein cage present in most living systems, stores excess soluble ferrous iron in the form of an insoluble ferric complex within its cavity. Magnetic nanocores formed by loading excess iron within an engineered ferritin from Archaeoglobus fulgidus (AfFtn-AA) were studied as a potential magnetic resonance (MR) imaging contrast agent. The self-assembly characteristics of the AfFtn-AA were investigated using dynamic light scattering technique and size exclusion chromatography. Homogeneous size distribution of the assembled nanoparticles was observed using transmission electron microscopy. The magnetic properties of iron-loaded AfFtn-AA were studied using vibrating sample magnetometry. Images obtained from a 3.0 T whole-body MRI scanner showed significant brightening of T(1) images and signal loss of T(2) images with increased concentrations of iron-loaded AfFtn-AA. The analysis of the MR image intensities showed extremely high R(2) values (5300 mM(-1) s(-1)) for the iron-loaded AfFtn-AA confirming its potential as a T(2) contrast agent.

Lipid Raft Size and Lipid Mobility in Non-raft Domains Increase during Aging and Are Exacerbated in APP/PS1 Mice Model of Alzheimer's Disease. Predictions from an Agent-Based Mathematical Model

PubMed Central

Santos, Guido; Díaz, Mario; Torres, Néstor V.

2016-01-01

A connection between lipid rafts and Alzheimer's disease has been studied during the last decades. Mathematical modeling approaches have recently been used to correlate the effects of lipid composition changes in the physicochemical properties of raft-like membranes. Here we propose an agent based model to assess the effect of lipid changes in lipid rafts on the evolution and progression of Alzheimer's disease using lipid profile data obtained in an established model of familial Alzheimer's disease. We have observed that lipid raft size and lipid mobility in non-raft domains are two main factors that increase during age and are accelerated in the transgenic Alzheimer's disease mouse model. The consequences of these changes are discussed in the context of neurotoxic amyloid β production. Our agent based model predicts that increasing sterols (mainly cholesterol) and long-chain polyunsaturated fatty acids (LCPUFA) (mainly DHA, docosahexaenoic acid) proportions in the membrane composition might delay the onset and progression of the disease. PMID:27014089

Naming games in two-dimensional and small-world-connected random geometric networks.

PubMed

Lu, Qiming; Korniss, G; Szymanski, B K

2008-01-01

We investigate a prototypical agent-based model, the naming game, on two-dimensional random geometric networks. The naming game [Baronchelli, J. Stat. Mech.: Theory Exp. (2006) P06014] is a minimal model, employing local communications that captures the emergence of shared communication schemes (languages) in a population of autonomous semiotic agents. Implementing the naming games with local broadcasts on random geometric graphs, serves as a model for agreement dynamics in large-scale, autonomously operating wireless sensor networks. Further, it captures essential features of the scaling properties of the agreement process for spatially embedded autonomous agents. Among the relevant observables capturing the temporal properties of the agreement process, we investigate the cluster-size distribution and the distribution of the agreement times, both exhibiting dynamic scaling. We also present results for the case when a small density of long-range communication links are added on top of the random geometric graph, resulting in a "small-world"-like network and yielding a significantly reduced time to reach global agreement. We construct a finite-size scaling analysis for the agreement times in this case.

Team Formation and Communication Restrictions in Collectives

NASA Technical Reports Server (NTRS)

Agogino, Adrian K.; Turner, Kagan

2003-01-01

A collective of agents often needs to maximize a "world utility" function which rates the performance of an entire system, while subject to communication restrictions among the agents. Such communication restrictions make it difficult for agents which try to pursue their own "private" utilities to take actions that also help optimize the world utility. Team formation presents a solution to this problem, where by joining other agents, an agent can significantly increase its knowledge about the environment and improve its chances of both optimizing its own utility and that its doing so will contribute to the world utility. In this article we show how utilities that have been previously shown to be effective in collectives can be modified to be more effective in domains with moderate communication restrictions resulting in performance improvements of up to 75%. Additionally we show that even severe communication constraints can be overcome by forming teams where each agent of a team shares the same utility, increasing performance an additional 25%. We show that utilities and team sizes can be manipulated to form the best compromise between how "aligned" an agent s utility is with the world utility and how easily an agent can learn that utility.

The effect of polymers onto the size of zinc layered hydroxide salt and its calcined product

NASA Astrophysics Data System (ADS)

Hussein, Mohd Zobir bin; Ghotbi, Mohammad Yeganeh; Yahaya, Asmah Hj; Abd Rahman, Mohd Zaki

2009-02-01

Zinc hydroxide nitrate, a brucite-like layered material was synthesized using pH control method. Poly(vinyl alcohol) and poly(ethylene glycol) were used at various percentages as size decreasing agents during the synthesis of zinc hydroxide nitrate. SEM and PXRD showed the decrease of size and thickness of the resultant zinc hydroxide nitrates. TG and surface area data confirmed the decrease of the particle sizes, too. When zinc hydroxide nitrates were heat treated at 500 °C, the physical properties of nano zinc oxides obtained depended on the parent material, zinc hydroxide nitrate.

Cyclic and Coherent States in Flocks with Topological Distance

NASA Astrophysics Data System (ADS)

Bhattacherjee, Biplab; Bhattacharya, Kunal; Manna, Subhrangshu

2014-01-01

A simple model of the two dimensional collective motion of a group of mobile agents have been studied. Like birds, these agents travel in open free space where each of them interacts with the first n neighbors determined by the topological distance with a free boundary condition. Using the same prescription for interactions used in the Vicsek model with scalar noise it has been observed that the flock, in absence of the noise, arrives at a number of interesting stationary states. One of the two most prominent states is the `single sink state' where the entire flock travels along the same direction maintaining perfect cohesion and coherence. The other state is the `cyclic state' where every individual agent executes a uniform circular motion, and the correlation among the agents guarantees that the entire flock executes a pulsating dynamics i.e., expands and contracts periodically between a minimum and a maximum size of the flock. We have studied another limiting situation when refreshing rate of the interaction zone is the fastest. In this case the entire flock gets fragmented into smaller clusters of different sizes. On introduction of scalar noise a crossover is observed when the agents cross over from a ballistic motion to a diffusive motion. Expectedly the crossover time is dependent on the strength of the noise η and diverges as η → 0. An even more simpler version of this model has been studied by suppressing the translational degrees of freedom of the agents but retaining their angular motion. Here agents are the spins, placed at the sites of a square lattice with periodic boundary condition. Every spin interacts with its n = 2, 3 or 4 nearest neighbors. In the stationary state the entire spin pattern moves as a whole when interactions are anisotropic with n = 2 and 3; but it is completely frozen when the interaction is isotropic with n=4$. These spin configu

Cast-In-Situ, Large-Sized Monolithic Silica Xerogel Prepared in Aqueous System.

PubMed

Ding, Wenhui; Wang, Xiaodong; Chen, Dong; Li, Tiemin; Shen, Jun

2018-05-15

This paper reports the preparation of cast-in-situ, large-sized monolithic silica xerogels by a two-step acid⁻base catalyzed approach under ambient pressure drying. Low-cost industrial silica sol and deionized water were used as the silicon source and the solvent, respectively. Hexadecetyltrimethylammonium bromide (CTAB) was used as a modification agent. Different amounts of polyethylene glycol 400 (PEG400) was added as a pore-forming agent. The prepared silica xerogels under ambient pressure drying have a mesoporous structure with a low density of 221 mg·cm -3 and a thermal conductivity of 0.0428 W·m -1 ·K -1 . The low-cost and facile preparation process, as well as the superior performance of the monolithic silica xerogels make it a promising candidate for industrial thermal insulation materials.

Encapsulation of nanoclusters in dried gel materials via an inverse micelle/sol gel synthesis

DOEpatents

Martino, Anthony; Yamanaka, Stacey A.; Kawola, Jeffrey S.; Showalter, Steven K.; Loy, Douglas A.

1998-01-01

A dried gel material sterically entrapping nanoclusters of a catalytically active material and a process to make the material via an inverse micelle/sol-gel synthesis. A surfactant is mixed with an apolar solvent to form an inverse micelle solution. A salt of a catalytically active material, such as gold chloride, is added along with a silica gel precursor to the solution to form a mixture. To the mixture are then added a reducing agent for the purpose of reducing the gold in the gold chloride to atomic gold to form the nanoclusters and a condensing agent to form the gel which sterically entraps the nanoclusters. The nanoclusters are normally in the average size range of from 5-10 nm in diameter with a monodisperse size distribution.

Activity of a social dynamics model

NASA Astrophysics Data System (ADS)

Reia, Sandro M.; Neves, Ubiraci P. C.

2015-10-01

Axelrod's model was proposed to study interactions between agents and the formation of cultural domains. It presents a transition from a monocultural to a multicultural steady state which has been studied in the literature by evaluation of the relative size of the largest cluster. In this article, we propose new measurements based on the concept of activity per agent to study the Axelrod's model on the square lattice. We show that the variance of system activity can be used to indicate the critical points of the transition. Furthermore the frequency distribution of the system activity is able to show a coexistence of phases typical of a first order phase transition. Finally, we verify a power law dependence between cluster activity and cluster size for multicultural steady state configurations at the critical point.

Scaling laws of strategic behavior and size heterogeneity in agent dynamics

NASA Astrophysics Data System (ADS)

Vaglica, Gabriella; Lillo, Fabrizio; Moro, Esteban; Mantegna, Rosario N.

2008-03-01

We consider the financial market as a model system and study empirically how agents strategically adjust the properties of large orders in order to meet their preference and minimize their impact. We quantify this strategic behavior by detecting scaling relations between the variables characterizing the trading activity of different institutions. We also observe power-law distributions in the investment time horizon, in the number of transactions needed to execute a large order, and in the traded value exchanged by large institutions, and we show that heterogeneity of agents is a key ingredient for the emergence of some aggregate properties characterizing this complex system.

Production of xanthan gum from a chemically defined medium introduction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weisrock, W.P.; Klein, H.S.

1983-02-22

Heteropolysaccharides produced by the action of Xanthomonas bacteria on carbohydrate media have a potential application as film forming agents, as thickeners in oil field drilling fluids and fracturing liquids and as emulsifying, stabilizing, and sizing agents. Heteropolysaccharides, particularly, xanthan gum, have a significant potential as mobility control agents in micellar polymer flooding. Xanthan gum has excellent viscosifying properties at low concentration, is resistant to shear degradation and exhibits only minimal losses in viscosity as a function of temperature, pH, and ionic strength. For these reasons, xanthan gum is an attractive alternative to synthetic polyacrylamides for enhanced oil recovery operations. 15more » claims.« less

Heterogeneous voter models

NASA Astrophysics Data System (ADS)

Masuda, Naoki; Gibert, N.; Redner, S.

2010-07-01

We introduce the heterogeneous voter model (HVM), in which each agent has its own intrinsic rate to change state, reflective of the heterogeneity of real people, and the partisan voter model (PVM), in which each agent has an innate and fixed preference for one of two possible opinion states. For the HVM, the time until consensus is reached is much longer than in the classic voter model. For the PVM in the mean-field limit, a population evolves to a preference-based state, where each agent tends to be aligned with its internal preference. For finite populations, discrete fluctuations ultimately lead to consensus being reached in a time that scales exponentially with population size.

Cytotoxicity of silica-glass fiber reinforced composites.

PubMed

Meriç, Gökçe; Dahl, Jon E; Ruyter, I Eystein

2008-09-01

Silica-glass fiber reinforced polymers can be used for many kinds of dental applications. The fiber reinforcement enhances the mechanical properties of the polymers, and they have good esthetic attributes. There is good initial bonding of glass fibers to polymers via an interface made from silane coupling agents. The aim of this in vitro study was to determine the cytotoxicity of two polymers reinforced with two differently sized silica-glass fibers before and after thermal cycling. Cytotoxicity of the polymers without fibers was also evaluated. Two different resin mixtures (A and B) were prepared from poly(vinyl chloridecovinylacetate) powder and poly(methyl methacrylate) (PMMA) dissolved in methyl methacrylate and mixed with different cross-linking agents. The resin A contained the cross-linking agents ethylene glycol dimethacrylate and 1,4-butanediol dimethacrylate, and for resin B diethylene glycol dimethacrylate was used. Woven silica-glass fibers were used for reinforcement. The fibers were sized with either linear poly(butyl methacrylate)-sizing or cross-linking PMMA-sizing. Cytotoxicity was evaluated by filter diffusion test (ISO 7405:1997) of newly made and thermocycled test specimens. Extracts were prepared according to ISO 10993-12 from newly made and from thermocycled specimens and tested by the MTT assay. The results from the experiments were statistically analyzed by one-way ANOVA and Tukey's test (rho<0.05). The filter diffusion test disclosed no change in staining intensity at the cell-test sample contact area indicating non-cytotoxicity in all experimental groups. Cell viability assessed by MTT assay was more than 90% in all experimental groups. All are non-cytotoxic. It can be concluded that correctly processed heat polymerized silica-glass fiber reinforced polymers induced no cytotoxicity and that thermocycling did not alter this property.

The role of feral mammals on wildlife infectious disease prevalence in two nature reserves within Mexico City limits.

PubMed

Suzán, Gerardo; Ceballos, Gerardo

2005-09-01

Wild and feral medium-sized mammals were live trapped at two natural protected areas within the Mexico City limits to determine antibody prevalence for the most common infectious diseases (rabies, toxoplasmosis, and canine parvovirus) in dogs and cats. Mammals were trapped during the dry (March-April) and rainy seasons (July-August) of 1996 and 1997. A total of 68 individuals were captured, representing 8 species: opossums (Didelphis virginiana), ringtails (Bassariscus astutus), spotted skunks (Spilogale gracilis), weasels (Mustela frenata), rock squirrels (Spermophilus variegatus), Mexican gray squirrels (Sciurus aureogaster), feral cats (Felis catus), and feral dogs (Canis familiaris). There was marked seroprevalence for parvovirus (86.6%) and lower seroprevalences for both toxoplasma (23.9%) and rabies (17.9%). There were no significant prevalence differences among mammals in both protected areas, which were of contrasting size and isolation (i.e., small and isolated versus large and nonisolated). We suggest that high seroprevalence of these three infectious agents in wild mammals is a result of the high densities of feral dogs and cats in the two areas sampled. Feral dogs are able to maintain the infectious agents in these localities regardless of the protected area size and isolation. However, the native mammals of the small and isolated reserve are more vulnerable to infectious diseases because of small population size and genetic bottlenecks. Our results indicate that natural areas in and around Mexico City are a refugium for latent infectious agents, several of which are zoonotic. These findings suggest that conservation measures, such as eradication of feral mammals and vaccination programs, in the protected areas and surrounding areas could be beneficial.

Improving Sensitivity in Ultrasound Molecular Imaging by Tailoring Contrast Agent Size Distribution: In Vivo Studies

PubMed Central

Streeter, Jason E.; Gessner, Ryan; Miles, Iman; Dayton, Paul A.

2010-01-01

Molecular imaging with ultrasound relies on microbubble contrast agents (MCAs) selectively adhering to a ligand-specific target. Prior studies have shown that only small quantities of microbubbles are retained at their target sites, therefore, enhancing contrast sensitivity to low concentrations of microbubbles is essential to improve molecular imaging techniques. In order to assess the effect of MCA diameter on imaging sensitivity, perfusion and molecular imaging studies were performed with microbubbles of varying size distributions. To assess signal improvement and MCA circulation time as a function of size and concentration, blood perfusion was imaged in rat kidneys using nontargeted size-sorted MCAs with a Siemens Sequoia ultrasound system (Siemans, Mountain View, CA) in cadence pulse sequencing (CPS) mode. Molecular imaging sensitivity improvements were studied with size-sorted αvβ3-targeted bubbles in both fibrosarcoma and R3230 rat tumor models. In perfusion imaging studies, video intensity and contrast persistence was ≈8 times and ≈3 times greater respectively, for “sorted 3-micron” MCAs (diameter, 3.3 ± 1.95 μm) when compared to “unsorted” MCAs (diameter, 0.9 ± 0.45 μm) at low concentrations. In targeted experiments, application of sorted 3-micron MCAs resulted in a ≈20 times video intensity increase over unsorted populations. Tailoring size-distributions results in substantial imaging sensitivity improvement over unsorted populations, which is essential in maximizing sensitivity to small numbers of MCAs for molecular imaging. PMID:20236606

Calculation extinction cross sections and molar attenuation coefficient of small gold nanoparticles and experimental observation of their UV-vis spectral properties.

PubMed

Tang, Junqi; Gao, Kunpeng; Ou, Quanhong; Fu, Xuewen; Man, Shi-Qing; Guo, Jie; Liu, Yingkai

2018-02-15

Gold nanoparticles (AuNPs) have been researched extensively, such as applied in various biosensors, biomedical imaging and diagnosis, catalysis and physico-chemical analysis. These applications usually required to know the nanoparticle size or concentration. Researchers have been studying a simply and quick way to estimate the concentration or size of nanoparticles from their optical spectra and SPR feature for several years. The extinction cross-sections and the molar attenuation coefficient were one of the key parameters. In this study, we calculated the extinction cross-sections and molar attenuation coefficient (decadic molar extinction coefficient) of small gold nanoparticles by dipole approximation method and modified Beer-Lambert law. The theoretical result showed that the surface plasmon resonance peak of small gold nanoparticles was blueshift with an increase size. Moreover, small AuNPs (sub-10nm) were prepared by using of dextran or trisodium citrate as reducing agent and capping agent. The experimental synthesized AuNPs was also shows a blueshift as increasing particle size in a certain range. And the concentration of AuNPs was calculated based on the obtained molar attenuation coefficient. For small nanoparticles, the size of nanoparticles and surface plasmon resonance property was not showed a positive correlation compared to larger nanoparticles. These results suggested that SPR peak depended not only on the nanoparticle size and shape but also on the nanoparticles environment. Copyright © 2017 Elsevier B.V. All rights reserved.

Nanocrystalline cellulose-dispersed AKD emulsion for enhancing the mechanical and multiple barrier properties of surface-sized paper.

PubMed

Yang, Luming; Lu, Sheng; Li, Juanjuan; Zhang, Fengshan; Cha, Ruitao

2016-01-20

In this study, we employed nanocrystalline cellulose (NCC) as an efficient dispersant to perpare alkyl ketene dimer (AKD) emulsion. The particle size and zeta potential of AKD/NCC emulsion were measured, which were approximately 5 μm and -50 mV, respectively. The surface-sized paper possessed multiple barriers properties. The air permeability of surface-sized paper was 0.29 μm/Pas and the sizing degree reached 42 s when the amount of sizing was 12.58 g/m(2) with a 96.83% decrease and a 40.00%, increase, respectively. Furthermore, the mechanical properties were optimal when the amount of sizing was about 8 g/m(2). AKD/NCC emulsion acted as a good reinforcing agent in surface-sized paper. Copyright © 2015 Elsevier Ltd. All rights reserved.

The vascular disrupting agent ZD6126 shows increased antitumor efficacy and enhanced radiation response in large, advanced tumors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Siemann, Dietmar W.; Rojiani, Amyn M.

2005-07-01

Purpose: ZD6126 is a vascular-targeting agent that induces selective effects on the morphology of proliferating and immature endothelial cells by disrupting the tubulin cytoskeleton. The efficacy of ZD6126 was investigated in large vs. small tumors in a variety of animal models. Methods and Materials: Three rodent tumor models (KHT, SCCVII, RIF-1) and three human tumor xenografts (Caki-1, KSY-1, SKBR3) were used. Mice bearing leg tumors ranging in size from 0.1-2.0 g were injected intraperitoneally with a single 150 mg/kg dose of ZD6126. The response was assessed by morphologic and morphometric means as well as an in vivo to in vitromore » clonogenic cell survival assay. To examine the impact of tumor size on the extent of enhancement of radiation efficacy by ZD6126, KHT sarcomas of three different sizes were irradiated locally with a range of radiation doses, and cell survival was determined. Results: All rodent tumors and human tumor xenografts evaluated showed a strong correlation between increasing tumor size and treatment effect as determined by clonogenic cell survival. Detailed evaluation of KHT sarcomas treated with ZD6126 showed a reduction in patent tumor blood vessels that was {approx}20% in small (<0.3 g) vs. >90% in large (>1.0 g) tumors. Histologic assessment revealed that the extent of tumor necrosis after ZD6126 treatment, although minimal in small KHT sarcomas, became more extensive with increasing tumor size. Clonogenic cell survival after ZD6126 exposure showed a decrease in tumor surviving fraction from approximately 3 x 10{sup -1} to 1 x 10{sup -4} with increasing tumor size. When combined with radiotherapy, ZD6126 treatment resulted in little enhancement of the antitumor effect of radiation in small (<0.3 g) tumors but marked increases in cell kill in tumors larger than 1.0 g. Conclusions: Because bulky neoplastic disease is typically the most difficult to manage, the present findings provide further support for the continued development of vascular disrupting agents such as ZD6126 as a vascular-targeted approach to cancer therapy.« less

Excess of Radiation Burden for Young Testicular Cancer Patients using Automatic Exposure Control and Contrast Agent on Whole-body Computed Tomography Imaging.

PubMed

Niiniviita, Hannele; Kulmala, Jarmo; Pölönen, Tuukka; Määttänen, Heli; Järvinen, Hannu; Salminen, Eeva

2017-06-01

The aim of the study was to assess patient dose from whole-body computed tomography (CT) in association with patient size, automatic exposure control (AEC) and intravenous (IV) contrast agent. Sixty-five testicular cancer patients (mean age 28 years) underwent altogether 279 whole-body CT scans from April 2000 to April 2011. The mean number of repeated examinations was 4.3. The GE LightSpeed 16 equipped with AEC and the Siemens Plus 4 CT scanners were used for imaging. Whole-body scans were performed with (216) and without (63) IV contrast. The ImPACT software was used to determine the effective and organ doses. Patient doses were independent (p < 0.41) of patient size when the Plus 4 device (mean 7.4 mSv, SD 1.7 mSv) was used, but with the LightSpeed 16 AEC device, the dose (mean 14 mSv, SD 4.6 mSv) increased significantly (p < 0.001) with waist cirfumference. Imaging with the IV contrast agent caused significantly higher (13% Plus 4, 35% LightSpeed 16) exposure than non-contrast imaging (p < 0.001). Great caution on the use of IV contrast agent and careful set-up of the AEC modulation parameters is recommended to avoid excessive radiation exposure on the whole-body CT imaging of young patients.

Thermal- and pH-Dependent Size Variable Radical Nanoparticles and Its Water Proton Relaxivity for Metal-Free MRI Functional Contrast Agents.

PubMed

Morishita, Kosuke; Murayama, Shuhei; Araki, Takeru; Aoki, Ichio; Karasawa, Satoru

2016-09-16

For development of the metal-free MRI contrast agents, we prepared the supra-molecular organic radical, TEMPO-UBD, carrying TEMPO radical, as well as the urea, alkyl group, and phenyl ring, which demonstrate self-assembly behaviors using noncovalent bonds in an aqueous solution. In addition, TEMPO-UBD has the tertiary amine and the oligoethylene glycol chains (OEGs) for the function of pH and thermal responsiveness. By dynamic light scattering and transmission electron microscopy imaging, the resulting self-assembly was seen to form the spherical nanoparticles 10-150 nm in size. On heating, interestingly, the nanoparticles showed a lower critical solution temperature (LCST) behavior having two-step variation. This double-LCST behavior is the first such example among the supra-molecules. To evaluate of the ability as MRI contrast agents, the values of proton ((1)H) longitudinal relaxivity (r1) were determined using MRI apparatus. In conditions below and above CAC at pH 7.0, the distinguishable r1 values were estimated to be 0.17 and 0.21 mM(-1) s(1), indicating the suppression of fast tumbling motion of TEMPO moiety in a nanoparticle. Furthermore, r1 values became larger in the order of pH 7.0 > 9.0 > 5.0. Those thermal and pH dependencies indicated the possibility of metal-fee MRI functional contrast agents in the future.

Synthesis and spectroscopic investigations of hydroxyapatite using a green chelating agent as template

NASA Astrophysics Data System (ADS)

Gopi, D.; Bhuvaneshwari, N.; Indira, J.; Kavitha, L.

2013-03-01

Hydroxyapatite [Ca10(PO4)6(OH)2, HAP] particles have been successfully synthesized by a cost-effective, eco-friendly green template method using natural and commercially available sucrose as a chelating agent. The sucrose used in this method has been extracted from various sources, three from natural and one from commercially available sources are exploited in our study to achieve a controlled crystallinity, particle size as well as uniform morphology. Spectral characterizations involving Fourier transform infrared spectroscopy (FT-IR) for the functional group analysis of sucrose and HAP; carbon-13 nuclear magnetic resonance spectroscopy (13C NMR) for the identification of the carbon atoms in sucrose and in HAP; liquid chromatography/mass spectrometry (LC-MS) for the determination of the hydrolyzed products of sucrose; and X-ray diffraction (XRD) techniques for the phase identification of the HAP particles were performed. The morphology of the HAP particles were assessed thoroughly using a scanning electron microscope (SEM) equipped with energy dispersive X-ray analysis (EDAX). The experimental results indicate that the obtained HAP using the natural sucrose as a chelating agent is of phase pure, with a well defined morphology having discrete particles without any agglomeration than the HAP from commercially available sucrose. Further, the reduced particle size can be achieved from the stem sugarcane extract as the source of the chelating agent.

Synthesis and spectroscopic investigations of hydroxyapatite using a green chelating agent as template.

PubMed

Gopi, D; Bhuvaneshwari, N; Indira, J; Kavitha, L

2013-03-01

Hydroxyapatite [Ca(10)(PO(4))(6)(OH)(2), HAP] particles have been successfully synthesized by a cost-effective, eco-friendly green template method using natural and commercially available sucrose as a chelating agent. The sucrose used in this method has been extracted from various sources, three from natural and one from commercially available sources are exploited in our study to achieve a controlled crystallinity, particle size as well as uniform morphology. Spectral characterizations involving Fourier transform infrared spectroscopy (FT-IR) for the functional group analysis of sucrose and HAP; carbon-13 nuclear magnetic resonance spectroscopy ((13)C NMR) for the identification of the carbon atoms in sucrose and in HAP; liquid chromatography/mass spectrometry (LC-MS) for the determination of the hydrolyzed products of sucrose; and X-ray diffraction (XRD) techniques for the phase identification of the HAP particles were performed. The morphology of the HAP particles were assessed thoroughly using a scanning electron microscope (SEM) equipped with energy dispersive X-ray analysis (EDAX). The experimental results indicate that the obtained HAP using the natural sucrose as a chelating agent is of phase pure, with a well defined morphology having discrete particles without any agglomeration than the HAP from commercially available sucrose. Further, the reduced particle size can be achieved from the stem sugarcane extract as the source of the chelating agent. Copyright © 2012 Elsevier B.V. All rights reserved.

78 FR 19334 - Proposed Collection; Comment Request

Federal Register 2010, 2011, 2012, 2013, 2014

2013-03-29

... continuous attention in resolving record inaccuracies; (4) disclose to the issuers for whom they perform... will vary according to the size and scope of the transfer agent's business activity. We note, however...

Effect of Silane Coupling Agent on the Creep Behavior and Mechanical Properties of Carbon Fibers/Acrylonitrile Butadiene Rubber Composites.

PubMed

Choi, Woong-Ki; Park, Gil-Young; Kim, Byoung-Shuk; Seo, Min-Kang

2018-09-01

In this study, we investigated the effect of the silane coupling agent on the relationship between the surface free energy of carbon fibers (CFs) and the mechanical strength of CFs/acrylonitrile butadiene rubber (NBR) composites. Moreover, the creep behavior of the CF/NBR composites at surface energetic point of view were studied. The specific component of the surface free energy of the carbon fibers was found to increase upon grafting of the silane coupling agent, resulting in an increase in the tensile strength of the CF/NBR composites. On the other hand, the compressive creep strength was found to follow a slightly different trend. These results indicate the possible formation of a complex interpenetrating polymer network depending on the molecular size of the organic functional groups of the silane coupling agent.

Resolving the Framework Position of Organic Structure-Directing Agents in Hierarchical Zeolites via Polarized Stimulated Raman Scattering.

PubMed

Fleury, Guillaume; Steele, Julian A; Gerber, Iann C; Jolibois, F; Puech, P; Muraoka, Koki; Keoh, Sye Hoe; Chaikittisilp, Watcharop; Okubo, Tatsuya; Roeffaers, Maarten B J

2018-04-05

The direct synthesis of hierarchically intergrown silicalite-1 can be achieved using a specific diquaternary ammonium agent. However, the location of these molecules in the zeolite framework, which is critical to understand the formation of the material, remains unclear. Where traditional characterization tools have previously failed, herein we use polarized stimulated Raman scattering (SRS) microscopy to resolve molecular organization inside few-micron-sized crystals. Through a combination of experiment and first-principles calculations, our investigation reveals the preferential location of the templating agent inside the linear pores of the MFI framework. Besides illustrating the attractiveness of SRS microscopy in the field of material science to study and spatially resolve local molecular distribution as well as orientation, these results can be exploited in the design of new templating agents for the preparation of hierarchical zeolites.

Supervised self-organization of homogeneous swarms using ergodic projections of Markov chains.

PubMed

Chattopadhyay, Ishanu; Ray, Asok

2009-12-01

This paper formulates a self-organization algorithm to address the problem of global behavior supervision in engineered swarms of arbitrarily large population sizes. The swarms considered in this paper are assumed to be homogeneous collections of independent identical finite-state agents, each of which is modeled by an irreducible finite Markov chain. The proposed algorithm computes the necessary perturbations in the local agents' behavior, which guarantees convergence to the desired observed state of the swarm. The ergodicity property of the swarm, which is induced as a result of the irreducibility of the agent models, implies that while the local behavior of the agents converges to the desired behavior only in the time average, the overall swarm behavior converges to the specification and stays there at all times. A simulation example illustrates the underlying concept.

The future of small molecule inhibitors in lymphoma.

PubMed

Gerecitano, John

2009-09-01

For the many patients with lymphoma that has relapsed after and/or has become refractory to existing treatments, the development of novel therapeutics is imperative. Investigation into intracellular processes that are dysregulated during lymphomagenesis has uncovered several new potential targets for anticancer agents. Although monoclonal antibodies and other immunotherapeutics have led to dramatic advances in the treatment of patients with lymphoma, the parallel development of small molecule inhibitors has been equally exciting. These agents, whose small size allows direct entry into tumor cells, can target distinct proteins or complexes, thereby disrupting molecular processes on which neoplastic cells depend for survival and growth. This review surveys the published literature on many of these new targeted molecules, focusing on some of the most promising agents for which phase 2 data currently exist. It also explores the potential for incorporating these agents into broader multidrug regimens.

Amphipathic Alpha-Helical Peptide Compositions as Antiviral Agents

NASA Technical Reports Server (NTRS)

Frank, Curtis W. (Inventor); Cheong, Kwang Ho (Inventor); Glenn, Jeffrey (Inventor); Cho, Nam-Joon (Inventor)

2014-01-01

The invention features methods and compositions that exploit the ability of amphipathic alpha-helical (AH) peptides to cause disruption of lipid-containing vesicles, such as enveloped viruses, in a size-dependent manner.

On-bead combinatorial synthesis and imaging of chemical exchange saturation transfer magnetic resonance imaging agents to identify factors that influence water exchange.

PubMed

Napolitano, Roberta; Soesbe, Todd C; De León-Rodríguez, Luis M; Sherry, A Dean; Udugamasooriya, D Gomika

2011-08-24

The sensitivity of magnetic resonance imaging (MRI) contrast agents is highly dependent on the rate of water exchange between the inner sphere of a paramagnetic ion and bulk water. Normally, identifying a paramagnetic complex that has optimal water exchange kinetics is done by synthesizing and testing one compound at a time. We report here a rapid, economical on-bead combinatorial synthesis of a library of imaging agents. Eighty different 1,4,7,10-tetraazacyclododecan-1,4,7,10-tetraacetic acid (DOTA)-tetraamide peptoid derivatives were prepared on beads using a variety of charged, uncharged but polar, hydrophobic, and variably sized primary amines. A single chemical exchange saturation transfer image of the on-bead library easily distinguished those compounds having the most favorable water exchange kinetics. This combinatorial approach will allow rapid screening of libraries of imaging agents to identify the chemical characteristics of a ligand that yield the most sensitive imaging agents. This technique could be automated and readily adapted to other types of MRI or magnetic resonance/positron emission tomography agents as well.

Nanoparticles for Cardiovascular Imaging and Therapeutic Delivery, Part 1: Compositions and Features.

PubMed

Stendahl, John C; Sinusas, Albert J

2015-10-01

Imaging agents made from nanoparticles are functionally versatile and have unique properties that may translate to clinical utility in several key cardiovascular imaging niches. Nanoparticles exhibit size-based circulation, biodistribution, and elimination properties different from those of small molecules and microparticles. In addition, nanoparticles provide versatile platforms that can be engineered to create both multimodal and multifunctional imaging agents with tunable properties. With these features, nanoparticulate imaging agents can facilitate fusion of high-sensitivity and high-resolution imaging modalities and selectively bind tissues for targeted molecular imaging and therapeutic delivery. Despite their intriguing attributes, nanoparticulate imaging agents have thus far achieved only limited clinical use. The reasons for this restricted advancement include an evolving scope of applications, the simplicity and effectiveness of existing small-molecule agents, pharmacokinetic limitations, safety concerns, and a complex regulatory environment. This review describes general features of nanoparticulate imaging agents and therapeutics and discusses challenges associated with clinical translation. A second, related review to appear in a subsequent issue of JNM highlights nuclear-based nanoparticulate probes in preclinical cardiovascular imaging. © 2015 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

Universal size effects for populations in group-outcome decision-making problems

NASA Astrophysics Data System (ADS)

Borghesi, Christian; Hernández, Laura; Louf, Rémi; Caparros, Fabrice

2013-12-01

Elections constitute a paradigm of decision-making problems that have puzzled experts of different disciplines for decades. We study two decision-making problems, where groups make decisions that impact only themselves as a group. In both studied cases, participation in local elections and the number of democratic representatives at different scales (from local to national), we observe a universal scaling with the constituency size. These results may be interpreted as constituencies having a hierarchical structure, where each group of N agents, at each level of the hierarchy, is divided in about Nδ subgroups with δ≈1/3. Following this interpretation, we propose a phenomenological model of vote participation where abstention is related to the perceived link of an agent to the rest of the constituency and which reproduces quantitatively the observed data.

Exposure of research personnel to carbon dioxide during euthanasia procedures.

PubMed

Amparan, Ashlee A; Djoufack-Momo, Shelly M; Grunden, Beverly; Boivin, Gregory P-

2014-07-01

CO₂ is one of the most commonly used euthanasia agents for laboratory animals. Considerable research has gone into the effect of the agent on animals, but little has been done to examine potential human exposure during these procedures. In this study, we examine the CO₂ concentrations to which personnel are exposed while euthanizing rodents with CO₂. To examine the environmental levels of CO₂ generated during euthanasia, we examined several variables including flow rate, inclusion of a cage in the euthanasia chamber, inversion of the euthanasia chamber, chamber size, distance from the euthanasia chamber, and room size. Under all conditions, CO₂ concentrations in the room temporarily increased significantly to 600 to 4000 ppm. The results of this study show that, under several testing scenarios, occupational levels of CO₂ did not exceed governmentally mandated allowable exposure limits during routine rodent euthanasia procedures.

Fluorescent immunolabeling of cancer cells by quantum dots and antibody scFv fragment.

PubMed

Zdobnova, Tatiana A; Dorofeev, Sergey G; Tananaev, Piter N; Vasiliev, Roman B; Balandin, Taras G; Edelweiss, Eveline F; Stremovskiy, Oleg A; Balalaeva, Irina V; Turchin, Ilya V; Lebedenko, Ekaterina N; Zlomanov, Vladimir P; Deyev, Sergey M

2009-01-01

Semiconductor quantum dots (QDs) coupled with cancer-specific targeting ligands are new promising agents for fluorescent visualization of cancer cells. Human epidermal growth factor receptor 2/neu (HER2/neu), overexpressed on the surface of many cancer cells, is an important target for cancer diagnostics. Antibody scFv fragments as a targeting agent for direct delivery of fluorophores offer significant advantages over full-size antibodies due to their small size, lower cross-reactivity, and immunogenicity. We have used quantum dots linked to anti-HER2/neu 4D5 scFv antibody to label HER2/neu-overexpressing live cells. Labeling of target cells was shown to have high brightness, photostability, and specificity. The results indicate that construction based on quantum dots and scFv antibody can be successfully used for cancer cell visualization.

Effects of dispersion solvent on the formation of silicon nanoparticles synthesized via microemulsion route

NASA Astrophysics Data System (ADS)

Liong, W. L.; Sreekantan, S.; Hutagalung, S. D.

2010-05-01

Silicon nanoparticles are synthesized by microemulsion route. Silicon tetrachloride (SiCl4) is used as a silicon source. Meanwhile, hydrazine (N2H5OH), sodium hydroxide (NaOH), and polyethylene glycol (PEG) are used as reduction agent, stabilizer, and capping agent, respectively. In this study, the effects of different solvents (methanol, 1-butanol, 2-propanol, ethanol, acetone, and toluene) on the dispersion and the stabilization of silicon nanoparticles are studied intensively. The results in this study show that ethanol solvent has given smaller particle size, better size distribution, stable suspension and well dispersion of silicon nanoparticles. The diameter of synthesized silicon nanoparticles is in the range of 30-100 nm. Moreover, the absorption edge of silicon nanoparticles in ethanol is observed at a shorter wavelength compared to the others solvent.

Encapsulation of nanoclusters in dried gel materials via an inverse micelle/sol gel synthesis

DOEpatents

Martino, A.; Yamanaka, S.A.; Kawola, J.S.; Showalter, S.K.; Loy, D.A.

1998-09-29

A dried gel material sterically entrapping nanoclusters of a catalytically active material and a process to make the material via an inverse micelle/sol-gel synthesis are disclosed. A surfactant is mixed with an apolar solvent to form an inverse micelle solution. A salt of a catalytically active material, such as gold chloride, is added along with a silica gel precursor to the solution to form a mixture. To the mixture are then added a reducing agent for the purpose of reducing the gold in the gold chloride to atomic gold to form the nanoclusters and a condensing agent to form the gel which sterically entraps the nanoclusters. The nanoclusters are normally in the average size range of from 5--10 nm in diameter with a monodisperse size distribution. 1 fig.

Fabrication of naphthalocyanine nanoparticles by laser ablation in liquid and application to contrast agents for photoacoustic imaging

NASA Astrophysics Data System (ADS)

Yanagihara, Ryuga; Asahi, Tsuyoshi; Ishibashi, Yukihide; Odawara, Osamu; Wada, Hiroyuki

2018-03-01

Naphthalocyanine nanoparticles were prepared by laser ablation in liquid using second-harmonics of nanosecond Nd:YAG laser as an excitation light sauce at various laser fluence, and the properties of naphthalocyanine nanoparticles, such as shape, size, zeta potential, chemical structure and optical absorption were examined. The scanning electron microscopy (SEM) and dynamic light scattering (DLS) measurements showed that the particle size of the nanoparticles could be controlled by the laser fluence. The IR spectra of the nanoparticles indicated the formation of carboxylate anion species at laser fluences above 100 mJ/cm2, which will result the zeta potential of the nanoparticles depending on the laser fluence. We also examined the potential application to contrast agents for photoacoustic, and confirmed that the naphthalocyanine nanoparticles generated a strong photoacoustic signal.

Photophysical characterization of fluorescent metal nanoclusters synthesized using oligonucleotides, proteins and small molecule ligands

NASA Astrophysics Data System (ADS)

Yeh, Hsin-Chih; Sharma, Jaswinder; Yoo, Hyojong; Martinez, Jennifer S.; Werner, James H.

2010-02-01

The size transition from bulk conducting metals to insulating nanoparticles and eventually to single atoms passes through the relatively unexplored few-atom nanocluster region. With dimensions close to the Fermi wavelength, these nanoclusters demonstrate molecule-like properties distinct from bulk metals or atoms, such as discrete and size-tunable electronic transitions which lead to photoluminescence. Current research aims to elucidate the fundamental photophysical properties of metal nanoclusters made by different means and based on different encapsulation agents. Here, we report the study of the photophysical properties, including quantum yields, lifetimes, extinction coefficients, blinking dynamics and sizes, of silver and gold nanoclusters synthesized using oligonucleotides, a protein (bovine serum albumin) and a Good's buffer molecule (MES, 2-(N-morpholino) ethanesulfonic acid) as encapsulation agents. We also investigate the change of photoluminescence as a function of temperature. Furthermore, we show that the fluorescent metal clusters can be used as a donor in forming a resonance energy transfer pair with a commercial organic quencher. These new fluorophores have great potential as versatile tools for a broad range of applications in biological and chemical detection.

Small Peptides Derived from Penetratin as Antibacterial Agents.

PubMed

Parravicini, Oscar; Somlai, Csaba; Andujar, Sebastián A; Garro, Adriana D; Lima, Beatriz; Tapia, Alejandro; Feresin, Gabriela; Perczel, Andras; Tóth, Gabor; Cascales, Javier López; Rodríguez, Ana M; Enriz, Ricardo D

2016-04-01

The synthesis, in vitro evaluation and conformational study of several small-size peptides acting as antibacterial agents are reported. Among the compounds evaluated, the peptides Arg-Gln-Ile-Lys-Ile-Trp-Arg-Arg-Met-Lys-Trp-Lys-Lys-NH2 , Arg-Gln-Ile-Lys-Ile-Arg-Arg-Met-Lys-Trp-Arg-NH2 , and Arg-Gln-Ile-Trp-Trp-Trp-Trp-Gln-Arg-NH2 exhibited significant antibacterial activity. These were found to be very active antibacterial compounds, considering their small molecular size. In order to better understand the antibacterial activity obtained for these peptides, an exhaustive conformational analysis was performed, using both theoretical calculations and experimental measurements. Molecular dynamics simulations using two different media (water and trifluoroethanol/water) were employed. The results of these theoretical calculations were corroborated by experimental circular dichroism measurements. A brief discussion on the possible mechanism of action of these peptides at molecular level is also presented. Some of the peptides reported here constitute very interesting structures to be used as starting compounds for the design of new small-size peptides possessing antibacterial activity. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

In situ characterization of silver nanoparticle synthesis in maltodextrin supramolecular structures

DOE PAGES

Bell, Nelson S.; Dunphy, Darren R.; Lambert, Timothy N.; ...

2015-06-26

In this study, the use of maltodextrin supramolecular structures (MD SMS) as a reducing agent and colloidal stabilizing agent for the synthesis of Ag nanoparticles (Ag NPs) identified three key points. First, the maltodextrin (MD) solutions are effective in the formation of well-dispersed Ag NPs utilizing alkaline solution conditions, with the resulting Ag NPs ranging in size from 5 to 50 nm diameter. Second, in situ characterization by Raman spectroscopy and small angle X-ray scattering (SAXS) are consistent with initial nucleation of Ag NPs within the MD SMS up to a critical size of ca. 1 nm, followed by amore » transition to more rapid growth by aggregation and fusion between MD SMS, similar to micelle aggregation reactions. Third, the stabilization of larger Ag NPs by adsorbed MD SMS is similar to hemi-micelle stabilization, and monomodal size distributions are proposed to relate to integer surface coverage of the Ag NPs. Conditions were identified for preparing Ag NPs with monomodal distributions centered at 30–35 nm Ag NPs.« less

Synthesis of cadmium sulfide in situ in reverse micelles and in hydrocarbon gels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Petit, C.; Pileni, M.P.

1988-04-21

The synthesis in situ of cadmium sulfide semiconductors in AOT reverse micelles produces smaller and more monodispersed particles than are obtained in Triton reverse micelles or in aqueous solution. When gelatine is added to the previous solution, the semiconductor is entrapped in a hydrocarbon gel and it size remains the same as that obtained in reverse micelles. The size of the sulfite cadmium aggregate formed in AOT hydrocarbon gels is similar to that obtained under similar conditions in AOT reverse micelles. AOT surfactant can play the role of stabilizing agent. However, a more efficient stabilization is obtained by adding tomore » AOT reverse micelles another stabilizing agent such as sodium hexametaphosphate. The crystallite size is strongly dependent on the ratio of the cadmium and sulfur ions, defined by x = (Cd/sup 2 +/)/(S/sup 2 -//. The yield of reduced viologen obtained by CdS irradiation in AOT reverse micelles is 15 times more efficient than that formed in aqueous solutions whereas it is only three times more in hydrocarbon gels.« less

Size tuned polyol-made Zn0.9M0.1Fe2O4 (M = Mn, Co, Ni) ferrite nanoparticles as potential heating agents for magnetic hyperthermia: from synthesis control to toxicity survey

NASA Astrophysics Data System (ADS)

Basti, H.; Hanini, A.; Levy, M.; Ben Tahar, L.; Herbst, F.; Smiri, L. S.; Kacem, K.; Gavard, J.; Wilhelm, C.; Gazeau, F.; Chau, F.; Ammar, S.

2014-12-01

Zn-rich substituted Zn0.9M0.1Fe2O4 (M = Mn, Co, Ni) ferrite nanoparticles (NPs) of about 5 and 10 nm were produced by the so-called polyol method. They were engineered for hyperthermia therapy based on their magnetic and morphological properties. Indeed, because of their comparatively low Curie temperature and reasonable magnetization, these probes may turn into useful self-regulated heating agents under suitable conditions. For such a purpose, the structure, the microstructure, the magnetic and magnetocalorimetric properties of the produced NPs as well as their in vitro cytotoxicity were investigated. Our results demonstrate that the magnetic properties of these magnetically diluted spinel ferrite particles can be largely modified by just changing their size. They also show that the about 10 nm sized manganese-based ones exhibit the highest heating power under a 700 kHz ac magnetic field and the lowest cytotoxicity on Immortalized human umbilical vascular endothelial cells (HUVEC).

Highly bacterial resistant silver nanoparticles: synthesis and antibacterial activities

NASA Astrophysics Data System (ADS)

Chudasama, Bhupendra; Vala, Anjana K.; Andhariya, Nidhi; Mehta, R. V.; Upadhyay, R. V.

2010-06-01

In this article, we describe a simple one-pot rapid synthesis route to produce uniform silver nanoparticles by thermal reduction of AgNO3 using oleylamine as reducing and capping agent. To enhance the dispersal ability of as-synthesized hydrophobic silver nanoparticles in water, while maintaining their unique properties, a facile phase transfer mechanism has been developed using biocompatible block co-polymer pluronic F-127. Formation of silver nanoparticles is confirmed by X-ray diffraction (XRD), transmission electron microscopy (TEM) and UV-vis spectroscopy. Hydrodynamic size and its distribution are obtained from dynamic light scattering (DLS). Hydrodynamic size and size distribution of as-synthesized and phase transferred silver nanoparticles are 8.2 ± 1.5 nm (σ = 18.3%) and 31.1 ± 4.5 nm (σ = 14.5%), respectively. Antimicrobial activities of hydrophilic silver nanoparticles is tested against two Gram positive ( Bacillus megaterium and Staphylococcus aureus), and three Gram negative ( Escherichia coli, Proteus vulgaris and Shigella sonnei) bacteria. Minimum inhibitory concentration (MIC) values obtained in the present study for the tested microorganisms are found much better than those reported for commercially available antibacterial agents.

Fabrication and performance of porous lithium sodium potassium niobate ceramic

NASA Astrophysics Data System (ADS)

Chen, Caifeng; Zhu, Yuan; Ji, Jun; Cai, Feixiang; Zhang, Youming; Zhang, Ningyi; Wang, Andong

2018-02-01

Porous lithium sodium potassium niobate (LNK) ceramic has excellent piezoelectric properties, chemical stability and great chemical compatibility. It has a good application potential in the field of biological bone substitute. In the paper, porous LNK ceramic was fabricated with egg albumen foaming agent by foaming method. Effects of preparation process of the porous LNK ceramic on density, phase structure, hole size and piezoelectric properties were researched and characterized. The results show that the influence factors of LNK solid content and foaming agent addition are closely relevant to properties of the porous LNK ceramic. When solid content is 65% and foaming agent addition is 30%, the porous LNK ceramic has uniform holes and the best piezoelectric properties.

Wash water waste pretreatment system

NASA Technical Reports Server (NTRS)

1977-01-01

Investigations were completed on wash waters based on each candidate personal cleansing agent. Evaluations of coagulants, antifoam agents, and the effect of promising antifoams on the chemical precipitation were included. Based on these evaluations two candidate soaps as well as their companion antifoam agents were selected for further work. Operating parameters included the effect of soap concentration, ferric chloride concentration, duration of mixing, and pore size of depth filters on the degree of soap removal. The effect of pressure on water flow through filter cartridges and on the rate of decline of water flow was also investigated. The culmination of the program was the recommendation of a pretreatment concept based on chemical precipitation followed by pressure filtration.

Young Citizens as Health Agents: Use of Drama in Promoting Community Efficacy for HIV/AIDS

PubMed Central

Kamo, Norifumi; Carlson, Mary; Brennan, Robert T.; Earls, Felton

2008-01-01

A community-based cluster randomized control trial in a medium-sized municipality in Tanzania was designed to increase local competence to control HIV/AIDS through actions initiated by children and adolescents aged 10 to 14 years. Representative groups from the 15 treatment communities reached mutual understanding about their objectives as health agents, prioritized their actions, and skillfully applied community drama (“skits”) to impart knowledge about the social realities and the microbiology of HIV/AIDS. In independently conducted surveys of neighborhood residents, differences were found between adults who did and did not witness the skits in their beliefs about the efficacy of children as HIV/AIDS primary change agents. PMID:18172136

Young citizens as health agents: use of drama in promoting community efficacy for HIV/AIDS.

PubMed

Kamo, Norifumi; Carlson, Mary; Brennan, Robert T; Earls, Felton

2008-02-01

A community-based cluster randomized control trial in a medium-sized municipality in Tanzania was designed to increase local competence to control HIV/AIDS through actions initiated by children and adolescents aged 10 to 14 years. Representative groups from the 15 treatment communities reached mutual understanding about their objectives as health agents, prioritized their actions, and skillfully applied community drama ("skits") to impart knowledge about the social realities and the microbiology of HIV/AIDS. In independently conducted surveys of neighborhood residents, differences were found between adults who did and did not witness the skits in their beliefs about the efficacy of children as HIV/AIDS primary change agents.

On the Fair Division of Multiple Stochastic Pies to Multiple Agents within the Nash Bargaining Solution

PubMed Central

Karmperis, Athanasios C.; Aravossis, Konstantinos; Tatsiopoulos, Ilias P.; Sotirchos, Anastasios

2012-01-01

The fair division of a surplus is one of the most widely examined problems. This paper focuses on bargaining problems with fixed disagreement payoffs where risk-neutral agents have reached an agreement that is the Nash-bargaining solution (NBS). We consider a stochastic environment, in which the overall return consists of multiple pies with uncertain sizes and we examine how these pies can be allocated with fairness among agents. Specifically, fairness is based on the Aristotle’s maxim: “equals should be treated equally and unequals unequally, in proportion to the relevant inequality”. In this context, fairness is achieved when all the individual stochastic surplus shares which are allocated to agents are distributed in proportion to the NBS. We introduce a novel algorithm, which can be used to compute the ratio of each pie that should be allocated to each agent, in order to ensure fairness within a symmetric or asymmetric NBS. PMID:23024752

Development of high temperature resistant graphite fiber coupling agents

NASA Technical Reports Server (NTRS)

Griffin, R. N.

1975-01-01

Surface treatments were investigated as potential coupling agents to improve the elevated temperature shear strength retention of polyimide/graphite and polyphenylquinoxaline/graphite composites. The potential coupling agents were evaluated by fiber strand tensile tests, fiber and composite weight losses at 533 and 588K, and by interlaminar shear strength retention at 533 and 588K. The two surface treatments selected for more extensive evaluation were a coating of Ventromer T-1, a complex organometallic reaction product of titanium tetrachloride and trimethyl borate, and a polyphenylquinoxaline (PPQ) sizing which was pyrolyzed in nitrogen to form a carbonaceous layer on the fiber. Pyrolyzed polyphenylquinoxaline is a satisfactory coupling agent for polyimide/Thornel 300 graphite fiber composites. During 1000 hours aging at 588K such composites lose a little over half their transverse tensile strength, and suffer a slight loss in flexural modulus. No degradation of flexural strength or interlaminar shear strength occured during 1000 hours aging at 588K. None of the coupling agents examined had a markedly beneficial effect with polyphenylquinoxaline composites.

Physical properties of organic particulate UV-absorbers used in sunscreens. I. Determination of particle size with fiber-optic quasi-elastic light scattering (FOQELS), disc centrifugation, and laser diffractometry.

PubMed

Herzog, Bernd; Katzenstein, Armin; Quass, Katja; Stehlin, Albert; Luther, Helmut

2004-03-01

In this study microparticles consisting of a benzotriazole derivative, which are used as absorbers for UV radiation in cosmetic sunscreens, were investigated. The particles were micronized in presence of a dispersing agent by means of a ball milling process. According to the energy input different particle sizes were produced in the range of 0.16 to 4 microm. The particle sizes obtained after different stages of the micronization process were measured using fiber-optic quasi-elastic light scattering (FOQELS), disc centrifugation, and laser diffractometry. All methods showed satisfactory agreement over the whole range of sizes. With the FOQELS technique the particle size distribution could be resolved to sizes well below 0.1 microm.

Novel thick-foam ferroelectret with engineered voids for energy harvesting applications

NASA Astrophysics Data System (ADS)

Luo, Z.; Shi, J.; Beeby, S. P.

2016-11-01

This work reports a novel thick-foam ferroelectret which is designed and engineered for energy harvesting applications. We fabricated this ferroelectret foam by mixing a chemical blowing agent with a polymer solution, then used heat treatment to activate the agent and create voids in the polymer foam. The dimensions of the foam, the density and size of voids can be well controlled in the fabrication process. Therefore, this ferroelectret can be engineered into optimized structure for energy harvesting applications.

Enhanced catalytic activity through the tuning of micropore environment and supercritical CO2 processing: Al(porphyrin)-based porous organic polymers for the degradation of a nerve agent simulant.

PubMed

Totten, Ryan K; Kim, Ye-Seong; Weston, Mitchell H; Farha, Omar K; Hupp, Joseph T; Nguyen, SonBinh T

2013-08-14

An Al(porphyrin) functionalized with a large axial ligand was incorporated into a porous organic polymer (POP) using a cobalt-catalyzed acetylene trimerization strategy. Removal of the axial ligand afforded a microporous POP that is catalytically active in the methanolysis of a nerve agent simulant. Supercritical CO2 processing of the POP dramatically increased the pore size and volume, allowing for significantly higher catalytic activities.

[Chemoembolization of symptomatic bone metastases: technical considerations and therapeutic effectiveness].

PubMed

Clarençon, F; Cormier, E; Di Maria, F; Sourour, N-A; Szatmary, Z; Rose, M; Chiras, J

2011-09-01

Chemoembolization of bone metastases is defined by the intraarterial perfusion of a chemotherapy agent followed by microparticles embolization to improve tissue impregnation. This technique increases the local concentration of the chemotherapy agent. Tumor response (stable or reduced tumor size) is achieved in 30-80% of cases with symptomatic relief in over 80% of cases. The indications, technical considerations, and effectiveness of this procedure will be reviewed. Copyright © 2011 Elsevier Masson SAS and Éditions françaises de radiologie. All rights reserved.

Imaging of Ep-CAM Positive Metastatic Cancer in the Lymph System

DTIC Science & Technology

2011-01-01

bind Ep-CAM positive breast cancer cells in pH up to 8.3, which will be important for the chelating agent DOTA . The DOTA -NHS-ester is best conjugated...must be conjugated with the fluorophore (IRDye 800CW) and a chelating agent ( DOTA ), which sequesters the radio-metal completing the dual-label...done simultaneously, anti-Ep-CAM (9601) was conjugated with 5-fold excess IRDye, 5- fold excess DOTA or 500-fold excess DOTA overnight. After size

Laser Based Stand-Off Detection of Biological Agents (detection a distance des agents biologiques a l’aide du laser)

DTIC Science & Technology

2010-02-01

overview of their respective national up-date. Dr. Roy presented a new technique for evaluating the bioaerosol particle size based on a multiple...Field-of-View LIDAR technique . Mr. Levesque from INO gave an overview of their expertise in LIDAR and biophotonics. Dr. Chin from Laval University gave... techniques have the potential to detect particulate aerosols remotely at distances of many kilometres [1]. They can provide spatially resolved

Antigiardial activity of glycoproteins and glycopeptides from Ziziphus honey.

PubMed

Mohammed, Seif Eldin A; Kabashi, Ahmed S; Koko, Waleed S; Azim, M Kamran

2015-01-01

Natural honey contains an array of glycoproteins, proteoglycans and glycopeptides. Size-exclusion chromatography fractionated Ziziphus honey proteins into five peaks with molecular masses in the range from 10 to >200 kDa. The fractionated proteins exhibited in vitro activities against Giardia lamblia with IC50 values ≤ 25 μg/mL. Results indicated that honey proteins were more active as antiprotozoal agents than metronidazole. This study indicated the potential of honey proteins and peptides as novel antigiardial agents.

Nanobubble-Affibody: Novel ultrasound contrast agents for targeted molecular ultrasound imaging of tumor.

PubMed

Yang, Hengli; Cai, Wenbin; Xu, Lei; Lv, Xiuhua; Qiao, Youbei; Li, Pan; Wu, Hong; Yang, Yilin; Zhang, Li; Duan, Yunyou

2015-01-01

Nanobubbles (NBs), as novel ultrasound contrast agents (UCAs), have attracted increasing attention in the field of molecular ultrasound imaging for tumors. However, the preparation of uniform-sized NBs is considered to be controversial, and poor tumor selectivity in in vivo imaging has been reported. In this study, we fabricated uniform nano-sized NBs (478.2 ± 29.7 nm with polydispersity index of 0.164 ± 0.044, n = 3) using a thin-film hydration method by controlling the thickness of phospholipid films; we then conjugated the NBs with Affibody molecules to produce nano-sized UCAs referred to as NB-Affibody with specific affinity to human epidermal growth factor receptor type 2 (HER2)-overexpressing tumors. NB-Affibody presented good ultrasound enhancement, demonstrating a peak intensity of 104.5 ± 2.1 dB under ultrasound contrast scanning. Ex vivo experiments further confirmed that the NB-Affibody conjugates were capable of targeting HER2-expressing tumor cells in vivo with high affinity. The newly prepared nano-sized NB-Affibody conjugates were observed to be novel targeted UCAs for efficient and safe specific molecular imaging and may have potential applications in early cancer quantitative diagnosis and targeted therapy in the future. Copyright © 2014 Elsevier Ltd. All rights reserved.

Evaluation of agarose gel electrophoresis for characterization of silver nanoparticles in industrial products.

PubMed

Jimenez, Maria S; Luque-Alled, Jose M; Gomez, Teresa; Castillo, Juan R

2016-05-01

Agarose gel electrophoresis (AGE) has been used extensively for characterization of pure nanomaterials or mixtures of pure nanomaterials. We have evaluated the use of AGE for characterization of Ag nanoparticles (NPs) in an industrial product (described as strong antiseptic). Influence of different stabilizing agents (PEG, SDS, and sodium dodecylbenzenesulfonate), buffers (TBE and Tris Glycine), and functionalizing agents (mercaptosuccinic acid (TMA) and proteins) has been investigated for the characterization of AgNPs in the industrial product using different sizes-AgNPs standards. The use of 1% SDS, 0.1% TMA, and Tris Glycine in gel, electrophoresis buffer and loading buffer led to the different sizes-AgNPs standards moved according to their size/charge ratio (obtaining a linear relationship between apparent mobility and mean diameter). After using SDS and TMA, the behavior of the AgNPs in the industrial product (containing a casein matrix) was completely different, being not possible their size characterization. However we demonstrated that AGE with LA-ICP-MS detection is an alternative method to confirm the protein corona formation between the industrial product and two proteins (BSA and transferrin) maintaining NPs-protein binding (what is not possible using SDS-PAGE). © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Alkalinity of non-industrial cleaning products and the likelihood of producing significant esophageal burns.

PubMed

Howell, J M

1991-11-01

Alkaline cleaning products are a cause of serious esophageal injury. Over time, legislation has diminished the concentration of many such non-industrial solutions and solids; however several products presently do not list either the pH or relative concentrations of alkaline constituents. This study measures the pHs of several non-industrial cleaning products containing either ammonium chloride, sodium hydroxide, or potassium hydroxide. Three pH measurements were performed on each of 10 non-industrial alkaline cleaning products (eight liquid, two solid). Two 0.1% ammonium chloride solutions had pHs of 12.06 +/- 0.00 and 12.06 +/- 0.01, whereas a pH of 12.43 +/- 0.00 was recorded in a 0.2% ammonium chloride solution. Concentrations of sodium hydroxide and potassium hydroxide were listed on only one of five liquid cleaning product labels. The pHs for these five products varied between 12.83 +/- 0.009 and 13.5 +/- .0.2. The pHs of three sodium hydroxide solutions differed from values reported in Micromedex (Micromedex Inc, Denver CO) by up to 0.32 pH units. Ten percent (v/v) solutions of two solid lye products had pHs of 13.62 +/- 0.008 and 13.74 +/- 0.02. The investigator found that selected non-industrial cleaning products, including ammonia solutions, retain the ability to cause clinically important esophageal damage.

Determination of 15 polycyclic aromatic hydrocarbons in aquatic products by solid-phase extraction and GC-MS.

PubMed

Liu, Qiying; Guo, Yuanming; Sun, Xiumei; Hao, Qing; Cheng, Xin; Zhang, Lu

2018-02-22

We propose a method for the simultaneous determination of 15 kinds of polycyclic aromatic hydrocarbons in marine samples (muscle) employing gas chromatography with mass spectrometry after saponification with ultrasound-assisted extraction and solid-phase extraction. The experimental conditions were optimized by the response surface method. In addition, the effects of different lyes and extractants on polycyclic aromatic hydrocarbons extraction were discussed, and saturated sodium carbonate was first used as the primary saponification reaction and extracted with 10 mL of ethyl acetate and secondly 1 mol/L of sodium hydroxide and 10 mL of n-hexane were used to achieve better results. The average recovery was 67-112%. Satisfactory data showed that the method has good reproducibility with a relative standard deviation of <13%. The detection limits of polycyclic aromatic hydrocarbons were 0.02-0.13 ng/g. Compared with other methods, this method has the advantages of simple pretreatment, low solvent consumption, maximum polycyclic aromatic hydrocarbons extraction, the fast separation speed, and the high extraction efficiency. It is concluded that this method meets the batch processing requirements of the sample and can also be used to determine polycyclic aromatic hydrocarbons in other high-fat (fish, shrimp, crab, shellfish) biological samples. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Optimization of Ripe Olive Processing with a Single Lye Treatment.

PubMed

Brenes, Manuel; Romero, Concepción; García-García, Pedro

2017-09-01

The development of a method for darkening black ripe olives during the washing step with a single NaOH treatment and preservation liquid was studied. Olives of the Hojiblanca cultivar were darkened at pilot plant scale, packed, sterilized, and analyzed after 2 mo of storage at ambient temperature. It was found that the use of a mixture of preservation liquid:water at a ratio of 1:1 during the first washing gave rise to darker olives with slightly better firmness and no effect on sensory quality. However, care must be taken with the concentration of acetic acid in the preservation solution, as a content of this organic acid higher than 25 g/L can cause adverse effects on olive color due to the low pH that can be reached in the flesh of the fruit. Additionally, the re-use of the preservation solution in the first washing resulted in enrichment in antioxidant compounds of the packed product. Black ripe olives processed with preservation liquid had a total phenolic content of 629 mg/kg, whereas those with only tap water had 376 mg/kg, in particular hydroxytyrosol and hydroxytyrosol-4-glucoside. These findings mean that it is possible to get darker olives with higher contents in bioactive substances by reusing the preservation liquid during the darkening step of black ripe olives. © 2017 Institute of Food Technologists®.

Role of noise and agents’ convictions on opinion spreading in a three-state voter-like model

NASA Astrophysics Data System (ADS)

Crokidakis, Nuno

2013-07-01

In this work we study opinion formation in a voter-like model defined on a square lattice of linear size L. The agents may be in three different states, representing any public debate with three choices (yes, no, undecided). We consider heterogeneous agents that have different convictions about their opinions. These convictions limit the capacity of persuasion of the individuals during the interactions. Moreover, there is a noise p that represents the probability of an individual spontaneously changing his opinion to the undecided state. Our simulations suggest that the system reaches stationary states for all values of p, with consensus states occurring only for the noiseless case p = 0. In this case, the relaxation times are distributed according to a log-normal function, with the average value τ growing with the lattice size as τ ∼ Lα, where α ≈ 0.9. We found a threshold value p* ≈ 0.9 above which the stationary fraction of undecided agents is greater than the fraction of decided ones. We also study the consequences of the presence of external effects in the system, which models the influence of mass media on opinion formation.

Numerical Modeling of Nanocellular Foams Using Classical Nucleation Theory and Influence Volume Approach

NASA Astrophysics Data System (ADS)

Khan, Irfan; Costeux, Stephane; Bunker, Shana; Moore, Jonathan; Kar, Kishore

2012-11-01

Nanocellular porous materials present unusual optical, dielectric, thermal and mechanical properties and are thus envisioned to find use in a variety of applications. Thermoplastic polymeric foams show considerable promise in achieving these properties. However, there are still considerable challenges in achieving nanocellular foams with densities as low as conventional foams. Lack of in-depth understanding of the effect of process parameters and physical properties on the foaming process is a major obstacle. A numerical model has been developed to simulate the simultaneous nucleation and bubble growth during depressurization of thermoplastic polymers saturated with supercritical blowing agents. The model is based on the popular ``Influence Volume Approach,'' which assumes a growing boundary layer with depleted blowing agent surrounds each bubble. Classical nucleation theory is used to predict the rate of nucleation of bubbles. By solving the mass balance, momentum balance and species conservation equations for each bubble, the model is capable of predicting average bubble size, bubble size distribution and bulk porosity. The model is modified to include mechanisms for Joule-Thompson cooling during depressurization and secondary foaming. Simulation results for polymer with and without nucleating agents will be discussed and compared with experimental data.

Water as foaming agent for open cell polyurethane structures.

PubMed

Haugen, H; Ried, V; Brunner, M; Will, J; Wintermantel, E

2004-04-01

The problem of moisture in polymer processing is known to any polymer engineer, as air bubbles may be formed. Hence granulates are generally dried prior to manufacturing. This study tried to develop a novel processing methods for scaffolds with controlled moisture content in thermoplastic polyurethane. The common foaming agents for polyurethane are organic solvents, whose residues remaining in the scaffold may be harmful to adherent cells, protein growth factors or nearby tissues. Water was used as a foaming agent and NaCl was used as porogens to achieve an open-cell structure. The polyether-polyurethane samples were processed in a heated press, and achieved a porosity of 64%. The pore size ranged between 50 and 500 microm. Human fibroblasts adhered and proliferate in the scaffold. A non-toxic production process was developed to manufacture a porous structure with a thermoplastic polyether-polyurethane. The process enables a mass-production of samples with adjustable pore size and porosity. In contrast to an existing method (solvent casting), the processing of the samples was not limited by its thickness. The process parameters, which attribute mostly to the pore building, were filling volume, temperature, NaCl-concentration and water-uptake rate.

Synthesis and characterization of melamine-urea-formaldehyde microcapsules containing ENB-based self-healing agents

NASA Astrophysics Data System (ADS)

Liu, Xing; Sheng, Xia; Lee, Jong Keun; Kessler, Michael R.

2007-07-01

Microcapsules for self-healing applications were produced with a melamine-urea-formaldehyde (MUF) polymer shell containing two different healing agent candidates, ENB (5-ethylidene-2-norbornene) and ENB with 10 wt.% of a norbornene based crosslinking agent (CL), by in-situ polymerization in an oil-in-water emulsion. Relatively neat outer surfaces with minor roughness were observed on the MUF microcapsules under optical and scanning electron microscopy. Shell thickness of the capsules ranged from 700 to 900 nm. Particle size analysis of the microcapsules showed narrow size distributions with a mean diameter of 113 μm for ENB-filled and 122 μm for ENB+CL-filled microcapsules at an agitation rate of 500 rpm. The microcapsules were found to be thermally stable up to 300°C and exhibited a 10 to 15 % weight loss when isothermally held at 150°C for 2 hr from thermogravimetric analysis. Overall, these MUF microcapsules exhibited superior properties compared to the urea-formaldehyde (UF) microcapsules used extensively for self-healing composites to date. In addition, the manufacturing process of MUF microcapsules is much simpler than those made from UF. Additional advantages of MUF microcapsules for self-healing composites are discussed.

Elemental selenium at nano size (Nano-Se) as a potential chemopreventive agent with reduced risk of selenium toxicity: comparison with se-methylselenocysteine in mice.

PubMed

Zhang, Jinsong; Wang, Xufang; Xu, Tongwen

2008-01-01

Selenium (Se) is an essential trace element with a narrow margin between beneficial and toxic effects. As a promising chemopreventive agent, its use requires consumption over the long term, so the toxicity of Se is always a crucial concern. Based on clinical findings and recent studies in selenoprotein gene-modified mice, it is likely that the antioxidant function of one or more selenoproteins is responsible for the chemopreventive effect of Se. Furthermore, upregulation of phase 2 enzymes by Se has been implicated as a possible chemopreventive mechanism at supranutritional dietary levels. Se-methylselenocysteine (SeMSC), a naturally occurring organic Se product, is considered as one of the most effective chemopreventive selenocompounds. The present study revealed that, as compared with SeMSC, elemental Se at nano size (Nano-Se) possessed equal efficacy in increasing the activities of glutathione peroxidase, thioredoxin reductase, and glutathione S-transferase, but had much lower toxicity as indicated by median lethal dose, acute liver injury, survival rate, and short-term toxicity. Our results suggest that Nano-Se can serve as a potential chemopreventive agent with reduced risk of Se toxicity.

Acoustically active lipospheres containing paclitaxel: a new therapeutic ultrasound contrast agent.

PubMed

Unger, E C; McCreery, T P; Sweitzer, R H; Caldwell, V E; Wu, Y

1998-12-01

Paclitaxel-carrying lipospheres (MRX-552) were developed and evaluated as a new ultrasound contrast agent for chemotherapeutic drug delivery. Paclitaxel was suspended in soybean oil and added to an aqueous suspension of phospholipids in vials. The headspace of the vials was replaced with perfluorobutane gas; the vials were sealed, and they were agitated at 4200 rpm on a shaking device. The resulting lipospheres containing paclitaxel were studied for concentration, size, acute toxicity in mice, and acoustic activity and drug release with ultrasound. Lipospheres containing sudan black dye were produced to demonstrate the acoustically active liposphere (AAL)-ultrasound release concept. Acoustically active lipospheres containing paclitaxel had a mean particle count of approximately 1 x 10(9) particles per mL and a mean size of 2.9 microns. Acute toxicity studies in mice showed a 10-fold reduction in toxicity for paclitaxel in AALs compared with free paclitaxel. The AALs reflected ultrasound as a contrast agent. Increasing amounts of ultrasound energy selectively ruptured the AALs and released the paclitaxel. Acoustically active lipospheres represent a new class of acoustically active drug delivery vehicles. Future studies will assess efficacy of AALs for ultrasound-mediated drug delivery.

Self-Assembled Nanomicelles as MRI Blood-Pool Contrast Agent.

PubMed

Babič, Andrej; Vorobiev, Vassily; Xayaphoummine, Céline; Lapicorey, Gaëlle; Chauvin, Anne-Sophie; Helm, Lothar; Allémann, Eric

2018-01-26

Gadolinium-loaded nanomicelles show promise as future magnetic resonance imaging (MRI) contrast agents (CAs). Their increased size and high gadolinium (Gd) loading gives them an edge in proton relaxivity over smaller molecular Gd-complexes. Their size and stealth properties are fundamental for their long blood residence time, opening the possibility for use as blood-pool contrast agents. Using l-tyrosine as a three-functional scaffold we synthesized a nanostructure building block 8. The double C18 aliphatic chain on one side, Gd-1,4,7,10-tetraazacyclododecane-1-4-7-triacetic acid (Gd-DO3A) with access to bulk water in the center and 2 kDa PEG on the hydrophilic side gave the amphiphilic properties required for the core-shell nanomicellar architecture. The self-assembly into Gd-loaded monodispersed 10-20 nm nanomicelles occurred spontaneously in water. These nanomicelles (Tyr-MRI) display very high relaxivity at 29 mm -1  s -1 at low field strength and low cytotoxicity. Good contrast enhancement of the blood vessels and the heart together with prolonged circulation time in vivo, makes Tyr-MRI an excellent candidate for a new supramolecular blood-pool MRI CA. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Multi-stimuli responsive Cu2S nanocrystals as trimodal imaging and synergistic chemo-photothermal therapy agents

NASA Astrophysics Data System (ADS)

Poulose, Aby Cheruvathoor; Veeranarayanan, Srivani; Mohamed, M. Sheikh; Nagaoka, Yutaka; Romero Aburto, Rebeca; Mitcham, Trevor; Ajayan, Pulickel M.; Bouchard, Richard R.; Sakamoto, Yasushi; Yoshida, Yasuhiko; Maekawa, Toru; Sakthi Kumar, D.

2015-04-01

A size and shape tuned, multifunctional metal chalcogenide, Cu2S-based nanotheranostic agent is developed for trimodal imaging and multimodal therapeutics against brain cancer cells. This theranostic agent was highly efficient in optical, photoacoustic and X-ray contrast imaging systems. The folate targeted NIR-responsive photothermal ablation in synergism with the chemotherapeutic action of doxorubicin proved to be a rapid precision guided cancer-killing module. The multi-stimuli, i.e., pH-, thermo- and photo-responsive drug release behavior of the nanoconjugates opens up a wider corridor for on-demand triggered drug administration. The simple synthesis protocol, combined with the multitudes of interesting features packed into a single nanoformulation, clearly demonstrates the competing role of this Cu2S nanosystem in future cancer treatment strategies.A size and shape tuned, multifunctional metal chalcogenide, Cu2S-based nanotheranostic agent is developed for trimodal imaging and multimodal therapeutics against brain cancer cells. This theranostic agent was highly efficient in optical, photoacoustic and X-ray contrast imaging systems. The folate targeted NIR-responsive photothermal ablation in synergism with the chemotherapeutic action of doxorubicin proved to be a rapid precision guided cancer-killing module. The multi-stimuli, i.e., pH-, thermo- and photo-responsive drug release behavior of the nanoconjugates opens up a wider corridor for on-demand triggered drug administration. The simple synthesis protocol, combined with the multitudes of interesting features packed into a single nanoformulation, clearly demonstrates the competing role of this Cu2S nanosystem in future cancer treatment strategies. Electronic supplementary information (ESI) available: Methodology and additional experimental results. See DOI: 10.1039/c4nr07139e

Camptothecin-loaded fusogenic nanodroplets as ultrasound theranostic agent in stem cell-mediated drug-delivery system.

PubMed

Ho, Yi-Ju; Chiang, Yu-Jung; Kang, Shih-Tsung; Fan, Ching-Hsiang; Yeh, Chih-Kuang

2018-05-28

Adipose-derived stem cells (ADSCs) have been utilized in cellular delivery systems to carry therapeutic agents into tumors by migration. Drug-loaded nanodroplets release drugs and form bubbles after acoustic droplet vaporization (ADV) triggered by ultrasound stimulation, providing a system for ultrasound-induced cellular delivery of theranostic agents. In order to improve the efficiency of drug release, fusogenic nanodroplets were designed to go from nano to micron size upon uptake by ADSCs for reducing ADV threshold. The purpose of our study was to demonstrate the utility of camptothecin-loaded fusogenic nanodroplets (CPT-FNDs) as ultrasound theranostic agents in an ADSCs delivery system. CPT-FNDs showed an increase in size from 81.6 ± 3.5 to 1043.5 ± 28.3 nm and improved CPT release from 22.0 ± 1.8% to 37.6 ± 2.1%, demonstrating the fusion ability of CPT-FNDs. CPT-FNDs-loaded ADSCs demonstrated a cell viability of 77 ± 4%, and the in vitro migration ability was 3.2 ± 1.2-fold for the tumor condition compared to the cell growth condition. Ultrasound enhancement imaging showed intratumoral ADV-generated bubble formation (increasing 3.24 ± 0.47 dB) triggered by ultrasound after CPT-FNDs-loaded ADSCs migration into B16F0 tumors. Histological images revealed intratumoral distribution of CPT-FNDs-loaded ADSCs and tissue damage due to the ADV. The CPT-FNDs can be used as theranostic agents in an ADSCs delivery system to provide the ultrasound contrast imaging and deliver combination therapy of drug release and physical damage after ADV. Copyright © 2018 Elsevier B.V. All rights reserved.

Resistance to antimicrobial agents among Salmonella isolates recovered from layer farms and eggs in the Caribbean region.

PubMed

Adesiyun, Abiodun; Webb, Lloyd; Musai, Lisa; Louison, Bowen; Joseph, George; Stewart-Johnson, Alva; Samlal, Sannandan; Rodrigo, Shelly

2014-12-01

This investigation determined the frequency of resistance of 84 isolates of Salmonella comprising 14 serotypes recovered from layer farms in three Caribbean countries (Trinidad and Tobago, Grenada, and St. Lucia) to eight antimicrobial agents, using the disc diffusion method. Resistance among isolates of Salmonella was related to the country of recovery, type of sample, size of layer farms, and isolate serotype. Overall, all (100.0%) of the isolates exhibited resistance to one or more of seven antimicrobial agents tested, and all were susceptible to chloramphenicol. The resistance detected ranged from 11.9% to sulphamethoxazole-trimethoprim (SXT) to 100.0% to erythromycin. The difference was, however, not statistically significant (P = 0.23). Across countries, for types of samples that yielded Salmonella, significant differences in frequency of resistance were detected only to SXT (P = 0.002) in Trinidad and Tobago and to gentamycin (P = 0.027) in St. Lucia. For the three countries, the frequency of resistance to antimicrobial agents was significantly different for ampicillin (P = 0.001) and SXT (P = 0.032). A total of 83 (98.8%) of the 84 isolates exhibited 39 multidrug resistance patterns. Farm size significantly (P = 0.032) affected the frequency of resistance to kanamycin across the countries. Overall, among the 14 serotypes of Salmonella tested, significant (P < 0.05) differences in frequency of resistance were detected to kanamycin, ampicillin, and SXT. Results suggest that the relatively high frequency of resistance to six of the antimicrobial agents (erythromycin, streptomycin, gentamycin, kanamycin, ampicillin, and tetracycline) tested and the multidrug resistance detected may pose prophylactic and therapeutic concerns for chicken layer farms in the three countries studied.

MRI contrast agent for targeting glioma: interleukin-13 labeled liposome encapsulating gadolinium-DTPA

PubMed Central

Liu, Xiaoli; Madhankumar, Achuthamangalam B.; Miller, Patti A.; Duck, Kari A.; Hafenstein, Susan; Rizk, Elias; Slagle-Webb, Becky; Sheehan, Jonas M.; Connor, James R.; Yang, Qing X.

2016-01-01

Background Detection of glioma with MRI contrast agent is limited to cases in which the blood-brain barrier (BBB) is compromised as contrast agents cannot cross the BBB. Thus, an early-stage infiltrating tumor is not detectable. Interleukin-13 receptor alpha 2 (IL-13Rα2), which has been shown to be overexpressed in glioma, can be used as a target moiety. We hypothesized that liposomes conjugated with IL-13 and encapsulating MRI contrast agent are capable of passing through an intact BBB and producing MRI contrast with greater sensitivity. Methods The targeted MRI contrast agent was created by encapsulating Magnevist (Gd-DTPA) into liposomes conjugated with IL-13 and characterized by particle size distribution, cytotoxicity, and MRI relaxivity. MR image intensity was evaluated in the brain in normal mice post injection of Gd-DTPA and IL-13-liposome-Gd-DTPA one day apart. The specificity for glioma detection by IL-13-liposome-Gd-DTPA was demonstrated in an intracranial glioma mouse model and validated histologically. Results The average size of IL-13-liposome-Gd-DTPA was 137 ± 43 nm with relaxivity of 4.0 ± 0.4 L/mmole-s at 7 Tesla. No significant cytotoxicity was observed with MTS assay and serum chemistry in mice. The MRI signal intensity was enhanced up to 15% post injection of IL-13-liposome-Gd-DTPA in normal brain tissue following a similar time course as that for the pituitary gland outside of the BBB. MRI enhanced by IL-13-liposome-Gd-DTPA detected small tumor masses in addition to those seen with Magnevist-enhanced MRI. Conclusions IL-13-liposome-Gd-DTPA is able to pass through the uncompromised BBB and detect an early stage glioma that cannot be seen with conventional contrast-enhanced MRI. PMID:26519740

Cognitive, cultural, and linguistic sources of a handshape distinction expressing agentivity.

PubMed

Brentari, Diane; Di Renzo, Alessio; Keane, Jonathan; Volterra, Virginia

2015-01-01

In this paper the cognitive, cultural, and linguistic bases for a pattern of conventionalization of two types of iconic handshapes are described. Work on sign languages has shown that handling handshapes (H-HSs: those that represent how objects are handled or manipulated) and object handshapes (O-HSs: those that represent the class, size, or shape of objects) express an agentive/non-agentive semantic distinction in many sign languages. H-HSs are used in agentive event descriptions and O-HSs are used in non-agentive event descriptions. In this work, American Sign Language (ASL) and Italian Sign Language (LIS) productions are compared (adults and children) as well as the corresponding groups of gesturers in each country using "silent gesture." While the gesture groups, in general, did not employ an H-HS/O-HS distinction, all participants (signers and gesturers) used iconic handshapes (H-HSs and O-HSs together) more often in agentive than in no-agent event descriptions; moreover, none of the subjects produced an opposite pattern than the expected one (i.e., H-HSs associated with no-agent descriptions and O-HSs associated with agentive ones). These effects are argued to be grounded in cognition. In addition, some individual gesturers were observed to produce the H-HS/O-HS opposition for agentive and non-agentive event descriptions-that is, more Italian than American adult gesturers. This effect is argued to be grounded in culture. Finally, the agentive/non-agentive handshape opposition is confirmed for signers of ASL and LIS, but previously unreported cross-linguistic differences were also found across both adult and child sign groups. It is, therefore, concluded that cognitive, cultural, and linguistic factors contribute to the conventionalization of this distinction of handshape type. Copyright © 2014 Cognitive Science Society, Inc.

Casein-Coated Fe5C2 Nanoparticles with Superior r2 Relaxivity for Liver-Specific Magnetic Resonance Imaging.

PubMed

Cowger, Taku A; Tang, Wei; Zhen, Zipeng; Hu, Kai; Rink, David E; Todd, Trever J; Wang, Geoffrey D; Zhang, Weizhong; Chen, Hongmin; Xie, Jin

2015-01-01

Iron oxide nanoparticles have been extensively used as T2 contrast agents for liver-specific magnetic resonance imaging (MRI). The applications, however, have been limited by their mediocre magnetism and r2 relaxivity. Recent studies show that Fe5C2 nanoparticles can be prepared by high temperature thermal decomposition. The resulting nanoparticles possess strong and air stable magnetism, suggesting their potential as a novel type of T2 contrast agent. To this end, we improve the synthetic and surface modification methods of Fe5C2 nanoparticles, and investigated the impact of size and coating on their performances for liver MRI. Specifically, we prepared 5, 14, and 22 nm Fe5C2 nanoparticles and engineered their surface by: 1) ligand addition with phospholipids, 2) ligand exchange with zwitterion-dopamine-sulfonate (ZDS), and 3) protein adsorption with casein. It was found that the size and surface coating have varied levels of impact on the particles' hydrodynamic size, viability, uptake by macrophages, and r2 relaxivity. Interestingly, while phospholipid- and ZDS-coated Fe5C2 nanoparticles showed comparable r2, the casein coating led to an r2 enhancement by more than 2 fold. In particular, casein coated 22 nm Fe5C2 nanoparticle show a striking r2 of 973 mM(-1)s(-1), which is one of the highest among all of the T2 contrast agents reported to date. Small animal studies confirmed the advantage of Fe5C2 nanoparticles over iron oxide nanoparticles in inducing hypointensities on T2-weighted MR images, and the particles caused little toxicity to the host. The improvements are important for transforming Fe5C2 nanoparticles into a new class of MRI contrast agents. The observations also shed light on protein-based surface modification as a means to modulate contrast ability of magnetic nanoparticles.

Comparative outcomes for sclerotherapy of head and neck venous vascular malformation between alcohol and bleomycin.

PubMed

Songsaeng, Dittapong; Churojana, Anchalee; Khumthong, Rujimas; Mahiwan, Laksanawadee

2015-04-01

To assess and compare the effectiveness of the two sclerosing agents (95% alcohol and Bleomycin) for the treatment of head and neck venous malformation (VM). The authors retrospectively reviewed our experience in treating VM of the head and neck region using two sclerosing agents, 95% alcohol (November 2001 to June 2008) and bleomycin (July 2008 to July 2010). Patients' demography (age, sex), lesion number location, type (focal/extensive), and characteristic features (cystic/tubular/mixed) were recorded. The treatment outcome was determined by decrease in size of VM in photographs taken at one month and at final clinical follow-up. These were analyzed by two radiologists using visual rating scale (worst or not improved, <50%, 50-75%, >75% of size reduction). One-way Anova test (p < 0.1) was used to show the differences in treatment effectiveness of the two sclerosing agents at short- and long-term intervals. Thirty-three patients, age ranged from 11 to 62 years (mean 25.1 years), with 27 female and six male patients were included in this study. The majority of patients were less than 16 years (17 patients, 51%). The 43 lesions were categorized as 28 VMs were focal (65.1%), 15 (34.9%) diffuse, and30 (69.7%) were of the mixed type. Sixteen lesions were treated with 95% alcohol, 23 lesions with bleomycin, and four lesions with a combination of the two sclerosants. The range of number of procedures was 1 to 16 (mean 3.76 procedures per patient) for alcohol, and 1 to 5 (mean 2.27 procedures per patient) for bleomycin. The cumulative dose ofsclerosant used was 101 ml for alcohol and 32.11 mg for bleomycin. Total follow-up at 1-month and at final was 43/43.(100%) and 35/43 (81.4%) respectively. Mean follow-up interval was 14.7 months. Differences in size reduction after treatment by different sclerosing agents were found. At more than 1-year follow-up, those treated with bleomycin gained graded 3 (> 75%) size reduction more than treated by 95% alcohol. No VM treated with 95% alcohol obtained grade 3 of size reduction at 1-year follow-up. Multiple regression analysis showed VM's favorable character for bleomycin treatment by decreasing mixed, cystic, and tubular Pediatrics had relatively more benefit with bleomycin treatment. Sclerotherapy using either alcohol or bleomycin is an effective treatment for VMs. Different treatment outcomes were significant at long-term with group of VM those treated with bleomycin but not at short-term (p < 0.1).

Polysaccharide based nanogels in the drug delivery system: Application as the carrier of pharmaceutical agents.

PubMed

Debele, Tilahun Ayane; Mekuria, Shewaye Lakew; Tsai, Hsieh-Chih

2016-11-01

Polysaccharide-based nanoparticles have fascinated attention as a vesicle of different pharmaceutical agents due to their unique multi-functional groups in addition to their physicochemical properties, including biocompatibility and biodegradability. The existence of multi-functional groups on the polysaccharide backbone permits facile chemical or biochemical modification to synthesize polysaccharide based nanoparticles with miscellaneous structures. Polysaccharide-based nanogels have high water content, large surface area for multivalent bioconjugation, tunable size, and interior network for the incorporation of different pharmaceutical agents. These unique properties offer great potential for the utilization of polysaccharide-based nanogels in the drug delivery systems. Hence, this review describes chemistry of certain common polysaccharides, several methodologies used to synthesize polysaccharide nanoparticles and primarily focused on the polysaccharide (or polysaccharide derivative) based nanogels as the carrier of pharmaceutical agents. Copyright © 2016 Elsevier B.V. All rights reserved.

Majority-Vote Model with Heterogeneous Agents on Square Lattice

NASA Astrophysics Data System (ADS)

Lima, F. W. S.

2013-11-01

We study a nonequilibrium model with up-down symmetry and a noise parameter q known as majority-vote model (MVM) of [M. J. Oliveira, J. Stat. Phys.66, 273 (1992)] with heterogeneous agents on square lattice (SL). By Monte Carlo (MC) simulations and finite-size scaling relations, the critical exponents β/ν, γ/ν and 1/ν and points qc and U* are obtained. After extensive simulations, we obtain β/ν = 0.35(1), γ/ν = 1.23(8) and 1/ν = 1.05(5). The calculated values of the critical noise parameter and Binder cumulant are qc = 0.1589(4) and U* = 0.604(7). Within the error bars, the exponents obey the relation 2β/ν + γ/ν = 2 and the results presented here demonstrate that the MVM heterogeneous agents belongs to a different universality class than the nonequilibrium MVM with homogeneous agents on SL.

Self-assembled dual-modality contrast agents for non-invasive stem cell tracking via near-infrared fluorescence and magnetic resonance imaging.

PubMed

Liu, Hong; Tan, Yan; Xie, Lisi; Yang, Lei; Zhao, Jing; Bai, Jingxuan; Huang, Ping; Zhan, Wugen; Wan, Qian; Zou, Chao; Han, Yali; Wang, Zhiyong

2016-09-15

Stem cells hold great promise for treating various diseases. However, one of the main drawbacks of stem cell therapy is the lack of non-invasive image-tracking technologies. Although magnetic resonance imaging (MRI) and near-infrared fluorescence (NIRF) imaging have been employed to analyse cellular and subcellular events via the assistance of contrast agents, the sensitivity and temporal resolution of MRI and the spatial resolution of NIRF are still shortcomings. In this study, superparamagnetic iron oxide nanocrystals and IR-780 dyes were co-encapsulated in stearic acid-modified polyethylenimine to form a dual-modality contrast agent with nano-size and positive charge. These resulting agents efficiently labelled stem cells and did not influence the cellular viability and differentiation. Moreover, the labelled cells showed the advantages of dual-modality imaging in vivo. Copyright © 2016 Elsevier Inc. All rights reserved.

For whom will the Bayesian agents vote?

NASA Astrophysics Data System (ADS)

Caticha, Nestor; Cesar, Jonatas; Vicente, Renato

2015-04-01

Within an agent-based model where moral classifications are socially learned, we ask if a population of agents behaves in a way that may be compared with conservative or liberal positions in the real political spectrum. We assume that agents first experience a formative period, in which they adjust their learning style acting as supervised Bayesian adaptive learners. The formative phase is followed by a period of social influence by reinforcement learning. By comparing data generated by the agents with data from a sample of 15000 Moral Foundation questionnaires we found the following. 1. The number of information exchanges in the formative phase correlates positively with statistics identifying liberals in the social influence phase. This is consistent with recent evidence that connects the dopamine receptor D4-7R gene, political orientation and early age social clique size. 2. The learning algorithms that result from the formative phase vary in the way they treat novelty and corroborative information with more conservative-like agents treating it more equally than liberal-like agents. This is consistent with the correlation between political affiliation and the Openness personality trait reported in the literature. 3. Under the increase of a model parameter interpreted as an external pressure, the statistics of liberal agents resemble more those of conservative agents, consistent with reports on the consequences of external threats on measures of conservatism. We also show that in the social influence phase liberal-like agents readapt much faster than conservative-like agents when subjected to changes on the relevant set of moral issues. This suggests a verifiable dynamical criterium for attaching liberal or conservative labels to groups.

Tunable, biodegradable gold nanoparticles as contrast agents for computed tomography and photoacoustic imaging

PubMed Central

Cheheltani, Rabee; Ezzibdeh, Rami M.; Chhour, Peter; Pulaparthi, Kumidini; Kim, Johoon; Jurcova, Martina; Hsu, Jessica C.; Blundell, Cassidy; Litt, Harold I.; Ferrari, Victor A.; Allcock, Harry R.; Sehgal, Chandra M.; Cormode, David P.

2016-01-01

Gold nanoparticles (AuNP) have been proposed for many applications in medicine. Although large AuNP (>5.5 nm) are desirable for their longer blood circulation and accumulation in diseased tissues, small AuNP (<5.5 nm) are required for excretion via the kidneys. We present a novel platform where small, excretable AuNP are encapsulated into biodegradable poly di(carboxylatophenoxy)phosphazene (PCPP) nanospheres. These larger nanoparticles (Au-PCPP) can perform their function as contrast agents, then subsequently break down into harmless byproducts and release the AuNP for swift excretion. Homogeneous Au-PCPP were synthesized using a microfluidic device. The size of the Au-PCPP can be controlled by the amount of polyethylene glycol-polylysine (PEG-PLL) block co-polymer in the formulation. Synthesis of Au-PCPP nanoparticles and encapsulation of AuNP in PCPP were evaluated using transmission electron microscopy and their biocompatibility and biodegradability confirmed in vitro. The Au-PCPP nanoparticles were found to produce strong computed tomography contrast. The UV-Vis absorption peak of Au-PCPP can be tuned into the near infrared region via inclusion of varying amounts of AuNP and controlling the nanoparticle size. In vitro and in vivo experiments demonstrated the potential of Au-PCPP as contrast agents for photoacoustic imaging. Therefore, Au-PCPP nanoparticles have high potency as contrast agents for two imaging modalities, as well as being biocompatible and biodegradable, and thus represent a platform with potential for translation into the clinic. PMID:27322961

Gold Nanoparticles: Promising Agent to Improve the Diagnosis and Therapy of Cancer.

PubMed

Ning, Limin; Zhu, Benwei; Gao, Tao

2017-01-01

Gold nanoparticles have been exploited for nanobiotechnology applications for the last two decades. New insights of the nanomaterials as promising agent for cancer diagnosis and therapy have just started to emerge. Due to the size- and shape-dependent optical, electrical and thermal properties, gold nanoparticles are being developed as diagnostic reagents, drug carriers, contrast agents, photothermal agents and radiosensitisers. This review aims to summarize the latest advances of gold nanoparticles in cancer treatment. We undertook a systematical search for research literatures using a well-framed review question and presented the applications in different fields, including early cancer diagnosis, imaging, radiotherapy, chemotherapy, gene therapy and photothermal therapy, which were fully described, filtered, combined and analyzed in order to provide documented proofs on the applications of gold nanoparticles in current cancer treatments. One hundred and sixty papers were included in the review, the majority of which represent latest researches in the field of gold nanoparticle-based diagnosis and therapy for cancer. Conventional treatment strategies for cancer cannot identify normal and cancer cells. While due to the high surface area to volume ratio and rich surface functionalization chemistry, gold nanoparticle can greatly enhance the targeting with adverse side effects of traditional treatment on normal tissues being avoided. Gold nanoparticles have greatly improved the traditional treatment due to their unique properties. However, their size-dependent toxicity, distribution and clearance need further studies to make them a clinical reality. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Topical agents for oral cancer chemoprevention: A systematic review of the literature.

PubMed

Chau, Lucy; Jabara, Justin T; Lai, Wanda; Svider, Peter F; Warner, Blake M; Lin, Ho-Sheng; Raza, S Naweed; Fribley, Andrew M

2017-04-01

We review the use of topical chemoprevention agents in patients with oral potentially malignant disorders (PMD). A systematic review of studies on topical chemoprevention agents for oral PMD from 1946 to November 2016 was conducted using the MEDLINE database, Embase, and Cochrane Library. Data were extracted and analyzed from selected studies including study type, sample size, demographics, treatment length, response rate, follow-up time, adverse effects, and recurrence. Of 108 studies, twenty-four, representing 679 cases met the inclusion criteria. The clinical lesions evaluated included oral leukoplakia, erythroplakia (OEL), verrucous hyperplasia (OVH), oral lichen planus, larynx squamous cell carcinoma, and oral squamous cell carcinoma (OSCC). The mean complete response rate for topical retinoid therapy was 32%. The mean complete response rate for 1% bleomycin therapy and 0.5% bleomycin was 40.2% and 25%, respectively. The complete response rate of OVH, OEL, and OSCC to photodynamic therapy ranged from 66.7% to 100%. There are a paucity of data examining topical treatment of oral PMDs. However, the use of topical agents among patients with oral lesions may be a viable complement or even alternative to traditional surgery, radiation, or systemic chemotherapy, with the advantage of reducing systemic side effects and sparing important anatomic structures. This study of 679 cases represents the largest pooled sample size to date, and the preliminary studies in this systematic review provide support for further inquiry. Copyright © 2017 Elsevier Ltd. All rights reserved.

[Burns in childhood. Social implications in the eve of the year 2000].

PubMed

Abad, P; Acosta, D; Martínez Ibáñez, V; Lloret, J; Patiño, B; Gubern, L; Carol, J; Boix Ochoa, J

2000-07-01

The thermic wounds in childhood are the third cause of morbility at hospital in our ambiance. The knowledge about incidence, the causal agents more frequent, and the detailed analysis of different variants about the subject are the unique manner to try to establish precautions against. The aim of this project is to analyse the factors and situations associated with thermic wound, through the retrospective study about the patients admitted. During three years, 362 patients were admitted at hospital, between 0 and 14 years old, following the criterion: barge burn size more than 10%, critical location (hands, face, neck), causal agent (electricity, chemical) or social situation. Different facts were analyzed about provenance, place, causal agent, burned part of the body, degree of lesion and the average stay at hospital. There were 59.6% males, and 40.3% females. Children between 1 and 5 years old, represented the largest group of patients, 205 cases. The 66% were from other hospital were they receive the first aid. The 98.7% were burned at home, and the place more frequent was kitchen, 51%. The causal agent was liquid in 65.4%, specially scald with water about 104 cases. The zones more affected were the face (39.2%), and the superior extremities, about 81% second degree superficial or deep. The size was 10 to 20% in 19% of patients, and more than 40% in 0.2% of children. The average stay was 17.47 days at hospital.

Designing Agent Utilities for Coordinated, Scalable and Robust Multi-Agent Systems

NASA Technical Reports Server (NTRS)

Tumer, Kagan

2005-01-01

Coordinating the behavior of a large number of agents to achieve a system level goal poses unique design challenges. In particular, problems of scaling (number of agents in the thousands to tens of thousands), observability (agents have limited sensing capabilities), and robustness (the agents are unreliable) make it impossible to simply apply methods developed for small multi-agent systems composed of reliable agents. To address these problems, we present an approach based on deriving agent goals that are aligned with the overall system goal, and can be computed using information readily available to the agents. Then, each agent uses a simple reinforcement learning algorithm to pursue its own goals. Because of the way in which those goals are derived, there is no need to use difficult to scale external mechanisms to force collaboration or coordination among the agents, or to ensure that agents actively attempt to appropriate the tasks of agents that suffered failures. To present these results in a concrete setting, we focus on the problem of finding the sub-set of a set of imperfect devices that results in the best aggregate device. This is a large distributed agent coordination problem where each agent (e.g., device) needs to determine whether to be part of the aggregate device. Our results show that the approach proposed in this work provides improvements of over an order of magnitude over both traditional search methods and traditional multi-agent methods. Furthermore, the results show that even in extreme cases of agent failures (i.e., half the agents failed midway through the simulation) the system's performance degrades gracefully and still outperforms a failure-free and centralized search algorithm. The results also show that the gains increase as the size of the system (e.g., number of agents) increases. This latter result is particularly encouraging and suggests that this method is ideally suited for domains where the number of agents is currently in the thousands and will reach tens or hundreds of thousands in the near future.

Synthesis of finely divided molybdenum sulfide nanoparticles in propylene carbonate solution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Afanasiev, Pavel, E-mail: pavel.afanasiev@ircelyon.univ-lyon1.fr

2014-05-01

Molybdenum sulfide nanoparticles have been prepared from the reflux solution reaction involving ammonium heptamolybdate and elemental sulfur in propylene carbonate. Addition to the reaction mixture of starch as a natural capping agent leads to lesser agglomeration and smaller size of the particles. Nanoparticles of MoS{sub x} (x≈4) of 10–30 nm size are highly divided and form stable colloidal suspensions in organic solvents. Mo K edge EXAFS of the amorphous materials shows rapid exchange of oxygen to sulfur in the molybdenum coordination sphere during the solution reaction. Thermal treatment of the amorphous sulfides MoS{sub x} under nitrogen or hydrogen flow atmore » 400 °C allows obtaining mesoporous MoS{sub 2} materials with very high pore volume and specific surface area, up to 0.45 cm{sup 3}/g and 190 m{sup 2}/g, respectively. The new materials show good potential for the application as unsupported hydrotreating catalysts. - Graphical abstract: Solution reaction in propylene carbonate allows preparing weakly agglomerated molybdenum sulfide with particle size 20 nm and advantageous catalytic properties. - Highlights: • Solution reaction in propylene carbonate yields MoS{sub x} particles near 20 nm size. • Addition of starch as capping agent reduces particles size and hinder agglomeration. • EXAFS at Mo K edge shows rapid oxygen to sulfur exchange in the solution. • Thermal treatment leads to MoS{sub 2} with very high porosity and surface area.« less

Reversal of Latency as Part of a Cure for HIV-1.

PubMed

Rasmussen, Thomas Aagaard; Tolstrup, Martin; Søgaard, Ole Schmeltz

2016-02-01

Here, the use of pharmacological agents to reverse HIV-1 latency will be explored as a therapeutic strategy towards a cure. However, while clinical trials of latency-reversing agents LRAs) have demonstrated their ability to increase production of latent HIV-1, such interventions have not had an effect on the size of the latent HIV-1 reservoir. Plausible explanations for this include insufficient host immune responses against virus-expressing cells, the presence of escape mutations in archived virus, or an insufficient scale of latency reversal. Importantly, these early studies of LRAs were primarily designed to investigate their ability to perturb the state of HIV-1 latency; using the absence of an impact on the size of the HIV-1 reservoir to discard their potential inclusion in curative strategies would be erroneous and premature. Copyright © 2015 Elsevier Ltd. All rights reserved.

Sunlight-assisted synthesis of colloidal silver nanoparticles using chitosan as reducing agent

NASA Astrophysics Data System (ADS)

Susilowati, E.; Maryani; Ashadi

2018-04-01

The present study we explore an environmentally friendly colloidal silver nanoparticles preparation using chitosan as reducing agent and stabilizer. It develops a new strategy on preparation of silver nanoparticles through the gel phase using sodium hydroxide (NaOH) as accelerator reagent. Sunlight irradiation was employed to assisted reducing process of silver ions to silver nanoparticles. Localized surface plasmon resonance (LSPR) phenomenon of silver nanoparticles was investigated using UV-Vis spectrophotometer. The shape and size of silver particles were analyzed using TEM. The formation of silver nanoparticles was confirmed by the appearance of LSPR absorption peak at 396.0–412.0 nm. The absorption peak of LSPR were affected by NaOH amount, time of sulight irradiation and concentration of AgNO3. The produced silver nanoparticles were spherical with dominant size range of 5 to 8 nm as shown by TEM images. All colloidals were stable without any aggregation for 30 days after preparation.

Biodistribution of amino-functionalized diamond nanoparticles. In vivo studies based on 18F radionuclide emission.

PubMed

Rojas, Santiago; Gispert, Juan D; Martín, Roberto; Abad, Sergio; Menchón, Cristina; Pareto, Deborah; Víctor, Víctor M; Alvaro, Mercedes; García, Hermenegildo; Herance, J Raúl

2011-07-26

Nanoparticles have been proposed for several biomedical applications; however, in vivo biodistribution studies to confirm their potential are scarce. Nanodiamonds are carbon nanoparticles that have been recently proposed as a promising biomaterial. In this study, we labeled nanodiamonds with (18)F to study their in vivo biodistribution by positron emission tomography. Moreover, the impact on the biodistribution of their kinetic particle size and of the surfactant agents has been evaluated. Radiolabeled diamond nanoparticles accumulated mainly in the lung, spleen, and liver and were excreted into the urinary tract. The addition of surfactant agents did not lead to significant changes in this pattern, with the exception of a slight reduction in the urinary excretion rate. On the other hand, after filtration of the radiolabeled diamond nanoparticles to remove those with a larger kinetic size, the uptake in the lung and spleen was completely inhibited and significantly reduced in the liver.

Morphologies, Processing and Properties of Ceramic Foams from Pre-Ceramic Foams from Pre-Ceramic Polymer Routes

NASA Technical Reports Server (NTRS)

Stackpoole, Mairead; Simoes, Conan R.; Venkatapathy, Ethiras (Technical Monitor)

2002-01-01

The current research is focused on processing ceramic foams that have potential as a thermal protection material. Ceramic foams with different architectures were formed from the pyrolysis of pre-ceramic polymers at 1200 C in different atmospheres. In some systems a sacrificial polyurethane was used as the blowing agent. We have also processed foams using sacrificial fillers to introduce controlled cell sizes. Each sacrificial filler or blowing agent leads to a unique morphology. The effect of different fillers on foam morphologies will be presented. The presentation will also focus on characterization of these foams in terms of mechanical and thermal properties. Foams processed using these approaches having bulk densities ranging from 0.15 to 0.9 g per cubic centimeter and a cell sizes from 5 to 500 micrometers. Compression strengths ranged from 2 to 7 MPa for these materials.

Propellant development for the Advanced Solid Rocket Motor

NASA Technical Reports Server (NTRS)

Landers, L. C.; Stanley, C. B.; Ricks, D. W.

1991-01-01

The properties of a propellant developed for the NASA Advanced Solid Rocket Motor (ASRM) are described in terms of its composition, performance, and compliance to NASA specifications. The class 1.3 HTPB/AP/A1 propellant employs an ester plasticizer and the content of ballistic solids is set at 88 percent. Ammonia evolution is prevented by the utilization of a neutral bonding agent which allows continuous mixing. The propellant also comprises a bimodal AP blend with one ground fraction, ground AP of at least 20 microns, and ferric oxide to control the burning rate. The propellant's characteristics are discussed in terms of tradeoffs in AP particle size and the types of Al powder, bonding agent, and HTPB polymer. The size and shape of the ballistic solids affect the processability, ballistic properties, and structural properties of the propellant. The revised baseline composition is based on maximizing the robustness of in-process viscosity, structural integrity, and burning-rate tailoring range.

A RAND Analysis Tool for Intelligence, Surveillance, and Reconnaissance: The Collections Operations Model

DTIC Science & Technology

2008-01-01

appropriate; scan cycle, emission interval, or emission probability; frequency bands; relative angular size of 2 Carl Rhodes, Jeff Hagen, and Mark...choices based on its own perceptions. An agent has autonomy. 2 In this report, “behaviors” are individual scripts , programs, instructions, or decision...relative angular size of main and side lobes (for directional signals); and the effective radiated power of each radiative lobe. With these parameters and

Microbubble Sizing and Shell Characterization Using Flow Cytometry

PubMed Central

Tu, Juan; Swalwell, Jarred E.; Giraud, David; Cui, Weicheng; Chen, Weizhong; Matula, Thomas J.

2015-01-01

Experiments were performed to size, count, and obtain shell parameters for individual ultrasound contrast microbubbles using a modified flow cytometer. Light scattering was modeled using Mie theory, and applied to calibration beads to calibrate the system. The size distribution and population were measured directly from the flow cytometer. The shell parameters (shear modulus and shear viscosity) were quantified at different acoustic pressures (from 95 to 333 kPa) by fitting microbubble response data to a bubble dynamics model. The size distribution of the contrast agent microbubbles is consistent with manufacturer specifications. The shell shear viscosity increases with increasing equilibrium microbubble size, and decreases with increasing shear rate. The observed trends are independent of driving pressure amplitude. The shell elasticity does not vary with microbubble size. The results suggest that a modified flow cytometer can be an effective tool to characterize the physical properties of microbubbles, including size distribution, population, and shell parameters. PMID:21622051

One-step, low-temperature fabrication of CdS quantum dots by watermelon rind: a green approach

PubMed Central

Lakshmipathy, Rajasekhar; Sarada, Nallani Chakravarthula; Chidambaram, K; Pasha, Sk Khadeer

2015-01-01

We investigated the one-step synthesis of CdS nanoparticles via green synthesis that used aqueous extract of watermelon rind as a capping and stabilizing agent. Preliminary phytochemical analysis depicted the presence of carbohydrates which can act as capping and stabilizing agents. Synthesized CdS nanoparticles were characterized using UV-visible, Fourier transform infrared spectroscopy, X-ray diffraction, EDX, dynamic light scattering, transmission electron microscopy, and atomic force microscopy techniques. The CdS nanoparticles were found to be size- and shape-controlled and were stable even after 3 months of synthesis. The results suggest that watermelon rind, an agro-waste, can be used for synthesis of CdS nanoparticles without any addition of stabilizing and capping agents. PMID:26491319

Phase Transition of Poly(acrylic acid-co-N-isopropylacrylamide) Core-shell Nanogels

NASA Astrophysics Data System (ADS)

Liu, Xiao-bing; Zhou, Jian-feng; Ye, Xiao-dong

2012-08-01

A series of poly(acrylic acid) macromolecular chain transfer agents with different molecular weights were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization and characterized by 1H NMR and gel permeation chromatography. Multiresponsive core-shell nanogels were prepared by dispersion polymerization of N-isopropylacrylamide in water using these poly(potassium acrylate) macro-RAFT agents as the electrosteric stabilizer. The size of the nanogels decreases with the amount of the macro-RAFT agent, indicating that the surface area occupied by per polyelectrolyte group is a critical parameter for stabilizing the nanogels. The volume phase transition and the zeta potentials of the nanogels in aqueous solutions were studied by dynamic light scattering and zetasizer analyzer, respectively.

Imaging efficiency of an X-ray contrast agent-incorporated polymeric microparticle.

PubMed

Ahn, Sungsook; Jung, Sung Yong; Lee, Jin Pyung; Lee, Sang Joon

2011-01-01

Biocompatible polymeric encapsulants have been widely used as a delivery vehicle for a variety of drugs and imaging agents. In this study, X-ray contrast agent (iopamidol) is encapsulated into a polymeric microparticle (polyvinyl alcohol) as a particulate flow tracer in synchrotron X-ray imaging system. The physical properties of the designed microparticles are investigated and correlated with enhancement in the imaging efficiency by experimental observation and theoretical interpretation. The X-ray absorption ability of the designed microparticle is assessed by Beer-Lambert-Bouguer law. Particle size, either in dried state or in solvent, primarily dominates the X-ray absorption ability under the given condition, thus affecting imaging efficiency of the designed X-ray contrast flow tracers. Copyright © 2011 John Wiley & Sons, Ltd.

Non-thermal transitions in a model inspired by moral decisions

NASA Astrophysics Data System (ADS)

Alamino, Roberto C.

2016-08-01

This work introduces a model in which agents of a network act upon one another according to three different kinds of moral decisions. These decisions are based on an increasing level of sophistication in the empathy capacity of the agent, a hierarchy which we name Piaget’s ladder. The decision strategy of the agents is non-rational, in the sense they are arbitrarily fixed, and the model presents quenched disorder given by the distribution of its defining parameters. An analytical solution for this model is obtained in the large system limit as well as a leading order correction for finite-size systems which shows that typical realisations of the model develop a phase structure with both continuous and discontinuous non-thermal transitions.

Single-particle aerosol mass spectrometry for the detection and identification of chemical warfare agent simulants.

PubMed

Martin, Audrey N; Farquar, George R; Frank, Matthias; Gard, Eric E; Fergenson, David P

2007-08-15

Single-particle aerosol mass spectrometry (SPAMS) was used for the real-time detection of liquid nerve agent simulants. A total of 1000 dual-polarity time-of-flight mass spectra were obtained for micrometer-sized single particles each of dimethyl methyl phosphonate, diethyl ethyl phosphonate, diethyl phosphoramidate, and diethyl phthalate using laser fluences between 0.58 and 7.83 nJ/microm2, and mass spectral variation with laser fluence was studied. The mass spectra obtained allowed identification of single particles of the chemical warfare agent (CWA) simulants at each laser fluence used although lower laser fluences allowed more facile identification. SPAMS is presented as a promising real-time detection system for the presence of CWAs.

Halloysite clay nanotubes for controlled release of protective agents.

PubMed

Abdullayev, Elshad; Lvov, Yuri

2011-11-01

Halloysite is a naturally occurring clay mineral with submicron sized hollow cylindrical morphology. Halloysite morphology, structure and properties were characterized by using SEM, TEM, XRD, FT-IR spectroscopy, surface electrokinetic (zeta) potential and nitrogen adsorption isotherms. Comparison of the halloysite structure with imogolite was also provided. Halloysite toxicological studies revealed that it is environmentally friendly and biocompatible material. Due to its unique tubular shape and availability in thousands of tons halloysite has potential to be applied as nanocontainers for encapsulation of chemically and biologically active agents such as medicines, pharmaceuticals, antiseptics, corrosion inhibitors, antifouling agents, and doped with them plastics producing smart polymeric nanocomposites with improved mechanical strength. Finally possibility to synthesize metal nanorods within the halloysite lumen was demonstrated.

DO HERBAL AGENTS HAVE A PLACE IN THE TREATMENT OF SLEEP PROBLEMS IN LONG-TERM CARE?

PubMed Central

Shimazaki, Mark; Martin, Jennifer L.

2007-01-01

Sleep disruption is common in the long-term care setting. This paper discusses the available literature on two herbal approaches to sleep problems in long-term care. The largest body of evidence exists for the use of the dietary/herbal supplements valerian and melatonin. While these agents appear to have a modest positive effect on sleep quality among older adults, most studies were small in size and included only subjective assessments of sleep quality. In addition, it is unclear whether these agents pose risks to long-term care residents due to potential drug interactions. Additional research is needed prior to making conclusive recommendations about the use of these interventions for sleep in the long-term care setting. PMID:17498609

SPARK: A Framework for Multi-Scale Agent-Based Biomedical Modeling.

PubMed

Solovyev, Alexey; Mikheev, Maxim; Zhou, Leming; Dutta-Moscato, Joyeeta; Ziraldo, Cordelia; An, Gary; Vodovotz, Yoram; Mi, Qi

2010-01-01

Multi-scale modeling of complex biological systems remains a central challenge in the systems biology community. A method of dynamic knowledge representation known as agent-based modeling enables the study of higher level behavior emerging from discrete events performed by individual components. With the advancement of computer technology, agent-based modeling has emerged as an innovative technique to model the complexities of systems biology. In this work, the authors describe SPARK (Simple Platform for Agent-based Representation of Knowledge), a framework for agent-based modeling specifically designed for systems-level biomedical model development. SPARK is a stand-alone application written in Java. It provides a user-friendly interface, and a simple programming language for developing Agent-Based Models (ABMs). SPARK has the following features specialized for modeling biomedical systems: 1) continuous space that can simulate real physical space; 2) flexible agent size and shape that can represent the relative proportions of various cell types; 3) multiple spaces that can concurrently simulate and visualize multiple scales in biomedical models; 4) a convenient graphical user interface. Existing ABMs of diabetic foot ulcers and acute inflammation were implemented in SPARK. Models of identical complexity were run in both NetLogo and SPARK; the SPARK-based models ran two to three times faster.

Minimal agent based model for financial markets I. Origin and self-organization of stylized facts

NASA Astrophysics Data System (ADS)

Alfi, V.; Cristelli, M.; Pietronero, L.; Zaccaria, A.

2009-02-01

We introduce a minimal agent based model for financial markets to understand the nature and self-organization of the stylized facts. The model is minimal in the sense that we try to identify the essential ingredients to reproduce the most important deviations of price time series from a random walk behavior. We focus on four essential ingredients: fundamentalist agents which tend to stabilize the market; chartist agents which induce destabilization; analysis of price behavior for the two strategies; herding behavior which governs the possibility of changing strategy. Bubbles and crashes correspond to situations dominated by chartists, while fundamentalists provide a long time stability (on average). The stylized facts are shown to correspond to an intermittent behavior which occurs only for a finite value of the number of agents N. Therefore they correspond to finite size effects which, however, can occur at different time scales. We propose a new mechanism for the self-organization of this state which is linked to the existence of a threshold for the agents to be active or not active. The feedback between price fluctuations and number of active agents represents a crucial element for this state of self-organized intermittency. The model can be easily generalized to consider more realistic variants.

Development of a microinstillation model of inhalation exposure to assess lung injury following exposure to toxic chemicals and nerve agents in Guinea pigs.

PubMed

Nambiar, Madhusoodana P; Wright, Benjamin S; Rezk, Peter E; Smith, Kelvin B; Gordon, Richard K; Moran, Theodore S; Richards, Shannon M; Sciuto, Alfred M

2006-01-01

Respiratory disturbances due to chemical warfare nerve agents (CWNAs) are the starting point of mass casualty and the primary cause of death by these weapons of terror and mass destruction. However, very few studies have been implemented to assess respiratory toxicity and exacerbation induced by CWNAs, especially methylphosphonothioic acid S-(2-(bis(1-methylethyl)amino)ethyl)O-ethyl ester (VX). In this study, we developed a microinstillation technique of inhalation exposure to assess lung injury following exposure to CWNAs and toxic chemicals. Guinea pigs were gently intubated by placing a microcatheter into the trachea 1.5 to 2.0 cm centrally above the bifurcation. This location is crucial to deliver aerosolized agents uniformly to the lung's lobes. The placement of the tube is calculated by measuring the distance from the upper front teeth to the tracheal bifurcation, which is typically 8.5 cm for guinea pigs of equivalent size and a weight range of 250 g to 300 g. The catheter is capable of withstanding 100 psi pressure; the terminus has five peripheral holes to pump air that aerosolizes the nerve agent that is delivered in the central hole. The microcatheter is regulated by a central control system to deliver the aerosolized agent in a volume lower than the tidal volume of the guinea pigs. The average particle size of the nerve agent delivered was 1.48 +/- 0.07 micrometer. The microinstillation technology has been validated by exposing the animals to Coomassie brilliant blue, which showed a uniform distribution of the dye in different lung lobes. In addition, the concentration of the dye in the lungs correlated with the dose/time of exposure. Furthermore, histopathological analysis confirmed the absence of barotraumas following micoinstillation. This novel technique delivers the agent safely, requires less amount of agent, avoids exposure to skin, pelt, and eye, and circumvents the concern of deposition of the particles in the nasal and palette due to the switching of breathing from nasal to oronasal in whole-body dynamic chamber or nose only exposure. Currently, we are using this inhalation exposure technique to investigate lung injuries and respiratory disturbances following direct exposure to VX.

Size-controlled synthesis of Pd nanocrystals using a specific multifunctional peptide

NASA Astrophysics Data System (ADS)

Chiu, Chin-Yi; Li, Yujing; Huang, Yu

2010-06-01

Here we report a peptide-mediated synthesis of Pd NCs in aqueous solution with controllable size in the sub-10 nanometre regime. The specific multifunctional peptide Q7 selected using the phage display technique can bind to the Pd NC surface and act as a stabilizer to mediate Pd crystal nucleation and growth. At the nucleation stage, Q7 bound to and helped stabilize the different-sized small Pd NC nuclei achieved using different concentrations of the external reducing agent, NaBH4. At the growth stage, Q7 played the dual role of binding to and reducing the precursor onto the existing nuclei, which led to the further controllable growth of the Pd NCs. By using the variable sizes of nuclei as seeds, and by introducing different amounts of precursors Pd NCs with tunable sizes from 2.6 to 6.6 nm were achieved with good size distribution.Here we report a peptide-mediated synthesis of Pd NCs in aqueous solution with controllable size in the sub-10 nanometre regime. The specific multifunctional peptide Q7 selected using the phage display technique can bind to the Pd NC surface and act as a stabilizer to mediate Pd crystal nucleation and growth. At the nucleation stage, Q7 bound to and helped stabilize the different-sized small Pd NC nuclei achieved using different concentrations of the external reducing agent, NaBH4. At the growth stage, Q7 played the dual role of binding to and reducing the precursor onto the existing nuclei, which led to the further controllable growth of the Pd NCs. By using the variable sizes of nuclei as seeds, and by introducing different amounts of precursors Pd NCs with tunable sizes from 2.6 to 6.6 nm were achieved with good size distribution. Electronic Supplementary Information (ESI) available. Experimental details for peptide selection, peptide synthesis and Pd NCs synthesis; Q7 peptide sequence molecular structure and characterization; TEM images of Pd NCs. See DOI: 10.1039/c0nr00194e/

Spray-drying nanocapsules in presence of colloidal silica as drying auxiliary agent: formulation and process variables optimization using experimental designs.

PubMed

Tewa-Tagne, Patrice; Degobert, Ghania; Briançon, Stéphanie; Bordes, Claire; Gauvrit, Jean-Yves; Lanteri, Pierre; Fessi, Hatem

2007-04-01

Spray-drying process was used for the development of dried polymeric nanocapsules. The purpose of this research was to investigate the effects of formulation and process variables on the resulting powder characteristics in order to optimize them. Experimental designs were used in order to estimate the influence of formulation parameters (nanocapsules and silica concentrations) and process variables (inlet temperature, spray-flow air, feed flow rate and drying air flow rate) on spray-dried nanocapsules when using silica as drying auxiliary agent. The interactions among the formulation parameters and process variables were also studied. Responses analyzed for computing these effects and interactions were outlet temperature, moisture content, operation yield, particles size, and particulate density. Additional qualitative responses (particles morphology, powder behavior) were also considered. Nanocapsules and silica concentrations were the main factors influencing the yield, particulate density and particle size. In addition, they were concerned for the only significant interactions occurring among two different variables. None of the studied variables had major effect on the moisture content while the interaction between nanocapsules and silica in the feed was of first interest and determinant for both the qualitative and quantitative responses. The particles morphology depended on the feed formulation but was unaffected by the process conditions. This study demonstrated that drying nanocapsules using silica as auxiliary agent by spray drying process enables the obtaining of dried micronic particle size. The optimization of the process and the formulation variables resulted in a considerable improvement of product yield while minimizing the moisture content.

The effects of anesthetic agents on pupillary function during general anesthesia using the automated infrared quantitative pupillometer.

PubMed

Shirozu, Kazuhiro; Setoguchi, Hidekazu; Tokuda, Kentaro; Karashima, Yuji; Ikeda, Mizuko; Kubo, Makoto; Nakamura, Katsuya; Hoka, Sumio

2017-04-01

Pupil reactivity can be used to evaluate central nervous system function and can be measured using a quantitative pupillometer. However, whether anesthetic agents affect the accuracy of the technique remains unclear. We examined the effects of anesthetic agents on pupillary reactivity. Thirty-five patients scheduled for breast or thyroid surgery were enrolled in the study. Patients were divided into four groups based on the technique used to maintain anesthesia: a sevoflurane-remifentanil (SEV/REM) group, a sevoflurane (SEV) group, a desflurane-remifentanil (DES/REM) group, and a propofol-remifentanil (PRO/REM) group. We measured maximum resting pupil size (MAX), reduction pupil size ratio (%CH), latency duration (LAT) and neurological pupil index (NPi). A marked reduction in MAX and %CH compared with baseline was observed in all groups, but LAT was unchanged during surgery. NPi reduced within the first hour of surgery in the SEV/REM, SEV, and DES/REM groups, but was not significantly different in the PRO/REM group. Compared with the PRO/REM group, mean %CH and NPi in patients anesthetized with SEV/REM, SEV or DES/REM were markedly lower at 1 h after surgery had commenced. There was no correlation between NPi and bispectral index. Fentanyl given alone decreased pupil size and %CH in light reflex, but did not change the NPi. NPi was decreased by inhalational anesthesia not but intravenous anesthesia. The difference in pupil reactivity between inhalational anesthetic and propofol may indicate differences in the alteration of midbrain reflexs in patients under inhalational or intravenous anesthesia.

Multi-A Graph Patrolling and Partitioning

NASA Astrophysics Data System (ADS)

Elor, Y.; Bruckstein, A. M.

2012-12-01

We introduce a novel multi agent patrolling algorithm inspired by the behavior of gas filled balloons. Very low capability ant-like agents are considered with the task of patrolling an unknown area modeled as a graph. While executing the proposed algorithm, the agents dynamically partition the graph between them using simple local interactions, every agent assuming the responsibility for patrolling his subgraph. Balanced graph partition is an emergent behavior due to the local interactions between the agents in the swarm. Extensive simulations on various graphs (environments) showed that the average time to reach a balanced partition is linear with the graph size. The simulations yielded a convincing argument for conjecturing that if the graph being patrolled contains a balanced partition, the agents will find it. However, we could not prove this. Nevertheless, we have proved that if a balanced partition is reached, the maximum time lag between two successive visits to any vertex using the proposed strategy is at most twice the optimal so the patrol quality is at least half the optimal. In case of weighted graphs the patrol quality is at least (1)/(2){lmin}/{lmax} of the optimal where lmax (lmin) is the longest (shortest) edge in the graph.

Examination of water spray airborne coal dust capture with three wetting agents

PubMed Central

Organiscak, J.A.

2015-01-01

Water spray applications are one of the principal means of controlling airborne respirable dust in coal mines. Since many coals are hydrophobic and not easily wetted by water, wetting agents can be added to the spray water in an effort to improve coal wetting and assist with dust capture. In order to study wetting agent effects on coal dust capture, laboratory experiments were conducted with three wetting agents used by the coal industry on -325 mesh sized Pocahontas No. 3 coal dust. Significant differences in coal dust sink times were observed among the three wetting agents at water mixture concentrations of 0.05%, 0.1% and 0.2%. The best wetting agent as identified by the coal dust sink test was only tested at the lowest 0.05% water mixture concentration and was found to have a negligible effect on spray airborne dust capture. Water spray airborne dust capture results for all three wetting agents tested at a 0.2% water mixture concentration showed that all three wetting agents exhibit similar but small improvements in dust capture efficiency as compared with water. These results indicate that the coal dust sink test may not be a good predictor for the capture of airborne dust. Additional research is needed to examine if the coal dust sink test is a better predictor of wetting agent dust suppression effects during cutting, loading, conveying and dumping of coal products by comparison to airborne dust capture from sprays. PMID:26251565

Phase transition of social learning collectives and the echo chamber.

PubMed

Mori, Shintaro; Nakayama, Kazuaki; Hisakado, Masato

2016-11-01

We study a simple model for social learning agents in a restless multiarmed bandit. There are N agents, and the bandit has M good arms that change to bad with the probability q_{c}/N. If the agents do not know a good arm, they look for it by a random search (with the success probability q_{I}) or copy the information of other agents' good arms (with the success probability q_{O}) with probabilities 1-p or p, respectively. The distribution of the agents in M good arms obeys the Yule distribution with the power-law exponent 1+γ in the limit N,M→∞, and γ=1+(1-p)q_{I}/pq_{O}. The system shows a phase transition at p_{c}=q_{I}/q_{I}+q_{o}. For pp_{c}), the variance of N_{1} per agent is finite (diverges as ∝N^{2-γ} with N). There is a threshold value N_{s} for the system size that scales as lnN_{s}∝1/(γ-1). The expected value of the number of the agents with a good arm N_{1} increases with p for N>N_{s}. For p>p_{c} and N

Modeling of a production system using the multi-agent approach

NASA Astrophysics Data System (ADS)

Gwiazda, A.; Sękala, A.; Banaś, W.

2017-08-01

The method that allows for the analysis of complex systems is a multi-agent simulation. The multi-agent simulation (Agent-based modeling and simulation - ABMS) is modeling of complex systems consisting of independent agents. In the case of the model of the production system agents may be manufactured pieces set apart from other types of agents like machine tools, conveyors or replacements stands. Agents are magazines and buffers. More generally speaking, the agents in the model can be single individuals, but you can also be defined as agents of collective entities. They are allowed hierarchical structures. It means that a single agent could belong to a certain class. Depending on the needs of the agent may also be a natural or physical resource. From a technical point of view, the agent is a bundle of data and rules describing its behavior in different situations. Agents can be autonomous or non-autonomous in making the decision about the types of classes of agents, class sizes and types of connections between elements of the system. Multi-agent modeling is a very flexible technique for modeling and model creating in the convention that could be adapted to any research problem analyzed from different points of views. One of the major problems associated with the organization of production is the spatial organization of the production process. Secondly, it is important to include the optimal scheduling. For this purpose use can approach multi-purposeful. In this regard, the model of the production process will refer to the design and scheduling of production space for four different elements. The program system was developed in the environment NetLogo. It was also used elements of artificial intelligence. The main agent represents the manufactured pieces that, according to previously assumed rules, generate the technological route and allow preprint the schedule of that line. Machine lines, reorientation stands, conveyors and transport devices also represent the other type of agent that are utilized in the described simulation. The article presents the idea of an integrated program approach and shows the resulting production layout as a virtual model. This model was developed in the NetLogo multi-agent program environment.

Preferential cytotoxicity of ZnO nanoparticle towards cervical cancer cells induced by ROS-mediated apoptosis and cell cycle arrest for cancer therapy

NASA Astrophysics Data System (ADS)

Sirelkhatim, Amna; Mahmud, Shahrom; Seeni, Azman; Kaus, Noor Haida Mohd

2016-08-01

The present study aimed to synthesize multifunctional ZnO-NP samples, namely ZnO-20, ZnO-40, and ZnO-80 nm, using different approaches, to be used as efficient anticancer agents. Systematic characterizations revealed their particle sizes and demonstrated nanostructures of nanorods (ZnO-80 nm) and nanogranules (ZnO-20 and ZnO-40 nm). They exhibited significant ( p < 0.05) toxicity to HeLa cancer cells. HeLa cell viabilities at 1 mM dose reduced to 37, 32, 15 %, by ZnO-80, ZnO-40, and ZnO-20 nm, respectively, at 48 h. However, the same dose exerted different effects of 79.6, 76, and 75 % on L929 normal cells at 48 h. Measurement of reactive oxygen species (ROS) showed a considerable ROS yields on HeLa cells by all samples with a pronounced percentage (50 %) displayed by ZnO-20 nm. Moreover, ROS-mediated apoptosis induction and blocked cell cycle progression in the S, G2/M, and G0/G1 phases significantly ( p < 0.05). Apoptosis induction was further confirmed by DNA fragmentation and Hoechst-PI costained images viewed under fluorescence microscope. Additionally, morphological changes of HeLa cells visualized under light microscope showed assortment of cell death involved shrinkage, vacuolization and apoptotic bodies' formation. Most importantly, results exposed the impact of size and morphology of ZnO samples on their toxicity to Hela cells mediated mainly by ROS production. ZnO-20 nm in disk form with its nanogranule shape and smallest particle size was the most toxic sample, followed by ZnO-40 nm and then ZnO-80 nm. An additional proposed mechanism contributed in the cell death herein was ZnO decomposition producing zinc ions (Zn2+) into the acidic cancer microenvironment due to the smaller sizes of ZnO-NPs. This mechanism has been adopted in the literatures as a size-dependent phenomenon. The emerged findings were suggested to provide new platforms in the development of therapeutics as selective agents to the fatal cervical cancer, and to benefit from the synergistic influence of size and nanostructure when designing anticancer agents.

Development of PEGylated KMnF3 nanoparticles as a T1-weighted contrast agent: chemical synthesis, in vivo brain MR imaging, and accounting for high relaxivity

NASA Astrophysics Data System (ADS)

Liu, Zhi-Jun; Song, Xiao-Xia; Tang, Qun

2013-05-01

Magnetic nanoparticles consisting of manganese-based T1-weighted contrast agents have rapidly achieved clinical application, however low proton relaxivity impedes further development. In this report, by analyzing nanoparticles' surface oxidation states we propose the possible reason for the low r1 relaxivity of common MnO nanoparticles and develop PEGylated fluoroperovskite KMnF3 nanoparticles as new T1-weighted contrast agents, which exhibit the highest longitudinal relaxivity (r1 = 23.15 mM-1 s-1) among all the reported manganese-based T1-weighted contrast agents. We, for the first time, illustrate a typical example showing that the surface oxidation states of metal ions exposed on the nanoparticles' surfaces are able to influence not only the optical, magnetic, electronic or catalytic properties but also water proton longitudinal relaxivity when applied as an MRI contrast agent. Cytotoxicity tests demonstrate that the PEGylated KMnF3 nanoparticles are free from toxicity. Further in vivo MRI experiments distinctively depict fine anatomical features in brain imaging at a low dose of 5 mg of Mn per kg and possible removal from the kidneys due to their small size and biocompatibility.Magnetic nanoparticles consisting of manganese-based T1-weighted contrast agents have rapidly achieved clinical application, however low proton relaxivity impedes further development. In this report, by analyzing nanoparticles' surface oxidation states we propose the possible reason for the low r1 relaxivity of common MnO nanoparticles and develop PEGylated fluoroperovskite KMnF3 nanoparticles as new T1-weighted contrast agents, which exhibit the highest longitudinal relaxivity (r1 = 23.15 mM-1 s-1) among all the reported manganese-based T1-weighted contrast agents. We, for the first time, illustrate a typical example showing that the surface oxidation states of metal ions exposed on the nanoparticles' surfaces are able to influence not only the optical, magnetic, electronic or catalytic properties but also water proton longitudinal relaxivity when applied as an MRI contrast agent. Cytotoxicity tests demonstrate that the PEGylated KMnF3 nanoparticles are free from toxicity. Further in vivo MRI experiments distinctively depict fine anatomical features in brain imaging at a low dose of 5 mg of Mn per kg and possible removal from the kidneys due to their small size and biocompatibility. Electronic supplementary information (ESI) available: Experimental procedure for two types of MnO nanoparticles, T1-weighted mapping. See DOI: 10.1039/c3nr00721a

Effect of both protective and reducing agents in the synthesis of multicolor silver nanoparticles

NASA Astrophysics Data System (ADS)

Rivero, Pedro Jose; Goicoechea, Javier; Urrutia, Aitor; Arregui, Francisco Javier

2013-02-01

In this paper, the influence of variable molar ratios between reducing and loading agents (1:100, 1:50, 1:20, 1:10, 1:5, 1:2, 1:1, 2:1) and between protective and loading agents (0.3:1, 0.75:1, 1.5:1, 3:1, 7.5:1, 30:1, 75:1) in the synthesis of silver nanoparticles by chemical reduction has been evaluated to obtain multicolor nanoparticles with a high stability in time. The protective agent poly(acrylic acid, sodium salt) (PAA) and reducing agent dimethylaminoborane (DMAB) play a key role in the formation of the resultant color. Evolution of the optical absorption bands of the silver nanoparticles as a function of PAA and DMAB molar ratios made it possible to confirm the presence of silver nanoparticles or clusters with a specific shape. The results reveal that a wide range of colors (violet, blue, green, brown, yellow, red, orange), sizes (from nanometer to micrometer), and shapes (cubic, rod, triangle, hexagonal, spherical) can be perfectly tuned by means of a fine control of the PAA and DMAB molar concentrations.

Surface impact on nanoparticle-based magnetic resonance imaging contrast agents

PubMed Central

Zhang, Weizhong; Liu, Lin; Chen, Hongmin; Hu, Kai; Delahunty, Ian; Gao, Shi; Xie, Jin

2018-01-01

Magnetic resonance imaging (MRI) is one of the most widely used diagnostic tools in the clinic. To improve imaging quality, MRI contrast agents, which can modulate local T1 and T2 relaxation times, are often injected prior to or during MRI scans. However, clinically used contrast agents, including Gd3+-based chelates and iron oxide nanoparticles (IONPs), afford mediocre contrast abilities. To address this issue, there has been extensive research on developing alternative MRI contrast agents with superior r1 and r2 relaxivities. These efforts are facilitated by the fast progress in nanotechnology, which allows for preparation of magnetic nanoparticles (NPs) with varied size, shape, crystallinity, and composition. Studies suggest that surface coatings can also largely affect T1 and T2 relaxations and can be tailored in favor of a high r1 or r2. However, the surface impact of NPs has been less emphasized. Herein, we review recent progress on developing NP-based T1 and T2 contrast agents, with a focus on the surface impact. PMID:29721097

Optimization of high quality Cu2ZnSnS4 thin film by low cost and environment friendly sol-gel technique for thin film solar cells applications

NASA Astrophysics Data System (ADS)

Chaudhari, J. J.; Joshi, U. S.

2018-05-01

In this study kesterite Cu2ZnSnS4 (CZTS) thin films suitable for absorber layer in thin film solar cells (TFSCs) were successfully fabricated on glass substrate by sol-gel method. The effects of complexing agent on formation of CZTS thin films have been investigated. X-ray diffraction (XRD) analysis confirms formation of polycrystalline CZTS thin films with single phase kesterite structure. XRD and Raman spectroscopy analysis of CZTS thin films with optimized concentration of complexing agent confirmed formation of kesterite phase in CZTS thin films. The direct optical band gap energy of CZTS thin films is found to decrease from 1.82 to 1.50 eV with increase of concentration of complexing agent triethanolamine. Morphological analysis of CZTS thin films shows smooth, uniform and densely packed CZTS grains and increase in the grain size with increase of concentration of complexing agent. Hall measurements revealed that concentration of charge carrier increases and resistivity decreases in CZTS thin films as amount of complexing agent increases.

Opinion formation of free speech on the directed social network

NASA Astrophysics Data System (ADS)

Su, Jiongming; Ma, Hongxu; Liu, Baohong; Li, Qi

2014-12-01

A dynamical model with continuous opinion is proposed to study how the speech order and the topology of directed social network affect the opinion formation of free speech. In the model, agents express their opinions one by one with random order (RO) or probability order (PO), other agents paying attentions to the speaking agent, receive provider's opinion, update their opinions and then express their new opinions in their turns. It is proved that with the same agent j repeats its opinion more, other agents who pay their attentions to j and include j's opinion in their confidence level at initial time, will continue approaching j's opinion. Simulation results reveal that on directed scale-free network: (1) the model for PO forms fewer opinion clusters, larger maximum cluster (MC), smaller standard deviation (SD), and needs less waiting time to reach a middle level of consensus than RO; (2) as the parameter of scale-free degree distribution decreases or the confidence level increases, the results often get better for both speech orders; (3) the differences between PO and RO get smaller as the size of network decreases.

New generation of magnetic and luminescent nanoparticles for in vivo real-time imaging

PubMed Central

Lacroix, Lise-Marie; Delpech, Fabien; Nayral, Céline; Lachaize, Sébastien; Chaudret, Bruno

2013-01-01

A new generation of optimized contrast agents is emerging, based on metallic nanoparticles (NPs) and semiconductor nanocrystals for, respectively, magnetic resonance imaging (MRI) and near-infrared (NIR) fluorescent imaging techniques. Compared with established contrast agents, such as iron oxide NPs or organic dyes, these NPs benefit from several advantages: their magnetic and optical properties can be tuned through size, shape and composition engineering, their efficiency can exceed by several orders of magnitude that of contrast agents clinically used, their surface can be modified to incorporate specific targeting agents and antifolding polymers to increase blood circulation time and tumour recognition, and they can possibly be integrated in complex architecture to yield multi-modal imaging agents. In this review, we will report the materials of choice based on the understanding of the basic physics of NIR and MRI techniques and their corresponding syntheses as NPs. Surface engineering, water transfer and specific targeting will be highlighted prior to their first use for in vivo real-time imaging. Highly efficient NPs that are safer and target specific are likely to enter clinical application in a near future. PMID:24427542

Cavitation-threshold Determination and Rheological-parameters Estimation of Albumin-stabilized Nanobubbles.

PubMed

Lafond, Maxime; Watanabe, Akiko; Yoshizawa, Shin; Umemura, Shin-Ichiro; Tachibana, Katsuro

2018-05-10

Nanobubbles (NBs) are of high interest for ultrasound (US) imaging as contrast agents and therapy as cavitation nuclei. Because of their instability (Laplace pressure bubble catastrophe) and low sensitivity to US, reducing the size of commonly used microbubbles to submicron-size is not trivial. We introduce stabilized NBs in the 100-250-nm size range, manufactured by agitating human serum albumin and perfluoro-propane. These NBs were exposed to 3.34- and 5.39-MHz US, and their sensitivity to US was proven by detecting inertial cavitation. The cavitation-threshold information was used to run a numerical parametric study based on a modified Rayleigh-Plesset equation (with a Newtonian rheology model). The determined values of surface tension ranged from 0 N/m to 0.06 N/m. The corresponding values of dilatational viscosity ranged from 5.10 -10 Ns/m to 1.10 -9 Ns/m. These parameters were reported to be 0.6 N/m and 1.10 -8 Ns/m for the reference microbubble contrast agent. This result suggests the possibility of using albumin as a stabilizer for the nanobubbles that could be maintained in circulation and presenting satisfying US sensitivity, even in the 3-5-MHz range.

Preparation and bactericide activity of gallic acid stabilized gold nanoparticles

NASA Astrophysics Data System (ADS)

Moreno-Álvarez, S. A.; Martínez-Castañón, G. A.; Niño-Martínez, N.; Reyes-Macías, J. F.; Patiño-Marín, N.; Loyola-Rodríguez, J. P.; Ruiz, Facundo

2010-10-01

In this work, gold nanoparticles with three different sizes (13.7, 39.4, and 76.7 nm) were prepared using a simple aqueous method with gallic acid as the reducing and stabilizing agent, the different sizes were obtained varying some experimental parameters as the pH of the reaction and the amount of the gallic acid. The prepared nanoparticles were characterized using X-ray diffraction, transmission electron microscopy, dynamic light scattering, and UV-Vis spectroscopy. Samples were identified as elemental gold and present spherical morphology, a narrow size distribution and good stabilization according to TEM and DLS results. The antibacterial activity of this gallic acid stabilized gold nanoparticles against S. mutans (the etiologic agent of dental caries) was assessed using a microdilution method obtaining a minimum inhibitory concentration of 12.31, 12.31, and 49.25 μg/mL for 13.7, 39.4, and 76.7 nm gold nanoparticles, respectively. The antibacterial assay showed that gold nanoparticles prepared in this work present a bactericide activity by a synergistic action with gallic acid. The MIC found for this nanoparticles are much lower than those reported for mixtures of gold nanoparticles and antibiotics.

Acoustic and photoacoustic characterization of micron-sized perfluorocarbon emulsions

NASA Astrophysics Data System (ADS)

Strohm, Eric M.; Gorelikov, Ivan; Matsuura, Naomi; Kolios, Michael C.

2012-09-01

Perfluorocarbon droplets containing nanoparticles (NPs) have recently been investigated as theranostic and dual-mode contrast agents. These droplets can be vaporized via laser irradiation or used as photoacoustic contrast agents below the vaporization threshold. This study investigates the photoacoustic mechanism of NP-loaded droplets using photoacoustic frequencies between 100 and 1000 MHz, where distinct spectral features are observed that are related to the droplet composition. The measured photoacoustic spectrum from NP-loaded perfluorocarbon droplets was compared to a theoretical model that assumes a homogenous liquid. Good agreement in the location of the spectral features was observed, which suggests the NPs act primarily as optical absorbers to induce thermal expansion of the droplet as a single homogenous object. The NP size and composition do not affect the photoacoustic spectrum; therefore, the photoacoustic signal can be maximized by optimizing the NP optical absorbing properties. To confirm the theoretical parameters in the model, photoacoustic, ultrasonic, and optical methods were used to estimate the droplet diameter. Photoacoustic and ultrasonic methods agreed to within 1.4%, while the optical measurement was 8.5% higher; this difference decreased with increasing droplet size. The small discrepancy may be attributed to the difficulty in observing the small droplets through the partially translucent phantom.

Acoustic and photoacoustic characterization of micron-sized perfluorocarbon emulsions.

PubMed

Strohm, Eric M; Gorelikov, Ivan; Matsuura, Naomi; Kolios, Michael C

2012-09-01

Perfluorocarbon droplets containing nanoparticles (NPs) have recently been investigated as theranostic and dual-mode contrast agents. These droplets can be vaporized via laser irradiation or used as photoacoustic contrast agents below the vaporization threshold. This study investigates the photoacoustic mechanism of NP-loaded droplets using photoacoustic frequencies between 100 and 1000 MHz, where distinct spectral features are observed that are related to the droplet composition. The measured photoacoustic spectrum from NP-loaded perfluorocarbon droplets was compared to a theoretical model that assumes a homogenous liquid. Good agreement in the location of the spectral features was observed, which suggests the NPs act primarily as optical absorbers to induce thermal expansion of the droplet as a single homogenous object. The NP size and composition do not affect the photoacoustic spectrum; therefore, the photoacoustic signal can be maximized by optimizing the NP optical absorbing properties. To confirm the theoretical parameters in the model, photoacoustic, ultrasonic, and optical methods were used to estimate the droplet diameter. Photoacoustic and ultrasonic methods agreed to within 1.4%, while the optical measurement was 8.5% higher; this difference decreased with increasing droplet size. The small discrepancy may be attributed to the difficulty in observing the small droplets through the partially translucent phantom.

In-situ heating TEM observation of microscopic structural changes of size-controlled metallic copper/gelatin composite.

PubMed

Narushima, Takashi; Hyono, Atsushi; Nishida, Naoki; Yonezawa, Tetsu

2012-10-01

Copper/gelatin composite particles with controlled sizes were prepared at room temperature from cupric sulfate pentahydrate in the presence of gelatin as a protective reagent by using hydrazine monohydrate as a reducing agent. The formed particles with the size between 190-940 nm were secondary aggregated particles which were composed of smaller nanosized particles ("particle-in-particle"), the presence of which was established by XRD patterns and a cross-sectional TEM image. The sintering behavior of these copper/gelatin composite particles was demonstrated by in-situ heating TEM under a high vacuum (approximately 10(-5) Pa) and separately with the oxygen partial pressure controlled at the 10(-4) Pa level. It was established that the particles began to sinter at about 330 degrees C with the oxygen and that they sublimate above 450 degrees C both in the vacuum and oxygen conditions. This result shows that the introduction of an adequate amount of oxygen was effective to remove the gelatin surrounding the particles. It can also be concluded that the sintering of the copper/gelatin composite particles occurred even in the absence of a reducing agent such as hydrogen gas.

Size, charge and concentration dependent uptake of iron oxide particles by non-phagocytic cells.

PubMed

Thorek, Daniel L J; Tsourkas, Andrew

2008-09-01

A promising new direction for contrast-enhanced magnetic resonance (MR) imaging involves tracking the migration and biodistribution of superparamagnetic iron oxide (SPIO)-labeled cells in vivo. Despite the large number of cell labeling studies that have been performed with SPIO particles of differing size and surface charge, it remains unclear which SPIO configuration provides optimal contrast in non-phagocytic cells. This is largely because contradictory findings have stemmed from the variability and imprecise control over surface charge, the general need and complexity of transfection and/or targeting agents, and the limited number of particle configurations examined in any given study. In the present study, we systematically evaluated the cellular uptake of SPIO in non-phagocytic T cells over a continuum of particle sizes ranging from 33nm to nearly 1.5microm, with precisely controlled surface properties, and without the need for transfection agents. SPIO labeling of T cells was analyzed by flow cytometry and contrast enhancement was determined by relaxometry. SPIO uptake was dose-dependent and exhibited sigmoidal charge dependence, which was shown to saturate at different levels of functionalization. Efficient labeling of cells was observed for particles up to 300nm, however, micron-sized particle uptake was limited. Our results show that an unconventional highly cationic particle configuration at 107nm maximized MR contrast of T cells, outperforming the widely utilized USPIO (<50nm).

Size, Charge and Concentration Dependent Uptake of Iron Oxide Particles by Non-Phagocytic Cells

PubMed Central

Thorek, Daniel L.J.; Tsourkas, Andrew

2008-01-01

A promising new direction for contrast-enhanced magnetic resonance (MR) imaging involves tracking the migration and biodistribution of superparamagnetic iron oxide (SPIO)-labeled cells in vivo. Despite the large number of cell labeling studies that have been performed with SPIO particles of differing size and surface charge, it remains unclear which SPIO configuration provides optimal contrast in non-phagocytic cells. This is largely because contradictory findings have stemmed from the variability and imprecise control over surface charge, the general need and complexity of transfection and/or targeting agents, and the limited number of particle configurations examined in any given study. In the present study, we systematically evaluated the cellular uptake of SPIO in non-phagocytic T cells over a continuum of particle sizes ranging from 33 nm to nearly 1.5 μm, with precisely controlled surface properties, and without the need for transfection agents. SPIO labeling of T cells was analyzed by flow cytometry and contrast enhancement was determined by relaxometry. SPIO uptake was dose dependent and exhibited sigmoidal charge dependence, which was shown to saturate at different levels of functionalization. Efficient labeling of cells was observed for particles up to 300nm, however micron-sized particle uptake was limited. Our results show that an unconventional highly cationic particle configuration at 107 nm maximized MR contrast of T cells, outperforming the widely utilized USPIO (<50 nm). PMID:18533252

Synthesis of surfactant-coated cobalt ferrite nanoparticles for adsorptive removal of acid blue 45 dye

NASA Astrophysics Data System (ADS)

Waheed Mushtaq, Muhammad; Kanwal, Farah; Imran, Muhammad; Ameen, Naila; Batool, Madeeha; Batool, Aisha; Bashir, Shahid; Mustansar Abbas, Syed; Rehman, Ata ur; Riaz, Saira; Naseem, Shahzad; Ullah, Zaka

2018-03-01

Cobalt ferrite (CoFe2O4) nanoparticles (NPs) are synthesized by wet chemical coprecipitation method using metal chlorides as precursors and potassium hydroxide (KOH) as a precipitant. The tergitol-1x (T-1x) and didecyldimethyl ammonium bromide (DDAB) are used as capping agents and their effect is investigated on particle size, size distribution and morphology of cobalt ferrite nanoparticles (CFNPs). The Fourier transform infrared spectroscopy confirms the synthesis of CFNPs and formation of metal-oxygen (M-O) bond. The spinel phase structure, morphology, polydispersity and magnetic properties of ferrite nanoparticles are investigated by x-ray diffraction, scanning electron microscopy, dynamic light scattering and vibrating sample magnetometry analyses, respectively. The addition of capping agents effects the secondary growth of CFNPs and reduces their particle size, as is investigated by dynamic light scattering and atomic force microscopy. The results evidence that the DDAB is more promising surfactant to control the particle size (∼13 nm), polydispersity and aggregation of CFNPs. The synthesized CFNPs, CFNPs/T-1x and CFNPs/DDAB are used to study their adsorption potential for removal of acid blue 45 dye, and a maximum adsorptive removal of 92.25% is recorded by 0.1 g of CFNPs/DDAB at pH 2.5 and temperature 20 ± 1 °C. The results show that the dye is physically adsorbed by magnetic NPs and follows the Langmuir isotherm model.

Habitat corridors facilitate genetic resilience irrespective of species dispersal abilities or population sizes.

PubMed

Christie, Mark R; Knowles, L Lacey

2015-06-01

Corridors are frequently proposed to connect patches of habitat that have become isolated due to human-mediated alterations to the landscape. While it is understood that corridors can facilitate dispersal between patches, it remains unknown whether corridors can mitigate the negative genetic effects for entire communities modified by habitat fragmentation. These negative genetic effects, which include reduced genetic diversity, limit the potential for populations to respond to selective agents such as disease epidemics and global climate change. We provide clear evidence from a forward-time, agent-based model (ABM) that corridors can facilitate genetic resilience in fragmented habitats across a broad range of species dispersal abilities and population sizes. Our results demonstrate that even modest increases in corridor width decreased the genetic differentiation between patches and increased the genetic diversity and effective population size within patches. Furthermore, we document a trade-off between corridor quality and corridor design whereby populations connected by high-quality habitat (i.e., low corridor mortality) are more resilient to suboptimal corridor design (e.g., long and narrow corridors). The ABM also revealed that species interactions can play a greater role than corridor design in shaping the genetic responses of populations to corridors. These results demonstrate how corridors can provide long-term conservation benefits that extend beyond targeted taxa and scale up to entire communities irrespective of species dispersal abilities or population sizes.

Habitat corridors facilitate genetic resilience irrespective of species dispersal abilities or population sizes

PubMed Central

Christie, Mark R; Knowles, L Lacey

2015-01-01

Corridors are frequently proposed to connect patches of habitat that have become isolated due to human-mediated alterations to the landscape. While it is understood that corridors can facilitate dispersal between patches, it remains unknown whether corridors can mitigate the negative genetic effects for entire communities modified by habitat fragmentation. These negative genetic effects, which include reduced genetic diversity, limit the potential for populations to respond to selective agents such as disease epidemics and global climate change. We provide clear evidence from a forward-time, agent-based model (ABM) that corridors can facilitate genetic resilience in fragmented habitats across a broad range of species dispersal abilities and population sizes. Our results demonstrate that even modest increases in corridor width decreased the genetic differentiation between patches and increased the genetic diversity and effective population size within patches. Furthermore, we document a trade-off between corridor quality and corridor design whereby populations connected by high-quality habitat (i.e., low corridor mortality) are more resilient to suboptimal corridor design (e.g., long and narrow corridors). The ABM also revealed that species interactions can play a greater role than corridor design in shaping the genetic responses of populations to corridors. These results demonstrate how corridors can provide long-term conservation benefits that extend beyond targeted taxa and scale up to entire communities irrespective of species dispersal abilities or population sizes. PMID:26029259

Size- and Shape-Dependent Antibacterial Studies of Silver Nanoparticles Synthesized by Wet Chemical Routes

PubMed Central

Raza, Muhammad Akram; Kanwal, Zakia; Rauf, Anum; Sabri, Anjum Nasim; Riaz, Saira; Naseem, Shahzad

2016-01-01

Silver nanoparticles (AgNPs) of different shapes and sizes were prepared by solution-based chemical reduction routes. Silver nitrate was used as a precursor, tri-sodium citrate (TSC) and sodium borohydride as reducing agents, while polyvinylpyrrolidone (PVP) was used as a stabilizing agent. The morphology, size, and structural properties of obtained nanoparticles were characterized by scanning electron microscopy (SEM), UV-visible spectroscopy (UV-VIS), and X-ray diffraction (XRD) techniques. Spherical AgNPs, as depicted by SEM, were found to have diameters in the range of 15 to 90 nm while lengths of the edges of the triangular particles were about 150 nm. The characteristic surface plasmon resonance (SPR) peaks of different spherical silver colloids occurring in the wavelength range of 397 to 504 nm, whereas triangular particles showed two peaks, first at 392 nm and second at 789 nm as measured by UV-VIS. The XRD spectra of the prepared samples indicated the face-centered cubic crystalline structure of metallic AgNPs. The in vitro antibacterial properties of all synthesized AgNPs against two types of Gram-negative bacteria, Pseudomonas aeruginosa and Escherichia coli were examined by Kirby–Bauer disk diffusion susceptibility method. It was noticed that the smallest-sized spherical AgNPs demonstrated a better antibacterial activity against both bacterial strains as compared to the triangular and larger spherical shaped AgNPs. PMID:28335201

Ontogenetic and evolutionary effects of predation and competition on nine-spined stickleback (Pungitius pungitius) body size.

PubMed

Välimäki, Kaisa; Herczeg, Gábor

2012-07-01

1. Individual- and population-level variation in body size and growth often correlates with many fitness traits. Predation and food availability are expected to affect body size and growth as important agents of both natural selection and phenotypic plasticity. How differences in predation and food availability affect body size/growth during ontogeny in populations adapted to different predation and competition regimes is rarely studied. 2. Nine-spined stickleback (Pungitius pungitius) populations originating from habitats with varying levels of predation and competition are known to be locally adapted to their respective habitats in terms of body size and growth. Here, we studied how different levels of perceived predation risk and competition during ontogeny affect the reaction norms of body size and growth in (i) marine and pond populations adapted to different levels of predation and competition and (ii) different sexes. We reared nine-spined stickleback in a factorial experiment under two levels of perceived predation risk (present/absent) and competition (high/low food supply). 3. We found divergence in the reaction norms at two levels: (i) predation-adapted marine stickleback had stronger reactions to predatory cues than intraspecific competition-adapted pond stickleback, the latter being more sensitive to available food than the marine fish and (ii) females reacting more strongly to the treatments than males. 4. The repeated, habitat-dependent nature of the differences suggests that natural selection is the agent behind the observed patterns. Our results suggest that genetic adaptation to certain environmental factors also involves an increase in the range of expressible phenotypic plasticity. We found support for this phenomenon at two levels: (i) across populations driven by habitat type and (ii) within populations driven by sex. © 2012 The Authors. Journal of Animal Ecology © 2012 British Ecological Society.

Field-isolated genotypes of Mycobacterium bovis vary in virulence and influence case pathology but do not affect outbreak size.

PubMed

Wright, David M; Allen, Adrian R; Mallon, Thomas R; McDowell, Stanley W J; Bishop, Stephen C; Glass, Elizabeth J; Bermingham, Mairead L; Woolliams, John A; Skuce, Robin A

2013-01-01

Strains of many infectious agents differ in fundamental epidemiological parameters including transmissibility, virulence and pathology. We investigated whether genotypes of Mycobacterium bovis (the causative agent of bovine tuberculosis, bTB) differ significantly in transmissibility and virulence, combining data from a nine-year survey of the genetic structure of the M. bovis population in Northern Ireland with detailed records of the cattle population during the same period. We used the size of herd breakdowns as a proxy measure of transmissibility and the proportion of skin test positive animals (reactors) that were visibly lesioned as a measure of virulence. Average breakdown size increased with herd size and varied depending on the manner of detection (routine herd testing or tracing of infectious contacts) but we found no significant variation among M. bovis genotypes in breakdown size once these factors had been accounted for. However breakdowns due to some genotypes had a greater proportion of lesioned reactors than others, indicating that there may be variation in virulence among genotypes. These findings indicate that the current bTB control programme may be detecting infected herds sufficiently quickly so that differences in virulence are not manifested in terms of outbreak sizes. We also investigated whether pathology of infected cattle varied according to M. bovis genotype, analysing the distribution of lesions recorded at post mortem inspection. We concentrated on the proportion of cases lesioned in the lower respiratory tract, which can indicate the relative importance of the respiratory and alimentary routes of infection. The distribution of lesions varied among genotypes and with cattle age and there were also subtle differences among breeds. Age and breed differences may be related to differences in susceptibility and husbandry, but reasons for variation in lesion distribution among genotypes require further investigation.

Tumor Vessel Compression Hinders Perfusion of Ultrasonographic Contrast Agents1

PubMed Central

Galiè, Mirco; D'Onofrio, Mirko; Montani, Maura; Amici, Augusto; Calderan, Laura; Marzola, Pasquina; Benati, Donatella; Merigo, Flavia; Marchini, Cristina; Sbarbati, Andrea

2005-01-01

Abstract Contrast-enhanced ultrasound (CEUS) is an advanced approach to in vivo assessment of tumor vascularity and is being increasingly adopted in clinical oncology. It is based on 1- to 10 µm-sized gas microbubbles, which can cross the capillary beds of the lungs and are effective echo enhancers. It is known that high cell density, high transendothelial fluid exchange, and poorly functioning lymphatic circulation all provoke solid stress, which compresses vessels and drastically reduces tumor blood flow. Given their size, we supposed that the perfusion of microbubbles is affected by anatomic features of tumor vessels more than are contrast agents traditionally used in dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). Here, we compared dynamic information obtained from CEUS and DCE-MRI on two experimental tumor models exhibiting notable differences in vessel anatomy. We found that tumors with small, flattened vessels show a much higher resistance to microbubble perfusion than to MRI contrast agents, and appear scarcely vascularized at CEUS examination, despite vessel volume adequate for normal function. Thus, whereas CEUS alone could induce incorrect diagnosis when tumors have small or collapsed vessels, integrated analysis using CEUS and DCE-MRI allows in vivo identification of tumors with a vascular profile frequently associated with malignant phenotypes. PMID:15967105

The influence of local majority opinions on the dynamics of the Sznajd model

NASA Astrophysics Data System (ADS)

Crokidakis, Nuno

2014-03-01

In this work we study a Sznajd-like opinion dynamics on a square lattice of linear size L. For this purpose, we consider that each agent has a convincing power C, that is a time-dependent quantity. Each high convincing power group of four agents sharing the same opinion may convince its neighbors to follow the group opinion, which induces an increase of the group's convincing power. In addition, we have considered that a group with a local majority opinion (3 up/1 down spins or 1 up/3 down spins) can persuade the agents neighboring the group with probability p, since the group's convincing power is high enough. The two mechanisms (convincing powers and probability p) lead to an increase of the competition among the opinions, which avoids dictatorship (full consensus, all spins parallel) for a wide range of model's parameters, and favors the occurrence of democratic states (partial order, the majority of spins pointing in one direction). We have found that the relaxation times of the model follow log-normal distributions, and that the average relaxation time τ grows with system size as τ ~ L5/2, independent of p. We also discuss the occurrence of the usual phase transition of the Sznajd model.

Green Synthesis of Ag, Cu and AgCu Nanoparticles using Palm Leaves Extract as the Reducing and Stabilizing Agents

NASA Astrophysics Data System (ADS)

Mohamad, N. A. N.; Arham, N. A.; Junaidah, J.; Hadi, A.; Idris, S. A.

2018-05-01

This paper reports the green synthesis of Ag, Cu and AgCu nanoparticles at room temperature using palm leaves extract. The purpose of this study is to eliminate the use of chemicals in the synthesis of nanoparticles and evaluate the efficiency of the palm leaves extract as the reducing and stabilizing agents. The palm leaves extract was added to metal salt solution and continuously stirred until reaction completed. The produced nanoparticles were analyzed using atomic absorption spectroscopy (AAS), Fourier transform infrared spectroscopy (FTIR), energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The analyses revealed that palm leaves extract has efficiently reduced the silver ions, but not the copper ions. During synthesis of AgCu nanoparticles, simultaneous reduction was occurred leading to formation of alloyed nanoparticles. Biomolecules from the palm leaves extract adsorbed on the surface of nanoparticles forming a capping layer thus stabilized the nanoparticles. The produced Ag and Cu nanoparticles were predominantly spherical with the particle size of Cu nanoparticles were larger than Ag nanoparticles. The AgCu nanoparticles closely resembled the Ag nanoparticles due to high Ag content with average size of 13nm. Therefore, palm leaves extract has a potential to be a good reducing and stabilizing agents.

A preliminary evaluation of self-made nanobubble in contrast-enhanced ultrasound imaging

NASA Astrophysics Data System (ADS)

Li, Chunfang; Wu, Kaizhi; Li, Jing; Liu, Haijuan; Zhou, Qibing; Ding, Mingyue

2014-03-01

Nanoscale bubbles (nanobubbles) have been reported to improve contrast in tumor-targeted ultrasound imaging due to the enhanced permeation and retention effects at tumor vascular leaks. In this work, a self-made nanobubble ultrasound contrast agent was preliminarily characterized and evaluated in-vitro and in-vivo. Fundamental properties such as morphology appearance, size distribution, zeta potential, bubble concentration (bubble numbers per milliliter contrast agent suspension) and the stability of nanobubbles were assessed by light microscope and particle sizing analysis. Then the concentration intensity curve and time intensity curves (TICs) were acquired by ultrasound imaging experiment in-vitro. Finally, the contrast-enhanced ultrasonography was performed on rat to investigate the procedure of liver perfusion. The results showed that the nanobubbles had good shape and uniform distribution with the average diameter of 507.9 nm, polydispersity index (PDI) of 0.527, and zeta potential of -19.17 mV. Significant contrast enhancement was observed in in-vitro ultrasound imaging, demonstrating that the self-made nanobubbles can enhance the contrast effect of ultrasound imaging efficiently in-vitro. Slightly contrast enhancement was observed in in-vivo ultrasound imaging, indicating that the nanobubbles are not stable enough in-vivo. Future work will be focused on improving the ultrasonic imaging performance, stability, and antibody binding of the nanoscale ultrasound contrast agent.

MPO4:Nd3+ (M=Ca, Gd), Luminomagnetic Nanophosphors with Optical and Magnetic Features for Multimodal Imaging Applications

NASA Astrophysics Data System (ADS)

Rightsell, Chris; Mimun, Lawrence C.; Kumar, Ajith G.; Sardar, Dhiraj K.

2015-03-01

Nanomaterials with multiple functionalities play a very important role in several high technology applications. A major area of such applications is the biomedical industry, where contrast agents with multiple imaging modalities can provide better results than conventional materials. Many of the contrast agents available now have drawbacks such as toxicity, photobleaching, low contrast, size restrictions, and overall cost of the imaging system. Rare-earth doped inorganic nanophosphors are alternatives to circumvent several of these issues, together with the added advantage of super high resolution imaging due to the excellent near infrared sensitivity of the phosphors. In addition to optical imaging features, by adding a magnetic ion such as Gd3+ at suitable lattice positions, the phosphor can be made magnetic, yielding dual imaging functionalities. In this research, we are presenting the optical and magnetic imaging features of sub-nanometer size MPO4:Nd3+ (M=Ca, Gd) phosphors for the potential application of these nanophosphors as multimodal contrast agents. Cytotoxicity, in vitro and in vivo imaging, penetration depth etc. are studied for various phosphor compositions, and optimized compositions are explored. This research was funded by the National Science Foundation Partnerships for Research and Education in Materials (NSF-PREM) Grant N0-DMR-0934218.

Single-Step Assembly of Multi-Modal Imaging Nanocarriers: MRI and Long-Wavelength Fluorescence Imaging

PubMed Central

Pinkerton, Nathalie M.; Gindy, Marian E.; Calero-DdelC, Victoria L.; Wolfson, Theodore; Pagels, Robert F.; Adler, Derek; Gao, Dayuan; Li, Shike; Wang, Ruobing; Zevon, Margot; Yao, Nan; Pacheco, Carlos; Therien, Michael J.; Rinaldi, Carlos; Sinko, Patrick J.

2015-01-01

MRI and NIR-active, multi-modal Composite NanoCarriers (CNCs) are prepared using a simple, one-step process, Flash NanoPrecipitation (FNP). The FNP process allows for the independent control of the hydrodynamic diameter, co-core excipient and NIR dye loading, and iron oxide-based nanocrystal (IONC) content of the CNCs. In the controlled precipitation process, 10 nm IONCs are encapsulated into poly(ethylene glycol) stabilized CNCs to make biocompatible T2 contrast agents. By adjusting the formulation, CNC size is tuned between 80 and 360 nm. Holding the CNC size constant at an intensity weighted average diameter of 99 ± 3 nm (PDI width 28 nm), the particle relaxivity varies linearly with encapsulated IONC content ranging from 66 to 533 mM-1s-1 for CNCs formulated with 4 to 16 wt% IONC. To demonstrate the use of CNCs as in vivo MRI contrast agents, CNCs are surface functionalized with liver targeting hydroxyl groups. The CNCs enable the detection of 0.8 mm3 non-small cell lung cancer metastases in mice livers via MRI. Incorporating the hydrophobic, NIR dye PZn3 into CNCs enables complementary visualization with long-wavelength fluorescence at 800 nm. In vivo imaging demonstrates the ability of CNCs to act both as MRI and fluorescent imaging agents. PMID:25925128

Autonomous microfluidic sample preparation system for protein profile-based detection of aerosolized bacterial cells and spores.

PubMed

Stachowiak, Jeanne C; Shugard, Erin E; Mosier, Bruce P; Renzi, Ronald F; Caton, Pamela F; Ferko, Scott M; Van de Vreugde, James L; Yee, Daniel D; Haroldsen, Brent L; VanderNoot, Victoria A

2007-08-01

For domestic and military security, an autonomous system capable of continuously monitoring for airborne biothreat agents is necessary. At present, no system meets the requirements for size, speed, sensitivity, and selectivity to warn against and lead to the prevention of infection in field settings. We present a fully automated system for the detection of aerosolized bacterial biothreat agents such as Bacillus subtilis (surrogate for Bacillus anthracis) based on protein profiling by chip gel electrophoresis coupled with a microfluidic sample preparation system. Protein profiling has previously been demonstrated to differentiate between bacterial organisms. With the goal of reducing response time, multiple microfluidic component modules, including aerosol collection via a commercially available collector, concentration, thermochemical lysis, size exclusion chromatography, fluorescent labeling, and chip gel electrophoresis were integrated together to create an autonomous collection/sample preparation/analysis system. The cycle time for sample preparation was approximately 5 min, while total cycle time, including chip gel electrophoresis, was approximately 10 min. Sensitivity of the coupled system for the detection of B. subtilis spores was 16 agent-containing particles per liter of air, based on samples that were prepared to simulate those collected by wetted cyclone aerosol collector of approximately 80% efficiency operating for 7 min.

Dynamics of Complex Systems Built as Coupled Physical, Communication and Decision Layers

PubMed Central

Kühnlenz, Florian; Nardelli, Pedro H. J.

2016-01-01

This paper proposes a simple model to capture the complexity of multilayer systems where their constituent layers affect, and are affected by, each other. The physical layer is a circuit composed by a power source and resistors in parallel. Every individual agent aims at maximizing its own delivered power by adding, removing or keeping the resistors it has; the delivered power is in turn a non-linear function that depends on the other agents’ behavior, its own internal state, its global state perception, the information received from its neighbors via the communication network and a randomized selfishness. We develop an agent-based simulation to analyze the effects of number of agents (system size), communication network topology, communication errors and the minimum power gain that triggers a behavioral change on the system dynamic. Our results show that a wave-like behavior at macro-level (caused by individual changes in the decision layer) can only emerge for a specific system size. The ratio between cooperators and defectors depends on the minimum gain assumed—lower minimal gains lead to less cooperation, and vice-versa. Different communication network topologies imply different levels of power utilization and fairness at the physical layer, and a certain level of error in the communication layer induces more cooperation. PMID:26730590

Monopoly models with time-varying demand function

NASA Astrophysics Data System (ADS)

Cavalli, Fausto; Naimzada, Ahmad

2018-05-01

We study a family of monopoly models for markets characterized by time-varying demand functions, in which a boundedly rational agent chooses output levels on the basis of a gradient adjustment mechanism. After presenting the model for a generic framework, we analytically study the case of cyclically alternating demand functions. We show that both the perturbation size and the agent's reactivity to profitability variation signals can have counterintuitive roles on the resulting period-2 cycles and on their stability. In particular, increasing the perturbation size can have both a destabilizing and a stabilizing effect on the resulting dynamics. Moreover, in contrast with the case of time-constant demand functions, the agent's reactivity is not just destabilizing, but can improve stability, too. This means that a less cautious behavior can provide better performance, both with respect to stability and to achieved profits. We show that, even if the decision mechanism is very simple and is not able to always provide the optimal production decisions, achieved profits are very close to those optimal. Finally, we show that in agreement with the existing empirical literature, the price series obtained simulating the proposed model exhibit a significant deviation from normality and large volatility, in particular when underlying deterministic dynamics become unstable and complex.

Tyrosine assisted size controlled synthesis of silver nanoparticles and their catalytic, in-vitro cytotoxicity evaluation.

PubMed

Maddinedi, Sireesh Babu; Mandal, Badal Kumar; Anna, Kiran Kumar

2017-04-01

A simple, green approach for the size controllable preparation of silver nanoparticles (SNPs) using tyrosine as reducing and capping agent is shown here. The size of SNPs is controlled by varying the pH of tyrosine solution. The as synthesized SNPs are characterized by using XRD, UV-Visible, DLS, TEM and SAED. Zeta potential measurements revealed the stability of tyrosine capped silver nanocolloids. Furthermore, catalytic activity studies concluded that the smaller SNPs acts as good catalyst and the catalytic activity depends on size of the nanoparticles. Further, the in-vitro cytotoxicity experiments concluded that the cytotoxicity of the prepared SNPs towards mouse fibroblast (3T3) cell lines is size and dose dependent. Additionally, the present approach is substitute to the traditional methods that are being used now-a-days for size controlled synthesis of SNPs. Copyright © 2017 Elsevier B.V. All rights reserved.

DETACHMENT OF BACTERIOPHAGE FROM ITS CARRIER PARTICLES.

PubMed

Hetler, D M; Bronfenbrenner, J

1931-05-20

The active substance (phage) present in the lytic broth filtrate is distributed through the medium in the form of particles. These particles vary in size within broad limits. The average size of these particles as calculated on the basis of the rate of diffusion approximates 4.4 mmicro in radius. Fractionation by means of ultrafiltration permits partial separation of particles of different sizes. Under conditions of experiments here reported the particles varied in the radius size from 0.6 mmicro to 11.4 mmicro. The active agent apparently is not intimately identified with these particles. It is merely carried by them by adsorption, and under suitable experimental conditions it can be detached from the larger particles and redistributed on smaller particles of the medium.

Production, depreciation and the size distribution of firms

NASA Astrophysics Data System (ADS)

Ma, Qi; Chen, Yongwang; Tong, Hui; Di, Zengru

2008-05-01

Many empirical researches indicate that firm size distributions in different industries or countries exhibit some similar characters. Among them the fact that many firm size distributions obey power-law especially for the upper end has been mostly discussed. Here we present an agent-based model to describe the evolution of manufacturing firms. Some basic economic behaviors are taken into account, which are production with decreasing marginal returns, preferential allocation of investments, and stochastic depreciation. The model gives a steady size distribution of firms which obey power-law. The effect of parameters on the power exponent is analyzed. The theoretical results are given based on both the Fokker-Planck equation and the Kesten process. They are well consistent with the numerical results.

Size controlled biogenic silver nanoparticles as antibacterial agent against isolates from HIV infected patients

NASA Astrophysics Data System (ADS)

Suganya, K. S. Uma; Govindaraju, K.; Kumar, V. Ganesh; Dhas, T. Stalin; Karthick, V.; Singaravelu, G.; Elanchezhiyan, M.

2015-06-01

Silver nanoparticles (AgNPs) are synthesized using biological sources due to its high specificity in biomedical applications. Herein, we report the size and shape controlled synthesis of AgNPs using the aqueous extract of blue green alga, Spirulina platensis. Size, shape and elemental composition of AgNPs were characterized using UV-vis spectroscopy, Fluorescence spectroscopy, FT-IR (Fourier Transform-Infrared Spectroscopy), FT-RS (Fourier Transform-Raman Spectroscopy), SEM-EDAX (Scanning Electron Microscopy-Energy Dispersive X-ray analysis) and HR-TEM (High Resolution Transmission Electron Microscopy). AgNPs were stable, well defined and monodispersed (spherical) with an average size of 6 nm. The synthesized AgNPs were tested for its antibacterial potency against isolates obtained from HIV patients.

Control design based on dead-zone and leakage adaptive laws for artificial swarm mechanical systems

NASA Astrophysics Data System (ADS)

Zhao, Xiaomin; Chen, Y. H.; Zhao, Han

2017-05-01

We consider the control design of artificial swarm systems with emphasis on four characteristics. First, the agent is made of mechanical components. As a result, the motion of each agent is subject to physical laws that govern mechanical systems. Second, both nonlinearity and uncertainty of the mechanical system are taken into consideration. Third, the ideal agent kinematic performance is treated as a desired d'Alembert constraint. This in turn suggests a creative way of embedding the constraint into the control design. Fourth, two types of adaptive robust control schemes are designed. They both contain leakage and dead-zone. However, one design suggests a trade-off between the amount of leakage and the size of dead-zone, in exchange for a simplified dead-zone structure.

Biocompatible Polyhydroxyethylaspartamide-based Micelles with Gadolinium for MRI Contrast Agents

NASA Astrophysics Data System (ADS)

Jeong, Sang Young; Kim, Hyo Jeong; Kwak, Byung-Kook; Lee, Ha-Young; Seong, Hasoo; Shin, Byung Cheol; Yuk, Soon Hong; Hwang, Sung-Joo; Cho, Sun Hang

2010-12-01

Biocompatible poly-[ N-(2-hydroxyethyl)- d, l-aspartamide]-methoxypoly(ethyleneglycol)-hexadecylamine (PHEA-mPEG-C16) conjugated with 1,4,7,10-tetraazacyclododecan-1,4,7,10-tetraacetic acid-gadolinium (DOTA-Gd) via ethylenediamine (ED) was synthesized as a magnetic resonance imaging (MRI) contrast agent. Amphiphilic PHEA-mPEG-C16-ED-DOTA-Gd forms micelle in aqueous solution. All the synthesized materials were characterized by proton nuclear magnetic resonance (1H NMR). Micelle size and shape were examined by dynamic light scattering (DLS) and atomic force microscopy (AFM). Micelles with PHEA-mPEG-C16-ED-DOTA-Gd showed higher relaxivities than the commercially available gadolinium contrast agent. Moreover, the signal intensity of a rabbit liver was effectively increased after intravenous injection of PHEA-mPEG-C16-ED-DOTA-Gd.

Nanocellular thermoplastic foam and process for making the same

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, Lingbo; Costeux, Stephane; Patankar, Kshitish A.

Prepare a thermoplastic polymer foam having a porosity of 70% or more and at least one of: (i) an average cell size of 200 nanometers or less; and (ii) a nucleation density of at least 1.times.1015 effective nucleation sites per cubic centimeter of foamable polymer composition not including blowing agent using a foamable polymer composition containing a thermoplastic polymer selected from styrenic polymer and (meth)acrylic polymers, a blowing agent comprising at least 20 mole-percent carbon dioxide based on moles of blowing agent and an additive having a Total Hansen Solubility Parameter that differs from that of carbon dioxide by lessmore » than 2 and that is present at a concentration of 0.01 to 1.5 weight parts per hundred weight parts thermoplastic polymer.« less

Iron removal on feldspar by using Averrhoa bilimbii as bioleaching agent

NASA Astrophysics Data System (ADS)

Amin, Muhammad; Aji, Bramantyo B.; Supriyatna, Yayat Iman; Bahfie, Fathan

2017-01-01

Investigation of Averrhoa bilimbii as bioleaching agent was carried out. Parameters of leaching duration, acid concentration, and temperature were performed in iron removal process. Feldspar with sized 149 µm was diluted in 30 ml acid solution in order to reduce its iron content. The experimental results showed a good technical feasibility of the process which iron oxide content of feldspar was decreased from 2.24% to 0.29%. The lowest iron concentration remained was obtained after 5 hours of leaching treatment at 60 °C, and concentrated (100 vol%) Averrhoa bilimbii extract as bioleaching agent. SEM characterizations were carried out on the feldspar before and after the leaching treatment. The result shows that there were no significant effect of leaching process on the ore morphology.

Optical tracer size differences allow quantitation of active pumping rate versus Stokes-Einstein diffusion in lymphatic transport

NASA Astrophysics Data System (ADS)

DSouza, Alisha V.; Marra, Kayla; Gunn, Jason R.; Samkoe, Kimberley S.; Pogue, Brian W.

2016-10-01

Lymphatic uptake of interstitially administered agents occurs by passive convective-diffusive inflow driven by interstitial concentration and pressure, while the downstream lymphatic transport is facilitated by active propulsive contractions of lymphatic vessel walls. Near-infrared fluorescence imaging in mice was used to measure these central components of lymphatic transport for the first time, using two different-sized molecules-methylene blue (MB) and fluorescence-labeled antibody immunoglobulin G (IgG)-IRDye 680RD. This work confirms the hypothesis that lymphatic passive inflow and active propulsion rates can be separated based upon the relative differences in Stokes-Einstein diffusion coefficient. This coefficient specifically affects the passive-diffusive uptake when the interstitial volume and pressure are constant. Parameters such as mean time-to-peak signal, overall fluorescence signal intensities, and number of active peristaltic pulses, were estimated from temporal imaging data. While the mean time to attain peak signal representative of diffusion-dominated flow in the lymph vessels was 0.6±0.2 min for MB and 8±6 min for IgG, showing a size dependence, the active propulsion rates were 3.4±0.8 pulses/min and 3.3±0.5 pulses/min, respectively, appearing size independent. The propulsion rates for both dyes decreased with clearance from the interstitial injection-site, indicating intrinsic control of the smooth muscles in response to interstitial pressure. This approach to size-comparative agent flow imaging of lymphatic function can enable noninvasive characterization of diseases related to uptake and flow in lymph networks.

Epithelial cell biocompatibility of silica nanospheres for contrast-enhanced ultrasound molecular imaging

NASA Astrophysics Data System (ADS)

Chiriacò, Fernanda; Conversano, Francesco; Soloperto, Giulia; Casciaro, Ernesto; Ragusa, Andrea; Sbenaglia, Enzo Antonio; Dipaola, Lucia; Casciaro, Sergio

2013-07-01

Nanosized particles are receiving increasing attention as future contrast agents (CAs) for ultrasound (US) molecular imaging, possibly decorated on its surface with biological recognition agents for targeted delivery and deposition of therapeutics. In particular, silica nanospheres (SiNSs) have been demonstrated to be feasible in terms of contrast enhancement on conventional US systems. In this work, we evaluated the cytotoxicity of SiNSs on breast cancer (MCF-7) and HeLa (cervical cancer) cells employing NSs with sizes ranging from 160 to 330 nm and concentration range of 1.5-5 mg/mL. Cell viability was evaluated in terms of size, dose and time dependence, performing the MTT reduction assay with coated and uncoated SiNSs. Whereas uncoated SiNSs caused a variable significant decrease in cell viability on both cell lines mainly depending on size and exposure time, PEGylated SiNSs (SiNSs-PEG) exhibit a high level of biocompatibility. In fact, after 72-h incubation, viability of both cell types was above the cutoff value of 70 % at concentration up to 5 mg/mL. We also investigated the acoustical behavior of coated and uncoated SiNSs within conventional diagnostic US fields in order to determine a suitable configuration, in terms of particle size and concentration, for their employment as targetable CAs. Our results indicate that the employment of SiNSs with diameters around 240 nm assures the most effective contrast enhancement even at the lowest tested concentration, coupled with the possibility of targeting all tumor tissues, being the SiNSs still in a size range where reticuloendothelial system trapping effect is relatively low.

Nanocomposite scaffolds with tunable mechanical and degradation capabilities: co-delivery of bioactive agents for bone tissue engineering.

PubMed

Cattalini, Juan P; Roether, Judith; Hoppe, Alexander; Pishbin, Fatemeh; Haro Durand, Luis; Gorustovich, Alejandro; Boccaccini, Aldo R; Lucangioli, Silvia; Mouriño, Viviana

2016-10-21

Novel multifunctional nanocomposite scaffolds made of nanobioactive glass and alginate crosslinked with therapeutic ions such as calcium and copper were developed for delivering therapeutic agents, in a highly controlled and sustainable manner, for bone tissue engineering. Alendronate, a well-known antiresorptive agent, was formulated into microspheres under optimized conditions and effectively loaded within the novel multifunctional scaffolds with a high encapsulation percentage. The size of the cation used for the alginate crosslinking impacted directly on porosity and viscoelastic properties, and thus, on the degradation rate and the release profile of copper, calcium and alendronate. According to this, even though highly porous structures were created with suitable pore sizes for cell ingrowth and vascularization in both cases, copper-crosslinked scaffolds showed higher values of porosity, elastic modulus, degradation rate and the amount of copper and alendronate released, when compared with calcium-crosslinked scaffolds. In addition, in all cases, the scaffolds showed bioactivity and mechanical properties close to the endogenous trabecular bone tissue in terms of viscoelasticity. Furthermore, the scaffolds showed osteogenic and angiogenic properties on bone and endothelial cells, respectively, and the extracts of the biomaterials used promoted the formation of blood vessels in an ex vivo model. These new bioactive nanocomposite scaffolds represent an exciting new class of therapeutic cell delivery carrier with tunable mechanical and degradation properties; potentially useful in the controlled and sustainable delivery of therapeutic agents with active roles in bone formation and angiogenesis, as well as in the support of cell proliferation and osteogenesis for bone tissue engineering.

Photoacoustic spectral characterization of perfluorocarbon droplets

NASA Astrophysics Data System (ADS)

Strohm, Eric; Gorelikov, Ivan; Matsuura, Naomi; Kolios, Michael

2012-02-01

Perfluorocarbon droplets containing optical absorbing nanoparticles have been developed for use as theranostic agents (for both imaging and therapy) and as dual-mode contrast agents. Droplets can be used as photoacoustic contrast agents, vaporized via optical irradiation, then the resulting bubbles can be used as ultrasound imaging and therapeutic agents. The photoacoustic signals from micron-sized droplets containing silica coated gold nanospheres were measured using ultra-high frequencies (100-1000 MHz). The spectra of droplets embedded in a gelatin phantom were compared to a theoretical model which calculates the pressure wave from a spherical homogenous liquid undergoing thermoelastic expansion resulting from laser absorption. The location of the spectral features of the theoretical model and experimental spectra were in agreement after accounting for increases in the droplet sound speed with frequency. The agreement between experiment and model indicate that droplets (which have negligible optical absorption in the visible and infrared spectra by themselves) emitted pressure waves related to the droplet composition and size, and was independent of the physical characteristics of the optical absorbing nanoparticles. The diameter of individual droplets was calculated using three independent methods: the time domain photoacoustic signal, the time domain pulse echo ultrasound signal, and a fit to the photoacoustic model, then compared to the diameter as measured by optical microscopy. It was found the photoacoustic and ultrasound methods calculated diameters an average of 2.6% of each other, and 8.8% lower than that measured using optical microscopy. The discrepancy between the calculated diameters and the optical measurements may be due to the difficulty in resolving the droplet edges after being embedded in the translucent gelatin medium.

Formulation and acoustic studies of a new phase-shift agent for diagnostic and therapeutic ultrasound.

PubMed

Sheeran, Paul S; Luois, Samantha; Dayton, Paul A; Matsunaga, Terry O

2011-09-06

Recent efforts in the area of acoustic droplet vaporization with the objective of designing extravascular ultrasound contrast agents has led to the development of stabilized, lipid-encapsulated nanodroplets of the highly volatile compound decafluorobutane (DFB). We developed two methods of generating DFB droplets, the first of which involves condensing DFB gas (boiling point from -1.1 to -2 °C) followed by extrusion with a lipid formulation in HEPES buffer. Acoustic droplet vaporization of micrometer-sized lipid-coated droplets at diagnostic ultrasound frequencies and mechanical indices were confirmed optically. In our second formulation methodology, we demonstrate the formulation of submicrometer-sized lipid-coated nanodroplets based upon condensation of preformed microbubbles containing DFB. The droplets are routinely in the 200-300 nm range and yield microbubbles on the order of 1-5 μm once vaporized, consistent with ideal gas law expansion predictions. The simple and effective nature of this methodology allows for the development of a variety of different formulations that can be used for imaging, drug and gene delivery, and therapy. This study is the first to our knowledge to demonstrate both a method of generating ADV agents by microbubble condensation and formulation of primarily submicrometer droplets of decafluorobutane that remain stable at physiological temperatures. Finally, activation of DFB nanodroplets is demonstrated using pressures within the FDA guidelines for diagnostic imaging, which may minimize the potential for bioeffects in humans. This methodology offers a new means of developing extravascular contrast agents for diagnostic and therapeutic applications. © 2011 American Chemical Society

Optimization for extracellular biosynthesis of silver nanoparticles by Penicillium aculeatum Su1 and their antimicrobial activity and cytotoxic effect compared with silver ions.

PubMed

Ma, Liang; Su, Wei; Liu, Jian-Xin; Zeng, Xiao-Xi; Huang, Zhi; Li, Wen; Liu, Zheng-Chun; Tang, Jian-Xin

2017-08-01

The present study addresses an eco-friendly and energy-saving method for extracellular biosynthesis of silver nanoparticles (AgNPs) using a cell free filtrate of the fungus strain Penicillium aculeatum Su1 as a reducing agent. Parametric optimization of the biosynthesis process demonstrated different effects on the size, distribution, yield, and synthesis rate of biosynthesized AgNPs. The transmission electron microscopy (TEM) measurements demonstrated that AgNPs were spherical or approximately spherical, with a size between 4 and 55nm. High-resolution transmission electron microscopy (HR-TEM) and X-ray diffraction (XRD) analyses indicated that AgNPs were nanocrystalline by nature, with the character of a face-centered cubic (fcc). Fourier transform infrared spectroscopy (FTIR) analysis confirmed the existence of protein molecules that acted as a reducing agent and a capping agent during the biosynthesis process. Furthermore, the biosynthesized AgNPs exhibited higher antimicrobial activity than silver ions against Gram negative bacteria, Gram positive bacteria and fungi. Compared with silver ions, the biosynthesized AgNPs presented higher biocompatibility toward human bronchial epithelial (HBE) cells and high cytotoxicity in a dose-dependent manner with an IC 50 of 48.73μg/mL toward A549 cells. These results demonstrate that Penicillium aculeatum Su1 is a potential bioresource that can be used to produce low-cost and eco-friendly AgNPs as efficient antimicrobial agent, drug delivery vehicle or anticancer drug for clinic treatment. Copyright © 2017 Elsevier B.V. All rights reserved.

When Does Diversity Trump Ability (and Vice Versa) in Group Decision Making? A Simulation Study

PubMed Central

Luan, Shenghua; Katsikopoulos, Konstantinos V.; Reimer, Torsten

2012-01-01

It is often unclear which factor plays a more critical role in determining a group's performance: the diversity among members of the group or their individual abilities. In this study, we addressed this “diversity vs. ability” issue in a decision-making task. We conducted three simulation studies in which we manipulated agents' individual ability (or accuracy, in the context of our investigation) and group diversity by varying (1) the heuristics agents used to search task-relevant information (i.e., cues); (2) the size of their groups; (3) how much they had learned about a good cue search order; and (4) the magnitude of errors in the information they searched. In each study, we found that a manipulation reducing agents' individual accuracy simultaneously increased their group's diversity, leading to a conflict between the two. These conflicts enabled us to identify certain conditions under which diversity trumps individual accuracy, and vice versa. Specifically, we found that individual accuracy is more important in task environments in which cues differ greatly in the quality of their information, and diversity matters more when such differences are relatively small. Changing the size of a group and the amount of learning by an agent had a limited impact on this general effect of task environment. Furthermore, we found that a group achieves its highest accuracy when there is an intermediate amount of errors in the cue information, regardless of the environment and the heuristic used, an effect that we believe has not been previously reported and warrants further investigation. PMID:22359562

CHANGES IN LIPID-ENCAPSULATED MICROBUBBLE POPULATION DURING CONTINUOUS INFUSION AND METHODS TO MAINTAIN CONSISTENCY

PubMed Central

KAYA, MEHMET; GREGORY, THOMAS S.; DAYTON, PAUL A.

2009-01-01

Stabilized microbubbles are utilized as ultrasound contrast agents. These micron-sized gas capsules are injected into the bloodstream to provide contrast enhancement during ultrasound imaging. Some contrast imaging strategies, such as destruction-reperfusion, require a continuous injection of microbubbles over several minutes. Most quantitative imaging strategies rely on the ability to administer a consistent dose of contrast agent. Because of the buoyancy of these gas-filled agents, their spatial distribution within a syringe changes over time. The population of microbubbles that is pumped from a horizontal syringe outlet differs from initial population as the microbubbles float to the syringe top. In this manuscript, we study the changes in the population of a contrast agent that is pumped from a syringe due to microbubble floatation. Results are presented in terms of change in concentration and change in mean diameter, as a function of time, suspension medium, and syringe diameter. Data illustrate that the distribution of contrast agents injected from a syringe changes in both concentration and mean diameter over several minutes without mixing. We discuss the application of a mixing system and viscosity agents to keep the contrast solution more evenly distributed in a syringe. These results are significant for researchers utilizing microbubble contrast agents in continuous-infusion applications where it is important to maintain consistent contrast agent delivery rate, or in situations where the injection syringe cannot be mixed immediately prior to administration. PMID:19632760

27 CFR 555.125 - Records maintained by permittees.

Code of Federal Regulations, 2011 CFR

2011-04-01

...; (iii) Manufacturer's marks of identification; (iv) Quantity (applicable quantity units, such as pounds... (dyn), blasting agents (ba), detonators (det), display fireworks (df), etc., and size (length and... nonlicensees or nonpermittees as prescribed in § 555.126. (5) The regional director (compliance) may authorize...

27 CFR 555.125 - Records maintained by permittees.

Code of Federal Regulations, 2010 CFR

2010-04-01

...; (iii) Manufacturer's marks of identification; (iv) Quantity (applicable quantity units, such as pounds... (dyn), blasting agents (ba), detonators (det), display fireworks (df), etc., and size (length and... nonlicensees or nonpermittees as prescribed in § 555.126. (5) The regional director (compliance) may authorize...

Effect of various factors on shoot regeneration from citrus epicotyl explants

USDA-ARS?s Scientific Manuscript database

The effect of various treatments on shoot organogenesis from seedling epicotyl explants from various scion and rootstock polyembryonic citrus types was determined. Treatments included water source, gelling agent, explant insertion, seed size, light intensity, malachite green, nonionic surfactants, a...

ROOM TEMPERATURE BULK AND TEMPLATE-FREE SYNTHESIS OF LEUCOEMARLDINE POLYANILINE NANOFIBERS

EPA Science Inventory

Herein, we describe a simple strategy for the bulk and template-free synthesis of reduced leucoemarldine polyaniline nanofibers size ranging from as low as 10 nm to 50 nm without the use of any reducing agents at room temperature.

The influence of persuasion in opinion formation and polarization

NASA Astrophysics Data System (ADS)

La Rocca, C. E.; Braunstein, L. A.; Vazquez, F.

2014-05-01

We present a model that explores the influence of persuasion in a population of agents with positive and negative opinion orientations. The opinion of each agent is represented by an integer number k that expresses its level of agreement on a given issue, from totally against k=-M to totally in favor k = M. Same-orientation agents persuade each other with probability p, becoming more extreme, while opposite-orientation agents become more moderate as they reach a compromise with probability q. The population initially evolves to (a) a polarized state for r=p/q\\gt 1 , where opinions' distribution is peaked at the extreme values k=+/- M , or (b) a centralized state for r < 1, with most opinions around k=+/- 1 . When r \\gg 1 , polarization lasts for a time that diverges as r^M \\ln N , where N is the population's size. Finally, an extremist consensus (k = M or -M ) is reached in a time that scales as r^{-1} for r \\ll 1 .

On the Motion of Agents across Terrain with Obstacles

NASA Astrophysics Data System (ADS)

Kuznetsov, A. V.

2018-01-01

The paper is devoted to finding the time optimal route of an agent travelling across a region from a given source point to a given target point. At each point of this region, a maximum allowed speed is specified. This speed limit may vary in time. The continuous statement of this problem and the case when the agent travels on a grid with square cells are considered. In the latter case, the time is also discrete, and the number of admissible directions of motion at each point in time is eight. The existence of an optimal solution of this problem is proved, and estimates of the approximate solution obtained on the grid are obtained. It is found that decreasing the size of cells below a certain limit does not further improve the approximation. These results can be used to estimate the quasi-optimal trajectory of the agent motion across the rugged terrain produced by an algorithm based on a cellular automaton that was earlier developed by the author.

Development of self-healing polymers via amine-epoxy chemistry: I. Properties of healing agent carriers and the modelling of a two-part self-healing system

NASA Astrophysics Data System (ADS)

Zhang, He; Yang, Jinglei

2014-06-01

Two types of healing agent carriers (microcapsules containing epoxy solution, referred to as EP-capsules, and etched hollow glass bubbles (HGBs) loaded with amine solution, referred to as AM-HGBs) used in self-healing epoxy systems were prepared and characterized in this study. The core percentages were measured at about 80 wt% and 33 wt% for EP-capsules and AM-HGBs, respectively. The loaded amine in AM-HGB, after incorporation into the epoxy matrix, showed high stability at ambient temperature, but diffused out gradually during heat treatment at 80 °C. The amount and the mass ratio of the two released healants at the crack plane were correlated with the size, concentration, and core percentage of the healing agent carriers. A simplified cubic array model for randomly distributed healing agent carriers was adopted to depict the longest diffusion distance of the released healants, which is inversely proportional to the cubic root of the carrier concentration.

Magnetic nanoparticles in magnetic resonance imaging and diagnostics.

PubMed

Rümenapp, Christine; Gleich, Bernhard; Haase, Axel

2012-05-01

Magnetic nanoparticles are useful as contrast agents for magnetic resonance imaging (MRI). Paramagnetic contrast agents have been used for a long time, but more recently superparamagnetic iron oxide nanoparticles (SPIOs) have been discovered to influence MRI contrast as well. In contrast to paramagnetic contrast agents, SPIOs can be functionalized and size-tailored in order to adapt to various kinds of soft tissues. Although both types of contrast agents have a inducible magnetization, their mechanisms of influence on spin-spin and spin-lattice relaxation of protons are different. A special emphasis on the basic magnetism of nanoparticles and their structures as well as on the principle of nuclear magnetic resonance is made. Examples of different contrast-enhanced magnetic resonance images are given. The potential use of magnetic nanoparticles as diagnostic tracers is explored. Additionally, SPIOs can be used in diagnostic magnetic resonance, since the spin relaxation time of water protons differs, whether magnetic nanoparticles are bound to a target or not.

Mentalizing skills do not differentiate believers from non-believers, but credibility enhancing displays do.

PubMed

Maij, David L R; van Harreveld, Frenk; Gervais, Will; Schrag, Yann; Mohr, Christine; van Elk, Michiel

2017-01-01

The ability to mentalize has been marked as an important cognitive mechanism enabling belief in supernatural agents. In five studies we cross-culturally investigated the relationship between mentalizing and belief in supernatural agents with large sample sizes (over 67,000 participants in total) and different operationalizations of mentalizing. The relative importance of mentalizing for endorsing supernatural beliefs was directly compared with credibility enhancing displays-the extent to which people observed credible religious acts during their upbringing. We also compared autistic with neurotypical adolescents. The empathy quotient and the autism-spectrum quotient were not predictive of belief in supernatural agents in all countries (i.e., The Netherlands, Switzerland and the United States), although we did observe a curvilinear effect in the United States. We further observed a strong influence of credibility enhancing displays on belief in supernatural agents. These findings highlight the importance of cultural learning for acquiring supernatural beliefs and ask for reconsiderations of the importance of mentalizing.

Mentalizing skills do not differentiate believers from non-believers, but credibility enhancing displays do

PubMed Central

van Harreveld, Frenk; Gervais, Will; Schrag, Yann; Mohr, Christine; van Elk, Michiel

2017-01-01

The ability to mentalize has been marked as an important cognitive mechanism enabling belief in supernatural agents. In five studies we cross-culturally investigated the relationship between mentalizing and belief in supernatural agents with large sample sizes (over 67,000 participants in total) and different operationalizations of mentalizing. The relative importance of mentalizing for endorsing supernatural beliefs was directly compared with credibility enhancing displays–the extent to which people observed credible religious acts during their upbringing. We also compared autistic with neurotypical adolescents. The empathy quotient and the autism-spectrum quotient were not predictive of belief in supernatural agents in all countries (i.e., The Netherlands, Switzerland and the United States), although we did observe a curvilinear effect in the United States. We further observed a strong influence of credibility enhancing displays on belief in supernatural agents. These findings highlight the importance of cultural learning for acquiring supernatural beliefs and ask for reconsiderations of the importance of mentalizing. PMID:28832606

Synthesis and in vitro evaluation of bone-seeking superparamagnetic iron oxide nanoparticles as contrast agents for imaging bone metabolic activity.

PubMed

Panahifar, Arash; Mahmoudi, Morteza; Doschak, Michael R

2013-06-12

In this article, we report the synthesis and in vitro evaluation of a new class of nonionizing bone-targeting contrast agents based on bisphosphonate-conjugated superparamagnetic iron oxide nanoparticles (SPIONs), for use in imaging of bone turnover with magnetic resonance imaging (MRI). Similar to bone-targeting (99m)Technetium medronate, our novel contrast agent uses bisphosphonates to impart bone-seeking properties, but replaces the former radioisotope with nonionizing SPIONs which enables their subsequent detection using MRI. Our reported method is relatively simple, quick and cost-effective and results in BP-SPIONs with a final nanoparticle size of 17 nm under electron microscopy technique (i.e., TEM). In-vitro binding studies of our novel bone tracer have shown selective binding affinity (around 65%) for hydroxyapatite, the principal mineral of bone. Bone-targeting SPIONs offer the potential for use as nonionizing MRI contrast agents capable of imaging dynamic bone turnover, for use in the diagnosis and monitoring of metabolic bone diseases and related bone pathology.

Statistics of the Kolkata Paise Restaurant problem

NASA Astrophysics Data System (ADS)

Ghosh, Asim; Chatterjee, Arnab; Mitra, Manipushpak; Chakrabarti, Bikas K.

2010-07-01

We study the dynamics of a few stochastic learning strategies for the 'Kolkata Paise Restaurant' problem, where N agents choose among N equally priced but differently ranked restaurants every evening, such that each agent tries to get dinner in the best restaurant (with each restaurant serving only one customer and the rest of the customers arriving there going without dinner that evening). We consider the learning strategies to be similar for all the agents, and assume that each follows the same probabilistic or stochastic strategy dependent on information about past successes in the game. We show that some 'naive' strategies lead to much better utilization of services than some relatively 'smarter' strategies. We also show that a service utilization fraction as high as 0.80 can result for a stochastic strategy, where each agent sticks to his past choice (independent of success achieved or not, with probability decreasing inversely in the past crowd size). The numerical results for the utilization fraction of the services in some limiting cases are analytically examined.

Encapsulated microbubbles and echogenic liposomes for contrast ultrasound imaging and targeted drug delivery

PubMed Central

Paul, Shirshendu; Nahire, Rahul; Mallik, Sanku; Sarkar, Kausik

2014-01-01

Micron- to nanometer-sized ultrasound agents, like encapsulated microbubbles and echogenic liposomes, are being developed for diagnostic imaging and ultrasound mediated drug/gene delivery. This review provides an overview of the current state of the art of the mathematical models of the acoustic behavior of ultrasound contrast microbubbles. We also present a review of the in vitro experimental characterization of the acoustic properties of microbubble based contrast agents undertaken in our laboratory. The hierarchical two-pronged approach of modeling contrast agents we developed is demonstrated for a lipid coated (Sonazoid™) and a polymer shelled (poly D-L-lactic acid) contrast microbubbles. The acoustic and drug release properties of the newly developed echogenic liposomes are discussed for their use as simultaneous imaging and drug/gene delivery agents. Although echogenicity is conclusively demonstrated in experiments, its physical mechanisms remain uncertain. Addressing questions raised here will accelerate further development and eventual clinical approval of these novel technologies. PMID:26097272

Effects of Korean Red Ginseng extract on busulfan-induced dysfunction of the male reproductive system.

PubMed

Jung, Seok-Won; Kim, Hyeon-Joong; Lee, Byung-Hwan; Choi, Sun-Hye; Kim, Hyun-Sook; Choi, Yang-Kyu; Kim, Joon Yong; Kim, Eun-Soo; Hwang, Sung-Hee; Lim, Kwang Yong; Kim, Hyoung-Chun; Jang, Minhee; Park, Seong Kyu; Cho, Ik-Hyun; Nah, Seung-Yeol

2015-07-01

Anticancer agents induce a variety of adverse effects when administered to cancer patients. Busulfan is a known antileukemia agent. When administered for treatment of leukemia in young patients, busulfan could cause damage to the male reproductive system as one of its adverse effects, resulting in sterility. We investigated the effects of Korean Red Ginseng extract (KRGE) on busulfan-induced damage and/or dysfunction of the male reproductive system. We found that administration of busulfan to mice: decreased testis weight; caused testicular histological damage; reduced the total number of sperm, sperm motility, serum testosterone concentration; and eventually, litter size. Preadministration of KRGE partially attenuated various busulfan-induced damages to the male reproductive system. These results indicate that KRGE has a protective effect against busulfan-induced damage to the male reproduction system. The present study shows a possibility that KRGE could be applied as a useful agent to prevent or protect the male reproductive system from the adverse side effects induced by administration of anticancer agents such as busulfan.

Aspirin- and Indomethacin-Induced Ulcers and their Antagonism by Anthihistamines

NASA Technical Reports Server (NTRS)

Brown, Patricia A.; Sawrey, James M.; Vernikos, Joan

1978-01-01

Gastric ulceration produced by aspirin and indomethacin was compared in acutely stressed and non-stressed rats. We found a synergism between these anti-inflammatory agents and acute stress in the production of gastric ulcers. Even at relatively high doses, neither agent caused appreciable gastric damage in non-stressed rats, whereas moderate doses of both agents produced massive ulceration in stressed rats. The synergism appears unrelated to the effect of these agents on the pituitary-adrenal response. The size and regional distribution of ulcers produced by aspirin and indomethacin in stressed rats were comparable. However, the dose--response curves of the two drugs were markedly dissimilar. Furthermore, the ulceration produced by indomethacin was attenuated by both H(sub 1) and H(sub 2) histamine receptor antagonists, whereas ulceration produced by aspirin was attenuated only by an H(sub 2) antagonist. The results suggest that the ulcerogenic mechanism of indomethacin may differ from that of aspirin and add to the growing evidence on the importance of endogenous histamine in various forms of gastric ulceration.

BLGAN: Bayesian learning and genetic algorithm for supporting negotiation with incomplete information.

PubMed

Sim, Kwang Mong; Guo, Yuanyuan; Shi, Benyun

2009-02-01

Automated negotiation provides a means for resolving differences among interacting agents. For negotiation with complete information, this paper provides mathematical proofs to show that an agent's optimal strategy can be computed using its opponent's reserve price (RP) and deadline. The impetus of this work is using the synergy of Bayesian learning (BL) and genetic algorithm (GA) to determine an agent's optimal strategy in negotiation (N) with incomplete information. BLGAN adopts: 1) BL and a deadline-estimation process for estimating an opponent's RP and deadline and 2) GA for generating a proposal at each negotiation round. Learning the RP and deadline of an opponent enables the GA in BLGAN to reduce the size of its search space (SP) by adaptively focusing its search on a specific region in the space of all possible proposals. SP is dynamically defined as a region around an agent's proposal P at each negotiation round. P is generated using the agent's optimal strategy determined using its estimations of its opponent's RP and deadline. Hence, the GA in BLGAN is more likely to generate proposals that are closer to the proposal generated by the optimal strategy. Using GA to search around a proposal generated by its current strategy, an agent in BLGAN compensates for possible errors in estimating its opponent's RP and deadline. Empirical results show that agents adopting BLGAN reached agreements successfully, and achieved: 1) higher utilities and better combined negotiation outcomes (CNOs) than agents that only adopt GA to generate their proposals, 2) higher utilities than agents that adopt BL to learn only RP, and 3) higher utilities and better CNOs than agents that do not learn their opponents' RPs and deadlines.

Size Matters: Developing Design Rules to Engineer Nanoparticles for Solid Tumour Targeting

NASA Astrophysics Data System (ADS)

Sykes, Edward Alexander

Nanotechnology enables the design of highly customizable platforms for producing minimally invasive and programmable strategies for cancer diagnosis and treatment. Advances in this field have demonstrated that nanoparticles can enhance specificity of anti-cancer agents, respond to tumour-specific cues, and direct the visualization of biological targets in vivo. . Nanoparticles can be synthesized within the 1 to 100 nm range to achieve different electromagnetic properties and specifically interact with biological tissues by tuning their size, shape, and surface chemistry. However, it remains unclear which physicochemical parameters are critical for delivering nanomaterials to the tumour site. With less than 5% of administered nanoparticles reaching the tumour, engineering of nanoparticles for effective delivery to solid tumours remains a critical challenge to cancer nanomedicine. A more comprehensive understanding of the interplay between the nanomaterial physicochemical properties and biological systems is necessary to enhance the efficacy of nanoparticle tumour targeting. This thesis explores how nanoparticle size and functionalization with cancer cell specific agents impact nanoparticle delivery to tumours. Furthermore, this doctoral work (i) discusses how tumour structure evolves with growth, (ii) elucidates how such changes modulate nanoparticle accumulation, and (iii) identifies how the skin serves as a significant off-target site for nanoparticle uptake. This thesis also demonstrates the utility of empirically-derived parametric models, Monte Carlo simulations, and decision matrices for mechanistically understanding and predicting the impact of nanomaterial features and tumour biology on nanoparticle fate in vivo. These topics establish key design considerations to tailor nanoparticles for enhanced tumour targeting. Collectively, the concepts presented herein form a fundamental framework for the development of personalized nanomedicine and nano-diagnostic agents in the future.

Gold Nanoparticles as a Photothermal Agent in Cancer Therapy: The Thermal Ablation Characteristic Length.

PubMed

Grosges, Thomas; Barchiesi, Dominique

2018-05-31

In cancer therapy, the thermal ablation of diseased cells by embedded nanoparticles is one of the known therapies. It is based on the absorption of the energy of the illuminating laser by nanoparticles. The resulting heating of nanoparticles kills the cell where these photothermal agents are embedded. One of the main constraints of this therapy is preserving the surrounding healthy cells. Therefore, two parameters are of interest. The first one is the thermal ablation characteristic length, which corresponds to an action distance around the nanoparticles for which the temperature exceeds the ablation threshold. This critical geometric parameter is related to the expected conservation of the body temperature in the surroundings of the diseased cell. The second parameter is the temperature that should be reached to achieve active thermal agents. The temperature depends on the power of the illuminating laser, on the size of nanoparticles and on their physical properties. The purpose of this paper is to propose behavior laws under the constraints of both the body temperature at the boundary of the cell to preserve surrounding cells and an acceptable range of temperature in the target cell. The behavior laws are deduced from the finite element method, which is able to model aggregates of nanoparticles. We deduce sensitivities to the laser power and to the particle size. We show that the tuning of the temperature elevation and of the distance of action of a single nanoparticle is not significantly affected by variations of the particle size and of the laser power. Aggregates of nanoparticles are much more efficient, but represent a potential risk to the surrounding cells. Fortunately, by tuning the laser power, the thermal ablation characteristic length can be controlled.

Effects of process parameters on properties of porous foams formed by laser-assisted melting of steel powder (AISI P21)/foaming agent (ZrH2) mixture

NASA Astrophysics Data System (ADS)

Seo, Ja-Ye; Lee, Ki-Yong; Shim, Do-Sik

2018-01-01

This paper describes the fabrication of lightweight metal foams using the directed energy deposition (DED) method. DED is a highly flexible additive manufacturing process wherein a metal powder mixed with a foaming agent is sprayed while a high-power laser is used to simultaneously melt the powder mixture into layered metal foams. In this study, a mixture of a carbon steel material (P21 powder) and a widely used foaming agent, ZrH2, is used to fabricate metal foams. The effects of various process parameters, such as the laser power, powder feed rate, powder gas flow rate, and scanning speed, on the deposition characteristics (porosity, pore size, and pore distribution) are investigated. The synthesized metal foams exhibit porosities of 10% or lower, and a mean pore area of 7 × 105 μm2. It is observed that the degree of foaming increases in proportion to the laser power to a certain extent. The results also show that the powder feed rate has the most pronounced effect on the porosity of the metal foams, while the powder gas flow rate is the most suitable parameter for adjusting the size of the pores formed within the foams. Further, the scanning speed, which determines the amounts of energy and powder delivered, has a significant effect on the height of the deposits as well as on the properties of the foams. Thus, during the DED process for fabricating metal foams, the pore size and distribution and hence the foam porosity can be tailored by varying the individual process parameters. These findings should be useful as reference data for the design of processes for fabricating porous metallic materials that meet the specific requirements for specialized parts.

Size-uniform 200 nm particles: fabrication and application to magnetofection.

PubMed

Mair, Lamar; Ford, Kris; Alam, M d Rowshon; Kole, Ryszard; Fisher, Michael; Superfine, Richard

2009-04-01

We report on the fabrication of arrays of mono- and multimetallic particles via metal evaporation onto lithographically patterned posts, as well as the magnetic force calibration and successful magnetofection of iron particles grown via this method. This work represents the first instance in which metal evaporation onto post structures was used for the formation of released, shape-defined metal particles. Also, our work represents the first use of lithographically defined particles as agents of magnetofection. Using these techniques it is possible to create particles with complex shapes and lateral dimensions as small as 40 nm. Our demonstrated compositionally flexible particles are highly size-uniform due to their photolithographically defined growth substrates, with particle dimensions along two axes fixed at 200 nm; the third axis dimension can be varied from 20 nm to 300 nm during the deposition procedure. Atomic percent of metals incorporated into the particle volume is highly tunable and particles have been synthesized with as many as four different metals. We performed magnetic force calibrations on a single particle size for iron particles using an axially magnetized NeFeB permanent magnet and comparisons are made with commercially available magnetic beads. In order to evalutate their usefulness as magnetofection agents, an antisense oligonucleotide (ODN) designed to correct the aberrant splicing of enhanced green fluorescent protein mRNA, was successfully transfected into a modified HeLa cell line. Magnetically enhanced gene delivery was accomplished in vitro using antisense ODN-laden iron particles followed by application of a field gradient. Magnetically enhanced transfection resulted in a 76% and 139% increase in fluorescence intensity when compared to Lipofectamine and antisense ODN-loaded particles delivered without magnetic treatment, respectively. To our knowledge, these experiments constitute the first use of lithographically defined particles as successful agents for magnetically enhanced transfection of an antisense oligonucleotide.

Fixed-time Insemination in Pasture-based Medium-sized Dairy Operations of Northern Germany and an Attempt to Replace GnRH by hCG.

PubMed

Marthold, D; Detterer, J; Koenig von Borstel, U; Gauly, M; Holtz, W

2016-02-01

A field study was conducted aimed at (i) evaluating the practicability of a fixed-time insemination regime for medium-sized dairy operations of north-western Germany, representative for many regions of Central Europe and (ii) substituting hCG for GnRH as ovulation-inducing agent at the end of a presynch or ovsynch protocol in an attempt to reduce the incidence of premature luteal regression. Cows of two herds synchronized by presynch and two herds synchronized by ovsynch protocol were randomly allotted to three subgroups; in one group ovulation was induced by the GnRH analog buserelin, in another by hCG, whereas a third group remained untreated. The synchronized groups were fixed-time inseminated; the untreated group bred to observed oestrus. Relative to untreated herd mates, pregnancy rate in cows subjected to a presynch protocol with buserelin as ovulation-inducing agent was 74%; for hCG it was 60%. In cows subjected to an ovsynch protocol, the corresponding relative pregnancy rates reached 138% in the case of buserelin and 95% in the case of hCG. Average service interval was shortened by 1 week in the presynch and delayed by 2 weeks in the ovsynch group. It may be concluded that fixed-time insemination of cows synchronized via ovsynch protocol with buserelin as ovulation-inducing agent is practicable and may help improve efficiency and reduce the work load involved with herd management in medium-sized dairy operations. The substitution of hCG for buserelin was found to be not advisable. © 2015 Blackwell Verlag GmbH.

PLGA/PFC particles loaded with gold nanoparticles as dual contrast agents for photoacoustic and ultrasound imaging

NASA Astrophysics Data System (ADS)

Wang, Yan J.; Strohm, Eric M.; Sun, Yang; Niu, Chengcheng; Zheng, Yuanyi; Wang, Zhigang; Kolios, Michael C.

2014-03-01

Phase-change contrast agents consisting of a perfluorocarbon (PFC) liquid core stabilized by a lipid, protein, or polymer shell have been proposed for a variety of clinical applications. Previous work has demonstrated that vaporization can be induced by laser irradiation through optical absorbers incorporated inside the droplet. In this study, Poly-lactide-coglycolic acid (PLGA) particles loaded with PFC liquid and silica-coated gold nanoparticles (GNPs) were developed and characterized using photoacoustic (PA) methods. Microsized PLGA particles were loaded with PFC liquid and GNPs (14, 35, 55nm each with a 20nm silica shell) using a double emulsion method. The PA signal intensity and optical vaporization threshold were investigated using a 375 MHz transducer and a focused 532-nm laser (up to 450-nJ per pulse). The laser-induced vaporization threshold energy decreased with increasing GNP size. The vaporization threshold was 850, 690 and 420 mJ/cm2 for 5μm-sized PLGA particles loaded with 14, 35 and 55 nm GNPs, respectively. The PA signal intensity increased as the laser fluence increased prior to the vaporization event. This trend was observed for all particles sizes. PLGA particles were then incubated with MDA-MB-231 breast cancer cells for 6 hours to investigate passive targeting, and the vaporization of the PLGA particles that were internalized within cells. The PLGA particles passively internalized by MDA cells were visualized via confocal fluorescence imaging. Upon PLGA particle vaporization, bubbles formed inside the cells resulting in cell destruction. This work demonstrates that GNPs-loaded PLGA/PFC particles have potential as PA theranostic agents in PA imaging and optically-triggered drug delivery systems.

A sustained release formulation of chitosan modified PLCL:poloxamer blend nanoparticles loaded with optical agent for animal imaging

NASA Astrophysics Data System (ADS)

Ranjan, Amalendu P.; Zeglam, Karim; Mukerjee, Anindita; Thamake, Sanjay; Vishwanatha, Jamboor K.

2011-07-01

The objective of this study was to develop optical imaging agent loaded biodegradable nanoparticles with indocynanine green (ICG) using chitosan modified poly(L-lactide-co-epsilon-caprolactone) (PLCL):poloxamer (Pluronic F68) blended polymer. Nanoparticles were formulated with an emulsification solvent diffusion technique using PLCL and poloxamer as blend-polymers. Polyvinyl alcohol (PVA) and chitosan were used as stabilizers. The particle size, shape and zeta potential of the formulated nanoparticles and the release kinetics of ICG from these nanoparticles were determined. Further, biodistribution of these nanoparticles was studied in mice at various time points until 24 h following intravenous administration, using a non-invasive imaging system. The average particle size of the nanoparticles was found to be 146 ± 3.7 to 260 ± 4.5 nm. The zeta potential progressively increased from - 41.6 to + 25.3 mV with increasing amounts of chitosan. Particle size and shape of the nanoparticles were studied using transmission electron microscopy (TEM) which revealed the particles to be smooth and spherical in shape. These nanoparticles were efficiently delivered to the cytoplasm of the cells, as observed in prostate and breast cancer cells using confocal laser scanning microscopy. In vitro release studies indicated sustained release of ICG from the nanoparticles over a period of seven days. Nanoparticle distribution results in mice showing improved uptake and accumulation with chitosan modified nanoparticles in various organs and slower clearance at different time points over a 24 h period as compared to unmodified nanoparticles. The successful formulation of such cationically modified nanoparticles for encapsulating optical agents may lead to a potential deep tissue imaging technique for tumor detection, diagnosis and therapy.

Advances in Drug Delivery Systems, from 0 to 3D superstructures.

PubMed

Radulescu, Marius; Popescu, Simona; Ficai, Denisa; Sonmez, Maria; Oprea, Ovidiu; Spoiala, Angela; Ficai, Anton; Andronescu, Ecaterina

2018-02-19

Nanomedicine is currently exploited for manufacturing therapeutic DDS and treatments protocols for various diseases and disorders. To obtain DDS, different types of materials are used, from organic to inorganic, polar to non-polar, micro to nanomaterials from 0D to 3D structured materials, respectively. Many of these materials were extensively studied and reviewed in the literature. The objectives of this review is to make a clear overview on drug delivery systems depending several aspects related to delivery mechanisms, the type of supports, the active agents ant the potential applications in the prevention or treatment of various diseases. Following aspects are extensively debated: synthesis issues, characteristics and potential uses of 0, 1, 2 and 3D drug delivery systems according to their nature and applications. These systems can be can be tailored according to the delivery mechanism (0-3D delivery) as well as by using more active agents, with more therapeutic activity or same activity but with different mechanisms of action. The size and morphology of the drug delivery system is essential, especially when talking about the internalization into the tumor cells while the mobility is especially dependent on the size. The influence of the nature of the supports and their polarity was extensively studied during the last decades, as well as the importance of the porosity and pore size, but only limited papers are devoted to the holistic analysis of the dimensionality of the support and the ways of delivering the active agents. This review is devoted to a holistic insight into the drug delivery systems, from a new, only marginally studied point of view, meaning the dimensionality of the drug delivery systems and the characteristics of the delivery. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Fundamental Study on the Development of Structural Lightweight Concrete by Using Normal Coarse Aggregate and Foaming Agent

PubMed Central

Lee, Han-Seung; Ismail, Mohamed A.; Woo, Young-Je; Min, Tae-Beom; Choi, Hyun-Kook

2014-01-01

Structural lightweight concrete (SLWC) has superior properties that allow the optimization of super tall structure systems for the process of design. Because of the limited supply of lightweight aggregates in Korea, the development of structural lightweight concrete without lightweight aggregates is needed. The physical and mechanical properties of specimens that were cast using normal coarse aggregates and different mixing ratios of foaming agent to evaluate the possibility of creating structural lightweight concrete were investigated. The results show that the density of SLWC decreases as the dosage of foaming agent increases up to a dosage of 0.6%, as observed by SEM. It was also observed that the foaming agent induced well separated pores, and that the size of the pores ranged from 50 to 100 μm. Based on the porosity of concrete specimens with foaming agent, compressive strength values of structural lightweight foam concrete (SLWFC) were obtained. It was also found that the estimated values from proposed equations for compressive strength and modulus of elasticity of SLWFC, and values obtained by actual measurements were in good agreement. Thus, this study confirms that new structural lightweight concrete using normal coarse aggregates and foaming agent can be developed successfully. PMID:28788691

Comparison of transcutaneous contrast-enhanced ultrasound-guided injected hemostatic agents with traditional surgery treatment for liver, spleen and kidney trauma: a retrospective study.

PubMed

Wang, Dong; Lv, Faqin; Luo, Yukun; An, Lichun; Li, Junlai; Xie, Xia; Tian, Jiangke; Zhao, Weiyan; Tang, Jie

2012-10-01

There is lack of studies on the effectiveness of transcutaneous contrast-enhanced ultrasound-guided injections of hemostatic agents for liver. spleen and kidney trauma. We compared treatment by hemostatic agents to surgical treatment in a retrospective interventional human study. The study enrolled a total of 135 subjects from emergency unit of the Chinese People's Liberation Army General Hospital in Beijing. Within the cohort, 62 patients received contrast enhanced ultrasound-guided injection of hemostatic agents and the rest received surgical treatments. The injury severity score was lower in the hemostatic agent treatment group than surgical treatment group (p<0.05), but Glasgow coma scale scores did not reach statistical significance. The patients in the surgical treatment group had significantly higher hospital fees than those in the hemostatic treatment group (p<0.05), although the length of hospitalization did not significantly differ between two groups. Safety outcome variables pre- and post-treatment remained within normal limits in both groups. Hemostatic agents were more cost-effective than surgery to treat patients with liver, spleen and kidney trauma. However, given the limited sample size, subsequent studies drawing upon larger populations from multiple medical centers are necessary for follow-up.

Role of CaCO3 and Charcoal Application on Organic Matter Retention in Silt-sized Aggregates

NASA Astrophysics Data System (ADS)

Berhe, A. A.; Kaiser, M.; Ghezzehei, T.; Myrold, D.; Kleber, M.

2011-12-01

The effectiveness of charcoal and calcium carbonate (CaCO3) applications to improve soil conditions has been well documented. However, their influence on the formation of silt-sized aggregates and the amount and protection of associated organic matter (OM) against microbial decomposition under differing soil mineralogical and microbiological conditions are still unknown. For sustainable management of agricultural soils, silt-sized aggregates (2-50 μm) are of particularly large importance because they store up to 60% of soil organic carbon and with mean residence times between 70 and 400 years. The objectives of this study are i) to analyze the ability of soil amendments (CaCO3, charcoal and their combined application) to increase the amount of silt-sized aggregates and associated organic matter, ii) vary soil mineral conditions to establish relevant boundary conditions for amendment-induced aggregation process, iii) to determine how amendment-induced changes in formation of silt-sized aggregates relate to microbial decomposition of OM. We set up artificial high reactive (clay: 40%, sand: 57%, SOM: 3%) and low reactive soils (clay: 10%, sand: 89%, SOM: 1%) and mixed them with charcoal (1%) and/or CaCO3 (0.2%). The samples were adjusted to a water potential of 0.3 bar using a nutrient solution and sub samples were incubated with microbial innoculum. After four months, silt-sized aggregates are separated by a combination of wet-sieving and sedimentation. We hypothesize that the relative increase in amount of silt-sized aggregates and associated OM is larger for less reactive soils than for high reactive soils because of a relative larger increase in binding agents by addition of charcoal and/or CaCO3 in less reactive soils. The effect of charcoal and/or CaCO3 application on the amount of silt-sized aggregates and associated OM is expected to increases with an increase in microbial activity. Between different treatments, we expect the incubated 'charcoal+CaCO3' combination to have the largest effect on silt-size scale aggregation processes because the amount of microbial derived cementing agents, charcoal derived functional groups containing OM, and Ca2+ ions are enhanced at the same time.

Pilot testing of a burn prevention teaching tool for Amish children.

PubMed

Rieman, Mary T; Kagan, Richard J

2012-01-01

Burn prevention education for Amish children is warranted as there are unique risks associated with the Amish lifestyle. Specific educational opportunities are related to scalds, ignition of clothing, and ignition of highly flammable materials. A culturally sensitive burn prevention teaching tool, consisting of a magnetic storyboard, burn safety curriculum, and tests, was developed with the cooperation of one Old Order Amish community. The purpose of this study was to test the effectiveness of the tool in an Amish school. The teacher obtained parental permission and informed assent for the participation of the children. Pretesting was completed before the lessons began. The teacher told stories and arranged the magnets on the storyboard to show burn hazards involving lighters, stoves, kerosene heaters, gasoline-powered engines, and hot liquids used for canning, butchering, mopping, washing clothes, and making lye soap. The children were challenged to rearrange the pieces for a safer situation. Posttesting was performed 2 months after the pretest. Twenty-seven students (grades 1-8) participated. Tests were scored as a percentage of the 33 items answered correctly. The mean pretest score was 62 and the mean posttest score was 83. Statistical analysis using paired t-test demonstrated a highly significant improvement in test scores (P < .0001), with a power of more than 99%. This pilot study demonstrated that the burn prevention teaching tool was effective for improving knowledge in one classroom of Amish children. These results support expanded use and testing of this tool in other Amish schools.

Development of a burn prevention teaching tool for Amish children.

PubMed

Rieman, Mary T; Kagan, Richard J

2012-01-01

Although there are inherent risks for burn injury associated with the Amish lifestyle, burn prevention is not taught in Amish schools. The purpose of this study was to develop a burn prevention teaching tool for Amish children. An anonymous parental survey was designed to explore the content and acceptability of a teaching tool within an Old Order Amish community. After institutional review board approval, the Amish teacher distributed surveys to 16 families of the 30 children attending the one-room school. Fourteen (88%) of the families responded to identify these burn risks in and around their homes, barns, and shops: lighters, wood and coal stoves, kerosene heaters, gasoline-powered engines, and hot liquids used for canning, butchering, mopping, washing clothes, and making lye soap. All respondents were in favor of teaching familiar safety precautions, fire escape plans, burn first aid, and emergency care to the children. There was some minor objection to more modern devices such as bath tub thermometers (25%), fire extinguishers (19%), and smoke detectors (6%). The teacher was interested in a magnetic teaching board depicting Amish children and typical objects in their home environment. Movable pieces could afford the opportunity to identify hazards and to rearrange them for a safer situation. This survey served to introduce burn prevention to one Amish community and to develop an appropriate teaching tool for the school. It is anticipated that community participation would support its acceptance and eventual utilization within this tenaciously traditional culture.

Chemically engineered persistent luminescence nanoprobes for bioimaging

PubMed Central

Lécuyer, Thomas; Teston, Eliott; Ramirez-Garcia, Gonzalo; Maldiney, Thomas; Viana, Bruno; Seguin, Johanne; Mignet, Nathalie; Scherman, Daniel; Richard, Cyrille

2016-01-01

Imaging nanoprobes are a group of nanosized agents developed for providing improved contrast for bioimaging. Among various imaging probes, optical sensors capable of following biological events or progresses at the cellular and molecular levels are actually actively developed for early detection, accurate diagnosis, and monitoring of the treatment of diseases. The optical activities of nanoprobes can be tuned on demand by chemists by engineering their composition, size and surface nature. This review will focus on researches devoted to the conception of nanoprobes with particular optical properties, called persistent luminescence, and their use as new powerful bioimaging agents in preclinical assays. PMID:27877248

Minority game with local interactions due to the presence of herding behavior

NASA Astrophysics Data System (ADS)

Cajueiro, Daniel Oliveira; de Camargo, Reinaldo Soares

2006-07-01

In this Letter we introduce a framework to study local interactions due to the presence of herding behavior in a minority game. The idea behind this approach is to consider that some of the agents who play the game imitate some of their neighbors who are believed to be more informed than themselves. We show that under herding behavior the cooperation between the agents is less efficient than the one which arises in the standard minority game and that the curve volatility of the attendance size as a function of the memory may be a monotone decreasing curve.

Fire extinguishing agents for oxygen-enriched atmospheres

NASA Astrophysics Data System (ADS)

Plugge, M. A.; Wilson, C. W.; Zallen, D. M.; Walker, J. L.

1985-12-01

Fire-suppression agent requirements for extinguishing fires in oxygen-enriched atmospheres were determined employing small-, medium-, large-, and full-scale test apparatuses. The small- and medium-scale tests showed that a doubling of the oxygen concentration required five times more HALON for extinguishment. For fires of similar size and intensity, the effect of oxygen enrichment of the diluent volume in the HC-131A was not as grate as in the smaller compartments of the B-52 which presented a higher damage scenario. The full-scale tests showed that damage to the airframe was as important a factor in extinguishment as oxygen enrichment.

Real-Time Optical Detection of Single Nanoparticles and Viruses Using Heterodyne Interferometry

NASA Astrophysics Data System (ADS)

Mitra, Anirban; Novotny, Lukas

Nanoparticles play a significant role in various fields such as biomedical imaging and diagnostics [1-4], process control in semiconductor manufacturing [5], explosives [6], environmental monitoring and climate change [7, 8], and various other fields. Inhalation of ultrafine particulates in air has been shown to have adverse effects, such as inflammation of lungs or pulmonary and cardiovascular diseases [9, 10]. Nano-sized biological agents and pathogens such as viruses are known to be responsible for a wide variety of human diseases such as flu, AIDS and herpes, and have been used as biowarfare agents [11, 12].

Word of Mouth : An Agent-based Approach to Predictability of Stock Prices

NASA Astrophysics Data System (ADS)

Shimokawa, Tetsuya; Misawa, Tadanobu; Watanabe, Kyoko

This paper addresses how communication processes among investors affect stock prices formation, especially emerging predictability of stock prices, in financial markets. An agent based model, called the word of mouth model, is introduced for analyzing the problem. This model provides a simple, but sufficiently versatile, description of informational diffusion process and is successful in making lucidly explanation for the predictability of small sized stocks, which is a stylized fact in financial markets but difficult to resolve by traditional models. Our model also provides a rigorous examination of the under reaction hypothesis to informational shocks.

Gd-Si Oxide Nanoparticles as Contrast Agents in Magnetic Resonance Imaging

PubMed Central

Cabrera-García, Alejandro; Vidal-Moya, Alejandro; Bernabeu, Ángela; Pacheco-Torres, Jesús; Checa-Chavarria, Elisa; Fernández, Eduardo; Botella, Pablo

2016-01-01

We describe the synthesis, characterization and application as contrast agents in magnetic resonance imaging of a novel type of magnetic nanoparticle based on Gd-Si oxide, which presents high Gd3+ atom density. For this purpose, we have used a Prussian Blue analogue as the sacrificial template by reacting with soluble silicate, obtaining particles with nanorod morphology and of small size (75 nm). These nanoparticles present good biocompatibility and higher longitudinal and transversal relaxivity values than commercial Gd3+ solutions, which significantly improves the sensitivity of in vivo magnetic resonance images. PMID:28335240

27 CFR 555.122 - Records maintained by licensed importers.

Code of Federal Regulations, 2011 CFR

2011-04-01

... quantity units, such as pounds of explosives, number of detonators, number of display fireworks, etc.). (5) Description (dynamite (dyn), blasting agents (ba), detonators (det), display fireworks (df), etc.) and size... identification. (4) Quantity (applicable quantity units, such as pounds of explosives, number of detonators...

27 CFR 555.122 - Records maintained by licensed importers.

Code of Federal Regulations, 2010 CFR

2010-04-01

... quantity units, such as pounds of explosives, number of detonators, number of display fireworks, etc.). (5) Description (dynamite (dyn), blasting agents (ba), detonators (det), display fireworks (df), etc.) and size... identification. (4) Quantity (applicable quantity units, such as pounds of explosives, number of detonators...

Glutathione promoted expeditious green synthesis of silver nanoparticles in water using microwaves

EPA Science Inventory

Silver nanoparticles with size range 5-10 nm has been synthesized under microwave irradiation conditions using gluathione, an absolutely benign antioxidant that serves as the reducing as well as capping agent in aqueous medium. This rapid protocol yields the nanoparticles within ...

Biocompatible Nanocomplexes for Molecular Targeted MRI Contrast Agent

NASA Astrophysics Data System (ADS)

Chen, Zhijin; Yu, Dexin; Wang, Shaojie; Zhang, Na; Ma, Chunhong; Lu, Zaijun

2009-07-01

Accurate diagnosis in early stage is vital for the treatment of Hepatocellular carcinoma. The aim of this study was to investigate the potential of poly lactic acid-polyethylene glycol/gadolinium-diethylenetriamine-pentaacetic acid (PLA-PEG/Gd-DTPA) nanocomplexes using as biocompatible molecular magnetic resonance imaging (MRI) contrast agent. The PLA-PEG/Gd-DTPA nanocomplexes were obtained using self-assembly nanotechnology by incubation of PLA-PEG nanoparticles and the commercial contrast agent, Gd-DTPA. The physicochemical properties of nanocomplexes were measured by atomic force microscopy and photon correlation spectroscopy. The T1-weighted MR images of the nanocomplexes were obtained in a 3.0 T clinical MR imager. The stability study was carried out in human plasma and the distribution in vivo was investigated in rats. The mean size of the PLA-PEG/Gd-DTPA nanocomplexes was 187.9 ± 2.30 nm, and the polydispersity index was 0.108, and the zeta potential was -12.36 ± 3.58 mV. The results of MRI test confirmed that the PLA-PEG/Gd-DTPA nanocomplexes possessed the ability of MRI, and the direct correlation between the MRI imaging intensities and the nano-complex concentrations was observed ( r = 0.987). The signal intensity was still stable within 2 h after incubation of the nanocomplexes in human plasma. The nanocomplexes gave much better image contrast effects and longer stagnation time than that of commercial contrast agent in rat liver. A dose of 0.04 mmol of gadolinium per kilogram of body weight was sufficient to increase the MRI imaging intensities in rat livers by five-fold compared with the commercial Gd-DTPA. PLA-PEG/Gd-DTPA nanocomplexes could be prepared easily with small particle sizes. The nanocomplexes had high plasma stability, better image contrast effect, and liver targeting property. These results indicated that the PLA-PEG/Gd-DTPA nanocomplexes might be potential as molecular targeted imaging contrast agent.

A Financial Market Model Incorporating Herd Behaviour

PubMed Central

2016-01-01

Herd behaviour in financial markets is a recurring phenomenon that exacerbates asset price volatility, and is considered a possible contributor to market fragility. While numerous studies investigate herd behaviour in financial markets, it is often considered without reference to the pricing of financial instruments or other market dynamics. Here, a trader interaction model based upon informational cascades in the presence of information thresholds is used to construct a new model of asset price returns that allows for both quiescent and herd-like regimes. Agent interaction is modelled using a stochastic pulse-coupled network, parametrised by information thresholds and a network coupling probability. Agents may possess either one or two information thresholds that, in each case, determine the number of distinct states an agent may occupy before trading takes place. In the case where agents possess two thresholds (labelled as the finite state-space model, corresponding to agents’ accumulating information over a bounded state-space), and where coupling strength is maximal, an asymptotic expression for the cascade-size probability is derived and shown to follow a power law when a critical value of network coupling probability is attained. For a range of model parameters, a mixture of negative binomial distributions is used to approximate the cascade-size distribution. This approximation is subsequently used to express the volatility of model price returns in terms of the model parameter which controls the network coupling probability. In the case where agents possess a single pulse-coupling threshold (labelled as the semi-infinite state-space model corresponding to agents’ accumulating information over an unbounded state-space), numerical evidence is presented that demonstrates volatility clustering and long-memory patterns in the volatility of asset returns. Finally, output from the model is compared to both the distribution of historical stock returns and the market price of an equity index option. PMID:27007236

MRI contrast agent for targeting glioma: interleukin-13 labeled liposome encapsulating gadolinium-DTPA.

PubMed

Liu, Xiaoli; Madhankumar, Achuthamangalam B; Miller, Patti A; Duck, Kari A; Hafenstein, Susan; Rizk, Elias; Slagle-Webb, Becky; Sheehan, Jonas M; Connor, James R; Yang, Qing X

2016-05-01

Detection of glioma with MRI contrast agent is limited to cases in which the blood-brain barrier (BBB) is compromised as contrast agents cannot cross the BBB. Thus, an early-stage infiltrating tumor is not detectable. Interleukin-13 receptor alpha 2 (IL-13Rα2), which has been shown to be overexpressed in glioma, can be used as a target moiety. We hypothesized that liposomes conjugated with IL-13 and encapsulating MRI contrast agent are capable of passing through an intact BBB and producing MRI contrast with greater sensitivity. The targeted MRI contrast agent was created by encapsulating Magnevist (Gd-DTPA) into liposomes conjugated with IL-13 and characterized by particle size distribution, cytotoxicity, and MRI relaxivity. MR image intensity was evaluated in the brain in normal mice post injection of Gd-DTPA and IL-13-liposome-Gd-DTPA one day apart. The specificity for glioma detection by IL-13-liposome-Gd-DTPA was demonstrated in an intracranial glioma mouse model and validated histologically. The average size of IL-13-liposome-Gd-DTPA was 137 ± 43 nm with relaxivity of 4.0 ± 0.4 L/mmole-s at 7 Tesla. No significant cytotoxicity was observed with MTS assay and serum chemistry in mice. The MRI signal intensity was enhanced up to 15% post injection of IL-13-liposome-Gd-DTPA in normal brain tissue following a similar time course as that for the pituitary gland outside of the BBB. MRI enhanced by IL-13-liposome-Gd-DTPA detected small tumor masses in addition to those seen with Magnevist-enhanced MRI. IL-13-liposome-Gd-DTPA is able to pass through the uncompromised BBB and detect an early stage glioma that cannot be seen with conventional contrast-enhanced MRI. © The Author(s) 2015. Published by Oxford University Press on behalf of the Society for Neuro-Oncology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Dose Reduction Study in Vaginal Balloon Packing Filled With Contrast for HDR Brachytherapy Treatment;HDR; Uterine cervix cancer; Vaginal balloon packing; Contrast; Monte Carlo

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saini, Amarjit S.; Zhang, Geoffrey G., E-mail: geoffrey.zhang@moffitt.org; Finkelstein, Steven E.

2011-07-15

Purpose: Vaginal balloon packing is a means to displace organs at risk during high dose rate brachytherapy of the uterine cervix. We tested the hypothesis that contrast-filled vaginal balloon packing reduces radiation dose to organs at risk, such as the bladder and rectum, in comparison to water- or air-filled balloons. Methods and Materials: In a phantom study, semispherical vaginal packing balloons were filled with air, saline solution, and contrast agents. A high dose rate iridium-192 source was placed on the anterior surface of the balloon, and the diode detector was placed on the posterior surface. Dose ratios were taken withmore » each material in the balloon. Monte Carlo (MC) simulations, by use of the MC computer program DOSXYZnrc, were performed to study dose reduction vs. balloon size and contrast material, including commercially available iodine- and gadolinium-based contrast agents. Results: Measured dose ratios on the phantom with the balloon radius of 3.4 cm were 0.922 {+-} 0.002 for contrast/saline solution and 0.808 {+-} 0.001 for contrast/air. The corresponding ratios by MC simulations were 0.895 {+-} 0.010 and 0.781 {+-} 0.010. The iodine concentration in the contrast was 23.3% by weight. The dose reduction of contrast-filled balloon ranges from 6% to 15% compared with water-filled balloon and 11% to 26% compared with air-filled balloon, with a balloon size range between 1.4 and 3.8 cm, and iodine concentration in contrast of 24.9%. The dose reduction was proportional to the contrast agent concentration. The gadolinium-based contrast agents showed less dose reduction because of much lower concentrations in their solutions. Conclusions: The dose to the posterior wall of the bladder and the anterior wall of the rectum can be reduced if the vaginal balloon is filled with contrast agent in comparison to vaginal balloons filled with saline solution or air.« less

Application of a recyclable plastic bulking agent for sewage sludge composting.

PubMed

Zhou, Hai-Bin; Ma, Chuang; Gao, Ding; Chen, Tong-Bin; Zheng, Guo-Di; Chen, Jun; Pan, Tian-Hao

2014-01-01

A recyclable plastic bulking agent (RPBA) that can be screened and reused was developed to improve sludge composting and to reduce costs. Two RPBAs were developed: RPBA35 (35 mm in diameter) and RPBA50 (50mm in diameter). The objective was to study the influence of size and quantity of RPBA on temperature, oxygen content, water removal during sludge composting, and phytotoxicity of the compost. RPBAs of both sizes improved the temperature, oxygen supply, and water removal compared with the treatment with no RPBA, and obtained phytotoxic-free compost. RPBA50 more effectively removed water than RPBA35. Oxygen diffusion rate in the composting pile containing RPBA50 was higher than in the treatment with no RPBA. When the RPBA50: sludge mixture ratio was above 1:1.5, the period over which the temperature exceeded 55 °C was insufficient to meet the harmless treatment requirement. The water evaporation rate was highest at a ratio of 1:2. Copyright © 2013. Published by Elsevier Ltd.

Visible-light-responsive ZnCuO nanoparticles: benign photodynamic killers of infectious protozoans

PubMed Central

Nadhman, Akhtar; Nazir, Samina; Khan, Malik Ihsanullah; Ayub, Attiya; Muhammad, Bakhtiar; Khan, Momin; Shams, Dilawar Farhan; Yasinzai, Masoom

2015-01-01

Human beings suffer from several infectious agents such as viruses, bacteria, and protozoans. Recently, there has been a great interest in developing biocompatible nanostructures to deal with infectious agents. This study investigated benign ZnCuO nanostructures that were visible-light-responsive due to the resident copper in the lattice. The nanostructures were synthesized through a size-controlled hot-injection process, which was adaptable to the surface ligation processes. The nanostructures were then characterized through transmission electron microscopy, X-ray diffraction, diffused reflectance spectroscopy, Rutherford backscattering, and photoluminescence analysis to measure crystallite nature, size, luminescence, composition, and band-gap analyses. Antiprotozoal efficiency of the current nanoparticles revealed the photodynamic killing of Leishmania protozoan, thus acting as efficient metal-based photosensitizers. The crystalline nanoparticles showed good biocompatibility when tested for macrophage toxicity and in hemolysis assays. The study opens a wide avenue for using toxic material in resident nontoxic forms as an effective antiprotozoal treatment. PMID:26604755

Synthesis of dextrin-stabilized colloidal silver nanoparticles and their application as modifiers of cement mortar.

PubMed

Konował, Emilia; Sybis, Marta; Modrzejewska-Sikorska, Anna; Milczarek, Grzegorz

2017-11-01

Various commercial dextrins were used as reducing and stabilizing agents for a novel one-step synthesis of silver nanoparticles from ammonia complexes of silver ions. As a result, stable colloids of silver were formed during the reaction with the particle size being the function of the dextrin type. The obtained colloids were characterized by UV-vis spectrophotometry, size distribution (using Non-Invasive Backscatter optics) and transmission electron microscopy (TEM). The achieved results clearly indicate the possibility of low-cost production of large quantities of colloidal silver nanoparticles using materials derived from renewable sources. The resulting silver colloids can be used for different purposes, e.g. as bactericidal agents. Combination of the aforementioned properties of nanosilver particles with plasticizing properties of dextrin enables to obtain cement mortars with increased workability and enhanced compressive strength. Moreover, the obtained material is also characterized by increased immunity to adverse impact of microorganisms. Copyright © 2017 Elsevier B.V. All rights reserved.

Voltammetric detection of biological molecules using chopped carbon fiber.

PubMed

Sugawara, Kazuharu; Yugami, Asako; Kojima, Akira

2010-01-01

Voltammetric detection of biological molecules was carried out using chopped carbon fibers produced from carbon fiber reinforced plastics that are biocompatible and inexpensive. Because chopped carbon fibers normally are covered with a sizing agent, they are difficult to use as an electrode. However, when the surface of a chopped carbon fiber was treated with ethanol and hydrochloric acid, it became conductive. To evaluate the functioning of chopped carbon fibers, voltammetric measurements of [Fe(CN)(6)](3-) were carried out. Redoxes of FAD, ascorbic acid and NADH as biomolecules were recorded using cyclic voltammetry. The sizing agents used to bundle the fibers were epoxy, polyamide and polyurethane resins. The peak currents were the greatest when using the chopped carbon fibers that were created with epoxy resins. When the electrode response of the chopped carbon fibers was compared with that of a glassy carbon electrode, the peak currents and the reversibility of the electrode reaction were sufficient. Therefore, the chopped carbon fibers will be useful as disposable electrodes for the sensing of biomolecules.

Self-healing of low-velocity impact damage in glass fabric/epoxy composites using an epoxy-mercaptan healing agent

NASA Astrophysics Data System (ADS)

Chao Yuan, Yan; Ye, Yueping; Zhi Rong, Min; Chen, Haibin; Wu, Jingshen; Qiu Zhang, Ming; Qin, Shi Xiang; Yang, Gui Cheng

2011-01-01

Self-healing woven glass fabric-reinforced epoxy composite laminates were made by embedding epoxy- and mercaptan-loaded microcapsules. After being subjected to low-velocity impact, the laminates were able to heal the damage in an autonomic way at room temperature. The healing-induced reduction in the damaged areas was visualized using a scanning acoustic microscope. The rate of damage area reduction, which is closely related to the effect of crack rehabilitation and mechanical recovery, is a function of impact energy, content and size of the healing microcapsules. Minor damage, such as microcracks in the matrix, can be completely repaired by the healing system without manual intervention, including external pressure. Microcapsules with larger size and/or higher concentration are propitious for delivering more healing agent to cracked portions, while imposition of lateral pressure on damaged specimens forces the separated faces to approach each other. Both can improve the rate of damage area reduction in the case of severe damage.

Investigation of optical properties and the photocatalytic activity of synthesized YbYO4 nanoparticles and YbVO4/NiWO4 nanocomposites by polymeric capping agents

NASA Astrophysics Data System (ADS)

Pourmasoud, Saeid; Sobhani-Nasab, Ali; Behpour, Mohsen; Rahimi-Nasrabadi, Mehdi; Ahmadi, Farhad

2018-04-01

YbVO4 nanoparticles YbVO4/NiWO4 nanocomposites were synthesized by simple and new method. The effect of various polymeric capping agents such as Tween 80, Tween 20 and PEG on the shape and size of YbVO4/NiWO4 nanocomposites were investigated. YbVO4/NiWO4 nanocomposites were analyzed through some techniques including, X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy, vibrating sample magnetometer (VSM), thermogravimetry differential thermal analysis (TG-DTA), transmission electron microscopy (TEM), field emission electron microscopy (FESEM), ultraviolet-visible spectroscopy (UV-Vis), and energy-dispersive X-ray spectroscopy (EDX). This attempt is the first study on the photocatalytic performance of the YbVO4/NiWO4 nanocomposites in various conditions such as size of particles and kind of dyes (rhodamine B (Rh B), methylene blue (MB), methyl orange (MO), and phenol red (Ph R)), under visible light.

Azomethine based nano-chemicals: Development, in vitro and in vivo fungicidal evaluation against Sclerotium rolfsii, Rhizoctonia bataticola and Rhizoctonia solani.

PubMed

Mondal, Prithusayak; Kumar, Rajesh; Gogoi, Robin

2017-02-01

Fungal diseases posing a severe threat to the production of pulses, a major protein source, necessitates the need of new highly efficient antifungal agents. The present study was aimed to develop azomethine based nano-fungicides for protecting the crop from fungal pathogens and subsequent yield losses. The protocol for the formation of nano-azomethines was generated and standardized. Technically pure azomethines were transformed into their nano-forms exploiting polyethylene glycol as the surface stabilizer. Characterization was performed by optical (imaging) probe (Zetasizer) and electron probe (TEM) characterization techniques. The mean particle sizes of all nano-fungicides were below 100nm. In vitro fungicidal potential of nano-chemicals was increased by 2 times in comparison to that of conventional sized azomethines against pathogenic fungi, namely, Rhizoctonia solani, Rhizoctonia bataticola and Sclerotium rolfsii. The performance of nano-chemicals in pot experiment study was also superior to conventional ones as antifungal agent. Copyright © 2016 Elsevier Inc. All rights reserved.