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1

Borax Production from Borax Slime, an Industrial Waste  

Microsoft Academic Search

Borax slime is formed during the production of borax from tincal, which is an important borate ore. It is a liquid containing the suspanded solid particles at high levels and is formed under the rich-in-borax solution in the reactor. This waste is discharged into the Marmara Sea and so causes environmental problems in Bandirma Golf. In this work, Borax production

Recep Boncukcuo?lu; M. Muhtar Kocakkerim; Mahir Alkan

1998-01-01

2

Molecular Structure of Borax  

NSDL National Science Digital Library

Borax was discovered 4000 years ago. It was first brought to Europe from Kashmir and Tibet. It is deposited by the evaporation of alkaline lakes, and today is mined in California, Nevada, and Tibet. The hydrated mineral is colorless and becomes chalky white during dehydration. It is water soluble, has a sweet alkaline taste, and is brittle. Borax has no toxic fumes; it is environmentally safe and should not be ingested. This chemical is an important source of boron containing compounds such as tincalconite and kernite, and is industrially important in the manufacturing of ceramics, paint, glass, and coated paper. It is also utilized as a disinfectant, insect repellent, water softener, and a detergent. The most common detergent brand is 20 Mule Team Borax.

2003-03-27

3

Dry processing of borax by calcination as an alternative to wet methods  

Microsoft Academic Search

Beneficiation of borax in the Kirka concentrator, Turkey is presently accomplished by wet processing techniques involving scrubbing of the minus 6 mm borax to remove the undesirable clayey impurities followed by cyclone and spiral classification of the fine fraction. The fine borax tailings assaying as high as 20% B2O3 mostly below 0.2 mm is disposed into the environment. Over a

T Batar; B Kahraman; E Cirit; M. S Celik

1998-01-01

4

Thermal decomposition of borax  

Microsoft Academic Search

Thermal decomposition of borax has been researched by thermal, XRD and FTIR methods as well as SEM microscopy. Study have\\u000a revealed that it proceeds according to the mechanism of internal reactions in the structure of the precursor as a medium.\\u000a \\u000a The following stages of the process have been distinguished: (1) dehydration, (2) internal structure reconstitution—formation\\u000a of tincalconite, (3) amorphization of

I. Waclawska

1995-01-01

5

Respiratory effects of borax dust  

Microsoft Academic Search

The relation of respiratory symptoms, pulmonary function, and abnormalities of chest radiographs to estimated exposures of borax dust has been investigated in a cross sectional study of 629 actively employed borax workers. Ninety three per cent of the eligible workers participated in the study and exposures ranged from 1.1 mg\\/m3 to 14.6 mg\\/m3. Symptoms of acute respiratory irritation such as

D H Garabrant; L Bernstein; J M Peters; T J Smith; W E Wright

1985-01-01

6

Dehydration Behaviour of Borax Pentahydrate to Anhydrous Borax by MultiStage Heating in a Fluidized  

Microsoft Academic Search

In order to optimize the anhydrous borax process in a fluidized bed calcinator, it is absolutely necessary to study the dehydration behaviour of borax pentahydrate. It was found that the basic feature of the dehydration of borax pentahydrate to anhydrous borax is concerned with the conditions employed. The bulk density and sodium borate content of the end product were determined

Omer S AH; A. Nusret BULUTCU

7

Effect of borax on hydration and hardening properties of magnesium and pottassium phosphate cement pastes  

Microsoft Academic Search

Magnesium and potassium phosphate cement (MKPC) sample were prepared by mixing dead burnt MgO powder, potassium phosphate\\u000a and different dosages of retarder borax to investigate the effect of borax on its hydration and hardening characteristics.\\u000a The pH value, fluidity, hydration temperature and strength development of MKPC paste were investigated, and the mineralogical\\u000a composition and microstructural morphology of its hydration products

Jianming Yang; Chunxiang Qian

2010-01-01

8

Respiratory effects of borax dust.  

PubMed Central

The relation of respiratory symptoms, pulmonary function, and abnormalities of chest radiographs to estimated exposures of borax dust has been investigated in a cross sectional study of 629 actively employed borax workers. Ninety three per cent of the eligible workers participated in the study and exposures ranged from 1.1 mg/m3 to 14.6 mg/m3. Symptoms of acute respiratory irritation such as dryness of the mouth, nose, or throat, dry cough, nose bleeds, sore throat, productive cough, shortness of breath, and chest tightness were related to exposures of 4.0 mg/m3 or more, and were infrequent at exposures of 1.1 mg/m3. Symptoms of persistent respiratory irritation meeting the definition of chronic simple bronchitis were related to exposure among non-smokers. Decrements in the FEV1 as a percentage of predicted were seen among smokers who had heavy cumulative borax exposures (greater than or equal to 80 mg/m3 years) but were not seen among less exposed smokers or among non-smokers. Radiographic abnormalities were uncommon and were not related to dust exposure. Borax dust appears to act as a simple respiratory irritant and perhaps causes small changes in the FEV1 among smokers who are heavily exposed.

Garabrant, D H; Bernstein, L; Peters, J M; Smith, T J; Wright, W E

1985-01-01

9

Thermoreversible konjac glucomannan gel crosslinked by borax  

Microsoft Academic Search

Dynamic viscoelastic measurements were carried out for novel konjac glucomannan\\/borax gels. Gel networks were formed through the crosslinking reaction between borate ions dissociated from borax and the cis-diol sites on the polysaccharide chains. At lower oscillation frequencies, the complex gels behave like a liquid, whereas at higher frequency they relax like true gel materials with a predominant elastic relaxation response.

Shanjun Gao; Jinming Guo; Katsuyoshi Nishinari

2008-01-01

10

Wet Scrubbing Experience with Fine Borax Dust  

Microsoft Academic Search

Borax dust emissions from borax fusion furnaces and calciners can be controlled by a moderate pressure drop scrubbing system designed to fit the particle characteristics. A case history is given for the upgrading of an inadequate scrubber system to a successful one by modification of existing equipment. Power requirement for the upgraded scrubber is 400 hp, as compared to 700

E. Dean Lemon

1977-01-01

11

Chemistry of the Borax/Glycol Condensate.  

National Technical Information Service (NTIS)

A review of some previous work on borate condensation reactions is given and experimental investigations are reported. The borax-glycol reaction is interpreted as involving a nearly complete degree of condensation, forming a mixture of acidic and basic bo...

G. H. Myers

1967-01-01

12

Assessment of boric acid and borax using the IEHR evaluative process for assessing human developmental and reproductive toxicity of agents  

SciTech Connect

This document presents an evaluation of the reproductive and developmental effects of boric acid, H3BO3 (CAS Registry No. 10043-35-3) and disodium tetraborate decahydrate or borax, Na2B4O2O(CAS Registry No. 1303-96-4). The element, boron, does not exist naturally. In dilute aqueous solution and at physiological pH (7.4), the predominant species in undissociated boric acid (greater than 98%), irrespective of whether the initial material was boric acid of borax. Therefore, it is both useful and correct to compare exposures and dosages to boric acid and borax in terms of `boron equivalents`, since both materials form equivalent species in dilute aqueous solution with similar systemic effects. In order to be clear in this document, the term `boron` will refer to `boron equivalents` or percent boron in boric acid and borax.

Moore, J.A.

1995-03-01

13

[Infrared spectral analysis for calcined borax].  

PubMed

To valuate the quality of calcined borax which is sold in the market, 18 samples of calcined borax were studied using the Fourier transform infrared, and samples with different water content were selected and analyzed. Then, the results of analysis were used to evaluate the quality of calcined borax. Results show that the infrared spectra of calcined borax include OH vibration, BO3(-3) vibration and BO4(5-) vibration absorption bands. The position and width of OH vibration absorption band depend on the level of water content, and the more the water content, the wider the absorption band. The number of BO3(3-) vibration and BO4(5-) vibration bands also depend on the level of water content, and the more the water content, and the stronger the hydrogen bond and the lower the symmetry of B atoms, the more the number of infrared absorption peaks. It was concluded that because the quality of calcined borax has direct correlation with water content, the infrared spectroscopy is an express and objective approach to quality analysis and evaluation of calcined borax. PMID:22007396

Zhao, Cui; Ren, Li-Li; Wang, Dong; Zhou, Ping; Zhang, Qian; Wang, Bo-Tao

2011-08-01

14

Crystallization kinetics of the borax decahydrate  

Microsoft Academic Search

The growth and dissolution rates of borax decahydrate have been measured as a function of supersaturation for various particle sizes at different temperature ranges of 13 and 50°C in a laboratory-scale fluidized bed crystallizer. The values of mass transfer coefficient, K, reaction rate constant, kr and reaction rate order, r were determined. The relative importances of diffusion and integration resistance

A. A. Ceyhan; Ö. Sahin; A. N. Bulutcu

2007-01-01

15

Laboratory Measurements of the W-band (3.2 mm) Properties of Phosphine (PH3) and Ammonia (NH3) Under Simulated Conditions for the Outer Planets  

NASA Astrophysics Data System (ADS)

A model, based on the Van Vleck-Weisskopf lineshape, was developed for the centimeter-wavelength opacity of PH3, which provides an order of magnitude improvement over previous models (Hoffman et al. ICARUS 152, 172-184, 2001). This formalism utilizes line intensities from the JPL (Pickett et al. 1998) catalog which have been selectively weighted to fit the centimeter wavelength laboratory data. The collisionally induced rotational lines which are lower in frequency than the first rotational line of J = 1 to 0 (267 GHz) have not been measured directly, thus in order to fit the data, weightings were given to those lines below 40 GHz. New laboratory measurements are currently being conducted to investigate whether this model is also accurate at 94 GHz (3.2 mm) under conditions for the outer planets. Preliminary measurements at room temperature agree well with this centimeter-wave formalism for PH3 opacity suggesting that the intensities of only the first 40 lines of the JPL catalog need to be weighted. Further measurements of the opacity and refractivity of PH3 in a hydrogen/helium (H2/He) atmosphere are being conducted at 94 GHz (3.2 mm) at pressures of 0.5, 1 and 2 bars and at temperatures of 210 K and 193 K. Additionally, new high-precision laboratory measurements of the opacity and refractivity of NH3 in an H2/He atmosphere will be conducted under the same frequency, temperature and pressure conditions described for PH3. These new measurements will better constrain the NH3 opacity model for use over a broader wavelength range. Results of measurements of both PH3 and NH3 can be used to better interpret maps of Saturn's emission at this wavelength and can potentially deduce spatial variations in the abundances of both gases in the atmosphere of Saturn. This work is supported by the NASA Planetary Atmospheres Program under grant NAG5-12122.

Mohammed, P. N.; Steffes, P. G.

2003-05-01

16

40 CFR 415.270 - Applicability; description of the borax production subcategory.  

Code of Federal Regulations, 2010 CFR

... Applicability; description of the borax production subcategory. 415.270...MANUFACTURING POINT SOURCE CATEGORY Borax Production Subcategory § 415.270 Applicability; description of the borax production subcategory. The...

2009-07-01

17

40 CFR 415.270 - Applicability; description of the borax production subcategory.  

Code of Federal Regulations, 2010 CFR

... Applicability; description of the borax production subcategory. 415.270...MANUFACTURING POINT SOURCE CATEGORY Borax Production Subcategory § 415.270 Applicability; description of the borax production subcategory. The...

2010-07-01

18

40 CFR 436.130 - Applicability; description of the borax subcategory.  

Code of Federal Regulations, 2010 CFR

...false Applicability; description of the borax subcategory. 436.130 Section 436...MINING AND PROCESSING POINT SOURCE CATEGORY Borax Subcategory § 436.130 Applicability; description of the borax subcategory. The provisions of...

2010-07-01

19

40 CFR 415.270 - Applicability; description of the borax production subcategory.  

Code of Federal Regulations, 2013 CFR

... Applicability; description of the borax production subcategory. 415.270...MANUFACTURING POINT SOURCE CATEGORY Borax Production Subcategory § 415.270 Applicability; description of the borax production subcategory. The...

2013-07-01

20

40 CFR 436.130 - Applicability; description of the borax subcategory.  

Code of Federal Regulations, 2010 CFR

...true Applicability; description of the borax subcategory. 436.130 Section 436...MINING AND PROCESSING POINT SOURCE CATEGORY Borax Subcategory § 436.130 Applicability; description of the borax subcategory. The provisions of...

2009-01-01

21

40 CFR 436.130 - Applicability; description of the borax subcategory.  

Code of Federal Regulations, 2013 CFR

...false Applicability; description of the borax subcategory. 436.130 Section 436...MINING AND PROCESSING POINT SOURCE CATEGORY Borax Subcategory § 436.130 Applicability; description of the borax subcategory. The provisions of...

2013-07-01

22

Laboratory measurements of the W band (3.2 mm) properties of phosphine (PH3) and ammonia (NH3) under simulated conditions for the outer planets  

NASA Astrophysics Data System (ADS)

A model, based on the Van Vleck-Weisskopf line shape, was developed for the centimeter-wavelength opacity of PH3, which provides an order of magnitude improvement over previous models [Hoffman et al., 2001]. New laboratory measurements indicate that the model is also accurate at 94 GHz (3.2 mm) under conditions for the outer planets. Measurements of the opacity and refractivity of PH3 in a hydrogen/helium (H2/He) atmosphere were conducted at 94 GHz (3.2 mm) at pressures of 0.5 and 2 bars and at temperatures of 293 K and 213 K. Additionally, new high-precision laboratory measurements of the opacity and refractivity of NH3 in an H2/He atmosphere were conducted at the same frequency at pressures from 0.5 to 2 bars and at temperatures of 204 K, 211 K, and 290 K. Results show that existing models, which predict NH3 opacity in an H2/He environment, understate the absorption due to the pressure broadened rotational lines. A new model is proposed for use at 94 GHz (3.2 mm) which uses a Ben-Reuven line shape [Ben-Reuven, 1966] for the inversion lines and a Kinetic line shape [Gross, 1955] for the rotational lines. Results of measurements of both PH3 and NH3 can be used to better interpret maps of Saturn's emission at this wavelength and can potentially be used to deduce spatial variations in the abundances of both gases in the atmosphere of Saturn.

Mohammed, Priscilla N.; Steffes, Paul G.

2004-07-01

23

Eagle Borax Works, Harmony Borax Works, Death Valley National Monument, California.  

National Technical Information Service (NTIS)

In this report the author suggests that in his view the most significant historical activity that occurred in Death Valley was the mining and processing of Borax. The purpose of this report has been to study the history of Death Valley National Monument. ...

F. R. Holland R. V. Simmonds

1971-01-01

24

A new Tertiary borax deposit in the Andes  

Microsoft Academic Search

The Loma Blanca borate deposit was formed in the muds of playa-lake environments during the Late Miocene and is the fourth Tertiary commercial borax deposit discovered within the borate districts of the world. It is the only South American deposit known to contain any of the minerals colemanite, inyoite, ulexite, borax, tincalconite and teruggite with a unique and characteristic mineral

R. N. Alonso; C. Helvac?; R. J. Sureda; J. G. Viramonte

1988-01-01

25

Electrochemical and ellipsometric study of the oxide films formed on copper in borax solution: Part II: Effect of ozone  

Microsoft Academic Search

The influence of O3 on the passive behaviour of copper was analysed in the potential region -0.32 to 0.70V vs RHE in borax solutions (pH9.2) through voltammetric techniques and ellipsometry. Oxide formation can be explained as a sequence of Cu2O growth, Cu(ii) chemisorption, and dissolution precipitation steps similar to those corresponding to copper electrodes in deaerated solutions. The role of

M. F. L. DE MELE; M. R. VIERA; J. O. ZERBINO

1997-01-01

26

Impurity adsorption mechanism of borax for a suspension growth condition: A comparison of models and experimental data  

Microsoft Academic Search

A fluidized bed crystallizer is employed to investigate the growth and dissolution rates of MgSO4?7H2O from aqueous solutions in the presence of borax as impurity at 25°C. By adding 0.5, 1, 2 and 5 wt % of impurity the pH value changes from 6.7 to 7.11, while the saturation temperature shifts to 24.8, 24.4, 24 and 23.1°C, respectively. The data

Sattar Al-Jibbouri; Joachim Ulrich

2004-01-01

27

Intracrystalline site preference of hydrogen isotopes in borax  

SciTech Connect

The total hydrogen involved in borax synthesized at 25/sup 0/C in aqueous solution is enriched in deuterium by 5.3% compared with the mother liquor. There is no change in the value of the D/H fractionation factor between the hydrogen in borax and those in the mother liquor with changes in the degree of supersaturation. The fractionation factor changes slightly with a change in the crystallization temperature of borax in the range from 5 to 25/sup 0/C. The D/H ratio in the different sites of borax was estimated by a fractional dehydration technique. The results show that hydrogen atoms of the polyanionic group (B/sub 4/O/sub 5/(OH)/sub 4/) are much more enriched in deuterium than those of the cationic group (Na/sub 2/ x 8H/sub 2/O). The delta D values, referred to the mother liquor from which the borax was crystallized, for the cationic group (site A) and the polyanionic group (site B) are -35 +/- 3 and 167 +/- 13%, respectively based on the fractional dehydration results obtained at -21/sup 0/C. At -21/sup 0/C, isotopic exchange between different sites during dehydration is assumed not to occur. The mechanism for dehydration of borax is discussed. 48 references, 8 figures, 3 tables.

Pradhananga, T.M.; Matsuo, S.

1985-01-03

28

40 CFR 180.1121 - Boric acid and its salts, borax (sodium borate decahydrate), disodium octaborate tetrahydrate...  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Boric acid and its salts, borax (sodium borate decahydrate...Tolerances § 180.1121 Boric acid and its salts, borax (sodium borate decahydrate...pesticidal chemical boric acid and its salts, borax (sodium borate...

2011-07-01

29

Production of high bulk density anhydrous borax in fluidized bed granulator  

Microsoft Academic Search

Production of anhydrous borax from borax pentahydrate was investigated in a fluidized bed calcinator. Single step calcination gives a puffed product with very low density. In order to obtain high bulk density product dehydration should be carried out at least in two stages. The most important step dominating the final bulk density is the first step. Dehydration of borax pentahydrate

Omer Sahin; A. Nusret Bulutcu

2002-01-01

30

Seizure disorders and anemia associated with chronic borax intoxication  

PubMed Central

During the course of investigation of two infants with seizure disorders it was discovered that both had been given large amounts of a preparation of borax and honey which resulted in chronic borate intoxication. In one child a profound anemia developed as well. The symptoms of chronic borate intoxication are different from those of the acute poisoning with which we are more familiar. The borax and honey preparations are highly dangerous and should no longer be manufactured or distributed for sale. ImagesFIG. 1FIG. 2

Gordon, A. S.; Prichard, J. S.; Freedman, M. H.

1973-01-01

31

Dynamics of pH modification of an acidic protein bait used for tropical fruit flies (Diptera: Tephritidae).  

PubMed

Several species of Anastrepha and Bactrocera fruit flies (Diptera: Tephritidae) are captured in traps baited with the protein bait NuLure combined with borax (sodium tetraborate decahydrate) in an aqueous solution, typically 9% NuLure (vol:vol) with 3% borax (wt:vol). NuLure is an acid hydrolysate of corn and has an acidic pH. Addition of borax makes the solution more alkaline, and increase in alkalinity results in increase of ammonia release from the bait solution. This is a very dynamic system, with resultant pH affected by factors such as the amount of borax added, the pH of the water used for preparation, the age of the bait solution, and the development of microbial growth. Problems with borax include amount needed to increase alkalinity of NuLure solutions, which creates difficulties in disposing of spent bait in fruit fly trapping programs. Therefore, research was conducted to evaluate NaOH as an alternative method to increase alkalinity of NuLure solutions. Laboratory experiments compared effect of NaOH versus borax for pH modification on changes in pH and ammonia content of NuLure solutions over time. Although NuLure/NaOH solutions could be adjusted to a more alkaline pH than NuLure/borax solutions, borax plays a critical role in pH stability over time. However, the pH of NuLure/NaOH is stabilized when propylene glycol (10% vol:vol) was used to prepare the bait solution. The use of NaOH can provide an alternative to the use of borax to increase bait solution alkalinity. PMID:20069869

Heath, Robert R; Vazquez, Aime; Schnell, Elena Q; Villareal, Janett; Kendra, Paul E; Epsky, Nancy D

2009-12-01

32

Photonic crystal borax competitive binding carbohydrate sensing motif.  

PubMed

We developed a photonic crystal sensing method for diol containing species such as carbohydrates based on a poly(vinyl alcohol) (PVA) hydrogel containing an embedded crystalline colloidal array (CCA). The polymerized CCA (PCCA) diffracts visible light. We show that in the presence of borax the diffraction wavelength shifts as the concentration of glucose changes. The diffraction shifts result from the competitive binding of glucose to borate, which reduces the concentration of borate bound to the PVA diols. PMID:19381378

Cui, Qingzhou; Ward Muscatello, Michelle M; Asher, Sanford A

2009-05-01

33

Toxicity detection of sodium nitrite, borax and aluminum potassium sulfate using electrochemical method.  

PubMed

Based on the inhibition effect on the respiratory chain activity of microorganisms by toxicants, an electrochemical method has been developed to measure the current variation of a mediator in the presence of microorganisms contacted with a toxicant. Microelectrode arrays were adopted in this study, which can accelerate the mass transfer rate of an analyte to the electrode and also increase the total current signal, resulting in an improvement in detection sensitivity. We selected Escherichia coli as the testee and the standard glucose-glutamic acid as an exogenous material. Under oxygen restriction, the experiments in the presence of toxicant were performed at optimum conditions (solution pH 7.0, 37 degrees C and reaction for 3 hr). The resulting solution was then separated from the suspended microorganisms and was measured by an electrochemical method, using ferricyanide as a mediator. The current signal obtained represents the reoxidation of ferrocyanide, which was transformed to inhibiting efficiency, IC50, as a quantitative measure of toxicity. The IC50 values measured were 410, 570 and 830 mg/L for sodium nitrite, borax and aluminum potassium sulfate, respectively. The results show that the toxicity sequence for these three food additives is consistent with the value reported by other methods. Furthermore, the order of damage degree to the microorganism was also observed to be: sodium nitrite > borax > aluminum potassium sulfate > blank, according to the atomic force microscopy images of E. coli after being incubated for 3 hr with the toxic compound in buffer solutions. The electrochemical method is expected to be a sensitive and simple alternative to toxicity screening for chemical food additives. PMID:23923788

Yu, Dengbin; Yong, Daming; Dong, Shaojun

2013-04-01

34

Corrosion resistance of inconel 690 to borax, boric acid, and boron nitride at 1100°C  

Microsoft Academic Search

Significant general and localized corrosion was observed on Inconel 690 coupons following exposure to borax, boric acid and boron nitride at 1100°C. Severe localized attack at and below the melt line was observed on coupons exposed to borax. An intergranular attack at and below the melt line was observed on coupons exposed to borax. An intergranular attack (IGA) of the

Imrich

2010-01-01

35

40 CFR 180.1121 - Boric acid and its salts, borax (sodium borate decahydrate), disodium octaborate tetrahydrate...  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Boric acid and its salts, borax (sodium borate...From Tolerances § 180.1121 Boric acid and its salts, borax (sodium borate...residues of the pesticidal chemical boric acid and its salts, borax (sodium...

2013-07-01

36

40 CFR 180.1121 - Boric acid and its salts, borax (sodium borate decahydrate), disodium octaborate tetrahydrate...  

Code of Federal Regulations, 2010 CFR

...2009-07-01 2009-07-01 false Boric acid and its salts, borax (sodium borate...From Tolerances § 180.1121 Boric acid and its salts, borax (sodium borate...residues of the pesticidal chemical boric acid and its salts, borax (sodium...

2009-07-01

37

40 CFR 180.1121 - Boric acid and its salts, borax (sodium borate decahydrate), disodium octaborate tetrahydrate...  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Boric acid and its salts, borax (sodium borate...From Tolerances § 180.1121 Boric acid and its salts, borax (sodium borate...residues of the pesticidal chemical boric acid and its salts, borax (sodium...

2010-07-01

38

Excavations at Harmony Borax Works: Historical Archeology at Death Valley National Monument.  

National Technical Information Service (NTIS)

The report gives details of excavations at Harmony Borax Works, Death Valley National Monument, California. Harmony was the central feature in the opening of Death Valley. During the 1880s, 20-mule teams hauled borax from Harmony to the rail head at Mojav...

G. A. Teague L. O. Shenk

1977-01-01

39

Dynamic light scattering of poly(vinyl alcohol)borax aqueous solution near overlap concentration  

Microsoft Academic Search

The physical properties of PVA-borax aqueous solutions with a PVA concentration near the overlap concentration and various borax concentrations were observed using dynamic light scattering and dynamic viscoelastic measurements. It had been proposed by Leibler et al. that the structure of PVA-borate complex in dilute aqueous solution strongly depends on: (1) excluded volume effect of polymers; (2) the intra- and

Chung Yuan Chen; Tzyy-Lung Yu

1997-01-01

40

Recovery of boron of the sieve reject in the production of borax  

Microsoft Academic Search

Boron ores are one of the most important underground richness of Turkey. Various boron compounds are produced from these ores. The most important one of them is borax. During the borax production process, a large quantity of the boron oxide (B2O3) is discharged by the trommel sieve waste (TSW). Also, this waste causes different environmental problems when it discharged directly

Recep Boncukcuo?lu; M. Muhtar Kocakerim; Erdem Kocada?istan; M. Tolga Yilmaz

2003-01-01

41

Guar gum and scleroglucan interactions with borax: experimental and theoretical studies of an unexpected similarity.  

PubMed

Guar gum is a galactomannan that assumes a very flexible conformation in solution, while Scleroglucan is a very rigid polysaccharide that dissolves in water as triple helices. Both polymers can form gels in the presence of borax. Despite their structural differences, the freeze-dried gel systems of both polymers, when compressed to form tablets, show a peculiar anisotropic swelling in water that reflects an amazing similarity in terms of their molecular properies. In this paper the behavior of the Guar/borax gel is compared with that of Scleroglucan/borax. The macroscopic properties of the two systems were characterized in terms of rheological measurements. Atomic force microscopy images and molecular dynamics simulation allowed to evaluate, at molecular level, the effect of borax addition to the Guar polymer. Both experiments show that an increasing of the polymer rigidity is produced by borax. The role played by galactose in the side chain was also discussed. PMID:20863102

Bocchinfuso, Gianfranco; Mazzuca, Claudia; Sandolo, Chiara; Margheritelli, Silvia; Alhaique, Franco; Coviello, Tommasina; Palleschi, Antonio

2010-10-21

42

Resistance of Borax-Copper Treated Wood in Aboveground Exposure to Attack by Formosan Subterranean Termites.  

National Technical Information Service (NTIS)

The spread of Formosan subterranean termites (FSTs) in the southern United States has increased public interest in finding a preservative treatment to protect framing lumber from termite attack. This study evaluated the use of a borax-based preservative t...

S. Lebow B. Woodward D. Crawford W. Abbott

2005-01-01

43

Hydrologic data and description of a hydrologic monitoring plan for the Borax Lake area, Oregon  

USGS Publications Warehouse

Borax Lake is located in southeastern Oregon, within the Alvord Valley Known Geothermal Resource Area. Borax Lake is a large hot spring; there are more than 50 smaller hot springs within about one-half mile to the north of the lake. Several geothermal exploration wells have been drilled near Borax Lake, and there is concern that development of the geothermal resources could affect the lake and nearby hot springs. A factor to consider in developing the resource is that the Borax Lake chub is an endangered species of fish that is found exclusively in Borax Lake. This study was designed to collect basic hydrologic data to develop a long-term monitoring plan. Baseline data, collected before geothermal production wells are used extensively, will provide an understanding of natural trends and will help identify change caused by development. Basic data collected during reconnaissance field visits to the area included spring temperatures, specific conductances, and discharge; field measurements in wells included water-level measurements and temperature, specific conductance, and discharge measurements in flowing wells. The study of the Borax Lake area included depth and temperature measurements in the vent area of the lake, point velocity measurements, underwater video photography, and an evaluation of methods to measure discharge from the lake. Water-quality samples were collected at Borax Lake, one hot spring, and one flowing well. Information from field visits was used to develop a monitoring plan. The plan would include monitoring Borax Lake by measuring discharge, stage, evaporation, temperature, and specific conductance; water-quality sampling and analysis; and monitoring shallow ground-water levels near Borax Lake using shallow piezometers. Minimally, one hot spring in North Borax Lake Spring Group 1 would be monitored for temperature and specific conductance and sampled for water-quality analysis. In addition, two flowing wells would be monitored for water levels, temperature, specific conductance, and discharge and sampled for water-quality analysis. The construction characteristics of these wells must be verified before long-term data collection begins. In the future, it may be helpful to monitor shallow and (or) deep observation wells drilled into the thermal aquifer to understand the possible effects of geothermal development on Borax Lake and nearby springs.

Schneider, T. R.; McFarland, William D.

1995-01-01

44

Borax counteracts genotoxicity of aluminum in rat liver.  

PubMed

This study was carried out to evaluate the protective role of borax (BX) on genotoxicity induced by aluminum (Al) in rat liver, using liver micronucleus assay as an indicator of genotoxicity. Sprague-Dawley rats were randomly separated into six groups and each group had four animals. Aluminum chloride (AlCl?; 5 mg/kg b.w.) and BX (3.25 and 13 mg/kg b.w.) were injected intraperitoneally to rats. Besides, animals were also treated with Al for 4 consecutive days followed by BX for 10 days. Rats were anesthetized after Al and BX injections and the hepatocytes were isolated for counting the number of micronucleated hepatocytes (MNHEPs). AlCl? was found to significantly (p < 0.05) increase the number of MNHEPs. Rats treated with BX, however, showed no increase in MNHEPs. Moreover, simultaneous treatments with BX significantly modulated the genotoxic effects of AlCl? in rats. It can be concluded that BX has beneficial influences and has the ability to antagonize Al toxicity. PMID:22491726

Turkez, Hasan; Geyiko?lu, Fatime; Tatar, Abdulgani

2013-10-01

45

Effect of sodium nitrite–borax blend on the corrosion rate of low carbon steel in industrial water medium  

Microsoft Academic Search

Effects of sodium nitrite–borax blend on low carbon steel corrosion in industrial water medium at various temperatures, various inhibitors concentration of sodium nitrite and borax and at various rotational speeds of the specimens have been studied by gravimetric and polarization measurements. Optimization of the three variables was made and correlating the results obtained by using Box–Wilson statistical method. The process

K. N. Mohana; A. M. Badiea

2008-01-01

46

The effect of borax pentahydrate addition to urea formaldehyde on the mechanical characteristics and free formaldehyde content of plywood  

Microsoft Academic Search

In this study, the effects of borax pentahydrate addition to urea formaldehyde (UF) on the bonding characteristics and free formaldehyde content have been studied. Experiments related to the bending strength, withdrawal shear strength and free formaldehyde content have been conducted on the three-layered beech and poplar plywood which are prepared by the addition of borax pentahydrate into their adhesive mixtures

Cem Sensogut; Murat Ozalp; Huseyin Yesil

2009-01-01

47

8mm/16mm Movie-Making.  

ERIC Educational Resources Information Center

The materials, techniques, and attitudes needed to make professional-quality movies using 8mm., super 8mm., and 16mm. amateur equipment are covered in this guide to movie-making. The pros and cons are discussed of the various makes and models of cameras and lenses. Other topics discussed are: exposure and lighting, choosing film, camera speed and…

Provisor, Henry

48

Sorption of boric acid and borax by activated carbon impregnated with various compounds  

Microsoft Academic Search

The separation of boron compounds, boric acid and borax from aqueous solution by activated carbon before and after impregnation with various compounds was studied. A series of activated carbons was prepared from coconut shell impregnated with calcium and barium chlorides, citric and tartaric acids. The examined processes were performed in batch and continuous systems under equilibrium and dynamic conditions. Impregnation

Lj. V. Rajakovi?; M. Dj. Risti?

1996-01-01

49

Association of reversible alopecia with occupational topical exposure to common borax-containing solutions  

Microsoft Academic Search

Boron is widely used in industrial materials, most frequently as the salt borax. Systemic exposure (eg, ingestion) to boron in boric acid been associated with reversible toxic alopecia among other manifestations. There is scant clinical literature on alopecia caused by topical exposure to boron. We observed a series of 3 patients in 2 workplaces who suffered reversible alopecia from cutaneous

William S. Beckett; Roger Oskvig; Mary Ellen Gaynor; Mark H. Goldgeier

2001-01-01

50

Impact of the propylene glycol-water-borax coolant on material recovery operations  

Microsoft Academic Search

The reaction of the propylene glycol-water-borax coolant with nitric acid has now been studied in some detail. This document is intended to provide a summary of the results. Findings are summarized under nine headings. Tests have also been conducted to determine if the new coolant would have any adverse effects on the uranium recycle systems. Experiments were scientifically designed after

W. K. Duerksen; P. A. Taylor

1983-01-01

51

Effect of mixing on the crystal size distribution of borax decahydrate in a batch cooling crystallizer  

Microsoft Academic Search

The effect of the impeller speed upon the metastable zone width, supersaturation level, crystal growth and the crystal size distribution of borax decahydrate have been investigated to find operating conditions of a batch cooling crystallizer. The importance of impeller speed was studied in baffled stirred crystallizer with a volume of about 2dm3, equipped with four straight blade turbine (4-SBT) cooling

Marija Akrap; Nenad Kuzmanic; Jasna Prlic-Kardum

2010-01-01

52

A Human Health Risk Assessment of Boron (Boric Acid and Borax) in Drinking Water  

Microsoft Academic Search

A human health risk assessment was conducted to derive an appropriate safe exposure level in drinking water of inorganic boron-containing compounds (boric acid and borax). Several regulatory agencies have set or plan to set drinking water guidelines or standards for boron (B). Recent publication of reproductive and developmental toxicity studies by the National Toxicology Program prompted this risk assessment, along

F. Jay Murray

1995-01-01

53

Enhancing fluorescence intensity of Ellagic acid in Borax-HCl-CTAB micelles.  

PubMed

Ellagic acid (C(14)H(6)O(8)), a naturally occurring phytochemical, found mainly in berries and some nuts, has anticarcinogenic and antioxidant properties. It is found that fluorescence of Ellagic acid (EA) is greatly enhanced by micelle of cetyltrimethylammonium bromide (CTAB) surfactant. Based on this effect, a sensitive proposed fluorimetric method was applied for the determination of Ellagic acid in aqueous solution. In the Borax-HCl buffer, the fluorescence intensity of Ellagic acid in the presence of CTAB is proportional to the concentration of Ellagic acid in range from 8.0×10(-10) to 4.0×10(-5) mol L(-1); and the detection limits are 3.2×10(-10) mol L(-1) and 5.9×10(-10) mol L(-1) excited at 266 nm and 388 nm, respectively. The actual samples of pomegranate rinds are simply manipulated and satisfactorily determined. The interaction mechanism studies argue that the negative EA-Borax complex is formed and solubilized in the cationic surfactant CTAB micelle in this system. The fluorescence intensity of EA enhances because the CTAB micelle provides a hydrophobic microenvironment for EA-Borax complex, which can prevent collision with water molecules and decrease the energy loss of EA-Borax complex. PMID:21239219

Wang, Feng; Huang, Wei; Zhang, Shuai; Liu, Guokui; Li, Kexiang; Tang, Bo

2011-03-01

54

Morphology–rheology relationship in hyaluronate\\/poly(vinyl alcohol)\\/borax polymer blends  

Microsoft Academic Search

In this work, we have prepared bioartificial polymer blends using hyaluronate (HA) as a biological component and poly(vinyl alcohol)–borax association (PVAs) as a synthetic component, and investigated the rheological properties as well as morphology of the blends. When plotted against the blend composition, the rheological properties showed both positive and negative deviation from the linear additive mixing rule depending on

Sook Heun Kim; Kyu Hyun; Tae Seok Moon; Tetsu Mitsumata; Joung Sook Hong; Kyung Hyun Ahn; Seung Jong Lee

2005-01-01

55

The effect of potassium carbonate, borax and wolmanit on the burning characteristics of oriented strandboard (OSB)  

Microsoft Academic Search

In this study, the determination of the burning characteristics of oriented strandboard (OSB) and the effect on the burning characteristics of OSB when three chemical substances, potassium carbonate, borax and wolmanit, which are used as a fire retardant, are applied with the methods of brushing or dipping, have been researched. A total of 56 each samples were prepared for this

Kadir Ozkaya; Abdullah Cemil Ilce; Erol Burdurlu; Salih Aslan

2007-01-01

56

Scleroglucan-borax hydrogel: a flexible tool for redox protein immobilization.  

PubMed

A highly stable biological film was prepared by casting an aqueous dispersion of protein and composite hydrogel obtained from the polysaccharide Scleroglucan (Sclg) and borax as a cross-linking agent. Heme proteins, such as hemoglobin (Hb), myoglobin (Mb), and horseradish peroxidase (HRP), were chosen as model proteins to investigate the immobilized system. A pair of well-defined quasi-reversible redox peaks, characteristics of the protein heme FeII/FeIII redox couples, were obtained at the Sclg-borax/proteins films on pyrolytic graphite (PG) electrodes, as a consequence of the direct electron transfer between the protein and the PG electrode. A full characterization of the electron transfer kinetic was performed by opportunely modeling data obtained from cyclic voltammetry and square wave voltammetry experiments. The efficiency of our cross-linking approach was investigated by studying the influence of different borax groups percentage in the Sclg matrix, revealing the versatility of this hydrogel in the immobilization of redox proteins. The native conformation of the three heme proteins entrapped in the hydrogel films were proved to be unchanged, reflected by the unaltered Soret adsorption band and by the catalytic activity toward hydrogen peroxide (H2O2). The main kinetic parameters, such as the apparent Michaelis-Menten constant, for the electrocatalytic reaction were also evaluated. The peculiar characteristics of Sclg-borax matrix make it possible to find wide opportunities as proteins immobilizing agent for studies of direct electrochemistry and biosensors development. PMID:19694483

Frasconi, Marco; Rea, Sara; Matricardi, Pietro; Favero, Gabriele; Mazzei, Franco

2009-09-15

57

Dispersion of borax in plastic is excellent fire-retardant heat insulator  

NASA Technical Reports Server (NTRS)

A mix of borax powder and a chlorinated anhydrous polyester resin yields a plastic composition that is fire-retardant, yields a minimum of toxic gases when heated, and exhibits high thermal insulating properties. This composition can be used as a coating or can be converted into laminated or cast shapes.

Evans, H.; Hughes, J.; Schmitz, F.

1967-01-01

58

Borax mediated layer-by-layer self-assembly of neutral poly(vinyl alcohol) and chitosan.  

PubMed

We report a multilayer film of poly(vinyl alcohol) (PVA)-borate complex and chitosan by using a layer-by-layer approach. PVA is an uncharged polymer, but hydroxyl functional groups of PVA can be cross-linked by using borax as a cross-linking agent. As a result electrostatic charges and intra- and interchain cross-links are introduced in the PVA chain and provide physically cross-linked networks. The PVA-borate was then deposited on a flat substrate as well as on colloidal particles with chitosan as an oppositely charged polyelectrolyte. Quartz crystal microbalance, scanning electron microscopy, and atomic force microscopy were used to follow the growth of thin film on flat substrate. Analogous experiments were performed on melamine formaldehyde colloidal particles (3-3.5 microm) to quantify the process for the preparation of hollow microcapsules. Removal of the core in 0.1 N HCl results in hollow microcapsules. Characterization of microcapsules by transmission electron microscopy revealed formation of stable microcapsules. Further, self-assembly of PVA-borate/chitosan was loaded with the anticancer drug doxorubicin, and release rates were determined at different pH values to highlight the drug delivery potential of this system. PMID:19530685

Manna, Uttam; Patil, Satish

2009-07-01

59

Corrosion resistance of inconel 690 to borax, boric acid, and boron nitride at 1100{degrees}C  

SciTech Connect

Significant general and localized corrosion was observed on Inconel 690 coupons following exposure to borax, boric acid and boron nitride at 1100{degrees}C. Severe localized attack at and below the melt line was observed on coupons exposed to borax. An intergranular attack at and below the melt line was observed on coupons exposed to borax. An intergranular attack (IGA) of the Inconel 690 was also observed. Severe internal void formation and IGA (30 mils penetration after 3 days) was observed in the coupon exposed to boric acid. Both borax and boric acid remove the protective chromium oxide; however, this layer can be reestablished by heating the Inconel 690 to 975 {degrees}C in air for several hours. Inconel 690 in direct contact with boron nitride resulted in the formation of a thick chromium borate layer, a general corrosion rate of 50 to 90 mils per year, and internal void formation of 1 mil per day.

Imrich, K.J.

1996-12-12

60

Validation of MCNP: SPERT-D and BORAX-V fuel  

SciTech Connect

This report discusses critical experiments involving SPERT-D{sup 1,2} fuel elements and BORAX-V{sup 3-8} fuel which have been modeled and calculations performed with MCNP. MCNP is a Monte Carlo based transport code. For this study continuous-energy nuclear data from the ENDF/B-V cross section library was used. The SPERT-D experiments consisted of various arrays of fuel elements moderated and reflected with either water or a uranyl nitrate solution. Some SPERT-D experiments used cadmium as a fixed neutron poison, while others were poisoned with various concentrations of boron in the moderating/reflecting solution. ne BORAX-V experiments were arrays of either boiling fuel rod assemblies or superheater assemblies, both types of arrays were moderated and reflected with water. In one boiling fuel experiment, two fuel rods were replaced with borated stainless steel poison rods.

Crawford, C.; Palmer, B.

1992-11-01

61

Validation of MCNP: SPERT-D and BORAX-V fuel  

SciTech Connect

This report discusses critical experiments involving SPERT-D[sup 1,2] fuel elements and BORAX-V[sup 3-8] fuel which have been modeled and calculations performed with MCNP. MCNP is a Monte Carlo based transport code. For this study continuous-energy nuclear data from the ENDF/B-V cross section library was used. The SPERT-D experiments consisted of various arrays of fuel elements moderated and reflected with either water or a uranyl nitrate solution. Some SPERT-D experiments used cadmium as a fixed neutron poison, while others were poisoned with various concentrations of boron in the moderating/reflecting solution. ne BORAX-V experiments were arrays of either boiling fuel rod assemblies or superheater assemblies, both types of arrays were moderated and reflected with water. In one boiling fuel experiment, two fuel rods were replaced with borated stainless steel poison rods.

Crawford, C.; Palmer, B.

1992-11-01

62

A study of the copper electrode behavior in borax buffer solutions containing chloride ions and benzotriazole-type inhibitors by voltammetry and the photocurrent response method  

Microsoft Academic Search

The electrochemical behavior of the Cu electrode in borax buffer solutions containing chloride ions and benzotriazole (BTA)-type inhibitors was studied by voltammetry and the photocurrent response method. A p-type photoresponse was observed from the Cu electrode in the pure borax buffer solutions. However, an n-type photoresponse was observed in chloride-containing borax buffer solutions if the Cl? concentration exceeded 0.08%. The

Guo-Ding Zhou; Hua Shao; B. H. Loo

1997-01-01

63

Structural and rheological characterization of Scleroglucan\\/borax hydrogel for drug delivery  

Microsoft Academic Search

The polysaccharide Scleroglucan, one of the most rigid polymers found in nature, can form a chemical\\/physical gel, in the presence of borax. The obtained hydrogel was loaded with three different model molecules (Theophylline, Vitamin B12 and Myoglobin) and then, after freeze-drying, was used as a matrix for tablets. The release profiles of the substances from the dosage forms were evaluated;

Tommasina Coviello; Gina Coluzzi; Antonio Palleschi; Mario Grassi; Eleonora Santucci; Franco Alhaique

2003-01-01

64

Potential dependence of the optical properties of the copper | aqueous borax interface  

Microsoft Academic Search

The potential dependence of the optical properties of a copper surface at potentials where CuO and Cu2O are reduced has been studied by in situ ellipsometry in 0.1 M borax. It is shown that a thin layer of a copper(I) oxide remains on the surface even after extensive reduction. It is proposed that these oxide films play an important role

Silvia Ceré; Susana R. de Sánchez; David J. Schiffrin

1995-01-01

65

Mysterious M&M's  

NSDL National Science Digital Library

Learners place an M&M candy in water and observe what happens. The sugar-and-color coating dissolves and spreads out in a circular pattern around the M&M. This introductory activity provides a basis for learners to ask questions and to learn more about dissolving, identifying and controlling variables, and designing a fair test.

Kessler, James H.; Galvan, Patricia M.

2007-01-01

66

Epoxy-borax-coal tar composition for a radiation protective, burn resistant drum liner and centrifugal casting method  

DOEpatents

A boron containing burn resistant, low level radiation protection material useful, for example, as a liner for radioactive waste disposal and storage, a component for neutron absorber, and a shield for a neutron source. The material is basically composed of Borax in the range of 25-50%, coal tar in the range of 25-37.5%, with the remainder being an epoxy resin mix. A preferred composition is 50% Borax, 25% coal tar and 25% epoxy resin. The material is not susceptible to burning and is about 1/5 the cost of existing radiation protection material utilized in similar applications.

Taylor, Robert S. (Livermore, CA); Boyer, Norman W. (Livermore, CA)

1980-01-01

67

8MM Film Directory.  

ERIC Educational Resources Information Center

All 8mm films in general distribution in the United States, regardless of length or subject, are listed in this directory: Standard or Super 8, silent or sound, cartridge or reel-to-reel. Indexed alphabetically and by the Dewey Decimal System, films and film series are entered under the headings of Arts, Education, Fiction, Language, Recreation,…

Kone, Grace Ann, Comp.

68

The effects of dietary boric acid and borax supplementation on lipid peroxidation, antioxidant activity, and DNA damage in rats  

Microsoft Academic Search

The aims of this study were to clarify the effects of high dietary supplementation with boric acid and borax, called boron (B) compounds, on lipid peroxidation (LPO), antioxidant activity, some vitamin levels, and DNA damage in rats. Thirty Sprague Dawley male rats were divided into three equal groups: the animals in the first group (control) were fed with a standard

Sinan Ince; Ismail Kucukkurt; Ibrahim Hakki Cigerci; A. Fatih Fidan; Abdullah Eryavuz

2010-01-01

69

ASSESSMENT OF BORIC ACID AND BORAX USING THE IEHR EVALUATIVE PROCESS FOR ASSESSING HUMAN DEVELOPMENT AND REPRODUCTIVE TOXICITY OF AGENTS  

EPA Science Inventory

This document presents an evaluation of the reproductive and developmental effects of boric acid, H3803 (CAS Registry No. 10043-35-3) and disodium tetraborate decehydrate or borax, Na2B4O2O(CAS Registry No. 1303-96-4). he element, boron, does not exist naturally. oron always exis...

70

Growth and uptake of N, P, K and B by Pinus radiata D. Don in response to applications of borax  

Microsoft Academic Search

Leader dieback associated with B deficiency in P. radiata D. Don plantations was treated with borax applied at rates of 50, 100 and 150 kg ha?1. This initially increased B in foliage from 5 to 40, 80 and 110 ?g g?1 respectively, and was followed by a rapid decline and stabilisation at around 25 ?g g?1 for the duration of

Peter Hopmans; Simon Clerehan

1991-01-01

71

Redetermination of the borax structure from laboratory X-ray data at 145 K  

PubMed Central

The title compound, sodium tetraborate decahydrate (mineral name: borax), Na2[B4O5(OH)4]·8H2O, has been studied previously using X-ray [Morimoto (1956). Miner. J. 2, 1–18] and neutron [Levy & Lisensky (1978). Acta Cryst. B34, 3502–3510] diffraction data. The structure contains tetra­borate anions [B4O5(OH)4]2? with twofold rotation symmetry, which form hydrogen-bonded chains, and [Na(H2O)6] octa­hedra that form zigzag chains [Na(H2O)4/2(H2O)2/1]. The O—H bond distances obtained from the present redetermination at 145?K are shorter than those in the neutron study by an average of 0.127?(19)?Å.

Gainsford, Graeme J.; Kemmitt, Tim; Higham, Caleb

2008-01-01

72

Total cost of 46-Mw Borax cogen system put at $30M  

SciTech Connect

The cogeneration system, designed around a W-251B gas turbine power plant exhausting into a Deltak waste heat boiler to produce ''free'' process steam from the gas turbine exhaust, is discussed. The design includes water injection for NO/sub x/ control, self-cleaning inlet air filters, evaporative coolers, supercharger, and supplementary firing of the waste heat boiler. Once the system is operational Borax will be able to generate all of the electricity needed for on-site operations and a large share of process steam needs--plus still have 22-23 Mw surplus electric power to sell, so that the installation should pay for itself in less than 5 years of service.

de Biasi, V.

1983-03-01

73

Preparation and characterization of antimicrobial wound dressings based on silver, gellan, PVA and borax.  

PubMed

Silver-loaded dressings are designed to provide the same antimicrobial activity of topical silver, with the advantages of a sustained silver release and a reduced number of dressing changes. Moreover, such type of dressing must provide a moist environment, avoiding fiber shedding, dehydration and adherence to the wound site. Here we describe the preparation of a novel silver-loaded dressing based on a Gellan/Hyaff(®) (Ge-H) non woven, treated with a polyvinyl alcohol (PVA)/borax system capable to enhance the entrapment of silver in the dressing and to modulate its release. The new hydrophilic non woven dressings show enhanced water uptake capability and slow dehydration rates. A sustained silver release is also achieved. The antibacterial activity was confirmed on Staphylococcus aureus and Pseudomonas aeruginosa. PMID:22939352

Cencetti, C; Bellini, D; Pavesio, A; Senigaglia, D; Passariello, C; Virga, A; Matricardi, P

2012-10-15

74

Borax in the supraglacial moraine of the Lewis Cliff, Buckley Island quadrangle--first Antarctic occurrence  

USGS Publications Warehouse

During the 1987-1988 austral summer field season, membersof the south party of the antarctic search for meteorites south-ern team* working in the Lewis Cliff/Colbert Hills region dis-covered several areas of unusual mineralization within theLewis Cliff ice tongue and its associated moraine field (figure1). The Lewis Cliff ice tongue (84°15'S 161°25'E) is a meteorite-stranding surface of ablating blue ice, about 2.3 by 7.0 kilo-meters, bounded on the west by the Lewis Cliff, on the northand northeast by a large supraglacial moraine, and on the eastby the Colbert Hills. To the south it opens to the Walcott Névé.Because it is a meteorite-stranding surface, the major component of ice motion in the area is believed to be vertical(Whillans and Cassidy 1983). The presence of Thule-Baffinmoraines at the northern terminus of the blue ice tends tosupport the hypothesis that the area underlying the moraineis essentially stagnant and that ice arriving from the south ispiling up against it. Areas containing mineral deposits werefound within the moraine field to the north and east of theblue ice margin and also along the east margins of the blue iceitself. Subsequent X-ray diffraction analyses of these depositshave shown that they are composed predominantly of nah-colite (NaHCO3), trona [Na3(CO3)(HCO3) · 2H20], borax[Na2B405(OH)4 · 8H20], and a new hexagonal hydrous sulfatespecies. This paper reports the details of the borax occurrence,because it is the first known on the continent.

Fitzpatrick, J. J.; Muhs, D. R.

1989-01-01

75

Measurements of Density and Thermal Expansion Coefficient of Sodium Tetraborate (Borax)-UO2 and of Sodium Metaborate-UO2 Solutions.  

National Technical Information Service (NTIS)

Measurements have been performed on the density and volumetric thermal expansion coefficient of liquid sodium tetraborate (borax) and of sodium metaborate, both pure, and with two different amounts of UO2 dissolved in each. These data are required for the...

M. Dalle Donne S. Dorner

1981-01-01

76

Discussion Question Resource: Laboratory Blood Test Results Laboratory Blood Test Results Arterial Blood Gases 141 Meg/L Mg 1.7 mg/dL pH 7.50 K 4.5 Meg/L PO4 2.9 mg/dL PaO2 59 mm Hg room air Cl 105 Meg/L Glu fasting 138 mg/dL PaCO2 25 mm Hg HCO3 29 Meg/L Hb 13.7 g/dL BUN 16 mg/dL act 39.4% Cr 0.9 mg/dL WBE 15 200/mm³ Ca 8.7 mg/dL Lymphocytes 10%  

EPA Pesticide Factsheets

Did you mean: Discussion Question Resource: Laboratory Blood Test Results Laboratory Blood Test Results Arterial Blood Gases 141 Meg/L Mg 1.7 mg/dL pH 7.50 K 4.5 Meg/L PO4 2.9 mg/dL PaO2 59 mm Hg room air Cl 105 Meg/L Glu fasting 138 mg/dL PaCO2 25 mm Hg HCO3 29 Meg/L Hb 13.7 g/dL BUN 16 mg/dL act 39.4% Cr 0.9 mg/dL WBE 15 200/mm³ Ca 8.7 mg/dL Lymphocytes 10% ?

77

In vitro percutaneous absorption of boron as boric acid, borax, and disodium octaborate tetrahydrate in human skin  

Microsoft Academic Search

Literature from the first half of this century reports concern for toxicity from topical use of boric acid, but assessment\\u000a of percutaneous absorption has been impaired by lack of analytical sensitivity. Analytical methods in this study included\\u000a inductively coupled plasmamass spectrometry which now allows quantitation of percutaneous absorption of10B in10B-enriched boric acid, borax and disodium octaborate tetrahydrate (DOT) in biological

Ronald C. Wester; Tracy Hartway; Howard I. Maibach; Michael J. Schell; D. Jack Northington; B. Dwight Culver; Philip L. Strong

1998-01-01

78

Ellipsometric and photocurrent characterization of oxide films formed on copper in borax solution with and without benzotriazol  

Microsoft Academic Search

The effect of the addition of benzotriazol on the passive behaviour of copper in borax solutions was analyzed in the potential region ?0.32 to 0.71 V vs. RHE using voltammetric, photocurrent and ellipsometric techniques. Oxide formation can be explained as a sequence of Cu2O growth (inner layer ippl) and dissolution precipitation of Cu(II), (outer hydrated oxide layer (oppl)). The resulting

J. O. Zerbino

1999-01-01

79

Experimental and theoretical investigation of boric acid production through reactive dissolution of oxalic acid crystals in borax aqueous solution  

Microsoft Academic Search

Reaction of oxalic acid crystals with borax solution was experimentally investigated in a 1.5 L batch reactor at different\\u000a operating conditions. The reaction was fast and took place very near to the surface of solid reactant. The dissolution process\\u000a was found to be bulk diffusion controlled. A surface reaction model considering particle shrinkage was proposed for description\\u000a of the process.

Bahman ZareNezhad

2003-01-01

80

Epoxy-borax-coal tar composition for a radiation protective, burn resistant drum liner and centrifugal casting method  

Microsoft Academic Search

A boron containing burn resistant, low level radiation protection material useful, for example, as a liner for radioactive waste disposal and storage, a component for neutron absorber, and a shield for a neutron source. The material is basically composed of borax in the range of 25-50%, coal tar in the range of 25-37.5%, with the remainder being an epoxy resin

N. W. Boyer; R. S. Taylor

1980-01-01

81

In vitro studies on chemoprotective effect of borax against aflatoxin B1-induced genetic damage in human lymphocytes.  

PubMed

A common dietary contaminant, aflatoxin B1 (AFB1), has been shown to be a potent mutagen and carcinogen in humans and many animal species. Since the eradication of AFB1 contamination in agricultural products has been rare, the use of natural or synthetic free radical scavengers could be a potential chemopreventive strategy. Boron compounds like borax (BX) and boric acid are the major components of industry and their antioxidant role has recently been reported. In the present report, we evaluated the capability of BX to inhibit the rate of micronucleus (MN) and sister chromatid exchange (SCE) formations induced by AFB1. There were significant increases (P < 0.05) in both SCE and MN frequencies of cultures treated with AFB1 (3.12 ppm) as compared to controls. However, co-application of BX (1, 2 and 5 ppm) and AFB1 resulted in decreases of SCE and MN rates as compared to the group treated with AFB1 alone. Borax gave 30-50 % protection against AFB1 induced SCEs and MNs. In conclusion, the support of borax was especially useful in aflatoxin-toxicated blood tissue. Thus, the risk on target tissues of AFB1 could be reduced and ensured early recovery from its toxicity. PMID:22526492

Turkez, Hasan; Geyiko?lu, Fatime; Dirican, Ebubekir; Tatar, Abdulgani

2012-12-01

82

Mg- and K-bearing borates and associated evaporites at Eagle Borax spring, Death Valley, California: A spectroscopic exploration  

USGS Publications Warehouse

Efflorescent crusts at the Eagle Borax spring in Death Valley, California, contain an array of rare Mg and K borate minerals, several of which are only known from one or two other localities. The Mg- and/or K-bearing borates include aristarainite, hydroboracite, kaliborite, mcallisterite, pinnoite, rivadavite, and santite. Ulexite and probertite also occur in the area, although their distribution is different from that of the Mg and K borates. Other evaporite minerals in the spring vicinity include halite, thenardite, eugsterite, gypsum-anhydrite, hexahydrite, and bloedite. Whereas the first five of these minerals are found throughout Death Valley, the last two Mg sulfates are more restricted in occurrence and are indicative of Mg-enriched ground water. Mineral associations observed at the Eagle Borax spring, and at many other borate deposits worldwide, can be explained by the chemical fractionation of borate-precipitating waters during the course of evaporative concentration. The Mg sulfate and Mg borate minerals in the Eagle Borax efflorescent crusts point to the fractionation of Ca by the operation of a chemical divide involving Ca carbonate and Na-Ca borate precipitation in the subsurface sediments. At many other borate mining localities, the occurrence of ulexite in both Na borate (borax-kernite) and Ca borate (ulexite-colemanite) deposits similarly reflects ulexite's coprecipitation with Ca carbonate at an early concentration stage. Such ulexite may perhaps be converted to colemanite by later reaction with the coexisting Ca carbonate - the latter providing the additional Ca2+ ions needed for the conversion. Mg and Ca-Mg borates are the expected late-stage concentration products of waters forming ulexite-colemanite deposits and are therefore most likely to occur in the marginal zones or nearby mud facies of ulexite-colemanite orebodies. Under some circumstances, Mg and Ca-Mg borates might provide a useful prospecting guide for ulexite-colemanite deposits, although the high solubility of Mg borate minerals may prevent their formation in lacustrine settings and certainly inhibits their geologic preservation. The occurrence of Mg borates in borax-kernite deposits is also related to fractionation processes and points to the operation of an Mg borate chemical divide, characterized by Mg borate precipitation ahead of Mg carbonate. All of these considerations imply that Mg is a significant chemical component of many borate-depositing ground waters, even though Mg borate minerals may not be strongly evident in borate orebodies. The Eagle Borax spring borates and other evaporite minerals were studied using spectroscopic and X-ray powder diffraction methods, which were found to be highly complementary. Spectral reflectance measurements provide a sensitive means for detecting borates present in mixtures with other evaporites and can be used to screen samples rapidly for X-ray diffraction analysis. The apparently limited occurrence of Mg and K borate minerals compared to Ca and Na borates may stem partly from the inefficiency of X-ray diffraction methods for delineating the mineralogy of large and complex deposits. Spectral reflectance measurements can be made in the laboratory, in the field, on the mine face, and even remotely. Reflectance data should have an important role in studies of existing deposit mineralogy and related chemical fractionation processes, and perhaps in the discovery of new borate mineral resources.

Crowley, J. K.

1996-01-01

83

Preparing high- and low-aspect ratio AlB 2 flakes from borax or boron oxide  

Microsoft Academic Search

The commercial preparation of aluminum-diboride flakes in aluminum relies on relatively expensive starting materials. A new\\u000a synthesis has been developed that allows AlB2 to be prepared directly from the reaction of borax (Na2B4O710H2O) or boron oxide (B2O3) with aluminum. Aluminum metal at temperatures higher than 900C has been shown to reduce these boron-containing compounds,\\u000a producing an Al2O3-containing slag and AlB2.

A. C. Hall; J. Economy

2000-01-01

84

RATIONAL ALGEBRA AND MM FUNCTIONS  

Microsoft Academic Search

MM functions, formed by finite composition of the operators min, max and translation, represent discrete-event systems involving disjunction, conjunction and delay. The paper shows how they may be formulated as homogeneous rational algebraic functions of degree one, over (max,+) algebra, and reviews the properties of such homogeneous functions, illustrated by some orbit-stability problems.

Ray A. Cuninghame-Green

85

50-mm MEMS deformable mirror  

NASA Astrophysics Data System (ADS)

A 50 mm diameter micromachined membrane mirror was designed and manufactured at TU Delft/DIMES in the framework of ESA's technology research program on adaptive optics. Equipped with 39 actuator electrodes the membrane mirror can be electrostatically deformed and used as a wavefront corrector. Functional and performance tests were carried out at Dornier Satellitensysteme GmbH to show its suitability for quasi- static correction of low-order aberrations caused by thermal and gravitational stresses in the future generation of large space telescopes.

Manhart, Sigmund; Hupfer, Werner J.; Nikolov, Susanne; Wuehrer, Christian; Vdovin, Gleb V.; Sodnik, Zoran

2000-07-01

86

pH Protocol  

NSDL National Science Digital Library

The purpose of this resource is to measure the pH of water. Students use either a pH meter or pH paper to measure the pH. If using the pH meter, the meter needs to be calibrated with buffer solutions that have pH values of 4, 7, and 10.

The GLOBE Program, UCAR (University Corporation for Atmospheric Research)

2005-06-02

87

Accidental mold\\/termite testing of high density fiberboard (HDF) treated with boric acid, borax and N'-N-naphthoylhydroxylamine (NHA)  

Microsoft Academic Search

High density fibreboard (HDF) was made from beech and pine furnish (50:50) and treated with boric acid (0.1-3%), borax (0.1-3%) or N'-N-(1,8-naphthalyl) hydroxylamine (NHA) (0.1-1%) prior to gluing with urea formaldehyde (UF) resin in order to determine resistance to Eastern subterranean termites ( Reticulitermes flavipes Kollar), the most economically important termite species in North America. HDF and southern yellow pine

S. Nami Kartal; Harold S. Burdsall; Frederick Green Ill

88

DETERMINATION OF REFRACTORY METALS IN FERROUS ALLOYS AND HIGH-ALLOY STEEL BY THE BORAX DISK X-RAY SPECTROCHEMICAL METHOD  

Microsoft Academic Search

X-ray spectrochemical methods were developed for the determination of ; Mo, W, Nb, and Ta in heat-resisting and corrosion-resisting alloys and of Mo and ; W in high-alloy steel. The refractory metals are separated from the bulk of the ; alloy matrix by convertional chemical separations, converted to oxides, fused in ; borax, and then determined by x-ray spectrochemical analysis.

C. L. Luke

1963-01-01

89

Functional photoacoustic microscopy of pH  

NASA Astrophysics Data System (ADS)

pH is a tightly regulated indicator of metabolic activity. In mammalian systems, imbalance of pH regulation may result from or result in serious illness. Even though the regulation system of pH is very robust, tissue pH can be altered in many diseases such as cancer, osteoporosis and diabetes mellitus. Traditional high-resolution optical imaging techniques, such as confocal microscopy, routinely image pH in cells and tissues using pH sensitive fluorescent dyes, which change their fluorescence properties with the surrounding pH. Since strong optical scattering in biological tissue blurs images at greater depths, high-resolution pH imaging is limited to penetration depths of 1mm. Here, we report photoacoustic microscopy (PAM) of commercially available pH-sensitive fluorescent dye in tissue phantoms. Using both opticalresolution photoacoustic microscopy (OR-PAM), and acoustic resolution photoacoustic microscopy (AR-PAM), we explored the possibility of recovering the pH values in tissue phantoms. In this paper, we demonstrate that PAM was capable of recovering pH values up to a depth of 2 mm, greater than possible with other forms of optical microscopy.

Chatni, M. Rameez; Yao, Junjie; Danielli, Amos; Favazza, Christopher P.; Maslov, Konstantin I.; Wang, Lihong V.

2012-02-01

90

In vivo models of multiple myeloma (MM).  

PubMed

The development of the plasma cell tumor (PCT) model was the first widely accepted in vivo model of multiple myeloma (MM). Potter and colleagues used this chemically induced PCT model to study the pathophysiology of malignant plasma cells and also used it to screen anti-MM agents. Two decades later the C57BL/KaLwRij mouse strain was found to spontaneously develop MM. Testing of pamidronate using this endogenously arising MM model revealed significant reductions in MM-associated bone disease, which was subsequently confirmed in human trials in MM patients. Transgenic models have also been developed in which the MM is localized in the bone marrow causing lytic bone lesions. Experiments in a transgenic model showed that a new oral proteasome inhibitor was effective at reducing MM burden. A clinical trial later confirmed this observation and validated the model. The xenograft model has been used to grow human MM in immunocompromised mice. The xenograft models of MM have been very useful in optimizing drug schedules and doses, which have helped in the treatments given to MM patients. However, in vivo models have been criticized for having a low clinical predictive power of new chemical entities (NCEs). Despite this, the knowledge gained from in vivo models of MM has without a doubt benefited MM patients. PMID:24704250

Sanchez, Eric; Chen, Haiming; Berenson, James R

2014-06-01

91

GOI characterization of 300-mm furnace tools  

Microsoft Academic Search

The purpose of this characterization was to gain an initial understand of the gate oxide integrity (GOI) differences on wafers processed in the 300mm furnace tools at SC300, a joint venture between Motorola and Infineon Technologies for 300mm wafer, process and equipment development, compared to similarly processed 200mm wafers at Motorola. Measurements were done using mercury probe tools located at

Karl E. Mautz

2002-01-01

92

A 5 mm ×5 mm ×1.37 mm hermetic FBAR duplexer for PCS handsets with wafer-scale packaging  

Microsoft Academic Search

We describe the design and measured performance of a 5 mm ×5 mm ×1.37 mm antenna duplexer for the U.S. PCS band (Tx: 1850-1910 MHz, Rx: 1930-1990 MHz) for cellular handsets based on FBAR (film acoustic resonator) technology. The FBARs are fabricated in a silicon-based IC process technology and are hermetically sealed in a wafer-level packaging process. Two dice, Tx

P. D. Bradley; R. Ruby; A. Barfknecht; F. Geefay; C. Han; G. Gan; Y. Oshmyansky

2002-01-01

93

Functional photoacoustic microscopy of pH  

PubMed Central

pH is a tightly regulated indicator of metabolic activity. In mammalian systems, an imbalance of pH regulation may result from or result in serious illness. In this paper, we report photoacoustic microscopy (PAM) of a commercially available pH-sensitive fluorescent dye (SNARF-5F carboxylic acid) in tissue phantoms. We demonstrated that PAM is capable of pH imaging in absolute values at tissue depths of up to 2.0 mm, greater than possible with other forms of optical microscopy.

Chatni, Muhammad Rameez; Yao, Junjie; Danielli, Amos; Favazza, Christopher P.; Maslov, Konstantin I.; Wang, Lihong V.

2011-01-01

94

Understanding pH  

NSDL National Science Digital Library

The first site related to pH is from the Horiba corporate Web site entitled the Story of pH (1). Visitors can learn what pH is and how it's measured, explore various facts about pH, and read several anecdotes such as "Is the Rain in Our Cities Acidic." The site contains simple text, attractive graphics, and a well-designed layout making it fun and easy for anyone to explore. The second site from the Miami Museum of Science is called the pH Factor (2) kids activity page. This interactive and extensive site contains lessons on testing items for pH, tasting acids and bases, an interactive meter to find the pH of common household items, and much more. Next, is the pH and Water Quality (3) page, which is part of the State of Kentucky Division of Water Web site. The site provides a table of the effects of pH on fish and aquatic life and gives a short description of the most significant environmental impacts of pH. Trout for example, can tolerate a pH range between 4.1 and 9.5 while Mosquito larvae can survive within the 3.3 and 4.7 range. The fourth site from Gardengate Magazine.com is entitled More Soil Stuff: Soil pH (4). Described is the pH range of most soil types, requirements of certain plants, how to test soil for pH, and how to adjust it using sulfur and limestone. Seaworld.org maintains the Understanding the pH Cycle within the Aquarium (5) lesson plan site. The stated objective of the activity is to have students define pH, explain how it affects a tank's water quality, and test the pH level in a classroom aquarium. Although an aquarium is obviously needed, the activity offers a unique and fun way for kids to learn about this basic chemistry concept. About.com offers the next site, which is an interactive pH calculator called pH (6). Users simply enter a pH to get the concentration of Hydrogen ions or, conversely, the Hydrogen ion concentration to get the pH. Another tool to learn about pH and Hydrogen ions is called Acids and Alkalis--the pH Scale (7). Provided by Purchon.com, the interactive pH scale illustrates how the ion concentration changes with pH, common acids associated with each, and whether it is a weak or strong acid or alkali. The last site maintained by the National Park Service is called Acid Rain Lesson Plan: Activity 1 The pH Scale (8). Kids will be able to describe the pH scale and its components, explain why a pH measurement must be accurate, and explain why small changes in pH are important. Everything needed to complete the activity is provided, including a materials list, complete instructions, thinking questions, as well as links for further information.

Brieske, Joel A.

95

A Toddler's Treatment of "Mm" and "Mm Hm" in Talk with a Parent  

ERIC Educational Resources Information Center

The study to be reported in this paper examined the work accomplished by "mm" and "mm hm" in the interactions of a parent and his daughter aged 0;10-2;0. Using the findings of Gardner (2001) for adults, the analysis shows that "mm" accomplished a range of functions based on its sequential placement and prosodic features, whereas "mm hm" was much…

Filipi, Anna

2007-01-01

96

Future 3-mm receivers for the SRT  

Microsoft Academic Search

A fundamental design goal of the Sardinia Radio Telescope is efficient operation in the 3-mm wavelength band. In fact, a lot of design effort is currently being expended to ensure that the telescope will function well at this wavelength. Despite this effort, no receivers for the 3-mm band have yet been specified owing to the pressure of work on other

L. Olmi

2006-01-01

97

MM Algorithms for Some Discrete Multivariate Distributions  

PubMed Central

The MM (minorization–maximization) principle is a versatile tool for constructing optimization algorithms. Every EM algorithm is an MM algorithm but not vice versa. This article derives MM algorithms for maximum likelihood estimation with discrete multivariate distributions such as the Dirichlet-multinomial and Connor–Mosimann distributions, the Neerchal–Morel distribution, the negative-multinomial distribution, certain distributions on partitions, and zero-truncated and zero-inflated distributions. These MM algorithms increase the likelihood at each iteration and reliably converge to the maximum from well-chosen initial values. Because they involve no matrix inversion, the algorithms are especially pertinent to high-dimensional problems. To illustrate the performance of the MM algorithms, we compare them to Newton’s method on data used to classify handwritten digits.

Zhou, Hua; Lange, Kenneth

2010-01-01

98

MM Algorithms for Some Discrete Multivariate Distributions.  

PubMed

The MM (minorization-maximization) principle is a versatile tool for constructing optimization algorithms. Every EM algorithm is an MM algorithm but not vice versa. This article derives MM algorithms for maximum likelihood estimation with discrete multivariate distributions such as the Dirichlet-multinomial and Connor-Mosimann distributions, the Neerchal-Morel distribution, the negative-multinomial distribution, certain distributions on partitions, and zero-truncated and zero-inflated distributions. These MM algorithms increase the likelihood at each iteration and reliably converge to the maximum from well-chosen initial values. Because they involve no matrix inversion, the algorithms are especially pertinent to high-dimensional problems. To illustrate the performance of the MM algorithms, we compare them to Newton's method on data used to classify handwritten digits. PMID:20877446

Zhou, Hua; Lange, Kenneth

2010-09-01

99

Introduction to QM/MM simulations.  

PubMed

Hybrid quantum mechanics/molecular mechanics (QM/MM) simulations have become a popular tool for investigating chemical reactions in condensed phases. In QM/MM methods, the region of the system in which the chemical process takes place is treated at an appropriate level of quantum chemistry theory, while the remainder is described by a molecular mechanics force field. Within this approach, chemical reactivity can be studied in large systems, such as enzymes. In the first part of this contribution, the basic methodology is briefly reviewed. The two most common approaches for partitioning the two subsystems are presented, followed by a discussion on the different ways of treating interactions between the subsystems. Special attention is given on how to deal with situations in which the boundary between the QM and MM subsystems runs through one or more chemical bonds. The second part of this contribution discusses what properties of larger system can be obtained within the QM/MM framework and how. Finally, as an example of a QM/MM application in practice, the third part presents an overview of recent QM/MM molecular dynamics simulations on photobiological systems. In addition to providing quantities that are experimentally accessible, such as structural intermediates, fluorescence lifetimes, quantum yields and spectra, the QM/MM simulations also provide information that is much more difficult to measure experimentally, such as reaction mechanisms and the influence of individual amino acid residues. PMID:23034745

Groenhof, Gerrit

2013-01-01

100

16mm Microfilm Viewing Equipment Guide.  

National Technical Information Service (NTIS)

A descriptive directory is provided of 16mm micorfilm readers and reader-printers that are manufactured or distributed in the United States. General evaluation criteria are provided to assist potential buyers. Manufacturer-provided photographs and detaile...

R. F. Gordon

1971-01-01

101

pH Game  

NSDL National Science Digital Library

The purpose of this resource is to teach students about the acidity levels of liquids and other substances around their school so they understand what pH levels tell us about the environment. Students will create mixtures of water samples, soil samples, plants and other natural materials to better understand the importance of pH levels.

The GLOBE Program, UCAR (University Corporation for Atmospheric Research)

2003-08-01

102

Exercise and Pulmonary Hypertension (PH)  

MedlinePLUS

... International PH News and Projects Let Me Breathe Music Video PATIENTS Patients Newly Diagnosed Request an Envelope ... International PH News and Projects Let Me Breathe Music Video Help spread PH awareness and share PH ...

103

Dark filaments observed at 8.3mm and 3.1mm wavelength  

NASA Technical Reports Server (NTRS)

Mapping of the sun was made at 3.1mm (98 GHz) and 8.3mm (36 GHz) wavelengths with a 45m dish radio telescope at the Nobeyama Cosmic Radio Observatory. The depressions associated with large H alpha filaments are derived to be -0.2 at 8.3mm and -0.05 at 3.1mm, which are darker than the values inferred by Raoult et al. (1979)

Hiel, E.; Ishiguro, M.; Kosugi, T.; Shibasaki, K.

1986-01-01

104

Future 3-mm receivers for the SRT  

NASA Astrophysics Data System (ADS)

A fundamental design goal of the Sardinia Radio Telescope is efficient operation in the 3-mm wavelength band. In fact, a lot of design effort is currently being expended to ensure that the telescope will function well at this wavelength. Despite this effort, no receivers for the 3-mm band have yet been specified owing to the pressure of work on other aspects of the SRT project and to the development of receivers for lower-frequency bands. To address this need, I will briefly re-examine the scientific drivers for the SRT and will also review the capabilities of the SRT and other new-generation millimeter-wave telescopes in order to discuss which strategy will be needed to exploit the full potential of the SRT at 3 mm.

Olmi, L.

105

Interferon-Inducing Characteristics of Mm Virus.  

National Technical Information Service (NTIS)

Interferon induction by MM virus in mice and in L cells was studied. In mice the virus readily induced interferon. The time of appearance was dose-dependent. A large virus dose induced interferon by 4 hr, whereas a small dose resulted in interferon produc...

D. J. Giron F. F. Pindak J. P. Schmidt P. T. Allen

1970-01-01

106

MM-122: High speed civil transport  

NASA Technical Reports Server (NTRS)

The rapidly expanding Pacific Rim market along with other growing markets indicates that the future market potential for a high speed civil transport is great indeed. The MM-122 is the answer to the international market desire for a state of the art, long range, high speed civil transport. It will carry 250 passengers a distance of 5200 nm at over twice the speed of sound. The MM-122 is designed to incorporate the latest technologies in the areas of control systems, propulsions, aerodynamics, and materials. The MM-122 will accomplish these goals using the following design parameters. First, a double delta wing planform with highly swept canards and an appropriately area ruled fuselage will be incorporated to accomplish desired aerodynamic characteristics. Propulsion will be provided by four low bypass variable cycle turbofan engines. A quad-redundant fly-by-wire flight control system will be incorporated to provide appropriate static stability and level 1 handling qualities. Finally, the latest in conventional metallic and modern composite materials will be used to provide desired weight and performance characteristics. The MM-122 incorporates the latest in technology and cost minimization techniques to provide a viable solution to this future market potential.

Demarest, Bill; Anders, Kurt; Manchec, John; Yang, Eric; Overgaard, Dan; Kalkwarf, Mike

1992-01-01

107

Terahertz\\/mm wave imaging simulation software  

Microsoft Academic Search

We have developed a mm wave\\/terahertz imaging simulation package from COTS graphic software and custom MATLAB code. In this scheme, a commercial ray-tracing package was used to simulate the emission and reflections of radiation from scenes incorporating highly realistic imagery. Accurate material properties were assigned to objects in the scenes, with values obtained from the literature, and from our own

M. R. Fetterman; J. Dougherty; W. L. Kiser Jr.

2006-01-01

108

Terahertz/mm wave imaging simulation software  

NASA Astrophysics Data System (ADS)

We have developed a mm wave/terahertz imaging simulation package from COTS graphic software and custom MATLAB code. In this scheme, a commercial ray-tracing package was used to simulate the emission and reflections of radiation from scenes incorporating highly realistic imagery. Accurate material properties were assigned to objects in the scenes, with values obtained from the literature, and from our own terahertz spectroscopy measurements. The images were then post-processed with custom Matlab code to include the blur introduced by the imaging system and noise levels arising from system electronics and detector noise. The Matlab code was also used to simulate the effect of fog, an important aspect for mm wave imaging systems. Several types of image scenes were evaluated, including bar targets, contrast detail targets, a person in a portal screening situation, and a sailboat on the open ocean. The images produced by this simulation are currently being used as guidance for a 94 GHz passive mm wave imaging system, but have broad applicability for frequencies extending into the terahertz region.

Fetterman, M. R.; Dougherty, J.; Kiser, W. L., Jr.

2006-10-01

109

A sensitivity study on spectroscopic parameter accuracies for a mm\\/sub-mm limb sounder instrument  

Microsoft Academic Search

The purpose of this paper is to perform a detailed error analysis for a mm\\/sub-mm limb sounding instrument with respect to spectroscopic parameters. This is done in order to give some insight into the most crucial spectroscopic parameters and to work out a list of recommendations for measurements that would yield the largest possible benefit for an accurate retrieval. The

C. L. Verdes; S. A. Buehler; A. Perrin; J.-M. Flaud; J. Demaison; G. Wlodarczak; J.-M. Colmont; G. Cazzoli; C. Puzzarini

2005-01-01

110

Ph.D. shortage  

NASA Astrophysics Data System (ADS)

The late 1990s will see a shortage of Ph.D. graduates, according to the Association of American Universities, Washington, D.C. AAU's new comprehensive study, “The Ph.D. Shortage: The Federal Role,” reports that competition for new Ph.D.s is already intense and can only intensify because demand is greater than supply in both academic and nonacademic markets.Doctoral education plays an increasingly important role in U.S. research and development programs. Students have a pivotal part in doing research and enriching it with new ideas. The AAU report says that graduate students are “major determinants of the creativity and productivity of U.S. academic research, the source of more than 50% of the nation's basic research.’ The market for doctoral education extends beyond the university. In 1985, about 43% of all Ph.D.s employed in this country were working outside higher education; the demand for doctorate recipients in nonacademic sectors continues to grow.

111

mmView: a web-based viewer of the mmCIF format  

PubMed Central

Background Structural biomolecular data are commonly stored in the PDB format. The PDB format is widely supported by software vendors because of its simplicity and readability. However, the PDB format cannot fully address many informatics challenges related to the growing amount of structural data. To overcome the limitations of the PDB format, a new textual format mmCIF was released in June 1997 in its version 1.0. mmCIF provides extra information which has the advantage of being in a computer readable form. However, this advantage becomes a disadvantage if a human must read and understand the stored data. While software tools exist to help to prepare mmCIF files, the number of available systems simplifying the comprehension and interpretation of the mmCIF files is limited. Findings In this paper we present mmView - a cross-platform web-based application that allows to explore comfortably the structural data of biomacromolecules stored in the mmCIF format. The mmCIF categories can be easily browsed in a tree-like structure, and the corresponding data are presented in a well arranged tabular form. The application also allows to display and investigate biomolecular structures via an integrated Java application Jmol. Conclusions The mmView software system is primarily intended for educational purposes, but it can also serve as a useful research tool. The mmView application is offered in two flavors: as an open-source stand-alone application (available from http://sourceforge.net/projects/mmview) that can be installed on the user's computer, and as a publicly available web server.

2011-01-01

112

Phase Correction for mm-arrays  

NASA Astrophysics Data System (ADS)

Monitoring the line emission from tropospheric water vapor can be used for phase correction of mm and sub-mm signals, since phase fluctuations at these wavelengths are predominantly caused by fluctuations in the distribution of water vapor. We have built a prototype cooled broad band 16-channel radiometer which allows us to measure the shape of the optically thin 22 GHz water vapor line. In the optically thin limit, line intensity and shape information allows the measurement of the total water vapor column and a coarse separation of the altitude distribution of the fluctuating water vapor component. This altitude information can be used to reduce the uncertainties in the conversion between the measured sky fluctuations and the actual phase fluctuations of astronomical signals. The use of a multi channel measurement will allow robust phase corrections over a wide range of weather conditions, including the presence of liquid water clouds. The system that we are building is targeted for implementation on the BIMA array with a goal of path length correction to 35 mu m rms. The system is the low frequency analogy to the 183 GHz system planned for the ALMA array. It will provide valuable experience in high accuracy phase correction.

Staguhn, J.; Harris, A. I.; Mundy, L. G.; Woody, D. P.; Plambeck, R. L.

1999-10-01

113

Viewing the Evolution of Massive Star Formation through FIR\\/Sub-mm\\/mm Eyes  

Microsoft Academic Search

In this paper, we present an overview of our method of constructing a family of models for the far-infrared, sub-millimeter, and millimeter (FIR\\/sub-mm\\/mm) line emission of molecular and atomic gas surrounding massive star formation in starburst galaxies. We show the results of a case study, an expanding supershell centered around a massive star cluster with a particular set of input

Lihong Yao; E. R. Seaquist

2006-01-01

114

The Table Mountain 8-mm wavelength interferometer  

NASA Technical Reports Server (NTRS)

A two-element radio interferometer operating at 8.33-mm wavelength has been developed at the Jet Propulsion Laboratory's Table Mountain Observatory near Wrightwood, CA. The interferometer employs a 5.5-m and a 3-m diameter antenna on an east-west baseline of 60 or 120 m, yielding fringe spacings at transit of 28 or 14 arcsec, respectively. The broad intermediate-frequency bandpass of 100-350 MHz and the system noise temperature of 500 K provide high sensitivity for the measurement of continuum sources. The interferometer has been used for high-resolution studies of the planets and the sun, and it is currently being adapted to study solar flare emissions at high spatial and time resolution.

Janssen, M. A.; Gary, B. L.; Gulkis, S.; Olsen, E. T.; Soltis, F. S.; Yamane, N. I.

1979-01-01

115

SgrA* emission at 7 mm  

NASA Astrophysics Data System (ADS)

SgrA* is a compact radio source coincident with the position of the supermassive black hole at the center of our Galaxy. It is surrounded by a complex of HII regions, known as SgrA. SgrA* presents variable emission, from radio to X-rays, with timescales that range from hours to months. Interferometric observations at frequencies up to 22 GHz have detected a 106 days quasi-periodicity in the light curves of SgrA* (Zhao et al. 2001). In our work, we present the result of 43 GHz (7 mm) single dish observations obtained with the Itapetinga radiotelescope, located in Atibaia, Brazil, during several long lasting campaigns starting in 2006, which aimed to detect variability and verify the existence of periodicity.

Beaklini, P. P. B.; Abraham, Z.

2011-10-01

116

SSC 50 mm dipole cross section  

SciTech Connect

In this paper we present the magnetic design of the two dimensional coil and iron cross section, referred to as DSX201/W6733, for the 50 mm aperture main ring dipole magnet for the Superconducting Super Collider (SSC). The computed values of the allowed field harmonics as a function of current, the quench performance predictions, the stored energy calculations, the effect of random errors on the coil placement and the Lorentz forces on the coil will be presented. The yoke has been optimized to reduce iron saturation effects on the field harmonics. We shall present the summary of this design which will include the expected overall performance of this cross section. Prototypes of these dipoles are being built at the Brookhaven National Laboratory (BNL) and at the Fermi National Accelerator Laboratory (FNAL). There are slight differences between the cross sections at the two laboratories. 7 refs., 6 figs., 11 tabs.

Gupta, R.C.; Kahn, S.A.; Morgan, G.H.

1991-01-01

117

17-4 PH and 15-5 PH  

NASA Technical Reports Server (NTRS)

17-4 PH and 15-5 PH are extremely useful and versatile precipitation-hardening stainless steels. Armco 17-4 PH is well suited for the magnetic particle inspection requirements of Aerospace Material Specification. Armco 15-5 PH and 17-4 PH are produced in billet, plate, bar, and wire. Also, 15-5 PH is able to meet the stringent mechanical properties required in the aerospace and nuclear industries. Both products are easy to heat treat and machine, making them very useful in many applications.

Johnson, Howard T.

1995-01-01

118

Simulation of Thermal Processes in Metamaterial MM-to-IR Converter for MM-wave Imager  

NASA Astrophysics Data System (ADS)

The main characteristics of MM-wave image detector were simulated by means of accurate numerical modelling of thermophysical processes in a metamaterial MM-to-IR converter. The converter represents a multilayer structure consisting of an ultra thin resonant metamaterial absorber and a perfect emissive layer. The absorber consists of a dielectric self-supporting film that is metallized from both sides. A micro-pattern is fabricated from one side. Resonant absorption of the MM waves induces the converter heating that yields enhancement of IR emission from the emissive layer. IR emission is detected by IR camera. In this contribution an accurate numerical model for simulation of the thermal processes in the converter structure was created by using COMSOL Multiphysics software. The simulation results are in a good agreement with experimental results that validates the model. The simulation shows that the real time operation is provided for the converter thickness less than 3 micrometers and time response can be improved by decreasing of the converter thickness. The energy conversion efficiency of MM waves into IR radiation is over 80%. The converter temperature increase is a linear function of a MM-wave radiation power within three orders of the dynamic range. The blooming effect and ways of its reducing are also discussed. The model allows us to choose the ways of converter structure optimization and improvement of image detector parameters.

Zagubisalo, Peter S.; Paulish, Andrey G.; Kuznetsov, Sergey A.

2014-03-01

119

Evolving Starburst Modeling of FIR\\/sub-mm\\/mm Line Emission. II. Application to M 82  

Microsoft Academic Search

We present starburst models for far-infrared\\/sub-millimeter\\/millimeter\\u000a(FIR\\/sub-mm\\/mm) line emission of molecular and atomic gas in an evolving\\u000astarburst region, which is treated as an ensemble of non-interacting hot\\u000abubbles which drive spherical shells of swept-up gas into a surrounding uniform\\u000agas medium. These bubbles and shells are driven by stellar winds and supernovae\\u000awithin massive star clusters formed during an

Lihong Yao

2009-01-01

120

40 Gbit/s silicon modulators fabricated on 200-mm and 300-mm SOI wafers  

NASA Astrophysics Data System (ADS)

We present 40 Gbit/s optical modulators based on different types of phase shifters (lateral pn, pipin, and interleaved pn junction phase). Those structures were processed both on 200 and 300mm SOI wafers, available in large-scale microelectronic foundries. Both Ring Resonators (RR) and Mach Zehnder (MZ) modulators were fabricated. As an example, MZ modulator based on 0.95 mm long interleaved pn junction phase shifter delivered a high ER of 7.8 dB at 40 Gbit/s with low optical loss of only 4 dB. Ring modulator was also fabricated and characterized at high-speed, exhibiting 40 Gbit/s.

Marris-Morini, Delphine; Baudot, Charles; Fédéli, Jean-Marc; Rasigade, Gilles; Vuillet, Nathalie; Souhaité, Aurélie; Ziebell, Melissa; Rivalin, Pierette; Olivier, Ségolène; Crozat, Paul; Bouville, David; Menezo, Sylvie; Boeuf, Frédéric; Vivien, Laurent

2014-03-01

121

Characterization of 300 mm silicon-polished and EPI wafers  

Microsoft Academic Search

Maturity of 300 mm polished wafers and early epi wafers were evaluated in respects of particles, flatness, metal contamination, and epitaxy thickness. Data of 300 mm polished wafers showed encouraging characteristics comparable to state-of-the-art 200 mm prime wafers. Preliminary characterization of 300 mm epi wafers revealed that dominant localized light scatterers (LLS) with sizes more than 1 ?m were epitaxy

Steven Shih; Chi Au; Zach Yang; Troy Messina; Randal K. Goodall; Howard R. Huff

1999-01-01

122

MASTER: a radiometer for mm and sub-mm observations from the Antarctic Plateau  

NASA Astrophysics Data System (ADS)

A radiometer based on SIS mixers for astrophysical observations is being assembled. The system, cooled to cryogenic temperature by a pulse tube refrigerator, is intended for operation on the Antartic Plateau during the local winter, using the mm dishes available there in the future. The system prototype will be tested at the focus of the 2.6m MITO telescope at the Testa Grigia Observatory on the italian Alps. We discuss the system characteristics and the observational programs.

Boella, G.; Gervasi, M.; Passerini, A.; Sironi, G.; Tartari, A.; Zannoni, M.; Natale, V.

123

40 CFR Table Mm-2 to Subpart Mm of... - Default Factors for Biomass-Based Fuels and Biomass  

Code of Federal Regulations, 2013 CFR

... 2013-07-01 false Default Factors for Biomass-Based Fuels and Biomass MM Table MM-2 to Subpart MM of Part 98 ...to Subpart MM of Part 98âDefault Factors for Biomass-Based Fuels and Biomass Biomass-based...

2013-07-01

124

Comparative analysis between 5 mm and 7.5 mm collimators in CyberKnife radiosurgery for trigeminal neuralgia.  

PubMed

Trigeminal neuralgia (TN) is treated in CyberKnife (Accuray Inc, Sunnyvale, USA) with the 5 mm collimator whose dosimetric inaccuracy is higher than the other available collimators. The 7.5 mm collimator which is having less dosimetric uncertainty can be an alternative for 5 mm collimator provided the dose distribution with 7.5 mm collimator is acceptable. Aim of this study is to analyze the role of 7.5 mm collimator in CyberKnife treatment plans of TN. The treatment plans with 5 mm collimators were re-optimized with 7.5 mm collimator and a bi-collimator system (5 mm and 7.5 mm). The treatment plans were compared for target coverage, brainstem doses, and the dose to normal tissues. The target and brainstem doses were comparable. However, the conformity indices were 2.31 ± 0.52, 2.40 ± 0.87 and 2.82 ± 0.51 for 5 mm, bi-collimator (5mm and 7.5 mm), 7.5 mm collimator plans respectively. This shows the level of dose spillage in 7.5 mm collimator plans. The 6 Gy dose volumes in 7.5 mm plans were 1.53 and 1.34 times higher than the 5 mm plan and the bi-collimator plans respectively. The treatment time parameters were lesser for 7.5 mm collimators. Since, the normal tissue dose is pretty high in 7.5 mm collimator plans, the use of it in TN plans can be ruled out though the treatment time is lesser for these 7.5 mm collimator plans. PMID:24049318

Sudahar, H; Kurup, P G G; Murali, V; Velmurugan, J

2013-07-01

125

Teaching Evolutionary Mechanisms: Genetic Drift and M&M's.  

ERIC Educational Resources Information Center

Describes a classroom activity that teaches the mechanism of genetic drift to undergraduates. Illustrates a number of concepts that are critical in developing evolution literacy by sampling M&M milk chocolate candies. (MM)

Staub, Nancy L.

2002-01-01

126

Simulating surveys of the high-z mm Universe  

NASA Astrophysics Data System (ADS)

The next generation of large single-dish mm and sub-mm (hereafter mm) telescopes (ground-based, balloon-borne, satellites) and interferometers, using new large-format fully-sampled focal-plane arrays, will provide greatly improved mapping speed, sensitivity, wavelength coverage, and resolution.

Chapin, E. L.; Hughes, D. H.; Aragón, M.; Montaña, A.; Gaztañaga, E.; Plionis, M.

2003-06-01

127

The pH Game.  

ERIC Educational Resources Information Center

Describes a game that can be used to teach students about the acidity of liquids and substances around their school and enable them to understand what pH levels tell us about the environment. Students collect samples and measure the pH of water, soil, plants, and other natural material. (DDR)

Chemecology, 1996

1996-01-01

128

Coping with PH over the Long Term  

MedlinePLUS

... International PH News and Projects Let Me Breathe Music Video PATIENTS Patients Newly Diagnosed Request an Envelope ... International PH News and Projects Let Me Breathe Music Video Help spread PH awareness and share PH ...

129

Production and characterization of an extracellular polysaccharide from Streptomyces violaceus MM72.  

PubMed

The isolation, optimization, purification and characterization of an extracellular polysaccharide (EPS) from a marine actinobacterium, Streptomyces violaceus MM72 were investigated. Medium composition and culture conditions for the EPS production by S. violaceus MM72 were optimized using two statistical methods: Plackett-Burman design applied to find the key ingredients and conditions for the best yield of EPS production and central composite design used to optimize the concentration of the three significant variables: glucose, tryptone and NaCl. The preferable culture conditions for EPS production were pH 7.0, temperature 35°C and NaCl concentration 2.0% for 120h with fructose and yeast extract as best carbon and nitrogen sources, respectively. The results showed that S. violaceus MM72 produced a kind of EPS having molecular weight of 8.96×10(5)Da. In addition, the EPS showed strong DPPH radical-scavenging activity, superoxide scavenging and metal chelating activities while moderate inhibition of lipid peroxidation and reducing activities determined in this study. These results showed the great potential of EPS produced by S. violaceus MM72 could be used in industry in place of synthetic compounds. The EPS from S. violaceus MM72 may be a new source of natural antioxidants with potential value for health, food and therapeutics. PMID:23597709

Manivasagan, Panchanathan; Sivasankar, Palaniappan; Venkatesan, Jayachandran; Senthilkumar, Kalimuthu; Sivakumar, Kannan; Kim, Se-Kwon

2013-08-01

130

Extracellular pH modulates GABAergic neurotransmission in rat hypothalamus.  

PubMed

Changes in extracellular pH have a modulatory effect on GABAA receptor function. It has been reported that pH sensitivity of the GABA receptor is dependent on subunit composition and GABA concentration. Most of previous investigations focused on GABA-evoked currents, which only reflect the postsynaptic receptors. The physiological relevance of pH modulation of GABAergic neurotransmission is not fully elucidated. In the present studies, we examined the influence of extracellular pH on the GABAA receptor-mediated inhibitory neurotransmission in rat hypothalamic neurons. The inhibitory postsynaptic currents (IPSCs), tonic currents, and the GABA-evoked currents were recorded with whole-cell patch techniques on the hypothalamic slices from Sprague-Dawley rats at 15-26 postnatal days. The amplitude and frequency of spontaneous GABA IPSCs were significantly increased while the external pH was changed from 7.3 to 8.4. In the acidic pH (6.4), the spontaneous GABA IPSCs were reduced in amplitude and frequency. The pH induced changes in miniature GABA IPSCs (mIPSCs) similar to that in spontaneous IPSCs. The pH effect on the postsynaptic GABA receptors was assessed with exogenously applied varying concentrations of GABA. The tonic currents and the currents evoked by sub-saturating concentration of GABA ([GABA]) (10?M) were inhibited by acidic pH and potentiated by alkaline pH. In contrast, the currents evoked by saturating [GABA] (1mM) were not affected by pH changes. We also investigated the influence of pH buffers and buffering capacity on pH sensitivity of GABAA receptors on human recombinant ?1?2?2 GABAA receptors stably expressed in HEK 293 cells. The pH influence on GABAA receptors was similar in HEPES- and MES-buffered media, and not dependent on protonated buffers, suggesting that the observed pH effect on GABA response is a specific consequence of changes in extracellular protons. Our data suggest that the hydrogen ions suppress the GABAergic neurotransmission, which is mediated by both presynaptic and postsynaptic mechanisms. PMID:24780768

Chen, Z-L; Huang, R-Q

2014-06-20

131

Philip Prorok, PhD  

Cancer.gov

Philip Prorok, PhD, mirum est notare quam littera gothica, quam nunc putamus parum claram, anteposuerit litterarum formas humanitatis per seacula quarta decima et quinta decima. Eodem modo typi, qui nunc nobis videntur parum clari, fiant sollemnes in futurum.

132

Dissolution kinetics of a lunar glass simulant at 25 °C: The effect of pH and organic acids  

Microsoft Academic Search

The dissolution kinetics of a simulated lunar glass were examined at pH 3, 5, and 7. Additionally, the pH 7 experiments were conducted in the presence of citric and oxalic acid at concentrations of 2 and 20 mM. The organic acids were buffered at pH 7 to examine the effect of each molecule in their dissociated form. At pH 3,

M. J. Eick; P. R. Grossl; D. C. Golden; D. L. Sparks; D. W. Ming

1996-01-01

133

PhEDEx Data Service  

NASA Astrophysics Data System (ADS)

The PhEDEx Data Service provides access to information from the central PhEDEx database, as well as certificate-authenticated managerial operations such as requesting the transfer or deletion of data. The Data Service is integrated with the "SiteDB" service for fine-grained access control, providing a safe and secure environment for operations. A plug-in architecture allows server-side modules to be developed rapidly and easily by anyone familiar with the schema, and can automatically return the data in a variety of formats for use by different client technologies. Using HTTP access via the Data Service instead of direct database connections makes it possible to build monitoring web-pages with complex drill-down operations, suitable for debugging or presentation from many aspects. This will form the basis of the new PhEDEx website in the near future, as well as providing access to PhEDEx information and certificate-authenticated services for other CMS dataflow and workflow management tools such as CRAB, WMCore, DBS and the dashboard. A PhEDEx command-line client tool provides one-stop access to all the functions of the PhEDEx Data Service interactively, for use in simple scripts that do not access the service directly. The client tool provides certificate-authenticated access to managerial functions, so all the functions of the PhEDEx Data Service are available to it. The tool can be expanded by plug-ins which can combine or extend the client-side manipulation of data from the Data Service, providing a powerful environment for manipulating data within PhEDEx.

Egeland, Ricky; Wildish, Tony; Huang, Chih-Hao

2010-04-01

134

Is smaller better? Comparison of 3-mm and 5-mm leaf size for stereotactic radiosurgery: A dosimetric study  

SciTech Connect

Purpose: To perform a dosimetric comparison of a minimal 3-mm leaf width multileaf collimator (MLC) and a minimal 5-mm MLC in dynamic conformal arc stereotactic radiosurgery for treatment of intracranial lesions. Methods and Materials: The treatment plans of 23 patients previously treated for intracranial lesions in our institution were redone using the BrainSCAN, version 5.3, stereotactic radiosurgery treatment planning system (BrainLAB). For each case, two dynamic conformal arc plans were generated: one using a minimal 3-mm micro-MLC (BrainLAB, Novalis) and one using a minimal 5-mm MLC (Varian Millennium). All arc parameters were the same in each of the two plans, except for the collimator angle settings. The collimator angle settings were optimized for each arc in each plan. A peritumoral rind structure (1 cm) was created to evaluate normal tissue sparing immediately adjacent to the target volume. Conformity indexes (CIs) were calculated for each plan. The dependence of normal tissue sparing and target conformity on target volume (TV) was determined. Results: The TV was 0.14-36.32 cm{sup 3} (median, 5.90). The CI was 1.22-2.60 (median, 1.51) for the 3-mm micro-MLC and 1.23-2.69 (median, 1.60) for the 5-mm MLC. Despite this small difference, it was a statistically significant increase (p < 0.0001) for the 5-mm MLC compared with the 3-mm micro-MLC. Improved normal tissue sparing was demonstrated using the 3-mm micro-MLC compared with the 5-mm MLC by examining the peritumoral rind volumes (PRVs) receiving 50% (PRV{sub 5}), 80% (PRV{sub 8}), and 90% (PRV{sub 9}) of the prescription dose. The reduction in the PRV{sub 5}, PRV{sub 8}, and PRV{sub 9} for the 3-mm micro-MLC compared with the 5-mm MLC was 13.5%, 12.9%, and 11.5%, respectively. The CI decreased with a larger TV, as did the difference in the CIs between the 3-mm micro-MLC and 5-mm MLC. A reduction in the PRV increased with larger TVs. Conclusion: The 3-mm micro-MLC provided better target conformity and greater normal tissue sparing than the 5-mm MLC in stereotactic radiosurgery using dynamic conformal arcs. These differences were small but consistent in the patients examined. Future research is needed to determine whether this small improvement can yield a clinical impact on patient care.

Chern, Shyh-shi [Department of Radiation Oncology, University of Utah School of Medicine, Salt Lake City, Utah (United States)]. E-mail: Richard.Chern@hci.utah.edu; Leavitt, Dennis D. [Department of Radiation Oncology, University of Utah School of Medicine, Salt Lake City, Utah (United States); Jensen, Randy L. [Department of Neurosurgery, University of Utah School of Medicine, Salt Lake City, Utah (United States); Shrieve, Dennis C. [Department of Radiation Oncology, University of Utah School of Medicine, Salt Lake City, Utah (United States)

2006-11-15

135

Synopsis of Tests Demonstrating Improvements in 175mm Forgings.  

National Technical Information Service (NTIS)

Contributing to the improved quality of the 175mm gun tubes have been (a) elimination of chrome-plating of exceptionally high strength 175mm M113 material, (b) reduction of yield strength to effect significantly higher toughness, (c)improving quality of f...

E. N. Hegge

1969-01-01

136

Temperature, classification and dewatering in 10 mm hydrocyclones  

Microsoft Academic Search

Small diameter hydrocyclones have had an increasing use in performing difficult phase separations in many industries. Further, these 10 mm diameter hydrocyclones also have the potential to be applied to fine particle classification, in particular to collect the sub-micron fraction.The key operating parameters that affect the dewatering and classification performance of 10 mm hydrocyclones are the operating pressure and feed

J. J. Cilliers; L. Diaz-Anadon; F. S. Wee

2004-01-01

137

Assessing the performance of MM/PBSA and MM/GBSA methods. 4. Accuracies of MM/PBSA and MM/GBSA methodologies evaluated by various simulation protocols using PDBbind data set.  

PubMed

By using different evaluation strategies, we systemically evaluated the performance of Molecular Mechanics/Generalized Born Surface Area (MM/GBSA) and Molecular Mechanics/Poisson-Boltzmann Surface Area (MM/PBSA) methodologies based on more than 1800 protein-ligand crystal structures in the PDBbind database. The results can be summarized as follows: (1) for the one-protein-family/one-binding-ligand case which represents the unbiased protein-ligand complex sampling, both MM/GBSA and MM/PBSA methodologies achieve approximately equal accuracies at the interior dielectric constant of 4 (with rp = 0.408 ± 0.006 of MM/GBSA and rp = 0.388 ± 0.006 of MM/PBSA based on the minimized structures); while for the total dataset (1864 crystal structures), the overall best Pearson correlation coefficient (rp = 0.579 ± 0.002) based on MM/GBSA is better than that of MM/PBSA (rp = 0.491 ± 0.003), indicating that biased sampling may significantly affect the accuracy of the predicted result (some protein families contain too many instances and can bias the overall predicted accuracy). Therefore, family based classification is needed to evaluate the two methodologies; (2) the prediction accuracies of MM/GBSA and MM/PBSA for different protein families are quite different with rp ranging from 0 to 0.9, whereas the correlation and ranking scores (an averaged rp/rs over a list of protein folds and also representing the unbiased sampling) given by MM/PBSA (rp-score = 0.506 ± 0.050 and rs-score = 0.481 ± 0.052) are comparable to those given by MM/GBSA (rp-score = 0.516 ± 0.047 and rs-score = 0.463 ± 0.047) at the fold family level; (3) for the overall prediction accuracies, molecular dynamics (MD) simulation may not be quite necessary for MM/GBSA (rp-minimized = 0.579 ± 0.002 and rp-1ns = 0.564 ± 0.002), but is needed for MM/PBSA (rp-minimized = 0.412 ± 0.003 and rp-1ns = 0.491 ± 0.003). However, for the individual systems, whether to use MD simulation is depended. (4) both MM/GBSA and MM/PBSA may be unable to give successful predictions for the ligands with high formal charges, with the Pearson correlation coefficient ranging from 0.621 ± 0.003 (neutral ligands) to 0.125 ± 0.142 (ligands with a formal charge of 5). Therefore, it can be summarized that, although MM/GBSA and MM/PBSA perform similarly in the unbiased dataset, for the currently available crystal structures in the PDBbind database, compared with MM/GBSA, which may be used in multi-target comparisons, MM/PBSA is more sensitive to the investigated systems, and may be more suitable for individual-target-level binding free energy ranking. This study may provide useful guidance for the post-processing of docking based studies. PMID:24999761

Sun, Huiyong; Li, Youyong; Tian, Sheng; Xu, Lei; Hou, Tingjun

2014-07-16

138

Call-graph-based inter-class MM path generation  

NASA Astrophysics Data System (ADS)

Inter-class testing is the testing of classes for composing an object-oriented system or subsystem during integration. MM Path is defined as an interleaved sequence of method executions linked by messages. It represents the interactions between methods in object-oriented software well, hence fits for object-oriented integration testing. However, the current MM Path generation methods only support intra-class testing. In this paper, a call-graph-based approach is proposed to promote MM Path automatic generation from intra-class to inter-class level. The approach is evaluated by controlled experiments on 12 Java benchmark programs with two typical call graph construction algorithms, Class Hierarchy Analysis and Anderson's Points-to Analysis. Then, the impact of the two algorithms on inter-class MM path generation efficiency is studied. The result shows that our approach is practicable and Anderson's Points-to Analysis outperforms Class Hierarchy Analysis for inter-class MM Path generation.

He, Wei; Zhao, Ruilian

2011-12-01

139

Acetate biodegradation by anaerobic microorganisms at high pH and high calcium concentration.  

PubMed

Acetate biodegradation at a high pH and a high calcium concentration was examined to clarify the effect of bacterial activity on the migration of organic (14)C compounds in cementitious repositories. Tamagawa river sediment or Teganuma pond sediment was anaerobically cultured with 5 mM acetate and 10 mM nitrate at pH 9.5-12 at 30 °C. After 20 and 90 days, the acetate concentration of the culture medium was analyzed and found to have decreased below 5 mM at pH ? 11. On the other hand, it did not decrease when either sediment was incubated in the absence of nitrate. These results suggest that nitrate-reducing bacteria can biodegrade acetate under more alkaline conditions than the reported pH range in which nitrate-reducing bacteria can exhibit activity. Acetate biodegradation was also examined at a high calcium concentration. Sediments were anaerobically cultured at pH 9.5 with 5 mM acetate and 10 mM nitrate in solution, equilibrated with ordinary Portland cement hydrate, in which the Ca concentration was 14.6 mM. No decrease in acetate concentration after incubation of the sediments was observed, nor was it lower than in the absence of cementitious composition, suggesting that kinetics of acetate biodegradation by anaerobic microorganisms is lowered by a high Ca concentration. PMID:21130545

Yoshida, Takahiro

2011-02-01

140

40 CFR Table Mm-1 to Subpart Mm of... - Default Factors for Petroleum Products and Natural Gas Liquids 1 2  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Default Factors for Petroleum Products and Natural Gas Liquids 1 2...GREENHOUSE GAS REPORTING Suppliers of Petroleum Products Pt. 98, Subpt. MM, Table...MM of Part 98âDefault Factors for Petroleum Products and Natural Gas Liquids 1...

2013-07-01

141

The 19 mm data recorders similarities and differences  

NASA Technical Reports Server (NTRS)

Confusion over the use of non-video 19 mm data recorders is becoming more pronounced as we enter the world of high performance computing. This paper addresses the following: the differences between ID-1, ID-2, MIL-STD-2179 and DD-2; what the proper machine is for various applications; how the machine can be integrated into an environment; and any misconceptions there might be about 19 mm tape recorders. DD-2 and 19 mm instrumentation recorders have missions for which each is well designed. While the differences may appear subtle, understanding the difference between the two is the key to picking the right recorder for a particular application.

Atkinson, Steve

1992-01-01

142

Thermal stability of recombinant green fluorescent protein (GFPuv) at various pH values  

Microsoft Academic Search

The thermal stability of the recombinant green fluorescent protein (GFPuv) expressed by Escherichia coli cells and isolated by three-phase partitioning extraction with hydrophobic interaction chromatography was studied. The GFPuv\\u000a (3.5–9.0 ?g of GFPuv\\/mL) was exposed to various pH conditions (4.91–9.03) and temperatures (75–95C) in the 10 mM buffers: acetate (pH 5.0–7.0), phosphate (pH 5.5–8.0), and Tris-HCl (pH 7.0–9.0). The extent

Thereza Christina Vessoni Penna; Marina Ishii; Adalberto Pessoa Junior; Olivia Cholewa

2004-01-01

143

Radka Stoyanova, PhD  

Cancer.gov

Dr. Radka Stoyanova, PhD has extensive background in developing approaches to best utilize imaging techniques in cancer research, diagnosis and treatment, as well as in developing approaches for the analysis, mining, and interpretation of "big data" generated by high-throughput approaches such as genomics, proteomics, and metabolomics. She received her Masters Degree in Mathematics from the University of Sofia, Bulgaria. Dr. Stoyanova obtained her doctoral training and PhD degree at the Imperial College London, under the mentorship of Profs.

144

pH Optrode Instrumentation  

NASA Technical Reports Server (NTRS)

pH-sensitive chromophoric reagents immobilized in porous optical fibers. Optoelectronic instrumentation system measures acidity or alkalinity of aqueous nutrient solution. Includes one or more optrodes, which are optical-fiber chemical sensors, in sense, analogous to electrodes but not subject to some of spurious effects distorting readings taken by pH electrodes. Concept of optrodes also described in "Ethylene-Vapor Optrodes" (KSC-11579). pH optrode sensor head, with lead-in and lead-out optical fibers, convenient for monitoring solutions located away from supporting electronic equipment.

Tabacco, Mary Beth; Zhou, Quan

1995-01-01

145

Development of Alternate 7.62mm Tracer Formulations.  

National Technical Information Service (NTIS)

Task Order No. 0001, Development of Alternate 7.62mm Tracer Formulations, addresses several shortcomings of the currently fielded red-orange bullet tracers, including performance in adverse weather conditions and performance with night vision equipment. T...

S. M. Buc G. Adelman S. Adelman

1993-01-01

146

Building 1204, oblique view to east, 90 mm lens. ...  

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

Building 1204, oblique view to east, 90 mm lens. - Travis Air Force Base, Squadron Operations & Readiness Crew Facility, W Street, Armed Forces Special Weapons Project Q Area, Fairfield, Solano County, CA

147

Building 931, oblique view to northwest, 210 mm lens. ...  

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

Building 931, oblique view to northwest, 210 mm lens. - Travis Air Force Base, Central Battery Charging Building, North of W Street, Armed Forces Special Weapons Project Q Area, Fairfield, Solano County, CA

148

Building 931, oblique view to southeast, 135 mm lens. ...  

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

Building 931, oblique view to southeast, 135 mm lens. - Travis Air Force Base, Central Battery Charging Building, North of W Street, Armed Forces Special Weapons Project Q Area, Fairfield, Solano County, CA

149

Building 1204, oblique view to west, 135 mm lens. ...  

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

Building 1204, oblique view to west, 135 mm lens. - Travis Air Force Base, Squadron Operations & Readiness Crew Facility, W Street, Armed Forces Special Weapons Project Q Area, Fairfield, Solano County, CA

150

Building 904, oblique view to northeast, 210mm lens Travis ...  

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

Building 904, oblique view to northeast, 210mm lens - Travis Air Force Base, Base Spares Warehouse No. 1, Dixon Avenue & W Street, Armed Forces Special Weapons Project Q Area, Fairfield, Solano County, CA

151

Building 904, oblique view to northwest, 135 mm lens ...  

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

Building 904, oblique view to northwest, 135 mm lens - Travis Air Force Base, Base Spares Warehouse No. 1, Dixon Avenue & W Street, Armed Forces Special Weapons Project Q Area, Fairfield, Solano County, CA

152

Building 909, oblique view to southeast, 135 mm lens. Building ...  

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

Building 909, oblique view to southeast, 135 mm lens. Building 908 at extreme right for context. - Travis Air Force Base, Handling Crew Building, North of W Street, Armed Forces Special Weapons Project Q Area, Fairfield, Solano County, CA

153

Building 904, oblique view to southeast, 135 mm lens. ...  

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

Building 904, oblique view to southeast, 135 mm lens. - Travis Air Force Base, Base Spares Warehouse No. 1, Dixon Avenue & W Street, Armed Forces Special Weapons Project Q Area, Fairfield, Solano County, CA

154

Building 932, oblique view to northwest, 90 mm lens. Building ...  

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

Building 932, oblique view to northwest, 90 mm lens. Building 933-935 at extreme left. - Travis Air Force Base, Nuclear Weapons Assembly Plant 5, W Street, Armed Forces Special Weapons Project Q Area, Fairfield, Solano County, CA

155

Feasibility Assessment of Conceptual 105-mm M68 Composite Tubes.  

National Technical Information Service (NTIS)

A study is reported in which the thermal, stress, fabrication, durability, and weapon interface problems associated with implementation of composite materials in a 105-mm M68 tube configuration are evaluated. It is shown that thermal factors associated wi...

F. A. Vassallo C. C. Morphy

1986-01-01

156

The 19 mm date recorders: Similarities and differences  

NASA Technical Reports Server (NTRS)

Confusion over the use of non-video 19 mm data recorders is becoming more pronounced in the world of high performance computing. The following issues are addressed: (1) the difference between ID-1, ID-2, MIL-STD-2179, and DD-2; (2) the proper machine for the necessary application; and (3) integrating the machine into an existing environment. Also, an attempt is made to clear up any misconceptions there might be about 19 mm tape recorders.

Atkinson, Steve

1991-01-01

157

Meteorological research applications of MM-wave radar  

Microsoft Academic Search

Summary MM-wave radar has now been developed well beyond that of simply providing qualitative information about the presence or location of clouds. Uncertainty about cloud properties leading to gross errors in climate model results has provided the impetus to develop mm-wave radars into reliable, quantitative tools for studying clouds. Besides depicting the small-scale (a few tens of meters) features of

R. A. Krofli; R. D. Kelly

1996-01-01

158

Water masers towards 1.2 mm dust clumps  

Microsoft Academic Search

We request 26 hours of ATCA time to obtain sub-arcsecond accurate positions for 57 water masers (33 of which are new detections) that we have detected towards 1.2 mm dust clumps using the Mount Pleasant radio telescope. The search has been primarily directed towards those 1.2 mm dust clumps that were determined to have a high probability of associated water

Shari Breen; James Caswell; Simon Ellingsen

2007-01-01

159

Combined quantum and molecular mechanics (QM/MM).  

PubMed

We describe the current state of the art of mixed quantum mechanics/molecular mechanics (QM/MM) methodology, with a particular focus on modeling of enzymatic reactions. Over the past decade, the effectiveness of these methods has increased dramatically, based on improved quantum chemical methods, advances in the description of the QM/MM interface, and reductions in the cost/performance of computing hardware. Two examples of pharmaceutically relevant applications, cytochrome P450 and class C ?-lactamase, are presented.: PMID:24981493

Friesner, Richard A

2004-12-01

160

Making pH Tangible.  

ERIC Educational Resources Information Center

Presents a laboratory exercise in which students test the pH of different substances, study the effect of a buffer on acidic solutions by comparing the behavior of buffered and unbuffered solutions upon the addition of acid, and compare common over-the-counter antacid remedies. (MKR)

McIntosh, Elizabeth; Moss, Robert

1995-01-01

161

Sashwati Roy, PhD  

Cancer.gov

Dr. Sashwati Roy is an Associate Professor of Surgery and Director of the Laser Capture Molecular Core at The Ohio State University, Columbus, Ohio. In 1994 she received her PhD degree in Physiology and Environmental Sciences and later completed her postdoctoral training at the University of California, Berkeley. Dr.

162

Karl Krueger, PhD  

Cancer.gov

Dr. Karl Krueger received a PhD in biochemistry from Vanderbilt University and continued his research training at NIH as a postdoctoral fellow before joining the faculty at Georgetown University School of Medicine. His research throughout this period focused on different aspects of drug receptors and their role in the nervous system.

163

Evolving Starburst Modeling of FIR\\/sub-mm\\/mm Line Emission. III. Application to Nearby Luminous Infrared Galaxies  

Microsoft Academic Search

In a previous work, we showed that the observed FIR\\/sub-mm\\/mm line spectra of\\u000aa starburst galaxy (M 82) can be successfully modeled in terms of the\\u000aevolutionary scheme of an ensemble of giant molecular clouds (GMCs) and shells,\\u000aand such studies can usefully constrain the age(s) or star formation history of\\u000aa starburst galaxy. In this paper we present a

Lihong Yao

2009-01-01

164

Particle trackers based on 1 mm and 0.7 mm scintillating fibers readout by a multi-anode photomultiplier  

NASA Astrophysics Data System (ADS)

A prototype particle tracking detector was constructed at LNF with 1 mm and 0.7 mm plastic scintillating fibers with a 64 channel Hamamatsu H7546A-200 Ultra-bialkali flat-panel multi-anode photomultiplier readout. Cosmic ray tracks from an array of 11 gas-filled drift tubes were matched to signals in the scintillating fibers in order to measure the resolution and efficiency of tracks reconstructed in the fiber-based tracker. The fibers allow for two possible readout methods, a hit-based (digital) and an amplitude-based (analog) mode. A GEANT4 detector simulation was also developed to compare cosmic ray data with Monte Carlo results. These fiber tracker designs are suggested as a way to meet the resolution and efficiency goals of modern detectors, such as an upgraded LHCb Outer Tracker. Resolutions for the fiber trackers were found to be 0.236 mm and 0.175 mm for the 1 mm and 0.7 mm trackers, respectively, in analog mode.

Leverington, Blake; Rosellini, Rossano; Anelli, Mario; Campana, Pierluigi

2013-08-01

165

Influence of pH and fluoride on properties of an oral strain of Lactobacillus casei grown in continuous culture.  

PubMed Central

A freshly isolated oral strain, Lactobacillus casei RB1014, was grown in continuous culture to compare the effects of pH and fluoride on growth and metabolism. The cells were grown at pH 7.0 to 3.2 in the absence of fluoride and from pH 7.0 to 5.4 with 20 mM NaF. Cell numbers varied from 3 X 10(9) to 30 X 10(9)/ml on blood agar during alterations in the growth pH from 7.0 to 4.27. Only when the culture was stressed by lowering the pH to 3.2 were cell numbers drastically reduced. Cells growing at pH 7.0 without fluoride were unable to grow when plated on fluoride agar (10.5 mM) at pH 5.5; however, when the growth pH was allowed to decrease to 4.94, cells grew on the fluoride plates in numbers equal to those growing on blood agar. This fluoride tolerance trait appeared rapidly once pH control was removed and was lost when the culture was returned to pH 7.0. The addition of 20 mM NaF to the culture medium did not adversely affect growth, provided that the pH was maintained at 6.0 or above; cells tolerant to 10.5 and 16 mM NaF appeared on pH 5.5 plates during this phase. In cells removed from the chemostat throughout the experiment and incubated at the pH of growth in a pH stat, glycolytic activity was optimum at pH 5.5 in the absence of NaF. Fluoride stimulated glycolytic activity by cells incubated at pH 7.0 and by cells growing with 20 mM NaF, provided that the pH of growth remained at or above 6.0. A more detailed examination of the adaptation to fluoride tolerance during shifts to acidic pH values revealed that cells capable of growth on acidic fluoride agar plates appeared within 2 h of the start of the fall in pH of the chemostat culture. Estimation of the intracellular pH during the period of the initial pH fall revealed that the intracellular pH was identical to the extracellular pH (i.e., no pH gradient [delta pH]), indicating that fluoride would not be transported into the cells to inhibit metabolism. However, once the pH of the medium was stabilized, delta pHs were generated, with the delta pH increasing as the pH declined. The inhibition of glycolysis by fluoride increased in proportion to the delta pH. Cells grown at pH 5.5 generated larger delta pHs than did cells grown at pH 7.0, although the values were normally small (approximately 0.9 U). The data suggest that the inherent fluoride tolerance of L. casei RB1014 was associated with relatively small delta pHs.

Hamilton, I R; Boyar, R M; Bowden, G H

1985-01-01

166

Water masers towards 1.2 mm dust clumps  

NASA Astrophysics Data System (ADS)

We request 26 hours of ATCA time to obtain sub-arcsecond accurate positions for 57 water masers (33 of which are new detections) that we have detected towards 1.2 mm dust clumps using the Mount Pleasant radio telescope. The search has been primarily directed towards those 1.2 mm dust clumps that were determined to have a high probability of associated water maser presence using the model of Breen et al. (2007). The rms pointing errors of the Mount Pleasant radio telescope are approximately 0.5 arcminutes which is insufficient to meaningfully compare the locations of the water masers with infrared data for the regions as well as the positions of the 1.2 mm dust clumps, towards which the observations were targeted. By obtaining sub-arcsecond accurate positions for the water masers we aim to test the model for water maser presence within 1.2 mm dust clumps of Breen et al. (2007) and add refinements as required. Modelling the presence/absence of water masers using the properties of 1.2 mm dust clumps provides a unique opportunity to constrain the mass range of the stars that the water masers are associated with.

Breen, Shari; Caswell, James; Ellingsen, Simon

2007-10-01

167

PhET Simulation: Density  

NSDL National Science Digital Library

This simulation provides a highly visual, intuitive way for students to explore how density is related to an object's mass and volume. Using a virtual water tank, users drop various objects to see what floats and what sinks. Use the mouse to submerge the object and see how much fluid it displaces. A scale is provided to measure the mass of the objects, with a density table available for view. Students can easily see why the density formula works, especially when they identify the "mystery" objects. Editor's Note: Scroll down on the page for exemplary lesson plans for grades 6-12 developed by the PhET project specifically to accompany the "Density" simulation. This item is part of a larger collection of simulations developed by the Physics Education Technology project (PhET).

2011-02-16

168

Christos Patriotis, PhD  

Cancer.gov

Dr. Christos Patriotis obtained his MSc in Biochemistry from the University of Sofia, Bulgaria in 1985 and his PhD in Molecular Biology from the Bulgarian Academy of Sciences in 1990. Postdoctoral training focused on signal transduction and tumor cell biology. He joined the faculty at Fox Chase Cancer Center in 1998; his research was directed toward understanding mechanisms of breast and ovarian cancer pathogenesis and identification of biomarkers associated with the early stages of the two types of cancer.

169

Investigation of the sapphire window on short MM waves band  

NASA Astrophysics Data System (ADS)

A analytic method of the eguivalent network for RF sapphire window of 3mm diffraction radiation oscillator is given in the paper. Numerical simulate and experiment are carried out on 3mm wave band. The testing results show that the design method agrees with the practical windows, and it is the fast optimum method. We employ the universal method, the piece of the window can be equal to dielectric waveguide and one end of the window connects the coupling slit of the mirror of open cavity. The design window by means of this method is used satisfactorily on 3mm DRO. The tube operates in the 84 108GHZ band, the output power is about 250m W.

Chen, Jiayu; Zhang, Yongchuag; Duan, Yuxiang

1995-12-01

170

New Methods for Exploring QM:MM Potential Energy Landscapes  

NASA Astrophysics Data System (ADS)

In recent years, the applicability of quantum chemical methods for large system studies has been greatly enhanced by the development of hybrid QM:MM techniques. Despite these advancements, exploring the associated potential energy surfaces continues to present two key challenges. First, the QM energy and derivative evaluations may be too costly for simulations; and second, the system size for many QM:MM cases are too large to effectively store or use second-order information, an approach often used in QM studies to allow for larger integration steps and fewer QM evaluations of the potential energy surface. Our most recent work is focused on overcoming both computational bottlenecks. Using surface fitting models together with direct Hessian-vector and diagonalization algorithms, we are developing models that can accurately and efficiently explore QM:MM potential energy landscapes for very large systems. Our current development status and results from initial applications will be described.

Hratchian, Hrant P.

2010-06-01

171

Integrated blood-gas sensor for pO2, pCO2 and pH  

Microsoft Academic Search

The fabrication and characterization of a combined pOz, pCOl and pH chemical sensor, designed for blood-gas monitoring, are discussed. Classical electrochemical principles are used in a miniaturized planar-type structure. Both amperometric (PO,) and potentiometric devices (pCOr, pH) are integrated on a 10 mm x 10 mm chip. The transducer part of the chip is realized using standard silicon technology. Polyacrylamide

A. van den Berg; B. H. van der Schoot; N. F. de Rooij; H. Biihler; W. E. Morf; L. F. J. Diirselen; L. F. J. Dürselen

1993-01-01

172

450mm wafer patterning with jet and flash imprint lithography  

NASA Astrophysics Data System (ADS)

The next step in the evolution of wafer size is 450mm. Any transition in sizing is an enormous task that must account for fabrication space, environmental health and safety concerns, wafer standards, metrology capability, individual process module development and device integration. For 450mm, an aggressive goal of 2018 has been set, with pilot line operation as early as 2016. To address these goals, consortiums have been formed to establish the infrastructure necessary to the transition, with a focus on the development of both process and metrology tools. Central to any process module development, which includes deposition, etch and chemical mechanical polishing is the lithography tool. In order to address the need for early learning and advance process module development, Molecular Imprints Inc. has provided the industry with the first advanced lithography platform, the Imprio® 450, capable of patterning a full 450mm wafer. The Imprio 450 was accepted by Intel at the end of 2012 and is now being used to support the 450mm wafer process development demands as part of a multi-year wafer services contract to facilitate the semiconductor industry's transition to lower cost 450mm wafer production. The Imprio 450 uses a Jet and Flash Imprint Lithography (J-FILTM) process that employs drop dispensing of UV curable resists to assist high resolution patterning for subsequent dry etch pattern transfer. The technology is actively being used to develop solutions for markets including NAND Flash memory, patterned media for hard disk drives and displays. This paper reviews the recent performance of the J-FIL technology (including overlay, throughput and defectivity), mask development improvements provided by Dai Nippon Printing, and the application of the technology to a 450mm lithography platform.

Thompson, Ecron; Hellebrekers, Paul; Hofemann, Paul; LaBrake, Dwayne L.; Resnick, Douglas J.; Sreenivasan, S. V.

2013-09-01

173

Effect of Ph on Human Complement Activity.  

National Technical Information Service (NTIS)

The influence of pH on the haemolytic activity of human complement (HuC') was investigated over the pH range 5.55-8.20. Maximum haemolytic activity of HuC' was observed at pH 6.77 and not at the pH level (7.2) usually used. Adjustment of pH to either the ...

B. J. Fogel W. A. Hook E. H. Fife

1966-01-01

174

Permeant cations and blockers modulate pH gating of ROMK channels.  

PubMed

External potassium (K) activates the inward rectifier ROMK (K(ir)1.1) by altering the pH gating of the channel. The present study examines this link between external K and internal pH sensitivity using both the two-electrode voltage clamp and the perfused, cut-open Xenopus oocyte preparation. Elevating extracellular K from 1 mM to 10 mM to 100 mM activated ROMK channels by shifting their apparent pK(a) from 7.2 +/- 0.1 (n = 6) in 1 mM K, to 6.9 +/- 0.02 (n = 5) in 10 mM K, and to 6.6 +/- 0.03 (n = 5) in 100 mM K. At any given internal pH, the number of active ROMK channels is a saturating function of external [K]. Extracellular Cs (which blocks almost all inward K current) also stimulated outward ROMK conductance (at constant 1 mM external K) by shifting the apparent pK(a) of ROMK from 7.2 +/- 0.1 (n = 6) in 1 mM K to 6.8 +/- 0.01 (n = 4) in 1 mM K + 104 mM Cs. Surprisingly, the binding and washout of the specific blocker, Tertiapin-Q, also activated ROMK in 1 mM K and caused a comparable shift in apparent pK(a). These results are interpreted in terms of both a three-state kinetic model and a two-gate structural model that is based on results with KcsA in which the selectivity filter can assume either a high or low K conformation. In this context, external K, Cs, and Tertiapin-Q activate ROMK by destabilizing the low-K (collapsed) configuration of the selectivity filter. PMID:12547773

Sackin, H; Vasilyev, A; Palmer, L G; Krambis, M

2003-02-01

175

pH and Bicarbonate Effects on Mitochondrial Anion Accumulation  

PubMed Central

Mitochondria from rabbit and dog renal cortex were incubated with 1 mM 14C-weak acid anions in media containing low (10 mM) or high (40 mM) concentrations of bicarbonate and the steady-state accumulation of labeled anion in the matrix was measured. In the absence of an energy source, no concentration of 14C-anion in the mitochondrial matrix space was present, but the anion concentration was significantly higher at low- than at high-bicarbonate concentration. Addition of an energy source, usually ascorbate plus tetramethyl-p-phenylenediamine, led to increases in matrix space anion levels and to accentuation of the difference in anion uptake between low- and high-bicarbonate media, so that two to four times as much anion was present at low- than at high-bicarbonate concentrations. The anions affected included substrates for which inner membrane carriers are present in mitochondria, such as citrate, ?-ketoglutarate, malate, and glutamate, as well as substances which diffuse passively across the inner membrane such as acetate and formate. When a nonbicarbonate medium buffered with Hepes was used, pH change did not alter anion uptake although anion concentrations exceeding those in the medium still developed when an energy source was present. The difference in mitochondrial anion accumulation between low- and high-bicarbonate levels diminished with decreasing temperature or with increasing anion concentration in the medium. Estimation of intramitochondrial pH with [14C]5,5-dimethyl-oxazolidine-2,4-dione showed that the pH gradient across the inner mitochondrial membrane was significantly greater with 10 than with 40 mM bicarbonate in the medium. A hypothesis is described that relates this effect of pH and bicarbonate on mitochondrial anion accumulation to the very rapid changes in substrate levels in renal cortex, which develop when acute metabolic acidosis or alkalosis is produced in the intact animal. It is suggested that an abrupt fall in systemic pH and bicarbonate is associated with a shift in substrate in renal cortex out of the cytoplasm and into mitochondria, where some of the added substrate is metabolized. Reduction in the size of the cytoplasmic pool of substrate occurs with relatively little accompanying change in the size of the mitochondrial pool, thus causing a net reduction in the total tissue pool. This mechanism accounts for the reduction in tissue levels of many mitochondrial substrates observed acutely in metabolic acidosis. In metabolic alkalosis, reversal of these effects leads to expansion of the cytoplasmic pool, thereby resulting in the rise in tissue levels of substrates which occurs in this condition.

Simpson, David P.; Hager, Steven R.

1979-01-01

176

MM/PBSA analysis of molecular dynamics simulations of bovine beta-lactoglobulin: free energy gradients in conformational transitions?  

PubMed

The pH-driven opening and closure of beta-lactoglobulin EF loop, acting as a lid and closing the internal cavity of the protein, has been studied by molecular dynamics (MD) simulations and free energy calculations based on molecular mechanics/Poisson-Boltzmann (PB) solvent-accessible surface area (MM/PBSA) methodology. The forms above and below the transition pH differ presumably only in the protonation state of residue Glu89. MM/PBSA calculations are able to reproduce qualitatively the thermodynamics of the transition. The analysis of MD simulations using a combination of MM/PBSA methodology and the colony energy approach is able to highlight the driving forces implied in the transition. The analysis suggests that global rearrangements take place before the equilibrium local conformation is reached. This conclusion may bear general relevance to conformational transitions in all lipocalins and proteins in general. PMID:15690343

Fogolari, Federico; Moroni, Elisabetta; Wojciechowski, Marcin; Baginski, Maciej; Ragona, Laura; Molinari, Henriette

2005-04-01

177

Six-mm, plane-wave shock driver.  

National Technical Information Service (NTIS)

A 6-mm-diameter, plane-wave shock generation system has been developed and characterized as a laboratory bench driver for small scale experiments. The driver is based on an exploding-foil-driven slapper used either directly or to initiate an HE pellet. Th...

A. M. Frank H. H. Chau

1993-01-01

178

RF and mm-Wave Photonics at Sandia National Laboratories  

SciTech Connect

RF and mm-wave photonic devices and circuits have been developed at Sandia National Laboratories for applications ranging from RF optical data links to optical generation of mm-wave frequencies. This talk will explore recent high-speed photonics technology developments at Sandia including: (1) A monolithic optical integrated circuit for all-optical generation of mm-waves. Using integrated mode-locked diode lasers, amplifiers, and detectors, frequencies between 30 GHz and 90 GHz are generated by a single monolithic (Al,Ga)As optical circuit less than 2mm in its largest dimension. (2) Development of polarization-maintaining, low-insertion-loss, low v-pi, Mach-Zehnder interferometer (MZI) modulators with DC-to-potentially-K-band modulation bandwidth. New low-loss polarization-maintaining waveguide designs using binary alloys have been shown to reduce polarization crosstalk in undoped (Al,Ga)As waveguides, yielding high extinction ratio (>40dB) and low on-chip loss (<6dB) in Mach-Zehnder interferometers. RF drive voltage is reduced through use of 45rnrn-active length devices with modulator sensitivity, v-pi, less than 3V.

Vawter, G.A.; Sullivan, C.

1999-07-08

179

66 MM Non-Lethal Grenade: Human Effects Review.  

National Technical Information Service (NTIS)

The purpose of this report is to assess the target effectiveness and the risks of severe (unacceptable) injury to those individuals who are impacted by the 66mm Non-Lethal Grenades (NLG) submunitions or projectiles (specifically the XM99 and the XM98) fro...

D. L. Gonzalez R. Constable T. Dayton J. Wilder B. J. Klauenberg

2003-01-01

180

LIGA-fabricated compact mm-wave linear accelerator cavities.  

SciTech Connect

Millimeter-wave rf cavities for use in linear accelerators, free-electron lasers, and mm-wave undulatory are under development at Argonne National Laboratory. Typical cavity dimensions are in the 1000 mm range, and the overall length of the accelerator structure, which consists of 30-100 cavities, is about 50-100 mm. An accuracy of 0.2% in the cavity dimensions is necessary in order to achieve a high Q-factor of the cavity. To achieve this these structures are being fabricated using deep X-ray lithography, electroforming, and assembly (LIGA). The first prototype cavity structures are designed for 108 GHz and 2p/3-mode operation. Input and output couplers are integrated with the cavity structures. The cavities are fabricated on copper substrates by electroforming copper into 1-mm-thick PMMA resists patterned by deep x-ray lithography and polishing the copper down to the desired thickness. These are fabricated separately and subsequently assembled with precision spacing and alignment using microspheres, optical fibers, or microfabricated spacers/alignment pieces. Details of the fabrication process, alignment, and assembly work are presented in here.

Song, J.J.; Bajikar, S.S.; DeCarlo, F.; Kang, Y.W.; Kustom, R.L.; Mancini, D.C.; Nassiri, A.; Lai, B.; Feinerman, A.D.; White, V.

1998-03-23

181

Large-Format 70-mm High-Speed Framing Camera.  

National Technical Information Service (NTIS)

A new large-format synchronized high-speed framing camera is described. The camera has a framing rate of 2.5 x 10 exp 6 frames/sec with a frame size of 64 by 38 mm and a 26-frame record length. The new camera uses a beryllium rotating mirror with an isosc...

J. B. Sonderman L. G. Seppala L. L. Shaw

1978-01-01

182

Liquid-crystal-based mm-wave tunable resonator  

Microsoft Academic Search

A new tunable planar resonator based on nematic liquid crystals (LC) substrate for applications at mm-wave frequencies is presented. The proposed structure utilizes an electric field bias to align the LC molecules, offering direct control over the dielectric properties (anisotropy) of the LC substrate. The LC used is a mixture commonly referred to as E7. A tunability of about 6%

M. Yazdanpanahi; S. Bulja; D. Mirshekar-Syahkal; R. James; S. E. Day; F. A. Ferna?ndez

2010-01-01

183

Bell & Howell Introduces an 8mm Cartridge Concept  

ERIC Educational Resources Information Center

"Bell & Howell has developed a highly versatile cartidge projector system for cine and super 8mm formats. Because Bell & Howell believes that standardization is an important factor in the development of a cartridge system, it has built in a flexibility which will allow this standardization. (Author)

Educ Screen Audiovisual Guide, 1970

1970-01-01

184

Analysis of Wear Data for the 155mm XM198.  

National Technical Information Service (NTIS)

This test attempts to determine which characteristics of tube or projectile cause or influence muzzle wear, particularly for the 155mm XM198 howitzer family of components (XM199 cannon, XM549 projectile, XM123 propelling charge). The test was limited to a...

R. G. Hasenbein

1975-01-01

185

Water masers towards 1.2 mm dust clumps  

NASA Astrophysics Data System (ADS)

We request 60 hours of ATCA time to obtain sub-arcsecond positions for 118 water masers that we have detected towards 1.2 mm dust clumps using the Mount Pleasant radio telescope. We will use the sub-arcsecond positions obtained for the water masers to test and further refine the model of Breen et al. (2007). Modelling the presence/absence of the water masers using the properties of the 1.2 mm dust clumps provides a unique opportunity to constrain the mass range of the stars that the water masers are associated with. The pointing accuracy of the Mount Pleasant radio observations are approximately 0.5 arcminutes which is insufficient to meaningfully compare the locations of the water masers with infrared data for the regions as well as the positions of the 1.2 mm dust clumps, towards which the observations were targeted. The Mt Pleasant search was been directed towards 404 1.2 mm dust clumps yielding approximately 240 water maser detections (of which accurate positions for 122 sources were obtained in the 2007OCTS semester, taken from the literature or derived from archived data). These observations will complete the project.

Breen, Shari; Caswell, James; Ellingsen, Simon

2008-04-01

186

Advisory List of Instructional Media--16MM Films.  

ERIC Educational Resources Information Center

These two advisory lists include information on 16mm films appropriate for the K-12 instructional program. In both bibliographies films are listed in the following categories: communication skills; guidance; health, physical education, safety, and sports; science; and social studies. The list for the 1982-1983 school year also includes categories…

North Carolina State Dept. of Public Instruction, Raleigh. Div. of Educational Media.

187

70mm roll film camera system for remote metallography  

Microsoft Academic Search

From joint meeting of the American Nuclear Society and the Atomic ; Industrial Forum and Nuclear Energy Exhibition; San Francisco, California, USA ; (11 Nov 1973). An automatically sequenced 70mm roll film camera system was ; adapted with minimal modification for use with remote metallographs to record ; high magnification (25 to 750X) photomosaics. The system is also applicable for

Gruber

1974-01-01

188

Penetration Characteristics of the 10 mm Nylon Cyclone.  

National Technical Information Service (NTIS)

The purpose of the work was to determine the flow rate at which the 10 mm nylon cyclone samples polydisperse coal dust in accordance with the AEC definition of respirable dust. The penetration characteristics of the cyclone were determined by taking simul...

E. B. Sansone W. Bell J. Buchino

1973-01-01

189

mmGrid: Distributed Resource Management Infrastructure for Multimedia Applications  

Microsoft Academic Search

Abstract We are developing mmGrid (Multimedia Grid) as an ex - tensible middleware architecture supporting multimedia ap - plications in a grid computing environment Our vision is to provide support for interactive applications from the fol - lowing domains: graphics, visualization, streaming media and tele - immersion The initial deployment will be within an enterprise as a mechanism for provisioning

Sujoy Basu; Sameer Adhikari; Raj Kumar; Yong Yan; Roland Hochmuth; Bruce E. Blaho

2003-01-01

190

Evaluating Patron Satisfaction at the M.M. Bennett Library.  

ERIC Educational Resources Information Center

Discusses a user satisfaction survey distributed to patrons of the M.M. Bennett Library at St. Petersburg College (Florida). Reports that satisfaction with reference assistance has varied, although there has been an improvement in the rating of library instructions since this question was first posed in 1999. Suggests that paper surveys are easier…

Barbier, Pat

2003-01-01

191

Mineralogic Model (MM3.0) Analysis Model Report  

SciTech Connect

The purpose of this report is to document the Mineralogic Model (MM), Version 3.0 (MM3.0) with regard to data input, modeling methods, assumptions, uncertainties, limitations and validation of the model results, qualification status of the model, and the differences between Version 3.0 and previous versions. A three-dimensional (3-D) Mineralogic Model was developed for Yucca Mountain to support the analyses of hydrologic properties, radionuclide transport, mineral health hazards, repository performance, and repository design. Version 3.0 of the MM was developed from mineralogic data obtained from borehole samples. It consists of matrix mineral abundances as a function of x (easting), y (northing), and z (elevation), referenced to the stratigraphic framework defined in Version 3.1 of the Geologic Framework Model (GFM). The MM was developed specifically for incorporation into the 3-D Integrated Site Model (ISM). The MM enables project personnel to obtain calculated mineral abundances at any position, within any region, or within any stratigraphic unit in the model area. The significance of the MM for key aspects of site characterization and performance assessment is explained in the following subsections. This work was conducted in accordance with the Development Plan for the MM (CRWMS M&O 2000). The planning document for this Rev. 00, ICN 02 of this AMR is Technical Work Plan, TWP-NBS-GS-000003, Technical Work Plan for the Integrated Site Model, Process Model Report, Revision 01 (CRWMS M&O 2000). The purpose of this ICN is to record changes in the classification of input status by the resolution of the use of TBV software and data in this report. Constraints and limitations of the MM are discussed in the appropriate sections that follow. The MM is one component of the ISM, which has been developed to provide a consistent volumetric portrayal of the rock layers, rock properties, and mineralogy of the Yucca Mountain site. The ISM consists of three components: (1) Geologic Framework Model (GFM); (2) Rock Properties Model (RPM); and (3) Mineralogic Model (MM). The ISM merges the detailed stratigraphy and structural features of the site into a 3-D model that will be useful in primary downstream models and repository design. These downstream models include the hydrologic flow models and the radionuclide transport models. All the models and the repository design, in turn, will be incorporated into the Total System Performance Assessment (TSPA) of the potential nuclear waste repository block and vicinity to determine the suitability of Yucca Mountain as a host for a repository. The interrelationship of the three components of the ISM and their interface with downstream uses are illustrated in Figure 1. The lateral boundaries of the ISM and its three component models are shown in Figure 2.

C. Lum

2002-02-12

192

Spitzer Imaging of Herschel Lensed Sub-mm Galaxies  

NASA Astrophysics Data System (ADS)

Sub-millimeter surveys have, in the last decade, revealed an unexpected population of high-redshift dust-obscured sub-mm galaxies (SMGs) which are forming stars at a tremendous rate. Due to steep number counts and the negative k-correction at sub-mm wavelengths sub-mm surveys are effective at finding intrinsically faint, gravitationally lensed galaxies. We have now produced a reliable list of about 150 bright lensed SMGs in 200 sq. deg of the Herschel-ATLAS and HerMES (the GTO program of the SPIRE Instrument team) surveys with Herschel-SPIRE. We propose Spitzer IRAC 3.6 and 4.5 micron imaging of 122 of these gravitationally lensed SMGs. The target SMGs are selected to maximally overlap with existing and planned multi-wavelength followup programs, without duplicating existing deep IRAC data. Using the proposed Spitzer data we will: (a) Extend the SEDs of z~ 1 to 5 lensed SMGs into the near-IR regime, where derived stellar masses are more reliable than those estimated at other wavelengths alone; (b) Combine with lens models from existing and planned high-resolution sub-mm imaging (SMA, CARMA, PdBI) to map the evolution of stellar mass as a function of redshift and star-formation rate (SFR); (c) Combine with existing and planned CO and CII molecular line measurements to map the evolution of dust-to-gas and stellar-to-gas mass ratios as a function of redshift and SFR; (d) Obtain snapshot statistics on the sub-mm galaxy evolution from z of 1 to 5 as a function of stellar, dust, and gas mass to study the role of mergers and AGN contribution that may regulate the starburst phenomenon; (e) Compare our results to those from numerical simulations of high-redshift starburst galaxies to investigate the physical conditions in SMGs, and their evolutionary pathways.

Cooray, Asantha; Wardlow, Julie; Kim, Sam; Khostovan, Ali; Mitchell-Wynne, Ketron; Barton, Elizabeth; Gong, Yan; Amblard, Alexandre; Serra, Paolo; Cooke, Jeff; Riechers, Dominik; Dominic, Benford; Frayer, David; Gardner, Jonathan; Fu, Hai; Bussmann, Shane; Gurwell, Mark; Leeuw, Lerothodi; Pasquale, Temi; Conley, Alex; Bock, Jamie; Vieira, Joaquin; Bridge, Carrie; Glenn, Jason; Zemcov, Michael; Schulz, Bernhard; Shupe, David; Hopwood, Ros; Negrello, Mattia; Andreani, Paola; Clements, David; Dannerbauer, Helmut; de Zotti, Gianfranco; Dunne, Loretta; Dunlop, James; Eales, Steve; Farrah, Duncan; Ivison, Rob; Jarvis, Matt; Maddox, Steve; Michalowski, Michal; Omont, Alain; Perez-Fournon, Ismael; Rigopoulou, Dimitra; Serjeant, Stephen; Smail, Ian; Thompson, Mark; Vaccari, Mattia; Verma, Aprajita; Coppin, Kirsten; Oliver, Seb; Wang, Lingyu

2011-05-01

193

Demonstration of pH control in a commercial immobilized glucose isomerase.  

PubMed

The synthesis of a variety of important biochemicals involves multistep enzyme-catalyzed reactions. In many cases, the optimal operating pH is much different for the individual enzymatic steps of such synthesis reactions. Yet, it may be beneficial if such reaction steps are combined or paired, allowing them to occur simultaneously, in proximity to one another, and at their respective optimal pH. This can be achieved by separating the micro-environments of the two steps of a reaction pathway using a thin urease layer that catalyzes an ammonia-forming reaction. In this article, the pH control system in a commercial immobilized glucose (xylose) isomerase pellet, which has an optimal pH of 7.5, is demonstrated. This system allows the glucose isomerase to have near its optimal pH activity when immersed in a bulk solution of pH 4.6. A theoretical analysis is also given for the effective fraction of the immobilized glucose isomerase, which remains active when the bulk pH is at 4.6 in the presence of 20 mM urea versus when the bulk pH is at its optimal pH of 7.5. Both theoretical and experimental results show that this pH control system works well in this case. (c) 1996 John Wiley & Sons, Inc. PMID:18629951

Fournier, R L; Varanasi, S; Byers, J P; Chen, G

1996-12-20

194

Charpy impact test results on five materials and NIST verification specimens using instrumented 2-mm and 8-mm strikers  

SciTech Connect

The Heavy-Section Steel Irradiation Program at Oak Ridge National Laboratory is involved in two cooperative projects, with international participants, both of which involve Charpy V-notch impact tests with instrumented strikers of 2mm and 8mm radii. Two heats of A 533 grade B class I pressure vessel steel and a low upper-shelf (LUS) submerged-arc (SA) weld were tested on the same Charpy machine, while one heat of a Russian Cr-Mo-V forging steel and a high upper-shelf (HUS) SA weld were tested on two different machines. The number of replicate tests at any one temperature ranged from 2 to 46 specimens. Prior to testing with each striker, verification specimens at the low, high, and super high energy levels from the National Institute of Standards and Technology (NIST) were tested. In the two series of verification tests, the tests with the 2mm striker met the requirements at the low and high energy levels but not at the super high energy. For one plate, the 2mm striker showed somewhat higher average absorbed energies than those for the 8-mm striker at all three test temperatures. For the second plate and the LUS weld, however, the 2mm striker showed somewhat lower energies at both test temperatures. For the Russian forging steel and the HUS weld, tests were conducted over a range of temperatures with tests at one laboratory using the 8mm striker and tests at a second laboratory using the 2mm striker. Lateral expansion was measured for all specimens and the results are compared with the absorbed energy results. The overall results showed generally good agreement (within one standard deviation) in energy measurements by the two strikers. Load-time traces from the instrumented strikers were also compared and used to estimate shear fracture percentage. Four different formulas from the European Structural Integrity Society draft standard for instrumented Charpy test are compared and a new formula is proposed for estimation of percent shear from the force-time trace.

Nanstad, R.K.; Sokolov, M.A.

1995-04-01

195

Fabrication of a multi-modal sensor with PH, EC and temperature sensing areas for agriculture application  

Microsoft Academic Search

A multi-modal sensor, with which was possible to simultaneously measure pH, electrical conductivity (EC) and temperature, was fabricated. The pH sensor, EC sensor, and temperature sensor were integrated using compatible complementary metal-oxide semiconductor (CMOS) logic technology on a small Si chip (area, 25 mm2). Simultaneous measurements of pH, EC and temperature were demonstrated, and the sensor was used successfully to

Masato Futagawa; H. Takao; M. Ishida; K. Sawada; T. Iwasaki

2009-01-01

196

Effect of Applied Potentials on Environmental Cracking Behavior of 17-4 PH Stainless Steel Weldments  

Microsoft Academic Search

The effects of anodic, cathodic, and open-circuit potentials (OCP) on the environmental cracking behavior of 17% Cr-4% Ni (17-4 [UNS S17400]) precipitation-hardenable (PH) stainless steel (SS) welds subjected to different thermal treatments were studied. Sheets of 17-4 PH SS 1.5 mm thick and in solution-treated condition were full-penetration welded autogenously using the gas tungsten arc welding process (GTAW). Weldments were

K. S. Raja; K. P. Rao

1995-01-01

197

Effect of pH and ionic strength on the physicochemical properties of coconut milk emulsions.  

PubMed

Coconut milk (16% to 17% fat, 1.8% to 2% protein) was extracted from coconut (Cocos nucifera L.) endosperm and diluted in buffer to produce natural oil-in-water emulsions (10 wt% oil). The effect of pH (3 to 7) and NaCl (0 to 200 mM) on the properties and stability, namely, mean particle size, zeta-potential, viscosity, microstructure, and creaming stability, of the natural coconut milk emulsions was investigated. At pH values close to the isoelectric point (IEP) of the coconut proteins (pH 3.5 to 4) and in the absence of NaCl, coconut milk flocculated, but did not coalesce. Flocculation corresponded to low surface charges and was accompanied by an increase in emulsion viscosity. Adding up to 200 mM NaCl to those flocculated emulsions did not change the apparent degree of flocculation. Coconut milk emulsion at pH 6 was negatively charged and not flocculated. Upon addition of salt, the zeta-potential decreased from -16 to -6 mV (at 200 mM NaCl) but this was not sufficient to induce flocculation in coconut milk emulsions. At low pH (< IEP), the positively charged droplets of coconut milk emulsions only flocculated when the NaCI concentration exceeded 50 mM, as the zeta-potential approached zero. PMID:19241548

Tangsuphoom, N; Coupland, J N

2008-08-01

198

The sub-mm/radio correlation in spiral galaxies  

NASA Astrophysics Data System (ADS)

This thesis reports the study of the dust and cosmic ray content of three edge- on spiral galaxies, NGC 3044, NGC 4157 and NGC 5775, to an unprecedented level. Observations in the sub-mm were made with the Submillimetre Common-User Bolometer Array (SCUBA) on the James Clerk Maxwell Telescope (JCMT). Metre- length radio continuum emission observations were conducted with the Giant Metrewave Radio Telescope (GMRT). We have produced multi-wavelength maps of the galaxies in our study at high resolution and good signal-to-noise in both the halo and disk. These maps are the basis for the rest of the study. Based on 450 and 850 mm observations of galaxies in our sample, we recalculated their gas-to-dust ratio which now agrees with our Galaxy's value. To our knowledge, we have produced the first spatially resolved cold-dust temperature map of any galaxy, for each galaxy in our sample. We have also produced a technique to calculate the spatial distribution of potential energy of the high-latitude dust, giving the lower limit energy required to transport dust from the disk to its current location. It is likely that one or more processes, such as perturbations in the galactic magnetic field, play a role in the ejection of the ISM, alongside supernovae. Finally, we show that a sub-mm/radio correlation exists spatially within the disks and haloes of NGC 3044, NGC 4157 and NGC 5775 and globally between these galaxies. This sub-mm/radio correlation is observational evidence that the conventional explanation for the famous FIR-radio correlation is incomplete or perhaps simply incorrect. An explanation, based on a review of the literature, is proposed for both the sub-mm/radio correlation and the FIR-radio correlation. The sub-mm/radio correlation, which includes emission from the dominant cold dust component, appears to be a more fundamental phenomenon than the specific case that results in the FIR/radio correlation, because the FIR picks out only a tiny fraction of the dust mass. We find that models that link magnetic fields to dust and cosmic rays as the origin of this correlation are the most promising in explaining the correlation in diverse galactic regions.

Brar, Rupinder Singh

2005-12-01

199

Perforation of 12 mm thick steel plates by 20 mm diameter projectiles with flat, hemispherical and conical noses  

Microsoft Academic Search

Projectiles with three different nose shapes (blunt, hemispherical and conical) have been used in gas gun experiments to penetrate 12mm thick Weldox 460E steel plates. Based on the experimental results, the residual velocity curves of the target material were constructed and compared. It was found that the nose shape of the projectile significantly affected both the energy absorption mechanism and

T Børvik; M Langseth; O. S Hopperstad; K. A Malo

2002-01-01

200

Simulation results on a resistive plate chamber for a bakelite thickness of 1 mm up to 3 mm  

SciTech Connect

The performance of bakelite electrodes with thicknesses of 1, 2, and 3 mm in a double-gap resistive plate chamber (RPC) have been tested by GEANT-based Monte Carlo simulation. Results show that the thickness of bakelite plays an important role in detecting particle signals. For checking the efficiency of these RPCs, gamma particles in the range 0.01-100 MeV have been simulated through different bakelite setups. For an isotropic gamma source, a sensitivity s{sub {gamma}}<3.5x10{sup -2} at <100 MeV by a 1 mm bakelite double-gap RPC has been observed. For the same gamma source with a 2 mm bakelite RPC, a sensitivity s{sub {gamma}}<4.0x10{sup -2} at <100 MeV has been measured, whereas for 3 mm bakelite RPC, sensitivity results were s{sub {gamma}}<4.44x10{sup -2} at <100 MeV. Similar characteristics of bakelite electrodes have been observed for a parallel gamma source configuration.

Rhee, J.T.; Jamil, M. [Institute for Advanced Physics, Konkuk University, Seoul 143-701 (Korea, Republic of)

2005-07-15

201

Simulation results on a resistive plate chamber for a bakelite thickness of 1 mm up to 3 mm  

NASA Astrophysics Data System (ADS)

The performance of bakelite electrodes with thicknesses of 1, 2, and 3 mm in a double-gap resistive plate chamber (RPC) have been tested by GEANT-based Monte Carlo simulation. Results show that the thickness of bakelite plays an important role in detecting particle signals. For checking the efficiency of these RPCs, gamma particles in the range 0.01-100 MeV have been simulated through different bakelite setups. For an isotropic gamma source, a sensitivity s?<3.5×10-2 at <100 MeV by a 1 mm bakelite double-gap RPC has been observed. For the same gamma source with a 2 mm bakelite RPC, a sensitivity s?<4.0×10-2 at <100 MeV has been measured, whereas for 3 mm bakelite RPC, sensitivity results were s?<4.44×10-2 at <100 MeV. Similar characteristics of bakelite electrodes have been observed for a parallel gamma source configuration.

Rhee, J. T.; Jamil, M.

2005-07-01

202

The pH of antiseptic cleansers  

PubMed Central

Background Daily bathing with antiseptic cleansers are proposed by some physicians as an adjunctive management of atopic dermatitis (AD). As atopic skin is sensitive, selection of cleansing products becomes a topic of concern. Objective Our purpose is to evaluate the pH of various antiseptic body cleansers to give an overview for recommendation to patients with AD. Methods Commonly bar and liquid cleansers consisted of antiseptic agents were measured for pH using pH meter and pH-indicator strips. For comparison, mild cleansers and general body cleansers were also measured. Results All cleansing bars had pH 9.8-11.3 except syndet bar that had neutral pH. For liquid cleansers, three cleansing agents had pH close to pH of normal skin, one of antiseptic cleansers, one of mild cleansers and another one of general cleansers. The rest of antiseptic cleansers had pH 8.9-9.6 while mild cleansers had pH 6.9-7.5. Syndet liquid had pH 7 and general liquid cleansers had pH 9.6. Conclusion The pH of cleanser depends on composition of that cleanser. Adding antiseptic agents are not the only factor determining variation of pH. Moreover, benefit of antiseptic properties should be considered especially in cases of infected skin lesions in the selection of proper cleansers for patients with AD.

Kulthanan, Kanokvalai; Varothai, Supenya; Nuchkull, Piyavadee

2014-01-01

203

Six-mm, plane-wave shock driver  

SciTech Connect

A 6-mm-diameter, plane-wave shock generation system has been developed and characterized as a laboratory bench driver for small scale experiments. The driver is based on an exploding-foil-driven slapper used either directly or to initiate an HE pellet. The slapper is driven by a low-inductance fireset with burst currents on the order of 30 kA and burst times of about 250ns, with a time-to-burst jitter under 10ns. Both the slapper impact and the detonation breakout of the pellet have been measured to be flat to within 10ns over a 6-mm diameter. Fabry-Perot velocimetry of impacts with LiF crystals were used to characterize shock pressures and durations. Attenuator plates and flyers driven by the HE were also measured, which provided a variety of available pulse shapes and data for modeling efforts.

Frank, A.M.; Chau, H.H.

1993-06-14

204

Six-mm, plane-wave shock driver  

SciTech Connect

A 6-mm-diameter, plane-wave shock generation system has been developed and characterized as a laboratory bench driver for small scale experiments. The driver is based on an exploding-foil-driven slapper used either directly or to initiate an HE pellet. The slapper is driven by a low-inductance fireset with burst currents on the order of 30 kA and burst times of about 250 ns, with time-to-burst jitter under 10 ns. Both the slapper impact and the detonation breakout of the pellet have been measured to be flat to within 10 ns over a 6-mm diameter. Fabry-Perot velocimetry of impacts with LiF crystals were used to characterize shock pressures and durations. Attenuator plates and flyers driven by the HE were also measured, which provided a variety of available pulse shapes and data for modeling efforts. [copyright]American Institute of Physics

Frank, A.M.; Chau, H.H. (Lawrence Livermore, National Laboratory, P.O. Box 808, Livermore, California 94551 (United States))

1994-07-10

205

Percutaneous transhepatic cholangioscopy with a 2.8 mm fiberscope.  

PubMed

The authors describe their initial experience with a 2.8 mm (8.5F) fiberscope. The instrument, used to refine interventional radiology maneuvers of the intra- and extra-hepatic bile ducts, caused no additional discomfort to the 18 patients treated. The fiberscope permitted differentiation between different causes of biliary stenosis in the few cases where doubt persisted after percutaneous cholangiography. Brushing was also performed wherever necessary. The color, and thus the composition, of bile duct stones could also be determined. This has helped us to plan the therapy with methyl-tert-butyl-ether (MTBE) in patients with cholesterol stones. Compared with traditional fiberscopes (diameter of 5mm or more) the new instrument is easier to use, and allows more peripheral ducts to be reached, but is expensive and has a smaller field of view and fewer possibilities for therapeutic applications. PMID:3383803

Gandini, G; Cesarani, F; Juliani, E; Regge, D; Bonardi, L; Recchia, S; Verme, G

1988-05-01

206

Design of 15 mm collars for SSC dipole magnets  

SciTech Connect

Ten 1-m long dipole magnets of the SSC design ''D'' cross section have been constructed and tested. In each model a collar type structure was used to contain and support the coil assembly at assembly and during operation at 4K. The collar structure must provide enough coil compression to minimize training and guarantee the coil cross section dimensions. Three types of collar designs were used. The behavior, measured and predicted, of two types of 15 mm stainless steel collars used on eight of the ten models is examined. The mechanical measurement of the 15 mm stainless steel collars used on eight 1-m dipole models are given. Observed behavior and preliminary design criteria are discussed. In order to better understand observed collar behavior and to evaluate new designs, finite element analysis of the collar designs was undertaken, and results are correlated with measured behavior. The behavior of alternate collar designs is predicted. 3 refs., 19 figs. (LEW)

Peters, C.

1986-03-01

207

Evolution of pH and chemical composition of pore solution in carbonated concrete  

Microsoft Academic Search

An investigation of carbonation in concrete, the pH and chemical composition change of the pore solution in concrete with different degrees of carbonation, was presented. The concrete samples were manufactured using ordinary portland cement and fly ash with dimension of 100mm diameter by 3mm in height, and six different mix proportions. The concrete samples were exposed to the environment (CO2

Qi Pu; Linhua Jiang; Jinxia Xu; Hongqiang Chu; Yi Xu; Yan Zhang

208

Thermal resistance of Alicyclobacillus acidoterrestris spores in different buffers and pH  

Microsoft Academic Search

The influence of buffers and pH on the thermal resistance of a novel flat sour-type of spoilage bacterium,Alicyclobacillus acidoterrestris, was investigated. At a low concentration (20 mM), decimal reduction times (D-values) in citrate and phosphate buffers were 13.6 and 12.9 min, respectively, showing little variation. At a high concentration (100 mM), however, theD-value in citrate buffer, 14.4 min, was significantly

M Murakami; H Tedzuka; K Yamazaki

1998-01-01

209

Effects of ion implantation on friction and wear of stainless steels. [15-5PH  

Microsoft Academic Search

Friction and wear of 304, 15-5 PH and 440C stainless steels and of pure Fe are shown to be reduced by ion implantation of Ti and C. Mechanically polished samples were ion implanted to fluences of 2 x 10¹⁵ Ti\\/mm² (90 to 180 keV) and 2 x 10¹⁵ C\\/mm² (30 keV); the implantation profiles of the two elements extended to

L. E. Pope; F. G. Yost; D. M. Follstaedt; J. A. Knapp; S. T. Picraux

1982-01-01

210

Six-mm, plane-wave shock driver  

Microsoft Academic Search

A 6-mm-diameter, plane-wave shock generation system has been developed and characterized as a laboratory bench driver for small scale experiments. The driver is based on an exploding-foil-driven slapper used either directly or to initiate an HE pellet. The slapper is driven by a low-inductance fireset with burst currents on the order of 30 kA and burst times of about 250

Alan M. Frank; Henry H. Chau

1994-01-01

211

Six-mm, plane-wave shock driver  

Microsoft Academic Search

A 6-mm-diameter, plane-wave shock generation system has been developed and characterized as a laboratory bench driver for small scale experiments. The driver is based on an exploding-foil-driven slapper used either directly or to initiate an HE pellet. The slapper is driven by a low-inductance fireset with burst currents on the order of 30 kA and burst times of about 250ns,

A. M. Frank; H. H. Chau

1993-01-01

212

A modified MM2 force field for bleomycin analysis  

NASA Astrophysics Data System (ADS)

New MM2 parameters for the cobalt binding site in cobalt-bleomycin, a potent antitumor antibiotic, are presented. These force constants were successfully used to model crystal structures of two cobalt-bleomycin analogues. Calculations on the bithiazole part of bleomycin show that the trans form is more stable than the cis form. It is also shown that conformational searches are necessary even in small inorganic molecules.

Charles, Robert; Ganly-Cunningham, Marcela; Warren, Rachel; Zimmer, Marc

1992-02-01

213

High mobility monolayer graphene over a 150mm substrate  

Microsoft Academic Search

We report the fabrication of monolayer graphene field effect devices over a 150 mm substrate. Using Cu-Ni multilayer growth substrates with Inductively Coupled Plasma-Enhanced Chemical Vapor Deposition (ICPCVD) at 700?, we were able to obtain unprecedented uniformity of monolayer graphene over the entire substrate, confirmed with Raman spectroscopic mapping after metal etching and transfer process. Mobility up to 9,000 cm2V-1s-1

Jinseong Heo; Yun Sung Woo; David H. Seo; Hyun-Jong Chung; Sunae Seo

2010-01-01

214

Water masers towards 1.2 mm dust clumps  

Microsoft Academic Search

We request 60 hours of ATCA time to obtain sub-arcsecond positions for 118 water masers that we have detected towards 1.2 mm dust clumps using the Mount Pleasant radio telescope. We will use the sub-arcsecond positions obtained for the water masers to test and further refine the model of Breen et al. (2007). Modelling the presence\\/absence of the water masers

Shari Breen; James Caswell; Simon Ellingsen

2008-01-01

215

Study of 5 and 10 mm thick CZT strip detectors  

Microsoft Academic Search

We report progress in the study of 5 and 10 mm thick CdZnTe strip detectors featuring orthogonal coplanar anode contacts. This novel anode geometry combines the advantages of pixel detectors with those of double-sided strip detectors. Like pixel detectors. these are electron-only devices that perform well as hard X-ray and ?-ray spectrometers and imagers even in the thicker configurations required

J. R. Macril; P. Dufour; L. A. Hamel; M. Julien; M. L. McConnelll; M. McClishl; J. M. Ryan; M. Widholm

2001-01-01

216

Simple spectral Representations for the M\\/M\\/1 Queue  

Microsoft Academic Search

This paper shows that certain basic descriptions of the time-dependent behavior of the M\\/M\\/1 queue have very simple representations as mixtures of exponentials. In particular, this is true for the busy-period density, the probability that the server is busy starting at zero, the expected queue length starting at zero and the autocorrelation function of the stationary queue-length process. In each

Joseph Abate; Ward Whitt

1988-01-01

217

Electromagnetic field measurements on a mm-wave linear accelerator  

SciTech Connect

Field strength measurements for the determination of the R/Q of a mm-wave, 50-MeV electron linear accelerator using perturbational techniques are described. The perturbation is achieved using optical fibers coated with a thin metallic film to form a hollow cylinder. The perturbational form factors for such a geometry are approximated using several simple analytical expressions which are compared to a finite difference calculation as well as experimental results on a known cavity.

Matthews, P.; Kang, Y.; Berenc, T.; Kustom, R. [Argonne National Lab., IL (United States); Willke, T.; Feinerman, A. [Univ. of Illinois, Chicago, IL (United States). Dept. of Electrical Engineering and Computer Science

1994-07-01

218

Variations on a QM/MM approach to cluster dynamics  

NASA Astrophysics Data System (ADS)

We discuss two extensions of a hierarchical QM/MM approach developed to describe clusters embedded into a polarizable environment. The first extension consists in considering the presence of a supporting metal. More specifically we consider the structure and dynamics of Na clusters on a surface built from Ar layers grown on a metal support. We study the effect of the Ar substrate and of the metal support. We find a faint binding on the surface and the effect of the dielectric response of the metal (DRM) turns out to be negligible. Deposit of small Na clusters is crucially influenced by the mechanical hardness of the metal support and the number of Ar layers, while the DRM makes little effect. The second extension consists in using the QM/MM approach to study color centers at an MgO surface. The particular efficiency of the QM/MM approach allows to consider large system's sizes and thus test the impact of the (necessarily) finite (surface) sample. We find that our results compare favorably with ab-initio approaches as well as with available experimental results.

Dinh, P. M.; Berger, D.; Faber, B.; Reinhard, P.-G.; Suraud, E.

2012-11-01

219

Influence of calcium, iron and pH on phosphate availability for microbial mineralization of organic chemicals  

SciTech Connect

A study was conducted to determine some of the factors affecting the P requirement for the biodegradation of p-nitrophenol, phenol, and glucose by Pseudomonas and Corynebacterium strains. Mineralization of glucose was rapid and the Pseudomonas sp. grew extensively in solutions with 5 and 10 mM phosphate, but the rate and extent of degradation were low and the bacterial population never became abundant in media with 0.2 mM phosphate. Similar results were obtained with the Corynebacterium sp. growing in media containing p-nitrophenol or phenol and in solutions with a purified phosphate salt. The extent of growth of the Corynebacterium sp. was reduced with 2 or 10 mM phosphate in media containing high Fe concentrations. Ca at 5 mM but not 0.5 mM inhibited p-nitrophenol mineralization by the Corynebacterium sp. with phosphate concentrations from 0.2 to 5.0 mM. Phenol mineralization by the Pseudomonas sp. in medium with 0.2 mM phosphate was rapid at pH 5.2, but the bacteria had little or no activity at pH 8.0. In contrast, the activity was greater at pH 8.0 than at pH 5.2 when the culture contained 10 mM phosphate. These effects of pH were similar in media with 5 mM Ca or no added Ca. The authors conclude that the effect of P on bacterial degradation can be influenced by the pH and the concentrations of Fe and Ca.

Robertson, B.K.; Alexander, M. (Cornell Univ., Ithaca, NY (United States))

1992-01-01

220

Microenvironments of pH in biofilms grown on dissolving silicate surfaces  

Microsoft Academic Search

Differences in pH between silicate–biofilm interfaces and bulk medium (?pH=pHinterface?pHbulk) were detectable with commercial microelectrodes in cultures grown in unbuffered medium (|?pH|=0.27–1.08) for an arthrobacter species, but were generally beneath detection (?pH<0.04) for a streptomyces species. Biofilm half-thicknesses developed by Arthrobacter ranged from 1.2 to 11.5 mm, and were highly variable even for replicates. In buffered medium, neither bacterium produced

Laura J. Liermann; Amy S. Barnes; Birgitta E. Kalinowski; Xiangyang Zhou; Susan L. Brantley

2000-01-01

221

Defining and Teaching pH  

Microsoft Academic Search

The 1909 definition of pH given in most general chemistry textbooks conflicts with the modern, operationally-defined pH scale that underlies laboratory measurement and relates to activities. At an elementary level, pH and the algebra of equilibria can be simply and correctly taught, without logarithms, in terms of the latter scale.

Richard F. Burton

2007-01-01

222

PhET Simulation: Sound  

NSDL National Science Digital Library

This interactive simulation allows users to analyze the properties of sound waves. Frequency and amplitude can be controlled, and users can enable audio tones to explore how pitch is related to frequency. Other options allow users to experiment with constructive and destructive interference by moving positions of speakers and listeners. Tools are also provided to measure wavelengths of various frequencies. Experimenting with interference from a wall and exploring sound in environments without air pressure are also possible. This simulation is part of a large and growing collection developed by the Physics Educational Technology Project using research-based principles. See the Related Materials below for a link to clicker questions and tutorials designed specifically for this simulation by the PhET team.

2008-10-29

223

Design and testing of a dual 8-T 380-mm\\/12-T 220-mm split superconducting solenoid for ORNL  

Microsoft Academic Search

A superconducting high field magnet facility has recently been prepared for operation at the Oak Ridge National Laboratory (ORNL). The facility consists of a background NbTi coil and an insert coil made of NbâSn tape. The background coil produces an 8-T central field, with a peak field of 8.8 T, in a bore of 380 mm and contains radial access

J. K. Ballou; R. L. Brown; W. A. Fietz; J. W. Forseman; W. H. Gray; W. J. Kenney; R. B. Wysor; W. D. Markiewicz; R. G. Van Alstyne

1981-01-01

224

Simulation results on a resistive plate chamber for a bakelite thickness of 1 mm up to 3 mm  

Microsoft Academic Search

The performance of bakelite electrodes with thicknesses of 1, 2, and 3 mm in a double-gap resistive plate chamber (RPC) have been tested by GEANT-based Monte Carlo simulation. Results show that the thickness of bakelite plays an important role in detecting particle signals. For checking the efficiency of these RPCs, gamma particles in the range 0.01-100 MeV have been simulated

J. T. Rhee; M. Jamil

2005-01-01

225

Heterogeneous Distribution of Microbial Activity in Methanogenic Aggregates: pH and Glucose Microprofiles  

PubMed Central

Methanogenic aggregates, harvested from an upflow anaerobic sludge blanket reactor treating potato starch wastewater, were acclimatized to either glucose or a mixture of sugars and organic nitrogen compounds (i.e., diluted molasses). Both types of granules exhibited internal pH and substrate concentration gradients in mineral medium (pH 7.0, 30°C) as was measured with microelectrodes. Glucose-acclimatized granules suspended in a mineral medium lacking glucose exhibited a distinct internal pH decrease of about 1 U within the granule, suggesting strong metabolism by the acidogenic bacteria. Molasses-acclimatized and aged granules suspended in mineral medium did not exhibit such a pH decrease, suggesting the importance of the metabolic state of these acidogens. The pH gradient did not occur in deactivated granules and was not observable in strongly buffered media (mineral medium containing 33 mM phosphate or reactor liquid). When glucose (0.5 to 5.0 mM) was added to the mineral medium, granules exhibited a convex pH profile. Glucose consumption was located exclusively in the outer 200 to 300 ?m of the aggregates (mean diameter = 1.5 mm). The addition of 20 mM 2-bromoethanesulfonic acid to the mineral medium indicated that the higher pH levels in the centre of the granule appeared to be related to the activity of methanogens. It is suggested that acidogenic activity occurs predominantly in the outer 200 to 300 ?m of the aggregate and methanogenic activity occurs predominantly in the center of the investigated granules. Images

Lens, Piet N. L.; De Beer, Dirk; Cronenberg, Carel C. H.; Houwen, Frans P.; Ottengraf, Simon P. P.; Verstraete, Willy H.

1993-01-01

226

Soil pH and Fertilizers  

NSDL National Science Digital Library

This Web site by the Mississippi State University Extension Service discusses why fertilizers are added to soils. The Web site begins by introducing the concept of the pH of the soil and how nutrients are affected by this pH level. Students can then learn about the pH logarithmic scale and about the factors that affect soil pH. At the end of the site, users will find a clear and concise table concerning different fertilizer materials characteristics including their speed of reaction and effect on pH in soils.

227

Soils - Part 4: Soil pH  

NSDL National Science Digital Library

Soil pH is defined and its implications for crop production are described in this lesson. How are soil pH and buffer pH determined? How are these assessments used in lime recommendations? The factors that influence pH variations in soils, the chemistry involved in changing the pH of a soil, and the benefits associated with liming acid soils will be discussed.[This lesson, as well as the other nine lessons in the Soils series, is taken from the "Soils Home Study Course," published in 1999 by the University of Nebraska Cooperative Extension.

228

Bolocam 1.1 mm Survey of the COSMOS Field  

NASA Astrophysics Data System (ADS)

Submillimeter galaxies are very luminous (L > 1012 Lsolar), high redshift (z > 1) galaxies which are highly obscured by dust. There is strong evidence that these galaxies are powered largely by high star formation rates, in which ultraviolet and optical light is absorbed by the dust and thermally emitted, peaking in the submillimeter and millimeter wavebands. We present results from a survey of the central 940 arcmin2 of the COSMOS field using Bolocam, the 1.1 mm camera at the Caltech Submillimeter Observatory. The COSMOS field has extensive multi-wavelength coverage from X-ray to radio. The coverage of such a large area in many wavebands is crucial to a complete characterization of the spectral energy distributions (SEDs) of submillimeter galaxies, thus integrating them into theories of galaxy formation and evolution. The survey combines Bolocam data taken in February 2004 and from February to April 2005. We present analysis of the data and characterization of the calibration and astrometry, the two dominant sources of systematic error for accurate photometry. The survey reaches an RMS noise level of ? {1.1 mm} ? 1.9 mJy beam-1, uniform over the entire 940 arcmin2. Our data shows 9 detections of galaxies above 3.8 ? , with one false detection expected above this threshold. We further present results of a fluctuation analysis of the data to constrain the number count distribution of submillimeter galaxies, and find it to be consistent with the previous Bolocam 1.1mm survey of the Lockman Hole. Future work includes follow-up of detected sources with SHARC II at 350 microns to measure the SED near the rest-frame submillimeter peak, and identification of radio counterparts in the deep VLA-COSMOS survey. This research was funded in part by a grant from the NSF (AST-0206158).

Schlaerth, J. A.; Aguirre, J. E.; Blain, A. W.; Bock, J. J.; Glenn, J.; Golwala, S. R.; Greve, T. R.; Laurent, G. T.; Maloney, P. R.; Rossinot, P.; Sayers, J.; Williams, J.

2005-12-01

229

TNT particle size distributions from detonated 155-mm howitzer rounds.  

PubMed

To achieve sustainable range management and avoid or minimize environmental contamination, the Army needs to know the amount of explosives deposited on ranges from different munitions and how these are degraded and transported under different geological and climatic conditions. The physical form of the deposited explosives has a bearing on this problem, yet the shapes and size distributions of the explosive particles remaining after detonations are not known. We collected residues from 8 high-order and 6 low-order non-tactical detonations of TNT-filled 155-mm rounds. We found significant variation in the amount of TNT scattered from the high-order detonations, ranging from 0.00001 to 2% of the TNT in the original shell. All low-order detonations scattered percent-level amounts of TNT. We imaged thousands of TNT particles and determined the size, mass and surface-area distributions of particles collected from one high-order and one low-order detonation. For the high-order detonation, particles smaller than 1 mm contribute most of the mass and surface area of the TNT scattered. For the low-order detonation, most of the scattered TNT mass was in the form of un-heated, centimeter-sized pieces whereas most of the surface area was again from particles smaller than 1 mm. We also observed that the large pieces of TNT disintegrate readily, giving rise to many smaller particles that can quickly dissolve. We suggest picking up the large pieces of TNT before they disintegrate to become point sources of contamination. PMID:14987934

Taylor, Susan; Hewitt, Alan; Lever, James; Hayes, Charlotte; Perovich, Laura; Thorne, Phil; Daghlian, Chuck

2004-04-01

230

Gas Analysis by Fourier Transform Mm-Wave Spectroscopy  

NASA Astrophysics Data System (ADS)

Molecular rotational spectroscopy of low pressure, room temperature gases offers high chemical selectivity and sensitivity with the potential for a wide range of applications in gas analysis. A strength of the technique is the potential to identify molecules that have not been previously studied by rotational spectroscopy by comparing experimental results to predictions of the spectroscopic parameters from quantum chemistry -6 so called library-free detection. The development of Fourier transform mm-wave spectrometers using high peak power (30 mW) active multiplier chain mm-wave sources brings new measurement capabilities to the analysis of complex gas mixtures. Strategies for gas analysis based on high-throughput mm-wave spectroscopy and arbitrary waveform generator driven mm-wave sources are described. Several new measurement capabilities come from the intrinsic time-domain measurement technique. High-sensitivity double-resonance measurements can be performed to speed the analysis of a complex gas sample containing several species. This technique uses a "pi-pulse" to selectively invert the population of two selected rotational energy levels and the effect of this excitation pulse on all other transitions in the spectrometer operating range is monitored using segmented chirped-pulse Fourier transform spectroscopy. This method can lead to automated determination of the molecular rotational constants. Rapid pulse duration scan experiments can be used to estimate the magnitude and direction of the dipole moment of the molecule from an unknown spectrum. Coherent pulse echo experiments, using the traditional Hahn sequence or two-color population recovery methods, can be used to determine the collisional relaxation rate of the unknown molecule. This rate determination improves the ability to estimate the mass of the unknown molecule from the determination of the Doppler dephasing rate. By performing a suite of automated, high-throughput measurements, there is the potential to determine the shape (via the rotational constant), electric properties (the dipole moments and its direction in the principal axis system), and the mass of the molecule to aid its identification.

Harris, Brent J.; Steber, Amanda L.; Lehmann, Kevin K.; Pate, Brooks H.

2013-06-01

231

ISL 500 kJ 15 mm railgun numerical simulation  

NASA Astrophysics Data System (ADS)

The study presents a numerical simulation of the mechanical and electromagnetic behavior of a 15-mm round bore railgun. The electromagnetic calculations were performed with the MSC/EMAS finite element code. The calculated electromagnetic forces acting on the structure serve as an input for the MSC/DYNA finite element code. The theoretical results are compared to the experimental measurements on the 400-kJ drive railgun. This model is used to compare the behavior of a solid armature with the current input at the backside to front-fed solid armatures. Several optimizations of the present design are proposed.

Kienner, Philippe; Kitzinger, Klaus

1993-01-01

232

Maps based on 53 GHz (5.7 mm wavelength)  

NASA Technical Reports Server (NTRS)

Maps based on 53 GHz (5.7 mm wavelength) observations made with the DMR over the entire 4-year mission (top) on a scale from 0 - 4 K, showing the near-uniformity of the CMB brightness, (middle) on a scale intended to enhance the contrast due to the dipole described in the slide 19 caption, and (bottom) following subtraction of the dipole component. Emission from the Milky Way Galaxy is evident in the bottom image. See slide 19 caption for information about map smoothing and projection.

2002-01-01

233

Stability of 35 mm Scanners as Used in Ophthalmologic Research  

PubMed Central

Background and Objective To assess the consistency of digitization of 35mm slides, as practiced in ophthalmologic research and estimate the impact of variation on semi-automated retinal vessel width measurements. Study Design and Methods A single retina slide was repeatedly digitized under various conditions on three scanner models. Average color levels were extracted from the resulting images, from which vessel widths were graded. The color channel level variations and possible correlation with width were analyzed. Results The Nikon 5000 scanner had average coefficients of variation (CV) of 0.4, 2.3, and 0.5 for the red, green, and blue channel levels across all runs. The p-values of the correlation between the red, green, and blue color channel levels, and the width of the large retinal arteriole, were 0.89, 0.27, and 0.58. Conclusion Our results suggest that the tested scanners digitize the 35mm slides in a reliable manner without biasing the retinal vessel measurements.

Jensen, Karl; Lee, Kristine E.; Knudtson, Michael D.; Klein, Ronald; Klein, Barbara E.K.

2009-01-01

234

Multilayer Laue Lenses with Focal Length of 10 mm  

NASA Astrophysics Data System (ADS)

Multilayer laue lenses are diffractive optics with a high potential for producing X-ray foci in the order of 10 nm or even below. Particularly for hard X-rays (E > 6 keV) these optics promise better resolution and higher efficiencies than currently available Fresnel zone plates. Magnetron sputter deposition has been used for the fabrication of multilayer laue lenses using the layer materials MoSi2 and Si. The lens design has been defined to get focal length in the order of 10 mm. One of the lenses with an aperture of about 20 ?m has been used as focusing optics in the nanoprobe beamline P06 at PETRA III. Ptychography has been applied to characterize the caustic of the focused beam and to determine the size of the X-ray focus. A spot size of about 39 nm could be obtained with a photon energy of 21 keV and a focal length of 9.9 mm.

Braun, S.; Kubec, A.; Menzel, M.; Niese, S.; Krüger, P.; Seiboth, F.; Patommel, J.; Schroer, C.

2013-03-01

235

[Cataract operation with the 7 mm clear cornea incision].  

PubMed

Cataract surgery can be combined with the correction of high preoperative astigmatism by using a corneal tunnel incision in the steep meridian. We examined 37 patients (mean age 70 years) with cataract and a mean preoperative astigmatism of 3.6 D (2.0-4.75 D). A 7-mm clear corneal incision was made for phacoemulsification and thus a reduction in the astigmatism was achieved. The mean induced astigmatism was 3.6 D (SD 1.6 D minium 0.8 D, maximum 7.5 D) on the first postoperative day and 2.7 D (SD 0.9 D, minimum 1.6 D, maximum 4.9 D) after 10 months. By modification of the incision technique with a trapezoidal corneal incision and a single radial suture the wound closure was more stable, but the astigmatic correction did not change significantly compared to the results after the original 7-mm clear corneal incision technique. PMID:8867152

Grote, A; Pham, D T; Wollensak, J

1996-02-01

236

A 14-megapixel 36 x 24-mm2 image sensor  

NASA Astrophysics Data System (ADS)

We will present a 3044 x 4556 pixels CMOS image sensor with a pixel array of 36 x 24 mm2, equal to the size of 35 mm film. Though primarily developed for digital photography, the compatibility of the device with standard optics for film cameras makes the device also attractive for machine vision applications as well as many scientific and highresolution applications. The sensor makes use of a standard rolling shutter 3-transistor active pixel in standard 0.35 ?m CMOS technology. On-chip double sampling is used to reduce fixed pattern noise. The pixel is 8 ?m large, has 60,000 electrons full well charge and a conversion gain of 18.5 ?V/electron. The product of quantum efficiency and fill factor of the monochrome device is 40%. Temporal noise is 35 electrons, offering a dynamic range of 65.4 dB. Dark current is 4.2 mV/s at 30 degrees C. Fixed pattern noise is less than 1.5 mV RMS over the entire focal plane and less than 1 mV RMS in local windows of 32 x 32 pixels. The sensor is read out over 4 parallel outputs at 15 MHz each, offering 3.2 images/second. The device runs at 3.3 V and consumes 200 mW.

Meynants, Guy; Scheffer, Danny; Dierickx, Bart; Alaerts, Andre

2004-06-01

237

Resonant biaxial 7-mm MEMS mirror for omnidirectional scanning  

NASA Astrophysics Data System (ADS)

Low-cost automotive laser scanners for environment perception are needed to enable the integration of advanced driver assistant systems (ADAS) into all automotive vehicle segments, a key to reducing the number of traffic accidents on roads. An omnidirectional 360 degree laser scanning concept has been developed based on combination of an omnidirectional lens and a biaxial large aperture MEMS mirror. This omnidirectional scanning concept is the core of a small sized low-cost time-of-flight based range sensor development. This paper describes concept, design, fabrication and first measurement results of a resonant biaxial 7mm gimbal-less MEMS mirror that is electrostatically actuated by stacked vertical comb drives. Identical frequencies of the two resonant axes are necessary to enable the required circle scanning capability. A tripod suspension was chosen since it allows minimizing the frequency splitting of the two resonant axes. Low mirror curvature is achieved by a thickness of the mirror of more than 500 ?m. Hermetic wafer level vacuum packaging of such large mirrors based on multiple wafer bonding has been developed to enable to achieve a large mechanical tilt angle of +/- 6.5 degrees in each axis. The 7mm-MEMS mirror demonstrates large angle circular scanning at 1.5kHz.

Hofmann, U.; Aikio, M.; Janes, J.; Senger, F.; Stenchly, V.; Weiss, M.; Quenzer, H.-J.; Wagner, B.; Benecke, W.

2013-03-01

238

The 0.3 mm diameter flexible amperometric lactate probe  

NASA Astrophysics Data System (ADS)

A flexible lactate electrode was made of 400 +/- 100 7 micrometers diameter carbon fibers, epoxy embedded in a 0.3 mm diameter polyimide tubing. The electrode was modified by precipitating on it the relatively insoluble complex formed between 1100 kd partially N-ethylamine quaternized poly((vinylpyridine)Os(bipyridine)2Cl)Cl (POs-EA) and lactate oxidase. The steady-state lactate electrooxidation current, at 2mM lactate concentration and at 22 C, was 4OO nA. The 5O +/- 10 microA/sq cm current density and the 2OmA/sq cm/M sensitivity decreased only by 5 percent upon increasing the partial pressure of oxygen from 0.0 to 0.2 atm. The electrode retains its sensitivity after dry storage at 4 C for 4 months in air but loses at 37 C half of its sensitivity in 7 hours through polymer desorption when operated at 0.4V (SCE).

Wang, Dan L.; Heller, Adam

1993-01-01

239

Stress relaxation in SSC 50mm dipole coils  

SciTech Connect

We are measuring the stress relaxation of SSC 50mm outer coils with the goal of predicting how much of the coil prestress will be lost while the coils are warehoused between manufacture and cooldown. We manufacture 3 inch (76.2mm) long segments of coil with the same materials and techniques that have been used for prototype coils. We are running four simultaneous tests in an attempt to separate the contributions of the different coil materials. Test one is a completely insulated coil section where the insulation is the all polyamide system being tested at Brookhaven; test two is a wire stack insulated only with the normal Kapton overwrap; test three is a stack of bare cable; and test four is a completely insulated normal coil section. All, except for the bare cable, include the ground insulation. The insulated coil sections are carefully dried before loading and testing in order to eliminate stress changes due to varying moisture content. The temperature dependence of the stress relaxation is being studied separately. Three companion papers presented at this conference will be: (1) Temperature dependence of the viscoelastic properties of SSC coil insulation'' (2) Measurement of the elastic modulus of Kapton perpendicular to the plane of the film at room and cryogenic temperatures'' (3) Theoretical methods for creep and stress relaxation studies of SSC coil.''

Rogers, D.; Markley, F.

1992-04-01

240

Using 70-mm aerial photography to identify rangeland sites  

NASA Technical Reports Server (NTRS)

A south Texas rangeland area was used as a study site to test the use of microdensitometry on 70-mm color-infrared and black-and-white photographs (scale 1:19,000) for distinguishing among 11 range sites (two brushland, seven grassland, two barren land) during the winter (February), spring (May), and summer (August) of 1976. Color-infrared photographs were also taken at a scale of 1:42,000 for the summer date. Film optical density readings were made on one color-infrared film with white light only. The best separations among density readings for all range sites were obtained using white light exposed on color-infrared film in the summer when vegetation was at peak foliage development. Results from this study indicate that 70-mm aerial color-infrared photography at a scale of 1:19,000 or 1:42,000 has good potential for identifying range sites in large and inaccessible areas, and could be a useful tool for range management.

Everitt, J. H.; Gerbermann, A. H.; Alaniz, M. A.; Bowen, R. L.

1980-01-01

241

Stability of recombinant green fluorescent protein (GFPuv) in glucose solutions at different concentrations and pH values  

Microsoft Academic Search

The stability at room temperature (25°C) of recombinant green fluorescent protein (GFPuv), expressed by Escherichia coli cells and isolated by three-phase partitioning extraction with hydrophobic interaction column, was studied. The GFPuv was\\u000a diluted in buffered (each 10 mM: Tris-HCl, pH 8.0; phosphate, pH 6.0 and 7.0 and acetate, pH 5.0) and in unbuffered (water for injection [WFI]; pH 6.70 ±

Thereza Christina Vessoni Penna; Marina Ishii; Juliana Sayuri Kunimura; Olivia Cholewa

2005-01-01

242

Stability of Recombinant Green Fluorescent Protein (GFPuv) in Glucose Solutions at Different Concentrations and pH Values  

Microsoft Academic Search

The stability at room temperature (25°C) of recombinant green fluorescent protein (GFPuv), expressed by Escherichia coli cells and isolated by three-phase partitioning extraction with hydrophobic interaction column, was studied. The GFPuv was\\u000a diluted in buffered (each 10 mM: Tris-HCl, pH 8.0; phosphate, pH 6.0 and 7.0 and acetate, pH 5.0) and in unbuffered (water\\u000a for injection [WFI]; pH 6.70 ±

THEREZA CHRISTINA VESSONI PENNAr; Marina Ishii; Juliana Sayuri Kunimura; Olivia Cholewa

243

Ionic and pH effects on the osmotic properties and structure of polyelectrolyte gels  

PubMed Central

We investigate the effects of salt concentration and pH on neutralized poly(acrylic acid) (PAA) gels in near physiological salt solutions. Either adding calcium ions or decreasing the pH are found to induce reversible volume transitions but the nature of these transitions seems to be different. For example, the osmotic pressure exhibits a simple power law dependence on the concentration as the transition is approached in both systems, but the power law exponent n is substantially different in the two cases. On decreasing the pH the value of n gradually increases from 2.1 (at pH = 7) to 3.2 (at pH = 1). By contrast, n decreases with increasing calcium ion concentration from 2.1 (in 100 mM NaCl solution) to 1.6 (0.8 mM CaCl2 in 100 mM NaCl solution). In both systems, a strong increase of the small-angle neutron scattering intensity (SANS) is observed near the volume transition. The SANS results reveal that calcium ions favor the formation of linearly aligned regions in PAA gels.

Horkay, Ferenc; Basser, Peter J.

2009-01-01

244

Online PH measurement technique in seawater desalination  

NASA Astrophysics Data System (ADS)

The measurement technology of pH is essential in seawater desalination. Glass electrode is the main pH sensor in seawater desalination. Because the internal impedance of glass electrode is high and the signal of pH sensor is easy to be disturbed, a signal processing circuit with high input impedance was designed. Because of high salinity of seawater and the characteristic of glass electrode, ultrasonic cleaning technology was used to online clean pH sensor. Temperature compensation was also designed to reduce the measurement error caused by variety of environment temperature. Additionally, the potential drift of pH sensor was analyzed and an automatic calibration method was proposed. In order to online monitor the variety of pH in seawater desalination, three operating modes were designed. The three modes are online monitoring mode, ultrasonic cleaning mode and auto-calibration mode. The current pH in seawater desalination was measured and displayed in online monitoring mode. The cleaning process of pH sensor was done in ultrasonic cleaning mode. The calibration of pH sensor was finished in auto-calibration mode. The result of experiments showed that the measurement technology of pH could meet the technical requirements for desalination. The glass electrode could be promptly and online cleaned and its service life was lengthened greatly.

Wang, Haibo; Wu, Kaihua; Hu, Shaopeng

2009-11-01

245

Intracellular pH changes induced by calcium influx during electrical activity in molluscan neurons  

PubMed Central

Simultaneous measurements of electrical activity and light absorbance have been made on nerve cell bodies from Archidoris monteryensis injected with indicator dyes. pH indicators, phenol red and bromocresol purple, and arsenazo III, which under normal conditions is primarily a calcium indicator have been employed. Voltage clamp pulses which induced calcium influx caused an absorbance decrease of the pH dyes indicating an internal acidification. The onset of the pH drop lagged the onset of Ca2+ influx by 200-400 ms, and pH continued to decrease for several seconds after pulse termination which shut off Ca2+ influx. Trains of action potentials also produced an internal pH decrease. Recovery of the pH change required periods greater than 10 min. The magnitude of the pH change was largely unaffected by external pH in the range 6.8-8.4. The voltage dependence of the internal p/ change was similar to the voltage dependence of calcium influx determined by arsenazo III, and removal of calcium from the bathing saline eliminated the pH signal. In neurons injected with EGTA (1-5 mM), the activity- induced internal Ca2+ changes were reduced or eliminated, but the internal pH drop was increased severalfold in magnitude. After the injection of EGTA, voltage clamp pulses produced a decrease in arsenazo III absorbance instead of the normal increase. Under these conditions the dye was responding primarily to changes in internal pH. Injection of H+ caused a rise in internal free calcium. The pH buffering capacity of the neurons was measured using three different techniques: H+ injection, depressing intrinsic pH changes with a pH buffer, and a method employing the EGTA-calcium reaction. The first two methods gave similar measurements: 4-9 meq/unit pH per liter for pleural ganglion cells and 13-26 meq/unit pH per liter for pedal ganglion cells. The EGTA method gave significantly higher values (20-60 meq/unit pH per liter) and showed no difference between pleural and pedal neurons.

1980-01-01

246

Coupling MM5 with ISOLSM: Development, testing, and applications  

SciTech Connect

Surface water and energy fluxes are tightly coupled with CO2 exchanges between the ecosystem and atmosphere. Other surface-to-atmosphere trace-gas exchanges of interest in climate change research (e.g., N2O, CH4, C18OO, and H218O) are also strongly impacted by surface energy exchanges. Further, land-use change has large effects on the surface energy balance and therefore the exchanges of these trace gases. To investigate these issues at the regional scale we have coupled MM5 (Grell et al. 1995) with ISOLSM (Riley et al. 2002, Riley et al. 2003), a land-surface model based on LSM1 (Bonan 1995).

Riley, W.J.; Cooley, H.S.; He, Y.; Torn, M.S.

2003-06-10

247

A densitometric analysis of commercial 35mm films  

NASA Technical Reports Server (NTRS)

IIaO films have been subjected to various sensitometric tests. The have included thermal and aging effects and reciprocity failure studies. In order to compare the special IIaO film with popular brands of 35 mm films and their possible use in astrophotography, Agfa, Fuji and Kodak print and slide formats, as well as black and white and color formats, were subjected to sensitometric, as well as densitometric analysis. A scanning electron microscope was used to analyze grain structure size, and shape as a function of both speed and brand. Preliminary analysis of the grain structure using an ISI-SS40 scanning electron microscope indicates that the grain sizes for darker densities are much larger than the grain size for lighter densities. Researchers analyze the scanning electron microscope findings of the various grains versus densities as well as enhancement of the grains, using the IP-8500 Digital Image Processor.

Hammond, Ernest C., Jr.; Ruffin, Christopher, III

1989-01-01

248

40 mm bore Nb-Ti model dipole magnet  

SciTech Connect

Preliminary R and D has been started on magnets for a next-generation high-energy-physics accelerator, the 20 TeV Superconducting Supercollider (SSC). One design now being developed at LBL is described in this paper. The design is based on two layers of flattened Nb-Ti cable, a 40 mm ID winding with flared ends, and an operating field of 6.5 T. Experimental results are presented on several one-meter-long models tested at both He I and He II temperature. Measurement of field, residual magnetization, quench propagation velocity, and winding prestress are presented. (A 2-in-1 magnet based on this coil design is being jointly developed by LBL and Brookhaven National Laboratory, and 15 ft. long models are being constructed at BNL).

Taylor, C.; Gilbert, W.; Hassenzahl, W.; Meuser, R.; Peters, C.; Rechen, J.; Scanlan, R.

1984-09-10

249

Supersonic Love waves in strong piezoelectrics of symmetry mm2  

SciTech Connect

A study has been made of the Love wave propagation on piezoelectric substrates of symmetry mm2. It has been shown that under certain conditions the velocity of the Love wave exceeds that of shear horizontal (SH) bulk waves in the substrate. This occurs when the slowness curve of SH bulk waves in the substrate either has a concavity or is convex with nearly zero curvature. For such {open_quotes}supersonic{close_quotes} Love waves to appear, it is also required that the substrate as well as the layer be specially oriented and that their material constants fulfill a number of inequalities. Numerical computations have been carried out for a number of structures. The results of numerical computations have been compared with approximate analytical estimations. {copyright} 2001 American Institute of Physics.

Darinskii, A. N.; Weihnacht, M.

2001-07-01

250

A mm-wave homogeneous ferrite phase scan antenna  

NASA Astrophysics Data System (ADS)

A concept for a mm-wave ferrite phase scan antenna is presented along with the design and the results of a 35-GHz test antenna. The antenna is fabricated by cutting periodic grooves into the side wall of an optimized (low loss, broadband) ferrite-type dielectric waveguide, thereby forming a series of radiating elements. This simple low-cost structure contains within one homogeneous ferrite rod the transmission line, phase shift section, and radiating aperture, with no discrete components to be assembled for aperture integration. The phase shifter design which can provide up to 360 deg/inch of reciprocal phase shift with an insertion loss of less than 0.6 dB/inch is described. The measurements of the antenna gain with respect to a standard gain horn indicated gains of 11 dB.

Stern, Richard A.; Babbitt, Richard W.; Borowick, John

1987-04-01

251

Phase correlator reduces mm-wave radar cost  

NASA Astrophysics Data System (ADS)

A technique involving the IC storage of magnetron phase for reference has been developed to make possible the use of the low-cost efficient magnetron in obtaining phase coherent signals for pulse Doppler radar. In the new external coherence method, the recorded random midpulse-region phase is compared with the frequency of the echo allowing Doppler information, free of phase noise, to be extracted. The gated magnetron was tested at Ka-band in a 35-GHz radar, and good agreement with the CP-4 5.5 GHz radar was shown. With good accuracy down to 10 cm/s, the present system, especially in the mm-wave region, has important applications to meteorological and military radar.

Weiss, R., Sr.; Hobbs, P.; Locatelli, J.

1986-03-01

252

The Apollo 15 coarse fines (4-10 mm)  

NASA Technical Reports Server (NTRS)

A new catalog of the Apollo 15 coarse fines particles is presented. Powell's macroscopic descriptions, resulting from his 1972 particle by particle binocular examination of all of the Apollo 15 4 to 10 mm fines samples, are retained. His groupings are also retained, but petrographic, chemical, and other data from later analyses are incorporated into this catalog to better characterize individual particles and describe the groups. A large number of particles have no characterization beyond that done by Powell. Complete descriptions of the particles and all known references are provided. The catalog is intended for anyone interested in the rock types collected by Dave Scott and Jim Irwin in the Hadley-Appenine region, and particularly for researchers requiring sample allocations.

Ryder, Graham; Sherman, Sarah Bean

1989-01-01

253

MM Herculis - An eclipsing binary of the RS CVn  

NASA Technical Reports Server (NTRS)

V, B and U differential photoelectric photometry has been obtained for the RS Canum Venaticorum-class eclipsing binary star MM Her, with the light outside the eclipse being Fourier-analyzed to study wave migration and amplitude. These, together with the mean light level of the system, have been monitored from 1976 through 1980. Observations within the eclipse have revealed eclipses to be partial, rather than total as previously thought. The geometric elements of the presently rectified light curve are forced on the pre-1980 light curves and found to be compatible. With these elements, and previously obtained double line radial velocity curves, new absolute dimensions of 1.18 solar masses and 1.58 solar radii are calculated for the hotter star and 1.27 solar masses and 2.83 solar radii for the cooler star. The plotting of color indices on the color-color curve indicates G2V and K2IV spectral types.

Sowell, J. R.; Hall, D. S.; Henry, G. W.; Burke, E. W., Jr.; Milone, E. F.

1983-01-01

254

Comparison of less lethal 40 mm sponge projectile and the 37 mm projectile for injury assessment on human thorax  

NASA Astrophysics Data System (ADS)

Since there is an increasing interest in avoiding human body injury in diverse situations like crowd control or peacekeeping missions, less lethal ammunition are more and more used. In this study we focus only on kinetic energy non-lethal (KENLW) projectiles. Their desired effects on human body are the temporary incapacitation through blunt trauma. There are different types of KENLW projectiles ranging from rigid to deformable projectiles. Unfortunately, the effects of such projectiles are not really well known as it is difficult to measure the force transmitted to the human body or the related deformation. Because the potential of injury excludes human living tests, tests are performed on cadavers, animals or human tissue surrogates. Besides these tests, numerical simulations are more and more used to gain more understanding, to assess or to predict the effects of this kind of projectile on human body. In this paper a comparison based on the viscous criterion between the 37 mm rigid projectile and the 40 mm sponge projectile was made.

Nsiampa, N.; Robbe, C.; Oukara, A.; Papy, A.

2012-08-01

255

Modelling and performance of Nb SIS mixers in the 1.3 mm and 0.8 mm bands  

NASA Technical Reports Server (NTRS)

We describe the modeling and subsequent improvements of SIS waveguide mixers for the 200-270 and 330-370 GHz bands (Blundell, Carter, and Gundlach 1988, Carter et al 1991). These mixers are constructed for use in receivers on IRAM radiotelescopes on Pico Veleta (Spain, Sierra Nevada) and Plateau de Bure (French Alps), and must meet specific requirements. The standard reduced height waveguide structure with suspended stripline is first analyzed and a model is validated through comparison with scale model and working scale measurements. In the first step, the intrinsic limitations of the standard mixer structure are identified, and the parameters are optimized bearing in mind the radioastronomical applications. In the second step, inductive tuning of the junctions is introduced and optimized for minimum noise and maximum bandwidth. In the 1.3 mm band, a DSB receiver temperature of less than 110 K (minimum 80 K) is measured from 180 through 260 GHz. In the 0.8 mm band, a DSB receiver temperature of less than 250 K (minimum 175 K) is obtained between 325 and 355 GHz. All these results are obtained with room-temperature optics and a 4 GHz IF chain having a 500 MHz bandwidth and a noise temperature of 14 K.

Karpov, A.; Carter, M.; Lazareff, B.; Billon-Pierron, D.; Gundlach, K. H.

1992-01-01

256

Error Growth Rate in the MM5 Model  

NASA Astrophysics Data System (ADS)

The goal of this work is to estimate model error growth rates in simulations of the atmospheric circulation by the MM5 model all the way from the short range to the medium range and beyond. The major topics are addressed to: (i) search the optimal set of parameterization schemes; (ii) evaluate the spatial structure and scales of the model error for various atmospheric fields; (iii) determine geographical regions where model errors are largest; (iv) define particular atmospheric patterns contributing to the fast and significant model error growth. Results are presented for geopotential, temperature, relative humidity and horizontal wind components fields on standard surfaces over the Atlantic-European region during winter 2002. Various combinations of parameterization schemes for cumulus, PBL, moisture and radiation are used to identify which one provides a lesser difference between the model state and analysis. The comparison of the model fields is carried out versus ERA-40 reanalysis of the ECMWF. Results show that the rate, at which the model error grows as well as its magnitude, varies depending on the forecast range, atmospheric variable and level. The typical spatial scale and structure of the model error also depends on the particular atmospheric variable. The distribution of the model error over the domain can be separated in two parts: the steady and transient. The first part is associated with a few high mountain regions including Greenland, where model error is larger. The transient model error mainly moves along with areas of high gradients in the atmospheric flow. Acknowledgement: This study has been supported by NATO Science for Peace grant #981044. The MM5 modelling system used in this study has been provided by UCAR. ERA-40 re-analysis data have been obtained from the ECMWF data server.

Ivanov, S.; Palamarchuk, J.

2006-12-01

257

300mm pilot line DSA contact hole process stability  

NASA Astrophysics Data System (ADS)

Directed Self-Assembly (DSA) is today a credible alternative lithographic technology for semiconductor industry [1]. In the coming years, DSA integration could be a standard complementary step with other lithographic techniques (193nm immersion, e-beam, extreme ultraviolet). Its main advantages are a high pattern resolution (down to 10nm), a capability to decrease an initial pattern edge roughness [2], an absorption of pattern guide size variation, no requirement of a high-resolution mask and can use standard fab-equipment (tracks and etch tools). The potential of DSA must next be confirmed viable for high volume manufacturing. Developments are necessary to transfer this technology on 300mm wafers in order to demonstrate semiconductor fab-compatibility [3-7]. The challenges concern especially the stability, both uniformity and defectivity, of the entire process, including tools and Blok Co-Polymer (BCP) materials. To investigate the DSA process stability, a 300mm pilot line with DSA dedicated track (SOKUDO DUO) is used at CEALeti. BCP morphologies with PMMA cylinders in a PS matrix are investigated (about 35nm natural period). BCP selfassembly in unpatterned surface and patterned surface (graphoepitaxy) configurations are considered in this study. Unpatterned configuration will initially be used for process optimization and fix a process of record. Secondly, this process of record will be monitored with a follow-up in order to validate its stability. Steps optimization will be applied to patterned surface configurations (graphoepitaxy) for contact hole patterning application. A process window of contact hole shrink process will be defined. Process stability (CD uniformity and defectivity related to BCP lithography) will be investigated.

Argoud, M.; Servin, I.; Gharbi, A.; Pimenta Barros, P.; Jullian, K.; Sanche, M.; Chamiot-Maitral, G.; Barnola, S.; Tiron, R.; Navarro, C.; Chevalier, X.; Nicolet, C.; Fleury, G.; Hadziioannou, G.; Asai, M.; Pieczulewski, C.

2014-03-01

258

Improved mm-wave photometry for kinetic inductance detectors  

NASA Astrophysics Data System (ADS)

Context. We have developed a dual-band (140 and 220 GHz) mm-wave imaging camera based on superconducting kinetic inductance detector (KID) arrays. Each array contains 132 superconducting resonators whose resonant frequencies are shifted by mm-wave photons absorption. The read out is achieved with a single electronics chain per band, taking advantage of the intrinsic KID frequency-domain multiplexability. The arrays are easily scalable and well adapted for future large format focal plane instruments. NIKA (formerly Néel IRAM KID Array, now New IRAM KID Array) has been specifically designed for the IRAM 30 m telescope at Pico Veleta, and is one of the first instruments using KIDs to have made measurements of astronomical sources. Aims: In this Letter we describe the solutions adopted to improve the calibration accuracy and the sensitivity of the instrument, and we report on the outcome of the 3rd NIKA observing run of October, 2011. Methods: We use a fast electronic modulation of the readout tone for each KID pixel in order to linearize the instrument calibration, which we track with measurements of planets. We also adopt a new design of the KIDs, sensitive to both polarizations, to increase the amount of radiation absorbed and thus the optical efficiency of the system. Results: We measured an average sensitivity on the sky of 21 mJys0.5 per beam at 140 GHz and 140 mJys0.5 at 220 GHz in the best observing conditions (?220 ? 0.2) after atmospheric noise decorrelation. The sensitivity at 220 GHz was limited by the atmospheric attenuation and loading as well as a reduction in the spectral bandwidth due to a misplaced filter. We found the repeatability in the photometry over the entire observing run to be better than 10% in both bands, thus demonstrating a significant improvement over the previous runs. We also find good agreement between NIKA measurements of faint astronomical sources and previous measurements of the same sources.

Calvo, M.; Roesch, M.; Désert, F.-X.; Monfardini, A.; Benoit, A.; Mauskopf, P.; Ade, P.; Boudou, N.; Bourrion, O.; Camus, P.; Cruciani, A.; Doyle, S.; Hoffmann, C.; Leclercq, S.; Macias-Perez, J. F.; Ponthieu, N.; Schuster, K. F.; Tucker, C.; Vescovi, C.

2013-03-01

259

The influence of calcium and pH on growth in primary roots of Zea mays  

NASA Technical Reports Server (NTRS)

We investigated the interaction of Ca2+ and pH on root elongation in Zea mays L. cv. B73 x Missouri 17 and cv. Merit. Seedlings were raised to contain high levels of Ca2+ (HC, imbibed and raised in 10 mM CaCl2) or low levels of Ca2+ (LC, imbibed and raised in distilled water). In HC roots, lowering the pH (5 mM MES/Tris) from 6.5 to 4.5 resulted in strong, long-lasting growth promotion. Surprisingly, increasing the pH from 6.5 to 8.5 also resulted in strong growth promotion. In LC roots acidification of the medium (pH 6.5 to 4.5) resulted in transient growth stimulation followed by a gradual decline in the growth rate toward zero. Exposure of LC roots to high pH (pH shift from 6.5 to 8.5) also promoted growth. Addition of EGTA resulted in strong growth promotion in both LC and HC roots. The ability of EGTA to stimulate growth appeared not to be related to H+ release from EGTA upon Ca2+ chelation since, 1) LC roots showed a strong and prolonged response to EGTA, but only a transient response to acid pH, and 2) promotion of growth by EGTA was observed in strongly buffered solutions. We also examined the pH dependence of the release of 45Ca2+ from roots of 3-day-old seedlings grown from grains imbibed in 45Ca2+. Release of 45Ca2+ from the root into agar blocks placed on the root surface was greater the more acidic the pH of the blocks. The results indicate that Ca2+ may be necessary for the acid growth response in roots.

Hasenstein, K. H.; Evans, M. L.

1988-01-01

260

Experimentally and theoretically observed native pH shifts in a nanochannel array  

PubMed Central

Lab-on-a-chip (LOC) technology provides a powerful platform for simultaneous separation, purification, and identification of low concentration multicomponent mixtures. As the characteristic dimension of LOC devices decreases down to the nanoscale, the possibility of containing an entire lab on a single chip is becoming a reality. This research examines one of the unique physical characteristics of nanochannels, in which native pH shifts occur. As a result of the electrical double layer taking up a significant portion of a 100 nm wide nanochannel, electroneutrality no longer exists in the channel causing a radial pH gradient. This work describes experimentally observed pH shifts as a function of ionic strength using the fluorescent pH indicator 5-(and-6)-carboxy SNARF®-1 and compares it to a model developed using Comsol Multiphysics. At low ionic strengths (~ 3 mM) the mean pH shift is approximately 1 pH unit whereas at high ionic strengths (~ 150 mM) the mean pH shift is reduced to 0.1 pH units. An independent analysis using fluorescein pH indicator is also presented supporting these findings. Two independent non-linear simulations coupling the Nernst-Planck equation describing transport in ionic solutions subjected to an electric field and Poisson's equation to describe the electric field as it relates to the charge distribution are solved using a finite element solver. In addition, the effects of chemical activities are considered in the simulations. The first numerical simulation is based on a surface ?-potential which significantly underestimates the experimental results for most ionic strengths. A modified model assuming that SNARF and fluorescein molecules are able to diffuse into the hydrolyzed SiO2 phase, and in the case of the SNARF molecule, able to bind to neutral regions of the SiO2 phase agrees quantitatively with experimental results.

Bottenus, Danny; Oh, Youn-Jin; Han, Sang M.; Ivory, Cornelius F.

2010-01-01

261

Influence of five neutralizing products on intra-oral pH after rinsing with simulated gastric acid.  

PubMed

The aetiology of dental erosion may be of both extrinsic and intrinsic origin. The aim of the present study was to test the ability of various neutralizing products to raise the low intra-oral pH after an erosive exposure, in this case to gastric acid, which was simulated using hydrochloric acid (HCl). Eleven adults participated. They rinsed with 10 ml of 10 mM HCl (pH 2) or 10 ml of 100 mM HCl (pH 1) for 1 min, after which the pH was measured intra-orally for up to 30 min at four sites (two approximal, one buccal, and the dorsum of the tongue). After rinsing with the two acid solutions (pH 1 and pH 2), the following products were used: (i) antacid tablet; (ii) gum arabic lozenge; (iii) mineral water; (iv) milk; and (v) tap water (positive control). The negative control was no product use. The five test products were used for 2 min after the erosive challenge. All the products produced an initially higher pH compared with the negative control. The antacid tablet resulted in the greatest and most rapid increase in pH, followed by the lozenge. In dental practice, the use of any of the neutralizing products tested, especially the antacid tablet, could be recommended in order to increase the intra-oral pH after an erosive challenge. PMID:21726291

Lindquist, Birgitta; Lingström, Peter; Fändriks, Lars; Birkhed, Dowen

2011-08-01

262

Stabilization of pH in solid-matrix hydroponic systems  

NASA Technical Reports Server (NTRS)

2-[N-morpholino]ethanesulfonic acid (MES) buffer or Amberlite DP-1 (cation-exchange resin beads) were used to stabilize substrate pH of passive-wicking, solid-matrix hydroponic systems in which small canopies of Brassica napus L. (CrGC 5-2, genome : ACaacc) were grown to maturity. Two concentrations of MES (5 or 10 mM) were included in Hoagland 1 nutrient solution. Alternatively, resin beads were incorporated into the 2 vermiculite : 1 perlite (v/v) growth medium at 6% or 12% of total substrate volume. Both strategies stabilized pH without toxic side effects on plants. Average seed yield rates for all four pH stabilization treatments (13.3 to 16.9 g m-2 day-1) were about double that of the control (8.2 g m-2 day-1), for which there was no attempt to buffer substrate pH. Both the highest canopy seed yield rate (16.9 g m-2 day-1) and the highest shoot harvest index (19.5%) occurred with the 6% resin bead treatment, even though the 10 mM MES and 12% bead treatments maintained pH within the narrowest limits. The pH stabilization methods tested did not significantly affect seed oil and protein contents.

Frick, J.; Mitchell, C. A.

1993-01-01

263

Dynamic regulation of gastric surface pH by luminal pH  

PubMed Central

In vivo confocal imaging of the mucosal surface of rat stomach was used to measure pH noninvasively under the mucus gel layer while simultaneously imaging mucus gel thickness and tissue architecture. When tissue was superfused at pH 3, the 25 ?m adjacent to the epithelial surface was relatively alkaline (pH 4.1 ± 0.1), and surface alkalinity was enhanced by topical dimethyl prostaglandin E2 (pH 4.8 ± 0.2). Luminal pH was changed from pH 3 to pH 5 to mimic the fasted-to-fed transition in intragastric pH in rats. Under pH 5 superfusion, surface pH was relatively acidic (pH 4.2 ± 0.2). This surface acidity was enhanced by pentagastrin (pH 3.5 ± 0.2) and eliminated by omeprazole, implicating parietal cell H,K-ATPase as the dominant regulator of surface pH under pH 5 superfusion. With either pH 5 or pH 3 superfusion (a) gastric pit lumens had the most divergent pH from luminal superfusates; (b) qualitatively similar results were observed with and without superfusion flow; (c) local mucus gel thickness was a poor predictor of surface pH values; and (d) no channels carrying primary gastric gland fluid through the mucus were observed. The model of gastric defense that includes an alkaline mucus gel and viscous fingering of secreted acid through the mucus may be appropriate at the intragastric pH of the fasted, but not fed, animal. J. Clin. Invest. 103:605–612 (1999)

Chu, Shaoyou; Tanaka, Shin; Kaunitz, Jonathan D.; Montrose, Marshall H.

1999-01-01

264

Functional photoacoustic microscopy of pH  

Microsoft Academic Search

pH is a tightly regulated indicator of metabolic activity. In mammalian systems, an imbalance of pH regulation may result from or result in serious illness. In this paper, we report photoacoustic microscopy (PAM) of a commercially available pH-sensitive fluorescent dye (SNARF-5F carboxylic acid) in tissue phantoms. We demonstrated that PAM is capable of pH imaging in absolute values at tissue

Muhammad Rameez Chatni; Junjie Yao; Amos Danielli; Christopher P. Favazza; Konstantin I. Maslov; Lihong V. Wang

2011-01-01

265

The PH20 Protein in Human Spermatozoa  

Microsoft Academic Search

PH-20 is a sperm plasma-membrane protein that has been shown to have hyaluronidase activity in several mammalian species including nonhuman primates. In this investigation, the PH-20 protein was characterized in noncapacitated human sperm and in capacitated human sperm. Two forms of PH-20 were ob- served in immunoblots of sodium dodecylsulfate polyacrylamide-gel electrophoresis (SDS PAGE) using a polyclonal antibody to recom-

KHALIDA SABEUR; GARY N. CHERR; ASHLEY I. YUDIN; PAUL PRIMAKOFF; MING-WEN LI; JAMES W. OVERSTREET

266

The pH of estuarine waters  

Microsoft Academic Search

The emf measurements for the TRIS buffer in seawater have been used to define buffer solutions that can be used to determine the pH on a free or total proton scale for estuarine waters. The pH is related to the stoichiometric dissociation constant (K*) of TRISH I-, the concentration of buffer (mTRrs) and salinity (5) by pH = pK* +

FRANK J. MILLERO

1986-01-01

267

Interstitial pH, pO2, and pCO2 controlled by optical sensors  

NASA Astrophysics Data System (ADS)

The continuous monitoring of interstitial pH, pO2 and pCO2 contained in the adipose tissue of intensive care patients, is one of the objective of the four year European project CLINICIP (Closed Loop Insulin Infusion in Critically Ill Patients). A glass capillary on line with the microfluidic system, is the solid support onto which the appropriate chemistry is immobilised. The optical working principle applied for the detection of oxygen and carbon dioxide is the modulation of the fluorescence lifetime, whereas absorption modulation is the approach followed for the pH detection. On this basis, two different optoelectronic units were developed for the interrogation of the glass capillary, one for life-time measurements and the other for absorption measurements. Preliminary tests demonstrated a resolution of 0.03 pH units for pH; ? 0.55 mmHg for oxygen and ? 0.6 mmHg for carbon dioxide; and an accuracy of 0.07 pH units for pH; ? 1 mmHg for oxygen and ? 1.5 mmHg for carbon dioxide.

Baldini, Francesco; Bizzarri, Alessandro; Cajlakovic, Merima; Giannetti, Ambra; Konrad, Christian; Mencaglia, Andrea

2005-11-01

268

Phosphocreatine kinetics at the onset of contractions in skeletal muscle of MM creatine kinase knockout mice  

NASA Technical Reports Server (NTRS)

Phosphocreatine (PCr) depletion during isometric twitch stimulation at 5 Hz was measured by (31)P-NMR spectroscopy in gastrocnemius muscles of pentobarbital-anesthetized MM creatine kinase knockout (MMKO) vs. wild-type C57B (WT) mice. PCr depletion after 2 s of stimulation, estimated from the difference between spectra gated to times 200 ms and 140 s after 2-s bursts of contractions, was 2.2 +/- 0.6% of initial PCr in MMKO muscle vs. 9.7 +/- 1.6% in WT muscles (mean +/- SE, n = 7, P < 0.001). Initial PCr/ATP ratio and intracellular pH were not significantly different between groups, and there was no detectable change in intracellular pH or ATP in either group after 2 s. The initial difference in net PCr depletion was maintained during the first minute of continuous 5-Hz stimulation. However, there was no significant difference in the quasi-steady-state PCr level approached after 80 s (MMKO 36.1 +/- 3.5 vs. WT 35.5 +/- 4.4% of initial PCr; n = 5-6). A kinetic model of ATPase, creatine kinase, and adenylate kinase fluxes during stimulation was consistent with the observed PCr depletion in MMKO muscle after 2 s only if ADP-stimulated oxidative phosphorylation was included in the model. Taken together, the results suggest that cytoplasmic ADP more rapidly increases and oxidative phosphorylation is more rapidly activated at the onset of contractions in MMKO compared with WT muscles.

Roman, Brian B.; Meyer, Ronald A.; Wiseman, Robert W.

2002-01-01

269

Anthropogenic carbon and ocean pH  

NASA Astrophysics Data System (ADS)

The burning of fossil fuels and forests increases atmospheric CO2 content, which drives a CO2 flux into the ocean, and thereby makes the ocean more acidic. The effects of increased CO2 and decreased ocean pH may individually and in combination have significant consequences for marine biota We present ocean pH change results from ocean geochemistry and ocean general circulation models for both atmospheric CO2 change scenarios and ocean carbon sequestration scenarios. Unsurprisingly, the pH decrease in the ocean reflects the spatial and temporal distribution of anthropogenic carbon. However, the pH response of the ocean depends sensitively on the rate at which carbon is added to the ocean. When CO2 changes occur over hundreds of thousands of years and longer, ocean carbonate-ion concentration is buffered by interaction with carbonate sediments, buffering ocean pH. However, when CO2 changes occur over decades and centuries, ocean alkalinity remains roughly constant, tending to make ocean pH relatively sensitive to changes in ocean carbon content. A doubling of atmospheric CO2 over a few centuries would decrease ocean pH by ~0.3 units. This is roughly the magnitude of pH variation over the past ~50 million years inferred from boron isotopes. There is no evidence of such rapid pH variation of this magnitude in the geologic record (with possible exceptions for rare catastrophic events). If CO2 is emitted as per the IPCC IS92a ``Business as Usual'' scenario, or even as per most of the proposed CO2 stabilization scenarios, ocean pH may decrease by an amount and at a rate not experienced by the Earth for the past few tens of millions of years. The biological consequences of such pH changes are uncertain at present.

Caldeira, K.; Wickett, M. E.; Duffy, P. B.; Barry, J. P.

2001-12-01

270

Mapping wetlands on beaver flowages with 35-mm photography  

USGS Publications Warehouse

Beaver flowages and associated wetlands on the Chippewa National Forest, north-central Minnesota, were photographed from the ground and from the open side window of a small high-wing monoplane. The 35-mm High Speed Ektachrome transparencies obtained were used to map the cover-type associations visible on the aerial photographs. Nearly vertical aerial photos were rectified by projecting the slides onto a base map consisting ofcontrol points located by plane-table survey. Maps were prepared by tracing the recognizable stands of vegetation in the rectified projection at the desired map scale. Final map scales ranging from 1:260 to 1:571 permitted identification and mapping of 26 cover-type associations on 10 study flowages in 1971. This cover-mapping technique was economical and substituted for detailed ground surveys. Comparative data from 10 flowages were collected serially throughout the entire open-water season. Although developed for analysis of waterfowl habitat, the technique has application to other areas of wildlife management and ecological investigation.

Kirby, R.E.

1976-01-01

271

SSC 50 mm dipole magnet cryostat thermal measurement results  

SciTech Connect

A prototype Superconducting Super Collider (SSC) 50 mm dipole magnet cryostat, DCA323, was instrumented at Fermilab and delivered to the SSC Laboratory for installation into the accelerator systems string test facility. In series with other magnets, the instrumented cryostat will be used to quantify and verify cryostat thermal performance with respect to design requirements. Prior to leaving Fermilab, DCA323 was subjected to magnetic testing at the Magnet Test Facility (MTF). This presented an opportunity to obtain preliminary thermal performance data under simulated operating conditions. It should be noted that measurements of overall cryostat thermal performance were not possible during the MTF measurements as the magnet test stands are designed for magnetic rather than thermal testing. They are not designed to limit heat inleak to the ends of the cryostat, which has been shown to have a significant effect on overall measured thermal performance. Nonetheless, these measurements do offer insight into the performance of several of the cryostat components and sub-systems.

Boroski, W.N.; Nicol, T.H.; Ruschman, M.K.; Schoo, C.J.

1993-05-01

272

Kinetic Inductance Detectors development for mm-wave Astronomy  

NASA Astrophysics Data System (ADS)

Throughout the last decades, development of low-temperat- ure detectors focused mainly on the design of high-sensitivity, single-pixel devices. This includes such devices as semiconductor-based photodetectors and bolometers, Magnetic Metallic Calorimeters (MMC), Superconducting Tunnel Junctions (STJ), and Transition Edge Sensors (TES). However, these devices have had limited success in achieving the simultaneous large-scale array sizes and large-bandwidth operation necessary for high-speed, high-resolution detection. To overcome this performance limitation, it is advisable to focus on low-temperature detectors which are intrinsically adapted to giant-array multiplexing and ultra-fast readout. To adopt large scale frequency-domain multiplexing for low-temperature detectors, it is necessary to find detectors which"broadcast" at microwave frequencies. Superconducting microwave resonators naturally lend themselves to this task. One recent demonstration is an implementation known as Kinetic Inductance Detectors (KIDs). This detection mechanism can be adopted for low-energy EM radiation (radio, mm, THz) in continuous mode, or in pulsed mode for higher energy radiation and particles. We present an ongoing development for a KIDs instrument dedicated to millimetric ground-based observations at the 30m IRAM telescope at Pico Veleta. The Neel IRAM KIDs Array (NIKA) project is coordinated in Grenoble and involves groups in Holland (SRON), UK (Cardiff) and Italy (Roma).

Monfardini, A.; Swenson, L. J.; Benoit, A.; Bideau, A.; Bres, G.; Camus, P.; Garde, G.; Hoffmann, C.; Minet, J.; Rodenas, H.; Nika Collaboration

273

Parallel implementation, validation, and performance of MM5  

SciTech Connect

We describe a parallel implementation of the nonhydrostatic version of the Penn State/NCAR Mesoscale Model, MM5, that includes nesting capabilities. This version of the model can run on many different massively Parallel computers (including a cluster of workstations). The model has been implemented and run on the IBM SP and Intel multiprocessors using a columnwise decomposition that supports irregularly shaped allocations of the problem to processors. This stategy will facilitate dynamic load balancing for improved parallel efficiency and promotes a modular design that simplifies the nesting problem AU data communication for finite differencing, inter-domain exchange of data, and I/O is encapsulated within a parallel library, RSL. Hence, there are no sends or receives in the parallel model itself. The library is Generalizable to other, similar finite difference approximation codes. The code is validated by comparing the rate of growth in error between the sequential and parallel models with the error growth rate when the sequential model input is perturbed to simulate floating point rounding error. Series of runs on increasing numbers of parallel processors demonstrate that the parallel implementation is efficient and scalable to large numbers of processors.

Michalakes, J.; Canfield, T.; Nanjundiah, R.; Hammond, S. [Argonne National Lab., IL (United States); Grell, G. [National Oceanic and Atmospheric Administration, Boulder, CO (United States)

1994-12-31

274

Mapping protein electron transfer pathways with QM/MM methods  

PubMed Central

Mixed quantum mechanics/molecular mechanics (QM/MM) methods offer a valuable computational tool for understanding the electron transfer pathway in protein–substrate interactions and protein–protein complexes. These hybrid methods are capable of solving the Schrödinger equation on a small subset of the protein, the quantum region, describing its electronic structure under the polarization effects of the remainder of the protein. By selectively turning on and off different residues in the quantum region, we are able to obtain the electron pathway for short- and large-range interactions. Here, we summarize recent studies involving the protein–substrate interaction in cytochrome P450 camphor, ascorbate peroxidase and cytochrome c peroxidase, and propose a novel approach for the long-range protein–protein electron transfer. The results on ascorbate peroxidase and cytochrome c peroxidase reveal the importance of the propionate groups in the electron transfer pathway. The long-range protein–protein electron transfer has been studied on the cytochrome c peroxidase–cytochrome c complex. The results indicate the importance of Phe82 and Cys81 on cytochrome c, and of Asn196, Ala194, Ala176 and His175 on cytochrome c peroxidase.

Guallar, Victor; Wallrapp, Frank

2008-01-01

275

COSMOG: Cosmology Oriented Sub-mm Modeling of Galactic Foregrounds  

NASA Technical Reports Server (NTRS)

With upcoming missions in mid- and far-Infrared there is a need for software packages to reliably simulate the planned observations. This would help in both planning the observation and scanning strategy and in developing the concepts of the far-off missions. As this workshop demonstrated, many of the new missions are to be in the far-IR range of the electromagnetic spectrum and at the same time will map the sky with a sub-arcsec angular resolution. We present here a computer package for simulating foreground maps for the planned sub-mm and far-IR missions. such as SPECS. The package allows to study confusion limits and simulate cosmological observations for specified sky location interactively and in real time. Most of the emission at wavelengths long-ward of approximately 50 microns is dominated by Galactic cirrus and Zodiacal dust emission. Stellar emission at these wavelengths is weak and is for now neglected. Cosmological sources (distant and not-so-distant) galaxies for specified cosmologies will be added. Briefly, the steps that the algorithm goes through is described.

Kashlinsky, A.; Leisawitz, D.

2004-01-01

276

pH Wave-Front Propagation in the Urea-Urease Reaction  

PubMed Central

The urease-catalyzed hydrolysis of urea displays feedback that results in a switch from acid (pH ?3) to base (pH ?9) after a controllable period of time (from 10 to >5000 s). Here we show that the spatially distributed reaction can support pH wave fronts propagating with a speed of the order of 0.1?1 mm min?1. The experimental results were reproduced qualitatively in reaction-diffusion simulations including a Michaelis-Menten expression for the urease reaction with a bell-shaped rate-pH dependence. However, this model fails to predict that at lower enzyme concentrations, the unstirred reaction does not always support fronts when the well-stirred reaction still rapidly switches to high pH.

Wrobel, Magdalena M.; Bansagi, Tamas; Scott, Stephen K.; Taylor, Annette F.; Bounds, Chris O.; Carranza, Arturo; Pojman, John A.

2012-01-01

277

Identification and characterization of MmORC4 and MmORC5 , two subunits of the mouse origin of replication recognition complex  

Microsoft Academic Search

.   Two new members of the mouse origin recognition complex (ORC) have been cloned that are closely related to Saccharomyces cerevisiae ORC4 and ORC5 as well as to their human homolog. Both MmORC4p and MmORC5p have a putative nucleotide triphosphate binding motif. Transcription\\u000a of MmORC4 and MmORC5 is not suppressed in mouse NIH3T3 fibroblasts made quiescent by serum starvation. The

Jan Springer; Margot Kneißl; Vera Pütter; Friedrich Grummt

1999-01-01

278

Sodium chloride reduces growth and cytosolic calcium, but does not affect cytosolic pH, in root hairs of Arabidopsis thaliana L  

Microsoft Academic Search

The effects of salinity (NaCl) stress on growth, cytoso- lic Ca2+ gradients and cytosolic pH homeostasis of root hairs of Arabidopsis thaliana are assessed here. Neither cytosolic Ca2+ nor pH at the hair apex were significantly affected by 20 min exposure of up to 90 mM NaCl or of up to 5 mM extracellular Ca2+. Exposure to increasing NaCl concentrations,

Stephen J. Halperin; Simon Gilroy; Jonathan P. Lynch

2003-01-01

279

The Termite Gut Microflora as an Oxygen Sink: Microelectrode Determination of Oxygen and pH Gradients in Guts of Lower and Higher Termites  

Microsoft Academic Search

Clark-type oxygen microelectrodes and glass pH microelectrodes, each with a tip diameter of <10 mm, were used to obtain high-resolution profiles of oxygen concentrations and pH values in isolated termite guts. Radial oxygen profiles showed that oxygen penetrated into the peripheral hindgut contents up to about 150 to 200 mm below the epithelial surface in both the lower termite Reticulitermes

ANDREAS BRUNE; DAVID EMERSON; ANDJOHN A. BREZNAK

1995-01-01

280

Response to the "Responsive PhD"  

ERIC Educational Resources Information Center

In June 2005, 50 graduate school deans gathered at Princeton to address the fact that the number of new PhDs conferred each year far exceeds the number of tenure-track academic jobs on offer. Under the auspices of the Woodrow Wilson National Fellowship Foundation's Responsive PhD Project, these deans spoke passionately about how American…

Huyssen, David

2007-01-01

281

pH. Agricultural Lesson Plans.  

ERIC Educational Resources Information Center

This lesson plan is intended for use in conducting classes on the effect of pH on plant growth. Presented first are an attention step/problem statement and a series of questions and answers designed to convey general information about soil pH and its effect on plants. The following topics are among those discussed: acidity and alkalinity; the…

Southern Illinois Univ., Carbondale. Dept. of Agricultural Education and Mechanization.

282

CALCULATING THE PH OF CALCIUM CARBONATE SATURATION  

EPA Science Inventory

Two new expressions for the pH of saturation (pH subs) were derived. One is a simplified equation developed from an aqueous carbonate equilibrium system in which correction for ionic strength was considered. The other is a more accurate quadratic formula that involves computerize...

283

A 4-mm-square 1.9 GHz Doherty power amplifier module for mobile terminals  

Microsoft Academic Search

A miniaturized Doherty power amplifier (PA) module for mobile terminals has been developed. Two GaAs HBTs and base bias circuits for a carrier amplifier and a peak amplifier are integrated onto a single chip GaAs MMIC (1.0 mm × 1.0 mm × 0.1 mm), which is mounted on a ceramic substrate (4.0 mm × 4.0 mm × 1.5 mm, alumina,

Takayuki Kato; Keiichi Yamaguchi; Yasuhiko Kuriyama

2005-01-01

284

Frequently Asked Questions for Parents of Children with PH  

MedlinePLUS

... International PH News and Projects Let Me Breathe Music Video Families Patients Newly Diagnosed Request an Envelope ... International PH News and Projects Let Me Breathe Music Video Help spread PH awareness and share PH ...

285

Photophysical properties of MM quadruply bonded complexes supported by carboxylate ligands, MM = Mo2, MoW, or W2.  

PubMed

While chemists have extensively studied the photophysical properties of d(6), d(8), and d(10) transition metal complexes, their early transition metal counterparts have received less attention. Quadruply bonded complexes of molybdenum and tungsten supported by carboxylate ligands have intense metal-to-ligand charge transfer (MLCT) absorptions that arise from the electronic coupling of the metal-metal (MM) ? orbital with the CO(2) ?-system. This coupling may in turn be linked to an extended ?-conjugated organic functional group. The major interaction is akin to the so-called back-bonding in metal carbonyl complexes. By the appropriate selection of MM, its attendant ligands, and the organic group, this absorption can be tuned to span the visible and near IR range, from 400 to 1000 nm. Consequently, these complexes offer potential as photon harvesters for photovoltaic devices and photocatalysis. In this Account, we describe recent studies of dinuclear M(II) containing complexes, where M = Mo or W, and show that there are both parallels and disparities to the monomeric transition metal complexes. These early transition metal complexes have relatively long lived excited state singlets when compared to other transition metal complexes. They also often show unusual dual emission (fluorescence and phosphorescence), with singlet (S(1)) lifetimes that range from 1 to 20 ps, and triplet (T(1)) lifetimes from 3 ns to 200 ?s. The fluorescent S(1) states are typically (1)MLCT for both M = Mo and W. These extended singlet lifetimes are uncommon for mononuclear transition metal complexes, which typically have very short lived (1)MLCT states due to rapid femto-second intersystem crossing rates. However, the T(1) states differ. This phosphorescence is MLCT in nature when M = W, while this emission comes from the ??* state for M = Mo. Through time-resolved femtosecond infrared spectroscopy, we can detect the asymmetric stretch of the CO(2) ligand in both the singlet and triplet ??* states. Through these analytical methods, we can study how the charge distribution in the singlet and triplet excited states changes over time. In addition, we can detect delocalized or localized examples of MLCT states, which represent class III and I excited state mixed valence in the Robin and Day scheme. PMID:23145921

Chisholm, Malcolm H; Gustafson, Terry L; Turro, Claudia

2013-02-19

286

Smart pH cuvette for optical monitoring of pH of biological samples  

NASA Astrophysics Data System (ADS)

A Smart pH Cuvette is developed by coating the inner surface with pH sensitive thin film. The coating is a hydroscopic sol-gel material doped with colorimetric pH indicator dye sensitive to the pH of analyte solutions in biological range. Ocean optics miniaturized spectrometers are used for signal detection and analysis, along with multimode optical fibers. This new pH sensing arrangement yields an inexpensive solution for monitoring the pH of samples for biological applications. The Smart pH Cuvettes provide a resolution of 0.01 pH units, an accuracy of 1% of the reading, and 90% response in less than 10 seconds.

Guenther, Derek A.; Shahriari, Mahmoud R.

2010-02-01

287

A QM/MM study of the catalytic mechanism of aspartate ammonia lyase.  

PubMed

Aspartate ammonia lyase (Asp) is one of three types of ammonia lyases specific for aspartate or its derivatives as substrates, which catalyzes the reversible reaction of l-aspartate to yield fumarate and ammonia. In this paper, the catalytic mechanism of Asp has been studied by using combined quantum-mechanical/molecular-mechanical (QM/MM) approach. The calculation results indicate that the overall reaction only contains two elementary steps. The first step is the abstraction of C? proton of l-aspartate by Ser318, which is calculated to be rate limiting. The second step is the cleavage of C?N bond of l-aspartate to form fumarate and ammonia. Ser318 functions as the catalytic base, whereas His188 is a dispensable residue, but its protonation state can influence the active site structure and the existing form of leaving amino group, thereby influences the activity of the enzyme, which can well explain the pH dependence of enzymatic activity. Mutation of His188 to Ala only changes the active site structure and slightly elongates the distance of C? proton of substrate with Ser318, causing the enzyme to remain significant but reduced activity. PMID:24875395

Zhang, Jing; Liu, Yongjun

2014-06-01

288

Effects of pH on the Production of Phosphate and Pyrophosphate by Matrix Vesicles' Biomimetics  

PubMed Central

During endochondral bone formation, chondrocytes and osteoblasts synthesize and mineralize the extracellular matrix through a process that initiates within matrix vesicles (MVs) and ends with bone mineral propagation onto the collagenous scaffold. pH gradients have been identified in the growth plate of long bones, but how pH changes affect the initiation of skeletal mineralization is not known. Tissue-nonspecific alkaline phosphatase (TNAP) degrades extracellular inorganic pyrophosphate (ePPi), a mineralization inhibitor produced by ectonucleotide pyrophosphatase/ phosphodiesterase-1 (NPP1), while contributing Pi from ATP to initiate mineralization. TNAP and NPP1, alone or combined, were reconstituted in dipalmitoylphosphatidylcholine (DPPC) liposomes to mimic the microenvironment of MVs. The hydrolysis of ATP, ADP, AMP and PPi was studied at pH 8 and 9 and compared to the data determined at pH 7.4. While catalytic efficiencies in general were higher at alkaline pH, PPi hydrolysis was maximal at pH 8 and indicated a preferential utilization of PPi over ATP, at pH 8 versus 9. In addition, all proteoliposomes induced mineral formation when incubated in a synthetic cartilage lymph (SCL) containing 1 mM ATP as substrate and amorphous calcium phosphate (ACP) or calciumphosphate- phosphatidylserine complexes (PS-CPLX) as nucleators. Propagation of mineralization was significantly more efficient at pHs 7.5 and 8 than at pH 9. Since a slight pH elevation from 7.4 to 8 promotes considerably more hydrolysis of ATP, ADP and AMP primarily by TNAP, this small pH change facilitates mineralization, especially via upregulated PPi hydrolysis by both NPP1 and TNAP, further elevating the Pi/PPi ratio, thus enhancing bone mineralization.

Simao, Ana Maria S.; Bolean, Mayte; Hoylaerts, Marc F.; Millan, Jose Luis; Ciancaglini, Pietro

2013-01-01

289

Gastric pH and motility in a porcine model of acute lung injury using a wireless motility capsule  

PubMed Central

Summary Background Evaluation of gastric pH and motility in a porcine model of acute lung injury using a novel, wireless motility capsule. Material/Methods A motility capsule was applied into the stomach of 7 Pietrain pigs with acute lung injury induced by high volume saline lavage. Wireless transmission of pH, pressure and temperature data was performed by a recorder attached to the animal’s abdomen. Gastric motility was evaluated using pH and pressure values, and capsule location was confirmed by autopsy. Results Gastric pH values were statistically significantly different (P<0.003) in the animals over time and ranged from 1.15 to 9.94 [5.73±0.47 (mean ±SD)] with an interquartile range of 0.11 to 2.07. The capsule pressure recordings ranged from 2 to 4 mmHg [2.6±0.5 mmHg (mean ±SD)]. There was no change in pressure patterns or sudden rise of pH >3 pH units during 24 hours. All animals had a gastroparesis with the capsules located in the stomach as indicated by the pressure and pH data and confirmed by necropsy. Conclusions The preliminary data show that Pietrain pigs with acute lung injury have a high variability in gastric pH and severely disturbed gastric motility.

Rauch, Stefan; Muellenbach, Ralf M.; Johannes, Amelie; Zollhofer, Bernd; Roewer, Norbert

2011-01-01

290

Dosimetric study of the 15 mm ROPES eye plaque  

SciTech Connect

The main aim of this paper is to make a study of dose-rate distributions obtained around the 15 mm, radiation oncology physics and engineering services, Australia (ROPES) eye plaque loaded with {sup 125}I model 6711 radioactive seeds. In this study, we have carried out a comparison of the dose-rate distributions obtained by the algorithm used by the Plaque Simulator (PS) (BEBIG GmbH, Berlin, Germany) treatment planning system with those obtained by means of the Monte Carlo method for the ROPES eye plaque. A simple method to obtain the dose-rate distributions in a treatment planning system via the superposition of the dose-rate distributions of a seed placed in the eye plaque has been developed. The method uses eye plaque located in a simplified geometry of the head anatomy and distributions obtained by means of the Monte Carlo code GEANT4. The favorable results obtained in the development of this method suggest that it could be implemented on a treatment planning system to improve dose-rate calculations. We have also found that the dose-rate falls sharply along the eye and that outside the eye the dose-rate is very low. Furthermore, the lack of backscatter photons from the air located outside the eye-head phantom produces a dose reduction negligible for distances from the eye-plaque r<1 cm but reaches up to 20% near the air-eye interface. Results showed that the treatment planning system lacks accuracy around the border of the eye (in the sclera and the surrounding area) due to the simplicity of the algorithm used. The BEBIG treatment planning system uses a global attenuation factor that takes into account the effect of the eye plaque seed carrier and the lack of backscatter photons caused by the metallic cover, which in the case of a ROPES eye plaque has a default value of T=1 (no correction). In the present study, a global attenuation factor T=0.96 and an air-interface correction factor which improve on treatment planning system calculations were obtained.

Granero, D.; Perez-Calatayud, J.; Ballester, F.; Casal, E.; Frutos, J.M. de [Department of Atomic, Molecular and Nuclear Physics and IFIC, University of Valencia-CSIC, Dr. Moliner 50, E46100 Burjassot (Spain); Medical Physics Section, University Hospital, Av. Ramon y Cajal 3, E47011 Valladolid (Spain)

2004-12-01

291

Calcification, growth and mortality of juvenile clams Ruditapes decussatus under increased pCO 2 and reduced pH: Variable responses to ocean acidification at local scales?  

Microsoft Academic Search

We investigated the effects of ocean acidification on juvenile clams Ruditapes decussatus (average shell length 10.24mm) in a controlled CO2 perturbation experiment. The carbonate chemistry of seawater was manipulated by diffusing pure CO2, to attain two reduced pH levels (by ?0.4 and ?0.7 pH units), which were compared to unmanipulated seawater. After 75days we found no differences among pH treatments

P. Range; M. A. Chícharo; R. Ben-Hamadou; D. Piló; D. Matias; S. Joaquim; A. P. Oliveira; L. Chícharo

2011-01-01

292

Effect of postweld heat treatment on weld metal impact toughness of a semi-austenitic PH stainless steel  

Microsoft Academic Search

Semi-austenitic precipitation hardened PH stainless steel plates, PH 15-7 Mo (Cu), 6.14 mm thick were autogenously welded using the electron beam welding (EBW) and plasma arc welding (PAW) processes. Impact toughness studies using Charpy V-notch samples (V-notch at the center of the weld metal) showed that EB welds had higher impact toughness than PA welds in various identical postweld heat

N. Sivaramakrishnan; K. S. Raja; K. Prasad Rao

1994-01-01

293

EFFECT OF PH ON HUMAN MYCOPLASMA STRAINS.  

PubMed

Shepard, Maurice C. (U.S. Naval Medical Field Research Laboratory, Camp Lejeune, N.C.), and Carl D. Lunceford. Effect of pH on human Mycoplasma strains. J. Bacteriol. 89:265-270. 1965.-The optimal reaction of culture media for the cultivation of T-strain Mycoplasma of human origin was investigated. By use of a recently modified tryptic digest medium, the optimal reaction in either agar or fluid medium was found to be pH 6.0. In contrast, human classic (large-colony) Mycoplasma could be cultivated in agar or fluid medium over a rather broad pH range, and the influence of the reaction of the medium appeared to be primarily species-dependent. M. salivarium, for example, grew best in agar from pH 5.5 through 6.5. M. pneumoniae (Easton's agent) yielded largest colony numbers in agar and highest titers in broth at pH 8.0. In the case of T-strain Mycoplasma, both maximal colony numbers in agar and highest titers in fluid media were achieved at a reaction of pH 6.0. In addition, largest colony size of T-strain Mycoplasma was also achieved in agar at pH 6.0, and averaged 50 to 100% larger than that obtained by cultivation at pH 8.0 with the same medium. Although T-strains will develop in agar media over a pH range of from 5.0 through 10.0, the extremely small colony size and poor staining properties resulting from growth in an alkaline medium make their recognition in agar cultures difficult. Aerobic cultivation of T-strains was first achieved in agar adjusted to pH 5.5 to 6.0. In fluid medium, multiplication of T-strains occurred only within the limits of pH 5.0 through 8.0, with highest titers being reached at pH 6.0. Greater attention to the reaction of complete Mycoplasma media is stressed. PMID:14255688

SHEPARD, M C; LUNCEFORD, C D

1965-02-01

294

Substrate Selectivity and pH Dependence of KAAT1 Expressed in Xenopus laevis Oocytes  

Microsoft Academic Search

.   When expressed in Xenopus oocytes KAAT1 increases tenfold the transport of l-leucine. Substitution of NaCl with 100 mm LiCl, RbCl or KCl allows a reduced but significant activation of l-leucine uptakes. Chloride-dependence is not strict since other pseudohalide anions such as thyocyanate are accepted. KAAT1\\u000a is highly sensitive to pH. It can transport l-leucine at pH 5.5 and 8,

S. Vincenti; M. Castagna; A. Peres; V. F. Sacchi

2000-01-01

295

Herschel Multi-Tiered Extragalactic Survey: SPIRE-mm Photometric Redshifts.  

National Technical Information Service (NTIS)

We investigate the potential of submm-mm and submm-mm-radio photometric redshifts using a sample of mm-selected sources as seen at 250, 350 and 500 micron by the SPIRE instrument on Herschel. From a sample of 63 previously identified mm sources with relia...

A. Amblard A. Blain A. Boselli A. Cava A. Conley C. D. Dowell D. Brisbin D. Burgarella D. L. Clements E. Chapin E. Dwek H. Aussel I. G. Roseboom J. Block J. S. Dunlop L. Conversi M. Bethermin N. Castro-Rodriquez P. Chanial R. Auld R. J. Ivison S. Chapman T. R. Greve V. Arumugam V. Buat

2012-01-01

296

Herschel Multi-Tiered Extragalactic Survey: SPIRE-mm Photometric Redshifts.  

National Technical Information Service (NTIS)

We investigate the potential of submm-mm and submm-mm-radio photometric red-shifts using a sample of mm-selected sources as seen at 250, 350 and 500 micrometers by the SPIRE instrument on Herschel. From a sample of 63 previously identified mm-sources with...

A. Amblard A. Blain A. Boselli A. Cava A. Conley A. Cooray C. D. Dowell D. Brisbin D. Burgarella D. L. Clements E. Chapin E. Dwek H. Aussel I. G. Roseboom J. Bock L. Conversi M. Bethermin N. Castro-Rodriguez P. Chanial R. Auld R. J. Ivison S. Chapman T. R. Greve V. Arumugam V. Buat

2011-01-01

297

Colorimetric Determination of pH.  

ERIC Educational Resources Information Center

Presented is an activity in which the pH of a solution can be quantitatively measured using a spectrophotometer. The theory, experimental details, sample preparation and selection, instrumentation, and results are discussed. (CW)

Tucker, Sheryl; And Others

1989-01-01

298

Mary Fennell, PhD Chair  

Cancer.gov

NCI Community Cancer Centers Program Evaluation Oversight Committee Roster CHAIR Mary Fennell, Ph.D. Chair, Department of Sociology and Community Health Brown University Box 1916, 211 Maxcy Hall 112 George Street Providence, RI 02912

299

Paul Pinsky, PhD, MPH  

Cancer.gov

Division of Cancer Prevention Staff Paul Pinsky, PhD, MPH Acting ChiefEarly Detection Research Group Location Division of Cancer PreventionNational Cancer Institute9609 Medical Center Drive, Room 5E444 Rockville, MD 20850 Phone

300

Aqueous-Solution pH Scales  

Microsoft Academic Search

The parallel existence of two forms of pH scale is considered, which is unique for the international metrological community. The basic advantages and shortcomings are considered for the multireference NIST scale and the single-reference BSI one.

O. V. Karpov; I. I. Maksimov; A. L. Seifer

2000-01-01

301

Assessing the performance of MM/PBSA and MM/GBSA methods. 3. The impact of force fields and ligand charge models.  

PubMed

Here, we systematically investigated how the force fields and the partial charge models for ligands affect the ranking performance of the binding free energies predicted by the Molecular Mechanics/Poisson-Boltzmann Surface Area (MM/PBSA) and Molecular Mechanics/Generalized Born Surface Area (MM/GBSA) approaches. A total of 46 small molecules targeted to five different protein receptors were employed to test the following issues: (1) the impact of five AMBER force fields (ff99, ff99SB, ff99SB-ILDN, ff03, and ff12SB) on the performance of MM/GBSA, (2) the influence of the time scale of molecular dynamics (MD) simulations on the performance of MM/GBSA with different force fields, (3) the impact of five AMBER force fields on the performance of MM/PBSA, and (4) the impact of four different charge models (RESP, ESP, AM1-BCC, and Gasteiger) for small molecules on the performance of MM/PBSA or MM/GBSA. Based on our simulation results, the following important conclusions can be obtained: (1) for short time-scale MD simulations (1 ns or less), the ff03 force field gives the best predictions by both MM/GBSA and MM/PBSA; (2) for middle time-scale MD simulations (2-4 ns), MM/GBSA based on the ff99 force field yields the best predictions, while MM/PBSA based on the ff99SB force field does the best; however, longer MD simulations, for example, 5 ns or more, may not be quite necessary; (3) for most cases, MM/PBSA with the Tan's parameters shows better ranking capability than MM/GBSA (GB(OBC1)); (4) the RESP charges show the best performance for both MM/PBSA and MM/GBSA, and the AM1-BCC and ESP charges can also give fairly satisfactory predictions. Our results provide useful guidance for the practical applications of the MM/GBSA and MM/PBSA approaches. PMID:23789789

Xu, Lei; Sun, Huiyong; Li, Youyong; Wang, Junmei; Hou, Tingjun

2013-07-18

302

In Vivo Model to Test Implanted Biosensors for Blood pH  

NASA Technical Reports Server (NTRS)

Biosensors for monitoring physiologic data continuously through telemetry are available for heart rate, respiration, and temperature but not for blood pH or ions affected by hydrogen ion concentration. A telemetric biosensor for monitoring blood pH on-line could be used to identify and manage problems in fluid and electrolyte metabolism, cardiac and respiratory function during space flight and the acid-base status of patients without the need for venipuncture in patients on Earth. Critical to the development of biosensors is a method for evaluating their performance after implantation. Mature rats, prepared with jugular, cannulas for repeated blood samples, were exposed to a gas mixture containing high levels of carbon dioxide (7%) in a closed environment to induce mild respiratory acidosis. Serial blood gas and pH measurements in venous blood were compared with electrical responses from sensors implanted in the subcutaneous tissue. Animals became slightly tachypneic after exposure to excess CO2, but remained alert and active. After 5 minutes, basal blood pH decreased from 7.404 +/- 0.013 to 7.289 +/- 0.010 (p less than 0.001)and PC02 increased from 45 +/- 6 to 65 +/- 4 mm. Hg (p les than 0.001). Thereafter pH and blood gas parameters remained stable. Implanted sensors showed a decrease in millivolts (mV) which paralleled the change in pH and averaged 5-6 mV per 0.1 unit pH. Implanted sensors remained sensitive to modest changes in tissue pH for one week. A system for inducing acidosis in rats was developed to test the in vivo performance of pH biosensors. The system provides a method which is sensitive, rapid and reproducible in the same and different animals with full recovery, for testing the performance of sensors implanted in subcutaneous tissues.

Arnaud, Sara B.; Somps, Chris J.; Madou, Marc; Hines, John; Wade, Charles E. (Technical Monitor)

1997-01-01

303

Simultaneous water desalination and electricity generation in a microbial desalination cell with electrolyte recirculation for pH control.  

PubMed

A recirculation microbial desalination cell (rMDC) was designed and operated to allow recirculation of solutions between the anode and cathode chambers. This recirculation avoided pH imbalances that could inhibit bacterial metabolism. The maximum power density was 931±29mW/m(2) with a 50mM phosphate buffer solution (PBS) and 776±30mW/m(2) with 25mM PBS. These power densities were higher than those obtained without recirculation of 698±10mW/m(2) (50mM PBS) and 508±11mW/m(2) (25mM PBS). The salt solution (20g/L NaCl) was reduced in salinity by 34±1% (50mM) and 37±2% (25mM) with recirculation (rMDC), and by 39±1% (50mM) and 25±3% (25mM) without recirculation (MDC). These results show that electrolyte recirculation using an rMDC is an effective method to increase power and achieve efficient desalination by eliminating pH imbalances. PMID:22200556

Qu, Youpeng; Feng, Yujie; Wang, Xin; Liu, Jia; Lv, Jiangwei; He, Weihua; Logan, Bruce E

2012-02-01

304

Article Comparison of the Effects of Aortic Valve Replacement Using 19-mm Carpentier-Edwards Perimount Bioprosthesis and 19-mm Medtronic Mosaic Bioprosthesis  

Microsoft Academic Search

Objective: Short (?3 months)- and middle (?4 months)-term results of aortic valve replacement (AVR) using 19-mm Carpentier-Edwards Perimount (CEP) bioprosthetic valves and 19-mm Medtronic Mosaic (MM) bioprosthetic valves in patients with small aortic annulus were com- pared. Patients and Methods: At our facility, AVR was performed using bioprostheses in 110 patients from April 1999 to March 2006. Of these patients,

Kazuyoshi Tanigawa; Kiyoyuki Eishi; Shiro Yamachika; Koji Hashizume; Seiichi Tada; Kentaro Yamane; Kenta Izumi; Hideaki Takai; Takashi Miura; Shun Nakaji

305

Measurements of Missing Mass (MM) Spectra from pi-p ==> (MM)-p at 8, 11, 13.5, and 16 GeV  

Microsoft Academic Search

Measurements of missing mass (MM) spectra from pi-p ==> (MM)-p at 8, 11, 13.5, and 16 GeV are reported. The MM mass range examined is 0 <= M2 <= 7.3 GeV2 with t (the proton four momentum transfer squared) in the interval 0.2 <= |t| <= 0.3 GeV2. Narrow resonances (R1, R2, R3, S, T, and U) with cross sections

D. Bowen; D. Earles; W. Faissler; D. Garelick; M. Gettner; M. J. Glaubman; B. Gottschalk; G. Lutz; J. Moromisato; E. I. Shibata; Y. W. Tang; E. Von Goeler; R. Weinstein; H. R. Blieden; G. Finocchiaro; J. Kirz; R. Thun

1972-01-01

306

Measurements of Missing Mass (MM) Spectra from ??p ? (MM)?p at 8, 11, 13.5, and 16 GeV  

Microsoft Academic Search

Measurements of missing mass (MM) spectra from ??p ? (MM)?p at 8, 11, 13.5, and 16 GeV are reported. The MM mass range examined is 0 ? M2 ? 7.3 GeV2 with t (the proton four momentum transfer squared) in the interval 0.2 ? ∣t∣ ? 0.3 GeV2. Narrow resonances (R1, R2, R3, S, T, and U) with cross sections

D. Bowen; D. Earles; W. Faissler; D. Garelick; M. Gettner; M. J. Glaubman; B. Gottschalk; G. Lutz; J. Moromisato; E. I. Shibata; Y. W. Tang; E. von Goeler; R. Weinstein; H. R. Blieden; G. Finocchiaro; J. Kirz; R. Thun

1972-01-01

307

Rainwater ph in the vicinity of hadera power plant, Israel during the winter season of 1981/82  

NASA Astrophysics Data System (ADS)

A new method for the continuous pH measurement of rainwater is discussed. Tkis method, applied at a site near a new coal-fired power plant (before its operation), showed a pH variation of 4.3 to 9.2 as compared to 6.5 ± 1.0 observed using conventional methods which measure pH at the end of each rain episode. The alkalinity of top soil in the vicinity, and hence natural aerosols act as a buffer, reducing the acidity of the rain. This buffering effect disappears after 30-40 mm of rainfall.

Kolton-Shapira, Rivka; Lakritz, Yerucham; Luria, Menachem

308

CMP process comparison for 150mm larger area InSb (111)B focal plane array substrates  

NASA Astrophysics Data System (ADS)

As size requirements and pixel viabilities for mid-wavelength infrared (MWIR) focal plane arrays (FPAs) continue to increase, larger InSb substrate diameters are of significant interest. To improve resolution and sensitivity requirements for high performance infrared focal plane array (IRFPA) imaging systems in the 1-5.4 ?m region (77°K), the surface of new larger diameter (150mm) InSb substrates must meet or surpass stringent demands. The scale-up to 150mm InSb has necessitated changes in processing and finishing parameters, as device layer growth by epitaxy or other means often requires a surface roughness average (Ra)~0.1 nm. This study compares two different CMP finishes for new 150mm diameter InSb wafers and examines their suitability for IRFPA applications. InSb surface quality was examined by molecular beam epitaxy (MBE), reflective high energy electron diffraction (RHEED), atomic force microscopy (AFM), thermal X-ray spectroscopy (TXPS), and multiple crystal x-ray diffraction (XRD) for two distinct CMP finishes on InSb(111)B substrates from the same crystal boule. This study has shown that differences result in thermal desorption properties with the CMP process, consistent with differences in surface smoothness and oxide composition. Better surface composition and crystallinity were produced with a modified CMP process for the 150mm diameter crystals. We conclude that the differential ratio between the pH, the oxidizer percentage, and the buffering percentage of the modified CMP process is a benefit to larger diameter InSb IRFPA applications.

Flint, P.; Allen, L. P.; Dallas, G.; Ruchert, B. D.; Bakken, D.; Blanchat, K.; Vangala, S. R.; Goodhue, W. D.; Bliss, D.; Dauplais, H.

2009-09-01

309

Tomato responses to ammonium and nitrate nutrition under controlled root-zone pH  

NASA Technical Reports Server (NTRS)

Tomato (Lycopersicon esculentum L. Mill. 'Vendor') plants were grown for 21 days in flowing solution culture with N supplied as either 1.0 mM NO3- or 1.0 mM NH4+. Acidity in the solutions was automatically maintained at pH 6.0. Accumulation and distribution of dry matter and total N and net photosynthetic rate were not affected by source of N. Thus, when rhizosphere acidity was controlled at pH 6.0 during uptake, either NO3- or NH4+ can be used efficiently by tomato. Uptake of K+ and Ca2+ were not altered by N source, but uptake of Mg2+ was reduced in NH4(+)-fed plants. This indicates that uptake of Mg2+ was regulated at least partially by ionic balance within the plant.

Peet, M. M.; Raper, C. D. Jr; Tolley, L. C.; Robarge, W. P.; Raper CD, J. r. (Principal Investigator)

1985-01-01

310

A simple model for assessing ammonia emission from ammoniacal fertilisers as affected by pH and injection into soil  

NASA Astrophysics Data System (ADS)

Ammonia (NH 3) volatilisation following the application of ammoniacal fertilisers and liquid manure to agricultural land is a significant source of atmospheric NH 3, which not only poses a risk to the environment, but may also result in a loss of plant available nitrogen (N). This study examined the potential for reducing NH 3 emission through acidifying an ammoniacal solution and by injecting the solution. The combination of the two technologies was studied and a model for predicting the most optimal treatment was developed. In the laboratory, ammonium (NH 4+) hydroxide (aqueous NH 3) was dissolved in water (pH 11) and injected into a loamy sand soil. The NH 3 emission was measured with a dynamic chamber technology. Injecting the solution to 10 mm below the soil surface reduced NH 3 emission by 10% compared to surface application, and injection to 30 mm reduced emission by 20% compared to surface application. Acidifying the ammoniacal solution by adding sulphuric acid and reducing pH to 10 reduced the emission by 60% at a 10 mm injection depth and 90% at 30 mm compared with non-acidified and surface-spread ammoniacal solution. The results show that there is an important interaction of pH and injection depth and that there is a need for models predicting a combined effect. This type of model could contribute to reduce cost and energy (traction force) by providing the optimal combination of acidifying and injection depth that gives a specific reduction in NH 3 emission, which in this study was reducing pH to 10 and inject the fertiliser to 30 mm below surface. This study showed that relatively simple models can predict the NH 3 emission from injected ammoniacal fertilisers, but that there is still a need for developing algorithms that predict the effect of pH, including the pH buffering capacity of the fertiliser and the soil.

Nyord, T.; Schelde, K. M.; Søgaard, H. T.; Jensen, L. S.; Sommer, S. G.

311

Ovalbumin-gum arabic interactions: effect of pH, temperature, salt, biopolymers ratio and total concentration.  

PubMed

The formation of soluble and insoluble complexes between ovalbumin (OVA) and gum arabic (GA) polysaccharide was investigated under specific conditions (pH 1.0-7.0; temperature 4-55 °C; NaCl concentration 0-60mM; total biopolymer concentration 0.05-3.0 wt%) by turbidimetric analysis. For the 2:1 OVA:GA ratio and in the absence of NaCl, soluble and insoluble complexes were observed at pH 4.61 (pH?1) and 4.18 (pH?2), respectively, with optimal biopolymer interactions occurring at pH 3.79 (pHopt). Under the same conditions, OVA alone gave only a weak turbidity intensity (turbidity <0.03), whereas GA had none. As the temperature increased, critical pH values shifted toward lower pH, and the maximum turbidity value occurred at 25 °C. The region between pH?1 and pH?2 was narrowed and the electrostatic interactions became weaker with increasing NaCl concentration. The maximum turbidity value increased as the total biopolymer concentration increased until reaching a critical value (2.0%), afterwards becoming a constant value. PMID:24149009

Niu, Fuge; Su, Yujie; Liu, Yuntao; Wang, Guanchao; Zhang, Yang; Yang, Yanjun

2014-01-01

312

?-Galactoside-binding activity of human galectin-1 at basic pH  

NASA Astrophysics Data System (ADS)

?-Galactoside-binding activity of human galectin-1 (hGal-1) was evaluated at pH 7-9.5 by fluorescence spectroscopy from the fraction bound to lactose gel (Y) and the lactose binding constant (Kb). Y decreases at pH > 8.2 ± 0.1 in the absence of NaCl, while it is constant in the presence of 150 mM NaCl. On the other hand, Kb is independent of pH and the NaCl concentration at basic pH. Analysis of Raman spectrum has shown that the pKa of Cys residues of hGal-1 is 8.5 ± 0.1 on average, indicating that about 40% of the six Cys residues of hGal-1 would be deprotonated at pH 8.2. The pH dependence of Y is explained by an increase of Coulombic repulsion among negatively charged hGal-1 on the lactose gel surface. This result suggests that Y is not always a good indicator of the ?-galactoside-binding activity of galectins, which contain many Cys residues.

Hiramatsu, Hirotsugu; Takeuchi, Katsuyuki; Fukuda, Koki; Nishino, Tomohide

2013-06-01

313

Effects of pH and elevated glucose levels on the electrochemical behavior of dental implants.  

PubMed

Implant failure is more likely to occur in persons with medically compromising systemic conditions, such as diabetes related to high blood glucose levels and inflammatory diseases related to pH levels lower than those in healthy people. The aim of this study was to investigate the effects of lower pH level and simulated- hyperglycemia on implant corrosion as these effects are critical to biocompatibility and osseointegration. The electrochemical corrosion properties of titanium implants were studied in four different solutions: Ringer's physiological solution at pH = 7.0 and pH = 5.5 and Ringer's physiological solution containing 15 mM dextrose at pH = 7 and pH = 5.5. Corrosion behaviors of dental implants were determined by cyclic polarization test and electrochemical impedance spectroscopy. Surface alterations were studied using a scanning electron microscope. All test electrolytes led to apparent differences in corrosion behavior of the implants. The implants under conditions of test exhibited statistically significant increases in I(corr) from 0.2372 to 1.007 ?Acm(-2), corrosion rates from 1.904 to 8.085 mpy, and a decrease in polarization resistances from 304 to 74 ?. Implants in dextrose-containing solutions were more prone to corrosion than those in Ringer's solutions alone. Increasing the acidity also yielded greater corrosion rates for the dextrose-containing solutions and the solutions without dextrose. PMID:24779948

Tamam, Evsen; Turkyilmaz, Ilser

2014-04-01

314

Development of luminescent pH sensor films for monitoring bacterial growth through tissue.  

PubMed

Although implanted medical devices (IMDs) offer many benefits, they are susceptible to bacterial colonization and infections. Such infections are difficult to treat because bacteria could form biofilms on the implant surface, which reduce antibiotics penetration and generate local dormant regions with low pH and low oxygen. In addition, these infections are hard to detect early because biofilms are often localized on the surface. Herein, an optical sensor film is developed to detect local acidosis on an implanted surface. The film contains both upconverting particles (UCPs) that serve as a light source and a pH indicator that alters the luminescence spectrum. When irradiated with 980 nm light, the UCPs produce deeply penetrating red light emission, while generating negligible autofluorescence in the tissue. The basic form of the pH indicator absorbs more of upconversion luminescence at 661 nm than at 671 nm and consequently the spectral ratio indicates pH. Implanting this pH sensor film beneath 6-7 mm of porcine tissue does not substantially affect the calibration curve because the peaks are closely spaced. Furthermore, growth of Staphylococcus epidermidis on the sensor surface causes a local pH decrease that can be detected non-invasively through the tissue. PMID:23832869

Wang, Fenglin; Raval, Yash; Chen, Hongyu; Tzeng, Tzuen-Rong J; DesJardins, John D; Anker, Jeffrey N

2014-02-01

315

Mechanism of intracellular pH increase during parthenogenetic activation of In vitro matured porcine oocytes.  

PubMed

Parthenogenetic activation of porcine oocytes by using 7% ethanol, 50 or 100 microM A23187 results in an increase in intracellular pH as does prolonged exposure to thimerosal. We attempt to specify which transporters or mechanisms are involved in the observed increase in intracellular pH during oocyte activation. Experiments were performed in the absence of sodium; the presence of 2.5 mM amiloride, a potent inhibitor of the Na(+)/H(+) antiport; in the absence of bicarbonate; and in the presence of 4, 4'-diisothiocyanatodihydrostilbene-2,2'-di-sulfonic acid, disodium salt (H(2)DIDS) for all three activation methods. These treatments had no effect on the increase in intracellular pH induced by the calcium ionophore or thimerosal, but all reduced the increase in pH (P < 0.001) in the 7% ethanol group. This suggests that the Na(+)/H(+) antiport and the HCO(3)(-)/Cl(-) exchangers are not playing a role during treatment with calcium ionophore or thimerosal, and the pH increase observed during treatment with 7% ethanol may be dependent upon a sodium or bicarbonate flux (or both) into the oocyte. Bafilomycin A1 (500 nm), an inhibitor of vacuolar-type H(+) ATPases, had no effect on 7% ethanol or thimerosal treatments, but significantly reduced the increase in intracellular pH observed during calcium ionophore treatment. This may be the result of an initial local increase in intracellular free calcium levels. PMID:10906054

Ruddock, N T; Macháty, Z; Milanick, M; Prather, R S

2000-08-01

316

MRF with adjustable pH  

NASA Astrophysics Data System (ADS)

Deterministic final polishing of high precision optics using sub-aperture processing with magnetorheological finishing (MRF) is an accepted practice throughout the world. A wide variety of materials can be successfully worked with aqueous (pH 10), magnetorheological (MR) fluids, using magnetic carbonyl iron (CI) and either ceria or nanodiamond nonmagnetic abrasives. Polycrystalline materials like zinc sulfide (ZnS) and zinc selenide (ZnSe) are difficult to polish at pH 10 with MRF, due to their grain size and the relatively low stiffness of the MR fluid lap. If microns of material are removed, the grain structure of the material begins to appear. In 2005, Kozhinova et al. (Appl. Opt. 44 4671-4677) demonstrated that lowering pH could improve MRF of ZnS. However, magnetic CI particle corrosion rendered their low pH approach unstable and unsuitable for commercial implementation. In 2009, Shafrir et al. described a sol-gel coating process for manufacturing a zirconia-coated CI particle that protects the magnetic core from aqueous corrosion (Appl. Opt .48 6797-6810). The coating process produces free nanozirconia polishing abrasives during the coating procedure, thereby creating an MR polishing powder that is "self-charged" with the polishing abrasive. By simply adding water, it was possible to polish optical glasses and ceramics with good stability at pH 8 for three weeks. The development of a corrosion resistant, MR polishing powder, opens up the possibility for polishing additional materials, wherein the pH may be adjusted to optimize effectiveness. In this paper we describe the CI coating process, the characterization of the coated powder, and procedures for making stable MR fluids with adjustable pH, giving polishing results for a variety of optical glasses and crystalline ceramics.

Jacobs, Stephen D.

2011-09-01

317

Cyclic variations in nitrogen uptake rate of soybean plants: effects of pH and mixed nitrogen sources  

NASA Technical Reports Server (NTRS)

To determine if the daily pattern of NO3- and NH4+ uptake is affected by acidity or NO3- : NH4+ ratio of the nutrient solution, non-nodulated soybean plants (Glycine max) were exposed for 21 days to replenished, complete nutrient solutions at pH 6.0, 5.5, 5.0, and 4.5 which contained either 1.0 mM NH4+, 1.0 mM NO3- [correction of NO3+], 0.67 mM NH4+ plus 0.33 mM NO3- (2:1 NH4+ : NO3-) [correction of (2:1 NH3+ : NO4-)], or 0.33 mM NH4+ plus 0.67 mM NO3- (1:2 NH4+ : NO3-). Net uptake rates of NH4+ and NO3- were measured daily by ion chromatography as depletion from the replenished solutions. When NH4+ and NO3- were supplied together, cumulative uptake of total nitrogen was not affected by pH or solution NH4+ : NO3- ratio. The cumulative proportion of nitrogen absorbed as NH4+ decreased with increasing acidity; however, the proportional uptake of NH4+ and NO3- was not constant, but varied day-to-day. This day-to-day variation in relative proportions of NH4+ and NO3- absorbed when NH4+ : NO3- ratio and pH of solution were constant indicates that the regulatory mechanism is not directly competitive. Regardless of the effect of pH on cumulative uptake of NH4+, the specific nitrogen uptake rates from mixed and from individual NH4+ and NO3- sources oscillated between maxima and minima at each pH with average periodicities similar to the expected interval of leaf emergence.

Raper, C. D. Jr; Vessey, J. K.; Henry, L. T.; Chaillou, S.

1991-01-01

318

Catalytic Mechanism of RNA Backbone Cleavage by Ribonuclease H from QM/MM Simulations  

PubMed Central

We use quantum mechanics/molecular mechanics (QM/MM) simulations to study the cleavage of the ribonucleic acid (RNA) backbone catalyzed by ribonuclease H. This protein is a prototypical member of a large family of enzymes that use two-metal catalysis to process nucleic acids. By combining Hamiltonian replica exchange with a finite-temperature string method, we calculate the free energy surface underlying the RNA cleavage reaction and characterize its mechanism. We find that the reaction proceeds in two steps. In a first step, catalyzed primarily by magnesium ion A and its ligands, a water molecule attacks the scissile phosphate. Consistent with thiol-substitution experiments, a water proton is transferred to the downstream phosphate group. The transient phosphorane formed as a result of this nucleophilic attack decays by breaking the bond between the phosphate and the ribose oxygen. In the resulting intermediate, the dissociated but unprotonated leaving group forms an alkoxide coordinated to magnesium ion B. In a second step, the reaction is completed by protonation of the leaving group, with a neutral Asp132 as a likely proton donor. The overall reaction barrier of ~15 kcal mol?1, encountered in the first step, together with the cost of protonating Asp132, is consistent with the slow measured rate of ~1–100/min. The two-step mechanism is also consistent with the bell-shaped pH dependence of the reaction rate. The non-monotonic relative motion of the magnesium ions along the reaction pathway agrees with X-ray crystal structures. Proton transfer reactions and changes in the metal ion coordination emerge as central factors in the RNA cleavage reaction.

Rosta, Edina; Nowotny, Marcin; Yang, Wei; Hummer, Gerhard

2011-01-01

319

POTENSI KURKUMIN SEBAGAI PENUNJUK pH SEMULAJADI UNTUK PEMBANGUNAN SENSOR OPTIK pH  

Microsoft Academic Search

The potential of curcumin reagent as a natural pH indicator for the development of an optical pH sensor was discussed in this study. Curcumin has been chosen because it has never been reported before for use in the development of an optical pH sensor. Curcumin is a colouring constituent of tumeric that giving yellow pigmentation. Curcumin showed clear colour changes

Rosmawani Mohammad; Musa Ahmad; Jamaluddin Mohd Daud

2007-01-01

320

Novel optical pH sensor for high and low pH values  

Microsoft Academic Search

The development of an optical pH sensor based on immobilization of mixture of two dyes on a triacetylcellulose membrane is described. The sensor has a useful pH range at low and high pH values, where glass electrodes show acidic and alkaline errors, respectively. Application of a back-propagation artificial neural network (ANN) model extends the measuring range of the proposed optode

Afsaneh Safavi; Mozhgan Bagheri

2003-01-01

321

Ruminal pH regulation and nutritional consequences of low pH  

Microsoft Academic Search

Volatile fatty acids (VFA) and lactic acid can build up in the rumen and reduce ruminal pH. Low ruminal pH for prolonged periods each day can affect feed intake, microbial metabolism and feed digestion, and has also been related to inflammation, diarrhea and milk fat depression. This paper considers aspects of pH regulation, as well as the effects of ruminal

J. Dijkstra; J. L. Ellis; E. Kebreab; A. B. Strathe; S. Lopez; A. Bannink

2012-01-01

322

Quercetin sensitizes cells in a tumour-like low pH environment to hyperthermia.  

PubMed

Quercetin has been shown to act as a hyperthermia sensitizer by inhibiting the synthesis of heat shock protein 70 (HSP70) in a variety of tumour cell lines. It is most effective under conditions of low pH. This study was designed to test the hypothesis that quercetin suppresses thermotolerance development in cells adapted to growth at low pH and renders them as responsive as acutely acidified cells to hyperthermia-induced cytotoxicity. Chinese hamster ovarian carcinoma cells (OvCa) were exposed to 42 degrees C hyperthermia and/or quercetin (50-200 mm) at their growth pH of either 7.3 or 6.7 or after acute acidification from 7.3 to 6.7. Thermotolerance development was measured by colony survival. HSP70 synthesis and total protein synthesis were measured by radioactive precursor pulse labelling techniques. Quercetin, in a concentration-dependent manner, reduced the rate of total protein synthesis and increased cytotoxicity equally after acute acidification to pH 6.7 or growth at pH 6.7 at 37 degrees C, and to a greater extent than it did in cells at pH 7.3. At 42 degrees C, 100 mm quercetin inhibited total protein synthesis, HSP70 synthesis and thermotolerance development to a similar extent in cells grown at pH 6.7 or acutely acidified to pH 6.7. In contrast, quercetin reduced but did not completely inhibit HSP70 synthesis and thermotolerance development in cells grown and heated at pH 7.3. These results support the hypothesis that quercetin can specifically reduce thermotolerance development in tumour cells adapted to growth at pHe 6.7 so that they respond similarly to acutely acidified cells. Since many tumours are adapted to growth at low pH and may resist a wide variety of therapeutic modalities, inhibition of thermotolerance expression by quercetin may not only enhance the response to hyperthermia but the response to commonly used therapies such as chemotherapy and radiation. PMID:12944166

Wachsberger, P R; Burd, R; Bhala, A; Bobyock, S B; Wahl, M L; Owen, C S; Rifat, S B; Leeper, D B

2003-01-01

323

Mechanisms of Reoxygenation-Induced Calcium Overload in Cardiac Myocytes: Dependence on pH i  

Microsoft Academic Search

This study investigated the selective effects of intracellular (pHi) or extracellular change in pH on reoxygenation-induced Ca2+ overload in simulated myocardial hypoxia. Experiments were performed in cultured cardiomyocytes isolated from the ventricle of neonatal ICR mouse. A model of chemical hypoxia with 2 mM sodium cyanide was developed to mimic the ATP depletion of hypoxia. This chemical hypoxia was \\

Naruto Matsuda; Tohru Mori; Hiroshi Nakamura; Munekazu Shigekawa

1995-01-01

324

Soil pH governs production rate of calcium carbonate secreted by the earthworm Lumbricus terrestris  

Microsoft Academic Search

Lumbricus terrestris earthworms exposed to 11 soils of contrasting properties produced, on average, 0.8±0.1mgCaCO3earthworm?1day?1 in the form of granules up to 2mm in diameter. Production rate increased with soil pH (r2=0.68, p<0.01). Earthworms could be a significant source of calcite in soils.

D. C. Lambkin; K. H. Gwilliam; C. Layton; M. G. Canti; T. G. Piearce; M. E. Hodson

2011-01-01

325

Antitumor drug Paclitaxel-loaded pH-sensitive nanoparticles targeting tumor extracellular pH  

Microsoft Academic Search

Research efforts have been devoted to demonstrating that the pH-sensitive characteristics of poly NIPAAm\\/chitosan nanoparticles can be applied to targeting tumors. A copolymer of (NIPAAm) and chitosan (4:1, m\\/m) was synthesized, and its drug release characteristics investigated. The results revealed that drug-loaded nanoparticles which encapsulation and loading efficiencies were 85.7% and 9.6%, respectively, exhibited pH-sensitive responses to tumor pH. The

Fan Li; Hong Wu; Hui Zhang; Fei Li; Chun-hu Gu; Qian Yang

2009-01-01

326

Evaluation of pH at the bacteria-dental cement interface.  

PubMed

Physiochemical assessment of the parasite-biomaterial interface is essential in the development of new biomaterials. The purpose of this study was to develop a method to evaluate pH at the bacteria-dental cement interface and to demonstrate physiochemical interaction at the interface. The experimental apparatus with a well (4.0 mm in diameter and 2.0 mm deep) was made of polymethyl methacrylate with dental cement or polymethyl methacrylate (control) at the bottom. Three representative dental cements (glass-ionomer, zinc phosphate, and zinc oxide-eugenol cements) were used. Each specimen was immersed in 2 mM potassium phosphate buffer for 10 min, 24 hrs, 1 wk, or 4 wks. The well was packed with Streptococcus mutans NCTC 10449, and a miniature pH electrode was placed at the interface between bacterial cells and dental cement. The pH was monitored after the addition of 1% glucose, and the fluoride contained in the cells was quantified. Glass-ionomer cement inhibited the bacteria-induced pH fall significantly compared with polymethyl methacrylate (control) at the interface (10 min, 5.16 ± 0.19 vs. 4.50 ± 0.07; 24 hrs, 5.20 ± 0.07 vs. 4.59 ± 0.11; 1 wk, 5.34 ± 0.14 vs. 4.57 ± 0.11; and 4 wks, 4.95 ± 0.27 vs. 4.40 ± 0.14), probably due to the fluoride released from the cement. This method could be useful for the assessment of pH at the parasite-biomaterial interface. PMID:21933936

Mayanagi, G; Igarashi, K; Washio, J; Nakajo, K; Domon-Tawaraya, H; Takahashi, N

2011-12-01

327

Evaluation of pH at the Bacteria-Dental Cement Interface  

PubMed Central

Physiochemical assessment of the parasite-biomaterial interface is essential in the development of new biomaterials. The purpose of this study was to develop a method to evaluate pH at the bacteria-dental cement interface and to demonstrate physiochemical interaction at the interface. The experimental apparatus with a well (4.0 mm in diameter and 2.0 mm deep) was made of polymethyl methacrylate with dental cement or polymethyl methacrylate (control) at the bottom. Three representative dental cements (glass-ionomer, zinc phosphate, and zinc oxide-eugenol cements) were used. Each specimen was immersed in 2 mM potassium phosphate buffer for 10 min, 24 hrs, 1 wk, or 4 wks. The well was packed with Streptococcus mutans NCTC 10449, and a miniature pH electrode was placed at the interface between bacterial cells and dental cement. The pH was monitored after the addition of 1% glucose, and the fluoride contained in the cells was quantified. Glass-ionomer cement inhibited the bacteria-induced pH fall significantly compared with polymethyl methacrylate (control) at the interface (10 min, 5.16 ± 0.19 vs. 4.50 ± 0.07; 24 hrs, 5.20 ± 0.07 vs. 4.59 ± 0.11; 1 wk, 5.34 ± 0.14 vs. 4.57 ± 0.11; and 4 wks, 4.95 ± 0.27 vs. 4.40 ± 0.14), probably due to the fluoride released from the cement. This method could be useful for the assessment of pH at the parasite-biomaterial interface.

Mayanagi, G.; Igarashi, K.; Washio, J.; Nakajo, K.; Domon-Tawaraya, H.; Takahashi, N.

2011-01-01

328

Feasibility of converting hi-speed processor for processing Kodak film types 7381/7271 (16mm) and 5381/5271 (35mm) using Kodak ECP chemistry  

NASA Technical Reports Server (NTRS)

Testing conducted to determine the feasibility of converting the 16/35/70 hi-speed processor to process Kodak film types 7381/7271 (16mm) and 5381/5271 (35mm) color negative films using Kodak ECP chemistry is described.

Weinstein, M. S.

1974-01-01

329

The apoplastic pH of the substomatal cavity of Vicia faba leaves and its regulation responding to different stress factors.  

PubMed

The apoplastic pH of the substomatal cavity is an essential determinant of stomatal movement. In detached leaves of Vicia faba substomatal apoplastic pH and its dependence on external (stress) factors was investigated using a non-invasive approach: pH-microsensors were inserted into open stomata, and upon contact with the apoplastic fluid, pH was measured continuously, as apoplastic pH was challenged by changed conditions of light, atmosphere (NH(3), CO(2)), and xylem sap (abscisic acid, cyanide, fusicoccin, pH, inorganic salts). Apoplastic pH proved extremely sensitive to infiltration and local flooding, which rapidly increased the apoplastic pH by more than 1.5 pH units. Recovery from infiltration took several hours, during which light effects on the apoplastic pH were strongly impeded. This indicates that pH tests carried out under such conditions may not be representative of the undisturbed leaf. NH(3), flushed across the stomata, yielded a rapid apoplastic alkalinization from which an apoplastic buffer capacity of 2-3 mM per pH unit was calculated. Fusicoccin, fed into the xylem sap acidified the apoplast, whereas cyanide alkalized it, thus underscoring the importance of the plasma membrane H(+) pump for apoplastic pH regulation. To address the question to what extent pH was a drought signal, the effect of iso-osmotic pH changes, fed into the xylem through the petiole were tested. It is demonstrated that the apoplastic response remained below 0.1 pH per pH unit imposed, regardless of the buffer capacity. An increase in the osmolarity of the bath solution (harbouring the cut petiole) using KCl, NaCl, CaCl(2) or sorbitol alkalized the substomatal apoplast. It is suggested that pH may only act as drought signal when accompanied by elevated osmolarity. PMID:11741043

Felle, Hubert H; Hanstein, Stefan

2002-01-01

330

Microfabrication of a tapered channel for isoelectric focusing with thermally generated pH gradient.  

PubMed

A simple microfabrication technique for the preparation of a tapered microchannel for thermally generated pH gradient isoelectric focusing (IEF) has been demonstrated. The tapered channel was cut into a plastic sheet (thickness was 120 microm), and the channel was closed by sandwiching the plastic sheet between two glass microscope slides. The length of the microchannel was 5 cm. The width of the separation channel was 0.4 mm at the narrow end and 4 mm at the wide end. The channel was coated with polyacrylamide to prevent electroosmotic flow (EOF) during focusing. Two electrolyte vials were mounted on top of each end of the channel with the wide end of the channel connected to the cathodic vial and the narrow to the anodic vial. The feasibility of the thermally generated pH gradient in a tapered channel was demonstrated. Important parameters that determined the feasibility of using a thermally generated pH gradient in a tapered channel were analyzed. Parameters to be optimized were control of EOF and hydrodynamic flow, selection of power supply mode and prevention of local overheating and air bubble formation. Tris-HCl buffer, which has a high pK(a) dependence with temperature, was used both to dissolve proteins and as the electrolyte. The thermally generated pH gradient separation of proteins was tested by focusing dog, cat and human hemoglobins with a whole column detection capillary IEF (CIEF) system. PMID:12412118

Huang, Tiemin; Pawliszyn, Janusz

2002-10-01

331

PhET Simulation: Build An Atom  

NSDL National Science Digital Library

This simulation is designed to help learners visualize atomic structure, as they drag protons, neutrons, and electrons to construct an atom. As particles are moved into place in the nucleus or the electron orbits, the simulation automatically displays the net charge, mass number, atomic symbol, and name of the element. After practicing with atom-building, users can test their skills against the clock in a game with four levels of increasing difficulty. See Related Materials for a lesson plan and student guide developed by the PhET project specifically for use with Build An Atom. The atom building simulation, which must be open and displayed to complete this activity, is available from PhET at: Build An Atom. This lesson is part of PhET (Physics Education Technology Project), a large collection of free interactive simulations for science education.

332

PhET Teacher Activities: Modeling Isotopes  

NSDL National Science Digital Library

This lesson plan was created specifically to accompany the PhET simulation "Isotopes and Atomic Mass". Appropriate for grades 7-10, it provides explicit guidance for modeling atoms and their variant isotopes. As students add neutrons to the nuclear model, they can see a relationship between the stability of the atom and its abundance in nature. The model makes it easy to visualize that atoms of one element always have the same number of protons, but can have various numbers of neutrons. It will help students differentiate Atomic Number (number of protons in the nucleus) from Mass Number (the number of protons and neutrons. The isotope simulation, which must be open and displayed to complete this activity, is available from PhET at: Isotopes and Atomic Mass. This lesson is part of PhET (Physics Education Technology Project), a large collection of free interactive simulations for science education.

Marrero, Robert

2011-07-18

333

Sensitization of Listeria monocytogenes to Low pH, Organic Acids, and Osmotic Stress by Ethanol  

PubMed Central

The killing of Listeria monocytogenes following exposure to low pH, organic acids, and osmotic stress was enhanced by the addition of 5% (vol/vol) ethanol. At pH 3, for example, the presence of this agent stimulated killing by more than 3 log units in 40 min of exposure. The rate of cell death at pH 3.0 was dependent on the concentration of ethanol. Thus, while the presence 10% (vol/vol) ethanol at pH 3.0 stimulated killing by more than 3 log units in just 5 min, addition of 1.25% (vol/vol) ethanol resulted in less than 1 log unit of killing in 10 min. The ability of 5% (vol/vol) ethanol to stimulate killing at low pH and at elevated osmolarity was also dependent on the amplitude of the imposed stress, and an increase in the pH from 3.0 to 4.0 or a decrease in the sodium chloride concentration from 25 to 2.5% led to a marked reduction in the effectiveness of 5% (vol/vol) ethanol as an augmentative agent. Combinations of organic acids, low pH, and ethanol proved to be particularly effective bactericidal treatments; the most potent combination was pH 3.0, 50 mM formate, and 5 % (vol/vol) ethanol, which resulted in 5 log units of killing in just 4 min. Ethanol-enhanced killing correlated with damage to the bacterial cytoplasmic membrane.

Barker, Clive; Park, Simon F.

2001-01-01

334

CRCHD Principal Investigator: Campbell, Janis, Ph.D.  

Cancer.gov

CRCHD Principal Investigator: Campbell, Janis, Ph.D.  Back to CRCHD Ongoing Research CNP Project Listing Janis Campbell, Ph.D. CNP Project Listing CNP Pilot Projects Project Investigator Biography Campbell, Janis, Ph.D. University of

335

CRCHD Principal Investigator: Paula A. Espinoza, Ph.D.  

Cancer.gov

CRCHD Principal Investigator: Paula A. Espinoza, Ph.D.  Back to CRCHD Ongoing Research CNP Project Listing Paula A. Espinoza, Ph.D. CNP Project Listing CNP Pilot Projects Project Investigator Biography Paula A. Espinoza, Ph.D. University

336

PhET Simulations: Quantum Phenomena  

NSDL National Science Digital Library

This is a collection of simulations from the PhET project in Quantum and Modern Physics. The simulations cover a range of topics including the photoelectric effect, wave interference, lasers, blackbody radiation, tunneling, the Stern-Gerlach experiment, nuclear physics, and applications of quantum mechanics. Each simulation provides a user interface that allows learners to explore the physical systems. These resources are part of the PhET project that has created a large collection of research-validated physics, chemistry, and math simulations.

Project, Physics E.

2008-07-13

337

PhEt - Physics Education Technology  

NSDL National Science Digital Library

PhEt is a free website of over sixty interactive simulations that provides opportunities for students to learn physics and chemistry through exploration and virtual labs. A browsable teacher-contributed collection of homework assignments, lectures, activities, and concept questions is available. Additional contributions designed to be used in conjunction with the PhET simulations may be submitted. Simulations can be run in three different ways: on line, by downloading one or more simulations at a time, or by a download of the entire website to your computer. Many simulations have been translated into different languages.

338

Differential genotoxicity of diphenyl diselenide (PhSe)2 and diphenyl ditelluride (PhTe)2.  

PubMed

Organoselenium compounds have been pointed out as therapeutic agents. In contrast, the potential therapeutic aspects of tellurides have not yet been demonstrated. The present study evaluated the comparative toxicological effects of diphenyl diselenide (PhSe)2 and diphenyl ditelluride (PhTe)2 in mice after in vivo administration. Genotoxicity (as determined by comet assay) and mutagenicicity were used as end-points of toxicity. Subcutaneous administration of high doses of (PhSe)2 or (PhTe)2 (500 µmol/kg) caused distinct genotoxicity in mice. (PhSe)2 significantly decreased the DNA damage index after 48 and 96 h of its injection (p < 0.05). In contrast, (PhTe) caused a significant increase in DNA damage (p < 0.05) after 48 and 96 h of intoxication. (PhSe)2 did not cause mutagenicity but (PhTe)2 increased the micronuclei frequency, indicating its mutagenic potential. The present study demonstrated that acute in vivo exposure to ditelluride caused genotoxicity in mice, which may be associated with pro-oxidant effects of diphenyl ditelluride. In addition, the use of this compound and possibly other related tellurides must be carefully controlled. PMID:24711962

Meinerz, Daiane Francine; Allebrandt, Josiane; Mariano, Douglas O C; Waczuk, Emily P; Soares, Felix Antunes; Hassan, Waseem; Rocha, João Batista T

2014-01-01

339

Brain metabolism is significantly impaired at blood glucose below 6 mM and brain glucose below 1 mM in patients with severe traumatic brain injury  

PubMed Central

Introduction The optimal blood glucose target following severe traumatic brain injury (TBI) must be defined. Cerebral microdialysis was used to investigate the influence of arterial blood and brain glucose on cerebral glucose, lactate, pyruvate, glutamate, and calculated indices of downstream metabolism. Methods In twenty TBI patients, microdialysis catheters inserted in the edematous frontal lobe were dialyzed at 1 ?l/min, collecting samples at 60 minute intervals. Occult metabolic alterations were determined by calculating the lactate- pyruvate (L/P), lactate- glucose (L/Glc), and lactate- glutamate (L/Glu) ratios. Results Brain glucose was influenced by arterial blood glucose. Elevated L/P and L/Glc were significantly reduced at brain glucose above 1 mM, reaching lowest values at blood and brain glucose levels between 6-9 mM (P < 0.001). Lowest cerebral glutamate was measured at brain glucose 3-5 mM with a significant increase at brain glucose below 3 mM and above 6 mM. While L/Glu was significantly increased at low brain glucose levels, it was significantly decreased at brain glucose above 5 mM (P < 0.001). Insulin administration increased brain glutamate at low brain glucose, but prevented increase in L/Glu. Conclusions Arterial blood glucose levels appear to be optimal at 6-9 mM. While low brain glucose levels below 1 mM are detrimental, elevated brain glucose are to be targeted despite increased brain glutamate at brain glucose >5 mM. Pathogenity of elevated glutamate appears to be relativized by L/Glu and suggests to exclude insulin- induced brain injury.

2010-01-01

340

Effects of pH, Chloride, and Bicarbonate on Cu(I) Oxidation Kinetics at Circumneutral pH  

NASA Astrophysics Data System (ADS)

The redox chemistry of copper species in the upper water column plays a significant role in its speciation, transport and bioavailability. Most previous studies have focused primarily on Cu(II), principally because Cu(I) is easily oxidized to Cu(II) by oxygen or other oxidants. However, a growing body of evidence indicates that a number of potentially important reactions may lead to Cu(I) formation and result in a significant steady-state concentration of Cu(I) in natural waters. Redox reactions of Cu(I) could result in the production of reactive oxygen species (ROS), such as superoxide and hydroxyl radical, that may subsequently induce a cascade of radical-promoted reactions with other constituents in natural waters. As such, a better understanding of copper-catalysed processes that produce and consume O2- is important in furthering our insight into factors contributing to global biogeochemical cycles. In this study, the oxidation kinetics of nanomolar concentrations of Cu(I) in NaCl solutions have been investigated over the pH range 6.5-8.0.The overall apparent oxidation rate constant was strongly affected by chloride, moderately by bicarbonate and, and to a lesser extent, by pH. In the absence of bicarbonate, an equilibrium-based speciation model indicated that Cu+ and CuClOH- were the most kinetically reactive species, while the contribution of other Cu(I) species to the overall oxidation rate was minor. A kinetic model based on recognized key redox reactions for these two species further indicated that oxidation of Cu(I) by oxygen and superoxide were important reactions at all pH values and [Cl-] considered, but back reduction of Cu(II) by superoxide only became important at relatively low chloride concentrations. Bicarbonate concentrations from 2-5 mM substantially accelerated Cu(I) oxidation. Kinetic analysis over a range of bicarbonate concentrations revealed that this was due to the formation of CuCO3-, which reacts relatively rapidly with oxygen, and not due to inhibition of the back reduction of Cu(II) by formation of Cu(II)-carbonate complexes. We conclude that the simultaneous oxygenation of Cu+, CuClOH- and CuCO3- is the rate-limiting step in the overall oxidation of Cu(I) under these conditions. Determination of values for apparent and intrinsic rate constants for the oxidation of those critical Cu(I) species by O2 over the pH range 6.5-8.0 should greatly assist in understanding and predicting inorganic Cu(I) and Cu(II) transformations in natural waters.

Yuan, X.; Pham, A.; Waite, T.; Xing, G.; Rose, A.

2012-12-01

341

Repeatability of the efficiency of columns packed with sub-3?m core-shell particles: Part I. 2.6?m Kinetex-C(18) particles in 4.6mm and 2.1mm×100mm column formats.  

PubMed

The column-to-column repeatability of the mass transfer mechanism in columns packed with sub-3?m shell particles was investigated. The parameters of this mechanism were measured for twelve columns (six 2.1mm×100mm and six 4.6mm×100mm) packed with the same batch of 2.6?m Kinetex-C(18) particles (Phenomenex, CA, USA). For both series, the manufacturer provided columns at different positions in the efficiency distribution given by the quality test control. Three compounds were used, uracil, naphthalene and insulin. The reduced longitudinal diffusion term was measured with the peak parking (PP) method, the reduced solid-liquid mass transfer resistance term was given by a combination of the PP results and a model of effective diffusion in ternary composite materials (non-porous cores, concentric porous shell, and eluent matrix), validated previously. The overall eddy diffusion term was obtained by subtraction of these two HETP terms from the overall reduced HETP measured by numerical integration of the entire peak profiles. The results demonstrate that the dispersion of the column efficiencies is only due to the random nature of the packing process. At the highest reduced velocity achieved, the relative standard deviations (RSDs) of the eddy diffusion term for the 2.1mm I.D. columns were ca. 7% and 3% for the low molecular weight compounds and for insulin, respectively. For the 4.6mm I.D. columns, these RSDs were 15% and 5%, respectively. The larger RSDs for the 4.6mm I.D. columns is explained by the exceptionally low value of the eddy diffusion term. PMID:22762953

Gritti, Fabrice; Guiochon, Georges

2012-08-24

342

SUBMILLIMETER ARRAY OBSERVATIONS TOWARD THE MASSIVE STAR-FORMING CORE MM1 OF W75N  

SciTech Connect

The massive star-forming core MM1 of W75N was observed using the Submillimeter Array with {approx}1'' and 2'' spatial resolutions at 217 and 347 GHz, respectively. From the 217 GHz continuum we found that the MM1 core consists of two sources, separated by about 1'': MM1a ({approx}0.6 M{sub sun}) and MM1b ({approx}1.4 M{sub sun}), located near the radio continuum sources VLA 2/VLA 3 and VLA 1, respectively. Within MM1b, two gas clumps were found to be expanding away from VLA 1 at about {+-}3 km s{sup -1}, as a result of the most recent star formation activity in the region. Observed molecular lines show emission peaks at two positions, MM1a and MM1b: sulfur-bearing species have emission peaks toward MM1a, but methanol and saturated species at MM1b. We identified high-temperature ({approx}200 K) gas toward MM1a and the hot core in MM1b. This segregation may result from the evolution of the massive star-forming core. In the very early phase of star formation, the hot core is seen through the evaporation of dust ice-mantle species. As the mantle species are consumed via evaporation the high-temperature gas species (such as the sulfur-bearing molecules) become bright. The SiO molecule is unique in having an emission peak exactly at the VLA 2 position, probably tracing a shock powered by VLA 2. The observed sulfur-bearing species show similar abundances both in MM1a and MM1b, whereas the methanol and saturated species show significant abundance enhancement toward MM1b, by about an order of magnitude, compared to MM1a.

Minh, Y. C. [Korea Astronomy and Space Science Institute (KASI), 838 Daeduk-daero, Hwaam, Yuseong-gu, Daejeon 305-348 (Korea, Republic of); Su, Y.-N.; Liu, S.-Y.; Yan, C.-H. [Academia Sinica, Institute of Astronomy and Astrophysics (ASIAA), P.O. Box 23-141, Taipei 106, Taiwan (China); Chen, H.-R. [Institute of Astronomy and Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Kim, S.-J., E-mail: minh@kasi.re.k [Department of Astronomy and Space Science, Kyunghee University, Yongin, Gyeonggi 446-701 (Korea, Republic of)

2010-11-10

343

pH & Rate of Enzymatic Reactions.  

ERIC Educational Resources Information Center

A quantitative and inexpensive way to measure the rate of enzymatic reaction is provided. The effects of different pH levels on the reaction rate of an enzyme from yeast are investigated and the results graphed. Background information, a list of needed materials, directions for preparing solutions, procedure, and results and discussion are…

Clariana, Roy B.

1991-01-01

344

Effect of Ph on Human Mycoplasma Strains.  

National Technical Information Service (NTIS)

The optimal reaction of culture media for the cultivation of T-strain Mycoplasma of human origin was investigated. By use of a recently modified tryptic digest medium, the optimal reaction in either agar or fluid medium was found to be pH 6.0. In contrast...

M. C. Shepard C. D. Lunceford

1964-01-01

345

The Economic Contribution of PhDs  

ERIC Educational Resources Information Center

This paper looks at what the value of a doctorate is, both to employers in particular and to society and the economy at large. Given the emphasis many universities and funding agencies/governments are putting upon the development of PhD programmes, this is an issue deserving attention. The paper tries to show how two separate but interrelated…

Casey, Bernard H.

2009-01-01

346

Monitoring fetal pH by telemetry  

NASA Technical Reports Server (NTRS)

Telemetry unit has been developed for possible use in measuring scalp-tissue pH and heart rate of unborn infant. Unit radius data to receiver as much as 50 ft. away. Application exists during hours just prior to childbirth to give warning of problems that might require cesarean delivery.

Blum, A.; Donahoe, T.; Jhabvala, M. D.; Ryan, W.

1980-01-01

347

First-Principles pH Theory  

NASA Astrophysics Data System (ADS)

Despite being one of the most important macroscopic measures and a long history even before the quantum mechanics, the concept of pH has rarely been mentioned in microscopic theories, nor being incorporated computationally into first-principles theory of aqueous solutions. Here, we formulate a theory for the pH dependence of solution formation energy by introducing the proton chemical potential as the microscopic counterpart of pH in atomistic solution models. Within the theory, the general acid-base chemistry can be cast in a simple pictorial representation. We adopt density-functional molecular dynamics to demonstrate the usefulness of the method by studying a number of solution systems including water, small solute molecules such as NH3 and HCOOH, and more complex amino acids with several functional groups. For pure water, we calculated the auto- ionization constant to be 13.2 with a 95 % accuracy. For other solutes, the calculated dissociation constants, i.e., the so- called pKa, are also in reasonable agreement with experiments. Our first-principles pH theory can be readily applied to broad solution chemistry problems such as redox reactions.

Kim, Yong-Hyun; Zhang, S. B.

2006-03-01

348

The Ph.D. Value Proposition  

ERIC Educational Resources Information Center

Atlanta University launched its doctor of arts in humanities (DAH) programs almost 40 years ago, and, since the 1988 merger with Clark College, Clark Atlanta University has continued to award the degrees. This fall, for the first time, its students will be able to earn Ph.D.s in humanities instead. In DAH programs around the country, there's been…

Cooper, Kenneth J.

2012-01-01

349

Teaching Physics Using PhET Simulations  

ERIC Educational Resources Information Center

PhET Interactive Simulations (sims) are now being widely used in teaching physics and chemistry. Sims can be used in many different educational settings, including lecture, individual or small group inquiry activities, homework, and lab. Here we will highlight a few ways to use them in teaching, based on our research and experiences using them in…

Wieman, C. E.; Adams, W. K.; Loeblein, P.; Perkins, K. K.

2010-01-01

350

Monograph on Borax, Boric Acid, and Borates.  

National Technical Information Service (NTIS)

The monographs summarize the available scientific literature from 1920 to 1978 related to the safety of food ingredients. Chemical information, biological data, and biochemical aspects are given. Other individual monographs are also available:

R. Handler

1978-01-01

351

Evolving Starburst Model of FIR\\/sub-mm\\/mm Line Emission and Its Applications to M82 and Nearby Luminous Infrared Galaxies  

Microsoft Academic Search

This thesis presents a starburst model for far-infrared\\/sub-millimeter\\/millimeter (FIR\\/sub- mm\\/mm) line emission of molecular and atomic gas in an evolving starburst region, which is treated as an ensemble of non-interacting hot bubbles which drive spherical shells of swept-up gas into a surrounding uniform gas medium. These bubbles and shells are driven by winds and supernovae within massive star clusters formed

Lihong Yao

352

Empirical force field (MM2 and MM3) calculations for peracetylated 1-deoxy-1-nitroheptitols and peracetylated 2-deoxyaldooctoses suggest that theoretical conformational analysis may be unreliable  

NASA Astrophysics Data System (ADS)

The conformational analysis of all sixteen possible diastereomeric configurations of peracetylated 2-deoxyaldooctoses and peracetylated 1-deoxy-1-nitroheptitols was undertaken. Molecular mechanics calculations were used to compute the geometries and energies of the compounds. Proton-proton vicinal coupling constants were also estimated from molecular mechanics results after applying a generalized Karplus equation. Comparison with the available experimental data confirms the global correctness of the calculations. A comparative study of MM2 and MM3 force fields for these compounds is presented.

Velasco, D.; Jaime, C.; Sánchez-Ruiz, X.

1995-10-01

353

Assessing the performance of the MM/PBSA and MM/GBSA methods: I. The accuracy of binding free energy calculations based on molecular dynamics simulations  

PubMed Central

The Molecular Mechanics/Poisson Boltzmann Surface Area (MM/PBSA) and the Molecular Mechanics/Generalized Born Surface Area (MM/GBSA) methods calculate binding free energies for macromolecules by combining molecular mechanics calculations and continuum solvation models. To systematically evaluate the performance of these methods, we report here an extensive study of 59 ligands interacting with six different proteins. First, we explored the effects of the length of the molecular dynamics (MD) simulation, ranging from 400 to 4800 ps, and the solute dielectric constant (1, 2 or 4) to the binding free energies predicted by MM/PBSA. The following three important conclusions could be observed: (1). MD simulation lengths have obvious impact on the predictions, and longer MD simulations are not always necessary to achieve better predictions; (2). The predictions are quite sensitive to solute dielectric constant, and this parameter should be carefully determined according to the characteristics of the protein/ligand binding interface; (3). Conformational entropy showed large fluctuations in MD trajectories and a large number of snapshots are necessary to achieve stable predictions. Next, we evaluated the accuracy of the binding free energies calculated by three Generalized Born (GB) models. We found that the GB model developed by Onufriev and Case was the most successful model in ranking the binding affinities of the studied inhibitors. Finally, we evaluated the performance of MM/GBSA and MM/PBSA in predicting binding free energies. Our results showed that MM/PBSA performed better in calculating absolute, but not necessarily relative, binding free energies than MM/GBSA. Considering its computational efficiency, MM/GBSA can serve as a powerful tool in drug design, where correct ranking of inhibitors is often emphasized.

Hou, Tingjun; Wang, Junmei; Li, Youyong; Wang, Wei

2011-01-01

354

Assessing the performance of the MM/PBSA and MM/GBSA methods. 1. The accuracy of binding free energy calculations based on molecular dynamics simulations.  

PubMed

The Molecular Mechanics/Poisson-Boltzmann Surface Area (MM/PBSA) and the Molecular Mechanics/Generalized Born Surface Area (MM/GBSA) methods calculate binding free energies for macromolecules by combining molecular mechanics calculations and continuum solvation models. To systematically evaluate the performance of these methods, we report here an extensive study of 59 ligands interacting with six different proteins. First, we explored the effects of the length of the molecular dynamics (MD) simulation, ranging from 400 to 4800 ps, and the solute dielectric constant (1, 2, or 4) on the binding free energies predicted by MM/PBSA. The following three important conclusions could be observed: (1) MD simulation length has an obvious impact on the predictions, and longer MD simulation is not always necessary to achieve better predictions. (2) The predictions are quite sensitive to the solute dielectric constant, and this parameter should be carefully determined according to the characteristics of the protein/ligand binding interface. (3) Conformational entropy often show large fluctuations in MD trajectories, and a large number of snapshots are necessary to achieve stable predictions. Next, we evaluated the accuracy of the binding free energies calculated by three Generalized Born (GB) models. We found that the GB model developed by Onufriev and Case was the most successful model in ranking the binding affinities of the studied inhibitors. Finally, we evaluated the performance of MM/GBSA and MM/PBSA in predicting binding free energies. Our results showed that MM/PBSA performed better in calculating absolute, but not necessarily relative, binding free energies than MM/GBSA. Considering its computational efficiency, MM/GBSA can serve as a powerful tool in drug design, where correct ranking of inhibitors is often emphasized. PMID:21117705

Hou, Tingjun; Wang, Junmei; Li, Youyong; Wang, Wei

2011-01-24

355

Recovery of macroinvertebrates by screening in the field: a comparison between coarse (1.18 mm) and fine (0.60 mm) mesh sieves  

USGS Publications Warehouse

We evaluated the potential loss of target benthic macroinvertebrates from coarse-mesh field wash down of samples through a 1.18-mm mesh sieve nested on a 0.60-mm mesh sieve. Visible target organisms (midges, mayflies, and fingernail clams) in the 1.18-mm mesh sieve were removed from the sample and enumerated in the field. The entire contents of both sieves were preserved for subsequent laboratory enumeration under 4X magnification. Percent recoveries from each treatment were based on total intact organisms found in all sieves. Percent recovery for fingernail clams found in the field (31%) was lower than for mayflies (79%) and midges (88%). Laboratory enumeration of organisms retained by the 1.18-mm sieve yielded additional fingernail clams (to total 74% recovered in the field and lab), mayflies (to total 89%), and midges (to total 91%). If the 1.18-mm sieve is used alone in the field, it is adequate to monitor mayflies, midges >1 cm, and adult fingernail clams greater than or equal to 5.0 mm shell length.

Dukerschein, J. T.; Gent, R.; Sauer, J.

1996-01-01

356

Effect of electrolyte pH on CIEF with narrow pH range ampholytes.  

PubMed

CIEF of components following sequential injection of ampholytes and the sample zone offers unique advantages for analysis. The most important one of these is the efficient separation of amphoteric compounds having pIs outside the pH range of the ampholytes applied, but the resolution of the components can be increased by an adequate setup in the injection protocol. In this study, the effect of the pH of the anolyte and catholyte on the selectivity and speed of the isoelectric focusing was investigated. Changes in the pH values significantly influenced the resolution and the length of the pH gradient, while changes in the charge state of components were also observed. Three ampholyte solutions (from different suppliers) covering only two pH units were used for the analyses of substituted nitrophenol dyes in uncoated capillary. With appropriate setup, the components, with pIs not covered by the ampholyte pH range, migrated in charged state outside the pH gradient. This phenomenon is preferable for coupling isoelectric focusing to MS detection, by evading the undesirable ion suppression effect of ampholytes. PMID:23086725

Páger, Csilla; Vargová, Andrea; Takácsi-Nagy, Anna; Dörnyei, Ágnes; Kilár, Ferenc

2012-11-01

357

Regulation of Escherichia coli formate hydrogenlyase activity by formate at alkaline pH.  

PubMed

Escherichia coli possesses two hydrogenases, Hyd-3 and Hyd-4. These, in conjunction with formate dehydrogenase H (Fdh-H), constitute distinct membrane-associated formate hydrogenlyases, FHL-1 and FHL-2, both catalyzing the decomposition of formate to H(2) and CO(2) during fermentative growth. FHL-1 is the major pathway at acidic pH whereas FHL-2 is proposed for slightly alkaline pH. In this study, regulation of activity of these pathways by formate has been investigated. In cells grown under fermentative conditions on glucose in the presence of 30 mM formate at pH 7.5, intracellular pH was decreased to 7.1, the activity of Fdh-H raised 3.5-fold, and the production of H(2) became mostly Hyd-3 dependent. These results suggest that at alkaline pH formate increases an activity of Fdh-H and of Hyd-3 both but not of Hyd-4. PMID:12192527

Mnatsakanyan, Nelli; Vassilian, Anait; Navasardyan, Liparit; Bagramyan, Karine; Trchounian, Armen

2002-10-01

358

Effects of cytoplasmic and luminal pH on Ca(2+) release channels from rabbit skeletal muscle.  

PubMed Central

Ryanodine receptor (RyR)-Ca(2+) release channels from rabbit skeletal muscle were incorporated into lipid bilayers. The effects of cytoplasmic and luminal pH were studied separately over the pH range 5-8, using half-unit intervals. RyR activity (at constant luminal pH of 7.5) was inhibited at acidic cytoplasmic pH, with a half-inhibitory pH (pH(I)) approximately 6.5, irrespective of bilayer potential and of whether the RyRs were activated by cytoplasmic Ca(2+) (50 microM), ATP (2 or 5 mM), or both. Inhibition occurred within approximately 1 s and could be fully reversed within approximately 1 s after brief inhibition or within approximately 30-60 s after longer exposure to acidic cytosolic pH. There was no evidence of any hysteresis in the cytoplasmic pH effect. Ryanodine-modified channels were less sensitive to pH inhibition, with pH(I) at approximately 5.5, but the inhibition was similarly reversible. Steady-state open and closed dwell times of RyRs during cytoplasmic pH inhibition suggest a mechanism where the binding of one proton inhibits the channel and the binding of two to three additional protons promotes further inhibited states. RyR activity was unaffected by luminal pH in the pH range 7.5 to 6.0. At lower luminal pH (5-5.5) most RyRs were completely inhibited, and raising the pH again produced partial to full recovery in only approximately 50% of cases, with the extent of recovery not detectably different between pH 7.5 and pH 9. The results indicate that isolated skeletal muscle RyRs are not inhibited as strongly by low cytoplasmic and luminal pH, as suggested by previous single-channel studies.

Laver, D R; Eager, K R; Taoube, L; Lamb, G D

2000-01-01

359

Optical pH sensor for physiological pH measurement  

NASA Astrophysics Data System (ADS)

A miniature optical sensor based on the fluorescent indicator, 8-hydroxyl-1,3,6-pyrene trisulfonic Acid Trisodium Salt (HOPSA), was developed for physiological pH measurement. Dowex-1 strongly basic anion exchange resin was used as a medium to immobilize the indicator on the end of an optical fiber to form a pH sensing layer. Polyetherurethane was dip- coated onto the sensing layer as the permeable membrane for H+. The properties of the sensor were assessed and found to be suitable for monitoring physiological pH values.

Zhang, Sifu; Rolfe, Peter; Wickramasinghe, Yapa A.

1994-02-01

360

Coordination complexes of Ph?Sb²? and Ph?Bi²?: beyond pnictonium cations.  

PubMed

The syntheses of salts containing ligand-stabilized Ph3Sb(2+) and Ph3Bi(2+) dications have been realized by in?situ formation of Ph3Pn(OTf)2 (Pn=Sb or Bi) and subsequent reaction with OPPh3, dmap and bipy. The solid-state structures demonstrate diversity imposed by the steric demands and nature of the ligands. The synthetic method has the potential for broad application enabling widespread development of the coordination chemistry for Pn(V) acceptors. PMID:24616180

Robertson, Alasdair P M; Burford, Neil; McDonald, Robert; Ferguson, Michael J

2014-03-24

361

Regulation of intracellular pH in cnidarians: response to acidosis in Anemonia viridis.  

PubMed

The regulation of intracellular pH (pHi) is a fundamental aspect of cell physiology that has received little attention in studies of the phylum Cnidaria, which includes ecologically important sea anemones and reef-building corals. Like all organisms, cnidarians must maintain pH homeostasis to counterbalance reductions in pHi, which can arise because of changes in either intrinsic or extrinsic parameters. Corals and sea anemones face natural daily changes in internal fluids, where the extracellular pH can range from 8.9 during the day to 7.4 at night. Furthermore, cnidarians are likely to experience future CO?-driven declines in seawater pH, a process known as ocean acidification. Here, we carried out the first mechanistic investigation to determine how cnidarian pHi regulation responds to decreases in extracellular and intracellular pH. Using the anemone Anemonia viridis, we employed confocal live cell imaging and a pH-sensitive dye to track the dynamics of pHi after intracellular acidosis induced by acute exposure to decreases in seawater pH and NH?Cl prepulses. The investigation was conducted on cells that contained intracellular symbiotic algae (Symbiodinium sp.) and on symbiont-free endoderm cells. Experiments using inhibitors and Na?-free seawater indicate a potential role of Na?/H? plasma membrane exchangers (NHEs) in mediating pHi recovery following intracellular acidosis in both cell types. We also measured the buffering capacity of cells, and obtained values between 20.8 and 43.8 mM per pH unit, which are comparable to those in other invertebrates. Our findings provide the first steps towards a better understanding of acid-base regulation in these basal metazoans, for which information on cell physiology is extremely limited. PMID:24256552

Laurent, Julien; Venn, Alexander; Tambutté, Éric; Ganot, Philippe; Allemand, Denis; Tambutté, Sylvie

2014-02-01

362

Effect of pH of amine fluoride containing toothpastes on enamel remineralization in vitro  

PubMed Central

Background One of the important factors of the demineralization and remineralization equilibrium of enamel is the pH of the surrounding solutions. Effort has been laid in the formulation of different fluoride compounds and the fluoride content in toothpastes but much less is known about the influence of the pH of the toothpastes on their effectiveness. It was therefore the aim of this study to investigate the influence of different pH levels on enamel remineralization in an in vitro experiment using polarization light microscopy and EDX quantitative element analysis. Methods A 5 × 5 mm window on the enamel surface of 40 caries free extracted human premolars was demineralized in a hydroxyethylcellulose solution at pH 4.8. The teeth were divided into 8 groups and the lower half of the window was covered with varnish serving as control. Each group was then immersed in toothpaste slurry containing amine fluoride (1400 ppm) at pH 4.1, 4.5, 5.1 and 6.9 or control toothpaste slurry without fluoride at pH 4.3, 4.7, 5.3 and 7.0. Serial sections were cut through the lesions and investigated with polarization light microscopy and quantitative EDX element analysis. Results The PLM results showed a decreased porous volume of the body of the lesion after incubation with fluoridated toothpaste at pH 4.53 and 5.16. No differences between the experimental window and the control window were found in the other groups. The quantitative element analysis showed no differences in the element content of any of the groups. Conclusion From the results it can be concluded that slightly acidified fluoridated dentifrices may have a certain positive effect on enamel remineralization.

Arnold, Wolfgang H; Haase, Anabel; Hacklaender, Julia; Gintner, Zeno; Banoczy, Jolan; Gaengler, Peter

2007-01-01

363

Does Mid-trimester Cervical Length >= 25 mm Predict Preterm Birth in High-Risk Women?  

PubMed Central

Objective To assess pregnancy outcome along a continuum of cervical lengths ?25 mm. Study Design Planned secondary analysis of a randomized cerclage trial of women with prior spontaneous preterm birth 170–346/7 weeks. Outcomes of women who maintained cervical lengths ?25 mm were analyzed. Women with cervical lengths <25 mm randomized to no cerclage comprised an internal comparison group. Results Of 1014 screened, 153 had cervical length <25mm, and 672 had cervical length ?25 mm. Birth <35 weeks occurred in 16% of the ?25 mm cohort. The relationship between cervical lengths ?25 mm and birth gestational age was null (p=0.15). In the <25 mm group, progressively shorter cervical lengths predicted birth <35 weeks (p<0.001); this relationship was null in the ?25 mm group (p=0.17). Conclusion The continuum of cervical lengths ?25 mm measured between 160/7 and 226/7 weeks does not predict gestational length in women with prior spontaneous preterm birth.

Owen, John; Szychowski, Jeff M.; Hankins, Gary; Iams, Jay D.; Sheffield, Jeanne S.; Perez-Delboy, Annette; Berghella, Vincenzo; Wing, Deborah A.; Guzman, Edwin R.

2010-01-01

364

Monte Carlo evaluation of CTDI{sub {infinity}} in infinitely long cylinders of water, polyethylene and PMMA with diameters from 10 mm to 500 mm  

SciTech Connect

Monte Carlo simulations were used to evaluate the radiation dose to infinitely long cylinders of water, polyethylene, and poly(methylmethacrylate) (PMMA) from 10 to 500 mm in diameter. Radiation doses were computed by simulating a 10 mm divergent primary beam striking the cylinder at z=0, and the scattered radiation in the -z and +z directions was integrated out to infinity. Doses were assessed using the total energy deposited divided by the mass of the 10-mm-thick volume of material in the primary beam. This approach is consistent with the notion of the computed tomography dose index (CTDI) integrated over infinite z, which is equivalent to the dose near the center of an infinitely long CT scan. Monoenergetic x-ray beams were studied from 5 to 140 keV, allowing polyenergetic x-ray spectra to be evaluated using a weighted average. The radiation dose for a 10-mm-thick CT slice was assessed at the center, edge, and over the entire diameter of the phantom. The geometry of a commercial CT scanner was simulated, and the computed results were in good agreement with measured doses. The absorbed dose in water for 120 kVp x-ray spectrum with no bow tie filter for a 50 mm cylinder diameter was about 1.2 mGy per mGy air kerma at isocenter for both the peripheral and center regions, and dropped to 0.84 mGy/mGy for a 500-mm-diam water phantom at the periphery, where the corresponding value for the center location was 0.19 mGy/mGy. The influence of phantom composition was studied. For a diameter of 100 mm, the dose coefficients were 1.23 for water, 1.02 for PMMA, and 0.94 for polyethylene (at 120 kVp). For larger diameter phantoms, the order changed--for a 400 mm phantom, the dose coefficient of polyethylene (0.25) was greater than water (0.21) and PMMA (0.16). The influence of the head and body bow tie filters was also studied. For the peripheral location, the dose coefficients when no bow tie filter was used were high (e.g., for a water phantom at 120 kVp at a diameter of 300 mm, the dose coefficient was 0.97). The body bow tie filter reduces this value to 0.62, and the head bow tie filter (which is not actually designed to be used for a 300 mm object) reduces the dose coefficient to 0.42. The dose in CT is delivered both by the absorption of primary and scattered x-ray photons, and at the center of a water cylinder the ratio of scatter to primary (SPR) doses increased steadily with cylinder diameter. For water, a 120 kVp spectrum and a cylinder diameter of 200 mm, the SPR was 4, and this value grew to 9 for a diameter of 350 mm and to over 16 for a 500-mm-diam cylinder. A freely available spreadsheet was developed to allow the computation of radiation dose as a function of object diameter (10-500 mm), composition (water, polyethylene, PMMA), and beam energy (10-140 keV, 40-140 kVp)

Zhou Hong; Boone, John M. [Department of Radiology and Department of Radiation Oncology, University of California, Davis, Sacramento, California 95817 (United States); Department of Radiology and Department of Biomedical Engineering, University of California, Davis, Sacramento, California 95817 (United States)

2008-06-15

365

pH recovery from intracellular alkalinization in Retzius neurones of the leech central nervous system.  

PubMed Central

1. Neutral-carrier pH-sensitive microelectrodes were used to investigate intracellular pH (pHi) recovery from alkalinization in leech Retzius neurones in Hepes- and in CO2-HCO3(-)-buffered solution. The Retzius neurones were alkaline loaded by the addition and subsequent removal of 16 mM acetate, by changing from 5% CO2-27 mM HCO3- to 2% CO2-11 mM HCO3- or by changing from CO2-HCO3(-)- to Hepes-buffered solution. 2. In Hepes-buffered solution (pH 7.4) the mean pHi was 7.29 +/- 0.11 and the mean membrane potential -44.7 +/- 5.9 mV (mean +/- S.D.; n = 83). 3. The rate of pHi recovery from alkalinization increased with decreasing pH of the bathing medium (pHb). pHi changed about 0.30 pH units for a pHb unit change. 4. A decrease of extracellular buffer concentration (Hepes concentration lowered from 20 to 5 mM) caused an acidification of extracellular and intracellular pH and an acceleration of pHi recovery from alkalinization. 5. A depolarization of the Retzius cell membrane-induced by increasing the K+ concentration of the bathing medium from 4 to 20 mM (delta Em = 16.5 +/- 5.5 mV) or from 4 to 40 mM (delta Em = 24.8 +/- 3.5 mV)--evoked a decrease of pHi and an acceleration of pHi recovery from alkalinization. 6. The H+ current blocker Zn2+ (0.5 mM) inhibited pHi recovery from alkalinization at resting membrane potential as well as during depolarization. The inhibition was more pronounced during depolarization. 7. In Cl(-)-free, CO2-HCO3(-)-buffered solution pHi recovery from an alkaline load by changing from 5% CO2-27 mM HCO3- to 2% CO2-11 mM HCO3- was slowed by 48-71%. The rate of pHi recovery from an alkaline load induced by changing from CO2-HCO3- to Hepes buffer was reduced by 33-56% in Cl(-)-free solution. The removal of external Cl- did not affect pHi recovery in Hepes-buffered solution. 8. The pHi recovery from alkalinization was DIDS-insensitive in CO2-HCO3(-)- as in Hepes-buffered solutions and was not slowed in the absence of external Na+. 9. It is concluded that in Retzius neurones pHi recovery from alkalinization is mediated by a passive voltage-dependent H+ influx along the electrochemical proton gradient. In the presence of CO2-HCO3- buffer a DIDS-insensitive Cl(-)-HCO3- exchanger additionally regulates pHi after an intracellular alkaline load. It cannot be excluded that intracellular processes (e.g. H+ release from organelles, metabolic H+ production) are also involved in pHi recovery from alkalinization.

Frey, G; Schlue, W R

1993-01-01

366

pH recovery from intracellular alkalinization in Retzius neurones of the leech central nervous system.  

PubMed

1. Neutral-carrier pH-sensitive microelectrodes were used to investigate intracellular pH (pHi) recovery from alkalinization in leech Retzius neurones in Hepes- and in CO2-HCO3(-)-buffered solution. The Retzius neurones were alkaline loaded by the addition and subsequent removal of 16 mM acetate, by changing from 5% CO2-27 mM HCO3- to 2% CO2-11 mM HCO3- or by changing from CO2-HCO3(-)- to Hepes-buffered solution. 2. In Hepes-buffered solution (pH 7.4) the mean pHi was 7.29 +/- 0.11 and the mean membrane potential -44.7 +/- 5.9 mV (mean +/- S.D.; n = 83). 3. The rate of pHi recovery from alkalinization increased with decreasing pH of the bathing medium (pHb). pHi changed about 0.30 pH units for a pHb unit change. 4. A decrease of extracellular buffer concentration (Hepes concentration lowered from 20 to 5 mM) caused an acidification of extracellular and intracellular pH and an acceleration of pHi recovery from alkalinization. 5. A depolarization of the Retzius cell membrane-induced by increasing the K+ concentration of the bathing medium from 4 to 20 mM (delta Em = 16.5 +/- 5.5 mV) or from 4 to 40 mM (delta Em = 24.8 +/- 3.5 mV)--evoked a decrease of pHi and an acceleration of pHi recovery from alkalinization. 6. The H+ current blocker Zn2+ (0.5 mM) inhibited pHi recovery from alkalinization at resting membrane potential as well as during depolarization. The inhibition was more pronounced during depolarization. 7. In Cl(-)-free, CO2-HCO3(-)-buffered solution pHi recovery from an alkaline load by changing from 5% CO2-27 mM HCO3- to 2% CO2-11 mM HCO3- was slowed by 48-71%. The rate of pHi recovery from an alkaline load induced by changing from CO2-HCO3- to Hepes buffer was reduced by 33-56% in Cl(-)-free solution. The removal of external Cl- did not affect pHi recovery in Hepes-buffered solution. 8. The pHi recovery from alkalinization was DIDS-insensitive in CO2-HCO3(-)- as in Hepes-buffered solutions and was not slowed in the absence of external Na+. 9. It is concluded that in Retzius neurones pHi recovery from alkalinization is mediated by a passive voltage-dependent H+ influx along the electrochemical proton gradient. In the presence of CO2-HCO3- buffer a DIDS-insensitive Cl(-)-HCO3- exchanger additionally regulates pHi after an intracellular alkaline load. It cannot be excluded that intracellular processes (e.g. H+ release from organelles, metabolic H+ production) are also involved in pHi recovery from alkalinization. PMID:8331595

Frey, G; Schlue, W R

1993-03-01

367

Molecular dynamics investigation on a series of HIV protease inhibitors: assessing the performance of MM-PBSA and MM-GBSA approaches.  

PubMed

The binding free energies (?G(Bind)) obtained from molecular mechanics with Poisson-Boltzmann surface area (MM-PBSA) or molecular mechanics with Generalized Born surface area (MM-GBSA) calculations using molecular dynamics (MD) trajectories are the most popular procedures to measure the strength of interactions between a ligand and its receptor. Several attempts have been made to correlate the ?G(Bind) and experimental IC(50) values in order to observe the relationship between binding strength of a ligand (with its receptor) and its inhibitory activity. The duration of MD simulations seems very important for getting acceptable correlation. Here, we are presenting a systematic study to estimate the reasonable MD simulation time for acceptable correlation between ?G(Bind) and experimental IC(50) values. A comparison between MM-PBSA and MM-GBSA approaches is also presented at various time scales. MD simulations (10 ns) for 14 HIV protease inhibitors have been carried out by using the Amber program. MM-PBSA/GBSA based ?G(Bind) have been calculated and correlated with experimental IC(50) values at different time scales (0-1 to 0-10 ns). This study clearly demonstrates that the MM-PBSA based ?G(Bind) (?G(Bind)-PB) values provide very good correlation with experimental IC(50) values (quantitative and qualitative) when MD simulation is carried out for a longer time; however, MM-GBSA based ?G(Bind) (?G(Bind)-GB) values show acceptable correlation for shorter time of simulation also. The accuracy of ?G(Bind)-PB increases and ?G(Bind)-GB remains almost constant with the increasing time of simulation. PMID:23121465

Srivastava, Hemant Kumar; Sastry, G Narahari

2012-11-26

368

Re-envisioning the PhD  

NSDL National Science Digital Library

This new site, sponsored by the Pew Charitable Trusts, is home to the Re-envisioning the PhD project, which is tasked with investigating change in doctoral education, in particular, helping to expand the career choices available to PhD students. In the Re-envisioning Project Resources section, visitors will find conference materials, recommendations from studies, summaries of interviews, a bibliography, career resources, and more. The Promising Practices section contains information on the different ways in which groups (universities, associations, organizations, and more) are responding to concerns about doctoral education. The other two main sections of the site, National/ International Resources and News and Updates contain links to even more resources, studies, current news, related projects, and more.

2001-01-01

369

PhET Simulation: States of Matter  

NSDL National Science Digital Library

This simulation helps learners visualize how molecules behave in solids, liquids, and gases. Add or remove heat and watch the motion of the molecules as they change phase. Push the pump and change the volume of matter in the closed container and watch the pressure gauge respond. More advanced students can compare the potential energy graphs for neon, argon, oxygen, and water -- which all have different interaction potential. Editor's Note: This particular activity would be well paired with the PhET "Gas Properties" simulation, which goes into more depth to explore the behavior of gas molecules in a closed container. Together, the simulations promote understanding of gas laws, states of matter, phase change, and kinetic theory. See Related Materials for a link to an exemplary lesson plan developed to accompany "States of Matter" simulation. This item is part of a larger collection of simulations developed by the Physics Education Technology project (PhET).

2011-07-18

370

Highlights From PhUn Week 2007  

NSDL National Science Digital Library

This is an article from The Physiologist. "More than 100 APS physiologists volunteered their time in reaching out to more than 3000 students last November during Physiology Understanding Week (PhUn Week), the APS member-based annual outreach program to local area K-12 schools (http://www.PhUnWeek.org). APS members partnered with more than 70 teachers and science educators from across the nation to develop engaging classroom or campus presentations for students at all grade levels, from day care through twelfth grades. The following vignettes are only a few samples of the excitement and fun generated by the focus on the physiology of health and exercise during the first week in November. All events with the primary APS member and lead teacher coordinators are listed in Table 1.".

2008-02-01

371

Partial Report on Engineering Test of Charge, Propelling, 155-MM, XM119, with Projectile, 155-MM, HE, M107, for Howitzer, 155-MM, M126 (T255E3) (Erosion Phase). .  

National Technical Information Service (NTIS)

An erosion life test was conducted from the 155-mm howitzer, M126. Firing was conducted with the M107 projectile and XM119 propelling charge to determine the accuracy tube life with the newly developed charge. Testing consisted of firing for range accurac...

J. S. Whitcraft

1964-01-01

372

Nanometer optical fiber pH sensor  

Microsoft Academic Search

A thousandfold miniaturization of immobilized optical fiber sensors has been achieved by a near-field optical technique. This technology is based on nanofabricated optical fiber tips and near-field photoinitiated polymerization. Submicrometer pH sensors have been prepared by attaching a copolymer covalently to a silanized fiber tip surface. The sensors have demonstrated their high spatial resolving ability, excellent detection limit (zeptomoles), very

Raoul Kopelman; Weihong Tan; Zhong-You Shi

1993-01-01

373

Cellulose based bulk pH optomembranes  

Microsoft Academic Search

The paper presents an efficient technique for the preparation of pH-sensitive bulk optomembranes for fiber optic chemical sensors (FOCS). The method is based on the physical entrapment of the reagent molecules in the bulk of cellulose acetate membranes. The durable immobilization of a pH indicator is achieved by the addition of an appropriate ion-balance reagent to the cellulose matrix. The

Wojciech Wróblewski; Ewa Ro?niecka; Artur Dybko; Zbigniew Brzózka

1998-01-01

374

PhET: Energy Skate Park  

NSDL National Science Digital Library

Students explore conservation of energy by building ramps, jumps, and tracks for a skateboarder. The relationship of kinetic and potential energy becomes clear through charts of energy vs. time and energy vs. position. The skater can be transported to different planets to illustrate the effects of changing the gravitational constant. This item is part of a larger collection of simulations developed by the Physics Education Technology project (PhET). The simulations are animated, interactive, and game-like environments.

2009-11-25

375

PhET Simulation: Balloons & Buoyancy  

NSDL National Science Digital Library

This applet experiments with a helium balloon, a hot air balloon, or a rigid sphere filled with different gases. The user can discover what makes some balloons float and others sink. Teaching ideas and activities are included. The direct link to the simulation is given as a mirror URL. This is part of a larger collection developed by the Physics Education Technology project (PhET).

2008-07-15

376

Hua Zhang, PhD, Biologist  

Cancer.gov

Hua Zhang received his Bachelor of Medicine at Shanghai Second Medical University then a PhD in Microbiology and Immunology at the University of Arizona. Dr. Zhang has had a longstanding interest in the development of immunotherapies for cancer. He first postdoctoral fellowship was in the Department of Chemical Engineering at the University of Texas where he worked to develop scFv antibody derived biologics (Zhang et al, Cancer Research 1995) and then he subsequently studied with Dr.

377

STM Studies of Mn12-Ph  

NASA Astrophysics Data System (ADS)

Mn12-Ph displays tunneling of quantized magnetization below 3K. In other Mn12 ligand variants this magnetic behavior can alter the electronic behavior of the molecule making them good candidates for a molecular logic gate or q-bit. Mn12O12(C6H5COO)16 (referred to as Mn12-Ph) has a Mn12 core with 16 Phenyl ligands and is deposited via spray injection onto surfaces of highly oriented pyrolytic graphite (HOPG) and other surfaces. We report Mn12-Ph in isolation, resembling single molecules with metallic core atoms and organic outer ligands. The local tunneling current observed within the molecular structure shows a strong bias voltage dependence, which is distinct from that of the surface. Further, evidence of internal inhomogeneity in the local density of states has been observed with high spatial resolution, and this inhomogeneity appears to be due to localized metallic behavior. These results facilitate magneto-metric studies of single molecule magnets in isolation. As compared to bulk crystal studies, our experiments allow the specific investigation of atomic sites in individual molecules.

Reaves, K.; Kim, K.; Iwaya, K.; Hitosugi, T.; Zhao, H.; Dunbar, K. R.; Katzgraber, H. G.; Teizer, W.

2013-03-01

378

Regulation of rabbit medullary collecting duct cell pH by basolateral Na+/H+ and Cl-/base exchange.  

PubMed Central

The collecting duct of the inner stripe outer medulla (OMCDi) is a major site of distal nephron acidification. Using the pH sensitive fluorescent dye 2'-7'-bis(carboxyethyl)-5,6,-carboxyfluorescein (BCECF) and quantitative spectrofluorometry to measure intracellular pH in isolated perfused OMCDi, we have characterized basolateral transport processes responsible for regulation of intracellular pH. Experiments suggesting the existence of basolateral Cl-/base exchange were performed. In HCO3- containing buffers, bath Cl- replacement resulted in reversible alkalinization of the OMCDi from 7.22 +/- 0.05 to 7.57 +/- 0.12. Similarly 0.1 mM bath 4',4'-diisothiocyanostilbene-2,2'-disulphonic acid (DIDS) alkalinized the OMCDi from 7.14 +/- 0.09 to 7.34 +/- 0.09 and blocked further alkalinization by bath Cl- removal (delta = + 0.02 pH units). The concentration dependence kinetics of Cl-/base exchange revealed a K1/2 of 10 mM for external Cl- with a Vmax of 0.50 pH U/min. Experiments suggesting the existence of basolateral Na+/H+ exchange were also performed. Replacement of bath Na+ by tetramethylammonium resulted in reversible cell acidification (7.14 +/- 0.09 to 6.85 +/- 0.1). Tubules that were acidified by a brief exposure to NH4Cl displayed recovery of cell pH back to baseline at a rate that was highly dependent on bath Na+ concentration. Half maximal recovery rate was achieved at 7 mM bath Na+ and Vmax was 0.605 pH U/min. The Na+-dependent rate of cell pH recovery after acidification was blocked by 0.2 mM bath amiloride. These results suggest that intracellular pH in the OMCDi is regulated by parallel basolateral Na+/H+ exchange and Cl-/base exchange.

Breyer, M D; Jacobson, H R

1989-01-01

379

Magnetic Optical Sensor Particles for pH Measurement  

Microsoft Academic Search

Magnetic optical sensor particles (MOSePs) in nanometer scale for pH measurement were synthesized and characterized. The measurement of pH is based on a ratiometric evaluation of the fluorescence of a pH-sensitive indicator dye (N-fluorescein-acrylamide) and a reference dye (a rhodamine derivative) which is not affected by pH. Measurement of pH in aqueous media in the range of pH 5 to

Elisabeth Scheucher; Günter Mistlberger; Ingo Klimant

2010-01-01

380

A wireless passive pH sensor based on pH electrode potential measurement  

Microsoft Academic Search

We present a wireless coupled-coil passive pH sensor for high-resolution remote pH monitoring. The sensor is based on a passive LC coil resonator whose resonant frequency is monitored remotely by measuring the impedance of an interrogator coil coupled to the sensor coil. The sensor consists of an inductive coil connected in parallel with a varactor (voltage dependent capacitor) and a

S. Bhadra; G. E. Bridges; D. J. Thomson; M. S. Freund

2010-01-01

381

Optical pH sensor for physiological pH measurement  

Microsoft Academic Search

A miniature optical sensor based on the fluorescent indicator, 8-hydroxyl-1,3,6-pyrene trisulfonic Acid Trisodium Salt (HOPSA), was developed for physiological pH measurement. Dowex-1 strongly basic anion exchange resin was used as a medium to immobilize the indicator on the end of an optical fiber to form a pH sensing layer. Polyetherurethane was dip- coated onto the sensing layer as the permeable

Sifu Zhang; Peter Rolfe; Yapa A. Wickramasinghe

1994-01-01

382

PhD job market: professional trajectories and incentives during the PhD  

Microsoft Academic Search

It is becoming more and more difficult for PhD graduates to find a job corresponding to their qualifications. Stephan and Levin have shown that this situation weakens the implicit contract between PhD students (or post-doc) and the research team in which they are doing their research. This weakness of the implicit contract may slow down scientific production because of the

V. Mangematin

2000-01-01

383

Evaluation of 3-mm diameter intravenous tubing for the rapid infusion of fluids.  

PubMed Central

The use of intravenous administration systems incorporating 3-mm internal diameter tubing is becoming more common in hospital practice. The maximum flow-rate of crystalloid solutions through 3-mm-diameter tubing is compared to that through conventional 4-mm tubing when connected to standard large-gauge intravenous cannulae. Lengths of intravenous tubing between 80 cm and 200 cm were tested in combination with 16 gauge, 14 gauge and 13 gauge intravenous cannulae. The results demonstrated that the use of 3-mm-diameter infusion sets, or the inclusion of even short lengths of 3-mm tubing in an infusion system, limits the maximum flow that can be delivered through a cannula of size 16 gauge or larger. The reduced performance of the 3-mm tubing makes administration systems incorporating even short lengths of this diameter of tubing unsuitable in emergency situations and locations where rapid infusion of fluids is vital.

Cross, G D

1987-01-01

384

Comparison of ozone simulations using MM5 and CALMET/MM5 hybrid meteorological fields for the July/August 2000 CCOS episode  

NASA Astrophysics Data System (ADS)

Two sets of meteorological fields were prepared for the July/August 2000 Central California Ozone Study (CCOS) episode. The first set was generated using the MM5 prognostic model. The second set was generated using the CALMET model in which the MM5-generated output was used as the initial guess field and objective analysis was used to improve agreement between simulated fields and observed air temperatures and wind speed components. The resulting CALMET/MM5 hybrid meteorological fields and those generated using MM5 alone were also used as inputs for the CAMx/SAPRC99 air quality model to simulation ozone concentrations for the July/August 2000 episode. Ozone concentrations simulated using the CALMET meteorological inputs resulted in better agreement with observed concentrations than those simulated using the MM5 generated inputs throughout the modeling domain. This analysis suggested that hybrid meteorological fields, developed by merging the results of objective analysis and prognostic models, can improve episodic air quality model performance over using prognostic meteorological fields alone.

Jackson, Bruce; Chau, Daniel; Gurer, Kemal; Kaduwela, Ajith

385

The implementation of a fast and accurate QM\\/MM potential method in Amber  

Microsoft Academic Search

Version 9 of the Amber simulation programs includes a new semi-empirical hybrid QM\\/MM functional- ity. This includes support for implicit solvent (generalized Born) and for periodic explicit solvent simulations using a newly developed QM\\/MM implementation of the particle mesh Ewald (PME) method. The code provides suffi- ciently accurate gradients to run constant energy QM\\/MM MD simulations for many nanoseconds. The

Ross C. Walker; Michael F. Crowley; David A. Case

2008-01-01

386

Novel thin bronchoscope with a 1.7-mm working channel for peripheral pulmonary lesions  

Microsoft Academic Search

In the present study, the authors evaluated the diagnostic utility of a novel thin bronchoscope with a 1.7-mm working channel for peripheral pulmonary lesions. A total of 118 patients were included in this prospective study. Bronchoscopic examination was performed using a 5.9-mm standard bronchoscope. If no visible endobronchial lesion was found, transbronchial biopsies were performed with 1.5-mm biopsy forceps under

M. Oki; H. Saka; C. Kitagawa; S. Tanaka; T. Shimokata; K. Mori; S. Kajikawa

2008-01-01

387

Mustang 3.3 mm Continuum Observations of Class 0 Protostars  

NASA Astrophysics Data System (ADS)

We present observations of six Class 0 protostars at 3.3 mm (90 GHz) using the 64 pixel MUSTANG bolometer camera on the 100 m Green Bank Telescope. The 3.3 mm photometry is analyzed along with shorter wavelength observations to derive spectral indices (S ? vprop ??) of the measured emission. We utilize previously published dust continuum radiative transfer models to estimate the characteristic dust temperature within the central beam of our observations. We present constraints on the millimeter dust opacity index ? between 0.862 mm, 1.25 mm, and 3.3 mm. ? mm typically ranges from 1.0 to 2.4 for Class 0 sources. The relative contributions from disk emission and envelope emission are estimated at 3.3 mm. L483 is found to have negligible disk emission at 3.3 mm, while L1527 is dominated by disk emission within the central beam. The ?disk mm <= 0.8-1.4 for L1527 indicates that grain growth is likely occurring in the disk. The photometry presented in this paper may be combined with future interferometric observations of Class 0 envelopes and disks.

Shirley, Yancy L.; Mason, Brian S.; Mangum, Jeffrey G.; Bolin, David E.; Devlin, Mark J.; Dicker, Simon R.; Korngut, Phillip M.

2011-02-01

388

Conventional metrizamide myelography (MM) and computed tomographic metrizamide myelography (CTMM) in scoliosis: a comparative study  

SciTech Connect

A retrospective examination was performed to assess the accuracy of metrizamide myelography (MM) and computed tomographic metrizamide myelography (CTMM) in scoliosis. Of 81 consecutive scoliotic children studied by myelography, 30 had only MM while the remaining 51 had CTMM immediately afterward. CTMM added esential diagnostic information in 13 cases of dysraphism and 4 cases, both methods gave the same imformation. The outhors conclude that in patients with severe scoliosis, dysraphism, and scoliosis with localized neurological disturbances, CTMM should always be added to MM or be the only examination; while in idiopathic scoliosis with vague neurological disturbances a survey of the entire spine is essential, preferably with MM.

Pettersson, H.; Harwood-Nash, D.C.; Fitz, C.R.; Chuang, H.S.; Armstrong, E.

1982-01-01

389

ADIFOR working note No. 11: ADIFOR strategies related to POINTER usage in MM5  

SciTech Connect

POINTERs are nonstandard Fortran statements which cannot be processed by ADIFOR. We are interested in generating derivative code for MM5, a mesoscale model code which uses POINTERs extensively and in a particular structured manner. We briefly report on POINTERs and their role in MM5 and, for their particular usage in MM5, describe the three-step code transformation scheme consisting of pre-ADIFOR, ADIFOR, and post-ADIFOR transformations that result in the generation of correct derivative code for MM5.

Bischof, C.; Khademi, P.; Knauff, T.

1994-03-01

390

pH and Peptide Supply Can Radically Alter Bacterial Populations and Short-Chain Fatty Acid Ratios within Microbial Communities from the Human Colon  

PubMed Central

The effects of changes in the gut environment upon the human colonic microbiota are poorly understood. The response of human fecal microbial communities from two donors to alterations in pH (5.5 or 6.5) and peptides (0.6 or 0.1%) was studied here in anaerobic continuous cultures supplied with a mixed carbohydrate source. Final butyrate concentrations were markedly higher at pH 5.5 (0.6% peptide mean, 24.9 mM; 0.1% peptide mean, 13.8 mM) than at pH 6.5 (0.6% peptide mean, 5.3 mM; 0.1% peptide mean, 7.6 mM). At pH 5.5 and 0.6% peptide input, a high butyrate production coincided with decreasing acetate concentrations. The highest propionate concentrations (mean, 20.6 mM) occurred at pH 6.5 and 0.6% peptide input. In parallel, major bacterial groups were monitored by using fluorescence in situ hybridization with a panel of specific 16S rRNA probes. Bacteroides levels increased from ca. 20 to 75% of total eubacteria after a shift from pH 5.5 to 6.5, at 0.6% peptide, coinciding with high propionate formation. Conversely, populations of the butyrate-producing Roseburia group were highest (11 to 19%) at pH 5.5 but fell at pH 6.5, a finding that correlates with butyrate formation. When tested in batch culture, three Bacteroides species grew well at pH 6.7 but poorly at pH 5.5, which is consistent with the behavior observed for the mixed community. Two Roseburia isolates grew equally well at pH 6.7 and 5.5. These findings suggest that a lowering of pH resulting from substrate fermentation in the colon may boost butyrate production and populations of butyrate-producing bacteria, while at the same time curtailing the growth of Bacteroides spp.

Walker, Alan W.; Duncan, Sylvia H.; McWilliam Leitch, E. Carol; Child, Matthew W.; Flint, Harry J.

2005-01-01

391

Electronic Absorption Spectra from MM and ab initio QM/MM Molecular Dynamics: Environmental Effects on the Absorption Spectrum of Photoactive Yellow Protein  

PubMed Central

We describe a new interface of the GPU parallelized TeraChem electronic structure package and the Amber molecular dynamics package for quantum mechanical (QM) and mixed QM and molecular mechanical (MM) molecular dynamics simulations. This QM/MM interface is used for computation of the absorption spectra of the photoactive yellow protein (PYP) chromophore in vacuum, aqueous solution, and protein environments. The computed excitation energies of PYP require a very large QM region (hundreds of atoms) covalently bonded to the chromophore in order to achieve agreement with calculations that treat the entire protein quantum mechanically. We also show that 40 or more surrounding water molecules must be included in the QM region in order to obtain converged excitation energies of the solvated PYP chromophore. These results indicate that large QM regions (with hundreds of atoms) are a necessity in QM/MM calculations.

Isborn, Christine M.; Gotz, Andreas W.; Clark, Matthew A.; Walker, Ross C.; Martinez, Todd J.

2012-01-01

392

Electronic Absorption Spectra from MM and ab initio QM/MM Molecular Dynamics: Environmental Effects on the Absorption Spectrum of Photoactive Yellow Protein.  

PubMed

We describe a new interface of the GPU parallelized TeraChem electronic structure package and the Amber molecular dynamics package for quantum mechanical (QM) and mixed QM and molecular mechanical (MM) molecular dynamics simulations. This QM/MM interface is used for computation of the absorption spectra of the photoactive yellow protein (PYP) chromophore in vacuum, aqueous solution, and protein environments. The computed excitation energies of PYP require a very large QM region (hundreds of atoms) covalently bonded to the chromophore in order to achieve agreement with calculations that treat the entire protein quantum mechanically. We also show that 40 or more surrounding water molecules must be included in the QM region in order to obtain converged excitation energies of the solvated PYP chromophore. These results indicate that large QM regions (with hundreds of atoms) are a necessity in QM/MM calculations. PMID:23476156

Isborn, Christine M; Götz, Andreas W; Clark, Matthew A; Walker, Ross C; Martínez, Todd J

2012-12-01

393

The effects of intracellular pH changes on resting cytosolic calcium in voltage-clamped snail neurones  

PubMed Central

We have investigated the effects of changing intracellular pH on intracellular free calcium concentration ([Ca2+]i) in voltage-clamped neurones of the snail Helix aspersa. Intracellular pH (pHi) was measured using the fluorescent dye 8-hydroxypyrene-1,3,6-trisulphonic acid (HPTS) and changed using weak acids and weak bases. Changes in [Ca2+]i were recorded using either fura-2 or calcium-sensitive microelectrodes. Acidification of the neurones with 5 mM or 20 mM propionate (?0.2 or 0.3 pH units acidification, respectively) caused a small reduction in resting [Ca2+]i of 5 ± 2 nM (n = 4) and 7 ± 16 nM (n = 4), respectively. The removal of the 20 mM propionate after ?40 min superfusion resulted in an alkalinization of ?0.35 pH units and an accompanying rise in resting [Ca2+]i of 31 ± 9 nM (n = 4, P < 0.05). The removal of 5 mM propionate did not significantly affect [Ca2+]i. Alkalinizations of ?0.2-0.4 pH units of Helix neurones induced by superfusion with 3 mM concentrations of the weak bases trimethylamine (TMA), ammonium chloride (NH4Cl) and procaine were accompanied by significant (P < 0.05) increases in resting [Ca2+]i of 42 ± 4 nM (n = 26), 30 ± 7 nM (n = 5) and 36 ± 4 nM (n = 3), respectively. The effect of TMA (0.5-6 mM) on [Ca2+]i was dose dependent with an increase in [Ca2+]i during pHi increases of less than 0.1 pH units (0.5 mM TMA). Superfusion of neurones with zero calcium (1 mM EGTA) Ringer solution inhibited depolarization-induced calcium increases but not the calcium increase produced by the first exposure to TMA (3 mM). In the prolonged absence of extracellular calcium (?50 min) TMA-induced calcium rises were decreased by 64 ± 10% compared to those seen in the presence of external calcium (P < 0.05). The calcium rise induced by TMA (3 mM) was reduced by 60 ± 5% following a 10 min period of superfusion with caffeine (10 mM) to deplete the endoplasmic reticulum (ER) stores of calcium (P < 0.05). Cyclopiazonic acid (10-30 ?M CPA), an inhibitor of the ER calcium pump, inhibited the calcium rise produced by TMA (3 mM) and NH4Cl (3 mM) by 61 ± 4% compared to controls (P < 0.05). These data are consistent with physiological intracellular alkaline shifts stimulating release of calcium, or inhibiting re-uptake of calcium by an intracellular store. The calcium increase was much reduced following application of caffeine, treatment with CPA or prolonged removal of external calcium. Hence the ER was likely to be the source of mobilized calcium.

Willoughby, Debbie; Thomas, Roger C; Schwiening, Christof J

2001-01-01

394

Depth Penetration and Detection of pH Gradients in Biofilms by Two-Photon Excitation Microscopy  

PubMed Central

Deep microbial biofilms are a major problem in many industrial, environmental, and medical settings. Novel approaches are needed to understand the structure and metabolism of these biofilms. Two-photon excitation microscopy (TPE) and conventional confocal laser scanning microscopy (CLSM) were compared quantitatively for the ability to visualize bacteria within deep in vitro biofilms. pH gradients within these biofilms were determined by fluorescence lifetime imaging, together with TPE. A constant-depth film fermentor (CDFF) was inoculated for 8 h at 50 ml · h?1 with a defined mixed culture of 10 species of bacteria grown in continuous culture. Biofilms of fixed depths were developed in the CDFF for 10 or 11 days. The microbial compositions of the biofilms were determined by using viable counts on selective and nonselective agar media; diverse mixed-culture biofilms developed, including aerobic, facultative, and anaerobic species. TPE was able to record images four times deeper than CLSM. Importantly, in contrast to CLSM images, TPE images recorded deep within the biofilm showed no loss of contrast. The pH within the biofilms was measured directly by means of fluorescence lifetime imaging; the fluorescence decay of carboxyfluorescein was correlated with biofilm pH and was used to construct a calibration curve. pH gradients were detectable, in both the lateral and axial directions, in steady-state biofilms. When biofilms were overlaid with 14 mM sucrose for 1 h, distinct pH gradients developed. Microcolonies with pH values of below pH 3.0 were visible, in some cases adjacent to areas with a much higher pH (>5.0). TPE allowed resolution of images at significantly greater depths (as deep as 140 ?m) than were possible with CLSM. Fluorescence lifetime imaging allowed the in situ, real-time imaging of pH and the detection of sharp gradients of pH within microbial biofilms.

Vroom, Jurrien M.; De Grauw, Kees J.; Gerritsen, Hans C.; Bradshaw, David J.; Marsh, Philip D.; Watson, G. Keith; Birmingham, John J.; Allison, Clive

1999-01-01

395

Iridium oxide pH sensor for biomedical applications. Case urea-urease in real urine samples.  

PubMed

This work demonstrates the implementation of iridium oxide films (IROF) grown on silicon-based thin-film platinum microelectrodes, their utilization as a pH sensor, and their successful formatting into a urea pH sensor. In this context, Pt electrodes were fabricated on Silicon by using standard photolithography and lift-off procedures and IROF thin films were growth by a dynamic oxidation electrodeposition method (AEIROF). The AEIROF pH sensor reported showed a super-Nerstian (72.9±0.9mV/pH) response between pH 3 and 11, with residual standard deviation of both repeatability and reproducibility below 5%, and resolution of 0.03 pH units. For their application as urea pH sensors, AEIROF electrodes were reversibly modified with urease-coated magnetic microparticles (MP) using a magnet. The urea pH sensor provided fast detection of urea between 78?M and 20mM in saline solution, in sample volumes of just 50?L. The applicability to urea determination in real urine samples is discussed. PMID:22857994

Prats-Alfonso, Elisabet; Abad, Llibertat; Casañ-Pastor, Nieves; Gonzalo-Ruiz, Javier; Baldrich, Eva

2013-01-15

396

A comparison between 2.0-mm standard and 2.0-mm locking miniplates in the management of mandibular fractures  

Microsoft Academic Search

Purpose  The purpose of this clinical study was to compare effectiveness of 2.0-mm locking miniplates and screws with 2.0-mm standard\\u000a miniplates and screws in treating mandible fractures.\\u000a \\u000a \\u000a \\u000a Patients and methods  A randomized prospective study comprising of 40 samples, where 20 patients (group 1) were treated with locking plates and\\u000a 20 patients (group 2) were treated with standard miniplates. All the cases were

D. Saikrishna; Sujeeth Kumar Shetty; T. R. Marimallappa

2009-01-01

397

Bioelectricity production from food waste leachate using microbial fuel cells: effect of NaCl and pH.  

PubMed

Microbial fuel cells are a promising technology for simultaneous treatment and energy recovery from food waste leachate. This study evaluates the effects of NaCl (0-150 mM) and pH on the treatment of food waste leachate using microbial fuel cells. The food waste leachate amended with 100mM NaCl enabled the highest maximum power density (1000 mW/m(3)) and lowest internal resistance (371?). Increasing the anodic pH gradually from acidic to alkaline conditions (pH 4-9) resulted in a gradual increase in maximum power density to 9956 mW/m(3) and decrease in internal cell resistance to 35.3?. The coulombic efficiency obtained under acidic conditions was only 17.8%, but increased significantly to 60.0% and 63.4% in the neutral and alkaline pH's MFCs, respectively. Maintaining a narrow pH window (6.3-7.6) was essential for efficient bioelectricity production and COD removal using microbial fuel cells for the treatment of food waste leachate. PMID:24140849

Li, Xiao Min; Cheng, Ka Yu; Wong, Jonathan W C

2013-12-01

398

Product Improvement Test of Cartridges, 5.56-mm, Assembled with Steel Cartridge Cases.  

National Technical Information Service (NTIS)

The purpose of the test was to determine suitability of the 5.56-mm steel-cased cartridges to replace standard brass-cased cartridges, and to determine the physical and technical characteristics of the 5.56-mm steel-cased cartridges. Specific test phases ...

L. J. Regan M. L. Kuczinski

1970-01-01

399

Two-mm-wavelength superheterodyne modulation radiometer with a Josephson frequency converter at the input  

NASA Astrophysics Data System (ADS)

The paper reports the successful field testing of a 2-mm-wavelength superheterodyne modulation radiometer with Josephson frequency converter on the RT-25x2 IPF radio telescope. The design and basic characteristics of the radiometer are summarized. Results were obtained that make it possible to refine values of solar brightness temperature at 2 mm.

Abliazov, V. S.; Andreev, S. A.; Vystavkin, A. N.; Gubankov, V. N.; Diakov, V. P.; Zhukov, A. I.; Kisliakov, A. G.; Rulev, K. A.; Tarasov, M. A.; Turygin, S. Iu.

1981-01-01

400

Development of the Solar Active Region 2684 at 8 mm Wavelength, September 22 - 27, 1980.  

National Technical Information Service (NTIS)

Results of the daily monitoring of the solar active region 2684 at 8mm wavelength using a 14m millimeter wave radiotelescope, are discussed. An increase in 8mm radiation to the value of 8 Sfu, and its subsequent rapid decay, are noted. Eight maps of the w...

S. Urpo

1981-01-01

401

Optical mm-wave generation by using external modulator based on optical carrier suppression  

Microsoft Academic Search

In this paper, we have theoretically investigated the transmission performance of the optical millimeter (mm)-wave generated by using an external modulator based on optical carrier suppression for the first time. According to our theory, the data signals carried by the optical mm-wave are transmitted in the dispersion fiber without fading but are degraded greatly because of the time shift of

Jianxin Ma; Chongxiu Yu; Zhen Zhou; Jianjun Yu

2006-01-01

402

296 lead fine pitch (0.4 mm) thin plastic QFP package with TAB interconnect  

Microsoft Academic Search

The quad flat pack (QFP) package has become the surface mount technology (SMT) package of choice for microprocessors and peripheral devices and is well suited for hand held computer application. To address this market segment Intel has developed a new package with a thin (2.0 mm) body for light weight, low standoff (0.25 mm maximum) for overall lower profile, in

Praveen Jain

1995-01-01

403

120mm M830A1 Heat Round Wear Life Prediction.  

National Technical Information Service (NTIS)

A wear life prediction is given for the US Army's M830A1 HEAT round used in the 120mm M256 & XM360 cannons. Five predictions are required and provided for the fielding of the 120mm FCS MCS gun system. Four of these predictions are for the hot, basic ambie...

S. Sopok

2009-01-01

404

[Sequence-specific interaction of pyrimidine oligonucleotides with double-stranded DNA at acidic pH complexes of different types].  

PubMed

The interaction of pyrimidine oligonucleotides (OLN(15) and OLN(6)) and their alkylating derivatives bearing 4-(3-amino)-N-methyl and N-2-chloroethyl (RCl) aniline residues at the 5'-phosphate with a fragment of the human gamma-interferon gene was studied. In the presence of 150 mM NaCl at pH 5.4, the yield of dsDNA alkylation was 60% for RCl-OLN(15) and 10% for RCl-OLN(6); at pH 4.0 in the presence of 150 mM NaCl and 10 mM MgCl2, the yield of the dsDNA modification product was 100% for RCl-OLN(6) and 50% for RCl-OLN(15). It was shown by native electrophoresis that OLN(15) could form with the target dsDNA complexes of two types in the presence of magnesium ions at pH 4.0. One of the complexes was stable at pH 5.4 in the presence of magnesium ions, whereas the other was not. We found that only the complex stable in 10 mM Mg(OAc)2, pH 5.4, was effectively alkylated. PMID:19915644

Brossalina, E B; Demchenko, E N; Demchenko, Iu N; Vlassov, V V

2009-01-01

405

Barium recovery by crystallization in a fluidized-bed reactor: effects of pH, Ba/P molar ratio and seed.  

PubMed

The effects of process conditions, including upward velocity inside the column, the amount of added seed and seed size, the pH value of the precipitant or the phosphate stream and the Ba/P molar ratio in a fluidized-bed reactor (FBR) were studied with a view to producing BaHPO? crystals of significant size and maximize the removal of barium. XRD were used to identify the products that were collected from the FBR. Experimental results show that an upward velocity of 48 cmmin(-1) produced the largest BaHPO? crystals with a size of around 0.84-1.0mm. The addition of seed crystals has no effect on barium removal. The use of a seed of a size in the ranges unseeded<0.149-0.29 mm<0.149 mm<0.29-0.42 mm produced increasing amounts of increasingly large crystals. The largest BaHPO? crystals were obtained at pH 8.4-8.8 with a Ba/P molar ratio of 1.0. In the homogeneous and heterogeneous processes, around 98% of barium was removed at pH 8.4-8.6 and [Ba]/[P]=1.0. The XRD results show that a significant amount of barium phosphate (Ba?(PO?)?) was obtained at pH 11. The compounds BaHPO? and BaO were present at a pH of below 10. PMID:24462085

Su, Chia-Chi; Reano, Resmond L; Dalida, Maria Lourdes P; Lu, Ming-Chun

2014-06-01

406

Application of quartz crystal microbalance to study the impact of pH and ionic strength on protein-silicone oil interactions.  

PubMed

In this study, we have used quartz crystal microbalance (QCM) to quantitate the adsorption of a protein on silicone oil coated surfaces as a function of protein concentration, pH and ionic strength using a 5 MHz quartz crystal. Protein adsorption isotherms were generated at different solution pH and ionic strengths. Surface saturation concentrations were selected from adsorption isotherms and used to generate adsorption profiles from pH 3.0 to 9.0, and at ionic strengths of 10 mM and 150 mM. At low ionic strength (10mM) and pH 5.0 (close to the isoelectric point of the protein), maximum adsorption of protein to the silicone oil surface was observed. At higher ionic strength (150 mM), no significant pH influence on adsorption was observed. QCM could be used as a reliable technique to study the binding of proteins to silicone oil coated surfaces. PMID:21497645

Dixit, Nitin; Maloney, Kevin M; Kalonia, Devendra S

2011-06-30

407

PhET Simulation: Reactions & Rates  

NSDL National Science Digital Library

This applet is designed for study of the kinetics of chemical reactions. It uses a model gas of three atomic species to illustrate the formation and disassociation of the different possible diatomic molecules. The user can run experiments with either one of each atom type or a gas of many atoms, controlling the density of the various species, the temperature, and energetics of the reaction. Data collection tools are available to calculate rate coefficients. Tips for teachers, ideas and activities are included. The direct link to the simulation is given as a mirror URL. This is part of a larger collection developed by the Physics Education Technology project (PhET).

2008-11-03

408

77 FR 75850 - Regulated Navigation Area; Upper Mississippi River MM 0.0 to MM 185.0; Cairo, IL to St. Louis, MO  

Federal Register 2010, 2011, 2012, 2013

...USCG-2012-1044] RIN 1625-AA11 Regulated Navigation Area; Upper Mississippi River MM 0...is establishing a temporary regulated navigation area (RNA) for all waters of the Upper...Industry Action Committee RNA Regulated Navigation Area UMR Upper Mississippi River...

2012-12-26

409

Validation of 2-mm Tissue Microarray Technology in Gastric Cancer. Agreement of 2-mm TMAs and Full Sections for Glut-1 and Hif-1 Alpha.  

PubMed

Background/Aim: Tissue Microarray (TMA) is a widely used method to perform high-throughput immunohistochemical analyses on different tissues by arraying small sample cores from paraffin-fixed tissues into a single paraffin block. TMA-technology has been validated on numerous cancer tissues and also for gastric cancer studies, although it has not been validated for this tumor tissue so far. The objective of this study was to assess, whether the 2-mm TMA-technology is able to provide representative samples of gastric cancer tissue. Materials and Methods: TMA paraffin blocks were constructed by means of 220 formalin-fixed and paraffin-embedded gastric cancer samples with a sample diameter of 2 mm. The agreement of immunohistochemical stainings of Glut-1 and Hif-1 alpha in TMA sections and the original full sections was calculated using kappa statistics and direct adjustment. Results: The congruence was substantial for Glut-1 (kappa 0.64) and Hif-1 alpha (kappa 0.70), but with an agreement of only 71% and 52% within the marker-positive cases of the full-section slides. Conclusion: Due to tumor heterogeneity primarily, the TMA technology with a 2-mm sample core shows relevant limitations in gastric cancer tissue. Although being helpful for tissue screening purposes, the 2-mm TMA technology cannot be recommended as a method equal to full-section investigations in gastric cancer. PMID:24982335

Berlth, Felix; Mönig, Stefan P; Schlösser, Hans A; Maus, Martin; Baltin, Christoph T H; Urbanski, Alexander; Drebber, Uta; Bollschweiler, Elfriede; Hölscher, Arnulf H; Alakus, Hakan

2014-07-01

410

Effectiveness of 2.0 mm Standard and 2.0 mm Locking Miniplates in Management of Mandibular Fractures: A Clinical Comparative Study.  

PubMed

To compare and evaluate the effectiveness of 2.0 mm locking miniplates versus 2.0 mm standard miniplates in treatment of mandible fractures. Sixty randomly selected patients who sustained mandibular fractures were selected for this study. The fractured fragments were stabilized using 2.0 mm locking miniplates in 30 cases and in the remaining 30 cases the fractured fragments were fixed with conventional 2.0 mm miniplates. Post-operative stability was assessed with radiographs at 7th day, 1st, and 3rd months. The stability of the reduced fracture was assessed clinically and both the types of plates were assessed with an OPG or conventional radiographs. This study shows favorable results on use of locking miniplates in mandibular fractures. The results show that there were no significant differences in the post-operative complications between the conventional and the locking plate/screw mandibular systems. The locking plate/screw system was more rigid than conventional plate/screw system, thereby reducing the need and duration of intermaxillary fixation (IMF). PMID:24644396

Shaik, Mahaboob; Subba Raju, T; Rao, N Koteswara; Reddy, Chandra Kiran

2014-03-01

411

Development of Controlled-Rolled 70 kgf/mm(2) and 80 kgf/mm(2) Class High Tensile Strength Steel Plate for Weld Structure.  

National Technical Information Service (NTIS)

To meet demands for higher strength steel plates for construcion machines with excellent cold formability and weldability, as-rolled HT70 steel plates (TS: 686 MPa) having a maximum thickness of 25.4 mm and as-rolled HT80 (TS: 784 MPa) steel plates of 12....

K. Amano O. Tanigawa C. Shiga T. Okumura

1989-01-01

412

Tetraphenylborate doped polyaniline based novel pH sensor and solid-state urea biosensor.  

PubMed

A novel pH sensor suitable for use in both aqueous and non-aqueous mediums is reported. The sensor is derived from polymer modified electrode obtained from electrochemical polymerisation of aniline in dry acetonitrile containing 0.5 M tetraphenyl borate at 2.0 V versus Ag/AgCl. The light yellow colour polymer modified electrode obtained under the present experimental condition has been characterised by scanning electron microscopy (SEM). The pH sensing of polymer modified electrode in both aqueous and non-aqueous mediums is examined and reported. As the typical examples, we used weak acid (acetic acid) and weak base (ammonium hydroxide) as analytes. The acetic acid is analysed in both aqueous and dry acetonitrile whereas ammonium hydroxide is analysed only in aqueous medium. The analysis in aqueous medium is conducted in 1 mM Tris-HCl buffer pH 7.0 and also in 0.1 M KCl. The slope of pH sensing is calculated from the data recorded in typical buffers and found to be approximately 86 mV per pH. The application of polymer modified electrode for the construction of urea biosensor is described based on immobilised urease within poly vinyl alcohol (PVA) matrix and also within organically modified sol-gel glass on the surface of polymer-modified electrode. The new urea sensor has shown maximum response of 160 mV at 25 degrees C with a lowest detection limit of 20 muM. The performance of new pH sensor and urea sensor has been studied and reported in this communication. PMID:18968424

Pandey, P C; Singh, G

2001-10-31

413

Porcine oocyte activation: differing roles of calcium and pH.  

PubMed

Intracellular pH has recently been shown to increase during parthenogenetic activation of the porcine oocyte. In the following set of experiments, intracellular pH was monitored during activation and pronuclear development was assessed following activation treatments with calcium, in the absence of calcium, and in oocytes loaded with the calcium chelator BAPTA-AM in calcium-free medium. Intracellular pH increase was not different among groups when treating with 7% ethanol or 50 microM calcium ionophore, or during treatment with thimerosal for 12 or 25 min. Activation with thimerosal (200 microM, 12 min) followed by 8 mM dithiothreitol (DTT, 30 min) resulted in a decreased pronuclear development in calcium-free medium with or without BAPTA-AM loaded oocytes as compared to controls. Activation with 50 microM calcium ionophore resulted in pronuclear development that was different between the calcium-free and BAPTA-AM loaded oocytes in calcium-free medium. Similar incidences of pronuclear formation were observed in all ethanol treatment groups. It was concluded that external calcium as well as large changes in intracellular free calcium are not necessary for the increase in intracellular pH, but normal intracellular calcium signaling is critical for normal levels of pronuclear development. Finally, oocytes were measured for intracellular pH changes for 30 min following subzonal sperm injection. Intracellular pH did not increase, although pronuclear formation was observed 6 hr post SUZI. This suggested that major differences were still present between sperm-induced and parthenogenetic activation of the porcine oocyte. PMID:11389559

Ruddock, N T; Macháty, Z; Cabot, R A; Prather, R S

2001-06-01

414

Design of the multilayer insulation system for the Superconducting Super Collider 50mm dipole cryostat  

SciTech Connect

The development of the multilayer insulation (MLI) system for the Superconducting Super Collider (SSC) 50 mm collider dipole cryostat is an ongoing extension of work conducted during the 40 mm cryostat program. While the basic design of the MLI system for the 50 mm cryostat resembles that of the 40 mm cryostat, results from measurements of MLI thermal performance below 80K have prompted a re-design of the MLI system for the 20K thermal radiation shield. Presented is the design of the MLI system for the 50 mm collider dipole cryostat, with discussion focusing on system performance, blanket geometry, cost-effective fabrication techniques, and built-in quality control measures that assure consistent thermal performance throughout the SSC accelerator. 16 refs., 8 figs., 2 tabs.

Boroski, W.N.; Nicol, T.H.; Schoo, C.J.

1991-03-01

415

Effect of postweld heat treatment on weld metal impact toughness of a semi-austenitic PH stainless steel  

SciTech Connect

Semi-austenitic precipitation hardened PH stainless steel plates, PH 15-7 Mo (Cu), 6.14 mm thick were autogenously welded using the electron beam welding (EBW) and plasma arc welding (PAW) processes. Impact toughness studies using Charpy V-notch samples (V-notch at the center of the weld metal) showed that EB welds had higher impact toughness than PA welds in various identical postweld heat treated (PWHT) conditions. Based on hardness and impact toughness values, the optimal postweld heat treated conditions are recommended. The effect of retained austenite, carbides and delta ferrite on impact toughness of the welds are discussed.

Sivaramakrishnan, N.; Raja, K.S.; Prasad Rao, K. (Indian Inst. of Tech., Madras (India). Dept. of Metallurgical Engineering)

1994-08-01

416

Nanoparticle assembled microcapsules for application as pH and ammonia sensor.  

PubMed

The encapsulation of molecular probes in a suitable nanostructured matrix can be exploited to alter their optical properties and robustness for fabricating efficient chemical sensors. Despite high sensitivity, simplicity, selectivity and cost effectiveness, the photo-destruction and photo-bleaching are the serious concerns while utilizing molecular probes. Herein we demonstrate that hydroxy pyrene trisulfonate (HPTS), a pH sensitive molecular probe, when encapsulated in a microcapsule structure prepared via the assembly of silica nanoparticles mediated by poly-L-lysine and trisodium citrate, provides a robust sensing material for pH sensing under the physiological conditions. The temporal evolution under continuous irradiation indicates that the fluorophore inside the silica microcapsule is extraordinarily photostable. The fluorescence intensity alternation at dual excitation facilitates for a ratiometic sensing of the pH, however, the fluorescence lifetime is insensitive to hydrogen ion concentration. The sensing scheme is found to be robust, fast and simple for the measurement of pH in the range 5.8-8.0, and can be successfully applied for the determination of ammonia in the concentration range 0-1.2 mM, which is important for aquatic life and the environment. PMID:22093347

Amali, Arlin Jose; Awwad, Nour H; Rana, Rohit Kumar; Patra, Digambara

2011-12-01

417

Hydrogen-bond network and pH sensitivity in human transthyretin  

PubMed Central

Transthyretin (TTR) is a tetrameric protein. TTR misfolding and aggregation are associated with human amyloid diseases. Dissociation of the TTR tetramer is believed to be the rate-limiting step in the amyloid fibril formation cascade. Low pH is known to promote dissociation into monomer and the formation of amyloid fibrils. In order to reveal the molecular mechanisms underlying pH sensitivity and structural stabilities of TTR, neutron diffraction studies were conducted using the IBARAKI Biological Crystal Diffractometer with the time-of-flight method. Crystals for the neutron diffraction experiments were grown up to 2.5?mm3 for four months. The neutron crystal structure solved at 2.0?Å revealed the protonation states of His88 and the detailed hydrogen-bond network depending on the protonation states of His88. This hydrogen-bond network is involved in monomer–monomer and dimer–dimer interactions, suggesting that the double protonation of His88 by acidification breaks the hydrogen-bond network and causes the destabilization of the TTR tetramer. Structural comparison with the X-ray crystal structure at acidic pH identified the three amino acid residues responsible for the pH sensitivity of TTR. Our neutron model provides insights into the molecular stability related to amyloidosis.

Yokoyama, Takeshi; Mizuguchi, Mineyuki; Nabeshima, Yuko; Kusaka, Katsuhiro; Yamada, Taro; Hosoya, Takaaki; Ohhara, Takashi; Kurihara, Kazuo; Tanaka, Ichiro; Niimura, Nobuo

2013-01-01

418

Effect of pH on the accumulation kinetics of pentachlorophenol in goldfish  

USGS Publications Warehouse

The kinetics of accumulation of pentachlorophenol (PCP) at various pH values were investigated to explore how pH-dependent accumulation might influence PCP toxicity. Goldfish (Carassius auratus ) were exposed to 5 mu g PCP/L in a static system buffered with 7.5 mM bicine or N,N-bis(2-hydroxyethyl)-2-aminoethane sulfonic acid (BES) at pH 7.0, 8.0, or 9.0. The amount of PCP in the fish, concentration of PCP in water, and the total amount of metabolites in the system were measured after exposure of fish from 1 to 96 hr. The distribution of PCP within the fish was altered by changes in the external pH. The pH-associated changes in distribution may have altered access of PCP to sites of metabolism, thereby altering the metabolic clearance. The pH-related changes in the pharmacokinetics of PCP resulted in a decrease in its bioconcentration factor with an increase in pH and account both for the decreased capacity of the fish to accumulated PCP and for its reduced LC50.

Stehly, G. R.; Hayton, W. L.

1990-01-01

419

Conformational states of sunflower (Helianthus annuus) Helianthinin: effect of heat and pH.  

PubMed

The structure and solubility of helianthinin, the most abundant protein of sunflower seeds, was investigated as a function of pH and temperature. Dissociation of the 11S form (hexamer) into the 7S form (trimer) gradually increased with increasing pH from 5.8 to 9.0. High ionic strength (I = 250 mM) stabilizes the 11S form at pH > 7.0. Heating and low pH resulted in dissociation into the monomeric constituents (2-3S). Next, the 7S and 11S forms of helianthinin were isolated and shown to differ in their secondary and tertiary structure, and to have denaturation temperatures (T(d)) of 65 and 90 degrees C, respectively. Furthermore, the existence of two populations of the monomeric form of helianthinin with denaturation temperatures of 65 and 90 degrees C was described. This leads to the hypothesis that helianthinin can adopt two different conformational states: one with T(d) = 65 degrees C and a second with T(d) = 90 degrees C. PMID:15506815

González-Pérez, Sergio; Vereijken, Johan M; Merck, Karin B; van Koningsveld, Gerrit A; Gruppen, Harry; Voragen, Alphons G J

2004-11-01

420

PhET Simulation: Balancing Chemical Equations  

NSDL National Science Digital Library

This simulation provides practice for beginners in balancing chemical equations. Introductory activities include separating a water molecule and making ammonia (a compound composed of sodium and hydrogen). The user clicks up or down arrows to add/delete atoms, while bar charts and balance scales are displayed to show when the equation is in balance. Next, apply what you've learned and play the "Balancing Game", with three levels of difficulty. Editor's Note: The game-like nature of this activity not only gives students practice with chemical equations, but goes much deeper. By viewing the distribution of individual atoms in real-time charts alongside the equation, the learner is building a basis to understand conservation of matter and chemical interactions. See Related Materials for a link to downloadable lessons and student guides developed specifically for use with this PhET simulation. This item is part of a larger collection of simulations developed by the Physics Education Technology project (PhET).

2011-08-15

421

The pH of Mars  

NASA Technical Reports Server (NTRS)

The Viking labeled release (LR) experiments provided data that can be used to determine the acid-base characteristics of the regolith. Constraints on the acid-base properties and redox potentials of the Martian surface material would provide additional information for determining what reactions are possible and defining formation conditions for the regolith. Calculations devised to determine the pH of Mars must include the amount of soluble acid species or base species present in the LR regolith sample and the solubility product of the carbonate with the limiting solubility. This analysis shows that CaCO3, either as calcite or aragonite, has the correct K(sub sp) to have produced the Viking LR successive injection reabsorption effects. Thus CaCO3 or another MeCO3 with very similar solubility characteristics must have been present on Mars. A small amount of soluble acid, but no more than 4 micro-mol per sample, could also have been present. It is concluded that the pH of the regolith is 7.2 +/- 0.1.

Plumb, R. C.; Bishop, J. L.; Edwards, J. O.

1993-01-01

422

Influence of cation type, ionic strength, and pH on solubilization and mobilization of residual hydrocarbon by a biosurfactant  

NASA Astrophysics Data System (ADS)

This study investigated the effect of cation type, ionic strength, and pH on the performance of an anionic monorhamnolipid biosurfactant for solubilization and removal of residual hexadecane from sand. Three common soil cations, Na +, Mg 2+, and Ca 2+, were used in these experiments and hexadecane was chosen to represent a nonaqueous phase liquid (NAPL) less dense than water. Results showed that hexadecane solubility in rhamnolipid solution was significantly increased by the addition of Na + and Mg 2+. Addition of up to 0.2 mM Ca 2+ also increased hexadecane solubility. For Ca 2+ concentrations greater than 0.2 mM there was little effect on hexadecane solubility due to competing effects of calcium-induced rhamnolipid precipitation and enhanced hexadecane solubilization. Efficiency of NAPL solubilization can be expressed in terms of molar solubilization ratios (MSR). The results showed that MSR values for hexadecane in rhamnolipid solutions increased 7.5-fold in the presence of 500 mM Na +, and 25-fold in the presence of 1 mM Mg 2+. The presence of cations also reduced the interfacial tension between rhamnolipid solutions and hexadecane. For example, an increase in Na + from 0 to 800 mM caused a decrease in interfacial tension from 2.2 to 0.89 dyn cm -1. Similarly, decreasing pH caused a reduction in interfacial tension. The lowest interfacial tension value observed in this study was 0.02 dyn cm -1 at pH 6 in the presence of 320 mM Na +. These conditions were also found to be optimal for removal of hexadecane residual from sand columns, with 58% of residual removed within three pore volumes. The removal of residual NAPL from the packed columns was primarily by mobilization, even though solubilization was significantly increased in the presence of Na +.

Bai, Guiyun; Brusseau, Mark L.; Miller, Raina M.

423

Interstitial PCO2 and pH, and their role as chemostimulants in the isolated respiratory network of neonatal rats.  

PubMed Central

1. CO2-H(+)-sensitive microelectrodes were used for simultaneous measurements of the partial pressure of CO2 (PCO2) and extracellular pH (pHo) in the ventral respiratory group (VRG) of the isolated brainstem-spinal cord of neonatal rats. Some of the data were analysed using diffusion equations. 2. With increasing recording depth within the boundaries of the VRG (300-600 microns below the tissue surface), PCO2 increased from 77 to 95 mmHg and pHo fell from 7.0 to 6.8 at steady state in standard saline equilibrated with 5% CO2 and 95% O2. 3. Elevating bath CO2 from 5 to 10-12.5% produced a mean increase in PCO2 of 18 mmHg, a fall in pHo of 0.13 pH units, and a 50-250% increase in the frequency of respiration-related spinal (C2) nerve bursts. Similar effects on C2 activity and pHo were observed upon lowering bath [HCO3-] from 25 to 10 mM, leading to a mean decrease in PCO2 of 4.4 mmHg in the VRG. 4. Raising bath [HCO3-] to 50 mM produced a substantial frequency decrease, a rise in pHo of 0.24 pH units and an elevation in PCO2 of 9.3 mmHg. C2 activity was not profoundly affected upon doubling the CO2-HCO3- content, leading to a mean increase in pHo of 0.13 pH units and elevation of PCO2 by 30 mmHg. 5. In a CO2-HCO3(-)-free, Hepes-buffered solution, PCO2 decreased to 18 mmHg in the VRG and pHo fell by 0.15 pH units with no major effect on rhythmic activity. Subsequent anoxic exposure for more than 15 min produced a further fall in PCO2 to below 1 mmHg, a decrease in pHo of 0.55 pH units, and blockade of respiration-related activity. In three out of the six preparations tested, C2 activity could be restored by reapplication of CO2-HCO3- in the absence of O2. 6. C2 activity persisted at a reduced frequency, even up to 30 min, during anoxia in the CO2-HCO(-)-buffered saline,leading to an elevation in PCO2 of 15 mmHg and a fall in pHo of 0.18 pH units. 7. The diffusion coefficient of CO2 in the tissue was found to be equal to that in saline. Two mean estimates for anoxic tissue of the function lambda 2/ alpha of tortuosity (lambda) and extracellular volume fraction (alpha), affecting extracellular diffusion of bicarbonate, were 4.7 and 4.1. The mean rate of acid production by anoxic tissue was 1.1 mequiv 1-1 min-1. 8. The results suggest that extracellular H+ is the primary stimulating factor in central chemosensitivity, which may often mask the less evident effects of CO2. A model of diffusion of acid equivalents in brain tissue is proposed. Images Figure 2

Voipio, J; Ballanyi, K

1997-01-01

424

Effects of external calcium concentration and pH on charge movement in frog skeletal muscle.  

PubMed Central

1. The effects of both external Ca2+ (1.8, 25, 50 and 100 mM) and external pH (pH 5.5, 7.15, and 9.0) on the voltage-dependence of charge movement in frog skeletal muscle were examined using the three intracellular micro-electrode voltage-clamp technique. 2. The two-state model of Schneider & Chandler (1973) was used to describe the voltage distribution of membrane charge. The parameters of this model are: Qmax, the maximum quantity of charge; V, the potential of equal distribution of charge; and k, a constant relating to the steepness of the charge vs. voltage relationship. 3. In 1.8 mM external Ca2+, alterations, in external pH shifted the transition potential, V, from a mean +/- S.E. of mean of -36.5 +/- 0.9 mV at pH 7.15 to -25.8 +/- 1.3 mV at pH 5.5 and to -42.5 +/- 1.8 mV at pH 9.0. These shifts are consistent with surface charge theory. No significant changes in Qmax or k were observed over the range of pH 5.5--9.0. 4. A reasonable fit of surface charge theory to the shifts in V over the range pH 5.5--9.0 could be obtained with surface charge densities and binding constants: sigma 1 = -1 e/165 A2, pK1 = 3.9 and sigma 2 = -1 e/400 A2, pK2 = 8. 5. However, at pH 7.15, both V and k changed with increasing external Ca2+ concentration. V shifted from -34.9 +/- 3.7 mV in 1.8 mM-Ca2+ to -13.8 +/- 5.1 mV, -19.3 +/- 3.6 mV and 3.3 +/- 9.3 mV in 25, 50 and 100 mM-Ca2+ respectively. k increased from 8.3 +/- 0.6 mV in 1.8 mM-Ca2+ to 15.3 +/- 1.4 mV, 14.6 +/- 1.6 mV and 20.0 +/- 2.9 mV in 25, 50 and 100 mM-Ca2+. Changes in k reflect decreases in the apparent charged particle valence from approximately 3 in 1.8 mM-Ca2+ to approximately 1.2 in 100 mM-Ca2+. As the external Ca2+ concentration was raised, Qmax was at least as large as that measured in 1.8 mM-Ca2+. The 43% decrease in the apparent valence of the charged groups cannot be explained by simple surface charge theory and may reflect a specific interaction between external Ca2+ and the charged groups. 6. Shifts in V with alterations in external pH and Ca2+ concentration are consistent with the effects of these agents on the contraction threshold of muscle fibres. This observation lends further support to the hypothesis that the charge movement is involved in gating muscle contraction and that the charged particles respond to changes in the electric field across the muscle cell membrane. 7. No difference was observed in the charge movement parameters of fibres from both room-temperature and cold-adapted frog tested at 2--5 degrees C in 1.8 mM-Ca2+ at pH 7.15. Images Fig. 1 Fig. 4 Fig. 5 Fig. 6

Shlevin, H H

1979-01-01

425

Regulation of the intracellular pH in the protozoan parasite Trypanosoma brucei brucei.  

PubMed

The mechanisms regulating the intracellular pH (pHi) in both forms of Trypanosoma brucei brucei (cultured cells) were investigated using the fluorescent probe 2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein (BCECF). The pHi values measured were 7.22+/-0.03 in the procyclics and 7.40+/-0.05 in the bloodstream form. In the presence of 24mM HCO3-, pHi values were slightly higher in both forms of trypanosomes suggesting a bicarbonate-linked pH regulation. pHi was more stable in procyclics (between 7.15 and 7.30 in the external pH range 6.4-7.6) than in the bloodstream forms. The amiloride analogue tested decreased pHi, suggesting Na+-driven Na+/H+ antiporters. H+-ATPases also seem to be involved in pHi regulation since the inhibitors N-ethylmaleimide (1 mM) and N,N'-dicyclohexylcarbodiimide (80 microM) induced a rapid acidification in both forms of trypanosomes. Addition of pyruvate caused a cytosol acidification in the bloodstream form only confirming the existence of a diffusion-facilitated carrier for pyruvate, with the cotransport of H+. Our results show that, although similar pH regulation mechanisms seem to exist in both forms of trypanosomes, the procyclics can regulate efficiently their pHi and consequently their plasma membrane potential whereas the bloodstream forms cannot always maintain their pHi and are easily depolarized following a small acid load. PMID:9348114

Fraser-L'Hostis, C; Defrise-Quertain, F; Coral, D; Deshusses, J

1997-09-01

426

Day-to-night variations of cytoplasmic pH in a crassulacean acid metabolism plant.  

PubMed

In crassulacean acid metabolism (CAM) large amounts of malic acid are redistributed between vacuole and cytoplasm in the course of night-to-day transitions. The corresponding changes of the cytoplasmic pH (pHcyt) were monitored in mesophyll protoplasts from the CAM plant Kalanchoe daigremontiana Hamet et Perrier by ratiometric fluorimetry with the fluorescent dye 2',7'-bis-(2-carboxyethyl)-5-(and-6-)carboxyfluorescein as a pHcyt indicator. At the beginning of the light phase, pHcyt was slightly alkaline (about 7.5). It dropped during midday by about 0.3 pH units before recovering again in the late-day-to-early-dark phase. In the physiological context the variation in pHcyt may be a component of CAM regulation. Due to its pH sensitivity, phosphoenolpyruvate carboxylase appears as a likely target enzyme. From monitoring delta pHcyt in response to loading the cytoplasm with the weak acid salt K-acetate a cytoplasmic H(+)-buffer capacity in the order of 65 mM H+ per pH unit was estimated at a pHcyt of about 7.5. With this value, an acid load of the cytoplasm by about 10 mM malic acid can be estimated as the cause of the observed drop in pHcyt. A diurnal oscillation in pHcyt and a quantitatively similar cytoplasmic malic acid is predicted from an established mathematical model which allows simulation of the CAM dynamics. The similarity of model predictions and experimental data supports the view put forward in this model that a phase transition of the tonoplast is an essential functional element in CAM dynamics. PMID:11732184

Hafke, J B; Neff, R; Hütt, M T; Lüttge, U; Thiel, G

2001-01-01

427

CRCHD - CRCHD Research - Principal Investigator: Bruce Macher, Ph.D.  

Cancer.gov

CRCHD - CRCHD Research - Principal Investigator: Bruce Macher, Ph.D. Home Disparities Research Programs CRCHD Ongoing Research PACHE PACHE Partnership Listing Bruce Macher, Ph.D. CRCHD Research Ongoing Research

428

CRCHD - CRCHD Research - Principal Investigator: Bruce Macher, Ph.D.  

Cancer.gov

CRCHD - CRCHD Research - Principal Investigator: Bruce Macher, Ph.D. Home Health Disparities Research CRCHD Research Ongoing Research PACHE PACHE Partnership Listing Bruce Macher, Ph.D. CRCHD Research Ongoing

429

Catalytic Decomposition of PH3 on Heated Tungsten Wire Surfaces  

NASA Astrophysics Data System (ADS)

The catalytic decomposition processes of PH3 on heated tungsten surfaces were studied to clarify the mechanisms governing phosphorus doping into silicon substrates. Mass spectrometric measurements show that PH3 can be decomposed by more than 50% over 2000 K. H, P, PH, and PH2 radicals were identified by laser spectroscopic techniques. Absolute density measurements of these radical species, as well as their PH3 flow rate dependence, show that the major products on the catalyst surfaces are P and H atoms, while PH and PH2 are produced in secondary processes in the gas phase. In other words, catalytic decomposition, unlike plasma decomposition processes, can be a clean source of P atoms, which can be the only major dopant precursors. In the presence of an excess amount of H2, the apparent decomposition efficiency is small. This can be explained by rapid cyclic reactions including decomposition, deposition, and etching to reproduce PH3.

Umemoto, Hironobu; Nishihara, Yushin; Ishikawa, Takuma; Yamamoto, Shingo

2012-08-01

430

Benefits of smaller electrode surface area (4 mm2) on steroid-eluting leads.  

PubMed

The purpose was to test whether a reduction of pacemaker electrode surface area below 8 mm2 improves leads that elute steroid from the electrode tip to the surrounding myocardium. A standard-sized 8 mm2 lead with 1 mg dexamethasone was implanted in 12 patients and a lead with 4 mm2 electrode surface area and 0.5 mg dexamethasone in ten patients. Pacing threshold, impedance, and sensing threshold were measured at implantation and after 1, 4, and 12 weeks. Pacing thresholds were similar for both groups and were always less than or equal to 0.8 V at 0.5 msec pulse duration in all patients. Impedance was significantly higher (P less than 0.05) for the 4 mm2 lead (implantation: 726 +/- 119 ohms; 1 week: 596 +/- 71 ohms; 4 weeks: 624 +/- 68 ohms; 12 weeks: 643 +/- 56 ohms) than for the 8 mm2 lead (implantation: 422 +/- 43 ohms; 1 week: 402 +/- 48 ohms; 4 weeks: 439 +/- 57 ohms; 12 weeks: 449 +/- 61 ohms). R wave amplitudes did not differ between both groups; no sensing failure occurred at 5 mV sensitivity. Compared to the 8 mm2 lead the reduction of surface area to 4 mm2 did not influence pacing threshold, but resulted in a higher pacing impedance. The amount of pacing energy was lower in the smaller-sized electrode. For clinical impact, low pacing threshold and high impedance leads are the condition to implant pulse generators with smaller battery capacity. PMID:1723192

Schuchert, A; Kuck, K H

1991-12-01

431

Contributions of Pauli repulsions to the energetics and physical properties computed in QM/MM methods.  

PubMed

Conventional combined quantum mechanical/molecular mechanical (QM/MM) methods lack explicit treatment of Pauli repulsions between the quantum-mechanical and molecular-mechanical subsystems. Instead, classical Lennard-Jones (LJ) potentials between QM and MM nuclei are used to model electronic Pauli repulsion and long-range London dispersion, despite the fact that the latter two are inherently of quantum nature. Use of the simple LJ potential in QM/MM methods can reproduce minimal geometries and energies of many molecular clusters reasonably well, as compared to full QM calculations. However, we show here that the LJ potential cannot correctly describe subtle details of the electron density of the QM subsystem because of the neglect of Pauli repulsions between the QM and MM subsystems. The inaccurate electron density subsequently affects the calculation of electronic and magnetic properties of the QM subsystem. To explicitly consider Pauli interactions with QM/MM methods, we propose a method to use empirical effective potentials on the MM atoms. The test case of the binding energy and magnetic properties of a water dimer shows promising results for the general application of effective potentials to mimic Pauli repulsions in QM/MM calculations. PMID:23922165

Jin, Yingdi; Johnson, Erin R; Hu, Xiangqian; Yang, Weitao; Hu, Hao

2013-10-15

432

Pioneering breakthroughs in implant monitor wafer cost reduction at 300 mm  

NASA Astrophysics Data System (ADS)

The semiconductor industry has been full of news regarding the transition to 300 mm wafers. In 1998, SEMICONDUCTOR300 (SC300) was the first to demonstrate the capability to produce integrated products on 300 mm wafers. To meet the challenge of maintaining quality while simultaneously reducing cost and ramping SC300 into pilot manufacturing, the authors have investigated the use of an overlay implant technique. A single 300 mm wafer is used to collect particle, high dose, and low dose information from a Eaton GSD HE-3 ion implanter. The implants, a high dose As+ 80 KeV 3E14 followed by a low dose As+ 60 KeV 3E11 damage implant, are measured using a KLA/Tencor Rs100 sheet resistance measurement tool with a 3 mm edge exclusion. In addition to verifying the technique at 300 mm, the paper presents overlay implant data collected using externally reclaimed wafers, currently one third the cost of prime 300 mm wafers, and explores the possibility of reusing implanted monitor wafers by re-annealing the wafers and repeating the low dose damage implant. Initial data is also presented for implants performed on the backside of 300 mm wafers.

Zeakes, Jason S.; Breeden, Terry A.

1999-08-01

433

Including explicit water molecules as part of the protein structure in MM/PBSA calculations.  

PubMed

Water is the natural medium of molecules in the cell and plays an important role in protein structure, function and interaction with small molecule ligands. However, the widely used molecular mechanics Poisson-Boltzmann surface area (MM/PBSA) method for binding energy calculation does not explicitly take account of water molecules that mediate key protein-ligand interactions. We have developed a protocol to include water molecules that mediate ligand-protein interactions as part of the protein structure in calculation of MM/PBSA binding energies (a method we refer to as water-MM/PBSA) for a series of JNK3 kinase inhibitors. Improved correlation between water-MM/PBSA binding energies and experimental IC50 values was obtained compared to that obtained from classical MM/PBSA binding energy. This improved correlation was further validated using sets of neuraminidase and avidin inhibitors. The observed improvement, however, appears to be limited to systems in which there are water-mediated ligand-protein hydrogen bond interactions. We conclude that the water-MM/PBSA method performs better than classical MM/PBSA in predicting binding affinities when water molecules play a direct role in mediating ligand-protein hydrogen bond interactions. PMID:24432790

Zhu, Yong-Liang; Beroza, Paul; Artis, Dean R

2014-02-24

434

The Herschel Multi-Tiered Extragalactic Survey: SPIRE-mm Photometric Redshifts  

NASA Technical Reports Server (NTRS)

We investigate the potential of submm-mm and submm-mm-radio photometric redshifts using a sample of mm-selected sources as seen at 250, 350 and 500 micron by the SPIRE instrument on Herschel. From a sample of 63 previously identified mm sources with reliable radio identifications in the Great Observatories Origins Deep Survey North and Lockman Hole North fields, 46 (73 per cent) are found to have detections in at least one SPIRE band. We explore the observed submm/mm color evolution with redshift, finding that the colors of mm sources are adequately described by a modified blackbody with constant optical depth Tau = (Nu/nu(sub 0))(exp Beta), where Beta = +1.8 and nu(sub 0) = c/100 micron. We find a tight correlation between dust temperature and IR luminosity. Using a single model of the dust temperature and IR luminosity relation, we derive photometric redshift estimates for the 46 SPIRE-detected mm sources. Testing against the 22 sources with known spectroscopic or good quality optical/near-IR photometric redshifts, we find submm/mm photometric redshifts offer a redshift accuracy of (absolute value of Delta sub (z))/(1 + z) = 0.16 (absolute value of Delta sub (z)) = 0.51). Including constraints from the radio-far-IR correlation, the accuracy is improved to (absolute value of Delta sub (z))/(1 + z) = 0.14 (((absolute value of Delta sub (z))) = 0.45). We estimate the redshift distribution of mm-selected sources finding a significant excess at Z > 3 when compared to approx 8S0 micron selected samples.

Roseboom, I. G.; Ivison, R. J.; Greve, T. R.; Amblard, A.; Arumugam, V.; Auld, R.; Aussel, H.; Bethermin, M.; Blain, A.; Block, J.; Boselli, A.; Brisbin, D.; Buat, V.; Burgarella, D.; Castro-Rodriquez, N.; Cava, A.; Chanial, P.; Chapin, E.; Chapman, S.; Clements, D. L.; Conley, A.; Conversi, L.; Dowell, C. D.; Dunlop, J. S.; Dwek, E.

2012-01-01

435

Intracellular pH, intracellular free Ca, and junctional cell-cell coupling  

Microsoft Academic Search

Summary Intracellular pH (pHi) and intracellular Ca2+ ([Ca2+]i) were determined inChironomus salivary gland cells under various conditions of induced uncoupling. pHi was measured with aThomas-type microelectrode, changes in [Ca2+]i and their spatial distribution inside the cell were determined with the aid of intracellularly injected aequorin and an image intensifier-TV system, and cell-to-cell coupling was measured electrically. Treatments with NaCN (5mm),

Birgit Rose; Roger Rick

1978-01-01

436

The Influence of pH on the Oxygen Isotope Composition of Calcium Carbonate  

NASA Astrophysics Data System (ADS)

Oxygen isotope fractionation between calcium carbonate and water is temperature-dependent and can therefore be used as a paleothermometer. Although oxygen isotope fractionation is expected from principles of equilibrium isotopic partitioning, the temperature-dependence remains uncertain because other factors, such as slow exchange between dissolved inorganic carbon (DIC) species and water, can obscure the temperature signal. Oxygen isotopic equilibrium between aqueous solution and calcium carbonate includes two distinct equilibria: equilibrium of the DIC species in solution (i.e., CO2(aq), H2CO3, HCO3-, and CO32-) with water, and equilibrium between the dissolved inorganic carbon with the precipitated carbonate. To isolate kinetic isotope effects that arise at the mineral-solution interface, isotopic equilibrium among DIC species must be maintained. This can be accomplished by dissolving the enzyme carbonic anhydrase (CA) into the solution, thereby reducing the time required for isotopic equilibration between DIC species by approximately two orders of magnitude between pH 7.7 and 9.3. We conduct calcite growth experiments aimed specifically at measuring the pH-dependence of kinetic oxygen isotope effects during precipitation of calcite. We precipitated calcite from aqueous solution at a constant pH and controlled supersaturation over the pH range 7.7-9.3. For each experiment, a gas mixture of N2 and CO2 is constantly bubbled through a beaker containing ~1300 mL of solution (30 mM CaCl2 + 5 mM NH4Cl + 0.1 mM SrCl2). As CO2 from the gas dissolves into solution, calcite crystals grow on the beaker walls. The pH of the solution is maintained by use of an autotitrator with NaOH as the titrant. We control the temperature, pH, the pCO2 of the gas inflow, and the gas inflow rate, and monitor the total alkalinity, the pCO2 of the gas outflow, and the amount of NaOH added. A constant crystal growth rate of ~1.6 mmol/m2/hr is maintained over all experiments. We will present results from this set of experiments and discuss kinetic oxygen isotope effects in the context of a recently-developed ion-by-ion growth model of calcite.

Hunt, J. D.; Watkins, J. M.; Ryerson, F. J.; DePaolo, D. J.

2013-12-01

437

Putting the pH into phosphatidic acid signaling  

PubMed Central

The lipid phosphatidic acid (PA) has important roles in cell signaling and metabolic regulation in all organisms. New evidence indicates that PA also has an unprecedented role as a pH biosensor, coupling changes in pH to intracellular signaling pathways. pH sensing is a property of the phosphomonoester headgroup of PA. A number of other potent signaling lipids also contain headgroups with phosphomonoesters, implying that pH sensing by lipids may be widespread in biology.

2011-01-01

438

Use and abuse of pH measurements  

Microsoft Academic Search

The development of the concept of pH from its invention by Sorenson in 1909 to the present-day National Bureau of Standards' pH scale is reviewed. The liquid junction potential problem involved in the use of the pH meter is discussed in detail. The magnitude of the error due to the junction potential depends upon the pH, ionic strength, nature of

Isaac Feldman

1956-01-01

439

New Routes to the PhD: Cause for Concern?  

ERIC Educational Resources Information Center

Recent developments suggest that the PhD is at a turning point. Professional groups have criticised the so-called traditional PhD. New routes to the PhD are proposed by several bodies and endorsed by one funding council. In light of these developments, it is appropriate to ask what the implications are for the PhD and for the academy. A focus…

Johnston, Bill; Murray, Rowena

2004-01-01

440

Organelle pH in the Arabidopsis endomembrane system.  

PubMed

The pH of intracellular compartments is essential for the viability of cells. Despite its relevance, little is known about the pH of these compartments. To measure pH in vivo, we have first generated two pH sensors by combining the improved-solubility feature of solubility-modified green fluorescent protein (GFP) (smGFP) with the pH-sensing capability of the pHluorins and codon optimized for expression in Arabidopsis. PEpHluorin (plant-solubility-modified ecliptic pHluorin) gradually loses fluorescence as pH is lowered with fluorescence vanishing at pH 6.2 and PRpHluorin (plant-solubility-modified ratiomatric pHluorin), a dual-excitation sensor, allowing for precise measurements. Compartment-specific sensors were generated by further fusing specific sorting signals to PEpHluorin and PRpHluorin. Our results show that the pH of cytosol and nucleus is similar (pH 7.3 and 7.2), while peroxisomes, mitochondrial matrix, and plastidial stroma have alkaline pH. Compartments of the secretory pathway reveal a gradual acidification, spanning from pH 7.1 in the endoplasmic reticulum (ER) to pH 5.2 in the vacuole. Surprisingly, pH in the trans-Golgi network (TGN) and multivesicular body (MVB) is, with pH 6.3 and 6.2, quite similar. The inhibition of vacuolar-type H(+)-ATPase (V-ATPase) with concanamycin A (ConcA) caused drastic increase in pH in TGN and vacuole. Overall, the PEpHluorin and PRpHluorin are excellent pH sensors for visualization and quantification of pH in vivo, respectively. PMID:23702593

Shen, Jinbo; Zeng, Yonglun; Zhuang, Xiaohong; Sun, Lei; Yao, Xiaoqiang; Pimpl, Peter; Jiang, Liwen

2013-09-01

441

MUSTANG 3.3mm Observations of Low-mass Cores  

NASA Astrophysics Data System (ADS)

We present observations of low-mass star-forming cores (L1527, L1448C, B335, L483) observed during 2009 with MUSTANG, the 3.3mm bolometer camera on the 100-m Green Bank Telescope. The 3.3mm emission may be used to constrain the fraction of emission coming from the envelope and disk. We present our initial model comparisons to observations of the dust emission surrounding the protostars. Comparison is made to interferometric observations of L1527. These observations demonstrate the feasibility of active surface observations with aperture efficiencies above 20% at 3mm with the GBT.

Shirley, Yancy L.; Mason, B. S.; Mangum, J. G.; Dicker, S. S.; Korngut, P. M.; Devlin, M. J.

2010-01-01

442

Feasibility of 1.6-mm isotropic voxel diffusion tensor tractography in depicting limbic fibers  

Microsoft Academic Search

Introduction  We attempted to assess the feasibility of a 1.6-mm isotropic voxel diffusion tensor imaging (DTI) tractography at 3T in visualizing\\u000a nerve bundles in the limbic system.\\u000a \\u000a \\u000a \\u000a Methods  We examined 20 healthy volunteers by conventional DTI with a voxel size of 1.6?×?1.6?×?3.0 mm and by high-resolution DTI with\\u000a a voxel size of 1.6?×?1.6?×?1.6 mm and generated tractographs of three limbic nerve bundles: the fornix,

Shunrou Fujiwara; Makoto Sasaki; Yoshiyuki Kanbara; Takashi Inoue; Ryonoshin Hirooka; Akira Ogawa

2008-01-01

443

A simple quantum mechanical/molecular mechanical (QM/MM) model for methanol  

NASA Astrophysics Data System (ADS)

Mixed quantum mechanical/molecular mechanical (QM/MM) models, in which one part of a system is treated at an ab initio level while the rest is described by an empirical force field, are becoming increasingly popular. In this Letter, we describe a simple QM/MM model for methanol (CH 3OH) in which the OH constitutes the ab initio region and is treated within a density functional representation, while the methyl group, the MM region, is treated using the AMBER force field. The model is used to study the structure of the bulk liquid and is shown to compare favorably with the experimental structure.

Morrone, Joseph A.; Tuckerman, Mark E.

2003-03-01

444

Radar frequency management and the new mm-wave radar operating frequencies  

NASA Astrophysics Data System (ADS)

Aspects of radar frequency management are examined, taking into account requirements that military radars must comply with the requirements of both NTIA and MIL-STD 469. Attention is given to mm-wave radar, the World Administrative Radio Conference (WARC-79) held in Geneva in the fall of 1979, and the establishment of new frequency bands for mm-wave radar. It is pointed out that the ratification in 1983, by the U.S. Senate, of the Final Acts of WARC-79 as a treaty, and promulgation of implementing U.S. regulations, has opened the door for mm-wave radar.

Johnston, S. L.

1984-12-01

445

One-to-Two Millimeter Wave Spectroscopy. V. PH3 and PD3  

Microsoft Academic Search

The J=0-->1 rotational transition of PH3 has been measured at nu0=266 944.0+\\/-1.0 Mc\\/sec (lambda=1.12 mm). With DJ=3.15 Mc\\/sec from infrared spectroscopy, this measurement yields B0=133 478.3 Mc\\/sec. Similarly, the 0-->1 transition of PD3 was measured at nu0=138 937.98+\\/-0.30 Mc\\/sec (lambda=2.16 mm) and B0=69 470.41 Mc\\/sec was obtained by using DJ=0.71 Mc\\/sec from infrared spectroscopy. The bond lengths in the two

Charles A. Burrus; Albert Jache; Walter Gordy

1954-01-01

446

Calcium release and its voltage dependence in frog cut muscle fibers equilibrated with 20 mM EGTA  

PubMed Central

Sarcoplasmic reticulum (SR) Ca release was studied at 13-16 degrees C in cut fibers (sarcomere length, 3.4-3.9 microns) mounted in a double Vaseline-gap chamber. The amplitude and duration of the action- potential stimulated free [Ca] transient were reduced by equilibration with end-pool solutions that contained 20 mM EGTA with 1.76 mM Ca and 0.63 mM phenol red, a maneuver that appeared to markedly reduce the amount of Ca complexed by troponin. A theoretical analysis shows that, under these conditions, the increase in myoplasmic free [Ca] is expected to be restricted to within a few hundred nanometers of the SR Ca release sites and to have a time course that essentially matches that of release. Furthermore, almost all of the Ca that is released from the SR is expected to be rapidly bound by EGTA and exchanged for protons with a 1:2 stoichiometry. Consequently, the time course of SR Ca release can be estimated by scaling the delta pH signal measured with phenol red by -beta/2. The value of beta, the buffering power of myoplasm, was determined in fibers equilibrated with a combination of EGTA, phenol red, and fura-2; its mean value was 22 mM/pH unit. The Ca content of the SR (expressed as myoplasmic concentration) was estimated from the total amount of Ca released by either a train of action potentials or a depleting voltage step; its mean value was 2,685 microM in the action-potential experiments and 2,544 microM in the voltage- clamp experiments. An action potential released, on average, 0.14 of the SR Ca content with a peak rate of release of approximately 5%/ms. A second action potential, elicited 20 ms later, released only 0.6 times as much Ca (expressed as a fraction of the SR content), probably because Ca inactivation of Ca release was produced by the first action potential. During a depolarizing voltage step to 60 mV, the rate of Ca release rapidly increased to a peak value of approximately 3%/ms and then decreased to a quasi-steady level that was only 0.6 times as large; this decrease was also probably due to Ca inactivation of Ca release. SR Ca release was studied with small step depolarizations that open no more than one SR Ca channel in 7,000 and increase the value of spatially averaged myoplasmic free [Ca] by only 0.2 nM.

1995-01-01

447

Can the supermassive objects at the centers of galaxies be traversable wormholes? The first test of strong gravity for mm/sub-mm very long baseline interferometry facilities  

NASA Astrophysics Data System (ADS)

The near future mm/sub-mm very long baseline interferometry experiments are ambitious projects aiming at imaging the “shadow” of the supermassive black hole candidate at the center of the Milky Way and of the ones in nearby galaxies. An accurate observation of the shape of the shadow can potentially test the nature of these objects and verify if they are Kerr black holes, as predicted by general relativity. However, previous work on the subject has shown that the shadows produced in other spacetimes are very similar to the one of the Kerr background, suggesting that tests of strong gravity are not really possible with these facilities in the near future. In this work, I instead point out that it will be relatively easy to distinguish black holes from wormholes, topologically nontrivial structures of the spacetime that might have been formed in the early Universe and might connect our Universe with other universes.

Bambi, Cosimo

2013-05-01

448

Notes on the Measurement of pH Values.  

National Technical Information Service (NTIS)

The original definition of pH is: pH = -log a(sub H). Where a(sub H) is the (relative) hydrogen ion activity. However, a single ion activity cannot be measured. Activities of individual ionic species are necessarily conventional. The pH number, of course,...

R. M. Carranza R. B. Rebak

2005-01-01

449

A Multiattributes Approach for Ranking PhD Programs  

ERIC Educational Resources Information Center

In its plan to combat the PhD shortage crisis, the Association to Advance Collegiate Schools of Business International (AACSB; 2003) has called for the development of PhD program rankings to serve as incentives for academic institutions to invest more in PhD programs, thereby counterbalancing the disproportionate influence of master of business…

Urbancic, Frank R.

2008-01-01

450

pH dynamics in sewers and its modeling.  

PubMed

pH variation in sewers has a significant effect on hydrogen sulfide production and emissions, and hence its accurate prediction is critical for the optimization of mitigation strategies. In this study, the nature and dynamics of pH variation in a sewer system is examined. Three sewer systems collecting domestic wastewater were monitored, with pH in all cases showing large diurnal variations. pH in fresh sewage in all three cases had a very similar trend with maximum pH in the range of 8.5-8.7. pH variation in fresh sewage followed the same pattern as the sewage flow rate, suggesting that sewage pH is influenced by household water use. Nitrogen content of the wastewater was found to be the most influential factor causing pH variation in fresh sewage, with the total ammonium concentration variation well correlated with the pH variation. A methodology for predicting pH variation in sewers is developed and calibration protocols proposed. The methodology, which is based on the concept of charge balance, was validated using titration curves and field pH data. Measurement of the total ammonium concentration in fresh sewage was found necessary and adequate for the calibration of the charge balance-based pH model. PMID:23962970

Sharma, Keshab; Ganigue, Ramon; Yuan, Zhiguo

2013-10-15

451

Writing your own activities - PhET Activity Guidelines  

NSDL National Science Digital Library

You can create your own lectures, homework, and labs around any PhET simulation by using the PhET Activity Guidelines . These guidelines will help you create "guided inquiry activities which encourage students to construct their own understanding," which are the most effective way to use PhET simulations.

Mckagan, Sam