Quantitative analysis of low-concentration α-HMX based on terahertz spectroscopy

2020 ◽  
Vol 12 (47) ◽  
pp. 5684-5690
Author(s):  
Zhengmin Tang ◽  
Hu Deng ◽  
Quancheng Liu ◽  
Jin Guo ◽  
Liping Shang
Keyword(s):  
Quantitative Analysis ◽  
Terahertz Spectroscopy ◽  
Crystal Form ◽  
Low Concentration ◽  
Low Concentrations

Due to the instability of α type HMX at low concentrations, it belongs to the impurity crystal form.

Quantitative analysis of direct oral anticoagulant rivaroxaban by terahertz spectroscopy

The Analyst ◽  
2020 ◽  
Vol 145 (11) ◽  
pp. 3909-3915 ◽  
Author(s):  
Xu Wu ◽  
Liping Wang ◽  
Yan Peng ◽  
Fang Wu ◽  
Jiumei Cao ◽  
...  
Keyword(s):  
Quantitative Analysis ◽  
Oral Anticoagulant ◽  
Terahertz Spectroscopy ◽  
New Method ◽  
Quantitative Detection ◽  
Direct Oral Anticoagulant ◽  
Qualitative And Quantitative

A new method for the qualitative and quantitative detection of direct oral anticoagulant rivaroxaban by terahertz spectroscopy.

scholarly journals Low Concentrations of Chlorhexidine Inhibit the Formation and Structural Integrity of Enzyme-Treated Multispecies Oral Biofilms

2021 ◽  
Vol 12 ◽  
Author(s):  
Kay Andrin Gränicher ◽  
Lamprini Karygianni ◽  
Thomas Attin ◽  
Thomas Thurnheer
Keyword(s):  
Structural Integrity ◽  
Fluorescent Dyes ◽  
Combined Treatment ◽  
Extracellular Proteins ◽  
Laser Scanning Microscopy ◽  
Extracellular Dna ◽  
Anaerobic Growth ◽  
Low Concentration ◽  
Low Concentrations ◽  
Dental Hard Tissues

The self-produced matrix of biofilms, consisting of extracellular polymeric substances, plays an important role in biofilm adhesion to surfaces and the structural integrity of biofilms. In dentistry, biofilms cause multiple diseases such as caries, periodontitis, and pulpitis. Disruption of these biofilms adhering to dental hard tissues may pose a major challenge since biofilms show higher tolerance to antimicrobials and antibiotics than planktonic cells. In this study, the effect of low concentrations of chlorhexidine (CHX) on enzyme-treated multispecies oral biofilm was investigated in an in vitro model. Six-species biofilms were enzymatically treated by anaerobic growth in a medium containing DNase I and proteinase K. Biofilms were exposed to a low concentration of CHX at defined time points. After 64h, biofilms were either harvested and quantified by cultural analyses or stained for confocal laser scanning microscopy (CLSM) analyses using either Live/Dead kit or different fluorescent dyes. A mixture of YoPro1 and SYTOX™ Green, Fluorescent Brightener 28 (Calcofluor), and SYPRO™ Ruby Protein Gel Stain was used to stain total DNA, exopolysaccharides, and extracellular proteins, respectively. Extracellular DNA (eDNA) was visualized via an indirect immunofluorescence assay (Mouse anti-DNA IgG, Goat anti-Mouse IgG, Streptavidin-Cy3). Overall, the total colony-forming units significantly decreased after combined treatment with a low concentration of CHX and enzymes compared to the group treated with CHX alone (p<0.001). These findings also apply to five species individually (Streptococcus mutans, Streptococcus oralis, Actinomyces oris, Veillonella dispar, and Candida albicans) occurring in the biofilms, with Fusobacterium nucleatum being the only exception. Furthermore, CLSM images showed less dense biofilms and a reduction in cell numbers after combined treatment compared to the group without enzymes. The combination of enzymes capable of disturbing the matrix integrity with antimicrobial agents thus appears to be a promising approach for biofilm disruption and killing.

Transepithelial movement of calcium in crustaceans

1993 ◽  
Vol 184 (1) ◽  
pp. 1-16 ◽  
Author(s):  
D. S. Neufeld ◽  
J. N. Cameron
Keyword(s):  
Active Transport ◽  
Calcium Concentration ◽  
Cellular Mechanism ◽  
The Body ◽  
High Rate ◽  
Calcium Flux ◽  
Moult Cycle ◽  
Electrochemical Gradient ◽  
Low Concentration ◽  
Low Concentrations

The regulation of calcium in most crustaceans is especially challenging owing to the highly mineralized cuticle that must be recalcified after each moult, a process that often occurs in environments with low concentrations of calcium. The gill and carapace epithelia separate the major calcium-containing compartments of the body and therefore see large changes in the rate of calcium flux through the moult cycle. Large changes in the ultrastructure of these cells do not, however, correlate well with the periods of calcium movement and probably reflect other physiological events. Despite the challenges to regulating calcium levels at various acclimation salinities and moult stages, the calcium concentration in the blood is maintained relatively constant. There is a rapid increase to a high rate of calcium flux across both the gill and carapace epithelium shortly after the moult; on an area-specific basis these fluxes are among the highest reported for calcium-transporting epithelia. When in water with a very low concentration of calcium, the electrochemical gradient for calcium is directed outwards and net influx must occur by active transport. Evidence suggests that changes in the electrochemical gradient, permeability and active transport are all important in the ability of crustaceans to take up calcium from water with a low concentration of this ion. Although an enzyme transporter is presumably involved in the active transport of calcium across epithelia, very little is known about the cellular mechanism of the transepithelial movement of calcium in crustaceans.

PIXE Analysis for Drainage from a Radioisotope Laboratory

1998 ◽  
Vol 08 (01) ◽  
pp. 57-67 ◽  
Author(s):  
Y. TAKAHASHI ◽  
H. YAMAZAKI ◽  
K. ISHII ◽  
S. MATSUYAMA ◽  
T. SATO ◽  
...  
Keyword(s):  
Quantitative Analysis ◽  
Internal Standard ◽  
Good Sensitivity ◽  
Pixe Analysis ◽  
Low Concentration ◽  
Uranium Ions ◽  
Polycarbonate Film ◽  
Mev Protons ◽  
Concentration Limits

PIXE technique has been applied to quantitative analysis of thorium and uranium ions in drainage from a radioisotope laboratory of Tohoku University. Two kinds of targets were prepared and analyzed with an in-air vertical PIXE system of 3 MeV protons. The concentrations of thorium and uranium higher than 40 ppb were easily determined by 3-μC irradiation on targets which are made from a 0.12-ml solution containing Ga-internal standard evaporated on a hand-made polycarbonate film. Uranium(VI) ions in a 25-ml sample were preconcentrated into a thin uniform target containing Zr or Pd as an internal standard by means of dibenzyldithiocarbamate complexation with subsequent condensation into dibenzylidene-D-sorbitol gels, and low concentration of 10 ppb was precisely determined by PIXE measurement. This method does not work for concentrating thorium ions. The PIXE analysis for these two kinds of targets has good sensitivity and precision enough to determine concentrations of thorium and uranium lower than their permissible concentration limits in drainage from a radioisotope laboratory.

The temperature variation of diamagnetic susceptibility

1954 ◽  
Vol 222 (1149) ◽  
pp. 239-253 ◽  
Keyword(s):  
Magnetic Properties ◽  
Fermi Surface ◽  
Temperature Variation ◽  
Diamagnetic Susceptibility ◽  
Experimental Results ◽  
Temperature Dependent ◽  
Constant Energy ◽  
Low Concentration ◽  
Low Concentrations ◽  
Theoretical Results

The temperature variation of a major contribution to the diamagnetic susceptibility of orbital electrons is calculated for various forms of the surfaces of constant energy in the neighbourhood of the Fermi surface in k space. Both quadratic and non-quadratic ϵ , k relations are considered. A discussion is given of the theoretical results in relation to the relevant experimental results and, in particular, in relation to the complicated variations of susceptibility with ( a ) temperature and ( b ) concentration for alloys of bismuth with low concentrations of added lead and tellurium. It is shown that the treatment provides a basis for a simple and direct correlation of the temperature-dependent and concentration-dependent magnetic properties for low-concentration diamagnetic alloy sequences.

scholarly journals Antibiotic-resistantEscherichia coliin market pigs in 1956–1979: the emergence of organisms with plasmid-borne trimethoprim resistance

1980 ◽  
Vol 84 (3) ◽  
pp. 467-477 ◽  
Author(s):  
H. Williams Smith
Keyword(s):  
Escherichia Coli ◽  
Antibiotic Resistance ◽  
Considerable Proportion ◽  
Low Concentration ◽  
E Coli ◽  
Low Concentrations

SUMMARYSurveys conducted since 1956 on the antibiotic resistance of theEscherichia coliin faecal specimens from pigs entering Chelmsford Market have revealed that despite the implementation of the Swann Report in 1971 pigs are still an enormous reservior of tetracycline-resistantE. coliwith conjugative ability.Increasingly large amounts ofE. coliresistant to streptomycin and sulphonamides were found in specimens examined in recent years unitl in 1979 the amounts present approached those of tetracycline-resistant organisms.E. coliresistant to chloramphenicol, ampicillin, neomycin, furazolidone or spectinomycin were present, usually in low concentration, in a considerable proportion of the specimens at each yearly examination but the concentration and incidence of these organisms showed no obvious sign of increasing with time. Much of this resistance, except to furazolidone, was of the transferable type.Until 1979 the incidence of faecal specimens containing trimethoprim-resistantE. coliwas very low. It increased significantly in that year, most of the resistance being plasmid-, or possibly transposon-determined.The result of surveys performed in a Cambridgeshire market in 1978 and 1979, which showed that a high proportion of faecal specimens contained low concentrations of trimethoprim-resistantE. coli, in general resembled those of the corresponding Chelmsford surveys, suggesting that all the Chelmsford surveys may have accurately reflected the position in the national pig herd.

Acquiring reproducible fluorescence spectra of dissolved organic matter at very low concentrations

2009 ◽  
Vol 60 (6) ◽  
pp. 1385-1392 ◽  
Author(s):  
B. R. H. Peiris ◽  
H. Budman ◽  
C. Moresoli ◽  
R. L. Legge
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
High Concentration ◽  
Low Concentration ◽  
Low Concentrations ◽  
Fibre Optic Probe ◽  
On Line ◽  
Optic Probe ◽  
Membrane Treatment ◽  
Concentration Levels

A method that would allow for fast and reliable measurements of dissolved organic matter (DOM), both at low and high concentration levels would be a valuable tool for online monitoring of DOM. This could have applications in a variety of areas including membrane treatment systems for drinking water applications which is of interest to our group. In this study, the feasibility of using fluorescence spectroscopy for monitoring DOM at very low concentration levels was demonstrated with an emphasis on optimizing the instrument parameters necessary to obtain reproducible fluorescence signals. Signals were acquired using a cuvette or a fibre optic probe assembly, the latter which may have applications for on-line or in-line monitoring. The instrument parameters such as photomultiplier tube (PMT) voltage, scanning rate and slit width were studied in detail to find the optimum parameter settings required. The results showed that larger excitation and emission slit widths were preferred, over larger PMT voltage or lower scanning rates, to obtain reproducible and rapid measurements when measuring very low concentration levels of DOM. However, this approach should be implemented with caution to avoid any reduction of the signal resolution.

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