scholarly journals Broadband and High‐Sensitivity Time‐Resolved THz System Using Grating‐Assisted Tilted‐Pulse‐Front Phase Matching

2021 ◽  
pp. 2101136
Author(s):  
Wei Cui ◽  
Kashif Masud Awan ◽  
Rupert Huber ◽  
Ksenia Dolgaleva ◽  
Jean‐Michel Ménard
Keyword(s):  
High Sensitivity ◽  
Phase Matching ◽  
Pulse Front ◽  
Time Resolved

scholarly journals Effects of Crystal Morphology on the Hot-Carrier Dynamics in Mixed-Cation Hybrid Lead Halide Perovskites

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 708
Author(s):  
Daniele Catone ◽  
Giuseppe Ammirati ◽  
Patrick O’Keeffe ◽  
Faustino Martelli ◽  
Lorenzo Di Mario ◽  
...  
Keyword(s):  
High Sensitivity ◽  
Carrier Dynamics ◽  
Large Area ◽  
Photovoltaic Properties ◽  
Time Resolved ◽  
Hot Carrier ◽  
Mixed Cation ◽  
Small Crystals ◽  
Characterization Of Materials ◽  
Lead Halide

Ultrafast pump-probe spectroscopies have proved to be an important tool for the investigation of charge carriers dynamics in perovskite materials providing crucial information on the dynamics of the excited carriers, and fundamental in the development of new devices with tailored photovoltaic properties. Fast transient absorbance spectroscopy on mixed-cation hybrid lead halide perovskite samples was used to investigate how the dimensions and the morphology of the perovskite crystals embedded in the capping (large crystals) and mesoporous (small crystals) layers affect the hot-carrier dynamics in the first hundreds of femtoseconds as a function of the excitation energy. The comparative study between samples with perovskite deposited on substrates with and without the mesoporous layer has shown how the small crystals preserve the temperature of the carriers for a longer period after the excitation than the large crystals. This study showed how the high sensitivity of the time-resolved spectroscopies in discriminating the transient response due to the different morphology of the crystals embedded in the layers of the same sample can be applied in the general characterization of materials to be used in solar cell devices and large area modules, providing further and valuable information for the optimization and enhancement of stability and efficiency in the power conversion of new perovskite-based devices.

Urinary gonadotropin measurements by enhanced luminometric assays (LIA) for the evaluation of pubertal development

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
And Demir ◽  
Adem Aydın ◽  
Atilla Büyükgebiz ◽  
Ulf-Håkan Stenman ◽  
Matti Hero
Keyword(s):  
Healthy Subjects ◽  
Reliable Method ◽  
Pubertal Development ◽  
High Sensitivity ◽  
Tanner Stage ◽  
Time Resolved ◽  
Stage 1 ◽  
Sensitive Detection Technique ◽  
Serum And Urine

Abstract Objectives Determination of LH in urine has proved to be a reliable method for evaluation of pubertal development. The human LH assay based on time-resolved immunofluorometric (IFMA) technology (AutoDELFIA, PerkinElmer, Wallac) has been found to be suitable for this purpose thanks to its high sensitivity but other assays have not been evaluated. We have analyzed our data obtained by another potentially sensitive detection technique, enhanced luminometric assay (LIA) with the objective of finding a viable alternative to IFMA since these may not be available in the future. Methods LIA was used to measure LH and FSH in serum and urine samples from 100 healthy subjects of each Tanner stage and both genders, whose pubertal development has been determined. Results Urinary gonodotropin concentrations measured by LIA correlated well with Tanner stage [(r=0.93 for girls, r=0.81 for boys; p<0.01 for LH) and (r=0.81 for girls, r=0.73 for boys; p<0.01 for FSH)]. LIA determinations revealed the increase in U-LH concentrations during the transition from Tanner stage 1–2 in both girls and boys (p<0.001), whereas U-FSH and S-LH were able to detect the increase from Tanner stage 1–2 only in boys or girls, respectively (both p<0.001). Conclusions Measurement of urinary gonadotropin concentrations by LIA may be useful for the evaluation of overall pubertal development and also in the detection of transition from prepuberty to puberty.

Time-Resolved Magnetic Resonance Angiography for Follow-Up of Treated Dural and Epidural Spinal Arteriovenous Fistula

2021 ◽  
Author(s):  
Giovanni Giulio Vercelli ◽  
Fabrizio Venturi ◽  
Massimiliano Minardi ◽  
Fabio Cofano ◽  
Francesco Zenga ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Magnetic Resonance Angiography ◽  
Vascular Malformations ◽  
High Sensitivity ◽  
Recurrence Time ◽  
Venous Plexus ◽  
Time Resolved ◽  
Arteriovenous Fistulas ◽  
Spinal Arteriovenous Fistula

Abstract Background Spinal arteriovenous fistulas (AVFs) are uncommon vascular malformations of spinal dural and epidural vessels. Actually digital subtraction angiography (DSA) is the gold standard for diagnosis and follow-up. The aim of this study is to demonstrate the validity of the multiphasic magnetic resonance angiography (MRA) to identify recurrent/residual AVFs or their correct surgical and/or endovascular closure. Methods A retrospective cases series with perimedullary venous plexus congestion due to spinal dural or epidural AVF was performed at our center from April 2014 to September 2019. After 1 month from treatment, the patients were subjected to time-resolved MRA and DSA to demonstrate recurrence or correct closure of AVFs. Results We collected a series of 26 matched time-resolved MRA and DSA in 20 patients who underwent an endovascular and/or surgical procedure. In our series, we reported five cases of recurrence. Time-resolved MRA detected six cases of recurrence, with 100% sensitivity and 95% specificity (p < 0.001). We used DSA as the standard reference. Conclusion Time-resolved MRA is a valid tool in posttreatment follow-up to detect recurrent or residual AVFs. It has high sensitivity and specificity and may replace DSA.

New Methods for Time-resolved Fluorescence Spectroscopy Data Analysis Based on the Laguerre Expansion Technique

2007 ◽  
Vol 46 (02) ◽  
pp. 206-211 ◽  
Author(s):  
L. Marcu ◽  
Q. Fang ◽  
T. Papaioannou ◽  
J. Qiao ◽  
M. Fishbein ◽  
...  
Keyword(s):  
Fluorescence Spectroscopy ◽  
Fluorescence Emission ◽  
High Sensitivity ◽  
Inflammatory Cells ◽  
Time Resolved ◽  
Laguerre Expansion ◽  
Tissue Diagnosis ◽  
Expansion Technique ◽  
Laguerre Basis

Summary Objectives : A new deconvolution method for the analysis of time-resolved laser-induced fluorescence spectroscopy (TR-LIFS) data is introduced and applied for tissue diagnosis. Method : The intrinsic TR-LIFS decays are expanded on a Laguerre basis, and the computed Laguerre expansion coefficients (LEC) are used to characterize the sample fluorescence emission. The method was applied for the diagnosis of atherosclerotic vulnerable plaques. Results : At a first stage, using a rabbit atherosclerotic model, 73 TR-LIFS in-vivo measurements from the normal and atherosclerotic aorta segments of eight rabbits were taken. The Laguerre deconvolution technique was able to accurately deconvolve the TR-LIFS measurements. More interesting, the LEC reflected the changes in the arterial biochemical composition and provided discrimination of lesions rich in macrophages/foamcells with high sensitivity (> 85%) and specificity (> 95%). At a second stage, 348 TR-LIFS measurements were obtained from the explanted carotid arteries of 30 patients. Lesions with significant inflammatory cells (macrophages/foam-cells and lymphocytes) were detected with high sensitivity (> 80%) and specificity (> 90%), using LEC-based classifiers. Conclusion : This study has demonstrated the potential of using TR-LIFS information by means of LEC for in- vivo tissue diagnosis, and specifically for detecting inflammation in atherosclerotic lesions, a key marker of plaque vulnerability.

scholarly journals Elucidation of a PTS–Carbohydrate Chemotactic Signal Pathway inEscherichia coliUsing a Time-resolved Behavioral Assay

1999 ◽  
Vol 10 (4) ◽  
pp. 1133-1146 ◽  
Author(s):  
Renate Lux ◽  
V. Ranjit N. Munasinghe ◽  
Fred Castellano ◽  
Joseph W. Lengeler ◽  
John E. T. Corrie ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Response Regulator ◽  
High Sensitivity ◽  
Signal Pathway ◽  
Response Threshold ◽  
Computer Assisted ◽  
Time Resolved ◽  
Response Range ◽  
Transport Mutants ◽  
Signaling Activity

Chemotaxis of Escherichia coli toward phosphotransferase systems (PTSs)–carbohydrates requires phosphoenolpyruvate-dependent PTSs as well as the chemotaxis response regulator CheY and its kinase, CheA. Responses initiated by flash photorelease of a PTS substrates d-glucose and its nonmetabolizable analog methyl α-d-glucopyranoside were measured with 33-ms time resolution using computer-assisted motion analysis. This, together with chemotactic mutants, has allowed us to map out and characterize the PTS chemotactic signal pathway. The responses were absent in mutants lacking the general PTS enzymes EI or HPr, elevated in PTS transport mutants, retarded in mutants lacking CheZ, a catalyst of CheY autodephosphorylation, and severely reduced in mutants with impaired methyl-accepting chemotaxis protein (MCP) signaling activity. Response kinetics were comparable to those triggered by MCP attractant ligands over most of the response range, the most rapid being 11.7 ± 3.1 s−1. The response threshold was <10 nM for glucose. Responses to methyl α-d-glucopyranoside had a higher threshold, commensurate with a lower PTS affinity, but were otherwise kinetically indistinguishable. These facts provide evidence for a single pathway in which the PTS chemotactic signal is relayed rapidly to MCP–CheW–CheA signaling complexes that effect subsequent amplification and slower CheY dephosphorylation. The high sensitivity indicates that this signal is generated by transport-induced dephosphorylation of the PTS rather than phosphoenolpyruvate consumption.

scholarly journals Photophysical and photochemical properties of electronically excited fluorescent dyes: a new type of time-resolved laser-scanning spectroscopy

1999 ◽  
Vol 1 (3) ◽  
pp. 165-172 ◽  
Author(s):  
Ma. Heupel ◽  
I. Gregor ◽  
St. Becker ◽  
E. Thiel
Keyword(s):  
Molecular Oxygen ◽  
Laser Scanning ◽  
Fluorescent Dyes ◽  
High Sensitivity ◽  
Ambient Conditions ◽  
Time Resolved ◽  
Electronically Excited ◽  
New Type ◽  
Photochemical Properties ◽  
Scanning Spectroscopy

The capacity of a new type of time-resolved laser-scanning spectroscopy is discussed. Due to the developed modulation technique we obtain a high sensitivity in the absorption measurement as well as a very efficient suppression of the background absorption. The new technique has been used to investigate photophysical and photochemical properties of fluorescent dyes. All presented results are discussed in view of potential applications like dye laser and fluorescence labelling.The possibility of intermolecular triplet state quenching by molecular oxygen and further agents is considered in detail. The quenching process is described in terms of diffusion controlled interaction. It is shown that under ambient conditions quenching agents can inhibit the quenching by molecular oxygen and therefore the generation of the chemically highly reactive singlet molecular oxygen. It can be expected that the obtained information can be used in order to increase the photostability not only of rhodamine dyes.

Phosphorescent porphyrin probes in biosensors and sensitive bioassays

2000 ◽  
Vol 28 (2) ◽  
pp. 74-77 ◽  
Author(s):  
D. B. Papkovsky ◽  
T. O'Riordan ◽  
A. Soini
Keyword(s):  
Oxygen Sensor ◽  
Spectral Characteristics ◽  
Screening Method ◽  
High Sensitivity ◽  
Water Soluble ◽  
Fluorescent Detection ◽  
Rapid Screening ◽  
Time Resolved ◽  
Phosphorescence Lifetime ◽  
Practical Applications

Platinum(II) and palladium(II) complexes of porphyrins and related tetrapyrrolic pigments emit strong phosphorescence at room temperatures, which is characterized by long lifetimes falling into the sub-millisecond range and long-wave spectral characteristics. These features make the dyes useful as probes for a number of bioanalytical applications, particularly those employing time-resolved fluorescent detection. They can provide high sensitivity and selectivity, together with rather simple instrumental set-up. A number of analytical systems are now under development that are based on the use of phosphorescent porphyrin probes. Experimental results are presented on the following systems: (i) fibre-optic phosphorescence lifetime-based oxygen sensor on the basis of hydrophobic platinum-porphyrins and development of advanced sensing materials and prototype instrumentation; (ii) practical applications of the optical oxygen sensor, including a sensitive immunosensor that employs glucose oxidase labels, a rapid screening method for cell viability in microtitre-plate format, non-destructive measurement of oxygen in packaged foods and reagentless biosensors for metabolites (glucose, lactate); and (iii) the use of water-soluble platinum- and palladium-porphyrins as labels for ultra-sensitive time-resolved phosphorescence immunoassays.

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