High-sensitivity Technique Research Articles

Surface-Bound Antibiotic for the Detection of β-Lactamases.

Antimicrobial resistance (AMR) has been identified as a major threat to public health worldwide. To ensure appropriate use of existing antibiotics, rapid and reliable tests of AMR are necessary. One of the most common and clinically important forms of bacterial resistance is to β-lactam antibiotics (e.g., penicillin). This resistance is often caused by β-lactamases, which hydrolyze β-lactam drugs, rendering them ineffective. Current methods for detecting these enzymes require either time-consuming growth assays or antibiotic mimics such as nitrocefin. Here, we report the development of a surface-bound, clinically relevant β-lactam drug that can be used to detect β-lactamases and that is compatible with a range of high-sensitivity, low-cost, and label-free analytical techniques currently being developed for point-of-care-diagnostics. Furthermore, we demonstrate the use of these functionalized surfaces to selectively detect β-lactamases in complex biological media, such as urine.

Mosaic abnormalities of the skin: review and guidelines from the European Reference Network for rare skin diseases.

Cutaneous mosaicism is an area of dermatology in which there has been an explosion of knowledge within the current decade. This has led to fundamental changes in the understanding of the conditions in this field, and to an ongoing paradigm shift in the approach to management of mosaic skin disorders. To lay out the general principles of mosaicism as they are currently understood, summarize the known cutaneous mosaic abnormalities of the skin with associated phenotypic and genotypic information, review the latest trials on targeted therapies and propose guidelines for the general approach to a patient with suspected mosaicism. This was a consensus expert review as part of the European Reference Network project (ERN-Skin). This study provides clinicians with a practical approach to the patient with suspected mosaicism, redefines mosaicism for the modern genetic era, and proposes a new classification system based on genetic mechanism. What's already known about this topic? Cutaneous mosaicism is a complex field of dermatology that encompasses most birthmarks, and many rare syndromes. Some cutaneous patterns are known to be seen in mosaicism. Very few treatment options are available for most mosaic abnormalities of the skin. Recent high-sensitivity genetic techniques have led to an explosion of knowledge about genotype and phenotype in the literature. What does this study add? Expert consensus from the European Reference Network project. Review of knowledge of confirmed mosaic abnormalities of the skin, including cutaneous phenotype, extracutaneous associated features and genotype. Proposed new classification of mosaic abnormalities of the skin by genetic mechanism and therefore inheritance potential. Practical tips on correct sample collection and genetic investigation. Review of trials of targeted therapies. Guidelines for a practical clinical approach to the patient with suspected mosaicism.

High-resolution distributed shape sensing using phase-sensitive optical time-domain reflectometry and multicore fibers.

In this paper, a highly-sensitive distributed shape sensor based on a multicore fiber (MCF) and phase-sensitive optical time-domain reflectometry (φ-OTDR) is proposed and experimentally demonstrated. The implemented system features a high strain sensitivity (down to ∼0.3 µɛ) over a 24 m-long MCF with a spatial resolution of 10 cm. The results demonstrate good repeatability of the relative fiber curvature and bend orientation measurements. Changes in the fiber shape are successfully retrieved, showing detectable displacements of the free moving fiber end as small as 50 µm over a 60 cm-long fiber. In addition, the proposed technique overcomes cross-sensitivity issues between strain and temperature. To the best of our knowledge, the results presented in this work provide the first demonstration of distributed shape sensing based on φ-OTDR using MCFs. This high-sensitivity technique proves to be a promising approach for a wide range of new applications such as dynamic, long distance and three-dimensional distributed shape sensing.

Detectability of biosignatures in a low-biomass simulation of martian sediments

Discovery of a remnant habitable environment by the Mars Science Laboratory in the sedimentary record of Gale Crater has reinvigorated the search for evidence of martian life. In this study, we used a simulated martian mudstone material, based on data from Gale Crater, that was inoculated and cultured over several months and then dried and pressed. The simulated mudstone was analysed with a range of techniques to investigate the detectability of biosignatures. Cell counting and DNA extraction showed a diverse but low biomass microbial community that was highly dispersed. Pellets were analysed with bulk Elemental Analysis – Isotope Ratio Mass Spectrometry (EA-IRMS), high-resolution Laser-ablation Ionisation Mass Spectrometry (LIMS), Raman spectroscopy and Fourier Transform InfraRed (FTIR) spectroscopy, which are all techniques of relevance to current and future space missions. Bulk analytical techniques were unable to differentiate between inoculated samples and abiotic controls, despite total levels of organic carbon comparable with that of the martian surface. Raman spectroscopy, FTIR spectroscopy and LIMS, which are high sensitivity techniques that provide chemical information at high spatial resolution, retrieved presumptive biosignatures but these remained ambiguous and the sedimentary matrix presented challenges for all techniques. This suggests challenges for detecting definitive evidence for life, both in the simulated lacustrine environment via standard microbiological techniques and in the simulated mudstone via analytical techniques with relevance to robotic missions. Our study suggests that multiple co-incident high-sensitivity techniques that can scan the same micrometre-scale spots are required to unambiguously detect biosignatures, but the spatial coverage of these techniques needs to be high enough not to miss individual cellular-scale structures in the matrix.

Nonlinear optical studies of calcium tartrate crystals

Calcium Tartrate crystals were synthesized using sol–gel technique. Linear optical studies of the crystals were carried out in the UV–Vis-NIR spectral range. Nonlinear optical open aperture z-scan studies were done using high sensitive z-scan experimental technique. Both saturable absorption and reverse saturable absorption behaviour were observed at different input fluences. Reverse saturable absorption characteristic of the crystals make them suitable for optical limiting applications. Our analysis revealed that the novel crystal has the optimum values for the optical limiting parameters which are required for a high-performance optical limiter.

In vitro MATURATION OF DROMEDARY SHE-CAMEL OOCYTES EXPOSED TO LASER IRRADIATION

The objective of this study was to study the effect of laser irradiation on maturation rate of dromedary she-camel oocytes. Although in vitro fertilization (IVF) technique in she-camel has been established, but maturation rate of camel oocytes is still low comparing with other animal species. Several studies performed to improve in-vitro maturation rate using different types of media with different incubation times. In order to establish high sensitive and low cost maturation improvement technique, laser irradiation has been suggested in the present work. Cumulus oocytes complexes (COCʼs) were collected from ovaries by aspiration method and grade (A) oocytes were chosen and divided into five different groups, 62 oocytes served as control group, an un-irradiated (group 1), 64 oocytes exposed to 2 minutes of laser irradiation (group 2), 57 oocytes exposed to 3 minutes of laser irradiation (group 3), 49 oocytes exposed to 4 minutes of laser irradiation (group 4) and 52 oocytes exposed to 5 minutes of laser irradiation (group 5) with a total output power of 3 mW for different exposure durations; 2, 3, 4 and 5 minutes. Afterwards, oocytes were matured in TCM-199 medium at 38.5oC and 5% CO2 in humidified air for 42 h. Maturation rate was calculated based on expulsion of the first polar body and statistically analyzed by one way ANOVA test. The obtained results showed that, the oocytes reached germinal vesicles (GV) which exposed to laser beam for 5 minutes at 488 nm wavelength represent significantly (P<0.05) the highest value (42.31%) compared to control (not irradiated, 16.13%). However, other groups of GV showed insignificant differences with the control group. The metaphase II (M II) in the control oocytes represents significantly (P<0.05) the highest value (75.81%) compared to 3-5 minutes exposed groups. The degenerated oocytes exposed to laser beam for 5 minutes at 488 nm wavelength represent significantly (P<0.05) the highest value (40.38%) compared to control (not irradiated, 8.06%). In conclusion‚ these results indicated that the exposure of laser irradiation for 2 minutes may improve in-vitro nuclear maturation of immature oocytes in dromedary she-camels as compared to other durations (3-5 minutes) at 488 nm wavelength (blue laser).

High-resolution spectral analysis of hybrid A/B-type band of 1,3-butadiene at 6.2 μm using an EC-QCL coupled with cavity ring-down spectroscopy

The fine rotational-vibrational spectra of long-chain molecules like 1,3-butadiene are very closely spaced and highly overlapped. Such investigations require high-sensitive techniques to avoid overlapping and adequate resolution to observe their fine structure spectra. In this work, we have utilized a high-resolution external cavity-quantum cascade laser at ∼6.2 μm coupled with high-sensitive cavity ring-down spectroscopy (CRDS) to determine the fine ro-vibrational spectra of 1,3-butadiene in the gas phase. We experimentally probed the hybrid A/B-type band at 1596.412 cm−1 and also calculated relevant spectroscopic parameters of 1,3-butadiene using Gaussian 16 and subsequently simulated the spectra using PGOPHER simulation. Finally, we selected a unique interference-free spectral region within the 1,3-butadiene spectrum, and performed detailed ro-vibrational study of 3 spectral lines in this region. These results are a great advance over the earlier works and provide a spectroscopic window that may enable selective and high-sensitive sensing of 1,3-butadiene in the future.

High spectral resolution of GaAs/AlAs phononic cavities by subharmonic resonant pump-probe excitation

We present here precise measurement of the resonance frequency, lifetime and shape of confined acoustic modes in the tens of GHz regime in GaAs/AlAs superlattice planar and micropillar cavities at low temperature ($\sim 20\,\textrm{K}$). The subharmonic resonant pump-probe technique, where the repetition rate of the pump laser is tuned to a subharmonic of the cavity resonance to maximize the amplitude of the acoustic resonance, in combination with a Sagnac interferometer technique for high sensitivity ($\sim 10 \,\textrm{fm}$) to the surface displacement, has been used. The cavity fundamental mode at $\sim 20\,\textrm{GHz}$ and the higher order cavity harmonics up to $\sim 180\,\textrm{GHz}$ have been clearly resolved. Mechanical Q-values up to $2.7 \times 10^4$ have been measured in a planar superlattice, and direct spatial mapping of confined acoustic modes in a superlattice cavity micropillar has been demonstrated. The Q-frequency product obtained is $ \sim 5 \times 10^{14}$ demonstrating the suitability of these superlattice cavities for optomechanical applications.

FTIR fingerprints associated to a PLS-DA model for rapid detection of smuggled non-compliant diesel marketed in Morocco

Fourier Transform Infrared Spectroscopy was selected as a rapid, non-destructive, cheap and a high sensitive technique combined with chemometric tools in order to detect and discriminate smuggled diesel samples from authentic products. A total of nineteen authentic diesels and eleven smuggled diesel samples were collected, their quality was checked by determining their chemical composition using the GCMS technique in order to avoid the use of adulterated products. Secondly, infrared fingerprints of all samples were recorded, and the resulting spectra processed by Principal Components Analysis (PCA) to visualize classes and to detect outliers. Partial Least Square Discriminate Analysis (PLS-DA) was carried out to classify samples in two classes (authentic or smuggled). The PCA results were able to indicate the dissimilarities between the two diesel classes, and the PCA scores-plot observed two groups. On the other hand, spectral data associated with PLS-DA models allowed a better classification between the two classes of diesel with a high specificity and sensitivity.

Improving Methodology of Particulate Measurement in Periodic Technical Inspection with High-Sensitivity Techniques: Laser Light Scattering Photometry and Particle Number Method

First, the validity of the current test procedure for particle measurement adopted in a periodic technical inspection (PTI) was evaluated by comparing test results obtained with the PTI and a type approval test (TAT) procedure using a Euro V level diesel truck with an intentionally damaged diesel particulate filter (DPF). PM and particle number (PN) with the TAT increased with increasing DPF damage ratio, and the PTI results well reproduced those in the TAT. However, the regulation limit of the PTI was so loose that even a 100% damaged DPF resulted in emission well below the PTI limit, although 0.5% and 5% damage ratios resulted in values exceeding the PN and PM limits in TAT, respectively. Then, we evaluated three different techniques for particle detection with the PTI procedure, such as an opacity meter, which is currently used in PTI, laser light scattering photometry (LLSP), and the PN method. For the detecting DPF failure, opacity meters did not have sufficient sensitivity. On the other hand, the LLSP was sensitive enough for detecting DPF failure, but the results varied among LLSP devices. This variation was due to the test procedure of PTI, which is strongly transient (no load racing). The LLSP and PN measurement devices were sensitive enough to detect DPF failure at idle, which was quite steady, and the variation observed in the PTI procedure did not occur. PN counting of particles over 15 nm was more sensitive than LLSP and was sensitive enough to detect DPF failure, which did not result in the PM limit in TAT being exceeded.

Raman spectroscopy of osteosarcoma cells

Osteosarcoma is the most common primary malignant bone tumor. In the last years, several studies have demonstrated that the increase of Hydroxyapatite (HA) and Interleukin-6 (IL-6) syntheses compared to those expressed by normal osteoblasts could be used to detect the degree of malignancy of osteosarcoma cells. Conventional biochemical methods widely employed to evaluate bone cell differentiation, including normal and cancerous phenotypes, are time consuming and may require a large amount of cells. HA is a mineral form of calcium phosphate whose presence increases with maturation of osteosarcoma cells. Analogously, IL-6 is a fundamental cytokine whose production is highly increased in osteosarcoma cells. In this study, we employ Raman spectroscopy to the identification and discrimination of osteosarcoma cells from osteo-differentiated mesenchymal stromal cells (MSCs) by detecting the presence of HA and IL-6. However, while the identification of HA is facilitated by the characteristic peak at 960 cm−1, corresponding to symmetric stretching (P–O) mode, the quantification of IL-6 it is much more elusive, being its Raman signal characterized by cysteine, but also by phenylalanine, amide I II and III whose signals are common to other proteins. Supported by an accurate multivariate analysis, the results show that Raman spectroscopy is a high sensitivity technique dealing out a direct and quantitative measurement of specific mineralization levels of osteosarcoma cells. In turn, by exploiting the Surface-Enhanced Raman Scattering stimulated by internalized Gold Nanoshells (AuNSs) and combined with scanning probe microscopies, we were able to employ Raman spectroscopy to study subcellular components locally.

Visualization technologies for 5-ALA-based fluorescence-guided surgeries.

5-ALA-based fluorescence-guided surgery has been shown to be a safe and effective method to improve intraoperative visualization and resection of malignant gliomas. However, it remains ineffective in guiding the resection of lower-grade, non-enhancing, and deep-seated tumors, mainly because these tumors do not produce detectable fluorescence with conventional visualization technologies, namely, wide-field (WF) surgical microscopy. We describe some of the main factors that limit the sensitivity and accuracy of conventional WF surgical microscopy, and then provide a survey of commercial and research prototypes being developed to address these challenges, along with their principles, advantages and disadvantages, as well as the current status of clinical translation for each technology. We also provide a neurosurgical perspective on how these visualization technologies might best be implemented for guiding glioma surgeries in the future. Detection of PpIX expression in low-grade gliomas and at the infiltrative margins of all gliomas has been achieved with high-sensitivity probe-based visualization techniques. Deep-tissue PpIX imaging of up to 5mm has also been achieved using red-light illumination techniques. Spectroscopic approaches have enabled more accurate quantification of PpIX expression. Advancements in visualization technologies have extended the sensitivity and accuracy of conventional WF surgical microscopy. These technologies will continue to be refined to further improve the extent of resection in glioma patients using 5-ALA-induced fluorescence.

A wide dynamic range and high resolution all-fiber-optic turbidity measurement system based on single photon detection technique

A high-resolution fiber-optic detection system has been developed to measure the wide dynamic range of turbidity. To obtain high-resolution measurement results, a high sensitive single photon detection technique (SPDT) has been used in the system. Based on fiber characteristics, a compact probe structure for fiber-optic integrated transceiver (FITP) is designed to transmitting and collection light signal, which has the capability of detecting turbidity in the narrow workspace. By combining the Beer-Lambert (B-L) law transmission law with single photon counting theory, a novel turbidity measurement theoretical model has been proposed, which shows a good exponential relationship over the whole measurement range from 0.01 to 1000 NTU (Nephelometric Turbidity Units). However, when detecting 0.01–0.1 NTU low turbidity, the experimental results turn into an approximate linear relationship, which good agrees with the proposed theoretical model. Last, some issues about the optimization of light intensity and requiring attention on constructing a practical distributed multi-point water turbidity remote monitoring system in the outdoors are also discussed. It was found that the system can achieve a measurement dynamic range as wide as 50 dB with a resolution better than 0.01 NTU in the range of 0.01–1000 NTU, which is suitable for some specific turbidity measurement in remote and narrow workspace.

An annotated checklist of tick-borne pathogens of dogs in Nigeria.

Tick-borne pathogens are transmitted by the bite of a tick vector or the ingestion therein by a susceptible host. Conventionally, the diagnosis of tick-borne parasites in Nigeria is achieved through the demonstration of their developmental stages in the host's blood or tissues. These classical methods are limited in their capability to detect chronic cases or healthy carriers and to differentiate between pathogens of similar morphological features. Molecular diagnostic techniques of high sensitivity have been developed to overcome these shortfalls by detecting the pathogen's DNA, elucidating their genetic makeup and comparing their phylogenetic relationship to other pathogens, sometimes necessitating taxonomic changes. Detection of DNA of canine tick-borne pathogens (CTBPs) such as Ehrlichia canis, Hepatozoon canis, and Mycoplasma haemocanis has been reported in Nigerian dogs corroborating earlier microscopic findings. Furthermore, DNA of Anaplasma platys, Ehrlichia ewingii, 'Candidatus Mycoplasma haemobos' and Theileria sp. hitherto considered to be absent in Nigeria has been detected, thereby expanding the spectrum of CTBPs in the country. However, in some cases, diagnoses based on the detection of single short DNA fragments from pathogens can cause considerable confusion. This occurred in the case of the large canine Babesia, previously referred to as Babesia canis which has been reported in Nigerian dogs. There appears to be confusion regarding the accurate status of this pathogen in Nigeria due to the subsequent classification into Babesia canis, Babesia vogeli and Babesia rossi. Moreover, several molecular studies failed to detect the DNA of Babesia gibsoni previously reported in Nigerian dogs by light microscope. These findings necessitate regular update of the list of CTBPs of veterinary and medical importance, in order to keep practitioners abreast with these changes. Herein, an annotated checklist of tick-borne pathogens of dogs in Nigeria, based on available data from both classical and molecular studies, with notes explaining any discrepancies between the methods and probable explanations thereof, is presented.

Deoxynivalenol screening in wheat‐derived products in Gran Asunción, Paraguay

Abstract Fusarium graminearum is one of the most important pathogens affecting wheat production in Paraguay. This fungus decreases yield and grain quality; the most important consequence is the production of mycotoxins from the trichothecene group, secondary metabolites toxic to humans and other animals. The toxin reported in Paraguay is deoxynivalenol, which has effects on the gastrointestinal tract and immune system. To determine the presence of deoxynivalenol in flour and baked goods, samples of wholemeal flour and white flour, white and wholemeal bread, and bran crackers were carried out in the Gran Asunción Area. The presence of deoxynivalenol was determined by monoclonal antibodies through the use of quantitative test strips. The results were variable and below those established by international standards.Practical applicationsIn the developing countries, the control of the quality and safety of food is practically nonexistent. In Paraguay, there is no legislation on the maximum levels of deoxynivalenol in wheat and derivatives. As this cereal and its derivative products are highly susceptible to contamination by Fusarium and its mycotoxins, it is a priority to initiate controls and establish bases for legislation on maximum acceptable limits in these products. Also highlight the need at country level of the application of high efficiency and sensitive techniques for quantification mycotoxins in food.

Nanocalorimetric evidence for nematic superconductivity in the doped topological insulator Sr0.1Bi2Se3

Spontaneous rotational-symmetry breaking in the superconducting state of doped $\mathrm{Bi}_2\mathrm{Se}_3$ has attracted significant attention as an indicator for topological superconductivity. In this paper, high-resolution calorimetry of the single-crystal $\mathrm{Sr}_{0.1}\mathrm{Bi}_2\mathrm{Se}_3$ provides unequivocal evidence of a two-fold rotational symmetry in the superconducting gap by a \emph{bulk thermodynamic} probe, a fingerprint of nematic superconductivity. The extremely small specific heat anomaly resolved with our high-sensitivity technique is consistent with the material's low carrier concentration proving bulk superconductivity. The large basal-plane anisotropy of $H_{c2}$ is attributed to a nematic phase of a two-component topological gap structure $\vec{\eta} = (\eta_{1}, \eta_{2})$ and caused by a symmetry-breaking energy term $\delta (|\eta_{1}|^{2} - |\eta_{2}|^{2}) T_{c}$. A quantitative analysis of our data excludes more conventional sources of this two-fold anisotropy and provides the first estimate for the symmetry-breaking strength $\delta \approx 0.1$, a value that points to an onset transition of the second order parameter component below 2K.

Low background neutron activation: a high sensitivity technique for long-lived radionuclides determination in rare events physics experiments

Low-background neutron activation analysis has proven to be a very useful analytical method for the selection of low-radioactive materials used for the realization of “rare-events” physics experiments. The present article reviews the main results obtained with neutron activation in the radio-pure materials selection by several research groups involved in underground astro-particle physics experiments.

Multi-channel averaging detection for fast imaging of weakly absorbing defects in surface thermal lensing.

Surface thermal lensing (STL) is a high sensitive pump-probe technique for photothermal characterization of weakly absorbing defects in optical materials. Commonly, the frequency modulation is applied in the pump beam, and the STL signal that appears as small modulation on top of an intense background is then detected on the probe beam by lock-in amplification. However, the lock-in detection by filtering the signal in the frequency domain results in low efficiency in the STL, preventing investigations of the large area surfaces. Here it is shown that the multi-channel averaging, which corresponds to temporal integration, is better suited for detection of the STL signal. It is demonstrated that by converting the conventional single-point scanning STL to the line scanning STL and employing suitable width of the time bins and the number of records, the imaging speed of the multi-channel averaging detection can be improved by a factor of 3.7 relative to the lock-in detection at the same signal-to-noise ratio of 6 dB and imaging resolution of 20 μm. Therefore, high-quality photothermal images of weakly absorbing defects can be recorded with higher efficiency and lower laser irradiance, making it possible to investigate large samples.

New Approach of High Sensitivity Techniques Using Collective Detection Method with Multiple GNSS Receivers.

The Collective Detection (CD) technique is a promising approach to meet the requirements for signal acquisition in GNSS-harsh environments. The CD approach has been proposed because of its potential to operate as both a direct positioning method and a high-sensitivity acquisition method. This paper is dedicated to the development of a new CD architecture for processing satellite signals in challenging environments. It proposes the best signal acquisition method used according to the reception conditions of the different receivers that can assist the user in difficulty. Knowing that the CD approach is beneficial in the case where the maximum of satellite signals can be combined, the proposed approach consists in choosing the best receiver(s) from several connected receivers to serve as a reference station, as smart cooperative navigation concept. New metrics of the CD with optimal weighting of visible satellites are exploited. Analysis of optimization method in order to use better satellites according to some defined parameters (elevation, , and GDOP) were carried out. Real GPS L1 C/A signals are exploited to analyze the efficiency of the proposed approach. A comparison of the results through the accumulation of some good satellites among all visible satellites have shown the effectiveness of this method.

Production of extracellular reactive oxygen species by phytoplankton: past and future directions.

In aquatic environments, phytoplankton represent a major source of reactive oxygen species (ROS) such as superoxide and hydrogen peroxide. Many phytoplankton taxa also produce extracellular ROS under optimal growth conditions in culture. However, the physiological purpose of extracellular ROS production by phytoplankton and its wider significance to ecosystem-scale trophic interactions and biogeochemistry remain unclear. Here, we review the rates, taxonomic diversity, subcellular mechanisms and functions of extracellular superoxide and hydrogen peroxide production by phytoplankton with a view towards future research directions. Model eukaryotic phytoplankton and cyanobacteria produce extracellular superoxide and hydrogen peroxide at cell-normalized rates that span several orders of magnitude, both within and between taxa. The potential ecophysiological roles of extracellular ROS production are versatile and appear to be shared among diverse phytoplankton species, including ichthyotoxicity, allelopathy, growth promotion, and iron acquisition. Whereas extracellular hydrogen peroxide likely arises from a combination of intracellular and cell surface production mechanisms, extracellular superoxide is predominantly generated by specialized systems for transplasma membrane electron transport. Future insights into the molecular-level basis of extracellular ROS production, combined with existing high-sensitivity geochemical techniques for the direct quantification of ROS dynamics, will help unveil the ecophysiological and biogeochemical significance of phytoplankton-derived ROS in natural aquatic systems.