Endoscopic Imaging Using a Multimode Optical Fibre Calibrated with Multiple Internal References

The interferometric acquisition of the transmission matrix (TM) of a multimode optical fibre (MMF), which is at the heart of multimode fibre-based endoscopic imaging methods, requires using a reference beam. Attempts to use an internal reference, that is to provide the reference in a common pathway geometry through the MMF itself, lead to a speckled reference intensity and consequential occurrence of “blind spots”—locations where insufficient optical power in the reference wave inflicts strong measurement errors. Here we show that combining a relatively small number of TMs, which are measured using different internal references, facilitates a complete elimination of blind spots, and thereby a significant enhancement of the imaging quality.

Multicenter Technical Validation of 30 Rapid Antigen Tests for the Detection of SARS-CoV-2 (VALIDATE)

During COVID19 pandemic, SARS-CoV-2 rapid antigen tests (RATs) were marketed with minimal or no performance data. We aimed at closing this gap by determining technical sensitivities and specificities of 30 RATs prior to market release. We developed a standardized technical validation protocol and assessed 30 RATs across four diagnostic laboratories. RATs were tested in parallel using the Standard Q® (SD Biosensor/Roche) assay as internal reference. We used left-over universal transport/optimum media from nasopharyngeal swabs of 200 SARS-CoV-2 PCR-negative and 100 PCR-positive tested patients. Transport media was mixed with assay buffer and applied to RATs according to manufacturer instructions. Sensitivities were determined according to viral loads. Specificity of at least 99% and sensitivity of 95%, 90%, and 80% had to be reached for 107, 106, 105 virus copies/mL, respectively. Sensitivities ranged from 43.5% to 98.6%, 62.3% to 100%, and 66.7% to 100% at 105, 106, 107 copies/mL, respectively. Automated assay readers such as ExDia or LumiraDx showed higher performances. Specificities ranged from 88.8% to 100%. Only 15 of 30 (50%) RATs passed our technical validation. Due to the high failure rate of 50%, mainly caused by lack of sensitivity, we recommend a thorough validation of RATs prior to market release.

Novel ratiometric fluorescent probe based on internal reference and its detection of hydrazine

In this work, dual-emissive ratiometric fluorescent system was constructed by the introduction of an ideal internal reference. By virtue of its unique alkalinity, N 2 H 4 could undergo a hydrazinolysis reaction with the ester group of F1 , inducing remarkable fluorescence enhancement while the blue fluorescence of the internal reference DPA remained constant. Consequently, the fluorescence intensity ratios (I 540 /I 440 ) were proportional to the concentrations of N 2 H 4 , which was beneficial for the exactly quantitative detection. The skillful strategy granted the sensing system advantages such as relative good solubility in aqueous media, easy-to-design, simple synthesis, large emission shift, good ratiometric response, as well as the successful application in real water samples and cell imaging.

Systematic Study on a Quantitative Analysis of Multicomponents by Single Marker (QAMS) Method for Simultaneous Determination of Eight Constituents in Pneumonia Mixture by UPLC-MS/MS

Pneumonia mixture was formulated and is available to treat children acute pneumonia and acute bronchitis in our hospital for nearly forty years, but there are few studies of its quality evaluation or control. In this paper, a new strategy for quality evaluation of pneumonia mixture was explored and verified through qualitative and quantitative analyses of multicomponents by single marker (QAMS) by UPLC-MS/MS. Baicalein was selected as an internal reference, and the relative correction factors (RCFs) and the relative retention time (RRT) of (R, S)-goitrin, amygdalin, chlorogenic acid, pseudoephedrine hydrochloride, ephedrine hydrochloride, ammonium glycyrrhizinate, and baicalin were established. The robustness and durability of the QAMS method were investigated. RCF values calculated by the average (AVG) method and linear regression (LRG) method had good repeatability and were acceptable for quantitative analysis, and the RTT combined with the exact masses of precursor and fragment ions and their abundance could be adopted for accurately positioning the chromatographic peak of the eight constituents. The consistency and feasibility of the QAMS method were verified by comparing the contents of the seven components calculated by a classic and validated external standard method (ESM) with those of the QAMS method, which reduces analytical cost and time of detection and avoids the problem of the diversity and large quantity of reference standards. The results demonstrated that the QAMS method developed in this paper could provide a new, alternative, and promising method to comprehensively and effectively determine multicomponents and control the quality of pneumonia mixture or even a group of similar medicines.

Imagine Your Crossed Hands as Uncrossed: Visual Imagery Impacts the Crossed-Hands Deficit

Successful interaction with our environment requires accurate tactile localization. Although we seem to localize tactile stimuli effortlessly, the processes underlying this ability are complex. This is evidenced by the crossed-hands deficit, in which tactile localization performance suffers when the hands are crossed. The deficit results from the conflict between an internal reference frame, based in somatotopic coordinates, and an external reference frame, based in external spatial coordinates. Previous evidence in favour of the integration model employed manipulations to the external reference frame (e.g., blindfolding participants), which reduced the deficit by reducing conflict between the two reference frames. The present study extends this finding by asking blindfolded participants to visually imagine their crossed arms as uncrossed. This imagery manipulation further decreased the magnitude of the crossed-hands deficit by bringing information in the two reference frames into alignment. This imagery manipulation differentially affected males and females, which was consistent with the previously observed sex difference in this effect: females tend to show a larger crossed-hands deficit than males and females were more impacted by the imagery manipulation. Results are discussed in terms of the integration model of the crossed-hands deficit.