Unfavorable Effects of Fixatives on the Fluorescence Intensity and Biological Functions of Fluorescent Proteins in HEK293T Cells and Transgenic Mice

Fluorescent proteins (FPs) are commonly used probes for coding genes that enable specific protein or whole-cell labeling. Their fluorescence intensity is used for molecular quantitation and intermolecular interaction analysis. Since FPs are usually small soluble proteins, they easily cross the membranes if cell integrity is disrupted, resulting in FP signal attenuation/loss. Specimen prefixation to preserve FP localization within cells/tissues is therefore useful. However, specific fixatives can weaken or eliminate FP signals. We studied the effects of five common fixatives on FP fluorescence intensity and biological functions to determine their suitability for FP signal and FRET efficiency preservation in cells and tissues. FP (GFP, YFP, CFP and RFP)-expressing HEK293T cells with methanol, 95% ethanol, 4% PFA, acetone and glutaraldehyde, and brain tissue sections of EGFP- and tdTomato-labeled transgenic fluorescent mice was fixed with 4% PFA. The FP signals in HEK293T cells and brain tissue from transgenic fluorescent mice were weakened or even eliminated after fixation with these fixatives. The fixatives affected FP biological function, and the FP FRET efficiency significantly differed between prefixation and postfixation (all p<0.01). Thus, fixatives impair FP fluorescence to some extent, leading to attenuation/loss of signals or even biological functions. Fixatives should be applied carefully in FP-related experiments to avoid bias.

Study on space absorbing of multilayer MWCNTs/Fe3O4/NBR composites

In order to meet the requirements of “wide, thin, strong and light” for military stealth materials, it is of great practical value to study the absorbing characteristics of multi-layer MWCNTs/Fe3O4/NBR absorbing materials in space. First, we use the large-scale software COMSOL Multiphysics to simulate the absorbing characteristics of the composite thin plate in space. Then the four-port network matrix is used to calculate the absorbing characteristics of the composite plate in space. Finally, the Free-Space method is used to measure the reflection attenuation loss, and the results of the three methods are compared and analyzed. The results show that when the frequency is 10 GHz, the reflection loss of multi-layer MWCNTs/Fe3O4/NBR reaches the maximum value of −27.91, −27.01 and −22.56 dB by COMOSL numerical simulation, four-port network the matrix and Free-Space experimental measurement. The results of the three methods show that the reflection loss is less than −10 dB in the frequency band of 6–14 GHz.

Impact of Equalizer step size in Underwater Acoustic Communication Channel

The Underwater Acoustic Channel (UAC) is a time variant channel and its multipath effects create ISI. This is one of the most important obstacles in the UAC channel which reduces the transmission rate. To remove this obstacle, a proper filter has to be designed in the receiver section. In this article, optimal step size for equalizer is computed and compared the results with the known techniques namely Decision Feedback Equalizer with interleave division multiple access (DFE IDMA) and Cyclic Prefix - Orthogonal Frequency Division Multiplexing (CP-OFDM) Equalizer. Channels are modeled using ray tracing methods. The various factors considered are ambient noise, attenuation loss, bottom and surface loss. The overall path loss for channels is computed by summing up the attenuation loss, surface and bottom loss. Simulation results evident that for short range UAC channel, the BER in the order of 10-2 is achieved using proposed methodology with least Eb/No compared to standard DFE method.

Implementing IoT in Underwater Communication using Li-Fi

Internet of Things (IoT) is attracting more research interest as a result of increased interaction of human with underwater world. IoT technology using Light fidelity (Li-Fi) module plays a vital role in Environmental monitoring, underwater exploration, underwater Disaster management and underwater military Applications. In this paper, we implement IoT in underwater communication using Li-Fi module. However Implementing Li-Fi module in underwater pose grand challenges due to the unique features of underwater channel and acoustic systems. We comprehensively investigate these unique features and finally possible solutions are provided. Simulations are done using MATLAB software to find which color of light emitting diode (LED) is suitable for underwater Communication. It is found that Blue – Cyan-Green Spectral range of wavelength 490nm to 560nm is suitable for underwater communication. We obtain low absorption, scattering and attenuation loss in the Blue – CyanGreen Spectral range. An application was developed for the fisherman to identify number and variety of fishes available in particular location.

Deep learning-based muscle segmentation and quantification at abdominal CT: application to a longitudinal adult screening cohort for sarcopenia assessment

Objective: To investigate a fully automated abdominal CT-based muscle tool in a large adult screening population. Methods: A fully automated validated muscle segmentation algorithm was applied to 9310 non-contrast CT scans, including a primary screening cohort of 8037 consecutive asymptomatic adults (mean age, 57.1±7.8 years; 3555M/4482F). Sequential follow-up scans were available in a subset of 1171 individuals (mean interval, 5.1 years). Muscle tissue cross-sectional area and attenuation (Hounsfield unit, HU) at the L3 level were assessed, including change over time. Results: Mean values were significantly higher in males for both muscle area (190.6±33.6 vs 133.3±24.1 cm2, p<0.001) and density (34.3±11.1 HU vs 27.3±11.7 HU, p<0.001). Age-related losses were observed, with mean muscle area reduction of -1.5 cm2/year and attenuation reduction of -1.5 HU/year. Overall age-related muscle density (attenuation) loss was steeper than for muscle area for both sexes up to the age of 70 years. Between ages 50 and 70, relative muscle attenuation decreased significantly more in females (-30.6% vs -18.0%, p<0.001), whereas relative rates of muscle area loss were similar (-8%). Between ages 70 and 90, males lost more density (-22.4% vs -7.5%) and area (-13.4% vs -6.9%, p<0.001). Of the 1171 patients with longitudinal follow-up, 1013 (86.5%) showed a decrease in muscle attenuation, 739 (63.1%) showed a decrease in area, and 1119 (95.6%) showed a decrease in at least one of these measures. Conclusion: This fully automated CT muscle tool allows for both individualized and population-based assessment. Such data could be automatically derived at abdominal CT regardless of study indication, allowing for opportunistic sarcopenia detection. Advances in knowledge: This fully automated tool can be applied to routine abdominal CT scans for prospective or retrospective opportunistic sarcopenia assessment, regardless of the original clinical indication. Mean values were significantly higher in males for both muscle area and muscle density. Overall age-related muscle density (attenuation) loss was steeper than for muscle area for both sexes, and therefore may be a more valuable predictor of adverse outcomes.

Design of Underwater Acoustic Channel Model for OFDM Communication System

The paper describes the design of underwater acoustic channel model for OFDM communication system. The underwater acoustic channel considered includes multipath effect, attenuation loss, absorption loss, spreading loss and total noise due to thermal Noise, turbulence Noise, shipping Noise, wave Noise. The acoustic channel model used for OFDM Communication will have the noise effect due to attenuation loss and ambient noise (Total Noise). In this research work, In the underwater channel, Multipath parameters such as length, width and depth and attenuation parameters such as frequency, salinity, radial range, SPS and ambient noise parameters such as shipping factor, wave factor are considered in calculating total noise.