Orientation-based solar noise impact on underwater and free-space optical wireless communication systems: experimental investigations.

Solar noise, when it interferes with the received signal at the system receiver (Rx) of an optical wireless communication (OWC) system, degrades the system's performance. The detrimental effect of solar noise on OWC systems has been well established in the literature. This work experimentally demonstrates solar noise interference in the OWC system by pointing the system Rx in various orientations in air and water mediums, e.g., 0° (Rx pointing horizontally leftward), 45°, 90° (Rx pointing vertically downward), 135°, 180° (Rx pointing horizontally rightward), 225°, 270° (Rx pointing vertically upward), and 315°. The experimental outcomes depict the signal's noise content, spectral leakage, and roll-off rate variation at multiple Rx orientations. We also demonstrate the solar noise interference in transmitting an image through the outdoor underwater OWC link by pointing the system Rx in various orientations. Experimental demonstration confirms that the same OWC system never behaves identically in the presence of solar noise if the system Rx keeps changing its orientation during the maneuver.

FTIR microspectroscopy and multivariate analysis facilitate identification of dynamic changes in epithelial-to-mesenchymal transition induced by TGF-ß in prostate cancer cells.

The standard diagnosis of prostate cancer is accomplished by the identification of cytomorphological deviations in biopsied tissues while immunohistochemistry is used to resolve the equivocal cases. Accumulating evidence favors the concept that epithelial-to-mesenchymal transition (EMT) is a stochastic process composed of multiple intermediate states instead of a single binary switch. Despite its significant role in promoting cancer aggressiveness, the current tissue-based risk stratification tools do not include any of the EMT phenotypes as a metric. As a proof-of-concept, the present study analyzes the temporal progression of EMT in transforming growth factor-beta (TGF-ß) treated PC3 cells encompassing multifarious characteristics such as morphology, migration and invasion, gene expression, biochemical fingerprint, and metabolic activity. Our multimodal approach reinstates EMT plasticity in TGF-ß treated PC3 cells. Further, it highlights that mesenchymal transition is accompanied by discernible changes in cellular morphometry and molecular signatures particularly in the range of 1800-1600 cm-1 and 3100-2800 cm-1 of Fourier-transformed infrared (FTIR) spectra signifying Amide III and lipid, respectively. Investigation of attenuated total reflectance (ATR)-FTIR spectra of extracted lipids from PC3 cell populations undergoing EMT identifies changes in stretching vibration at FTIR peaks at 2852, 2870, 2920, 2931, 2954, and 3010 cm-1 characteristics of fatty acids and cholesterol. Chemometric analysis of these spectra indicates that the level of unsaturation and acyl chain length of fatty acid coregister with differential epithelial/mesenchymal states of TGF-ß treated PC3 cells. Observed changes in lipids also correlate with cellular nicotinamide adenine dinucleotide hydrogen (NADH) and flavin adenine dinucleotide dihydrogen (FADH2) levels and mitochondrial oxygen consumption rate. In summary, our study establishes that morphological and phenotypic traits of epithelial/mesenchymal variants of PC3 cells concur with their respective biochemical and metabolic properties. It also underscores that spectroscopic histopathology has a definitive potential to refine the diagnosis of prostate cancer reckoning its molecular and biochemical heterogeneities.

Performance of the Reed-Solomon-coded underwater optical wireless communication system with orientation-based solar light noise.

Various physical and chemical properties of seawater degrade the performance of the underwater optical wireless communication (UOWC) system. Implementing a forward error correction (FEC) coding scheme, advanced modulation, and signal processing techniques improves the UOWC system performance. So far, the implementation of FEC codes over the UOWC system has not been discussed with the system receiver (Rx) orientations. The undersea background noise is a challenge to the UOWC system, and the solar noise is robust in this category. The system Rx experiences unequal solar noise density when it faces different orientations. This paper evaluates the performance of the UOWC system, implementing the Reed-Solomon (RS) coding scheme when the Rx meets different orientations, and presents a computational model to find out energy-efficient RS code for a specific direction. The theoretical evaluation demonstrates that a fixed RS code is not always energy-efficient to the system when the Rx moves in various orientations.

Theoretical study on the effectiveness of optical filters to suppress orientation-based solar light noise.

It is well established in the literature that the performance of an underwater optical wireless communication (UOWC) system degrades due to various channel-based and environmental attributes. So far, consistent performance by a UOWC system has not been discussed when the system receiver (Rx) is positioned at a certain depth and takes on different orientations, i.e., vertically upward or downward, and horizontally left or right. This paper discusses the UOWC system performance when the Rx points in three different orientations and captures the modulated light signal and different intensities of solar light. We carry out a detailed comparative performance analysis of the UOWC Rx system considering various optical components, such as a colored glass optical bandpass filter, optical thin-film interference filter, and optical wide-field birefringent filter (OWFBF), which are mounted in front of the UOWC Rx to suppress solar light noise interference for different orientations. We observe that the same UOWC Rx behaves differently in all three orientations and the OWFBF outperforms.

Tunable Van der Waal's optical metasurfaces (VOMs) for biosensing of multiple analytes.

Van der Waal's heterostructure assembling low dimensional materials are the new paradigm in the field of nanophotonics. In this work, we theoretically investigate Van der Waal's optical metasurfaces consisting of graphene and hBN for the application of biosensing of multiple analytes in the mid-infrared (MIR) region. Phonon polaritons of hexagonal boron nitride (hBN) show an advantage over plasmon polaritons, as the phonon polaritons are lossless and possess high momentum and enhanced lifetime. The hybrid phonon mode produced at 6.78 µm in the mid-infrared (MIR) region with near-perfect absorption is used for surface-enhanced infrared absorption (SEIRA) based detection of organic analytes. Moreover, by adding the graphene layer, the device's overall resonance responses can be tuned, enabling it to identify multiple organic analytes-such as 4,4'-bis(N-carbazolyl)-1,1'-biphenyl (CBP) and nitrobenzene (Nb) [C6H5NO2], just by changing graphene's fermi potential (Ef). Owing to large wave vector of phonon polariton, the device has the capability to detect small amount of number of molecules (390 for CBP and 1990 for nitrobenzene), thus creating a highly sensitive optical biosensor.

Comprehensive Evaluation of PAXgene Fixation on Oral Cancer Tissues Using Routine Histology, Immunohistochemistry, and FTIR Microspectroscopy.

The choice of tissue fixation is critical for preserving the morphology and biochemical information of tissues. Fragile oral tissues with lower tensile strength are challenging to process for histological applications as they are prone to processing damage, such as tissue tear, wrinkling, and tissue fall-off from slides. This leads to loss of morphological information and unnecessary delay in experimentation. In this study, we have characterized the new PAXgene tissue fixation system on oral buccal mucosal tissue of cancerous and normal pathology for routine histological and immunohistochemical applications. We aimed to minimize the processing damage of tissues and improve the quality of histological experiments. We also examined the preservation of biomolecules by PAXgene fixation using FTIR microspectroscopy. Our results demonstrate that the PAXgene-fixed tissues showed significantly less tissue fall-off from slides. Hematoxylin and Eosin staining showed comparable morphology between formalin-fixed and PAXgene-fixed tissues. Good quality and slightly superior immunostaining for cancer-associated proteins p53 and CK5/6 were observed in PAXgene-fixed tissues without antigen retrieval than formalin-fixed tissues. Further, FTIR measurements revealed superior preservation of glycogen, fatty acids, and amide III protein secondary structures in PAXgene-fixed tissues. Overall, we present the first comprehensive evaluation of the PAXgene tissue fixation system in oral tissues. This study concludes that the PAXgene tissue fixation system can be applied to oral tissues to perform diagnostic molecular pathology experiments without compromising the quality of the morphology or biochemistry of biomolecules.