Polarization sensitive optical frequency domain imaging system for endobronchial imaging

A polarization sensitive endoscopic optical frequency domain imaging (PS-OFDI) system with a motorized distal scanning catheter is demonstrated. It employs a passive polarization delay unit to multiplex two orthogonal probing polarization states in depth, and a polarization diverse detection unit to detect interference signal in two orthogonal polarization channels. Per depth location four electro-magnetic field components are measured that can be represented in a complex 2×2 field matrix. A Jones matrix of the sample is derived and the sample birefringence is extracted by eigenvalue decomposition. The condition of balanced detection and the polarization mode dispersion are quantified. A complex field averaging method based on the alignment of randomly pointing field phasors is developed to reduce speckle noise. The variation of the polarization states incident on the tissue due to the circular scanning and catheter sheath birefringence is investigated. With this system we demonstrated imaging of ex vivo chicken muscle, in vivo pig lung and ex vivo human lung specimens

Multimodal probe for optical coherence tomography epidetection and micron-scale indentation

We present a multimodal ferrule-top sensor designed to perform the integrated epidetection of Optical Coherence Tomography (OCT) depth-profiles and micron-scale indentation by all-optical detection. By scanning a sample under the probe, we can obtain structural cross-section images and identify a region-of-interest in a nonhomogeneous sample. Then, with the same probe and setup, we can immediately target that area with a series of spherical-indentation measurements, in which the applied load is known with a μN precision, the indentation depth with sub-μm precision and a maximum contact radius of 100μm. Thanks to the visualization of the internal structure of the sample, we can gain a better insight into the observed mechanical behavior. The ability to impart a small, confined load, and perform OCT A-scans at the same time, could lead to an alternative, high transverse resolution, Optical Coherence Elastography (OCE) sensor

High resolution combined molecular and structural optical imaging of colorectal cancer in a xenograft mouse model

With the emergence of immunotherapies for cancer treatment, there is a rising clinical need to visualize the tumor microenvironment (TME) non-invasively in detail, which could be crucial to predict the efficacy of therapy. Nuclear imaging techniques enable whole-body imaging but lack the required spatial resolution. Conversely, near-infrared immunofluorescence (immuno-NIRF) is able to reveal tumor cells and/or other cell subsets in the TME by targeting the expression of a specific membrane receptor with fluorescently labeled monoclonal antibodies (mAb). Optical coherence tomography (OCT) provides three-dimensional morphological imaging of tissues without exogenous contrast agents. The combination of the two allows molecular and structural contrast at a resolution of ~15 µm, allowing for the specific location of a cell-type target with immuno-NIRF as well as revealing the three-dimensional architectural context with OCT. For the first time, combined immuno-NIRF and OCT of a tumor is demonstrated in situ in a xenograft mouse model of human colorectal cancer, targeted by a clinically-safe fluorescent mAb, revealing unprecedented details of the TME. A handheld scanner for ex vivo examination and an endoscope designed for imaging bronchioles in vivo are presented. This technique promises to complement nuclear imaging for diagnosing cancer invasiveness, precisely determining tumor margins, and studying the biodistribution of newly developed antibodies in high detail

PERÍODO DE INDUÇÃO DE BLENDAS DE BIODIESEL DE DIFERENTES FONTES GRAXAS

O presente trabalho teve como objetivo avaliar o efeito da estabilidade a oxidação do biodiesel de soja pela blendagem com outros biodieseis advindos de diferentes fontes graxas amplamente. Para condução do experimento realizou-se planejamento fatorial ao nível 2³ misturando-se biodieseis de soja em diferentes níveis com biodiesel de milho, pequi e gordura suína, todos estes obtidos via transesterificação homogênea alcalina, para avaliação da estabilidade oxidativa (período de indução). A partir dos resultados obtidos pode-se concluir que a blendagem de biodieseis de diferentes origens proporciona variações nas respostas de estabilidade à oxidação do combustível. Enquanto a adição de ésteres advindos de fonte vegetal garantiu melhora na estabilidade oxidativa, ésteres de gordura suína proporcionaram declínio nas respostas obtidas a partir de sua blendagem com o biodiesel de soja

Total synthesis, isolation, surfactant properties, and biological evaluation of ananatosides and related macrodilactone-containing rhamnolipids

Rhamnolipids are a specific class of microbial surfactants, which hold great biotechnological and therapeutic potential. However, their exploitation at the industrial level is hampered because they are mainly produced by the opportunistic pathogenPseudomonas aeruginosa. The non-human pathogenic bacteriumPantoea ananatisis an alternative producer of rhamnolipid-like metabolites containing glucose instead of rhamnose residues. Herein, we present the isolation, structural characterization, and total synthesis of ananatoside A, a 15-membered macrodilactone-containing glucolipid, and ananatoside B, its open-chain congener, from organic extracts ofP. ananatis. Ananatoside A was synthesized through three alternative pathways involving either an intramolecular glycosylation, a chemical macrolactonization or a direct enzymatic transformation from ananatoside B. A series of diasteroisomerically pure (1→2), (1→3), and (1→4)-macrolactonized rhamnolipids were also synthesized through intramolecular glycosylation and their anomeric configurations as well as ring conformations were solved using molecular modeling in tandem with NMR studies. We show that ananatoside B is a more potent surfactant than its macrolide counterpart. We present evidence that macrolactonization of rhamnolipids enhances their cytotoxic and hemolytic potential, pointing towards a mechanism involving the formation of pores into the lipidic cell membrane. Lastly, we demonstrate that ananatoside A and ananatoside B as well as synthetic macrolactonized rhamnolipids can be perceived by the plant immune system, and that this sensing is more pronounced for a macrolide featuring a rhamnose moiety in its native1C4conformation. Altogether our results suggest that macrolactonization of glycolipids can dramatically interfere with their surfactant properties and biological activity

Inter-Individual Variability in tDCS Effects: A Narrative Review on the Contribution of Stable, Variable, and Contextual Factors

Due to its safety, portability, and cheapness, transcranial direct current stimulation (tDCS) use largely increased in research and clinical settings. Despite tDCS’s wide application, previous works pointed out inconsistent and low replicable results, sometimes leading to extreme conclusions about tDCS’s ineffectiveness in modulating behavioral performance across cognitive domains. Traditionally, this variability has been linked to significant differences in the stimulation protocols across studies, including stimulation parameters, target regions, and electrodes montage. Here, we reviewed and discussed evidence of heterogeneity emerging at the intra-study level, namely inter-individual differences that may influence the response to tDCS within each study. This source of variability has been largely neglected by literature, being results mainly analyzed at the group level. Previous research, however, highlighted that only a half—or less—of studies’ participants could be classified as responders, being affected by tDCS in the expected direction. Stable and variable inter-individual differences, such as morphological and genetic features vs. hormonal/exogenous substance consumption, partially account for this heterogeneity. Moreover, variability comes from experiments’ contextual elements, such as participants’ engagement/baseline capacity and individual task difficulty. We concluded that increasing knowledge on inter-dividual differences rather than undermining tDCS effectiveness could enhance protocols’ efficiency and reproducibility