Borges-Martinez, MerlysMontenegro-Pohlhammer, NicolasZhang, XianceGalvez-Aranda, Diego E....
13页
查看更多>>摘要：We evaluate the fullerene C-60 binding effect; through the metal (Al) and through the ligand (Pc,TPP), on the photophysical and charge transport properties of M-porphyrin(TPP)/phthalocyanine(Pc) (M = Al(III), Zn (II)). We perform density functional theory (DFT) and time-dependent DFT calculations for the macrocycle-C-60 dyads, showing that all systems studied are thermodynamically favorable. The C-60 binding effect on the absorption spectrum is a red-shift of the Q and Soret (B) bands of TPPs and Pcs. The Pc dyads show longer k for Q bands (673 nm) than those with TPP (568 nm). AlTPP-C-60 and ZnTPP-C-60 show a more favorable electron injection to TiO2 than the analogs Pcs, and the regeneration of the dye is preferred in AlTPP-C-60 and AlPc-C-60. Zero-bias conductance is computed (10(-4)-10(-7) G(0)) for the dyads using molecular junctions with Au(1 1 1)-based electrodes. When a bias voltage of around 0.6 V up to 1 V is applied, an increase in current is obtained for AlTPP-C-60 (10(-7) A), ZnTPP-C-60 (10(-7) A), and AlPc-C-60 (10(-8) A). Although there is not a unique trend in the behavior of the dyads, Pcs have better photophysical properties than TPPs and the latter are better in the charge transport. We conclude that AlTPP(ZnTPP)-C-60 dyads are an excellent alternative for designing new materials for dye-sensitized solar cells or optoelectronic devices. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Molecules with Aggregation-Induced Emission (AIE) effects could show strong emission in solid or aggregate form, thus they are suitable for applications in the field of solid luminescent materials. According to former reporting, AIE molecules are always J-aggregates. In this study, a new benzotriazole derivate with electron donor-acceptor structure was synthesized. (E)-4-(2-(1H-benzo[d] [1,2,3] triazol-1-yl) vinyl)-N, N-dimethylaniline (BTADA) has both TICT and AIE effect, even though it is H-aggregate. Furthermore, BTADA could respond to proton in solution and solid form. Due to its multiple binging sites, proton would bind to benzotriazole and dimethylaniline moiety successively when BTADA was exposed to acid, and the fluorescent color changed from green to yellow then blue as the concentration of proton increased. Such phenomena indicate BTADA has potential usage in proton detection. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：In-situ synchrotron X-ray diffraction and Raman spectroscopy were used to study the stabilities, thermal expansion and vibrational modes of synthetic Mg-3(PO4)(2). The polymorphs (Mg-3(PO4)(2)-I, II, III) were investigated in the temperature range of 299 similar to 1173 K at ambient pressure. An irreversible phase transition was observed for both Mg-3(PO4)(2)-II and Mg-3(PO4)(2)-III, whereas Mg-3(PO4)(2)-I is stable in the present study. Based on the in-situ synchrotron X-ray diffraction and Raman spectroscopic measurements, Mg-3(PO4)2-II and Mg-3(PO4)(2)-III transform to Mg-3(PO4)(2)-I at 1073 K and 1023 K, respectively. The volumetric thermal expansion coefficients of Mg-3(PO4)(2)-I, II and III were determined as 3.31(4) x 10(-5) K-1, 3.91(4) x 10(-5) K-1, and 3.25(5) x 10(-5) K-1, respectively. All three Mg-3(PO4)(2) polymorphs show axial thermal expansive anisotropy since the thermal expansion coefficients along different axes are inconsistent. The effect of temperature on the Raman vibrations of the three Mg-3(PO4)(2) polymorphs was quantitatively analyzed. And the isobaric mode Grfineisen parameters of three Mg-3(PO4)(2) polymorphs are calculated, which are in the range of 0.07 similar to 3.54. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：The superoxide anion radical (O-2(center dot)), a pernicious ROS in living cells, has long been recognized as an important cell signaling molecule involved in numerous physiological and pathological processes, including innate immunity and metabolic homeostasis. Here, we developed a new bodipy-based fluorescent probe for monitoring O-2(center dot) based on the selective cleavage of phosphate bond in BODIPY-T by O-2(center dot) , producing a high-brightness fluorescent BODIPY-COOH. The probe exhibits excellent selectivity for O-2(center dot) with little interference from other ROS species. Fluorescence imaging of RAW264.7 cells also demonstrated successful detection of endogenous O-2(center dot) changes in living cells, indicating that BODIPY-T is a potential probe for the diagnosis and study of the corresponding diseases. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：The task of assembling and calculating spectrally significant lines of Vitamin D2 and D3 is related to a wider goal of establishing if it is possible to develop non-invasive optical sensors for these substances present at concentrations on the order of tens of nmol/L. Such a non-invasive in vivo sensor would be helpful for medical considerations, among others, related to multiple sclerosis prevention, reduced risk of mortality in D3-treated acute in-patients admitted with COVID 19, systemic infection, acute respiratory tract infections, including epidemic influenza, community-acquired pneumonia at concentrations < 50 nmol/L (< 20 ng/mL), dental health (90 - 100 nmol/L) of 25(OH) D, general health and others. Currently, to determine the concentration of these substances, it is necessary to draw a sample from a vein in ambulatory settings and analyse the sample with the gold standard of mass spectroscopy or immunoassay. In this article Vitamin D optical properties are studied by density functional theory calculations, compared to reported data, and the new calculated and measured D2 and D3 optical absorption lines are presented, as well as the calculations compared with spectral measurements of optical transmission, FTIR ATR and Raman spectra. (C) 2021 Elsevier B.V. All rights reserved.
Andrikopoulos, K. S.Chrissanthopoulos, A.Beobide, A. SotoIconomopoulou, S. M....
11页
查看更多>>摘要：The current work reports on a systematic study related to the vibrational modes of the ester carbonyl group in drawn polyesters. We have observed and try to explain how the presence of aromatic units in the molecular structure substantially affects the respective elements of the Raman tensor in contrast to the dipole moment derivative vector which is only marginally influenced. The work is based on the collection of polarized Raman spectra and FTIR dichroism measurements on the one hand and on DFT calculations on the other. The experimental data were obtained from uniaxially stretched aliphatic and semi-aromatic polyesters. The calculations were applied on relevant oriented oligomers and allowed the extraction: (i) of reliable Raman/FTIR vibrational spectra and (ii) the components of the dipole moment derivative and Raman tensor of the vibrational modes and in particular the ones involving the ester carbonyl group. Experimental data indicate that the intensity of the ester carbonyl band is considerably enhanced in the Raman spectra of semi-aromatic polyesters, which results from a considerable enhancement of the related coupling coefficient. Furthermore, the angles of the principle Raman tensor axis are rotated so that the element of the tensor with the greatest value is oriented towards the direction designated by the segment. The latter explains the peculiar experimentally indicated anisotropy, through the ester carbonyl stretching, for the case of semi-aromatic polyesters, which is totally different with that observed in the aliphatic ones. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Atractylodes macrocephala Koidz. (AM) is an important plant of traditional Chinese medicine (TCM), and its status can be comparable with ginseng in China. The efficacy and quality of AM are closely related to the place of origin. Hence, we proposed a simple and fast strategy to classify AM from different geographical origins by using multi-way fluorescence fingerprint combined with chemometric methods. AM samples with different dilution levels have different fluorescence characteristics, resulting from different content of fluorescence components and chemical microenvironment. Therefore, AM samples were diluted 5-fold, 10-fold, and 20-fold with 40% ethanol aqueous solution to obtain excitation-emission matrix data, and multi-way (three-way and four-way) data arrays were constructed. And then, the fluorescence fingerprints of AM samples were characterized by three-way and four-way parallel factor analysis (PARAFAC). In addition, four pattern recognition methods were used to classify AM from different provinces. The results show that the four-way data array can provide more abundant information than three-way data arrays, so it is more conducive to sample classification. According to the results obtained from the analysis of four-way data array, the correct classification rate (CCR) of the cross-validation and prediction set obtained by partial least squares-discrimination analysis (PLS-DA) were 90.5% and 100%, respectively. To sum up, the proposed method can be regarded as a powerful, feasible, convenient, reliable, and universal classification tool for the classification of AM samples from different provinces and can be used as a promising method to realize the geographical origin traceability of other TCMs. (c) 2021 Published by Elsevier B.V.
查看更多>>摘要：Herein, a facile self-assembly through adenosine monophosphate (AMP) and luminol with Tb3+ was employed to construct a dual-ligand coordinated AMP-Tb-luminol coordination polymers (CPs), which emitted the typical fluorescence of luminol. Based on the sensitization effect of ciprofloxacin (CIP) on the luminescence of Tb3+, a ratiometric sensor was fabricated using the fluorescence of luminol as an inert reference. The fluorescent intensity ratios of Tb3+ to that of luminol enhanced linearly with the CIP concentration in the range from 5 nM to 2.5 mu M with a lower limit of detection of 2 nM. In addition, the proposed ratiometric fluorescent sensor exhibited high selectivity for CIP, which could also be used to detect CIP in human blood serum (HBS) with satisfactory results. To our knowledge, this is the first demonstration of using dual-ligand coordination lanthanide (Ln)-based CPs for ratio-metric CIP assay, and this straightforward strategy may open up a new platform for designing the ratio-metric sensors based on the Ln CPs. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：It is highly desirable to develop a simple, efficient and sensitive strategy for organophosphorus pesticides (OPs) in both environment pollution and human health. Herein, a novel amplified fluorescence polarization (FP) biosensor was established for highly sensitive detection of OPs using MnO2 nanosheets as the signal enhancer. In this system, OPs can suppress the activity of acetylcholinesterase (AChE) efficiently, blocking the hydrolysis reaction of acetylthiocholine (ATCh) to generate thiocholine (TCh) by AChE. TCh can lead the decomposition of MnO2 nanosheets to manganese ions. So, without the influence of TCh, MnO2 nanosheets can maintain its original shape and form a stable complex with FAM-DNA, which greatly enhanced the FP signal. This method can tremendously improve the sensitivity of FP with a detection limit of 0.01 ng/mL for diazinon. In addition, it was also applicable to determine other four OPs and investigate the level of diazinon in real water samples. Consequently, the proposed approach provides a new promising platform for detection of OPs and is expected to be used in application of environmental monitoring. (C) 2021 Published by Elsevier B.V.
查看更多>>摘要：Anti-tuberculosis fixed-dose combinatorial formulation (FDCs) is an effective drug for the treatment of tuberculosis. As a compound medicine, its efficacy is based on the comprehensive action of multiple main ingredients. If the content of an active ingredient is insufficient, not only will it reduce the curative effect, but it also causes patients to develop drug resistance and leads to the evolution of drug-resistant strains of tuberculosis, which hamper the treatment of the disease. Thus accurate detection of the contents of active components in the anti-tuberculosis FDC is the key link of its quality control. For the first time, convolutional neural networks (CNN), one of the most popular deep learning methods, is adopted to develop a quantitative calibration model based on terahertz time-domain spectroscopy (THz-TDS) for the accurate detection of the content of each active component in the anti-tuberculosis FDCs. For comparison with CNN, partial least squares regression (PLSR) was also introduced to build a reference quantitative calibration model. For CNN modeling, the raw THz spectral is fed to the model directly; While for PLSR, prior to the spectrum feeding to the model, the raw spectral data are processed by multiple different combinations of preprocessing. Experimental and simulation results demonstrate that although preprocessing techniques can improve the prediction performance of PLSR, its prediction capabilities is still inferior to CNN based on raw spectrum. Therefore, for the quantitative analysis of the content of each active component in the anti-tuberculosis FDCs, CNN appears to be an ideal modeling method. (C) 2021 Elsevier B.V. All rights reserved.
NSTL
Elsevier