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Cartilage Dec 2021Spectroscopic techniques, such as near-infrared (NIR) spectroscopy, are gaining significant research interest for characterizing connective tissues, particularly...
OBJECTIVE
Spectroscopic techniques, such as near-infrared (NIR) spectroscopy, are gaining significant research interest for characterizing connective tissues, particularly articular cartilage, because there is still a largely unmet need for rapid, accurate and objective methods for assessing tissue integrity in real-time during arthroscopic surgery. This study aims to identify the NIR spectral range that is optimal for characterizing cartilage integrity by () identifying the contribution of its major constituents (collagen and proteoglycans) to its overall spectrum using proxy constituent models and () determining constituent-specific spectral contributions that can be used for assessment of cartilage in its physiological state.
DESIGN
The NIR spectra of cartilage matrix constituent models were measured and compared with specific molecular components of organic compounds in the NIR spectral range in order to identify their bands and molecular assignments. To verify the identified bands, spectra of the model compounds were compared with those of native cartilage. Since water obscures some bands in the NIR range, spectral measurements of the native cartilage were conducted under conditions of decreasing water content to amplify features of the solid matrix components. The identified spectral bands were then compared and examined in the resulting spectra of the intact cartilage samples.
RESULTS
As water was progressively eliminated from cartilage, the specific contribution of the different matrix components was observed to correspond with those identified from the proxy cartilage component models.
CONCLUSION
Spectral peaks in the regions 5500 to 6250 cm and 8100 to 8600 cm were identified to be effective for characterizing cartilage proteoglycan and collagen contents, respectively.
Topics: Arthroscopy; Cartilage, Articular; Collagen; Proteoglycans; Spectroscopy, Near-Infrared
PubMed: 34643470
DOI: 10.1177/19476035211035417 -
Materials (Basel, Switzerland) Feb 2020Monophasic ZnFeO nanoparticles with wurtzite structure were synthesized in the 0 ≤ x ≤ 0.05 concentration range using a freeze-drying process followed by heat...
Monophasic ZnFeO nanoparticles with wurtzite structure were synthesized in the 0 ≤ x ≤ 0.05 concentration range using a freeze-drying process followed by heat treatment. The samples were characterized regarding their optical, structural, and magnetic properties. The analyses revealed that iron doping of the ZnO matrix induces morphological changes in the crystallites. Iron is substitutional for zinc, trivalent and distributed in the wurtzite lattice in two groups: isolated iron atoms and iron atoms with one or more neighboring iron atoms. It was also shown that the energy band gap decreases with a higher doping level. The samples are paramagnetic at room temperature, but they undergo a spin-glass transition when the temperature drops below 75 K. The magnetic frustration is attributed to the competition of magnetic interactions among the iron moments. There are a superexchange interaction and an indirect exchange interaction that is provided by the spin (and charge) itinerant carriers in a spin-polarized band situated in the vicinity of the Fermi level of the Fe-doped ZnO semiconductor. The former interaction actuates for an antiferromagnetic coupling among iron ions, whereas the latter constitutes a driving force for a ferromagnetic coupling that weakens, decreasing the temperature. Our results strongly contribute to the literature because they elucidate the controversies reported in the literature for the magnetic state of the Fe-doped ZnO system.
PubMed: 32075143
DOI: 10.3390/ma13040869 -
Sensors (Basel, Switzerland) Mar 2024In satellite remote sensing (SRS), there is a demand for large-power microwave components. A Butler matrix is essential to a transmitting antenna array in SRS. This...
In satellite remote sensing (SRS), there is a demand for large-power microwave components. A Butler matrix is essential to a transmitting antenna array in SRS. This article illustrates the electrical and mechanical design, simulation, and test results of a large-power planar beamforming network for SRS at C-band. It is a 4 × 4 Butler matrix based on square coaxial lines. Short-ended stubs are used in the Butler matrix to broaden its bandwidth by 10%, support inner conductors, and enhance heat transfer in vacuum environments. The simulation results are consistent with the measured results. The reflection coefficient is less than -18 dB, and the isolation is more than 23 dB from 3.8 GHz to 4.2 GHz. The insertion losses are less than 0.6 dB, and the phase errors are better than ±6°. The measured peak microwave power of the proposed Butler matrix is 9 kW. Its size is 440 × 400 × 40 mm. The proposed Butler matrix beamforming network can be applied to SRS systems.
PubMed: 38610343
DOI: 10.3390/s24072132 -
Nanomaterials (Basel, Switzerland) Jul 2023Transparent conductors (TC) have been widely applied in a wide range of optoelectronic devices. Nevertheless, different transparent spectral bands are always needed for...
Transparent conductors (TC) have been widely applied in a wide range of optoelectronic devices. Nevertheless, different transparent spectral bands are always needed for particular applications. In this work, indium tin oxide (ITO)-free TCs with tunable transparent bands based on the film structure of TiO/Ag/AZO (Al-doped ZnO) were designed by the transfer matrix method and deposited by magnetron sputtering. The transparent spectra and figure-of-merit (FOM) were effectively adjusted by precisely controlling the Ag layer's thickness. The fabricated as-deposited samples exhibited an average optical transmittance larger than 88.3% (400-700 nm), a sheet resistance lower than 7.7 Ω.sq, a low surface roughness of about 1.4 nm, and mechanical stability upon 1000 bending cycles. Moreover, the samples were able to hold optical and electrical properties after annealing at 300 °C for 60 min, but failed at 400 °C even for 30 min.
PubMed: 37513119
DOI: 10.3390/nano13142108 -
Molecules (Basel, Switzerland) Nov 2022Monomers of -fluorophenol (FP) were trapped from the gas phase into cryogenic argon and nitrogen matrices. The estimated relative energies of the two conformers are very...
Monomers of -fluorophenol (FP) were trapped from the gas phase into cryogenic argon and nitrogen matrices. The estimated relative energies of the two conformers are very close, and in the gas phase they have nearly equal populations. Due to the similarity of their structures (they only differ in the orientation of the OH group), the two conformers have also similar predicted vibrational signatures, which makes the vibrational characterization of the individual rotamers challenging. In the present work, it has been established that in an argon matrix only the most stable conformer of FP exists (the OH group pointing away from the fluorine atom). On the other hand, the IR spectrum of FP in a nitrogen matrix testifies to the simultaneous presence in this matrix of both the conformer and of the higher-energy conformer (the OH group pointing toward the fluorine atom), which is stabilized by interaction with the matrix gas host. We found that the exposition of the cryogenic N matrix to the Globar source of the infrared spectrometer affects the conformational populations. By collecting experimental spectra, either in the full mid-infrared range or only in the range below 2200 cm, we were able to reliably distinguish two sets of experimental bands originating from individual conformers. A comparison of the two sets of experimental bands with computed infrared spectra of the conformers allowed, for the first time, the unequivocal vibrational identification of each of them. The joint implementation of computational vibrational spectroscopy and matrix-isolation infrared spectroscopy proved to be a very accurate method of structural analysis. Some mechanistic insights into conformational isomerism (the quantum tunneling of hydrogen atom and vibrationally-induced conformational transformations) have been addressed. Finally, we also subjected matrix-isolated FP to irradiations with UV light, and the phototransformations observed in these experiments are also described.
Topics: Argon; Nitrogen; Molecular Conformation; Spectrophotometry, Infrared; Ultraviolet Rays
PubMed: 36500356
DOI: 10.3390/molecules27238248 -
Clinical Neurophysiology : Official... Apr 2023The aim of this study is to explore whether cortical activation and its lateralization during motor imagery (MI) in subacute spinal cord injury (SCI) are indicative of...
OBJECTIVE
The aim of this study is to explore whether cortical activation and its lateralization during motor imagery (MI) in subacute spinal cord injury (SCI) are indicative of existing or upcoming central neuropathic pain (CNP).
METHODS
Multichannel electroencephalogram was recorded during MI of both hands in four groups of participants: able-bodied (N = 10), SCI and CNP (N = 11), SCI who developed CNP within 6 months of EEG recording (N = 10), and SCI who remained CNP-free (N = 10). Source activations and its lateralization were derived in four frequency bands in 20 regions spanning sensorimotor cortex and pain matrix.
RESULTS
Statistically significant differences in lateralization were found in the theta band in premotor cortex (upcoming vs existing CNP, p = 0.036), in the alpha band at the insula (healthy vs upcoming CNP, p = 0.012), and in the higher beta band at the somatosensory association cortex (no CNP vs upcoming CNP, p = 0.042). People with upcoming CNP had stronger activation compared to those with no CNP in the higher beta band for MI of both hands.
CONCLUSIONS
Activation intensity and lateralization during MI in pain-related areas might hold a predictive value for CNP.
SIGNIFICANCE
The study increases understanding of the mechanisms underlying transition from asymptomatic to symptomatic early CNP in SCI.
Topics: Humans; Spinal Cord Injuries; Neuralgia; Electroencephalography; Pain Measurement; Motor Cortex
PubMed: 36796284
DOI: 10.1016/j.clinph.2023.01.006 -
JPMA. the Journal of the Pakistan... Feb 2024To evaluate composite class II restoration proximal contacts and contours by comparing saddlecontoured metal matrix and pre-contoured self-adhesive matrix system. (Randomized Controlled Trial)
Randomized Controlled Trial
OBJECTIVE
To evaluate composite class II restoration proximal contacts and contours by comparing saddlecontoured metal matrix and pre-contoured self-adhesive matrix system.
METHODS
The randomised controlled trial (NCT05414656) was conducted at the Department of Operative Dentistry, School of Dentistry, Shaheed Zulfiqar Ali Bhutto Medical University, Pakistan Institute of Medical Sciences, Islamabad, Pakistan, from May to October 2022, and comprised of patients having supra-gingival class II cavities. They were randomised into class II restoration with saddle-contoured matrix band group A, and restoration with pre-contoured self-adhesive matrix group B. The tightness of proximal contacts was evaluated using the Fédération Dentaire Internationale criteria and the quality of proximal contours was assessed using clinical and radiographic examination. Data was analysed using SPSS 16.
RESULTS
Of the 60 subjects, 42(70%) were females and 18(30%) were males. The overall mean age was 38.03±15.33 years. There were 30(50%) subjects in each of the 2 groups. The highest restoration was needed in the upper premolar 20(33.3%). The tightness of proximal contact was not significantly different between the groups (p=0.94). Clinical examination for production of good contours was higher in group A compared to group B, but the difference was not significant (p>0.05).
CONCLUSIONS
There was no significant difference between saddle-contoured metal matrix and pre-contoured selfadhesive matrix for composite class II restoration proximal contacts and contours.
CLINICAL TRIAL LINK
https://clinicaltrials.gov RCT (NCT05414656).
Topics: Male; Female; Humans; Young Adult; Adult; Middle Aged; Composite Resins; Resin Cements; Matrix Bands; Research Design; Bicuspid; Dental Restoration, Permanent
PubMed: 38419215
DOI: 10.47391/JPMA.8627 -
Scientific Reports Aug 2023Lieb lattice is one of the simplest bipartite lattices, where compact localized states (CLS) are observed. This type of localization is induced by the peculiar topology...
Lieb lattice is one of the simplest bipartite lattices, where compact localized states (CLS) are observed. This type of localization is induced by the peculiar topology of the unit cell, where the modes are localized only on selected sublattices due to the destructive interference of partial waves. We demonstrate the possibility of magnonic Lieb lattice realization, where flat bands and CLS can be observed in the planar structure of sub-micron in-plane sizes. Using forward volume configuration, the Ga-doped YIG layer with cylindrical inclusions (without Ga content) arranged in a Lieb lattice with 250 nm period was investigated numerically (finite-element method). The structure was tailored to observe, for a lowest magnonic bands, the oscillatory and evanescent spin waves in inclusions and matrix, respectively. Such a design reproduces the Lieb lattice of nodes (inclusions) coupled to each other by the matrix with the CLS in flat bands.
PubMed: 37542063
DOI: 10.1038/s41598-023-39816-w -
Plant Methods Feb 2021The cuticle is a protective layer playing an important role in plant defense against biotic and abiotic stresses. So far cuticle structure and chemistry was mainly...
BACKGROUND
The cuticle is a protective layer playing an important role in plant defense against biotic and abiotic stresses. So far cuticle structure and chemistry was mainly studied by electron microscopy and chemical extraction. Thus, analysing composition involved sample destruction and the link between chemistry and microstructure remained unclear. In the last decade, Raman imaging showed high potential to link plant anatomical structure with microchemistry and to give insights into orientation of molecules. In this study, we use Raman imaging and polarization experiments to study the native cuticle and epidermal layer of needles of Norway spruce, one of the economically most important trees in Europe. The acquired hyperspectral dataset is the basis to image the chemical heterogeneity using univariate (band integration) as well as multivariate data analysis (cluster analysis and non-negative matrix factorization).
RESULTS
Confocal Raman microscopy probes the cuticle together with the underlying epidermis in the native state and tracks aromatics, lipids, carbohydrates and minerals with a spatial resolution of 300 nm. All three data analysis approaches distinguish a waxy, crystalline layer on top, in which aliphatic chains and coumaric acid are aligned perpendicular to the surface. Also in the lipidic amorphous cuticle beneath, strong signals of coumaric acid and flavonoids are detected. Even the unmixing algorithm results in mixed endmember spectra and confirms that lipids co-locate with aromatics. The underlying epidermal cell walls are devoid of lipids but show strong aromatic Raman bands. Especially the upper periclinal thicker cell wall is impregnated with aromatics. At the interface between epidermis and cuticle Calcium oxalate crystals are detected in a layer-like fashion. Non-negative matrix factorization gives the purest component spectra, thus the best match with reference spectra and by this promotes band assignments and interpretation of the visualized chemical heterogeneity.
CONCLUSIONS
Results sharpen our view about the cuticle as the outermost layer of plants and highlight the aromatic impregnation throughout. In the future, developmental studies tracking lipid and aromatic pathways might give new insights into cuticle formation and comparative studies might deepen our understanding why some trees and their needle and leaf surfaces are more resistant to biotic and abiotic stresses than others.
PubMed: 33557869
DOI: 10.1186/s13007-021-00717-6 -
Materials (Basel, Switzerland) Aug 2021Micro mechanism consideration is critical for gaining a thorough understanding of amorphous shear band behavior in magnetorheological (MR) solids, particularly those...
Micro mechanism consideration is critical for gaining a thorough understanding of amorphous shear band behavior in magnetorheological (MR) solids, particularly those with viscoelastic matrices. Heretofore, the characteristics of shear bands in terms of formation, physical evolution, and response to stress distribution at the localized region have gone largely unnoticed and unexplored. Notwithstanding these limitations, atomic force microscopy (AFM) has been used to explore the nature of shear band deformation in MR materials during stress relaxation. Stress relaxation at a constant low strain of 0.01% and an oscillatory shear of defined test duration played a major role in the creation of the shear band. In this analysis, the localized area of the study defined shear bands as varying in size and dominantly deformed in the matrix with no evidence of inhibition by embedded carbonyl iron particles (CIPs). The association between the shear band and the adjacent zone was further studied using in-phase imaging of AFM tapping mode and demonstrated the presence of localized affected zone around the shear band. Taken together, the results provide important insights into the proposed shear band deformation zone (SBDZ). This study sheds a contemporary light on the contentious issue of amorphous shear band deformation behavior and makes several contributions to the current literature.
PubMed: 34442907
DOI: 10.3390/ma14164384