SUMMARY
In the field, kimberlites are characterized by high electrical conductivities (about 0.1 S m−1) compared to most igneous rocks. The reason for these high conductivities has not been fully ...elucidated to date. We investigate here the spectral induced polarization of seven core samples of kimberlites in the frequency range 1.43 mHz–20 kHz. The measurements are made at pore water conductivities ranging from 0.07 to 2.4 S m−1 (NaCl, 25 °C). We also measured the cation exchange capacity (CEC), the specific surface area (SSA) and the magnetic susceptibility of the core samples. We characterized the samples by optical microscopy as well as the X-ray diffraction and thermogravimetric analyses. Based on the electrical measurements, we obtained values of the surface conductivity produced by the double electrical layer coating the solid particles, and the normalized chargeability values characterizing the polarization magnitude of these materials. Mineralogical analyses show significant amount of magnetite (from 2 to 9 wt. per cent, approximately 1 to 4 per cent in vol. content) and smectite (from 1 to 44 wt. per cent) in the core samples. The main contributor of the CEC is smectite because of its very high CEC. The quadrature conductivity, the normalized chargeability, and the surface conductivity are controlled by the CEC normalized by the tortuosity of the pore space (product of the formation factor by the porosity). Our data demonstrate that the conduction and polarization of kimberlites are both controlled by the presence of smectite rather than associated with magnetite. Comparing the new data set and data recently obtained with volcanic rocks from both shield and strato-volcanoes in the previous papers of this series, we show that the model of polarization of the dynamic Stern layer correctly describes the complex electrical conductivity of kimberlites as well. Our results also explain the cause of electrical conductivity anomalies detected at kimberlite pipes and offer new perspectives in using induced polarization method for the exploration of kimberlites around the world.
Summary Background The cause of follicular occlusion, a key early event in the pathogenesis of hidradenitis suppurativa (HS), also known as acne inversa, remains unknown.
Objectives To identify ...changes, if any, in the antimicrobial peptide (AMP) and cytokine expression profile of HS affected human skin.
Methods Quantitative immunohistomorphometry was used to compare the in situ protein expression of selected AMPs and cytokines in lesional HS skin from 18 patients with that in healthy skin (n = 12). The lesional skin from patients with HS was histologically subclassified based on the predominance of inflammation vs. scarring.
Results Compared with healthy controls, significantly increased immunoreactivity for cathelicidin (LL‐37) was noted in the apocrine sweat gland and distal outer root sheath (ORS) of the hair follicle (HF) epithelium in lesional HS skin. Immunoreactivity for LL‐37, psoriasin, human β‐defensin 3 (hBD3), α‐melanocyte stimulating hormone (α‐MSH), macrophage migration inhibitory factor (MIF), tumour necrosis factor (TNF)‐α and interleukin (IL)‐8 was significantly increased in HS epidermis. LL‐37 and TNF‐α immunoreactivity was also increased in the dermis of lesional HS skin. In contrast, lysozyme expression was decreased in the epidermis of lesional HS skin, while that of TNF‐α and IL‐8 was decreased in the proximal ORS of HFs in HS lesions. These differences were most pronounced in HS with predominant inflammation.
Conclusions Our observations raise the question as to whether excessive secretion of AMPs by the skin, in particular by the apocrine sweat glands, distal HF epithelium, and epidermis, may attract inflammation and thus facilitate or promote HS development.
Biosensors based on graphene and bio‐graphene interfaces have gained momentum in recent years due to graphene's outstanding electronic and mechanical properties. By introducing the patterning of a ...single‐layer graphene surface by two‐photon oxidation (2PO), the surface hydrophobicity/hydrophilicity and doping can be varied at the nanoscale while preserving the carbon network, thus opening possibilities to design new devices. In this study, the effect of 2PO on the catalytic activity of the noncovalently immobilized enzyme horseradish peroxidase (HRP) on single‐layer graphene‐coated Si/SiO2 chips is presented. To monitor the activity continuously, a simple well‐plate setup is introduced. Upon controllable 1–2‐layer immobilization, the catalytic activity decreases to a maximum value of 7.5% of the free enzyme. Interestingly, the activity decreases with increasing 2PO area on the samples. Hence, the HRP catalytic activity on the graphene surface is locally controlled. This approach can enable the development of graphene‐bio interfaces with locally varying enzyme activity.
The study investigates the catalytic performance of horseradish peroxidase immobilized on pristine and laser‐oxidized graphene surfaces in a 1–2‐layer range. UV–vis spectroscopy is employed to track substrate oxidation. The results show a higher catalytic reaction rate on the pristine surface compared to the laser‐oxidized one, revealing surface‐related effects on the enzyme.
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•Simple design of hot carrier solar cell with double heterostructure.•Electrochemical fabrication of InP/PbSe heterostructure.•Valence band offset 0.3eV and conduction band offset ...0.8eV for InP/PbSe interface.•Double beam experiment for probing carrier–carrier energy transfer.•Optoelectrical observation of hot carrier extraction at room temperature.
Energy filtering of hot carriers in a solar cell may be attained by using band offsets at heterointerfaces. This rough energy filtering does not require special sophisticated energy filtering contacts, and may be implemented in the form of a double heterojunction. PbSe thin film as absorber layer was electrodeposited on InP single crystal. Experimental evidence of hot carrier filtering at InP/PbSe heterointerface at room temperature was obtained by double beam optoelectrical measurements. The measurements can be interpreted by thermionic emission over the band offset barriers. The valence band offset of 0.3eV at the InP/PbSe heterointerface was measured by X-ray Photoelectron Spectroscopy. The filtering process may become useful for new generation of hot carrier solar cells.
The graphene oxide (GO) film embossing and reduction was demonstrated under femtosecond laser pulses. The best conductivity of laser reduced GO film of 200Ω/□ was achieved for fs laser pulses energy ...of 35–45nJ and 10–25 pulses per µm. We demonstrate the patterned laser reduction over the embossed GO film that holds it integrity and conductivity. Laser reduced GO properties was studied by Raman, SEM and sheet resistance measurements.
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•Laser direct patterning of reduced GO was produced from 500nm GO film on flexible (PET) substrate by femtosecond pulses.•For thick LrGO film there is a minimum in resistance while linear crystalline quality increases with laser fluence.•Laser induced embossing of GO provides 3D formation with details aspect ratio as 1:10.•Two-step laser-induced detachment of GO patches from polymer substrates is shown.
Mycotoxins comprise a frequent type of toxins present in food and feed. The problem of mycotoxin contamination has been recently aggravated due to the increased complexity of the farm-to-fork chains, ...resulting in negative effects on human and animal health and, consequently, economics. The easy-to-use, on-site, on-demand, and rapid monitoring of mycotoxins in food/feed is highly desired. In this work, we report on an advanced mycotoxin biosensor based on an array of graphene field-effect transistors integrated on a single silicon chip. A specifically designed aptamer against ochratoxin A (OTA) was used as a recognition element, where it was covalently attached to graphene surface via pyrenebutanoic acid, succinimidyl ester (PBASE) chemistry. Namely, an electric field stimulation was used to promote more efficient π-π stacking of PBASE to graphene. The specific G-rich aptamer strand suggest its π-π stacking on graphene in free-standing regime and reconfiguration in G-quadruplex during binding an OTA molecule. This realistic behavior of the aptamer is sensitive to the ionic strength of the analyte solution, demonstrating a 10-fold increase in sensitivity at low ionic strengths. The graphene-aptamer sensors reported here demonstrate fast assay with the lowest detection limit of 1.4 pM for OTA within a response time as low as 10 s, which is more than 30 times faster compared to any other reported aptamer-based methods for mycotoxin detection. The sensors hold comparable performance when operated in real-time within a complex matrix of wine without additional time-consuming pre-treatment.
•Biosensor based on an microarray of aptamer-conjugated graphene field-effect transistors was developed.•Real-time highly responsive and rapid detection of Ochratoxin A is achieved.•Ionic strength effect on sensitivity to OTA in buffer is demonstrated.•Realistic scheme of aptamer G-quadruplex conformation upon small toxin molecules binding is proposed.•On-chip device enables in-field detection of OTA trace in wine within 50 s.
Ultrafast laser processing has emerged as a versatile technique for modifying materials and introducing novel functionalities. Over the past decade, this method has demonstrated remarkable advantages ...in the manipulation of 2D layered materials, including synthesis, structuring, functionalization, and local patterning. Unlike continuous‐wave and long‐pulsed optical methods, ultrafast lasers offer a solution for thermal heating issues. Nonlinear interactions between ultrafast laser pulses and the atomic lattice of 2D materials substantially influence their chemical and physical properties. This paper highlights the transformative role of ultrafast laser pulses in maskless green technology, enabling subtractive, and additive processes that unveil ways for advanced devices. Utilizing the synergetic effect between the energy states within the atomic layers and ultrafast laser irradiation, it is feasible to achieve unprecedented resolutions down to several nanometers. Recent advancements are discussed in functionalization, doping, atomic reconstruction, phase transformation, and 2D and 3D micro‐ and nanopatterning. A forward‐looking perspective on a wide array of applications of 2D materials, along with device fabrication featuring novel physical and chemical properties through direct ultrafast laser writing, is also provided.
This paper explores the cutting‐edge use of ultrafast laser technology to precisely modify 2D materials. It presents a leap from theory to real‐world applications, demonstrating how ultrafast lasers can tailor material properties for advanced devices. This method offers nanometer precision without heat‐related issues, revolutionizing novel electronic, photonic, and sensing devices design, making it a key tool for future innovations.
The paper presents data on the anisotropic complex dielectric permeability of nematic LC-1289 in microwave range. The obtained data allow us to build a Cole-Cole diagram. It indicates the existence ...of two dispersion regions for transversal permittivity and one dispersion region for longitudinal permittivity and corresponding relaxation times.
The effect of the synthetic compound 2-morpholino-5-phenyl-6
H
-1,3,4-thiadiazine hydrochloride (L17) on rats with a streptozotocin-nicotinamide model of type 2 diabetes mellitus (DM2) was studied. ...The experiment was performed on 50 male Wistar rats. L17 was administered intramuscularly to diabetic rats at a dose of 40 mg/kg. Modeling DM2 revealed hyperglycemia, accumulation of glycated hemoglobin (HbA
1c
) and malondialdehyde (MDA); a decreased content of thiols; and compensatory activation of antioxidant defense (AOD) enzymes superoxide dismutase (SOD), catalase, glutathione peroxidase in erythrocytes. Administration of L17 to diabetic rats was accompanied by a decrease in hyperglycemia, normalization of HbA
1c
and MDA levels and AOD enzyme activity, and prevention of thiol depletion. Correction of hyperglycemia and imbalance in the free-radical oxidation(AOD system in the experiment made further study of the mechanism of the antidiabetic action of L17 promising.
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