National Institute Of Materials Physics - Romania

This study aims to investigate the impact of clays on the quality of the Nubia reservoir in the Saqqara field, Gulf of Suez, Egypt. The research will contribute to a broader knowledge of reservoir characterization, offering valuable insights for similar geological settings in other regions, thereby aiding in the optimization of resource management in global petroleum industries. The shale evaluation procedure involves three primary steps: estimating shale volume, identifying clay minerals, and assessing shale distribution. The neutron-density (N-D) method was employed to estimate the shale volume in the Nubia reservoir, yielding an average of 0.6% across four wells, with a maximum recorded value of 2.2% in well GS323-3. These values represent that the Nubia reservoir contains a negligible amount of shale, indicating that the porosity and permeability are high. Clay mineral analysis, based on a Potassium-Thorium (K-Th) and Potassium-PEF cross-plots, identified the presence of chlorite, illite, montmorillonite, and heavy thorium-bearing minerals, where chlorite and illite enhance the mechanical stability of the reservoir, while montmorillonite may cause issues with swelling and pressure. Thorium-bearing heavy minerals are typically associated with reduced permeability due to their influence on chemical interactions. The shale distribution analysis, conducted using the Thomas and Stieber model, confirms the overall cleanliness of the Nubia reservoir. Most formation data points align with the 0% shale line, indicating high total porosity, while only a few points fall along the dispersed shale line. In conclusion, the findings indicate that the Nubia reservoir exhibits minimal shale content, predominantly clean lithology, and favorable porosity and permeability characteristics. Consequently, the reservoir is classified as high-quality, making it suitable for efficient hydrocarbon production.

This work reports the fabrication and optimization of nylon/multi-walled carbon nanotube (MWCNT) nanocomposite-based triboelectric nanogenerators (TENGs) using a spin coating method. By carefully tuning the MWCNT concentration, the device achieved a substantial enhancement in electrical output, with open-circuit voltage and short-circuit current peaking at 29.7 V and 3.0 mu A, respectively, at 0.05 wt% MWCNT loading on the surface of nylon. The corresponding power density reached approximately 13.9 mW/m2, representing a significant improvement over pure nylon-based TENGs. The enhanced performance is attributed to improved charge trapping and dielectric properties due to well-dispersed MWCNTs on the surface of nylon, while excessive loading caused agglomeration, reducing efficiency. This lightweight, flexible nanocomposite TENG offers a promising solution for efficient, sustainable energy harvesting in wearable electronics and self-powered sensor systems, highlighting its potential for practical energy applications.

Biodegradable polymers like poly(epsilon-caprolactone) (PCL) are widely studied for their potential applications in biomedical and environmental fields. To enhance PCL's thermal, and bioactive properties, researchers have explored composite formulations with other polymers or bioactive compounds. Oleic acid (OA), a naturally occurring fatty acid, has been identified as a promising modifier. This study investigates the modification of PCL with OA using an eco-friendly catalyst to improve its functional properties. PCL was grafted with OA using Maghnite-H+, a heterogeneous solid catalyst clay activated via sulfuric acid treatment. A response surface methodology with a central composite design was applied to optimize synthesis parameters, including reaction temperature, duration, and catalyst concentration. The resulting composite was characterized using FTIR and NMR to confirm structural modifications, while its thermal stability was evaluated. Antioxidant activity was assessed using the DPPH radical scavenging assay, and antimicrobial potential was tested against various microorganisms. The PCL-OA composite exhibited enhanced antioxidant activity, with increased radical scavenging efficiency compared to unmodified PCL. Antimicrobial tests revealed strain-dependent effects, with improved inhibition observed in specific combinations of caprolactone, OA, and PCL-OA. The findings suggest that OA incorporation enhances PCL's bioactivity, making it a promising material for biomedical and packaging applications.

The study of spectral gamma-ray logs plays a critical role in understanding the lithofacies and depositional environments of subsurface geologic formations. This research focuses on the Lam Member within the Habban oilfield, located in the Sab'atayn Basin, Yemen. By integrating spectral gamma-ray data with core analysis and other geological datasets, this study aims to provide insights into the stratigraphic distribution, mineral composition, and depositional processes of the Lam Member. Key parameters, such as thorium, uranium, and potassium concentrations, recorded from two wells were analyzed to infer sedimentary characteristics and environmental conditions. The results reveal significant lithologic heterogeneity and suggest a complex interplay of fluvial and marine depositional systems, enhancing the understanding of the basin petroleum potential. The Lam Member comprises interbedded carbonate (dolomite) and claystone with intercalated sandstone. Spectral gamma-ray results indicate that clay minerals primarily consist of mixed-layer clays, chlorite, kaolinite, and minor illite. Based on the Th/U ratio (less than 2), the depositional environment is identified as marine.

In this study, thin films of copper oxide (CuO) were deposited on indium-doped tin oxide (ITO) layers supported on glass substrates using a simple and low-cost home-made pneumatic spray technique at 350 degrees C for different deposition times (5 min, 10 min, 15 min, 20 min). Copper chloride (CuCl22H(2)O) was used as copper source at a concentration of 0.05 mol/l. X-ray diffraction patterns revealed that the films were polycrystalline with a monoclinic structure in the preferred directions (111) and (-111). Increasing the deposition time led to an increase in grain size from 11.85 to 14.73 nm. Surface analysis by scanning electron microscopy revealed improved uniformity and horizontal growth of the CuO films with increasing roughness at a deposition time of 20 min. UV-Visible measurements showed a decrease in transmittance from 73 to 47% for the wavelength range (300-1100 nm) with increasing deposition time, accompanied by a decrease in the reflectance of the films. The energy gap (Eg) decreased from 2.17 to 2.44 eV, while the Urbach energy increased with increasing spray time from 0.145 to 0.33 eV. The prepared films had absorption coefficients greater than 5 x 10(4) cm(-1) in the visible range, which diminished in the near-infrared range. The refractive index ranged between 2.01 and 3.00, whereas the dielectric constant (epsilon(r)) increased from 3.65 to 9.17.

This study examines the impact of shale volume (Vsh) and clay mineral distribution on the petrophysical properties and reservoir quality of the Matulla Formation in the Gulf of Suez, a critical factor in global hydrocarbon exploration and production. Understanding how shale affects porosity, permeability, and fluid saturation enhances reservoir characterization, optimizing recovery techniques such as hydraulic fracturing and sustainable resource management. The evaluation process involved calculating shale volume using the neutron-density method, with values ranging from 1.9% to 11% across four wells (GS323-1, GS323-2A, GS323-3, GS323-4A). Clay minerals have been identified through Potassium-Thorium (K-Th) cross-plot include chlorite, illite, kaolinite, montmorillonite, and mixed-layer clays. Montmorillonite and chlorite negatively impact porosity and permeability, while kaolinite and illite improve hydrocarbon retention. Shale distribution analysis using the Thomas and Stieber model showed both laminated and dispersed forms, where laminated shales had minimal blockage, and dispersed clays significantly reduced the reservoir quality. Results reveal that wells with low Vsh (GS323-1 and GS323-4A) which ranges from 1.5 to 2% exhibit excellent reservoir quality, with high porosity (14%), high permeability (317-320.7 mD), and low water saturation (32-44%). Moderate Vsh wells (GS323-2A) show reduced porosity (13%), permeability (220 mD), and increased water saturation (46%), reflecting good but diminished quality. High Vsh well (GS323-3) display lower porosity (12%), permeability (140 mD), and moderate water saturation (37%), indicating challenges in fluid flow. This study highlights the need for tailored strategies to mitigate high shale content and swelling clays, offering valuable insights into optimizing hydrocarbon exploration and production in shale-influenced reservoirs worldwide.

Electrochemical water splitting is regarded as a viable solution to future energy demands. Considering this, an innovative method to produce efficient oxygen evolution electrodes based on Co and Ni was proposed and successfully developed, where the metal atoms are intimately mixed before the calcination treatment. Electrochemical measurements demonstrated the high oxygen evolution activity and stability of the thus synthesized electrodes, EDX, and XPS revealing that the surface exhibits a remarkable oxidation resistance, allowing the active phase to better maintain its state when subjected to the aggressive positive potential required for oxygen evolution. Moreover, low electrical resistivity was recorded as a result of reduced thickness of the catalytic layer, further increasing the efficiency. These findings provide new insights into the design of durable and high-performance OER electrodes.

We report large-scale synthesis of monolayer WS2 films obtained by sulfurization of oxidized magnetron sputtered monolayer W precursors. Literature routes typically require similar to 800 degrees C, well above the 400 degrees C limit imposed by back-end-of-line (BEOL) integration. Here, using an enhanced chemical vapor deposition (CVD) approach, the magnetron sputtered ultrathin W precursor (a W monolayer film, 0.27 nm thick, which in ambient air becomes a WOx monolayer) is sulfurized at the lowest possible temperature (450 degrees C) within a microreactor, which consists of a sandwich-like structure formed by the precursor and a clean Si substrate. The obtained WS2 material has a good crystallinity and uniform morphology across the entire growth substrate, as confirmed by detailed characterization. These results highlight the versatility of the method combining magnetron sputtering and microreactor-CVD, facilitating its applications to wafer-scale synthesis of monolayer WS2, heterogeneously integrated into electronic circuits (a major objective for next-generation electronics and optoelectronics). Additionally, we investigate in detail the properties of WS2 films synthesized from a bilayer W precursor (0.43 nm thick), under the same conditions, and we calculated the frequencies of the second-order Raman scattering modes. For electrical measurements, we fabricated WS2/few-layer-graphene heterostructures, whose atomically clean interface yields reliable, low-resistance contacts. These devices exhibit resistive switching behavior, likely governed by vacancy migration, making it a promising candidate for memristive applications. Our results demonstrate that electronics-grade monolayer WS2 can be synthesized at 450 degrees C, approaching the BEOL requirement of 400 degrees C.

The main objective of this research is to get a comprehensive view on the subsurface geological data on the Esh El Mellaha area and environs, Red Sea, Egypt. This includes determining the depth and structural characteristics of the basement surface beneath the region, as well as identifying additional gravity and magnetic sources and potential structures within the sedimentary cover. To achieve this goal, Bouguer gravity and aeromagnetic data were used, processed and analyzed. Various depth estimation techniques were employed to analyze subsurface structures, each offering distinct advantages. Euler Deconvolution effectively delineates structural discontinuities and fault systems, while the Source Parameter Imaging (SPI) method improves depth accuracy through wavenumber analysis. The Analytical Signal method enhances resolution, providing detailed depth variations. Across these methods, the estimated depth ranges from 300 to 5000 m, with an average depth of approximately 2380 m, offering critical insights into the subsurface geological framework. Two-dimensional (2.5D) modeling was conducted on two selected gravity and magnetic profiles to estimate the depth, dip, density, and magnetic susceptibility of the source bodies. Additionally, three-dimensional (3D) modeling was applied to Bouguer gravity and Reduced-to-the-Pole (RTP) magnetic profiles, providing a detailed representation of the causative source structures. The results of the 3D inversion of gravity and magnetic data reveal the subsurface distribution of density and magnetic susceptibility, aiding in the identification of major geological structures. The sectional maps and 3D models illustrate the vertical and horizontal variations in subsurface formations, highlighting distinct anomaly zones that may correspond to faults and lithological changes. The obtained results indicate that the sedimentary succession thickness is ranging from 1.0 to 2.2 km, a finding corroborated by the borehole data. Positive structural features identified in these models suggest promising targets for potential hydrocarbon reservoirs.

In this work a method in two steps for the preparation of the composites based on poly(ortho-toluidine) (POT) and the MoS2 and WS2 sheets was reported. In the first step, by ball-milling of mixtures of MoS2 and WS2 particles, the sheets of MoS2 and WS2 (MoS2: WS2) with weight ratio equal to 3:1, 1:1 and 1:3 were prepared. In the second step, the interaction in solid-state of the MoS2: WS2 samples with POT in emeraldine-base (POT-EB) and emeraldine-salt (POT-ES) was used to obtain composites of the type MoS2: WS2/POT-EB and MoS2: WS2/ POT-ES. Using X-ray diffraction (XRD), FTIR spectroscopy, Raman scattering and X-ray photoelectron spectroscopy (XPS), we demonstrate that: i) the ball-milling method can allow the preparation of the MoS2 and WS2 sheets with different stacking order, ii) the interaction of POT-EB with the MoS2: WS2 samples involves the transformation of some repeating units of the type EB into ES; and iii) the interaction of POT-ES with the MoS2: WS2 samples leads to the appearance of new positive charges onto macromolecular chains which are compensated by S2- ions. According to thermogravimetric analysis (TG) and differential scanning calorimetry (DSC), all samples are demonstrated to be stable up to 230 degrees C. Dielectric spectroscopy data reveal a complex dependence of DC electrical conductivity on frequency, temperature, and composite concentration. We use the apparent activation energy, defined as the derivative of the logarithm of conductivity with respect to the inverse temperature. The obtained results indicate that apparent activation energy is influenced by system composition via filling factors. The electrical properties of these heterogeneous materials are described using Lichtenecker's mixing laws. For components with similar electrical properties, the effective conductivity and apparent activation energy were determined as linear combinations of the individual conductivities and activation energies, respectively, weighted by the component concentrations. Our findings align with experimental data, offering a framework for understanding conductivity and activation energy in multi-component systems.