Polymer Graphite Pencil Lead as a Cheap Alternative for Classic Conductive SPM Probes

Exploring the physicochemical traits, antifungal capabilities, and 3D spatial complexity of hydroxyapatite with Ag+Mg2+ substitution in the biocomposite thin films

The silver/magnesium doped hydroxyapatite (AgMgHAp, Ca10-x-yAgxMgy(PO4)6(OH)2, xAg=0.05 and yMg=0.02) nanocomposites coatings were deposited on Si substrate using the dip coating technique. The resulting coatings were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared (FTIR-ATR) spectroscopy, atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The EDS analysis highlighted the presence of the constitutive elements of the silver/magnesium doped hydroxyapatite (AgMgHAp) nanocomposites coatings. The surface microtexture of the AgMgHAp was assessed by atomic force microscopy (AFM) technique. The AFM data suggested the obtaining of a uniform deposited layer comprised of equally distributed nanoconglomerates. FT-IR studies highlighted the presence of vibrational modes associated with the phosphate and hydroxyl groups. No bands associated with silver or magnesium were observed. The XPS analysis highlighted the presence of the constituent elements of hydroxyapatite (Ca 2p, P 2 s, O 1 s), as well as dopants (Ag 3d, Mg 1 s and Mg 2p). The antifungal evaluation of AgMgHAp coatings was carried out using the Candida albicans ATCC 10231 fungal strain. The results of the antifungal assay revealed that the AgMgHAp coatings exhibited a strong inhibitory antifungal activity. Furthermore, the data highlighted that the AgMgHAp inhibited the development of biofilm on their surface. The results revealed that the antifungal activity of the coating varied based on the duration of incubation. On the other hand, the data also showed that AgMgHAp nanocomposites coatings inhibited the fungal cell adhesion and development from the early stages of the incubation. In addition to morphological analysis, we additionally take advantage of AFM images to investigate and explore the domain of fractal and multifractal analysis applied to the films under evaluation. Our studies indicates that nanocomposite coatings made from AgMgHAp demonstrate strong antifungal properties. Our studies indicates that nanocomposite coatings made from AgMgHAp demonstrate strong antifungal properties. These results suggest the potential of AgMgHAp nanocomposite coatings as a promising solution for developing innovative antifungal devices in biomedical applications.

Polymer-Assisted Graphite Exfoliation: Advancing Nanostructure Preparation and Multifunctional Composites

Exfoliated graphite (ExG) embedded in a polymeric matrix represents an accessible, cost-effective, and sustainable method for generating nanosized graphite-based polymer composites with multifunctional properties. This review article analyzes diverse methods currently used to exfoliate graphite into graphite nanoplatelets, few-layer graphene, and polymer-assisted graphene. It also explores engineered methods for small-scale pilot production of polymer nanocomposites. It highlights the chemistry involved during the graphite intercalation and exfoliation process, particularly emphasizing the interfacial interactions related to steric repulsion forces, van der Waals forces, hydrogen bonds, π-π stacking, and covalent bonds. These interactions promote the dispersion and stabilization of the graphite derivative structures in polymeric matrices. Finally, it compares the enhanced properties of nanocomposites, such as increased thermal and electrical conductivity and electromagnetic interference (EMI) shielding applications, with those of neat polymer materials.

Investigation of microstructural, micromorphology, and surface plasmon resonance characteristics in Ni/Al, Ni/Cu, and Ni/SS thin films

As the first boundary between the environment and the material, the surface plays an important role in their interaction with each other, therefore, the use of appropriate tools and analysis to examine the mechanical properties and morphology of surfaces has particular importance in industry and research. In this research, a thin film of nickel was deposited on metal substrates made of aluminum, copper, and steel by using the RF magnetic cathode. Then, using a non-contact atomic force microscope, the morphological properties of the nickel film with static parameters, Minkowski functionals (MF's), fractal, and multifractal were extracted to be analyzed and studied. After that, using parameters such as root mean square (RMS) roughness, skewness, and kurtosis, it was determined how the surface roughness, distribution, and probability density of particles on the film surface alters with the change of the substrate. Next, by examining and analyzing the Δα and Δf parameters obtained from the multifractal section, the morphology of the produced film on the metal substrates was investigated. Then, the change in the surface plasmon resonance (SPR) peak position is changed for the prepared film in the range of the absorption spectrum due to the substrate effect and the microstructural properties of the formed film. HIGHLIGHTS: Ni film has been deposited by Rf magnetron sputtering. The effect of metal substrates on the topography, fractality, and optical properties was studied. Minkowski functionals were used to investigate the surface morphology of the samples. Substrate's material and the topography of the formed film can changed the surface plasmon resonance position.

Synthesis of rGO/CoFe2O4 Composite and Its Magnetorheological Characteristics

In this study, composite particles of rGO/CoFe2O4 were synthesized using a solvothermal method to fabricate a low-density magnetorheological (MR) material with enhanced sedimentation stability. The morphology and crystallographic features of rGO/CoFe2O4 were characterized via SEM, TEM, and XRD, and its magnetic properties were tested using VSM. The MR fluid was formulated by blending rGO/CoFe2O4 particles into silicone oil. Under different magnet strengths (H), a rotational rheometer was used to test its MR properties. Typical MR properties were observed, including shear stress, viscosity, storage/loss modulus, and dynamic yield stress (τdy) following the Herschel-Bulkley model reaching 200 Pa when H is 342 kA/m. Furthermore, the yield stress of the MR fluid follows a power law relation as H increases and the index changes from 2.0 (in the low H region) to 1.5 (in the high H region). Finally, its MR efficiency was calculated to be about 104% at H of 342 kA/m.

Evaluation on microalgae for the production of bio-chemicals and electricity

Recent advancement in biophotovoltaic systems using microalgae, coupled with biorefinery approach, would improve economy-feasibility in production. The major concern is its commercial strength in terms of scalability, strain selection and extraction procedure cost. It must compete with conventional feedstocks such as fossil fuels. This project proposes to enhance the economic feasibility of microalgae-based biorefinery by evaluating their performance for bio-electricity, bio-diesel and carotenoids production in a single cycle. The first part of the study was to construct and select a Bio-bottle Voltaic (BBV) device that would allow microalgae to grow and produce bioproducts, as well as generate the maximum current output reading derived from the microalgae's photosynthesis process. The second phase consisted of a 25-day investigation into the biorefinery performance of six different microalgal species in producing bio-electricity, bio-diesel and carotenoid in a prototype BBV device. The prototype BBV device with aluminium foil and pencil lead as its anode and cathode produced the highest carotenoid and biodiesel component production from the two microalgae tested, according to the results of the first phase of the experiment. In the second portion of the study, Scenedesmus dimorphus and Chlorella vulgaris were identified as the two microalgae most capable of maintaining their growth throughout the experiment. The maximum current reading observed for C. vulgaris was 653 mV. High Performance Liquid Chromatography analysis showed four major carotenoid compounds found which were Neoxanthin, Cantaxanthin, Astaxanthin and 9-cis antheraxanthin, and the highest carotenoid producer was C. vulgaris which recorded at 1.73 μg/mL. C. vulgaris recorded as the most alkanes producer with 22 compounds detected and Heptacosane and Heneicosane as the two major biodiesel compounds found in the extracts. Evaluation of C. vulgaris data showed that it has enormous potential for microalgal biorefinery candidates. Further ongoing research and development efforts for C. vulgaris will improve the economic viability of microalgae-based industries and reduce reliance on depleted fossil fuels.

Morphological and fractal features of cancer cells anchored on composite layers based on magnesium-doped hydroxyapatite loaded in chitosan matrix

In the present study, we report the development and characterization of composite layers (by spin coating) based on magnesium-doped hydroxyapatite in a chitosan matrix, containing human osteosarcoma MG63 cells anchored. Studies regarding the biocompatibility of the composite layers were performed with the aid of a MTT (3-4,5-Dimethylthiazol 2,5-diphenyltetrazolium bromide) assay. The data determined that the composite layers did not inhibit the growth and adhesion of MG63 cells to their surfaces exhibiting good biocompatibility properties. Furthermore, the attachment and development of MG63 cells on the surface of MgHApCh composite layers were investigated using atomic force microscopy (AFM). AFM topographical maps emphasized that the HApCh and 8MgHApCh composite layers surface promoted the attachment and proliferation of MG63 cells on their surface. Meanwhile, in the case of 30MgHApCh layers incubated for 48 h, a slight modification of the morphological features of the MG63 cells. In addition, the effects of the composite layers against Candida albicans ATCC 10231 were also evaluated. The data results from the in vitro antifungal assay depicted that the composite layers successfully inhibited the growth of the fungal cells onto their surface. Morphological and fractal analyses unveil cancer cell surfaces on Mg-containing composite layers with intricate 3D patterns, driven by high-frequency components. Their remarkable complexity and roughness arises from a strong multifractal nature, supporting more effective vertical growth compared to Si and HApCh surfaces. The cell viability reduced of uncoated Si surface is highlighted by its less intense 3D pattern growth. Our results show that the uncoated Si surface promotes lower viability of MG63 cancer cells, with less rough and complex 3D spatial patterns.

The impact of helical slide honing on surface microtexture compared to plateau honing process through relevant characterization methods

The cylinder engine surface texture has a major influence on the functional performances of the ring-pack tribo-system. The cylinder engine surface microtexture manufactured by plateau honing (PH) and helical slide honing (HSH) processes have been analyzed using white light interferometry (WLI), and stereometric analysis. The approaches in three-dimensional (3-D) white light interferometer measurements and surface stereometric analysis are important for the correct interpretation of 3-D local surface texture features and can be applied in mathematical models for calculating the friction. The samples were divided into two groups: plateau honing (PH) samples and helical slide honing (HSH) samples to discuss the obtained results, according to the honing techniques obtained after several stages: the rough and finish honing and final stage. The obtained results demonstrated that the surface of group PH has the higher values of root mean square height (Sq = 1.83 μm) and fractal dimension (Df = 2.74 ± 0.01), while the lowest values of root mean square height (Sq = 0.63 μm) and fractal dimension (Df = 2.60 ± 0.01) were found for HSH samples. These values highlight that the PH samples are more irregular (both as surface and topography) in comparison with HSH samples. HIGHLIGHTS: We characterized the micromorphology of surface microtexture in plateau and helical slide honing. The nanostructure morphology was investigated using the white light interferometry, fractal and stereometric analyses. The surface topography during the HSH process has different characteristics than the PH process and can be used to obtain better friction and lubrication performances.

Stereometric analysis of Ti1- x Alx N thin films deposited by direct current/radio frequency magnetron sputtering

A study of image analysis of Ti_1-x Al_x N films deposited on corning glass substrates by a direct current (DC)/radio frequency (RF) magnetron sputtering system was performed. Atomic force microscopy (AFM) data were studied to understand how the impact of the concentration of Al content influences the 3D surface morphology as well as the surface texture parameters. The results showed that the superficial morphology was modified by the increase of Al content in the Ti_1-x Al_x N films, as well as the surface microtexture. It has also been observed that the Ti_1-x Al_x N film surface with the highest aluminum (Al) doping concentration presented a similar surface morphology to pristine titanium nitride (TiN) thin films. The Abbott-Firestone curves for all films exhibited an S-like shape suggesting topographic uniformity and Gaussian distribution of heights. An increase in surface uniformity is observed with Al concentration. The characterization of the surface morphology of Ti_1-x Al_x N films by the evaluation of surface statistical parameters suggests that the surface topography can be adjusted by suitable doping of aluminum and offers a deeper understanding of the applicability of these films.

Enhancement of sp3 C Fraction in Diamond-like Carbon Coatings by Cryogenic Treatment

Diamond-like carbon (DLC) coatings deposited onto high-speed-steel surfaces were subjected to deep cryogenic treatment (DCT) at temperatures of −120 to −196 °C to investigate the evolution of microstructure, bonding structure, and mechanical properties. The surface morphology and the bonding structure of the DLC coatings were studied using scanning electron microscopy, transmission electron microscopy, micro-Raman spectroscopy, and X-ray photoelectron spectroscopy. It is found that DCT affects the surface morphology, especially the size and the height of the aggregates. For those DLCs with more than 50% sp3 C fraction, the sp2 C → sp3 C transformation occurred in coatings treated at a temperature of −120 to −160 °C; and the maximum fraction of sp3 C was obtained after treatment at −140 °C. Almost keeping the wear resistance of DLCs, DCT can improve the adhesion strength, and surface hardness. The findings of this study indicate that DCT will be a potential post-treatment method to tune the microstructure and mechanical performance of DLC coatings.

Batch Fabrication of Wear-Resistant and Conductive Probe with PtSi Tip

This paper presents a simple and reliable routine for batch fabrication of wear-resistant and conductive probe with a PtSi tip. The fabrication process is based on inductively coupled plasma (ICP) etching, metal evaporation, and annealing. Si tips with curvature radii less than 10 nm were produced with good wafer-level uniformity using isotropic etching and thermal oxygen sharpening. The surface roughness of the etched tip post was reduced by optimized isotropic etching. The dependence of the platinum silicide morphology on annealing conditions were also systematically investigated, and conductive and wear-resistant probes with PtSi tips of curvature radii less than 30 nm were batch fabricated and applied for scanning piezoelectric samples.

Paper Thermoelectrics by a Solvent-Free Drawing Method of All Carbon-Based Materials

As practical interest in the flexible or wearable thermoelectric generators (TEGs) has increased, the demand for the high-performance TEGs based on ecofriendly, mechanically resilient, and economically viable TEGs as alternatives to the brittle inorganic materials is growing. Organic or hybrid thermoelectric (TE) materials have been employed in flexible TEGs; however, their fabrication is normally carried out using wet processing such as spin-coating or screen printing. These techniques require materials dissolved or dispersed in solvents; thus, they limit the substrate choice. Herein, we have rationally designed solvent-free, all carbon-based TEGs dry-drawn on a regular office paper using few-layered graphene (FLG). This technique showed very good TE parameters, yielding a power factor of 97 μW m-1 K-2 at low temperatures. The p-type only device exhibited an output power of up to ∼19.48 nW. As a proof of concept, all carbon-based p-n TEGs were created on paper with the addition of HB pencil traces. The HB pencil exhibited low Seebeck coefficients (-7 μV K-1), and the traces were highly resistive compared to FLG traces, which resulted in significantly lower output power compared to the p-type only TEG. The demonstration of all carbon-based TEGs drawn on paper highlights the potential for future low-cost, flexible, and almost instantaneously created TEGs for low-power applications.

A Facile Strategy to Fabricate Antistatic Polyamide 1012/Multi-Walled Carbon Nanotube Pipes for Fuel Delivery Applications

Developing antistatic long chain polyamide (LCPA) resins and fabricating the corresponding fuel pipes are challenges but necessary. Herein, a facile but effective strategy was put forward to fabricate LCPA resins with a superior conductivity, meeting the requirements of electrostatic sub-conductors. The strategy was based on, first, the incorporation of a large amount (15 wt%) of multi-walled carbon nanotubes (MWCNTs) into a polyamide 1012 (PA1012) matrix as a master batch, which formed a dense conductive network. Subsequently, it was diluted with PA1012 granules to produce base resins, and the reprocessed nanocomposites with a critical content of MWCNTs (3 wt%) could generate an effectively interconnected conductive network, with sparse and thinning features. Using the base resins, fuel pipes for automobiles, petrol stations and high pressure applications were successfully fabricated, where the thin conductive network was transformed into a thick one due to external field-induced re-agglomeration of MWCNTs. In this way, the obtained fuel pipes combined excellent conductive and barrier properties, and mechanical properties at high and low temperatures. These comprehensive properties also arose from the uniform dispersion of MWCNTs in an LCPA matrix, even without coupling agents; the attractive interaction between MWCNTs and the polyamide chains contributed to their strong interface adhesion. Thus, this research provides a versatile approach to fabricating antistatic LCPA resins, which will certainly extend their application to vehicle fuel systems.

Field Emission Properties of Polymer Graphite Tips Prepared by Membrane Electrochemical Etching

This paper investigates field emission behavior from the surface of a tip that was prepared from polymer graphite nanocomposites subjected to electrochemical etching. The essence of the tip preparation is to create a membrane of etchant over an electrode metal ring. The graphite rod acts here as an anode and immerses into the membrane filled with alkali etchant. After the etching process, the tip is cleaned and analyzed by Raman spectroscopy, investigating the chemical composition of the tip. The topography information is obtained using the Scanning Electron Microscopy and by Field Emission Microscopy. The evaluation and characterization of field emission behavior is performed at ultra-high vacuum conditions using the Field Emission Microscopy where both the field electron emission pattern projected on the screen and current–voltage characteristics are recorded. The latter is an essential tool that is used both for the imaging of the tip surfaces by electrons that are emitted toward the screen, as well as a tool for measuring current–voltage characteristics that are the input to test field emission orthodoxy.