Surface Analysis Research Articles

Stabilizing Bifurcated Hydrogen Bond in 8-Aminoquinoline Appended Peptides.

The hydrogen bonding interaction between an amide N-H and the amide N of the preceding residue is prevalent in proline-containing proteins and peptides. However, the N-H···N hydrogen bonding interaction is rare in non-prolyl natural peptides due to restricted dihedral angles. Herein, we stabilize this type of interaction in 8-aminoquinoline appended non-prolyl peptides through bifurcated N···H···N hydrogen bond. The 8-aminoquinoline-incorporated model peptides 2a-i were designed, synthesized, and the crystal structures of 2a-c and 2i were solved. Analysis of crystal data reveals that the amide N-H of aminoquinoline is involved in bifurcated hydrogen bonding interaction with the nitrogen of the preceding amino acid residue and the nitrogen in quinoline. Analysis of crystal packing, Hirshfeld surface and fingerprint plots confirms that the intermolecular O···H contacts significantly contribute to stabilizing bifurcated N···H···N hydrogen bonding interaction. Furthermore, NMR experiments and CD spectroscopy were conducted to examine the preferred conformation in solution, and the data corroborate with the crystal structure conformation.

The role of manufacturing-induced texture on the tribological performance of cold work tool steels

Abstract Manufacturing operations produce surface characteristics that, although stochastic, can significantly affect functionality, especially in forming tools, impacting contact and lubrication conditions during operation. This study investigates the influence of stochastic microtextures resulting from milling on the tribological performance of cold work tool steels with two different carbon contents (0.8 and 2 wt%). Different surface textures were observed resulting from the different C contents, with 3D roughness parameters indicating rougher surfaces for the 2.0% wt. C steel. Tribological behavior was assessed using the strip drawing test to analyze friction, wear coefficients, and wear mechanisms. Surface analysis before and after testing was executed employed SEM, EDX, and CLSM, with CLSM also used to determine 3D roughness parameters of the worn tracks. Post-test macrographic analyses and 2D roughness measurements were conducted on the pulled sheets. Tribological test data revealed lower friction and wear coefficients for the 2.0 wt.% C tool steel, with susceptibility to abrasion wear, while the 0.8 wt.% C tool exhibited a higher tendency towards adhesion wear. Post-test analysis suggested smoother surfaces for the 2.0 wt.% C steel compared to the 0.8 wt.% C steel. Macrographic analysis showed no visible wear marks on sheets tested with the 2.0 wt.% C steel, contrasting with wear grooves visible on sheets pulled against the 0.8 wt.% C steel. Additionally, 2D roughness measurements indicated higher roughness after pulling against the 0.8 wt.% C tool compared to the 2.0 wt. C tool. Overall, the study demonstrates that manufacturing-induced textures without the need of post-manufacturing texturing influence the tribological performance of the evaluated steels, opening an avenue to be explored to improve the tribological performance of forming tools.

Ionic Nitrogen-Doped Carbon Dots as Nonpolar Lubricant Additives at Low Effective Addition.

The poor compatibility with nonpolar lubricant still hinders the application of carbon dots (CDs) in lubrication. In addition, research proves that the existence of ionic structure and active groups on CDs are conducive to their lubricity. In order to obtain the ionic structures and good oil compatibility synchronously, a kind of ionic nitrogen-doped CDs (NCDs) was synthesized via the alkylation of nitrogen in NCDs and anion exchange. The new material could exhibit good tribological performance as poly alpha olefins (PAO4) additives with low addition. Moreover, an ionic liquid, [N44HH][DEHP], with the same anion was chosen as a comparison to investigate the role of NCD cations. The surface analyses demonstrate that NCD cations and phosphate ester anions adsorb on the friction interface to play a synergistic lubrication role during the friction process, which could generate a superior carbon-based tribofilm.

A Zn(II)-based 1D Coordination Polymer with Adsorption Properties and Hirshfeld Surface Analysis

A Zn(II)-based 1D Coordination Polymer with Adsorption Properties and Hirshfeld Surface Analysis

Innovative Solution for Invasive Species and Water Pollution: Hydrochar Synthesis from Pleco Fish Biomass

In recent years, the invasive pleco fish has emerged as a global concern due to its adverse effects on ecosystems and economic activities, particularly in various water bodies in Mexico. This study introduces an innovative solution, employing microwave-assisted hydrothermal carbonization (MHTC) to synthesize hydrochar from pleco fish biomass. The research aimed to optimize synthesis conditions to enhance hydrochar yield, calorific value, and adsorption capacities for fluoride and cadmium in water. MHTC, characterized by low energy consumption, high reaction rates, and a simple design, was employed as a thermochemical process for hydrochar production. Key findings revealed that through response surface analysis, the study identified the optimal synthesis conditions for hydrochar production, maximizing yield and adsorption capacities while minimizing energy consumption. Physicochemical characterization demonstrated that hydrochars derived from pleco fish biomass exhibited mesoporous structures with fragmented surfaces, resembling hydroxyapatite, a major component of bone. Hydrochars derived from pleco fish biomass exhibited promising adsorption capacities for fluoride and cadmium in water, with hydrochar from Exp. 1 (90 min, 160 °C) showing the highest adsorption capacity for fluoride (4.16 mg/g), while Exp. 5 (90 min, 180 °C) demonstrated superior adsorption capacity for cadmium (98.5 mg/g). Furthermore, the utilization of pleco fish biomass for hydrochar production not only offers an eco-friendly disposal method for invasive species but also addresses fluoride and cadmium contamination issues, contributing to sustainable waste management and water treatment solutions. The resulting hydrochar, rich in solid fuel content with low pollutant emissions, presents a promising approach for waste management and carbon sequestration. Moreover, the optimized synthesis conditions pave the way for sustainable applications in energy production, addressing critical environmental and public health concerns. This research provides valuable insights into the potential of microwave-assisted hydrothermal carbonization for transforming invasive species into valuable resources, thereby mitigating environmental challenges and promoting sustainable development.

A comparative study of X-ray structural analysis, DFT computations, and Hirshfeld surface analysis for decahydroacridine-1,8-diones

A comparative study of X-ray structural analysis, DFT computations, and Hirshfeld surface analysis for decahydroacridine-1,8-diones

Experimental study on operating characteristics of rotor-bearing system lubricated by gallium-based liquid metal

PurposeThe purpose of this paper is to explore the operating characteristics of gallium-based liquid metals (GLMs) by directly adding them as lubricants in real mechanical equipment.Design/methodology/approachThis paper conducts an analysis of the rotor-bearing system under GLM lubrication using a constructed test rig, focusing on vibration signals, surface characteristics of the friction pair, contact resistance and temperature rise features.FindingsThe study reveals that GLM can effectively improve the lubrication condition of the tribo-pair, leading to a more stable vibration signal in the system. Surface analysis demonstrates that GLM can protect the sample surface from wear, and phase separation occurs during the experimental process. Test results of contact resistance indicate that, in addition to enhancing the interfacial conductivity, GLM also generates a fluid dynamic pressure effect. The high thermal conductivity and anti-wear effects of GLM can reduce the temperature rise of the tribo-pair, but precautions should be taken to prevent oxidation and the loss of its fluidity.Originality/valueThe overall operating characteristics of the rotor-bearing system under GLM lubrication were investigated to provide new ideas for the lubrication of the rotor-bearing system.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-03-2024-0067/

Magnetic Rubber@Ni-Co layered double hydroxide derived from ZIF-67 template as nanostructured sorbent; application in determination of anticancer drugs in plasma samples

In this study, a magnetic three-dimensional nano-composite based on Rubber-Fe3O4@Ni-Co Layered double hydroxide derived from ZIF-67 template was synthesized by a hydrothermal method. The proposed nano-composite was used as a sorbent for the enrichment of trace amounts of anti-cancer drugs (dasatinib and erlotinib hydrochloride) from plasma samples followed by determination using high-performance liquid chromatographic analysis (HPLC-UV). The synthesized nano-sorbent was characterized by X-ray diffraction, field emission scanning electron microscopy, Fourier transform infrared spectroscopy, vibrating-sample magnetometer, Brunauer-Emmett-Teller surface analysis, Barrett-Joyner-Halenda pore size analysis and energy dispersive X-ray spectroscopy. Under optimal experimental conditions, factors affecting on extraction efficiency such as pH, ionic strength, extraction temperature and time, desorption solvent and time, the limit of detection (LODs) and the limit of quantification (LOQs) were obtained as 0.6, 2 µg/L for both of dasatinib and erlotinib, respectively. Also, linear range of the method were 2–500 and 2–1000 µg/L for dasatinib and erlotinib, respectively. Relative standard deviations (RSD%) for the repeatability of extraction on sorbent to sorbent were obtained as 3.59, 1.97 %, and one sorbent reusability were investigated and relative standard deviation values were obtained 5.35, 3.30 % for dasatinib and erlotinib, respectively.

Vacancy Ordering in Ultrathin Copper Oxide Films on Cu(111).

Oxide thin films grown on metal surfaces have wide applications in catalysis and beyond owing to their unique surface structures compared to their bulk counterparts. Despite extensive studies, the atomic structures of copper surface oxides on Cu(111), commonly referred to as "44" and "29", have remained elusive. In this work, we demonstrated an approach for the structural determination of oxide surfaces using element-specific scanning tunneling microscopy (STM) imaging enhanced by functionalized tips. This approach enabled us to resolve the atomic structures of "44" and "29" surface oxides, which were further corroborated by noncontact atomic force microscopy (nc-AFM) measurements and Monte Carlo (MC) simulations. The stoichiometry of the "44" and "29" frameworks was identified as Cu23O16 and Cu16O11, respectively. Contrary to the conventional hypothesis, we observed ordered Cu vacancies within the "44" structure manifesting as peanut-shaped cavities in the hexagonal lattice. Similarly, a combination of Cu and O vacancies within the "29" structure leads to bean-shaped cavities within the pentagonal lattice. Our study has thus resolved the decades-long controversy on the atomic structures of "44" and "29" surface oxides, advancing our understanding of copper oxidation processes and introducing a robust framework for the analysis of complex oxide surfaces.

Are Video Games and School Conflictual or Complementary Contexts for Affording Psychological Need Fulfillment? Implications for Adolescents’ Problematic Gaming and School Adjustment

Abstract According to the need density hypothesis, adolescents are at risk for problematic gaming when they only experience satisfaction of their basic psychological needs within, but not outside, the gaming context. This cross-sectional study among daily gamers (N = 309, M age = 15.63, 94.8% boys) is the first to examine this hypothesis in adolescence, thereby comparing adolescents’ need fulfillment between the contexts of video games and school and examining the role of need fulfilment in both contexts in relation to problematic gaming and school outcomes. Response surface analysis showed that adolescents’ overall need satisfaction (across the two contexts) was related to lower problematic gaming and less maladaptive school outcomes. Consistent with the need density hypothesis, adolescents reported more problematic gaming, school disengagement and school burnout when high need satisfaction in the gaming context co-occurred with either low need satisfaction or high need frustration at school. Directions for future research are discussed.

Tribological Behavior of Hydrocarbons in Rolling Contact

In the analysis of tribological contacts, the focus is often on a singular question or result. However, this entails the potential risk that the overall picture and the relationships could be oversimplified or even that wrong conclusions could be drawn. In this article, a comprehensive consideration of test results including component and lubricant analyses is demonstrated by using the example of rolling contact. For this purpose, thrust cylindrical roller bearings of type 81212 with unadditized base oils were tested in the mixed-friction area. Our study shows that by using an adapted and innovative surface analysis, a deeper dive into the tribo-film is feasible even without highly sophisticated analytical equipment. The characterization of the layers was performed by the three less time-consuming spatially resolved analysis methods of µXRF, ATR FTIR microscopy and Raman spectroscopy adapted by Schaeffler. This represents a bridge between industry and research. The investigations show that especially undocumented and uncontrolled contamination of the test equipment could lead to surprising findings, which would result in the wrong conclusions. Simple substances, like hydrocarbons, are demanding test specimens.

Damage behavior of cold-rolled sintered fiber felts

Abstract Porous Materials, such as sintered fiber felts (SFFs), can contribute to
the reduction of aircraft noise by acting as a low-noise trailing edge (TE). A rolling
process with a time-varying rolling gap was sucessfully used to tailor the aeroacoustic
properties of SFFs. To ensure the suitability of rolled porous materials for application,
the mechanical properties after rolling must be investigated. The objective of this
study was to clarify the effect of the rolling process on the damage evolution during
tensile loading. A SFF consisting of a functional layer and a support grid made
of alloy 1.4404 was used for rolling. Interrupted tensile tests in combination with
computed tomography (CT) were used to investigate the damage evolution of asreceived
material, uniformly rolled material and material rolled with a gradient in
thickness reduction. Metallographic examination and fracture surface analysis using
scanning electron microscopy (SEM) complemented the CT analysis. Uniformly rolled
material with a low degree of deformation (-0.74 ≤ φ < 0) failed identically to the
as-received material. The functional layer failed first, starting from the center. The
support grid subsequently failed due to the incremental failure of individual wires. The
material rolled with a gradient in thickness reduction failed accordingly. A significant
change in damage evolution occured for material rolled at high degrees of deformation
φ≤-1.53, where the support grid fails first and the functional layer second. The rolling
process using a time-varying rolling gap does not result in a detrimental mechanical
behavior under tensile load. The results improve the general understanding of the
effects of rolling processes on the properties of porous materials and allow the damage
behavior to be taken into account with regard to its application as a TE.

Eco-Engineered Low-Cost Carbosorbent Derived from Biodegradable Domestic Waste for Efficient Total Chromium Removal from Aqueous Environment: Spectroscopic and Adsorption Study

Chromium contamination in water bodies poses severe risks to both the environment and human health. This research introduces an innovative solution to this challenge by creating a vapor-activated carbosorbent from biodegradable household waste. The efficacy of this adsorbent in removing total chromium through batch methods from aqueous solutions was investigated. Surface analysis using scanning electron microscopy (SEM) exhibited a porous structure, while Fourier-transform infrared spectroscopy (FTIR) identified distinct functional groups on the surface. The point of zero charge (PZC), determined at 6.95, revealed the adsorbent’s surface chemistry. Impressively, the synthesized carbosorbent exhibited significant adsorption capacities of 23.08 mg.g-1 for Cr(III) and 24.84 mg.g-1 for Cr(VI) under optimal conditions. The Langmuir isotherm model illustrated a monolayer adsorption mechanism aligned with the pseudo-second-order kinetic model, confirming chemisorption. Thermodynamic analysis disclosed favorable and spontaneous chromium adsorption. Negative ΔG° values affirmed the spontaneity, while the exothermic nature of the process was signified by the positive ΔH° value, indicating heat release. Increased randomness at the solid-liquid interface, indicated by the positive ΔS° value, underscored the enhanced affinity between the adsorbent and adsorbate. This study exemplifies the potential of the vapor-activated carbosorbent as an efficient and sustainable remedy for chromium-contaminated water bodies.

Spreading model of single droplet impacting the banana leaf surface and computational fluid dynamics simulation analysis

The droplet deposition behavior is an important indicator of precision agriculture and sustainable agriculture 4.0. Comprehensive analysis of the behavior and modeling of pesticide droplets impacting target leaves is an important basis for achieving efficient spray deposition. In this study, banana leaves were taken as the research object, the spreading model and computational fluid dynamics (CFD) model of single droplet impacting on the target leaf surface were studied from the micro and macro perspectives. The aim is to clarify and obtain the quantitative mapping relationship between droplet deposition performance and related operating parameters. The results showed that the pesticide droplets were asymmetrically spread and slipped on the surface of the inclined banana leaves. The maximum lateral spreading diameter Dnmax was only affected by the normal component of Weber number Wen, while the maximum tangential spreading diameter Dtmax and slip distance L were affected by the normal component of Weber number Wen and the inclination angle α. As the impact velocity increases, the pesticide droplets interact with the non-smooth morphology of the banana leaf surface to form a large number of pinning sites on the edge contact line. Combining the microscopic characteristics of banana leaves with the physicochemical characteristics of the droplets, a CFD model was established to carry out single-drop impact simulation verification. The impact velocity and inclination angle were set as variables to carry out CFD simulation of the dynamic process. The numerical simulation results are consistent with the spreading model obtained from the experimental study, which can quantitatively reflect the impact process of pesticide droplets. The spreading model and CFD model of pesticide droplets impacting on the banana leaf surface established in this study, can provide guidance for the selection of pesticide application for the spray droplet deposition behavior. At the same time, it can also provide methodological reference for other crop spray research and spray technology research in other fields.

Synthesis and X-ray characterization of two new 1,4-benzoxazine derivatives: Structural analysis and DFT calculations

The synthesis and XRD characterization of two new 1,4-benzoxazine derivatives (3a-5a) namely ethyl‐6‐nitro‐3a‐(p‐tolylamino)‐1,2,3,3a‐tetrahydrobenzo[b]cyclopenta[e][1,4]oxa-zine‐9a(9H)‐carboxylate (3a) and methyl-6,10b-dimethyl-5a,6,10b,11-tetrahydrobenzo[5,6][1,4]oxazino[2,3-b]indole-2-carboxylate (5a) are reported herein. In both compounds it is observed the formation of π···π and CH···π interactions and strong NH···O H-bonds, which were studied energetically at the PBE0-D3/def2-TZVP level of theory. The Hisrhfeld surface and QTAIM analyses and NCI plots were used to study the nature and the extent of different intermolecular interactions observed in both structures, revealing the existence of additional R21(6) and R21(7) synthons. In addition, using the potential energy density as energy predictor, the QTAIM method is useful to investigate the relative contribution of each interaction to the formation of the assemblies.

Research on Optimization of Water Jet Coupling System Parameters in Automated Ultrasonic Phased Array Inspection

When ultrasonic testing is used for non-destructive testing of welded workpieces, the surface of the ultrasonic transducer or wedge should have a good coupling effect with the measured surface of the workpiece. However, in actual ultrasonic testing, it is difficult to ensure that the ultrasonic transducer completes uniform scanning, resulting in poor coupling between the probe and the workpiece, resulting in low acoustic coupling stability of ultrasonic testing. In view of the above problems, this paper designs and constructs an automated ultrasonic phased array inspection platform using water jet coupling. By taking water flow rate, coupling distance, and transducer center frequency as independent variable parameters of the water jet coupling system, and using the received sound wave amplitude as the response variable for experimental comparison, a response surface analysis is conducted on these parameters to optimize the detection resolution of the automated ultrasonic inspection system. The results show that the most accurate system detection results are achieved when the water flow rate is 0.4 L/min, the coupling distance is between 1.0-1.6 mm, and the transducer center frequency is 10 MHz. This effectively solves the problem of low stability in ultrasound detection coupling, improves the detection efficiency, and provides guidance for further research on the imaging effect of automated ultrasonic phased array inspection in subsequent studies.

Sensitivity Analysis of MHD Hybrid Nanofluid Flow over a Radially Shrinking Disk with Heat Generation

This work features the numerical computation and statistical analysis (response surface and sensitivity) for the flow and thermal progress of an axisymmetric copper-alumina/water hybrid nanofluid subjected to a permeable shrinking disk. The simultaneous factors of magnetic field (MHD), heat generation and suction parameter in the heat transfer development and flow characteristic are observed. The flow and energy equations are mathematically developed based on the boundary layer assumptions. These equations are then simplified with the aids of the similarity variables. The numerical results are then generated by the bvp4c solver in the Matlab software. The dual solutions are possible and exist up to a separation value upon the inclusion of suction effect. The increment of heat generation parameter from 0% to 1% reduces the heat transfer rate for all values of the stretching/shrinking parameter. For the response surface analysis, the responses (skin friction coefficient and heat transfer rate) are analyzed for three factors (magnetic, suction, heat generation) and three magnitudes (low, medium, high). Based on this analysis, the magnetic and suction parameters provide a significant effect on the skin friction with p-values < 0.05. Meanwhile, for the heat transfer coefficient, all factors give significant impact with zero p-values. Meanwhile, the sensitivity analysis reveals that the suction parameter has higher sensitivity to the heat transfer as compared to the magnetic and heat generation parameter. Even though these parameters being less sensitive, their influence on heat transfer remains statistically significant.

Exploring hybrid dihydrogen phosphate systems: Experimental and theoretical investigation

The investigation into the crystal structure of 1-(carboxymethyl)cyclohexyl methanaminium dihydrogenphosphate endeavors to unravel the intricate molecular interactions at play. Utilizing Hirshfeld surface analysis, we delineate the specific types of interactions within the molecules. Fingerprint plots and molecular surface contours (dnorm, di, and de) vividly illustrate the proportional contributions of H…H (53.8%), O…H (42.9%), and O…O (2.2%). Further characterization through FTIR and UV–Vis spectroscopy enhances our comprehension.In contrast, the molecular arrangement’s reinforcement stems from the NH… O interaction, leading to a linear chain. Through FTIR and FT-Raman experiments, we discern functional groups, contrasting experimental results with theoretical values. Mulliken atomic charges are meticulously examined, indicating reduced reactivity and heightened stability across diverse environments.Exploration of energy gaps in HOMO-LUMO and Density of States (DOS) spectra reveals coherence, supported by Natural Bond Orbital (NBO) Analysis, accentuating the equilibrium in energy during donor and acceptor transitions. This holistic approach enriches our understanding of the structural intricacies and stability factors inherent in the examined compound.

Kopsia terengganensis’ alkaloids as potential green inhibitors for mild steel corrosion in CO2-saturated 3.5% NaCl medium

The corrosion inhibition potential of alkaloids from Kopsia terengganensis bark extract (KTBE) in mitigating the mild steel corrosion in a CO2-saturated 3.5% NaCl medium was evaluated. Standard corrosion evaluation methods, including weight loss test, electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PD) were employed, which revealing a concentration-dependent enhancement in KTBE's inhibition efficiency. At 500 ppm, the corrosion inhibition efficiency recorded the highest value of 90.63% based on the weight loss study and 87.38% based on electrochemical analysis. Tafel slopes in PD studies affirmed that KTBE functioned as an anodic-type inhibitor. The adsorption of the inhibitor is in accordance with the Langmuir adsorption isotherm with an adsorption free energy (ΔG°ads) of −26.47 kJ/mol, suggesting the binding of KTBE molecules by means of physisorption. Surface analysis conducted through scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy, and Fourier transform infrared spectroscopy (FTIR) confirmed the formation of a protective inhibitive layer on the surface of mild steel. The proposed corrosion inhibition mechanism involves electrostatic interactions between KTBE molecules and the mild steel surface. This comprehensive investigation underscores KTBE's potential as an effective corrosion inhibitor in corrosive environments.

Hydrogen bond thermotropic ferroelectric liquid crystal of DL-tartaric acid and 4-heptyloxybenzoic acid (1:1): Experimental and density functional theory (DFT) approach

The current research work incorporates structural, experimental and computational studies of a hydrogen bond thermotropic ferroelectric liquid crystal (HBTFLC) complex synthesised from DL-tartaric acid (DLTA) and 4-heptyloxybenzoic acid (7OBA) with 1:1 ratio. Spectroscopic studies (XRD, NMR, FTIR, UV–Vis) and Density Functional Theory (DFT) are utilized to confirm intermolecular hydrogen bonds in the synthesised complex. Polarizing Optical Microscope (POM) study confirms the phase sequence (N*, Sm C*, Sm F* and Sm G*) while Differential Scanning Calorimetry (DSC) explore the thermal properties of the mesophases. The Frontier Molecular Orbital (FMO) and Molecular Electrostatic Potential (MEP) surface analysis also explore the donor-acceptor interactions, stability and chemical reactivity of the complex. The nature of H-bond is estimated by Natural Bond Orbital (NBO) studies with the support of Atom-in-Molecules (AIM) and Reduced Density Gradient (RDG) analysis. Nonlinear Optical (NLO) properties of the complex are studied by calculating its polarizability and hyperpolarizability.