Experimental Aspects Research Articles

The mechanism and effect factors of the combustion cycle‐to‐cycle variations in the spark ignition engine

AbstractThe combustion cycle‐to‐cycle variations (CCV) are the typical combustion phenomena in the internal combustion engine, which will not only affect the combustion efficiency, heat‐work conversion process, and emission formation in the cylinder, but also cause the output torque and power fluctuation, resulting in unstable and even misfire. These phenomena are particularly evident in the spark ignition (SI) engine, especially at idle, acceleration, and high exhaust gas recirculation conditions. Consequently, it is quite important to explore the internal relationship and correlation mechanism between the CCV and the affecting factors. This paper comprehensively reviewed the fundamental reasons and mechanisms of CCV of the SI engine. In addition, the characteristic parameters and characterization methods of the CCV, the laws and influencing factors of the CCV, and the numerical simulation methods of the CCV were introduced in detail to quantitatively analyze the performance, combustion, and emissions characteristics of the SI engine. Each research direction is discussed in detail in various sections. The research status of the CCV of the SI engine from the experimental and numerical simulation aspects was also presented and discussed. Lastly, effective methods and strategies were proposed to improve the combustion process and fuel economy, and reduce exhaust emissions of the SI engine for high efficiency and clean combustion.

Methods for degrading dicloxacillin in water using inorganic peroxides and their combination with UVC- experimental and theoretical aspects

Antibiotics are currently recognized as environmental pollutants. In this work, the methods involved in the degradation of a β-lactam antibiotic (i.e., DXC) by treatments based on inorganic peroxides and UVC (e.g., UVC alone, UV-C/H2O2, UVC/peroxymonosulfate, and UVC/peroxydisulfate) are presented. The methodology of computational calculations to obtain frontier orbitals and Fukui indices for DXC, and elucidate the reactive moieties on the target substance is also shown. Finally, the direct oxidation by peroxides and UV-C/H2O2 action to treat DXC in simulated pharmaceutical wastewater are depicted. The chromatographic and theoretical analyses allowed for determining the degrading performance of inorganic peroxides and UVC-based treatments toward the target pollutant in aqueous samples.•Treatments based on inorganic peroxides and UVC as useful methods for degrading the β-lactam antibiotic dicloxacillin.•Persulfates and UV-C/H2O2 showed high degrading action on the target pharmaceutical.•Methodologies based on theoretical calculations for the identification of reactive moieties on the DXC susceptible to radical attacks are presented.

Measurement and evaluation of the flashover voltage on polluted cap and pin insulator: An experimental and theoretical study

This study investigates the flashover voltage on high voltage insulators in polluted environments, employing a combination of experimental and theoretical approaches. Utilizing Analysis of Variance (ANOVA) and the Finite Element Method (FEM), the research aims to offer a thorough comprehension of the phenomenon. The experimental aspect of the study involves subjecting insulators to polluted environments, replicating real-world scenarios, and measuring the resulting flashover voltages. This experimental study focuses on investigating flashover pollution, where artificial pollution is introduced into an experimental model. An observational approach is employed to assess the impact of conductivity and pollution distribution on the 1512 L cap and pin insulator, as well as its proposed experimental model. Complementing the experimental approach, the theoretical aspect of the study employs the FEM method to simulate and model the insulator's behaviour under pollution. This computational technique enables a detailed analysis of the electrical field distribution, surface potential, and stress repartition across the surface of the insulator. Simulations further explore the impact of pollution on flashover voltage and leakage current. The FEM results are then compared with experimental findings to validate the model's accuracy and reliability. By analyzing the collected data, the ANOVA technique is applied to identify significant differences in flashover voltage under diverse pollution levels. This statistical approach allows for the determination of the most influential factors affecting insulator performance. This research offers valuable insights into the influence of flashover voltage on high-voltage insulators in polluted environments, contributing to the development of more robust and efficient insulation systems. The combination of ANOVA and FEM methods provides a robust framework for understanding and predicting insulator performance, ultimately benefiting the power industry and promoting energy sustainability.

Clathrate Hydrates as a Kind of Promising Ice Nanoreactors.

Since their discovery, clathrate hydrates (CHs) have received great attention both from theoretical and experimental aspects due to their great potential for gas storage and prospective applications as icy crystal materials. However, there has been limited research on the decomposition, reduction or other reactions of gases enclosed in CHs. Thanks to their unique hydrogen bonding network and cavity structures, CHs can serve as the promising nanoreactors to achieve chemical conversions, e. g. reducing greenhouse gases. In this review-type article, we characterize the potential performance of such CHs nanoreactors by discussing their multiple functions including important roles of hydrogen bonds in CHs, e. g. the confinement effect and proton source, and then discuss the enhanced electron-binding ability of guest molecules and the structures and properties of trapped electrons in the stacked nanocages, which contribute to our understanding of chemical reactions occurring in CHs. Finally, we provide detailed analyses of representative reaction mechanisms underwent in CH nanoreactors and effective calculational and molecular dynamics simulation methods. This review-type article aims to provide a detailed summary about the functional characteristics of CHs and reactivity in CHs, which make CHs a kind of promising icy nanoreactors.

Experiences of early career researchers: Influences on the design and reporting of animal experiments, and the practical and emotional support needed to enhance best practice methods.

While best practice methodology in animal research aims to address reproducibility and translational issues, awareness and implementation remains low. Preclinical systematic reviews have highlighted many flaws, including issues with internal validity and reporting. With early career researchers (ECRs) heavily involved in all aspects of animal experiments, it is crucial we understand what shapes their research practices. Semi-structured interviews were conducted with 13 ECRs, including research masters, PhD and postdoctoral academics. Data were collected and analysed concurrently using constant comparison techniques and an iterative approach. Findings revealed low-level awareness of best practice recommendations but a desire to engage in dedicated workshops on designing and reporting animal experiments. Current laboratory practices and previous literature were main influences on research practice, more than institutional training. An unexpected finding was the discovery of ethical and emotional dilemmas ECRs faced when working with animals. This highlights the need for a multifaceted approach to better support junior researchers, both emotionally and practically, to encourage responsible science.

Numerical simulation study on opening blood–brain barrier by ultrasonic cavitation

Experimental studies have shown that ultrasonic cavitation can reversibly open the blood–brain barrier (BBB) to assist drug delivery. Nevertheless, the majority of the present study focused on experimental aspects of BBB opening. In this study, we developed a three-bubble-liquid-solid model to investigate the dynamic behavior of multiple bubbles within the blood vessels, and elucidate the physical mechanism of drug molecules through endothelial cells under ultrasonic cavitation excitation. The results showed that the large bubbles have a significant inhibitory effect on the movement of small bubbles, and the vibration morphology of intravascular microbubbles was affected by the acoustic parameters, microbubble size, and the distance between the microbubbles. The ultrasonic cavitation can significantly enhance the unidirectional flux of drug molecules, and the unidirectional flux growth rate of the wall can reach more than 5 %. Microjets and shock waves emitted from microbubbles generate different stress distribution patterns on the vascular wall, which in turn affects the pore size of the vessel wall and the permeability of drug molecules. The vibration morphology of microbubbles is related to the concentration, arrangement and scale of microbubbles, and the drug permeation impact can be enhanced by optimizing bubble size and acoustic parameters. The results offer an extensive depiction of the factors influencing the blood–brain barrier opening through ultrasonic cavitation, and the model may provide a potential technique to actively regulate the penetration capacity of drugs through endothelial layer of the neurovascular system by regulating BBB opening.

SERS microscopy as a tool for comprehensive biochemical characterization in complex samples.

Surface enhanced Raman scattering (SERS) spectra of biomaterials such as cells or tissues can be used to obtain biochemical information from nanoscopic volumes in these heterogeneous samples. This tutorial review discusses the factors that determine the outcome of a SERS experiment in complex bioorganic samples. They are related to the SERS process itself, the possibility to selectively probe certain regions or constituents of a sample, and the retrieval of the vibrational information in order to identify molecules and their interaction. After introducing basic aspects of SERS experiments in the context of biocompatible environments, spectroscopy in typical microscopic settings is exemplified, including the possibilities to combine SERS with other linear and non-linear microscopic tools, and to exploit approaches that improve lateral and temporal resolution. In particular the great variation of data in a SERS experiment calls for robust data analysis tools. Approaches will be introduced that have been originally developed in the field of bioinformatics for the application to omics data and that show specific potential in the analysis of SERS data. They include the use of simulated data and machine learning tools that can yield chemical information beyond achieving spectral classification.

An In-Silico Drug Designing Approach Attempted on a Newly Synthesized Co(II) Complex along with its Other Biological Activities: A Combined Investigation of both Experimental and Theoretical Aspects.

A new Co (II) complex incorporating a novel Schiff base ligand acquired from the condensation of 3,3'-Methylenedianiline and 2-Hydroxy-5-bromobenzaldehyde was synthesized and characterized. The synthesized complex was air and moisture stable, monomeric, and non-electrolytic in nature. Based on physical and spectral studies, tetrahedral conformation was ascribed to the synthesized Co (II) complex.Density Functional Theory (DFT) was used to analysis different electronic parameters of the optimized structure of Co(II) complex to reveal its stability.Using different analytic and spectroscopic techniques, the new Co (II) complex was established to interact with DNA quite effectively and works as an efficient metallo intercalators. The synthesized complex was discovered to cleave DNA significantly, so it can be inferred that the complex will inhibit the growth of pathogens. Molecular docking was performed to check the binding affinity of the cobalt complex with different receptors, responsible for different diseases. Proteins like progesterone receptor and induced myeloid leukemia cell differentiation Mcl-1 protein showed high binding affinity with this complex, and hence the complex might have some implications for inhibition of progesterone hormones in biological systems. Biological activity of the Co (II) complex was also predicted through computational analysis with SwissADME.Using strains of Escherichia coli, Klebsiella pneumoniae, Bacillus subtilis, and Staphylococcus aureus, an in vitro antibacterial activity of the ligand and Co (II) complex was carried out. This activity was further validated by a molecular docking investigation.

Improving energy consumption for dynamic intake and exhaust FAÇADES: A new setup design: Part B

Dynamic insulation technology adjusts thermal resistance to reduce building energy consumption in response to climate changes. Sustainable building practices prioritize optimizing the building envelope to enhance energy efficiency and regulate the interaction between indoor and outdoor environments. The previous part of this study (Part A) provided an overview of dynamic insulation technology and its potential effectiveness in Iraqi structures with intermittent heating and cooling. The successful implementation of dynamic thermal insulation necessitates careful planning and design solutions that balance performance and efficiency. This paper (Part B) three wall models (static, dynamic, modified dynamic) to evaluate their thermal performance during the heating season. The results demonstrate that the intake facade achieves a preheating efficiency of 77% for the dynamic wall and 81.8% for the modified dynamic wall at the maximum permissible fresh air limit. This improvement in efficiency enhances the quality and conditions of fresh air intake. Additionally, the modified dynamic wall exhibits a notable 50% reduction in pressure loss compared to the dynamic wall, resulting in lower intake or exhaust fan power and thus energy consumption. The results of this paper will guide the presentation of cooling season results and the experimental aspect of future work, offering valuable insights for further exploration. Practical applications This study aims to enhance the efficiency of dynamic facades by investigating the physical phenomena within wall layers. The paper delves into the determination of optimal airflow patterns within facades, the assessment of airflow path modifications, and the evaluation of energy efficiency achieved by implementing dynamic insulation at the intake and exhaust facades during the heating season. The findings contribute to streamlining design complexities and expanding design options for specific climates, thereby ensuring the pragmatic implementation of this technology.

33S NMR: Recent Advances and Applications.

The purpose of this review is to present advances and applications of 33S NMR, which is an underutilized NMR spectroscopy. Experimental NMR aspects in solution, chemical shift tendencies, and quadrupolar relaxation parameters will be briefly summarized. Emphasis will be given to advances and applications in the emerging fields of solid-state and DFT computations of 33S NMR parameters. The majority of the examples were taken from the last twenty years and were selected on the basis of their importance to provide structural, electronic, and dynamic information that is difficult to obtain by other techniques.

Effect of an inquiry-based teaching sequence on secondary school students’ understanding of wave optics

Wave optics is a mandatory part of Croatian secondary school physics curriculum for students in the final year of secondary school (age 18–19). Many physics education research studies have shown that it is a difficult physics topic for both university and secondary school students. An inquiry-based teaching sequence on wave optics, designed for eight 45-min teaching periods, was developed by the authors. The sequence included four investigative students’ experiments on the topics of interference, diffraction, and polarization of light, as well as several teacher demonstrations. The experimental group included six classes of students from six different Croatian urban secondary schools, who underwent the teaching intervention with the new inquiry-based sequence on wave optics, whereas the control group consisted of six classes from the same schools, taught in a predominantly lecturing way. Both groups were post-tested with the same instrument, the Conceptual Survey on Wave Optics (CSWO), to evaluate the research hypothesis that the new sequence might improve students’ conceptual understanding better than the traditional teaching. The results of the experimental and control groups were analyzed and compared using the Rasch analysis. The results show that the experimental group outperformed the control group in four out of five conceptual areas probed by the CSWO, suggesting that the new inquiry-based teaching sequence may contribute to stronger development of secondary school students’ conceptual understanding of wave optics, especially concerning typical wave optics patterns, reasoning from experiments, and explaining basic wave optics phenomena. A questionnaire on attitudes toward the teaching intervention was administered to students and it was found that students generally liked the inquiry-based teaching intervention and expressed positive attitudes to interactive, experimental, and collaborative aspects of physics teaching. The results are very promising, but their generalization may be limited by the selection of the students, as well as by the short duration of the teaching intervention and the relatively small breadth of the covered topics. Published by the American Physical Society 2024

Reaction mechanism and kinetic study on the methanol dominated gas-based reduction process

Alcohols, represented by methanol, have received attention as a new type of reducing agent in various fields, including carbide synthesis, surface carburization etc. In order to clarify the reduction routes, reaction mechanisms and influencing factors on the morphology of the products during the methanol dominated reduction process, this work examined the preparation of molybdenum hemicarbide by reducing and carbonizing MoO3 with methanol. We used a combination of thermodynamic calculations, thermogravimetric analysis and XRD to clarify the reduction path of MoO3 at different temperatures, and characterized the morphology evolution of the product using SEM. Furthermore, a novel kinetic mathematical model was proposed to account for the intricate reaction involving methanol and multivalent oxide, which incorporated numerous parameters with practical physical significance, enhancing its predictive precision. In summary, our findings provide valuable insights into thermodynamics, kinetics, and experimental aspects of reactions involving methanol, offering guidance for controlled carbide particle synthesis.

Shape of a Rotating Slinky

If a Slinky suspended in a U-shape is rotated horizontally, it will have the shape of an upside-down [Formula: see text], like [Formula: see text], due to the centrifugal force in the horizontal direction acting on each point of the Slinky. In this paper, we discuss the shape of a rotating Slinky in both theoretical and experimental aspects. The rotating Slinky has the shape described by a multi-valued function if the angular velocity of the rotation satisfies [Formula: see text]. Our theoretical results are in good agreement with experimental observations. The video of the experiments can be viewed at https://youtu.be/rpu9Ol2jdAM .

Performance evaluation of full-scale façades: design support tools

The research identifies an innovative process for the performance assessment of façades. Starting from the harmonised technical specifications, it defines a Method Statement that considers the responses to climate change in progress. This document, drawn up based on know-how gained as a result of experiments conducted on façade components, was created as a support tool for the National Technical Assessment body-TAB. The methodology is deductive with an interdisciplinary approach applied to testing activities in its obligatory and experimental aspects. The research is based on process innovation, performance evaluations and quality controls of the project from a constructive-environmental perspective.

Experimental and theoretical aspects of magnetic circular dichroism and magnetic circularly polarized luminescence in the UV, visible and IR ranges: A review

A historical sketch of the MCD (magnetic circular dichroism) spectroscopy is reported in its experimental and theoretical aspects. MCPL (magnetic circularly polarized luminescence) is also considered. The main studies are presented encompassing porphyrinoid systems, aggregates and materials, as well as simple organic molecules useful for the advancement of the interpretation. The MCD of chiral systems is discussed with special attention to new studies of natural products with potential pharmaceutical valence, including Amaryllidaceae alkaloids and related isocarbostyrils. Finally, the vibrational form of MCD, called MVCD, which is recorded in the IR part of the spectrum is also discussed. A final brief note on perspectives is given.

Quantitative phase imaging techniques for measuring scattering properties of cells and tissues: a review-part II.

Quantitative phase imaging (QPI) is a non-invasive, label-free technique that provides intrinsic information about the sample under study. Such information includes the structure, function, and dynamics of the sample. QPI overcomes the limitations of conventional fluorescence microscopy in terms of phototoxicity to the sample and photobleaching of the fluorophore. As such, the application of QPI in estimating the three-dimensional (3D) structure and dynamics is well-suited for a range of samples from intracellular organelles to highly scattering multicellular samples while allowing for longer observation windows. We aim to provide a comprehensive review of 3D QPI and related phase-based measurement techniques along with a discussion of methods for the estimation of sample dynamics. We present information collected from 106 publications that cover the theoretical description of 3D light scattering and the implementation of related measurement techniques for the study of the structure and dynamics of the sample. We conclude with a discussion of the applications of the reviewed techniques in the biomedical field. QPI has been successfully applied to 3D sample imaging. The scattering-based contrast provides measurements of intrinsic quantities of the sample that are indicative of disease state, stage of growth, or overall dynamics. We reviewed state-of-the-art QPI techniques for 3D imaging and dynamics estimation of biological samples. Both theoretical and experimental aspects of various techniques were discussed. We also presented the applications of the discussed techniques as applied to biomedicine and biology research.

Selective separation and recovery of valuable metals through directional vulcanization of black copper sludge

The recovery of copper (Cu) from secondary sources has emerged as a promising trend in the copper industry’s advancement. Black copper sludge (BCS), a valuable hazardous waste produced during Cu electrolytic refining, contains various precious metals, including Cu3As. This study investigates theoretical and experimental aspects using BCS as a raw material to mitigate solid waste emissions and retrieve valuable metals. The proposed method for separating Cu from As through directional sulfidation offers an environmentally friendly solution. Gibbs free energies of the sulfidation reaction between BCS and S were calculated using HSC Chemistry 9.0, with experimental validation confirming the method’s feasibility. The study explores the effects of vulcanization temperature, holding time, and S content during the vulcanization reaction. Under optimal conditions of 873 K temperature, 60 min holding time, and 20 % excess S, Cu existed as Cu2S in the sulfide residue, while As2O3 was observed as a condensate. Cu and As recovery rates were 98.38 % and 84.62 % respectively, with a 99.98 % removal efficiency for Cu volatiles and 94.36 % for As residue. This method effectively separates Cu and As from solid wastes containing As, offering a simpler and more environmentally friendly alternative to traditional pyrometallurgical and hydrometallurgical methods. The study presents a novel, eco-friendly, and highly efficient approach for the safe disposal of As-containing solid waste.

Laboratory and Numerical Investigation of Pre-Tensioned Reinforced Concrete Railway Sleepers Combined with Plastic Fiber Reinforcement.

This research investigates the application of plastic fiber reinforcement in pre-tensioned reinforced concrete railway sleepers, conducting an in-depth examination in both experimental and computational aspects. Utilizing 3-point bending tests and the GOM ARAMIS system for Digital Image Correlation, this study meticulously evaluates the structural responses and crack development in conventional and plastic fiber-reinforced sleepers under varying bending moments. Complementing these tests, the investigation employs ABAQUS' advanced finite element modeling to enhance the analysis, ensuring precise calibration and validation of the numerical models. This dual approach comprehensively explains the mechanical behavior differences and stresses within the examined structures. The incorporation of plastic fibers not only demonstrates a significant improvement in mechanical strength and crack resistance but paves the way for advancements in railway sleeper technology. By shedding light on the enhanced durability and performance of reinforced concrete structures, this study makes a significant contribution to civil engineering materials science, highlighting the potential for innovative material applications in the construction industry.

Thermodynamic modeling of pressure-dependent phase diagram in alkali metals Li, Na and K

The high-pressure behavior of the alkali metals has attracted much attention in both experimental and theoretical aspects. This study is focused on the thermodynamic optimization of the temperature and pressure dependence of the molar volumes, the compressibility and phase diagrams of Li, Na and K according to the CALPHAD method. The pressure-temperature phase diagrams of lithium, sodium and potassium up to 50–100 GPa were calculated using the obtained thermodynamic parameters. The available experimental data, such as extremely low melting temperatures at high pressure, pressure-induced structural transitions between simple bcc and fcc crystals and the molar volume changes with the increasing pressure, were well reproduced in our calculations. The good agreements between our calculations and the experiments assessed in the literature indicated that our thermodynamic parameters are reasonable. Our thermodynamic calculations would assist to understand the phase transitions and structural properties of alkali metals at high pressure.

Semi-analytical modeling and vibration analysis of bolted frame structure under non-uniform pretension

Most of the frame structures in mechanical equipment are connected by bolts, and the non-uniform pretension among the bolts will have an obvious impact on the vibration characteristic parameters of the frame structure. In this paper, semi-analytical modeling and vibration analysis of a frame structure considering non-uniform pretension of bolts are carried out based on the Timoshenko beam theory and Rayleigh-Ritz method. Specifically, a method is proposed to decompose the frame structure into several substructures and model them respectively, and further the coupling springs are applied among the substructures. Through the vibration test of a beam lap structure with a bolted joint, the analytical expressions between bolt pretension and bolted joint stiffness and damping parameters are obtained. Moreover, the method of simulating the non-uniform pretension among each bolted joint is proposed. Considering the external factors such as reinforcing rib structures and flexible rod exciter, and a complete semi-analytical dynamic model of the bolted frame structure introducing the non-uniform pretension is further established. A case study is carried out on a frame structure that contains four connecting bolts with non-uniform pretension. The natural characteristics of the frame structure are solved by using the developed modeling method, and the rationality of the analysis results is verified by experiments. Based on this, the increasing trends of the resonant frequencies and the resonant response of the frame structure under different pretension conditions are analyzed from two aspects of experiment and simulation.