Comparative Experimental Study Research Articles

Autologous Serum Eye Drops Diluted with Cyclosporine A 0.05% and Sodium Hyaluronate 0.1%: An Experimental Comparative Study

Purpose The purpose of this study was to assess in-vitro efficacy of a suffusion of autologous serum withcyclosporine 0.05% (CsA) and sodium hyaluronate 0.1% (SH). Methods The expression of proinflammatory markers interleukin 6 (IL-6) and TNF-Alpha (TNF-α) in limbal epithelial cells was evaluated. Also, assessment of the stability of epithelial growth factor and transforming growth factor-beta (EGF, TGF-β) in the 50% combinations with autologous serum (AS) was done. The characteristics (pH, density, osmolality) of the two combinations were also evaluated. Additionally, cytotoxicity effect of given test compounds was evaluated on human limbal epithelial cells (LEpiC). Results The percentage of cells expressing IL-6 subjected to AS + SH and AS + CsA were 6.23% and 5.69% respectively. There was no significant difference in percentage of cells expressing TNF-α between the formulations (5.87%, 5.83% respectively). The growth factors; EGF and TGF-β remained stable forone month duration (on 2 and 4 weeks) at 4 °C without significant difference between the time intervals tested. The results of MTT assay suggested that limbal epithelial cells treated with AS + CsA and AS + SH combinations showed minimal toxicity however it was not significant statistically (p ≤ 0.05). Conclusion Two test combinations (AS + CsA, AS + SH) showed stable growth factors (EGF, TGF-β) and good anti-inflammatory property against pro-inflammatory markers. Also, the 2 combinations were found safe on cultured limbal epithelial cells. The novel combination of autologous serum in CsA may provide added benefit in dry eye disease (DED) through their combined anti-inflammatory and epitheliotropic effects.

Heatwave-induced functional shifts in zooplankton communities result in weaker top-down control on phytoplankton.

Freshwater ecosystems are increasingly affected by rising annual mean temperatures and heatwaves. While heatwaves are expected to have more immediate effects than mean temperature increases on local communities, comparative experimental studies are largely lacking. We conducted a 1-month mesocosm experiment to test the effect of different warming treatments, constantly raised temperatures (+3°C) and recurring heatwaves (+6°C), on plankton communities. We specifically tested how shifts in zooplankton trait composition and functional groups are reflected in ecosystem function (top-down control on primary producers). We found that heatwaves had a stronger and more immediate effect on zooplankton trait composition (specifically on body length and body mass) and functional groups. Heatwaves led to the decrease of small-bodied grazers (i.e., Rotifera) and the dominance of larger omnivorous Copepoda, and these shifts resulted in weaker top-down control, leading to elevated phytoplankton biomass. Altogether, our results highlight the importance of the indirect effects of heatwaves via inducing shifts in zooplankton functional groups and trait composition, which may lead to algal blooms.

Investigation of structural, morphological, optical and electronic properties of Cu-doped PbS thin films: a comparative experimental and theoretical study

Thin film technology has emerged as a cornerstone in optoelectronics, enabling the fabrication of compact, lightweight devices with enhanced performance and efficiency through precise control of the nanoscale thicknesses of functional materials. The current study explores the impact of copper (Cu) doping (3.125%, 6.25%, and 12.5%) on lead (Pb) sites in PbS to examine the structural, morphological, electronic, optical, and thermoelectric characteristics, employing both experimental and theoretical approaches. Polycrystalline thin films of PbS are deposited by spin coating technique on glass substrates. The XRD study discloses the cubic crystal structure of pristine and Cu-doped PbS with nominal variation in d-spacing. Surface morphological investigations reveal that Cu-doping transforms the coffee beans like grains to nanoplates that significantly affect the surface homogeneity and porosity. The tuning of band structure in the visible range, 1.64–2.21 eV is witnessed in the band structure analysis. Moreover, the experimental results are complemented by a theoretical study using WIEN2k software. Theoretical study exhibits the direct bandgap nature and with the incorporation of Cu, it increases from 0.89 to 2.11 eV. The density of states spectra for Cu-doped PbS exhibits strong hybridization between p-states of Pb and S, and d-states of Cu. Optical findings demonstrate significant variations in the absorption spectrum, which result in modifications in the optical energy band gap and peculiar optical parameters of doped samples. At room temperature, the increase in electrical conductivity (σ/τ) from 0.2 × 1020 (Ω.m.s)−1 for PbS to 0.3 × 1020, 3.1 × 1020 and 7.8 × 1020 (Ω.m.s)−1, thermal conductivity from 0.25 × 1014 W m.K.s−1 to 0.30 × 1014, 2.4 × 1014 and 5.2 × 1014 W m.K.s−1 and decrease in Seebeck coefficient from 72 to 35, 13 and 8 μV/K with the inclusion of Cu up to 3.125, 6.25 and 12.5% offer the potential for advancing thermoelectric technology. This could lead to improved efficiency and practical utilization in energy harvesting and waste heat recovery.

Comparative experimental and theoretical study of thermal and rheological features of Cu/PAM/DW and water/PAM/SiO2 individual polynanofluids

Comparative experimental and theoretical study of thermal and rheological features of Cu/PAM/DW and water/PAM/SiO2 individual polynanofluids

Dynamic response of UHMWPE/polyurea composite plates under combined blast and ballistic impact

Combined load caused by blast impulse and fragmentation impact poses a synergetic damage threat to the protective structure. To improve the blast and ballistic impact resistance of Ultra-high molecular weight polyethylene (UHMWPE), polyurea coated Ultra-high molecular weight polyethylene structure was proposed, and the composite structures with different coating thickness and coating position were prepared. Composite projectiles formed by combining foam projectiles and steel projectiles were launched by light gas gun to simulate the combined load of explosion impact and fragmentation. Comparative experimental studies were carried out. The experimental results show that the polyurea layer has good elastic properties, preventing the excessive deformation of the PE layer. The polyurea coating position and the time interval of the combined load show significant influence on the impact resistance of the composite structure. When the load was relatively low, PE plate with polyurea coating on booth face has both the advantages of PE plate with coating on the front and back face, but when the load increased, the impact resistance potential of polyurea layer was not fully developed. With the increase of the combined load, structures with polyurea coating on the back face has a good resistance of combined impact.

Anti-turbulent efficiency of oil-soluble polymer solutions and colloid systems flowing through cylindrical channel

Relevance. The use of anti-turbulent additives for transporting hydrocarbon liquids through main pipelines allows reducing significantly the energy consumption of pumping power stations. Aim. Comparative analysis of the anti-turbulent efficiency of high-molecular polymers and compositions of surfactants. Methods. Laboratory-scale experimentation aimed to study the flow of dilute polymer solutions and dispersed surfactant systems through a cylindrical channel of a turbulent rheometer. Results. The author has carried out the comparative experimental studies of the anti-turbulent efficiency of extremely dilute solutions of polymers and colloidal systems. The results were obtained that suggest a higher anti-turbulent efficiency of high-molecular-weight polymers compared to micellar surfactant systems. Solutions of high molecular weight polybutadiene and aluminum polyhydroxydicarboxylates in gasoline were used as samples for the experimental comparison of hydrodynamic efficiency. The paper describes the laboratory setup, on which the studies were carried out, and introduces the formulas used for quantitative calculations. The structure of polymer solutions and colloidal systems is considered and a theoretical explanation is given for the preferential use in industrial practice of high-molecular polymers in extremely low concentrations in real pipelines. It was found out that the mechanisms of degradation of antiturbulent properties of polymer solutions and dispersed surfactant systems are different. This is due to the difference in the structure of macromolar coils of polymer with an immobilized solvent and that of micelles from low molecular amphiphilic compounds. The paper introduces the arguments that explain the degradation of the antiturbulent properties of polymers not by the destruction of carbon-chain macromolecules, but by decomposition in a turbulent flow of the original large associates, consisting of a large number of chains, into individual and smaller macromolecular coils with an immobilized solvent.

Effect of solvent pre-treatment on microwave assisted pyrolysis of Spirulina (Algal Biomass) and Ficus benghalensis (Lignocellulosic Biomass) for production of biofuels: comparative experimental studies

Effect of solvent pre-treatment on microwave assisted pyrolysis of Spirulina (Algal Biomass) and Ficus benghalensis (Lignocellulosic Biomass) for production of biofuels: comparative experimental studies

Effects of Resistance Training, Estrogen Therapy, and Calcium Chitosan Supplement Containing Vitamin D on Bone Turnover in Ovariectomized Rats: An Experimental-Comparative Study

Background: Hormone therapy is a highly effective method for treating menopausal disorders. However, its side effects may include an increased risk of cancer, heart disease, and pulmonary embolism. Previous research has demonstrated that both exercise and nutrition separately have positive effects on menopausal symptoms. Therefore, we suggest that combining exercise and nutrition interventions may provide a synergistic effect, yielding results at least similar to those of estrogen (Est) therapy. Objectives: This study aims to compare the independent and combined effects of resistance training (RT), Est therapy, and vitamin D calcium chitosan (Vit D + Ca++ + Chit) supplementation on markers of bone turnover in ovariectomized (OVX) rats. Methods: Forty-two female Wistar rats were randomly divided into seven groups (n = 6 per group): (1) healthy-control (He-Co), (2) OVX-Vit D + Ca++ + Chit + RT, (3) OVX-saline (Sal) + Est + RT, (4) Sal + RT, (5) OVX-Vit D + Ca++ +Chit, (6) OVX-Sal + Est, and (7) OVX-Control (OVX-Co). Bone samples were extracted 48 hours after the final session. Two-way ANOVAs were used to determine differences in intervention effects between groups. The alpha level was set to 0.05. Results: Ovariectomy (OVX) decreased bone tissue expression of alkaline phosphatase (ALP) and osterix (OSX) while increasing peroxisome proliferator-activated receptor gamma (PPAR-γ) gene expression. Ovariectomy also decreased the number of osteocytes and osteoblasts while increasing the number of osteoclasts. Resistance training (RT) and Vit D + Ca++ + Chit intake increased bone tissue expression of ALP, OSX, and PPAR-γ gene expression. Additionally, RT and Vit D + Ca++ + Chit supplementation increased the number of osteocytes and osteoblasts and decreased the number of osteoclasts. Conclusions: The combined interventions had synergistic effects compared to each intervention separately on ALP, osteocyte, osteoblast, and osteoclast observations. Therefore, combining RT with Vit D + Ca++ + Chit could be a non-pharmacological approach to address bone turnover alterations caused by OVX.

A Comparative Experimental and Computational Study on the Nature of the Pangolin-CoV and COVID-19 Omicron

The relationship between pangolin-CoV and SARS-CoV-2 has been a subject of debate. Further evidence of a special relationship between the two viruses can be found by the fact that all known COVID-19 viruses have an abnormally hard outer shell (low M disorder, i.e., low content of intrinsically disordered residues in the membrane (M) protein) that so far has been found in CoVs associated with burrowing animals, such as rabbits and pangolins, in which transmission involves virus remaining in buried feces for a long time. While a hard outer shell is necessary for viral survival, a harder inner shell could also help. For this reason, the N disorder range of pangolin-CoVs, not bat-CoVs, more closely matches that of SARS-CoV-2, especially when Omicron is included. The low N disorder (i.e., low content of intrinsically disordered residues in the nucleocapsid (N) protein), first observed in pangolin-CoV-2017 and later in Omicron, is associated with attenuation according to the Shell-Disorder Model. Our experimental study revealed that pangolin-CoV-2017 and SARS-CoV-2 Omicron (XBB.1.16 subvariant) show similar attenuations with respect to viral growth and plaque formation. Subtle differences have been observed that are consistent with disorder-centric computational analysis.

A Comparative Experimental and Computational Study on the Nature of the Pangolin-CoV and COVID-19 Omicron.

The relationship between pangolin-CoV and SARS-CoV-2 has been a subject of debate. Further evidence of a special relationship between the two viruses can be found by the fact that all known COVID-19 viruses have an abnormally hard outer shell (low M disorder, i.e., low content of intrinsically disordered residues in the membrane (M) protein) that so far has been found in CoVs associated with burrowing animals, such as rabbits and pangolins, in which transmission involves virus remaining in buried feces for a long time. While a hard outer shell is necessary for viral survival, a harder inner shell could also help. For this reason, the N disorder range of pangolin-CoVs, not bat-CoVs, more closely matches that of SARS-CoV-2, especially when Omicron is included. The low N disorder (i.e., low content of intrinsically disordered residues in the nucleocapsid (N) protein), first observed in pangolin-CoV-2017 and later in Omicron, is associated with attenuation according to the Shell-Disorder Model. Our experimental study revealed that pangolin-CoV-2017 and SARS-CoV-2 Omicron (XBB.1.16 subvariant) show similar attenuations with respect to viral growth and plaque formation. Subtle differences have been observed that are consistent with disorder-centric computational analysis.

Dynamic mechanical behavior of CNT-reinforced epoxy under medium-strain rate: A comparative study

Carbon nanotubes (CNTs) are generally recognized as one of the most effective fillers to improve the properties of polymeric materials. Subjected to dynamic loading, polymer-based materials often exhibit high strain rate sensitivity. This research investigates the effectiveness of CNTs fillers on the mechanical properties of an epoxy resin at low to medium strain rates through conducting a comparative experimental study. Performing tensile and shear tests, the elastic modulus and strength properties of CNT/epoxy and pure epoxy resin are measured at different strain rates. By proposing an empirical logarithmic relationship, the prediction of dynamic elastic modulus and strength properties at any desired low to medium strain rate is facilitated. For measuring the dynamic fracture toughness of CNT/epoxy and pure epoxy resin at medium strain rate, the instrumented charpy impact test based on the Dynamic Key Curves (DKC) method is used. Experimental measurements still imply on significant enhancements in axial and shear properties and also dynamic fracture toughness up to medium strain rates of 150 s−1 by adding small portion of CNTs.

Comparative experimental study of the effect of loading rate on the typical mechanical properties of bubble and clear ice cubes

Icing is a common liquid–solid phase change process that usually has negative effects. Bubbles will form in ice due to the fact that air is significantly less soluble in ice than it is in water. These bubbles will have an effect on its mechanical properties. To quantitatively investigate the effect of air bubbles on the mechanical strength of ice cube, an experimental setup is built to explore the mechanical strength and modulus of clear and bubble ice cubes at different loading rates. The results show that even a low volume fraction of air bubbles in the ice cubes as low as 1.98% can have a significant effect on their mechanical properties. The weakening of tensile, compressive and bending strengths by air bubbles is almost less than 20%, while the weakening of shear strength by air bubbles reaches almost 60%. The effect of air bubbles on the four typical mechanical moduli does not exceed 20%. This research helps to optimize the de-icing technique and also provides methods and ideas for preparing ice.

Output voltage control of DAB converters based on uncertainty and disturbance estimation.

The dual active bridge (DAB) converter is a power electronic device commonly used for DC voltage regulation and stabilization. However, during its control process, external disturbances, load variations, input voltage variations, switching tube voltage drops, dead time, etc. lead to errors in the control output, thus reducing the control accuracy of the system. Therefore, this article propose a robust control scheme for the output voltage based on uncertainty and disturbance estimator. In this article, an average small-signal model of the dual active bridge converter was established in terms of the basic principles and operation mechanisms, simplifying the controller's design. Then, the basic principles of the uncertainty and disturbance estimator (UDE) are introduced. The small-signal model of the dual active bridge (DAB) converter is applied to the UDE to minimize output voltage error by enabling the controller to directly regulate the shift ratio. Finally, this article discusses the application and effectiveness of the uncertainty and disturbance estimator (UDE) in the simulation and control of dual active bridge (DAB) converters. A series of experimental comparative studies are conducted, demonstrating that this scheme offers significant advantages in suppressing system uncertainties and disturbances.

Critical analysis of enhanced photovoltaic thermal systems: a comparative experimental study of PCM, TEG, and nanofluid applications

Phase change materials (PCM), thermoelectric generators (TEG), and nanofluids are popular methods investigated for improving conventional photovoltaic thermal (PVT) systems. These methods are particularly used in warm climates where high temperatures negatively impact photovoltaic (PV) power output and energy efficiency. This experimental study evaluated the effects of 32 °C melting point PCM and TEG integration on PVT units, as well as 42 °C melting point PCM and nanofluid incorporation on concentrated PVT (CPVT) units. Technical, exergetic, and economic performance were compared using a small-scale PVT module. Low-cost commercially available materials were used to construct all PVT units. Industrial metal waste was introduced to enhance the thermal conductivity of paraffin wax and salt hydrate PCMs. The results indicated that applying PCMs, porous media, and concentrator plates increased energy generation, potentially offsetting their higher initial cost and achieving an energy cost of approximately $0.135/kWh. However, TEG and nanofluid implementation remained uneconomical, leading to a 15–35 % increase in energy cost. The water-based CPVT unit, enhanced with paraffin wax and copper fins, demonstrated the best technical performance. This unit achieved electrical, thermal, and exergy efficiencies of approximately 15.5 %, 37.4 %, and 16.7 %, respectively, with more than a 20 % reduction in cell temperature. The study also revealed that severe structural changes caused by corrosion of metallic materials in hydrated PCMs could alter the melting point by more than 30 %. This change negatively impacts heat storage capacity. Conversely, incorporating metal chips in non-hydrated PCMs improved the time to reach the melting point state by 30–60 minutes.

A comparative experimental study of the drilling and milling of a newly developed AFRP/SS/AFRP co-cured material

A comparative experimental study of the drilling and milling of a newly developed AFRP/SS/AFRP co-cured material

Long-term aging simulation of asphalt mixture: A comparative experimental study

In this study, the efficacy of the extended oven aging procedure outlined in NCHRP 973 for generating laboratory-produced reclaimed asphalt pavement (RAP) was explored. The study also sought to establish a correlation between the results obtained from the aged bitumen extracted from oven-aged asphalt mixture and PAV-aged bitumen. Both aging techniques, with varying durations, were applied, and a series of tests, encompassing penetration, softening point, rotational viscosity, bending beam rheometer, temperature sweep using dynamic shear rheometer, and FTIR, were conducted for comprehensive comparison. The outcomes revealed that the oven aging procedure has limited applicability for simulating the long-term aging of asphalt mixtures. At the temperature of 95°C, an increase in the oven aging duration had minimal impact on the degree of aging, especially beyond five days, as evidenced by various parameters such as penetration, softening point, viscosity, master curves of viscoelastic properties, aging index, and low-, intermediate-, and high-temperature characteristics of the different aged bitumens. Furthermore, a comparative analysis between PAV and bitumen extracted from oven-aged asphalt mixture indicated that bitumen aged for five days in the oven exhibited analogous properties to bitumen subjected to 1 cycle of PAV aging, encompassing chemical, rheological, and physical test results. In conclusion, while some researchers have suggested that performing 2 or 3 cycles of PAV aging may be necessary to simulate long-term aging, the findings indicate that oven aging of asphalt mixture cannot effectively simulate aging characteristics beyond 1 cycle of PAV aging.

Experimental investigation of 3D printed polylactic acid and polylactic acid – hydroxyapatite composite through material extrusion technique for biomedical application

In biomedical industries, composite additive manufacturing are employed for customization, quicker production, efficient use and capital reduction. This experimental work focuses on the development of poly lactic acid (PLA) and novel extruded hydroxyapatite (HA) reinforced poly lactic acid (HPLA) by material extrusion (ME) technique and their properties were compared with that of standard 3D printed PLA. The extruded composite filaments were subjected to thermal characterization (DSC, TGA) and chemical characterization (FTIR) to ensure filament quality and its implementation in ME technique for 3D printing process. In addition, the melt compounded composite filaments were subjected to annealing to observe the influence of heat treatment upon their mechanical properties and thereby to validate their potential to resist breakage during ME process. Taguchi orthogonal array method using MiniTab software is employed to execute the parameter optimization for the 3D printing process. The 3D printed tensile, flexural and impact specimens, using pure PLA and extruded composite filaments, as per American Society for Testing and Materials (ASTM) standards were subjected to a comparative experimental study which showed that 3D printed specimens using PLA and HPLA performed better than that of standard PLA specimens due to the improvement in their crystalline nature. The ruptured specimens were subjected to microstructural characterization (optical microscopy, SEM) to observe failure modes and ash content test was conducted to validate the homogenous distribution HA filler particles in PLA matrix. In addition, mechanical characterization was also performed on 3D printed bone plate/bone scaffold application using extruded filaments of PLA and HPLA, as per ASTM F543 standards, to validate incorporation of the composite filaments in real-time application in biomedical industry.

Seismic evaluation of a self-centering retrofit solution for modular steel structure connections

In this study, a novel plug-in modular steel structure (MSS) connection is proposed, in which the connector, cover plates, and bolts form a complete connecting system. To improve the seismic performance and post-earthquake functional recoverability of the MSS connection, a retrofit solution with diagonal self-centering (SC) haunch braces is introduced, and the self-centering modular steel structure (SC-MSS) connection is developed. Theoretical analysis of the mechanical properties of the MSS and SC-MSS connections are conducted, and the calculation formulas for the initial stiffness and bending bearing capacity are derived. A comparative experimental study of one MSS connection and five SC-MSS connections under cyclic loading was carried out to evaluate their seismic performance, and to explore the influences of the main haunch parameters on the behavior of the SC-MSS connection. The results demonstrate that the plug-in connector, cover plate, and bolts can realize reliable continuity and integrity between modules. The SC haunch braces have good collaborative work with the modules and provide sufficient restoring force, and the damage in all the SC-MSS connections was found to be effectively controlled and delayed as compared with the MSS connection. The MSS connection displays a full shuttle-shaped hysteretic response with adequate plastic development, while the SC-MSS connections successfully exhibit expected flag-shaped hysteretic responses with higher bearing capacity and lower residual displacement. The adjustment of the post-activation stiffness and pre-pressed force of the haunch brace is found to improve the connection performance, and a reasonable selection of the installation scheme could achieve optimal self-centering efficiency. The experimental results also verify the feasibility and correctness of the proposed theoretical formulas and mechanical assumptions.

Comparative experimental study on photothermal conversion and shape memory properties of MF-based flexible composite phase change materials loaded with carbon nanotubes and polydopamine

Efficient use of solar energy can effectively alleviate the problem of energy shortages. Currently, extensive researches have been carried out on photothermal conversion materials. However, factors such as photothermal conversion and thermal conductivity limit the practical implementation of photothermal materials. In this research, a novel flexible composite phase change material (CPCM) with melamine foam (MF) as the supporting skeleton, carbon nanotube (MWCNT)/polydopamine (PDA) as the light-absorbing coating and polyethylene glycol (PEG) as the energy storage material was successfully prepared. The results show that the MF-based CPCMs have good shape stability with a leakage of only 0.9 %, and high phase change enthalpies, the melting enthalpy was above 172.0 J/g. In addition, the thermal conductivity was improved due to the introduction of light-absorbing coatings into the CPCMs. Compared with MF/PEG, MWCNT/MF/PEG, and PDA/MF/PEG, MWCNT/PDA/MF/PEG were improved by 35.21 %, 8.6 % and 29.46 %, respectively. Finally, the average charging efficiency of MWCNT/PDA/MF/PEG is 96.26 %, which is 62.33 % and 20.1 % higher than that of MWCNT/MF/PEG and PDA/MF/PEG respectively, indicating that MWCNT and PDA nanofillers played a synergistic role in enhancing the performance of CPCMs. This study provides new and innovative ways for the design of photothermal materials.

A proposed model for enhancing e-bank transactions: an experimental comparative study

In this paper, we introduce a novel approach to address the dynamic prediction of customer activity in electronic payment transactions for individual clients. Our approach is founded on customer online payment transaction records from registered UK-based online retailers between 01/12/2009 and 09/12/2011. These retailers primarily specialize in unique gift items for various occasions, catering to a wide range of clients, including wholesalers. We used classification analysis based on the correlation coefficient to measure and describe a customer's electronic payment capability based on the quality of products they purchase. Furthermore, we trained multi-layered models (linear model, deep learning, random forest, and support vector machines (SVM)) to capture the dynamics of e-bank transaction reinforcement for retail customers using machine learning. Real transaction data from a UK online retailer was employed in our study. The experimental results consistently demonstrated the effectiveness of our proposed strategy.