Small Size Effect Research Articles

Alkali-assisted synthesis of ultrafine NiPt nanoparticles immobilized on La2O2CO3 for highly efficient dehydrogenation of hydrous hydrazine and hydrazine borane

Designing highly active and selective metal nanocatalysts for use in liquid chemical hydrides is highly attractive but remains a critical challenge. Herein, bimetallic NiPt nanoparticles (NPs) immobilized on lanthanum oxycarbonate (NiPt/La2O2CO3) have been facilely synthesized via an alkali-assisted reduction method. The introduction of NaOH is the key factor to the formation of the well-dispersed and ultrafine NiPt NPs (2.8 nm). The obtained Ni0.6Pt0.4/La2O2CO3 exhibits an extraordinarily high catalytic activity and 100% H2 selectivity for hydrous hydrazine dehydrogenation, providing a turnover frequency value (TOF) high up to 490 h−1 at 298 K. Additionally, the NiPt/La2O2CO3 prepared with NaOH demonstrates higher catalytic performance and lower activation energy than that of NiPt/La2O2CO3_N prepared without NaOH. Moreover, the NiPt/La2O2CO3 also shows an outstanding catalytic efficiency (TOF = 1200 h−1) for dehydrogenation of hydrazine borane at 298 K. The efficient catalytic performance may be attributed to the small size effect, the strong metal-support interaction, and the NaOH promotion effect. This alkali-assisted reduction method provides a new perspective for preparing of highly efficient catalysts in clean energy application.

The Application Status of Nanoscale Cellulose-Based Hydrogels in Tissue Engineering and Regenerative Biomedicine.

As a renewable, biodegradable, and non-toxic material with moderate mechanical and thermal properties, nanocellulose-based hydrogels are receiving immense consideration for various biomedical applications. With the unique properties of excellent skeletal structure (hydrophilic functional groups) and micro-nano size (small size effect), nanocellulose can maintain the three-dimensional structure of the hydrogel to a large extent, providing mechanical strength while ensuring the moisture content. Owing to its unique features, nanocellulose-based hydrogels have made excellent progress in research and development on tissue engineering, drug carriers, wound dressings, development of synthetic organs, 3D printing, and biosensing. This review provides an overview of the synthesis of different types of nanocellulose, including cellulose nanocrystals, cellulose nanofibers, and bacterial nanocellulose, and describes their unique features. It further provides an updated knowledge of the development of nanocellulose-based functional biomaterials for various biomedical applications. Finally, it discusses the future perspective of nanocellulose-based research for its advanced biomedical applications.

Miniaturized Self-Resonant Micro Coil Array with A Floating Structure for Wireless Multi-Channel Transmission.

Micro size antennas have significant merits due to the small size effect, enabling new device concepts. However, the low‐quality factor (Q‐factor), the large size of impedance matching components, and the poor selectivity of the multi‐array design remain challenging issues. To solve these issues, a floating coil structure stacked on a loop micro‐antenna is suggested. Various floating coil designs are prepared with appropriate matching conditions at specific target frequencies, using an easy fabrication process without the need for additional space. A simple one‐loop antenna design shows a higher Q‐factor than other, more complicated designs. The micro‐sized loop antenna with the 80 µm trace width design exhibits the highest Q‐factor, around 31 within 7 GHz. The 8 different floating coil designs result in high‐frequency selectivity from 1 to 7 GHz. The highest selectivity contrast and WPT efficiency are above 7 and around 1%, respectively. Considering the size of the antenna, the efficiency is not low, mainly due to the good matching effect with the high Q‐factor of the floating coil and the loop antenna. This micro‐antenna array concept with high integration density can be applied for advanced wireless neural stimulation or in wireless pixel array concepts in flexible displays.

Evaluating the sensitive question methods; recommended Uludag Adjustment for the Crosswise Model

Sensitive questions are frequently asked in medical, psychological, and sociological research. In the social science literature, it is widely accepted that when respondents are asked such questions, social desirability bias affects survey research. Different methods in the literature aimed to reduce measurement errors such as social desirability bias and increase the reliability of participants' answers. These methods address the problem to increase the effectiveness of predictions by using indirect questioning techniques. The sensitive question methods evaluated in this study are randomized response technique, grouped answer method, unmatched-count technique, and crosswise model. These methods were evaluated with a comprehensive simulation study. The performances of the methods were evaluated according to the sample size and the sensitive issue prevalence in the hypothetical population. In the second part, in order to reduce the small sample size and low prevalence effect of the crosswise model, the Uludag correction of the crosswise model was proposed in the study. As a result, the crosswise model performs quite well compared to the other methods. In the use of the crosswise model, it is recommended to use the Uludag correction of the model proposed in this study in cases where low prevalence and small samples are studied.

Scale-dependent torsional vibration response of non-circular nanoscale auxetic rods

In the current paper, analysis of torsional vibration behavior of non-circular nanorods made of auxetic honeycomb material is investigated for the first time. The triangular and elliptical cross-sections are selected to be analyzed. Moreover, one of the distinct properties of auxetic honeycomb materials is that they possess a negative Poisson’s ratio, which can be effective on the design and analysis of structures. In order to capture a small size or scale effect, the constitutive relation of nanorods is modified based on Eringen’s nonlocal elasticity theory (ENET). Hamilton’s principle is employed to obtain the kinematic relation of nanoscale rods. The nonlocal derived governing equations of non-circular auxetic nanorods are solved by utilizing an analytical method with respect to different boundary conditions. In order to verify the correctness of obtained outcomes, the results are compared to previous investigations, and good agreement can be observable. The influences of various parameters such as both Clamped–Clamped (C–C) and Clamped-Free (C-F) boundary conditions, nonlocal parameters, inclined angles, and geometrical ratios are explored and illustrated in the framework of several figures, which can be seen in detail.

Buckling of stepped nanobeams with intermediate supports

Investigated herein is the buckling behaviour of nonlocal elastic stepped nanobeams with intermediate supports, which are subjected to the axial compressions. The constitutive equations are established within the framework of Eringen’s nonlocal theory of elasticity to embrace the small size effect. An analytical method has been developed for the determination of critical buckling loads for axially loaded nanobeams with intermediate supports. The comparison of the degenerated results with the available work in the literature is found to be in close agreement. The small size effect, the intermediate support location, on the stability of nanobeams is thoroughly discussed by the parametric studies. The numerical simulations are carried out with the help of MATLAB tools.

Near-Infrared-Light-Modulated Lubricating Coating Enabled by Photothermal Microgels.

As a micro-/nano-sized hydrogel, polymeric microgel not only has three-dimensional (3D) molecular networks but also displays the small-size effect, which has been widely used in various fields, such as drug nanocarrier, photonic crystal, functional coating, and aqueous lubrication. In this work, a photothermal lubricating coating was prepared using polymeric/inorganic hybrid microgels and its surficial friction was deliberately modulated by the remote irradiation of near-infrared (NIR) light. Specifically, a photothermal hybrid microgel, Fe3O4@poly(N-isopropylacrylamide-co-polyacrylic acid) (Fe3O4@PNA), was first fabricated and then sprayed onto poly(ethyleneimine) (PEI)-modified substrate to form a lubricating microgel coating. At room temperature, this microgel coating was hydrophilic and achieved good hydration lubrication with relatively low friction. After the introduction of NIR light, the photothermal microgel coating converted light energy into heat energy for increasing its own temperature rapidly. Due to the thermosensitive PNA shell, the wettability of the coating was transformed to hydrophobicity above the lower critical solution temperature (LCST), resulting in a remarkable increase in friction. In other words, the surficial friction of this microgel coating could be reversibly modulated using NIR light. This work expands the application scope of microgels in the field of aqueous lubrication and introduces the functional microgels into making the smart lubricating coating for the first time. This basic research in the field of friction control may provide an efficient strategy for the design of interfacial sensing, controlled transmission, and intelligent manipulator.

Bioinert TiC ceramic coating prepared by laser cladding: Microstructures, wear resistance, and cytocompatibility of the coating

Recent advance in biological applications such as artificial joint replacement are focused towards fabricating reliable bearing surface to extend their service life. Given this perspective, incremental attempts have been made to enhance the wear resistance of titanium alloys used widely in artificial joint and mechanical reliability of brittle TiC ceramic, but plan often don't go along with reality. It is proposed that both high mechanical reliability and wear resistance can be hold if a thin TiC ceramic coating is formed onto high toughness Ti6Al4V alloy used widely in biological applications. In this paper, bioinert TiC ceramic coating was fabricated on Ti6Al4V substrate surfaces through laser cladding using preplaced TiC nanoceramic powders on the substrate surfaces. The microstructural characteristics of the TiC ceramic coating were investigated in detail. Further, the rapid melting mechanism of the TiC nanoparticles and the microstructural formation mechanism of the coating were revealed. Moreover, the wear mechanism and cytocompatibility of the coating were identified. The results showed that the original TiC nanoparticles completely melted and solidified to form dendritic TiC ceramic coating owing to the small size effect of the nanoparticles and the thermodynamic effect of the high-energy laser beam . The wear resistance of the TiC ceramic coating fabricated by laser cladding was three times higher than that of the Ti6Al4V substrate, and the coating had the same good cytocompatibility as that shown by Ti6Al4V. Microstructure-phase-property relationships in TiC ceramic coating were revealed and discussed according to our research findings. The designed TiC coating and Ti alloy hybrid might be potential application in artificial joint surfaces and other implants with strong wear-resistance requirements. • Bioinert TiC ceramic coatings on Ti6Al4V substrate was fabricated by laser cladding using preplaced TiC nanoparticles. • TiC dendrites were generated owing to the high-temperature diffusion of carbon atoms and Ostwald ripening mechanism. • The formation mechanism of ceramic coatings fabricated by laser cladding using TiC ceramic nano particles was proposed. • The coating showed comparable cytocompatibility to Ti alloy and did not affect cell adhesion, spreading, and proliferation.

Interfacing with Fe-N-C Sites Boosts the Formic Acid Dehydrogenation of Palladium Nanoparticles.

Hierarchical micro-/mesoporous carbons with abundant Fe-N-C sites were prepared through one-step carbonization of a metal-organic framework (MOF) with sodium iron ethylenediaminetetraacetic acid [NaFe(III)EDTA], which can facilitate the nucleation and growth of ultrafine (∼1.4 nm) and highly dispersed palladium nanoparticles (Pd NPs). Interfacing Pd NPs with Fe-N-C sites has been demonstrated for the first time to boost the heterogeneous catalysis of hydrogen production from formic acid, affording an ultrahigh turnover frequency (TOF) value of 7361 h-1 at 323 K. The robust synergistic interactions between Pd NPs and Fe-N-C sites together with the small size effects of Pd NPs are responsible for the enhanced catalytic activity.

Safety of nanometer powder control technology-based on mine gas explosion

Due to the rapid development of China and the increasing demand for various minerals, the accidents of mine operations have occurred frequently in recent years, which have caused a huge obstacle to the safety of the people’s lives and the prosperity and prosperity of the country. Not to be ignored, the response is also imminent. Based on the above background, this paper aims to study the safety of nano-material powder control technology on mine gas explosion suppression. In order to further analyze the influence of nanomaterials on explosion suppression and the improvement of safety performance, the flame propagation and pressure characteristic parameters of gas explosion were selected to evaluate the safety performance. In this paper, nano-calcium carbonate and nano-silica are selected for explosion suppression experiments. According to the gas explosion theory, the smaller the particle size of the powder, the better the explosion suppression effect. Silicon oxide’s small size effect, interface effect, photoelectric characteristics, etc., enhance the powder’s anti-explosion performance. In the experiment, by adding powder, it was verified that the safety of nano-powder control technology for gas explosion suppression was improved. This article combines powder control technology with nano-materials, making full use of the powder properties of nano-materials, and studying their improvement of the safety performance of gas explosion suppression.

Microporous Sulfur-Doped Carbon Atoms as Supports for Sintering-Resistant Platinum Nanocluster Catalysts

Carbon (C)-supported metal nanoclusters consisting of a few dozen atoms are highly attractive for a wide range of important catalytic processes with optimal reactivity and selectivity, yet they suffer from metal sintering and consequent deactivation because of the weak interaction between metals and inert C surface. Here, we report a microporous sulfur-doped carbon (S–C) as a support for sintering-resistant metal nanoclusters based on the strong interaction between metal and doped sulfur (S) atoms. The S–C support is prepared by carbonization of microporous conjugated poly(3,3′-bithiophene), which has a robust three-dimensional cross-linked network structure. The structural features of the conjugated polymer-derived S–C support, including high S contents of up to ∼26.9 wt % and large specific surface areas of 708–1019 m2 g–1, make it capable of anchoring ∼1 nm platinum (Pt) clusters even with a high Pt loading of 20 wt %. Remarkably, the S–C-supported Pt nanocluster catalysts can tolerate high-temperature treatments up to 700 °C in a reductive atmosphere or harsh hydrothermal treatments (alkaline water, 2 M bar of H2, and 200 °C for 12 h). Moreover, the S–C-supported Pt nanocluster catalysts exhibit a much enhanced catalytic performance for formic acid oxidation compared to the commercial Pt/C catalyst owing to the small-size effects.

Insights into the interaction between PANI and Au NPs of magnetic core‐shell Fe3O4/PANI/Au catalysts with remarkable catalytic performance in 4‐NP reduction

AbstractMagnetic Fe3O4/PANI core‐shell composites were prepared as the support of gold catalysts. The Fe3O4 magnetic core was prepared by solvothermal reaction and coated with polyaniline (PANI) shell via in situ aniline polymerization on Fe3O4 surface. Au nanoparticles were loaded on Fe3O4/PANI composites through gold sol adsorption and in situ reduction method to prepare Fe3O4/PANI/Au(Sol) and Fe3O4/PANI/Au(In Situ) catalysts, respectively. We found that the initial activities of Fe3O4/PANI/Au(Sol) were higher than that of Fe3O4/PANI/Au(In Situ) due to the small size effect of Au in catalysts. Although the size of Au in Fe3O4/PANI/Au(In Situ) was bigger than that in Fe3O4/PANI/Au(Sol), it should be noted that both of Fe3O4/PANI/Au(Sol) and Fe3O4/PANI/Au(In Situ) possessed good catalytic recycling stability. The conversion of 4‐NP was still above 97% and 99% after 15 cycles for Fe3O4/PANI/Au(Sol) and Fe3O4/PANI/Au(In Situ), respectively. The good catalytic stability for Fe3O4/PANI/Au(In Situ) could be attributed to the stronger interaction between PANI and Au NPs. We believe that our work provides an effective strategy for the preparation of long‐life catalysts and the investigations can be used to design other conductive polymers supported noble metal catalysts.

Health effects of psychological interventions for worry and rumination: A meta-analysis.

Evidence suggests that perseverative cognition (PC), the cognitive representation of past stressful events (rumination) or feared future events (worry), mediates the relationship between stress and physical disease. However, the experimental evidence testing methods to influence PC and the subsequent relationship with health outcomes has not been synthesized. Therefore, the current review addressed these gaps. Studies randomly assigning participants to treatment and control groups, measuring PC and a physical and/or behavioral health outcome after exposure to a nonpharmacological intervention, were included in a systematic review. Key terms were searched in Medline, PsycINFO and CINAHL databases. Of the screened studies (k = 10,703), 36 met the eligibility criteria. Random-effects meta-analyses revealed the interventions, relative to comparison groups, on average produced medium-sized effects on rumination (g = -.58), small-to-medium sized effects on worry (g = -.41) and health behaviors (g = .31), and small-sized effects on physical health outcomes (g = .23). Effect sizes for PC were negatively associated with effect sizes for health behaviors. (following outlier removal). Effect sizes for PC were significantly larger when interventions were delivered by health care professionals than when delivered via all other methods. No specific intervention type (when directly compared against other types) was associated with larger effect sizes for PC. Psychological interventions can influence PC. Medium-sized (negative) effect sizes for PC correspond with small (but positive) health behavior effect sizes. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

A-75 Effects of Rivastigmine on Neurocognitive Deficits in Patients with Parkinson’s Disease

Abstract Objective Cognitive impairments are commonly seen in Parkinson’s disease (PD). However, identification and tracking of cognitive deficits are not always part of treatment plans. Cholinergic treatment with rivastigmine has demonstrated beneficial effects on cognition and gait stability in PD-dementia, but less evidence exists in PD-mild cognitive impairment. We investigated the cognitive effects of rivastigmine treatment in a 3-month open-label pilot study. Method 31 participants with PD and mild–moderate cognitive impairment (24 male; mean age = 71.7; mean years-of-education = 17.2; mean Montreal Cognitive Assessment (MoCA) score = 21.7) completed pre-testing in a single-site, non-randomized study at the University of Maryland Parkinson’s Disease and Movement Disorders Center. A subset of 12 patients returned for follow-up after 12 weeks of rivastigmine treatment. A physical examination, the MoCA, and a computerized cognitive measure (NeuroTrax) were completed at each session. It was hypothesized that rivastigmine would benefit cognition, particularly executive functioning. Results Rivastigmine benefited global cognitive functioning as measured by both the MoCA (t(10) = −2.5, p < 0.05; M(Time 1) = 22.6(2.2), M(Time 2) = 24.9(3.9)) and NeuroTrax (t(11) = −3.0, p < 0.05; M(Time 1) = 88.7(13.6), M(Time 2) = 95.5(11.6)), though no domain-specific changes were evident. Relationships among the two measures were also examined. Moderate correlations were found between MoCA total scores and NeuroTrax measures including Global Cognitive Scale (r = 0.40, p < 0.05), Visuospatial Functioning (r = 0.39, p < 0.05), Executive Functioning (r = 0.50, p < 0.005), and Motor Response (speed/planning; r = 0.51, p < 0.005). Conclusions Although small sample size and practice effects must be considered, results suggest potential global cognitive benefit of rivastigmine for patients with PD experiencing mild–moderate cognitive deficits. Treatment planning for all PD patients should include periodic cognitive screenings and consideration of treatment options.

Discomfort, pain and fatigue levels of 160 cyclists after a kinematic bike-fitting method: an experimental study

ObjectiveTo analyse rider’s subjective responses after a standardised bicycle ergonomic adjustment method.MethodsExperimental study of 160 healthy, amateur mountain bikers analysed previously and 30 days after a bike-fitting session. The main...

Upholding trust in therapeutic trials and evidence-based medicine: need for full disclosure of data, crowdsourcing data analysis and independent review?

An active 74-year-old woman with hypertension and a family history of hypercholesterolaemia was referred for evaluation of chest pain and underwent coronary angiography. Low-density lipoprotein (LDL) cholesterol was 270 mg/dL....

Elucidation of the thermophysical mechanism of hexagonal boron nitride as nanofluids additives

This study systematically investigated the physicochemical characteristics of hexagonal boron nitride (h-BN) nanoparticles dispersed in polyalphaolefin 6 (PAO6) from a molecular level to explore the thermal stability of nano-lubricants. The nanoparticles were characterized via transmission electron microscopy (TEM), field-emission scanning electron microscopy (FE-SEM), fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and energy-dispersive spectrometry (EDS) to analyze the chemical bonds, element distribution, and impurity. We not only theoretically reveal the rheological behavior of nano-lubricants but also propose precise models to predict the viscosity. Moreover, this study comprehensively analyzed the thermal stability of nano-lubricants under different gas environments through thermogravimetric analysis and revealed that the nanofluid thermal stability was improved owing to the small-size effect. The results show that the thermal conductivity of the nano-lubricants was significantly higher than that of PAO6. Finally, the mechanism of thermal property enhancement by the h-BN nanoparticles is revealed.

Recent Large-Cap Stock Outperformance and Its Impact on US Equities

Although a significant amount of literature has been written on the small-size effect, the recent outperformance of large, mega-cap stocks in the United States has been noticeable. The impact of this outperformance on passive, smart beta, and active investing is likely underestimated, however. This relationship has made indexes less diversified by impacting the effective number of stocks measure within these indexes. The portfolio construction of factor (smart beta) portfolios has become more significant, as large-cap stocks within factors have outperformed small-cap stocks within the same factor. The outperformance of large-cap stocks has also impacted active investing. Active investors typically have a small or equal-weight tilt relative to the benchmark, therefore the recent outperformance of large-cap stocks has provided a headwind to active investment. The dominance of large caps is unlikely to continue, but their performance and impact is crucial to acknowledge and understand. <b>TOPICS:</b>Security analysis and valuation, analysis of individual factors/risk premia, performance measurement <b>Key Findings</b> ▪ US large-cap stocks have outperformed since 1984. ▪ The impact of this outperformance is broader than many investors realize. ▪ This outperformance has impacted passive, smart beta, and active investing.

Wildlife conservation in a fragmented landscape: the Eurasian red squirrel on the Isle of Wight

Island populations may have a higher extinction risk due to reduced genetic diversity and need to be managed effectively in order to reduce the risk of biodiversity loss. The Eurasian red squirrels (Sciurus vulgaris) in the south of England only survive on three islands (the Isle of Wight, Brownsea and Furzey islands), with the Isle of Wight harbouring the largest population in the region. Fourteen microsatellites were used to determine the genetic structure of red squirrel populations on the Isle of Wight, as well as their relatedness to other populations of the species. Our results demonstrated that squirrels on these islands were less genetically diverse than those in Continental mainland populations, as would be expected. It also confirmed previous results from mitochondrial DNA which indicated that the squirrels on the Isle of Wight were relatively closely related to Brownsea island squirrels in the south of England. Importantly, our findings showed that genetic mixing between squirrels in the east and west of the Isle of Wight was very limited. Given the potential deleterious effects of small population size on genetic health, landscape management to encourage dispersal of squirrels between these populations should be a priority.

Double mode model of size-dependent chaotic vibrations of nanoplates based on the nonlocal elasticity theory

In this paper vibrations of the isotropic micro/nanoplates subjected to transverse and in-plane excitation are investigated. The governing equations of the problem are based on the von Kármán plate theory and Kirchhoff–Love hypothesis. The small-size effect is taken into account due to the nonlocal elasticity theory. The formulation of the problem is mixed and employs the Airy stress function. The two-mode approximation of the deflection and application of the Bubnov–Galerkin method reduces the governing system of equations to the system of ordinary differential equations. Varying the load parameters and the nonlocal parameter, the bifurcation analysis is performed. The bifurcations diagrams, the maximum Lyapunov exponents, phase portraits as well as Poincare maps are constructed based on the numerical simulations. It is shown that for some excitation conditions the chaotic motion may occur in the system. Also, the small-scale effects on the character of vibrating regimes are illustrated and discussed.