Graphene Nanoparticles Research Articles

Development of Tailored Graphene Nanoparticles: Preparation, Sorting and Structure Assessment by Complementary Techniques.

We present a thorough structural characterization of Graphene Nano Particles (GNPs) prepared by means of physical procedures, i.e., ball milling and ultra-sonication of high-purity synthetic graphite. UV-vis absorption/extinction spectroscopy, Dynamic Light Scattering, Transmission Electron Microscopy, IR and Raman spectroscopies were performed. Particles with small size were obtained, with an average lateral size <L> = 70−120 nm, formed by few <N> = 1−10 stacked layers, and with a small number of carboxylic groups on the edges. GNPs relatively more functionalized were separated by centrifugation, which formed stable water dispersions without the need for any surfactant. A critical reading and unified interpretation of a wide set of spectroscopic data was provided, which demonstrated the potential of Specular Reflectance Infrared Spectroscopy for the diagnosis and quantification of chemical functionalization of GNPs. Raman parameters commonly adopted for the characterization of graphitic materials do not always follow a monotonic trend, e.g., with the particle size and shape, thus unveiling some limitations of the available spectroscopic metrics. This issue was overcome thanks to a comparative spectra analysis, including spectra deconvolution by means of curve fitting procedures, experiments on reference materials and the exploitation of complementary characterization techniques.

Effect of multiscale hybrid fillers on the electrical conductivity of silicone-based conductive textiles

Synergistic combinations of the microsized copper filler and nanosized conductive fillers were applied to silicone-based conductive textile for improvement of electrical conductivity. Conductive composite textiles (CCTs) were manufactured through screen-printing and subsequent thermal curing of polydimethylsiloxane containing hybrid fillers. We examined changes in the electrical properties of the CCTs according to the type and concentration of nanosized fillers including silver nanowires, graphene nanoparticles, and carbon nanotubes. It was found that upon the addition of 0.5 wt% graphene, the electrical resistance was improved by 27% compared to that of the original CCT owing to the formation of an excellent conductive network.

Blocking tau transmission by biomimetic graphene nanoparticles.

Tauopathies are a class of neurodegenerative diseases resulting in cognitive dysfunction, executive dysfunction, and motor disturbance. The primary pathological feature of tauopathies is the presence of neurofibrillary tangles in the brain composed of tau protein aggregates. Moreover, tau aggregates can spread from neuron to neuron and lead to the propagation of tau pathology. Although numerous small molecules are known to inhibit tau aggregation and block tau cell-to-cell transmission, it is still challenging to use them for therapeutic applications due to poor specificity and low blood-brain barrier (BBB) penetration. Graphene nanoparticles were previously demonstrated to penetrate the BBB and are amenable to functionalization for targeted delivery. Moreover, these nanoscale biomimetic particles can self-assemble or assemble with various biomolecules including proteins. In this paper, we show that graphene quantum dots (GQDs), as graphene nanoparticles, block the seeding activity of tau fibrils by inhibiting the fibrillization of monomeric tau and triggering the disaggregation of tau filaments. This behavior is attributed to electrostatic and π-π stacking interactions of GQDs with tau. Overall, our studies indicate that GQDs with biomimetic properties can efficiently inhibit and disassemble pathological tau aggregates, and thus block tau transmission, which supports their future developments as a potential treatment for tauopathies.

Istraživanja mehaničkih i prigušujućih svojstava stiren-butadien kaučuka sa grafenom i čađi

An experimental and numerical study on the mechanical and damping properties of styrene-butadiene rubber (SBR) composites with graphene nanoparticles (GNP) and carbon black (CB) is presented in this paper. The composites were tested for mechanical properties such as hardness and tensile strength. It is observed that the composites with GNP &amp; CB fillers have higher stiffness and percentage elongation for failure. A scale model of the chassis was subjected to forced vibration to find the damping properties of each of the prepared composites. The experimental results were used to create a numerical model in ANSYS software using Yeoh's hyper-elastic model to generate a hyper-elastic material to simulate the composite property and to perform harmonic response analysis in ANSYS. The results from experiments and theoretical findings exhibited good agreement.

The gut microbiome meets nanomaterials: exposure and interplay with graphene nanoparticles.

Graphene-based nanoparticles are widely applied in many technology and science sectors, raising concerns about potential health risks. Emerging evidence suggests that graphene-based nanomaterials may interact with microorganisms, both pathogens and commensal bacteria, that dwell in the gut. This review aims to demonstrate the current state of knowledge on the interplay between graphene nanomaterials and the gut microbiome. In this study, we briefly overview nanomaterials, their usage and the characteristics of graphene-based nanoparticles. We present and discuss experimental data from in vitro studies, screening tests on small animals and rodent experiments related to exposure and the effects of graphene nanoparticles on gut microbiota. With this in mind, we highlight the reported crosstalk between graphene nanostructures, the gut microbial community and the host immune system in order to shed light on the perspective to bear on the biological interactions. The studies show that graphene-based material exposure is dosage and time-dependent, and different derivatives present various effects on host bacteria cells. Moreover, the route of graphene exposure might influence a shift in the gut microbiota composition, including the alteration of functions and diversity and abundance of specific phyla or genera. However, the mechanism of graphene-based nanomaterials' influence on gut microbiota is poorly understood. Accordingly, this review emphasises the importance of studies needed to establish the most desirable synthesis methods, types of derivatives, properties, and safety aspects mainly related to the routes of exposure and dosages of graphene-based nanomaterials.

Experimental investigation on pH and stability of distilled water ethylene glycol mixture with graphene nanoplatelets

An efficient heat transfer medium improves the overall efficiency of the equipment, and the main difficulty is with making well-dispersed nanoparticles in base fluids. The current research is focused to study the effect of different surfactants on nanoparticle dispersion and enhancement through property modifications. The stability and pH value of various surfactants with varying sonication duration were studied and compared with the graphene nanofluids. The graphene nanofluids were prepared by a two-step method by dispersing 0.1 wt% graphene nanoparticles in distilled water and ethylene glycol with a ratio of 70:30. The surfactants namely Cetyltrimethylammonium bromide (CTAB), Polyvinylpyrrolidone (PVP K-30), and Polysorbate 60 (Tween 60) of each 0.1 wt% were used for stabilizing the nanofluids. The duration of the sonication process was set as 60, 90, and 120 min respectively followed by the magnetic stirring for 60 min duration. The stability behavior of nanofluids was studied through visual inspection, UV spectrum, and zeta potential techniques, and the corresponding pH values were measured to correlate with the performance of the heat transfer equipment. The results showed that the dispersion of graphene nanofluids strongly depends on the type and amount of dispersant in the absolute value of zeta potential. Finally, the optimum conditions were found based on the enhanced stability, pH, and sonication time of graphene nanoplatelets in distilled water-ethylene glycol mixture with Polyvinylpyrrolidone (PVP K-30) as a surfactant for the battery thermal management systems (BTMS) in electric vehicles.

Folic Acid-Functionalized Albumin/Graphene Oxide Nanocomposite to Simultaneously Deliver Curcumin and 5-Fluorouracil into Human Colorectal Cancer Cells: An In Vitro Study.

Nowadays, due to various inherent properties, graphene-based nanoparticles are widely used in drug delivery research. On the other hand, folate receptors are highly expressed on the surface of human tumor cells. In this work, to enhance the 5-fluorouracil (5FU) and curcumin (Cur) effects on colon cancer, we constructed a folic acid- (FA-) modified codelivery carrier based on graphene nanoparticles (GO-Alb-Cur-FA-5FU). The HUVEC and HT-29 were selected for evaluating the antitumor effect of the prepared nanocarriers. The structure of nanocarriers was characterized by FTIR spectroscopy, X-ray diffraction analysis, TEM microscopy, and a DLS analyzer. The efficiency of the prepared carrier was evaluated by fluorescence microscopy using Annexin V and the PI kit. The cytotoxicity of the carrier's component individually and the efficacy of the drug carrier GO-Alb-Cur-FA-5FU were assessed by MTT. The results of the pharmacological tests indicated that the new nanoparticles cause increased apparent toxicity in HT-29 cells. The apoptosis rate of the HT-29 and HUVEC cells treated with IC50 values of GO-Alb-Cur-FA-5FU for 48 h was higher than the cells treated with IC50 values of 5FU and Cur individually, which indicated the greater inhibitory efficacy of GO-Alb-Cur-FA-5FU than free drugs. The designed GO-Alb-CUR-FA-5FU delivery system can be applied for targeting colon cancer cells and can be severe as a potential candidate for future drug development.

Effect of Graphene Oxide Nanoparticles on the Flexural Strength of all CeramicsAn In-vitro Study

Introduction: Desirable properties of monolithic ceramics like strength, stability at high temperatures, high stiffness has made it useful for biomedical, electronic, automotive, industrial, defence and space applications. The brittle nature and mechanical unreliability of monolithic ceramics limit their use. Aim: To evaluate, if there is an increase in flexural strength of all ceramics incorporated with graphene nanoparticles. Materials and Methods: This in-vitro study was conducted in the Department of Prosthodontics and Crown and Bridge, Sri Ramachandra Institute of Higher Education and Research, Chennai, Tamil Nadu, India, from February 2021 to April 2021, where 20 specimens of all ceramic dimensions of 20×5×3 (20 mm in length, 5 mm in width, 3 mm in thickness) according to American Dental Association (ADA) specification number 69, 1991 for flexural strength were grouped into group A (Control) with no Graphene Oxide (GO), group B with GO added. A universal testing machine with a cross head speed of 0.5 mm/ min and a span length of 15 mm was used to load the specimen in the centre. To compare the flexural strength of the two groups, the Mann Whitney U-test was used. Normality was the data assessed using Shapiro-Wilk and Kolmogorov-Smirnov test. Results: The results show that there was a significant difference (p=0.001) in the mean flexural strength between the groups. Group B had the highest mean flexural strength of 562.61 MPa, while Group A had the lowest of 458.61 MPa. Conclusion: The results concluded that, all ceramics incorporated with graphene nanoparticles showed superior flexural strength.

Green synthesis of silver nanoparticles, graphene, and silver-graphene nanocomposite using Melissa officinalis ethanolic extract: Anticancer effect on MCF-7 cell line.

Nanotechnology has helped a lot in diagnosing and treating multiple illnesses, specifically cancer, and increasing the development of targeted drug delivery methods. Nanocomposites are materials with at least one component smaller than 100 nm. Therefore, this study aims to assess the anticancer effects of silver-graphene nanocomposite on MCF-7. In this study, the rate of inhibition of cancer cell growth and production of reactive oxygen radicals, malondialdehyde, and glutathione stores in MCF7 cells were investigated. Cancer cells were exposed to nano particles for 48 hr. Silver nanoparticles and graphene both reduced the growth rate of MCF-7. Subsequently, by treating the cells with silver-graphene nanocomposite, the rate of inhibition of cell growth at the highest concentration was 84.60%. Nanoparticles also inhibited the growth of cancer cells through the oxidative stress pathway by increasing the amount of intracellular ROS, followed by increasing malondialdehyde and decreasing glutathione stores, so that at the highest combined concentration of nanoparticles, the amounts of LPO and ROS increased up to 70% and 74 %, and glutathione reserves decreased by 16%. Treatment of MCF-7 cells with silver or graphene nanoparticles and combination treatment with these two substances against cisplatin have sound effects, and by affecting oxidative stress factors, such as increased ROS and subsequent increase in lipid membrane damage, inhibit cell growth and proliferation. According to the mathematical model, silver graphene nanocomposite> silver nanoparticles> graphene has the best effect in inhibiting the growth of cancer cells, respectively.

Recent advances in thermal conductivity and thermal applications of graphene and its derivatives nanofluids

• Seven factors should be considered in the study of graphene thermal conductivity. • Significant research gap exists in factors of graphene thermal conductivity. • Positive and negative effects both exist when graphene nanofluids are applied. • Economics and environment must be considered in application of graphene nanofluids. • More thermal studies on the graphene nanofluids are warranted. With the rapid development of industrial technology, more and more high-power-consumption devices are utilized, resulting in significant challenges to the durability, reliability, and efficiency of devices, facilities, and systems. Developing efficient thermal management systems for high power consumption application scenarios has evolved as a prominent research topic. Graphene nanomaterials are suitable candidates for nanofluids because of their excellent physical properties and high thermal conductivity. Although there are many studies on graphene nanofluids, there is no comprehensive review article about the influencing factors of thermal conductivity and the applications of graphene nanofluids, especially in economic and environmental analysis. This paper reviews the influencing factors of the graphene nanofluid thermal conductivity, including temperature, nanoparticle size and shape, base fluid, concentration, pH, surface modification, and ultrasonication. Moreover, the applications of graphene nanofluids in heat pipes, heat exchangers, solar collectors, and pool boiling devices are presented. Their applications are also discussed in terms of economics and the environment. In addition, the findings of thermal research on graphene nanofluids are summarized, and available opportunities and challenges are demonstrated. It is concluded that graphene nanomaterials significantly improve the thermal conductivity of the base fluid by 1.2% to 83.4%. Graphene nanofluids significantly improved the performance of thermal management devices. This comprehensive review is necessary to promote the research and effective application of graphene nanofluids in the context of sustainable development and carbon neutrality.

Nanoarchitected graphene/copper oxide nanoparticles/MoS2 ternary thin films as highly efficient electrodes for aqueous sodium-ion batteries.

Sodium-ion batteries (SIBs) operating in aqueous electrolyte are an emerging technology that promises to be safer, cheaper, more sustainable and more efficient than their lithium-based counterparts. One of the great challenges associated with this technology is the development of advanced materials with high specific capacity to be used as electrodes. Herein, we describe an ingenious strategy to prepare unprecedented tri-component nanoarchitected thin films with superior performance when applied as anodes in aqueous SIBs. Taking advantage of the broadness and versatility of the liquid-liquid interfacial route, three transparent nanocomposite films comprising graphene, molybdenum sulphide and copper oxide nanoparticles have been prepared. The samples were characterized using several techniques, and the results demonstrated that depending on the specific experimental strategy, different nanoarchitectures are achieved, resulting in different and improved properties. An astonishing capacity of 1377 mA h g-1 at 0.1 A g-1 and a degree of recovery of 100% were observed for the film in which the interactions among the components were optimized. This is among the highest capacity values reported in the literature and demonstrates the potential of these tri-component materials to be used as anodes in aqueous sodium-ion batteries.

A review: studying the effect of graphene nanoparticles on mechanical, physical and thermal properties of polylactic acid polymer.

Polylactic acid (PLA) is a linear aliphatic polyester thermoplastic made from renewable sources such as sugar beet and cornstarch. Methods of preparation of polylactic acid are biological and chemical. The advantages of polylactic acid are biocompatibility, easily processing, low energy loss, transparency, high strength, resistance to water and fat penetration and low consumption of carbon dioxide during production. However, polylactic acid has disadvantages such as hydrophobicity, fragility at room temperature, low thermal resistance, slow degradation rate, permeability to gases, lack of active groups and chemical neutrality. To overcome the limitations of PLA, such as low thermal stability and inability to absorb gases, nanoparticles such as graphene are added to improve its properties. Extensive research has been done on the introduction of graphene nanoparticles in PLA, and all of these studies have been studied. In this study, we intend to study a comprehensive study of the effect of graphene nanoparticles on the mechanical, thermal, structural and rheological properties of PLA/Gr nanocomposites and also the effect of UV rays on the mechanical properties of PLA/Gr nanocomposites.

Microwave synthesis of antimony oxide graphene nanoparticles - a new electrode material for supercapacitors.

For the first time, antimony oxide nanoparticles were produced using a microwave technique and evaluated as a supercapacitor electrode. The specific capacitance derived from the material's galvanostatic charge-discharge curve was 98 F g-1 in 1 M Li2SO4 electrolyte at 0.1 A g-1 current density. The charge storage mechanism visible in the CV curve is nearly rectangular and identical to the EDLC charge storage mechanism. Additionally, antimony species were chemically attached to graphene oxide using an antimony(iii) chloride precursor and subsequently microwave aided procedures were used to convert the antimony species to SbO-G nanocomposites. The results of energy-dispersive X-ray spectroscopy demonstrated the pure character of the produced material. In a three-electrode cell arrangement, the resulting composite was electrochemically characterized. The cyclic voltammogram results showed that among the pristine SbO, graphene, and SbO-G materials, SbO-G had a higher specific capacitance value of 37.58 F g-1, at a scan rate of 10 mV s-1. The material has also demonstrated good conductivity characteristics based on electrochemical impedance spectroscopy research. After 3500 galvanostatic charge-discharge cycles, the material had excellent cycling stability of ∼100%. All the remarkable capacitive properties demonstrated by this material indicate that it can be a viable choice in the field of energy storage devices.

Low-velocity impact behavior and mechanical characteristics of basalt/glass hybrid composites with graphene filler for enhancing aircraft nose tip

The growing need for eco-friendly, reliable, lightweight yet rigid materials for aircraft structures served as the inspiration for this work. The intention of this research is to examine the microdamage effects of a hybrid composite made of basalt/glass fiber infused with graphene, on the low energy drop weight impact test. Four main methods are used, which encompass the fabrication of composites, low-velocity impact testing, methods for evaluating impacted composites using ultrasound nondestructive testing, and a study of damage morphology through a scanning electron microscope. An E-glass fiber(400 GSM) combined with natural basalt fiber in an 8:2 ratio and infusing graphene nanoparticles is manufactured, to develop a more appealing hybrid composite for aviation industries. The samples of hybrid composite, each varying with 1 % and 2 % graphene weight ratio of fillers with the fibers are used. Eight outer layers made of glass fiber and two inner layers of basalt fiber composite are prepared using hand layup and compression molding methods. Different impact energy levels ranging from 5 J to 48 J are applied to study the propagation of the damage in the composite at low-impact velocities (1.5–3 m/s). The impact damage for glass/basalt with 2 wt% graphene was comparatively 24 % less than that of glass/basalt without infused graphene nanoparticles at the highest impact energy, thus proving addition of natural basalt and graphene filler improves the strength of the composites.

Experimental investigation on the influence of silanized graphene coatings on carbon fiber composites as toughening agents at low temperatures

Several applications of carbon fiber are being investigated, with the alteration of the carbon fiber surface using graphene based nanoparticles as the primary focus. But, in the present study, carbon fiber was surface modified with 3-aminopropyl trimethoxysilane functionalized graphene nanoparticles using the electrophoretic deposition (EPD) method, and the CFRP composite laminate was fabricated using the VARTM method. The matrix comprises diglycidyl ether of bisphenol A (DGEBA) and triethylenetetramine (TETA) hardener. To assess toughness behaviour, the modified CFRP samples were subjected to charpy impact tests at both room temperature (RT) and cryogenic temperature (CT). The impact strength of CFRP specimens was enhanced by 14.8% and 18.7% at RT and CT, respectively. FTIR analysis was conducted to confirm the presence of flexible silane bonding. SEM analysis was conducted to further examine the fracture surface. At CT, silane functions as a flexible coupler inside CFRP laminates, imparting toughness to CFRP laminates.

Marine Collagen-Based Antibacterial Film Reinforced with Graphene and Iron Oxide Nanoparticles.

It has become more widely available to use biopolymer-based films as alternatives to conventional plastic-based films due to their non-toxic properties, flexibility, and affordability. However, they are limited in application due to deficiencies in their properties. The marine collagen was the specimen for the present study. Thus, the main objective was to reinforce marine collagen-based films with 1.0% (w/w of the dry polymer weight) of iron oxide nanoparticles (IO-NPs), graphene oxide nanoparticles (GO-NPs), or a combination of both oxides (GO-NPs/IO-NPs) as antibacterial and antioxidant additives to overcome some of the limitations of the film. In this way, the nanoparticles were incorporated into the film-forming solution (2% w/v in acetic acid, 0.05 M) and processed by casting. Thereafter, the films were dried and analyzed for their physicochemical, mechanical, microstructural, and functional properties. The results show that the effective combination of GO-NPs/IO-NPs enhanced the physicochemical properties by increasing the water contact angle (WCA) of the films from 77.2 to 84.4° and their transparency (T) from 0.5 to 5.2. Furthermore, these nanoparticles added antioxidant and antibacterial value to the films, with free radical inhibition of up to 95.8% and 23.8 mm of bacteria growth inhibition (diameter). As a result, both types of nanoparticles are proposed as suitable additives to be incorporated into films and enhance their different properties.

Mechanochemical Synthesis of Polyanilines and Their Nanocomposites: A Critical Review.

The mechanochemical synthesis of polyanilines (PANIs), made by oxidative polymerization of anilines, is reviewed. First, previous knowledge of the polymerization reaction in solution is discussed to understand the effect of different parameters: oxidant/monomer ratio, added acid, oxidant, temperature and water content on the properties of the conducting polymers (molecular weight, degradation, doping/oxidation level, conductivity, and nanostructure). The work on mechanochemical polymerization (MCP) of anilines is analyzed in view of previous data in solution, and published data are critically reconsidered to clarify the interpretation of experimental results. A key factor is the production of acids during polymerization, which is often overlooked. The production of gaseous HCl during MCP of aniline hydrochloride is experimentally observed. Since some experiments involves the addition of small amounts of water, the kinetics and heat balance of the reaction with concentrated solutions were simulated. A simple experiment shows fast (&lt;2 min) heating of the reaction mixture to the boiling point of water and temperature increments are observed during MCP in a mortar. The form and sizes of PANI nanostructures made by MCP or solution are compared. The extensive work on the production of nanocomposites by MCP of anilines together with different nanomaterials (porous clays, graphene, carbon nanotubes, metal, and oxide nanoparticles) is also described.

ZnO interrelated graphene matrix-based sensors for quercetin

An electrochemical study of quercetin (QUR) was carried out voltammetrically using graphene (Gr) and zinc oxide nanoparticles (ZnO) modified carbon paste electrodes (CPE). The effect of phosphate buffer solution (0.2 M PBS) of various pH was tested and we found that pH 6.0 was optimum. The electrochemical analysis of QUR involves a redox-coupled reaction with one oxidation peak at 0.356 V and a reduction peak at 0.324 V with a peak strength of 1.05 μA and 0.413 μA, respectively. The peak current obtained at the modified electrode was higher than the bare CPE, indicating the electrocatalytic behavior of the modifier. Surface characterization of Gr-ZnO/CPE was evaluated using X-ray diffraction (XRD) studies, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and Energy dispersive X-ray spectroscope (EDS). Sweep rate investigation provided knowledge about reaction mechanisms involving transferring an equal number of electrons and protons. The electrochemical process was governed by adsorption. The limit of detection (LOD) was computed to be 18.0 nM. The developed electrode material was utilized to determine QUR in real samples, which exhibited excellent recovery, demonstrating the utility of the proposed electrode.

Investigation on Wear Analysis of Aluminium (Al) 7075 Alloy Reinforced with Titanium Carbide (TiC) and Graphene (Gr) Nanoparticles

In this study wear behavior of metal matrix nanocomposites covers a distinctive mixture of Al 7075 reinforced through Titanium Carbide (TiC) and Graphene in nanoform. Present work consists of Al7075 base metal is reinforced with nanopowder TiC (2.5 % wt.) and Graphene (0.25% wt.). The samples casted by ultrasonic stir casting technique and machining in accordance with ASTM standards, then tested for wear behavioral characteristics using pin on disc. This method was functional to determine the effect of three factors like sliding velocity, applied load and sliding distance for the above work by using the Taguchi method. By considering three factors, three levels, and the composition of nanoTiC (2.5%) by keeping a constant Graphene (0.25% wt.), the applied load variations in steps are 10 N, 20 N, and 30 N, the sliding velocity is 1.5m/sec, 2.5m/sec, and 3.5 m/sec, and the sliding distances 500m, 1000m, and 1500 m to study the wear behavior.

Insight into Darcy flow of ternary‐hybrid nanofluid on horizontal surfaces: Exploration of the effects of convective and unsteady acceleration

AbstractThe transport phenomenon of water conveying spherical carbon nanotubes, cylindrical graphene, and platelet aluminum oxide nanoparticles exhibits a linear relationship between the pressure gradient causing the dynamics of ternary‐hybrid nanofluid and the velocity. However, it is essential to note that little is known about the computation of roughness at the surface transition zone during the early stages of accretion. The Darcy flow of ternary‐hybrid nanofluid was investigated and reported in this paper with the intention to provide insight into the convective and unstable acceleration related to leading‐edge accretion. The governing equations roughly represented that the time‐dependent fluid flow were nondimensionalized using the Blasius‐Rayleigh Stokes variable, and the three‐stage Lobatto IIIa integration formula for a finite difference (MATLAB package bvp4c) was used to solve numerically. Based on the analysis of results, it is worth concluding that the velocity decreases significantly due to a growth in the leading‐edge accretion (γ) because the convective acceleration increases while the unsteady acceleration decreases for . As , convective acceleration increases while the unsteady acceleration decreases. As γ enlarges from 90° to 180°, both forms of the acceleration are decreasing properties, but unsteady deceleration is bound to manifest.