Browsing by Author "Dikici, Burak"

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Age Hardening Response of an Al/Tic Hot Pressed Multi-Layered Composite: Influence on Corrosion
(Sage Publications Ltd, 2012) Dikici, Burak
In this study, Al-Cu-based three-layered metal matrix composites reinforced with TiC particles were produced successfully by a conventional hot pressing method under argon (Ar) atmosphere. To evaluate the effect of heat treatment, the composites were treated for 24 h at 530 degrees C and then aged in an oil bath at 180 degrees C for various aging periods. The multi-layered composite was characterized by SEM, EDS, XRD, and the Vickers microhardness test. It was concluded that the peak hardness for the multi-layered composite was observed, when the aging period was extended up to approximately 12 h. The hardness of the middle layer increased from approximately 140 to 291 HV within 12 h. The corrosion resistance of the composites decreased with increasing aging time and some preferential corrosion attack was detected in the composite layers. In addition, it was found that the pitting susceptibility of unaged composites was also higher than that of all the aged specimens.
Al-5cu/B4cp Composites: the Combined Effect of Artificially Aging (T6) and Particle Volume Fractions on the Corrosion Behaviour
(Elsevier, 2020) Tozkoparan, Burak; Dikici, Burak; Topuz, Mehmet; Bedir, Fevzi; Gavgali, Mehmet
In this study, the Al-5Cu matrix composites reinforced with different boron carbide (B4C) particle volume fractions have been successfully produced by the hot-pressing method. Then, the artificially aging (T6) was applied to the composites for increasing their mechanical properties. The combined effect of the T6 heat treating and the B4C particle volume fraction on the corrosion behaviour of the composites were investigated by potentiodynamic scanning (PDS) technique under aerated and deaerated 3.5% NaCl marine environments. The effect of the T6 treating on the hardness and corrosion susceptibilities of the composites were also evaluated microstructurally to contribute to their industrial use and production processes. The microstructural characterization of the composites was carried out by using a scanning electron microscope (SEM) with an attached energy dispersive spectrum (EDS) and X-ray diffraction (XRD). It was found that the corrosion susceptibilities of the composite have been interestingly decreased with increasing the B4C particle volume fraction in the matrix while the T6 treatment enhances the pitting susceptibility of the composites. The reason of the behaviour has been discussed in details the text. (C) 2020 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.
An Anfis Model To Prediction of Corrosion Resistance of Coated Implant Materials
(Springer, 2017) Tuntas, Remzi; Dikici, Burak
In the present study, an adaptive neuro-fuzzy inference system (ANFIS) model has been used for predicting the corrosion resistance of AA6061-T4 alloy coated with micro-/nano-hydroxyapatite (HA) powders by sol-gel technique. The input parameters of the model consist of the HA powder size (micro-/nanoscale, 35 mu m/20 nm), coating thickness (30, 60 and 85 mu m) and potential values, while the output parameter is corrosion current density. The performance of proposed ANFIS model was tested on the potentiodynamic polarization scanning (PDS) curves by comparing experimental and the theoretical results of the coatings. The results showed that the generated PDS curves of the coatings are in definitely acceptable levels with obtained results in our experimental reference study. Then, the combined effect of arbitrary selected coating thickness and HA powder size on corrosion behaviour of the coatings was also predicted by trained ANFIS model without using any experimental data. And finally, the predicted results for the arbitrary selected coating thicknesses were compared by validation tests. The results showed that the ANFIS has potential to be used in industrial applications of biomedical implant materials coated with HA without performing any experiments after detailed systematic studies in the near future.
An Artificial Neural Network (Ann) Solution To the Prediction of Age-Hardening and Corrosion Behavior of an Al/Tic Functional Gradient Material (Fgm)
(Sage Publications Ltd, 2021) Dikici, Burak; Tuntas, Remzi
In this theoretical study, the prediction of the corrosion resistance and age-hardening behavior of an Al/TiC functional gradient material (FGM) has been investigated by using the artificial neural network (ANN). The input parameters have been selected as TiC volume fraction of the composite layers, aging periods of the composite, environmental conditions, and applied potential during the corrosion tests. Current and microhardness were used as the one output in the proposed network. Also, a new three-layered composite has been imaginarily designed to demonstrate the predictive capability and flexibilities of the ANN model as a case study. Artificially aging (T6) process and potentiodynamic scanning (PDS) tests were used for heat-treating and corrosion response of the FGS, respectively. The results showed that the generated PDS curves of the FGM and calculated corrosion parameters of the case study are quite near and in acceptable limits for similar composites obtained values in experimental studies. Besides, this study has been a great success in predicting peak-aging times and its corresponding hardness values more precisely.
A Comparative Study: the Combined Effect of the Cold Working and Age Hardening Processes on Pitting Behaviour of Al/Sic Metal Matrix Composites Under Saline Environment
(Sage Publications Ltd, 2016) Dikici, Burak; Tekmen, Cagri
The combined effect of cold working and age hardening treatment (T8) on the corrosion behaviour of Al-Si-Mg based metal matrix composite reinforced with silicon carbide particles has been investigated in 3.5wt% NaCl solution by potentiodynamic polarization technique. Composites containing 10 and 20 vol% silicon carbide particles were produced by compocasting technique and cold-worked at ratios of 4, 6, 10, 25 and 50% prior to ageing heat treatment conducted at 175 degrees C Corroded surfaces of the composites were observed by using scanning electron microscopy. A significant change in the corrosion behaviour of composites was observed when cold work ratio was increased from 4 to 50%. In addition, it has been found that the influence of cold working on corrosion behaviour is relatively higher compared to the effect of reinforcement content and age-hardening treatment.
Corrosion of Metallic Biomaterials
(Springer-verlag Berlin, 2015) Dikici, Burak; Esen, Ziya; Duygulu, Ozgur; Gungor, Serap
Metallic materials have been used as biomedical implants for various parts of the human body for many decades. The physiological environment (body fluid) is considered to be extremely corrosive to metallic surfaces; and corrosion is one of the major problems to the widespread use of the metals in the human body since the corrosion products can cause infections, local pain, swelling, and loosening of the implants. Recently, the most common corrosion-resistant metallic biomaterials are made of stainless steels and titanium and its alloys along with cobalt chromium molybdenum alloys. It is well known that protective surface films of the alloys play a key role in corrosion of the metallic implants. Key documents on the corrosion behavior of the metallic biomaterials in human body have been compiled under this chapter as a review.
Corrosion Performance and Microstructural Response of A380 Matrix Alloy Reinforced With Sol-Gel Tio2-Coated Sic Particles: a Perspective on Previous Studies
(Carl Hanser verlag, 2015) Dikici, Burak; Tekmen, Cagri; Yigit, Ozcan
In this study, the corrosion susceptibility of aluminium matrix composites reinforced with sol-gel TiO2-coated silicon carbide particles has been investigated. The corrosion of the composite, fabricated by means of a liquid metal infiltration technique, was established in chloride-containing alkaline environments using the potentiodynamic polarisation technique. Microstructural and interfacial characterisation of the composite was carried out by using an optical microscope, scanning electron microscope, energy dispersion spectroscopy and X-ray diffractometer. The corrosion performance and its effect on the composite microstructure are discussed in relation to previous observations.
Corrosion Susceptibilities of Al-cu/Tic Mmcs Fabricated by Conventional Hot Pressing
(Natl inst Science Communication, 2007) Gavgali, Mehmet; Dikici, Burak; Bedir, Fevzi
The effect of TiC particle volume fraction on the electrochemical behaviours of metal matrix composites (MMCs), which is Al-Cu based reinforced with TiCp has been investigated in both aerated and deaerated 1.0 N H2SO4 aqueous solutions. Composites reinforced with TiC particles at volume fractions of 20, 30 and 40% have been produced by conventional hot pressing method and then, artificially aged (T6). The corrosion susceptibilities of the composites have been analyzed by using the cyclic potentiodynamic polarization technique. The surface morphology of the composites has been determined by scanning electron microscopy (SEM). The results show that the corrosion susceptibilities of the composites increase with increased TiC particle content but decreases with T6 heat treatment pet-formed on the composites.
Description of the Corrosion Behaviors of Am50 and Am60 Magnesium Alloying Sheets Manufactured by Twin-Roll Strip Casting Method
(2011) Zubaroğlu, Emin; Dikici, Burak
Magnezyum alaşımlarının diğer metalik yapısal malzemelerin tümüne göre yoğunluğunun düşük ve spesifik mukavemetinin yüksek oluşu başta otomotiv, uçak ve uzay olmak üzere bir çok endüstri alanının yoğun ilgisini üzerine çekmektedir. Günümüzde, magnezyum esaslı sac levhaların üretim süreçleri ve mekanik özellikleri üzerine birçok çalışma yapılmış olmasına karşın bu malzemelerin korozyon davranışı üzerine yapılan çalışmalar halen devam etmektedir. Ayrıca, Mg ve alaşımlarının korozyon hızı uygulanacak ısıl işlemler ile de değişebilmektedir. Yeni alaşım bileşimleri geliştirmek ve farklı şekillendirme yöntemlerinin potansiyelini ortaya koymak amacıyla yoğurma alaşımları üzerinde çok kapsamlı araştırmalar sürmektedir. Bu çalışmada, çift merdaneli sürekli döküm yöntemi ile üretilmiş AM50 ve AM60 Mg alaşımlı levhaların korozyon davranışları üzerine homojenleştirme ısıl işleminin etkisi potansiyodinamik polarizasyon (PDS) ve elektrokimyasal impedans (EIS) teknikleri kullanılarak %3.5 NaCl çözeltisi içerisinde araştırılmıştır. Numunelerin korozyon öncesi ve sonrası mikroyapısal incelemeleri optik mikroskop ve taramalı elektron mikroskop (SEM) yardımı ile incelenmiştir
The Effect of Electroless Ni Coating of Sic Particles on the Corrosion Behavior of A356 Based Squeeze Cast Composite
(Assoc Mechanical Engineers Technicians Slovenia, 2011) Dikici, Burak; Tekmen, Cagri; Gavgali, Mehmet; Cocen, Umit
The corrosion behavior of electroless Ni coated SiC particle reinforced squeeze cast aluminum based composite was investigated by potentiodynamic scanning (PDS) and electrochemical impedance spectroscopy (EIS) techniques in aerated and deaerated chloride solutions. Microstructural and interfacial characterization of the composite was carried out by using an optical microscope, scanning electron microscope (SEM), energy dispersion spectroscopy (EDS) and X-ray diffractometer (XRD). It has been observed that electroless Ni coating of SiC particles is not an effective method to improve its corrosion resistance in structural applications containing halide solution. (C)2011 Journal of Mechanical Engineering. All rights reserved.
Effect of Hydroxyapatite/Sio2 Hybride Coatings on Surface Morphology and Corrosion Resistance of Rex-734 Alloy
(Elsevier Sci Ltd, 2016) Say, Yakup; Aksakal, Bunyamin; Dikici, Burak
REX-734 stainless steel alloy was coated with hydroxyapatite (HA)-silicon dioxide (SiO2) composite (hybride) coatings by using the sol-gel method. Surface morphologies, adhesion resistances and corrosion behaviors of the coatings were examined and the characterization of the coatings was performed by using XRD, SEM, and EDS. It was observed that porous and crack-free surface morphology enhanced adhesion strength of the coatings. Through the shear tests, it was found that the adhesion resistance was 25.14 MPa in HA coatings and 25.47 MPa in HA-SiO2 coatings. Corrosion analyses of the coatings were performed by using potentiodynamic polarization (PDS) tests. It was determined that corrosion dimples formed on the coating surface and the corrosion resistance in HA+SiO2 coatings increased with decreasing porosity; however, in the further steps of corrosion, it reached to the base material by causing a pitting effect on the coated surface. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved.
Effect of Hydroxyapatite:zirconia Volume Fraction Ratio on Mechanical and Corrosive Properties of Ti-Matrix Composite Scaffolds
(Elsevier, 2022) Topuz, Mehmet; Dikici, Burak; Gavgali, Mehmet; Yilmazer, Yasemin
Ti-based scaffolds reinforced with zirconia and hydroxyapatite were produced successfully by a hybrid method with an eco-friendliness and low cost to obtain low elastic modulus (E) with sufficient physical, electrochemical and biological properties. The effect of simultaneous modification of the volume fraction of hydroxyapatite (HA) and zirconia (ZrO2) on scaffolds was investigated in terms of mechanical, corrosive, and antibacterial properties. Scanning electron microscopy with attached electron dispersive spectroscopy and X-ray diffraction were used for the characterization of scaffolds. Compression and electrochemical tests were performed to determine mechanical properties with detailed fracture mechanism and in-vitro corrosion susceptibility to simulated body fluid at 37 degrees C, respectively. Antibacterial tests were carried out by comparing the inhibition areas of E.coli and S.aureus bacteria. It was observed that the mechanical strength of the scaffolds decreased with increasing HA:ZrO2 volume fraction ratio. The lowest E was achieved (6.61 GPa) in 6:4 HA:ZrO2 composite scaffolds. Corrosion current density (J(corr)) values were calculated to be 21, 337, and 504 mu A/cm(2) for unreinforced Ti, 3:2 and 6:4 HA:ZrO2 reinforced scaffolds, respectively. The inhibition capacity of the 6:4 reinforced composite scaffold was found to be more effective against S.aureus bacteria than other scaffolds.
The Effect of Sintering Time on Synthesis of in Situ Submicron Α-Al2o3 Particles by the Exothermic Reactions of Cuo Particles in Molten Pure Al
(Elsevier Science Sa, 2013) Dikici, Burak; Gavgali, Mehmet
In this study, in situ alpha-Al2O3 reinforcing particles have been successfully synthesised in an Al-Cu matrix alloy by means of the conventional Hot Pressing (HP) method. The effect of sintering time on the forming of the alpha-Al2O3 phase at 1000 degrees C was investigated using Differential Thermal Analysis (DTA), X-ray Diffraction (XRD) and a Scanning Electron Microscope (SEM). The sintered composites contained thermodynamically stable alpha-Al2O3 particles and theta-Al2Cu eutectic phases, which were embedded in the Al-Cu matrix. The in situ alpha-Al2O3 particles were generally spherical and their mean size was observed to be less than 0.5 mu m. The results showed that sintering time influences not only the reaction rate of copper and the formation of Al2O3. Also, an increase in the sintering time accelerates the formation of submicron in situ alpha-Al2O3 particles and decreases the quantity of theta-Al2Cu intermetallic phase in the liquid aluminium. Additionally, sintering of composite for 30 min at 1000 degrees C increased the hardness from 60 to 174 HV. (C) 2012 Elsevier B. V. All rights reserved.
Effects of the Heat Treatment on the Corrosi̇on Behavior of Az31, Az61 and Az91, Manufactured With Double Roll Strip Casting
(2013) Kalaycı, Fehmi; Dikici, Burak
1- Magnezyum (Mg) alaşımlarının diğer metalik yapısal malzemelerin tümüne göre yoğunluğunun düşük ve spesifik mukavemetinin yüksek oluşu başta otomotiv, uçak ve uzay olmak üzere bir çok endüstri alanının yoğun ilgisini üzerine çekmektedir. 2- Günümüzde, magnezyum esaslı sac levhaların üretim süreçleri ve mekanik özellikleri üzerine birçok çalışma yapılmış olmasına karşın bu malzemelerin korozyon davranışı üzerine yapılan çalışmalar halen devam etmektedir. Ayrıca Mg ve alaşımlarının korozyon hızı uygulanacak ısıl işlemler ile de değişebilmektedir. 3- Yeni alaşım bileşimleri geliştirmek ve farklı şekillendirme yöntemlerinin potansiyelini ortaya koymak amacıyla yoğurma alaşımları üzerinde çok kapsamlı araştırmalar sürmektedir. 4- Bu çalışmada, çift merdaneli sürekli döküm yöntemi ile üretilmiş AZ31, AZ61 ve AZ91 Mg alaşımlı levhaların korozyon davranışları üzerine homojenleştirme ısıl işleminin etkisi potansiyodinamik polarizasyon (PDS) ve elektrokimyasal impedans (EIS) teknikleri kullanılarak %3.5 NaCl çözeltisi içerisinde araştırılmıştır. Numunelerin korozyon öncesi ve sonrası mikroyapısal incelemeleri optik mikroskop ve taramalı elektron mikroskop (SEM) yardımı ile incelenmiştir.
Hidroksiapatit Kaplanmış Al2024'ün Simüle Edilmiş Vücut Sıvısında İn-vitro Korozyon Performansı: Karşılaştırmalı Bir Çalışma
(2023) Topuz, Mehmet; Dikici, Burak
Bu çalışmada, hidroksiapatit (HA) kaplamaların Al-Cu-Mg alaşımları (Al2024) üzerine uygulanabilirliği elektrokimyasal tekniklerle incelenmiştir. Kaplanan tabakaların yapısal karakterizasyonları SEM, EDS ve XRD test/analizleri ile incelenmiştir. Yüzey adezyon direnci ve elektrokimyasal bozunma davranışı, sırasıyla çizilme ve potansiyodinamik tarama (PDS) testleri ile test edilmiştir. Al2024 yüzeylerinde HA kaplamanın homojen bir yapıya sahip olduğu ancak kesit görüntülerinden bazı lokal bölgelerin yeterince HA ile kaplanamadığı görülmüştür. Ayrıca kaplama yüzeyleri, HA kaplamalara özgü mikro gözenekli morfolojiye sahip olduğu tespit edilmiştir. Kaplamanın çizilme testi sonuçlarından, kritik yük direncinin (Lc1), 12N’un biyomedikal uygulamalar için yeterli olacağı öngörülmüştür. Elektrokimyasal korozyon testleri, HA kaplamanın Al2024 alaşımının korozyon akımı yoğunluğunu (Icorr) ve korozyon oranını azalttığını ortaya çıkarmıştır (HA kaplı ve kaplanmamış Al2024 alaşımı için sırasıyla 0,885 ve 5,260 µA·cm-2). Ancak HA kaplama ile elde edilen düşük Icorr değerine rağmen hem Icorr hem de pasivasyon akım yoğunluğu (Ipass) değerlerinin (HA kaplama için 3,15 µA·cm-2, farklı titanyum türleri için 0.03 ila 0.08 µA·cm-2) olduğu gözlemlenmiş olup ticari titanyum alaşımlarına kıyasla yetersiz olduğu ortaya çıkarılmıştır.
An Investigation on the Aging Responses and Corrosion Behaviour of A356/Sic Composites by Neural Network: the Effect of Cold Working Ratio
(Sage Publications Ltd, 2016) Tuntas, Remzi; Dikici, Burak
In the present study, an artificial neural network model has been used for predicting the corrosion behaviour, aging and hardness responses of aluminium-based metal matrix composites reinforced with silicon carbide particle. Hyperbolic tangent sigmoid and linear activation functions are employed as the most appropriate activation function for hidden and output layers, respectively. The developed artificial neural network model is used to predict the corrosion current density, peak aging time and peak hardness of the composites. Feed forward back propagation neural network has been trained by Levenberg Marquardt algorithm. The regression correlation coefficients (R-2) between the predicted and the experimental values of the corrosion current densities are found as 0.99986, 0.99629 and 0.99671 for the training, testing and validation datasets, respectively. Also, some case studies have been predicted by artificial neural network model. Test results indicate that the proposed network can be used efficiently for the prediction of the polarization response, peak aging time and peak hardness of the composites for different SiC volume fractions and deformation ratio without using any experimental data.
Prediction of Corrosion Susceptibilities of Al-Based Metal Matrix Composites Reinforced With Sic Particles Using Artificial Neural Network
(Sage Publications Ltd, 2015) Tuntas, Remzi; Dikici, Burak
In this theoretical study, the prediction of the corrosion resistance of Al-Si-Mg-based metal matrix composites reinforced with SiC particles has been studied, using an artificial neural network. Four input vectors were used in the construction of the proposed network; namely, volume fraction of SiC reinforcement, aging time of the composites, environmental conditions, and potential. Current was used as the one output in the proposed network. Test results indicate that the proposed network can be used efficiently for the prediction of the corrosion resistance of Al-Si-Mg-based metal matrix composites reinforced with SiC particles, and the methodology is suitable for engineers to study the corrosion of metal matrix composites. In addition, a few forecasts regarding the polarization response for different SiC volume fractions and aging conditions have also been generated without using any experimental data.
Processing of Ti/(ha+zro2) Biocomposite and 50% Porous Hybrid Scaffolds With Low Young's Modulus by Powder Metallurgy: Comparing of Structural, Mechanical, and Corrosion Properties
(Elsevier, 2021) Topuz, Mehmet; Dikici, Burak; Gavgali, Mehmet; Kaseem, Mosab
Processing of titanium (Ti)-based implants with improved corrosion resistance and Young's modulus close to that of cortical bone are receiving considerable attention in orthopedic and dental applications. Therefore, Ti matrix, hydroxyapatite (HA) and hydroxyapatite-zirconia (HA+ZrO2) reinforced composites were successfully produced using powder metallurgy as both bulk and 50% in vol. porous scaffold in this study. Microstructure, mechanical and corrosion properties of the bulk and scaffold composites were investigated comparatively. Scanning electron microscopy with attached an energy dispersive spectroscopy (SEM-EDS) and XRD diffraction analysis was used for the characterization of samples. Mechanical properties were determined by using micro Vickers hardness and compressive tests. Besides, the corrosion behaviours of the samples were determined in simulated body fluid (SBF) at 37 degrees C by using potentiodynamic scanning (PDS) tests. Room-temperature compression tests revealed that the bulk samples had higher values of Young's modulus and yield strength in comparison to the scaffold samples where the lowest values of Young's modulus and yield strength of 3 GPa and 6.93 MPa, respectively were obtained in the case of the Ti/(HA+ZrO2) composite scaffold. Moreover, in-vitro corrosion tests in SBF showed that the Ti/(HA+ZrO2) composite scaffold had higher corrosion resistance than the scaffold reinforced with only the HA phase. The corrosion mechanism of the bulk and scaffold samples was also elucidated by taking the microstructural analysis and phase compositional of the samples into account.
Production of Annealed Cold-Sprayed 316l Stainless Steel Coatings for Biomedical Applications and Their In-Vitro Corrosion Response
(Maik Nauka/interperiodica/springer, 2018) Dikici, Burak; Topuz, Mehmet
316L powders were successfully deposited onto Al5052 aluminium substrates by cold spray method. Annealing was treated on the coated samples at 250-1000A degrees C temperatures under Ar atmosphere. The in vitro performances of the coatings have been compared with using electrochemical corrosion test technique in the simulated body fluid (SBF) at body temperature (37A degrees C). A scanning electron microscope (SEM-EDS) and X-ray diffraction (XRD) have been used for microstructural characterization and phases identifications of the coatings, respectively. The results were shown that there are high adhesions at particle and substrate interfaces and between the particles deposited as well. Also, the increasing annealing temperature increases corrosion resistance of the cold sprayed 316L stainless steel coatings. The corrosion susceptibility of the coating annealed at 1000A degrees C was similar that of standard 316L stainless steel implant material in Ringer's solution. The microstructural observations revealed that corrosion starts between the inter-splat powders and continues throughout the surface not in-depth.
Sustainable Walnut Shell-Filled Polylactic Acid-Hydroxyapatite Hybrid Coatings for Enhanced Corrosion Resistance and Bioactivity of Magnesium Biomaterials
(Wiley, 2025) Topuz, Mehmet; Topuz, Fatma Coskun; Dikici, Burak; Seifzadeh, Davod
Due to the high corrosion rate and limited biocompatibility of commonly used magnesium (Mg) and its alloys, current studies have focused on surface modification techniques. In this study, which is aimed at overcoming these obstacles in biomedical applications, hybrid coatings of PLA-HA-Walnut shell (Wshell) were successfully applied to Mg substrates. The presence of micropores on the surfaces of the hybrid coatings was detected using SEM surface morphology, and the elemental composition and structural characterization of the coatings were confirmed through analyses. With a higher Wshell fraction, the corrosion current density decreased significantly compared to uncoated Mg and PLA-coated Mg, increasing the electrochemical corrosion resistance of Mg. The adhesion strength between the coatings and the Mg substrates increased to grade 3B with Wshell-filled hybrid coatings. Moreover, the contact angle of PLA-coated Mg decreased as the Wshell fraction increased, indicating enhanced surface wettability. Wshell hybrid coatings exhibit fibrous morphology and the formation of Ca- and P-rich layers. These results, along with the filling of Wshell, suggest that PLA-HA-Wshell hybrid coatings could be a promising additive material for potential next-generation low-cost and sustainable biomedical coatings to enhance the corrosion resistance and bioactivity of Mg.