Physical Sciences and Mathematics Commons^™

Direct Electrochemistry And Glucose Biosensing Of Glucose Oxidase-Gold Nanoparticles Composite Synthesized By Enzyme Method, Fang He, Xiao-Li Qin, Ying-Chun Fu, Chao Chen, Qing-Ji Xie, Shou-Zhuo Yao

Journal of Electrochemistry

Glucose oxidase (GOx)-gold nanoparticles (AuNPs) composite was synthesized by the one-pot enzyme reaction in the mixture solution of NaAuCl₄, GOx and glucose, and a Nafion/GOx-AuNPs/glassy carbon electrode was fabricated by the cast-coating method to examine the direct electrochemistry of GOx and the biosensing performance on this electrode. Such a GOx-AuNPs composite showed good direct-electrochemistry activity and bioactivity of GOx, probably because the enzyme-mediated AuNPs are close to the redox active centers of GOx. This enzyme electrode exhibited a linear amperometric response to glucose concentration (0.54 mmol·L^-1) at -0.4 V (vs. SCE), and a detection limit of …

Synthesis Of Namnpo4 By Spraying Drying-High Temperature Sintering And Its Electrochemical Performance, Xiao-Chen Lin, Xiao-Biao Wu, Xu Hou, Yong Yang

Journal of Electrochemistry

As a cathode material for sodium ion batteries, NaMnPO₄/C nanocomposite is successfully synthesized by the combination of spraying drying and high temperature sintering methods. The crystal structure of the as-synthesized phosphate material is confirmed as the natrophilite NaMnPO₄, which possesses orthorhombic symmetry and Pmnb space group. It is shown that the precursors are hollow spherical particles and the obtained product consists of micro-scaled secondary particles, which are composed of NaMnPO₄ nanocrystallites (tens of nanometres) and amorphous carbon networks. The ionic and electronic conductivities of NaMnPO₄ are both effectively enhanced with the help of this …

Comparison In Factors Affecting Electrochemical Properties Of Thermal-Reduced Graphene Oxide For Supercapacitors, Peng Xiao, Da-Hui Wang, Jun-Wei Lang

Journal of Electrochemistry

In this paper, thermal-reduced graphene oxide (T-RGO) materials are synthesized by modified Hummer’s method, followed by thermal reduction under argon atmosphere at different temperatures. Electrochemical investigations show that, for T-RGO electrodes, good electrical conductivity is necessary and the surface functional groups play more significant role than the specific surface area in determining the electrochemical capacitance. The T-RGO obtained at 900 °C (T-RGO900) with a relatively high Brunauer-Emmett-Teller (BET) surface area (314 m²·g^-1) and a high electrical conductivity (2421 S·m^-1) shows a low specific capacitance of 56 F·g^-1. In comparison, the T-RGO obtained …

One-Step Synthesis Of Pani/Nihcf Hybrid Film Using Unipolar Pulse Electrodeposition And Its Electrocatalytic Reduction Performance For H2O2 Detection, Sen-Liang Liao, Xiu-Min Li, Xiao-Gang Hao, Yan-Hong Wang, Chun-Feng Xue, Yong-Hong Wang

Journal of Electrochemistry

Organic–inorganic hybrid films composed of polyaniline/nickel hexacyanoferrate (PANI/NiHCF) were fabricated on platinum substrates using unipolar pulse one-step electrodeposition. The deposition mechanism of hybrid film was proposed: Due to high potential of unipolar pulse electrodeposition, which avoided the reduction of Fe(CN)₆^3-, the films with high electrocatalytic property and “insoluble” form of NiHCF were achieved. The morphology and composition of PANI/NiHCF hybrid film were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and Fourier transform infrared spectroscopy (FT-IR). The effect of pulse potential on the electrochemical performance of hybrid film was investigated in detail. Results showed that …

Platinum Hollow Nanospheres With Different Sizes: Controllable Synthesis And Electrocatalytic Oxidation Toward Methanol, Xuan Lin, Mei-Qin Cheng, Zhong-Jin Shang, Ting Xiong, Xian-Tu Zhang, Wei Tian, Jian-Yun Lin, Qi-Ling Zhong, Bin Ren

Journal of Electrochemistry

The selenium (Se) templates and hollow platinum (Pthollow) nanospheres with different sizes were controllably synthesized by adjusting the concentration of sodium dodecyl sulphonate (SDSN) (CSDSN, μmol·L-1) which was used as a surfactant. Accordingly, the Pthollow nanospheres modified glassy carbon (GC) electrode (Pthollow/GC) was prepared. The morphology and composition of Pthollow nanospheres were characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM), energy dispersive X-ray spectroscopy (EDX), high resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED) and X-ray diffraction (XRD) techniques. The electrocatalytic activities of Pthollow/GC and electrodeposited Pt nanoparticles modified glassy carbon electrode (Ptnano/GC) toward methanol oxidation …

Production And Applications Of Formaldehyde-Free Phenolic Resins Using 5-Hydroxymethylfurfural Derived From Glucose In-Situ, Yongsheng Zhang

Electronic Thesis and Dissertation Repository

The phenol-formaldehyde (PF) resin manufacturing industry is facing a growing challenge with respect to concerns over human health, due to the use of carcinogenic formaldehyde and sustainability due to the use of petroleum-based phenol in PF resin manufacture. Glucose and its derivative, 5-hydroxymethylfurfural (5-HMF), have proven to be potential substitutes for formaldehyde in the synthesis of phenolic novolac resins.

This thesis investigated a number of glucose and 5-HMF resin systems including the curing of phenol-glucose novolac resin (PG) with a bis-phenol-A type epoxy. The curing process was modeled according to the Sestak-Berggren equation (S, B) using Málek methods. This was …

Poly(Ester Amide) And Poly(Ethyl Glyoxylate) Nanoparticles For Controlled Drug Release, Amira Mohamed Moustafa

Electronic Thesis and Dissertation Repository

The objective of this research was to develop polymeric nanoparticles (NPs) having improved drug release properties for drug delivery. Poly(ester amide)s (PEAs) are promising biodegradable polymers. PEA NPs were prepared via emulsification-evaporation and salting-out methods and optimized through by varying different processing parameters. Polymer-model drug conjugates based on PEAs containing L-aspartic acid and rhodamine B were synthesized and used for NP preparation. Release behavior was studied and compared to a control system with physically encapsulated rhodamine B. It was shown that the release of rhodamine B from the covalent system did not show the burst effect and exhibited a slower …

Scale-Up Methodology For Bench-Scale Slurry Photocatalytic Reactors Using Combined Irradiation And Kinetic Modelling, Patricio J. Valades Pelayo

Electronic Thesis and Dissertation Repository

The present study focuses on developing a predictive methodology to scale-up a slurry annular photoreactor using a TiO₂ Degussa P25 from the bench-scale to a pilot-plant scale. The bench-scale photoreactor is a Photo-CREC-Water II, a 2.65 L internally-irradiated slurry annular photocatalytic reactor. The pilot-plant scale photoreactor is a Photo-CREC Water Solar Simulator, a 9.8 L pilot-plant photoreactor, externally irradiated by eight lamps.

The adopted methodology allows the independent validation of radiative and kinetic models avoiding cross-correlation issues. The proposed approach involves two Monte Carlo methods, to model the Radiative Transfer Equation (RTE) inside each photoreactor. With this end, a …

Water System For Developing Countries / Disaster Relief Made With Local Materials, Shumon Hasan

Chemistry & Biochemistry Undergraduate Honors Theses

The objective of this project was to design a water purification system that can be constructed from easily available materials, common to the particular country, and is capable of the complete water purification process.

The Development Of A Laminated Copolyester Electric Guitar, Addison S. Karnes

Electronic Theses and Dissertations

This thesis is an investigation of the fabrication and assembly methodologies employed in the development of a proof-of-principle prototype electric guitar composed of laminated copolyester. The objective of the project was to develop the processes and procedures to create an optimized physical and visual bond between layers to minimize vibratory dissipation, thus maximizing sustain. A high speed CNC router, abrasive waterjet, laser engraver-cutter, as well as various manual fabrication and assembly methods were investigated in the construction of the guitar prototypes. The lamination processes explored include low-temperature, heat-assisted pressure bonding, solvent and chemical welding, and contact adhesives. The project concluded …

Designing Magnetically Responsive Ultrafiltration Membranes, Robert William Dong

Graduate Theses and Dissertations

Ultrafiltration (UF) membranes developed out of a need for protein separation processes. Currently, they are used in a variety of industries ranging from food manufacturing to pharmaceuticals for two main purposes: concentration, separation, and buffer exchange. UF membrane processes in product streams undergo frequent use and like all membrane processes experience a gradual decline in performance due to fouling phenomena both irreversible and reversible. Ultimately, performance declines to a point where the UF membrane needs to be replaced. Frequent replacement of UF membranes is detrimental to major industries that require high product throughput using UF processes. Thus, it is important …

Diffusion And Adsorption Coefficients Of Aromatic Hydrocarbons In Gas Chromatography Capillary Columns, Gabriela Navarro Tovar

Electronic Thesis and Dissertation Repository

This study focuses on a mathematical description of aromatic species elution peaks from a gas chromatographic BPX5 capillary column. Using the chromatographic peaks, statistical moments are calculated for toluene, naphthalene, phenol and 2-naphthol. This thesis reports two modelling approaches involving laminar gas flow, distribution coefficients (K_s) and diffusion coefficients in the stationary phase (D_s).

Firstly, a model with equilibrium adsorption is considered to describe symmetric peaks for toluene and naphthalene. Moreover, a model with non-equilibrium adsorption is proposed to describe asymmetric peaks of phenol and 2-napthol. In addition to the K_s and D …

Electrochemical And Spectroscopic Studies Of Ethanol Oxidation On Nano-Cubic Pt Modified By Tin Adatoms, Lu Rao, Bin-Wei Zhang, Yan-Yan Li, Yan-Xia Jiang, Shi-Gang Sun

Journal of Electrochemistry

The nano-cubic Pt modified by tin (Sn) was synthesized and used to investigate the role of this adatom played in the ethanol oxidation. The onset potential of ethanol oxidation was significantly shifted negatively which can be forward about 300 mV when the coverage of Sn (θSn)was 0.9. The electrtochemical in situ FTIR result demonstrated that the amount of CO2 increased first, and then decreased with θSn increased, and reached the maximun when θSn was 0.38. Furthermore, the formation of acetic acid could be observed at very low potential (-0.05 V) after modifying Sn adatom, and the amount of acetic acid …

Boosting Electrocatalytic Activity Of Nitrogen-Doped Graphene/Carbon Nanotube Composite For Oxygen Reduction Reaction, Yu Zhang, Jin-Song Hu, Wen-Jie Jiang, Lin Guo, Zi-Dong Wei, Li-Jun Wan

Journal of Electrochemistry

Developing low-cost catalysts with high electrocatalytic activity for oxygen reduction reaction (ORR) has recently attracted much attention because the sluggish ORR currently limits the performance and commercialization of fuel cells and metal-air batteries as well. Nitrogen doped carbon materials have been considered as a promising candidate for the replacement of high-cost and scarce Pt-based catalysts although their electrocatalytic activity still needs to be much improved. In this work, an improved nitrogen-doped graphene/carbon nanotubes composite (N-rGO/CNT) was developed as an efficient ORR electrocatalyst. It was found that the ORR activity of N-rGO/CNT composite could be significantly enhanced by introducing iron in …

Influence Of Pt:Ru Ratio In Nanotubes Array Structures On The Electrocatalytic Activity Of Methanol Oxidation, Jin-Hua Yuan, Feng-Bin Wang, Xing-Hua Xia

Journal of Electrochemistry

Bimetallic PtRu nanotubes array electrodes (NTAEs) with varied Pt to Ru atomic ratios have been prepared by electrochemical codeposition in 3-aminopropyltri-methoxysilane modified porous anodic alumina (PAA) membranes. The structure and morphology of the catalysts were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Electrochemical results showed that the NTAEs with varied atomic ratios could be achieved by controlling the precursor concentration for deposition. The prepared nanoarrays composed of Pt or PtRu alloy promoted the mass-normalized activity toward the sluggish electrooxidation reaction of methanol due to the increased catalytic activity and real surface area, as well as the …

Effect Of Imidazole Ionic Liquids On The Electro-Oxidation Of P-Methoxy Toluene, Qiong Chen, Ying-Hong Zhu, Ying Zhu, Yan-Fang Li, Chun-An Ma

Journal of Electrochemistry

The interactions between four Imidazole ionic liquids (EMIMBF₄, BMIMBF₄, BMIMHSO₄, BMIMAc) and p-methoxy toluene were investigated by ultraviolet spectroscopy. The red shifts of absorption peak were obviously observed, and the fine structures of the spectroscopy were disappeared on the long wave district. p-MT producing stable excited state was benefit from the interaction with solvent molecules. The electro-oxidation behavious of p-MT were studied in the four ILs on platinum electrode by cyclic voltammetry (CV) and chronoamperometry (CP), and the diffusion coefficients (D) and activation energies (ED) were calculated. The results indicated that the electro-oxidation process …

Electro-Catalytic Properties Of Β-Pbo2/Sb-Sno2/Ti Electrode On Phenol Oxidation, Peng Li, Yue-Min Zhao, Li-Zhang Wang, Yan-Le Zhang, Zhao-Qing Lu

Journal of Electrochemistry

The combination technology of brush pyrolysis and electroplating was employed in the preparation of β-PbO₂/Sb-SnO₂/Ti electrode. X-ray Diffraction (XRD) and Scanning Electron Microscope (SEM) results showed that the Sb-SnO₂ as an interlayer would restrain the formation of lead fluoride and the crystallization degree on the electrode surface could be as high as 100%. The grain size was calculated by Scherrer formula to be 25.2 nm and the agglomeration of lead dioxide was effectively eliminated. The potential span of diffusion control phase, oxygen evolution potential, Tafel slope for the β-PbO₂/Sb-SnO₂/Ti electrode during …

Electrochemistry Of Glucose Oxidase Modified On Porin-Phospholipid Biomimic Membrane, Kun-Qi Wang, Zuo-Ming Zhang, Wei Xing, Chang-Peng Liu, Xing Zhou

Journal of Electrochemistry

Biomimic membrane with nano-channels, which is made up of porin MspA and 1,2-Dimyristoyl-sn-glycero-3-phosphocholine (DMPC) is constructed on glassy carbon substrate, and glucose oxidase (GOD) is modified on it. The direct electrochemical reaction and electrocatalytic behavior to oxygen and glucose of GOD on the GOD/MspA-DMPC/GC electreode are expounded by the cyclic voltammetric method. The study shows that GOD immobilized on porin MspA and DMPC biomimic membrane displays direct and surface-controlled electrochemical reaction nearby formal potential (E0′) of the flavoprotein active centre (FAD/FADH), and the electrochemical reaction contains two electrons and two protons exchange in 0.1 mmol?L^-1 phosphate buffer solution (PBS) …

Fabrication Of Pattern Of Graphene Oxide And Au Nanoparticles By Microcontanct Printing Technique, Wen-Hui Pang, Xiao-Jian Xiao, Meng-Wei Ye, Kai-Chao Deng, Jing Tang

Journal of Electrochemistry

Graphene oxide (GO) was prepared by modified Hummers method. Using the GO solution as "ink", Au nanoparticles (AuNPs) and GO were transferred to the surface of ITO substrate modified with (3-aminopropyl) triethoxysilane (APTES/ITO) in a sequence. The transferred AuNPs and GO could form a uniform and dense composite pattern which was characterized by FE-SEM and AFM. Moreover, using the APTES/ITO substrate surface potential as zero, the sequences of the surface potential were APTES>GO>Au.

Recent Progress In Heteroatoms Doped Carbon Materials As A Catalyst For Oxygen Reduction Reaction, Wei Ding, Xue Zhang, Li Li, Zi-Dong Wei

Journal of Electrochemistry

Developing catalytic materials for oxygen reduction reactions (ORR) with high performance and low cost has been one of the major challenges for large-scale applications of fuel cells. In this review, we summarize the recent progress in the heteroatoms doped carbon materials as a catalyst for the catalysis of ORR, with an emphasis on the universal origin of their catalytic mechanisms. The future prospects of the metal-free catalyst were to find precisely controlled doping methods, to explore the role of heteroatoms in the catalysis, and to generate more active catalysts with suitable nanostructure.

Fabrication And Characterization Of The Ni-Scsz Composite Anodes With A Cu-Lscm-Ceo2 Catalyst Layer In The Thin Film Sofc, Yao Lv, Bo Huang, Xi-Zhi Gu, Chun-Yi Hou, Yi-Xing Hu, Xiao-Yin Wang, Xin-Jian Zhu

Journal of Electrochemistry

Solid oxide fuel cell (SOFC) directly operating on hydrocarbon without external reforming has the potential of greatly speeding up the application of SOFCs for transportation. In this paper, a three-layer structure anode was fabricated by tape casting and screen printing method. The addition of Cu-LSCM-CeO₂ to the supported anode surface presented better performance running on H₂ and ethanol. The maximum power densities were 511 and 390 mW?cm^-2, respectively, running on H₂ and ethanol at 750 °C. No significant degradation was observed on the anode. Consequently, the Cu-LSCM-CeO₂ catalyst layer on the surface of the …

Preparation Of Pt/Dna-Mwcnts/Gc Electrode And Its Electrocatalytic Activity Toward H2O2 Reduction, Li-Li Fan, Li-Na Wu, Zhi-Yu Qu, Dan-Feng Liu, Jun-Ming Zhang, Si-Ming Fan, You-Jun Fan

Journal of Electrochemistry

The DNA-multi-walled carbon nanotubes (MWCNTs)/glassy carbon (GC) electrode was prepared by modifying the DNA functionalized MWCNTs composite on a GC electrode. A novel non-enzymatic H₂O₂ sensing electrode was fabricated by electrodepositing Pt nanoparticles on the DNA-MWCNTs/GC electrode. The modified electrodes were characterized by scanning electron microscope (SEM). The response properties of the sensing electrode to H₂O₂ were investigated by cyclic voltammetry and chronoamperometry. The results indicated that the sensing electrode exhibited a good linear relationship between response current and H₂O₂ concentration in the range of 0.04 ~ 18.07 mmol·L^-1 with …

Identifying Conditions To Optimize Lactic Acid Production From Food Waste, Raymond M. Redcorn

Open Access Theses

There is an increased demand for lactic acid for the production of biopolymers and to aid nutrient removal in wastewater treatment. Food waste offers a source of soluble sugars to produce lactic acid, which does not increase land demand, but digestion conditions have yet to be optimized when co-digested with primary sludge. Food waste was collected from cafeteria waste bins, homogenized and seeded with primary sludge. A Box Behnken Response surface design was used to optimize lactic acid production based on pH, temperature, loading rate, and retention time. Subsequent experiments verified and refined those conditions to optimize for both yield …

Impact Of Nanostructure On Polymer-Based Nonvolatile Memory Devices, Seung Hyun Sung

Open Access Theses

Memory functionality is essential for many high-end electronic applications (e.g. , smart phones, personal computers). Particularly, organic nonvolatile memory devices based on polymer ferroelectric materials are a promising approach toward the development of low-cost memory due to the ease of processing and flexibility associated with the device. Here, we will focus on a memory device with a two-component active layer and a diode structure. This ferroelectric diode (FeD) has a nanostructured active layer, composed of ferroelectric and semiconducting polymers, and it can provide easy access to high-performance polymer-based memory devices. In order to create these nanostructured active layers, we …

Dynamics Of Nanoparticles In Fluids And At Interfaces, Weikang Chen

Dissertations, Theses, and Capstone Projects

In this thesis, we use molecular dynamics simulation to study three basic behaviors or properties of nanoparticles: deposition during droplets evaporation, slip boundary condition and Brownian motion. These three problems address the need for an in-depth understanding of the dynamics of nanoparticles in fluids and at interfaces. In the first problem, evaporation of the droplets dispersed with particles, we investigated the distribution of evaporative flux, inner flow field, density and temperature. And we use these numerical experiments to check on our hydrodynamic theory of the "coffee ring" phenomenon. The simulations reveal the connection between the particle interactions and the deposit …

Study Of Polyaniline For Use In An Organic Field Effect Transistor, Thomas Martin Sprinkle

Chemistry & Biochemistry Theses & Dissertations

Polyaniline's emeraldine base form was synthesized via chemical polymerization in HCl acidic media utilizing ammonium persulfate as the oxidant. Synthesis was done at room temperature and -30 'C and characterized for differences by X-ray diffraction, thermogravimetric analysis, and differential scanning calorimetry. Methanol soxhlet extraction was done to increase number average molecular weight from 77,400 to 81,000 and decrease the poly dispersity index from 3.82 to 2.14. Films were cast using N, N'- Dimethylpropyleneurea and N-Methylpyrrolidone and showed poor mechanical properties upon acidic doping.

Cyclic voltammetry was done with HC1 as the acidic media and an ITO coated slide as the …

Electrochemically Active Biofilm Assisted Synthesis Of Ag@Ceo2 Nanocomposites For Antimicrobial Activity, Photocatalysis And Photoelectrodes, Mohammad Mansoob Khan Dr, S. A. Ansari, J. H. Lee, M. O. Ansari, J Lee, M. H. Cho

Dr. Mohammad Mansoob Khan

Ag@CeO2 nanocomposites were synthesized by a biogenic and green approach using electrochemically active biofilms (EABs) as a reducing tool. The as-synthesized Ag@CeO2 nanocomposites were characterized and used in antimicrobial, visible light photocatalytic and photoelectrode studies. The Ag@CeO2 nanocomposites showed effective and efficient bactericidal activities and survival test against Escherichia coli O157:H7, and Pseudomonas aeruginosa. The as-synthesized Ag@CeO2 nanocomposites also exhibited enhanced visible light photocatalytic degradation of 4-nitrophenol and methylene blue than pure CeO2. A photocatalytic investigation showed that the Ag@CeO2 nanocomposites possessed excellent visible light photocatalytic activities compared to pure CeO2. Electrochemical impedance spectroscopy and photocurrent measurements showed that the …

Electrocatalytic Oxidation Of Formate On Pd-Cu/C - Effect Of Dealloying Pretreatment, Jiang Kun, Wang Ye, Lin Tao, Cai Wen-Bin

Journal of Electrochemistry

Carbon supported highly dispersed Pd-Cu nanoalloy catalyst toward formate electrooxidation is prepared via one-pot synthesis by using ethylene glycol as the reducing agent and sodium citrate as the stabilizer. The as-prepared catalyst is structurally characterized by TEM and XRD. The Cu dealloyment is carried out through repetitive potential cycling of the Pd-Cu/C catalyst in an acidic solution. The dealloying effect on the performance of the Pd-Cu/C is investigated by using cyclic voltammetry and chronoamperometry, and the surface structural change of Pd-Cu/C is probed by in situ ATR-IR measurement. The results show that the as-prepared Pd-Cu/C processes a better long-term stability …

Synthesis Of Silver Nanoparticles Supported On Graphene Quantum Dots For Oxygen Reduction Reaction, Jian Ju, Wei Chen

Journal of Electrochemistry

Silver-based catalysts have been extensively investigated as the platinum substituted catalysts due to their high catalytic efficiency, low cost and long-term durability. In this study, the surfactant-free silver nanoparticles supported on graphene quantum dots were synthesized through a facile approach without addition of any other protecting ligands and reducing agents. The “surface-clean” silver nanoparticles had remarkable electrocatalytic performance towards oxygen reduction reaction (ORR) with the most efficient four-electron transfer process. Compared with commercial Pt/C catalyst, the hybrid nanoparticles showed comparable catalytic performance for ORR but much higher tolerance to methanol. Such silver nanoparticles supported on graphene quantum dots may have …

Electrochemical Fabrication Of Two-Dimensional Flower-Like Pt Nanostructures For Methanol Electrocatalytic Oxidation, Xia Wang, Jun Hu, Yong-Jun Li

Journal of Electrochemistry

Two-dimensional flower-like Pt nanostructures (2D FPNs) were fabricated on glassy carbon substrates by galvanostatical electrochemical technique. The electrolyte was the HAuCl₄ + HClO₄ aqueous solution without addition of any structure-directing organic reagent, which made as-prepared Pt nanostructures cleaner, exhibiting much higher reactivity. Scanning electron microscopic images revealed that 2D FPNs were spherical Pt nano-flowers constructed by the smallest building blocks, nano-leaves. The number density of spherical Pt nano-flowers can be tuned by controlling the electrodeposition time. High resolution transmission electron microscopic images indicated that each nano-leaf was formed by growing along Pt(111) direction. Electrocatalytic activities of as-prepared 2D …