- Department of Chemistry, Isfahan University of Chemistry, Isfahan 84156-83111, IRAN
- +989131123280
Ali A. Ensafi
Isfahan University of Technology, Chemistry, Faculty Member
- noneedit
- Prof. Ali A. Ensafi was graduated in Analytical Chemistry (Ph.D.) in 1991 from Shiraz University (Iran). Then, he joi... moreProf. Ali A. Ensafi was graduated in Analytical Chemistry (Ph.D.) in 1991 from Shiraz University (Iran). Then, he joined the Department of Chemistry at Isfahan University of Technology (Iran). He became a full professor in 2001 at Isfahan University of Technology. He joined as an Adjunct Professor in the Department of Chemistry & Biochemistry at University of Arkansas (Fayetteville, AR, USA) in July 2021.
As a visiting professor, he was at the University of Waterloo (Canada) during 1999-2000 and at the University of Arkansas (USA) during 2007-2008.
He is Head of Center of Excellence in Sensors & Green Chemistry of Ministry of Sciences, Research & Technology of Iran, and Head of Department of Chemistry in Isfahan University of Technology, Iran.
He has an H-index of 70 and has published more than 500 ISI papers, and he has more than 150 international and/or national oral presentations.
He has been awarded three international awards. He is co-authors of three books (Academic Press & Springer publishers), Editor of “Electrochemical Biosensors, Elsevier”, Associate Editor of Journal of the Iranian Chemical Society (Springer publisher), and Editorial Board of 15 International Scientific Journals.
Prof. Ensafi is the top 1% of Scientists in Chemistry in Thomson Routers, Essential Science Indicators.
His research program is developing sensors and biosensors (based electrochemical and spectroscopic methods) and new energy source based-nanomaterials for fuel cells, supercapacitors, and storage energy.edit
Flexible electrodes with high deformability and energy density are critical for electronic textiles. The key factor for achieving high-performance supercapacitors with superior power and energy density is the evaluation of materials that... more
Flexible electrodes with high deformability and energy density are critical for electronic textiles. The key factor for achieving high-performance supercapacitors with superior power and energy density is the evaluation of materials that exhibit exceptional capacitive performance. Herein, we have prepared Ni-Co nanoparticles at the surface of polyaniline-salphen (Ni-Co@PS). Then, followed by casting Ni-Co@PS on a conductive carbon cloth (CC) as a substrate through a facile in-situ polymerization strategy. The morphologies of Ni-Co@PS composite were characterized by different methods such as FE-SEM, XPS, XRD, BET, and electrochemical methods. This nanocomposite showed high tolerability and a large surface area with excellent behavior as a new nanomaterial for supercapacitor application. Thus, the optimum composite designed with a metal ratio (nickel–cobalt 3:1 w/w) satisfactorily possesses a specific capacitance of up to 549.994 C g−1 (1447.2 F g−1) under 0.5 A g−1 and long-term cycl...
In this study, we conducted direct synthesis of a dual metal–organic framework (Ni/Co-Hemin MOF) on phosphorous-doped reduced graphene oxide (PrGO) to serve as an active material in high-performance asymmetrical supercapacitors. The... more
In this study, we conducted direct synthesis of a dual metal–organic framework (Ni/Co-Hemin MOF) on phosphorous-doped reduced graphene oxide (PrGO) to serve as an active material in high-performance asymmetrical supercapacitors. The nanocomposite was utilized as an active material in supercapacitors, exhibiting a noteworthy specific capacitance of 963 C g−1 at 1.0 A g−1, along with a high rate capability of 68.3% upon increasing the current density by 20 times, and superior cycling stability. Our comprehensive characterization and control experiments indicated that the improved performance can be attributed to the combined effect of the dual MOF and the presence of phosphorous, influencing the battery-type supercapacitor behavior of GO. Additionally, we fabricated an asymmetric hybrid supercapacitor (AHSC) using Ni/Co-Hemin/PrGO/Nickel foam (NF) and activated carbon (AC)/NF. This AHSC demonstrated a specific capacitance of 281 C g−1 at 1.0 A g−1, an operating voltage of 1.80 V, an i...
Research Interests:
The design of bimetallic tellurides that exhibit excellent electrochemical properties remains a huge challenge for high-performance supercapacitors. In the present study, tellurium is consolidated on CoNi2@rGO for the first time, to... more
The design of bimetallic tellurides that exhibit excellent electrochemical properties remains a huge challenge for high-performance supercapacitors. In the present study, tellurium is consolidated on CoNi2@rGO for the first time, to synthesize NiTe2-Co2Te2@rGO nanocomposite by using a facile hydrothermal method. As-prepared NiTe2-Co2Te2@rGO nanocomposite was characterized by EDS, TEM, FESEM, Raman, BET, XRD, and XPS techniques to prove the structural transformation. Upon the electrochemical characterization, NiTe2-Co2Te2@rGO has notably presented numerous active sites and enhanced contact sites with the electrolyte solution during the faradic reaction. The as-prepared nanocomposite reveals a specific capacity of 223.6 mAh g−1 in 1.0 M KOH at 1.0 A g-1. Besides, it could retain 89.3% stability after 3000 consecutive galvanostatic charge–discharge cycles at 1.0 A g−1 current density. The hybrid supercapacitor, fabricated by activated carbon as an anode site, and NiTe2-Co2Te2@rGO as a ...
Research Interests:
A voltammetric sensor based on a ZIF-8@CuO nanorod-modified GCE was developed to determine selectively furazolidone by differential pulse voltammetry.
Research Interests: Chemistry, Copper, Nanocomposite, Metal, Nanorod, and 3 moreCHEMICAL SCIENCES, Oxide, and Electrocatalyst
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Abstract A mononuclear Re(I) complex, [ReCl(CO) 3 (phen-dione)], was investigated as a new electrocatalyst for the reduction of CO 2 in two catalytic systems (homogeneous and heterogeneous) by voltammetry experiments. A modified pencil... more
Abstract A mononuclear Re(I) complex, [ReCl(CO) 3 (phen-dione)], was investigated as a new electrocatalyst for the reduction of CO 2 in two catalytic systems (homogeneous and heterogeneous) by voltammetry experiments. A modified pencil graphite electrode with carboxylated multiwall carbon nanotubes (CMWCNTs-PGE) was used as a working electrode for both catalytic systems. In the homogeneous system, the Re(I) complex revealed the catalytic activity for the reduction of CO 2 to CO in an acetonitrile solution at the onset potential of −545 mV vs. NHE. Also, the results showed that the presence of methanol as a weak Bronsted acid enhanced the rate of the catalytic process for the reduction of CO 2 in the homogenous condition. In the heterogonous condition, the Re(I) complex was simply casted on the CMWCNTs-PGE and then investigated for the reduction of CO 2 in an acidic solution of MeOH. The results also revealed that the onset potential for the heterogeneous catalyst was more positive than the homogenous condition. Also, the cathodic current density for the heterogeneous catalyst was higher in an acidic solution of MeOH. Adding sulfuric acid shifted the onset potential about 477 mV toward the more positive potential (at the onset potential of −390 mV vs. NHE) and increased the cathodic current about 10.7 times in the heterogeneous reduction of CO 2 .
Research Interests:
Research Interests:
Research Interests:
Silver nanoparticles were decorated on organic amine chain functionalized multiwall carbon nanotubes to fabricate a sensitive glucose sensor.
Research Interests:
Research Interests:
AbstractThis study was conducted to design a biosensor as a new, rapid, and sensitive tool for investigation of binding of zearalenone with double-stranded DNA (dsDNA). Polydiallyldimethylammonium chloride (PDDA) as a polycation and... more
AbstractThis study was conducted to design a biosensor as a new, rapid, and sensitive tool for investigation of binding of zearalenone with double-stranded DNA (dsDNA). Polydiallyldimethylammonium chloride (PDDA) as a polycation and multiwall carbon nanotubes (MWCNTs) provide a positively charged surface with a high surface area for the immobilization of dsDNA as a polyanion on the surface of pencil graphite electrode (PGE). Using the dsDNA/MWCNT–PDDA-modified PGE, it was possible to detect the interaction of zearalenone with dsDNA, which allowed us to apply the dsDNA-modified electrode for trace determination of zearalenone. The changes at the oxidation signal of adenine were evaluated before/after each modification/immobilization step. By using dsDNA/PDDA–MWCNT/PGE, zearalenone could be detected as low as 0.005 ng mL−1. The relative standard deviation of five measurements of 0.5 ng mL−1 zearalenone was found to be 4.2 %. Finally, the highly stable electrochemical biosensor was applied to analyze the zearalenone concentration in milk and wheat samples. Graphical AbstractxElectrochemical DNA Biosensor for Zearalenone detection
Research Interests: Chemistry, Electrochemistry, Biosensor, Bioassay, Toxin, and 3 moreMycotoxin, Food Sciences, and Zearalenone
CuBi2O4 nanoparticles are electrochemically deposited on nanoporous stainless steel supports from aqueous HNO3 solutions containing Bi(NO3)3 and Cu(NO3)2 in a molar ratio of 2:1.
Research Interests:
Here, cobalt ferrite nanohybrid decorated on exfoliated graphene oxide (CoFe2O4/EGO) was synthesized. The nanohybrid was characterized by different methods such as X-ray diffraction spectroscopy, scanning electron microscopy, energy... more
Here, cobalt ferrite nanohybrid decorated on exfoliated graphene oxide (CoFe2O4/EGO) was synthesized. The nanohybrid was characterized by different methods such as X-ray diffraction spectroscopy, scanning electron microscopy, energy dispersive X-ray diffraction microanalysis, transmission electron microscopy, FT-IR, Raman spectroscopy and electrochemical methods. The CoFe2O4/EGO nanohybrid was used to modify glassy carbon electrode (GCE). The voltammetric investigations showed that CoFe2O4/EGO nanohybrid has synergetic effect towards the electro-reduction of H2O2 and electro-oxidation of nicotinamide adenine dinucleotide (NADH). Rotating disk chronoamperometry was used for their quantitative analysis. The calibration curves were observed in the range of 0.50 to 100.0 μmol L(-1) NADH and 0.9 to 900.0 μmol L(-1) H2O2 with detections limit of 0.38 and 0.54 μmol L(-1), respectively. The repeatability, reproducibility and selectivity of the electrochemical sensor for analysis of the analytes were studied. The new electrochemical sensor was successfully applied for the determination of NADH and H2O2 in real samples with satisfactory results.
Research Interests:
Research Interests:
Functionalized‐multiwall carbon nanotubes decorated with redox active copper nanoparticles have been fabricated for sensitive enzyme‐less H2O2 detection. The new nanocomposite was characterized by Transmission electron microscopy, energy... more
Functionalized‐multiwall carbon nanotubes decorated with redox active copper nanoparticles have been fabricated for sensitive enzyme‐less H2O2 detection. The new nanocomposite was characterized by Transmission electron microscopy, energy dispersive X‐ray analysis and cyclic voltammetry. The response of the modified electrode to H2O2 was examined using amperometry at −0.45 V vs. Ag/AgCl in a buffer solution at pH 10.0. The developed sensor displayed linear concentration ranges of 0.5–10.0 and 10.0–10000.0 µmol L−1 with a detection limit of 0.3 µmol L−1. The proposed sensor displayed good selectivity for H2O2 detection in the presence of common interferences such as ascorbic acid.
Research Interests:
ABSTRACT An automated gas analyser has been designed, constructed and installed for online monitoring of H2, CH4, CO and CO2 in the reduction plant at Mobarakeh Steel Company, Iran. A small and low-resolution mass spectrometer is used in... more
ABSTRACT An automated gas analyser has been designed, constructed and installed for online monitoring of H2, CH4, CO and CO2 in the reduction plant at Mobarakeh Steel Company, Iran. A small and low-resolution mass spectrometer is used in this instrument. The analyser accepts the sample directly from the ambient pressure. Mass spectra are converted to percentages of the species in the mixture based on a derived mathematical expression and especially developed software. The instrument is capable of simultaneously analyzing six different gas inputs. The instrument recorded a precision level of below 3%.
Research Interests:
Research Interests: Materials Science, Biomedical Engineering, Nanoparticle, Carbon Nanotube, Transmission Electron Microscopy, and 14 moreCyclic Voltammetry, Atomic Force Microscopy, Medicine, Humans, Dielectric Spectroscopy, Nickel, Fourier transform infrared spectroscopy, Electrodes, Hydrogen-Ion Concentration, Ferric Compounds, Magnetite Nanoparticles, Biosensing Techniques, Nanotubes Carbon, and Linear Sweep Voltammetry
Research Interests:
Page 1. ANALYTICAL LETERS, 28(4), 73 1-747 (1995) DETERMINATION OF THIOCYANATE AT THE NANOGRAW LEVEL BY A KINETIC METHOD Keywords: Thiocyanate, Catalytic, Iodine-Sodium Azide Ali A . Ensafi* and ...
Research Interests:
The synergistic effect between metal ions and increasing the surface area leads to the fabrication of supercapacitor materials with high capacity. It is predicted that transition metal selenide compounds will be ideal electrode materials... more
The synergistic effect between metal ions and increasing the surface area leads to the fabrication of supercapacitor materials with high capacity. It is predicted that transition metal selenide compounds will be ideal electrode materials for supercapacitors. However, the defects of poor conductivity and volume expansion of the compounds are fundamental problems that must be solved. In this work, we successfully synthesized the cobalt-nickel selenide nitrogen-doped carbon (H-CoNiSe2/NC) hollow polyhedral composite structure using ZIF-67 as a precursor. The CoSe2 and NiSe2 nanoparticles embedded in the NC polyhedral framework offer a wealth of active sites for the whole electrode. Moreover, the presence of the NC structure in the proposed composite can simultaneously lead to improved conductivity and reduce the volume effect created during the cycling procedure. The H-CoNiSe2/NC electrodes provide high specific capacity (1131 C/g at 1.0 A/g) and outstanding cyclic stability (91.4% ret...
Research Interests:
ABSTRACT
Research Interests:
Research Interests:
Abstract This work mainly deals with the application of cleanup, preconcentration and electrochemical determination of flutamide. A new system is developed to cleanup and detect of flutamide at the surface of a working electrode.... more
Abstract This work mainly deals with the application of cleanup, preconcentration and electrochemical determination of flutamide. A new system is developed to cleanup and detect of flutamide at the surface of a working electrode. Differential pulse voltammetry (DPV) was used as a detection system. A modified pencil graphite electrode (PGE) was used as a working electrode. The surface of the PGE was coated with sodium dodecyl sulfate (SDS)-modified silica thin film. Flutamide is extracted from sample to the modified silica thin film and reduced electrochemically, and then, it was oxidized at the electrode surface. The effect of sample pH, SDS concentration, percentage of ingredients fiber structure, applied potential on the formation of fiber, and applied potential time on the electrode surface to form the fiber were evaluated. Other essential factors for flutamide extraction such as extraction time, stirring rate, pretreatment potential and electrochemical parameters were optimized. Using the extraction system, the DPV responses of different concentrations of flutamide were linear in the range of 0.10–100.0 nmol L−1 and 0.10–100.0 μmol L−1 with a detection limit of 34 pmol L−1. The technique was successfully applied for the determination of flutamide in human urine and plasma samples. The technique was successfully applied for the determination of flutamide in human urine and plasma samples.Graphical Abstract
Research Interests:
Research Interests:
A new electrode material for supercapacitor application is introduced based on polypyrrole conductive polymer and nickel-cobalt hexacyanoferrate poly-nuclear inorganic compound.
Research Interests:
A new electrochemical biosensor is introduced to study naringin–DNA interaction and naringin detection, using a modified pencil graphite electrode (PGE). The biosensor was prepared by modification of a PGE with MWCNTs-poly... more
A new electrochemical biosensor is introduced to study naringin–DNA interaction and naringin detection, using a modified pencil graphite electrode (PGE). The biosensor was prepared by modification of a PGE with MWCNTs-poly dialyldimethylammonium chloride (PDDA) decorated with ds-DNA (dsDNA/PDDA-MWCNTs/PGE). Change in the oxidation signals of adenine and guanine was used as probes for the biosensor evaluation, using differential pulse voltammetry. Under the optimized conditions, naringin could be measure from 0.058 to 580.0 µg mL−1 with a limit of detection of 0.010 µg mL−1. The relative standard deviation for five measurements of 0.58 µg mL−1 naringin was found as 3.7 and 4.2 %, based on the guanine and adenine signals, respectively. The biosensor was used as a selective sensor for the determination of naringin. In addition, electrochemical impedance spectroscopy was performed to evaluate the charge-transfer resistance of the modified and unmodified PGEs. Finally, this highly stable electrochemical biosensor was used to analyze naringin contents in various citrus juices.Graphical Abstract
Research Interests:
A novel method was initially developed for the activation of a gold electrode modified with gold nanoparticles by applying a high potential in the presence of sodium hydroxide. In a second stage, the selective oxidation of folic acid was... more
A novel method was initially developed for the activation of a gold electrode modified with gold nanoparticles by applying a high potential in the presence of sodium hydroxide. In a second stage, the selective oxidation of folic acid was investigated on the gold electrode described above. The effects of chemical and instrumental parameters such as NaOH concentration, scan rate, activation potential, and the duration of high potential application were investigated and the parameters were optimized. The results showed that 1.0 mol L –1 NaOH solution at a scan rate of 100 mV s –1 and with an applied potential of 4.50 V for 60 s produced the best results. The optimized sensor was then used to measure folic acid by differential pulse voltammetry. A good linear correlation was found between the peak current of folic acid and its concentration in the range of 1.0 × 10–8 to 1.0 × 10–6 mol L–1 with a detection limit of 7.50 × 10–9 mol L–1. The effects of potential interfering compounds on th...
Research Interests:
A highly selective voltammetric method was developed for the simultaneous determination of ascorbic acid (AA), dopamine (DA), and uric acid (UA) using Tiron polymer film modified on glassy carbon electrode. The modified electrode... more
A highly selective voltammetric method was developed for the simultaneous determination of ascorbic acid (AA), dopamine (DA), and uric acid (UA) using Tiron polymer film modified on glassy carbon electrode. The modified electrode separated the anodic oxidation peaks potential of AA, DA and UA with a well-defined peak separation in the present of each other to measure AA, DA and UA individually or simultaneously without any intermolecular effect. The calibration curves were obtained over the range of 4.0-792.0 µmol/L AA, 0.2-45.8 µmol/L DA, and 0.06-166.0 µmol/L UA. Detection limits of 1.79 µmol/L AA, 0.07 µmol/L DA, and 0.021 µmol/L UA were obtained at pH 3.0. The interference of potential interfering substances on the determination of AA, DA and UA were studied, and the results confirm the selectivity of the method. The modified electrode was used for the determination of AA, DA, and UA simultaneously in real samples such as drugs, urine, and synthesis samples, with satisfactory re...
Research Interests:
Research Interests:
Research Interests:
Research Interests: Chemistry, Data Analysis, Chemometrics, Kinetics, Environmental Analytical Chemistry, and 15 moreDosage Form, Partial Least Squares, Nitrite, Chemical Analysis, Kinetic, Cross Validation, Partition Coefficient, Bromate, Food development, Charge transfer, Matrix Effect, Analytical Sciences, Pharmaceutical Formulation, kinetic analysis, and limit of detection
Research Interests:
A new simple and inexpensive optical chemical sensor for cadmium(II) ions is presented. The cadmium sensing system was prepared by incorporating 2-amino-cyclopentene-1-dithiocarboxylic acid (ACDA) on a triacetylcellulose membrane. The... more
A new simple and inexpensive optical chemical sensor for cadmium(II) ions is presented. The cadmium sensing system was prepared by incorporating 2-amino-cyclopentene-1-dithiocarboxylic acid (ACDA) on a triacetylcellulose membrane. The absorption spectra of the optical sensor membrane in Cd(II) solution showed a maximum peak at 430 nm. The proportionality in intensity of the membrane color on the optode to varying amounts
Research Interests:
A new differential pulse voltammetric method for dopamine determination at a bare glassy carbon electrode has been developed. Dopamine, ascorbic acid (AA) and uric acid (UA) usually coexist in physiological samples. Because AA and UA can... more
A new differential pulse voltammetric method for dopamine determination at a bare glassy carbon electrode has been developed. Dopamine, ascorbic acid (AA) and uric acid (UA) usually coexist in physiological samples. Because AA and UA can be oxidized at potentials close to that of DA it is difficult to determine dopamine electrochemically, although resolution can be achieved using modified electrodes. Additionally, oxidized dopamine mediates AA oxidation and the electrode surface can be easily fouled by the AA oxidation product. In this work a chemometrics strategy, partial least squares (PLS) regression, has been applied to determine dopamine in the presence of AA and UA without electrode modification. The method is based on the electrooxidation of dopamine at a glassy carbon electrode in pH 7 phosphate buffer. The dopamine calibration curve was linear over the range of 1–313 μM and the limit of detection was 0.25 μM. The relative standard error (RSE %) was 5.28%. The method has bee...
Research Interests:
The potential toxicity of catecholics is a big concern, because the catechol-derived semiquinone radical after the oxidation of catechol (CA) can donate an H-atom to generate quinone, and during this process a superoxide anion radical may... more
The potential toxicity of catecholics is a big concern, because the catechol-derived semiquinone radical after the oxidation of catechol (CA) can donate an H-atom to generate quinone, and during this process a superoxide anion radical may be produced. Considering the fact that catecholics are highly consumed in our daily life and some drugs also contain one or more CA moieties, we speculate that CA's toxicity might not be insurmountable. Therefore, finding approaches to investigate catecholics potential toxicity is of great significance. Here in, an electrochemical protocol for direct monitoring of genotoxicity of catecholics is described. CA encapsulated on MWCNTs (CA@MWCNT) through continuous cyclic voltammetric on the surface of pencil graphite electrode (PGE). Subsequently, a DNA functionalized biosensor (DNA/CA@MWCNT/PGE) was prepared and characterized for the detection and the investigation of DNA damage induced by radicals generated from catecholics. The change in the charge transfer resistance (Rct) after the incubation of the DNA biosensor in the damaging solution for a certain time was used as an indicator for DNA damage. Incubation of DNA-modified electrode with CA solution containing Cu(II), Cr(VI) and Fe(III) has been shown to result in oxidative damage to the DNA and change in the electrochemical properties. It was found that the presence of Cu(II), Cr(VI) and Fe(III) in solution caused damage to DNA. The inhibitory effect of glutathione and plumbagin on the CA-mediated DNA damage has also been investigated using the biosensor. The minimum concentration of the metal ions for CA induced DNA damage was investigated. Recognition of suitable matrixes for CA-mediated DNA damage can be assessed using proposed DNA biosensor. Such direct monitoring of the DNA damage holds great promise for designing new biosensors with modification of the biosensor with different damaging agents.
Research Interests:
Research Interests:
A simple kinetic spectrophotometric method was developed for the determination of traces of vanadium present in petroleum, food and steel. The method is based on the catalytic effect of vanadium on the oxidation of gallocyanine by bromate... more
A simple kinetic spectrophotometric method was developed for the determination of traces of vanadium present in petroleum, food and steel. The method is based on the catalytic effect of vanadium on the oxidation of gallocyanine by bromate at a pH of 4.0. The decrease in ...
Research Interests:
Research Interests: Engineering, Chemistry, Analytical Chemistry, Neural Network, Medicine, and 15 moreAdsorption, Multivariate Analysis, Copper, Calibration, Lead, Cathodic Stripping Voltammetry, Metals, CHEMICAL SCIENCES, Metal ion, Analyst, Anodic Stripping Voltammetry, Optimality Condition, Artificial Neural Network, Multivariate Calibration, and limit of detection
Research Interests:
A ferrocenemonocarboxylic acid modified carbon nanotubes paste electrode (FMAMCNTPE) was constructed and used as a fast and sensitive tool for the determination of isoproterenol (ISPT) at trace level. It has been shown by direct current... more
A ferrocenemonocarboxylic acid modified carbon nanotubes paste electrode (FMAMCNTPE) was constructed and used as a fast and sensitive tool for the determination of isoproterenol (ISPT) at trace level. It has been shown by direct current cyclic voltammetry, double step chronoamperometry and electrochemical impedance spectroscopy (EIS) that this modified electrode can catalyze the oxidation of ISPT in aqueous solution. The kinetic parameters of the system including electron transfer coefficient, and rate constant for the chemical reaction between ISPT and the redox sites in FMAMCNTPE were also determined using the electrochemical approaches. In addition, differential pulse voltammetry (DPV) was used for quantitative analysis. DPV showed wide linear dynamic range (0.5 – 50.0 mol L–1 ISPT) with a detection limit of 0.2 µmol L–1 ISPT. The relative standard deviation (RSD%) for ten successive assays of 5.0 mol L–1 ISPT was 1.9%. Finally, this method was also examined as a selective, simpl...