Voltammetric determination of venlafaxine as an antidepressant drug employing Gd2O3 nanoparticles graphite screen printed electrode

Graphite screen printed electrode modified with Gd_2 O_3 nanoparticles(Gd_2 O_3/SPE) was developed for the determination of venlafaxine(VF). The Gd_2 O_3 nanoparticles were thoroughly characterized by scanning electron microscopy(SEM), transmission electron microscopy(TEM) and X-ray diffraction(XRD) analyses. To study the electrochemical behaviour of venlafaxine cyclic voltammetry(CV), chronoamperometry(CHA)and differential pulse voltammetry(DPV) were employed. These studies reveal that the oxidation of venlafaxine is facilitated at Gd_2 O_3/SPE. After optimization of analytical conditions, analysis of venlafaxine using the modified electrode in 0.1 mol/L PBS(pH 7.0) demonstrates that the peak currents corresponding to venlafaxine vary linearly with its concentration in the range of 5.0 ×10~(-6)-9.0 × 10~(-4) mol/L. The detection limit(S/N = 3) of 2.1 × 10~(-7) mol/L is obtained for venlafaxine using DPV. The prepared modified electrode benefits from advantages such as simple preparation method, high sensitivity and low detection limit.Moreover, the evaluation of practical applicability of this proposed method is successful in the identification of venlafaxine in pharmaceutical formulations, urine and water samples.     

酶催化分光荧光法测定环境水中痕量铬(Ⅵ)

铬（Ⅳ）对血红蛋白模拟酶催化荧光体系具有强烈的猝灭作用, 据此建立了一种酶催化分光荧光法测定铬（Ⅳ）的新方法。研究了溶液酸度、L-酪氨酸浓度、血红蛋白浓度、H₂O₂浓度及反应时间等因素对体系的影响。在pH10.4的NH₃·H₂O-NH₄Cl缓冲溶液中, 当L-酪氨酸、血红蛋白和H₂O₂的浓度分别为1.4×10^-4mol/L、1.0×10^-6mol/L和3.5×10^-5mol/L时, 测定铬（Ⅳ）的线性范围为2.0×10^-6～1.0×10^-4mol/L, 检出限为1.1×10^-8mol/L。1000倍NO₃^-、SO₄^2-、Na⁺、K⁺、Cl^-、Br^-, 300倍PO₄^3-、Al³⁺、NH₄⁺, 50倍Mn²⁺、Mg²⁺、Fe²⁺、Cu²⁺, 1倍Fe³⁺对铬（Ⅳ）的测定没有干扰。干扰较大的Fe³⁺, 可加入过量的柠檬酸掩蔽。对浓度为4.8×10^-5mol/L的铬（Ⅳ）进行11次平行测定, 其相对标准偏差为2.8%。该法已成功地应用于环境水样中铬（Ⅳ）含量的测定。     

Solid–Liquid Interfacial Energy of Solid Neopentylglycol Solution in Equilibrium with Neopentylglycol–Aminomethylpropanediol Eutectic Liquid

The grain boundary groove shapes for solid neopentylglycol solution (NPG-40 mol pct AMPD) in equilibrium with the neopentylglycol (NPG)–aminomethylpropanediol (AMPD) eutectic liquid (NPG-42.2 mol pct AMPD) have been directly observed using a horizontal linear temperature gradient apparatus. From the observed grain boundary groove shapes, the Gibbs–Thomson coefficient (Г) and solid–liquid interfacial energy (σ _SL) of solid NPG solution have been determined to be (7.4 ± 0.7) × 10^?8 K m and (6.4 ± 1.0) × 10^?3 J m^?2, respectively. The grain boundary energy of solid NPG solution has been determined to be (12.5 ± 1.0) × 10^?3 J m^?2 from the observed grain boundary groove shapes. The ratio of thermal conductivity of equilibrated eutectic liquid to thermal conductivity of solid NPG solution has also been determined to be 0.48.     

Absorption behavior of lattice oxygen in Ce_(0.8)Y_(0.2)O_(2-δ) at intermediate temperature

The absorption behavior of lattice oxygen for Ce_(0.8)Y_(0.2)O_(2-δ)(YDC) crystal was investigated. Combined with TG-DSC, XRD, Raman and XPS characterization, lattice oxygen absorption occurs at intermediate temperature(from 500 to 800 ℃),which is related to the oxygen vacancies consumption,and no phase change is observed in this process. In electric conductivity relaxation(ECR) experiment, prolonged oxygen diffusion process is observed above 600 ℃, which may be caused by oxygen absorption process. And through ECR experiments,the bulk diffusion coefficient D_(chem) and surface exchange coefficient K_(ex) for YDC dense sample are measured as 6,5×10~(-5)-2×10~(-4)cm~2/s and K_(ex)=2×10~(-4)-9×10~(-4)cm/s at intermediate temperature range.     

A fluorescent probe based on a spiropyran for sensitive detection of Ce~(3+) ion

A spiropyran-based probe was developed.It serves as a fluorescence turn-on probe for selective detection of Ce~(3+) in both ethanol and aqueous(water/ethanol,1:9 or 9:1,v/v) media.Ce~(3+) can induce photochromism of the probe though the probe exhibits negligible photochromic property by itself.The probe is sensitive to Ce~(3+) and the detection limit reaches 1.7 μmol/L.It exhibits a high selectivity for Ce~(3+)ion over other common metal cations including Li~+,Na~+,Ag~+,Sr~(2+),Ni~(2+),Co~(2+),Hg~(2+),Zn~(2+),Cr~(3+),Al~(3+),Fe~(3+) and Bi~(3+) and lanthanide ions Nd~(3+),Yb~(3+) and La~(3+).The probe may be used for quantitative determination of the concentration of Ce~(3+) ion in a range of 1-10 μmol/L and for application to environmental water samples.Sensing mechanism of the probe towards Ce~(3+) ion is proposed.     

Color-tunable Ca10Na(PO4)7:Ce3+/Tb3+/Mn2+ phosphor via energy transfer

A series of Ca_(10)Na(PO_4)_7:Ce~(3+)/Tb~(3+)/Mn~(2+)(CNPO:Ce~(3+)/Tb~(3+)/Mn~(2+)) phosphors with high brightness were synthesized by high-temperature solid-state method. X-ray diffraction(XRD), scanning electron microscopy(SEM), diffuse reflectance spectra(DRS), photo luminescence(PL) spectra, luminescence decay curves and thermally stability were performed to characterize the as-prepared samples. For Ce~(3+)-doped samples, an intense and broad band emission is present under 265 nm excitation. When Ce~(3+) and Tb~(3+)are codoped, energy transfer(ET) process from Ce3+ to Tb3+ is demonstrated with electric dipole-dipole interaction. The internal and external quantum efficiencies(QEs) of CNPO:0.15 Ce~(3+), 0.04 Tb~(3+), 0.005 Mn~(2+)are measured to 76.79% and 54.11% under 265 nm excitation and temperature-dependent PL intensity can remain 51.78% at 150 ℃ of its initial intensity at 25 ℃. It is indicated that single-phased white lightemitting CNPO:Ce~(3+)/Tb~(3+)/Mn~(2+) phosphor can serve as a promising phosphor for illumination devices.     

Reaction between tetravalent cerium ion and chloride ion and effect of thiourea using cyclic voltammetry

To monitor the reaction between Ce⁴⁺ ion and Cl^– ion at the electron level, an electrochemical experiment was designed in this work. Herein, the intermediate and final products that may be produced during the redox reaction are directly tracked by using cyclic voltammetry, and the influences of Ce⁴⁺ ion concentration, temperature and F^– ion on the reduction peak potential of Ce⁴⁺ ion were investigated. The results show that Ce⁴⁺ ion reacts with Cl^– ion through an irreversible reaction without any intermediate products, and the rate-determining step of the reaction is diffusion during the electrode reaction. The effects of temperature (20–40 °C) and Ce⁴⁺ ion concentration (0.04–0.12 mol/L) on the reduction peak potential of Ce⁴⁺ ion can be ignored, but the higher the molar ratio of F^– to Ce⁴⁺ (0–3 mol/mol), the more easily the reduction of Ce⁴⁺ ion to Ce³⁺ ion occurs. Additionally, the Ce⁴⁺ ions are preferentially reduced by thiourea when thiourea is added in the HCl solution, and thiourea inhibits the oxidation of Cl^– ions to Cl₂ by forming a complex with Cl^– ions. This work provides a theoretical basis for the role of thiourea in inhibiting Cl₂ production and offers a new way to find new reductants.     

Synthesis and application of biocompatible nontoxic nanoparticles for reclamation of Ce3+ from synthetic wastewater: Toxicity assessment,kinetic, isotherm and thermodynamic study

The aim of present study is to synthesize forsterite nanoparticles(FRST) for the reclamation of cerium ions(Ce~(3+)) from synthetic wastewater.The aim to synthesize FRST nanoparticles is due to its biocompatible and nontoxic nature.The formation of nanoparticles with average diameter of 58 nm was confirmed by TEM analysis.SEM images of bare FRST nanoparticles show a heterogeneous surface with porous nature.BET surface area of FRST nanoparticles is calculated to be 33.69 m~2/g.The significant uptake of Ce~(3+) ions can be obtained for all the selected concentrations(25-150 mg/L) within 2 h of adsorbent—adsorbate interaction.The pH study shows that by increasing pH from acidic to alkaline range,higher removal can be achieved.Temperature study demonstrates the endothermic nature of Ce~(3+)adsorption.The value of sticking probability suggests very high sticking probability of Ce~(3+) ion for FRST nanoparticles.Ce~(3+) uptake is favored by higher temperature and with the increase in temperature from298 to 328 K,Langmuir adsorption capacity increases from 36.45 to 42.99 m~2/g.Applicability of FRST nanoparticles was also investigated for other light and heavy rare earth elements in single solute and multisolute systems,FRST nanoparticles show the significant removal of divalent metallic pollutants as well.The assessment of chemical toxicity of treated wastewater was carried out with the bioluminescent photobacterium(Vibrio fischeri) and decreased toxicity was observed in treated water samples.The outcome of present study suggests that the FRST nanoparticles can be efficiently utilized for the removal of Ce~(3+) ions and a wide range of other pollutant species as well.     

Synthesis and luminescence properties of novel Ce3+-doped Yb3Al5–xGaxO12 garnets with very fast decay time

A novel series of Ce~(3+)-doped Yb_3 Al_(5-x)Ga_xO_(12)(x = 0, 1,2, 3,4, 5) powders of ytterbium aluminum gallium garnets were synthesized by high temperature solid-state reaction in a carbon reducing atmosphere. The ytterbium aluminum garnets were characterized by X-ray powder diffraction, UV-Vis diffuse reflectance spectra, photoluminescence spectra and decay curves. Moreover, the substitution effect for the Al~(3+) sites with Ga~(3+) in 0.5 at%Ce:Yb_3 Al_(5-x)Ga_xO_(12)(x = 0,1, 2, 3, 4, 5) garnets were discussed. With the increase of Ga~(3+) ion concentration, the visible absorption peaks within 400-450 nm have blue shift phenomenon,while the absorption peaks in the range of 330-350 nm and the absorption band edge red shifts.Furthermore, the short decay times are very short with less than 10 ns due to the Yb~(3+) + Ce~(3+)→ Yb~(2+) + Ce~(4+) electron transfer reaction.     

Phase relations,microstructure, and valence transition studies on CaZr_(1-x)Ce_xTi_2O_7(0.0≤x≤1.0) system

In this study, Ce-doped zirconolite was synthesized through high-temperature solid-state reaction at 1250 ℃ in air for 96 h. The crystal phase.microstructure and valence transition were studied by X-ray diffraction(XRD), scanning electron microscopy(SEM), and X-ray photoelectron spectroscopy(XPS).Phase relations of CaZr_(1-x)Ce_xTi_2O_7 systems were determined by XRD analyses and Rietveld refinements.Four different phases are identified, namely zirconolite, perovskite, pyrochlore, and cerianite. The phase transformation(2M-zirconolite → 4M-zirconolite → Ce-pyrochlore) is caused by cations rearrangement as cerium content increases. The solubility limit of cerium ions in CaZr_(1-x)Ce_xTi_2O_7 system is estimated to be approximately 0.80. Under sintering air atmosphere, partial reduction of Ce~(4+) in Ce~(3+) is detected in Ce 3d XPS spectra, and the ratio of Ce~(3+) and Ce~(4+) significantly decreases as cerium content increases.     

Effects of Solute and Surfactant Addition on the Crystallization and Morphology of Hydroxyapatite Powders Synthesized by Hydrolysis of Calcium Hydrogen Phosphate Dehydrate (DCPD)

The effects of the addition of alcohol and cetyltrimethylammonium bromide (CTAB) on the crystallization and the morphology of hydroxyapatite (HA) powders synthesized by hydrolysis of calcium hydrogen phosphate dehydrate (DCPD) in the 2.5 M NaOH solutions at 348 K (75 °C) for 1 hour have been studied. The values of zeta potential have large differences between the sums of DCPD with CTAB (Z _DCPD+CTAB) minus the sum of DCPD and CTAB (Z _DCPD + Z _CTAB), and of HA with CTAB (Z _HA+CTAB) minus the sum of HA and CTAB (Z _HA + Z _CTAB), respectively. When the hydrolysis of DCPD occurred in the 2.5 M NaOH solutions at 348 K (75 °C) for 1 hour both with and without alcohol and CTAB, XRD results show the only one phase of HA in the as-dried powders. When the NaOH solution does not contain CTAB, the crystallite size of HA powders decreased from 23 ± 1 to 16 ± 1 nm as the alcohol content was more than 50 pct. The crystallite size of HA powders obtained from DCPD synthesized in the 2.5 M NaOH solution with 1.0 × 10^?3 M CTAB decreased when the alcohol content was increased to 70 pct, whereas the crystallite size increased when the alcohol concentration was greater than that of 70 pct. SEM images show that the HA powders have a rod-like shape when DCPD was synthesized in the 2.5 M NaOH solution without CTAB or alcohol. When the NaOH solution had 1.0 × 10^?3 M CTAB and various alcohol concentrations, the morphology of HA powder still maintained a rod-like or needle-like shape. The HA powder had a maximum specific surface area of 180.25 m²/g when the hydrolysis of DCPD occurred in a 2.5 M NaOH solution containing 1.0 × 10^?3 M CTAB and 70 pct alcohol at 348 K (75 °C) for 1 hour.     

Oxygen Permeation of Partly Molten Slags

The conductivities, oxygen ion transference numbers, and oxygen permeation fluxes of NiO-30, 36, 42, and 48 wt pct Bi₂O₃, In₂O₃-30, 36, 42, and 48 wt pct Bi₂O₃, ZnO-15, 20, 25, and 30 wt pct Bi₂O₃, ZrV₂O₇-16, 20, 24, and 28 wt pct V₂O₅, and BiVO₄-5, 7, 10, and 12 wt pct V₂O₅ partly molten slags have been measured by using the four-probe DC, volumetric measurements of the faradaic efficiency, and gas flow techniques, respectively, under various temperatures and oxygen partial pressure gradients. Results indicate that in the ranges of slag layer thicknesses 1 to 5 mm and temperatures 923 K to 1173 K (650 °C to 900 °C), used in the present study, the overall oxygen permeation kinetics is controlled by both chemical diffusion and surface exchange reactions. The oxygen permeation fluxes (3 × 10^?9 to 9 × 10^?8 mol/cm² s) were found to increase with volume fraction of liquid. The oxygen ion transference number was found to be in the range 0.2 to 0.8. The ambipolar conductivity, characteristic thickness, and surface exchange coefficient were estimated to be in the ranges 1.1 × 10^?3 to 2.3 × 10^?1 S/cm, 2 × 10^?2 to 7 × 10^?2 cm, and 1.3 × 10^?6 to 2.1 × 10^?6 cm/s, respectively.     

Effect of Er,Gd, and Nd Co-Dopants on the Properties of Sm-Doped Ceria Electrolyte for IT-SOFC

Doped ceria electrolytes of Ce_0.8Sm_0.20O_1.90 (SDC), Ce_0.8Er_0.08Sm_0.12O_1.90 (ESDC), Ce_0.8Gd_0.08Sm_0.12O_1.90 (GSDC), and Ce_0.8Nd_0.08Sm_0.12O_1.90 (NSDC) were prepared by a citric–nitrate combustion process. The thermal decomposition of the precursor was investigated by simultaneous thermogravimetric analysis and differential thermal analysis experiments. The phase structure of the calcined and sintered powders was characterized by X-ray diffraction analysis. All of the samples were fluorite-type ceria-based solid solutions. The calcined and sintered powders were also characterized by Fourier transform infrared spectroscopy. Scanning electron microscopy was used to characterize the samples after calcination and sintering. A relative density over 95 percent of the theoretical density was achieved after the sintering process. Electrical conductivities of the sintered samples were measured using the impedance spectra method. The highest ionic conductivity value was found to be 5.28 × 10^?2 S cm^?1 at 1023 K (750 °C) for GSDC sintered at 1673 K (1400 °C) for 6 hours.     

锡在壳聚糖-多壁碳纳米管修饰玻碳电极上的电化学行为及其测定

制备了壳聚糖(CTS)-多壁碳纳米管(MWCNT)修饰玻碳(GCE)电极,利用差分脉冲溶出伏安法研究了锡在该电极上的电化学行为,探讨了电极反应机理。在优化测定条件的基础上,提出了一种测定痕量锡的新方法。在1.0 mol/L的盐酸溶液中,于－1 000 mV电位处锡被富集在修饰电极表面,在－1 000～0.00 mV电位范围内,以800 mV/s的扫描速率,锡在－630 mV电位处产生一灵敏的溶出峰,峰电流与锡 的浓度在4.2×10^-8～1.3×10^-5 mol/L范围内呈良好的线性关系,检出限(S/N=3)为3.1×10^-9 mol/L。方法应用于生铁和合金钢样品中痕量锡的测定,结果与火焰原子吸收光谱法(FAAS)的测定结果基本一致。     

Corrosion Compatibility Studies of Stainless Steel 304L in Flowing Liquid Lead Bismuth Eutectic

Stainless steel 304L is being considered as a structural material for some components in the lead–bismuth eutectic (LBE) target facility operating at a temperature of about 250°C. Data available on the corrosion of SS 304L in LBE for long duration exposure at these temperatures are scanty. This paper gives the corrosion behaviour of SS 304L after the exposure of 6500 h in LBE in a non-isothermal loop with oxygen concentration of ~4 × 10^?10 wt% at temperatures of 250 and 350°C and with flow velocity of 16 cm s^?1. The composition of the surface film was analysed by energy dispersive X-ray (EDAX) and X-ray photoelectron spectroscopy techniques. To record the changes in the mechanical properties of SS 304L upon exposure tensile tests of the tensile specimens exposed to LBE were performed in air at room temperature and the fractured surfaces were examined by scanning electron microscope (SEM). Changes in microstructure and elemental composition of the exposed surface of SS 304L were studied using SEM and EDAX. While no changes were observed in the mechanical properties and microstructure due to prolonged exposure to LBE at either temperature, the specimens exposed to 350°C after 6500 h showed a corrosion rate of 1.2 × 10^?3 μm h^?1. While no penetration of LBE into the grain boundaries was observed at either temperature after an exposure of 6500 h, a minor depletion of nickel was noted in specimens exposed at 350°C.     

Optical and electrical conductivity properties of rare earth elements (Sm,Y, La,Er) co-doped CeO2

In this research, un-doped CeO₂ and Ce_0.85La_0.10M_0.05O₂ (M: Sm, Er, Y) compounds were synthesized by hydrothermal method and the multi-functional properties are reported. Oxygen defects were created with the additives of rare earth ions. The electrical and luminescence behaviors of the synthesized compounds were investigated in accord with the types of additives. The synthesized products were characterized by X-ray diffraction (XRD) analysis, Brunauer–Emmett–Teller (BET) measurement, UV–vis diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM), photoluminescence (PL) spectroscopy and electrochemical impedance spectroscopic (EIS). All synthesized compounds are found to be nano-structured and have cubic phase. The total conductivity of all samples was calculated. Hence, the total conductivity of un-doped CeO₂, Ce_0.85La_0.10Y_0.05O₂, Ce_0.85La_0.10Er_0.05O₂ and Ce_0.85La_0.10Sm_0.05O₂ is found to be 2.07 × 10^?10, 5.70 × 10^?4, 1.0 × 10^?3 and 0.0747 S/cm, respectively. Also, bandgap energy (E_g) of these samples calculated from UV visible absorption spectra is discussed, and the optical results show variation between 3.2 and 2.15 eV. Additionally, the luminescence properties of the compounds were investigated and different emissions occur depending on the additive type. Accordingly, photoluminescent emission spectra of Ce_0.85La_0.10Y_0.05O₂, Ce_0.85La_0.10Er_0.05O₂ and Ce_0.85La_0.10Sm_0.05O₂ phosphors indicate that these phosphors have red, green and orange-red colors, respectively.     

Hot Corrosion Behaviour of Refractory and Rare Earth Oxide Reinforced CoCrAlY APS Coatings at 700 °C

This paper investigates cyclic hot corrosion of plasma sprayed CoCrAlY?+?Al₂O₃?+?YSZ (C1) and CoCrAlY?+?CeO₂ (C2) composite coatings on MDN 321 and Superni 76 substrates in molten salt (Na₂SO₄-60%V₂O₅) environment exposed to 700 °C. Weight change technique is used to evaluate the corrosion performance. Both C1 and C2 coatings showed better corrosion resistance than uncoated alloy. Both the coatings showed linear weight gain during the initial cycles and parabolic weight gain nature with subsequent hot corrosion cycles. The parabolic rate constant (K_p) of C1 and C2 coating was observed to be in the range 0.29–0.32?×?10^?10 g² cm^?4 s^?1 and 1.0–1.13?×?10^?10 g² cm^?4 s^?1 respectively. In C1 coating, the globular and continuously packed structure on the corroded surface having CoO, Cr₂O₃, CoCr₂O₄ and CoAl₂O₄ spinel oxides provided superior hot corrosion resistance. While in case of C2 coating, the outward growth of CeVO₄ irregular crystals as a corrosion product of CeO₂ and V₂O₅ salt deteriorated the oxide scales resulting in higher corrosion rate.     

催化动力学光度法测定锌尾矿中痕量铅

在高氯酸-邻苯二甲酸氢钾介质中,于90 ℃水浴中加热,发现铅(Ⅱ)对碘酸钾氧化核固红的褪色反应有催化作用,据此建立了催化动力学光度法测定痕量铅的新方法。通过正交试验和方差分析确定最佳实验条件为:8.0 mL 1 g/L核固红(NFR)溶液,2.5 mL 0.02 mol/L HClO₄,0.5 mL 0.02 mol/L邻苯二甲酸氢钾溶液和1.5 mL 0.02 mol/L KIO₃溶液。方法线性范围为4.0×10^-5～4.4×10^-3 g/L,检出限为3.0×10^-6 g/L。实验表明,该催化反应为假一级反应,表观活化能E_a = 29.762 kJ/mol,反应表观速率常数K = 1.2×10^-4 s^-1。方法用于本地锌矿尾矿中铅含量的测定,测定值与原子吸收光谱法基本一致,相对标准偏差(n=9)为1.5% ~2.1%,加标回收率为98% ~ 104%。     

Genesis of nanocrystalline Ho2O3 via thermal decomposition of holmium acetate: Structure evolution and electrical conductivity properties

This study focuses on the preparation of nanostructured holmium oxide via the decomposition of holmium acetate precursor utilizing the non-isothermal strategy. Thermogravimetric analysis(TGA) was used to follow up the various thermal events involved in the decomposition process. Dehydration completes approximately at 150℃, which is followed by the decomposition of the anhydrous acetate leading to the formation of holmium oxide. Based on the TGA results the acetate precursor was heated non-isothermally at the temperature range of 150 e700℃. The obtained solids were characterized using powder X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS), Fourier transform infrared spectroscopy(FT-IR), field-emission scanning electron microscopy(FE-SEM) and transmission electron microscopy(TEM). It is found that nanocrystalline Ho_2 O_3 starts to form at 500℃ and presents the only phase detected at the 500 e700℃ range. The electrical conductivity of the solids that form at the temperature range of 300 e700℃ was investigated. The obtained values were correlated with the observed structural modifications accompanying the heat treatment. The electrical conductivity of the Ho_2 O_3 samples prepared at 500, 600 and 700℃ reaches the values of 1.92 × 10~(-7), 1.61 × 10~(-7) and 8.33 × 10~(-8) Ω~(-1)cm~(-1) at a measuring temperature of 500℃, respectively. These values are potentially advantageous for high-resistivity devices.     

Effects of CeCl3 and LaCl3 on callus and root induction and the physical response of tobacco tissue culture

La³⁺ and Ce³⁺ have positive effects on plant growth and production. Although it is well known that rare earth elements promote cell growth, the biological effects of La³⁺ and Ce³⁺ on callus, shoot and root induction in tobacco are still unclear. The relationships among callus induction, rooting, enzyme activities and stomatal characteristics in tobacco are unknown. The objectives of this study were to identify the relationships between the induction of calluses, shoots, roots, stomata and enzyme activities. The induction percentages of calluses, buds, roots were recorded at 5, 10, 15, 20 and 25 days after La³⁺ and Ce³⁺ treatments. Peroxidase isoenzyme activity was determined by electrophoresis. The characteristics of the stomata were observed under an optical microscope. Our results show that low concentrations of Ce³⁺ (<15 mg/L) result in increases in the induction percentages of calluses, buds and roots, but La³⁺ (>5 mg/L) inhibits the induction of calluses, buds and roots. There are more peroxidase isoenzyme bands in Ce³⁺ treatments than in La³⁺ treatments. This is consistent with the induction percentages of calluses, buds and roots in Ce³⁺ and La³⁺ treatments. High enzyme activities may promote the induction of calluses, buds and roots. The stomata area and stomata number of leaves are significantly different between La³⁺ treatments and Ce³⁺ treatments. La³⁺ improves the stomata area and number. Based on these results, we speculate that La³⁺ may promote the development of the photosynthetic system. Ce³⁺ may promote tobacco growth and rooting by improving enzyme activities.