Conductive and radiative heat transfer inhibition in YSZ photonic glass

A high temperature stable ceramic photonic structure is demonstrated with low thermal conductivity and suppressed external radiative heat transfer. The structure is based on a disordered arrangement of yttria-stabilized zirconia (YSZ) microparticles, called photonic glass (PhG). The prepared YSZ-PhG film exhibits low thermal conductivity of 0.03 Wm⁻¹K⁻¹ comparable to that of the air. The small point contacts of the adjacent YSZ particles are the main cause of such low thermal conductivity. After annealing at 1400 °C for 5 h, the solid thermal conductivity increased to 0.3 Wm⁻¹K⁻¹ at room temperature due to the thermally induced neck formation, associated with an increased contact area between adjacent particles. This thermal conductivity is still much lower than that of conventional YSZ thermal barrier coatings (TBCs) with approximately 1 Wm⁻¹K⁻¹. At the same time, the PhG structure is an efficient scatterer for thermal radiation in the wavelength range between 1 and 6 μm. In an only 100 μm thick structure an average reflection of 84% was obtained. At 1400 °C, the effective thermal conductivity is 0.2 Wm⁻¹K⁻¹. The presented structure is applicable to other oxides with even lower bulk thermal conductivity and can be considered for future TBCs.     

Investigation of hydrogen plasma treatment for reducing defects in silicon quantum dot superlattice structure with amorphous silicon carbide matrix

We investigate the effects of hydrogen plasma treatment (HPT) on the properties of silicon quantum dot superlattice films. Hydrogen introduced in the films efficiently passivates silicon and carbon dangling bonds at a treatment temperature of approximately 400°C. The total dangling bond density decreases from 1.1 × 10¹⁹ cm^-3 to 3.7 × 10¹⁷ cm^-3, which is comparable to the defect density of typical hydrogenated amorphous silicon carbide films. A damaged layer is found to form on the surface by HPT; this layer can be easily removed by reactive ion etching.     

Study and characterization of porous copper oxide produced by electrochemical anodization for radiometric heat absorber

The aim of this work is to optimize the different parameters for realization of an absorbing cavity to measure the incident absolute laser energy. Electrochemical oxidation is the background process that allowed the copper blackening. A study of the blackened surface quality was undertaken using atomic force microscopy (AFM) analysis and ultraviolet-visible-infrared spectrophotometry using a Shimadzu spectrophotometer. A two-dimensional and three-dimensional visualization by AFM of the formed oxide coating showed that the copper surfaces became porous after electrochemical etching with different roughness. This aspect is becoming more and more important with decreasing current density anodization. In a 2 mol L ^-1 of NaOH solution, at a temperature of 90°C, and using a 16 mA cm² constant density current, the copper oxide formed has a reflectivity of around 3% in the spectral range between 300 and 1,800 nm. Using the ‘mirage effect’ technique, the obtained Cu₂O diffusivity and thermal conductivity are respectively equal to (11.5 ± 0.5) 10 to 7 m² s^-1 and (370 ± 20) Wm^-1 K^-1. This allows us to consider that our Cu₂O coating is a good thermal conductor. The results of the optical and thermal studies dictate the choice of the cavity design. The absorbing cavity is a hollow cylinder machined to its base at an angle of 30°. If the included angle of the plane is 30° and the interior surface gives specular reflection, an incoming ray parallel to the axis will undergo five reflections before exit. So the absorption of the surface becomes closely near 0.999999.     

Synergistic optimization of electrical-thermal properties of dual vacancy Bi1−x-yPbyCu1−xSeO by improving mobility and reducing lattice thermal conductivity

We fabricate Bi_1?x-yPb_yCu_1?xSeO (x = 0, 0.03, 0.06, y = 0, 0.10) samples via 4 min-microwave synthesis combined with 5 min-spark plasma sintering. The phase composition, microstructure, valence, and electrical and thermal transport properties of the samples are investigated at 298–873 K. Pb doping provides impurity carriers and increases the concentration to 0.9–3.0 × 10²⁰ cm^-³ . Bi and Cu vacancy could provide a carrier transport channel to reduce carrier scattering probability, leading to improved mobility. Twin crystals, stacking faults, and grain boundary segregation are observed in Bi_0.87Pb_0.10Cu_0.97SeO on scanning transmission electron microscopy. Bi and Cu vacancy increase the sample point defects in Pb-doped or undoped samples which results in a decrease in lattice thermal conductivity. The lattice thermal conductivity of Bi_0.87Pb_0.10Cu_0.97SeO is decreased to an extremely low value of 0.13 Wm^?1 K^?1 and a maximum ZT value of 1.09 is achieved at 873 K.     

Effect of seeding on the thermal conductivity of self-reinforced silicon nitride

Thermal conductivity of Si₃N₄ containing large β-Si₃N₄ particles as seeds for grain growth was investigated. Seeds addition promotes growth of β-Si₃N₄ grains during sintering to develop the duplex microstructure. The thermal conductivity of the material sintered at 1900 °C improved up to 106 W m⁻¹ K⁻¹, although that of unseeded material was 77 Wm⁻¹ K⁻¹. Seeds addition leads to reduction of the sintering temperature with developing the duplex microstructure and with improving the thermal conductivity, which benefits in terms of production cost of Si₃N₄ ceramics with thermal conductivity. ©     

Kinetic Modeling,Thermodynamic Approach and Molecular Dynamics Simulation of Thermal Inactivation of Lipases from Burkholderia cepacia and Rhizomucor miehei

The behavior against temperature and thermal stability of enzymes is a topic of importance for industrial biocatalysis. This study focuses on the kinetics and thermodynamics of the thermal inactivation of Lipase PS from B. cepacia and Palatase from R. miehei. Thermal inactivation was investigated using eight inactivation models at a temperature range of 40–70 °C. Kinetic modeling showed that the first-order model and Weibull distribution were the best equations to describe the residual activity of Lipase PS and Palatase, respectively. The results obtained from the kinetic parameters, decimal reduction time (D and t_R), and temperature required (z and z’) indicated a higher thermal stability of Lipase PS compared to Palatase. The activation energy values (Ea) also indicated that higher energy was required to denature bacterial (34.8 kJ mol⁻¹) than fungal (23.3 kJ mol⁻¹) lipase. The thermodynamic inactivation parameters, Gibbs free energy (ΔG^#), entropy (ΔS^#), and enthalpy (ΔH^#) were also determined. The results showed a ΔG^# for Palatase (86.0–92.1 kJ mol⁻¹) lower than for Lipase PS (98.6–104.9 kJ mol⁻¹), and a negative entropic and positive enthalpic contribution for both lipases. A comparative molecular dynamics simulation and structural analysis at 40 °C and 70 °C were also performed.     

Thermal and electrical properties of additive-free rapidly hot-pressed SiC ceramics

The thermal and electrical properties of newly developed additive free SiC ceramics processed at a temperature as low as 1850 °C (RHP0) and SiC ceramics with 0.79 vol.% Y₂O₃-Sc₂O₃ additives (RHP79) were investigated and compared with those of the chemically vapor-deposited SiC (CVD-SiC) reference material. The additive free RHP0 showed a very high thermal conductivity, as high as 164 Wm⁻¹ K⁻¹, and a low electrical resistivity of 1.2 × 10⁻¹ Ω cm at room temperature (RT), which are the highest thermal conductivity and the lowest electrical resistivity yet seen in sintered SiC ceramics processed at ≤1900 °C. The thermal conductivity and electrical resistivity values of RHP79 were 117 Wm⁻¹ K⁻¹ and 9.5 × 10⁻² Ω cm, respectively. The thermal and electrical conductivities of CVD-SiC parallel to the direction of growth were ∼324 Wm⁻¹ K⁻¹ and ∼5 × 10⁻⁴Ω⁻¹ cm⁻¹ at RT, respectively.     

Process induced alignment of carbon nanotube decreases longitudinal thermal conductivity of Al2O3 based porous composites

Alumina (Al₂O₃) based porous composites, reinforced with zirconia (ZrO₂), 3 and 8 mol% Y₂O₃ stabilized ZrO₂ (YSZ) and 4 wt% carbon nanotube (CNT) are processed via spark plasma sintering. The normalized linear shrinkage during sintering process of Al₂O₃-based composite shows minimum value (19.2–20.4%) for CNT reinforced composites at the temperature between 1650 °C and 575 °C. Further, the combined effect of porosity, phase-content and its crystallite size in sintered Al₂O₃-based porous composite have elicited lowest thermal conductivity of 1.2 Wm⁻¹K⁻¹ (Al₂O₃-8YSZ composite) at 900 °C. Despite high thermal conductivity of CNT (∼3000 Wm⁻¹K⁻¹), only a marginal thermal conductivity increase (∼1.4 times) to 7.3–13.4 Wm⁻¹K⁻¹ was observed for CNT reinforced composite along the longitudinal direction at 25 °C. The conventional models overestimated the thermal conductivity of CNT reinforced composites by up to ∼6.7 times, which include the crystallite size, porosity, and interfacial thermal resistance of Al₂O₃, YSZ and, CNT. But, incorporation of a new process induced CNT-alignment factor, the estimated thermal conductivity (of <6.6 Wm⁻¹K⁻¹) closely matched with the experimental values. Moreover, the high thermal conductivity (<76.1 Wm⁻¹K⁻¹) of the CNT reinforced porous composites along transverse direction confirms the process induced alignment of CNT in the spark plasma sintered composites.     

Effect of lattice impurities on the thermal conductivity of β-Si3N4

Effect of impurities in the crystal lattice and microstructure on the thermal conductivity of sintered Si₃N₄ was investigated by the use of high-purity β-Si₃N₄ powder. The sintered materials were fabricated by gas pressure sintering at 1900 °C for 8 and 48 h with addition of 8 wt.% Y₂O₃ and 1 wt.% HFO₂. A chemical analysis was performed on the loose Si₃N₄ grains taken from sintered materials after the chemical treatment. Aluminum was not removed from Si₃N₄ grains, which originated from the raw powder of Si₃N₄. The coarse grains had fewer impurities than the fine grains. Oxygen was the major impurity in the grains, and gradually decreased during grain growth. The thermal conductivity increased from 88 Wm⁻¹ K⁻¹ (8 h) to 120 Wm⁻¹ K⁻¹ (48 h) as the impurities in the crystal lattice decreased. Purification by grain growth thus improved the thermal conductivity, but changing grain boundary phases might also influence the thermal conductivity.     

Effect of La3+ substitution on the structural and thermoelectric properties of Ca3-xLaxCo4O9+δ

The thermoelectric properties of Ca₃Co₄O₉ were optimized by the substitution of La³⁺ for Ca²⁺ in Ca₃Co₄O₉. The La³⁺ substitution significantly enhanced the thermoelectric power factor and reduced the lattice thermal conductivity. The lattice thermal conductivities at 800 °C for x = 0 and 0.3 samples were 1.80 and 1.34 Wm⁻¹ K⁻¹, respectively. The reduced thermal conductivity was mainly attributed to mass and strain field fluctuations in the crystal lattice. Ca_2.7La_0.3Co₄O_9+δ showed the largest dimensionless figure-of-merit (0.282 at 800 °C) by combining high power factor and the lowest lattice thermal conductivity. This work demonstrates that the La³⁺ substitution is a highly effective approach for improving high-temperature thermoelectric properties.     

Effects of yttria and magnesia on densification and thermal conductivity of sintered reaction-bonded silicon nitrides

A variety of combinations of Y₂O₃ and MgO were used as additives in preparing Si₃N₄ ceramics by the sintering of reaction-bonded silicon nitride (SRBSN) method. By varying the amount of Y₂O₃ in the range of 0-5 mol% and that of MgO in the range of 0-8 mol%, the effects of Y₂O₃ and MgO additives on nitridation and sintering behaviors as well as thermal conductivity were studied. It was found that appropriate amount and combination of Y₂O₃ and MgO additives were essential for attaining full densification and achieving high thermal conductivity. The sample doped with 2.5 mol% of Y₂O₃ and 5 mol% of MgO attained a thermal conductivity of 128 Wm⁻¹K⁻¹ when sintered at 1900°C for 6 hours, and the sample doped with 2 mol% of Y₂O₃ and 4 mol% of MgO achieved a thermal conductivity of 156 Wm⁻¹K⁻¹ when sintered for 24 hours.     

Preparation and Characterization of a Chloroperoxidase-like Catalytic Antibody

The small molecule, meso-tetra(α,α,α,α-o-phenylacetamidophenyl) porphyrin (Mr1147.0) was used as complete antigen to elicit MAb through the immunization and cell fusion techniques. The MAb 1F2 obtained was demonstrated to be very pure by MALDI/TOFMS. The subtype of MAb 1F2 is IgG2a, which has a relative molecular weight of 156,678.8 Da.No significant change in the intensity of absorption peaks in UV and CD spectra was observed over a pH range between 6 and 12. The high stability of the abzyme and the tight binding between Fe porphyrin and antibody were also demonstrated. V_max, K_m, κcat, κcat/K_m for abzyme are 5.18 × 10⁻⁸ Ms⁻¹, 1.50 × 10⁻⁸ M, 0.518 s⁻¹, 3.45 × 10⁷ M⁻¹s⁻¹, respectively. The data obtained indicate that catalytic antibody has high catalytic activity. The chloroperoxidase activity of MAb 1F2-Fe porphyrin complex is stable from 10 °C to 60 °C.     

High interfacial thermal resistance induced low thermal conductivity in porous SiC-SiO2 composites with hierarchical porosity

The incorporation of a thermally insulating secondary phase can significantly increase the interfacial thermal resistance attributed to its low intrinsic thermal conductivity and the creation of multiple phonon scattering interfaces between adjacent SiC particles. The newly developed porous SiC-33 wt% SiO₂ composites with SiO₂ as a thermally insulating secondary phase exhibited a very low thermal conductivity (0.047 Wm⁻¹ K⁻¹, 72.4 % porous), which is an order of magnitude lower than the previously reported lowest thermal conductivity (0.14 Wm⁻¹ K⁻¹, 76.3 % porous) for powder processed porous SiC ceramics and is even lower than the thermal conductivity (0.060 Wm⁻¹ K⁻¹, 87.9% porous) of SiO₂ aerogel. The porous SiC-(16–73 wt%) SiO₂ composites processed from nano β-SiC and a 40 wt% carbon template exhibited a hierarchical (meso-/macro-porous) pore structure that transformed to a trimodal (micro-/meso-/macro-porous) porous structure when polysiloxane was added and sintering was performed at 600–1000 °C in air.     

Role of vanadium ions,oxygen vacancies,and interstitial zinc in room temperature ferromagnetism on ZnO-V2O5 nanoparticles

In this work, we present the role of vanadium ions (V⁺⁵ and V⁺³), oxygen vacancies (V_O), and interstitial zinc (Zn_i) to the contribution of specific magnetization for a mixture of ZnO-V₂O₅ nanoparticles (NPs). Samples were obtained by mechanical milling of dry powders and ethanol-assisted milling for 1 h with a fixed atomic ratio V/Zn?=?5% at. For comparison, pure ZnO samples were also prepared. All samples exhibit a room temperature magnetization ranging from 1.18?×?10⁻³ to 3.5?×?10⁻³ emu/gr. Pure ZnO powders (1.34?×?10⁻³ emu/gr) milled with ethanol exhibit slight increase in magnetization attributed to formation of Zn_i, while dry milled ZnO powders exhibit a decrease of magnetization due to a reduction of V_O concentration. For the ZnO-V₂O₅ system, dry milled and thermally treated samples under reducing atmosphere exhibit a large paramagnetic component associated to the formation of V₂O₃ and secondary phases containing V⁺³ ions; at the same time, an increase of V_O is observed with an abrupt fall of magnetization to σ?~?0.7?×?10⁻³ emu/gr due to segregation of V oxides and formation of secondary phases. As mechanical milling is an aggressive synthesis method, high disorder is induced at the surface of the ZnO NPs, including V_O and Zn_i depending on the chemical environment. Thermal treatment restores partially structural order at the surface of the NPs, thus reducing the amount of Zn_i at the same time that V₂O₅ NPs segregate reducing the direct contact with the surface of ZnO NPs. Additional samples were milled for longer time up to 24 h to study the effect of milling on the magnetization; 1-h milled samples have the highest magnetizations. Structural characterization was carried out using X-ray diffraction and transmission electron microscopy. Identification of V_O and Zn_i was carried out with Raman spectra, and energy-dispersive X-ray spectroscopy was used to verify that V did not diffuse into ZnO NPs as well to quantify O/Zn ratios.     

Effects of SiC whisker addition on mechanical,thermal, and permeability properties of porous silica-bonded SiC ceramics

The effects of SiC whisker addition into nano-SiC powder-carbon black template mixture on flexural strength, thermal conductivity, and specific flow rate of porous silica-bonded SiC ceramics were investigated. The flexural strength of 1200°C-sintered porous silica-bonded SiC ceramics increased from 9.5 MPa to 12.8 MPa with the addition of 33 wt% SiC whisker because the SiC whiskers acted as a reinforcement in porous silica-bonded SiC ceramics. The thermal conductivity of 1200°C-sintered porous silica-bonded SiC ceramics monotonically increased from 0.360 Wm^–1K^–1 to 1.415 Wm^–1K^–1 as the SiC whisker content increased from 0 to 100 wt% because of the easy heat conduction path provided by SiC whiskers with a high aspect ratio. The specific flow rate of 1200°C-sintered porous SiC ceramics increased by two orders of magnitude as the SiC whisker content increased from 0 to 100 wt%. These results were primarily attributed to an increase in pore size from 125 nm to 565 nm and secondarily an increase in porosity from 49.9% to 63.6%. In summary, the addition of 33 wt% SiC whisker increased the flexural strength, thermal conductivity, and specific flow rate of porous silica-bonded SiC ceramics by 35%, 133%, and 266%, respectively.     

Tuning of structural,optical, and magnetic properties of ultrathin and thin ZnO nanowire arrays for nano device applications

One-dimensional (1-D) ultrathin (15 nm) and thin (100 nm) aligned 1-D (0001) and (0001¯) oriented zinc oxide (ZnO) nanowire (NW) arrays were fabricated on copper substrates by one-step electrochemical deposition inside the pores of polycarbonate membranes. The aspect ratio dependence of the compressive stress because of the lattice mismatch between NW array/substrate interface and crystallite size variations is investigated. X-ray diffraction results show that the polycrystalline ZnO NWs have a wurtzite structure with a = 3.24 Å, c = 5.20 Å, and [002] elongation. HRTEM and SAED pattern confirmed the polycrystalline nature of ultrathin ZnO NWs and lattice spacing of 0.58 nm. The crystallite size and compressive stress in as-grown 15- and 100-nm wires are 12.8 nm and 0.2248 GPa and 22.8 nm and 0.1359 GPa, which changed to 16.1 nm and 1.0307 GPa and 47.5 nm and 1.1677 GPa after annealing at 873 K in ultrahigh vacuum (UHV), respectively. Micro-Raman spectroscopy showed that the increase in E₂ (high) phonon frequency corresponds to much higher compressive stresses in ultrathin NW arrays. The minimum-maximum magnetization magnitude for the as-grown ultrathin and thin NW arrays are approximately 8.45 × 10⁻³ to 8.10 × 10⁻³ emu/g and approximately 2.22 × 10⁻⁷ to 2.190 × 10⁻⁷ emu/g, respectively. The magnetization in 15-nm NW arrays is about 4 orders of magnitude higher than that in the 100 nm arrays but can be reduced greatly by the UHV annealing. The origin of ultrathin and thin NW array ferromagnetism may be the exchange interactions between localized electron spin moments resulting from oxygen vacancies at the surfaces of ZnO NWs. The n-type conductivity of 15-nm NW array is higher by about a factor of 2 compared to that of the 100-nm ZnO NWs, and both can be greatly enhanced by UHV annealing. The ability to tune the stresses and the structural and relative occupancies of ZnO NWs in a wide range by annealing has important implications for the design of advanced photonic, electronic, and magneto-optic nano devices.     

Determinations of Ce solid solution mechanism and limit thermal conductivity of YTaO4 ceramics

x mol% CeO₂-YTaO₄ (x = 0, 3, 6, 9, 12) ceramics have been synthesized by the spark plasma sintering (SPS) technique. We focus on the changes in lattice distortion, bonding length, thermal conductivity, thermal expansion, and phase stability of the prepared samples. XRD, Raman, and XPS are used to determine the chemical valence and solid solution mechanism of Ce in the lattice of YTaO₄, while its effects on thermal/mechanical properties are elucidated from microstructures. Y³⁺ is substituted via Ce³⁺, and all samples maintain a monoclinic phase. The limit thermal conductivity (1.2 W?m^?1?K^?1, 900 °C) is realized in 9 mol% CeO₂-YTaO₄, and the thermal expansion coefficients are increased to 10.2 × 10^?6 K^?1 at 1200 °C. Furthermore, the exceptional phase stability and mechanical properties of all samples indicate that they can provide good thermal insulation at high temperatures, and have higher working temperatures than the current YSZ thermal barrier coatings.     

Thermoelectric properties of Ca0.8Dy0.2MnO3 synthesized by solution combustion process

High-quality Ca_0.8Dy_0.2MnO₃ nano-powders were synthesized by the solution combustion process. The size of the synthesized Ca_0.8Dy_0.2MnO₃ powders was approximately 23 nm. The green pellets were sintered at 1150-1300°C at a step size of 50°C. Sintered Ca_0.8Dy_0.2MnO₃ bodies crystallized in the perovskite structure with an orthorhombic symmetry. The sintering temperature did not affect the Seebeck coefficient, but significantly affected the electrical conductivity. The electrical conductivity of Ca_0.8Dy_0.2MnO₃ increased with increasing temperature, indicating a semiconducting behavior. The absolute value of the Seebeck coefficient gradually increased with an increase in temperature. The highest power factor (3.7 × 10^-5 Wm^-1 K^-2 at 800°C) was obtained for Ca_0.8Dy_0.2MnO₃ sintered at 1,250°C. In this study, we investigated the microstructure and thermoelectric properties of Ca_0.8Dy_0.2MnO₃, depending on sintering temperature.     

Enhancing thermoelectric properties of p-type (Bi,Sb)2Te3 via porous structures

Bismuth telluride is a widely used commercial thermoelectric material with excellent thermoelectric performances near room temperature. Reducing thermal conductivity is one of the most effective ways to improve performances of thermoelectric materials. In this study, the thermal conductivity of the material was reduced by fabricating porous structures. Highly dense NaCl-(Bi,Sb)₂Te₃ composites were fabricated by a high-pressure technology. The NaCl phase was then removed from the composites by ultrasonic washing to produce porous structures. The produced (Bi,Sb)₂Te₃ porous materials possessed excellent thermoelectric properties. The porosity and pore size of the (Bi,Sb)₂Te₃ porous materials increased with the increasing NaCl content, decreasing the thermal conductivity significantly. An ultra-low lattice thermal conductivity of 0.21 Wm^?1K^?1 at 493 K was achieved when the porosity was 39%, almost the lowest lattice thermal conductivity reported for (Bi,Sb)₂Te₃ bulk materials. The figure of merit ZT value was enhanced to 1.05 at 493 K when the porosity was 25%. Compared with the most compacted samples (ZT = 0.79 and porosity of 10%) prepared under the same conditions, the ZT value of the porous samples increased by 33%. This study indicated that porous thermoelectric materials can be prepared simply, quickly and efficiently by high-pressure/ultrasonication washing to improve thermoelectric performances, which has evident reference values for preparing other thermoelectric pore materials with enhancing behaviors.     

Identification and Characterization of a Thermostable GH36 α-Galactosidase from Anoxybacillus vitaminiphilus WMF1 and Its Application in Synthesizing Isofloridoside by Reverse Hydrolysis

An α-galactosidase-producing strain named Anoxybacillus vitaminiphilus WMF1, which catalyzed the reverse hydrolysis of d-galactose and glycerol to produce isofloridoside, was isolated from soil. The α-galactosidase (galV) gene was cloned and expressed in Escherichia coli. The galV was classified into the GH36 family with a molecular mass of 80 kDa. The optimum pH and temperature of galV was pH 7.5 and 60 °C, respectively, and it was highly stable at alkaline pH (6.0–9.0) and temperature below 65 °C. The specificity for p-nitrophenyl α-d-galactopyranoside was 70 U/mg, much higher than that for raffinose and stachyose. Among the metals and reagents tested, galV showed tolerance in the presence of various organic solvents. The kinetic parameters of the enzyme towards p-nitrophenyl α-d-galactopyranoside were obtained as K_m (0.12 mM), V_max (1.10 × 10⁻³ mM s⁻¹), and K_cat/K_m (763.92 mM⁻¹ s⁻¹). During the reaction of reverse hydrolysis, the enzyme exhibited high specificity towards the glycosyl donor galactose and acceptors glycerol, ethanol and ethylene glycol. Finally, the isofloridoside was synthesized using galactose as the donor and glycerol as the acceptor with a 26.6% conversion rate of galactose. This study indicated that galV might provide a potential enzyme source in producing isofloridoside because of its high thermal stability and activity.