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An electrochemical biosensor was prepared for nucleic acid-based hantavirus detection using a Cu-based metal-organic framework (CuMOF) as a signal tag. The CuMOF was synthesized by the solvothermal method and then covalently bonded with signal DNA (sDNA) probes. The Au nanoparticles and reduced graphene oxide composite were deposited on the electrode surface by electroreduction as support substrate and was then functionalized with capture DNA (cDNA) probes by self-assembly. Through the complementary base pairing, the target DNA (tDNA) fragment of hantavirus hybridized with the cDNA and the sDNA in a sandwich-type format. The tDNA was detected according to the current signal of the CuMOF catalyzed reaction using o-phenylenediamine as redox substrate. The peak current of the biosensor at − 0.55 V increased linearly in proportion to the logarithmic value of the tDNA concentration from 10−15 to 10−9 mol/L, with a detection limit of 0.74 × 10−15 mol/L. Moreover, the proposed biosensor was successfully applied to detect hantavirus and was able to distinguish hantavirus from other arboviruses.

D-Mannose isomerase can reversibly catalyze D-fructose to D-mannose which has various beneficial effects. A novel D-mannose isomerase gene (PsMIaseA) from Pseudomonas syringae was cloned and expressed in Escherichia coli. The recombinant D-mannose isomerase (PsMIaseA) showed the highest amino acid sequence homogeneity of 50% with ManI from Thermobifda fusca. PsMIaseA was purified through Ni-NTA chromatography, and its specific activity was 818.6 U mg-1. The optimal pH and temperature of PsMIaseA were pH 7.5 and 45 °C, respectively. The enzyme was stable within a wide pH range from 5.0 to 10.0. It could efficiently convert D-fructose to D-mannose without any metal ions. When PsMIaseA was incubated with 600 g/L D-fructose for 6 h, the space-time yield of D-mannose reached 27.2 g L-1 h-1 with a maximum conversion ratio of 27%. Therefore, the D-mannose isomerase may be suitable for green production of D-mannose.

An engineered β-mannanase (mRmMan5A) from Rhizomucor miehei was successfully expressed in Pichia pastoris. Through high cell density fermentation, the expression level of mRmMan5A reached 79,680 U mL−1. The mRmMan5A showed maximum activity at pH 4.5 and 65 °C, and exhibited high specific activities towards mannans. To produce manno-oligosaccharides, palm kernel cake (PKC) was pretreated by steam explosion at 200 °C for 7.5 min, and then hydrolyzed by mRmMan5A. As a result, the total manno-oligosaccharide yield reached 34.8 g/100 g dry PKC, indicating that 80.6% of total mannan in PKC was hydrolyzed. Moreover, the kilo-scale production of manno-oligosaccharides was carried out to verify the feasibility of mass production. A total of 261.3 g manno-oligosaccharides were produced from 1.0 kg of dry PKC. An effective β-mannanase for the bioconversion of mannan-rich biomasses and an efficient method for the production of manno-oligosaccharides from PKC are provided in this paper.

Partially hydrolyzed guar gum (PHGG), an important supplemental dietary fiber, has been used as food ingredient in many industries. In this study, a novel β-mannanase gene (RmMan5A) from Rhizomucor miehei was successfully expressed in Pichia pastoris and subjected for PHGG production. Enzyme activity of fermentation supernatant reached 85,200UmL-1 after 168h high cell density fermentation. The purified RmMan5A exhibited the highest enzyme activity at pH 7.0 and 65°C. RmMan5A was then employed for guar gum hydrolysis and PHGG obtained demonstrated a weight-average molecular weight (Mw) of 2.5×104Da. Total dietary fiber accounted 90.6% of PHGG and 24.9% (w/w) of PHGG were identified as manno-oligosaccharides with degree of polymerization

The crystallization behavior and microstructure of a series of Dy 3 + /Tb 3 + doped aluminoborosilicate (ABS) magneto-optical glass was investigated using differential scanning calorimetry (DSC), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The apparent crystallization activation energy ( E g ) and the kinetic properties at the corresponding glass transition temperature ( T g ) were studied as a function of Dy 3 + /Tb 3 + concentration. The results showed that the glass matrix precipitated Al 3 Tb(BO 3 ) 4 and TbBO 3 crystals when subjected to heat treatment at 852.8 and 902.6 °C, respectively. The crystallization activation energy of these two crystalline phases (Al 3 Tb(BO 3 ) 4 and TbBO 3 ) was E p1 = 993.3 kJ/mol and E p2 = 544.97 kJ/mol, respectively. The average crystallization index was 0.5 and 0.8, respectively. By applying the Kissinger equation to the parameterized crystallization behavior, the calculated phase transition activation energy was determined to be 420.18 kJ/mol. The parameterized crystallization behavior of this particular ABS magneto-optical glass can be used to avoid the deterioration of magneto-optical properties due to the crystallization of glass matrix.

To produce manno-oligosaccharides from cassia gum, a mutated glycoside hydrolase family 134 β-mannanase gene (mRmMan134A) from Rhizopus microsporus var. rhizopodiformis F518 was expressed in Pichia pastoris and a high expression level (3680 U mL−1) was obtained through high cell density fermentation. mRmMan134A exhibited maximum activity at pH 5.5 and 50 °C. It was then subjected to hydrolyze cassia gum with 70.6% of overall yield of manno-oligosaccharides. From the hydrolysate, seven components (F1–F7) were separated and identified as mannose, mannobiose, galactose, mannotriose, mannotetraose, 61-α- d -galactosyl-β- d -mannobiose, and mannopentaose, respectively. According to in vitro fermentation, the manno-oligosaccharides were able to promote the growth of three Bifidobacterium strains and six Lactobaillus strains with 3.0-fold increment in culture absorbance, and these strains preferred manno-oligosaccharides with degree of polymerization (DP) 2–3 rather than those with DP 4–5. Novel manno-oligosaccharides from cassia gum with promising prebiotic activity were provided in the present study.

Foam glass was prepared which using iron tailings and waste glass with SiC powders as foaming agent. The influence of the foam temperature on the bulk density, porosity, water absorption and compressive strength was studied. The results show that foam glass with higher iron tailings content of 24.5 wt% could be prepared at about 830 °C for 30 min. Some of the reactions inside the iron tailings are responsible for the foaming mechanisms. When the foam temperature was 830 °C, the bulk density and flexural strength reached a minimum value of 0.224 g/cm 3 and 0.53 MPa.

Hydroxyapatite luminescent nanocrystallines doped with 6 mol.% Tb3+ (Tb-HA) were prepared via chemical deposition method and calcined at different temperature, and the effects of calcinations temperature on the luminescence intensity and fluorescent lifetime were studied. TEM image of Tb-HA revealed that the shape of nanocrystallines changed from needle-like to short rod-like and sphere-like with the increase of calcinations temperature; while the particles sizes decreased from 190 nm to 110 nm. The crystallinity degree increased. The typical emission peaks attributed to Tb3+ ions were observed in emission spectra of 6 mol.% Tb-HA under 378 nm excitation. The luminescent intensity of Tb-HA, which showed the fluorescence quenching, firstly enhanced and then decreased at 700 °C; while the fluorescent lifetime increased firstly and then decreased after 600 °C. Furthermore, the ratio of intensity between 545 nm and 490 nm corresponding to electric-dipole and magnetic-dipole transition (IR: IO) increases firstly and then decreases, which revealed that the proportion of substitute type and site of Ca2+ ions by Tb3+ ions were helpful to realize the substitute process and functional structure design.

A series of Europium (Eu) and Strontium (Sr) codoped hydroxyapatite samples (Ca10-x-Srx-HAp: Eu) were designed and prepared using the chemical co-precipitation method. The crystalline structure, chemical composition and luminescent property of samples were characterized by X-ray diffraction (XRD) and photoluminescent spectrum (PL). XRD patterns showed that Eu doping had little effect on the structure of the samples, while with the increase of Sr content, crystallinity and interplanar crystal spacing were increased. PL spectra indicate that the fluorescence intensity at 596 nm and 618 nm of Ca-Sr-HAp: Eu samples increased firstly and then decreased with increase of Sr content at 394 nm excitation, and the strongest peak appeared in the Ca3-Sr7-HAp: Eu samples. At the same time, the fluorescence lifetime of the samples showed the same tendency with the increase of Sr content. In addition, the ratio of magnitude between electric dipole and magnetic dipole transition (IR/IO) also increased firstly and decreased subsequently along with the increase of Sr content in the matrix. Furthermore, the energy transfer 1104 无 机 材 料 学 报 第 31卷 parameters (f) calculated from luminescent dynamic of Eu correlating to different sites and transitions present the reverse change. It is concluded that the doped sites of Eu ions in the host lattice are affected by the content and location of Sr ions in the matrix. Thereby a tunable luminescent property of Ca10-x-Srx-HAp: Eu samples can be obtained by changing the site of Eu ions in the matrix through adjusting the value of Sr/Ca.