优化全磁选渣冶炼操作工艺研究

根据铁自身具备的磁性特征,通过磁选工艺处理钢渣,回收其中的铁被广泛关注~([1])。马钢特钢在转炉炼钢生产中使用的回收钢渣为全磁选渣,但在炼钢冶炼操作中存在喷溅、拉磷等问题。本文主要讨论在冶炼过程中如何解决这些问题来提高金属回收率,降低成本。

新型杂多化合物[(CH_3CH_2)_4N]_4H_3O·{Na[(HMo_2O_5)_3(HPO_4)(H_2PO_4)_3]_2}·(H_2PO_4)_2·10H_2O的水热合成与晶体结构

The title compound [(CH 3CH 2) 4N] 4H 3O{Na[(HMo 2O 5) 3(HPO 4)(H 2PO 4) 3] 2}·(H 2PO 4) 2·10H 2O was synthesized by hydrothermal method and its structure was determined with single crystal X ray analysis. The cluster anion of the title compound shows a P1 symmetry sandwich structure. The crystal is triclinic, space group P 1 with a =15.151 3(2) nm, b =15.851 7(10) nm, c =23\^025 1(10) nm, α = 89.00(1)° , β =80.09(3)°, γ = 74.30(2)°, V =5.241 90(8) nm 3, Z =2, D c=2.105 g/cm 3, F (000)=3 270, S =1.039, μ =1. 655 mm -1 .

Effects of polyphosphoric acid modified asphalt on the low-temperature cracking of asphalt mixtures

In order to determine whether polyphosphoric acid （PPA） can partially or completely substitute styrene-butadiene- styrene （SBS） modifier while it does not adversely affect the resistance to thermal cracking of the asphalt mixture, the low- temperature fracture properties of the PPA modified mixtures are evaluated and compared to the SBS modified mixtures. First, laboratory compacted test samples were tested by the indirect tensile test （IDT） and the newly developed fracture testing protocol, named as disk-shaped compact tension （DCT）. Then, the effects of the test temperature and air-void ratio on the low-temperature fracture properties of asphalt mixtures were analyzed. The results show that the fracture resistance of the PPA modified mixtures is worse than that of the SBS modified mixtures. However, for those modified mixtures that use the PPA substituting part of the SBS modifier, a relatively low-temperature fracture resistance can be obtained compared with the mixture only using the SBS modifier.

Liver Damage by the Interaction of Malathion with Cimetidine in Rat

In this study the authors aimed to evaluate the oxidative stress enzymes indicative of liver damage in rats exposed to malathion （M）, subchronic form using cimetidine （C） and cimetidine plus malathion （M ＋ C）. Malathion, widely used organophosphorus insecticide worldwide, induces oxidative liver damage type; cimetidine is an antagonist of histamine H2-receptor, it has been shown to be an inhibitor of various CYP45o isoforms. Male Wistar rats weighing 200-250 g were studied, exposed to malathion orally for 3 weeks （0.15 mg/kg/day, 2 mg/kg/day, 15 mg/kg/day） and cimetidine 10 mg/kg/day. Malathion plus cimetidine affect susceptibility to oxidative stress and possibly modifies the antioxidant defense capacity directly or indirectly.

Construction of eukaryotic expression vector encoding ATP synthase lipid-binding protein-like protein gene of Sj and its expression in HeLa cells

Objective： To clone and construct the recombinant plasmid containing ATP synthase lipid-binding protein-like protein gene of Schistosomajaponicum,（SjAslp） and transfer it into mammalian cells to express the objective protein. Methods： By polymerase chain reaction （PCR） technique, SjAslp was amplified from the constructed recombinant plasmid pBCSK＋/SjAslp, and inserted into cloning vector pUCm-T. Then, SjAslp was subcloned into an eukaryotic expression vector pcDNA3.1（＋）. After identifying it by PCR, restrictive enzymes digestion and DNA sequencing, the recombinant plasmid was transfected into HeLa cells using electroporation, and the expression of the recombinant protein was analyzed by immunocytochemical assay. Results： The specific gene fragment of 558 bp was successfully amplified. The DNA vaccine of SjAslp was successfully constructed. Immunocytochemical assay showed that SjAslp was expressed in the cytoplasm of HeLa cells. Conclusion： SjAslp gene can be expressed in eukaryotic system, which lays the foundation for development of the SjAslp DNA vaccine against schitosomiasis.

Developing an Efficient Technology for Key Intermediates Production Used in Enzymatic Synthesis of Cladribine and Nelarabine

The pilot-scale process for preparing 2-amino-6-chloro-9-（2＇,3＇,5＇-tri-O-acetyl-Dq3-ribofuranosyl）-purine and 2-chloroadenosine has been developed with a total yield of the desired compounds 73% and 44.5%, respectively. These compounds are useful intermediates for enzymatic synthesis of active pharmaceutical ingredients Nelarabine and Cladribine. The starting material--commercially avaliable guanosine--was acetylated with acetic anhydride, yielding 2,3,5-tri-O-acetylguanosine, which was further deoxyhalogenated with phosphorous oxychloride in presence of tetraethylammonia chloride. Diazotization of the resulting intermediate with tert-butylnitrite leads to the corresponding ribofuranosyl-substituted 2,6-dichloropurine, which was converted to 6-chloroadenosine by reaction with methanolic ammonia.

Lowland pasture in Himalayan highland: edaphic properties and species composition

This study was carried out to investigate if on-farm cut vs. grazed pastures differed in soil fertility and species density in the temperate Himalayan highlands. Soil fertility and species relative density were measured from 30 cut and 30 grazed dairy pastures. In both types of pasture, soil pH, available phosphorus(P) and exchangeable potassium(K) were negatively correlated with pasture age and slope. In cut pasture, cocksfoot(Dactylis glomerata) and pasture age were positively correlated,whereas in grazed pasture, they were negatively correlated. In grazed pasture, unsown species and pasture age were positively correlated. Soil available P was significantly greater in cut pastures whereas soil exchangeable K was significantly greater in grazed pastures. In terms of species density, cut pasture had greater densities of cocksfoot and Italian ryegrass(Lolium multiflorum), whereas grazed pasture showed greater densities of white clover, sedge and local grass. Our study suggests that, if there are no improvements in the current method of pasture management, the cut pastures in the future are likely to have a simple pasture mixture constituting only cocksfoot and white clover(Trifolium repens).Whereas in grazed pasture, the pasture mixture is likely to be comprised of white clover and unsown species such as sedge, local grass and broadleaf weeds.

Study on in Vitro Degradation of Sutures for Decomposable Esophageal Stent

PLLA and PGLA sutures for decomposable esophageal stent were investigated in phosphate buffer solution （PBS） （pH=7.4） at 37 ℃ for a period of 8 weeks. In vitro degradation was studied by determining the change of weight loss, pH value, intrinsic viscosity, tensile strength, orientation degree, degree of crystallinity, melting point and surface morphology of the suture samples. The results showed that all properties of PLLA sutures had no obvious changes, however, the properties of PGLA sutures all changed significantly. The pH value, intrinsic viscosity, tensile strength, orientation degree and degree of crystallinity decreased gradually, and the weight loss of PGLA sutures increased with the degradation time. At 6th week, tensile strength of PGLA sutures nearly reached O, and weight loss approached to 70% at 8th week. The results of DSC showed that melting point of crystalline region of PGLA sutures substantially remained unchanged and melting heat enthalpy increased gradually during in vitro degradation, and the new ordered regions appeared in the amorphous area. The results of SEM showed that surface coating of PGLA sutures spalled initially, and then the sutures occured transverse rupture. Therefore, PGLA suture is suitable to prepare decomposable esophageal stent to expand benign esophageal stenosis or stricture, but stent prepared by PLLA suture is not appropriate for the treatment of benign esophageal stenosis because it is decomposed for more than 2 months.

SERS imaging for label-free detection of the phospholipids distribution in hybrid lipid membrane

A label-free and low-cost mapping method based on SERS imaging was reported for illustrating the distribution of phospho- lipids with similar structures in binary lipid membranes on Ag nanoparticles （Ag NPs） films. The Ag NPs films exhibited strong SERS activity and good reproducibility which were investigated with p-aminothiopbenol （p-ATP） as probe molecules. Atomic force microscope （AFM） measurement proved that compact lipid membranes formed on the Ag NPs films. Basing on the Ag NPs films, the SERS spectra of phospholipids in the mixed lipid membranes were achieved and the inherent vibration of 1,2-dimyristoyl-sn-lycero-3-phosphoglycerol, sodium salt （DMPG）, 1482 cm-1, was used to distinguish between DMPG and dimyristoylphosphatidylcholine （DMPC）. The proportions of phospholipids in the mixed lipid membranes were represented by the intensity ratio of peaks at 1482 cm-1 and 1650 cm1 （R1482/1650） simultaneously： increasing R1482/1650 indicated higher propor- tion of DMPG and lower proportion of DMPC. SERS imaging of the lipid membranes was constructed as a combination of spacial information and the semiquantitative detection of phospholipids according to R1482/1650, which showed that the charged phospholipids, DMPG, aggregated in the hybrid lipid membranes. The presented mapping strategy based on SERS imaging carried out on Ag NPs films supplied a facile, label-free and inexpensive way for potential applications in the research on the structure of the lipid membrane, such as lipid domains and rafts.

Plasma-assisted fabrication of monolayer phosphorene and its Raman characterization

There have been continuous efforts to seek novel functional two-dimensional semiconductors with high performance for future applications in nanoelectronics and optoelectronics. In this work, we introduce a successful experimental approach to fabricate monolayer phosphorene by mechanical cleavage and a subsequent Ar＊ plasma thinning process. The thickness of phosphorene is unambiguously determined by optical contrast spectra combined with atomic force microscopy （AFM）. Raman spectroscopy is used to characterize the pristine and plasma-treated samples. The Raman frequency of the A2g mode stiffens, and the intensity ratio of A2g to Alg modes shows a monotonic discrete increase with the decrease of phosphorene thickness down to a monolayer. All those phenomena can be used to identify the thickness of this novel two-dimensional semiconductor. This work on monolayer phosphorene fabrication and thickness determination will facilitate future research on phosphorene.