Investigation of a non-explosive directional roof cutting technology for self-formed roadway

Traditional explosives have characteristics of high risk,large vibration,and poor directional fracturing.Consequently,an instantaneous expander with a single crack surface(IESCS),which is a novel nonexplosive directional rock-breaking technique,has been developed.The directional roof-cutting mechanism of the IESCS method,driven by high-pressure gas,was theoretically analyzed.Laboratory experiments and numerical simulations proved the directional slitting effect of the IESCS method to be excellent.Compared with shaped-charge blasting,the charge of IESCS was reduced by 8.9%,but the crack rate increased by 9%in field tests.After IESCS pre-splitting,the roof directionally collapsed along the cutting line,and the gangue filled the goaf.Moreover,the directional roof cutting by the IESCS could decrease roadway stress.The average pressure of hydraulic supports on the cutting side of the roof was 31%lower than that on the non-cutting side of the roof after pre-splitting.After the self-formed roadway constructed by the IESCS was stabilized,the final relative displacement of the roof and floor was 157.3 mm,meeting the required standard of the next working face.Thus,the IESCS was effectively applied to directional roof pre-splitting.The results demonstrate the promising potential of IESCS in the mining and geotechnical fields.

灵芝漆酶基因转录Cu^(2+)诱导特性及其启动子的克隆与序列分析

以Cu2+为诱导物检测了灵芝漆酶同工酶基因的转录特性,并对其启动子进行了克隆及序列分析。研究发现:灵芝漆酶基因在Cu2+的作用下表达量出现明显差异,其中以在发酵液中添加3.0 mmol.L-1Cu2+、诱导时间为6 d时,漆酶基因的mRNA表达量最高。根据GenBank中已报道的灵芝漆酶基因的序列信息,经PCR扩增获得了灵芝漆酶5′端长879bp的基因特异序列,进而通过self-formed adaptor PCR(SEFA-PCR)方法,扩增得到灵芝漆酶基因起始密码子上游长832bp的启动子序列。分析表明,该启动子区域除分布有TATA-box、CAAT-box及GC-box等基本的转录起始元件外,还存在多个潜在的顺式作用元件序列位点,包括4个MRE元件、4个STRE元件、11个HSE元件和5个氮因子结合位点等。

Lithium bis(oxalate)borate crosslinked polymer electrolytes for high-performance lithium batteries

Solid electrolytes play a vital role in solid-state Li secondary batteries,which are promising high-energy storage devices for new-generation electric vehicles.Nevertheless,obtaining a suitable solid electrolyte by a simple and residue-free preparation process,resulting in a stable interface between electrolyte and electrode,is still a great challenge for practical applications.Herein,we report a self-crosslinked polymer electrolyte(SCPE)for high-performance lithium batteries,prepared by a one-step method based on 3-methoxysilyl-terminated polypropylene glycol(SPPG,a liquid oligomer).It is worth noting that lithium bis(oxalate)borate(Li BOB)can react with SPPG to form a crosslinked structure via a curing reaction.This self-formed polymer electrolyte exhibits excellent properties,including high roomtemperature ionic conductivity(2.6×10^(-4) S cm^(-1)),wide electrochemical window(4.7 V),and high Li ion transference number(0.65).The excellent cycling stability(500 cycles,83%)further highlights the improved interfacial stability after the in situ formation of SCPE on the electrode surface.Moreover,this self-formation strategy enhances the safety of the battery under mechanical deformation.Therefore,the present self-crosslinked polymer electrolyte shows great potential for applications in high-performance lithium batteries.

PREPARATION OF CAULIFLOWER-LIKE PMMA PARTICLES AND THEIR FORMATION MECHANISM

A simple technique for preparing cauliflower-like PMMA particles by a self-formation method is proposed. PMMA particles can be obtained with tunable surface morphology by varying the polymerization time. Experimental results show that the formation of these cauliflower-like particles can be attributed to the special particle growth mechanism in the self-formation method.

Direct synthesis of tin spheres/nitrogen-doped porous carbon composite by self-formed template method for enhanced lithium storage

To inhibit the agglomeration of tin-based nanomaterials and simplify the complicated synthesis process,a facile and eco-friendly self-formed template method is reported to synthesize tin submicron spheres dispersed in nitrogen-doped porous carbon(Sn/NPC)by pyrolysis of a mixture of disodium stannous citrate and urea.The vital point of this strategy is the formation of Na_(2)CO_(3)templates during pyrolysis.This self-formed Na_(2)CO_(3)acts as porous templates to support the formation of NPC.The obtained NPC provides good electronic conductivity,ample defects,and more active sites.Serving as anode for Li-ion batteries,the Sn/NPC electrode obtains a stable discharge capacity of 674.1 mAh/g after 150 cycles at 0.1 A/g.Especially,a high discharge capacity of 331.2 mAh/g can be achieved after 1100 cycles at 3 A/g.Additionally,a full cell coupled with LiCoO_(2)as cathode yields a discharge capacity of 524.8 mAh/g after 150 cycles at 0.1 A/g.In-situ XRD is implemented to investigate the alloying/dealloying reaction mechanisms.Density functional theory calculation ulteriorly explicates that NPC heightens intrinsic electronic conductivity,and NPC especially pyrrolic-N and pyridinic-N doping facilitates the Li-adsorption ability.Climbing image nudged elastic band method reveals low Li~+diffusion energy barrier in presence of N atoms,which accounts for the terrific electrochemical properties of Sn/NPC electrode.

Fabrication of ultrafine ZnFe2O4 nanoparticles for efficient photocatalytic reduction CO2 under visible light illumination

A one-pot, solvent-thermal process was used to create the ultrafine ZnFe2O4nanoparticles photocatalyst.During the solvent-thermal process, the in situ self-forming NaCl not only served as a "cage" to confine the ion diffusion, but also acted as a microreactor for nanocrystallite growth. An average particle size of ～10 nm and a high-specific surface area of～112.9 m2/g were observed for the ultrafine ZnFe2O4nanoparticles Owing to the synergistic effect of ultrafine particle size, the full utilization of the visible light region and high conduction band(CB) position, ultrafine ZnFe2O4photocatalyst displayed an efficient photocatalytic CO2reduction under visible light illumination. Besides, the ultrafine ZnFe2O4photocatalyst showed high production selectivity for CH3CHO and C2H5OH generation in aqueous CO2/NaHCO3solution. This work may provide a new idea for the synthesis of new high-efficiency photocatalysts.