Separation,Purification and Characterization of Three Endo-polygalacturonases from a Newly Isolated Penicillum oxalicum

Three endo-polygalacturonases (endoPGs) from a newly isolated Penicillum oxalicum (CGMCC 0907) capable of utilizing waste biomass as growth substrate were separated and purified to homogeneity by ultra-filtration, affinity adsorption chromatography, CM-cellulose column chromatography, and Sephadex G-100 gel filtration chromatography with the overall yield of 64.5% from the crude enzyme. The specific activities and recovery rates of endoPG-1, endoPG-2 and endoPG-3 were 1120 U/mg and 21.6%, 1350 U/mg and 25.9%, and 1560 U/mg and 17.0%, respectively. The three purified endoPGs had a close molecular weight to 41 kDa as estimated by SDS-PAGE. The optimum temperature and pH for the function of them were 65℃ and 5.0, 55℃ and 5.0, 50℃ and 5.5, respectively. Their pI and Km values were 5.9 and 0.78 mg/mL, 6.0 and 1.2 mg/mL, and 6.1 and 2.0 mg/mL, respectively.     

Influence of different modified β zeolite on skeletal isomerization of n-hexene in the presence of hydrogen

Zeolite β was modified via treating with oxalic acid and doping with magnesium, and the influence of different modified zeolite β on skeletal isomerization of n-hexene in the presence of hydrogen was investigated. Moreover, parent β and modified β were characterized by XRD, N₂ physisorption, IR, NH₃–TPD, ²⁷Al MAS NMR and ²⁹Si MAS NMR, respectively. The results indicated, compared with parent β, β treated by oxalic acid was found that non-framework aluminum was removed effectively, and surface aluminum and framework aluminum were eliminated partly, which resulted in considerable decrease in the amount of acid sites. In contrast, the introduction of magnesium has little effect on crystalline structure of β, but it can reduce the amount of strong Brönsted acid sites. Noticeably, when β was modified by the combination of oxalic acid treatment and Mg dope, it can not only remove non-framework aluminum and reduce the amount of acid sites, but also facilitate the stability of crystalline structure of β and further eliminate strong Brönsted acid sites due to the introduction of Mg. The evaluation results of skeletal isomerization of n-hexene in the presence of hydrogen showed that, compared with parent β, β modified by the combination of oxalic acid treatment and Mg dope exhibits better activity and stability.     

氮压机节能降噪新方法

针对氮气供大于求的矛盾,采取减小氮压机设定最大电流以降低其运行负荷和对低压氮压机实施节能双式控制的措施,减少氮气放空量,降低放空噪声,延长低压氮压机的卸载运行时间,取得了节能降噪的效果。简介氮气供应系统流程和控制,详细分析优化措施、节能双式控制模式以及相关参数的设定值。     

Efficient delivery of antitumor drug to the nuclei of tumor cells by amphiphilic biodegradable poly(L-aspartic acid-co-lactic acid)/DPPE co-polymer nanoparticles

The use of biodegradable polymeric nanoparticles (NPs) for controlled drug delivery has shown significant therapeutic potential. Polyaspartic acid and polylactic acid are the most intensively studied biodegradable polymers. In the present study, novel amphiphilic biodegradable co-polymer NPs, poly(L-aspartic acid-co-lactic acid) with 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE) (poly(AA-co-LA)/DPPE) is synthesized and subsequently used to encapsulate an antitumor drug doxorubicin (DOX). The formulation parameters of the NPs are optimized to improve encapsulation efficiency. The resulting drug-loaded NPs possess better size homogeneity (polydispersity) and exhibit pH-responsive drug release profiles. Cellular viability assays indicate that the poly(AA-co-LA)/DPPE NPs did not induce cell death, whereas doxorubicin encapsulated NPs were cytotoxic to various types of tumor cells. In addition, the free NPs could not enter the cell nuclei after internalized in tumor cells. The DOX-loaded NPs exhibit efficient intracellular delivery in tumor cells with co-localization in lysosome and delay entering into the nucleus, which suggests a time- and pH-dependent drug release profile within cells. When applied to deliver chemotherapeutics to a mouse xenograft model of human lung adenocarcinoma, DOX-loaded NPs have a comparable antitumor activity with free DOX, and greatly reduce systemic toxicity and mortality. The delivery of cytotoxic drugs directly to the nucleus specifically within tumor cells is of great interest. These results demonstrate the feasibility of the application of the amphiphilic polyaspartic acid derivative, poly(AA-co-LA)/DPPE, as a nanocarrier for cell nuclear delivery of potent antitumor drugs.     

DNA-wrapped carbon nanotubes as sensitive electrochemical labels in controlled-assembly-mediated signal transduction for the detection of sequence-specific DNA

A novel electrochemical strategy that uses DNA-wrapped carbon nanotubes (CNTs) as electrochemical labels is developed for sensitive and selective detection of sequence-specific DNA. The presence of target DNA mediates the formation of a sandwiched complex between the DNA-wrapped CNT and a hairpin DNA capture probe immobilized on magnetic beads. This allows target-selective collection of the CNT labels by magnetic separation and transfer on the electrode surface modified with an insulating self-assembled monolayer (SAM). After treatment with N,N-dimethylformamide, the collected sandwiched complex releases the bare CNTs and facilitates the removal of magnetic beads from the electrode surface. The bare CNTs can then assemble on the SAM-modified electrode surface and mediate efficient electron transfer between the electrode and the electroactive species in the solution with a strong current signal generated. The results indicate that the developed strategy shows a sensitive response to target DNA with a desirable signal gain and a low detection limit of 0.9 pM. This strategy is also demonstrated to provide excellent differentiation of single-base mismatch in target DNA. It is expected that this electrochemical strategy may hold great potential as a novel platform for clinical diagnostics and genetic analysis.     

Nanoparticle-induced exosomes target antigen-presenting cells to initiate Th1-type immune activation

The mechanisms associated with the induction of systemic immune responses by nanoparticles are not fully understood, but their elucidation is critical to address safety issues associated with the broader medical application of nanotechnology. In this study, a key role of nanoparticle-induced exosomes (extracellularly secreted membrane vesicles) as signaling mediators in the induction of T helper cell type 1 (Th1) immune activation is demonstrated. In vivo exposure to magnetic iron oxide nanoparticles (MIONs) results in significant exosome generation in the alveolar region of Balb/c mice. These act as a source of nanoparticle-induced, membrane-bound antigen/signaling cargo, which transfer their components to antigen-presenting cells (APCs) in the reticuloendothelial system. Through exosome-initiated signals, immature dendritic cells (iDCs) undergo maturation and differentiation to the DC1 subtype, while macrophages go through classical activation and differentiation to the M1 subtype. Simultaneously, iDCs and macrophages release various Th1 cytokines (including interleukin-12 and tumor necrosis factor α) driving T-cell activation and differentiation. Activated APCs (especially DC1 and M1 subtypes) consequently prime T-cell differentiation towards a Th1 subtype, thereby resulting in an orchestrated Th1-type immune response. Th1-polarized immune activation is associated with delayed-type hypersensitivity, which might underlie the long-term inflammatory effects frequently associated with nanoparticle exposure. These studies suggest that nanoparticle-induced exosomes provoke the immune activation and inflammatory responses that can accompany nanoparticle exposure.     

解读近代中西合璧式建筑——以天长市图书馆楼为例

天长市图书馆（时称“天长县图书馆”）始建于1921年,是安徽省近代历史上较早成立的公共图书馆,是安徽省最早的县级图书馆,也是安徽省现存不多的民国公共建筑之一,是中西合璧式折衷主义风格建筑的代表。文章是在作者近期参与天长市图书馆楼建筑测绘工作的基础上,对其建筑技术、风格及其成因进行的阶段性研究。     

青岛海湾大桥大直径旋挖钻孔灌注桩施工技术

青岛海湾大桥大沽河航道桥采用φ2.5m桩基,为目前国内海上直径最大的群桩基础.根据桥位处地质条件复杂、桩径大、海上施工条件复杂等情况,其海上钻孔灌注桩均采取搭设工作平台进行施工.介绍了海上钻孔平台搭设、旋挖机钻进及泥浆护壁成孔施工工艺.较之传统的回转钻机和冲击反循环钻机钻进,旋挖钻进工艺提高了成孔效率和成孔质量,同时拓宽了旋挖钻机的应用领域.     

土壤源热泵运行能耗动态模拟分析

分析了空调系统相关设备动态模型的建立方法。结合实例,评价了土壤源热泵的能耗情况。能耗主要源自地埋管换热器循环泵,地下水位对土壤源热泵的能耗影响较大。     

干线公路沥青路面就地冷再生技术与机械施工

沥青路面就地冷再生技术的推广使用,为干线公路旧路改造提供了一条新途径,合理的机械配置、科学的施工方法与工艺流程是养护大修工程质量的重要保证,必须关注施工过程中的有关注意事项。