Determination of interfacial tension and viscosity under dripping flow in a step T-junction microdevice

Microfluidic approaches for the determination of interfacial tension and viscosity of liquid-liquid systems still face some challenges. One of them is liquid-liquid systems with low interfacial and high viscosity, because dripping flow in normal microdevices can't be easily realized for the systems. In this work, we designed a capillary embedded step T-junction microdevice to develop a modified microfluidic approach to determine the interfacial tension of several systems, specially, for the systems with low interfacial tension and high viscosity. This method combines a classical T-junction geometry with a step to strengthen the shear force further to form monodispersed water/oil (w/o) or aqueous two-phase (ATP) droplet under dripping flow. For systems with low interfacial tension and high viscosity, the operating range for dripping flow is relative narrow whereas a wider dripping flow operating range can be realized in this step T-junction microdevice when the capillary number of the continuous phase is in the range of 0.01 to 0.7. Additionally, the viscosity of the continuous phase was also measured in the same microdevice. Several different systems with an interfacial tension from 1.0 to 8.0 mN·m^-1 and a viscosity from 0.9 to 10 mPa·s were measured accurately. The experimental results are in good agreement with the data obtained from a commercial interfacial tensiometer and a spinning digital viscometer. This work could extend the application of microfluidic flows.     

Fabrication of effective mesoporous silica materials for emergency hemostasis application

Silicon - Uncontrolled bleeding is an important cause of traumatic death in wartime and peacetime. Despite the significant advances in hemostatic research, it is still challenging to develop safer...     

Efficient synthesis of tyrosol from L-tyrosine via heterologous Ehrlich pathway in Escherichia coli

For the efficient conversion of L-tyrosine(L-Tyr) to tyrosol, which is an aromatic compound widely used in the pharmaceutical and chemical industries, a novel four-enzyme cascade pathway based on the Ehrlich pathway of Saccharomyces cerevisiae was designed and reconstructed in Escherichia coli. Then,the expression levels of the relevant enzymes were coordinated using a modular approach and gene duplication after the identification of the pyruvate decarboxylase from Candida tropicalis(Ct PDC) as ...     

低温甲醇洗碳捕集改进与优化

减少CO₂排放对环境保护尤为重要。传统低温甲醇洗工艺中大量被贫甲醇吸收的CO₂由于被N₂稀释而直接作为尾气排放进大气中。为探究工艺改进空间,本研究基于Aspen Plus对一传统低温甲醇洗工艺进行模拟,物性方法选用CPA (Cubic-Plus-Association)模型并对该模型的二元交互系数进行回归修正,后与实际数据进行对比确保模型的准确性。对于工艺改进,首先在传统低温甲醇洗工艺的基础上采用四级增压热闪蒸和降压闪蒸相结合的方式进行一次改进以用于CO₂捕集,并对相关参数进行优化以进一步降低系统公用工程消耗。结果显示,虽然一次改进工艺的CO₂产量是传统工艺的3.3倍,但系统能量消耗增加了2.12%,系统(火用)消耗增加了17.81%。接着,在一次改进工艺的基础上采用“半贫液+透平回收”相结合技术进一步进行节能改进,二次改进工艺的CO₂产量不仅与一次改进工艺相当,系统能量消耗和系统(火用)消耗相比于传统低温甲醇洗工艺也分别降低了17.16%和5.85%。     

高温抗烧结吸附剂对SeO2捕集性能

使用气固瞬时反应装置在700~1100℃下对不同氧化物（氧化镁、氧化铁、氧化铝、氧化钙）的硒捕集性能进行研究,确定吸附产物性质。基于此选取相应的典型矿物及双组分抗烧结吸附剂改善硒高温吸附能力。结果表明：900℃前氧化钙捕集效果最好,但1100℃时其吸附量迅速降低到167.59μg/g;γ-氧化铝在高温下捕集效果较好,1100℃时吸附量可达415.04μg/g,这与其优异的孔隙结构有关。钙基矿物方解石因其具有一定的抗烧结能力和发达的孔隙结构,表现出更好的高温捕集能力,1100℃时吸附量可提高到1064.97μg/g。双组分吸附剂高温捕集能力展现出不同程度的提高。钙-铝基吸附剂高温捕集性能提高相对较小;而钙-硅基吸附剂在高温下效果远高于单组分吸附剂,与氧化钙相比,1100℃时可提高1787.21μg/g。     

原料油汽化特性对催化裂化反应结焦过程影响的CFD模拟

为考察原料油汽化特性影响,在一套百万吨级工业FCC提升管中,基于多相欧拉模型耦合EMMS曳力和传质、油滴汽化和十二集总反应动力学模型,采用三维CFD模拟研究气液固三相流动、汽化、反应、结焦的复杂过程,新开发结焦预测模型定量预测结焦状况,对比研究不同原料油雾化液滴粒径和起始汽化温度下各相和反应组分浓度场、温度场分布和结焦程度。结果表明,模拟方法可较准确预测汽化、反应生焦和结焦过程,不同雾化液滴粒径和起始汽化温度通过流场分布和汽化快慢影响液相油滴汽化率和反应转化率;合适液滴粒径(60 μm)和起始汽化温度(654 K)可提升轻油、汽油、液化石油气目标产品收率并改善结焦程度。     

Co?N graphene encapsulated cobalt catalyst for H2O2 decomposition under acidic conditions

Hydrogen peroxide (H₂O₂) has been listed as one of the 100 most important chemicals in the world. However, huge amount of residual H₂O₂ is hard to timely decomposed into O₂ and H₂O under acidic condition, easily resulting in explosion hazard. Here, we reported a core–shell structure catalyst, that is graphene with Co N structure encapsulated Co nanoparticles. Co N graphene shell serves as the active site for the H₂O₂ decomposition, and Co core further enhance this decomposition. Benefiting from it, the H₂O₂ decomposition were close to 100% after 6 cycles without pH adjustment, which increased 6 orders of magnitude compared with no catalyst. At the same time, the O₂ generation reached 99.67% in 2 h with little metal leaching, and ·OH has been greatly inhibited to only 0.08%. This work can cleanly remove H₂O₂ with little deep oxidation and protect the process of H₂O₂ utilization to achieve a safer world.     

Dual‐bed catalyst system for the direct synthesis of high density aviation fuel with cyclopentanone from lignocellulose

In this article, we demonstrated an integrated process for the direct production of tri(cyclopentane) with cyclopentanone which can be obtained from lignocellulose. The reaction was carried out in a dual‐bed continuous flow reactor. In the first bed, cyclopentanone was selectively converted to 2,5‐dicyclopentylcyclopentanol over the Pd‐MgAl‐HT (hydrotalcite) catalyst. Under solvent‐free and mild conditions (443 K, 0.1 MPa H₂), high carbon yield (81.2%) of 2,5‐dicyclopentylcyclopentanol was achieved. Subsequently, the 2,5‐dicyclopentylcyclopentanol was further hydrodeoxygenated to tri(cyclopentane) in the second bed. Among the investigated catalysts, the Ni‐Hβ‐DP prepared by deposition‐precipitation (DP) method exhibited the highest activity for the hydrodeoxygenation step. By using Pd‐MgAl‐HT as the first bed catalyst and Ni‐Hβ‐DP as the second bed catalyst, tri(cyclopentane) was directly produced at high carbon yield (80.0%) with cyclopentanone as feedstock. This polycycloalkane has high density (0.91 kg/L) and can be used as additive to improve the density and volumetric heating value of bio‐jet fuel. © 2016 American Institute of Chemical Engineers AIChE J, 62: 2754–2761, 2016     

MicroRNA-155 Mediates Augmented CD40 Expression in Bone Marrow Derived Plasmacytoid Dendritic Cells in Symptomatic Lupus-Prone NZB/W F1 Mice

Systemic lupus erythematosus (SLE) is a chronic multi-organ autoimmune disease characterized by hyperactivated immune responses to self-antigens and persistent systemic inflammation. Previously, we reported abnormalities in circulating and bone marrow (BM)-derived plasmacytoid dendritic cells (pDCs) from SLE patients. Here, we aim to seek for potential regulators that mediate functional aberrations of pDCs in SLE. BM-derived pDCs from NZB/W F1 mice before and after the disease onset were compared for toll-like receptor (TLR) induced responses and microRNA profile changes. While pDCs derived from symptomatic mice were phenotypically comparable to pre-symptomatic ones, functionally they exhibited hypersensitivity to TLR7 but not TLR9 stimulation, as represented by the elevated upregulation of CD40, CD86 and MHC class II molecules upon R837 stimulation. Upregulated induction of miR-155 in symptomatic pDCs following TLR7 stimulation was observed. Transfection of miR-155 mimics in pre-symptomatic pDCs induced an augmented expression of Cd40, which is consistent with the increased CD40 expression in symptomatic pDCs. Overall, our results provide evidence for miR-155-mediated regulation in pDC functional abnormalities in SLE. Findings from this study contribute to a better understanding of SLE pathogenesis and ignite future interests in evaluating the molecular regulation in autoimmunity.     

Pd-Pt-Ce/Al_2O_3催化剂在VOC净化处理中的催化性能

采用浸渍法制备Pd-Pt-Ce/Al_2O_3催化剂,考察贵金属Pd和Pt负载量、助剂种类及负载量、空速对催化甲苯燃烧活性的影响。结果表明,适宜的贵金属负载量和助剂可极大提高Pd-Pt/Al_2O_3催化剂活性,当Pd和Pt质量分数分别为0.05%和0.005%、助剂Ce质量分数为1%时,Pd-Pt-Ce/Al_2O_3催化剂在低温条件下表现出较好的催化性能。空速对催化剂的催化活性影响较为明显,适宜的空速低于20 000 h-1。