Pig kidney phosphofructokinase. Purification to homogeneity and qualitative basic characterization.

Phosphofructokinase has been purified from pig kidney by extraction with phosphate buffer at pH 8, followed by alcohol treatment, affinity chromatography on matrix-bound Cibacron blue F3G-A, and gel chromatography on Sepharose 6B. Using sodium dodecyl sulphate electrophoresis the enzyme was found to be homogeneous and to have a specific activity of about 80 units/mg protein. Like other phosphofructokinases, at pH 7.0 the enzyme exhibits a sigmoidal dependence in its activity on the fructose 6-phosphate concentration and is strongly inhibited by ATP. The degree of citrate inhibition is influenced by the concentration of the two substrates. ATP strengthens and fructose 6-phosphate relieves the inhibition by citrate. AMP and cAMP are able to overcome the ATP inhibition. The ADP activation curve is biphasic. The molecular weight of the subunit of pig kidney phosphofructokinase was determined to be 88 000 by means of sodium dodecyl sulphate electrophoresis.     

Neurogenesis of bone marrow-derived mesenchymal stem cells onto β-mercaptoethanol-loaded PLGA film

Bone marrow-derived mesenchymal stem cells (BMSCs) are of particular interest in the field of tissue engineering because of their potential to differentiate into osteoblasts, chondrocytes, and neuronal cells. In order to promote the differentiation of BMSCs into specific cell types, appropriate scaffold biomaterials and bioactive molecules that can support the differentiation of BMSCs into specific cell types are needed. We hypothesized that β-mercaptoethanol (BME), which has been reported to induce the differentiation of BMSCs into neural-like cells, promotes BMSCs to differentiate into neural-like cells when BME is added to polymeric scaffolds containing the BMSCs. We fabricated biocompatible film shaped scaffolds composed of poly(lacti-co-glycolic) acid (PLGA) and various concentrations of BME to confirm that BME-promoted differentiation of BMSCs is concentration-dependent. Cell proliferation increased as the BME concentration in the films increased at the early stage, and the proliferation rate remained similar on the PLGA films for 3 weeks following the BMSC seeding. The expression of neuronal markers in differentiated BMSCs was assessed by RT-PCR. At 2- and 3-week time-points, mRNA expression of neurofilament and neuron specific enolase was significantly increased in PLGA/BME films containing 400 μM BME compared to PLGA films. Thus, we have identified BMSC-seeded PLGA/BME films with 200 μM and 400 μM BME as potentially useful candidates for neural tissue engineering applications by promoting BMSC proliferation and differentiation towards neural-like cells.     

Multi-layered Graphene Silica-Based Tunable Absorber for Infrared Wavelength Based on Circuit Theory Approach

Graphene can be utilized as a tunable material for a wide range of infrared wavelength regions due to its tunable conductivity property. In this paper, we use Y-shaped silver material resonator placed over the top of multiple graphene silica-layered structures to realize the perfect absorption over the infrared wavelength region. We propose four different designs by placing the graphene sheet over silica. The absorption and reflectance performance of the structures have been explored for 1500- to 1600-nm wavelength range. The proposed design also explores the absorption tunability of the structure for the different values of graphene chemical potential. We have reported the negative impedance for the perfect absorption for proposed metamaterial absorber structures. All the metamaterial absorbers have reported 99% of its absorption peaks in the infrared wavelength region. These designs can be used as a tunable absorber for narrowband and wideband applications. The proposed designs will become the basic building block of large photonics design which will be applicable for polariser, sensor, and solar applications.

     

微花蛛毛苣苔在中国云南的发现及其补充描述

中越边境喀斯特地区是全球生物多样性热点地区,也是生物多样性保护的关键区域,近年来在该地区发现了多个蛛毛苣苔属植物的新种。微花蛛毛苣苔于2001年在越南北部喀斯特地区首次采集到标本,直到2018年才被发表出来,由于发表时仅基于一号花发育未成熟的标本,所以该物种的诸多形态特征仍不清楚。作者开展中越边境喀斯特地区植物多样性调查时,在我国云南东南部发现了微花蛛毛苣苔,并采集到花发育成熟的植株,对其进行了解剖观察和测量,现对该物种进行补充描述,并提供墨线图和野外生态照片以资辨认。微花蛛毛苣苔与腺花蛛毛苣苔在光滑无毛而反折的花萼以及被腺毛的花冠等形态上最相似,但不同之处在于微花蛛毛苣苔的叶上面幼时被褐色蛛丝状绵毛,后变近无毛,花序顶生,花冠长9～12 mm,蒴果直,不旋扭,长1.2～2.8 cm。微花蛛毛苣苔在滇东南的发现,说明中国南部喀斯特地区和越南北部喀斯特地区构成了一个完整的植物区系地理单元。     

苦苣苔科凹柱苣苔属在越南的发现及水晶凹柱苣苔的补充描述

中越边境喀斯特地区有着异乎寻常的植物多样性,已经成为全球生物多样性研究和保护的热点区域,近年来在该区发现了多个苦苣苔科植物的新种或新属。凹柱苣苔属是2010年才被建立的新属,该属的花与叶相比,花较大,叶相对较小,叶片边缘稍外卷,花序仅单花,柱头盘状或凹坑状,蒴果长椭球形而有别于苦苣苔科的其他属。凹柱苣苔属为喀斯特专性植物,目前仅包括分布于黔西南的凹柱苣苔和分布于滇东南的水晶凹柱苣苔两个物种。作者在开展中越边境喀斯特地区植物多样性调查时,在越南北部的河江省发现了水晶凹柱苣苔,基于该新发现居群的植物标本,对其进行了补充描述,确认其花期为11月—12月,并对该物种濒危状况进行了重新评估,同时提供了野外生态照片以资辨认。目前,越南已记录苦苣苔科植物32属150余种,凹柱苣苔属在越南北部的发现,不仅丰富了该国苦苣苔科植物的多样性,再一次充分证明了中越边境喀斯特地区是一个完整的植物区系地理单元,而且为稀有的水晶凹柱苣苔提供了更加丰富的野外本底资料,对其将来的深入研究和保护具有重要的生物地理学和保护生物学意义。     

Aerobryum brevicuspis S.He (Brachytheciaceae), a new species from northern Vietnam

A new species of Aerobryum Dozy & Molk. (Brachytheciaceae), A. brevicuspis S.He from Lao Cai Province, northern Vietnam is described and illustrated. The new species resembles epiphytic A. speciosum Dozy & Molk. in the presence of pendent, sparsely branched stems, similar shape of leaves and areolation, but differs by its apiculate to cuspidate leaf apices, a single, faint or sometimes double costae in branch leaves, rather differentiated alar cells, the presence of a central strand in the stems, and numerous clustered axillary hairs that are often 5-8(-10) cells long.     

Transition from Diffusion‐Controlled Intercalation into Extrinsically Pseudocapacitive Charge Storage of MoS2 by Nanoscale Heterostructuring

2D nanomaterials have been found to show surface‐dominant phenomena and understanding this behavior is crucial for establishing a relationship between a material's structure and its properties. Here, the transition of molybdenum disulfide (MoS₂) from a diffusion‐controlled intercalation to an emergent surface redox capacitive behavior is demonstrated. The ultrafast pseudocapacitive behavior of MoS₂ becomes more prominent when the layered MoS₂ is downscaled into nanometric sheets and hybridized with reduced graphene oxide (RGO). This extrinsic behavior of the 2D hybrid is promoted by the fast Faradaic charge‐transfer kinetics at the interface. The heterostructure of the 2D hybrid, as observed via high‐angle annular dark field–scanning transmission electron microscopy and Raman mapping, with a 1T MoS₂ phase at the interface and a 2H phase in the bulk is associated with the synergizing capacitive performance. This 1T phase is stabilized by the interactions with the RGO. These results provide fundamental insights into the surface effects of 2D hetero‐nanosheets on emergent electrochemical properties.