An embryonic cell divides again and again

The study of semiconductor nanocrystals (NCs) is a very active research field, due to the wide range of applications, related to light-emission and absorption, photodetection, solar cells, light emitting diode or tunable emitters for bio-labeling1. One area is the development of detection techniques with high spatial resolution enabled by the small size of nanomaterials. As a representative example, nanometer probes of temperature can be very useful to obtain an accurate local value of temperature, particularly in catalysis where the activity and selectivity are temperature dependent. The key is to obtain the value of the local temperature inside the solution or inside the solid at the surface of the reactants. Certain catalytic reactions require high temperatures to occur so another challenge is to build a high local temperature probe (> 373 K). In this context, semiconductor NCs are promising objects to provide this precision due to the temperature dependence of their optical properties. We present here the synthesis of different types of NCs (Cd3P22, InP@ZnS3 and CdSe@CdS4), their capacities as nanothermometers for high temperatures (>340 K) and the conditions which have to be fullfilled for accurate measurements. Different parameters such as the wavelength, the intensity, the area and the full width at half maximum of emission were studied as a function of temperature. The studied temperatures ranges from room temperature to 540 K and the comparison between the different NCs is discussed.

Where there was one cell there are two, then four, then eight,..

10/01/2018 · We’re asking for your help

Mitosis and Meiosis - Pearson - The Biology Place

Active transporters. These use the energy from the hydrolysis of ATP to transport substances against their prevailing electrochemical gradient. The classic example to which you refer is the sodium pump (also known as the Na+-K+ ATPase). This is an ATPase present in the cell membrane that transfers 3 sodium ions out of the cell in exchange for 2 potassium ions into the cell (both against their electrochemical gradient) at the expense of the consumption of one molecule of ATP. It plays a vital role in the maintenance of a low sodium and high potassium concentration within cells. It therefore is fundamental in maintaining the driving force for many sodium-dependent secondary active transporters. In direct answer to your question, the sodium pump is not the only active transporter.
There are other ATPases responsible for transporting protons, calcium
ions, as well as larger molecular weight substrates. There are also ATPases present in the organellar membranes. For example, a calcium ATPase in the sarcoplasmic reticulum of muscle cells plays a fundamental role in relaxation of muscle following calcium-dependent contraction. In one important example, the movement of the substrate down its electro-chemical gradient is used to drive the synthesis of ATP: This is the F1F0 ATPase of mitochondria.

LabBench Activity Mitosis and Meiosis

Eduard Zenkevich (born in 1945): graduated from Belarussian State University (1967, Minsk, Belarus), PhD Degree (1973), Doctor Habil. (1990). Full Professor of Physics (1998, Institute of Molecular and Atomic Physics, NAS of Belarus), Full Professor of Physics (2007, Belarussian National Technical University). Main research activities: structure/relaxation dynamics relationships in nanoscale self-assembled objects: multiporphyrin structures, pigment-protein complexes, “semiconductor quantum dot – dye molecule” nanocomposites. Visiting professor and lecturer at the Institute of Physics, University of Technology Chemnitz (1993-2016, Germany); accredited expert of Russian Corporation of Nanotechnologies “ROSNANO” (2010). The total list of publications includes more than 200 publications in refereed periodicals, two books.

Proteins are assembled from amino acids using information encoded in genes
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25/02/1993 · Original Article

TiO2 nanofibers were synthesized using electrospinning [Jamil et al Ceramics International 38 (2012) 2437–2441]. The nanofibers were polycrystalline and porous in nature having average diameter and length of ~150 nm and 200 µm, respectively. Fig. 1 (a) and (b) shows scanning electron microscope (SEM) and transmission electron microscope (TEM) image of TiO2 nanofibers, respectively. The bandgap of the nanofibers lies in optical range ˃ 3.2eV. Which showed relatively low photocatalytic degradation of toxic textile dyes (Fig. 2). To improve it photocatalytic activity we embedded Mn0.5Co0.5Fe2O4 nanoparticles into TiO2 nanofibers. Which showed improved photocatalytic activity for the degradation of toxic organic compound (Fig. 2). We are now investigating the effect of photocatalytic water splitting for hydrogen evolution. It is expected that these heterostructure nanofibers will show improve photocatalytic activity for hydrogen evolution via water splitting.

Actin is a very important protein for practically all cells

Activity Description: Students work in pairs to think about how the “instructions” of the cell are used to make proteins and form an analogy using a restaurant. Students are asked to think about the molecular players of DNA synthesis and are asked to think about their counterparts in a restaurant. To promote discussion, students complete their answers on a blank paper or 3 x 5 index card. Once finished they will pass their answers randomly in the classroom and read each other’s ideas aloud. This activity can be done in a large class.

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Heterogeneous photo-catalysis is an advanced oxidation process (PAO), which has been the subject of numerous studies and applications, particularly using the commercial oxide of TiO2 (P25, Evonik). Zinc oxide (ZnO) has often been considered a valid alternative to TiO2 due to its good opto-electronic, catalytic and photochemical characteristics along with its low cost. In order to improve the photocatalytic performance of ZnO for practical applications, various types of synthetic approaches have been developed, including, among others, the hydrothermal / solvothermal growth method, sol-gel method, ultrasonic assisted method, deposition chemistry in vapor phase, etc. with the aim of preparing ZnO particles with different sizes and morphologies. However, all of these methods require relatively severe reaction conditions such as high temperature, sophisticated techniques, high purity of gases, adjustable gas flow, expensive raw materials, etc. Therefore, it is important to find a simple and cost-effective method for the synthesis of crystalline nano-particles of ZnO. For this reason, in the present work, the ZnO has been synthesized by three different procedures: conventional aqueous precipitation method, hydrothermal method (H) and microwave assisted method (MW). In all three processes, the same material is obtained, hydrocincite [Zn5(CO3) 2(OH)6], which evolves to crystalline ZnO after calcination thermal treatments. We investigated the effect of the calcination temperature, at the same time (2 h), on the optical, textural and structural properties. Photo-catalytic studies were performed using two selected substrates, Methyl Orange and Phenol, as toxic model substrates (one colorant and the other transparent). The catalysts prepared were characterized by several techniques: DRX, SBET, FE-SEM, TEM and UV-Vis (in diffuse reflectance mode).From the results of XRD, it has been possible to establish that a minimum difference between the relative intensities of exposed faces (I100 and I002) is a crucial factor to obtain good photocatalytic properties. This minimum difference is achieved, in our cases by thermal treatments of calcination at 400ºC, 2 h. When this temperature is chosen, there is no appreciable variation between the photocatalytic activities of the oxides of zinc obtained by the three processes, and there are small differences depending on the nature of the substrate chosen, which can be attributed to the textural differences between the oxides. In any case, the obtained zinc oxides show, for each substrate, photo-catalytic activities in the UV that are superior to those presented by the widely used commercial oxide TiO2 (P25) used as reference.