Magnetosome vesicles are present before magnetite formation, and MamA is required for their activation

Bacterial magnetosomes are intracellular compartments that house highly ordered magnetite crystals. By using Magnetospirillum sp. AMB-1 as a model system, we show that magnetosome vesicles exist in the absence of magnetite, biomineralization of magnetite proceeds simultaneously in multiple vesicles, and biomineralization proceeds from the same location in each vesicle. The magnetosome-associated protein, MamA, is required for the formation of functional magnetosome vesicles and displays a dynamic subcellular localization throughout the growth cycle of magnetotactic bacteria. Together, these results suggest that the magnetosome precisely coordinates magnetite biomineralization and can serve as a model system for the study of organelle biogenesis in noneukaryotic cells

A Multi Phase Transformation System Using a Special Transformer Connection

This paper proposes a novel transformer connection scheme to convert the three phase grid supply to a five-phase fixed voltage and fixed frequency supply. The output transformer connection outputs five phases can be used in applications requiring a five-phase supply. Multi-phase motor drives have been studied from more than thirty years. The interest has grown so that some international power electronic conferences have hosted sessions on the multi-phase motor drives. Generally, multi-phase machines drive has many advantages over conventional three-phase drive such as high power handling capability by dividing the required power between multiple phases, reduced torque pulsations and higher reliability. Three phase drive, the loss of stator phase does not prevent the machine from starting and running. The main advantages of multi-phase systems are reduced rotor harmonic currents, increased torque per ampere for the same volume machine, reduced stator copper losses. The main application areas of multiphase induction motor drives are ship propulsion, traction (including electric and hybrid electric vehicles) and the concept of more-electric aircraft. A difference between Three-Phase supply and Five-Phase supply. Other suitable applications are locomotive traction aerospace and high power applications. Presently the grid power available is only limited to three-phase so the supply to multi-phase motors is invariably given from power electronic converters

Security Assessment for Zenbo Robot Using Drozer and mobSF Frameworks

These days, almost everyone has been entirely relying on mobile devices and mobile related applications running on Android Operating Systems, the most used Mobile Operating System in the world with the largest market share. These Mobile devices and applications can become an information goldmine for hackers and are considered one of the significant concerns mobile users face who stand a chance of being victimized during data breach from hackers due to lapse in information security and controls. Such challenge can be put to bare through systematic digital forensic analysis through penetration testing for a humanoid robot like Zenbo, which run Android OS and related application, to help identify associated security vulnerabilities and develop controls required to improve security using popular penetration testing tools such as Drozer, Mobile Application Security framework (mobSF), and AndroBugs with the help of Santoku Linux distribution

Generalized Sagnac Effect

Experiments were conducted to study light propagation in a light waveguide loop consisting of linearly and circularly moving segments. We found that any segment of the loop contributes to the total phase difference between two counterpropagating light beams in the loop. The contribution is proportional to a product of the moving velocity v and the projection of the segment length Deltal on the moving direction, Deltaphi=4pivDeltal/clambda. It is independent of the type of motion and the refractive index of waveguides. The finding includes the Sagnac effect of rotation as a special case and suggests a new fiber optic sensor for measuring linear motion with nanoscale sensitivity.Comment: 3 pages (including 3 figures

The Pyrococcus furiosus ironome is dominated by [Fe4_{4}S4_{4}]2+^{2+} clusters or thioferrate-like iron depending on the availability of elemental sulfur

Pyrococcus furiosus is a hyperthermophilic anaerobic archaeon whose metabolism depends on whether elemental sulfur is (+S$^{0}$) or is not (-S$^{0}$) included in growth medium. Under +S$^{0}$ conditions, expression of respiratory hydrogenase declines while respiratory membrane-bound sulfane reductase and the putative iron-storage protein IssA increase. Our objective was to investigate the iron content of WT and ΔIssA cells under these growth conditions using Mössbauer spectroscopy. WT-S$^{0}$ cells contained ∼1 mM Fe, with ∼85% present as two spectroscopically distinct forms of S = 0 [Fe$_{4}$S$_{4}$]$^{2+}$ clusters; the remainder was mainly high-spin Fe$^{II}$. WT+S$^{0}$ cells contained 5 to 9 mM Fe, with 75 to 90% present as magnetically ordered thioferrate-like (TFL) iron nanoparticles. TFL iron was similar to chemically defined thioferrates; both consisted of Fe$^{III}$ ions coordinated by an S$_{4}$ environment, and both exhibited strong coupling between particles causing high applied fields to have little spectral effect. At high temperatures with magnetic hyperfine interactions abolished, TFL iron exhibited two doublets overlapping those of [Fe$_{4}$S$_{4}$]$^{2+}$ clusters in -S$^{0}$ cells. This coincidence arose because of similar coordination environments of TFL iron and cluster iron. The TFL structure was more heterogeneous in the presence of IssA. Presented data suggest that IssA may coordinate insoluble iron sulfides as TFL iron, formed as a byproduct of anaerobic sulfur respiration under high iron conditions, which thereby reduces its toxicity to the cell. This was the first Mössbauer characterization of the ironome of an archaeon, and it illustrates differences relative to the iron content of better-studied bacteria such as Escherichia coli

Truncated Hexa-Octahedral Magnetite Crystals in Martian Meteorite ALH84001: Evidence of Biogenic Activity on Early Mars

The landmark paper by McKay et al. [1] cited four lines of evidence associated with the Martian meteorite ALH84001 to support the hypothesis that life existed on Mars approximately 4 Ga ago. Now, more than five years later, attention has focused on the ALH84001 magnetite grains embedded within carbonate globules in the ALH84001 meteorite. We have suggested that up to approx.25% of the ALH84001 magnetite crystals are products of biological activity [e.g., 2]. The remaining magnetites lack sufficient characteristics to constrain their origin. The papers of Thomas Keprta et al. were criticized arguing that the three dimensional structure of ALH84001 magnetite crystals can only be unambiguously determined using electron tomographic techniques. Clemett et al. [3] confirmed that magnetites produced by magnetotactic bacteria strain MV-I display a truncated hexa-octahedral geometry using electron tomography and validated the use of the multi-tilt classical transmission microscopy technique used by [2]. Recently the geometry of the purported martian biogenic magnetites was shown be identical to that for MV-1 magnetites using electron tomography [6]

I – V characterization of vacuum deposited zinc selenide – silicon hetero junction

841-846Zinc selenide (ZnSe) thin films were grown on silicon (Si) wafer by thermal evaporation and the hetero-structure was subjected to annealing at various temperatures. X-ray diffractogram recorded for various samples were analysed to extract the structural information including crystallite size, strain and dislocation density. ZnSe films exhibited cubic structure with (111) orientation and the crystallite size has increased from about 21 nm to 43 nm upon annealing at 673 K. Annealing at temperature above this has degraded the films. I – V characterization has shown nonlinear relation and affected by post deposition annealing. Thermionic emission and Cheung models were applied to obtain various parameters that assess the performance of hetero-structured devices. Minimum ideality factor was observed (n = 1.75 from Cheung Model) for as deposited system and it increased after annealing. Analysis has proven that series resistance increases after annealing under air ambience

The relevance of nanoscale biological fragments for ice nucleation in clouds

Most studies of the role of biological entities as atmospheric ice-nucleating particles have focused on relatively rare supermicron particles such as bacterial cells, fungal spores and pollen grains. However, it is not clear that there are sufficient numbers of these particles in the atmosphere to strongly influence clouds. Here we show that the ice-nucleating activity of a fungus from the ubiquitous genus Fusarium is related to the presence of nanometre-scale particles which are far more numerous, and therefore potentially far more important for cloud glaciation than whole intact spores or hyphae. In addition, we quantify the ice-nucleating activity of nano-ice nucleating particles (nano-INPs) washed off pollen and also show that nano-INPs are present in a soil sample. Based on these results, we suggest that there is a reservoir of biological nano-INPs present in the environment which may, for example, become aerosolised in association with fertile soil dust particles