Liquid crystal phase of counter-rotating staircases – A case of antiferrochirality

Helical structures continue to inspire, and there is considerable temptation to attribute helicity to columnar liquid crystals (LC). While short isohelical sequences are undoubtedly present, and longer ones in chiral or chiral-doped compounds, the order is only short-range, equivalent to a paramagnet without or with field. However, here we report a confirmed example of a true LC phase of achiral compounds consisting of columns, each being a long-range homochiral helix. Long-range periodicity and isochirality are maintained by intercolumnar interaction. This orthorhombic LC, spacegroup Fddd, is discovered in compounds with either bent or straight rod-like pi-conjugated cores. There are 4 right and 4 left-handed ribbons or star-profiled columns per unit cell. The structure is equivalent to an antiferromagnet with twist replacing spins. A theory based on interacting quadrupoles confirms this structure as energetically favoured over alternatives. The findings open a new approach to homochirality in achiral compounds, with promising optical/chiroptical properties.

Laser scanning based straightness measurement of precision bright steel rods

In industrial manufacturing of bright steel rods one important quality factor is the straightness or straightness deviation. Depending on the application, deviations of less than 0.1 mm per meter rod length are desired and can be reached with state of the art manufacturing equipment. Such high quality requirements can only be guaranteed with continuos quality control. Manual straightness measurements conducted offline using a dial gauge provide accurate results on single positions of the rod. We propose a contactless, optical measurment technique based on laser scanning which has the potential to be used inline during production to inspect all rods over the entire length. The method is based on evaluating the intensity signal of the reflected laser radiation against the scan angle. It is shown, that in combination with an accurate calibration this signal can be used to determine the rod’s deviation from a straight rod. We explain the measurement and calibration principle as well as data evaluation. We present the experimental setup and first measurement results on a single position on several samples. For a homogeneous sample surface and neglecting laser drift, accuracy and precision were determined to be in the range of 10 - 20 µm. We discuss the working principle of a potential inline system.

Controlled Growth of CdS Nanostep Structured Arrays to Improve Photoelectrochemical Performance

CdS nanostep-structured arrays were grown on F-doped tin oxide-coated glasses using a two-step hydrothermal method. The CdS arrays consisted of a straight rod acting as backbone and a nanostep-structured morphology on the surface. The morphology of the samples can be tuned by varying the reaction parameters. The phase purity, morphology, and structure of the CdS nanostep-structured arrays were characterized by X-ray diffraction and field emission scanning electron microscopy. The light and photoelectrochemical properties of the samples were estimated by a UV-Vis absorption spectrum and photoelectrochemical cells. The experimental results confirmed that the special nanostep structure is crucial for the remarkable enhancement of the photoelectrochemical performance. Compared with CdS rod arrays, the CdS nanostep-structured arrays showed increased absorption ability and dramatically improved photocurrent and energy conversion efficiency. This work may provide a new approach for improving the properties of photoelectrodes in the future.

Microbacterium algeriense sp. nov., a novel actinobacterium isolated from Algerian oil production waters

A non-motile, straight-rod-shaped, Gram-stain-positive and facultative anaerobic bacterium (i.e., strain G1T) was isolated from production waters from an Algerian oilfield. Growth was observed in the presence of 0.3–3.5 % (w/v) NaCl, at 20–50 °C and at pH 6.0–9.0. Results of phylogenetic analyses based on 16S rRNA gene sequences showed that strain G1T belonged to the genus Microbacterium . Strain G1 T was closely related to Microbacterium oxydans (DSM 20578T) and Microbacterium maritypicum (DSM 12512T) with 99.8 % sequence similarity and to Microbacterium saperdae (DSM 20169T) with 99.6 % sequence similarity. Strain G1 T contained MK9, MK10, MK11, MK12 and MK13 as respiratory quinones, and phosphatidylglycerol, diphosphatidylglycerol and glycolipid as the major polar lipids. The major cellular fatty acids were anteiso-C15:0, iso-C16:0 and anteiso-C17:0. The estimated DNA G+C content was 69.57 mol% based on its draft genome sequence. Genome annotation of strain G1T predicted the presence of 3511 genes, of which 3483 were protein-coding and 47 were tRNA genes. The DNA–DNA hybridization (DDH) and average nucleotide identity (ANI) values between strain G1T and M. oxydans (DSM 20578T) and M. maritypicum (DSM 12512T) were in both cases far below the respective species boundary thresholds (27.5 and 28.0 % for DDH; and 84.40 and 84.82% for ANI, respectively). Based on the data presented above, strain G1T was considered to represent a novel species for which the name Microbacterium algeriense is proposed with the type strain G1T (=DSM 109018T=LMG 31276T).

VALUATION OF DURABILITY OF ROD PILLARS OF THE SLOPY RESCUING DEVICE

The need for special saving devices arises during emergency response. Such situations are connected with rescuing of people or animals from deep narrow holes or even from under blockages of constructions. By using the saving devices the cargo raising on a certain height is possible if other ways of delivery are absent. Main structural elements of saving devices are three rod pillars. Top ends of rods are connected in a mounting knot. Often the saving device is equipped with the winch. The winch could be fasten to one of the rod pillars or have individual placing. Rescuing devices differ in a type of a rod design (straight or a slopy plane), loading capacity, rods production material, type of rods connection, a possibility of using on slopes with pillars location in the different planes, modifications of winches, compactness during transportation. There is a big variety of rescuing devices, however in the market of Ukraine offer mostly straight rod rescuing devices. Therefore there is a need for creation of design and durability checking of the slopy rod rescuing device which could be applied to carrying out rescue operations from bridges, buildings and other constructions. In this work it is performed an estimation of durability of a design of the slopy rod rescuing device. It is considered three cases of the support pillars placement. The first case is when pillars of the slopy rescuing device are placed in one horizontal plane. The second case - the longest rod pillar is placed on a ledge. The third case - two shorter rod pillars are placed on a ledge. For each of these cases it is established a type of deformation of rods of the saving device. Construction rods are stretching or compression during work are and loaded with longitudinal forces. From the stretching durability condition the cross section of steel rods is picked up.

Design, Simulation, and Test of a New Threshing Cylinder for High Moisture Content Corn

Corn harvesting mode has gradually changed from ear harvesting to direct grain harvesting. In view of the problems of high moisture content in corn harvesting in China, such as the rates of broken grains (BGR) and uncleared grains (UGR) being too high, a new single longitudinal axial threshing cylinder was designed, which mainly included a cylinder spindle, a spiral feeding inlet, a T-type rasp bar, a separating straight rod, and a spiral extracting rod. Firstly, the three states of grain during the threshing process and the key influence factors of threshing and force analysis of corn ears in the threshing device were analyzed, then the structure of the threshing cylinder was designed, and its parameters were determined by theoretical analysis results. The arrangement mode of threshing elements adopted a combination of a T-type rasp bar, a separating straight rod, and a spiral extracting rod with a 6-head spiral pattern and an arrangement step of 250 mm. Secondly, the arrangement step of threshing elements was determined by discrete element method solution (DEM) simulation; the result showed that the average movement velocity was 55.04 m/s and the threshing time was 6–8 s. Finally, a multiple factors experiment of the threshing device was carried out, and the result showed that the order of the effect factors of the BGR and UGR was cylinder rotational speed > concave clearance > feed amount. When cylinder rotational speed was 309.17 r/min, concave clearance was 35.48 mm, and the feed amount was 6.13 kg/s. The verification experiment result showed that the BGR and UGR were 1.24% and 1.33%, respectively, which meet standard requirements. The research results could provide a reference for the design of a high moisture content grain threshing device and combine harvester.

Effect of Ultrasonic Bending Vibration Introduced by the L-shaped Ultrasonic Rod on Solidification Structure and Segregation of Large 2A14 Ingots

In order to achieve long-term and stable ultrasonic treatment in the direct chill semi-continuous casting process, a new L-shaped ceramic ultrasonic wave guide rod is designed to introduce ultrasonic bending vibration into 2A14 aluminum alloy melt. The effect of ultrasonic bending vibration on the solidification structure and composition segregation of large 2A14 aluminum alloy ingots (φ 830 mm × 6000 mm) in the process of semi-continuous casting were studied by means of a direct reading spectrometer, scanning electron microscope, metallographic microscope, and hardness test. The ultrasonic ingot treated by bending vibration was compared with the ingot without ultrasonic treatment and the ingot treated by the traditional straight-rod titanium alloy wave guide rod. The results show that, during the solidification of 2A14 aluminum alloy, ultrasonic treatment can significantly refine the grain, break up the agglomerated secondary phase, and make its distribution uniform. The macro-segregation degree of solute including the negative segregation at the edge of the ingots and the positive segregation in the center can be reduced. Through comparative analysis, the macrostructure of the ingot, treated by the L-shaped ceramic ultrasonic wave guide rod, was found to be better than that of the ingot treated by the traditional straight-rod titanium alloy wave guide rod. In particular, the grain refinement effect at the edge of the ingot was the best, the secondary phase was smaller, more solute elements can be dissolved into the α-Al matrix, and the ability of the L-shaped ultrasonic wave guide rod to restrain segregation was stronger at the edge of the ingot.

NEW STRAIN OF PARARHIZOBIUM SP. IB ST 1-4 ISOLATED FROM POOL FINGERS OF SHULGAN-TASH CAVE

From the mineral formation (pool fingers) of the shulgfan-Tash cave (Southern Urals) the first member of bacterial genus Pararhizobium was isolated (strain IB St 1-4). Pararhizobium is a genus of soil bacteria that fix nitrogen association with roots of legumes. Cells IB St 1-4 strain are Gram-negative straight rod-shaped bacterium (0,5-0,7×2,0-2,5μm). Growth is observed at 4-28°C with an optimum pH at 6-8. The strain precipitating of calcium carbonate on Ca-salts of malic acid in vitro. The relatedness of strain IB St 1-4 to members of Pararhizobium herbae, Pararhizobium giardinii and Pararhizobium polonicum species was revealed according physiological and biochemical features as well as phylogenetic analysis of the 16S rRNA gene sequence. The genes nifH and nodC that responsible for nitrogen fixation and plant nodulation in the strain IB St 1-4 were not detected.