Quality control of 40S ribosome head assembly ensures scanning competence

During translation initiation, 40S ribosomes scan the mRNA until they encounter the start codon, where conformational changes produce a translation-competent 80S complex. Destabilizing the scanning complex results in misinitiation at non-AUG codons, demonstrating its importance for fidelity. Here, we use a combination of biochemical and genetic analyses to demonstrate that the ability of the nascent subunit to adopt the scanning complex is tested during assembly via structural mimicry. Specifically, formation of the 80S-like assembly intermediate, which structurally resembles scanning complexes, requires the correct folding of two rRNA elements in the subunit head and the proper positioning of the universally conserved head proteins Rps3, Rps15, Rps20, and Rps29. rRNA misfolding impairs the formation of 80S-like ribosomes, and bypass of individual checkpoints using cancer-associated mutations produces ribosomes defective in accurate start-site selection. Thus, the formation of 80S-like assembly intermediates is a quality control step that ensures scanning competence of the nascent subunit.

Initial tightening of a cylinder head assembly on a marine engine block

When attaching the cylinder head to the engine block, to internal combustion engines, the force with which the mounting screws are tightened is of particular importance (in case of too tight a tightening the screws may break, and in the case of too small tightening the fluid may leave the container due to removal. the flanges one to the other). In the case of slow, high-power engines, the engine block is individual, containing a single cylinder shirt. The intermediate solution of the engine block for a group of cylinders is also used. The two-stroke engine chops are more strongly heat demanded, due to the doubling of the number of cycles in the unit of time, respectively by combustion processes in the unit of time. Requesting the cylinder head bolts and other components of the assembly by force due to the pressure developed during the process of gas exchange and combustion in the engine cylinders is a demand with a pulsating character.

A Cut above the Rest: Characterization of the Assembly of a Large Viral Icosahedral Capsid

The head of Salmonella virus SPN3US is composed of ~50 different proteins and is unusual because within its packaged genome there is a mass (>40 MDa) of ejection or E proteins that enter the Salmonella cell. The assembly mechanisms of this complex structure are poorly understood. Previous studies showed that eight proteins in the mature SPN3US head had been cleaved by the prohead protease. In this study, we present the characterization of SPN3US prohead protease mutants using transmission electron microscopy and mass spectrometry. In the absence of the prohead protease, SPN3US head formation was severely impeded and proheads accumulated on the Salmonella inner membrane. This impediment is indicative of proteolysis being necessary for the release and subsequent DNA packaging of proheads in the wild-type phage. Proteomic analyses of gp245- proheads that the normal proteolytic processing of head proteins had not occurred. Assays of a recombinant, truncated form of the protease found it was active, leading us to hypothesize that the C-terminal propeptide has a role in targeting the protease into the prohead core. Our findings provide new evidence regarding the essential role of proteolysis for correct head assembly in this remarkable parasite.

Research on spiral angle optimization for longitudinal road header's cutting head

The cutting head is the key component of a road header in tunnel excavation, where the concept of the spiral angle design directly affects the comprehensive performance, which includes cutting resistance, fluctuation coefficient, specific energy consumption, cutting head stress distribution, and so on. Based on the theory of rock-breaking by pick, the mechanical model of pick was established, and the three-dimensional force vector in the WORKBENCH coordinate system was determined. The 3D model of the proposed cutting head was designed using PRO/E and the static simulation was carried out using WORKBENCH, while the stress information of key parts was obtained. Furthermore, a four-dimensional fitting method was used to investigate the influence of the horizontal swing speed, rotational speed, and spiral angle of the cutting head, on the stress of the cutting head assembly. By setting the horizontal swing speed, rotational speed and the spiral angle as design variables and the specific energy consumption, total cutting resistance, fluctuation coefficient, power consumption, and stress on cutting head assembly as the objective function; the multiobjective optimization function of the cutting head was established. By using genetic algorithm, the complex problem has been solved. The solution of this optimization function provides the horizontal swing speed, rotational speed, and spiral angle values, where the optimal performance is achieved, in the aspect of energy consumption, cutting resistance, fluctuation coefficient, cutting power, and cutting motor power. This method provides solid guidance and is a great reference in spiral angle design and optimization.

Mechanical Design and Analysis of Detector Head Assembly for Space bone High-Resolution Imaging Sensor

The imaging sensors employed in satellites are subjected to a wide range of vibratory loads induced during the launching phase. The effect of temperature change also needs to be looked upon while designing the structure of the imaging sensor as satellite passes through the solar and lunar phase. This project work goes into depth of challenges incurred during launching and in-orbit operation. The research includes development of lightweight structure, incorporating flexure interface to house detector head assembly (DHA) components. The design of flexural mount is a novel approach that not only arrests the deformation of the imaging sensor but also restricts structural stresses to affect the performance of the imaging sensor. This article showcases the assessment of three different mechanical designs of DHA through finite element simulation results computed in ANSYS workbench environment. The survivability of DHA structure has been checked under 55g quasi-static loading to simulate launch vibration along with 10°C thermal gradient corresponded to the in-service orbital motion. In this research work, AL6061-T6 and Kovar has been chosen for various design components of the DHA as they are space qualified materials. Though both material options showed similar performance, due to low density, ready availability and cost effectiveness leads to select Al6061-T6 material for the fabrication of DHA components.

Analysis of a Flanged and Dished Head Assembly Used in a Horizontal Storage Tank

A nonstandard flanged and dished head is frequently used in the horizontal storage tank for quick and full access to the internal in oil and gas industry. The head is forged into an elliptical shape with a flat edge at its peripheral. The flat edge serves as a flange while the other mating half coming from the tank shell. The flange pair is installed within a C-shaped clamp and secured by compression bolts at its head side. A gasket is sandwiched between the mating surfaces of the flange pair to provide proper seal. While the head can be removed easily by unscrewing the compression bolts, this disintegrated structure does increase the complexity in component design and unique requirement for installation. The bolt compression load not only affects the pressure capacity of the storage tank, but also governs the stresses in flange pair and C-clamp. In this study, the flanged and dished head assembly has been modeled and analyzed by finite element method for stresses and gasket seal performance subject to installation and operation loads. Both elastic and elastic-plastic analysis has been performed. The tightening force of the bolts is examined against component stresses and gasket seal performance. Optimized bolt load is recommended based on acceptance criteria for stresses and leakage prevention.

Halobacterium salinarum virus ChaoS9, a Novel Halovirus Related to PhiH1 and PhiCh1

The unexpected lysis of a large culture of Halobacterium salinarum strain S9 was found to be caused by a novel myovirus, designated ChaoS9. Virus purification from the culture lysate revealed a homogeneous population of caudovirus-like particles. The viral genome is linear, dsDNA that is partially redundant and circularly permuted, has a unit length of 55,145 nt, a G + C% of 65.3, and has 85 predicted coding sequences (CDS) and one tRNA (Arg) gene. The left arm of the genome (0–28 kbp) encodes proteins similar in sequence to those from known caudoviruses and was most similar to myohaloviruses phiCh1 (host: Natrialba magadii) and phiH1 (host: Hbt. salinarum). It carries a tail-fiber gene module similar to the invertible modules present in phiH1 and phiCh1. However, while the tail genes of ChaoS9 were similar to those of phiCh1 and phiH1, the Mcp of ChaoS9 was most similar (36% aa identity) to that of Haloarcula hispanica tailed virus 1 (HHTV-1). Provirus elements related to ChaoS9 showed most similarity to tail/assembly proteins but varied in their similarity with head/assembly proteins. The right arm (29–55 kbp) of ChaoS9 encoded proteins involved in DNA replication (ParA, RepH, and Orc1) but the other proteins showed little similarity to those from phiH1, phiCh1, or provirus elements, and most of them could not be assigned a function. ChaoS9 is probably best classified within the genus Myohalovirus, as it shares many characteristics with phiH1 (and phiCh1), including many similar proteins. However, the head/assembly gene region appears to have undergone a recombination event, and the inferred proteins are different to those of phiH1 and phiCh1, including the major capsid protein. This makes the taxonomic classification of ChaoS9 more ambiguous. We also report a revised genome sequence and annotation of Natrialba virus phiCh1.