Parallel-Axis Gear Design Methodology for Minimization of Power Loss and Its Effect on Vibration Characteristics

Gear tooth strength is mainly considered in gear design to ensure the ability to transmit power. With the design process, various sets of gear parameters are probably selected to meet the tooth strength. However the efficiencies of various designed gears are different. Improper gear parameter selection probably makes the gear power loss increase significantly. In this paper, the design methodology to minimize gear power loss is presented. A spur gear selected from a catalogue is used as the reference gear. Then several gears with various parameters but having the ability to transmit the same load are designed. The power losses of the designed and the reference gears are estimated by the sliding loss model, hence the minimum power loss gear is able to choose from the various designed gear set.s Both analytical and experimental results show that to minimize gear power loss along with keeping loading capacity, pressure angle should be increased and module should be reduced. The effect of this design methodology on vibration characteristics is also investigated by measuring the vibration attributed to the sample gear sets. It is found that the helical gear having large pressure angle, wide face width and having helix angle about 10° to 20° is favorable, since it has more capability to transmit load, lower power loss and also lower vibration than the reference spur gear

Spur and Helical Gear Sliding Loss Model with Load Distribution Pattern on Gear Tooth Surface

The model for estimation of spur and helical gear sliding loss with load distribution pattern on gear tooth surface is presented in this paper. The load distribution for the spur gear is considered to distribute uniformly along the line of contact. During double teeth meshing, load sharing ratio between meshing teeth is considered to be 33:67 percent or 45:55 percent. For the helical gear the load distribution can be calculated by the method proposed by Niemann and Richter. The contour plots of load distribution conform to the tooth contact patterns obtained experimentally. The sliding losses estimated from the presented method are compared with the estimations done by the former model and also the experimental results. It is found that the sliding losses calculated from the presented method are closer to the experimental results than the estimations from the former model. The effects of the helix angle and pressure angle on the sliding loss can also be estimated correctly by the presented method.The model for estimation of spur and helical gear sliding loss with load distribution pattern on gear tooth surface is presented in this paper. The load distribution for the spur gear is considered to distribute uniformly along the line of contact. During double teeth meshing, load sharing ratio between meshing teeth is considered to be 33 : 67 percent or 45 : 55 percent. For the helical gear the load distribution can be calculated by the method proposed by Niemann and Richter. The contour plots of load distribution on gear tooth surface conform to the tooth contact patterns obtained experimentally. The sliding losses estimated from the presented method are compared with the estimations done by the former model and also the experimental results. It is found that the sliding losses calculated from the presented method are closer to the experimental results than the estimations from the former model. The effects of the helix angle and pressure angle on the sliding loss can also be estimated correctly by the presented method

Polymeric IgA are sulfated proteins

AbstractThe main sulfated proteins secreted by rabbit mammary gland tissue had Mr of ∼67 000, 63 000 and 23 000, and one component which most likely corresponded to proteoglycans had a diffuse electrophoretic mobility (Mr>200 000). The sulfate groups in the 67–63 kDa proteins were mostly linked to carbohydrates. These proteins and the 23 kDa protein were co-purified and identified to heavy chains of immunoglobulin A (IgA) and J chain, respectively. Sulfation of α-chains also occurred in rat mammary and rabbit lacrimal glands. We conclude that polymeric IgA which are produced by plasma cells and released in secretion fluids after transcytosis through epithelia are sulfated

Analytical and Experimental Investigation of Parameters Affecting Sliding Loss in a Spur Gear Pair

The effects of gear module, pressure angle and gear ratio on the sliding losses of a spur gear pair have been investigated analytically and experimentally in this paper. The analytical investigations were done by using the gear meshing model proposed in the authors' former work. The various empirical formulas of friction coefficient are used in the calculation process. The estimated results are compared with the experimental results done by using back-to-back gear test rig. The analytical results agree well with the experimental results. The sliding losses of gears having larger module are higher than the gears having smaller module. The larger pressure angle gears have lower sliding losses, and increasing the gear ratio causes the increase in sliding loss. The estimated results calculated by using the friction coefficient formula proposed by ISO TC60 are the most accurate comparing with the experimental results

αS1-casein, which is essential for efficient ER-to-Golgi casein transport, is also present in a tightly membrane-associated form

<p>Abstract</p> <p>Background</p> <p>Caseins, the main milk proteins, aggregate in the secretory pathway of mammary epithelial cells into large supramolecular structures, casein micelles. The role of individual caseins in this process and the mesostructure of the casein micelle are poorly known.</p> <p>Results</p> <p>In this study, we investigate primary steps of casein micelle formation in rough endoplasmic reticulum-derived vesicles prepared from rat or goat mammary tissues. The majority of both α_S1- and β-casein which are cysteine-containing casein was dimeric in the endoplasmic reticulum. Saponin permeabilisation of microsomal membranes in physico-chemical conditions believed to conserve casein interactions demonstrated that rat immature β-casein is weakly aggregated in the endoplasmic reticulum. In striking contrast, a large proportion of immature α_S1-casein was recovered in permeabilised microsomes when incubated in conservative conditions. Furthermore, a substantial amount of α_S1-casein remained associated with microsomal or post-ER membranes after saponin permeabilisation in non-conservative conditions or carbonate extraction at pH11, all in the presence of DTT. Finally, we show that protein dimerisation via disulfide bond is involved in the interaction of α_S1-casein with membranes.</p> <p>Conclusions</p> <p>These experiments reveal for the first time the existence of a membrane-associated form of α_S1-casein in the endoplasmic reticulum and in more distal compartments of the secretory pathway of mammary epithelial cells. Our data suggest that α_S1-casein, which is required for efficient export of the other caseins from the endoplasmic reticulum, plays a key role in early steps of casein micelle biogenesis and casein transport in the secretory pathway.</p

Resistance of LHC main bus bar splices at room temperature and at 77.4 K

As part of the quality control the resistance of newly produced LHC main bus bar splices is now routinely measured at room temperature (RT) in order to conclude on the electrical continuity of the bus bar stabiliser across the splice under operating conditions. In this note we present splice resistance measurements that have been performed at RT and in liquid nitrogen (LN) in the CERN Cryolab with “ideal” splices (represented by continuous dipole and quadrupole bus bars), and with dipole and quadrupole splices with different defects, which cause an additional RT splice resistance of up to 60 µΩ. The RT resistance (RRT) results obtained with the Cryolab set-up are compared to the calculated resistance values and with the so-called R-8 and R-16 resistance results, as they are measured in the LHC tunnel with a Digital Low Resistance Ohmmeter with a voltage tap distance of 8 cm or 16 cm. The RT to LN resistance ratio has been determined for all splices in order to study the influence of the resistance of the splice contact surfaces on the overall splice resistance

Optochemical Tools For Protein Dimerization In Living Cells

Fundamental biological processes including cell division, migration, and death, are driven by protein interactions. Regulation of protein localization is one of the mechanisms cells utilize to control cellular events with high spatial and temporal precision. Therefore, several techniques have been developed to provide control of protein interactions and localization. A number of elegant approaches employ naturally light-responsive proteins, also known as optogenetics, to reversibly induce protein‒ protein binding interactions with subcellular precision. However, the application of these light-inducible protein systems to various intracellular locations beyond the plasma membrane has been limited. Moreover, to achieve sustained interactions in some applications, most of these optogenetic systems require continuous illumination, increasing the risk of phototoxicity. Another robust and widely utilized technique to control protein interactions via small molecules is the chemically-induced dimerization (CID) of proteins; the most classic example of this technique being rapamycin-induced dimerization. However, the lack of spatiotemporal control and reversibility in this system has necessitated the development of new dimerizers in the past two decades. By combining light-inducible features with the CID technique, we have created a novel platform to rapidly and reversibly induce protein dimerization using light with high specificity in living cells. This is accomplished with subcellular spatiotemporal resolution using a series of novel, cell-permeable, photoactivatable, and photocleavable chemical dimerizers. The modular design of our system has allowed us to tailor the properties of our molecules for studying various protein functions and biological pathways inside living cells. Furthermore, we demonstrate the utility of our system by applying it to manipulate dynamic biological events including organelle transport and spindle assembly checkpoint. This work establishes a foundation for optogenetic control over protein function and highlights the advantages of a hybrid chemical and genetic approach. We envision our tools to be readily adapted to experimentally probe complex signaling networks and other cellular processes that depend upon spatiotemporal regulation of protein localization on biologically-relevant timescales

The Empirical Formula for the Stiffness of a Spur Gear Pair Based on Finite Element Solutions

Gear meshing stiffness is commonly determined by the analytical method or the finite element method (FEM). Both methods can be used to determine the meshing stiffness but the calculation for the analytical method is more complicated, while the FEM is impacted by the tooth contact setting and large computation time. Thus, both methods have limitations for practical use. Here, an empirical formula was proposed to calculate meshing stiffness of a spur gear pair with gear ratio 1:1 in moderate to large load conditions. The formula was divided into two parts as 1) an equation used to calculate the stiffness of the gear cylinder derived from the elasticity equations, and 2) an empirical formula to determine the meshing stiffness of the tooth pair based on FEM solutions. The second part of the formula was constructed by selecting the related parameters, finding the appropriate formula pattern, and determining the relation between these parameters and tooth stiffness at any meshing position. Meshing stiffness of the gear pair was determined by combining the stiffness of two parts connected in series.  Accuracy of the empirical formula was verified by comparing the calculated meshing stiffness with previous research and indicated that the calculated meshing stiffness conformed well with other studies. Our proposed empirical formula can be applied to any spur gear pair with gear ratio 1:1 to accurately determine gear meshing stiffness

The membrane-associated form of as1- casein interacts with cholesterol-rich detergent-resistant microdomains

Caseins, the main milk proteins, interact with colloidal calcium phosphate to form the casein micelle. The mesostructure of this supramolecular assembly markedly influences its nutritional and technological functionalities. However, its detailed molecular organization and the cellular mechanisms involved in its biogenesis have been only partially established. There is a growing body of evidence to support the concept that as1-casein takes center stage in casein micelle building and transport in the secretory pathway of mammary epithelial cells. Here we have investigated the membrane-associated form of as1-casein in rat mammary epithelial cells. Using metabolic labelling we show that as1-casein becomes associated with membranes at the level of the endoplasmic reticulum, with no subsequent increase at the level of the Golgi apparatus. From morphological and biochemical data, it appears that caseins are in a tight relationship with membranes throughout the secretory pathway. On the other hand, we have observed that the membrane-associated form of as1-casein co-purified with detergent-resistant membranes. It was poorly solubilised by Tween 20, partially insoluble in Lubrol WX, and substantially insoluble in Triton X-100. Finally, we found that cholesterol depletion results in the release of the membrane-associated form of as1-casein. These experiments reveal that the insolubility of as1-casein reflects its partial association with a cholesterolrich detergent-resistant microdomain. We propose that the membrane-associated form of as1-casein interacts with the lipid microdomain, or lipid raft, that forms within the membranes of the endoplasmic reticulum, for efficient forward transport and sorting in the secretory pathway of mammary epithelial cells