Summary Diderm bacteria have an outer membrane that provides defense against environmental factors including antibiotics. Understanding the process of outer membrane biogenesis is, therefore, of ...critical importance in order to envisage new treatments of these bacterial pathogens. Borrelia burgdorferi is the pathogen responsible for Lyme disease. Its outer membrane contains integral, beta-barrel proteins as well as swathes of externally exposed lipoproteins. Previous work has demonstrated that the beta-barrel assembly machine (BAM complex) in B. burgdorferi and other Spirochetes shares several similarities with the BAM complex in other bacterial lineages, such as the Proteobacteria that includes Escherichia coli. However, Iqbal et al. () have identified the inner membrane protein TamB as a subunit of the BAM complex in Spirochetes. This latest study highlights the modular nature of the BAM complex, and suggests that in some bacterial lineages the BAM complex and translocation and assembly module (the TAM) function as a single unit.
Heat shock protein 90 (Hsp90) is an ATP-dependent molecular chaperone which is essential in eukaryotes. It is required for the activation and stabilization of a wide variety of client proteins and ...many of them are involved in important cellular pathways. Since Hsp90 affects numerous physiological processes such as signal transduction, intracellular transport, and protein degradation, it became an interesting target for cancer therapy. Structurally, Hsp90 is a flexible dimeric protein composed of three different domains which adopt structurally distinct conformations. ATP binding triggers directionality in these conformational changes and leads to a more compact state. To achieve its function, Hsp90 works together with a large group of cofactors, termed co-chaperones. Co-chaperones form defined binary or ternary complexes with Hsp90, which facilitate the maturation of client proteins. In addition, posttranslational modifications of Hsp90, such as phosphorylation and acetylation, provide another level of regulation. They influence the conformational cycle, co-chaperone interaction, and inter-domain communications. In this review, we discuss the recent progress made in understanding the Hsp90 machinery.
Only when the power goes off and food spoils do we truly appreciate how much we rely on refrigerators and freezers. In Refrigeration Nation, Jonathan Rees explores the innovative methods and gadgets ...that Americans have invented to keep perishable food cold—from cutting river and lake ice and shipping it to consumers for use in their iceboxes to the development of electrically powered equipment that ushered in a new age of convenience and health.
As much a history of successful business practices as a history of technology, this book illustrates how refrigeration has changed the everyday lives of Americans and why it remains so important today. Beginning with the natural ice industry in 1806, Rees considers a variety of factors that drove the industry, including the point and product of consumption, issues of transportation, and technological advances. Rees also shows that how we obtain and preserve perishable food is related to our changing relationship with the natural world. He compares how people have used the cold chain in America to other countries, offering insight into more than just what we eat. Refrigeration Nation helps explain one small part of who we are as a people.
Water is fundamental to human life, and the ways in which a society uses it can tell us a great deal about a people. The ancient Greeks and Romans had at their disposal several mechanical ...water-lifting devices. The water-screw, the force pump, the compartmented wheel, and the bucket-chain were developed by scientists associated with the great school at Alexandria. Application of these devices was sporadic in the Hellenistic world, but they, and the later saqiya gear, were used in a wide range of rural and urban settings in many parts of the Roman Empire. Professor Oleson has prepared a definitive study of mechanical water-lifting devices in the Greek and Roman world. He systematically and thoroughly examines the literary, papyrological, and archaeological evidence for the devices and considers the design, materials, settings, costs, effectiveness, and durability of the many adaptations of the small basic repertoire of models. The literary and papyrological materials range from Deuteronomy to papyri of the seventh century AD, and the archaeological sites discussed range from Babylon to Wales. An extensive collection of illustrations complements the literary, papyrological, and archaeological evidence for this remarkable ancient technology.
In the context of the rapid rise of agricultural mechanization in China, this paper examines the impact of household-owned farm machinery and outsourced agricultural machinery services on the land ...leasing behavior of Chinese relatively large-scale farmers. Based on the CFPS2018 survey data, this study suggests that farm machinery is beneficial for expanding the scale of farms. With increases in household-owned machinery, farmers are more inclined to lease-in land, and they are less inclined to rent-out land. The more agricultural machinery services farmers purchase, the more they tend to transfer-in land and the probability of transfer-out land is lower. However, uneven village terrain can weaken the effects of the two kinds of agricultural mechanization on land leasing. Moreover, this study confirms that household-owned farm machinery and outsourced agricultural machinery services could positively regulate each other's influence on land leasing, indicating that there is a complementary relationship between the two types of agricultural machinery. Further mechanism analyses show that the channels by which household-owned farm machinery and outsourced agricultural machinery services affect land leasing are quite different. The self-purchased machinery of farmers mainly plays a role through labor complementarity effects, while outsourced agricultural machinery services mainly affect land leasing through labor substitution effects.
•With increases in household-owned machinery, farmers are more (less) inclined to lease-in (lease-out) land.•The more agricultural machinery services farmers purchase, the more (less) they tend to transfer-in (transfer-out) land.•There is a complementary relationship between household-owned farm machinery and outsourced agricultural machinery services.•Self-purchased farm machinery mainly plays a role through labor complementarity effects.•Outsourced agricultural machinery services mainly affect land leasing through labor substitution effects.
Mitochondria are essential in most eukaryotes and are involved in numerous biological functions including ATP production, cofactor biosyntheses, apoptosis, lipid synthesis, and steroid metabolism. ...Work over the past two decades has uncovered the biogenesis of cellular iron-sulfur (Fe S) proteins as the essential and minimal function of mitochondria. This process is catalyzed by the bacteria-derived iron-sulfur cluster assembly (ISC) machinery and has been dissected into three major steps: de novo synthesis of a 2Fe-2S cluster on a scaffold protein; Hsp70 chaperone-mediated trafficking of the cluster and insertion into 2Fe-2S target apoproteins; and catalytic conversion of the 2Fe-2S into a 4Fe-4S cluster and subsequent insertion into recipient apoproteins. ISC components of the first two steps are also required for biogenesis of numerous essential cytosolic and nuclear Fe S proteins, explaining the essentiality of mitochondria. This review summarizes the molecular mechanisms underlying the ISC protein-mediated maturation of mitochondrial Fe S proteins and the importance for human disease.
•An extended and up-to-date review on bearing fault assessment (BFA) is provided.•Detailed information on signal processing and learning approaches is given.•Fault size and damage degradation ...estimation are stated as the main aims in BFA.•VIB, AE, CUR and VOLT are found as the main signals to extract useful information.•Open problems and challenges on this research topic are discussed.
Health condition monitoring of rotating machinery is a crucial task to guarantee reliability in industrial processes. In particular, bearings are mechanical components used in most rotating devices and they represent the main source of faults in such equipments; reason for which research activities on detecting and diagnosing their faults have increased. Fault detection aims at identifying whether the device is or not in a fault condition, and diagnosis is commonly oriented towards identifying the fault mode of the device, after detection. An important step after fault detection and diagnosis is the analysis of the magnitude or the degradation level of the fault, because this represents a support to the decision-making process in condition based-maintenance. However, no extensive works are devoted to analyse this problem, or some works tackle it from the fault diagnosis point of view. In a rough manner, fault severity is associated with the magnitude of the fault. In bearings, fault severity can be related to the physical size of fault or a general degradation of the component. Due to literature regarding the severity assessment of bearing damages is limited, this paper aims at discussing the recent methods and techniques used to achieve the fault severity evaluation in the main components of the rolling bearings, such as inner race, outer race, and ball. The review is mainly focused on data-driven approaches such as signal processing for extracting the proper fault signatures associated with the damage degradation, and learning approaches that are used to identify degradation patterns with regards to health conditions. Finally, new challenges are highlighted in order to develop new contributions in this field.
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