New prefabricated support structure for TBM tunneling in complex strata of coal mines: engineering practice

Tunnel Boring Machines (TBMs) have been successfully applied in the excavation of deep shaft roadways in coal mines, yielding substantial socio-economic benefits. However, technical bottlenecks remain that hinder their further promotion and application. In response to the challenge of current support structures and techniques failing to simultaneously meet the requirements of support efficiency, strength, and construction costs, which impedes the full utilization of TBM speed advantages, a research team has developed a novel steel pipe segment assembly support structure. Large-scale model tests of the new prefabricated support structure were conducted to ascertain the deformation and failure patterns under loaded conditions, and the support structure was optimized based on the test results. Numerical simulations were performed to evaluate the reliability of the new support structure under TBM tunneling conditions. Industrial trials were subsequently conducted to field-test the feasibility of the new steel pipe segment support structure for TBM-excavated roadways in coal mines. The test results indicate that the maximum tensile strain of the surrounding rock is 803 με, and the deformation of the steel pipe support structure is less than 1 mm. The new support structure can be installed quickly, with the installation of one ring of segments (1.5 m) completed within 90 minutes, significantly enhancing the support strength in TBM-excavated roadways and the adaptability to strata conditions. This research provides a technical reference for further increasing the tunneling speed of coal mine roadways and ensuring the continuity of coal mining operations

Stakeholder Perspectives on Sustainability in the Food-Energy-Water Nexus

Interest in the various dimensions of environmental, economic, and social sustainability for food, energy, and water (FEW) systems, independently and collectively (i. e., the FEW nexus), has spawned an increasing amount of literature that seeks to understand the various linkages within the FEW nexus and provide guidance to inform decision-making to enhance sustainability. While the use of science and data can generate important and relevant information, it is not clear how important they are relative to relevant policy and the integration of policy within and across the individual FEW domains. In this work, we assessed perspectives on various considerations that pertain to sustainability in the FEW nexus. To do so, we identified numerous stakeholder groups who have interests throughout the FEW nexus, and conducted a survey of a subset of these groups. Although the responses differed across the stakeholder groups that we surveyed, the consistent result was that stakeholders generally understand that FEW systems are physically connected at high levels, and that policy is less integrated than desired. When forced to choose between priorities for science and data or for integrated policy to enhance sustainability, respondents from Academia and Extension preferred more science and data, whereas respondents who are, or more frequently interact with, practitioners and policy-makers preferred integrated policy. Overall, with other results and findings that are relevant for advancing sustainability and improving communication the FEW nexus, we conclude that the importance of science, data, and integrated policy depends on the context in which the stakeholders operate in the FEW domain

Requirement of argininosuccinate lyase for systemic nitric oxide production

Nitric oxide (NO) is crucial in diverse physiological and pathological processes. We show that a hypomorphic mouse model of argininosuccinate lyase (encoded by Asl) deficiency has a distinct phenotype of multiorgan dysfunction and NO deficiency. Loss of Asl in both humans and mice leads to reduced NO synthesis, owing to both decreased endogenous arginine synthesis and an impaired ability to use extracellular arginine for NO production. Administration of nitrite, which can be converted into NO in vivo, rescued the manifestations of NO deficiency in hypomorphic Asl mice, and a nitric oxide synthase (NOS)-independent NO donor restored NO-dependent vascular reactivity in humans with ASL deficiency. Mechanistic studies showed that ASL has a structural function in addition to its catalytic activity, by which it contributes to the formation of a multiprotein complex required for NO production. Our data demonstrate a previously unappreciated role for ASL in NOS function and NO homeostasis. Hence, ASL may serve as a target for manipulating NO production in experimental models, as well as for the treatment of NO-related diseases

The integral graphs with index 3 and exactly two main eigenvalues

AbstractA graph is called integral if the spectrum of its adjacency matrix has only integral eigenvalues. An eigenvalue of a graph is called main eigenvalue if it has an eigenvector such that the sum of whose entries is not equal to zero. In this paper, we show that there are exactly 25 connected integral graphs with exactly two main eigenvalues and index 3

Some results on graphs with exactly two main eigenvalues

AbstractAn eigenvalue of a graph G is called main if there is an associated eigenvector not orthogonal to j, the vector with each entry equal to 1. In this work, an error in a prior paper [Y. Hou and F. Tian, Unicyclic graphs with exactly two main eigenvalues, Appl. Math. Letters, 19 (2006), 1143–1147] is pointed out and the properties of the graphs with exactly two main eigenvalues and with pendent vertices are discussed. As an application, we obtain, together with known results, all connected bicyclic and tricyclic graphs with exactly two main eigenvalues