mathematical chemistry is a branch of theoretical chemistry for discussion and prediction of the molecular structure using mathematical methods without necessarily referring to quantum mechanics. in theoretical chemistry, distance-based molecular structure descriptors are used for modeling physical, pharmacologic, biological and other properties of chemical compounds. the wiener polarity index ...

Administration of the direct acting carcinogen N-methyl-N-nitrosourea (NMU) to 50-55-day-old virgin female rats on different days of the estrous cycle yields differential breast tumor biology (T. A. Ratko and C. W. Beattie, Cancer Res., 45: 3042-3047). One basis for these estrous cycle-dependent differences may be the duration of cell cycle stages of susceptible structures such as mammary termi...

The hydrogen (H₂) cycle associated with the dinitrogen (N₂) fixation process was studied in laboratory cultures of the marine cyanobacterium Crocosphaera watsonii. The rates of H₂ production and acetylene (C₂H₂) reduction were continuously measured over the diel cycle with simultaneous measurements of fast repetition rate fluorometry and dissolved oxygen. The maximum rate of H₂ production was c...

We investigate minimum vertex degree conditions for 3-uniform hypergraphs which ensure the existence of loose Hamilton cycles. A loose Hamilton cycle is a spanning cycle in which consecutive edges intersect in a single vertex. We prove that every 3-uniform n-vertex (n even) hypergraph H with minimum vertex degree δ1(H) ≥ ( 7 16 + o(1) ) ( n 2 ) contains a loose Hamilton cycle. This bound is asy...

Let G be an undirected connected graph that is not a path. We define h(G) (respectively, s(G)) to be the least integer m such that the iterated line graph Lm(G) has a Hamiltonian cycle (respectively, a spanning closed trail). To obtain upper bounds on h(G) and s(G), we characterize the least integer m such that Lm(G) has a connected subgraph H, in which each edge of H is in a 3-cycle and V (H) ...

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We consider the complexity of the Hamilton cycle decision problem when restricted to k-uniform hypergraphs H of high minimum codegree δ(H). We show that for tight Hamilton cycles this problem is NP-hard even when restricted to k-uniform hypergraphsH with δ(H) ≥ n2−C, where n is the order of H and C is a constant which depends only on k. This answers a question raised by Karpiński, Ruciński and ...

This paper aims to provide comprehensive 4E (energy, exergy, exergoeconomic, and exergoenvironmental) advanced exergy analyses of the Refrigeration Cycle (RC) Heat Recovery (HRRC) comparison performance with R744 (CO2) R744A (N2O) working fluids. Moreover, multi-objective optimization systems has been considered define optimal conditions best cycle from various perspectives. In HRRC, heat recov...

Cytoplasmic polyadenylation-induced mRNA translation is a hallmark of early animal development. In Xenopus oocytes, where the molecular mechanism has been defined, the core factors that control this process include CPEB, an RNA binding protein whose association with the CPE specifies which mRNAs undergo polyadenylation; CPSF, a multifactor complex that interacts with the near-ubiquitous polyade...

Cell-cycle induction in hepatocytes protects from prolonged tissue damage after toxic liver injury. Early growth response (Egr)-1(-/-) mice exhibit increased liver injury after carbon tetrachloride (CCl(4)) exposure and reduced TNF-α production. Because TNF-α is required for prompt cell-cycle induction after liver injury, here, we tested the hypothesis that Egr-1 is required for timely hepatocy...