Fluctuations in mixtures of lamellar- and nonlamellar-forming lipids

We consider the role of nonlamellar-forming lipids in biological membranes by examining fluctuations, within the random phase approximation, of a model mixture of two lipids, one of which forms lamellar phases while the other forms inverted hexagonal phases. To determine the extent to which nonlamellar-forming lipids facilitiate the formation of nonlamellar structures in lipid mixtures, we examine the fluctuation modes and various correlation functions in the lamellar phase of the mixture. To highlight the role fluctuations can play, we focus on the lamellar phase near its limit of stability. Our results indicate that in the initial stages of the transition, undulations appear in the lamellae occupied by the tails, and that the nonlamellar-forming lipid dominates these undulations. The lamellae occupied by the head groups pinch off to make the tubes of the hexagonal phase. Examination of different correlations and susceptibilities makes quantitative the dominant role of the nonlamellar-forming lipids.Comment: 7 figures (better but larger in byte figures are available upon resuest), submitte

New mechanism of membrane fusion

We have carried out Monte Carlo simulation of the fusion of bilayers of single chain amphiphiles which show phase behavior similar to that of biological lipids. The fusion mechanism we observe is very different from the ``stalk'' hypothesis. Stalks do form on the first stage of fusion, but they do not grow radially to form a hemifused state. Instead, stalk formation destabilizes the membranes and results in hole formation in the vicinity of the stalks. When holes in each bilayer nucleate spontaneously next to the same stalk, an incomplete fusion pore is formed. The fusion process is completed by propagation of the initial connection, the stalk, along the edges of the aligned holes.Comment: 4 pages, 3 figure

Distribution of lipids in non-lamellar phases of their mixtures

We consider a model of lipids in which a head group, characterized by its volume, is attached to two flexible tails of equal length. The phase diagram of the anhydrous lipid is obtained within self-consistent field theory, and displays, as a function of lipid architecture, a progression of phases: body-centered cubic, hexagonal, gyroid, and lamellar. We then examine mixtures of an inverted hexagonal forming lipid and a lamellar forming lipid. As the volume fractions of the two lipids vary, we find that inverted hexagonal, gyroid, or lamellar phases are formed. We demonstrate that the non-lamellar forming lipid is found preferentially at locations which are difficult for the lipid tails to reach. Variations in the volume fraction of each type of lipid tail are on the order of one to ten per cent within regions dominated by the tails. We also show that the variation in volume fraction is correlated qualitatively with the variation in mean curvature of the head-tail interface.Comment: 10 pages, 12 figures (better figures are available upon request), to appear in J. Chem. Phy

Returning Methods of Rykyu\u27s Drifting Ships in the Qing Dynasty

The communication between Ryukyu･Okinawa and China has a long history. It has been said that the history has begun even at Ming Dynasty. Ryukyu Dynasty were canonized by Chinese king even after Satsuma clan (now Kagoshima Prefecture)\u27s invasion in the beginning of 17 century. The tributary relations between Ryukyu and China had last for 5 centuries until Ryukyu became Okinawa Prefecture by Meiji Japanese government in 1872. The relationship between China and Ryukyu basic were tributary relations. However, the main transportation mean in Ryukyu were by ship, and lots of ship encountered typhoon, lost control of their ship, and finally were drifted to China continent. You can refer to these historical documentation in the book 「Selected documentation of China-Ryukyu relations in Qing Dynasty」 which was public by China First Historical Archives. Lots of ship-drift cases are written in this book from Qianlong era to Guangxu era of Qing Dynasty. Various forms of transportation can be found form those cases. This paper will not focus on tributary ships from Ryukyu, but on the part of rescue and aid from Qing government to those who were drifted from Ryukyu

Sewage treatment

The basic function of the wastewater treatment plant is to speed up the natural processes by which water purifies itself. In earlier years, the natural treatment process in streams and lakes was adequate to perform basic wastewater treatment. As our population and industry grew, increased levels of treatment became necessary before discharging domestic wastewater

On the Question of the Imperative or Dispositivity of the Norm of Paragraph 1 of Article 782 of the Civil Code of the Russian Federation, Which Establishes the Right of the Customer to Unmotivated Refusal of the Contract for the Provision of Paid Services

In this article, the author explores the question of the qualification of Paragraph 1 of Article 782 of the Civil Code of the Russian Federation, which gives the right to unmotivated refuse to perform a contract for the provision of paid services. The paper considers various approaches to the issue of dispositivity or imperativeness of this norm. The positions of scientists on the legal nature of 782 of the Civil Code of the Russian Federation are considered. The author analyzes judicial practice for the possibility of blocking the right to unilateral refusal. Based on the presented analysis, conclusions are drawn about the dispositivity of 782 of the Civil Code of the Russian Federation regarding the inadmissibility of blocking the right to unilateral refusal itself, at the same time, the parties are allowed to establish a different procedure for the implementation of this right. A possible option for improving domestic legislation regulating the termination of a contract for the provision of paid services is also proposed