tailieunhanh - Flocculation In Natural And Engineered Environmental Systems - Chapter 16

Hiểu biết về số phận của các hạt (cá nhân tế bào cũng như vật liệu flocculated) quan trọng cho việc mô tả các thông lượng của vật chất hữu cơ trầm tích trong các hồ và đại dương. Đông máu có thể đóng một vai trò quan trọng trong số phận của những hạt này vì nó có thể kết quả trong sản xuất của các hạt lớn hơn mà có thể phục vụ làm thức ăn cho ăn hạt động vật, hoặc có thể giải quyết và bị mất trầm tích dưới biển sâu. hiểu biết hóa học và vật lý các yếu. | 16 Using Atomic Force Microscopy to Study Factors Affecting Bioadhesion at Molecular to Nanoscale Levels Bruce E. Logan CONTENTS Introduction. 339 Methods. 341 Results and Discussion. 341 Bacterial Topography. 341 Surface Roughness . 344 Interaction Forces. 345 Outlook for Using AFM to Study Attachment Processes. 348 Acknowledgments. 348 References . 348 INTRODUCTION Understanding the fate of particles individual cells as well as flocculated material is important for describing the flux of organic matter to sediments in lakes and oceans. Coagulation can play an important role in the fate of these particles as it can result in the production of larger particles that either can serve as food for particle-feeding animals or can settle out and be lost to deep marine sediments. Understanding the chemical and physical factors that affect adhesion and therefore coagulation rates has not been easy. There are a variety of particle types and sizes in aquatic systems that affect both the collision rate and the collision efficiency. Here we consider factors affecting the success of the initial adhesion event with a focus on molecular-scale effects. Most particles both biotic and abiotic in freshwater and marine systems carry a net negative charge. Conventional DLVO theory has been used to understand the 1-56670-615-7 05 2005 byCRC Press 339 Copyright 2005 by CRC Press 340 Flocculation in Natural and Engineered Environmental Systems collision and adhesion of these like-charged particles. According to this theory the forces governing the approach of two colloidal particles or surfaces are described in terms of Lifshitz-van der Waals LW attractive forces and electrostatic EL repulsive forces between like-charged Particle charge is typically measured in terms of zeta potential based on the velocity of a particle suspended in water between two plates set at a fixed potential. Because of the high salinity of .