Direct-contact Transfer Research Articles

Dense monolayer films of atomically precise graphene nanoribbons on metallic substrates enabled by direct contact transfer of molecular precursors.

Atomically precise graphene nanoribbons (GNRs) of two types, chevron GNRs and N = 7 straight armchair GNRs (7-AGNRs), have been synthesized through a direct contact transfer (DCT) of molecular precursors on Au(111) and gradual annealing. This method provides an alternative to the conventional approach for the deposition of molecules on surfaces by sublimation and simplifies preparation of dense monolayer films of GNRs. The DCT method allows deposition of molecules on a surface in their original state and then studying their gradual transformation to polymers to GNRs by scanning tunneling microscopy (STM) upon annealing. We performed STM characterization of the precursors of chevron GNRs and 7-AGNRs, and demonstrate that the assemblies of the intermediates of the GNR synthesis are stabilized by π-π interactions. This conclusion was supported by the density functional theory calculations. The resulting monolayer films of GNRs have sufficient coverage and density of nanoribbons for ex situ characterization by spectroscopic methods, such as Raman spectroscopy, and may prove useful for the future GNR device studies.

Preface

This ninth volume of the serial publication, Annual Review of Heat Transfer, continues the fine tradition of providing improved communication on new, important developments in the general field of heat transfer. As in previous volumes, each chapter in the Annual Review deals with a significant, emerging topic by starting from fundamental physical considerations and then proceeding in a logical fashion to the forefront of recent developments and future challenges. The contributing authors are either young but upcoming, or well-established leaders in these emerging fields. A list of the topics covered in the past two volumes illustrates well this special characteristic of the Annual Review. Volume 7 contained excellent chapters on significant, but wide-ranging heat transfer research and developments in micro- and nano-scale optical and optoelectronic devices, growth of dendritic crystals, polymeric composite processing, active enhancement using electric field, direct-contact transfer with droplets, clean-up of underground toxic wastes, and fluidized beds, while Volume 8 considered such important topics as heat transfer in microelectronics, Rayleigh-Bénard convection, aerodynamics of flame surfaces, radiative transfer in non-isothermal inhomogeneous media, heat pipe analysis and simulation, and high heat flux spray cooling. Continuing with this tradition, the present volume provides informative chapters on bioheat transfer, large scale surface radiative transport, radiative transfer in fibrous media, combustion in porous media, turbine blade coolant passage heat transfer, external flow film boiling, heat transfer in oscillatory flows, and two-dimensional annular flow. The editor is deeply grateful to the participating authors for their excellent contributions, to Begell House for providing invaluable editorial assistance, and to the heat transfer community for its continuing support and input.

Preface

The serial publication, Annual Review of Heat Transfer, focuses on new, important developments in the general field of heat transfer. As in the previous volumes, each chapter in the Annual Review deals with a significant, emerging topic by starting from fundamental physical considerations and then proceeding in a logical fashion to the forefront of recent developments and future challenges. The contributing authors are either young and upcoming, or well-established leaders in these emerging fields. A list of the topics covered in the last two volumes illustrates this special characteristic of the Annual Review. Volume 6 considered heat transfer topics in bio-optical imaging, ultrafine structures (aerogels), multi-phase modeling of alloy solidification, liquid jet impingement, interface measurements, CVD diamond layers, and molecular and microscale transport phenomena; Volume 7 contained excellent chapters on significant, but wide-ranging heat transfer research and developments in micro- and nano-scale optical and optoelectronic devices, growth of dendritic crystals, polymeric composite processing, active enhancement using electric fields, direct-contact transfer with droplets, clean-up of underground toxic wastes, and fluidized beds. Following this distinctive character, the present volume provides important contributions on heat transfer in microelectronics, Rayleigh-Benard convection, aerodynamics of flame surfaces, radiative transfer in non-isothermal inhomogeneous media, heat pipe analysis and simulation, and high heat flux spray cooling. The editor wishes to express his deep gratitude to the participating authors for their outstanding contributions, to Begell House for providing consistently excellent editorial assistance, and to the heat transfer community for its continuing support and input.

Studies on the Transmission of Amebiasis in a Children's Home in New Orleans 1

Summary and ConclusionsAn historical review of the transmission of amebiasis indicates that little is known of the actual means of the transmission of the infection, and that the cysts of Endamoeba histolytica have not been recovered except within the body of man and reservoir hosts, under fingernails, in feces or associated with filth flies. The known continued high incidence of amebiasis in a children's home in New Orleans over a period of many years presented the opportunity of studying the mechanism of transmission of amebiasis in an institutional environment.Two procedures were selected for the isolation of the organisms: (1) use of the Foerst centrifuge to recover organisms from liquid media, and (2) application of NIH swabs to detect contamination in relatively dry places of this institution. Experimental tests with the Foerst centrifuge indicated that the efficiency of the machine was above 70 per cent for the parasites tested. Concentrates of parasite organisms in this machine were obtained from dust samples, hands, toys, underwear and contents of the wading pool.Endamoeba histolytica was isolated from six places: the hands and soiled underwear of the children, the bottom of the laundry chute, the damp sand in the play box, the pool contents, and the concrete floor of the pool after draining. Other parasites, including Endamoeba coli, Endolimax nana, Enterobius vermicularis, and undiagnosable amebic cysts, were found in these and other places. The tops of boxes, chairs, seats of toys, bed frames, laundered underwear, toys, book shelves, swings and slides, floors and stairways were all found contaminated with protozoan cysts and helminth eggs which had most probably originated from infections in the children.The methods of transmission of amebiasis in this home suggest direct contact transfer aided by the general pollution of the environment. This conclusion has been reached as a logical inference. A description of the daily routine of the children has been presented, with an explanation of how these organisms might have reached the places from which they were isolated, and why they might serve as a source of infection for the children.The epidemiologies of E. histolytica and Enterobius appear to parallel one another in this institution. The high incidence of these infections has continued in the home in spite of ordinary hygienic measures directed against them. On the other hand, the operation of this type of transmission has already been demonstrated for oxyuriasis. The habits of the children, living in close contact, and the employment of unskilled help who did not always realize the necessity of hygienic measures probably aided considerably in perpetuating the incidence of amebiasis in this institution.Since the continued high incidence of amebiasis appeared to be due to direct contact transfer and general pollution of the environment, the home was cleaned throughout with live steam at the same time that mass chemotherapy directed against E. histolytica was carried out on the attendants and the children. The efficacy of steam sterilization as a supplementary means of eradicating the infection extrinsically was later tested by using NIH swabs in locations previously demonstrated as contaminated by the children. Four weeks after completion of the treatment the examination of one specimen from each of the children by means of the direct fecal film and zinc sulphate centrifugal floatation technic indicated that not a single stool specimen was positive.These tests indicate that the use of live steam to sterilize the environment together with antiamebic mass chemotherapy constituted a simple and practical means of controlling amebiasis. It seems probable that, under similar environmental conditions elsewhere, this same technic might be applied with equal success.