Mechanosynthesis - Knowledge

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early paper gives a predicted placement speed of 1 dimer per second for this tooltip, this limit was imposed by the slow speed of recharging the tool using an inefficient recharging method and is not based on any inherent limitation in the speed of use of a charged tooltip. Additionally, no sensing means was proposed for discriminating among the three possible outcomes of an attempted dimer placement—deposition at the correct location, deposition at the wrong location, and failure to place the dimer at all—because the initial proposal was to position the tooltip by dead reckoning, with the proper reaction assured by designing appropriate chemical energetics and relative bond strengths for the tooltip-surface interaction.

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mechanochemical means, under the control of an external computer. In the literature, such a tool is called an assembler or molecular assembler. Once assemblers exist, geometric growth (directing copies to make copies) could reduce the cost of assemblers rapidly. Control by an external computer should then permit large groups of assemblers to construct large, useful projects to atomic precision. One such project would combine molecular-level conveyor belts with permanently mounted assemblers to produce a factory.

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in 2003 commissioned a study to deal with these issues and larger social and ecological implications, led by mechanical engineering professor Ann Dowling. This was anticipated by some to take a strong position on these problems and potentials —– and suggest any development path to a general theory of

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The DCB6Ge tooltip motif, initially described at a Foresight Conference in 2002, was the first complete tooltip ever proposed for diamond mechanosynthesis and remains the only tooltip motif that has been successfully simulated for its intended function on a full 200-atom diamond surface. Although an

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The goal of one line of mechanoassembly research focuses on overcoming these problems by calibration, and selection of appropriate synthesis reactions. Some suggest attempting to develop a specialized, very small (roughly 1,000 nanometers on a side) machine tool that can build copies of itself using

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would be attached to molecular mechanical systems, and their encounters would result from mechanical motions bringing them together in planned sequences, positions, and orientations. It is envisioned that mechanosynthesis would avoid unwanted reactions by keeping potential reactants apart, and would

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on a cryogenic copper surface, grossly validating the approach. Since then, a number of research projects have undertaken to use similar techniques to store computer data in a compact fashion. More recently the technique has been used to explore novel physical chemistries, sometimes using lasers to

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There is a growing body of peer-reviewed theoretical work on synthesizing diamond by mechanically removing/adding hydrogen atoms and depositing carbon atoms (a process known as diamond mechanosynthesis or DMS). For example, the 2006 paper in this continuing research effort by Freitas, Merkle and

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More recent theoretical work analyzes a complete set of nine molecular tools made from hydrogen, carbon and germanium able to (a) synthesize all tools in the set (b) recharge all tools in the set from appropriate feedstock molecules and (c) synthesize a wide range of stiff hydrocarbons (diamond,

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temperature), and that the silicon variant (DCB6Si) also works at 80 K but not at 300 K. These tooltips are intended to be used only in carefully controlled environments (e.g., vacuum). Maximum acceptable limits for tooltip translational and rotational misplacement errors are reported in paper

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In practice, getting exactly one molecule to a known place on the microscope's tip is possible, but has proven difficult to automate. Since practical products require at least several hundred million atoms, this technique has not yet proven practical in forming a real product.

667:, and then use the microscope's precise positioning abilities to push the molecule on the tip into another on a substrate. Since the angles and distances can be precisely controlled, and the reaction occurs in a vacuum, novel chemical compounds and arrangements are possible. 539:, because of the many strong bonds it can form, the many types of chemistry these bonds permit, and utility of these bonds in medical and mechanical applications. Carbon forms diamond, for example, which if cheaply available, would be an excellent material for many machines. 460:

in which reaction outcomes are determined by the use of mechanical constraints to direct reactive molecules to specific molecular sites. There are presently no non-biological chemical syntheses which achieve this aim. Some atomic placement has been achieved with

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in 2000, is a focused ongoing effort involving 23 researchers from 10 organizations and 4 countries that is developing a practical research agenda specifically aimed at positionally controlled diamond mechanosynthesis and diamondoid nanofactory development.

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Current technical proposals for nanofactories do not include self-replicating nanorobots, and recent ethical guidelines would prohibit development of unconstrained self-replication capabilities in nanomachines.

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reported the first instance of purely mechanical-based covalent bond-making and bond-breaking, i.e., the first experimental demonstration of true mechanosynthesis—albeit with silicon rather than carbon atoms.

706:(SPM) on an atomic surface at room temperature. The suggested methodology supports fully automatic control of single- and multiprobe instruments in solving tasks of mechanosynthesis and bottom-up 474: 559: 493:, reactive molecules encounter one another through random thermal motion in a liquid or vapor. In a hypothesized process of mechanosynthesis, reactive 123: 648:

III—tooltips must be positioned with great accuracy to avoid bonding the dimer incorrectly. Over 100,000 CPU hours were invested in this study.

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and difficult laboratory work. In the early 2000s, a typical experimental arrangement was to attach a molecule to the tip of an

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and green goo (various potential disasters arising from runaway replicators, which could be built using mechanosynthesis) the

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graphite, fullerenes, and the like). All required reactions are analyzed using standard ab initio quantum chemistry methods.

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In 2008, a $ 3.1 million grant was proposed to fund the development of a proof-of-principle mechanosynthesis system.

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capable of building macroscopic objects with atomic precision. The potential for these has been disputed, notably by

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their collaborators reports that the most-studied mechanosynthesis tooltip motif (DCB6Ge) successfully places a C

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Robert A. Freitas Jr., "A Simple Tool for Positional Diamond Mechanosynthesis, and its Method of Manufacture,"

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excite the tips to particular energy states, or examine the quantum chemistry of particular chemical bonds.

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strongly favor desired reactions by holding reactants together in optimal orientations for many molecular

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Much of the excitement regarding advanced mechanosynthesis regards its potential use in assembly of

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R. V. Lapshin (2011). "Feature-oriented scanning probe microscopy". In H. S. Nalwa (ed.).

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did not address molecular manufacturing at all, except to dismiss it along with grey goo.

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Mediated Growth of Diamond C(110) Surface via Si/Ge-Triadamantane Dimer Placement Tools"

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Oyabu, Noriaki; Custance, ÓScar; Yi, Insook; Sugawara, Yasuhiro; Morita, Seizo (2003).

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Most theoretical explorations of advanced machines of this kind have focused on using

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Temelso, Berhane; Sherrill, C. David; Merkle, Ralph C.; Freitas, Robert A. (2006).

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Deposition on Diamond C(110) Surface using Si/Ge/Sn-based Dimer Placement Tools"

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Yin, Zhi-Xiang; Cui, Jian-Zhong; Liu, Wenbin; Shi, Xiao-Hong; Xu, Jin (2007).

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In 2005, the first patent application on diamond mechanosynthesis was filed.

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Mann, David J.; Peng, Jingping; Freitas, Robert A.; Merkle, Ralph C. (2004).

813: 782: 606: 517:. So far, such devices provide the closest approach to fabrication tools for 351: 322: 223: 1577: 1410: 1239: 963: 921: 676: 570: 374: 242: 194: 60: 1185: 1147: 1091: 1049: 1001: 798:"Drexler and Smalley make the case for and against 'molecular assemblers'" 758: 1130: 1107:"Theoretical Analysis of Diamond Mechanosynthesis. Part III. Positional C 979:"Theoretical Analysis of Diamond Mechanosynthesis. Part I. Stability of C 955: 691: 659:

Further research to consider alternate tips will require time-consuming

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systems, with ribosome-like systems as an attractive early objective.

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2004 proposed practical method for enabling diamond mechanosynthesis

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In part to resolve this and related questions about the dangers of

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The technique of moving single atoms mechanically was proposed by

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provides an example of a programmable mechanosynthetic device.

690:'s Zürich Research Institute successfully spelled the letters 1027:"Theoretical Analysis of Diamond Mechanosynthesis. Part II. C 977:

Peng, Jingping; Freitas, Robert A.; Merkle, Ralph C. (2004).

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Dimer Placement Tooltip Motifs for Diamond Mechanosynthesis"

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Mediated Growth of Nanocrystalline Diamond C(110) Surface"

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In 1999, an experimentally proved methodology called

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Digital Matter?: Towards Mechanised Mechanosynthesis

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Speeding the development of molecular nanotechnology

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