Nanocrystallography has transformed our ability to interrogate the atomic structures of proteins, peptides, organic molecules and materials. By probing atomic level details in ordered sub-10 nm regions of nanocrystals, scanning nanobeam electron diffraction extends the reach of nanocrystallography and in principle obviates the need for diffraction from large portions of one or more crystals. Scanning nanobeam electron diffraction is now applied to determine atomic structures from digitally defined regions of beam-sensitive peptide nanocrystals. Using a direct electron detector, thousands of sparse diffraction patterns over multiple orientations of a given crystal are recorded. Each pattern is assigned to a specific location on a single nanocrystal with axial, lateral and angular coordinates. This approach yields a collection of patterns that represent a tilt series across an angular wedge of reciprocal space: a scanning nanobeam diffraction tomogram. Using this diffraction tomogram, intensities can be digitally extracted from any desired region of a scan in real or diffraction space, exclusive of all other scanned points. Intensities from multiple regions of a crystal or from multiple crystals can be merged to increase data completeness and mitigate missing wedges. It is demonstrated that merged intensities from digitally defined regions of two crystals of a segment from the OsPYL/RCAR5 protein produce fragment-based ab initio solutions that can be refined to atomic resolution, analogous to structures determined by selected-area electron diffraction. In allowing atomic structures to now be determined from digitally outlined regions of a nanocrystal, scanning nanobeam diffraction tomography breaks new ground in nanocrystallography.

Relativistic electron diffraction depends on linear and quadratic terms in the electric potential, the latter being neglected in the frequently used relativistically corrected Schrödinger equation. The quadratic electric potential term modifies atomic scattering amplitudes in particular for large-angle scattering and backscattering. The respective correction increases with increasing scattering angle, increasing atomic number and increasing kinetic energy. Conventional tabulations for electron scattering and its large-angle extrapolations can be amended in closed form by a universal correction based on the screened Coulomb potential squared.

A novel approach for finding and evaluating structural models of small metallic nanoparticles is presented. Rather than fitting a single model with many degrees of freedom, libraries of clusters from multiple structural motifs are built algorithmically and individually refined against experimental pair distribution functions. Each cluster fit is highly constrained. The approach, called cluster-mining, returns all candidate structure models that are consistent with the data as measured by a goodness of fit. It is highly automated, easy to use, and yields models that are more physically realistic and result in better agreement to the data than models based on cubic close-packed crystallographic cores, often reported in the literature for metallic nanoparticles.

In this study, the atomic structure of the ternary icosahedral ZnMgTm quasicrystal (QC) is investigated by means of single-crystal X-ray diffraction. The structure is found to be a member of the Bergman QC family, frequently found in Zn–Mg–rare-earth systems. The ab initio structure solution was obtained by the use of the Superflip software. The infinite structure model was founded on the atomic decoration of two golden rhombohedra, with an edge length of 21.7 Å, constituting the Ammann–Kramer–Neri tiling. The refined structure converged well with the experimental diffraction diagram, with the crystallographic R factor equal to 9.8%. The Bergman clusters were found to be bonded by four possible linkages. Only two linkages, b and c, are detected in approximant crystals and are employed to model the icosahedral QCs in the cluster approach known for the CdYb Tsai-type QC. Additional short b and a linkages are found in this study. Short interatomic distances are not generated by those linkages due to the systematic absence of atoms and the formation of split atomic positions. The presence of four linkages allows the structure to be pictured as a complete covering by rhombic triacontahedral clusters and consequently there is no need to define the interstitial part of the structure (i.e. that outside the cluster). The 6D embedding of the solved structure is discussed for the final verification of the model.

A new approach is presented to obtain candidate structures from atomic pair distribution function (PDF) data in a highly automated way. It fetches, from web-based structural databases, all the structures meeting the experimenter's search criteria and performs structure refinements on them without human intervention. It supports both X-ray and neutron PDFs. Tests on various material systems show the effectiveness and robustness of the algorithm in finding the correct atomic crystal structure. It works on crystalline and nanocrystalline materials including complex oxide nanoparticles and nanowires, low-symmetry and locally distorted structures, and complicated doped and magnetic materials. This approach could greatly reduce the traditional structure searching work and enable the possibility of high-throughput real-time auto-analysis PDF experiments in the future.

Structure-mining finds and returns the best-fit structures from structural databases given a measured pair distribution function data set. Using databases and heuristics for automation it has the potential to save experimenters a large amount of time as they explore candidate structures from the literature.

A scientifically accurate and valid epidemiologic study of reproductive problems among the families of veterans exposed to radiation from atomic bombings and nuclear weapons tests is not feasible, concluded an Institute of Medicine (IOM) committee in a new report.

The science questions that could be answered by an electron ion collider (EIC) – a very large-scale particle accelerator – are significant to advancing our understanding of the atomic nuclei that make up all visible matter in the universe, says a new report by the National Academies of Sciences, Engineering, and Medicine.

The federal government should foster collaboration and decrease obstacles that can keep foreign atomic, molecular, and optical (AMO) physicists from working in the United States, if the nation is to maintain its position as leader in these fields, says a new report from the National Academies of Sciences, Engineering, and Medicine.

The rate of warming in the oceans is 'relentless,' and the hottest 5 years ever recorded were the last 5.

Atomic Habits author James Clear offers tips for adopting good habits, dropping bad ones, enhancing your decision-making, and focusing on continuous improvement.

Maralinga Tjarutja shines a spotlight on the people who have lived on their lands for over 60,000 years. While it’s a story of deep tragedy, it also celebrates their incredible resilience.

An intimate account of one young girl’s harrowing experience and miraculous survival.

A wristwatch, which comprises an atomic oscillator comprising a system for detecting the beat frequencies obtained by the Raman effect.

Embodiments include methods of identifying a personalized cardiovascular device based on patient-specific geometrical information, the method comprising acquiring an anatomical model of at least part of the patient's vascular system; performing, using a processor, one or more of geometrical analysis, computational fluid dynamics analysis, and structural mechanics analysis on the anatomical model; and identifying, using the processor, a personalized cardiovascular device for the patient, based on results of one or more of the geometrical analysis, computational fluid dynamics analysis, and structural mechanics analysis of anatomical model.

Embodiments include methods of identifying a personalized cardiovascular device based on patient-specific geometrical information, the method comprising: generating a patient specific model of at least a portion of a patient's vasculature from image data of the patient's vasculature and one or more measured or estimated physiological or phenotypic parameters of the patient; determining pathology characteristics from cardiovascular geometry of the patient specific model; defining an objective function for a device based on design considerations and one or more estimates of hemodynamic and mechanical characteristics; optimizing the objective function, by simulating at least one change in devices and evaluating the objective function using fluid dynamic or structural mechanic analysis; and using the optimized objective function to either (i) select a device from a set of available devices or (ii) manufacture a desired device.

A method for preparing a metal sulfide thin film using ALD and structures incorporating the metal sulfide thin film. The method includes providing an ALD reactor, a substrate, a first precursor comprising a metal and a second precursor comprising a sulfur compound. The first and the second precursors are reacted in the ALD precursor to form a metal sulfide thin film on the substrate. In a particular embodiment, the metal compound comprises Bis(N,N'-di-sec-butylacetamidinato)dicopper(I) and the sulfur compound comprises hydrogen sulfide (H2S) to prepare a Cu2S film. The resulting metal sulfide thin film may be used in among other devices, photovoltaic devices, including interdigitated photovoltaic devices that may use relatively abundant materials for electrical energy production.

A process for the purification of organometallic compounds or heteroatomic organic compounds from oxygen, water and from the compounds deriving from the reaction of water and oxygen with the organometallic or heteroatomic compounds whose purification is sought, comprising the operation of contacting the organometallic or heteroatomic compound to be purified in the liquid state or in form of vapor, pure or in a carrier gas, with a hydrogenated getter alloy, and optionally also with one or more gas sorber materials selected among palladium on porous supports and a mixture of iron and manganese supported on zeolites.

Barium, strontium, tantalum and lanthanum precursor compositions useful for atomic layer deposition (ALD) and chemical vapor deposition (CVD) of titanate thin films. The precursors have the formula M(Cp)2, wherein M is strontium, barium, tantalum or lanthanum, and Cp is cyclopentadienyl, of the formula (I), wherein each of R1-R5 is the same as or different from one another, with each being independently selected from among hydrogen, C1-C12 alkyl, C1-C12 amino, C6-C10 aryl, C1-C12 alkoxy, C3-C6 alkylsilyl, C2-C12 alkenyl, R1R2R3NNR3, wherein R1, R2 and R3 may be the same as or different from one another and each is independently selected from hydrogen and C1-C6 alkyl, and pendant ligands including functional group(s) providing further coordination to the metal center M. The precursors of the above formula are useful to achieve uniform coating of high dielectric constant materials in the manufacture of flash memory and other microelectronic devices.

Barium, strontium, tantalum and lanthanum precursor compositions useful for atomic layer deposition (ALD) and chemical vapor deposition (CVD) of titanate thin films. The precursors have the formula M(Cp)2, wherein M is strontium, barium, tantalum or lanthanum, and Cp is cyclopentadienyl, of the formula wherein each of R1-R5 is the same as or different from one another, with each being independently selected from among hydrogen, C1-C12 alkyl, C1-C12 amino, C6-C10 aryl, C1-C12 alkoxy, C3-C6 alkylsilyl, C2-C12 alkenyl, R1R2R3NNR3, wherein R1, R2 and R3 may be the same as or different from one another and each is independently selected from hydrogen and C1-C6 alkyl, and pendant ligands including functional group(s) providing further coordination to the metal center M. The precursors of the above formula are useful to achieve uniform coating of high dielectric constant materials in the manufacture of flash memory and other microelectronic devices.

A method of depositing a crystalline strontium titanate film on a substrate is provided, comprising carrying out an atomic layer deposition (ALD) process with strontium and titanium precursors, wherein the strontium precursor is bis(n-propyltetramethylcyclopentadienyl)strontium.

Barium, strontium, tantalum and lanthanum precursor compositions useful for atomic layer deposition (ALD) and chemical vapor deposition (CVD) of titanate thin films. The precursors have the formula M(Cp)2, wherein M is strontium, barium, tantalum or lanthanum, and Cp is cyclopentadienyl, of the formula wherein each of R1-R5 is the same as or different from one another, with each being independently selected from among hydrogen, C1-C12 alkyl, C1-C12 amino, C6-C10 aryl, C1-C12 alkoxy, C3-C6 alkylsilyl, C2-C12 alkenyl, R1R2R3NNR3, wherein R1, R2 and R3 may be the same as or different from one another and each is independently selected from hydrogen and C1-C6 alkyl, and pendant ligands including functional group(s) providing further coordination to the metal center M. The precursors of the above formula are useful to achieve uniform coating of high dielectric constant materials in the manufacture of flash memory and other microelectronic devices.

An atomic oscillator includes: a gas cell which includes two window portions having a light transmissive property and in which metal atoms are sealed; a light emitting portion that emits excitation light to excite the metal atoms in the gas cell; a light detecting portion that detects the excitation light transmitted through the gas cell; a heater that generates heat; and a connection member that thermally connects the heater and each window portion of the gas cell to each other.

Casting jigs, methods, and kits that may be used in manufacture of anatomical healing caps. A casting jig may include a body having one or more wells within the body, each well being open at a proximal end thereof and having a negative shape corresponding to an anatomical healing cuff body of a given tooth position. Each respective anatomical healing cuff body negative shape includes an asymmetrical cross-section and an irregular surface so that an anatomical healing cuff body having said shape is configured to provide substantially custom filling of at least an emergence portion of a void where a natural tooth once emerged or should have emerged from the void (e.g., in the case of a congenitally missing tooth). The casting jig may further include a socket at a distal end of each well that is configured to receive therein a dental implant or dental implant analog.

A method for forming a V-NAND device is disclosed. Specifically, the method involves deposition of at least one of semiconductive material, conductive material, or dielectric material to form a channel for the V-NAND device. In addition, the method may involve a pretreatment step where ALD, CVD, or other cyclical deposition processes may be used to improve adhesion of the material in the channel.

Hundreds of thousands of U.S. veterans took part in nuclear tests after World War II, and into the Cold War. Many of these vets suffer long-term health issues including lung problems and cancer, and many haven’t received compensation for their injuries and feel abused, neglected and forgotten by the government and a country that exposed them to unforeseen risks. This story of the veterans who witnessed secret atomic testing is a co-production with our friends at the RetroReport.

Visitors are travelling to outback South Australia for tours of the former atomic testing site, but traditional owners want to see the narrative refocused to tell their story.

A friend wrote to me today urging me to read Killing the Rising Sun as, by he said, Bill O’Reilly, since it made the case that the U.S. had to drop atomic bombs on Japan. My reply: You underestimate me, my friend; I’ve already read to Killing the Rising Sun. The key issue out of […]

In my new novel, The Oppenheimer Alternative — coming June 2, 2020, and available for pre-order now — the following exchange occurs between J. Robert Oppenheimer and his wife Kitty (with Kitty employing a racial slur that was regrettably all-too-common during the Second World War): “They … they’ve dropped a second bomb,” Oppie said, holding her. […]

ANATOMICALLY CORRECT Kermit wishes he was.

In bacteria, the restart of stalled DNA replication forks requires the DNA helicase PriA. PriA can recognize and remodel abandoned DNA replication forks, unwind DNA in the 3'-to-5' direction, and facilitate the loading of the helicase DnaB onto the DNA to restart replication. Single-stranded DNA–binding protein (SSB) is typically present at the abandoned forks, but it is unclear how SSB and PriA interact, although it has been shown that the two proteins interact both physically and functionally. Here, we used atomic force microscopy to visualize the interaction of PriA with DNA substrates with or without SSB. These experiments were done in the absence of ATP to delineate the substrate recognition pattern of PriA before its ATP-catalyzed DNA-unwinding reaction. These analyses revealed that in the absence of SSB, PriA binds preferentially to a fork substrate with a gap in the leading strand. Such a preference has not been observed for 5'- and 3'-tailed duplexes, suggesting that it is the fork structure that plays an essential role in PriA's selection of DNA substrates. Furthermore, we found that in the absence of SSB, PriA binds exclusively to the fork regions of the DNA substrates. In contrast, fork-bound SSB loads PriA onto the duplex DNA arms of forks, suggesting a remodeling of PriA by SSB. We also demonstrate that the remodeling of PriA requires a functional C-terminal domain of SSB. In summary, our atomic force microscopy analyses reveal key details in the interactions between PriA and stalled DNA replication forks with or without SSB.

In bacteria, the restart of stalled DNA replication forks requires the DNA helicase PriA. PriA can recognize and remodel abandoned DNA replication forks, unwind DNA in the 3'-to-5' direction, and facilitate the loading of the helicase DnaB onto the DNA to restart replication. Single-stranded DNA–binding protein (SSB) is typically present at the abandoned forks, but it is unclear how SSB and PriA interact, although it has been shown that the two proteins interact both physically and functionally. Here, we used atomic force microscopy to visualize the interaction of PriA with DNA substrates with or without SSB. These experiments were done in the absence of ATP to delineate the substrate recognition pattern of PriA before its ATP-catalyzed DNA-unwinding reaction. These analyses revealed that in the absence of SSB, PriA binds preferentially to a fork substrate with a gap in the leading strand. Such a preference has not been observed for 5'- and 3'-tailed duplexes, suggesting that it is the fork structure that plays an essential role in PriA's selection of DNA substrates. Furthermore, we found that in the absence of SSB, PriA binds exclusively to the fork regions of the DNA substrates. In contrast, fork-bound SSB loads PriA onto the duplex DNA arms of forks, suggesting a remodeling of PriA by SSB. We also demonstrate that the remodeling of PriA requires a functional C-terminal domain of SSB. In summary, our atomic force microscopy analyses reveal key details in the interactions between PriA and stalled DNA replication forks with or without SSB.

In bacteria, the restart of stalled DNA replication forks requires the DNA helicase PriA. PriA can recognize and remodel abandoned DNA replication forks, unwind DNA in the 3'-to-5' direction, and facilitate the loading of the helicase DnaB onto the DNA to restart replication. Single-stranded DNA–binding protein (SSB) is typically present at the abandoned forks, but it is unclear how SSB and PriA interact, although it has been shown that the two proteins interact both physically and functionally. Here, we used atomic force microscopy to visualize the interaction of PriA with DNA substrates with or without SSB. These experiments were done in the absence of ATP to delineate the substrate recognition pattern of PriA before its ATP-catalyzed DNA-unwinding reaction. These analyses revealed that in the absence of SSB, PriA binds preferentially to a fork substrate with a gap in the leading strand. Such a preference has not been observed for 5'- and 3'-tailed duplexes, suggesting that it is the fork structure that plays an essential role in PriA's selection of DNA substrates. Furthermore, we found that in the absence of SSB, PriA binds exclusively to the fork regions of the DNA substrates. In contrast, fork-bound SSB loads PriA onto the duplex DNA arms of forks, suggesting a remodeling of PriA by SSB. We also demonstrate that the remodeling of PriA requires a functional C-terminal domain of SSB. In summary, our atomic force microscopy analyses reveal key details in the interactions between PriA and stalled DNA replication forks with or without SSB.

Manhattan Project (U.S.) -- History.

London : Dublin, 1843.

Boston : W.D. Ticknor, 1847.

Edinburgh : William Whyte, 1829.

Boston : A. Williams, 1870.

Carlsruhae : D.R. Marx, 1819.

Havniae : Typis N. Christensen, 1792.

London : J. & A. Churchill, 1887.

London : Printed by Mary Clark, and are to be sold by John Clark, at Mercers Chappel at the Lower End of Cheapside, MDCLXXVIII. [1678]

Erin E. Hecht
Sep 25, 2019; 39:7748-7758
BehavioralSystemsCognitive

Next-Generation Miniaturized Rubidium Atomic Clock Improves Performance and adds Features without Increasing Size

Christopher T. Richards and Enrico A. Eberhard

Muscle force-length dynamics are governed by intrinsic contractile properties, motor stimulation and mechanical load. Although intrinsic properties are well-characterised, physiologists lack in vitro instrumentation accounting for combined effects of limb inertia, musculoskeletal architecture and contractile dynamics. We introduce in vitro virtual-reality (in vitro-VR) which enables in vitro muscle tissue to drive a musculoskeletal jumping simulation. In hardware, muscle force from a frog plantaris was transmitted to a software model where joint torques, inertia and ground reaction forces were computed to advance the simulation at 1 kHz. To close the loop, simulated muscle strain was returned to update in vitro length. We manipulated 1) stimulation timing and, 2) the virtual muscle's anatomical origin. This influenced interactions among muscular, inertial, gravitational and contact forces dictating limb kinematics and jump performance. We propose that in vitro-VR can be used to illustrate how neuromuscular control and musculoskeletal anatomy influence muscle dynamics and biomechanical performance.

SUMMARY:

The cerebral ventricles have been studied since the fourth century BC and were originally thought to harbor the soul and higher executive functions. During the infancy of neuroradiology, alterations to the ventricular shape and position on pneumoencephalography and ventriculography were signs of mass effect or volume loss. However, in the current era of high-resolution cross-sectional imaging, variation in ventricular anatomy is more easily detectable and its clinical significance is still being investigated. Interpreting radiologists must be aware of anatomic variations of the ventricular system to prevent mistaking normal variants for pathology. We will review of the anatomy and development of the lateral ventricles and discuss several ventricular variations.