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Dexterous magnetic manipulation of ferromagnetic objects is well established, with three to six degrees of freedom possible depending on object geometry.sup.1. There are objects for which non-contact dexterous manipulation is desirable that do not contain an appreciable amount of ferromagnetic material but do contain electrically conductive material. Time-varying magnetic fields generate eddy currents in conductive materials.sup.2-4, with resulting forces and torques due to the interaction of the eddy currents with the magnetic field. This phenomenon has previously been used to induce drag to reduce the motion of objects as they pass through a static field.sup.5-8, or to apply force on an object in a single direction using a dynamic field.sup.9-11, but has not been used to perform the type of dexterous manipulation of conductive objects that has been demonstrated with ferromagnetic objects. Here we show that manipulation, with six degrees of freedom, of conductive objects is possible by using multiple rotating magnetic dipole fields. Using dimensional analysis.sup.12, combined with multiphysics numerical simulations and experimental verification, we characterize the forces and torques generated on a conductive sphere in a rotating magnetic dipole field. With the resulting model, we perform dexterous manipulation in simulations and physical experiments. Time-varying magnetic fields can be used to manipulate the position and orientation of conductive non-magnetic objects., Author(s): Lan N. Pham [sup.1] , Griffin F. Tabor [sup.2] , Ashkan Pourkand [sup.2] , Jacob L. B. Aman [sup.3] , Tucker Hermans [sup.2] [sup.4] , Jake J. Abbott [sup.1] [...]

The rational bottom-up synthesis of atomically defined graphene nanoribbon (GNR) heterojunctions represents an enabling technology for the design of nanoscale electronic devices. Synthetic strategies used thus far have relied on the random copolymerization of two electronically distinct molecular precursors to yield GNR heterojunctions. Here we report the fabrication and electronic characterization of atomically precise GNR heterojunctions prepared through late-stage functionalization of chevron GNRs obtained from a single precursor. Post-growth excitation of fully cyclized GNRs induces cleavage of sacrificial carbonyl groups, resulting in atomically well-defined heterojunctions within a single GNR. The GNR heterojunction structure was characterized using bond-resolved scanning tunnelling microscopy, which enables chemical bond imaging at T = 4.5 K. Scanning tunnelling spectroscopy reveals that band alignment across the heterojunction interface yields a type II heterojunction, in agreement with first-principles calculations. GNR heterojunction band realignment proceeds over a distance less than 1 nm, leading to extremely large effective fields.

Objectives: To evaluate the prevalence of bacterial presence in free‐catch urine samples preceded by either a standardised prepped ("clean‐catch") protocol versus unprepped (non‐cleaned) voiding. Materials and Methods: The study was a single‐centre prospective single‐blinded randomised controlled trial. Urine samples were obtained from 100 client‐owned dogs presenting for routine evaluation. Dogs were randomly assigned to either the prepped group (preputial or peri‐vulvar area cleaned with sterile saline before collection) or the unprepped group (no preliminary cleansing) stratified by sex. Urinalysis and urine culture (blood and MacConkey agar) were performed on all samples. Significant bacterial presence on urine culture was defined as >104 colony forming units (CFU)/mL. Results: There were no statistically significant associations between prepped versus unprepped collection method or sex with a urinalysis positive for bacteriuria. However, on culture, significant bacterial growth was almost five times more likely to be associated with males relative to females (odds ratio 4.59, 95% confidence interval 1.61 to 13.10). The probability of finding a positive culture was not statistically associated with prep method (odds ratio 1.43, 95% confidence interval 0.50 to 4.08). Clinical Significance: For the majority of dogs without clinical signs of urinary tract infection, free‐catch urine collection does not result in significant bacteriuria found on analysis or culture. The presence of bacteria found in free‐catch samples may be secondary to sample contamination or subclinical bacteriuria. Sample contamination or subclinical bacteriuria may be more prevalent in male dogs. [ABSTRACT FROM AUTHOR]

We report a scanning tunneling microscopy and noncontact atomic force microscopy study of close-packed 2D islands of tetrafluorotetracyanoquinodimethane (F4TCNQ) molecules at the surface of a graphene layer supported by boron nitride. While F4TCNQ molecules are known to form cohesive 3D solids, the intermolecular interactions that are attractive for F4TCNQ in 3D are repulsive in 2D. Our experimental observation of cohesive molecular behavior for F4TCNQ on graphene is thus unexpected. This self-assembly behavior can be explained by a novel solid formation mechanism that occurs when charged molecules are placed in a poorly screened environment. As negatively charged molecules coalesce, the local work function increases, causing electrons to flow into the coalescing molecular island and increase its cohesive binding energy.

Owing to its relativistic low-energy charge carriers, the interaction between graphene and various impurities leads to a wealth of new physics and degrees of freedom to control electronic devices. In particular, the behavior of graphene's charge carriers in response to potentials from charged Coulomb impurities is predicted to differ significantly from that of most materials. Scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) can provide detailed information on both the spatial and energy dependence of graphene's electronic structure in the presence of a charged impurity. The design of a hybrid impurity-graphene device, fabricated using controlled deposition of impurities onto a back-gated graphene surface, has enabled several novel methods for controllably tuning graphene's electronic properties. Electrostatic gating enables control of the charge carrier density in graphene and the ability to reversibly tune the charge and/or molecular states of an impurity. This paper outlines the process of fabricating a gate-tunable graphene device decorated with individual Coulomb impurities for combined STM/STS studies. These studies provide valuable insights into the underlying physics, as well as signposts for designing hybrid graphene devices.

Objectives : To quantify the effects of wellness examinations conducted in the common treatment area on fear, anxiety and stress indicators in client‐owned dogs. Materials and Methods : The study was a prospective, non‐blinded, randomised, two‐period two‐treatment crossover trial. Client‐owned healthy adult dogs presenting for wellness or dental evaluations at a single veterinary teaching hospital received three consecutive rapid assessment exams; a baseline exam (owner present), followed by two identical physical exams differing in location and presented in random order (isolated exam room with owner present versus common treatment area, owner absent). Primary endpoints were a cumulative fear, anxiety and stress score for five standardised behaviours and heart rate (bpm) measured for each exam. Results : Forty‐four dogs were enrolled. Modal fear, anxiety and stress score at baseline was 1 of 5, indicating none to mild stress. Both fear, anxiety and stress and heart rates measured in the common treatment area were clinically elevated relative to assessments conducted in the exam room. Relative to baseline, animals examined in the common treatment area showed increased fear, anxiety and stress (+2.6 units, se 0.5; P<0.0001) and heart rate (20 bpm, 95% confidence interval 13, 28; P<0.0001. Twenty‐eight dogs (64%) exhibited fear, anxiety and stress scores ≥3 of 5 (moderate to severe stress) in the common treatment area, compared to 19 (43%) during exam room assessments. Clinical Significance : Stress assessments in this study may have been biased by inability to blind assessors to location. However, stress metrics showed clinically significant, consistent and directionally symmetrical increases when dogs were examined in the common treatment area. When physical exam locations are highly stimulating, dogs may experience increased stress and anxiety, with detrimental effects on clinical assessments and behavioural welfare. Whenever possible, physical exams and procedures should take place in low‐stress environments with the owner present. [ABSTRACT FROM AUTHOR]