Advancement in fabrication of carbon nanotube tip for atomic force microscope using multi-axis nanomanipulator in scanning electron microscope

We have constructed a new nanomanipulator (NM) in a field emission scanning electron microscope (FE-SEM) to fabricate carbon nanotube (CNT) tip to precisely adjust the length and attachment angle of CNT onto the mother atomic force microscope (AFM) tip. The new NM is composed of 2 modules, each of which has the degree of freedom of three-dimensional rectilinear motion x, y and z and one-dimensional rotational motion θ. The NM is mounted on the stage of a FE-SEM. With the system of 14 axes in total which includes 5 axes of FE-SEM and 9 axes of nano-actuators, it was possible to see CNT tip from both rear and side view about the mother tip. With the help of new NM, the attachment angle error could be reduced down to 0º as seen from both the side and the rear view, as well as, the length of the CNT could be adjusted with the precision using electron beam induced etching. For the proper attachment of CNT on the mother tip surface, the side of the mother tip was milled with focused ion beam. In addition, electron beam induced deposition was used to strengthen the adhesion between CNT and the mother tip. In order to check the structural integrity of fabricated CNT, transmission electron microscope image was taken which showed the fine cutting of CNT and the clean surface as well. Finally, the performance of the fabricated CNT tip was demonstrated by imaging 1-D grating and DNA samples with atomic force microscope in tapping mode.

Smartphone and teamwork as a methodological tool for teaching and learning physics

This research is based on the usefulness of mobile phones as a tool for students to learn about uniform rectilinear motion in vertical free fall, based on experimental practice. To evaluate whether these mobile devices allow better learning on the subject, a pre-test/post-test design was carried out with 43 students participating in the 9th grade in natural sciences. McNemar and Stuart-Maxwell non-parametric tests were applied. The proposal on the experimental practice gave satisfactory results when comparing the pre-test and post-test, in the analysis of the particular and global form of the answers.

Difficulties in the interpretation of kinematics graphs in secondary basic education students

This research reports the findings derived from the identification of the difficulties exhibited by a group of 76 students from different grades of basic secondary education in a private educational institution with an emphasis on science education. The students were given a questionnaire presenting five situations based on the Position-Time graph associated with uniform rectilinear motion of particles. The research approach is of a quantitative nature at a descriptive level with a field design, since it was the students who filled in the instrument. It is highlighted as a finding in the opinion of the students that the subject has been seen in class, but due to the teacher’s methodology it is not fully understood by them. The results show that the students have a long list of difficulties mainly due to the lack of articulation of mathematical concepts in physical contexts, a situation that prevents them from analyzing the proposed statements, reasoning about the approaches, and improving in the process of searching for alternative solutions with clear arguments.

Does a container of ideal gas increase in temperature when accelerated and stopped?

An insulated container consisting of two ideal gas atoms are used. It is shown using rectilinear motion and elastic collisions with the walls of the container how the root mean square speed of the atoms change during acceleration of the container and after the container comes to a sudden stop.

Nature’s Perfection: Aristotle and Descartes on Motion and Purpose

Descartes holds that, insofar as nature is a purposeless, unthinking, extended substance, there could be no final causes in physics. Descartes’ derivation of his three laws of motion from the perfections of God thus underwrites a rejection of Aristotle’s conception of natural self-motion and teleology. Aristotle derived his conception of the purposeful action of sublunar creatures from his notion that superlunar bodies are perfect, eternal, living beings, via the thesis that circular motion is more complete or perfect than rectilinear motion. Descartes’ reduction of circular motion to rectilinear motion, achieved through his theological foundation of the laws of motion, thus marks a crucial break from Aristotle’s philosophy of nature. This paper argues that the shift from the Aristotelian conception of nature as self-moving and teleological to the Cartesian conception of nature as purposeless and inert, is not an empirical discovery but is rooted in differing conceptions of where perfection lies in nature.

A family of novel compliant linear-motion mechanisms based on compliant rolling-contact element pivot

Compliant linear-motion mechanisms are of great use in precision machines, due to their excellent performances such as infinite resolution and low cost. The accuracy of the mechanisms is an important consideration for mechanical design in applications, especially in the case of large working load. Considering that COmpliant Rolling-contact Element (CORE) pivot is characterized with high bearing capacity, the paper adopts it as a building block to design a family of compliant linear-motion mechanisms for applications of heavy load. These mechanisms are achieved by replacing four rigid pivots in a parallel four-bar mechanism with CORE pivots, and the motion accuracy is improved by means of contacting surfaces design of four CORE pivots. Firstly, structures of CORE pivot are introduced and five extended arrangements for bearing heavy load are presented. Meanwhile, motion for the CORE pivot is analyzed and preconditions for achieving a pure roll are discussed. Then, configuration of the compliant linear-motion mechanisms constructed by CORE pivots is obtained, and kinematics of the mechanisms is analyzed and parametric design condition for rectilinear motion is modeled. Based on the condition, detailed topological structures of the mechanisms are designed. Finally, motion simulations and experiment tests are implemented to verify accuracy of the proposed mechanisms. The results demonstrate that the mechanisms proposed in this paper are capable of offering a high-precision linear motion and providing a promising application prospect in precision machines.

Theoretical Thermal-Mechanical Modelling and Experimental Validation of a Three-Dimensional (3D) Electrothermal Microgripper with Three Fingers

This paper presents the theoretical thermal-mechanical modeling and parameter analyses of a novel three-dimensional (3D) electrothermal microgripper with three fingers. Each finger of the microgripper is composed of a bi-directional Z-shaped electrothermal actuator and a 3D U-shaped electrothermal actuator. The bi-directional Z-shaped electrothermal actuator provides the rectilinear motion in two directions. The novel 3D U-shaped electrothermal actuator offers motion with two degrees of freedom (DOFs) in the plane perpendicular to the movement of the Z-shaped actuator. As a result, each finger possesses 3D mobilities with three DOFs. Each beam of the actuators is heated externally with polyimide films. In this work, the static theoretical thermal-mechanical model of the 3D U-shaped electrothermal actuator is established. Finite-element analyses and experimental tests are conducted to verify and validate the model. With this model, parameter analyses are carried out to provide insight and guidance on further improving the 3D U-shaped actuator. Furthermore, a group of micro-manipulation experiments are conducted to demonstrate the flexibility and versality of the 3D microgripper on manipulate different types of small/micro-objects.

A novel method to assess the spatiotemporal image quality in fluoroscopy

Objectives. The planar formulation of the noise equivalent quanta (NEQ) and detective quantum efficiency (DQE) used to assess the image quality of projection images does not deal with the influence of temporal resolution on signal blurring and image noise. These metrics require correction factors based on temporal resolution when used for dynamic imaging systems such as fluoroscopy. Additionally, the standard NEQ and detector DQE are determined on pre-processed images in scatter-free conditions for effective energies produced by additional aluminium or copper filters that are not representative of clinical fluoroscopic procedures. In this work, we developed a method to measure “frame NEQ” and “frame system DQE” which include the temporal frequency bandwidth and consider the anti-scatter grid, the detector and the image processing procedures for beam qualities with scatter fractions representative of clinical use. Approach. We used a solid water phantom to simulate a patient and a thin copper disc to measure the spatial resolution. The copper disc, set in uniform rectilinear motion in the image plane, assessed the temporal resolution. These new metrics were tested on two fluoroscopy systems, a C-arm and a floor-mounted cardiology, for multiple parameters: phantom thicknesses from 5 to 20 cm, frame rates from 3 to 30 fps, spatial and temporal image processing of different weights. Main results. The frame NEQ correctly described the image quality for different scatter conditions, temporal resolutions and image processing techniques. The frame system DQE varied between 0.38 and 0.65 within the different beam and scatter conditions, and correctly mitigated the influence of spatial and temporal image processing. Significance. This study introduces and validates an unbiased formulation of in-plane NEQ and system DQE to assess the spatiotemporal image quality of fluoroscopy systems.

Characteristics of biochemical indicators of sperm production of carp males while using naked oats in the nutrition process during pre-sprawning period

In the research there have been used males of the Nyvka intra-breed type of the Ukrainian scaly carp breed, which were kept during the pre-spawning period in the pond conditions of the State Enterprise “Experimental fish farm Nyvka” within the Institute of Fisheries of the National Academy of Agrarian Sciences of Ukraine (IFNAASU). The carps were divided into 3 groups. The first group (Experiment I) was fed 100 % naked oats, the second (Experiment II) – 30 %, the control group of fish (Control) was fed a grain mixture. The quality of sexual products of male carp was assessed by determining the effect of adding naked oats to their diet during the pre-spawning period. Indicators of sperm motility and fertilizing ability, content of γ-, β- and α-globulins, albumin, prealbumin, and physiological characteristics of ejaculates of respiratory and regenerative capacity, activity of enzymes of respiratory chain of mitochondria (CHO and SDG) were studied. Given the increased productivity of fish sperm, in particular the increase in the number of sperm with rectilinear motion, decrease in the number of inanimate sperm and changes in the protein formula of germ cells, it is advisable to add naked oats to the main diet in the amount of 30 %.