Mass Chain Research Articles

Polymethacrylamide—An underrated and easily accessible upper critical solution temperature polymer: Green synthesis via photoiniferter reversible addition–fragmentation chain transfer polymerization and analysis of solution behavior in water/ethanol mixtures

AbstractWithin the group of stimuli‐responsive, “smart” materials, upper critical solution temperature (UCST) polymers remain sparsely investigated. Thus, this work focusses on a vastly ignored UCST polymer: polymethacrylamide (PMAAm). A cost‐efficient photoiniferter reversible addition–fragmentation chain transfer (RAFT) polymerization yielding narrowly dispersed (Đ < 1.1) PMAAm is presented. This PMAAm exhibits highly thermoreversible UCST‐type phase transitions (PT) in water/ethanol mixtures (ethanol content: 17–35 wt%) which are investigated via temperature dependent dynamic light scattering (DLS). Apart from the ethanol content, the PT temperature is affected by polymer mass fraction and chain length and varies between 10–80 °C depending on the three mentioned parameters. Lastly, PMAAm's propensity towards amide hydrolysis and concomitant PT‐suppression is investigated. Below temperatures of 40 °C, PMAAm solutions show no sign of amide hydrolysis for at least three days, however, if heated to 70 °C, the thermoresponsiveness gradually degrades within hours.

Evaluation of fission product yields and associated covariance matrices

ABSTRACT The independent and cumulative fission product yields (FPYs) and their covariance matrices were newly evaluated for thermal- and fast-neutron induced fission and spontaneous fission. We principally evaluated the independent isobaric charge distributions by taking account of available experimental data, especially putting emphasis on the shell and even-odd staggering in the fission yields by applying a Boltzmann factor including the shell and the pairing correction energies for the mass of fission products. Furthermore, the isomeric ratios of FPY were obtained by a systematic calculation based on the Hauser-Feshbach theory. Normalization of the FPY and associated covariance matrices of independent FPY were determined based on the generalised least-square method to make them consistent with important physical constraints. Especially, the FPYs were normalized to be consistent with the mass chain yield of England and Rider. The cumulative FPYs were calculated by following the relevant -decay chain by using the decay data from JENDL/DD-2015. Finally, we verified the FPYs evaluated presently by considering experimental decay heats, delayed neutron yields, aggregate antineutrino spectra, and results from post-irradiation examination. All the results have shown that the present set of FPYs were consistent with these data and free from trivial problems present in JENDL/FPY-2011.

Dynamics of an orbital siphon anchored to a rotating ellipsoidal asteroid for resource exploitation

This paper investigates the dynamics of an orbital siphon anchored to a rotating ellipsoidal asteroid. The siphon is a chain of tether-connected payload masses arranged vertically from the asteroid surface, envisaged for propellantless delivery of payloads (e.g., mined material) from the asteroid surface to a collecting spacecraft. If the structure is long enough, the centrifugal-induced force can overcome the gravitational force on the payloads, eventually allowing resource payloads to escape. By connecting new payloads at the bottom of this chain while removing upper payloads a net orbital siphon effect is established, which provides a net continuous flow of resources from the asteroid surface to a collecting spacecraft, attached at the top of the siphon. The dynamics of the siphon is investigated in detail by varying a set of relevant parameters, in particular, chain length, anchor location and asteroid shape. It is shown that the system exhibits oscillatory behaviour in the equatorial plane, with decreasing oscillation amplitude over time and that the longest equatorial end is the best anchor location to guarantee proper siphon operation while minimizing the chain length. Eventually, a method is proposed to exploit the equatorial Coriolis-induced oscillations of the siphon to transfer payload masses from the collecting spacecraft to the stable equilibrium points associated with the effective potential of the ellipsoidal asteroid, where a catcher would collect the material.

Nonstandard continualization of 1D lattice with next-nearest interactions. Low order ODEs and enhanced prediction of the dispersive behavior

In this article, different standard and nonstandard continualization techniques are applied to a one-dimensional solid consisting in a chain of masses interacting with nearest and next-nearest neighbors through linear springs. The study focuses on the reliability of the different continua in capturing the dispersive behavior of the discrete, on the order of the continuous governing equation because of its effect on the need for including nonclassical boundary conditions, as well as on the physical inconsistencies that appear for short wavelengths. The Regularization method, used by Bacigalupo and Gambarotta for a lattice with nearest interactions, presents advantages over the others.

Dynamics of a Nonrigid Orbital Siphon at a Near-Earth Asteroid

The orbital siphon is a novel concept for propellantless payload transfer from the surface of a rotating body to orbit. In the context of asteroid mining, the orbital siphon represents an efficient solution to deliver mined material from the asteroid surface to an orbiting station for later processing or storage. The key idea is that the centrifugal-induced force exerted on a tether-connected chain of payload masses assembled from the surface of a rotating body can be large enough to pull the lower masses to initialize an orbital siphon effect: new payloads are connected to the chain while upper payloads are removed. In this paper, the dynamics of an orbital siphon anchored to two irregularly shaped near-Earth asteroids is investigated. The siphon is modeled as a closed chain of tether-connected buckets kept taut by two pulleys: one at the asteroid surface and one attached to an orbiting collecting spacecraft. Buckets are filled with asteroid material to be delivered to the collecting spacecraft. It is shown that the irregularities of the gravitational field do not introduce instabilities to the orbital siphon system for the scenarios presented in this paper. Without any braking mechanism required, the average speed of the siphon does not diverge but reaches a constant value at a steady state. Moreover, it is shown that the siphon effect is still generated when the anchor moves on the asteroid surface, allowing the mining location to be moved without interrupting the flow of material to the collecting spacecraft.

Nonlinear Oscillations of a Chain of Masses in a Liquid

Nonlinear regular and random vibrations of a metamaterial made as a chain of massive elements immersed in a viscous liquid are studied. The nearest neighbors are connected by nonlinear elastic forces. Stokes friction is taken into account. A system of equations for mass oscillations is obtained. In the continuum long-wave approximation, the system is reduced to a simplified partial differential equation with nonlinear and dissipative terms. We find the exact solutions and show that the competition of nonlinearity and absorption can lead to the formation of a steady wave profile shape. For noise waves, the correlation function and intensity spectrum are given. The process of sawtooth wave excitation by distributed external sources is analyzed. The limiting “peak” amplitude is calculated. Waves in tubes of variable cross section filled with metamaterial are considered. Based on the solution of the equation containing coordinate-dependent tube section, an expression is found for the amplitude of the sawtooth wave.

Microscopic study of nuclear structure dynamics of neutron-deficient even–even 100–110Cd isotopes within the framework of projected shell model

We have studied the deformation systematics of [Formula: see text] and [Formula: see text] values, yrast spectra, band structure and backbending phenomena in the neutron-deficient even–even [Formula: see text]Cd isotopes within the projected shell model (PSM) framework. The observations of the systematics of [Formula: see text] and [Formula: see text] values for [Formula: see text]Cd isotopes are well reproduced in present calculations. Our observations show that, as we move from [Formula: see text]Cd to [Formula: see text]Cd, the deformation increases and then it reduces up to [Formula: see text]Cd. This gives us a confirmation that [Formula: see text]Cd is the most deformed nucleus in this set of isotopic mass chain. The backbending phenomena is also observed in these isotopes, which can be related to the crossing of ground band (g-band) by 2-quasiparticle (qp) bands or s-bands. The pseudomagic character of [Formula: see text]Cd has also been observed.

Microscopic study of shape evolution and ground state properties in even-even Cd isotopes using covariant density functional theory

We have studied the trend of ground state quadrupole deformation and shape transition in even-even 96−136Cd isotopes. Binding energy, two neutrons separation energies, shell closure parameter, rms radii of neutron and proton, charge radii, and nuclear skin thickness have also been studied as a function of the neutron number. We performed the calculations by employing covariant density functional theory with density-dependent meson exchange and point coupling interactions. The ground-state properties are found in good agreement with available experimental data. Our results predict the shape transition from spherical to prolate, prolate to oblate, oblate to prolate, and prolate to spherical in this isotopic mass chain. Besides, the oblate-prolate shape coexistence is also predicted in 110−114Cd isotopes.

Cancer Cachexia Induces Preferential Skeletal Muscle Myosin Loss When Combined With Denervation.

Patients with cancer cachexia (CCX) suffer from muscle wasting, which is often but not always accompanied by selective loss of myosin. Here we examined the effects of CCX on muscle mass and myosin heavy chain (MyHC) expression in denervated (DEN) muscles, especially focusing on the protein synthesis and degradation pathways. Male CD2F1 mice were randomly divided into control (CNT) and CCX groups and their left sciatic nerve was transected. CCX was induced by an intraperitoneal injection of colon 26 cells. After 14 days, the serum concentration of IL-6 and corticosteroid was higher in CCX mice than in CNT mice. The combination of CCX with DEN (CCX + DEN) resulted in a marked reduction of the gastrocnemius muscle weight (−69%) that was significantly lower than DEN (−53%) or CCX (−36%) alone. CCX had no effect on MyHC content, but it elicited a preferential MyHC loss when combined with DEN. The expression levels of autophagy markers cathepsin D and LC3BII/I ratio were markedly higher in the CCX + DEN group than in the CNT + DEN and the CCX groups. Paradoxically, there was an increase in protein synthesis rate and phosphorylation levels of p70S6K and rpS6, markers of mTORC1 signaling, in the CNT + DEN group, and these molecular alterations were inhibited in the CCX + DEN group. Our data indicate that CCX aggravates muscle atrophy in DEN muscles by inducing seletive loss of myosin, which involves inactivity dependent mechanisms that is likely to be a consequence of increased autophagy-mediated protein breakdown coupled with impaired protein synthesis.

DPYSL2 is a novel regulator for neural stem cell differentiation in rats: revealed by Panax notoginseng saponin administration

BackgroundThe limited neuronal differentiation of the endogenous or grafted neural stem cells (NSCs) after brain injury hampers the clinic usage of NSCs. Panax notoginseng saponins (PNS) were extensively used for their clinical value, such as in controlling blood pressure, blood glucose, and inhibiting neuronal apoptosis and enhancing neuronal protection, but whether or not it exerts an effect in promoting neuronal differentiation of the endogenous NSCs is completely unclear and the potential underlying mechanism requires further exploration.MethodsFirstly, we determined whether PNS could successfully induce NSCs to differentiate to neurons under the serum condition. Mass spectrometry and quantitative polymerase chain reaction (Q-PCR) were then performed to screen the differentially expressed proteins (genes) between the PNS + serum and serum control group, upon which dihydropyrimidinase-like 2 (DPYSL2), a possible candidate, was then selected for the subsequent research. To further investigate the actual role of DPYSL2 in the NSC differentiation, DPYSL2-expressing lentivirus was employed to obtain DPYSL2 overexpression in NSCs. DPYSL2-knockout rats were constructed to study its effects on hippocampal neural stem cells. Immunofluorescent staining was performed to identify the differentiation direction of NSCs after 7 days from DPYSL2 transfection, as well as those from DPYSL2-knockout rats.ResultsSeven differentially expressed protein spots were detected by PD Quest, and DPYSL2 was found as one of the key factors of NSC differentiation in a PNS-treated condition. The results of immunostaining further showed that mainly Tuj1 and GFAP-positive cells increased in the DPYSL2-overexpressed group, while both were depressed in the hippocampal NSCs in the DPYSL2-knockout rat.ConclusionsThe present study revealed that the differentiation direction of NSCs could be enhanced through PNS administration, and the DPYSL2 is a key regulator in promoting NSC differentiation. These results not only emphasized the effect of PNS but also indicated DPYSL2 could be a novel target to enhance the NSC differentiation in future clinical trials.

Post-neutron mass chain yield distribution in the thermal neutron induced fission of $$^{{{229}}}\text {Th}$$

Post-neutron mass chain yield distribution in the thermal neutron induced fission of $$^{{{229}}}\text {Th}$$

Nuclear Data Sheets for A = 90

The experimental results from the various reaction and decay studies leading to nuclides in the A = 90 mass chain have been reviewed. These data are summarized and presented, together with the adopted level schemes and properties, for the nuclides from Ge(Z = 32) through Pd(Z = 46). This evaluation replaces the previous evaluation by E. Browne, which appeared in Nuclear Data Sheets 82, 379 (1998).

Micro and macroscopic mechanical behaviors of high-density polyethylene under UV irradiation and temperature

The macroscopic mechanical behavior of high-density polyethylene (HDPE) during photodegradation is characterized by decreases of tensile elongation-at-failure. An apparent linear relation between the elongation-at-failure and the molar mass indicates that the decrease of the elongation of HDPE over time is highly dependent on the decrease of the average molar mass. Possible preferential scission of the high molar mass chains was observed for HDPE exposed to ultraviolet (UV) irradiance higher than 40% (61 W/m2) of the full intensity at 50 °C. Tensile modulus of HDPE exposed at 50 °C increased with the exposure time until reaching the complete loss of ductility except the 5% UV. For 40% UV/30 °C as well as for 5% UV/50 °C, the young modulus trend cannot be evaluated with performed (small) duration. Nanomechanical test results suggest that the increased tensile modulus is due to stiffening of the entire cross-section. Furthermore, HDPE showing the complete loss of ductility exhibited significantly higher modulus in the surface regions than the core regions particularly for the UV intensity higher than 40% (61 W/m2), which increased crack sensitivity to cause embrittlement of the entire specimens.

Nuclear Data Sheets for A=98

Experimental spectroscopic data on nuclear structure and decay are evaluated for known nuclides of mass 98 (Br, Kr, Rb, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In). Detailed evaluation results of individual reactions and decays are presented together with the Adopted values that are recommended for level properties, γ and β radiations, and other spectroscopic information. 98Mo remains as the most extensively studied nuclide via various reactions and decays. Level schemes of Sr, Y, Zr, Tc, and Pd nuclides in this mass chain are also well established to date; while Kr, Rb, Nb, Ag and Cd are amongst the least-studied ones for excited states, with only limited data available for each. On the neutron-rich side, 98Br has been identified in the 9Be(238U,F) reaction, but no spectroscopic data are yet available, while for 98In on the proton-rich side, only the ground state and an isomer are known with half-lives measured but their spin-parities and the absolute level energy of the isomer yet to be determined. While 98Ru and 98Rh have also been extensively studied, large discrepancies exist between the high-spin sections of the proposed level schemes in different measurements, and these need to be clarified and resolved with further experimental investigations to improve the currently-adopted ones, which have been selected from the measurements with higher statistics, considering no other criteria of preference. This work supersedes all the earlier evaluations of A=98 (2003Si07, 1998Si18, 1992Si21, 1983Mu21, 1974Me34).

Solubility and loading ability of benzene derivative drugs onto viscose substrate in supercritical carbon dioxide and their release behavior in solvent

An investigation of the solubility and loading ability (LA) of nine benzene derivative drugs with different chemical structures onto viscose substrate in supercritical carbon dioxide fluid (SCF–CO2) was performed, in order to construct some bases at the first time for manufacturing drug-loaded cosmetic textiles by employing an ecofriendly, sustainable supercritical methodology. Moreover, a release behavior of each of the loaded drugs from viscose substrate in a solvent of ethanol was also disclosed. The results show that a more hydrophobicity of the substituent group linked on the benzene ring readily led to a higher solubility in SCF-CO2, while an overlong aliphatic tail and its molar mass also brought some effects on its dissolving behavior. As for the isomer drugs, the locations of a methoxy group (-O-CH3) at the ortho-position to the carboxyl group (-(CO)–OH) in the benzene ring resulted in the highest solubility, while a para-position showed the lowest solubility in SCF-CO2. The loading ability (LA) for most of the tested drugs mainly depended on their solubilities in SCF-CO2, and was also affected by the interactions between the drug and viscose substrate. The investigation of drug release reveals that the LA played a predominant role in the release behaviors of the tested drugs with different substituent groups, molar mass or aliphatic chains and isomer structures. Moreover, the drug molecular size and its interaction with viscose substrate also presented effects on the subsequent release behaviors in the utilized release system and conditions.

IMPACT OF THE FOURTH INDUSTRIAL REVOLUTION ON EDUCATION AND THE PRINCIPALS’ CHALLENGES

The digital revolution led to the birth of the Fourth Industrial Revolution, which opened new, unlimited areas of creativity and innovation in various scientific fields. It has created a set of new technologies that combine three key elements: physical, digital, and biological, to produce unprecedented rapid variables in human life. The problem is that this revolution created the challenges facing all organizations and institutions, including educational institutions, when it imposed requirement of highly efficient, the education is required to keep abreast of technological developments, while today's schools are in dire need of further development and innovation in the world Fast changing. Therefore, the school faces many problems through a flood of new information accelerated according to the rapid changes, and need to be creative and more comprehensive assimilation of modern technology. Through the descriptive and analytical approach, the subject was discussed in three sections, first: the dimensions of the fourth industrial revolution. Second: the use of modern technology in schools of basic education, and finally the challenges facing school principals. The findings showed that: The Fourth Industrial Revolution constituted technological breakthroughs, such as artificial intelligence, cybersecurity, biotechnology, and the mass chain. These technologies have challenged all societies in how to exploit these opportunities. Educational institutions must develop. There was a need for quality graduates characterized by creative thinking, innovative production and adaptation to innovations and inventions. As such, school principals have had many burdens and responsibilities to employ maximum creative management skills to keep pace with scientific and technological progress. The need for an innovative and effective school administration capable of managing change and employing technology in administrative work. Keywords modern technology, education, challenges, principals

Non-Reciprocal Wave Transmission in a Bilinear Spring-Mass System

Abstract Significant amplitude-independent and passive non-reciprocal wave motion can be achieved in a one-dimensional (1D) discrete chain of masses and springs with bilinear elastic stiffness. Some fundamental asymmetric spatial modulations of the bilinear spring stiffness are first examined for their non-reciprocal properties. These are combined as building blocks into more complex configurations with the objective of maximizing non-reciprocal wave behavior. The non-reciprocal property is demonstrated by the significant difference between the transmitted pulse displacement amplitudes and energies for incidence from opposite directions. Extreme non-reciprocity is realized when almost-zero transmission is achieved for the propagation from one direction with a noticeable transmitted pulse for incidence from the other. These models provide the basis for a class of simple 1D non-reciprocal designs and can serve as the building blocks for more complex and higher dimensional non-reciprocal wave systems.

Flexural Wave Propagation in Mass Chain-Filled Carbon Nanotubes.

The propagation characteristics of terahertz (THz) flexural waves in mass chain-filled single-walled carbon nanotubes (MCSCs) are studied using a continuum mechanics approach and molecular dynamics (MD) simulations, where each single-walled carbon nanotube (SWCNT) is modeled as a nonlocal Timoshenko beam based on the nonlocal strain gradient theory. The effect of the surrounding elastic medium and the van der Waals (vdW) interactions between the mass chain and the SWCNT on the wave propagation is quantitatively considered in governing equations, respectively. The analytical expressions of two flexural wave branches and the bandgap between the two branches are derived. When combining our MD simulations of the carbon-atom chain-filled SWCNT, the wave within the bandgap disperses rapidly, and the mass chain has a significant influence on the phase velocity of the flexural wave. The present theoretical solution has a high accuracy in a wide frequency range up to the THz region. In particular, the surrounding elastic medium of the MCSCs remarkably affects the phase velocity for low frequencies, but not for high frequencies. The present study indicates that the wave propagation of a SWCNT could be modulated by changing the filled mass chain and the surrounding elastic medium.

Effect of Block Medium Parameters on Energy Dissipation

This paper describes energy distribution in a block medium simulated by a one-dimensional chain of masses joined by springs and dampers. Equations describing the motion of masses are solved by the methods of the theory of ordinary differential equations. The effect of the block medium parameters on energy dissipation is investigated. An approximate analytical solution is obtained that describes the total energy of a block medium at large values of time.

Stick-slip kinetics in a bistable bar immersed in a heat bath

Structural transitions in some rod-like biological macromolecules under tension are known to proceed by the propagation through the length of the molecule of an interface separating two phases. A continuum mechanical description of the motion of this interface, or phase boundary, takes the form of a kinetic law which relates the thermodynamic driving force across it with its velocity in the reference configuration. For biological macromolecules immersed in a heat bath, thermally activated kinetics described by the Arrhenius law is often a good choice. Here we show that ‘stick-slip’ kinetics, characteristic of friction, can also arise in an overdamped bistable bar immersed in a heat bath. To mimic a rod-like biomolecule we model the bar as a chain of masses and bistable springs moving in a viscous fluid. We conduct Langevin dynamics calculations on the chain and extract a temperature dependent kinetic relation by observing that the dissipation at a phase boundary can be estimated by performing an energy balance. Using this kinetic relation we solve boundary value problems for a bistable bar immersed in a constant temperature bath and show that the resultant force-extension relation matches very well with the Langevin dynamics results. We estimate the force fluctuations at the pulled end of the bar due to thermal kicks from the bath by using a partition function. We also show rate dependence of hysteresis in cyclic loading of the bar arising from the stick-slip kinetics. Our kinetic relation could be applied to rod-like biomolecules, such as, DNA and coiled-coil proteins which exhibit structural transitions that depend on both temperature and loading rate.