Efficient reconfiguration of lattice-based modular robots

Modular robots consist of many identical units (or atoms) that can attach together and perform local motions. By combining such motions, one can achieve a reconfiguration of the global shape of a robot. The term modular comes from the idea of grouping together a fixed number of atoms into a metamodule, which behaves as a larger individual component. Recently, a fair amount of research has focused on algorithms for universal reconfiguration using Crystalline and Telecube metamodules, which use expanding/contracting cubical atoms.From an algorithmic perspective, this work has achieved some of the best asymptotic reconfiguration times under a variety of different physical models. In this paper we show that these results extend to other types of modular robots, thus establishing improved upper bounds on their reconfiguration times. We describe a generic class of modular robots, and we prove that any robot meeting the generic class requirements can simulate the operation of a Crystalline atom by forming a six-arm structure. Previous reconfiguration bounds thus transfer automatically by substituting the six-arm structures for the Crystalline atoms. We also discuss four prototyped robots that satisfy the generic class requirements: M-TRAN, SuperBot, Molecube, and RoomBot.     

Propagation of Lamb waves in an immersed periodically grooved plate: Experimental detection of the scattered converted backward waves

Guided waves propagation in immersed plates with irregular surfaces has potential application to detection and assessment of the extent, depth and pattern of the irregularity. The complexity of the problem, due to the large number of involved parameters, has limited the number of existing studies. The simplest case of irregularities of practical interest is the two-dimensional corrosion profile. Even this case is in general so complex, that one can extract several amplitude dominant periodic surfaces only by using a Fourier spectrum of the surface. Guided waves in plates, with one or both free surfaces having periodic perturbations of different shapes, have been presented in specialized literature.     

Fundamentals of designing cylindrical high-order transformation optics invisibility cloaks using silver–silica metamaterials

Metamaterials have effective properties that are distinct from their composites as they consist of engineered-designed properties that are not in nature. In order to be able to design a metamaterial, we should establish sufficient understanding of the properties of the constituents. This will enable us to engineer new effective parameters of the metamaterial. We shall perform a detailed analytical study for the effective parameters and the constituents’ parameters of silver–silica metamaterial. This will define the optical response of the mixture at different sizes of the inclusions’ and different volume fractions of the silver and silica. Also an optimum value of the volume fraction is proposed to achieve a broadened resonance optical response. Finally, we propose the design technique and constraints of a non-magnetic optical cloaking device, based on high-order transformation optics with different volume fractions of silver and silica.     

Low-power MRI by Frank-sequence excitation

Recently, a new NMR method employing an rf excitation scheme with strongly reduced power has been introduced, which is based on modulating rf pulses according to Frank sequences. For many applications, a reduction of rf power is essential, e.g. to eliminate bulky rf pre-amplifiers or in medical high-field MRI to preserve patient safety. Another benefit of the new scheme are very short dead times allowing for measurements of samples with short relaxation times. In this work, Frank-sequence excitation is used for low-power imaging for the first time. Results of one-, two-, and three-dimensional imaging experiments are presented and compared to conventional images.     

Synthesis by MW-assisted direct arylation,side-arms driven self-assembly and functional properties of 9,10-dithienylanthracene orthogonal materials

We report a new class of multifunctional 9,10-dithienylanthracene-based materials having an anthracene π-core functionalized at the 9,10 positions with thienyl side-arms of different size and type of substitution. MW-assisted double direct arylation reaction is employed for the first time to synthesize the target molecules in one-step, organometallic free conditions, in only 5 min and yields up to 80% rather than by a multi-step Stille coupling taken as conventional reference approach. DFT calculations reveal a molecular conformation characterized by the thienyl rings orthogonal to the anthracene core. Nevertheless, despite the non-coplanar structure, all compounds exhibited highly crystalline cast films emitting blue light, with an extraordinary variability in morphology and hole mobility up to 8×10⁻³ cm² V⁻¹ s⁻¹.     

Impact of environmentally friendly processing solvents on the properties of blade‐coated polymer solar cells

High‐performance polymer solar cells (PSCs) are typically fabricated by spin coating in inert atmosphere from toxic halogenated solvents such as 1,2‐dichlorobenzene (o‐DCB) and chlorobenzene. This fabrication process is potentially hazardous for both the humans and the environment and dramatically impacts the possibility for the organic photovoltaic technology to be adopted at large scale. In this work, efficient PSCs blade coated in air using nonhalogenated 1,2,4‐trimethylbenzene (TMB) as processing solvent are demonstrated. The active layer, based on a previously synthesized benchmark polymer PFQ2T‐benzodithiophene blended with [6,6]‐phenyl‐C61‐butyric acid methyl ester (PC₆₁BM), showed an enhanced solid‐state aggregation induced by the use of TMB. Compared to o‐DCB‐processed devices, the solar cells fabricated from TMB resulted 10% more efficient with a power conversion efficiency of 4.20%. Interestingly, the improved photovoltaic performance resulted from the combination of synergic effects promoted by a more favorable film morphology, such as high exciton dissociation efficiency and lower bimolecular recombinations resulting in higher charge collection efficiency at the electrodes. The positive effect of TMB, compared to that of commonly employed halogenated solvents, confirms the great potential of this approach for the development of efficient PSCs for practical applications with reduced environmental impact. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 487–494     

Incorporation of 125I, 134I,and 99mTe in some Pharmaceutics and Hormones

In-vitro-labelling of vasopressin and tofranil using radioactive iodine and lechnelium, is carried out by direct interaction between nascent halogen and the macromolecules. Labelling takes place at the favourable pH in the tyrosyl residue of the molecule, yielding a die-iodo derivative or similar. The present method had the advantage of being simple rapid and gives labelled compounds of high specific activity. The gel-filtration method furnished labelled compounds with a minimum degradation products.     

Synthesis of some novel N5-sulfonylated and N1-alkyated pyrazole derivatives and their antimicrobial activity in conjunction with molecular docking study

Some novel N5-sulfonylated 4 were synthesized via sulfonylation of 5-amino-1H-pyrazole derivative 1 with arylsulfonyl chlorides. On the other hand, N1-alkylated pyrazoles 7 and 10 were synthesized through alkylation of compound 1 with each of chloroacetamides and ethylchloroacetate under different conditions. Condensation of compounds 4 and 7 with different aromatic aldehydes furnished the corresponding arylidene derivatives. In spite of, condensation of 10 with aromatic aldehydes afforded the 2-(5-amino-2-aryl-1H-pyrazol-1-yl)acetic acid. The structure of the newly synthesized compounds was elucidated by elemental analyses and spectral data. Also, the suggested mechanisms for their formation were studied. Additionally, some selected new compounds were screened against antimicrobial activity. Compound 7c exhibited a higher activity against Candida albicans (inhibition zone diameter [IZD] = 31.3 ± 0.6 mm) than the standard antibiotic Nystatin (IZD = 21 ± 0.5 mm). Also, compound 7c showed minimum inhibitory concentration = 125 and 250 μg/mL against Klebsiella pneumonia and Staphylococcus aureus, respectively. Molecular docking study also was carried out for compound 7c .     

Synthesis of new C-glycosyl aza-β3-amino acids building blocks

New C-glycosylated N^β-protected aza-β³-amino acid building blocks have been prepared from C-glycosyl aldehydes of gluco and galacto configuration by reductive amination and subsequent N-alkylation. These moieties were elaborated to β-dipeptides by elongation at the C- or the N-terminus establishing their ability to be incorporated in original glycosylated foldamers.