All-optical method for maintaining a fixed intensity level of a light signal in optical computation

In data and image processing the role of optics is already well established. Due to inherent parallelism the optical systems run faster than its electronic counterparts. Optical nonlinear material can be used as a successful optical switch. The primary requirement for proper functioning of such nonlinear material based logic devices is a fixed intensity level of the optical signal against a specific logic state. In this communication, the authors propose a new concept to obtain a fixed intensity level of optical signal against a specific logic state for data processing. The scheme may extend a tremendous application not only to the area of all-optical computation, but also to optical communication process.     

Crystal and molecular structure of diaqua-bis-(3,5-dimethyl-1-guanyl pyrazole) nickel (II) nitrate, [Ni(C6N4H10)2(H2O)2](N03)2

The title compound crystallizes in space groupP2₁/n witha=10.651(3),b=11.082(2),c=8.993(3) Å,=106.79(3)°;R=0.064 andR _w=0.074 for 3399 observed reflections (I3(I)) from 3674 measured. The structure was solved by direct methods and refined by least squares. The Ni atom of the complex is located at a center of inversion, and is surrounded by four nitrogen atoms of the two ligands in square-planar geometry. The oxygen atoms of the two centrosymmetrically related water molecules complete the coordination around the metal ion to form an elongated octahedron.     

Synthesis and structure of the first water-soluble chiral monomeric MnIV complex: [Δ-MnIV(biguanide)3] (ClO4)4·H2O

The reaction of KMnO₄ with alkaline biguanide sulfate solution, followed by acidification of the resulting stable filtrate with concentrated HClO₄, led to the title complex, 1. The crystal structure of the [Δ-Mn^IV(bigH)₃](ClO₄)₄·H₂O (1, bigH: biguanide, C₂H₇N₅) has a tetragonal chiral P4 ₁ 2 ₁ 2 space group with a = b = 11.416(3) ?, c = 20.742(7) ?, Z = 4. The complex consists of one chiral [Δ-Mn^IV(bigH)₃] tetracation, four ClO₄ ⁻ anions, and one water molecule. In the tetracation, six N atoms from three neutral biguanide chelate coordinate to the Mn^IV cation, forming an octahedron with Δ-optical activity. The [Δ-Mn^IV(bigH)₃] tetracation interconnects each other by numerous hydrogen bonds with N–H···O and O–H···O between biguanide moieties of the [Δ-Mn^IV(bigH)₃] tetracations and counter-anions as well as water molecules, to construct a three-dimensional network.     

Regiospecificity of nucleotide–amino acid mating vs. water dynamics: a key to protein–nucleic acid assemblies: structure of unidecahydrated inosine-5′-monophosphate and L–glutamic acid (2C10H13N4O8P·C5H11NO4·11H2O) cocrystal at atomic resolution

The crystal structure of a unidecahydrated cocomplex between two Inosine-5-monophosphates (IMP) and one L-glutamic acid has been determined by X-ray crystallographic methods. The crystal belongs to the monoclinic space group P2₁ with cell dimensions a = 8.650(1), b = 21.900(1), c = 12.370(1) Å, and = 110.4°(9). This structure reveals extensive hydrogen bonding of glutamic acid to the nucleotide through direct and water-mediated interactions. The phosphate oxygens (O3B and O1B) seem to prefer nonspecific interaction with the functional sites of glutamic acid (OE2 ······O1B = 1.78 Å, NA······O3B = 2.73 Å, OH······O3B = 3.06 Å), whereas the bases prefer specific (O······N3B = 2.88 Å) binding. A solvent mediated N7A···W5···N7B hydrogen bond used for stabilization of the stacked purine bases has been observed as in other amino acid–nucleotide cocrystals. Glutamic acid occupies the same hydrophilic region in the nucleotide cocrystal as was found in glutamine–inosine monophosphate (Gln–IMP) and in serine–inosine monophosphate (Ser–IMP) complexes through substantial replacement of free and bound water molecules. This points to the dynamic hydrogen bonding nature of the water molecules and their stereochemical cooperation for the placement of amino acid through the polycoordination within the crystal.     

9[1-(2-Hydroxy ethoxy)-3-hydroxy propyl] guanine: a nucleoside analog

The compound 9[1-(2-hydroxy ethoxy)-3-hydroxy propyl] guanine crystalizes in the tetragonal system, space group P4₁2₁2 with a = 11.106 (1), c = 20.558 (2) Å, and Z = 8. The acyclic chain C1¯O1¯C4¯C5¯O5 is in the extended configuration and the glycosidic torsion angle (C4¯N9¯C1¯O1) is 125.1 (8)°. The molecules are held together by Van der Waal's forces.     

1-(Ethoxymethyl)-6-(phenylselenyl)-5-ethyl uracil: a nucleoside analog

The compound, 1-(ethoxymethyl)-6-(phenylselenyl)-5-ethyl uracil, crystallizes in the monoclinic space group P2₁/n with unit cell parameters a = 5.304(1), b = 21.261(4), c = 13.996(4) Å, = 94.30(2)°, and Z = 4. The acyclic chain C1, O4, C4, C5 is in fully extended form and nearly perpendicular to the uracil base. The molecules are held together by van der Waal's forces.     

Efficient newton–raphson/singular value decomposition-based optimization scheme with dynamically updated critical condition number for rapid convergence of weighted histogram analysis method equations

Selection of the successful optimization strategy is an essential part of solving numerous practical problems yet often is a nontrivial task, especially when a function to be optimized is multidimensional and involves statistical data. Here we propose a robust optimization scheme, referred to as NR/SVD-Cdyn, which is based on a combination of the Newton–Raphson (NR) method along with singular value decomposition (SVD), and demonstrate its performance by numerically solving a system of the weighted histogram analysis method equations. Our results show significant improvement over the direct iteration and conventional NR optimization methods. The proposed scheme is universal and could be used for solving various optimization problems in the field of computational chemistry such as parameter fitting for the methods of molecular mechanics and semiempirical quantum-mechanical methods. © 2019 Wiley Periodicals, Inc.     

All optical frequency encoding method for converting a decimal number to its equivalent binary number using tree architecture

In any kind of computing and data processing system the use of binary numbers are found very much suitable and reliable. On the other hand several natural representations have been realized using decimal numbers. So conversion of a decimal number to its binary equivalent and vise-versa are of great importance in the field of computation technology. There lie already a number of established methods regarding such conversion processes. Again optical tree architecture is one of the most promising systems for realizing the optical conversion of any decimal number to its equivalent binary. Here in this communication the authors propose a new method for optical conversion of a decimal number to its binary equivalent using tree architecture based system and frequency encoding principle. In frequency encoding system, frequency of light is used for encoding of decimal digits or binary bits instead of intensity variation. For example 0 and 1 bits of binary number are coded by two different frequencies of light signal, instead of representing the presence of light as 1 and absence by 0. The proposed conversion process has multifaceted advantages in communication, as well as in data processing. To implement the above conversion some characteristic features of semiconductor optical amplifier (SOA) have been used massively. The wavelength conversion property, cross gain modulation and some nonlinear properties of SOA are exploited to get the frequency encoded response. The proposed system carries all the basic advantages of optical processing as well as those of frequency encoding also.     

Alternating approach of implementing frequency encoded all-optical logic gates and flip-flop using semiconductor optical amplifier

In conduction of parallel logic, arithmetic and algebraic operations, optics has already proved its successful role. Since last few decades a number of established methods on optical data processing were proposed and to implement such processors different data encoding/decoding techniques have also been reported. Currently frequency encoding technique is found be a promising as well as a faithful mechanism for the conversion of all-optical processing as the frequency of light remains unaltered after refection, refraction, absorption, etc. during the transmission of light. There are already proposed some frequency encoded optical logic gates. In this communication the authors propose a new and different concept of frequency encoded optical logic gates and optical flip-flop using the non-linear function of semiconductor optical amplifier.