Three-axis attitude determination via Kalman filtering of magnetometer data

A three-axis Magnetometer/Kalman Filter attitude determination system for a spacecraft in low-altitude Earth orbit is developed, analyzed, and simulation tested. The motivation for developing this system is to achieve light weight and low cost for an attitude determination system. The extended Kalman filter estimates the attitude, attitude rates, and constant disturbance torques. Accuracy near that of the International Geomagnetic Reference Field model is achieved. Covariance computation and simulation testing demonstrate the filter's accuracy. One test case, a gravity-gradient stabilized spacecraft with a pitch momentum wheel and a magnetically-anchored damper, is a real satellite on which this attitude determination system will be used. The application to a nadir pointing satellite and the estimation of disturbance torques represent the significant extensions contributed by this paper. Beyond its usefulness purely for attitude determination, this system could be used as part of a low-cost three-axis attitude stabilization system

A dodecameric water cluster built around a cyclic quasiplanar hexameric core in an organic supramolecular complex of a cryptand

An infinite network is formed by the hydrogen bonding of a cluster of 12 hydrogen-bonded water molecules (see picture) to the secondary amino nitrogen atoms of a laterally nonsymmetric azacryptand. This mode of association had not previously been predicted or found experimentally

Synthesis, characterization and complexation properties of aheteroditopic cryptand L towards Cu<SUP>II</SUP> and Zn<SUP>II</SUP>: crystal structures of L&#183;3H<SUB>2</SUB>O and[ZnL][ClO<SUB>4</SUB>]<SUB>2</SUB>&#183;2H<SUB>2</SUB>O

A new heteroditopic cryptand (L) has been synthesized in high yields, at 5 &#176;C and in absence of any templating metal ion, by tripod-tripod Schiff-base condensation of tris(3-aminopropyl)amine and 2,2',2''-nitrilotris- (ethyleneoxy)tris(benzaldehyde) followed by reduction in situ with NaBH4. The molecule has an endo-endo conformation with a distance of 5.291 &#197; between the two bridgehead nitrogens. The cryptand forms mononuclear cryptates of the general formula [ML][ClO4]2 with copper(II) and zinc(II) perchlorates. The crystal structure of [ZnL][ClO4]2&#183;2H2O was determined. The ZnII occupies the N4 end of the cavity in an almost ideal tetrahedral geometry. The blue copper(II) cryptate exhibits ligand-field bands at 875 and 745 nm and a ligand-to-metal charge transfer at 275 nm in acetonitrile solution at 298 K indicative of pseudo-tetrahedral CuN4 co-ordination. However, its EPR spectral characteristics in the solid state or in solution are typical of a magnetically concentrated complex

Metal-organic framework structures of Cu(II) with pyridine-2,6-dicarboxylate and different spacers: identification of a metal bound acyclic water tetramer

The ligand pyridine-2,6-dicarboxylic acid (pdcH2) reacts under hydrothermal conditions, with Cu(NO3)2&#183;6H2O in the presence of different N-heterocycles used as spacers to form 1D, 2D or 3D metal-organic framework structures depending on the nature of the spacer. These network structures are characterized by X-ray crystallography, variable temperature magnetic measurements, powder X-ray diffraction, infrared and thermal gravimetric analyses. With 4,4'-bipyridine spacer, a 2D network is formed where every alternate Cu(II) ion in the chain is coordinated terminally to an acyclic tetrameric water cluster

Synthesis and characterization of mono- and bis-D-π-A cryptand derivatives for second-order nonlinear optics and its modulation with different metal ion inputs

Two new classes of mono- and bis-D-&#960;-A cryptand derivatives with a flexible and a rigid cryptand core have been synthesized. The linear and nonlinear optical properties of these molecules are probed. The three dimensional cavity of the cryptand moiety has been utilized to modulate the SHG intensity to different extents in solution with metal ion inputs such as NiII, CuII, ZnII, and CdII. We also report that decomplexation events can be used to reversibly modulate their NLO responses

Otkrivanje i karakterizacija rotavirusa genogrupe 5 povezanog s proljevom prasadi u sjeveroistočnoj Indiji

Rotaviruses have been recognized as an important etiological agent of non-bacterial acute gastroenteritis in young children and animals of several species worldwide, including diarrhoea in weaning and post-weaning piglets. In this study, we report the prevalence and molecular epidemiology of rotaviruses detected from piglets in different regions of the north-eastern hilly region of India. A total of 457 faecal samples (339 diarrhoeal and 118 non-diarrhoeal) were collected from piglets from local (n = 130) and cross breed (n = 327) piglets between July 2013 to June 2015 in different seasons of the year. All the samples were subjected to RNA-PAGE and RTPCR analysis. Rotaviruses were detected in 4.81% animals by RNA-PAGE and 7.43% animals by RT-PCR, with the highest prevalence (9.67%) from Meghalaya state. All the isolates were recorded as GARV and genogroup 5. The prevalence was higher in unorganized farms (10.77%) compared to organized farms (4.0%) with higher detection from diarrhoeic (9.14%) compared to non-diarrhoeic animals (2.54%). A higher prevalence was also recorded during the summer (12.5%) and winter (9.09%) seasons. On the basis of the sequence analysis, all the isolates were placed in a unique single cluster, different from other Indian isolates from humans and animals, which were in close proximity with human isolates. This is the first report of the detection of G5 Rotavirus associated with piglet diarrhoea in India.Rotavirusi su prepoznati kao važan etiološki čimbenik nebakterijskog akutnog gastroenteritisa kod male djece i različitih vrsta životinja. Kod prasadi to uključuje i proljev koji se pojavljuje pri odbiću i nakon odbića. U ovom je radu prikazana prevalencija i molekularna epidemiologija rotavirusa otkrivenih kod prasadi iz različitih dijelova sjeveroistočnog, brdovitog područja Indije. U razdoblju od srpnja 2013. do lipnja 2015. godine, tijekom različitih sezona, prikupljeno je ukupno 457 uzoraka fecesa (339 proljevastih i 118 neproljevastih). Uzorci su potjecali od prasadi lokalnih (n = 130) i križnih pasmina (n = 327). Svi su uzorci podvrgnuti RNA-PAGE i RT-PCR analizama. Rotavirusi su otkriveni u 4,81 % životinja pomoću RNA-PAGE i 7,43 % životinja pomoću RT-PCR analize. Najveća prevalencija (9,67 %) utvrđena je u državi Meghalaya. Svi su izolati registrirani kao GARV i genogrupa 5. Prevalencija je bila viša u slabo organiziranim farmama (10,77 %) u usporedbi s dobro organiziranim farmama (4,0 %), s većom učestalošću otkrivanja kod životinja koje su imale proljev (9,14 %) u odnosu na životinje bez proljeva (2,54 %). Također, veća je prevalencija utvrđena tijekom ljetnih (12,5 %) i zimskih (9,09 %) sezona. Na temelju analize sekvencija svi su izolati smješteni u jedinstveni pojedinačni skup (klaster). Taj je skup različit od drugih indijskih izolata ljudi i životinja u kojima je bio u neposrednoj blizini izolata ljudi. Ovo je prvo izvješće o otkrivanju rotavirusa G5 povezanih s proljevom prasadi u Indiji

A new class of three dimensional D-π-A trigonal cryptand derivatives for second-order nonlinear optics

Synthesis, crystal structures, linear and nonlinear optical properties of tris D-&#960;-A cryptand derivatives with C3 symmetry are reported. Three fold symmetry inherent in the cryptand molecules has been utilized for designing these molecules. Molecular nonlinearities have been measured by hyper-Rayleigh scattering (HRS) experiments. Among the compounds studied, L1 adopts non-centrosymmetric crystal structure. Compounds L1, L2, L3 and L4 show a measurable SHG powder signal. These molecules are more isotropic and have significantly higher melting points than the classical p-nitroaniline based dipolar NLO compounds, making them useful for further device applications. Besides, different acceptor groups can be attached to the cryptand molecules to modulate their NLO properties

The first D-π-A octupolar cryptand molecule to exhibit bulk non-linearity

The cryptand derivative has H-bond mediated trigonal network structure that leads to octupolar bulk nonlinearity

Lewis acid-induced rearrangment of α-[bis(methylthio)methylene]ethyl-2-styrylcyclopropylcarbinols: unexpected formation of a novel bicyclo[3.2.1]octadiene framework

The α-[bis(methylthio)methylene]ethyl-2-styrylcyclopropylcarbinols 9a-c undergo a simple but unexpected skeletal rearrangement in the presence of stannic chloride in nitromethane to afford bicyclo[3.2.1]octadiene derivatives 10a-c exclusively in good yields. The structure of 10a was conclusively elucidated by X-ray diffraction studies. A possible mechanism governing the formation of 10 is proposed