Splitting Off Research Articles

Analytical biotechnology of recombinant peptides and proteins: II. A confirmation of the primary structure of fusion protein containing human proinsulin and optimization of its proteolysis by trypsin

The kinetics of trypsin proteolysis of the fusion protein (FP) containing human proinsulin was studied by a set of analytical micromethods. These were the microcolumn reversed-phase HPLC and the qualitative identification by MALDI-TOF mass spectrometry and amino acid sequencing. The first stage of the proteolysis was shown to be the cleavage of FP into the leader fragment and proinsulin. The subsequent splitting off ofC-peptide from proinsulin results in the formation of ArgB31-ArgB32-insulin. The effect of temperature on the formation of de-ThrB30-insulin, a by-product, was also studied. The structure of FP was confirmed by the peptide mapping technique, and the leader fragment was shown to contain noN-terminal Met residue.

Constrained Edge-Splitting Problems

<p>Splitting off two edges su, sv in a graph G means deleting su, sv and<br />adding a new edge uv. Let G = (V +s,E) be k-edge-connected in V<br />(k >= 2) and let d(s) be even. Lov´asz proved that the edges incident to s<br />can be split off in pairs in such a way that the resulting graph on vertex<br />set V is k-edge-connected. In this paper we investigate the existence of<br />such complete splitting sequences when the set of split edges has to meet<br />additional requirements. We prove structural properties of the set of those<br />pairs u, v of neighbours of s for which splitting off su, sv destroys k-edge-connectivity. This leads to a new method for solving problems of this type.</p><p>By applying this method we obtain a short proof for a recent result of<br />Nagamochi and Eades on planarity-preserving complete splitting sequences and prove the following new results: let G and H be two graphs on the same set V + s of vertices and suppose that their sets of edges incident to s coincide. Let G (H) be k-edge-connected (l-edge-connected, respectively) in V and let d(s) be even. Then there exists a pair su, sv which can be split off in both graphs preserving k-edge-connectivity (l-edge-connectivity, resp.) in V , provided d(s) >= 6. If k and l are both even then such a pair always exists. Using these edge-splitting results and the polymatroid intersection theorem we give a polynomial algorithm for the problem of simultaneously augmenting the edge-connectivity of two graphs by adding a (common) set of new edges of (almost) minimum size.</p>

Edge-Connectivity Augmentation with Partition Constraints

In the well-solved edge-connectivity augmentation problem we must find a minimum cardinality set F of edges to add to a given undirected graph to make it k-edge-connected. This paper solves the generalization where every edge of F must go between two different sets of a given partition of the vertex set. A special case of this partition-constrained problem, previously unsolved, is increasing the edge-connectivity of a bipartite graph to k while preserving bipartiteness. Based on this special case we present an application of our results in statics. Our solution to the general partition-constrained problem gives a min-max formula for |F| which includes as a special case the original min-max formula of Cai and Sun [Networks, 19 (1989), pp. 151--172] for the problem without partition constraints. When k is even the min-max formula for the partition-constrained problem is a natural generalization of the unconstrained version. However, this generalization fails when k is odd. We show that at most one more edge is needed when k is odd and we characterize the graphs that require such an extra edge. We give a strongly polynomial algorithm that solves our problem in time O(n(m + nlog n)log n). Here n and m denote the number of vertices and distinct edges of the given graph, respectively. This bound is identical to the best-known time bound for the problem without partition constraints. Our algorithm is based on the splitting off technique of Lovasz, like several known efficient algorithms for the unconstrained problem. However, unlike previous splitting algorithms, when k is odd our algorithm must handle obstacles that prevent all edges from being split off. Our algorithm is of interest even when specialized to the unconstrained problem, because it produces an asymptotically optimum number of distinct splits.

Family Experiences and the Erosion of Support for Intergenerational Coresidence

FRANCES K. GOLDSCHEIDER Brown University LEORA LAWTON TechSociety Research* We test the affluence interpretation of the decline in intergenerational coresidence, which implicitly affirms that close kin would still offer housing to those in need, by examining the factors that influence attitudes about coresidence with young adult children and aging parents. Using national data, we model the effects of living in a multigenerational household in childhood and living independently from parents prior to marriage on respondents' obligation to allow aging parents and adult children who are in need to coreside. We find strong effects of living arrangements experiences on attitudes that differ by the type of intergenerational coresidence. Key Words: affluence, attitudes, coresidence, intergenerational relations, living arrangements. Home is the place where, when you have to go there, they have to let you in. Robert Frost, Death of the Hired Man Shelter is a fundamental resource that family members attempt to provide each other when necessary. Although levels of intergenerational coresidence have declined dramatically in recent decades in the United States and in other developed countries, most analysts interpret these changes as the result of increases in affluence that have allowed previously dependent relatives to split off from the nuclear family to live in a home of their own (Kuznets, 1978; Michael, Fuchs, & Scott, 1980). Given that splitting off increases the privacy of both those who split off and their relatives, the increased number of young adults leaving home prior to marriage (Goldscheider, 1997) and the greater likelihood that widowed parents live alone (Ruggles, 1996) are usually seen as strictly beneficial. The affluence interpretation underlies this positive view, and it suggests that although the necessity for coresidence has declined, there has been no reduction in the commitment to provide it. Rather, ascribing change to affluence implicitly affirms that close kin would still offer housing to those in need. However, changes in preferences may have been as important as increases in affluence in the splitting off of extra relatives from American families (Pampel, 1983). The outcry in the popular press (Cowan, 1989; Gross, 1991; Lindsay, 1984) and from some scholars (Schnaiburg & Goldenburg, 1989) against the recent increase in grown children living with parents, despite the dramatic increases in housing costs and youth unemployment (Levy, 1987), suggests that Americans may have become increasingly opposed to parents and adult children sharing a residence, even if the parent or child is in a difficult situation and lacks the physical or financial resources to make separate living feasible. In fact, the commitment to provide housing to close kin in need may be weakening. Many may no longer feel that they have to let you in. These two explanations-changes in affluence and changes in preferences-are not contradictory, given that changes in attitudes and preferences are likely to occur as a result of changes in behavior. The decline in coresidence has been under way for most of the twentieth century (Ruggles, 1994). Through social-psychological behaviorist mechanisms of social learning and through the interpretation of experiences via processes such as those set forth by cognitive theorists, people develop attitudes about their family relationships and obligations (Caspi & Elder, 1988; Sroufe & Fleeson, 1988). Children watch what significant others like their parents do, hear what they say, and learn by imitating many of their parents' attitudes and behavioral choices. If increases in affluence mean that families need to provide intergenerational coresidence less often, children are less likely to observe such living arrangements and are more likely to conclude that such solutions are inappropriate or unnecessary. Of course, not all learning takes place in childhood, and most people find that the economic and family commitments of adulthood restructure their choices and priorities and increase their concern for the needs of others. …

Kinetics of electroreduction of tris–oxalate cobalt(III) complexes on the dropping mercury electrode.

Abstract The kinetics and mechanism of electroreduction of tris–oxalate cobalt(III) complexes and oxalate cobalt(II) complexes at a dropping mercury electrode were studied with special attention to double layer effects for the electrode reaction of Co(III) to Co(II). Two irreversible waves corresponding to the electroreduction of Co(III) to Co(II) and Co(II) to Co(0) were observed. As a result of measurements in solutions containing exclusively Co(II) complexes, it was discovered that only aqua-complexes of Co2+ are involved in a slow electrochemical step, regardless of the oxalate concentration in the bulk solution. These complexes are formed by the fast splitting off of the coordinated oxalate ions from the originally predominant Co(II) oxalate complexes. The reversibility of the chemical reactions accompanying the electroreduction of these species also follows from the above measurements. This allows one to consider the aqua-complexes of Co(II) to be one of the products of the overall electrode reaction of the Co(III)/Co(II) couple. These generated particles, being positively charged, effectively participate in screening the electric field within the diffuse layer so that appropriate corrections for the double layer structure must be taken into consideration. The corresponding expressions for the above corrections are derived and their validity is shown by comparing theory and experiment.

Audio signal processing arrangement for deriving a center channel signal and also an audio visual reproduction system comprising such a processing arrangement

An audio signal processing arrangement includes a first filter (20) for splitting off signal components from the left channel signal (L) at least within one frequency band. Signal components are split off from the right channel signal (R) by a second filter (23). The output signals of the filters (20 and 23) are compared with the right channel signal (R) and the left channel signal (L), respectively. The filter parameters of the filters (20 and 23) are adjusted to values at which there is maximum correlation between the compared signals according to a given criterion. The center channel signal is derived in dependence on the filter adjustment. This can be effected by combining the output signals of the filters (20 and 23). In this manner, a center channel signal is obtained formed by the correlating left and right channel signal components, so that the stereo image is hardly disturbed by the addition of the center channel signal, whereas the perceived position of the virtual sources in the stereo image becomes less dependent on the listener's position with respect to the left and right loudspeakers.

Kinetics of Coupling of 4-Methoxybenzenediazonium Ion with 2,6-Dihydroxypyridine

The kinetics of reaction of 4-methoxybenzenediazonium ion (3) with 2,6-dihydroxypyridine (1) has been studied in methoxyacetate, acetate, and phosphate buffers. The rate-limiting step is the formation of the reaction intermediate and not the splitting off of the proton (which was detected in the cases of citrazinic acid and its methyl ester). Therefrom it follows that for 2,6-dihydroxypyridine derivatives the steric hindrance to the formation of the Wheland intermediate exerted by CO2- and CO2CH3 groups represents a necessary condition for the rate-limiting splitting off of the proton and, hence, for the existence of general base catalysis.

Quantum Chemical Study of Thermal Dehydrochlorination of Poly(vinyl chloride) Containing Aldehyde Groups

Thermal dehydrochlorination of syndiotactic oligomeric models of PVC with aldehyde groups is studied using semiempirical quantum chemical methods AM1 and MNDO. The possibility of both radical and ionic mechanism of HCl elimination is examined. From the results it follows that the homolytic detachment of chlorine from the carbon in β-position to the aldehyde group is preferred, followed by hydrogen splitting off. Hydrogen atom detachment from the carbon in α-position to the aldehyde group as the first step is found energetically less convenient. The dehydrochlorination of aldehyde-containing PVC model, especially of the first molecule from the chain, is remarkably easier in comparison with regular PVC model. However, the energetical preference is smaller for further HCl splitting off and, from the kinetic point of view, this process seems to be slower. The influence of the aldehyde group inductive effect on the driving force potential m(Ca-Cw) is apparent from the partial charge distributions.

Computer modelling of the degradation of linear polymers

Mechanisms of degradation of linear polymers are considered with the help of a computer program, which uses a pseudo-random number generator to carry out a Monte Carlo-like simulation of the processes. Randomly chosen bonds are degraded either at random positions along a molecule or by a number of specific systematic processes, such as breaking the molecule in half or slicing off a fixed number or percentage of units. The resulting molecular weight distribution (MWD) changes are compared to experimental measurements reported in the literature and generated in the authors' own laboratory. Totally random processes do not explain observed movements of the MWD to lower molecular weight or the formation of new peaks. Both processes require specific systematic scission of the polymer chain, such that, for instance, the length of one of the degradation products falls within the range of the original MWD. New peaks require the splitting off of fragments of a systematic length and/or recombination of fragments with each other or with other molecules in the distribution. Peak movement requires the preferential scission of the longest molecules. Random processes tend to follow standard first-order kinetic plots of reciprocal DP vs time, provided all the products of degradation are included in the DP calculation. Systematic scission processes tend to introduce curvature.

Algorithmic complexity of the universe and quantum transitions splitting off extra coordinates

We consider a model of quantum gravitation in which the probability of the appearance of any quantum gravitational objects is connected with their Kolmogorov algorithmic complexity. We show that in such a case, extra coordinates may be split off.

Studies of the degradation of pullulan by the decycling maltodextrinase of Flavobacterium sp.

The mode of action on pullulan of the decycling maltodextrinase of Flavobacterium sp. was studied. The enzyme specifically split (1 → 4)-α- d-glucosidic linkages and, preferentially through cleavage of its tetraose units, degraded the α- d-glucan into larger fragments, which were further hydrolysed. About 39% of the carbohydrate was found to be the branched trisaccharide panose, established by 1H NMR spectroscopy and by the mp of the corresponding alditol dodecaacetate. At concentrations > 56 mM, panose exhibited product inhibition of further hydrolysis. Remarkable amounts of a dimer and a tetramer of panose, and of a branched tetrasaccharide, 6 3- O-α- d-glucosylmaltotriose, that arose from the tetraose units and the reducing ends of the pullulan molecules, were found among the larger hydrolysis products. The probable structures of some minor fragments were deduced from the debranching pattern obtained with pullulanase. The formation of glucose (6% of the carbohydrate) observed during pullulan degradation was most probably due to multiple transglycosylation reactions between the branched tetrasaccharide and a branched pentasaccharide, with subsequent splitting off of glucose from the transglycosylation products.

Electrical properties of sputtered MnO 2 thin films

In a previous paper we have shown that it was possible to obtain low-resistivity (1.5 Ω ⋅ cm) and stoichiometric MnO 2 films by reactive cathodic sputtering of an Mn 3O 4 target. Thermogravimetric analysis, SIMS, and XRD techniques have been used to relate chemical and physical characteristics of the deposits to their electrical properties. The resistivity of semiconducting manganese dioxide films is lowered (down to 0.3 Ω ⋅ cm) by air annealing up to 450°C. This treatment also produces the thermal splitting off of oxygen from the sample. The initial presence of contaminating sodium clusters inside the films must have an influence on the electrical behaviour of air-reduced films.

The Point Arena eddy: A recurring summer anticyclone in the California Current

The propensity for an anticyclonic eddy (∼100‐ to 200‐km diameter) to develop west of Point Arena during the summer is documented with an analysis of satellite derived sea surface temperature (SST) data and a review of published historical hydrographic data. The satellite data span the period from 1981 through 1989 and the hydrographic data include CalCOFI surveys from 1949–1959 and a few more recent studies. A closed anticyclone was apparent in many of the historical dynamic height maps, while a meander pattern, lacking closed contours, characterized the coincident hydrographic 10‐m temperature maps. A conceptual model of an eddylike perturbation imbedded in a broader equatorward flow is adopted as a working hypothesis. In this simplistic model, the only distinction between an eddy (with closed contours) and a meander (without closed contours) is the relative strength of the eddylike perturbation. This led to a method to detect the eddies in the satellite SST data, which were dominated by meanderlike patterns: A linear trend was subtracted from each image to remove large‐scale SST gradients, leaving an expression of the residual eddylike perturbation. Composite images over select time periods were produced for analysis by computing spatial variance EOFs of the detrended data. With this approach, a warm‐core eddy was evident at Point Arena in summertime satellite SST data from 1981–1985 and 1987–1989 (formation of an eddy in 1986 remains unresolved because the readily available SST data were incomplete). The eddy was bounded on the inshore side by the jet and filament system studied during the 1987 and 1988 Coastal Transition Zone (CTZ) program. Recurrence of this eddy was apparently coupled with the recurring cold filament commonly observed at Point Arena during the summer. The coevolution of the eddy and meandering jet during 1988 was studied with sequential composite empirical orthogonal function (EOF) satellite SST images. These show that a deep anticyclonic meander was present near Cape Mendocino and directed the jet toward shore. In late July 1988 this meander pinched off a new eddy, and the subsequent jet flow was redirected southward and displaced farther offshore. These events account for the transition in the jet observed in the July CTZ hydrographic surveys. The length scale and position of the Point Arena eddy is consistent with a standing wave, phase locked to a prominent cape (in this case, Mendocino). The significance of the apparent splitting off of an eddy in 1988, as well as the apparent preponderance of anticyclones evident in these EOFs, is discussed relative to recent theoretical and numerical model developments.

Determination of hemoglobin adducts from aldehydes formed during lipid peroxidation in vitro

This study was performed in order to investigate the formation of hemoglobin (Hb) adducts from some aldehydes, known to be formed during the peroxidation of polyunsaturated fatty acids. Hb was reacted in vitro with aldehydes followed by reduction of hemolysate with sodium borohydride and isolation of globin. Using the N-alkyl Edman method, globin samples were derivatized with pentafluorophenyl isothiocyanate for specific splitting off of N-substituted N-terminal valines. Adducts formed were then characterized by gas chromatography mass spectrometry using different ionization techniques. It was shown that adducts from saturated aldehydes were Schiff bases and those from α,β-unsaturated aldehydes were mixtures of Schiff bases and 1,4-addition products. Aldehyde adducts were also measured in Hb from erythrocytes induced for lipid peroxidation. Incubation of the erythrocytes in presence of arachidonic acid led to increased levels of adducts.

Kinetics of emulsion polymerization of methyl methacrylate and its copolymerization with acryl- or methacrylamide

The kinetics of emulsion homo- and copolymerization of methyl methacrylate with amides of acrylic or methacrylic acids are studied. A specific feature of the reaction is the presence of a gel effect, leading to accelerated polymerization at high degrees of conversion. The magnitude of the gel effect depends on the initiation rate, and the concentration and nature of the emulsifier. It is shown that the formation of polymer-monomer particles involves different mechanisms, the ratio between which is determined by the presence of water soluble copolymers and by the initiation rate. The dependence of the kinetic order with respect to the emulsifier on the concentration of initiator and comonomer is determined by the existence of bimolecular splitting off of radicals in the aqueous phase. The effect of amides on emulsion polymerization is associated with an increase in the rate of growth in the latex particles and the probability of chain termination in the aqueous phase.

The Dark Goddess: An Encounter With the Dark Feminine

The various expressions of the archetype of the Dark Goddess through myth and history are explored in this article. The Black Madonna, Lilith, Inanna, Hecate, Artemis, Diana, Kali, and the Seven Africa Powers are described. The author describes her splitting off of the dark side of the feminine due to her culture and illegitimacy as a child. Feelings of passion, sexuality, sensuality, anger, and rage went underground with the adoration of the Virgin Mary, promoted as the ideal. With the owning of the totality of the feminine, a woman recognizes and owns her own strength. Two examples are given of the trays of a 6-year-old girl and a 58-year-old woman, and the manifestation of the protective, dark goddesses for their healing of sexual abuse.

Evanescent modes and scattering in quasi-one-dimensional wires.

We calculate the current transmission amplitudes and electrical conductance as a function of Fermi energy for electrons scattering from a single defect in a quasi-one-dimensional wire. In a confined geometry the scattering boundary conditions couple propagating modes in the wire to nonpropagating or evanescent modes. Therefore, the applied steady current causes localized or evanescent modes to build up around any defects in the wire. These extra stored electrons strongly affect the scattering boundary conditions for the propagating modes whenever the Fermi energy approaches either a new quasi-one-dimensional subband or a quasi-bound-state splitting off of the higher confinement subbands. We show that the presence of evanescent modes can lead to either perfect transparency or perfect opaqueness for the scattering modes, even in the presence of scattering defects. For the special case of a \ensuremath{\delta}-function scatterer in the wire we analytically obtain the scattering amplitudes. We also numerically examine a finite-range scatterer.

Kinetics of polymer degradation involving the splitting off of small molecules: Part 3—Treatment of experimental data for dehydrochlorination of PVC in an inert atmosphere

High conversion kinetic runs of PVC dehydrochlorination in a nitrogen atmosphere have been measured. Our data, as well as those available from the literature, have been treated employing the theory developed previously. Excellent agreement has been obtained between theory and experiment. Kinetic parameters obtained by the non-linear least-squares method show that the activation energy and the pre-exponential factor for random elimination of HCl from PVC chains are E α = 170 kJ mol −1 and log ( A s −1 ) = 12·7 independently of the type of polymer. The length of the kinetic chain in the zip propagation varies with PVC type and decreases with increasing temperature. The polymers contain up to 9 mole per cent of structures which do not split off HCl; the content of structural irregularities causing premature zip termination is small.

Asymmetric hydrogenation by heterogenized cationic rhodium phosphinite complexes

Chiral cationic rhodium(I) complexes with bisphosphinite ligands have been immobilized on sulphonated ion exchangers based on styrene-divinylbenzene copolymers, thus allowing the formation of highly active and enantioselective heterogenized catalysts. It was found that low-crosslinked supports are suitable for the preparation of such catalysts, certainly as far as the asymmetric hydrogenation of N-acylated dehydroamino acid esters is concerned. The activity can be increased to optimum values by using gel polymers crosslinked with O.5% divinylbenzene and by preloading the polymers with lithium or ammonium ions. Swelling volumes have been checked and an unexpectedly high ratio of activity to swelling volume was found for the ammonium ion. When the rhodium complex of 4,6- O-benzylidene-2,3- O-bis(diphenylphosphino)-β-D-glucopyranoside (Ph-β-glup) was heterogenized on acid supports it gave higher ee values (95%) in comparison to the homogeneous catalyst (91% ee). This is due to solvolysis catalyzed by the acid function of the polymer which leads to a splitting off of the benzylidene unit of the rhodium complex as verified by immobilization of an analogous complex prepared independently. Recycling experiments displayed high constancy in optical induction which remained stable in all the runs until activity ceased. This was not true for the aminophosphine-phosphinite complex PROPRAPHOS, however, which exhibited a steady reduction of optical induction with activity. Rhodium leaching was found to be < O.5% using the protonated exchangers, but increased when salt forms of the exchangers were employed.

Results Towards Synthesizing the Potential Electrical Conductor Poly(1,2-dithiolo-1,2-dithiole-2,6-diylidene)

Abstract Complex-catalyzed polymerization of bis-alkylthio-acetylenes 4 with nickel catalysts leads to the poly(bis-alkylthio-acetylenes) 2 (P[nbar]: 3–50). The influence of the catalysts, of the structure of the monomers and of the solvent on the polymerization is described. The polymers 2 are insulators and become semiconductors by doping with electron acceptors. Compounds 2 decompose thermically at temperatures higher than 250°C by a splitting off of dialkyldisulfides, dialkylsulfides and alkanethioles. By laser-induced pyrolysis electrical conductors are formed. The 4 are useful starting compounds for synthesizing dimeric 1,4-dithiafulvenes 8. The 1,2-dithiole-thione 3a is available from 2,3-di-tert-butylthiofumarates or perchlorobutadiene with sulfuration reagents. The reactions of 3a with electrophiles and nucleophiles are studied. From 3a, the 3H,6H-2,5-bis-aryl-1,2-thiazolino [5,4-d] 1,2-thiazoline-3,6-dithiones 28 are easily obtainable. Their isomerization to the 3H,6H-3,6-bisarylimino-1,2-dithio...