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Soils store more carbon than other terrestrial ecosystems1,2. How soil organic carbon (SOC) forms and persists remains uncertain1,3, which makes it challenging to understand how it will respond to climatic change3,4. It has been suggested that soil microorganisms play an important role in SOC formation, preservation and loss5–7. Although microorganisms affect the accumulation and loss of soil organic matter through many pathways4,6,8–11, microbial carbon use efficiency (CUE) is an integrative metric that can capture the balance of these processes12,13. Although CUE has the potential to act as a predictor of variation in SOC storage, the role of CUE in SOC persistence remains unresolved7,14,15. Here we examine the relationship between CUE and the preservation of SOC, and interactions with climate, vegetation and edaphic properties, using a combination of global-scale datasets, a microbial-process explicit model, data assimilation, deep learning and meta-analysis. We find that CUE is at least four times as important as other evaluated factors, such as carbon input, decomposition or vertical transport, in determining SOC storage and its spatial variation across the globe. In addition, CUE shows a positive correlation with SOC content. Our findings point to microbial CUE as a major determinant of global SOC storage. Understanding the microbial processes underlying CUE and their environmental dependence may help the prediction of SOC feedback to a changing climate.

Highly fluorescent new 5-substituted 2-iminopyrrolyl boron complexes were tested in OLEDs exhibiting luminances up to 23 530 cd m−2 and an EQEmax of 2.75%.

A group of new boron complexes [BPh2{κ2N,N′-NC4H3-2-C(H)N-C6H4X}] (X = 4-Cl 4c, 4-Br 4d, 4-I 4e, 3-Br 4f, 2-Br 4g, 2-I 4h) containing different halogens as substituents in the N-aryl ring have been synthesized and characterized in terms of their molecular properties. Their photophysical characteristics have been thoroughly studied in order to understand whether these complexes exhibit an internal heavy-atom effect. Phosphorescence emission was found for some of the synthesized halogen-substituted boron molecules, particularly for 4g and 4h. DFT and TDDFT calculations showed that the lower energy absorption band resulted from the HOMO to LUMO (π–π*) transition, except for 2-I 4h, where the HOMO−1 to LUMO transition was also involved. The strong participation of iodine orbitals in HOMO−1 is reflected in the calculated absorption spectra of the iodine derivatives, especially 2-I 4h, when spin–orbit coupling (SOC) was included. Organic light-emitting diodes (OLEDs) based on these complexes, in the neat form or dispersed in a matrix, were also fabricated and tested. The devices based on films prepared by thermal vacuum deposition showed the best performance. When neat complexes were used, a maximum luminance (Lmax) of 1812 cd m−2 was obtained, with a maximum external quantum efficiency (EQEmax) of 0.15%. An EQEmax of ca. 1% along with a maximum luminance of 494 cd m−2 were obtained for a device fabricated by co-deposition of the boron complex and a host compound (1,3-bis(N-carbazolyl)benzene, mCP).

The photophysical properties of conjugated polymers are sensitive to the environment; hence they can be used as probe for local interactions. Here we report on the effect of a ferroelectric polymer in the photoluminescence of a conjugated polymer and show that the local electric field, created by the ferroelectric polymer, induces a photoluminescence quenching, translated into a reduction of the fluorescence intensity and lifetime. Blends and bi-layer systems were studied, with the blends showing a more pronounced effect.

The photophysical properties of two p-phenylenevinylene trimer end-capped with triphenylamine or cyanoacetate groups were investigated with special attention to the different donor-acceptor character of the terminal units, relatively to a same central phenylenevinylene trimer. It is shown that these conjugated small molecules constitute a quite useful model system to understand how the end-capped groups couple to the central molecular unit with respect to energy and/or electron transfer. The study of these two compounds in solution showed that after photoexcitation, the conformational relaxation leads to an increase in the conjugated backbone planarization. A more pronounced intramolecular charge transfer in the excited state of the molecule with two alkyl cyanoacetate groups as electron-withdrawing ends was also found. The molecular structures of the two compounds are especially advantageous for electronic applications such as organic photovoltaics, for example, due to their narrow optical band gaps that potentially lead to a more efficient photon harvesting in the organic devices fabricated with these compounds.

New bis- and tris(iminopyrrole)-functionalized linear (1,2-(HNC4 H3 -C(H)N)2 -C6 H4 (2), 1,3-(HNC4 H3 -C(H)N)2 -C6 H4 (3), 1,4-(HNC4 H3 -C(H)N)2 -C6 H4 (4), 4,4'-(HNC4 H3 -C(H)N)2 -(C6 H4 -C6 H4 ) (5), 1,5-(HNC4 H3 C-(H)N)2 -C10 H6 (6), 2,6-(HNC4 H3 C-(H)N)2 -C10 H6 (7), 2,6-(HNC4 H3 C-(H)N)2 -C14 H8 (8)) and star-shaped (1,3,5-(HNC4 H3 -C(H)N-1,4-C6 H4 )3 -C6 H3 (9)) π-conjugated molecules were synthesized by the condensation reactions of 2-formylpyrrole (1) with several aromatic di- and triamines. The corresponding linear diboron chelate complexes (Ph2 B[1,3-bis(iminopyrrolyl)-phenyl]BPh2 (10), Ph2 B[1,4-bis(iminopyrrolyl)-phenyl]BPh2 (11), Ph2 B[4,4'-bis(iminopyrrolyl)-biphenyl]BPh2 (12), Ph2 B[1,5-bis(iminopyrrolyl)-naphthyl]BPh2 (13), Ph2 B[2,6-bis(iminopyrrolyl)-naphthyl]BPh2 (14), Ph2 B[2,6-bis(iminopyrrolyl)-anthracenyl]BPh2 (15)) and the star-shaped triboron complex ([4',4'',4'''-tris(iminopyrrolyl)-1,3,5-triphenylbenzene](BPh2 )3 (16)) were obtained in moderate to good yields, by the treatment of 3-9 with B(C6 H5 )3 . The ligand precursors are non-emissive, whereas most of their boron complexes are highly fluorescent; their emission color depends on the π-conjugation length. The photophysical properties of the luminescent polyboron compounds were measured, showing good solution fluorescence quantum yields ranging from 0.15 to 0.69. DFT and time-dependent DFT calculations confirmed that molecules 10 and 16 are blue emitters, because only one of the iminopyrrolyl groups becomes planar in the singlet excited state, whereas the second (and third) keeps the same geometry. Compound 13, in which planarity is not achieved in any of the groups, is poorly emissive. In the other examples (11, 12, 14, and 15), the LUMO is stabilized, narrowing the gap between the highest occupied molecular orbital and the lowest unoccupied molecular orbital (HOMO-LUMO), and the two iminopyrrolyl groups become planar, extending the size of the π-system, to afford green to yellow emissions. Organic light-emitting diodes (OLEDs) were fabricated by using the new polyboron complexes and their luminance was found to be in the order of 2400 cd m(-2) , for single layer devices, increasing to 4400 cd m(-2) when a hole-transporting layer is used.

A new oligomer-type para-phenylenevinylene end-capped with triphenylamine groups (TPAPV) was synthesised and its optical properties thoroughly investigated. Fluorescence quenching studies showed that an important fraction of the photogenerated excitons formed in TPAPV is quenched by [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) in blend films, therefore indicating efficient exciton dissociation and potential applications in organic photovoltaic (PV) cells. Planar heterojunction organic photovoltaic cells containing TPAPV as the electron-donor were fabricated and devices with structure ITO/TPAPV(6 nm)/C60(50 nm)/BCP(10 nm)/Ag exhibited an open-circuit voltage (VOC), short-circuit current (JSC), fill factor (FF), and power-conversion efficiency (PCE) of 0.92 V, 2.9 mA cm−2, 47.8%, and 1.23%, respectively.

The modulation of conjugated polyelectrolyte fluorescence response by nonionic surfactants is dependent on the structures of the surfactant and polymer, polymer average molecular weight, and polyelectrolyte–surfactant interactions. In this paper, we study the effect of nonionic n-alkyl polyoxyethylene surfactants (CiEj) with different alkyl chain lengths (CiE5 with i = 6, 8, 10, and 12) and number of oxyethylene groups (C12Ej with j = 5, 7, and 9) on the photophysics and ionic conductivity of poly{[9,9-bis(6′-N,N,N-trimethylammonium)-hexyl]-2,7-fluorene-alt-1,4-phenylene}bromide (HTMA-PFP) in dimethyl sulfoxide–water 4% (v/v). Molecular dynamics simulations show that HTMA-PFP chains tend to approach as the simulation evolves. However, the minimum distance between the polymer centers of mass increases upon addition of the surfactant and grows with both the surfactant alkyl chain length and the number of oxyethylene groups, although there are no specific polymer–surfactant interactions. A significant increa...

Introduction: Ceramic veneers color is determined by the color and thickness of the ceramic, the cement and dental substrate color [1,2]. Changes in the thickness of feldspathic veneers, as well as the cement used, drastically influence the final color of the restoration [3]. Fluorescence is the optical property responsible for the perception of tooth vitality [4]. In a tooth, this optical property is mainly determined by dentin as it has more collagen (organic matter), which contains fluorescence-releasing amino acids, such as tryptophan, providing three times the fluorescence of enamel [5,6]. Aim of the study: Fluorescence emission evaluation of feldspathic ceramics using different cement colors as well as different ceramic thickness. Materials and methods: Feldspathic ceramic CEREC blocks (color A2) were cut with a manual microtome at a speed of 450 rpm with refrigeration to obtain 40 samples with a thickness of 0.5 and 0.8 mm. Filtek Supreme XTE Body composite resin discs with a thickness of 1mm [7] were produced using a resin frame. The discs were polymerized with a light-curing Elipar S10 Led. Surface treatment of the ceramic was carried out according to the manufacturer’s instructions. Ceramic samples were cemented to the composite resin discs with Relyx Veneer B0,5 / white or with Filtek Supreme XTE Body color A3 (previously heated in a resin oven). The cementation of the groups was done with a constant force of 50 Newtons for 60 seconds and polymerized for 40 seconds with Elipar S10 Led photopolymerizer. Fluorescence spectra were obtained on a SPEX Fluorolog2I2I spectrofluorometer at a wavelength of 380 nm and at room temperature. Results: An increase in thickness intensified the emission of fluorescence. The cementation material used in the study didn’t show statistically significant differences in fluorescence emission intensity when used in two different thicknesses (p = 0,378). Nonetheless, significant differences (p

Three new phenylene vinylene oligomers containing either a bis(oligoether)phenyl ring or a benzothiadiazole central unit and either carbazole or triphenylamine end capping groups were synthesized and characterized. The photophysical characterization in solution reveals a significant variation in properties depending on the combined moieties. Amplified spontaneous emission in neat drop cast films of two of these compounds was studied. One of them was also characterized in terms of its two-photon photoluminescence.

A homologous series of p-phenylenevinylene oligomers (PPV)n (n = 3–5) with terminal dialkylamino groups have been synthesized, and characterized. The photophysical and solvatochromic properties of oligomers with three, four, and five phenyl groups were investigated in solution through steady-state and time-resolved fluorescence. The red-shift seen in absorption and photoluminescence (PL) spectra on increasing chain length is consistent with an extension of the conjugation length. Decreasing solvent polarity leads to small shifts of the absorption spectra and large blue-shifts of the PL spectra. Time-resolved emission on these oligomers allows separation of conformational and solvent contributions to their photophysical behavior. Global analysis of fluorescence decays collected at different emission wavelengths shows biexponential behavior in toluene at room temperature. The longer time appears as a decay component at all emission wavelengths and decreases from 949 to 850 ps with increasing chain length. T...

Photoexcitation of flexible conjugated polymers is invariably followed by a fast conformational/torsional relaxation towards a configuration favouring coplanarity of the conjugated segments. In general, the experimental relaxation rate constant (k(CR)) depends on the solvent viscosity (η) and temperature (T), and is not proportional to T/η. A theory capable of explaining the observed dependence of k(CR) on T and η over a wide range of these variables is not available. This gap is filled here by presenting a stochastic model that includes the participation of the oligomer side chain in storing and dissipating the stresses induced by photoexcitation. The model is able to account for the softening of solute-solvent interactions and its predictions are found to be in excellent agreement with the observed relaxation rate constants of a series of substituted p-phenylenevinylene trimers [ChemPhysChem 2009, 10, 448-454] on T, η and the size of the side-chains.

The interaction between three poly(9,9-bis(6-N,N,N-trimethylammonium)hexyl)fluorene phenylene) bromide (HTMA-PFP) samples of different molecular weights (Mn ) 14.5, 30.1 and 61.3 kg/mol) and both dsDNA and ssDNA secondary structures has been studied using UV-visible absorption and fluorescence spectroscopies (including steady-state, time-resolved, and anisotropy measurements for the latter), viscosity, and electrical conductivity in 4% (v/v) DMSO-water mixtures. At low nucleic acid concentrations, formation of a 1:1 complex in terms of HTMA-PFP repeat units and DNA bases occurs. This interaction results in quenching of polymer emission. For higher molar ratios of DNA to HTMA-PFP, corresponding to charge neutralization, a second process is observed that is attributed to aggregate formation. From the changes in the absorption spectra, the polymer aggregation constant and the aggregate absorption spectra were calculated by applying an iterative method. Polymer aggregation dramatically quenches HTMA-PFP fluorescence in the region of the electroneutrality point. Under these conditions, the ratio of the emission intensity at 412 nm (maximum) to that at 434 nm (I 412 /I 434 ) reaches a minimum, the electrical conductivity decreases, and the viscosity of the solution remains constant, showing that the DNA concentration can be determined through various HTMAPFP physicochemical properties. With respect to the photophysical parameters (emission quantum yield, shape and shift of emission spectra), no significant differences were observed between dsDNA and ssDNA or with conjugated polymer or DNA molecular weight. The two short-lived components in the fluorescence decays are attributed to the presence of aggregates. Aggregates are also suggested to be responsible for the decrease in the fluorescence anisotropy through interchain exciton migration.

Arrival sequencing and scheduling (ASS) at airports is an NP-hard problem. Much effort has been made to use permutation-representation-based genetic algorithms (GAs) to tackle this problem, whereas this paper attempts to design an efficient GA based on a binary representation of arriving queues. Rather than using the order and/or arriving time of each aircraft in the queue to construct chromosomes for GAs, this paper uses the neighboring relationship between each pair of aircraft, and the resulted chromosome is a 0-1-valued matrix. A big advantage of this binary representation is a highly efficient uniform crossover operator, which is normally not applicable to those permutation representations. The strategy of receding horizon control (RHC) is also integrated into the new GA to attack the dynamic ASS problem. An extensive comparative simulation study shows that the binary-representation-based GA outperforms the permutation-representation-based GA.

Models that demonstrate environmental regulation as a consequence of organism and environment coupling all require a number of core assumptions. Many previous models, such as Daisyworld, require that certain environment-altering traits have a selective advantage when those traits also contribute towards global regulation. We present a model that results in the regulation of a global environmental resource through niche construction without employing this and other common assumptions. There is no predetermined environmental optimum towards which regulation should proceed assumed or coded into the model. Nevertheless, polymorphic stable states that resist perturbation emerge from the simulated co-evolution of organisms and environment. In any single simulation a series of different stable states are realised, punctuated by rapid transitions. Regulation is achieved through two main subpopulations that are adapted to slightly different resource values, which force the environmental resource in opposing directions. This maintains the resource within a comparatively narrow band over a wide range of external perturbations. Population driven oscillations in the resource appear to be instrumental in protecting the regulation against mutations that would otherwise destroy it. Sensitivity analysis shows that the regulation is robust to mutation and to a wide range of parameter settings. Given the minimal assumptions employed, the results could reveal a mechanism capable of environmental regulation through the by-products of organisms.

Two p-phenylenevinylene (PV) trimers, containing 3'-methylbutyloxyl (in MBOPV3) and 2'-ethylhexyloxyl (in EHOPV3) side chains, are used as model compounds of PV-based conjugated polymers (PPV) with the purpose of clarifying the origin of fast (picosecond time) components observed in the fluorescence decays of poly[2-methoxy-5-(2'-ethylhexyloxy)-p-phenylenevinylene] (MEH-PPV). The fluorescence decays of MBOPV3 and EHOPV3 reveal the presence of similar fast components, which are assigned to excited-state conformational relaxation of the initial population of non-planar trimer conformers to lower-energy, more planar conformers. The rate constant of conformational relaxation k(CR) is dependent on solvent viscosity and temperature, according to the empirical relationship k(CR)=aeta(o) (-alpha)exp(-alphaE(eta)/RT), where aeta(o) (-alpha) is the frequency factor, eta(o) is the pre-exponential coefficient of viscosity, E(eta) is the activation energy of viscous flow. The empirical parameter alpha, relating the solvent microscopic friction involved in the conformational change to the macroscopic solvent friction (alpha=1), depends on the side chain. The fast component in the fluorescence decays of MEH-PPV polymers (PPVs), is assigned to resonance energy transfer from short to longer polymer segments. The present results call for revising this assignment/interpretation to account for the occurrence of conformational relaxation, concurrently with energy transfer, in PPVs.

The inability of airport capacity to meet the growing air traffic demand is a major cause of congestion and costly delays. Airport capacity management (ACM) in a dynamic environment is crucial for the optimal operation of an airport. This paper reports on a novel method to attack this dynamic problem by integrating the concept of receding horizon control (RHC) into a genetic algorithm (GA). A mathematical model is set up for the dynamic ACM problem in a multiairport system where flights can be redirected between airports. A GA is then designed from an RHC point of view. Special attention is paid on how to choose those parameters related to the receding horizon and terminal penalty. A simulation study shows that the new RHC-based GA proposed in this paper is effective and efficient to solve the ACM problem in a dynamic multiairport environment

No-tillage (NT) is becoming increasingly attractive to farmers because it clearly reduces production costs relative to conventional tillage (CT). However, many producers in southern Italy are reluctant to adopt this practice because NT can have contrasting consequences on grain yield depending on weather conditions. The effect of NT and CT on continuous durum wheat ( Triticum durum Desf.) under rainfed Mediterranean conditions was studied, over a 3-year period (2000–2002) at two locations (Foggia and Vasto) in southern Italy. Yield, grain quality [thousand kernel weight (TKW), test weight (TW) and protein content (PC)] and soil water content were assessed. Higher yield was obtained with NT than CT in the first 2 years at Foggia. In contrast, mean yield and quality parameters at Vasto were similar for the two treatments, except in the third year in which CT produced more than NT (4.6 Mg ha −1 versus 2.9 Mg ha −1 ). At Foggia, TW and TKW were higher in NT than CT in all years. Highest PC was obtained under CT (19.6% and 15.5% for CT versus 14.7% and 11.4% for NT, respectively, in the growing season 2000–2001 and 2001–2002) indicating that grain was shriveled with low starch accumulation. At Foggia, where this study was part of a long-term experiment started in 1995, a strong correlation was observed between yield and rainfall during the wheat growing season. The coefficient of determination ( R 2 ) values for CT and NT were 0.69 * and 0.31 ns, respectively, and the regression straight line crossed around 300 mm of rainfall. These results indicate that NT was superior below this rainfall value, whereas more rainfall enhanced yield in CT. We conclude that NT performed better at Foggia with limited rainfall during the durum wheat growing season. The superior effect of NT in comparison to CT, was due to lower water evaporation from soil combined with enhanced soil water availability.

Electron-acceptor units, combined with bithiophene substituted with flexible chains end-functionalized with cross-linkable moieties, provide soluble donor-acceptor-donor (DAD) π-conjugated oligomer-type molecules with cross-linking ability and broad absorption in the visible spectrum. A study on the cross-linking conditions of the new oligomers to yield insoluble polymer networks is presented, including conditions for obtaining polymer films over poly(3,4-ethylenedioxythiophene):polystyrene sulfonate-covered substrates. The combination of the DAD molecular design and cross-linking functionality opens prospects for applications in solution-processed small-molecule solar cells with morphologically-stable organic layers.

There is presently strong evidence that anthocyanins protect plant tissues from excessive solar radiation. In support of this, we have shown that the red flavylium form of anthocyanins (AH+) dissipates more than 99% of the absorbed radiation energy into heat through a series of ultra-fast excited-state processes, among which excited-state proton transfer to water plays the major role. In this work, it is shown for the first time that the less exuberant (colorless) hemiketal form of three common anthocyanins (pelargonin, cyanin, and malvin) is equally efficient at dissipating the absorbed (UV-B) radiation into heat by fast photo-tautomerization, which yields the cis-chalcone form in its ground state in a few picoseconds.

Resonance Raman (RR) spectroscopy was used to investigate conformational characteristics of the hemes of several ferricytochromes of the cytochrome c 3 family, electron transfer proteins isolated from the periplasm and membranes of sulfate-reducing bacteria. Our analysis concentrated on the low-frequency region of the RR spectra, a fingerprint region that includes vibrations for heme-protein C–S bonds [ν(CaS)]. It has been proposed that these bonds are directly involved in the electron transfer process. The three groups of tetraheme cytochrome c 3 analyzed, namely Type I cytochrome c 3 (TpIc 3s), Type II cytochrome c 3 (TpIIc 3s) and Desulfomicrobium cytochromes c 3, display different frequency separations for the two ν(CaS) lines that are similar among members of each group. These spectral differences correlate with differences in protein structure observed among the three groups of cytochromes c 3. Two larger cytochromes of the cytochrome c 3 family display RR spectral characteristics for the ν(CaS) lines that are closer to TpIIc 3 than to TpIc 3. Two other multiheme cytochromes from Desulfovibrio that do not belong to the cytochrome c 3 family display ν(CaS) lines with reverse relative areas in comparison with the latter family. This RR study shows that the small differences in protein structure observed among these cytochrome c 3 correlate to differences on the heme–protein bonds, which are likely to have an impact upon the protein function, making RR spectroscopy a sensitive and useful tool for characterizing these cytochromes.

SUMMARY We use a genetic algorithm to evolve neural models of path integration,with particular emphasis on reproducing the homing behaviour of Cataglyphis fortis ants. This is done within the context of a complete model system, including an explicit representation of the animal's movements within its environment. We show that it is possible to produce a neural network without imposing a priori any particular system for the internal representation of the animal's home vector. The best evolved network obtained is analysed in detail and is found to resemble the bicomponent model of Mittelstaedt. Because of the presence of leaky integration, the model can reproduce the systematic navigation errors found in desert ants. The model also naturally mimics the searching behaviour that ants perform once they have reached their estimate of the nest location. The results support possible roles for leaky integration and cosine-shaped compass response functions in path integration.

Soil moisture and temperature, sowing depth and penetration resistance affect the time and percentage of seedling emergence, which are crucial for the simulation of drought-limited crop production. The aim of this research was to measure the effect of soil water potential on germination and emergence, shoot and root elongation rates (SER and RER) of two different seed/crop types. Sugar beet and durum wheat seeds were sown into two soils (clay and loam), submitted to five matric potentials (-0.01, -0.1, -0.2, -0.4 and -0.8 MPa) and incubated at constant temperature (25 degrees C) and humidity. Cumulative count analysis was used to estimate parameters of the distribution of germination or emergence times for each box of beet or wheat seeds and to derive estimates for base potentials (psi(b)), hydrothermal times (H) and numbers of viable units. In a second experiment, NaCl solution was used to mimic the soil matric potentials to estimate potential RER and SER. Germination of sugar beet was slightly more sensitive to matric potential than durum wheat (psi(b) Of - 1.13 and - 1.23 MPa, respectively). H-(g) was longer for sugar beet than for durum wheat (67 vs 47 MPa degrees Cd). For emergence Ob was similar for both seed types and soils but hydrothermal times (H-(e)) were 40 MPa degrees Cd higher for sugar beet than for wheat. Emergence was about 20 MPa degrees Cd earlier in loam than in clay. SER measured in soils were similar for both crops and for durum wheat it agreed with those determined in NaCl solution. RER and SER fell with decreasing osmotic potential to approximately 20% of their maximum values (1.03 rum h(-1) and 0.57 mm h(-1), respectively). Seedling viability decreased with decreasing matric potential and more in clay than in loam soil and more for sugar beet than durum wheat. Seed and soil aggregate size are discussed with respect to the effects of water diffusion and soil-seed contact on germination and emergence modelling.

The tetraheme protein cytochrome c3 (Cyt-c3) from Desulfovibrio gigas, immobilized on a self-assembled monolayer (SAM) of 11-mercaptoundecanoic acid, is studied by theoretical and spectroscopic methods. Molecular dynamics simulations indicate that the protein docks to the negatively charged SAM via its lysine-rich domain around the exposed heme IV. Complex formation is associated with only little protein structural perturbations. This finding is in line with the resonance Raman and surface-enhanced resonance Raman (SERR) spectroscopic results that indicate essentially the same heme pocket structures for the protein in solution and adsorbed on SAM-coated Ag electrodes. Electron- and proton-binding equilibrium calculations reveal substantial negative shifts of the redox potentials compared to the protein in solution. The magnitude of these shifts decreases in the order heme IV (� 161 mV) . heme III (� 73 mV) . heme II (� 57 mV) . heme I (� 26 mV), resulting in a change of the order of reduction. These shifts originate from the distance-dependent electrostatic interactions between the SAM headgroups and the individual hemes, leading to a stabilization of the oxidized forms. The results of the potential- dependent SERR spectroscopic analyses are consistent with the theoretical predictions and afford redox potential shifts of � 160 mV (heme IV), � 90 mV (heme III), � 70 mV (heme II), and 120 mV (heme I) relative to the experimental redox potentials for Cyt-c3 in solution. SERR spectroscopic experiments reveal electric-field-induced changes of the redox potentials also for the structurally very similar Cyt-c3 from Desulfovibrio vulgaris, although the shifts are somewhat smaller compared to Cyt-c3 from D. gigas. This study suggests that electric-field-induced redox potential shifts may also occur upon binding to biomembranes or partner proteins and thus may affect biological electron transfer processes.

The secretin receptor is a member of a large family of G-protein-coupled receptors that recognize polypeptide hormone and/or neuropeptides. Charged, conserved residues might play a key role in their function, either by interacting with the ligand or by stabilizing the receptor structure. Of the four charged amino acids that are conserved in the whole secretin receptor family, D49 and R83 (in the N-terminal domain) were probably important for the secretin receptor structure: replacement of D49 by H or R and of R83 by D severely reduced both the maximal response to secretin and its potency. No functional secretin receptor could be detected after replacement of R83 by L. Mutation of D49 to E, A, or N had no effect or reduced 5-fold the potency of secretin. The highly conserved positive charges found at the extracellular ends of TM III (K194) and IV (R255) were important for the secretin receptor function, as K194 mutation to A or Q and R255 mutation to Q or D decreased the secretin's affinity 15- to 1000-fold, respectively. Six extracellular charged residues are conserved in closely related receptors but not in the whole family. K121 (TM I) and R277 (TM V) were not important for functional secretin receptor expression. D174 (TM II) was necessary to stabilize the active receptor structure: the D174N mutant receptors were unable to stimulate normally the adenylate cyclase in response to secretin, and functional D174A receptors could not be found. Mutation of R255, E259 (second extracellular loop), and E351 (third extracellular loop) to uncharged residues reduced only 10- to 100-fold the secretin potency without changing its efficacy: these residues either stabilized the active receptor conformation or formed hydrogen rather than ionic bonds with secretin. Mutation of K121 (TM I) to Q or L and of R277 (TM V) to E or Q did not affect the receptor functional properties.

A secretin receptor was cloned from a commercial human pancreatic complementary DNA (cDNA) bank. The amino acid sequence deduced from the nucleotide sequence differed slightly from the three different sequences previously published, suggesting a genetic polymorphism of the human receptor. The binding properties of the receptor were evaluated by testing natural secretin, related peptides, and synthetic analogs or fragments on membranes of Chinese hamster ovary (CHO) cells expressing the receptor after transfection. The second-messenger coupling was evaluated by adenylate cyclase measurement. The human secretin receptor was compared with the rat and the rabbit receptors. In the three animals species, rat and human secretin were equipotent; rabbit secretin was equipotent on human and rabbit secretin receptors and less potent on the rat receptor. Similar data were obtained for the [Arg 16 ]-secretin analog. Deletion of histidine 1 and replacement of aspartate 3 reduced the affinity of the peptides for the three receptors; however, the reduction was more pronounced on rat than on human and rabbit secretin receptors. Finally, the low affinity of the rat and human receptors for vasoactive intestinal peptide (VIP) was identical; the rabbit receptor, however, had a 20-fold higher affinity. Thus the human secretin receptor shows properties of both rat and rabbit receptors. Evaluation of the properties of chimeric receptors will be useful to fit the ligand on the receptors.

We typed the Sardinian population at the D1S80 VNTR locus. Nineteen alleles were detected in a sample of 92 unrelated individuals, allele frequency distribution showing a modal pattern mostly in agreement with other Caucasoid populations. A high degree of heterozygosity (observed value=80.4%) was present. Goodness-of-fit tests demonstrated no departure from Hardy-Weinberg expectations. Data regarding heterozygosity, number of alleles and singletons appeared in accordance with the IAM mutation-drift equilibrium model and showed no evidence of hidden substructuring.

Reactions of 2-(N-arylimino)pyrroles (HNC4H3C(H)=N-Ar) with triphenylboron (BPh3) in boiling toluene afford the respective highly emissive N,N'-boron chelate complexes, [BPh2 {κ(2)N,N'-NC4H3C(H)=N-Ar}] (Ar=C6H5 (12), 2,6-Me2-C6H3 (13), 2,6-iPr2-C6H3 (14), 4-OMe-C6H4 (15), 3,4-Me2-C6 H3 (16), 4-F-C6H4 (17), 4-NO2-C6H4 (18), 4-CN-C6H4 (19), 3,4,5-F3-C6H2 (20), and C6F5 (21)) in moderate to high yields. The photophysical properties of these new boron complexes largely depend on the substituents present on the aryl rings of their N-arylimino moieties. The complexes bearing electron-withdrawing aniline substituents 17-20 show more intense (e.g., ϕf =0.71 for Ar=4-CN-C6H4 (19) in THF), higher-energy (blue) fluorescent emission compared to those bearing electron-donating substituents, for which the emission is redshifted at the expense of lower quantum yields (ϕf=0.13 and 0.14 for Ar=4-OMe-C6H4 (15) and 3,4-Me2-C6H3 (16), respectively, in THF). The presence of substituents bulkier than a hydrogen atom at the 2,6-positions of the aryl groups strongly restricts rotation of this moiety towards coplanarity with the iminopyrrolyl ligand framework, inducing a shift in the emission to the violet region (λmax =410-465 nm) and a significant decrease in quantum yield (ϕf=0.005, 0.023, and 0.20 for Ar=2,6-Me2-C6H3 (13), 2,6-iPr2-C6H3 (14), and C6F5 (21), respectively, in THF), even when electron-withdrawing groups are also present. Density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations have indicated that the excited singlet state has a planar aryliminopyrrolyl ligand, except when prevented by steric hindrance (ortho substituents). Calculated absorption maxima reproduce the experimental values, but the error is higher for the emission wavelengths. Organic light-emitting diodes (OLEDs) have been fabricated with the new boron complexes, with luminances of the order of 3000 cd m(-2) being achieved for a green-emitting device.

The contribution of the extracellular loops of the secretin receptor to the recognition of secretin was investigated by transfection in CHO cells of chimeric receptors, in which the three loops of the secretin recombinant receptor were replaced by the corresponding sequences of the glucagon receptor. The role of the third loop could not be evaluated as the transfected cells did not respond to secretin. Replacement of extracellular loop 2 reduced markedly the capability of secretin to occupy the receptor but did not alter the capacity of the receptor to discriminate between peptide analogues modified in position 3. Replacement of the first extracellular loop not only reduced the potency of secretin but also decreased the capacity of the receptor to discriminate between ligands having in position 3 an aspartate (as in secretin), an asparagine, or a glutamic acid. This change in receptor properties was reproduced by a single mutation of lysine 173 of the receptor into isoleucine. Thus, the basic amino acid in position 173 is likely to interact with aspartate 3 of secretin. As an aspartate is also present in position 3 of VIP and PACAP, two peptides related to secretin, and a lysine residue is conserved in the first extracellular loop of the VIP and PACAP receptors, this interaction may be a key element of peptide recognition by this receptor family.

Searching the Pareto front for multiobjective optimization problems usually involves the use of a population-based search algorithm or of a deterministic method with a set of different single aggregate objective functions. The results are, in fact, only approximations of the real Pareto front. In this paper, we propose a new deterministic approach capable of fully determining the real Pareto front for those discrete problems for which it is possible to construct optimization algorithms to find the k best solutions to each of the single-objective problems. To this end, two theoretical conditions are given to guarantee the finding of the actual Pareto front rather than its approximation. Then, a general methodology for designing a deterministic search procedure is proposed. A case study is conducted, where by following the general methodology, a ripple-spreading algorithm is designed to calculate the complete exact Pareto front for multiobjective route optimization. When compared with traditional Pareto front search methods, the obvious advantage of the proposed approach is its unique capability of finding the complete Pareto front. This is illustrated by the simulation results in terms of both solution quality and computational efficiency.

The three compounds [BPh(2)(κ(2)N,N'-NC(4)H(3)C(H)=N-C(6)H(5))] (A), [BPh(2)(κ(2)N,N'-NC(4)H(3)C(H)=N-1,4-C(6)H(4)-N=H)C-H(3)C(4)N-N,N'κ(2))BPh(2)] (B) and [BPh(2)(κ(2)N,N'-NC(4)H(3)C(H)=N-4,4'-C(6)H(4)-C(6)H(4)-N=(H)C-H(3)C(4)N-N,N'κ(2))BPh(2)] (C) are blue to green light emitters with average to excellent quantum yields. DFT and TD-DFT calculations were performed in order to understand their behaviour. The geometry of their ground and singlet excited state was optimised, and their absorption patterns and emission were calculated. The large dihedral angles between the planes of the N-aryl and 2-formiminopyrrolyl moieties of the chelating ligand drop considerably, leading to an almost planar geometry in the singlet state. In the three species, the lowest energy absorption occurs at 383, 428, and 419 nm, being calculated at 377, 502, and 529 nm in the gas-phase (slightly shifted in the right direction in THF). It results from a HOMO to LUMO excitation, and was assigned to a transition between π and π* orbitals (ILCT) of the iminopyrrolyl ligand, despite small differences in the exact composition of the HOMO and LUMO in A, B, and C. Introduction of the LB94 functional did not improve the calculated absorption wavelengths, but PBE0 with an all electron basis set within the SOPERT approximation led to better agreement with the experimental absorption maxima and a good reproduction of the excited state lifetimes. The estimated emission wavelengths reproduce the experimental trends.

The competitive interaction has been studied between double-stranded DNA (dsDNA), the cationic conjugated polyelectrolyte (CPE) poly[9,9-bis(6-N,N,N-trimethylamonium)hexyl)-fluorene-phenylene)] bromide (HTMA-PFP) and anionic or neutral surfactants (sodium dodecyl sulfonate, SDSu, and n-dodecyl pentaoxyethylene glycol ether, C(12)E(5)) in 4% (v/v) dimethyl sulfoxide (DMSO)-water using UV/visible absorption and fluorescence spectroscopy. Dramatic changes are observed in the spectroscopic behavior of the system depending on the order of addition of the reagents, the surfactant charge, and concentration range. If the neutral C(12)E(5) is added to the HTMA-PFP/dsDNA complex, no significant spectroscopic changes are observed. However, if SDSu is added to the same complex, a dramatic increase of the absorbance and emission intensity is observed for surfactant concentrations above the critical micelle concentration (cmc). In contrast, if dsDNA is added to HTMA-PFP/surfactant systems (with surfactant concentrations above their cmc) no significant changes are observed with SDSu, while a dramatic quenching of polymer emission is observed with C(12)E(5), which can be explained quantitatively in terms of HTMA-PFP/surfactant/DNA complexation and the subsequent polymer aggregation upon charge neutralization. The results are compared with those for the binary systems (HTMA-PFP/DNA and HTMA-PFP/surfactants) and indicate the importance of electrostatic interactions between HTMA-PFP and oppositely charged species in the aggregation processes.

We review and discuss the structural consequences of embedding a random network within a metric space such that nodes distributed in this space tend to be connected to those nearby. We find that where the spatial distribution of nodes is maximally symmetrical some of the structural properties of the resulting networks are similar to those of random nonspatial networks. However, where the distribution of nodes is inhomogeneous in some way, this ceases to be the case, with consequences for the distribution of neighborhood sizes within the network, the correlation between the number of neighbors of connected nodes, and the way in which the largest connected component of the network grows as the density of edges is increased. We present an overview of these findings in an attempt to convey the ramifications of spatial embedding to those studying real-world complex systems. © 2010 Wiley Periodicals, Inc. Complexity 16: 20–28, 2010 © 2010 Wiley Periodicals, Inc.

New 2-iminophenanthro[9,10-c]pyrrole ligand precursors containing phenyl or 2,6-diisopropylphenyl groups at the imine nitrogen substituent, 2-arylformiminophenanthro[9,10-c]pyrroles (aryl = phenyl IIa, 2,6-diisopropylphenyl IIb) were synthesized and deprotonated in situ with NaH, originating solutions of the corresponding sodium salts (IVa, IVb). The reaction of these salts with zinc chloride gave the homoleptic bis-ligand Zn(II) complexes [Zn(kappa(2)N,N'-2-arylformiminophenanthro[9,10-c]pyrrolyl)(2)] (aryl = phenyl 2a, 2,6-diisopropylphenyl 2b). The new ligand precursors and complexes were characterized by NMR, elemental analysis, UV/vis spectroscopy, and X-ray crystallography, when possible. The photophysical characterization was carried out using steady-state and picosecond time-resolved luminescence techniques in solution. The influence of the pi-extended conjugation of the condensed phenanthro group on the deprotonated iminopyrrolyl ligands coordinated to Zn(2+) greatly enhances fluorescence quantum yields of the complexes (2a, 2b) in relation to those of their ligand precursors (IIa, IIb). Complex 2a shows emission in the green spectral region (lambda(max) = 494 nm), presenting the highest fluorescence quantum yield (phi(f) = 8.8%). In the case of the complex 2b (phi(f) = 3.9%), the bulkiness of the 2,6-diisopropyl substituents of the arylimino group highly restricts the aryl ring rotation toward coplanarity with the ligand framework, inducing a shift in the emission to the blue region (lambda(max) = 459 nm). The values of the radiative (k(f)) and radiationless rate constants (k(nr)) show that the fluorescence quantum yield enhancement in the complexes results from a 50-fold increase in k(f) values, indicating much more allowed pi-pi* transitions in complexes 2a and 2b than those occurring in the ligand precursors IIa and IIb, with an essentially n-pi* character. These assignments were confirmed by density-functional theory (DFT) and time-dependent DFT (TD-DFT) molecular orbital calculations. Simple 2-aryliminopyrrole ligand precursors (Ia, Ib) and their Zn(II) complexes (1a, 1b) were also prepared to compare their photophysical properties with those of the corresponding 2-aryliminophenanthro[9,10-c]pyrrolyl compounds.

Genetic Algorithms (GAs) have a good potential of solving the Gate Assignment Problem (GAP) at airport terminals, and the design of feasible and efficient evolutionary operators, particularly, the crossover operator, is crucial to successful implementations. This paper reports an application of GAs to the multi-objective GAP. The relative positions between aircraft rather than their absolute positions in the queues to gates is used to construct chromosomes in a novel encoding scheme, and a new uniform crossover operator, free of feasibility problems, is then proposed, which is effective and efficient to identify, inherit and protect useful common sub-queues to gates during evolution. Extensive simulation studies illustrate the advantages of the proposed GA scheme with uniform crossover operator.

Non-Stokes-Einstein relaxation: The rate constant of conformational relaxation of a phenylenevinylene trimer (see picture) in different solvents is proportional to eta(-alpha), with alpha values decreasing from close to unity (low viscosity) to zero at sufficiently high solvent viscosity. This behaviour is attributed to the flexible methylbutyl side chains of the trimer, which partially screen the solvent friction. The p-phenylenevinylene (PV) trimer (MBOPV3) was used to probe the effect of conformational relaxation on fluorescence decays of PV-based polymers in the high solvent viscosity regime, from n-hexadecane (3.45 cP at 293 K) to liquid paraffin (123 cP at 293 K), and in dilute poly(methyl methacrylate) (PMMA) solid films. The effect of intermolecular energy transfer and radiative transport on the fluorescence decays was also analysed by increasing the concentration of MBOPV3 in the PMMA films up to a pure MBOPV3 film. The rate constant of conformational relaxation was found to decrease with increasing solvent viscosity up to about 23 cP, but then becomes viscosity independent. The non-Stokes-Einstein behaviour of k(CR) versus eta over the whole viscosity range apparently results from the presence of the flexible methylbutyl side chains of MBOPV3, which partially screens the solvent friction. Conformational relaxation is not observed in very dilute PMMA solid films, where the fluorescence decay becomes single exponential. The decays become multi-exponential again with an increase of MBOPV3 concentration in the PMMA films, but in this case it is due to intermolecular (interchain) energy transfer from less planar to more planar conformations of MBOPV3. In the pure MBOPV3 film, interchain energy transfer (radiative and non-radiative) is the major process responsible for the observed (tetra-exponential) decays.

The synthesis and photophysical properties of six new abietic acid based amine end-capped p-phenylenevinylene trimers (AECPV3) in their lowest excited singlet states are presented. The AECPV3 compounds show a large red-shift of both the absorption (25-30 nm) and emission (37-42 nm) maxima with respect to those of the corresponding trimers. Picosecond time-resolved fluorescence data reveal the presence of a fast conformational relaxation process (40-62 ps) of the initially excited compounds, leading to more planar conformers. The conformational relaxation time is proportional to the volume of both the side chain and the amine groups.

The interaction between the cationic HTMA-PFP (Poly-(9,9-bis(6'-N,N,N-trimethylammonium)hexyl-fluorene phenylene) bromide) and oppositely charged sodium n-alkyl sulfonate surfactants of different chain lengths has been studied in DMSO-water solutions (4% v/v) by UV-visible absorption, fluorescence spectroscopy, fluorescence lifetimes, electrical conductivity, and (1)H NMR spectroscopy. Polymer-surfactant interactions lead to complex spectroscopic behaviors which depends on surfactant concentration. At low surfactant concentrations, the observed strong static fluorescence quenching of fluorescence seems to be associated with formation of aggregates between polymer chains neutralized through interaction with surfactants. This is supported by conductivity and by analysis of absorption spectra deconvoluted at each surfactant concentration using an adapted iterative method. In contrast, above the surfactant critical micelle concentration, there is a strong fluorescence enhancement, leading in some cases to higher intensities than in the absence of surfactants. This is attributed to the transformation of the initially formed aggregates into some new aggregate species involving surfactant and polymer. These changes in HTMA-PFP fluorescence as a function of n-alkyl sulfonate concentration are important for the general understanding of polymer-surfactant interactions, and the aggregates formed may be important as novel systems for applications of these conjugated polyelectrolytes.

Many real-world networks analyzed in modern network theory have a natural spatial element; e.g., the Internet, social networks, neural networks, etc. Yet, aside from a comparatively small number of somewhat specialized and domain-specific studies, the spatial element is mostly ignored and, in particular, its relation to network structure disregarded. In this paper we introduce a model framework to analyze the mediation of network structure by spatial embedding; specifically, we model connectivity as dependent on the distance between network nodes. Our spatially embedded random networks construction is not primarily intended as an accurate model of any specific class of real-world networks, but rather to gain intuition for the effects of spatial embedding on network structure; nevertheless we are able to demonstrate, in a quite general setting, some constraints of spatial embedding on connectivity such as the effects of spatial symmetry, conditions for scale free degree distributions and the existence of small-world spatial networks. We also derive some standard structural statistics for spatially embedded networks and illustrate the application of our model framework with concrete examples.

We report on the molecular interactions between room-temperature ionic liquids (RTILs) and Nafion® and PDMS membranes, proving that in contact with these polymers RTILs behave like electrolytes rather than solvents.

This paper presents analysis and follow up experiments based on previous work where a neurally controlled simulated agent was evolved to navigate using path integration (PI). Specifically, we focus on one agent, the best one produced, and investigate two interesting features. Firstly, the agent stores its current coordinates in two leaky integrators, whose leakage is partially compensated for by a normalisation mechanism. We use a comparison between four network topologies to test if this normalised leakage mechanism is adaptive for the agent. Secondly, the controller generates efficient searching behaviour in the vicinity of its final goal. We begin an analysis of the dynamical system (DS) responsible for this, starting from a simple three variable system.

Background Circulating or dietary cholesterol is not able to cross the blood-brain barrier (BBB) and cholesterol homeostasis in brain is thought to depend largely on endogenous biosynthesis. Cholesterol biosynthesis and content are reduced in the brain of several models of Huntington’s disease (HD) (Valenza et al ., 2005; 2007; 2010). This cerebral dysfunction is measurable also in HD patients starting from early disease stages (Leoni et al ., 2008; Leoni et al ., 2013). Aims In the adult brain cholesterol-dependent neuronal activities, such as neurite outgrowth and synaptic properties, mainly rely on the transport of cholesterol from astrocytes on ApoE-containing particles (Mauch et al ., 2001). Cholesterol supply to neurons might be reduced in HD astrocytes by contributing to neuronal dysfunction in HD neurons. Methods and results Here we show that primary astrocytes obtained from R6/2 HD mice and from mouse knock-in Neural Stem (NS) cell lines expressing mutant huntingtin produce and release less cholesterol bound to ApoE-containing lipoproteins into the medium, compared to control astrocytes. Accordingly, conditioned medium from wild-type astrocytes (GCMwt), but not from R6/2 astrocytes (GCMHD) or from wt astrocytes depleted of lipoproteins (GCMwt-delip), is able to compensate the defect in neurite outgrowth and to ameliorate synaptic-related properties in HD neurons. In parallel we established a dose-response relationship between cholesterol application and these parameters. Furthermore, results from gain and loss of function experiments in wt and HD primary astrocytes reinforce the notion of an altered cross-talk between astrocytes and neurons which can be rescued experimentally. Conclusions In conclusion, our results suggest that astrocytes carrying the HD mutation are the major responsible of the cholesterol dysfunction in HD as they contribute to supply less cholesterol to the surrounding neurons.

This work continues with the development of a non-dispersive UV optical sensor for stack emissions for SO2 and NO2. These gases are among the most important ones in the emissions of the petrochemical industry. The NDUV consists of three optical channels sensing different spectral regions: 300 nm for SO2, 380 nm for NO2 and 320 nm used as a common reference. Each channel has an interference filter centered at each channel's wavelength, and a photodiode with control electronics. Calibration curves and the effect of cross interference on concentration measurements of these gases are shown.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

12 Non-dispersive analyzers have been used for measurement of gases for many years and were recently introduced as on-line meters for continuous stack emission measurements in industrial plants. SO2 and NO2 are among the most important gases in the emissions of the petrochemical industry. The development of a UV-visible meter for these gases is presented. It consists of three optical channels sensing different spectral regions: 300 nm for SO2, 380 nm for NO2 and 320 nm used as a common reference. Each channel has an interference filter of 10 nm bandwidth centered at each channel's wavelength. Each filter is followed by a photodiode and its electronics which are housed in a single compartment with no moving parts. An incandescent lamp with high output in the UV region was selected and mounted on the opposite side of the stack by appropriate flanges. The equipment was designed to measure in the range between 0 and 500 ppmv with a resolution of about 2 ppmv. Performance parameters like signal stability, dark current, detection limit and calibration curves are shown.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The secretin amino terminal residues are essential for high affinity binding to the cognate receptor and for the subsequent activation of adenylate cyclase. It has been already established that two basic residues of the receptor TM 2 are involved in the interaction with aspartate 3 of the ligand. The present work investigated the hypothesis that two conserved tyrosine residues of the TM 1 (Tyrosines 124 and 128) could also participate to the positioning of the amino terminus of the ligand. Tyrosines 124 and 128 were mutated into alanine and histidine residues, and the properties of the mutant receptors, expressed in CHO cells, were compared with those of the wild-type receptor. Mutation of tyrosine 124 to Ala or His decreased the affinity of the receptor for secretin, [Glu3]secretin, [Asn3]secretin and the secretin fragment 2-27, and reduced the intrinsic activity of [Asn3]secretin. Mutation of tyrosine 128 to Ala, but not to His reduced 50-fold secretin and [Asn3]secretin affinity but only 3-fold that of [Glu3]secretin. Secretin and [Glu3]Sn were equipotent in that mutant receptor. These results suggested that tyrosine 128 of the secretin receptor interacted directly with the [Asp3] residue of secretin and thus that the amino terminal domain of secretin interacts with amino acids buried in both the TM 1 and TM 2 helices.

The effects of alprazolam (1.5 mg/die) on the levels of the monoaminergic neurotransmitter metabolites, on the activity of the hypothalamic-pituitary-adrenal axis and on clinical outcome in subjects with primary late-onset dysthymia were investigated. Drug treatment significantly decreased plasma and urinary cortisol levels, serotonin platelet-bound and urinary 3-methoxy-4-hydroxyphenylglycol concentrations, while it increased plasma homovanillic acid (HVA) concentrations. Significant relationships were observed between neurochemicals and global scores or some items of the Hamilton Depression Rating Scale, before and after treatment. Patients responded positively (73%) to the therapy; clinical outcome was significantly correlated with plasma and urinary HVA levels. Collected data seem to support the hypothesis that central monoaminergic systems are in part involved in therapeutic response to alprazolam.

A total of 1176 HLA-A,B,DR haplotypes were reconstructed by typing 303 unrelated families referred to our laboratory during the last seven years for the search of HLA identical sibs in view of bone marrow transplantation. A total of 614 different three-locus haplotypes were found. Most of them (83.6%) were present only once or twice, whereas 24/614 (3.9%) were found 6–28 times each. HLA-B44 was present in 4 of these most frequent haplotypes. HLA-B44 has been implicated as the molecular target for bone marrow allograft rejection. Therefore, a better knowledge of the HLA-B44 haplotype relationships might prove useful for the programming of registries of unrelated bone marrow donors. Eighty five serologically defined HLA-B44 unrelated subjects, either one or both parents from the above families, were subtyped by a high-resolution sequence-specific oligonucleotide probing approach. Moreover, 34 unrelated potential donors recruited for those patients that did not find a suitable donor among their siblings were subtyped also for HLA-B44. B*4403, which accounted for 47/85 (55.3%) serologically defined B44 alleles, appeared in strong, statistically significant, linkage disequilibrium with HLA-A29, -A23 and -DR7. On the other hand, B*4402, which covered virtually all other B44 alleles, showed prevalent gametic associations with HLA-A2 and HLA-A24. The linkage disequilibrium between HLA alleles is the key for the low frequency of HLA-B44 mismatches in donors selected as HLA-A,B,DRB1 identical to patients waiting for unrelated bone marrow transplantation. If a given patient presents unusual haplotypes, the chance of finding HLA-B44 mismatches may be higher because of the presence of different haplotype relationships in the donors. P. L. Mattiuz, E. Di Paolo, V Fossombroni, A. Menicucci, F. Pradella, B. Porfirio, G. Rombola. HLA-B44 subtypes and the chance of finding HLA compatible donor/recipient pairs for bone marrow transplantation: a haplotype study of 303 Italian families. Tissue Antigens 1997: 50: 602–609. Munksgaard, 1997 A total of 1176 HLA-A,B,DR haplotypes were reconstructed by typing 303 unrelated families referred to our laboratory during the last seven years for the search of HLA identical sibs in view of bone marrow transplantation. A total of 614 different three-locus haplotypes were found. Most of them (83.6%) were present only once or twice, whereas 24/614 (3.9%) were found 6–28 times each. HLA-B44 was present in 4 of these most frequent haplotypes. HLA-B44 has been implicated as the molecular target for bone marrow allograft rejection. Therefore, a better knowledge of the HLA-B44 haplotype relationships might prove useful for the programming of registries of unrelated bone marrow donors. Eighty five serologically defined HLA-B44 unrelated subjects, either one or both parents from the above families, were subtyped by a high-resolution sequence-specific oligonucleotide probing approach. Moreover, 34 unrelated potential donors recruited for those patients that did not find a suitable donor among their siblings were subtyped also for HLA-B44. B*4403, which accounted for 47/85 (55.3%) serologically defined B44 alleles, appeared in strong, statistically significant, linkage disequilibrium with HLA-A29, -A23 and -DR7. On the other hand, B*4402, which covered virtually all other B44 alleles, showed prevalent gametic associations with HLA-A2 and HLA-A24. The linkage disequilibrium between HLA alleles is the key for the low frequency of HLA-B44 mismatches in donors selected as HLA-A,B,DRB1 identical to patients waiting for unrelated bone marrow transplantation. If a given patient presents unusual haplotypes, the chance of finding HLA-B44 mismatches may be higher because of the presence of different haplotype relationships in the donors.

OBJECTIVE: Indexes of myocardial ischemia and vasoconstrictive hormonal release were evaluated in order to investigate the difference between essential hypertension and hypertension during chronic renal failure. BACKGROUND: Arterial hypertension induces several cardiovascular alterations that reflect themselves either on the heart and/or on the coronary blood flow enhancing the cardiovascular risk. Since chronic renal failure can influence the neuroendocrine response, various mechanisms involved in hypertension during chronic renal failure are still unclear. High endothelin 1 (ET-1) levels have been found both in arterial hypertension and during chronic renal failure. Interestingly, either ET-1 or catecholamines seem also to be implied in the pathogenesis of myocardial ischemia. METHODS: 20 hypertensive uremic and 20 essentially hypertensive patients underwent echocardiographic wall motion and wall thickening analysis performed at baseline and immediately after the end of exercise. Simultaneously, myocardial perfusion was evaluated by 99mTc-MIBI-SPECT. In addition, plasma norepinephrine and ET-1 concentrations were measured at baseline and at peak exercise. RESULTS: The segmental radionuclide analysis showed a greater ischemic degree in hypertensive uremic patients. Yet, we were able to identify one or more regions of the left ventricle in which both systolic thickening measurements and wall motion after exercise were impaired. After exercise, wall thickening impairment was correlated with both wall motion abnormalities (r = 0.72, p < 0.01) and MIBI ischemic grade (r = 0.82, p < 0.001). Basal and after-exercise plasmatic norepinephrine and endothelin levels were higher in hypertensive uremic than in essentially hypertensive patients. Moreover, there was a significant correlation between increments in norepinephrine concentration and MIBI perfusion defects, and between the increment in ET-1 concentration and both MIBI perfusion defects, or kinetic alterations assessed by wall motion as well as by wall thickening. CONCLUSIONS: This is the first cross-sectional study in which a higher degree of myocardial ischemia has been observed in hypertensive uremic patients combined with an enhanced plasma release of both norepinephrine and ET-1. This phenomenon may contribute to enhance the cardiovascular risk of these patients.