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In the Klamath-Siskiyou region of northern California and southwest Oregon, the mixed-severity fire regime and short fire return interval has created diverse vegetative landscape with frequent regenerating patches of forest vegetation. Considerable evidence from this region suggests that intense competition from neighborhood vegetation can greatly reduce the survival and growth of young conifers following severe site disturbance, including fire. However, relatively little information exists regarding the growing conditions one to three decades following disturbance, particularly in unmanaged stands. We measured the effects of neighbor-hood vegetation on regenerating Douglas-fir (Pseudotsuga menziesii) growth in northern California, 10-20 years following severe wildfires. Steep climatic gradients owing to complex topography in the region can cause significant variation in local temperatures, levels of precipitation, and solar radiation; thus our measurements were dispersed across two abiotic envir...

We conducted a study that evaluated the likelihood of capturing food web relationships with stable isotopes using two dominant producers, red alder and Douglas-fir, in the Oregon Coast Range. Foliage from 10 riparian forests dominated by either red alder or Douglas-fir was analyzed for δ15N and δ13C to determine the isotopic variability within a forest stand and across stands. We then conducted a sensitivity analysis using the IsoError model (Phillips and Gregg 2001) to determine whether δ15N and δ13C could successfully discriminate between red alder and Douglas-fir in a food web study. We found greater δ15N variation within and across sites for Douglas-fir (within stand: ≤2.58‰, average across stands: 1.72‰) compared to red alder (within stand: 0.59‰, average across stands: 0.27‰). δ13C variation was similar for both species within and among forest stands. On average, δ15N and δ13C of red alder and Douglas-fir differed by

Fire in riparian areas has the potential to influence the functions riparian vegetation provides to streams and aquatic biota. However, there is little information on the effects of fire on riparian areas. The objectives of the present study were to: (i) determine how fire severity interacts with riparian topographic setting, micro-environmental conditions, and pre-fire community composition to control post-fire regeneration; (ii) determine how riparian regeneration patterns and controls change during early succession; and (iii) determine how critical riparian functions are influenced by and recover after fire. Study locations included the Biscuit Fire in southwestern Oregon and the B&B Complex Fire in the Cascade Mountain Range of west-central Oregon, USA. We measured post-fire woody species regeneration, and measured factors such as fire severity, pre-fire species composition, and stream size as potential factors associated with post-fire regeneration patterns. At a relatively coarse spatial scale, patterns in post-fire colonization were influenced by elevation. At finer spatial scales, both conifer- and hardwood-dominated riparian plant communities were self-replacing, suggesting that each community type tends to occur in specific ecological settings. Abundant post-fire regeneration in riparian areas and the self-replacement of hardwood- and conifer-dominated communities indicate high resilience of these disturbance-adapted plant communities.

Height growth equations for dominant trees are needed for growth and yield projections, to determine appropriate silvicultural regimes, and to estimate site index. Red alder [Alnus rubra Bong.] is a fast-growing hardwood species that is widely planted in the Pacific Northwest, USA. However, red alder dominant height growth equations used currently have been determined using stem analysis trees from natural stands rather than repeated measurements of stand-level top height from plantations, which may cause them to be biased. A regional dataset of red alder plantations was complied and used to construct a dynamic base-age invariant top height growth equation. Ten anamorphic and polymorphic Generalized Algebraic Difference Approach (GADA) forms were fit using the forward difference approach. The Chapman–Richards anamorphic and Schumacher anamorphic model forms were the only ones with statistically significant parameters that yielded biologically reasonable predictions across a full range of the available data. The Schumacher model form performed better on three independent datasets and, therefore, was selected as the final model. The resulting top height growth equations differed appreciably from tree-level dominant height growth equations developed using data from natural stands, particularly at the younger ages and on lower site indices. Both the rate and shape parameters of the Schumacher function were not influenced by initial planting density. However, this analysis indicates that the asymptote, which is related to site index, may be reduced for plantations with initial planting density below 500 trees ha−1. The final equation can be used for predictions of top height (and thus) site index for red alder plantations across a range of different growing conditions.

We have recently identified a new class of compounds that selectively kill cells that express P-glycoprotein (P-gp, MDR1), the ATPase efflux pump that confers multidrug resistance on cancer cells. Several isatin-beta-thiosemicarbazones from our initial study have been validated and a range of analogues synthesized and tested. A number demonstrated improved MDR1-selective activity over the lead, NSC73306 (1). Pharmacophores for cytotoxicity and MDR1 selectivity were generated to delineate the structural features required for activity. The MDR1-selective pharmacophore highlights the importance of aromatic/hydrophobic features at the N4 position of the thiosemicarbazone and the reliance on the isatin moiety as key bioisosteric contributors. Additionally, a quantitative structure-activity relationship (QSAR) model that yielded a cross-validated correlation coefficient of 0.85 effectively predicts the cytotoxicity of untested thiosemicarbazones. Together, the models serve as effective approaches for predicting structures with MDR1-selective activity and aid in directing the search for the mechanism of action of 1.

We sought to understand how vegetation indicators and local topographic factors interact to influence riparian fire severity in two recent fires in Oregon, USA. A stratified random sampling design was used to select points in a range of fire severity classes, forest stand ages, and stream sizes in each fire. At each point, plots were sampled in riparian areas and adjacent uplands. Fire severity was assessed in each plot, and measurements were made of factors that have been found to influence riparian fire severity. Understory fire severity (percent exposed mineral soil and bole char height) was significantly lower in riparian areas compared with adjacent uplands in both fires, suggesting a decoupling in understory fire effects in riparian areas versus uplands. However, overstory fire severity (percent crown scorch and percent basal area mortality) was similar in riparian areas and adjacent uplands in both fires. Fire severity in riparian areas was most strongly associated with upland fire severity. In addition, vegetation indicators, particularly those describing riparian fine fuel component and species composition, were strong predictors of riparian fire severity. Consistency in factors controlling fire severity in the two fires suggests that controls on riparian fire severity may be similar in other regions.

Peroxisome proliferator-activated receptor-gamma (PPAR-gamma) plays an essential role in lipid and glucose homeostasis. It is recognized as the receptor of the thiazolidinediones-a synthetic class of anti-diabetic drugs-and is the target of many drug discovery efforts because of its role in disease states, such as type II diabetes mellitus. In this study, structure-based virtual screening of the PPAR-gamma ligand binding domain against a natural product library has revealed 29 potential agonists. In vitro testing of this list identified six flavonoids to have stimulated PPAR-gamma transcriptional activity in a transcriptional factor assay. Of these, flavonoid-psi-baptigenin-was classed as the most potent PPAR-gamma agonist, possessing low micromolar affinity (EC(50) = 2.9 microM). Further in vitro testing using quantitative RT-PCR and immunoblotting experiments demonstrated that psi-baptigenin activated PPAR-gamma mRNA (4.1 +/- 0.2-fold) and protein levels (2.9 +/- 0.4-fold) in THP-1 macrophages. Moreover, psi-baptigenin's-induced PPAR-gamma enhancement was abolished in the presence of a selective PPAR-gamma antagonist, GW9662. Induced-fit docking investigations provide a detailed understanding on the ligands' mechanism of action, suggesting five of the active flavonoids induce significant conformational change in the receptor upon binding. Overall, these results offer insight into various naturally derived flavonoids as leads/templates for development of novel PPAR-gamma ligands.

Riparian forests are known to be floristically diverse and influenced by multiscale phenomena, yet few studies have explicitly compared how these factors contribute to various aspects of riparian plant diversity. We analyzed woody riparian plant species and environmental data from four western Oregon watersheds distributed across a wide climate- driven productivity gradient at three scales (40-m 2 sample plots (alpha diversity), 1-ha plots, and species pools from 16 1-ha plots in each watershed) to compare three hypotheses of control on species diversity: (1) local control, (2) direct climatic control, and (3) indirect climatic control. We used a process model (3-PG) to model gross primary productivity (GPP) as a functional climate index across our study area. We performed multiple linear regression to determine the best predictors of alpha (sample-plot scale) diversity, compositional change within riparian forests (beta diversity), and hectare-scale diversity and used path analysis to explore hypothesized causal linkages between climate and other factors and species diversity. We also analyzed a companion data set of gap and forest environments from a subset of the same sites to determine the influence of disturbance on species diversity across the gradient. We found evidence for strong spatial patterning in woody plant richness consistent with indirect climatic control on woody plant richness. Climate (GPP) showed negative relationships with alpha diversity and hectare richness of trees, shrubs, and woody plant species and was the most commonly selected explanatory variable in regression analyses. GPP and Rubus spectabilis cover increased from the least to most productive climates while understory light and moisture heterogeneity across the riparian area decreased. These environmental changes coincided with declines in alpha, beta, and hectare-scale diversity. Disturbance gaps yielded higher richness at most sites, but differences in species richness between gap and forest sample plots did not increase at high levels of GPP, as hypothesized. This study points toward an integrated conceptual model whereby regional and landscape scale controls such as climate and watershed position complement and interact with local controls (i.e., vegetation structure, environmental gradients) to jointly govern woody plant diversity in riparian forests.

Ataper equation and a volume table are presented for red alder (Alnus rubra Bong.) trees grown in plantations. Fourteen diameter measurements from each of 234 trees were collected from nine plantations throughout the Pacific Northwest. Diameter inside bark (dib) along the stemwas fitted to a variable exponent model form. Individual tree merchantable volume was then estimated as volume inside bark by integrating the taper function from 6 in. (stump height) to the height at a 5-in. (diameter outside bark) top. Incorporating two easily measured tree variables—dbhand total tree height—provided an accurate fit. Model results and the use of an independent evaluation data set of plantation-grown trees indicated that the model presented here was a better predictor of dib in managed stands than previously published red alder taper equations. Thisequation provides reliable dib and merchantable volume predictions and is an improvement over previous red alder volume and taper equations.

The three peroxisome proliferator-activated receptor (PPAR) isoforms; PPARα, PPARγ and PPARδ, play central roles in lipid metabolism and glucose homeostasis. Dual PPARα/γ agonists, which stimulate both PPARα and PPARγ isoforms to similar extents, are gaining popularity as it is believed that they are able to ameliorate the unwanted side effects of selective PPARα and PPARγ agonists; and may also be used to treat dyslipidemia and type 2 diabetes mellitus simultaneously. In this study, virtual screening of natural product libraries, using both structure-based and ligand-based drug discovery approaches, identified ten potential dual PPARα/γ agonist lead compounds (9-13 and 16-20). In vitro assays confirmed these compounds to show no statistically significant toxicity to cells, with the exception of compound 12 which inhibited cell growth to 74.5%±3.5 and 54.1%±3.7 at 50μM and 100μM, respectively. In support of their potential as dual PPARα/γ agonists, all ten compounds upregulated the expression of cholesterol transporters ABCA1 and ABCG1 in THP-1 macrophages, with indoline derivative 16 producing the greatest elevation (2.3-fold; 3.3-fold, respectively). Furthermore, comparable to the activity of established PPARα and PPARγ agonists, compound 16 stimulated triacylglycerol accumulation during 3T3-L1 adipocyte differentiation as well as fatty acid β-oxidation in HuH7 hepatocytes.

The charge density distribution in 2,2'-Dihydroxy-1,1'-naphthalazine (Pigment Yellow 101; P.Y.101) has been determined using high-resolution X-ray diffraction and multipole refinement, along with density functional theory calculations. Topological analysis of the resulting densities highlights the localisation of single/double bonds in the central C=N-N=C moiety of the molecule in its ground state. The density in the N—N is examined in detail, where we show that very small differences between experiment and theory are amplified by use of the Laplacian of the density. Quantification of hydrogen bonds highlights the importance of the intramolecular N—H…O interaction, known to be vital for retention of fluorescence in the solid state, relative to the many but weak intermolecular contacts located. However, a popular method for deriving H-bond strengths from density data appears to struggle with the intramolecular N—H…O interaction. We also show that theoretical estimation of anisotropic displacements for hydrogen atoms brings little benefit overall, and degrades agreement with experiment for one intra-molecular contact. NH&MRC

The complex [(η5-Me3SiC5H4)Fe(10aneP3-H2,C2H3)]+, where Me3SiC5H4 is trimethylsilylcyclopentadienyl and 10-aneP3-H2,C2H3 is 1-vinyl-1,4,8-triphosphacyclodecane, has been prepared by the base-catalyzed template cyclization of 1,3-bis(phosphino)propane (1,3-bpp) and trivinylphosphine (tvp) at the metal center. A related radical-initiated iron-template reaction between 1,2-bis(phosphino)ethane (1,2-bpe) and triallylphosphine (tap) gave [(η5-C5Me5)Fe(Me-10aneP3-H2,C3H5)]+, where C5Me5 is 1,2,3,4,5-pentamethylcyclopentadienyl and Me-10aneP3-H2,C3H5 is the unsymmetric 10-aneP3 derivative 1-allyl-3-methyl-1,4,7-triphosphacyclodecane. This macrocycle is the result of two intramolecular hydrophosphination reactions, one that generates a five-membered (chelate) ring with an exo-methyl group and one a six-membered chelate. The [(η5-CpR)Fe]+ fragment also controls the cyclization of 1,2-bis(diallylphosphino)ethane with phenylphosphine to give a ternary complex containing the symmetrical 11-membered macrocycle 1-phenyl-4,8-diallyl-1,4,8-triphosphacycloundecane, in addition to the unsymmetrical 10-aneP3 derivative.

We studied riparian forests along mountain streams in four large watersheds of western Oregon and far northern California, USA, to better understand the multiscale controls on woody riparian vegetation in a geographically complex region. In each of the four-study watersheds, we sampled woody riparian vegetation in161-ha sampling reaches that straddled the stream channel. Within each hectare, we sampled riparian vegetation and local environmental factors in 40 m2 sampling plots arrayed along topographic transects. We also surveyed natural disturbance gaps in 6 ha in each watershed to explore the effects of fine scale disturbance on species distributions. We compared species composition across our study watersheds and used Nonmetric Multidimensional Scaling (NMS) and chi-squared analyses to compare the relative importance of landscape scale climate variables and local topographic and disturbance variables in explaining species distributions at sampling plot and hectare scales. We noted substantial turnover in the riparian flora across the region, with greatest numbers of unique species in watersheds at the ends of the regional gradient. In NMS ordinations at both scales, variation in woody riparian species composition showed strongest correlations with climatic variables and Rubus spectabilis cover, but the latter was only an important factor in the two northern watersheds. At the smaller scale, topographic variables were also important. Chi-squared analyses confirmed that more species showed landscape scale habitat preferences (watershed associations) than associations with topographic position (94.7% vs. 42.7% of species tested) or gap versus forest setting (94.7% vs. 24.6% of species tested). The woody riparian flora of western Oregon shows important biogeographic variation; species distributions showed strong associations with climatic variables, which were the primary correlates of compositional change between riparian sites at both scales analyzed. Additional local variation in composition was explained by measures of topography and disturbance.

Core peptide (CP) is a unique peptide derived from the transmembrane sequence of T cell antigen receptor (TCR)-alpha chain that is capable of inhibiting the immune response both in vitro and in animal models of T cell mediated inflammation. CP contains two basic amino acids (lysine and arginine) in its sequence. The presence of these charged residues interspersed between hydrophobic amino acids is important for function. Here in an attempt to understand CP’s biophysical properties leading to activity we have synthesized a number of CP analogues and correlated their model structure with their biological activity. It became apparent that it is not only the charge of the amino acids but also the nature of the polar amino acids themselves and the topography and spacing between them by hydrophobic amino acids, creating a hydrophobic face, that are critical for CP function.

In the Pacific Northwest, a mixture of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) and red alder (Alnus rubra Bong.) often results when red alder regenerates naturally in planted conifer stands. The relationships among stand structure, tree mortality, tree size, and understory development in the two species mixtures were explored at two sites for the first 16 years after planting. Treatments included a range of species proportions, and red alder was either planted simultaneously with Douglas-fir or planting was delayed for 5 years. Red alder was also removed from some simultaneously planted proportions. Both replacement effects (total stand density held constant) and additive effects (stand density doubled) of the interaction were considered. Red alder grew relatively better at Cascade Head Experimental Forest in the Coast Range, while Douglas-fir grew better at H.J. Andrews Experimental Forest in the less temperate Cascade Mountains. Possible production benefits from mixed plantings were examined using two methods of calculation. Potential production benefits from certain planted proportions of the two species occurred at H.J. Andrews Experimental Forest. No planting time or species proportion resulted in yield improvements over monoculture stands at Cascade Head Experimental Forest. Understory species also varied because of differences in site and stand characteristics that resulted from the differences in planting times and species proportions.

Hartree-Fock, density functional, and MP2 methods are applied to the problem of designing neutral, bicyclic C3-symmetric cages incorporating interacting anion- and cation-binding sites which strongly bind NaCl as an ion contact pair. A large number of trial ligands L and their complexes L:NaCl are tested, with the focus on maximizing binding by (i) optimizing the cavity size and shape and (ii) varying the nature of the anion- and cation-binding functionalities. The corresponding complexes L:Cl(-) and L:Na(+) are also studied in some detail. An analysis of their structures and charge distributions helps to build a consistent picture of the requirements for a successful NaCl binding. The 'best' candidate ligand utilizes a tripodal triether-substituted amine N(CH2CH2OR-)3 to bind the sodium cation; three thiourea groups in a tripodal arrangement with a 1,3,5-trisubstituted benzyl spacer group {C6H3(CH2NHC [Formula: see text] XNH-)3 X=O,S} to bind chloride; and a -CH2CH2- spacer linking the two binding sites. A simple Quantitative Structure-Property analysis suggests that the binding cavity shape and size is near to the optimal one for this system.

Ecologists are increasingly using multivariate analytical approaches to reveal relationships between communities. These methods have promise in other fields as well. The use of multivariate methods to delineate relationships and classify an agroforestry system was tested among fruit-based agroforestry gardens in northern Thailand. Data on crop species composition, species abundance, perennial-crop age groups, and other physical and ecological factors from 82 gardens in three villages in a Highland watershed in northern Thailand were used in this study. Using Hierarchical Cluster Analysis the gardens were divided into clusters, each representing a different garden type (or fruit-based agroforestry subsystem). Non-metric multidimensional scaling (NMS) analysis was used to assist in the interpretation of classification groupings and analysis gradients. The NMS analysis shows overall crop diversity, herbaceous food crops, size and market potential of the fruit planting as important classifying factors. However, this analysis did not produce as clear distinctions as hoped among gardens in a continuum of gradually changing and overlapping characteristics.

Riparian areas of large streams provide important habitat to many species and control many instream processes - but is the same true for the margins of small streams? This review considers riparian areas alongside small streams in forested, mountainous areas of the Pacific Northwest and asks if there are fundamental ecological differences from larger streams and from other regions and if there are consequences for management from any differences. In the moist forests along many small streams of the Pacific Northwest, the contrast between the streamside and upslope forest is not as strong as that found in drier regions. Small streams typically lack floodplains, and the riparian area is often constrained by the hillslope. Nevertheless, riparian-associated organisms, some unique to headwater areas, are found along small streams. Disturbance of hillslopes and stream channels and microclimatic effects of streams on the riparian area provide great heterogeneity in processes and diversity of habitats. The tight coupling of the terrestrial riparian area with the aquatic system results from the closed canopy and high edge-to-area ratio for small streams. Riparian areas of the temperate, conifer dominated forests of the Pacific Northwest provide a unique environment. Forest management guidelines for small streams vary widely, and there has been little evaluation of the local or downstream consequences of forest practices along small streams.

Predictive models of plant diversity have typically focused on either a landscape's capacity for richness (equilibrium models), or on the processes that regulate competitive exclusion, and thus allow species to coexist (nonequilibrium models). Here, we review the concepts and purposes of a hierarchical, multiscale model of the controls of plant diversity that incorporates the equilibrium model of climatic favorability at macroscales, nonequilibrium models of competition at microscales, and a mixed model emphasizing environmental heterogeneity at mesoscales. We evaluate the conceptual model using published data from three spatially nested datasets: (1) a macroscale analysis of ecoregions in the continental and western U.S.; (2) a mesoscale study in California; and (3) a microscale study in the Siskiyou Mountains of Oregon and California. At the macroscale (areas from 3889 km2 to 638,300 km2), climate (actual evaporation) was a strong predictor of tree diversity (R2 = 0.80), as predicted by the conceptual model, but area was a better predictor for vascular plant diversity overall (R2 = 0.38), which suggests different types of plants differ in their sensitivity to climatic controls. At mesoscales (areas from 1111 km2 to 15,833 km2), climate was still an important predictor of richness (R2 = 0.52), but, as expected, topographic heterogeneity explained an important share of the variance (R2 = 0.19) showed positive correlations with diversity of trees, shrubs, and annual and perennial herbs, and was the primary predictor of shrub and annual plant species richness. At microscales (0.1 ha plots), spatial patterns of diversity showed a clear unimodal pattern along a climate-driven productivity gradient and a negative relationship with soil fertility. The strong decline in understory and total diversity at the most productive sites suggests that competitive controls, as predicted, can override climatic controls at this scale. We conclude that this hierarchical, multiscale model provides a sound basis to understand and analyze plant species diversity. Specifically, future research should employ the principles in this paper to explore climatic controls on species richness of different life forms, better quantify environmental heterogeneity in landscapes, and analyze how these large-scale factors interact with local nonequilibrium dynamics to maintain plant diversity.

The reactions of the N-heterocyclic carbene (NHC) stabilised group 13 trihydride complexes [AlH3(IMeMe)] (1) (IMeMe = 1,3,4,5-tetramethylimidazol-2-ylidene), [AlH3(IiPrMe)] (2) (IiPrMe = 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene) with three molar equivalents of phenol, and [InH3(IMes)] (3) (IMes = 1,3-bis(2,4,6-trimethylphenyl)imidazole-2-ylidene) with one molar equivalent of 1,1,1,5,5,5-hexafluoropentan-2,4-dione (F6acacH) are presented. These render the imidazolium tetraphenoxyaluminate species; [IMeMe · H][Al(OPh)4] (4) and [IiPrMe · H][Al(OPh)4] (5), and 1,3-bis(2,4,6-trimethylphenyl)imidazolium 1,1,1,5,5,5-hexafluoropentan-2,4-dionate; [IMes · H][CH{C(O)CF3}2] (6), the latter leading to metallohydride decomposition. The molecular structures of 4 and 6 are described.

Accurate structure factors have been measured for the two known conformational polymorphs (A and B) of famotidine up to a maximum resolution of sin(θ)/λ = 1.2 Å−1 at 100 K using a conventional X-ray source and a CCD-based diffractometer. The experimental electron-density distribution was modelled using a multipole model and the interatomic interactions were analysed following the atoms-in-molecules theory. Excellent equivalence between most electronic and electrostatic properties in the polymorphs exists and no significant differences were found to exist across polymorphs either in the interatomic interactions (via the topological analysis) or in the atomic charges from integration of the atomic basins. Additional derived properties, such as the molecular dipole moment, similarly did not distinguish between the polymorphs. Only the molecular electrostatic potential mapped on top of the molecular surface, i.e. the isodensity contoured at 0.00675 e Å−3, was able to uncover the differences between A and B. In both conformations, the sizes of the electronegative and electropositive areas match. However, the average electrostatic potential in the electronegative area of A is −40 kJ mol−1, while the corresponding value in B is −55 kJ mol−1. Together with the physical shape and dimensions of A and B, this leads to a conclusion that the polymorphs are mutually exclusive at the same receptor binding site.

Intramolecular non-covalent interactions involving aromatic residues in the ternary species Λ-β 1 -[Co( R , R -picchxn)( S -aa)] 2+ (aa=Tyr, O Me-tyr or Phe) have been investigated. Such interactions are important to discriminatory processes associated with molecular recognition in chemical and biochemical systems. The single-crystal X-ray study of Λ-β 1 -[Co( R , R -picchxn)( S -tyr)]Br 2 · 3.5H 2 O demonstrates the influence of intramolecular π–π and bifurcated NH–π interactions in determining the molecular conformation of the complex cation in the solid state. The Co(III) complexes synthesised are diamagnetic, and have been fully assigned in solution using multidimensional NMR techniques. Remarkably, the solid state conformation observed for Λ-β 1 -[Co( R , R -picchxn)( S -tyr)] 2+ has been shown to predominate in solutions of all the complexes, as evidenced by appropriate rOe correlations. 1 H NMR measurements carried out in order to determine equilibrium rotamer distributions confirm the dominance of this conformer in solution. NMR measurements also show that rotamer populations are relatively unchanged at elevated temperatures and in a variety of solvents. The results of this detailed study, which demonstrate the significance of non-covalent interactions involving aromatic residues to the determination of the molecular conformation, serve to highlight the suitability of these simple ternary Co(III) complexes to act as models for such interactions.

Single-crystal X-ray structures and high-resolution solution NMR studies of Λ-β 1 -[Co( R , R -picchxn)( R -phe)](ClO 4 ) 2 · H 2 O and Λ-β 1 -[Co( R , R -picchxn)( R -tyr)](ClO 4 ) 2 · 2H 2 O (pheH=phenylalanine, tyrH=tyrosine) are reported. In the former, the aromatic side group of the phenylalanine ligand is extended, as is found in related halide salts. In the tyrosine analogue, the aromatic ring adopts a conformation such that a weak intramolecular NH–π interaction with a NH group of the tetradentate ligand is stabilized. The interaction is rather weak and is not particularly favoured in solution, as revealed by 1 H NMR. The β 1 complex of phenylalanine is not the thermodynamically stable diastereoisomer. Equilibration experiments give a mixture of Λ-β 1 , Λ-β 2 and Δ-α diastereoisomers in D 2 O solution, the α diastereoisomer being more stable than either of the β complexes by about 1 kJ mol −1 at 298.2 K. Intramolecular π–π and NH–π interactions are responsible for the stabilization of the α complex, demonstrating the significance of the cooperative effects of such interactions. The ternary cobalt complexes described in this study could act as simple model systems for investigating the discriminatory effects of analogous weak interactions that occur in a complex biological setting.

The synthesis and characterization of a series of ternary Co(III) complexes which could act as simple model systems for the study of non-covalent interactions involving aromatic residues is reported. Such interactions are important to the discriminatory processes associated with molecular recognition in chemical and biochemical systems, but are relatively poorly understood due to the inherent complexity of the majority of systems. The species reported in this paper are Λ-β1-[Co(R,R-picchxn)(S-trp)]2+ (picchxn=N,N′-di(2-picolyl)-1,2-diaminocyclohexane; trp=the anion of tryptophan) and Δ-α-, Λ-β1- and Λ-β2-[Co(R,R-picchxn)(R-trp)]2+. A single-crystal X-ray study of the Δ-α- and Λ-β2-R-trp complexes has demonstrated that the molecular cation of each adopts a conformation where intramolecular π–π interactions involving the indole group and a pyridyl ring occur in the solid state. 2D-ROESY and 1H NMR experiments of these diamagnetic complexes have established that these interactions persist in solution, as is also the case with the Λ-β1-S-trp cation. Except for the Λ-β2-R-trp species, all possess various combinations of NH–π interactions as well, and these too serve to influence markedly the rotamer distributions in several instances. Equilibrium rotamer populations determined using NMR have enabled the energetics of the system to be evaluated. NMR measurements also show that the rotamer populations are relatively unchanged at elevated temperatures, and that the non-covalent interactions which dictate both the solid state and solution configurations of these complexes persist in a variety of solvents. It is shown for R-trp that combined NH–π and π–π interactions provide the driving force for octahedral inversion of both Λ-β1 and Λ-β2 diastereoisomers to the Δ-α form. The unprecedented stabilization of this species is rationalized in terms of a hierarchy of competing non-covalent aromatic interactions.

E-4-Amino-2-methylbut-2-enoic acid, (±)-4-amino-2-methylbutanoic acid, (+)-(S)- and (−)-(R)-4-amino-2-methylbutanoic acid, which are analogues of the inhibitory neurotransmitter GABA (γ-aminobutyric acid, 4-aminobutanoic acid), were synthesised from ethyl 2-methyl-4-phthalimidobut-2-enoate, ethyl 2-methyl-4-phthalimidobutanoate, (+)-[(2R-(3,3-dimethylbutyro-1,4-lactonyl)]-(2S)-methyl-4-phthalimidobutanoate and (−)-[(2R-(3,3-dimethylbutyro-1,4-lactonyl)]-(2R)-methyl-4-phthalimidobutanoate, respectively. The assignment of the absolute configuration of (+)-(S)- and (−)-(R)-4-amino-2-methylbutanoic acid was based on the X-ray crystallographic structure of the (+)-(R,S)-diastereoisomer, and direct comparison of specific rotations with the published data for (−)-(R)-4-amino-2-methylbutanoic acid.

The experimental electron density distributions (EDD) in tetrafluorophthalonitrile and tetrafluoroisophthalonitrile have been determined from a multipole refinement with use of accurate X-ray diffraction data collected at 100 K. As hydrogen atoms pose a serious challenge to a successful X-ray based EDD determination due to their diminishing diffraction power, the absence of any such atoms in the studied complexes is an important advantage. The experimental EDD is compared with theoretical densities resulting from high-level ab initio and DFT calculations using the atoms in molecules theory. Topological analysis of the electron density was used to compare the two different isomers and to estimate the similarity of identical functional groups in different crystalline environments. Comparison with theoretical results reveals subtle differences in C−F bonds. The experimental molecular electrostatic potential satisfactorily explains the observed differences in the patterns of weak intermolecular interactions.

The experimental charge density distribution in crystalline 9-ethynyl-9-fluorenol has been determined in a refinement of a pseudo-atomic multipolar expansion (Hansen−Coppens formalism) against extensive low-temperature (T = 100 K) single-crystal X-ray diffraction data and compared with a selection of theoretical DFT calculations on the same complex. The molecule crystallizes in the centrosymmetric space group C2/c with two independent molecules in the asymmetric unit. A range of multipole models of varying complexity were tested and found to describe the observed intensities almost equally well in terms of the usual residual values presented; however, the resulting total density distributions and derived properties, such as atomic charges and molecular electrostatic potentials, showed significant differences and it is emphasized that care has to be taken when parameters used for the refinements are selected. In addition to the two medium-strength OH---O hydrogen bonds, which are found to differ between mo...

Hybrid poplar (Populus spp.) is the newest tree crop in the Pacific Northwest. We have been studying its management and growth in the Willamette Valley of western Oregon on poorly drained soils with no irrigation. We found very good growth rates—up to 4000 ft3/ac in 6 yr—on soils considered poor for many kinds of agriculture. For plantation establishment, we found that after 1 yr, simple no-till methods were as effective as the often-used ripping and tilling approaches. An herbicide screening study resulted in good poplar growth with some herbicides and reduced growth with two others commonly used in site preparation. Our investigation of root development indicates that the good growth on these poorly drained, nonirrigated soils is associated with poplar's deep and extensive root development. West. J. Appl. For. 18(4):281–285.

A new approach to the rational design of Lewis acids based on face-face π-π interactions is described. The synthesis of two novel diols (-)(1R,3R)-2,2-dimethyl-1,2,3,4-tetrahydronaphthalene-1,3-diol (I) and (-)(1S,3R)-trans-2,2-dimethyl-1,2,3,4-tetrahydronaphthalene-1-3-diol (II) is reported in six and five steps resp. starting from α-tetralone. Complexation of (-)(1R,3R)-2,2-dimethyl-1,2,3,4-tetrahydronaphthalene-1,3-diol to phenylboronic acid shows the interplanar distance between the boron atom and the arom. ring to be 3.05 A, which is ideal for the proposed interactions. [on SciFinder(R)]

The total experimental charge density in 1-(2-hydroxy-5-nitrophenyl)ethanone (1) has been determined using high-resolution X-ray diffraction data in combination with neutron diffraction data measured at 100 K. Multipole refinement was carried out in terms of the rigid pseudoatom model. Multipole refinement converged at R = 0.026 for 5415 reflections with I > 2σ(I). Topological analysis of the total experimental charge density ρ(r) and its Laplacian, −∇2ρ(r) together with a comparison against high level theoretical gas-phase calculations reveals fine details of intra- and intermolecular bonding features, in particular the extent of the π-delocalisation throughout the molecule.

Single-crystal X-ray structures of Λ-β 1-[Co(R,R-picchxn)(R-phe)]Br2, Λ-β 1-[Co(R,R-picchxn)(R-phe)]Br2·3H2O and Λ-β 1-[Co(R,R-picchxn)(R-phe)]I2 are reported. In each structure there are three formula units in the asymmetric unit. Considerable disorder attends the anions and water molecules of crystallisation. In every case the conformer adopted by the coordinated aminoacidate is such that the phenylalaninato side chain is extended in order to minimize non-bonded steric interactions with the Co(tetradentate)fragment. Such an arrangement is in accord with the fact that this kind of diastereoisomer does not participate in any strong intramolecular π-π or NH-π interaction.

The syntheses and structural characterisations of a number of 2-arsa- and 2-stiba-1,3-dionato complexes of main group elements are reported. The synthetic methods that were employed in this study include the reaction of lithium heterodionate complexes, [Li{η2-O,O–OC(R)EC(R)O}], E=As or Sb, R=alkyl or aryl, with main group metal halides or the reactions of arsa- and stiba-enols, OC(R)EC(R)OH, with either main group alkyl or amide complexes. The hetero-ligands in the prepared complexes have been shown by X-ray crystallographic studies to coordinate the main group metal centre in several modes, that is, in a delocalised form (η2-O,O coordination) as in [{M[η2-O,O–OC(R)EC(R)O](L)}2], M=Li or Na, E=As or Sb, R=Ad (adamantyl) or Ph, L=Et2O or DME; [Na{η2-O,O–OC(Mes*)EC(Mes*)O}(DME)2], E=As or Sb, Mes*=C6H2But3-2,4,6, and [Mg{η2-O,O–OC(Ph)AsC(Ph)O}2(DME)]; in a localised diacylpnictido form (η1-E coordination) as in P[As{C(O)R}2]3, R=But or Ph; or as a combination of the two modes (η1-E–: η2-O,O–) as in [LiCl(Et2O)(DME){η2-O,O–Cl3InAs[C(O)R]2}].

The single-crystal X-ray structure of a sulphate-bearing buttgenbachite, Cu36Cl7.8(NO3)1.3(SO4)0.35(OH)62.2.5.2H2O, from Likasi, Democratic Republic of Congo, has been determined at 100 and 288 K. The basic framework of the structure is the same as has been previously reported for buttgenbachite, except for the identification of a hydrogen-bonded chloride ion (occupancy 0.6) at the origin instead of a Cu ion with partial occupancy. The nature of nitrate positional disorder along channels in the c direction and how this relates to the presence of other species such as chloride ions and water molecules and, most importantly, sulphate ions has been elucidated. One nitrate ion, with an occupancy of 0.18, lies at 2/3,l/3,l/4 and shares the site with a chloride ion (occupancy 0.30) and also a sulphate ion (occupancy 0.09); a second nitrate, with an occupancy of 0.24, lies at 2/3,1/3,0.084 and shares the site with a water molecule (occupancy 0.06). As a result, a formula of Cu36Cl7.8(NO3)1.3(SO4)0.35(OH)62.2.5.2H2O is obtained. Re-refinement of deposited data for a supposed connellite crystal from the Toughnut mine,Tombstone, Arizona gives a related, but different, pattern of anion substitution. No sulphate could be detected in the structure and it is evident that this structure refers to buttgenbachite. A nitrate nitrogen atom and a chloride ion are disordered at 2/3,l/3,l/4, the overall site being fully occupied. A chloride ion with ∼0.5 occupancy is sited at the origin and the formula Cu36Cl7.9(NO3)1.1(OH)63.4H2O is indicated. Re-refinement of a deposited data set for another buttgenbachite crystal from the Likasi mine reveals a partially occupied nitrate centred at 2/3,l/3, z and a partially occupied chloride at 2/3,l/3,l/4. Either 0.5Cl–, OH–, H2O or H3O+ is located at the origin. If the latter is the case, the stoichiometry for this buttgenbachite is Cu36Cl6.5(NO3)1.5(OH)64.5.5H2O. The present study has highlighted the fact that a range of compositions for buttgenbachite exists, depending on the pH and relative activities of chloride, nitrate and sulphate ions in solutions from which the mineral crystallizes.

N-Metallated azomethine ylides were generated by the reaction of arylidene glycine imines with AgOAc and triethylamine. These azomethine ylides undergo cycloaddition to chiral acrylamides with excellent diastereoselectivity. The configuration of two of the cycloadducts was confirmed by X-ray crystallography.

We investigated three Douglas fir–red alder stands in Oregon, USA, and five Norway spruce–European beech stands in Bavaria, Germany, to test the hypothesis that admixtures of broadleaved trees improve nutritional status of conifers. At each site needle samples from 20 to 30 conifer trees with varying proportions of broadleaves adjacent to the sample trees were taken and analysed for needle mass and the macronutrients N, P, K, Ca and Mg. The neighbourhood of each tree was described by the proportion of deciduous basal area within an 8 m circle. Ordination methods (principal component analysis; redundancy analysis) were used to test the dependency of the multivariate nutritional pattern in conifers on deciduous neighbours and rank correlation and regression were used to analyse bivariate relationships between tree species composition and descriptors of needle status. The statistical analyses yielded no evidence that deciduous admixtures improve foliar nutrition of conifers. Alongside with other empirical studies this shows that beneficial effects of broadleave admixtures on conifer nutrition are less common than postulated. Future research investigating the whole causal path relevant for tree nutrition and growth is necessary to improve our knowledge in the complex field of nutrition of mixed species forests.

The experimental charge density distribution of 5,6,7-trihydroxyflavone (1), has been determined from high-resolution X-ray diffraction data collected at 100 K. Additionally, high level single-point gas-phase calculations as well as periodic calculations have been carried out for (1). To our surprise, the topological analysis of the experimental electron density revealed a cage critical point in the geometric center of the tri-hydroxy substituted aromatic ring. This feature was independently confirmed by analysis of another study of 1. However, both high-level gas-phase and periodic ab initio calculations failed to reproduce this feature. The degree of bias on the electron density by using the Hansen–Coppens multipole model was tested by a multipole refinement of generated theoretical structure factors. This clearly showed that the cage critical point is not an artefact resulting from the use of the multipole model. Compound 1 contains a large number of weak, intermolecular hydrogen bonds and these are analysed using the Atoms in Molecules (AIM) approach, which leads to quantitative measures for hydrogen bond strength. The experimentally derived lattice energy of −467 kJ mol−1 shows a rather strongly held crystal lattice.

The assembly of [Cd(L1)]— {[L1]3— = N[CH2CH2N=C(CH3)COO—]3} into the tetranuclear cluster {[Cd(L1)]Na(H2O)2}2 in the presence of Na+ is mediated by Na+-carboxylate interactions; in contrast In3+ and Fe3+ induce the partial hydrolysis of [L1]3— to afford the complexes [In(L2)Cl] and {[Fe(L2)]2O} {[L2]2— = N[CH2CH2NH2][CH2CH2N=C(CH3)COO—]2} which aggregate via intermolecular H-bonding. Der Effekt partieller Hydrolyse beim Wechsel der Art der intermolekularen Bindung zwischen Metall-Komplexen Die Umwandlung von [Cd(L1)]— ([L1]3— = N[CH2CH2N=C(CH3)COO—]3) in den vierkernigen Cluster {[Cd(L1)]Na(H2O)2}2 in Anwesenheit von Na+ wird durch Na+-Carboxylat-Wechselwirkungen vermittelt. Im Gegensatz hierzu induzieren In3+ und Fe3+ die partielle Hydrolyse von [L1]3— unter Bildung der Komplexe [In(L2)Cl] und {[Fe(L2)]2O} ([L2]2— = N[CH2CH2NH2][CH2CH2N=C(CH3)COO—]2 ), die uber intermolekulare Wasserstoffbrucken-Bindungen aggregieren.

Hoganite, copper(II) acetate monohydrate, and paceite (pronounced ‘pace-ite’), calcium(II) copper(II) tetraacetate hexahydrate, occur as isolated crystals embedded in ferruginous gossan from the Potosi Pit, Broken Hill, New South Wales, Australia. They are associated with goethite, hematite, quartz, linarite, malachite, azurite, cerussite and cuprian smithsonite. Hoganite is bluish green with a pale blue streak and a Mohs hardness of 1½; it possesses perfect {001} and distinct {110} cleavages and has a conchoidal fracture. Chemical analysis of hoganite gave (wt.%) C 23.85; H 3.95; Cu 31.6; Fe 0.4; O (by difference) 40.2, yielding an empirical formula of C4H7.89O5.07Cu1.00Fe0.01. The simplified formula is C4H8O5Cu or Cu(CH3COO)2.H2O, the mineral being identical to the synthetic compound of the same formula. Single-crystal X-ray data for hoganite are: monoclinic, space group C2/c, a = 13.162(3), b = 8.555(2), c = 13.850(3)Å, β = 117.08(3)°, Z = 8. The density, calculated from single-crystal data, is 1.910 g cm−3. The strongest lines in the X-ray powder pattern are [dobs (Iobs) (hkl)] 6.921 (100) (011); 3.532 (28) (202); 6.176 (14) (200); 3.592 (11) (22); 5.382 (10) (11); 2.278 (10) (204); 5.872 (9) (002). Hoganite (orientation presently unknown) is biaxial positive with α = 1.533(2), β = 1.541(3), γ = 1.554(2), 2V(meas.) = 85(5)°, 2V(calc.) = 76.8°, dispersion is r < v, medium (white light); it is strongly pleochroic with X = blue, Y = pale bluish, Z = pale bluish green and absorption X > Y > Z. The mineral is named after Graham P. Hogan of Broken Hill, New South Wales, Australia, a miner and well-known collector of Broken Hill minerals.Paceite is dark blue with a pale blue streak and a Mohs hardness of 1½; it possesses perfect {100} and {110} cleavages and has an uneven fracture. Chemical analysis of paceite gave (wt.%) C 21.25; H 5.3; Ca 9.0; Cu 14.1; O (by difference) 50.35, yielding an empirical formula of C8H23.77O14.23Ca1.02-Cu1.00. The simplified formula is C8H24O14CaCu or CaCu(CH3COO)4.6H2O, the mineral being identical to the synthetic compound of the same formula. Unit-cell data (refined from X-ray powder diffraction data) for paceite are: tetragonal, space group I4/m, a = 11.155(4), c = 16.236(17)Å, Z = 4. The density, calculated from refined cell data, is 1.472 g cm−3. The strongest lines in the X-ray powder pattern are [dobs (Iobs) (hkl)] 7.896 (100) (110); 3.530 (20) (310); 5.586 (15) (200); 8.132 (8) (002); 9.297 (6) (101); 2.497 (4) (420); 3.042 (3) (321). Paceite is uniaxial positive with ω = 1.439(2) and ɛ = 1.482(3) (white light); pleochroism is bluish with a greenish tint (O), pale bluish with a greyish tint (E), and absorption O ⩾ E. The mineral is named after Frank L. Pace of Broken Hill, New South Wales, Australia, an ex-miner and well-known collector of Broken Hill minerals.

C-2 lithiation of acetals 2 followed by trapping with aldehydes gives 3. Subsequent unmasking of the acetal function provides furobenzo(thio)pyrans 4, cycloadditions of which have been investigated.

A multipole model of the charge density distribution in thioacetamide has been obtained using high-resolution single crystal X-ray diffraction data. Topological analysis of the total experimental charge density ρ(r) and its Laplacian −∇2ρ(r) at the bond critical points reveals fine details of intra- and intermolecular bonding features.

Indoleamine-2,3-dioxygenase-1 (IDO1) is a critical immunoregulatory enzyme responsible for the metabolism of tryptophan during inflammation and disease. Based upon a pyranonaphthoquinone framework, the first examples of indoleamine-2,3-dioxygenase-1 (IDO1) inhibitors containing a carborane cage are reported. The novel closo-1,2-carboranyl-N-pyranonaphthoquinone derivatives display low μM binding affinity for the human recombinant enzyme, with IC50 values ranging from 0.78 to 1.77 μM. Australian Research Council (ARC), NBCF

We examined the structure and composition of forested buffer strips in the central and northern Coast Range of Oregon and found little botanical evidence of an effect on plant community composition or dynamics from isolating these forests as buffers. Thus, concerns about microenvironmental changes due to extended edge effects appear unfounded in this region for the plant community. Tree stocking was low, especially on terraces; evidence suggests that competition, as well as site conditions, limit the regeneration of trees, including conifers. Understory diversity (richness) was greater under conifer canopy types; understory cover was greater under hardwood canopy types. Tree regeneration, especially on terraces and under hardwoods, was limited although more abundant than in older, unmanaged riparian forest. In the long term, succession models for this region suggest that many of these riparian areas will succeed to a largely treeless community.

Reactions of mercury(II) halides with 1,3-thiazolidine-2-thione (tzdSH) and benzo-1,3-thiazoline-2-thione (bztzSH) in aqueous ethanol produced the 1:2 complexes with the former ligand but, due to steric effects, only the previously described 1: 1 complexes of the latter were isolated. Vibrational and C-13 NMR spectral studies indicate eta (1)-thione donation by the heterocyclic ligand and this has been confirmed by the crystal structure determination of (tzdSH)(2)HgBr2. The structure consists of pseudotetrahedral mercury (II) with longer C-S and shorter C-N bonds than in the free ligand and with the Br-Hg-Br angle being similar to 20 degrees smaller than the largest angle, S-Hg-S, around mercury due to deformation by inter- and intra-molecular interactions. The heterocyclic ligands are unsymmetrical round mercury relative to the two bromines. Reaction of the two thiones with mercury(II) acetate in ethanol in the presence of triethylamine results in deprotonation with the formation of the corresponding thionates. The former produced insoluble (tzdS)(2)Hg while the latter formed plate-like (bztzS)(2)Hg whose crystal structure showed linearity around mercury with digonal coordination via the thionate sulphur. The small Hg-S-C angle and (HgN)-N-... separation are indicative of a weak interaction between mercury and the nitrogen of the thioamide double bond. (C) 2001 Elsevier Science B.V. All rights reserved.

5-endo-trig Iodocyclisations of the (E)-homoallylic sulfonamides 24 in the presence of potassium carbonate give excellent yields of trans-2,5-disubstituted-3-iodopyrrolidines 36. In the absence of base, these initial kinetic products undergo rapid isomerization to the corresponding cis-2,5-disubstituted pyrrolidines 37 by a ring opening–reclosure mechanism to these thermodynamic isomers. Octahydroindole derivatives 40 and 41 can be similarly obtained from the alk-2-enylcyclohexylsulfonamides 31 and 32. Attempted 5-endo-trig cyclisations of homoallylic carbamates were generally unsuccessful and resulted instead in relatively inefficient 6-exo cyclisations involving the carbamate carbonyl group. Deiodination provides both trans- and cis-2,5-disubstituted pyrrolidines [49 and 50]; the free amine derived from trans-2-butyl-5-pentylpyrrolidine 49d is a component of a fire ant defence pheromone. X-Ray crystallography was carried out for 37f, 36, and 37k.

The tyrosine kinase inhibitors (TKIs) and multikinase inhibitors (MKIs) are oncology drugs of increasing importance that have improved the treatment of multiple tumors types. In some patients these agents produce adverse effects, including pharmacokinetic drug-drug interactions, due to cytochrome P450 (CYP) inhibition. Information on the propensity of the drugs to elicit such effects often only becomes evident as the drugs enter clinical use. The present study assessed 18 kinase inhibitors (1 and 50 μM) for the inhibition of major drug metabolizing CYPs 1A2, 2C9, 2D6 and 3A4 in human liver microsomes. Most TKIs and MKIs inhibited CYP reactions at the higher concentration but axitinib also potently inhibited CYP1A2-dependent 7-ethoxyresorufin O-deethylation activity at the lower concentration. Kinetic analyses of CYP1A2 inhibition by axitinib were undertaken in microsomes and found a Ki of 0.11 ± 0.01 μM, which was 7.5-fold lower than the Km for 7-ethoxyresorufin oxidation (0.83 ± 0.06 μM); the inhibition mechanism was linear-mixed. From computational modeling two potential binding modes for axitinib were identified in the active site of CYP1A2: one in which the oxidizable axitinib thioether sulfur atom is within ~4.45 A of the CYP1A2 heme, and is likely to favor biotransformation of the drug, and a second in which the pyridine moiety is in proximity to the heme, which may contribute to inhibition. The applicability of these findings to potential pharmacokinetic interactions in patients during axitinib treatment should now be assessed.