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Adsorption of chiral molecules on chiral surfaces implies diastereomerism, evident in the adoption of distinct adsorption geometries. We show here that this diastereomerism produces a signature in the motion of chiral molecules desorbing from a chiral surface. The rotations of S- and R-alanine molecules are analyzed upon desorption from R-Cu{531} using first-principles molecular dynamics simulations. S-Ala molecules exhibit a larger angular momentum, with a clear preference for one rotational sense, whereas no such preference is observed for R-Ala molecules upon desorption from this surface. These trends would be reversed for desorption from the S-Cu{531} surface. Possible applications include chiral separation techniques and enantiospecific sensors.

The interaction of highly reactive species with solid surfaces can result in modes of adsorption quite distinct from the classic molecular and dissociative events that are usually thought to dominate. For instance, compelling experimental evidence suggests that adsorption of F2at the Si{001} surface is often initiated by abstraction (and binding at the surface) of just one fluorine atom from the molecule; the second fluorine atom subsequently experiences either a separate atomic adsorption event or ejection from the surface altogether. Molecular dynamics simulations using empirical potentials support this concept but massively overestimate the prevalence of atomic ejection. In this work, we report first-principles molecular dynamics calculations that correctly show atomic ejection to be rare while providing insight into the details of abstractive adsorption. In addition, we also examine the case of F2adsorption onto a monohydrogenated Si{001} surface, finding evidence for a different type of abstractive adsorption, in which a hydrogen atom may be removed from the surface to form a short-lived HFF intermediate. The latter rapidly decomposes to produce either HF or (via reaction with another surface hydrogen atom) H2.

Hypoxemia is a defining feature of acute respiratory distress syndrome (ARDS), an often-fatal complication of pulmonary or systemic inflammation, yet the resulting tissue hypoxia, and its impact on immune responses, is often neglected. In the present study, we have shown that ARDS patients were hypoxemic and monocytopenic within the first 48 h of ventilation. Monocytopenia was also observed in mouse models of hypoxic acute lung injury, in which hypoxemia drove the suppression of type I interferon signaling in the bone marrow. This impaired monopoiesis resulted in reduced accumulation of monocyte-derived macrophages and enhanced neutrophil-mediated inflammation in the lung. Administration of colony-stimulating factor 1 in mice with hypoxic lung injury rescued the monocytopenia, altered the phenotype of circulating monocytes, increased monocyte-derived macrophages in the lung and limited injury. Thus, tissue hypoxia altered the dynamics of the immune response to the detriment of the host and interventions to address the aberrant response offer new therapeutic strategies for ARDS.

We investigate the adsorption and reaction of NO on Cu{311} viaa combination of reflection absorption infrared spectroscopy (RAIRS) and first-principles density functional theory (DFT), providing a mechanistic understanding of the reaction as it progresses. Our results support an interpretation that N2O is formed viaan associative mechanism involving N2O2as the crucial intermediate species. Consistent with previous work, we find that such an intermediate readily converts between its initial nitrogen-down configuration and an inverted oxygen-down configuration, prior to decomposition by cleavage of a single N–O bond. As the reaction proceeds, the surface is progressively poisoned by the accumulation of O adatoms resulting from N–O bond scission, and we probe this aspect of the reaction in detail as a function both of temperature and of the surface's pre-exposure to oxygen. Our results indicate that sustained conversion of NO to N2O on Cu would be contingent upon identifying some co-reactant capable of continuously removing O from the surface as the reaction proceeds.

When the interactions between surfaces and adsorbates are studied, molecular rotations are often neglected. In this work, we carefully analyze the rotational dynamics of methane and ethane molecules desorbing from two different platinum surfaces by means of first-principles molecular dynamics simulations. With respect to its rotational symmetry, methane, a benchmark system for adsorption dynamics, constitutes a spherical top and ethane is a symmetric top. We focus on the achiral Pt{110}-(1×2) surface, which exhibits both mirror symmetry and a stepped geometry, and on the chiral Pt{531} surface, which exhibits kink sites and lacks reflection symmetry. For methane, neither a strong nor directed angular momentum is induced by either of the two surfaces, whereas for ethane we find an increased directionality for the molecular rotation upon desorption from Pt{531} compared to Pt{110}-(1×2). The principle of microscopic reversibility implies that such results (in time reversal) will also be relevant to the process of adsorption, which would therefore be sensitive to the initial rotational state of incoming molecules.

A homologous series of halogen bonding monolayers based on terminally iodinated perfluoroalkanes and 4,4′-bipyridine have been observed on a graphitic surface and noninvasively probed using powder X-ray diffraction. An excellent agreement is observed between the X-ray structures and density functional theory calculations with dispersion force corrections. Theoretical analysis of the binding energies of the structures indicate that these halogen bonds are strong (25 kJ mol–1), indicating that the layers are highly stable. The monolayer structures are found to be distinct from any plane of the corresponding bulk structures, with limited evidence of partitioning of hydrocarbon and perfluoro tectons. The interchain interactions are found to be slightly stronger than those in related aromatic systems, with important implications for 2D crystal engineering.

We report on reflection absorption infrared spectroscopy (RAIRS) investigations into the influence of oxygen on the surface chemistry of NH3on Fe{111}. Preadsorption of oxygen is found to strengthen the interaction between ammonia and the surface, albeit at the lowest oxygen coverage examined the effect is only notable when the ammonia coverage becomes high. At higher oxygen coverage, the same effect is observed even with very low ammonia coverage. In cases where the oxygen overlayer is ordered, the effects are seen quite clearly, but for disordered overlayers, the surface heterogeneity makes assignment of absorption features more difficult; nevertheless, comparison with the ordered examples allows us to identify the same underlying behavior. When potassium is coadsorbed with oxygen, the effect on ammonia adsorption is three-fold, including potassium-dominated and oxygen-dominated features, alongside features that suggest either canceling or absent influences from the atomic adsorbates. Synthesis of ammonia from nitrogen adatoms in 0.6 mbar H2shows clear evidence of very similar surface interactions.

We describe a method for the calculation of chemical softness at metal surfaces, demonstrating its utility in understanding the adsorption of benzene, nitrobenzene and anisole at the Pt{111} surface. Based on this method, we show that directing effects due to either of the substituent groups are mostly swamped by substrate influences, while significant variations in softness within the groups themselves are readily apparent.

Multicolor flow cytometry and cell sorting are powerful immunologic tools for the study of hepatic mϕ, yet there is no consensus on the optimal method to prepare liver homogenates for these analyses. Using a combination of mϕ and endothelial cell reporter mice, flow cytometry, and confocal imaging, we have shown that conventional flow‐cytometric strategies for identification of Kupffer cells (KCs) leads to inclusion of a significant proportion of CD31hiendothelial cells. These cells were present regardless of the method used to prepare cells for flow cytometry and represented endothelium tightly adhered to remnants of KC membrane. Antibodies to endothelial markers, such as CD31, were vital for their exclusion. This result brings into focus recently published microarray datasets that identify high expression of endothelial cell‐associated genes by KCs compared with other tissue‐resident mϕ. Our studies also revealed significant and specific loss of KCs among leukocytes with commonly used isolation methods that led to enrichment of proliferating and monocyte‐derived mϕ. Hence, we present an optimal method to generate high yields of liver myeloid cells without bias for cell type or contamination with endothelial cells. Protocol to remove endothelial cell contamination and selection bias inherent in conventional methods for isolating and analyzing liver Kupffer cells.

We have investigated the adsorption of pyridine on Cu(110) in ultrahigh vacuum through a combination of work-function measurements and femtosecond infrared–visible sum and difference frequency generation (SFG/DFG). A monolayer of pyridine substantially reduces the work function by 2.9 eV because of the large pyridine dipole. We performed density functional theory (DFT) calculations that provided the change in dipole moment upon adsorption, in very good agreement with the experimental results. The pyridine dipole strongly enhances the sum frequency response of the surface electrons, but surprisingly, it reduces the surface difference frequency signal. We propose a model based on the static electric-field-induced nonlinear optical response generated by the collective electric field of the adsorbate layer. The pyridine dipole switches direction from the ground to the excited electronic state, as charge moves from nitrogen to the ring. SFG can then be enhanced by the electric field of adsorbed pyridine in its ground electronic state, whereas the 2.33-eV incident photon in DFG excites electrons into the pyridine LUMO, which reverses the electric field in the adsorbate layer and reduces the nonlinear optical response. The model was verified by 2.33-eV pump–SFG probe spectroscopy, where the pump pulse was found to reduce the surface electron response on a subpicosecond time scale. This demonstrates the potential for manipulating the work function in organic electronic devices by photon-induced dipole-moment reversal.

Understanding the interplay between intrinsic molecular chirality and chirality of the bonding footprint is crucial in exploiting enantioselectivity at surfaces. As such, achiral glycine and chiral alanine are the most obvious candidates if one is to study this interplay on different surfaces. Here, we have investigated the adsorption of glycine on Cu{311} using reflection–absorption infrared spectroscopy, low-energy electron diffraction, temperature-programmed desorption, and first-principles density-functional theory. This combination of techniques has allowed us to accurately identify the molecular conformations present under different conditions and discuss the overlayer structure in the context of the possible bonding footprints. We have observed coverage-dependent local symmetry breaking, with three-point bonded glycinate moieties forming an achiral arrangement at low coverages, and chirality developing with the presence of two-point bonded moieties at high coverages. Comparison with previous work on the self-assembly of simple amino acids on Cu{311} and the structurally similar Cu{110} surface has allowed us to rationalize the different conditions necessary for the formation of ordered chiral overlayers.

Chirality can manifest itself in diverse ways when a molecule adsorbs on a metal surface. A clear understanding of the interplay between molecular chirality, “footprint chirality”, and chirality in the long-range self-organization is crucial if metal surfaces are to be exploited for enantioselective heterogeneous catalysis or enantio-discriminating sensors. We have investigated the self-organization of l-alanine adsorbed as alaninate on Cu{311}, using reflection–absorption infrared spectroscopy in conjunction with first-principles calculations to determine bonding configurations, and low-energy electron diffraction and scanning tunnelling microscopy to elucidate structural features. Three ordered structures are seen. One has a symmetric lattice and 3-point adsorbate bonding (the “symmetric lattice” or SL phase); the others, occurring at higher coverage, have chiral lattices and also involve 2-point bonding (the “chiral lattice” or CL phase). Possible models for these structures are discussed, together with the roles of footprint chirality and of long-range chirality in the self-organization. These results set the forms of chirality seen in alaninate overlayers on Cu{110} and {100} surfaces into a wider context. The common underlying principles should help in establishing a general framework for understanding the behavior of chiral adsorbates on low-symmetry metal surfaces.

ABSTRACTThe larval stage of the cestode parasite Echinococcus granulosuscauses hydatid disease in humans and livestock. This infection is characterized by the growth in internal organ parenchymae of fluid-filled structures (hydatids) that elicit surprisingly little inflammation in spite of their massive size and persistence. Hydatids are protected by a millimeter-thick layer of mucin-based extracellular matrix, termed the laminated layer (LL), which is thought to be a major factor determining the host response to the infection. Host cells can interact both with the LL surface and with materials that are shed from it to allow parasite growth. In this work, we analyzed the response of dendritic cells (DCs) to microscopic pieces of the native mucin-based gel of the LL (pLL). In vitro, this material induced an unusual activation state characterized by upregulation of CD86 without concomitant upregulation of CD40 or secretion of cytokines (interleukin 12 [IL-12], IL-10, tumor necrosis factor alpha [TNF-a], and IL-6). When added to Toll-like receptor (TLR) agonists, pLL-potentiated CD86 upregulation and IL-10 secretion while inhibiting CD40 upregulation and IL-12 secretion. In vivo, pLL also caused upregulation of CD86 and inhibited CD40 upregulation in DCs. Contrary to expectations, oxidation of the mucin glycans in pLL with periodate did not abrogate the effects on cells. Reduction of disulfide bonds, which are known to be important for LL structure, strongly diminished the impact of pLL on DCs without altering the particulate nature of the material. In summary, DCs respond to the LL mucin meshwork with a “semimature” activation phenotype, both in vitroand in vivo.

Macrophages (MΦs) colonize tissues during inflammation in two distinct ways: recruitment of monocyte precursors and proliferation of resident cells. We recently revealed a major role for IL-4 in the proliferative expansion of resident MΦs during a Th2-biased tissue nematode infection. We now show that proliferation of MΦs during intestinal as well as tissue nematode infection is restricted to sites of IL-4 production and requires MΦ-intrinsic IL-4R signaling. However, both IL-4Rα–dependent and –independent mechanisms contributed to MΦ proliferation during nematode infections. IL-4R–independent proliferation was controlled by a rise in local CSF-1 levels, but IL-4Rα expression conferred a competitive advantage with higher and more sustained proliferation and increased accumulation of IL-4Rα+ compared with IL-4Rα− cells. Mechanistically, this occurred by conversion of IL-4Rα+ MΦs from a CSF-1–dependent to –independent program of proliferation. Thus, IL-4 increases the relative density of tissue MΦs by overcoming the constraints mediated by the availability of CSF-1. Finally, although both elevated CSF1R and IL-4Rα signaling triggered proliferation above homeostatic levels, only CSF-1 led to the recruitment of monocytes and neutrophils. Thus, the IL-4 pathway of proliferation may have developed as an alternative to CSF-1 to increase resident MΦ numbers without coincident monocyte recruitment.

We have investigated the interaction of H2and NH3with {100} surfaces of iron pyrite (FeS2) in ultrahigh vacuum (UHV) and the synthesis of NH3from the reaction of preadsorbed atomic N with atomic H, the H either preadsorbed on or arriving at the surface, all at surface temperatures of 170 K or above. Hydrogen adsorbs and reacts only when it arrives at the surface as atomic H, after cracking at a hot filament. Recombinative desorption of H2occurs with a peak temperature of 225 K and is accompanied by desorption of H2S, formed by surface reaction of Hadswith S, with a peak temperature of 260 K. NH3adsorbs molecularly from the gas phase, albeit with some degree of partial dissociation, and desorbs with a peak temperature of 215 K. NH3can be synthesized when the surface, after pre-exposure to activated nitrogen, is exposed to atomic H. The synthesized NH3desorbs with a peak temperature of 230 K, demonstrating that all hydrogenation steps are feasible under these conditions; the process appears to be desorption-limited. The results are discussed in comparison with both industrial Haber-Bosch NH3synthesis and natural NH3synthesis by the enzyme nitrogenase. The potential significance of the low-temperature hydrogenation and desorption, in the context of a possible bioinspired approach toward ammonia synthesis, is outlined.

Macrophage (MΦ) activation must be tightly controlled to preclude overzealous responses that cause self-damage. MicroRNAs promote classical MΦ activation by blocking antiinflammatory signals and transcription factors but also can prevent excessive TLR signaling. In contrast, the microRNA profile associated with alternatively activated MΦ and their role in regulating wound healing or antihelminthic responses has not been described. By using an in vivo model of alternative activation in which adult Brugia malayi nematodes are implanted surgically in the peritoneal cavity of mice, we identified differential expression of miR-125b-5p, miR-146a-5p, miR-199b-5p, and miR-378-3p in helminth-induced MΦ. In vitro experiments demonstrated that miR-378-3p was specifically induced by IL-4 and revealed the IL-4–receptor/PI3K/Akt-signaling pathway as a target. Chemical inhibition of this pathway showed that intact Akt signaling is an important enhancement factor for alternative activation in vitro and in vivo and is essential for IL-4–driven MΦ proliferation in vivo. Thus, identification of miR-378-3p as an IL-4Rα–induced microRNA led to the discovery that Akt regulates the newly discovered mechanism of IL-4–driven macrophage proliferation. Together, the data suggest that negative regulation of Akt signaling via microRNAs might play a central role in limiting MΦ expansion and alternative activation during type 2 inflammatory settings.

Density functional theory is employed to investigate the stepwise decomposition of hydrazine on Fe{211}. Local energy minima are described for N2Hx(x= 0–4) intermediates, along with the transition states and pathways that connect them. We find that the dehydrogenation (N–H scission) and nitrogen decoupling (N–N scission) steps have activation energies in the range of 0.91 to 1.04 eV, with the exception of bond-breaking in NNH2(barrier of 0.52 eV) and for NNH (barrier of 0.55 eV). The reverse reactions of hydrogenation (N–H formation) and nitrogen coupling (N–N formation) have activation energies between 1.24 and 2.01 eV and 2.33 and 4.46 eV, respectively. Dehydrogenation and nitrogen decoupling are therefore generally competitive routes for hydrazine decomposition, with the dominant surface products at low-to-moderate temperatures being NH2moieties and N adatoms. Elevated temperatures should allow for the evolution of gas-phase N2and NH3, the latter species being particularly favored under conditions of excess hydrogen.

The dissociation and synthesis of ammonia (NH3) have been extensively investigated for over a century, but detailed understanding of key reaction steps is still rather limited. In this work, we study the behavior of ammonia and related compounds on the Fe{211} surface, calculating the energetics of the complete hydrogenation/deydrogenation reaction profile and characterizing transition states for each bond-breaking process.

Gold atoms act as anchoring sites for gold nanoparticles in the ceria-catalyzed water−gas shift reaction; however, the anchoring site of the nanoparticle is a matter of debate. Both oxygen and cerium vacancies have been suggested as the anchoring sites in different studies. Aiming to provide insight into this issue, we utilize density functional theory and ab initio thermodynamics approaches to investigate the formation of various vacancies at a CeO2{111} surface, both with and without gold adatoms. We find that, under reaction conditions, the cerium vacancy is much harder to form and is much less stable than the oxygen vacancy, regardless of the absence or presence of gold on the surface. Gold adsorption at the oxygen vacancy site is strongly preferred to that on the cerium vacancy; the latter becomes favorable only near the extreme oxygen-rich limit, which would not be achievable under the reaction conditions. Other possible vacancies have also been examined. We find that in addition to a single oxygen vacancy, oxygen vacancy clusters could also be anchoring sites for gold nucleation. This study lays a foundation toward understanding the boundary structure between Au nanoparticlues and ceria support, which in turn would hold promise to unravel their catalytic roles.

This study investigated demographic, personality, and attitude differences between students enrolled in online courses and students enrolled in traditional, lecture courses. Subjects were 120 education majors enrolled in required Master's of Education core courses. Students enrolled in either online (n= 51) or traditional course format (n= 69) during summer and fall semesters 2001. The two groups of students were compared on an author-designed questionnaire assessing students' demographic characteristics and attitudes toward both online and traditional instruction and the Cattell Sixteen Personality Factor Questionnaire. Analysis indicated high demographic and interpersonal similarity between students enrolled in online course formats and students enrolled in traditional, face-to-face course formats. Significant differences in attitude were found between the two groups; online courses were rated higher by online students but viewed with considerable ambivalence by students enrolled in traditional section courses.

Personality profiles of education majors were compared using the California Psychological Inventory and Edwards Personal Preference Schedule. Discriminant analyses indicated significant differences on selected scales for men (n= 50) and women (n= 112) and for those interested in elementary and secondary teaching. These findings are discussed in terms of their relevance to the future teaching activities of education majors.

One of the most frequent criticisms leveled against using nonparametric statistics is their alleged lack of power or sensitivity compared to their parametric counterparts. Empirical studies of the power of nonparametric procedures versus their parametric partners have shown that their lack of power, in many situations, is a myth. Where there is evidence that distributions depart appreciably from normality and the variances are not homogeneous, the probability is enhanced that the power advantage can be found in the nonparametric procedures.

Drug attitude and use assessment of 598 undergraduate students revealed attitudinal differences between anticipated occupation groups and drug use patterns that paralleled prior studies which used college student samples. Results are discussed as they pertain to the education of those planning to enter the teaching profession.

An analysis of 1698 empirical articles published in the Journal of Counseling Psychologysince 1954 was performed to provide an examination of the patterns of use of non-parametric statistical procedures. Analysis indicated that non-parametric procedures have not been as widely used as parametric procedures. It was also evident that the use of non-parametric procedures has steadily declined over time. The question of the appropriateness of the domination of parametric procedures emerges.

Ninety-seven adult children of alcoholics (ACOAs), 36 adults with dysfunctional family histories, and 41 adults without identified dysfunctional family histories were compared on self-reports of 20 adult characteristics. Significant differences among the groups were found on 4 of the characteristics, with the ACOA group showing the highest frequency of occurrence on 17 of them. No differences due to gender of the alcoholic parent were found, and there was no group by gender interaction. The results suggested that the clinical characteristics attributed to ACOAs may have some empirical validity but the ACOAs seem fairly similar to adults with other types of dysfunctional family histories.

A review of the literature concerning factors predictive of duration in counseling indicates, on the whole, inconsistent and often conflicting results. The present study examined the relationship between selected variables related to clients, therapists, and system and duration of counseling with a sample of 428 clients of a university counseling center. The initial interview data indicated that six variables were significantly related to duration but collectively only accounted for 23% of the variance. It is argued that efforts to delineate factors relating to duration of treatment might profitably consider variables pertaining to other phases of the counseling process.

Few standardized instruments measure attitudes and beliefs towards substance abuse. The Substance Abuse Attitude Survey, developed for measuring drug attitudes in medical education, was administered to 598 college undergraduates, and a factor analysis was performed. Three coherent and stable factors were identified, e.g., Stereotypes and Moralism, Treatment, and Permissiveness. Internal consistency and 6-wk. test-retest measures indicated moderate to high reliability factor structure. Results are discussed in terms of sample differences between this effort and a previous validation.

This study investigated the relationship between scores on the California Psychological Inventory and Carkhuff's accurate empathy rating scale for 49 graduate students in counselor education, rs ranged from - .42 for Dominance to .30 for ‘v.1,’ the internality-externality vector.

Interpretation of motion under three levels of motion cues for 36 kindergarten and 36 third-grade children was examined. Analysis indicated that third-grade children were more skillful at identifying motion than kindergartners and postural cues were more effective than flow lines.

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Mean scores of 49 counseling majors on the California Personality Inventory indicated the 13 men showed more favorable personal characteristics than the 36 women.