Strong-field molecular ionization beyond the single active electron approximation.

This work explores quantitative limits to the single-active electron approximation, often used to deal with strong-field ionization and subsequent attosecond dynamics. Using a time-dependent, multiconfiguration approach, specifically the time-dependent configuration interaction method, we solve the time-dependent Schrödinger equation for the two-electron dihydrogen molecule with the possibility of tuning at will the electron-electron interaction by an adiabatic switch-on/switch-off function. We focus on signals of the single ionization of H2 under a strong near-infrared, four-cycle, linearly polarized laser pulse of varying intensity and within a vibrationally frozen molecular model. The observables we address are post-pulse total ionization probability profiles as a function of the laser peak intensity. Three values of the internuclear distance R taken as a parameter are considered, R = Req = 1.4 a.u. for the equilibrium geometry of the molecule, R = 5.0 a.u. for an elongated molecule, and R = 10.2 a.u. for a dissociating molecule. The most striking observation is the non-monotonous behavior of the ionization probability profiles at intermediate elongation distances with an instance of enhanced ionization and one of partial ionization quenching. We give an interpretation of this in terms of a resonance-enhanced-multiphoton ionization mechanism with interfering overlapping resonances resulting from excited electronic states.

White hard clam (Meretrix lyrata) shells as novel filter media to augment the phosphorus removal from wastewater.

It is well recognized that filter media play a crucial role in constructed wetlands (CWs) for decontamination of phosphorus (P)-rich wastewater. This study investigates the suitability of raw white hard clam shells (WHC) and white hard clam shells thermally modified at 800 °C (WHC-M800) as potential media to enhance P treatment performance in CWs. The results indicated that both WHC and WHC-M800 displayed appropriate physicochemical properties, such as high porosity, excellent hydraulic conductivity, and rich Ca content. WHC-M800 exhibited a superior P adsorption capacity (38.7 mg/g) to WHC (12.8 mg/g). However, the practical utilization of WHC-M800 as filter media in CWs may be compromised, due to certain limitations, for example: extremely high pH values in the post-adsorption solutions; high weight losses during calcination and adsorption processes; low mechanical strength; and intensive energy consumption. In contrast, the WHC demonstrated significant advantages of reasonably high P adsorption capacity, locally abundant availability, low cost, and marginal side effects. The fractionation of inorganic P of WHC and WHC-M800 revealed that Ca-bounded P was the most dominant binding form, followed by loosely bound P, Fe-P, occluded P, and Al-P. The present study demonstrates that recycling of WHC shells as a potential substrate in CWs provides a feasible method for upgrading P removal in CWs. Additionally, it helps to reduce waste WHC shells in a simple, cheap, and eco-friendly way, thus can double environmental benefits.

Twelve-day medium pumping into tubular cell-laden scaffold using a lab-made PDMS connector.

In the current study, a method is proposed to supply culture medium into a two-layered cell-laden tubular scaffold in order to enhance cell proliferation, confluence, and viability. The two-layered cell-laden tubular scaffold was made of calcium-alginate mixed with fibroblast cells (NIH/3T3) using a lab-made double- coaxial laminar-flow generator. Afterwards, the tubular scaffold was connected to a syringe pump system using a polydimethylsiloxane (PDMS) micro-connector for long-term cell culture. Three medium pumping conditions were applied and compared: a heart-beat-mimicking pumping (20 µL/s, 1 s period, and 50 % pulse width), a continuous pumping (20 µL/s) and a non-pumping. Non-leaky connections between the tubular scaffolds and the micro-connector outlet were sustained for 13.5 ± 0.83 d in heartbeat-mimicking pumping and 11.8 ± 0.33 d in continuous pumping condition, due to the elasticity of the tubular scaffolds. Importantly, the two pumping conditions resulted in more cell proliferation, confluence, and viability than the non-pumping condition. Furthermore, analysis of newly-produced type-I collagen matrix indicated that the cells under the two pumping conditions formed a tissue-like structure. The proposed technique could further be applied to vascular co-culturing for vascular engineered tissue.

Highlight on the solution processes occurring on silver(i)-assembling porphyrins in the presence of an excess of silver salt.

Coordination cages obtained upon complexation of pyridyl functionalized porphyrins by Ag+ disassemble when overtaking a 1 : 2 stoichiometric amount of silver salt. An excess of Ag+ then leads to unusual chemical processes, here analyzed in detail, which permanently transform the monomeric porphyrins. The observed processes, discussed with reference to model compounds devoid of polyether substituted pyridyl residues, evidence a peculiar reactivity for meso 2,6-dimethylphenyl substituted porphyrins.

Facile one-pot synthesis of multi-yolk-shell Bi@C nanostructures by the nanoscale Kirkendall effect.

Multi-yolk-shell Bi@C nanostructures were prepared via a facile one-pot template-free hydrothermal approach. The prepared Bi@C nanostructures can act as a solid catalyst in the thermal decomposition of cyclotrimethylenetrinitramine (RDX) and display excellent catalytic activity, which highlights their application in the field of energetic materials.

Recurrent pneumonia: a review with focus on clinical epidemiology and modifiable risk factors in elderly patients.

Community-acquired pneumonia (CAP) is one of the most common reasons for physician visits and hospitalizations in North America. Rates of CAP increase with age and CAP is associated with significant morbidity and mortality, especially in the elderly. Though there is much written about the epidemiology and risk factors of incident (first episode) pneumonia, much less is known about recurrent pneumonia. Rates of recurrent pneumonia within 3-5-years of an episode of CAP are 9-12% with a median time to recurrence of 123-317 days and mortality ranging from 4 to 10%. Age ≥65-years-old and impaired functional status are the only patient characteristics that are independently associated with increased risk of recurrence. In terms of modifiable risk factors, only the use of proton-pump inhibitors and systemic and inhaled corticosteroids have consistently been associated with increased risk of recurrent pneumonia, while angiotensin-converting enzyme (ACE) inhibitors may exert a protective effect. Many chronic medical conditions typically associated with increased incident pneumonia-such as chronic obstructive pulmonary disease (COPD), neurological disease (resulting in dysphagia or silent aspiration), and heart failure-were not associated with increased risk of recurrent pneumonia. However, those who are immune-suppressed (e.g., immunoglobulin deficiencies) may be at increased risk of recurrent pneumonia. In summary, among those who survive an episode of pneumonia, recurrence is not uncommon, particularly in the elderly. Following recovery from an episode of pneumonia, patients should be evaluated for risk factors that would predispose to a second episode including seeking evidence of immunosuppression in younger patients and medication optimization, particularly in the elderly.

Rates and risk factors for recurrent pneumonia in patients hospitalized with community-acquired pneumonia: population-based prospective cohort study with 5 years of follow-up.

BACKGROUND: The rates and risk factors for developing recurrent pneumonia following hospitalization with community-acquired pneumonia (CAP) are poorly understood. METHODS: We examined a population-based cohort of patients with CAP who survived hospital admission and who were free of pneumonia for at least 3 months. We collected clinical, functional, and medication-related information and pneumonia severity index (PSI). Using linked databases we followed patients for 5 years and captured any clinical episode of pneumonia 90 days or more post-discharge. We used Cox proportional hazards models (adjusted for age, sex, PSI, functional status, medications) to determine rates and independent correlates of recurrent pneumonia. RESULTS: The final cohort included 2709 inpatients; 43% were 75 years or older, 34% were not fully independent, and 56% had severe pneumonia. Over 5 years of follow-up, 245 (9%; 95% confidence interval [CI], 8%-10%) patients developed recurrent pneumonia, and 156 (64%) of these episodes required hospitalization. Rate of recurrence was 3.0/100 person-years and median time to recurrence was 317 days (interquartile range, 177-569); 32 (13%) patients had 2 or more recurrences. In multivariable analyses only age >75 years (adjusted P = .047) and less than fully independent functional status (12% recurrence rate with impaired functional status vs 7% for fully independent; adjusted hazard ratio, 1.7; 95% CI, 1.3-2.2; P < .001) were significantly associated with recurrent pneumonia. CONCLUSIONS: One of 11 patients who survived CAP hospitalization had recurrent pneumonia over 5 years and those with impaired functional status were at particularly high risk. Recurrent pneumonia is common and more attention to preventive strategies at discharge and closer follow-up over the long-term seem warranted.

[Population genetic structure of wild-growing ginseng (Planax ginseng C. A. Meyer) assessed using AFLP markers].

Genetic variability in ten populations of wild-growing ginseng was assessed using AFLP markers with the application of fragment analysis on a genetic analyzer. The variation indices were high in the populations (P = 55.68%; H(S) = 0.1891) and for the species (P = 99.65%; H(S) = 0.2857). Considerable and statistically significant population differentiation was demonstrated (theta = 0.363; Bayesian approach, "full model"; F(ST) = 0.36, AMOVA). The results of AMOVA and Bayesian analysis indicate that 64.46% of variability is found within the populations. Mantel test showed no correlation between the genetic and geographic distances among the populations (r = -0.174; P = 0.817). Hierarchical AMOVA and analysis of genetic relationships based on Euclidean distances (NJ, PCoA, and MST) identified two divergent population groups of ginseng. Low gene flow between these groups (N(m) = 0.4) suggests their demographic independence. In accordance to the concept of evolutionary significant units (ESU), these population groups, in terms of the strategy and tactics for conservation and management of natural resources, should be treated as management units (MUs). The MS tree topology suggests recolonization of southern Sikhote-Alin by ginseng along two directions, from south and west.

Molecular dissociative ionization and wave-packet dynamics studied using two-color XUV and IR pump-probe spectroscopy.

We present a combined theoretical and experimental study of ultrafast wave-packet dynamics in the dissociative ionization of H_{2} molecules as a result of irradiation with an extreme-ultraviolet (XUV) pulse followed by an infrared (IR) pulse. In experiments where the duration of both the XUV and IR pulses are shorter than the vibrational period of H_{2};{+}, dephasing and rephasing of the vibrational wave packet that is formed in H_{2};{+} upon ionization of the neutral molecule by the XUV pulse is observed. In experiments where the duration of the IR pulse exceeds the vibrational period of H_{2};{+} (15 fs), a pronounced dependence of the H;{+} kinetic energy distribution on XUV-IR delay is observed that can be explained in terms of the adiabatic propagation of the H_{2};{+} wave packet on field-dressed potential energy curves.

Behavior of simetryn and thiobencarb in the plough zone of rice fields.

The behavior of simetryn and thiobencarb in flooded rice soil was investigated in a 2-year study. The concentrations of simetryn and thiobencarb were in the hundreds of µg kg−1 in the top soil layer (0­5 cm) and became significantly lower in tens of µg kg−1 in the deeper soil layers (5­10 and 10­15 cm). The half-lives of the two herbicides were also shorter (36 and 17 days for simetryn and thiobencarb, respectively) in the top soil layer, as they were most affected by environmental conditions, compared with corresponding values of 82 and 69 days in the 5­10 cm soil layer. Simetryn concentration was stable, while thiobencarb's half-life was 165 days in the 10­15 cm layer. About 35% of the applied mass of simetryn and thiobencarb were found in the rice soil compartment.

State-resolved reactivity of CH4(2nu3) on Pt(111) and Ni(111): effects of barrier height and transition state location.

Quantum state-resolved sticking coefficients on Pt(111) and Ni(111) surfaces have been measured for CH4 excited to the first overtone of the antisymmetric C-H stretch (2nu3) at well-defined kinetic energies in the range of 10-90 kJ/mol. The ground-state reactivity of CH4 is approximately 3 orders of magnitude lower on Ni(111) than on Pt(111) for kinetic energies in the range of 10-64 kJ/mol, reflecting a difference in barrier height of 28+/-6 kJ/mol. 2nu3 excitation of CH4 increases its reactivity by more than 4 orders of magnitude on Ni(111), whereas on Pt(111) the reactivity increase is lower by 2 orders of magnitude. We discuss the observed differences in the state-resolved reactivity for the ground state and 2nu3 excited state of methane in terms of a difference in barrier height and transition state location for the dissociation reaction on the two metal surfaces.

Cavity ring-down spectroscopy of jet-cooled silane isotopologues in the Si-H stretch overtone region.

Absorption spectra of silane in the region of the first overtone of the Si-H stretch vibration have been recorded in a seeded supersonic jet expansion by cavity ring-down spectroscopy as well as in a static gas cell at room temperature by photoacoustic spectroscopy. Spectral simplification due to strong rotational cooling in the jet expansion enables us to clearly resolve and assign the rovibrational transitions of the (2000) and (1100) bands of the three isotopologues, (28)SiH(4), (29)SiH(4), and (30)SiH(4), in their natural isotopic abundance. Interconversion between different nuclear spin species of SiH(4) is found to be absent during the jet expansion. Isotope shifts for (29)SiH(4) and (30)SiH(4) relative to (28)SiH(4) are measured and found to be suitable for selective vibrational excitation of any of three silane isotopologues by pulsed laser excitation in a jet expansion.

Temporal dynamics of dairy health and production in rural smallholder communities in Northern Vietnam.

The objective of this field study was to describe the temporal pattern of dairy cattle health and production and associated risk factors in rural small-holder communities in northern Vietnam, one of the target areas of the government's dairy development programme. A total of 99 dairy farms (11 per commune) were recruited from 9 of 32 communes in Ba Vi District, Ha Tay Province, using random two-stage cluster sampling. All dairy cattle present on the selected farms were included. After the initial questionnaire survey was conducted, farms were visited to collect follow-up information at 3-monthly intervals over a period of one year. The results suggest that offtake as well as mortality are important productivity indices because farmers sell or slaughter dairy cattle that are in poor health at low prices during summer months. Changes in relation to the farming operation suggest that for the farmers adopting dairy production it has become one of the main agricultural activities.

A longitudinal study to identify constraints to dairy cattle health and production in rural smallholder communities in Northern Vietnam.

The objective of the study was to investigate constraints to dairy cattle health and production in rural smallholder communities in northern Vietnam, one of the target areas of the Vietnam government's dairy development programme. A total of 99 dairy farms (11 per commune) were recruited from 9 of 32 communes in Ba Vi District, using random two-stage cluster sampling. After the initial questionnaire interviews were conducted, farms were visited at three monthly intervals over a period of 1 year. Information on several health and production parameters relating to the study cattle was collected. Using multiple indicator modelling, it was found that Fasciola infestation, farmers who had been involved in dairying for longer (not indicative of better management skills), larger herd size, and cattle being kept in a shed were linked to reduced reproductive performances.

Steep increase in HIV prevalence among tuberculosis patients in Ho Chi Minh City.

In Vietnam the spread of HIV infection is thought to be limited. In 12 urban districts of Ho Chi Minh City representative samples of tuberculosis patients have undergone HIV testing since 1995. HIV prevalence increased steeply from 0.5% in 1995 to 4% in 2000, with a doubling time of approximately 21 months. This study highlights the need to intensify HIV/AIDS prevention and control in Vietnam.

Molecular characterization of CD40 signaling intermediates.

Signal transduction through the CD40 receptor is initiated by binding of its trimeric ligand and propagated by interactions of tumor necrosis factor receptor-associated factor (TRAF) proteins with the multimerized CD40 cytoplasmic domain. Using defined multimeric constructs of the CD40 cytoplasmic domain expressed as either soluble or myristoylated proteins, we have addressed the extent of receptor multimerization needed to initiate signal transduction and identified components of CD40 signaling complexes. Signal transduction in human embryonic kidney 293 cells, measured by nuclear factor kappaB activation, was observed in cells expressing soluble trimeric CD40 cytoplasmic domain and to a lesser extent in cells expressing dimeric CD40 cytoplasmic domain. Nuclear factor kappaB activation was strongest in cells expressing myristoylated trimeric CD40 cytoplasmic domain. Signal transduction through trimeric CD40 cytoplasmic domains with various point mutations in the TRAF binding sites was similar to signal transduction through analogous full-length receptors. Transiently expressed soluble trimeric CD40 cytoplasmic domain was isolated as complexes that contained TRAF2, TRAF3, TRAF5, TRAF6, and the inhibitor of apoptosis protein (c-IAP1). Association of c-IAP1 with the CD40 cytoplasmic domain complex was indirect and dependent on the presence of an intact TRAF1/2/3 binding site. These results suggest that extracellular ligation of CD40 can be bypassed and that soluble trimerized CD40 complexes can be isolated and used to identify components that link CD40 with signaling pathways.

CD40 signaling through tumor necrosis factor receptor-associated factors (TRAFs). Binding site specificity and activation of downstream pathways by distinct TRAFs.

Tumor necrosis factor receptor-associated factors (TRAFs) associate with the CD40 cytoplasmic domain and initiate signaling after CD40 receptor multimerization by its ligand. We used saturating peptide-based mutational analyses of the TRAF1/TRAF2/TRAF3 and TRAF6 binding sequences in CD40 to finely map residues involved in CD40-TRAF interactions. The core binding site for TRAF1, TRAF2, and TRAF3 in CD40 could be minimally substituted. The TRAF6 binding site demonstrated more amino acid sequence flexibility and could be optimized. Point mutations that eliminated or enhanced binding of TRAFs to one or both sites were made in CD40 and tested in quantitative CD40-TRAF binding assays. Sequences flanking the core TRAF binding sites were found to modulate TRAF binding, and the two TRAF binding sites were not independent. Cloned stable transfectants of human embryonic kidney 293 cells that expressed wild type CD40 or individual CD40 mutations were used to demonstrate that both TRAF binding sites were required for optimal NF-kappaB and c-Jun N-terminal kinase activation. In contrast, p38 mitogen-activated protein kinase activation was primarily dependent upon TRAF6 binding. These studies suggest a role in CD40 signaling for competitive TRAF binding and imply that CD40 responses reflect an integration of signals from individual TRAFs.

CD40-tumor necrosis factor receptor-associated factor (TRAF) interactions: regulation of CD40 signaling through multiple TRAF binding sites and TRAF hetero-oligomerization.

CD40 is a TNF receptor superfamily member that provides activation signals in antigen-presenting cells such as B cells, macrophages, and dendritic cells. Multimerization of CD40 by its ligand initiates signaling by recruiting TNF receptor-associated factors (TRAFs) to the CD40 cytoplasmic domain. Recombinant human TRAF proteins overexpressed in insect cells were biochemically characterized and used to finely map TRAF binding regions in the human CD40 cytoplasmic domain. TRAF1, TRAF2, TRAF3, and TRAF6, but not TRAF4 or TRAF5, bound directly to the CD40 cytoplasmic domain. CD40 interactions with TRAF2 and TRAF3 were stronger than the interactions with TRAF1 and TRAF6. Full-length TRAF3 and TRAF5 formed hetero-oligomers, presumably through their predicted isoleucine zippers. TRAF3-TRAF5 hetero-oligomers interacted with CD40, indicating that TRAF5 can be indirectly recruited to the CD40 cytoplasmic domain. Overlapping peptides synthesized on cellulose membranes were used to map each TRAF interaction region. TRAF1, TRAF2, and TRAF3 interacted with the same region. The recognition site for TRAF6 was a nonoverlapping membrane proximal region. Using peptides with progressive deletions, a minimal TRAF1, TRAF2, and TRAF3 binding region was mapped to the PVQET sequence in the CD40 cytoplasmic domain. The minimal region for TRAF6 binding was the sequence QEPQEINF. These studies demonstrate that the CD40 cytoplasmic domain contains two nonoverlapping TRAF binding regions and suggest that TRAF1, TRAF2, and TRAF3 could bind competitively to one site. Relative affinities and competition of individual and hetero-oligomeric TRAF proteins for CD40 binding sites may contribute to receptor specificity and cell-type selectivity in CD40-dependent signaling.

Immunolocalization of basic fibroblast growth factor and platelet-derived growth factor-A during adjuvant arthritis in the Lewis rat.

A prerequisite in defining the role of a growth factor in a disease is knowledge of its expression kinetics during the natural course of the disease. We, therefore, used immunohistochemical and immunoblot analyses to examine tissue distribution of basic fibroblast growth factor (bFGF) and platelet-derived growth factor (PDGF-A) during the development of destructive arthropathy in the rat adjuvant arthritis model. In normal joints, bFGF was primarily localized in endothelial cells. In inflamed joints, increased staining for bFGF was found in the invading panni, hyperplastic synovium, and thickened periosteum where bFGF was also co-localized with two cell proliferation markers. Staining for bFGF began to increase at the onset of arthritis (days 11 to 13), reached peak level on days 17 to 24, and gradually declined afterward. In contrast, PDGF-A staining did not change until day 17 and the increased staining was restricted to areas of newly formed bone. The district temporal and spatial distribution pattern of these two growth factors during the destructive arthropathy strongly suggests that they play different roles during arthritis. Although PDGF-A seems to be exclusively related to osteogenesis, bFGF may have a more extensive impact on synovial proliferation and bone destruction as well as bone formation.