bluuebunny/crossref_metadata_2025 huggingface dataset:
Innate Immune Responses in Human Monocyte-Derived Dendritic Cells Are Highly Dependent on the Size and the 5′ Phosphorylation of RNA Molecules
Authors: Jiang Miao , Österlund Pamela , Sarin L. Peter , Poranen Minna M. , Bamford Dennis H. , Guo Deyin , Julkunen Ilkka
Published: July 2011

Recognition of viral genetic material takes place via several different receptor systems, such as retinoic acid-inducible gene I-like receptors and TLRs 3, 7, 8, and 9. At present, systematic comparison of the ability of different types of RNAs to induce innate immune responses in human immune cells has been limited. In this study, we generated bacteriophage ϕ6 and influenza A virus-specific ssRNA and dsRNA molecules ranging from 58 to 2956 nt. In human monocyte-derived dendritic cells (moDCs), short dsRNAs efficiently upregulated the expression of IFN (IFN-α, IFN-β, and IFN–λ1) and proinflammatory (TNF-α, IL-6, IL-12, and CXCL10) cytokine genes. These genes were also induced by ssRNA molecules, but size-specific differences were not as pronounced as with dsRNA molecules. Dephosphorylation of short ssRNA and dsRNA molecules led to a dramatic reduction in their ability to stimulate innate immune responses. Such a difference was not detected for long ssRNAs. RNA-induced cytokine responses correlated well with IFN regulatory factor 3 phosphorylation, suggesting that IFN regulatory factor 3 plays a major role in both ssRNA- and dsRNA-activated responses in human moDCs. We also found that IFN gene expression was efficiently stimulated following recognition of short dsRNAs by retinoic acid-inducible gene I and TLR3 in human embryonic kidney 293 cells, whereas ssRNA-induced responses were less dependent on the size of the RNA molecule. Our data suggest that human moDCs are extremely sensitive in recognizing foreign RNA, and the responses depend on RNA size, form (ssRNA versus dsRNA), and the level of 5′ phosphorylation.
Soluble Proteins Induce Strong CD8+ T Cell and Antibody Responses through Electrostatic Association with Simple Cationic or Anionic Lipopeptides That Target TLR2
Authors: Chua Brendon Y. , Pejoski David , Turner Stephen J. , Zeng Weiguang , Jackson David C.
Published: July 2011

The low immunogenicity exhibited by most soluble proteins is generally due to the absence of molecular signatures that are recognized by the immune system as dangerous. In this study, we show that electrostatic binding of synthetic branched cationic or anionic lipopeptides that contain the TLR-2 agonist Pam2Cys markedly enhance a protein’s immunogenicity. Binding of a charged lipopeptide to oppositely charged protein Ags resulted in the formation of stable complexes and occurs at physiologic pH and salt concentrations. The induction of cell-mediated responses is dependent on the electrostatic binding of lipopeptide to the protein, with no CD8+ T cells being elicited when protein and lipopeptide possessed the same electrical charge. The CD8+ T cells elicited after vaccination with lipopeptide–protein Ag complexes produced proinflammatory cytokines, exhibited in vivo lytic activity, and protected mice from challenge with an infectious chimeric influenza virus containing a single OVA epitope as part of the influenza neuraminidase protein. Induction of a CD8+ T cell response correlated with the ability of lipopeptide to facilitate Ag uptake by DCs followed by trafficking of Ag-bearing cells into draining lymph nodes. Oppositely charged but not similarly charged lipopeptides were more effective in DC uptake and trafficking. Very high protein-specific Ab titers were also achieved by vaccination with complexes composed of oppositely charged lipopeptide and protein, whereas vaccination with similarly charged constituents resulted in significant but lower Ab titers. Regardless of whether similarly or oppositely charged lipopeptides were used in the induction of Ab, vaccination generated dominant IgG1 isotype Abs rather than IgG2a.
Anti-CD3 Therapy Promotes Tolerance by Selectively Depleting Pathogenic Cells while Preserving Regulatory T Cells
Authors: Penaranda Cristina , Tang Qizhi , Bluestone Jeffrey A.
Published: July 2011

Monoclonal anti-CD3 Abs have been used clinically for two decades to reverse steroid-resistant acute graft rejection. In autoimmune diabetes, short course treatment with FcR-nonbinding (FNB) anti-CD3 mAb in mice with recent onset of diabetes induces long-term disease remission. Induction of tolerogenic regulatory T cells (Tregs) has been implicated to be one of the mechanisms of action by FNB anti-CD3 mAb in these settings. In this study, we examined the effect of FNB anti-CD3 mAb treatment on the homeostasis of naive, effector, and regulatory T cells in vivo. Anti-CD3 treatment induced a transient systemic rise in the percentage but not absolute number of CD4+Foxp3+ Tregs due to selective depletion of CD4+Foxp3− conventional T cells. T cell depletion induced by FNB anti-CD3 mAb was independent of the proapoptotic proteins Fas, caspase-3, and Bim and was not inhibited by overexpression of the anti-apoptotic protein, Bcl-2. Tregs were not preferentially expanded and we found no evidence of conversion of conventional T cells into Tregs, suggesting that the pre-existing Tregs are resistant to anti-CD3–induced cell death. Interestingly, expression of the transcription factor Helios, which is expressed by thymus-derived natural Tregs, was increased in Tregs after FNB anti-CD3 mAb treatment, suggesting that the anti-CD3 treatment can alter, and potentially stabilize, Treg function. Taken together, the results suggest that FNB anti-CD3 therapy promotes tolerance by restoring the balance between pathogenic and regulatory T cells.
NKT Cells Inhibit Antigen-Specific Effector CD8 T Cell Induction to Skin Viral Proteins
Authors: Mattarollo Stephen R. , Yong Michelle , Gosmann Christina , Choyce Allison , Chan Dora , Leggatt Graham R. , Frazer Ian H.
Published: July 2011

We recently demonstrated that CD1d-restricted NKT cells resident in skin can inhibit CD8 T cell-mediated graft rejection of human papillomavirus E7-expressing skin through an IFN-γ–dependent mechanism. In this study, we examined the role of systemically derived NKT cells in regulating the rejection of skin grafts expressing viral proteins. In lymph nodes draining transplanted skin, Ag-specific CD8 T cell proliferation, cytokine production, and cytotoxic activity were impaired by NKT cells. NKT cell suppression was mediated via CD11c+ dendritic cells. Inhibition of CD8 T cell function did not require Foxp3+ regulatory T cells or NKT cell-secreted IFN-γ, IL-10, or IL-17. Thus, following skin grafting or immunization with human papillomavirus-E7 oncoprotein, NKT cells reduce the capacity of draining lymph node-resident APCs to cross-present Ag to CD8 T cell precursors, as evidenced by impaired expansion and differentiation to Ag-specific CD8 T effector cells. Therefore, in the context of viral Ag challenge in the skin, systemic NKT cells limit the capacity for effective priming of adaptive immunity.
Lung Tumor-Associated Dendritic Cell-Derived Amphiregulin Increased Cancer Progression
Authors: Hsu Ya-Ling , Huang Ming-Shyan , Cheng Da-En , Hung Jen-Yu , Yang Chih-Jen , Chou Shah-Hwa , Kuo Po-Lin
Published: July 2011

The interaction of cancer within a microenvironment is an important factor determining cancer development. This study analyzed the soluble factors secreted by tumor-associated dendritic cells (TADCs), which are responsible for increasing lung cancer growth, migration, invasion, and epithelial-to-mesenchymal transition. Addition of amphiregulin, present in large amounts in TADC-conditioned medium (CM), mimicked the inductive effect of TADC-CM on lung cancer progression, supported by the enhancement of cell proliferation, migration, and invasion as well as osteolytic bone metastases phenotypes. In contrast, neutralization of amphiregulin from TADC-CM decreased the advanced malignancy-inductive properties of TADC-CM. Significant upregulation of amphiregulin has been seen in tumor-infiltrating CD11c+ DCs in human lung cancer samples and patients’ sera. The enhancement of amphiregulin in TADCs has also been noted in mice transplanted with lung cancer cells. Induction of lung cancer progression by TADC-derived amphiregulin is associated with increased STAT3 and AKT activation, which subsequently increases the expression of cyclin D, Twist, and Snail. Blocking AKT significantly decreases TADC-CM and amphiregulin-mediated migration by decreasing the upregulation of Snail, whereas inhibition of STAT3 reduced the modulation of TADC-derived amphiregulin on Twist and cyclin D expression, suggesting that cooperation of STAT3 and AKT plays a critical role in TADC-mediated cancer progression. Moreover, mice treated with anti-amphiregulin Abs showed decreased incidence of cancer development and increased survival rates. Our study suggests that inhibition of amphiregulin or amphiregulin-related signaling is an attractive therapeutic target in lung cancer patients.
Interaction with FcγRIIB Is Critical for the Agonistic Activity of Anti-CD40 Monoclonal Antibody
Authors: White Ann L. , Chan H. T. Claude , Roghanian Ali , French Ruth R. , Mockridge C. Ian , Tutt Alison L. , Dixon Sandra V. , Ajona Daniel , Verbeek J. Sjef , Al-Shamkhani Aymen , Cragg Mark S. , Beers Stephen A. , Glennie Martin J.
Published: July 2011

A high activatory/inhibitory FcγR binding ratio is critical for the activity of mAb such as rituximab and alemtuzumab that attack cancer cells directly and eliminate them by recruiting immune effectors. Optimal FcγR binding profiles of other anti-cancer mAb, such as immunostimulatory mAb that stimulate or block immune receptors, are less clear. In this study, we analyzed the importance of isotype and FcγR interactions in controlling the agonistic activity of the anti-mouse CD40 mAb 3/23. Mouse IgG1 (m1) and IgG2a (m2a) variants of the parental 3/23 (rat IgG2a) were engineered and used to promote humoral and cellular responses against OVA. The mouse IgG1 3/23 was highly agonistic and outperformed the parental Ab when promoting Ab (10–100-fold) and T cell (OTI and OTII) responses (2- to >10-fold). In contrast, m2a was almost completely inactive. Studies in FcγR knockout mice demonstrated a critical role for the inhibitory FcγRIIB in 3/23 activity, whereas activatory FcγR (FcγRI, -III, and -IV) was dispensable. In vitro experiments established that the stimulatory effect of FcγRIIB was mediated through Ab cross-linking delivered in trans between neighboring cells and did not require intracellular signaling. Intriguingly, activatory FcγR provided effective cross-linking of 3/23 m2a in vitro, suggesting the critical role of FcγRIIB in vivo reflects its cellular distribution and bioavailability as much as its affinity for a particular Ab isotype. In conclusion, we demonstrate an essential cross-linking role for the inhibitory FcγRIIB in anti-CD40 immunostimulatory activity and suggest that isotype will be an important issue when optimizing reagents for clinical use.
Repair of Chromosomal RAG-Mediated DNA Breaks by Mutant RAG Proteins Lacking Phosphatidylinositol 3-Like Kinase Consensus Phosphorylation Sites
Authors: Gapud Eric J. , Lee Baeck-Seung , Mahowald Grace K. , Bassing Craig H. , Sleckman Barry P.
Published: July 2011

Ataxia telangiectasia mutated (ATM) and DNA-dependent protein kinase catalytic subunits (DNA-PKcs) are members of the phosphatidylinositol 3-like family of serine/threonine kinases that phosphorylate serines or threonines when positioned adjacent to a glutamine residue (SQ/TQ). Both kinases are activated rapidly by DNA double-strand breaks (DSBs) and regulate the function of proteins involved in DNA damage responses. In developing lymphocytes, DSBs are generated during V(D)J recombination, which is required to assemble the second exon of all Ag receptor genes. This reaction is initiated through a DNA cleavage step by the RAG1 and RAG2 proteins, which together comprise an endonuclease that generates DSBs at the border of two recombining gene segments and their flanking recombination signals. This DNA cleavage step is followed by a joining step, during which pairs of DNA coding and signal ends are ligated to form a coding joint and a signal joint, respectively. ATM and DNA-PKcs are integrally involved in the repair of both signal and coding ends, but the targets of these kinases involved in the repair process have not been fully elucidated. In this regard, the RAG1 and RAG2 proteins, which each have several SQ/TQ motifs, have been implicated in the repair of RAG-mediated DSBs. In this study, we use a previously developed approach for studying chromosomal V(D)J recombination that has been modified to allow for the analysis of RAG1 and RAG2 function. We show that phosphorylation of RAG1 or RAG2 by ATM or DNA-PKcs at SQ/TQ consensus sites is dispensable for the joining step of V(D)J recombination.
The architecture of information in organisations
Authors: Iyamu Tiko
Published: July 2011

Over the last two decades competition amongst organisations including financial institutions has increased tremendously. The value of information is critical to competition in different organisations. In addition, the management of cost of delivery and cohesiveness of information flow and use in the organisations continue a challenge to information technology (IT). In an attempt to address these challenges, many organisations sought various solutions, including enterprise information architecture (EIA). The EIA is intended to address the needs of the organisation for competitive advantage.This research article focused on the role of principles in the development and implementation of EIA. The article aimed to investigate how EIA could be best leveraged, exploited, or otherwise used to provide business value. The research brings about a fresh perspective and new methodological principles required in architecting the enterprise information.
Comparisons of temperature, pressure and humidity measurements by balloon-borne radiosondes and frost point hygrometers during MOHAVE 2009
Authors: Hurst D. F. , Hall E. G. , Jordan A. F. , Miloshevich L. M. , Whiteman D. N. , Leblanc T. , Walsh D. , Vömel H. , Oltmans S. J.
Published: July 2011

Abstract. We compare coincident, balloon-borne, in situ measurements of temperature and pressure by two radiosondes (Vaisala RS92, Intermet iMet-1-RSB) and measurements of relative humidity (RH) by Vaisala RS92 sondes and frost point hygrometers. Data from a total of 28 balloon flights with mixed payloads are analyzed in 1-km altitude bins to quantify measurement biases between sensors and how they vary with altitude. The disparities between sensors determined here are compared to measurement uncertainties quoted by the two radiosonde manufacturers. Our comparisons expose several flight profiles with anomalously large measurement differences. Excluding these anomalous profiles, 33 % of RS92-iMet median temperature differences exceed the uncertainty limits calculated from manufacturer-quoted uncertainties. A statistically significant, altitude-independent bias of about 0.5 ± 0.2 °C is revealed for the RS92-iMet temperature differences. Similarly, 23 % of RS92-iMet median pressure differences exceed the quoted uncertainty limits, with 83 % of these excessive differences above 16 km altitude. The pressure differences are altitude dependent, increasing from −0.6 ± 0.9 hPa at the surface to 0.7 ± 0.1 hPa above 15 km. Temperature and pressure differences between redundant RS92 sondes on the same balloon exceed manufacturer-quoted reproducibility limits 20 % and 2 % of the time, respectively, with most of the excessive differences belonging to anomalous difference profiles. Relative humidity measurements by RS92 sondes are compared to other RS92 sondes and to RH values calculated using frost point hygrometer measurements and coincident radiosonde temperature measurements. For some flights the RH differences are anomalously large, but in general are within the ±5 % RH measurement uncertainty limits quoted for the RS92. The quantitative effects of RS92 and iMet pressure and temperature differences on frost point-based water vapor mixing ratios and RH values, respectively, are also presented.
Technical note: Consistent calculation of aquatic gross production from oxygen triple isotope measurements
Authors: Kaiser J.
Published: July 2011

Abstract. Oxygen triple isotope measurements can be used to calculate aquatic gross oxygen production rates. Past studies have emphasised the appropriate definition of the 17O excess and often used an approximation to derive production rates from the 17O excess. Here, I show that the calculation can be phrased more consistently and without any approximations using the relative 17O/16O and 18O/16O isotope ratio differences (delta values) directly. I call this the "dual delta method". The 17O excess is merely a mathematical construct and the derived production rate is independent of its definition, provided all calculations are performed with a consistent definition. I focus on the mixed layer, but also show how time series of triple isotope measurements below the mixed layer can be used to derive gross production. In the calculation of mixed layer productivity, I explicitly include isotopic fractionation during gas invasion and evasion, which requires the oxygen supersaturation s to be measured as well. I also suggest how bubble injection could be considered in the same mathematical framework. I distinguish between concentration steady state and isotopic steady state and show that only the latter needs to be assumed in the calculation. It is even possible to derive an estimate of the net production rate in the mixed layer that is independent of the assumption of concentration steady state. I review measurements of the parameters required for the calculation of gross production rates and show how their systematic uncertainties as well as the use of different published calculation methods can cause large variations in the production rates for the same underlying isotope ratios. In particular, the 17O excess of dissolved O2 in equilibrium with atmospheric O2 and the 17O excess of photosynthetic O2 need to be re-measured. Because of these uncertainties, all calculation parameters should always be fully documented and the measured relative isotope ratio differences as well as the oxygen supersaturation should be permanently archived, so that improved measurements of the calculation parameters can be used to retrospectively improve production rates.
High nitrate to phosphorus ratio attenuates negative effects of rising pCO2 on net population carbon accumulation
Authors: Krug S. A. , Eggers S. L. , Matthiessen B.
Published: July 2011

Abstract. The ongoing rise in atmospheric pCO2 and the consequent increase in ocean acidification have direct effects on marine calcifying phytoplankton which potentially translates into altered carbon export. To date it remains unclear first, how nutrient ratio, in particular from coccolithophores preferred phosphate limitation, interacts with pCO2 on particulate carbon accumulation. Second, how direct physiological responses on the cellular level translate into a net population response. In this study cultures of Emiliania huxleyi were full-factorially exposed to two different N:P ratios (Redfield and high N:P) and three different pCO2 levels. Effects on net population particulate inorganic and organic carbon (PIC, POC) were measured after E. huxleyi cultures reached stationary phase. Thereby cell sizes and total cell abundance were taken into account. Corresponding to literature results show a significant negative cellular PIC and POC response which, however, was strongest under high N:P ratio. In contrast, net population PIC and POC accumulation was significantly attenuated under high N:P ratio. We suggest that less cellular nutrient accumulation allowed for higher cell abundances which compensated for the strong negative cellular PIC and POC response to pCO2 on the population level. Moreover, the design of this study also allowed following natural alteration of carbon chemistry through changing DIC and alkalinity. Our results suggest that at high initial pCO2 natural alteration of pCO2 during the experimental runtime was regulated by algal biomass. In contrast, at low initial pCO2 the PIC/POC ratio was responsible for changes in pCO2. Our results point to the fact that the physiological (i.e. cellular) PIC and POC response to ocean acidification cannot be linearly extrapolated to total population response and thus carbon export. It is therefore recommended to consider effects of nutrient limitation on cell physiology and translate these to net population carbon accumulation when predicting the influence of coccolithophores on both, the atmospheric pCO2 feedback and their function in carbon export mechanisms.
The impact of land surface temperature on soil moisture anomaly detection from passive microwave observations
Authors: Parinussa R. M. , Holmes T. R. H. , Crow W. T.
Published: July 2011

Abstract. For several years passive microwave observations have been used to retrieve soil moisture from the Earth's surface. Low frequency observations have the most sensitivity to soil moisture, therefore the modern Soil Moisture and Ocean Salinity (SMOS) and future Soil Moisture Active and Passive (SMAP) satellite missions observe the Earth's surface in the L-band frequency. In the past, several satellite sensors such as the Advanced Microwave Scanning Radiometer-EOS (AMSR-E) and Windsat have been used to retrieve surface soil moisture using multi-channel observations obtained at higher microwave frequencies. While AMSR-E and Windsat lack an L-band channel, they are able to leverage multi-channel microwave observations to estimate additional land surface parameters. In particular, the availability of Ka-band observations allows AMSR-E and Windsat to obtain surface temperature estimates required for the retrieval of surface soil moisture. In contrast, SMOS and SMAP carry only a single frequency radiometer. Because of this, ancillary – and potentially less accurate – sources of surface temperature information (e.g. re-analysis data from operational weather prediction centers) must be sought to produce surface soil moisture retrievals. Here, two newly-developed, large-scale soil moisture evaluation techniques, the triple collocation (TC) approach and the R value data assimilation approach, are applied to quantify the global-scale impact of replacing Ka-band based surface temperature retrievals with Modern Era Retrospective-analysis for Research and Applications (MERRA) surface temperature predictions on the accuracy of Windsat and AMSR-E surface soil moisture retrievals. Results demonstrate that under sparsely vegetated conditions, the use of Ka-band radiometric land surface temperature leads to better soil moisture anomaly estimates compared to those retrieved using MERRA land surface temperature predictions. However the situation is reversed for highly vegetated conditions where soil moisture anomaly estimates retrieved using MERRA land surface temperature are superior. In addition, the surface temperature phase shifting approach is shown to generally enhance the value of MERRA surface temperature estimates for soil moisture retrieval. Finally, a high degree of consistency is noted between evaluation results produced by the TC and Rvalue soil moisture verification approaches.
Association of peptic ulcer disease and pulmonary disease with risk of periprosthetic fracture after primary total knee arthroplasty
Authors: Singh Jasvinder A. , Lewallen David G.
Published: July 2011

Objective

To assess the association of specific comorbidities with periprosthetic fractures after primary total knee replacement (TKR).

Methods

We used the prospectively collected data in the Mayo Clinic total joint registry from 1989–2008 on all patients who had undergone primary TKR. The outcome of interest was postoperative periprosthetic fractures during followup. The main predictors of interest were comorbidities grouped from the validated Deyo‐Charlson index. Multivariable‐adjusted Cox regression analyses were adjusted for sex, age, body mass index (BMI), American Society of Anesthesiology (ASA) class, operative diagnosis, and implant fixation. Hazard ratios (HRs) and 95% confidence intervals (95% CIs) were calculated.

Results

We included 17,633 primary TKRs with a mean followup of 6.3 years. The mean age was 68 years, 55% were women, and the mean BMI was 31 kg/m2. There were 188 postoperative periprosthetic fractures on postoperative day 1 or later; 162 fractures (86%) occurred on postoperative day 90 or later. In multivariable analyses that simultaneously adjusted for all comorbidities and other variables (age, sex, BMI, ASA, operative diagnosis, and cement status), the following 2 conditions were significantly associated with an increased hazard of postoperative periprosthetic fractures: peptic ulcer disease (HR 1.87, 95% CI 1.28–2.75; P = 0.0014) and chronic obstructive pulmonary disease (HR 1.62, 95% CI 1.10–2.40; P = 0.02).

Conclusion

Peptic ulcer disease and chronic obstructive pulmonary disease are associated with a higher risk of periprosthetic fractures after primary TKR. This may be related to the disease or its treatments, which need further study. Identification of specific risk factors may allow for implementation of intervention strategies to reduce this risk.
Changes in cotherapies after initiation of disease‐modifying antirheumatic drug therapy in patients with rheumatoid arthritis
Authors: Kawai Vivian K. , Grijalva Carlos G. , Arbogast Patrick G. , Curtis Jeffrey R. , Solomon Daniel H. , Delzell Elizabeth , Chen Lang , Ouellet‐Hellstrom Rita , Herrinton Lisa , Liu Liyan , Mitchel Edward F. , Stein C. Michael , Griffin Marie R.
Published: July 2011

Objective

We hypothesized that initiation of a new disease‐modifying antirheumatic drug (DMARD) for treatment of rheumatoid arthritis (RA) would decrease the use of corticosteroids, nonsteroidal antiinflammatory drugs (NSAIDs), and narcotics.

Methods

Using administrative databases, we assembled 4 retrospective cohorts of RA patients (1998–2005) and identified 5 groups initiating DMARD regimens: methotrexate (MTX) with (new MTX) or without (first MTX) use of other nonbiologic DMARDs in the previous year; new hydroxychloroquine (HCQ) and/or sulfasalazine (SSZ; new HCQ/SSZ) and new leflunomide (new LEF), both with previous use of MTX; and new tumor necrosis factor α (TNFα) antagonists (new anti‐TNF). We compared within‐person differences in any use of cotherapies (≥1 prescription) between the 6 months before and the 6–12 months after DMARD initiation.

Results

Among 32,476 DMARD initiators, the prevalence of corticosteroid, NSAID, and narcotic use increased by 15%, 5%, and 6%, respectively, in the 6 months before initiation compared to the previous 6 months, suggesting worsening of the disease. In the 6–12 months after initiation for most initiator groups, more patients stopped using corticosteroids and NSAIDs than started, with overall decreases of 8.9% (95% confidence interval [95% CI] 8.4–9.4%) for corticosteroids and 12.9% (95% CI 12.3–13.4%) for NSAIDs. The proportion of narcotic users changed little (overall decrease of 2.5%; 95% CI 1.9–3.0%).

Conclusion

Use of all 3 cotherapies increased in the 6 months before initiation of new DMARD regimens for RA. Use of corticosteroids and NSAIDs decreased modestly 6–12 months after initiation, but there was only a very small decrease in narcotic use. These differential changes require further study.
Structural and Material Design of Open‐Cell Powder Metallurgical Foams
Authors: Quadbeck Peter , Kümmel Kerstin , Hauser Ralf , Standke Gisela , Adler Jörg , Stephani Günter , Kieback Bernd
Published: July 2011

High porosity permeable materials have been manufactured on the basis of the highly uniform structure of foamed polyurethane since the 1950 s. This paper shows the development of open cell foams based on all kinds of steels, titanium alloys, and also open‐cell molybdenum foams made by a powder metallurgical replication technique. Such materials show a wide range of physical and mechanical properties, which may be adapted to various requirements. The automotive industry, for example, needs high‐temperature resistant materials with high permeability and good strength for catalytic conversion. For orthopaedic implants, the network‐like metal foams made of titanium, tantalum, or steel exhibit a bone‐like structure. The powder metallurgical replication route represents an economic method to process open‐cell metal foams with a unique combination of properties for a wide range of applications.
Highly Reproducible Surface‐Enhanced Raman Scattering on a Capillarity‐Assisted Gold Nanoparticle Assembly
Authors: Que Ronghui , Shao Mingwang , Zhuo Shujuan , Wen Chunye , Wang Suidong , Lee Shuit‐Tong
Published: July 2011

A facile method based on capillarity‐assisted assembly is used to fabricate high‐performance surface‐enhanced Raman scattering (SERS) substrates employing clean Au nanoparticles (NPs). This method is better than micro‐channel way because the former may supply large‐area uniform assembly and overcome the uneven radial distribution. Such densely‐arranged assembly of Au NPs exhibits high reproducibility and large Raman enhancement factors of 3 × 1010, arising from strong electromagnetic field coupling induced by adjacent Au NPs. The spot‐to‐spot SERS signals show that the relative standard deviation (RSD) in the intensity of the main Raman vibration modes (1310, 1361, 1509, 1650 cm−1) of Rhodamine 6G at a concentration of 1 × 10−10 M are consistently less than 20%, demonstrating good spatial uniformity and reproducibility. The SERS signals of sudan dye at a 1 × 10−8 M concentration also shows high reproducibility with a low RSD of <20%. Further, the assembly substrate is stable, retaining excellent uniformity and sensitivity after storage for months. This assembly strategy integrating the advantages of low‐cost production, high sensitivity, and reproducibility would significantly facilitate practical SERS detection.
Hierarchical Superhydrophobic Surfaces Fabricated by Dual‐Scale Electron‐Beam‐Lithography with Well‐Ordered Secondary Nanostructures
Authors: Feng Jiansheng , Tuominen Mark T. , Rothstein Jonathan P.
Published: July 2011

Recent studies on superhydrophobic surfaces have revealed the important roles of structural hierarchy in the overall properties of these surfaces. Here, a novel, versatile, and efficient technique is introduced for fabricating macroscopic hierarchical superhydrophobic surfaces with both well‐defined primary microstructures and well‐ordered secondary nanostructures using electron‐beam lithography. With this technique, the engineering capability of controlling the size, shape, and distribution of the secondary‐features is demonstrated, which allows a systematic and quantitative study of the individual effects of these parameters. Superhydrophobic surfaces produced by this new technique exhibit two distinctive wetting behaviors, high and low adhesion. The structural characteristics and structure‐property relations of each of those two regimes are discussed.
Evolution of Nanoporous Pt–Fe Alloy Nanowires by Dealloying and their Catalytic Property for Oxygen Reduction Reaction
Authors: Shui Jiang‐lan , Chen Chen , Li James C. M.
Published: July 2011

The short life and high cost of carbon‐supported Pt nanoparticle catalysts (Pt/C) are two main problems with proton exchange membrane fuel cells. Porous Pt alloy nanowires have more durability and catalytic activity than Pt/C. Dealloying is a facile way to make nanoporous Pt. However, the process of porosity formation is difficult to control. In this paper, electrospinning and chemical dealloying techniques are used to make long, thin and yet nanoporous Pt–Fe alloy nanowires. The evolution of nanoporosity is observed and studied. It is found that non‐uniform composition in the precursor PtFe5 alloy nanowires helps the formation of nanoporous structure. The overall wire diameter is about 10–20 nm and the ligament diameter only 2–3 nm. These porous long nanowires interweave to form a self‐supporting network with a high specific activity, 2.3 times that of conventional Pt/C catalysts, and also have better durability.
Is Poly(vinylcarbazole) a Good Host for Blue Phosphorescent Dopants in PLEDs? Dimer Formation and Their Effects on the Triplet Energy Level of Poly(N‐vinylcarbazole) and Poly(N‐Ethyl‐2‐Vinylcarbazole)
Authors: Jankus Vygintas , Monkman Andrew P
Published: July 2011

The detailed measurement and analysis of the delayed emission from poly(vinylcarbazole) (PVK) and poly(N‐ethyl‐2‐vinyl‐carbazole) (P2VK) thin films is described. PVK has rapidly become a “polymer of choice” for hosting phosphorescent dopants in PLEDs, especially blue emitters. In this respect it is important to have a full understanding of the triplet properties of this host. It is concluded that in films, the electronic 0–0 peak energy of PVK phosphorescence is found at 2.88 eV (14 K). With an increase of temperature, >44 K, increasing emission from new long lived, lower energy species, previously ascribed to “trap states” in the literature, is observed. Increasing temperature enables thermally assisted triplet exciton hopping to these trap states. Critically it is shown that some of these triplet trap species are ground state triplet dimers in origin for both PVK (2.46 eV) and P2VK (2.1 eV), and not all of them are of excimer nature as previously thought. These species can quench the emission of blue heavy metal complexes doped in PVK and drastically effect performance over lifetime if the dimer formation increases over time and at elevated operating temperature. It is therefore concluded that PVK might not be such an ideal host material for blue phosphorescent emitters.
Artificial Cilia: Generation of Magnetic Actuators in Microfluidic Systems
Authors: Belardi Jacob , Schorr Nicolas , Prucker Oswald , Rühe Jürgen
Published: July 2011

Magnetic artificial cilia are fabricated from photoreactive copolymer precursors filled with magnetic nanoparticles by a new photolithographic process. Two different crosslinkers and UV‐radiation of two different wavelengths are used to generate arrays of planar magnetically actuatable rubber flaps. The cilia are integrated into a microfluidic channel and operated in water using a rotating permanent magnet.
Female marmosets' behavioral and hormonal responses to unfamiliar intruders
Authors: Ross Corinna N. , French Jeffrey A.
Published: July 2011

The endocrine control mechanisms for female mammalian aggression have been largely unstudied. Although it has been proposed that androgens may modulate female aggressive behavior in a similar manner to males, very little conclusive evidence exists. Previous work in male marmosets found that post‐encounter increases in testosterone (T) were dependent on the intensity of aggression displayed during the aggressive encounter. We exposed female marmosets (Callithrix kuhlii), a monogamous and biparental primate, to aggressive interactions with unfamiliar intruders. Individual female marmosets exhibited changes in T and estradiol (E2) that are associated with aggressiveness dependent on the intensity of aggression displayed as well as their role during the encounter. Resident females exhibited increased E2 immediately following an encounter in which they displayed high rates of aggression. If resident females received high rates of aggression from the intruder, the resident displayed increased T 24 hr following the encounter. Interestingly, if the female was an intruder in the encounter, the intensity of her aggression was associated with increased cortisol immediately following the trials, whereas received aggression was associated with increased T and E2 immediately following the trial. Female primates do exhibit situation‐dependent changes in gonadal steroids in association with aggression that may serve to prime them for future aggressive interactions. Am. J. Primatol. 73:1072–1081, 2011. © 2011 Wiley‐Liss, Inc.
Tosylhydrazone – neue Anwendungen klassischer Reagentien in palladiumkatalysierten Kreuzkupplungen und metallfreien Umsetzungen
Authors: Barluenga José , Valdés Carlos
Published: July 2011

Tosylhydrazone sind wertvolle Zwischenverbindungen, die in der organischen Chemie seit fast 60 Jahren Anwendung finden. Die jüngste Entdeckung einer palladiumkatalysierten Kreuzkupplungsreaktion unter Beteiligung eines Tosylhydrazon‐Kupplungspartners weckte ein neues Interesse an diesen Reagentien. Die Reaktion ist nahezu universell für Hydrazone und kann zur Synthese polysubstituierter Alkene genutzt werden. Im Verlauf dieser Forschungen wurden außerdem neue metallfreie C‐C‐ und C‐O‐Kupplungen gefunden. Da Tosylhydrazone leicht aus Carbonylverbindungen zugänglich sind, bieten diese Umwandlungen neue Möglichkeiten für die Derivatisierung von Carbonylverbindungen. Dieser Kurzaufsatz behandelt diese neuartigen Reaktionen dieses klassischen Reagens.
Wasserspaltung mit Cobalt
Authors: Artero Vincent , Chavarot‐Kerlidou Murielle , Fontecave Marc
Published: July 2011

Die Energieversorgung der Zukunft kann nur durch grundlegende Neuerungen auf dem Gebiet billiger, nachhaltiger und effizienter Systeme zur Gewinnung und Speicherung von Energie aus erneuerbaren Quellen oder aus Sonnenlicht gesichert werden. Die Erzeugung von Wasserstoff, einem Brennstoff mit bemerkenswerten Eigenschaften, durch die Wasserspaltung mithilfe von Sonnenlicht ist in diesem Zusammenhang ein vielversprechender Ansatz. Während die aktiven Zentren von wasserspaltenden Enzymen – wie Hydrogenasen und Photosystem II – Eisen‐, Nickel‐ und Manganionen enthalten, hat sich Cobalt in den vergangenen fünf Jahren als vielseitigstes unedles Metall bei der Entwicklung synthetischer Katalysatoren zur H2‐ und O2‐Erzeugung durch Reduktion bzw. Oxidation von Wasser bewährt. Solche Katalysatoren lassen sich mit Photosensibilisatoren zu Systemen für die photokatalytische Wasserstofferzeugung aus Wasser koppeln.
Tosylhydrazones: New Uses for Classic Reagents in Palladium‐Catalyzed Cross‐Coupling and Metal‐Free Reactions
Authors: Barluenga José , Valdés Carlos
Published: July 2011

Tosylhydrazones are useful synthetic intermediates that have been used in organic chemistry for almost 60 years. The recent discovery of a palladium‐catalyzed cross‐coupling reaction involving a tosylhydrazone coupling partner has triggered renewed interest in these reagents. This reaction shows nearly universal generality with regard to the hydrazone and can be employed for the preparation of polysubstituted alkenes. In the course of this research, novel metal‐free CC and CO bond‐forming reactions have been discovered. Since tosylhydrazones are readily prepared from carbonyl compounds, these transformations offer new synthetic opportunities for the unconventional modification of carbonyl compounds. This Minireview discusses all of these new reactions of a classic reagent.
Volatiles from the Maillard reaction of L‐ascorbic acid with L‐glutamic acid/L‐aspartic acid at different reaction times and temperatures
Authors: Tan Zhi‐Wei , Yu Ai‐Nong
Published: July 2011

The formation of pyrazines in the Maillard reaction of L‐ascorbic acid (ASA) with L‐glutamic acid (Glu)/L‐aspartic acid (Asp) is influenced by reaction temperature and reaction time. Our studies indicate that pyrazines are not formed in both model systems until the reaction temperature reaches 120 °C. The model systems involving ASA and Glu show increased formation of 2,5‐dimethylpyrazine and 2‐ethyl‐3‐methylpyrazine with increasing temperature and an increased formation of 2‐ethyl‐3‐methylpyrazine with reaction time. In model systems where ASA reacted with Asp, the formation of 3‐ethyl‐2,5‐dimethylpyrazine and 3,5‐diethyl‐2‐methyl‐pyrazine increased with increasing temperature and the formation of 3‐ethyl‐2,5‐dimethylpyrazine, 3,5‐diethyl‐2‐methylpyrazine, and 2‐ethyl‐6‐methylpyrazine increased with reaction time. These results provide information on potential mechanisms in the formation of pyrazine compounds and could provide guidelines in the thermal processing of foods containing ASA. Copyright © 2011 Curtin University of Technology and John Wiley & Sons, Ltd.
Smoking, body weight, physical exercise, and risk of lower limb total joint replacement in a population‐based cohort of men
Authors: Mnatzaganian George , Ryan Philip , Norman Paul E. , Davidson David C. , Hiller Janet E.
Published: July 2011

Objective

To assess the associations of smoking, body weight, and physical activity with risk of undergoing total joint replacement (TJR) in a population‐based cohort of men.

Methods

A cohort study of 11,388 men that integrated clinical data with hospital morbidity data and mortality records was undertaken. The risk of undergoing TJR was modeled on baseline weight, height, comorbidity, socioeconomic status, years of smoking, and exercise in 3 separate age groups, using Cox proportional hazards regressions and competing risk regressions (CRRs).

Results

Dose‐response relationships between weight and risk of TJR and between smoking and risk of TJR were observed. Being overweight independently increased the risk of TJR, while smoking lowered the risk. The decreased risk among smokers was demonstrated in both Cox and CRR models and became apparent after 23 years of exposure. Men who were in the highest quartile (≥48 years of smoking) were 42–51% less likely to undergo TJR than men who had never smoked. Tests for trend in the log hazard ratios (HRs) across both smoking and weight quantiles yielded significant P values. Vigorous exercise increased the hazard of TJR; however, the association reached statistical significance only in the 70–74‐year‐old age group (adjusted HR 1.64 [95% confidence interval 1.19–2.24]). Adjusting for Deyo‐Charlson Index or Elixhauser's comorbidity measures did not eliminate these associations.

Conclusion

Our findings indicate that being overweight and reporting vigorous physical activity increase the risk of TJR. This study is the first to demonstrate a strong inverse dose‐response relationship between duration of smoking and risk of TJR. More research is needed to better understand the role of smoking in the pathogenesis of osteoarthritis.
Tetraphenylethylene‐based Glycoconjugate as a Fluorescence “Turn‐On” Sensor for Cholera Toxin
Authors: Hu Xin‐Ming , Chen Qi , Wang Jin‐Xiang , Cheng Qian‐Yi , Yan Chao‐Guo , Cao Jie , He Yu‐Jian , Han Bao‐Hang
Published: July 2011

Tetraphenylethylene (TPE)‐based glycoconjugates were easily synthesized by copper(I)‐catalyzed “click reactions” between propargyl‐attached TPE and azido‐functionalized sugars. The TPE compound bearing lactosyl moieties (Lac‐TPE) was found to be a fluorescence “turn‐on” sensor for cholera toxin by virtue of aggregation‐induced emission characteristics of the TPE motif owing to the specific interaction of lactose with the cholera toxin B subunit, whilst a cellobiose‐functionalized TPE derivative did not show any response to the toxin. Therefore, Lac‐TPE shows promising applications in the detection of cholera toxin, as well as in the investigation of carbohydrate–protein interaction.
Into the deep: New discoveries at the base of the green plant phylogeny
Authors: Leliaert Frederik , Verbruggen Heroen , Zechman Frederick W.
Published: July 2011

Recent data have provided evidence for an unrecognised ancient lineage of green plants that persists in marine deep‐water environments. The green plants are a major group of photosynthetic eukaryotes that have played a prominent role in the global ecosystem for millions of years. A schism early in their evolution gave rise to two major lineages, one of which diversified in the world's oceans and gave rise to a large diversity of marine and freshwater green algae (Chlorophyta) while the other gave rise to a diverse array of freshwater green algae and the land plants (Streptophyta). It is generally believed that the earliest‐diverging Chlorophyta were motile planktonic unicellular organisms, but the discovery of an ancient group of deep‐water seaweeds has challenged our understanding of the basal branches of the green plant phylogeny. In this review, we discuss current insights into the origin and diversification of the green plant lineage.
Empowering plant evo‐devo: Virus induced gene silencing validates new and emerging model systems
Authors: Di Stilio Verónica S.
Published: July 2011

It is increasingly recognized that current established model systems are not sufficient to understand the evolution of biodiversity. The main limitation in developing additional model systems is the difficulty or inability to perform functional studies of target genes. Evolutionary developmental (evo‐devo) biologists have adopted a transient transgenic technique, developed over the last decade for agricultural applications, which is allowing functional studies in the most disparate plant lineages. From monocots to dicots and from herbs to trees, virus‐induced gene silencing (VIGS) has opened up a world of opportunities in plant evo‐devo.
Determination of 5‐hydroxytryptamine in serum by electrochemiluminescence detection with the aid of capillary electrophoresis
Authors: Hu Yuefang , Xu Wei , Li Jianping , Li Lanjuan
Published: July 2011

A rapid, sensitive and simple electrochemiluminescence method for the determination of 5‐hydroxytryptamine (5‐HT) using capillary electrophoresis was proposed. The experimental parameters, including the detection potential, the concentration of Ru(bpy)32+, the concentration and pH of phosphate buffer for separation and detection, the injection voltage and time and the separation voltage on the determination of 5‐HT, were optimized. Under the optimized conditions, the linear concentration range for 5‐HT was 3.5 × 10‐9–5.1 × 10‐3 mol/L, with a detection limit of 5 × 10‐10 mol/L. The relative standard deviations (RSDs) of the ECL intensity and the migration times for six continuous injections of 1.0 µmol/L 5‐HT were 2.48% and 1.3%, respectively. The method was successfully applied to 5‐HT assay in samples of human serum in 5 min and the extraction recoveries with spiked serum samples were over 94.4%. Copyright © 2011 John Wiley & Sons, Ltd.
Engineered Thermobifida fusca cutinase with increased activity on polyester substrates
Authors: Silva Carla , Da Shi , Silva Nádia , Matamá Teresa , Araújo Rita , Martins Madalena , Chen Sheng , Chen Jian , Wu Jing , Casal Margarida , Cavaco‐Paulo Artur
Published: July 2011

A bacterial cutinase from Thermobifida fusca, named Tfu_0883, was genetically modified by site‐directed mutagenesis to enhance its activity on poly(ethylene terephthalate) (PET). The new mutations tailored the catalytic site for PET, increasing the affinity of cutinase to this hydrophobic substrate and the ability to hydrolyze it. The mutation I218A was designed to create space and the double mutation Q132A/T101A was designed both to create space and to increase hydrophobicity. The activity of the double mutant on the soluble substrate p‐nitrophenyl butyrate increased two‐fold compared to wild‐type cutinase, while on PET both single and double mutants exhibited considerably higher hydrolysis efficiency. The replacement of specific amino acids at the active site was an effective approach for the improvement of the Tfu_0883 cutinase capacity to hydrolyze polyester surfaces. Thus, this study provides valuable insight on how the function and stability of enzymes can be improved by molecular engineering for their application in synthetic fiber biotransformation.