bluuebunny/crossref_metadata_2025 huggingface dataset:
Etching and recovery of gold from aluminum substrate in thiourea solution
Authors: Jindra Tomáš , Prokop Zdeněk , Šnita Dalimil
Published: December 2011

This paper deals with two (main) problems of specific gold etching from parts of industrial equipment (e.g., supporting inserts into chambers for physical or chemical vapor deposition). First part of the paper is focused on selective etching of gold from aluminum substrates. Selectivity of the reaction, i.e. leaving substrates intact, is crucial. For this reason, the environmentally friendly and safe method of etching gold in a thiourea solution was tested. This method, while well described in literature, does not preserve various substrates (e.g., aluminum, stainless steel). The main goal of this part of the paper was to understand the mechanism of the reaction and to improve the reaction selectivity towards the aluminum alloy substrate. Thus, different acidifying agents were tested. Second part of the paper is focused on recovery (reduction) of gold from thiourea solutions. Chemical, electrochemical, and biological reduction were tested for gold recovery.
Oxidation of 3,5-di-tert-butylcatechol in the presence of V-polyoxometalate
Authors: Hu Xue-Feng , Wu Lei
Published: December 2011

The oxidase and dioxygenase reactions of 3,5-di-tert-butylcatechol (DTBC, I) in the presence of V-polyoxometalate were studied. It was found that the addition of a Lewis base quenched the V-polyoxometalate-catalysed catechol dioxygenase reaction and catalysed the oxidase reaction selectively. The existence of V-polyoxometalate accelerates the autoxidation rate of I as demonstrated by the rate measurements. ESR and UV-VIS spectra showed that the Lewis base destroyed the dioxygenation reaction catalyst as formed and restrained its regeneration by suppressing the coordination of catechol radical to vanadium. The by-products of the dioxygenation and oxidation reactions are H2O and H2O2, respectively.
What do thermonuclear bombs have to do with intercultural hermeneutics? (Or on the superiority of Dickens over Heidegger)
Authors: Małecki Wojciech
Published: December 2011

In this paper, I discuss Richard Rorty’s views on intercultural hermeneutics as presented in his essay “Heidegger, Kundera, and Dickens” and in his correspondence with the Indian philosopher Anindita Niyogi Balslev. In doing so, I focus primarily on Rorty’s presumption that instead of providing an “authentic” picture of another culture, the goal of intercultural studies or hermeneutics should be to look if there is anything “of use” that a given culture offers and that is not offered by ours.
Possible application of deliberative democracy in parliament
Authors: Dolný Branislav
Published: December 2011

Deliberative democracy, as a dominant paradigm in contemporary democratic theory, offers a new, attractive conception of democratic legitimacy, which represents an alternative to a democracy that functions through the mechanism of political competition. A major problem with deliberation is the issue of its institutionalisation, as the theories of deliberative democracy have not produced a more specific institutional framework or form in which it could be used in political practice. Parliaments appear to be particularly suitable places for its potential implementation. Moreover, deliberative democracy could contribute to a change in discourse quality and the way decision-making is conducted in parliaments, which is often considered problematic. Due to its incompatibility with competitive democracy, the opportunities for introducing deliberative democracy into parliaments are very limited. The study also outlines three ways of reconciling deliberative democracy and parliaments.
The pragmatist conception of altruism and reciprocity
Authors: Višňovský Emil
Published: December 2011

The paper provides an account of the pragmatist philosophical conception of reciprocity and altruism based on the ontology of “panrelationalism”. The Deweyan concepts of transaction and cooperation are also outlined in some detail as well as the pragmatist (Rortyan) idea of justice. The author attempts to show that altruism is not necessarily just reciprocal but demands as its supplement (at least) altruism without reciprocation.
Proposing new approaches for dating young volcanic eruptions by luminescence methods
Authors: Rufer Daniel , Gnos Edwin , Mettier Ralph , Preusser Frank , Schreurs Guido
Published: December 2011

The application of luminescence dating to young volcanic sediments has been first investigated over three decades ago, but it was only with the technical innovations of the last decade that such analyses became viable. While current analytical procedures show promise for dating late Quaternary volcanic events, most efforts have been aimed at unconsolidated volcanic tephra. Investigations into direct dating of lava flows or of non-heated volcanoclastics like phreatic explosion layers, however, remain scarce. These volcanic deposits are of common occurrence and represent important chrono- and volcanostratigraphic markers. Their age determination is therefore of great importance in volcanologic, tectonic, geomorphological and climate studies. In this article, we propose the use of phreatic explosion deposits and xenolithic inclusions in lava flows as target materials for luminescence dating applications. The main focus is on the crucial criterion whether it is probable that such materials experience complete luminescence signal resetting during the volcanic event to be dated. This is argued based on the findings from existing literature, model calculations and laboratory tests.
New exposure of loess deposits in Boyanychi (Ukraine) — Results of thermoluminescence analyses
Authors: Kusiak Jarosław , Łanczont Maria , Bogucki Andrij
Published: December 2011

The loess site at Boynychi (the Volyn Upland) is of essential importance for the stratigraphy of Middle and Upper Pleistocene in Central Europe. The profile was recently dated by Fedorowicz and Prylypko in 2007 (parallel dating), and by Kusiak in 2009. The Upper Vistulian loesses are much thicker in the exposure from 2009 than in the earlier examined one (2007). The list of results obtained in the Gdańsk, Kiev and Lublin laboratories, respectively, can be divided in two. The first group contains the results obtained for the Horohiv and Korshiv pedocomplexes and for the loess from the penultimate glacial, which separates these pedocomplexes. The results from all laboratories are very similar and rather well describe the real age of dated deposits. The second group contains the widely differing results of dating of the Vistulian loesses. The TL ages obtained by Fedorowicz and Prylypko are considerably older than those obtained by Kusiak in the new exposure. The latter ones excellently correspond to the geologic-stratigraphic interpretation of the profile. Two incompatible series of TL dating results indicate that local variability of loess accumulation conditions in different stages of their formation may have resulted in incomplete luminescence zeroing of mineral material before deposition.
Field gamma spectrometry, Monte Carlo simulations and potential of non-invasive measurements
Authors: Guérin Guillaume , Mercier Norbert
Published: December 2011

The determination of gamma dose rates is of prior importance in the field of luminescence dating methods. In situ measurements are usually performed by the insertion of dosimeters or a portable gamma spectrometer cell in sediments. In this paper, Monte-Carlo simulations using the Geant4 toolkit allow the development of a new technique of insitu gamma dose rate evaluations: a spectrometer cell is placed on the surface of sediments under excavation to acquire successive spectra as sediments are removed by excavations. The principle of this non-invasive technique is outlined and its potential is discussed, especially in the case of environments in which radioelements are heterogeneously distributed. For such cases, a simple method to reconstruct gamma dose rate values with surface measurements using an attenuator is discussed, and an estimation of errors is given for two simple cases. This technique appears to be applicable, but still needs experimental validation.
Dendrochronological and radiocarbon dating of the medieval stronghold in Ujście (Poland)
Authors: Bolka Monika , Krąpiec Marek
Published: December 2011

In 2008, the archaeological museum in Piła carried out excavations in the site No. 5 in Ujście upon the river Noteć (Poland), at the Rybacka Street and in the Old Market Square. In 12 archaeological excavations and 4 surveys abundant wooden structures were discovered, from which about 800 samples were taken, mainly of pine (Pinus sylvestris L.) and oakwood (Quercus sp.). The studies were aimed at absolute dating of wood with the dendrochronological method, the wiggle matching fitting curves method, as well as anatomical determination of wood. Absolute dating of the oakwood from the Rybacka Street allowed to distinguish the oldest fortifications of the stronghold from the ninth century, and also intensive introduction of wood in the years 980–1080 AD, whereas analysis of wood from the Old Market (survey IV) allowed to distinguish eight structural levels, from the 1530s until the 970s. On the basis of the pine wood 227-year-long local chronology 2U_02A was produced, dated with the wiggle-matching method for the period 860–1080 (±10) cal. AD. Most of the pine samples proved to represent wood introduced in the 990s and 1040s (±10) cal. AD, and also some repairs in the years 1000–1030 and 1050–1070 (±10) cal. AD.
Stages of development in the Polish Carpathian Foredeep basin
Authors: Oszczypko Nestor , Oszczypko-Clowes Marta
Published: December 2011

In southern Poland, Miocene deposits have been recognised both in the Outer Carpathians and the Carpathian Foredeep (PCF). In the Outer Carpathians, the Early Miocene deposits represent the youngest part of the flysch sequence, while in the Polish Carpathian Foredeep they are developed on the basement platform. The inner foredeep (beneath the Carpathians) is composed of Early to Middle Miocene deposits, while the outer foredeep is filled up with the Middle Miocene (Badenian and Sarmatian) strata, up to 3,000mthick. The Early Miocene strata are mainly terrestrial in origin, whereas the Badenian and Sarmatian strata are marine. The Carpathian Foredeep developed as a peripheral foreland basin related to the moving Carpathian front. The main episodes of intensive subsidence in the PCF correspond to the period of progressive emplacement of the Western Carpathians onto the foreland plate. The important driving force of tectonic subsidence was the emplacement of the nappe load related to subduction roll-back. During that time the loading effect of the thickening of the Carpathian accretionary wedge on the foreland plate increased and was followed by progressive acceleration of total subsidence. The mean rate of the Carpathian overthrusting, and north to north-east migration of the axes of depocentres reached 12 mm/yr at that time. During the Late Badenian-Sarmatian, the rate of advance of the Carpathian accretionary wedge was lower than that of pinch-out migration and, as a result, the basin widened. The Miocene convergence of the Carpathian wedge resulted in the migration of depocentres and onlap of successively younger deposits onto the foreland plate.
Comments to X. Li and Y. M. Wang (2011) Comparisons of geoid models over Alaska computed with different Stokes' kernel modifications, JGS 1(2): 136-142
Authors: Sjöberg L.
Published: December 2011

Comments to X. Li and Y. M. Wang (2011) Comparisons of geoid models over Alaska computed with different Stokes' kernel modifications, JGS 1(2): 136-142

Li and Wang recently compared geoid determination by various gravimetric methods for modifying Stokes' formula vs. using GPS/levelling geoid heights as a reference model. Possible large systematic errors in the differences of gravimetric and GPS/levelling geoid models deteriorate the results and conclusions. Moreover, spectral combination, the only stochastic method in the study, was applied in an unrealistic way.
Diverse Schools in a Democratic Society
Authors: Jacobsen Rebecca , Frankenberg Erica , Lenhoff Sarah Winchell
Published: December 2011

The 2010 Census revealed the extent to which today’s metropolitan areas are growing increasingly diverse. At the forefront of this change are schools. Yet, research on school context continues to rely upon a traditional, cross-sectional bifurcation that designates schools as either diverse or not. This classification may be especially inaccurate for some educational outcomes such as whether schools are cultivating effective citizenship for a diverse democracy. Because of changing demographics, this paper considers whether a new framework for conceptualizing school racial composition, including the number and identity of specific racial groups and the stability of those groups, can determine more precisely the ways in which school diversity impacts students’ citizenship learning.
Pathogenic Natural Antibodies Propagate Cerebral Injury Following Ischemic Stroke in Mice
Authors: Elvington Andrew , Atkinson Carl , Kulik Liudmila , Zhu Hong , Yu Jin , Kindy Mark S. , Holers V. Michael , Tomlinson Stephen
Published: December 2011

Self-reactive natural Abs initiate injury following ischemia and reperfusion of certain tissues, but their role in ischemic stroke is unknown. We investigated neoepitope expression in the postischemic brain and the role of natural Abs in recognizing these epitopes and mediating complement-dependent injury. A novel IgM mAb recognizing a subset of phospholipids (C2) and a previously characterized anti-annexin IV mAb (B4) were used to reconstitute and characterize injury in Ab-deficient Rag1−/− mice after 60 min of middle cerebral artery occlusion and reperfusion. Reconstitution with C2 or B4 mAb in otherwise protected Rag1−/− mice restored injury to that seen in wild-type (wt) mice, as demonstrated by infarct volume, demyelination, and neurologic scoring. IgM deposition was demonstrated in both wt mice and reconstituted Rag1−/− mice, and IgM colocalized with the complement activation fragment C3d following B4 mAb reconstitution. Further, recombinant annexin IV significantly reduced infarct volumes in wt mice and in Rag1−/− mice administered normal mouse serum, demonstrating that a single Ab reactivity is sufficient to develop cerebral ischemia reperfusion injury in the context of an entire natural Ab repertoire. Finally, C2 and B4 mAbs bound to hypoxic, but not normoxic, human endothelial cells in vitro. Thus, the binding of pathogenic natural IgM to postischemic neoepitopes initiates complement-dependent injury following murine cerebral ischemia and reperfusion, and, based also on previous data investigating IgM reactivity in human serum, there appears to be a similar recognition system in both mouse and man.
Importance of Antibody in Virus Infection and Vaccine-Mediated Protection by a Latency-Deficient Recombinant Murine γ-Herpesvirus-68
Authors: Freeman Michael L. , Burkum Claire E. , Woodland David L. , Sun Ren , Wu Ting-Ting , Blackman Marcia A.
Published: December 2011

The human γ-herpesviruses EBV and Kaposi’s sarcoma-associated herpesvirus establish lifelong latent infections, can reactivate in immunocompromised individuals, and are associated with the development of malignancies. Murine γ-herpesvirus-68 (γHV68), a rodent pathogen related to EBV and Kaposi’s sarcoma-associated herpesvirus, provides an important model to dissect mechanisms of immune control and investigate vaccine strategies. Infection of mice with γHV68 elicits robust antiviral immunity, and long-term protection from γHV68 reactivation requires both cellular and humoral immune responses. Vaccination of mice with AC-replication and transcription activator (RTA), a highly lytic latency-null recombinant γHV68, results in complete protection from wild-type γHV68 infection that lasts for at least 10 mo. In this report, we examine the immune correlates of AC-RTA–mediated protection and show that sterilizing immunity requires both T cells and Ab. Importantly, Ab was also critical for mitigating viral infection in the brain, and in the absence of Ab-mediated control, amplification of the AC-RTA virus in the brain resulted in fatality. Our results highlight important considerations in the development of vaccination strategies based on live-attenuated viruses.
IL-33–Responsive Lineage−CD25+CD44hi Lymphoid Cells Mediate Innate Type 2 Immunity and Allergic Inflammation in the Lungs
Authors: Bartemes Kathleen R. , Iijima Koji , Kobayashi Takao , Kephart Gail M. , McKenzie Andrew N. , Kita Hirohito
Published: December 2011

Innate immunity provides the first line of response to invading pathogens and a variety of environmental insults. Recent studies identified novel subsets of innate lymphoid cells that are capable of mediating immune responses in mucosal organs. In this paper, we describe a subset of lymphoid cells that is involved in innate type 2 immunity in the lungs. Airway exposure of naive BALB/c or C57BL/6J mice to IL-33 results in a rapid (<12 h) production of IL-5 and IL-13 and marked airway eosinophilia independently of adaptive immunity. In the lungs of nonsensitized naive mice, IL-33–responsive cells were identified that have a lymphoid morphology, lack lineage markers, highly express CD25, CD44, Thy1.2, ICOS, Sca-1, and IL-7Rα (i.e., Lin−CD25+CD44hi lymphoid cells), and require IL-7Rα for their development. Airway exposure of naive mice to a clinically relevant ubiquitous fungal allergen, Alternaria alternata, increases bronchoalveolar lavage levels of IL-33, followed by IL-5 and IL-13 production and airway eosinophilia without T or B cells. This innate type 2 response to the allergen is nearly abolished in mice deficient in IL-33R (i.e., ST2), and the Lin−CD25+CD44hi lymphoid cells in the lungs are required and sufficient to mediate the response. Thus, a subset of innate immune cells that responds to IL-33 and vigorously produces Th2-type cytokines is present in mouse lungs. These cells may provide a novel mechanism for type 2 immunity in the airways and induction of allergic airway diseases such as asthma.
Bronchial Artery Arising from the Left Vertebral Artery: Case Report and Review of the Literature
Authors: Amrhein Timothy J. , Kim Charles , Smith Tony P. , Washington L.
Published: December 2011

Knowledge of bronchial artery anatomy, including the possible locations of anomalous origin, is essential for complete catheter directed embolization for massive hemoptysis. Undetected anomalous bronchial arteries can be a source of failed bronchial artery embolization. We report a case of a common trunk bronchial artery arising from the left vertebral artery and review standard and variant bronchial artery anatomy.
Re-explorative Parathyroid Surgery for Persistent and Recurrent Primary Hyperparathyroidism
Authors: Afors Karolina , O'Connell Rachel L , Thomas Martin H
Published: December 2011

Primary hyperparathyroidism (HPT) is treated by parathyroidectomy. Excision of abnormal parathyroid tissue is curative in the majority of cases. Postoperative persistent or recurrent HPT has been reported up to 30%. The purpose of this study was to evaluate the role of imaging techniques and determine the efficacy of reexplorative surgery. A total of 306 patients underwent parathyroidectomy between 2000 and 2009. Twelve patients (3.9%) were not cured. Two patients declined further treatment, the other 10 patients underwent further investigation and surgery. Imaging and results of redo surgery together with associated complications were evaluated. All 10 patients were investigated with sestamibi, which accurately localized aberrant parathyroid tissue in three cases and ultrasound scans which also localized three cases. CT was useful in one of the three cases for which it was used. PET and MRI were not helpful. Twelve glands were resected, six adenomas, five hyperplastic and one normal gland. Nine of the 10 reoperated patients became normocalcemic. Complications included a bilateral recurrent laryngeal paresis. In total, 317 operations were performed and 303 of 306 (99%) patients were cured. Redo surgery for HPT is challenging and carries higher risks than primary surgery. Sestamibi and ultrasound scans are the most helpful imaging modalities. When there is concordance a targeted approach may be considered, otherwise a more extensive dissection is required. Redo parathyroid surgery should be considered, even if scans are unhelpful, for patients who are symptomatic or young or have a persistently high calcium level.
Secondary Hyperparathyroidism Presenting with Vocal Cord Paralysis
Authors: Ho Thomas WT , McMullen Todd P
Published: December 2011

The association of vocal cord paralysis with tumors in the neck generally raises the suspicion of an underlying malignancy. We report the clinical course, imaging and operative findings in a patient with secondary hyperparathyroidism presenting with vocal cord paralysis. The related literature is also reviewed. A 45-year-old man with end-stage renal failure was awaiting surgical treatment for secondary hyperparathyroidism. Ultrasound of the neck demonstrated hypoechoic nodules consistent with enlarged parathyroid glands. Several months later, just before the scheduled date for parathyroid surgery, he developed increasing hoarseness and vocal fatigue. Direct laryngoscopy revealed an immobile left vocal cord (VC). Neck examination and further imaging did not reveal the source of VC palsy. A presumptive diagnosis of thyroid or parathyroid malignancy involving the recurrent laryngeal nerve (RLN) was made. Intraoperatively, four enlarged parathyroid glands were encountered. The left superior gland was seen stretching and displacing the RLN without evidence of direct invasion. This was successfully dissected off while preserving the RLN. The remaining three parathyroid glands were subsequently removed with autotransplantation of a parathyroid remnant. In addition, a left thyroid lobectomy and ipsilateral level VI dissection was performed. Final pathology revealed parathyroid hyperplasia and thyroid follicular adenoma. No malignancy was seen. Three weeks later, the patient's biochemistry had normalized and his voice improved. Laryngoscopy confirmed a mobile left VC. Benign parathyroid tumors are rarely associated with RLN compression leading to VC paralysis. Such diagnoses are difficult to make preoperatively. In the absence of malignant invasion, the RLN should be preserved during surgery as it is likely to recover once the compression is relieved.
Adrenal Adenoma–Hemangioma: A Unique Collision Tumor
Authors: Raveendran Subhash , Babu SP Harish , Kumar ML Arun , Iyoob VA , Natesh Bonny
Published: December 2011

Collision tumors are distinct and rare groups of neoplasms characterized by occurrence of two histologically different neoplasms at one site as a single lesion without significant tissue admixture. They are described in different parts of the body including adrenal glands. Collision tumors reported in relation to adrenal gland are mainly combinations of adenoma and metastasis. Here we present a case of incidentally detected adrenal collision tumor with adenoma and hemangioma as components which is a very rare and unique occurrence.
Overlap of Pseudohypoparathyroidism and Primary Hyperparathyroidism in a Patient: Just a Coincidence?
Authors: Neukirch Ana Karena , Heckmann Christian , Weyerbrock Norbert , Günther Silke , Dotzenrath Cornelia
Published: December 2011

A 56-year-old female patient with the phenotype of Albright's hereditary osteodystrophy (AHO) and pseudohypoparathyroidism 1a (PHP) diagnosed in 1987 was shown to have a heterozygote inactivating mutation on the GNAS1 gene. The patient has been treated with oral calcium and vitamin D since diagnosis of PHP 1a and developed primary hyperparathyroidism (pHPT) in 2009. Ultrasound as well as 99Tcsestamibi could demonstrate a lesion in the right lower position. Intraoperatively, a solitary parathyroid adenoma was found and resected leading to a ‘normalization’ of PTH and calcium. This case highlight is the rare coincidence of PHP, AHO and pHPT.
Spin‐orbit interaction in a two‐dimensional electron gas: A SU(2) formulation
Authors: Raimondi R. , Schwab P. , Gorini C. , Vignale G.
Published: December 2011

Spin‐orbit interaction is usefully classified as extrinsic or intrinsic, depending on its origin: the potential due to random impurities (extrinsic), or the crystalline potential associated with the band or device structure (intrinsic). In this paper we will show how, by using a SU(2) formulation, the two sources may be described in an elegant and unified way. As a result we obtain a simple description of the interplay of the two types of spin‐orbit interaction, and a physically transparent explanation of the vanishing of the d.c. spin Hall conductivity in a Rashba two‐dimensional electron gas when spin relaxation is neglected, as well as its reinstatement when spin relaxation is allowed. Furthermore, we obtain an explicit formula for the transverse spin polarization created by an electric current, which generalizes the standard formula obtained by Edelstein, and Aronov and Lyanda‐Geller by including extrinsic spin‐orbit interaction and spin relaxation.
Learning from “Coffee Rings”: Ordered Structures Enabled by Controlled Evaporative Self‐Assembly
Authors: Han Wei , Lin Zhiqun
Published: December 2011

Research into the evaporation of solutions is not only aimed at a better understanding the physics of evaporation, but increasingly at capitalizing on the extremely simple method it offers to assemble diverse nonvolatile solutes into complex ordered structures on the submicron and longer length scales. This Review highlights recent advances in evaporative assembly of confined solutions, focusing especially on recently developed approaches that provide structures with unprecedented regularity composed of polymers, nanoparticles, and biomaterials, by controlled evaporation‐driven, flow‐aided self‐assembly. A broad range of variables that can control the deposition are explored and the future directions of this rich field are presented.
Influence of Periodic Nitrogen Functionality on the Selective Oxidation of Alcohols
Authors: Chan‐Thaw Carine E. , Villa Alberto , Veith Gabriel M. , Kailasam Kamalakannan , Adamczyk Leslie A. , Unocic Raymond R. , Prati Laura , Thomas Arne
Published: December 2011

An enhancement in catalytic alcohol oxidation activity is attributed to the presence of nitrogen heteroatoms on the external surface of a support material. The same Pd particles (3.1–3.2 nm) were supported on polymeric carbon–nitrogen supports and used as catalysts to selectively oxidize benzyl alcohol. The polymeric carbon–nitrogen materials include covalent triazine frameworks (CTF) and carbon nitride (C3N4) materials with nitrogen content varying from 9 to 58 atomic percent. With comparable metal exposure, estimated by X‐ray photoelectron spectroscopy, the activity of these catalysts correlates with the concentration of nitrogen species on the surface. Because the catalysts showed comparable acidic/basic properties, this enhancement cannot be ascribed to the Lewis basicity but most probably to the nature of N‐containing groups that govern the adsorption sites of the Pd nanoparticles.
Intramolecular HAr Ligand Exchange between Silicon and Boron: Functionality Transfer of SiH to BH
Authors: Kawachi Atsushi , Morisaki Hiroshi , Nishioka Norimasa , Yamamoto Yohsuke
Published: December 2011

o‐C6H4(SiR3−nHn)(BMes2) (1; R=Me, Ph; n=1, 2) undergo MesH (Mes=mesityl) ligand exchange between the silicon atom and the boron atom to form o‐C6H4(SiMesR3−nHn−1)(BMesH) (6) upon heating. The resulting hydroborane intermediates (6) immediately react with benzaldehyde to afford their corresponding benzyloxyboranes (5). A DFT study of model compounds reveals the transition states of the ligand exchange. A hydride abstraction from the silicon atom by the boron center is key to reaching the transition states, which include the tricoordinate silyl‐cation moiety and the tetracoordinate hydridoborate moiety.
Total Synthesis of (+)‐Asteriscanolide: Further Exploration of the Rhodium(I)‐Catalyzed [(5+2)+1] Reaction of Ene‐Vinylcyclopropanes and CO
Authors: Liang Yong , Jiang Xing , Fu Xu‐Fei , Ye Siyu , Wang Tao , Yuan Jie , Wang Yuanyuan , Yu Zhi‐Xiang
Published: December 2011

The total synthesis of (+)‐asteriscanolide is reported. The synthetic route features two key reactions: 1) the rhodium(I)‐catalyzed [(5+2)+1] cycloaddition of a chiral ene‐vinylcyclopropane (ene‐VCP) substrate to construct the [6.3.0] carbocyclic core with excellent asymmetric induction, and 2) an alkoxycarbonyl‐radical cyclization that builds the bridging butyrolactone ring with high efficiency. Other features of this synthetic route include the catalytic asymmetric alkynylation of an aldehyde to synthesize the chiral ene‐VCP substrate, a highly regioselective conversion of the [(5+2)+1] cycloadduct into its enol triflate, and the inversion of the inside–outside tricycle to the outside–outside structure by an ester‐reduction/elimination to enol‐ether/hydrogenation procedure. In addition, density functional theory (DFT) rationalization of the chiral induction of the [(5+2)+1] reaction and the diastereoselectivity of the radical annulation has been presented. Equally important is that we have also developed other routes to synthesize asteriscanolide using the rhodium(I)‐catalyzed [(5+2)+1] cycloaddition as the key step. Even though these routes failed to achieve the total synthesis, these experiments gave further useful information about the scope of the [(5+2)+1] reaction and paved the way for its future application in synthesis.
A stochastic model for survival of early prostate cancer with adjustments for leadtime, length bias, and over‐detection
Authors: Wu Grace Hui‐Min , Auvinen Anssi , Yen Amy Ming‐Fang , Hakama Matti , Walter Stephen D. , Chen Hsiu‐Hsi
Published: December 2011

To compare the survival between screen‐detected and clinically detected cancers, we applied a series of non‐homogeneous stochastic processes to deal with leadtime, length bias, and over‐detection by using full information on detection modes obtained from the Finnish randomized controlled trial for prostate cancer screening. The results show after 9‐year follow‐up the hazard ratio of prostate cancer death for screen‐detected cases against clinically detected cases increased from 0.24 (95% CI: 0.16–0.35) without correction for these biases, to 0.76 after correction for leadtime and length biases, and finally to 1.03 (95% CI: 0.79–1.33) for a further adjustment for over‐detection. Adjustment for leadtime and length bias but no over‐detection led to a 24% reduction in prostate cancer death as a result of prostate‐specific antigen test. The further calibration of over‐detection indicates no gain in survival of screen‐detected prostate cancers (excluding over‐detected case as stayer considered in the mover–stayer model) as compared with the control group in the absence of screening that is considered as the mover. However, whether the model assumption on over‐detection is robust should be validated with other data sets and longer follow‐up.
Terpenoids are Widespread in Actinomycetes: A Correlation of Secondary Metabolism and Genome Data
Authors: Citron Christian A. , Gleitzmann Julia , Laurenzano Gianfranco , Pukall Rüdiger , Dickschat Jeroen S.
Published: December 2011

The genomes of all bacteria with publicly available sequenced genomes have been screened for the presence of sesquiterpene cyclase homologues, resulting in the identification of 55 putative geosmin synthases, 23 homologues of 2‐methylisoborneol synthases, and 98 other sesquiterpene cyclase homologues. Most of these enzymes by far were found in actinomycetes. The terpenoid volatiles from 35 strains, including 31 actinomycetes and four strains from other taxa, were collected by using a closed‐loop stripping apparatus and identified by GC‐MS. All of these bacteria apart from one strain encode sesquiterpene cyclase homologues in their genomes. The identified volatile terpenoids were grouped according to structural similarities and their biosynthetic relationship, and the results of these analyses were correlated to the available genome information, resulting in valuable new insights into bacterial terpene biosynthesis.
Nanographite Impurities in Carbon Nanotubes: Their Influence on the Oxidation of Insulin, Nitric Oxide, and Extracellular Thiols
Authors: Chng Elaine Lay Khim , Pumera Martin
Published: December 2011

There has been growing interest in the use of modified‐carbon‐nanotube electrodes in applications such as the electrochemical detection of biologically significant compounds, owing to their apparent “electrocatalytic” properties and ability to enhance oxidative signals. In spite of their salient properties, little work has been done to further examine the reasons for these reported characteristics. In this report, we present clear evidence that the presence of nanographite impurities within carbon nanotubes (CNTs) is responsible for providing the previously reported enhanced electrochemical response. We have demonstrated this effect on homocysteine, N‐acetyl‐L‐cysteine, nitric oxide, and insulin, which are important biological agents in the body. Moreover, we also showed that the influence of nanographite impurities on the electrochemistry of carbon nanotubes is prevalent among a variety of CNTs, such as single‐walled CNTs, double‐walled CNTs, and few‐walled CNTs. Our findings will have a profound influence upon the biomedical applications of CNTs.
Discrimination and Classification of Ginsenosides and Ginsengs Using Bis‐Boronic Acid Receptors in Dynamic Multicomponent Indicator Displacement Sensor Arrays
Authors: Zhang Xiaojun , You Lei , Anslyn Eric V. , Qian Xuhong
Published: December 2011

Ginsenosides are complex natural products with a diverse array of biological activities, but their molecular recognition and sensing is challenging. A library of simple bis‐boronic acid‐based receptors with various spacers was synthesized for the sensing of ginsenosides. The incorporation of two boronic acids allowed the pairing of two indicators, which can simultaneously bind the receptors or two saccharides within the ginsenosides. A cross‐reactive sensing array was therefore constructed using the receptors in conjunction with different pairs of indicators. LDA plots created from the colorimetric response of the hosts and indicator pairs reveal excellent classification of the ginsenosides, and the corresponding loading plots reveal the cross‐reactivity of the receptors. In addition, several commercial ginseng extracts were unambiguously classified using the same sensing array. The assay reported here should be applicable to the analysis of other large saccharide‐based natural products.
Synthesis and Antimicrobial Activity of New 2,5‐Disubstituted 1,3,4‐Oxadiazoles and 1,2,4‐Triazoles and Their Sugar Derivatives
Authors: El‐Sayed Wael A. , Ali Omar M. , Hendy Hend A. , Abdel‐Rahman Adel A.‐H.
Published: December 2011

A series of new 2,5‐disubstituted‐1,3,4‐oxadiazole and 1,2,4‐triazole derivatives were synthesized by heterocyclization of acid hydrazide 1 and thiosemicarbazide derivative 2. Furthermore, the acyclic C‐nucleoside analogs were prepared by cyclization of their corresponding sugar hydrazones by reaction with acetic anhydride. The antimicrobial activity of the prepared compounds was evaluated and some of the synthesized compounds revealed good activities against fungi.
Synthesis and Characterization of a Novel Soluble Diethoxy Phosphoryl Chitosan
Authors: Ma Li , Li Kerang , Li Limin , Liu Pu
Published: December 2011

A simple and efficient method for the preparation of a novel soluble chitosan derivative, diethoxy phosphoryl chitosan (PH‐chitosan), has been developed. Ph‐chitosan was characterized by elemental analysis, FT‐IR, NMR, ICP, XRD, TG and SEM, respectively. The chemical identity of PH‐chitosan was determined by FT‐IR and confirmed by NMR, and those results unequivocally demonstrated that diethoxy phosphoryl groups were grafted onto the amino and hydroxyl groups of chitosan. The results of XRD indicated that the crystalline structure of chitosan was destroyed due to the incorporation of diethoxy phosphoryl group resulting in loss of hydrogen bond. The analysis of TG demonstrated that PH‐chitosan was less thermal stable than chitosan. This simple synthetic method provided a new and available approach to prepare a soluble high molecule weight chitosan derivative.
Direct α‐Alkylation of Aldehydes by Brønsted‐Acid Catalysis
Authors: Zhu Xiangrong , Wang Ting , Guo Qixiang
Published: December 2011

A Brønsted acid catalyzed direct alkylation reaction of aldehydes was described. The 3,5‐dinitrobenzoic acid promoted the reaction between aldehydes and diarylmethanols to afford the corresponding alkylation products with middle to high yields (up to 91% yield).
Synthesis of 2,2‐Bis‐C‐functionalized Chain Glucosid‐3‐ketals
Authors: Zhang Fuyi , Liu Hong , Sheng Yingming , Liu Hongmin
Published: December 2011

Novel 2,2‐bis‐C‐functionalized chain glucosid‐3‐uloses have been synthesized in the form of ketal. The synthesis is rather convenient through one pot multistep reactions and no expensive reagents are involved. The products are formed via autoxidation‐Michael addition mechanism and their structures were characterized by X‐ray crystallographic analysis. Their crystal stuctures are stablilized by intermolecular hydrogen bonds and double‐strand supramolecular stacking is observed.
Fantastic Plastic
Authors: Banerji Amitabh , Tausch Michael W. , Scherf Ullrich
Published: December 2011

Mit diesem Beitrag werden fachliche Grundlagen, experimentelle Zugänge und didaktische Materialien für die curriculare Innovation von Chemieunterricht vorgestellt. Die Experimente und Materialien beziehen sich auf das Phänomen der Elektrolumineszenz, das im Zusammenhang mit modernen Flachbildschirmen ein alltagsnaher, motivierender Kontext für Schülerinnen und Schüler ist. Gleichzeitig handelt es sich im Zusammenhang mit der Forderung nach energiesparenden, in Farbe, Leuchtkraft und Pixelgröße maßgeschneiderten Lichtquellen um ein aktuelles Forschungs‐ und Entwicklungsfeld in Wissenschaft und Technik.
Hydrogenolysis of Glycerol to 1,2‐Propanediol over Ru–Cu Bimetals Supported on Different Supports
Authors: Liu Huizhen , Liang Shuguang , Jiang Tao , Han Buxing , Zhou Yinxi
Published: December 2011

Glycerol is a low‐cost and renewable resource, and its utilization is of great interest for chemical industry and sustainable development. In this work, a series of Ru–Cu bimetallic catalysts were prepared using different supports in an attempt to develop highly efficient catalysts. Hydrogenolysis of aqueous solution of glycerol was performed with the supported Ru–Cu catalysts. The bimetallic catalysts were very efficient for catalyzing the hydrogenolysis of glycerol compared with the corresponding monometallic catalysts. One hundred percent of glycerol conversion and 78.5% of 1,2‐propanediol yield could be achieved at 180°C and 8 MPa.
Experimental and Computational Active Site Mapping as a Starting Point to Fragment‐Based Lead Discovery
Authors: Behnen Jürgen , Köster Helene , Neudert Gerd , Craan Tobias , Heine Andreas , Klebe Gerhard
Published: December 2011

Small highly soluble probe molecules such as aniline, urea, N‐methylurea, 2‐bromoacetate, 1,2‐propanediol, nitrous oxide, benzamidine, and phenol were soaked into crystals of various proteins to map their binding pockets and to detect hot spots of binding with respect to hydrophobic and hydrophilic properties. The selected probe molecules were first tested at the zinc protease thermolysin. They were then applied to a wider range of proteins such as protein kinase A, D‐xylose isomerase, 4‐diphosphocytidyl‐2C‐methyl‐D‐erythritol synthase, endothiapepsin, and secreted aspartic protease 2. The crystal structures obtained clearly show that the probe molecules populate the protein binding pockets in an ordered fashion. The thus characterized, experimentally observed hot spots of binding were subjected to computational active site mapping using HotspotsX. This approach uses knowledge‐based pair potentials to detect favorable binding positions for various atom types. Good agreement between the in silico hot spot predictions and the experimentally observed positions of the polar hydrogen bond forming functional groups and hydrophobic portions was obtained. Finally, we compared the observed poses of the small‐molecule probes with those of much larger structurally related ligands. They coincide remarkably well with the larger ligands, considering their spatial orientation and the experienced interaction patterns. This observation confirms the fundamental hypothesis of fragment‐based lead discovery: that binding poses, even of very small molecular probes, do not significantly deviate or move once a ligand is grown further into the binding site. This underscores the fact that these probes populate given hot spots and can be regarded as relevant seeds for further design.
Engineering and Functionalization of the Disulfide‐Constrained Miniprotein Min‐23 as a Scaffold for Diagnostic Application
Authors: Zoller Frederic , Schwaebel Thimon , Markert Annette , Haberkorn Uwe , Mier Walter
Published: December 2011

Miniproteins are scaffolds for the development of alternative non‐immunoglobin binding agents for medical applications. This peptide format features high tolerance to sequence mutagenesis, excellent proteolytic stability, and fast blood pool clearance. Herein we present the total chemical synthesis of the disulfide‐constrained scaffold Min‐23 and its functionalization for in vitro and in vivo application. Optimized solid‐phase peptide chemistry and oxidative folding strategies were developed to engineer this miniprotein with native‐like disulfide configuration. High levels of serum stability and proteolytic resistance, as well as a beneficial pharmacokinetic profile for diagnostic imaging, were determined by using radiolabeling techniques such as positron emission tomography. The reported achievements highlight Min‐23 as a promising scaffold for the development of novel recognition molecules for medical application.
Long‐Range Transport of Giant Vesicles along Microtubule Networks
Authors: Herold Christoph , Leduc Cécile , Stock Robert , Diez Stefan , Schwille Petra
Published: December 2011

We report on a minimal system to mimic intracellular transport of membrane‐bounded, vesicular cargo. In a cell‐free assay, purified kinesin‐1 motor proteins were directly anchored to the membrane of giant unilamellar vesicles, and their movement studied along two‐dimensional microtubule networks. Motion‐tracking of vesicles with diameters of 1–3 μm revealed traveling distances up to the millimeter range. The transport velocities were identical to velocities of cargo‐free motors. Using total internal reflection fluorescence (TIRF) microscopy, we were able to estimate the number of GFP‐labeled motors involved in the transport of a single vesicle. We found that the vesicles were transported by the cooperative activity of typically 5–10 motor molecules. The presented assay is expected to open up further applications in the field of synthetic biology, aiming at the in vitro reconstitution of sub‐cellular multi‐motor transport systems. It may also find applications in bionanotechnology, where the controlled long‐range transport of artificial cargo is a promising means to advance current lab‐on‐a‐chip systems.
Mode Change in the Self‐Motion of a Benzoquinone Disk Coupled with a NADPH System
Authors: Nakata Satoshi , Matsuda Yui , Ikura Yumihiko S. , Takeda Akira , Izumi Shunsuke
Published: December 2011

The self‐motion of a benzoquinone (BQ) disk on NADPH was investigated as the coupling of an autonomous motor and an enzyme reaction. In the absence of the enzyme reaction, features of motion changed depending on the concentration of NADPH, that is, continuous motion→ intermittent oscillatory motion→ no motion. When the reverse reaction from NADP+ to NADPH was introduced into the system with the addition of an enzyme reaction, continuous motion changed to intermittent oscillatory motion with small amplitude. The mechanism of this mode change is discussed in relation to the surface tension as a driving force and the time course of UV spectra as a window to the progress of the reaction. Characteristic features of the mode change were qualitatively reproduced by a numerical calculation.
Furfural—A Promising Platform for Lignocellulosic Biofuels
Authors: Lange Jean‐Paul , van der Heide Evert , van Buijtenen Jeroen , Price Richard
Published: December 2011

Furfural offers a promising, rich platform for lignocellulosic biofuels. These include methylfuran and methyltetrahydrofuran, valerate esters, ethylfurfuryl and ethyltetrahydrofurfuryl ethers as well as various C10–C15 coupling products. The various production routes are critically reviewed, and the needs for improvements are identified. Their relative industrial potential is analysed by defining an investment index and CO2 emissions as well as determining the fuel properties for the resulting products. Finally, the most promising candidate, 2‐methylfuran, was subjected to a road trial of 90 000 km in a gasoline blend. Importantly, the potential of the furfural platform relies heavily on the cost‐competitive production of furfural from lignocellulosic feedstock. Conventional standalone and emerging coproduct processes—for example, as a coproduct of cellulosic ethanol, levulinic acid or hydroxymethyl furfural—are expensive and energetically demanding. Challenges and areas that need improvement are highlighted. In addition to providing a critical review of the literature, this paper also presents new results and analysis in this area.
The NLRP3/ASC/Caspase‐1 axis regulates IL‐1β processing in neutrophils
Authors: Mankan Arun K. , Dau Therese , Jenne Dieter , Hornung Veit
Published: December 2011

Neutrophils play a pivotal role in the defense against bacterial, viral and fungal infections and are important mediators in the acute inflammatory response. At the same time, neutrophils are also in volved in sterile inflammatory responses that are triggered by endogenous ligands. A series of immediate effector functions and the expression of proinflammatory genes enable neutrophils to initiate the immune response against the injurious agent. Among these, interleukin‐1β (IL‐1β) plays a key role in the orchestration of the inflammatory response. Induction of IL‐1β expression leads to production of cytosolic pro‐IL‐1β, which requires further processing by a proteolytic cleavage event. Caspase‐1 was initially identified as the main IL‐1β‐converting enzyme, and the upstream events leading to caspase‐1 activation were identified as so‐called inflammasome complexes. Up to now, the inflammasome system has mainly been studied in macrophages, whereas the inflammasome was thought to play a redundant or no role in the cell intrinsic processing of pro‐IL‐1β in neutrophils. Here, we identify the expression of the components of the NLRP3 inflammasome complex in neutrophils and show that the NLRP3 inflammasome pathway is indeed operational in neutrophils. Our findings establish the NLRP3 inflammasome as a key step in the secretion of matured IL‐1β by neutrophils.