bluuebunny/crossref_metadata_2025 huggingface dataset:
Modelowanie dostępności i mobilności w kontekście zróżnicowań regionalnych liczby ludności, PKB i spółek prawa handlowego
Authors: Rosik Piotr , Komornicki Tomasz , Goliszek Sławomir
Published: March 2021

Artykuł   stanowi   oryginalną   syntezę   badań   dostępności   i   mobilności   prowadzonych w Instytucie Geografii i Przestrzennego Zagospodarowania Polskiej Akademii Nauk (IGiPZ PAN) w kontekście uwarunkowań przestrzennych rozwoju przemysłu w Polsce, ze szczególnym uwzględnieniem rozkładu przestrzennego ludności, PKB oraz lokalizacji spółek prawa handlowego. Autorzy podjęli się analizy dostęp- ności potencjałowej w transporcie ciężarowym, gdzie na miarę atrakcyjności celu wpływają zarówno liczba ludności, jak i PKB. Do analizy empirycznej wykorzystano autorską aplikację OGAM. W części artykułu poświęconej mobilności wykorzystano rezultaty modelowego rozkładu ruchu na krajowej i wojewódzkiej sieci drogowej oraz oprogramowanie VISUM. Przedstawiono oryginalną metodę, która porównuje wyniki modelu grawitacyjnego z rzeczywistym rozkładem ruchu, wynikającym z pomiarów natężenia ruchu w sieci, w odniesieniu do podróży między spółkami prawa handlowego odbywanych przez przedsiębiorców (biz- nesmenów, przedstawicieli handlowych itd.). Rozkład teoretyczny ruchu pojazdów osobowych porównano z wykorzystaniem analizy kartograficznej i pokazano przeszacowanie lub niedoszacowanie ruchu względem wyników generalnego pomiaru ruchu (GPR) w 2010 roku. W badaniu dostępności i mobilności wykorzystano macierz czasów podróży na poziomie gminnym (2321 jednostek). Prędkości obliczono na podstawie modelu prędkości IGiPZ PAN. Wskazano, że modele potencjału i grawitacji należą do mało popularnych metod analizy uwarunkowań transportowych rozwoju przemysłu w Polsce i dają duże możliwości w zakresie wskazywania potencjalnych lokalizacji dla nowych inwestycji w kontekście transportu towarów i podróży służbowych.
Zmiany w turystycznym transporcie lotniczym Egiptu w latach 2005–2014
Authors: Wendt Jan A.
Published: March 2021

Rewolucja zwana arabską wiosną znalazła swoje odbicie w zmianach wielkości lotniczego, turystycznego ruchu pasażerskiego w krajach Afryki Północnej, zwłaszcza w Egipcie i Tunezji. Głównym przedmiotem prezentowanych badań jest ocena zmian wielkości ruchu turystycznego w Egipcie. Celem pracy jest pokazanie wielkości negatywnego oddziaływania wydarzeń politycznych w Egipcie na spadek ruchu turystycznego oraz dochodów z turystyki w tym kraju. Do analizy i korelacji wybrano zmiany wielkości turystycznego ruchu lotniczego w Egipcie na wybranych lotniskach. W 2011 roku, w porównaniu do 2008 roku, w porcie lotniczym w Szarm el-Szejk ruch pasażerski zmniejszył się o 37%, a w Hurghadzie o 27%. Stabilizacja sytuacji politycznej w kolejnych latach spowodowała wzrost wielkości przewozów lotniczych. Jednak zamach wojskowy w 2013 roku kolejny raz doprowadził do spadku ruchu turystycznego. Dopiero uspokojenie sytuacji politycznej w 2014 roku przyniosło wzrost liczby turystów. Jednak dochody z turystyki w 2014 roku stanowią jedynie 62% dochodów z najlepszego dla egipskiej turystyki 2010 roku. Według danych statystycznych całkowita liczba turystów zagranicznych, którzy odwiedzili Egipt w 2011 roku, spadła o 33% w porównaniu z 2010 rokiem. Wprawdzie w 2012 roku nastąpił jej wzrost o 18% w porównaniu do 2011 roku, jednak kolejny rok, wraz z nasileniem wydarzeń politycznych, przyniósł spadek o 15%, a niewielki wzrost – o 5% – nastąpił dopiero w 2014 roku.
Zachowania konsumenckie Polaków korzystających z oferty polsko-egipskich biur podróży w Szarm el-Szejk
Authors: Ziółkowska-Weiss Kamila
Published: March 2021

Egipt jest coraz popularniejszy wśród polskich turystów. Wyjazdom do tego państwa sprzyja niezwykle korzystna cena wycieczek w porównaniu z ofertami innych nadmorskich krajów. Jedną z przyczyn tego stanu jest fakt, że Egipt stanowi jedną z tzw. destynacji dolarowych. W sytuacji, gdy kurs dolara w stosunku do euro jest niższy, a złotówka ma silną pozycję wobec obu tych walut, wycieczki do Egiptu mają bardzo atrakcyjne ceny. Główny cel przyjazdu do Egiptu to: turystyka wypoczynkowa (piękne plaże), kursy nurkowania, snorkeling, windsurfing, żeglarstwo, jachting, wędkarstwo, golf oraz turystyka poznawcza. Intensywność zainteresowania oraz możliwości finansowe potencjalnych turystów spowodowały powstanie lokalnych biur podroży, które zajęły się zaspokajaniem nowych potrzeb – przygotowaniem ofert turystyki i wypoczynku. Co roku do Egiptu przybywa duża liczba polskich turystów, którzy pragną poznać i zwiedzić ten kraj. W związku z tym w egipskich kurortach powstają polsko-egipskie biura podróży oferujące turystom lokalne, fakultatywne wycieczki. W artykule omówiono działalność największych polsko-egipskich biur podróży w Szarm el-Szejk (ang. Sharm el-Sheikh), takich jak: E-Sharm.Pl, Słoneczny Sharm, PolSharm, czy Esti Tours. Autorka przedstawia wyniki badań, które przeprowadziła w sierpniu 2015 roku w Szarm el-Szejk wśród polskich turystów, którzy korzystali z usług lokalnych biur podróży. Zaprezentowano dane o tym, jaką formę turystyki i wypoczynku preferują ankietowani w Egipcie, co skłoniło ich do skorzystania z usług danego biura podróży, jak dowiedzieli się o jego istnieniu, w ilu fakultatywnych wycieczkach uczestniczyli, czym kierowali się przy wyborze lokalnego biura oraz ile pieniędzy wydali w polsko-egipskich biurach podróży działających w Szarm el-Szejk. Dokonano również analizy najczęściej wybieranych przez polskich turystów wycieczek fakultatywnych oraz oceny ich organizacji.
Procesy koncentracji gospodarczej dużych przedsiębiorstw przemysłowych Poznania
Authors: Tobolska Anna
Published: March 2021

Celem pracy jest przedstawienie przebiegu procesów koncentracji gospodarczej na podstawie zmian organizacyjnych i własnościowych zachodzących w dużych przedsiębiorstwach przemysłowych Poznania. Procesy koncentracji gospodarczej są jednym z najistotniejszych współczesnych zjawisk ekonomicznych. Polegają one na skupianiu w jednym organizmie gospodarczym coraz większych zasobów używanych do prowadzenia działalności gospodarczej na coraz większą skalę. Wynikiem tych procesów jest funkcjonowanie wieloczłonowych podmiotów gospodarczych, a więc takich, które składają się z podporządkowanych jednostek organizacyjno-gospodarczych o zróżnicowanym statusie prawnym i ekonomicznym. Procesy koncentracji gospodarczej, utożsamiane w swoim aspekcie zewnętrznym z procesami integracji, pokazują mechanizm organizacyjny powstawania sieci przemysłowych tworzonych przez wielonarodowe koncerny funkcjonujące w skali globalnej.
Impact of COVID 19 Pandemic in Hemodialysis Units in Mexico
Authors:   Renal Assistance Center, JF Bueno-Hernández
Published: March 2021

Since the World Health Organization (WHO) declared the pandemic associated with COVID 19, our hemodialysis center took up preventive measures based on the literature on this matter, and created an algorithm for restraining and avoiding further transmission of the virus.
Mecanização sustentável da agricultura familiar: o caso do Noroeste Matogrossense
Authors: Morello Thiago , Heck Claudia , Guimarães Leonela
Published: March 2021

O subsídio à mecanização da agropecuária de pequeno porte visando maior produtividade e menor impacto ambiental tem sido obstado por barreiras infraestruturais, administrativas e financeiras. Procurando contribuir para identificar opções factíveis para a Amazônia brasileira, o presente artigo confronta a experiência da Ásia, África e França com pesquisa de campo realizada no Noroeste Mato-Grossense. Nesta foram identificadas duas modalidades de mecanização subsidiada, a prestação do serviço pelo governo municipal e a cessão, pelo mesmo, de tratores para serem temporariamente administrados por associações de produtores. Não obstante ter sido atestado o potencial de tais alternativas, foram detectados problemas de implementação, compreendendo déficit de tratores, indisponibilidade de fundos para manutenção e maior custo contábil da modalidade associativa. Como medidas corretivas, recomendam-se (i) aumento do orçamento público alocado para assistência técnica e extensão rural voltada ao fortalecimento financeiro e administrativo das associações, (ii) focalização do subsídio na modalidade associativa sempre que possível, mas também em serviços de reparo e manutenção, bem como (iii) uma opção, pelas associações, entre microtratores e tratores, embasada em viabilidade financeira e não em preferências subjetivas.
Pengaruh Masyarakat Ekonomi ASEAN Terhadap Kondisi dan Mobilitas Tenaga Kerja ASEAN Tahun 2015
Authors: Allayna Adelia Maretha , Hidayatullah M Irfan
Published: March 2021

Konsep kerja sama kawasan atau regionalisme mulai meluas berbagai dunia. Salah satu kawasan yang berhasil membentuk regionalisme adalah Asia Tenggara yang dinamai ASEAN. Sejak awal berdirinya, ASEAN lebih diarahkan untuk meningkatkan kerja sama yang berfokus pada bidang politik untuk mencapai keamanan dan perdamaian di kawasan Asia Tenggara. Terbentuknya ASEAN ini tentu saja memberikan dampak bagi setiap negara sebagai akibat dari peraturan, visi misi dan kerja sama didalamnya yang telah dirumuskan bersama dalam kesepakata atas nama ASEAN. Untuk merespon munculnya sejumlah tantangan kerja sama regional, maka dirumuskanlah “ASEAN Vision 2020” yang disahkan di kuala lumpur, malaysia. Salah satu bentuk implementasi ASEAN Vision adalah MEA (Masyarakat Ekonomi Asean) yang memiliki 5 pilar utama, salah dari pilar tersebut adalah masalah ketenagakerjaan. Penelitian ini dilakukan untuk menegtahui aliran, kondisi, dan mobilitas tenaga kerja di wilayah AsiaTenggara serta peluang dan tantangan ASEAN. Penelitian ini menggunakan metode deskriptif-kualitatif. Rendahnya skill dan tingkat pendidikan tenaga kerja menghambat visi misi Masyarakat Ekonomi ASEAN dalam bidang ketenagakerjaan. Dengan terbentuknya MEA kedepannya tentu akan memberikan peluang serta tantangan yang harus dihadapi oleh pemerintah dan para tenaga kerja untuk lebih meningkatkan dan mengasah skill serta kompetensi diri sehingga mampu untuk bersaing dan menghadapi arus MEA di kedepan harinya nanti.
Quantum computation of scattering in scalar quantum field theories
Authors: Jordan Stephen P. , Lee Keith S. M. , Preskill John
Published: March 2021

Quantum field theory provides the framework for the most fundamental physical theories to be confirmed experimentally and has enabled predictions of unprecedented precision. However, calculations of physical observables often require great computational complexity and can generally be performed only when the interaction strength is weak. A full understanding of the foundations and rich consequences of quantum field theory remains an outstanding challenge. We develop a quantum algorithm to compute relativistic scattering amplitudes in massive $\phi^4$ theory in spacetime of four and fewer dimensions. The algorithm runs in a time that is polynomial in the number of particles, their energy, and the desired precision, and applies at both weak and strong coupling. Thus, it offers exponential speedup over existing classical methods at high precision or strong coupling.
Unitary operation attack and the improvement on probabilistic quantum key distribution
Authors: Lin Tzu-Han , Yang Chun-Wei , Hwang Tzonelih
Published: March 2021

This study points out that a malicious communicant in Hwang et al.\textquoteright{}s probabilistic quantum key distribution (PQKD) protocol can manipulate the secret key without being detected by using the unitary operation attack. Accordingly, the security requirements of a PQKD protocol, i.e., unpredictability and fairness, cannot be satisfied in their protocol. A possible solution is also provided to solve the problem.
Transferable Multi-level Attention Neural Network for Accurate Prediction of Quantum Chemistry Properties via Multi-task Learning
Authors: Liu Ziteng , Lin Liqiang , Jia Qingqing , Cheng Zheng , Jiang Yanyan , Guo Yanwen , Ma Jing
Published: March 2021

The development of efficient models for predicting specific properties through machine learning is of great importance for the innovation of chemistry and material science. However, predicting global electronic structure properties like frontier molecular orbital HOMO and LUMO energy levels and their HOMO-LUMO gaps from the small-sized molecule data to larger molecules remains a challenge. Here we develop a multi-level attention neural network, named DeepMoleNet, to enable chemical interpretable insights being fused into multi-task learning through (1) weighting contributions from various atoms and (2) taking the atom-centered symmetry functions (ACSFs) as the teacher descriptor. The efficient prediction of 12 properties including dipole moment, HOMO, and Gibbs free energy within chemical accuracy is achieved by using multiple benchmarks, both at the equilibrium and non-equilibrium geometries, including up to 110,000 records of data in QM9, 400,000 records in MD17 and 280,000 records in ANI-1ccx for random split evaluation. The good transferability for predicting larger molecules outside the training set is demonstrated in both equilibrium QM9 and Alchemy datasets at density functional theory (DFT) level. Additional tests on non-equilibrium molecular conformations from DFT-based MD17 dataset and ANI-1ccx dataset with coupled cluster accuracy as well as the public test sets of singlet fission molecules, biomolecules, long oligomers, and protein with up to 140 atoms show reasonable predictions for thermodynamics and electronic structure properties. The proposed multi-level attention neural network is applicable to high-throughput screening of numerous chemical species in both equilibrium and non-equilibrium molecular spaces to accelerate rational designs of drug-like molecules, material candidates, and chemical reactions.
Infrared Hide-and-Seek: Vibrational Excitons Conceal Surfactants at the Air/Water Interface
Authors: Carter-Fenk Kimberly A. , Carter-Fenk Kevin , Fiamingo Michelle E , Allen Heather , Herbert John M.
Published: March 2021

Surface-sensitive vibrational spectroscopy is a common tool for measuring molecular organization and intermolecular interactions at interfaces. Peak intensity ratios are typically used to extract molecular information from one-dimensional spectra but vibrational coupling between surfactant molecules can manifest as signal depletion in one-dimensional spectra. Through a combination of experiment and theory, we demonstrate the emergence of vibrational excitons in infrared reflection-absorption spectra of soluble and insoluble surfactants at the air/water interface. Vibrational coupling yields a signicant decrease in peak intensities corresponding to C-F vibrational modes of perfluorooctanoic acid molecules. Vibrational excitons also form between arachidic acid surfactants within a compressed monolayer, manifesting as signal reduction of C-H stretching modes. The aqueous phase ionic composition impacts surfactant intermolecular distances, thereby modulating vibrational coupling strength between surfactants. Our results serve as a cautionary tale against employing alkyl and fluoroalkyl vibrational peak intensities in analyses that are ubiquitous in interface science.
TS-Torquoselectivity from Global Conformational Profile
Authors: Yadav Veejendra , Yadav Arpita , Rao Maddali L N
Published: March 2021

From global conformational profile and differential activation energies of conrotatory outward and inward ring openings of all the conformers, it is shown that (a) 3-OMe-cyclobutene must open exclusively outward, and (b) conformers exist for 3-CHO-, 3-COMe-, and 3-NO-cyclobutenes that will open outwards as well. All the conformers of 3-OMe-, 3-CHO-, 3-COMe-, and 3-NO-cyclobutenes are, respectively, within 5.6, 3.2, 4.0 and 2.6 kcal/mol and, hence, abundantly available at room temperature for reaction.
High-Throughput Electron Diffraction Reveals a Hidden Novel Metal-Organic Framework for Electrocatalysis
Authors: Ge Meng , Wang Yanzhi , Carraro Francesco , Liang Weibin , Roostaeinia Morteza , Siahrostami Samira , Proserpio Davide M. , Doonan Christian , falcaro paolo , Zheng Haoquan , Zou Xiaodong , Huang Zhehao
Published: March 2021

Metal-organic frameworks (MOFs) are known for their versatile combination of inorganic building units and organic linkers, which offers immense opportunities in a wide range of applications. However, many MOFs are typically synthesized as multiphasic polycrystalline powders, which are challenging for studies by X-ray diffraction. Therefore, developing new structural characterization techniques is highly desired in order to accelerate discoveries of new materials. Here, we report a high-throughput approach for structural analysis of MOF nano- and sub-microcrystals by three-dimensional electron diffraction (3DED). A new zeolitic-imidazolate framework (ZIF), denoted ZIF-EC1, was first discovered in a trace amount during the study of a known ZIF-CO3-1 material by 3DED. The structures of both ZIFs were solved and refined using 3DED data. ZIF-EC1 has a dense 3D framework structure, which is built by linking mono- and bi-nuclear Zn clusters and 2-methylimidazolates (mIm-). With a composition of Zn3(mIm)5(OH), ZIF-EC1 exhibits high N and Zn densities. We show that the N-doped carbon material derived from ZIF-EC1 is a promising electrocatalysis for oxygen reduction reaction (ORR). The discovery of this new MOF and its conversion to an efficient electrocatalyst highlights the power of 3DED in developing new materials and their applications.
A Method for the Accurate Quantification of Gas Streams by On-Line Mass Spectrometry
Authors: Velasco Edwing , Ballesteros Rueda Luz Marina , Baldovino Medrano Víctor Gabriel
Published: March 2021

The accuracy of the online quantification of gaseous effluents from catalytic reactors by mass spectrometry (MS) is rarely addressed by researchers, despite the extensive use of the technique. MS results are strongly sensitive to both the operation conditions of the reactor and to the state of the instrument. Therefore, most studies use them as qualitative descriptors of the performance of catalytic reaction systems. The purpose of this work was to develop an accurate method for the quantification of gaseous effluents from catalytic reactors. For this purpose, the mathematical expressions from the so-called external and internal standard calibration methods for MS were coupled to the typical metrics used for studying catalytic reactions; namely, conversion, selectivity, and carbon mass balances. The catalytic combustion of methane was selected as a model reaction to test the developed approach. The accuracy of the developed method was validated by comparison with results obtained in a separated reaction system coupled online to a gas chromatograph. The closure of the carbon mass balance was used as a control metrics allowing for the assessment of the physical meaning of the method. In general, the internal standard method of calibration was found to be best for the accurate quantification of gaseous streams by on-line mass spectrometry. In general, the results of this investigation may be of use to researchers in the field of catalysis as well as to research workers using mass spectrometry for various purposes.
Transmembrane Anion Transport Promoted by Thioamides
Authors: Pomorski Robert , García-Valverde María , quesada roberto , Chmielewski Michał J.
Published: March 2021

Thioamide groups represent useful hydrogen-bonding motifs for the development of active transmembrane anion transporters. Using a 1,8-dithioamidocarbazole scaffold the superior performance of thioamides compared with the parent amides has been demonstrated.
A Comparative Life Cycle Assessment of Different Production Processes for Waterborne Polyurethane Dispersions
Authors: Klug Valentin , Schöggl Josef-Peter , Dallinger Doris , Stueckler Clemens , Steiner Andreas , Arzt Anton , Kappe C. Oliver , Baumgartner Rupert J.
Published: March 2021

This study provides a comparative life cycle assessment (LCA) of four different polyurethane dispersion production processes from cradle-to-gate. The environmental performances of the NMP process, the acetone process, the melt process, and a conceptualized continuous flow process were evaluated and compared following the CML 2001 methodology. The LCA revealed that the conceptualized flow process exhibits the lowest environmental impact in all investigated impact categories. Depending on the impact category, the melt process or the acetone process rank second. The NMP process was observed to have the highest impact in all categories. Consequently, the flow process has the lowest carbon footprint (1.13 kg CO2-eq), according to the global warming potential (100 years), followed by the melt (1.45 kg CO2-eq), the acetone (1.95 kg CO2-eq) and the NMP process (3.11 kg CO2-eq).
Transforming Predictions into Testable Hypotheses: The Case of Polar Organic Reactivity
Authors: Proppe Jonny , Kircher Johannes
Published: March 2021

Herbert Mayr’s research on reactivity scales tells a success story of how polar organic synthesis can be rationalized by a simple empirical relationship. In this work, we propose an extension to Mayr’s reactivity approach that is rooted in uncertainty quantification (UQ). It transforms the unique values of reactivity parameters (sN, N, E) into value distributions. Through uncertainty propagation, these distributions can be exploited to quantify the uncertainty of bimolecular rate constants. Our UQ-based extension serves three purposes. First, predictions of polar organic reactivity can be transformed into testable hypotheses, which increases the overall reliability of the method and guides the exploration of new research directions. Second, it is also possible to quantify the discriminability of two competing reactions, which is particularly important if subtle reactivity differences matter. Third, since rate constant uncertainty can also be quantified for reactions that have yet to be observed, new opportunities arise for benchmarking computational chemistry methods (benchmarking under uncertainty). We demonstrate the functionality and performance of the UQ-extended reactivity approach at the example of the 2001/12 reference data set released by Mayr and co-workers [J. Am. Chem. Soc. 2001, 123, 9500; J. Am. Chem. Soc. 2012, 134, 13902]. As a by-product of the new approach, we obtain revised reactivity parameters for the electrophiles and the nucleophiles of the reference set.
Identification of Transthyretin Tetramer Kinetic Stabilizers That Are Capable of Inhibiting the Retinol-Dependent Retinol Binding Protein 4-Transthyretin Interaction
Authors: Cioffi Christopher L. , Raja Arun , Muthuraman Parthasarathy , Jayaraman Aravindan , Jayakumar Srinivasan , Varadi Andras , Racz Boglarka , Petrukhin Konstantin
Published: March 2021

Dissociation of transthyretin (TTR) tetramers may lead to misfolding and aggregation of pro-amyloidogenic monomers, which underlies TTR amyloidosis (ATTR) pathophysiology. ATTR is a progressive disease resulting from the deposition of toxic fibrils in tissues that predominantly presents clinically as amyloid cardiomyopathy and peripheral polyneuropathy. Ligands that bind to and kinetically stabilize TTR tetramers prohibit their dissociation and may prevent ATTR onset. Drawing from clinically investigated AG10, we designed a constrained congener (18a) that exhibits excellent TTR tetramer binding potency, prevents TTR aggregation in a gel-based assay, and possesses desirable pharmacokinetics in mice. Additionally, 18a significantly lowers murine serum retinol-binding protein 4 (RBP4) levels despite a lack of binding at that protein’s all-trans-retinol site. We hypothesize that kinetic stabilization of TTR tetramers via 18a is allosterically hindering all-trans-retinol-dependent RBP4-TTR tertiary complex formation and that the compound could present ancillary therapeutic utility for indications treated with RBP4 antagonists, such as macular degeneration.
Dioxygen Activation Kinetics over Distinct Cu Site Types in Cu-CHA Zeolites
Authors: Bregante Daniel , Wilcox Laura , Liu Changming , Paolucci Christopher , Gounder Rajamani , Flaherty David
Published: March 2021

Cu-exchanged zeolites activate dioxygen to form active sites for partial methane oxidation (PMO), nitrogen oxide decomposition, and carbon monoxide oxidation. Apparent rates of O2 activation depend both on the intrinsic kinetics of distinct Cu site types and the distributions of such sites within a given zeolite, which depend on the density and arrangement of the framework Al atoms. Here, we use hydrothermal synthesis methods to control the arrangement of framework Al sites in chabazite (CHA) zeolites and, in turn, the distinct Cu site types formed. Time-resolved in situ resonance Raman spectroscopy reveals the kinetics of O2 adsorption and activation within these well-defined Cu-CHA materials and the concomitant structural evolution of copper-oxygen (CuxOy) complexes, which are interpreted alongside Cu(I) oxidation kinetics extracted from in situ X-ray absorption spectroscopy (XAS). Raman spectra of several plausible CuxOy species simulated using density functional theory suggest that experimental spectra (λex = 532 nm) capture the formation of mono(μ-oxo)dicopper species (ZCuOCuZ). Transient experiments show that the timescales required to form CuxOy structures that no longer change in Ra-man spectra correspond to the durations of oxidative treatments that maximize CH3OH yields in stoichiometric PMO cycles (approximately 2 h). Yet, these periods extend well beyond the timescales for the complete conversion of the initial Cu(I) intermediates to their Cu(II) states (<0.3 h, reflected in XANES spectra), which demonstrates that CuxOy complexes continue to evolve structurally following rapid oxidation. The dependence of ZCuOCuZ formation rates on O2 pressure, H2O pressure, and temperature are consistent with a mechanism in which ZCuOH reduce to form ZCu+ sites that bind molecular oxygen and form ZCu-O2 intermediates. Subsequent reaction with proximate ZCu+ form bridging peroxo dicopper complexes that cleave O-O bonds to form ZCuOCuZ in steps facilitated by water. These data and interpretations provide evidence for the chemical processes that link rapid and kinetically irrelevant Cu oxidation steps (frequently probed by XAS and UV-Vis spectroscopy) to the relatively slow genesis of reactive Cu complexes that form CH3OH during PMO. In doing so, we reveal previously unrec-ognized complexities in the processes by which Cu ions in zeolites activate O2 to form active CuxOy complexes, which under-score the insight afforded by judicious combinations of experimental and theoretical techniques.
Anion Specific Effects Drive the Formation of Li-Salt Based Aqueous Biphasic Systems
Authors: Dubouis Nicolas , France-Lanord Arthur , Brige Amandine , Salanne Mathieu , Grimaud Alexis
Published: March 2021

Aqueous biphasic systems (ABS) can form when mixing water with two compounds such as polymers, ionic-liquids or simple salts. While this phenomenon has been known for decades and found applications in various fields such as biology, recycling or even more recently electrochemistry, the physics behind the formation of ABSs remains ill-understood. It was recently demonstrated that ABSs can be composed of two salts sharing the same cation (Li+) but different anions (sulfonamide and halide). Interestingly, their formation could not be explained by the position of the anions within the chaotropic/kosmotropic series and was rather proposed to originate from an anion size mismatch, albeit the size for these anions was never measured yet owing to the lack of a proper experimental methodology. Here, we combine experimental techniques and molecular simulations to assess the specific effects (size, shape, hydrophobic/hydrophilic character) of a series of anions and correlate them with the formation of ABSs. We demonstrate that while the anion size mismatch is a prerequisite for the formation of Li-salts based ABSs, their shape can also play an important role, providing general guidelines for forming new ABSs with potential future applications.
Sunflower-like Fluorescent Self-Assembled Morphologies Formed by Pyridothiazole Based Aggregation Induced Emission (AIE) Dye and Its Cell Imaging Applications
Authors: Kshtriya Vivekshinh , Koshti Bharti , Haque Ashadul , Gangrade Ankit , Singh Ramesh, , Joshi khashti Ballabh , Bandyopadhyay Sujoy , Bhatia Dhiraj , Gour Nidhi
Published: March 2021

We report for the very first-time self-assembly of 4-(5-methoxythiazolo[4,5-b]pyridin-2-yl)-N,N-dimethylaniline (TPA) to fluorescent sunflower-like architectures. Interestingly, TPA exhibits blue fluorescence in visible light at 385 nm and the fluorescence is not affected by photo-induced quenching rather the fluorescence keeps on increasing with time under broad day light. The morphologies of self-assembled structures of TPA were studied at various concentrations in dimethyl sulphoxide (DMSO) and Tetrahydrofuran (THF). The microscopic studies through SEM and fluorescence microscopy reveal the formation of sunflower-like fluorescent self-assemblies. Further, our study revealed that the sunflower shaped assemblies formed by TPA exhibitfluorescence under blue, green, and red channels that can be evinced by the fluorescence spectroscopy and microscopy. Hence TPA exhibits panchromatic emission properties and it reveals tunable emission properties under different excitation wavelengths. Further, AIE properties of TPA were evinced by recording fluorescence in THF under varying concentrations of water and doing solvent chromic studies.Finally,the utility of TPA as a cell imaging agent was studied in human breast cancer cell lines (MDA-MB-231) which suggested TPA can penetrate the cell membrane and can be effectively used as a cell labeling dye.
Multi-Catalytic Approach to One-Pot Stereoselective Synthesis of Secondary Benzylic Alcohols
Authors: Casnati Alessandra , Lichosyt Dawid , Lainer Bruno , Veth Lukas , Dydio Pawel
Published: March 2021

One-pot multi-step procedures bear the potential to rapidly build up molecular complexity while avoiding the wasteful and costly isolations and purifications of consecutive intermediates. Here we report multi-catalytic protocols that convert alkenes, unsaturated aliphatic alcohols, and aryl boronic acids into secondary benzylic alcohols with high stereoselectivities under sequential catalysis that integrates alkene cross-metathesis, isomerization, and nucleophilic addition. Because each transformation of the sequence is executed by an independent catalyst, without any catalytic cross-reactivity, allylic alcohols bearing a prochiral double bond can be converted to any stereoisomer of the product with high stereoselectivity (>98:2 er and >20:1 dr). Overall, with the aid of up to four catalysts operating in a single vessel, the protocols directly convert simple starting materials into a range of value-added products with high stereocontrol and excellent material efficiency, demonstrating both the efficacy and the advantages of the one-pot synthesis employing multiple transition-metal catalysts.
Synthesis of Single-Handed Helical Spiro-Conjugated Ladder Polymers through Quantitative and Chemoselective Cyclizations
Authors: Zheng Wei , Ikai Tomoyuki , Yashima Eiji
Published: March 2021

We report the unprecedented synthesis of one-handed helical spiro-conjugated ladder polymers with well-defined primary and secondary structures, in which the spiro-linkeddibenzo[a,h]anthracene fluorophores are arranged in a one-handed twisting direction, through quantitative and chemoselective acidpromoted intramolecular cyclizations of random-coil precursor polymers composed of chiral 1,1’-spirobiindane and achiral bis[2-(4-alkoxyphenyl)ethynyl]phenylene units. Intense circular dichroism (CD) and circularly polarized luminescence (CPL) were observed, whereas the precursor polymers exhibited negligible CD and CPL activities. The introduction of 2,6-dimethyl substituents on the 4- alkoxyphenylethynyl pendants is of key importance for this simple,quantitative, and chemoselective cyclization. This strategy is applicable to the defect-free precise synthesis of other varieties of fully p-conjugated molecules and coplanar ladder polymers that have not been achieved before.
Reaction on a Rink: Kondo-Enhanced Heterogeneous Single-Atom Catalysis
Authors: Li Xiangyang , Gong Hong , Zhuang Qingfeng , Wang Bing , Zheng Xiao , Yang Jinlong
Published: March 2021

Boosting the efficiency of heterogeneous single-atom catalysts (SACs) by adjusting the microenvironment of the active atom has recently attracted enormous attention. However, attempts to tune the spin-spin interaction between the SAC and its microenvironment have remained rather scarce. Some interesting questions can be raised, among which a fundamental one is: can the surrounding environment influence the local spin state of an SAC, and if so, can such influence be utilized to enhance the catalytic activity? In this work, we explore such a possibility by investigating the thermochemical effect of Kondo screening of a local atomic spin by free electrons in the metal support. Inspired by the exothermicity of the spin-screening interaction, a novel approach to heterogeneous catalysis -- reaction on a rink (ROAR) -- is proposed. In contrast to the conventional notion of thermal catalytic reaction, lowering the temperature of metal support is predicted to result in a reduced reaction barrier. As a proof of concept, CO oxidation catalyzed by the Co@CoPc/Au(111) composite is scrutinized. By combining the density functional theory and a hierarchical equations of motion approach, it predicts that the existing s-d hybridization between the magnetic d orbital of Co adatom and the substrate metallic states in the transition state will lower the free energy barrier and accelerate the reaction rate. Furthermore, if the strength of s-d hybridization is enlarged, a more appreciable speedup will be achieved. This work highlights the potential usefulness of the spin degrees of freedom to heterogeneous single-atom catalysis, and our proposed ROAR approach could open up a new horizon for exploiting the role of atomic spin in chemical reactions.
Polariton Induced Conical Intersection and Berry Phase
Authors: Farag Marwa , Mandal Arkajit , Huo Pengfei
Published: March 2021

We investigate the Polariton induced conical intersection (PICI) created from coupling a diatomicmolecule with the quantized photon mode inside an optical cavity, and the corresponding BerryPhase effects. We use the rigorous Pauli-Fierz Hamiltonian to describe the quantum light-matterinteractions between a LiF molecule and the cavity, and exact quantum propagation to investigatethe polariton quantum dynamics. The molecular rotations relative to the cavity polarization directionplay a role as the tuning mode of the PICI, resulting in an effective CI even within a diatomic molecule.To clearly demonstrate the dynamical effects of the Berry phase, we construct two additional modelsthat have the same Born-Oppenheimer surface, but the effects of the geometric phase are removed.We find that when the initial wavefunction is placed in the lower polaritonic surface, the Berryphase causes aπphase-shift in the wavefunction after the encirclement around the CI, indicatedfrom the nuclear probability distribution. On the other hand, when the initial wavefunction is placedin the upper polaritonic surface, the geometric phase significantly influences the couplings betweenpolaritonic states and therefore, the population dynamics between them. These BP effects are furtherdemonstrated through the photo-fragment angular distribution. PICI created from the quantizedradiation field has the promise to open up new possibilities to modulate photochemical reactivities.
Ground-State Electron Transfer as an Initiation Mechanism for Asymmetric Hydroalkylations in Radical Biocatalysis
Authors: Fu Haigen , Lam Heather , Emmanuel Megan , Kim Ji Hye , Sandoval Braddock , Hyster Todd K.
Published: March 2021

Stereoselective bond-forming reactions are essential tools in modern organic synthesis. However, catalytic strategies for controlling the stereochemical outcome of radical-mediated C–C bond formation remain underdeveloped. Here, we report an ‘ene’-reductase catalyzed asymmetric hydroalkylation of olefins using α-bromoketones as radical precursors. In these reactions, radical initiation occurs via ground-state electron transfer from the flavin cofactor located within the enzyme active site, representing a mechanistic departure from previous photoenzymatic hydroalkylations. Four rounds of site saturation mutagenesis based on wild-type nicotinamide-dependent cyclohexanone reductase (NCR) were deployed to access a variant capable of catalyzing a cyclization to furnish β-chiral cyclopentanones with high levels of enantioselectivity. Additionally, the wild-type NCR was identified that could catalyze the intermolecular coupling with precise stereochemical control over the radical termination step. This report demonstrates this enzyme family’s catalytic versatility and highlights the opportunity for protein engineering to address reactivity and selectivity challenges in radical biocatalysis.
Peering into Buried Interfaces with X-Rays and Electrons to Unveil MgCO3 Formation During CO2 Capture in Molten Salt Promoted MgO
Authors: Bork Alexander Hansen , Rekhtina Margarita , Willinger Elena , Castro-Fernández Pedro , Drnec Jakub , Abdala Paula M. , Müller Christoph
Published: March 2021

The addition of molten alkali metal salts drastically accelerates the kinetics of CO2 capture by MgO through the formation of MgCO3. However, the growth mechanism, the nature of MgCO3 formation and the exact role of the molten alkali metal salts on the CO2 capture process remains elusive, holding back the development of more effective MgO-based CO2 sorbents. Here, we unveil the growth mechanism of MgCO3 under practically relevant conditions using a well-defined, yet representative, model system that is a MgO(100) single crystal coated with NaNO3. The model system is interrogated by in situ X-ray reflectometry coupled with grazing incidence X-ray diffraction, scanning electron microscopy and high-resolution transmission electron microscopy. When bare MgO(100) is exposed to a flow of CO2, a non-crystalline surface carbonate layer of ca. 7 Å thickness forms. In contrast, when MgO(100) is coated with NaNO3 MgCO3 crystals nucleate and growth. These crystals have a preferential orientation with respect to the MgO(100) substrate, and form at the interface between MgO(100) and the molten NaNO3. MgCO3 grows epitaxially with respect to MgO(100) and the lattice mismatch between MgCO3 and MgO is relaxed through lattice misfit dislocations. Pyramid shaped pits on the surface of MgO, in the proximity and below the MgCO3 crystals, point to the etching of surface MgO, providing dissolved [Mg2+…O2–] ionic pairs for MgCO3 growth. Our studies highlight the importance of combining X-rays and electron microscopy techniques to provide atomic to micrometer scale insight into the changes occurring at complex interfaces under reactive conditions.
Pyrrole Hemithioindigo Antimitotics with Near-Quantitative Bidirectional Photoswitching Photocontrol Cellular Microtubule Dynamics with Single-Cell Precision
Authors: Sailer Alexander , Meiring Joyce , Heise Constanze , Pettersson Linda , Akhmanova Anna , Thorn-Seshold Julia , Thorn-Seshold Oliver
Published: March 2021

Photoswitchably bioactive reagents, known as “photopharmaceuticals”, promise powerful applications in high-precision biological research. Yet most photoswitch scaffolds cannot be quantitatively bidirectionally photoisomerised, so they suffer from residual background activity that can confound experiments. We rationally designed photopharmaceuticals using the emerging near-quantitative photoswitch pyrrole hemithioindigo (PHTubs), to isomer-specifically inhibit the cytoskeletal protein tubulin. These PHTub reagents allow simultaneous visible-light imaging and photoswitching in live cells, where they could be used for cell-precise photomodulation of microtubule dynamics, and photocontrol over cell cycle progression and cell death. This is, as far as we know, the first use of a hemithioindigo photopharmaceutical for high-spatiotemporal-resolution biological control in live cells. This work opens up new horizons for high-precision microtubule research using PHTubs; and shows the cellular applicability of the near-quantitative photoswitch pyrrole hemithioindigo as a valuable scaffold for photocontrol of a range of other biological targets.
Assessment of the Effect of Process Conditions and Material Characteristics of Alkali Metal Salt-Promoted MgO-Based Sorbents on Their CO2 Capture Performance
Authors: Chen Jian , Duan Lunbo , Donat Felix , Müller Christoph
Published: March 2021

CO2 capture using alkali metal salt (AMS)-promoted MgO-based sorbents at intermediate temperatures (300 – 500 °C) has gained increased interest recently. The prospects of such materials for CO2 capture were assessed in this work. We investigated the most reactive MgO-based sorbents that have been reported in the literature, i.e., MgO promoted with a combination of various AMS (incl. NaNO3, LiNO3, K2CO3 and Na2CO3), and examined how particle size (from powder to pelletized 500 μm particles) and reaction conditions (calcination/carbonation temperature, and partial pressure of CO2) affect the cyclic CO2 uptake using a thermogravimetric analyzer (TGA) at ambient pressure. The TGA results showed that the CO2 uptake of the sorbents decreased significantly after pelletization, losing 74 % of its initial capacity. However, the CO2 uptake capacity of the pelletized sorbents continued to increase over 100 cycles and reached a value (~ 0.46 gCO2/gsorbent) close to that of the powdery sample (~ 0.53 gCO2/gsorbent). Analysis via X-ray diffraction (XRD), inductively coupled plasma optical emission spectroscopy (ICP-OES), scanning electron microscope (SEM) and N2 physisorption suggests that the increase in CO2 uptake was related to a change of the nature of the alkali species within the molten phase that is reflected by their re-crystallization behavior when cooling them down to room temperature, and appeared to be affected by the CO2 partial pressure present during carbonation. Finally, the CO2 capture performance of the best-performing sorbents was evaluated in a packed bed reactor, in order to assess whether the most reactive sorbents are capable of removing a significant amount of CO2 from a gas stream at ambient pressure. The CO2 uptake of the sorbents in the packed bed experiments was very close to that in the TGA experiments; however, the CO2 capture efficiency was less than 10 %, which currently appears too low for an industrial post-combustion CO2 capture process to be viable. New material developments should not only focus on improving the rate of formation of MgCO3 from MgO, but also assess whether CO2 removal with such sorbents is actually feasible.
Structure illumination microscopy imaging of lipid vesicles in live bacteria with naphthalimide-appended organometallic complexes
Authors: Ranieri Anna Maria , Vezzelli Matteo , Leslie Kathryn , Huang Song , Stagni Stefano , Jacquemin Denis , Jiang Haibo , Hubbard Alysia , Rigamonti Luca , Watkin Elizabeth , Ogden Mark , New Elizabeth , Massi Massimiliano
Published: March 2021

There is a lack of molecular probes for imaging bacteria, in comparison to the array of such tools available for the imaging of mammalian cells. Here, organometallic molecular probes have been developed and assessed for bacterial imaging, designed to have the potential to support multiple imaging modalities. The chemical structure of the probes is designed around a metal-naphthalimide structure. The 4-amino-1,8-naphthalimide moiety, covalently appended through a pyridine ancillary ligand, acts as a luminescent probe for super-resolution microscopy. On the other hand, the metal centre, rhenium(I) or platinum(II) in the current study, enables techniques such as nanoSIMS. While the rhenium(I) complex was not sufficiently stable to be used as probe, the platinum(II) analogue showed good chemical and biological stability. Structured illumination microscopy (SIM) imaging on live Bacillus cereus confirmed the suitability of the probe for super-resolution microscopy. NanoSIMS analysis was used to monitor the uptake of the platinum(II) complex within the bacteria and demonstrate the potential of this chemical architecture to enable multimodal imaging. The successful combination of these two moieties introduces a platform that could lead to a versatile range of multi-functional probes for bacteria.
Arte chancay: reconstrucción ritual del mundo
Authors:   Centro Peruano de Arqueología Marítima y Subacuática (CPAMS), Cortéz Vicente
Published: March 2021

Pocas culturas prehispánicas presentan manifestaciones formales tan claras y definidas como la cultura chancay. La originalidad de su arte revela una cultura autónoma y coherente que, a pesar de ser ampliamente reconocida, mantiene aún el velo de su pasado distante y esquivo. Hoy nos identificamos con sus formas estéticas, pero estamos todavía lejos de comprender plenamente el sentido de sus representaciones. En el presente artículo, se esboza una interpretación de algunas expresiones de la realidad cultural de Chancay a través de su producción artística, vinculada principalmente con los ritos funerarios y el culto a los antepasados. Se ordenará el corpus de representaciones en función de los tres temas básicos presentes en el ritual funerario, a saber: el carácter divino del ancestro, la recreación ritual del entorno y la asignación de sentido a la muerte de un miembro de la sociedad. Dentro de este contexto, trataremos de entender las particularidades de los cánones artísticos y las convenciones estilísticas que definen su arte. De esta manera, la iconografía y la estética nos permitirán reconstruir las concepciones culturales que definen cada objeto y, a partir de ello, aproximarnos a la cosmovisión que dio forma y sentido a la vida de la sociedad chancay.
La sagrada obsesión por capturar al personaje. Un encuentro con el fotógrafo peruano Herman Schwarz
Authors:   Universidad de Lima, Rabí do Carmo Alonso
Published: March 2021

Esta entrevista ofrece a los lectores la mirada del artista sobre su propio trabajo. Esto abre no solamente una nueva perspectiva de análisis crítico del discurso o el objeto artístico (existe una marcada tendencia crítica a no considerar las palabras del artista), sino que, además, complementa otras miradas o lecturas posibles. En este caso, se trata de Herman Schwarz, un notable fotógrafo peruano que ha transitado con solvencia distintos campos durante los últimos cuarenta años, que van desde la fotografía documental hasta la poética del retrato, pasando por el uso de la imagen como herramienta social y documental. La voz del fotógrafo es la guía que irá descubriendo los pilares de su vocación y explicando al detalle las características de su discurso.
The effect of the local cold application on low back pain and vascular complications of patients undergoing coronary angiography
Authors: Fariba Ebrahimi-Shalmani  , Farideh Hasavari  , Salman Nikfarjam  , Ehsan Kazemnejad Leili  , Nazila Javadi-Pashaki
Published: March 2021

Coronary angiography due to the risk of vascular complications and low back pain development can lead to undesirable outcomes. This clinical trial was performed on 110 patients undergoing CAG through the femoral artery in 2019. Low back pain was assessed by VAS at baseline, 2, 4, 6 and 24 hours after angiography and vascular complications were investigated 9 times in this period. Results of group and time interaction analysis revealed that pain and vascular complications were significantly different between these two groups (P <0.001). After controlling for individual, clinical and technical variables, the scores of low back pain were associated with the intervention group compared to the control group (P <0.001), Body Mass Index (P=0/035) and INR (P <0.001). The extent of hematoma was associated with group (P = 0.003) and also the extent of ecchymosis was associated with group (P = 0.002), education (P = 0.44) and BMI (P = 0.035). In this study, the local cold was effective in back pain and vascular complications in patients undergoing CAG.