Creativity and organization are usually considered as contradictory or even paradoxical (e.g. DeFillippi et al., 2007), not only in the arts but also in the sciences. For creativity implies the creation of something novel and, at least potentially useful (Shalley et al., 2004) and, as such, is a necessary but not sufficient condition for innovation widely praised to guarantee the survival of organizations if not societies. Creativity is traditionally assumed to be fostered by individual freedom and slack resources. By contrast, organization – or organizing – with its emphasis on formality, rules, routines and systemness does not seem to foster but rather to hinder the unfolding of creativity in time and space. While temporary as well as partial forms of organizations are considered principally more supportive in this respect (Burke and Morely, 2016; Ahrne and Brunsson, 2018), I will argue in the following that any analysis of creative processes in and across organizations has to focus on both freedom and constraints – as well as on the tensions and contradiction arising from there, no matter whether these are of a truly paradoxical nature or not. Any process research on creativity, of a strong or more moderate nature (Fortwengel et al., 2017), should not only study “patterns in events” (Langley, 1999: 692) but focus on the interrelating of the two poles of the tensions, more appropriately conceived as a duality than a dualism. For Giddens (1984), whose work has been quite well received by economic geographers with respect to his concept of duality of structure and agency (e.g. Bathelt and Glückler, 2014), a duality is a melding of opposites. In more concrete terms, and following the definition by Graetz and Smith (2008), a duality comprises “the simultaneous presence of competing and ostensibly contradictory” (p. 270) properties, not unlike in a paradox. Ashforth and Reingen (2014), in a recent study of the relationships of idealist and pragmatists in a natural food cooperative, not only build on this definition and differentiation. Rather, these authors rightly emphasize that “the notions of ostensible contradiction and unified whole provide more conceptual space for exploring how the elements may in fact be complementary” (p. 475). With regard to such complementarities, or even supplementaries in a Derridean sense, including the more often than not productive role of (even self-imposed) constraints in creative processes (Ortmann and Sydow, 2018), we do need a more reflective and balanced account of organization and organizing – one which was already asked for by Adler and Borys (1996) more than two decades ago with regard to the enabling and constraining effects of bureaucratic structures. In fact, the four papers accepted for publication in this themed issue reflect to a large extent the long-needed move towards recognizing the importance of such a focus on tensions and contradictions as dualities (Farjoun, 2017). As correctly emphasized by Hautala and Ibert (2018) in their introduction to this theme issue these papers even share a processual approach to such dualities. In what follows, I will recap the tensions which not only of the four papers but also the commentary by Grabher (2018) address and inquire into exactly how they address them, for instance by unearthing the concepts these authors mobilize to theorize them. I will conclude that, from an organization theory perspective, economic geography seems on a good way to a more balanced and conflict-sensitive, even dialectical process understanding of creativity and organization that could well be pushed a bit further into this direction by not only considering tensions and contradictions as conditions and outcomes of organizing for creativity but also as important means. In addition, a more explicit study of tensions and contradictions and their role in creative processes in arts and sciences across different levels of analysis may be useful. At the same time, organization research has, despite some attempts to consider spatiality more seriously (e.g. Clegg and Kornberger, 2006), to learn a lot from economic geography about the multidimensional character of spatiality of creative processes.
Weniger anzeigenThis study aims to estimate the surface runoff and examine the impact of climate change on water resources in the Upper Kabul River Basin (UKRB). A hydrological model was developed using the Soil and Water Assessment Tool (SWAT) from 2009 to 2019. The monthly calibration was conducted on streamflow in six stations for the period from 2010 to 2016, and the results were validated from 2017 to 2018 based on available observed data. The hydrological sensitivity parameters were further prioritized using SWAT-CUP. The uncertainty of the model was analyzed by the 95% Prediction Uncertainty (95PPU). Future projections were analyzed for the 2040s (2030–2049) and 2090s (2080–2099) compared to the baseline period (1986–2005) under two representation concentration pathways (RCP4.5, RCP8.5). Four Regional Climate Models (RCMs) were bias-corrected using the linear scaling bias correction method. The modeling results exhibited a very reasonable fit between the estimated and observed runoff in different stations, with NS values ranging from 0.54 to 0.91 in the calibration period. The future mean annual surface runoff exhibited an increase in the 2040s and 2090s compared to the baseline under both RCPs of 4.5 and 8.5 due to an increase in annual precipitation. The annual precipitation is projected to increase by 5% in the 2040s, 1% in the 2090s under RCP4.5, and by 9% in the 2040s and 2% in the 2090s under RCP8.5. The future temperature is also projected to increase and consequently lead to earlier snowmelt, resulting in a shift in the seasonal runoff peak to earlier months in the UKRB. However, the shifts in the timing of runoff could lead to significant impacts on water availability and exacerbate the water stress in this region, decreasing in summer runoff and increasing in the winter and spring runoffs. The future annual evapotranspiration is projected to increase under both scenarios; however, decreases in annual snowfall, snowmelt, sublimation, and groundwater recharge are predicted in the UKRB.
Weniger anzeigenFrom 2016 to 2020, the “PraeRi” study, conducted by three German veterinary universities, was aimed at enhancing animal health and welfare in dairy farms. With 765 dairy farms visited and 101,307 animals examined, this study provided a basis for improving animal health and welfare. The study population comprised three different regions representing a broad variety of characteristics. To ensure representative estimates, a sample size of 250 farms was determined for each region, employing a stratified sampling plan based on farm size. According to the information provided by the farmers, the most commonly occurring disease in their herds was mastitis without general disorder (14.2% to 16.3% of the herd—depending on the region). For most disorders, prevalence data were lowest for the region South compared with the two remaining regions. Multivariable regression analyses were performed to identify risk factors for various target variables, and the results were communicated through individual reports and benchmarking flyers to participating farmers. The authors encountered challenges in management and communication due to the project’s size in terms of personnel, data, and farms examined. Harmonizing data management and hypothesis testing across all involved parties added complexity.
Weniger anzeigenCitrate-coated electrostatically stabilized very small superparamagnetic iron oxide particles (VSOPs) have been successfully tested as magnetic resonance angiography (MRA) contrast agents and are promising tools for molecular imaging of atherosclerosis. Their repeated use in the background of pre-existing hyperlipidemia and atherosclerosis has not yet been studied. This study aimed to investigate the effect of multiple intravenous injections of VSOPs in atherosclerotic mice. Taurine-formulated VSOPs (VSOP-T) were repeatedly intravenously injected at 100 µmol Fe/kg in apolipoprotein E-deficient (ApoE KO) mice with diet-induced atherosclerosis. Angiographic imaging was carried out by in vivo MRI. Magnetic particle spectrometry was used to detect tissue VSOP content, and tissue iron content was quantified photometrically. Pathological changes in organs, atherosclerotic plaque development, and expression of hepatic iron-related proteins were evaluated. VSOP-T enabled the angiographic imaging of heart and blood vessels with a blood half-life of one hour. Repeated intravenous injection led to VSOP deposition and iron accumulation in the liver and spleen without affecting liver and spleen pathology, expression of hepatic iron metabolism proteins, serum lipids, or atherosclerotic lesion formation. Repeated injections of VSOP-T doses sufficient for MRA analyses had no significant effects on plaque burden, steatohepatitis, and iron homeostasis in atherosclerotic mice. These findings underscore the safety of VSOP-T and support its further development as a contrast agent and molecular imaging tool.
Weniger anzeigenElectrochemical fluorination on nickel anodes, also known as the Simons’ process, is an important fluorination method used on an industrial scale. Despite its success, the mechanism is still under debate. One of the proposed mechanisms involves higher valent nickel species formed on an anode acting as effective fluorinating agents. Here we report the first attempt to study fluorination by means of first principles investigation. We have identified a possible surface model from the simplest binary nickel fluoride (NiF2). A twice oxidized NiF2(F2) (001) surface exhibits higher valent nickel centers and a fluorination source that can be best characterized as an [F2]− like unit, readily available to aid fluorination. We have studied the adsorption of CH4 and the co-adsorption of CH4 and HF on this surface by means of periodic density functional theory. By the adsorption of CH4, we found two main outcomes on the surface. Unreactive physisorption of CH4 and dissociative chemisorption resulting in the formation of CH3F and HF. The co-adsorption with the HF gave rise to four main outcomes, namely the formation of CH3F, CH2F2, CH3 radical, and also physisorbed CH4.
Weniger anzeigenmeso-Tetrahexylporphyrin was converted to its corresponding 7,8-dihydroxychlorin using an osmium tetroxide-mediated dihydroxylation strategy. Its diol moiety was shown to be able to undergo a number of subsequent oxidation reactions to form a chlorin dione and porpholactone, the first meso-alkylporphyrin-based porphyrinoid containing a non-pyrrolic building block. Further, the diol chlorin was shown to be susceptible to dehydration, forming the porphyrin enol that is in equilibrium with its keto-chlorin form. The meso-hexylchlorin dione could be reduced and it underwent mono- and bis-methylation reactions using methyl-Grignard reagents, and trifluoromethylation using the Ruppert-Prakash reagent. The optical and spectroscopic properties of the products are discussed and contrasted to their corresponding meso-aryl derivatives (where known). This contribution establishes meso-tetrahexyl-7,8-dihydroxychlorins as a new and versatile class of chlorins that is susceptible to a broad range of conversions to generate functionalized chlorins and a pyrrole-modified chlorin analogue.
Weniger anzeigenIncreased expression and nuclear translocation of β-CATENIN is frequently observed in breast cancer, and it correlates with poor prognosis. Current treatment strategies targeting β-CATENIN are not as efficient as desired. Therefore, detailed understanding of β-CATENIN regulation is crucial. Bone morphogenetic proteins (BMP) and Wingless/Integrated (WNT) pathway crosstalk is well-studied for many cancer types including colorectal cancer, whereas it is still poorly understood for breast cancer. Analysis of breast cancer patient data revealed that BMP2 and BMP6 were significantly downregulated in tumors. Since mutation frequency in genes enhancing β-CATENIN protein stability is relatively low in breast cancer, we aimed to investigate whether decreased BMP ligand expression could contribute to a high protein level of β-CATENIN in breast cancer cells. We demonstrated that downstream of BMP stimulation, SMAD4 is required to reduce β-CATENIN protein stability through the phosphorylation in MCF7 and T47D cells. Consequently, BMP stimulation reduces β-CATENIN levels and prevents its nuclear translocation and target gene expression in MCF7 cells. Conversely, BMP stimulation has no effect on β-CATENIN phosphorylation or stability in MDA-MB-231 and MDA-MB-468 cells. Likewise, SMAD4 modulation does not alter the response of those cells, indicating that SMAD4 alone is insufficient for BMP-induced β-CATENIN phosphorylation. While our data suggest that considering BMP activity may serve as a prognostic marker for understanding β-CATENIN accumulation risk, further investigation is needed to elucidate the differential responsiveness of breast cancer cell lines.
Weniger anzeigenThe paper explores the phenomenon of anonymous news channels on Russian Telegram, which have become increasingly popular in recent years. Drawing on 25 self-confrontation interviews, we answer the following questions: Do users trust anonymous news? If not, why do they keep using this information source? How does a restrictive socio-political context influence users’ trust in alternative news sources? Our results show that, in Russia, the concept of trust is linked to the normative democratic understanding of journalistic functions. At the same time, many users believe that trust in media is not at all necessary and develop individual strategies to navigate a “chaos of narratives”. The paper discusses Telegram’s role in shaping trust or distrust in news.
Weniger anzeigenIn recent years, the number of foodborne infections with non-O1 and non-O139 Vibrio cholerae (NOVC) has increased worldwide. These have ranged from sporadic infection cases to localized outbreaks. The majority of case reports describe self-limiting gastroenteritis. However, severe gastroenteritis and even cholera-like symptoms have also been described. All reported diarrheal cases can be traced back to the consumption of contaminated seafood. As climate change alters the habitats and distribution patterns of aquatic bacteria, there is a possibility that the number of infections and outbreaks caused by Vibrio spp. will further increase, especially in countries where raw or undercooked seafood is consumed or clean drinking water is lacking. Against this background, this review article focuses on a possible infection pathway and how NOVC can survive in the human host after oral ingestion, colonize intestinal epithelial cells, express virulence factors causing diarrhea, and is excreted by the human host to return to the environment.
Weniger anzeigenBackground: Cataracts resulting from equine recurrent uveitis (ERU) or other forms of uveitis are usually associated with rapid progression. ERU is the most common ocular disease cause of blindness and cause of cataracts in horses. The necessity for the posterior capsulorhexis (PC) during phacoemulsification (PE) is controversial. This study aimed to evaluate vision and complications after PE combined with pars plana vitrectomy (PPV) in horses with uveitis-associated cataracts and compare the PE technique with and without posterior capsulorhexis. Methods: Thirty-two eyes of 28 horses with uveitis-associated cataracts aged 14 months to 19.6 years were treated with PE-PPV under identical conditions. Twenty-three eyes of 21 horses were affected by an ERU-associated (ERU group), and nine eyes of 7 horses were affected by cataracts related to uveitis with pathogenesis different to ERU (non-ERU group). PE-PPV was performed in 12 eyes of 10 horses (PC group) and 20 eyes of 18 horses without posterior capsulorhexis (NPC group). Follow-up examination was performed at a mean of 1.7 ± 1.8 years postoperatively (range: 1 month–6.4 years). Results: In the period up to 1 month postoperatively, 17/20 (85%) NPC-eyes and 8/12 (67%) PC-eyes (total: 25/32 [78%]) were visual. From 1–6 months postoperatively, 16/20 (80%) NPC-eyes and 7/12 (58.3%) PC-eyes (total: 23/32 [72%]), and from 6–12 months, 7/11 (63.6%) NPC-eyes and 3/8 (37.5%) PC-eyes (total: 10/19 [52.6%]) were visual. From 12–18 months postoperatively, 3/7 (42.9%) NPC-eyes and 2/9 (22.2%) PC-eyes (total: 5/16 [31.3%]), and from 18–24 months, 3/8 (37.5%) NPC-eyes and 1/8 (12.5%) PC-eyes (total: 4/16 [25%]) were visual. After 24 months postoperatively, 2/7 (28.6%) NPC-eyes and 1/8 (12.5%) PC-eyes (total: 3/15 [20%]) were visual. Despite the higher number of visual eyes in the NPC group at each time point, differences were not significant. No obvious differences regarding postsurgical vision were observed between the ERU- and non-ERU groups at each time point. In the overall population, a significant decrease in the number of eyes with postoperative active uveitis was observed during the follow-up examinations (p < 0.001). A significant increase in the number of eyes that were blind due to retinal detachment was observed in the overall patient population as the examination period progressed (p < 0.001). Retinal detachment was the sole long-term cause of blindness. Conclusions: In horses diagnosed with uveitis-associated cataracts and treated with PE-PPV, no persistent active uveitis was observed in the present study during follow-up examinations. However, the proportion of eyes that were blind due to retinal detachment increased. Whilst PE-PPV may prevent postsurgical persistent active uveitis and remove lens opacity, the prognosis for a visual outcome is guarded. A superior outcome in postsurgical vision was observed in the NPC group. However, caution is required when interpreting these results due to several factors that affect the independent comparison of the surgical groups.
Weniger anzeigenOur study of German television content production firms entering the Hungarian market and other markets, and of U.S. firms entering the German market shows that foreign market entry in this industry often takes the form of network entry and, in some cases, collective network entry. The network orientation is the preferred strategy, to help firms cope with the often substantial “cultural discount” on their products. To interpret these observations, we extend the network approach of the Nordic school of international business research and distinguish between networks as a (relational) perspective and a form of governance. Our data show that, in this industry, different “market” entry strategies are implicated in network entry. Foreign market entry is a process that includes a dynamic mix of market, hierarchical, and network arrangements. Using ideas from Giddens’ (1984) structuration theory, we conceptualize foreign market entry as a process driven by the recursive interplay of knowledgeable agents and the social structure of organizational networks and fields.
Weniger anzeigenContext. Multiwavelength photometry of the secondary eclipses of extrasolar planets is able to disentangle the reflected and thermally emitted light radiated from the planetary dayside. Based on this, we can measure the planetary geometric albedo Ag, which is an indicator of the presence of clouds in the atmosphere, and the recirculation efficiency ϵ, which quantifies the energy transport within the atmosphere.
Aims. We measure Ag and ϵ for the planet WASP-178 b, a highly irradiated giant planet with an estimated equilibrium temperature of 2450 K.
Methods. We analyzed archival spectra and the light curves collected by CHEOPS and TESS to characterize the host WASP-178, refine the ephemeris of the system, and measure the eclipse depth in the passbands of the two telescopes.
Results. We measured a marginally significant eclipse depth of 70 ± 40 ppm in the TESS passband, and a statistically significant depth of 70 ± 20 ppm in the CHEOPS passband.
Conclusions. Combining the eclipse-depth measurement in the CHEOPS (λeff = 6300 Å) and TESS (λeff = 8000 Å) passbands, we constrained the dayside brightness temperature of WASP-178 b in the 2250–2800 K interval. The geometric albedo 0.1< Ag<0.35 generally supports the picture that giant planets are poorly reflective, while the recirculation efficiency ϵ >0.7 makes WASP-178 b an interesting laboratory for testing the current heat-recirculation models.
Weniger anzeigenWe validate the Transiting Exoplanet Survey Satellite (TESS) object of interest TOI-2266.01 (TIC 8348911) as a small transiting planet (most likely a super-Earth) orbiting a faint M5 dwarf (V = 16.54) on a 2.33 d orbit. The validation is based on an approach where multicolour transit light curves are used to robustly estimate the upper limit of the transiting object's radius. Our analysis uses SPOC-pipeline TESS light curves from Sectors 24, 25, 51, and 52, simultaneous multicolour transit photometry observed with MuSCAT2, MuSCAT3' and HiPERCAM, and additional transit photometry observed with the LCOGT telescopes. TOI-2266 b is found to be a planet with a radius of 1.54 ± 0.09 R⊕, which locates it at the edge of the transition zone between rocky planets, water-rich planets, and sub-Neptunes (the so-called M dwarf radius valley). The planet is amenable to ground-based radial velocity mass measurement with red-sensitive spectrographs installed in large telescopes, such as MAROON-X and Keck Planet Finder (KPF), which makes it a valuable addition to a relatively small population of planets that can be used to probe the physics of the transition zone. Further, the planet's orbital period of 2.33 days places it inside a ‘keystone planet’ wedge in the period-radius plane where competing planet formation scenarios make conflicting predictions on how the radius valley depends on the orbital period. This makes the planet also a welcome addition to the small population of planets that can be used to test small-planet formation scenarios around M dwarfs.
Weniger anzeigenBackground
Migratory birds generally have tightly scheduled annual cycles, in which delays can have carry-over effects on the timing of later events, ultimately impacting reproductive output. Whether temporal carry-over effects are more pronounced among migrations over larger distances, with tighter schedules, is a largely unexplored question.
Methods
We tracked individual Arctic Skuas Stercorarius parasiticus, a long-distance migratory seabird, from eight breeding populations between Greenland and Siberia using light-level geolocators. We tested whether migration schedules among breeding populations differ as a function of their use of seven widely divergent wintering areas across the Atlantic Ocean, Mediterranean Sea and Indian Ocean.
Results
Breeding at higher latitudes led not only to later reproduction and migration, but also faster spring migration and shorter time between return to the breeding area and clutch initiation. Wintering area was consistent within individuals among years; and more distant areas were associated with more time spent on migration and less time in the wintering areas. Skuas adjusted the period spent in the wintering area, regardless of migration distance, which buffered the variation in timing of autumn migration. Choice of wintering area had only minor effects on timing of return at the breeding area and timing of breeding and these effects were not consistent between breeding populations.
Conclusion
The lack of a consistent effect of wintering area on timing of return between breeding areas indicates that individuals synchronize their arrival with others in their population despite extensive individual differences in migration strategies.
Weniger anzeigenComplex technologies are often developed in inter-organisational networks as actors try to reduce development costs and uncertainty about the viability of these innovations. However, as of to date it remains unclear how such innovations are financed collectively under conditions characterised by extreme uncertainty. Hence we explore how financial resources within innovation networks are mobilised and allocated. This question is of particular importance to the development of system technologies that are viable only if all critical components are functional on time. We explore this issue by reviewing the development of a radically new system technology for mass manufacturing microchips in the semiconductor industry. In this industry, technological roadmaps allow actors to identify critical components that still need to be developed. These components are the so-called roadmap gaps. However, suppliers can be reluctant to develop the required components at their own expense because of the high uncertainties involved. In such cases, providing financial support to component suppliers is a central task of innovation networks. The empirical analysis shows that semiconductor manufacturers take both an individual and a collective approach to filling roadmap gaps. This study contributes to prior research on innovation networks and financial management not only by identifying and clarifying these two approaches, but also by revealing under which conditions they are used. The findings are particularly relevant to scholars interested in the innovations of complex product systems (CoPS).
Weniger anzeigenBackground: The COVID-19 pandemic caused multiple stressors that may lead to symptoms of adjustment disorder.
Objective: We longitudinally examined relationships between risk and protective factors, pandemic-related stressors and symptoms of adjustment disorder during the COVID-19 pandemic, as well as whether these relationships differed by the time of assessment.
Method: The European Society for Traumatic Stress Studies (ESTSS) ADJUST Study included N = 15,169 participants aged 18 years and above. Participants from 11 European countries were recruited and screened three times at 6-month intervals from June 2020 to January 2022. Associations between risk and protective factors (e.g. gender), stressors (e.g. fear of infection), and symptoms of adjustment disorder (AjD, ADNM-8) and their interaction with time of assessment were examined using mixed linear regression.
Results: The following predictors were significantly associated with higher AjD symptom levels: female or diverse gender; older age; pandemic-related news consumption >30 min a day; a current or previous mental health disorder; trauma exposure before or during the pandemic; a good, satisfactory or poor health status (vs. very good); burden related to governmental crisis management and communication; fear of infection; restricted social contact; work-related problems; restricted activity; and difficult housing conditions. The following predictors were associated with lower AjD levels: self-employment or retirement; working in healthcare; and face-to-face contact ≥ once a week with loved ones or friends. The effects of the following predictors on AjD symptoms differed by the time of assessment in the course of the pandemic: a current or previous mental disorder; burden related to governmental crisis management; income reduction; and a current trauma exposure.
Conclusions: We identified risk factors and stressors predicting AjD symptom levels at different stages of the pandemic. For some predictors, the effects on mental health may change at different stages of a pandemic.
Weniger anzeigenBackground
Suicidal ideation is a major concern in clinical practice. Yet, little is known about prevalence rates of suicidal ideation in patients undergoing outpatient psychotherapeutic treatment. Therefore, the aim of the current study is to assess the prevalence of suicidal ideation in a large sample of psychotherapy outpatients in Germany. The data analyzed in this study is taken from the KODAP-project on the coordination of data collection and analysis at German university-based research and training outpatient clinics for psychotherapy.
Methods
A total of N = 10,357 adult outpatients (64.4 % female; age: M(SD) = 35.94 (13.54), range: 18–92 years of age) starting cognitive-behavioral therapy at one of 27 outpatient clinics in Germany were included in the current study. Prevalence of suicidal ideation was assessed with the Suicide Item (Item 9) of the Beck-Depression Inventory II.
Results
Suicidal ideation was reported by 36.7 % (n = 3795) of the participants. Borderline Personality Disorder, Posttraumatic Stress Disorder, and recurrent Major Depression were the diagnoses most strongly associated with the presence and severity of suicidal ideation.
Limitation
Suicide ideation was assessed only with the respective item of the Beck Depression Inventory II.
Conclusion
Suicidal ideation is very common among adult patients who start psychotherapy in Germany. A well-founded knowledge of risk assessment in suicidal patients and suicide-specific treatment options is therefore highly relevant.
Weniger anzeigenThis work reviews possible signatures and potential detectability of present-day volcanically emitted material in the atmosphere of Venus. We first discuss the expected composition of volcanic gases at present time, addressing how this is related to mantle composition and atmospheric pressure. Sulfur dioxide, often used as a marker of volcanic activity in Earth’s atmosphere, has been observed since late 1970s to exhibit variability at the Venus’ cloud tops at time scales from hours to decades; however, this variability may be associated with solely atmospheric processes. Water vapor is identified as a particularly valuable tracer for volcanic plumes because it can be mapped from orbit at three different tropospheric altitude ranges, and because of its apparent low background variability. We note that volcanic gas plumes could be either enhanced or depleted in water vapor compared to the background atmosphere, depending on magmatic volatile composition. Non-gaseous components of volcanic plumes, such as ash grains and/or cloud aerosol particles, are another investigation target of orbital and in situ measurements. We discuss expectations of in situ and remote measurements of volcanic plumes in the atmosphere with particular focus on the upcoming DAVINCI, EnVision and VERITAS missions, as well as possible future missions.
Weniger anzeigenContamination of water bodies is a global environmental and human health issue. Conventional water treatment systems cannot efficiently eliminate organic contaminants, particularly drugs. Photocatalysis is a promising, environmentally friendly oxidation process for the removal of such compounds. A key point is the choice of material to be used as photocatalyst. Here, TiO2/CaTiO3/Cu2O/Cu composites were fabricated by adding different amounts (x) of graphene oxide (GO) (x wt% = 1, 3, and 5 %) to CaCu3Ti4O12 powder using the solid-state synthesis method. The produced pellets were sintered under inert nitrogen atmosphere at 1100 °C for 3 h. X-ray diffraction analysis showed that the Cu metal amount was increased upon GO addition, and the UV–Vis diffuse reflectance spectroscopy showed that the spectral response was extended to the visible range. Then, high performance liquid chromatography assessment of paracetamol degradation by a photocatalytic cell using TiO2/CaTiO3/Cu2O/Cu composites with different GO amounts showed that the removal efficiency was increased upon introduction of 0.5 mM peroxymonosulfate (PMS) as active component to generate radical dotSO4‾ radicals. After 3 h under visible light, 96 % of 10 ppm paracetamol was degraded by the composite with 3 % of GO (1 cm2 surface photocatalyst) compared with 50 % by the composite without GO in the same experimental conditions (PMS in 210 mL of aqueous solution). Free radical trapping and the acute toxicity of potential degradation by-products were also investigated. Our results indicate that TiO2/CaTiO3/Cu2O/Cu with 3 % GO displays long-term stability and durability for the photocatalytic removal of pharmaceutical pollutants from wastewater.
Weniger anzeigenMuch attention has been paid to dynamical simulation and quantum machine learning (QML) independently as applications for quantum advantage, while the possibility of using QML to enhance dynamical simulations has not been thoroughly investigated. Here we develop a framework for using QML methods to simulate quantum dynamics on near-term quantum hardware. We use generalization bounds, which bound the error a machine learning model makes on unseen data, to rigorously analyze the training data requirements of an algorithm within this framework. Our algorithm is thus resource efficient in terms of qubit and data requirements. Furthermore, our preliminary numerics for the XY model exhibit efficient scaling with problem size, and we simulate 20 times longer than Trotterization on IBMQ-Bogota.
Weniger anzeigen