scholarly journals Homogeneous Catalytic C(sp3)–H Functionalization of Gaseous Alkanes

2021 ◽  
Author(s):  
Antonio Pulcinella ◽  
Daniele Mazzarella ◽  
Timothy Noel

The conversion of light alkanes into bulk chemicals is becoming an important challenge as it avoids effectively the use of prefunctionalized alkylating reagents. The implementation of such processes is, however,...

ARCHALP ◽  
2018 ◽  
pp. 126-137
Author(s):  
Marina Hämmerle

We cannot understand the development of Vorarlberg’s architectural culture without its spatial, topographical, and socio-economic context. There is a great contrast between rural valleys and the busy, semi-urban Rhine Valley. With their exemplary buildings, states and municipalities model the production of excellent, contemporary architecture. Industrial and commercial architecture has achieved an impressive corporate identity as well. However, we rarely find the same quality in residential construction. Because of the high cost of real estate and construction apartment buildings have grown up like mushrooms, intruding upon areas formerly predominated by detached housing. Urban sprawl has eliminated the borders between the 29 municipalities of the Rhine Valley, resulting in a giant suburban landscape. To remedy this process, the players cooperate with the regional authorities as they carry out their vision of urban planning, including guidelines and ideas. Because planning and production have become so complex, urban and regional development has turned into an immense challenge. Provincial and municipal authorities value openness, participation, common good, ecology, and sustainability and involve citizens and adapt the process to their needs. Still, they must consider subsidy rules and regulations, which, until now, have privileged private property over common good and have prioritized ecological standards over architectural quality and the concerns of urban planning. Since 1997, the Vorarlberg Architecture Institute, has inspired, challenged, and spoken for the architectural-cultural scene. It continues to mediate and complement the discourse and activities of the Central Association of the Architects of Vorarlberg. In addition, the Chamber of Architects strives to improve competition procedures. The Energy Institute Vorarlberg supports ecology and promotes sustainability. The Quality Association “vorarlberger_holzbaukunst” has promoted the renaissance of timber construction. Carpenters and architects actively support the prefabrication and development of new technical solutions. Similarly, the members of the Werkraum Bregenzerwald, a craftsmen’s association, continue and transform the cultural heritage in sophisticated and resource-friendly ways, as evidenced by many buildings and the “Werkraumhaus” itself. Vorarlberg’s hospitality industry plays an important role in supporting and promoting the architectural culture. However, thoughtful and coordinated master planning is necessary to expand the quality of individual architectural projects to urban and regional planning and construction. This transition will be the most important challenge for the period of urban densification. Vorarlberg may be Alpine – even rural – but it is urban without doubt.[English translation by Ingeborg Fink].


2020 ◽  
Vol 16 ◽  
Author(s):  
Kannappan Panchamoorthy Gopinath ◽  
Malolan Rajagopal ◽  
Abhishek Krishnan ◽  
Shweta Kolathur Sreerama

Background: Depletion and contamination of environmental resources such as water, air and soil caused by human activities is an increasingly important challenge faced around the world. The consequences of environmental pollution are felt acutely by all living beings, both on a short and long-term basis, thereby making methods of remediation of environmental pollution an urgent requirement. Objectives: The objective of this review is to dissect the complications caused by environmental degradation, highlight advancements in the field of nanotechnology and to scrutinize its applications in environmental remediation. Furthermore, the review aims to concisely explain the merits and drawbacks of nanotechnology compared to existing methods. Conclusion: The current and potential applications of nanomaterials and nanocomposites in the prevention, control and reduction of air, water and soil pollution and the mechanisms involved have been elucidated, as have their various merits and demerits. The applications of nanotechnology in the fields of carbon capture and agriculture have also received attention in this review.


Author(s):  
Ruth Weintraub

Scepticism about inference to the best explanation is far less often discussed than scepticism about another ampliative form of inference, enumerative induction. Both of these inference forms are widely used, and scepticism about either can pose an important challenge. This chapter aims to redress the imbalance by giving scepticism about inference to the best explanation the attention it, too, deserves. The chapter’s conclusion is that inference to the best explanation, even to the observable, may be in a worse epistemic position than enumerative induction. The reason for this is that there are sceptical arguments that target inference to the best explanation which do not have inductive analogues, but the converse is not true.


Author(s):  
Jean L. Cohen

We typically associate sovereignty with the modern state, and the coincidence of worldly powers of political rule, public authority, legitimacy, and jurisdiction with territorially delimited state authority. We are now also used to referencing liberal principles of justice, social-democratic ideals of fairness, republican conceptions of non-domination, and democratic ideas of popular sovereignty (democratic constitutionalism) for the standards that constitute, guide, limit, and legitimate the sovereign exercise of public power. This chapter addresses an important challenge to these principles: the re-emergence of theories and claims to jurisdictional/political pluralism on behalf of non-state ‘nomos groups’ within well-established liberal democratic polities. The purpose of this chapter is to preserve the key achievements of democratic constitutionalism and apply them to every level on which public power, rule, and/or domination is exercised.


2020 ◽  
Vol 74 (11) ◽  
pp. 866-870
Author(s):  
Lewis C. H. Maddock ◽  
Alan Kennedy ◽  
Eva Hevia

While fluoroaryl fragments are ubiquitous in many pharmaceuticals, the deprotonation of fluoroarenes using organolithium bases constitutes an important challenge in polar organometallic chemistry. This has been widely attributed to the low stability of the in situ generated aryl lithium intermediates that even at –78 °C can undergo unwanted side reactions. Herein, pairing lithium amide LiHMDS (HMDS = N{SiMe3}2) with FeII(HMDS)2 enables the selective deprotonation at room temperature of pentafluorobenzene and 1,3,5-trifluorobenzene via the mixed-metal base [(dioxane)LiFe(HMDS)3] (1) (dioxane = 1,4-dioxane). Structural elucidation of the organometallic intermediates [(dioxane)Li(HMDS)2Fe(ArF)] (ArF = C6F5, 2; 1,3,5-F3-C6H2, 3) prior electrophilic interception demonstrates that these deprotonations are actually ferrations, with Fe occupying the position previously filled by a hydrogen atom. Notwithstanding, the presence of lithium is essential for the reactions to take place as Fe II (HMDS)2 on its own is completely inert towards the metallation of these substrates. Interestingly 2 and 3 are thermally stable and they do not undergo benzyne formation via LiF elimination.


Author(s):  
Evelien Croonen ◽  
Hans van der Bij ◽  
Rozenn Perrigot ◽  
Assâad El Akremi ◽  
Olivier Herrbach

An important challenge for franchisors is to find individuals with strong intentions to become franchisees that they can actively support in this ambition. We contribute to franchising research by developing and testing a model to explain individual intentions to become franchisees as a specific type of entrepreneurial intention (EI). We combine Achievement Motivation Theory (AMT) with the Theory of Planned Behaviour (TPB) to propose inverted U-shaped associations between individual motivations (i.e. need for achievement and risk-taking propensity), their cognitive assessments of franchising (i.e. attitude towards franchising and perceived behavioural control), and their EI regarding franchising. Our survey of 666 individuals demonstrates that need for achievement impacts attitude towards franchising and perceived behavioural control regarding franchising following respectively inverted U-shaped and declining positive relationships, and they partly mediate the relationships between need for achievement and EI regarding franchising. We find a negative linear association with attitude towards franchising.


2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Max Borsche ◽  
Dirk Reichel ◽  
Anja Fellbrich ◽  
Anne S. Lixenfeld ◽  
Johann Rahmöller ◽  
...  

AbstractNeurological long-term sequelae are increasingly considered an important challenge in the recent COVID-19 pandemic. However, most evidence for neurological symptoms after SARS-CoV-2 infection and central nervous system invasion of the virus stems from individuals severely affected in the acute phase of the disease. Here, we report long-lasting cognitive impairment along with persistent cerebrospinal fluid anti-SARS-CoV-2 antibodies in a female patient with unremarkable standard examination 6 months after mild COVID-19, supporting the implementation of neuropsychological testing and specific cerebrospinal fluid investigation also in patients with a relatively mild acute disease phase.


2021 ◽  
Vol 50 (7) ◽  
pp. 4299-4358
Author(s):  
Yalan Wang ◽  
Ping Hu ◽  
Jia Yang ◽  
Yi-An Zhu ◽  
De Chen

This review describes the recent progress in computational catalysis that has addressed the C–H bond activation of light alkanes.


Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4466
Author(s):  
Pablo Domínguez de María

Nitriles comprise a broad group of chemicals that are currently being industrially produced and used in fine chemicals and pharmaceuticals, as well as in bulk applications, polymer chemistry, solvents, etc. Aldoxime dehydratases catalyze the cyanide-free synthesis of nitriles starting from aldoximes under mild conditions, holding potential to become sustainable alternatives for industrial processes. Different aldoxime dehydratases accept a broad range of aldoximes with impressive high substrate loadings of up to >1 Kg L−1 and can efficiently catalyze the reaction in aqueous media as well as in non-aqueous systems, such as organic solvents and solvent-free (neat substrates). This paper provides an overview of the recent developments in this field with emphasis on strategies that may be of relevance for industry and sustainability. When possible, potential links to biorefineries and to the use of biogenic raw materials are discussed.


Sign in / Sign up

Export Citation Format

Share Document