Bent's Rule Research Articles

Electronegativity Effects on Conformational Stability Using Bent's Rule: From Simple Molecules to Acetylcholine

Hybridization and electronegativity are fundamental concepts in chemistry connected by Bent's rule. This rule explains many aspects of the structural chemistry and reactivity of organic and inorganic compounds. Over decades, the application of Bent's rule has expanded, demonstrating its wide-ranging utility in elucidating molecular stability due to the substitution of highly electronegative atoms. This study successfully leverages Bent's rule to explain conformational energy difference in acetylcholine case using density-functional calculations. We used butane (Group 2) and butanone (Group 3) families to model the head of ACh+ and substituted one of the carbons with highly electronegative atoms: B, C, N, and O. This enabled us to evaluate the effects of electronegativity, as well as the presence of carbonyl groups, on their conformational stability and s character. There were three highlighted results. First, our calculations result in the s character are consistent with Bent's rule. Second, the high conformational energy differences can be attributed to the changes of s character in C2–Z bond: linear in Group 2 and exponential in Group 3, indicating the strong contribution of the carbonyl group. Third, the key determining factor in ACh+ conformational stability is the carbonyl group, which also strongly contributes to the solute-solvent interactions. Therefore, our study can be further applied to other similar molecules, potentially leading to broader applications in chemistry, especially for understanding ACh+ stability for Alzheimer’s Disease treatment.

Deciphering the Differential Origin of Hydrogen Bonds in the Normal and Tautomer Forms of 7‐Azaindole:Piperidin‐2‐one Hydrogen‐Bonded Complex: Excited‐State Double Proton Transfer

AbstractThe excited‐state double proton transfer (ESDPT) reaction in the intermolecular hydrogen‐bonded complex 7‐azaindole:piperidin‐2‐one is investigated by quantum chemical calculations with particular emphasis on the H‐bonding interactions within the system. The natural bond orbital (NBO) calculations show that the X─H···Y H‐bonds in the studied complexes, namely, 7‐azaindole:piperidin‐2‐one (N‐form) and 7H‐pyrrolo[2,3‐b]pyridine:3,4,5,6‐tetrahydropyridin‐2‐ol (T‐form, proton transferred tautomer) are aptly described by hyperconjugative charge transfer effect ( is non‐bonded lone‐pair on Y‐atom). That the hyperconjugation effect outplays the rehybridization effect is invoked to account for the observed red‐shifting H‐bonds in harmony with the Bent's rule. The differential nature of interactions underlying the origin of X─H···Y H‐bonds in the complexes (N‐form and T‐form) is explored from atoms‐in‐molecules (AIM) calculations. The H‐bonds in the N‐form are found to have a primarily electrostatic origin (closed‐shell interaction) whereas the relatively stronger H‐bonds in the T‐form are assisted by contribution from shared‐shell (covalent) interaction. The nonoccurrence of the double‐proton transfer reaction in the S0 state is argued from the large barrier for the transformation N‐form → T‐form (N‐form constitutes the global minimum on the S0‐PEC), whereas the stability order is reversed together with a marked reduction of the energy barrier in the S1‐PEC accounting for the ESDPT process.

Blue- and Red-Shifting C-H⋯O Hydrogen Bonds of Cyclic Ethers with Haloforms: Effect of Ring-Size and Consistency with Bent's Rule.

A DFT-based computational study is carried out to delve into the interplay between hyperconjugation and rehybridization effects underlying the formation of blue- or red-shifting H-bonds (HBs) in 1 : 1 complexes of cyclic ethers (HB acceptor) of varying ring-size with haloforms, CHF3 and CHCl3 (HB donor). The calculations reveal that with decreasing angular strain (increasing ring-size) of the cyclic ethers, the extent of blue-shift increases for 1 : 1 complexes with CHF3, while a reverse sequence is observed with CHCl3, eventually leading to a red-shifting HB in the oxepane : CHCl3 complex. It is noted that the trend in the shift of C-H stretching fundamental is not mirrored by the C-H bond length or interaction energies for both the systems studied, that is, the low sensitivity of the changes on the strain on the O-atom of HB acceptor (cyclic ethers) is to be emphasized.

Role distance. An ethnographic study on how street-level managers cope

Abstract Policy is not only made by street-level bureaucrats at the frontlines. It is also made by their superiors—street-level managers—who set the organizational conditions through which street-level bureaucrats act. Although scholars have documented how street-level bureaucrats cope with the pressures of their work by, for instance, breaking or bending rules, the question of how street-level managers cope with the pressures of their own work has received less attention. Drawing from ethnographic data of a network of publicly funded health centers in the Midwestern US, I show how street-level managers use an interaction ritual with role distance to cope. Role distance is mobilized when the person uses communicative expressions such as laughter or cries of frustration to convey a critical distance from what her organizational role prescribes. Based on classic sociological insights, I posit that role distance can function as follows. It can help managers preserve self by allowing them to define their putatively “more-human self” from their work, create a feeling of collectiveness as they orient themselves to the shared frustrations yet obligations that their role engenders, which enables them to coordinate on carrying out tasks, even those that rub against their preferences and well-intentions. Taken together, I suggest that role distance can offer a coping function, which enables them to hold in abeyance individual and collective responsibility for the decisions they make. I then highlight the benefits and unintended consequences of role distance and posit what academics and practitioners can do to ensure that street-level managers use role distance toward more productive ends.

Qualitative Interviews to Add Patient Perspectives in Colorectal Cancer Screening: Improvements in a Learning Health System.

Health systems are interested in increasing colorectal cancer (CRC) screening rates as CRC is a leading cause of preventable cancer death. Learning health systems are ones that use data to continually improve care. Data can and should include qualitative local perspectives to improve patient and provider education and care. This study sought to understand local perspectives on CRC screening to inform future strategies to increase screening rates across our integrated health system. Health insurance plan members who were eligible for CRC screening were invited to participate in semi-structured phone interviews. Qualitative content analysis was conducted using an inductive approach. Forty member interviews were completed and analyzed. Identified barriers included ambivalence about screening options (e.g., "If it had the same performance, I'd rather do home fecal sample test. But I'm just too skeptical [so I do the colonoscopy]."), negative prior CRC screening experiences, and competing priorities. Identified facilitators included a positive general attitude towards health (e.g., "I'm a rule follower. There are certain things I'll bend rules. But certain medical things, you just got to do."), social support, a perceived risk of developing CRC, and positive prior CRC screening experiences. Study findings were used by the health system leaders to inform the selection of CRC screening outreach and education strategies to be tested in a future simulation model. For example, the identified barrier related to ambivalence about screening options led to a proposed revision of outreach materials that describe screening types more clearly.

Experimental Study on Double-Joint Soft Actuator and Its Dexterous Hand.

In this paper, we propose a pneumatic double-joint soft actuator based on fiber winding and build a dexterous hand with 11 degrees of freedom. Firstly, soft actuator structural design is carried out according to the actuator driving principle and gives the specific manufacturing process. Then, an experimental analysis of the bending performance of a single soft actuator, including bending angle, speed, and force magnitude, is carried out by building a pneumatic control experimental platform. Finally, a series of dexterous robotic hand-grasping experiments is conducted. Different grasping methods are used to catch the objects and measure the objects' change in height, length, and rotation angle during the experiment. The results show that the proposed soft actuator is more consistent with the bending rule of human fingers, and that the gestures of the dexterous hand are more imaginable and flexible when grasping objects. The soft actuator can carry out horizontal and vertical movements, and rotation of the object in the dexterous hand, thus achieving better human-computer interaction.

Conceptualizing the bending and breaking of rules in the heavy goods transport sector

Heavy goods vehicles (HGVs) are a critical factor in road traffic safety for “Vision Zero-events”, defined as road accidents with fatalities and serious injuries. The bending and breaking of safety-related rules in the HGV-sector, such as not following rest and work hour regulations, not securing cargo sufficiently, or not following the regulations concerning cabotage, in the commercial goods transport sector is a cause for concern and has in a very limited degree been studied as a system problem. This paper suggests that deregulation and international competition in the transport sector are bringing about a working climate where even serious safety-minded actors in the HGV business find themselves needing to cut corners to stay in business. The current situation in the Norwegian HGV sector is such that the organization of the business, the market development and the regulatory regimes are in effect transferring the responsibility for traffic safety vertically downwards to the actors at the lowest levels of the transport system. These actors are the truck drivers, who often bend and break rules to perform their work on time. This paper presents a scoping study designed to address the concept of rule bending in the HGV transport sector, using a combination of peer reviewed literature and a heterogeneous sample of grey literature from the transport sector. The scoping study shows how the scientific literature discusses violations and transgressions as both intentional and nonintentional acts but does not adequately describe how certain types of behaviour differ from overt violations and transgressions. The actions are simply considered violations that are devoid of meaning and both systemic and cultural context. We suggest a conceptualization of rule bending and rule breaking as “Adaptive Non-conforming Behaviour (ANB)” that builds on the context found in the grey literature. Further, the conceptualization provides a framework for the recognition of ANB, dimensions for further study and an outlined research design. We believe there is a need to increase system knowledge because safety analysis lacks in-depth insight into how the system affect the working practices in the HGV sector. The justification of the ANB approach is that it can be incorporated into safety and risk assessments of the transport sector, to provide a framework for context-sensitive studies that are non-normative, less concerned with violations as rule breaking, and more concerned with rule bending as a system wide problem.

Something’s Gotta Give: Bent Rules, Breached Bottom Line, and the International Amateur Athletics Federations’ Handling of the “China Question”

International Sport Federations, as part of the Olympic network, have different organizational structures and decision-making mechanisms from the International Olympic Committee. The authors, in examining the history of the International Amateur Athletics Federations’ (IAAF) handling of the “China question” in international sport, probe how these differences translated into the IAAF’s organizational politics and power dynamics in face of governmental interference. Primarily examining archival documents obtained from the IAAF Archive and the International Olympic Committee Historical Archives, the authors particularly follow how the self-governing IAAF upheld, bent, and modified its statutes during its engagement with the People’s Republic of China from the 1950s to the 1970s and around its eventual admission of the People’s Republic of China’s Athletics Association in 1978. It is also argued that the IAAF’s engagement and inclusion of the People’s Republic of China allowed the consolidation of its monopolizing power in global athletics governance.

Visible Light Photoredox-Catalyzed Decarboxylative Alkylation of 3-Aryl-Oxetanes and Azetidines via Benzylic Tertiary Radicals and Implications of Benzylic Radical Stability

Four-membered heterocycles offer exciting potential as small polar motifs in medicinal chemistry but require further methods for incorporation. Photoredox catalysis is a powerful method for the mild generation of alkyl radicals for C-C bond formation. The effect of ring strain on radical reactivity is not well understood, with no studies that address this question systematically. Examples of reactions that involve benzylic radicals are rare, and their reactivity is challenging to harness. This work develops a radical functionalization of benzylic oxetanes and azetidines using visible light photoredox catalysis to prepare 3-aryl-3-alkyl substituted derivatives and assesses the influence of ring strain and heterosubstitution on the reactivity of small-ring radicals. 3-Aryl-3-carboxylic acid oxetanes and azetidines are suitable precursors to tertiary benzylic oxetane/azetidine radicals which undergo conjugate addition into activated alkenes. We compare the reactivity of oxetane radicals to other benzylic systems. Computational studies indicate that Giese additions of unstrained benzylic radicals into acrylates are reversible and result in low yields and radical dimerization. Benzylic radicals as part of a strained ring, however, are less stable and more π-delocalized, decreasing dimer and increasing Giese product formation. Oxetanes show high product yields due to ring strain and Bent's rule rendering the Giese addition irreversible.

Coping with political interference and resource scarcity: Governance in the former tribal regions of Pakistan

Design and delivery of public services in the global south remain woefully understudied. This is especially the case with newly institutionalized regions enmeshed in economic, social, and security challenges. Public administration literature recommends that regions facing wicked problems must rely on effective governance but offer little insight into the specificities of the problems faced by implementers and the prevailing means to tackle them. In this exploratory qualitative study, we focus our attention on studying governance in the understudied context of the tribal areas in the mountainous northwestern regions of Pakistan. We apply Lipsky’s street-level bureaucracy framework to learn how frontline public employees working in these regions cope with the identified challenges of political interference and resource scarcity. Our findings demonstrate that public employees in the former tribal regions of Pakistan bend and break rules, engage in corruption, and shirk responsibilities to cope with challenges and meet performance expectations. The findings underscore the need for more contextualized institution-building such that frontline public workers are more answerable to citizens than to those who undermine the democratic imperative of these critical public infrastructure projects.

Prosocial rule breaking, ingroups and social norms: Parental decision-making about COVID-19 rule breaking in the UK.

The British public generally adhered to COVID‐19‐related restrictions, but as the pandemic drew on, it became challenging for some populations. Parents with young children were identified as a vulnerable group. We collected rich, mixed‐methods survey data from 99 UK‐based parents (91 mothers) of children under 12, who described their lockdown transgressions. Household mixing was the most prevalent broken rule. Template analysis found that rule breaking was driven by ‘ingroup‐level’ prosocial motivations to protect the mental and social health of family and loved ones, and that parents were ‘engaged’ decision‐makers who underwent careful deliberation when deciding to break rules, making trade‐offs, bending rules, mitigating risks, reaching consensus, and reacting to perceived rule injustices. Cumulative link models found that the perceived reasonableness of rule violations was predicted by social norms. Rules were broken by parents not for antisocial reasons, but for ‘ingroup‐level’ prosocial reasons, linked to supporting loved ones.

Exploring the COVID-19 pandemic experience of maternity clinicians in a high migrant population and low COVID-19 prevalence country: A qualitative study

BackgroundAustralia experienced a low prevalence of COVID-19 in 2020 compared to many other countries. However, maternity care has been impacted with hospital policy driven changes in practice. Little qualitative research has investigated maternity clinicians’ perception of the impact of COVID-19 in a high-migrant population. AimTo investigate maternity clinicians’ perceptions of patient experience, service delivery and personal experience in a high-migrant population. MethodsWe conducted semi-structured in-depth interviews with 14 maternity care clinicians in Sydney, New South Wales, Australia. Interviews were conducted from November to December 2020. A reflexive thematic approach was used for data analysis. FindingsA key theme in the data was ‘COVID-19 related travel restrictions result in loss of valued family support for migrant families’. However, partners were often ‘stepping-up’ into the role of missing overseas relatives. The main theme in clinical care was a shift in healthcare delivery away from optimising patient care to a focus on preservation and safety of health staff. DiscussionClinicians were of the view migrant women were deeply affected by the loss of traditional support. However, the benefit may be the potential for greater gender equity and bonding opportunities for partners.Conflict with professional beneficence principles and values may result in bending rules when a disconnect exists between relaxed community health orders and restrictive hospital protocols during different phases of a pandemic. ConclusionThis research adds to the literature that migrant women require individualised culturally safe care because of the ongoing impact of loss of support during the COVID-19 pandemic.

Confronting a Compound Crisis: The School Principal’s Role During Initial Phase of the COVID-19 Pandemic

The COVID-19 pandemic, bringing to the forefront and catalyzing long-unconfronted racial and economic inequities, in addition to economic collapse and deep political divisions - which all impact students and schools – has resulted in a compound crisis requiring a novel conceptualization of school leadership during times of crisis. This qualitative study captures the leadership experience of principals during the apocalyptic crisis _ the COVID-19 pandemic - beginning from the time schools were closing in March 2020 to the end of the school year in June. Crisis leadership, transformative leadership and social capital constitute the overarching framework for this study. The purpose of this case study was to discover how principals engaged in their thinking and practice to handle the compound crisis, in order to generate a rich description and gain an understanding of school leadership during the first phase of the COVID 19 pandemic. Our research questions were: What were the challenges and complications of leading during the initial phase of the compound crisis from the perspective of principals? How did principals respond? What were the emergent leadership practices? For this case study, we used a purposeful, maximum variation sample of nine principals in Florida. We sought balance in gender, race and ethnicity, and grade level. In-depth interviews were conducted using a structured protocol. Analysis treated each principal as an individual case, then cross-case thematic analysis was employed to uncover common patterns and themes. Three findings emerged. First, participants drew upon their individual reservoirs of shared leader qualities, including personalized and pragmatic communicator; leading with flexibility, creativity and care; bending rules and shifting priorities; and showing resilience under pressure. Second, they tapped into their schools’ strengths, including school context and in-house expertise. Third, they made inter-school connections. The first phase of the compound crisis pushed principals to prioritize care, safety, and wellbeing of students, teachers, and communities above accountability measures and systemic institutional constraints. A call to action for equity is the next logical step for system consideration, and was echoed by participating principals, as well as a realization that going back to old ways is no longer an option.

Optimal design of tapered composite structures with a dynamic boundary subset blending model

Based on the classical bending rule that the plies composing the thinner region should be a subset of the ones of the thicker region for two adjacent laminates, a genetic algorithm–based dynamic boundary subset blending model is proposed to optimize the global stacking sequence of composite structures with ply-drops. Besides the stacking sequence chromosome of the guide laminate and ply number chromosome of each panel, a chromosome of a dynamic boundary subset factor is introduced for each panel to obtain a fully blended design. The lower and upper bounds of the dynamic boundary subset factor chromosome for each panel is determined by the ply number chromosomes of the panel and its adjacent panels. The stacking sequence of each panel can be determined by selection from combinations of various stacking sequences. The proposed blending model can solve the problem that laminates with identical thicknesses have the completely same layups even when they are not adjacent to each other. The optimal feasible designs outperform other published solutions for the 18-panel horseshoe configuration problem based on the classical bending rule.

Making small-dams work: everyday politics around irrigation cooperatives in Turkey.

Much research on environmental issues in Turkey has focused on conflictual state-led projects, for example on the large-scale GAP irrigation schemes or hydroelectric plants. This article shows that, in a complementary way, it is also necessary to study less contested projects, since power struggles for control over natural resources tend to occur in the implementation and everyday management of these as well. It analyses the everyday dynamics of negotiations and the arrangements found locally during the implementation of the national programme ‘1000 gölet in 1000 days’. Gölet, hillside reservoirs built for irrigation, enabled the government to demonstrate its involvement at a very local level in numerous villages in Turkey. However, the complex implementation of these numerous and relatively small projects compelled agents of the hydraulic administration to negotiate the transfer of their management to local actors. Taking irrigation cooperatives in the Izmir region as a starting point, this article highlights how the shaping of social arrangements for managing the new water resource depends both on local and supralocal power relations. It challenges the idea of a monolithic state disconnected from homogenous communities of irrigators, and reveals the flexibility of these relations. It focuses on the way actors – not only irrigators but also state officials at the local level – adapt norms, bend rules and find arrangements in order to shape new water institutions and infrastructure.

Graphene gets bent

Graphene gets bent

Culzean country park – how an iconic Scottish landscape used designation to secure a sustainable future

ABSTRACT When in 1969 Culzean, Ayrshire, was designated as Scotland’s first country park, it utilised legislative provisions intended to provide countryside recreation space for motorists. This paper offers a critical review of the designation process, revealing how this was used by the National Trust for Scotland as a mechanism to manage their prime property, and particularly to achieve a financially sustainable future. It shows how creative financing, bending rules, manipulating expectations, and flexibility were applied through partnerships with public authorities that were beneficial to all parties, while not quite adhering to the intent of the legislation. Culzean achieved acclaim, offered an exemplar to be followed by its counterparts, and informed perceptions and definitions of the British country park. A review of this experience is critical in that austerity is now threatening the existing funding model and new funding models are needed. An understanding of historic processes may help inform present solutions.

Parameterizing the Curvilinear Roofs of Traditional Chinese Architecture

The curvilinear roofs of ancient Chinese wooden architecture feature unique functional, hierarchical, and aesthetic elements. However, the digitalization of these roofs has yet to be explored because of the lack of accurate mathematical models for these roof geometries. This research aims to parameterize the design and construction rules for these roofs as stipulated in the Yingzao fashi. We first illustrate the major features of curvilinear roofs, followed by a comprehensive investigation on the raising and bending rules via the original texts and drawing samples provided in the Yingzao fashi and the Annotated yingzao fashi by Sicheng Liang. Then, the mathematical models are developed. The main contribution of this research is the transformation of the design and building rules for complex curvilinear roofs into mathematical models, enabling designers to generate such roof architecture and adding new insights to existing mathematical methods in studying ancient architecture.

The Public Library as Resistive Space in the Neoliberal City

With reduced hours, decaying infrastructure, and precariously positioned staff, local public libraries provide much needed services in cities devastated by inequality and slashed safety nets. In this article, I draw on ethnographic research of a small public library in a diverse, mostly working class neighborhood in Queens, New York. I show that in addition to providing an alternative to the capitalist market by distributing resources according to people's needs, the library serves as a moral underground space, where middle–class people bend rules to help struggling city residents. Although the library occasionally replicates hegemonic ideologies about immigrant assimilation, it provides a striking example of cross–class and interclass solidarities and resistance to the neoliberal social order. I conclude by discussing the potential of public libraries as everyday spaces of subversion and emancipation, as well as research sites for urban scholars.

8-Aminoquinoline-Assisted Synthesis and Crystal Structure Studies of Ferrocenyl Aryl Sulfones.

A copper-catalyzed 8-aminoquinoline-directed oxidative cross-coupling of the C-H bond of ferrocene with sodium arylsulfinates has been achieved. The robust copper catalyst tolerates a range of methyl, tert-butyl, bromo, chloro, iodo and nitro functional groups in the phenyl ring, and set the stage for the synthesis of substituted ferrocene sulfones. Furthermore, X-ray crystal structure study on several ferrocenyl sulfones reveals the tetrahedral geometry around sulfur; interestingly, the O-S-O angle is larger than the electropositive substituent C-S-C angle which could be explained by Bent's rule. Further, unusual intramolecular O(S)⋅⋅⋅N(amide) short contacts (2.925-3) and O(S)⋅⋅⋅C=O were also noticed in ferrocenyl sulfones.