Symmetry-enhanced supertransfer of delocalized quantum states

Coherent hopping of excitation rely on quantum coherence over physically extended states. In this work, we consider simple models to examine the effect of symmetries of delocalized multi-excitation states on the dynamical timescales, including hopping rates, radiative decay, and environmental interactions. While the decoherence (pure dephasing) rate of an extended state over N sites is comparable to that of a non-extended state, superradiance leads to a factor of N enhancement in decay and absorption rates. In addition to superradiance, we illustrate how the multi-excitonic states exhibit `supertransfer' in the far-field regime: hopping from a symmetrized state over N sites to a symmetrized state over M sites at a rate proportional to MN. We argue that such symmetries could play an operational role in physical systems based on the competition between symmetry-enhanced interactions and localized inhomogeneities and environmental interactions that destroy symmetry. As an example, we propose that supertransfer and coherent hopping play a role in recent observations of anomolously long diffusion lengths in nano-engineered assembly of light-harvesting complexes.Comment: 6 page

Polarographic Studies on Complexes of Pd(II) & Co(II) with Triethanolamine

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Chelating and Bridging Roles of 2-(2-Pyridyl)benzimidazole and Bis(diphenylphosphino)acetylene in Stabilizing a Cyclic Tetranuclear Platinum(II) Complex.

The reaction of complex [Pt(Me)(DMSO)(pbz)], 1, (pbz = 2-(2-pyridyl)benzimidazolate) with [PtMe(Cl)(DMSO)2], B, followed by addition of bis(diphenylphosphino)acetylene (dppac), gave the novel tetranuclear platinum complex [Pt4Me4(μ-dppac)2(pbz)2Cl2], 2, bearing both the pbz and dppac ligands. In this structure, the pbz ligands are both chelating and bridging to stabilize the tetraplatinum framework. The tetranuclear Pt(II) complex was fully characterized by NMR spectroscopy, X-ray crystallography, and mass spectrometry, and its electronic structure was investigated and supported by DFT calculations

Influence of different concentration of heavy metals on the seed germination and growth of tomato

Some heavy metals in higher doses may cause metabolic disorders and growth inhibition for most of the plant species. This study was performed in order to evaluate two tomato varieties (Barakat and Local tomato) response to ordinary Heavy Metals (Fe, Pb and Cu) in northern of Iran. Five doses (0, 0.001, 0.01, 0.1 and 1%) of lead acetate, cupric carbonate and ferric chloride were investigated. The experiment was conducted under 12±2h photoperiodic laboratory condition in a laboratory germinator. Results showed that the reaction of varieties to different heavy metal compounds and those doses is varied and Barakat variety has greater resistance in more indices. Also, heavy metals kind and different doses of these compounds affected the germination and some growth indices. In this experiment the highest inhibition on shoot length 2.66 cm, root/ shoot ratio 0.87, moisture content 0.31 g, fresh weight 0.32 g and dry weight 0.059 g were obtained from Fe compound, however; had not significance different with other heavy metal compounds in case of root length 3.39 cm and coefficient of germination velocity 0.27% (P≤0.05). Also, dose of 1% appeared highest undesirable effect on all evaluated indexes.Key words: Tomato, toxic metal, dose, coefficient of germination velocity

SOLVENT EFFECTS ON THE ELECTRONIC ABSORPTION SPECTRA OF SOME ANALYTICAL INDICATORS

Electronic absorption spectra of selected ligands (Alloxan, Carmine, Naphthol Yellow S, Hematoxylin and Cyanine) were recorded in presence of different solvents (H2O, Ethyl acetate, Ethanol, DMF, Isopropyl alcohol, Amyl alcohol and Butanol) of variable physical properties. The electronic transitions were assigned. The data are analyzed based on the multiple linear regression technique explained from the views of different solvent parameters. Statistical analyses of the effect of solvents on the electronic spectra of the present ligands have been investigated

What the policy and stewardship landscape of a national health research system looks like in a developing country like Iran: a qualitative study

BACKGROUND: The health research system (HRS) is an important national priority that requires a systematic and functional approach. Evaluating the HRS of Iran as a developing country and identifying its challenges reveals the stewardship-related role in how the whole system is operating well. This study aims to assess the HRS in terms of stewardship functions and highlight the enhancement points. METHODS: This study was carried out between March 2020 and April 2021 using a systematic review and meta-synthesis of evidence to examine the Iranian HRS stewardship challenges and interview 32 stakeholders, using a critical case sampling and snowballing approach which included both semi-structured and in-depth interviews. The interviewees were selected based on criteria covering policy-makers, managers, research bodies and nongovernmental organizations (NGOs) in health research-related fields like higher education, research, technology, innovation and science. All data were analysed using content analysis to determine eight main groups of findings under three levels: macro, meso, and micro. RESULTS: Analysis of the findings identified eight main themes. The most critical challenges were the lack of an integrated leadership model and a shared vision among different HRS stakeholders. Their scope and activities were often contradictory, and their role was not clarified in a predetermined big picture. The other challenges were legislation, priority-setting, monitoring and evaluation, networking, and using evidence as a decision support base. CONCLUSIONS: Stewardship functions are not appropriately performed and are considered the root causes of many other HRS challenges in Iran. Formulating a clear shared vision and a work scope for HRS actors is critical, along with integrating all efforts towards a unified strategy that assists in addressing many challenges of HRS, including developing strategic plans and future-oriented and systematic research, and evaluating performance. Policy-makers and senior managers need to embrace and use evidence, and effective networking and communication mechanisms among stakeholders need to be enhanced. An effective HRS can be achieved by redesigning the processes, regulations and rules to promote transparency and accountability within a well-organized and systematic framework

Exploring the use of new school buildings through post-occupancy evaluation and participatory action research

This paper presents the results of the development and testing of an integrated post-occupancy evaluation (POE) approach for teachers, staff, pupils and community members using newly constructed school buildings. It focusses on three cases of UK secondary schools, demonstrating how users can be inspired to engage with the problems of school design and energy use awareness. The cases provided new insights into the engagement of school teachers, staff and young people regarding issues of sustainability, management, functional performance and comfort. The integrative approach adopted in these cases provided a more holistic understanding of these buildings’ performance than could have been achieved by either observational or more traditional questionnaire-based methods. Moreover, the whole-school approach, involving children in POE, provided researchers with highly contextualised information about how a school is used, how to improve the quality of school experiences (both socially and educationally) and how the school community is contributing to the building's energy performance. These POE methods also provided unique opportunities for children to examine the social and cultural factors impeding the adoption of energy-conscious and sustainable behaviours