Successive Steps Research Articles

Step-by-step full factorial design to optimize a quantitative sandwich ELISA

In this work, a quantitative sandwich ELISA was optimized, through a full factorial design of experiments (DOE) in successive steps of a preliminary protocol obtained by the method of one factor at a time (OFAT). The specificity of the optimized ELISA, the lower limit of quantification, the quantification range and the analytical sensitivity of the antigen quantification curve were evaluated, in comparison with the curve obtained from the preliminary protocol. The full factorial DOE was linked to a simple statistical processing, which facilitates the interpretation of the results in those laboratories where there is no trained statistician. The step-by-step optimization of the ELISA and the successive incorporation into the protocol of the best combination of factors and levels, allowed obtaining a specific immunoassay, with an analytical sensitivity 20 times greater and with a lower limit of antigen quantification that decreased from 156.25 at 9.766 ng/mL. As far as we know, there are no reports of optimization of an ELISA following the step-by-step scheme used in this work. The optimized ELISA will be used for the quantification of the TT-P0 protein, the active principle of a vaccine candidate against sea lice.

Unveiling the Intimate Mechanism of the Crocin Antioxidant Properties by Radiolytic Analysis and Molecular Simulations.

The successive steps of the oxidation mechanism of crocin, a major compound of saffron, by the free OH• radical are investigated by pulse radiolysis, steady-state (gamma) radiolysis methods, and molecular simulations. The optical absorption properties of the transient species and their reaction rate constants are determined. The absorption spectrum of the oxidized radical of crocin resulting from the H-abstraction presents a maximum of 678 nm and a band of 441 nm, almost as intense as that of crocin. The spectrum of the covalent dimer of this radical contains an intense band at 441 nm and a weaker band at 330 nm. The final oxidized crocin, issued from radical disproportionation, absorbs weaker with a maximum of 330 nm. The molecular simulation results suggest that the OH• radical is electrostatically attracted by the terminal sugar and is scavenged predominantly by the neighbor methyl site of the polyene chain as in a sugar-driven mechanism. Based on detailed experimental and theoretical investigations, the antioxidant properties of crocin are highlighted.

Development of SnO2: Ag Nanoparticle as an Affordable Catalyst for the Degradation of Gentian Violet Dye

Abstract: An effective visible catalyst (SnO2:Ag) was successfully synthesized using co-precipitation method for the decomposition of the dye Gentian Violet (GV). In addition to XRD, SEM and UV – Visible analysis, a variety of other physicochemical measurements were used to validate the as-prepared SnO2:Ag nanoparticles. The phase identification of prepared sample is characterized by X – ray powder diffraction (XRD), which confirms the tetragonal rutile structure. The surface morphology is examined using a scanning electron microscope (SEM) and the optical absorption and the band gap value are calculated using the UV-visible spectrum. These results confirm the synthesis of nanoparticles by successive steps. A nanoparticles was demonstrated to be a superior catalyst for the degradation of GV dye when exposed to UV light. The photocatalytic activity studies are discussed using SnO2:Ag nanoparticles. The degradation efficiency of the nanoparticle is 96 % towards the degradation of the GV dye

Protein Is an Intelligent Micelle.

Interpreting biological phenomena at the molecular and cellular levels reveals the ways in which information that is specific to living organisms is processed: from the genetic record contained in a strand of DNA, to the translation process, and then to the construction of proteins that carry the flow and processing of information as well as reveal evolutionary mechanisms. The processing of a surprisingly small amount of information, i.e., in the range of 1 GB, contains the record of human DNA that is used in the construction of the highly complex system that is the human body. This shows that what is important is not the quantity of information but rather its skillful use-in other words, this facilitates proper processing. This paper describes the quantitative relations that characterize information during the successive steps of the "biological dogma", illustrating a transition from the recording of information in a DNA strand to the production of proteins exhibiting a defined specificity. It is this that is encoded in the form of information and that determines the unique activity, i.e., the measure of a protein's "intelligence". In a situation of information deficit at the transformation stage of a primary protein structure to a tertiary or quaternary structure, a particular role is served by the environment as a supplier of complementary information, thus leading to the achievement of a structure that guarantees the fulfillment of a specified function. Its quantitative evaluation is possible via using a "fuzzy oil drop" (FOD), particularly with respect to its modified version. This can be achieved when taking into account the participation of an environment other than water in the construction of a specific 3D structure (FOD-M). The next step of information processing on the higher organizational level is the construction of the proteome, where the interrelationship between different functional tasks and organism requirements can be generally characterized by homeostasis. An open system that maintains the stability of all components can be achieved exclusively in a condition of automatic control that is realized by negative feedback loops. This suggests a hypothesis of proteome construction that is based on the system of negative feedback loops. The purpose of this paper is the analysis of information flow in organisms with a particular emphasis on the role of proteins in this process. This paper also presents a model introducing the component of changed conditions and its influence on the protein folding process-since the specificity of proteins is coded in their structure.

Utility of narrow-band imaging with or without dual focus magnification in neoplastic prediction of small colorectal polyps: a Vietnamese experience.

Accurate neoplastic prediction can significantly decrease costs associated with pathology and unnecessary colorectal polypectomies. Narrow band imaging (NBI) and dual-focus (DF) mode are promising emerging optical technologies for recognizing neoplastic features of colorectal polyps digitally. This study aimed to clarify the clinical usefulness of NBI with and without DF assistance in the neoplastic prediction of small colorectal polyps (<10 mm). This cross-sectional study included 530 small colorectal polyps from 343 consecutive patients who underwent colonoscopy at the University Medical Center from September 2020 to May 2021. Each polyp was endoscopically diagnosed in three successive steps using white-light endoscopy (WLE), NBI, and NBI-DF and retrieved for histopathological assessment. The diagnostic accuracy of each modality was evaluated with reference to histopathology. There were 295 neoplastic polyps and 235 non-neoplastic polyps. The overall accuracies of WLE, WLE+NBI, and WLE+NBI+NBI-DF in the neoplastic prediction of colorectal polyps were 70.8%, 87.4%, and 90.8%, respectively (p<0.001). The accuracy of WLE+NBI+NBI-DF was significantly higher than that of WLE+NBI in the polyp size ≤5 mm subgroup (87.3% vs. 90.1%, p<0.001). NBI improved the real-time neoplastic prediction of small colorectal polyps. The DF mode was especially useful in polyps ≤5 mm in size.

Investigation of Oxidation Homogeneity in Asphalt Puck after Simulation of Long-Term Aging (Pressure Aging Vessel).

For decades, it has been known that the creation of oxygenated functional groups, especially carbonyl and sulfoxide, is among the main causes of chemical aging and degradation of asphalt. However, is the oxidation of a bitumen homogeneous? The focus of this paper was to follow the oxidation phenomena through an asphalt puck during a pressure aging vessel (PAV) test. According to the literature, the asphalt oxidation process that leads to the creation of oxygenated functions can be divided into the following successive main steps: the absorption of oxygen in asphalt at the air/asphalt interface, diffusion into the matrix, and reaction with asphalt molecules. To study the PAV oxidation process, the creation of carbonyl and sulfoxide functional groups in three asphalts were investigated after various aging protocols by Fourier transform infrared spectroscopy (FTIR). From these experiments performed on different layers of asphalt puck, it was observed that PAV aging resulted in a nonhomogeneous oxidation level inside the entire matrix. Compared to the upper surface, the lower section exhibited carbonyl and sulfoxide indices 70% and 33% lower, respectively. Moreover, the difference in the oxidation level between the top and bottom surfaces increased when the thickness and viscosity of the asphalt sample increased.

Flax fiber based semicarbazide biosorbent for removal of Cr(VI) and Alizarin Red S dye from wastewater

In the present study, flax fiber based semicarbazide biosorbent was prepared in two successive steps. In the first step, flax fibers were oxidized using potassium periodate (KIO4) to yield diadehyde cellulose (DAC). Dialdehyde cellulose was, then, refluxed with semicarbazide.HCl to produce the semicarbazide functionalized dialdehyde cellulose (DAC@SC). The prepared DAC@SC biosorbent was characterized using Brunauer, Emmett and Teller (BET) and N2 adsorption isotherm, point of zero charge (pHPZC), elemental analysis (C:H:N), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analyses. The DAC@SC biosorbent was applied for the removal of the hexavalent chromium (Cr(VI)) ions and the alizarin red S (ARS) anionic dye (individually and in mixture). Experimental variables such as temperature, pH, and concentrations were optimized in detail. The monolayer adsorption capacities from the Langmuir isotherm model were 97.4 mg/g and 18.84 for Cr(VI) and ARS, respectively. The adsorption kinetics of DAC@SC indicated that the adsorption process fit PSO kinetic model. The obtained negative values of ΔG and ΔH indicated that the adsorption of Cr(VI) and ARS onto DAC@SC is a spontaneous and exothermic process. The DAC@SC biocomposite was successfully applied for the removal of Cr(VI) and ARS from synthetic effluents and real wastewater samples with a recovery (R, %) more than 90%. The prepared DAC@SC was regenerated using 0.1 M K2CO3 eluent. The plausible adsorption mechanism of Cr(VI) and ARS onto the surface of DAC@SC biocomposite was elucidated.

A new procedure for autonomous acquisition of photosynthesis-irradiance curves on a microphytobenthic biofilm

Despite their high productivity and their key role in coastal processes, microphytobenthic biofilm studies remain relatively scarce because in situ, meteorological hazards make it difficult to acquire reproducible measurements, also due to difficulties in properly reproducing field conditions in the laboratory. Therefore, in order to better understand the processes of microphytobenthic primary production, we have developed an automated laboratory system and procedure with variable light intensity, with a large number of replicates. This article aims to provide a description of the creation of a P-I curve based on a total of 128 vertical profiles recorded on a sediment core taken in situ, placed in the automated system and studied under controlled conditions of temperature and air humidity while light intensity was varied automatically, thus allowing to work in standard and replicable conditions. With measured production levels of up to 14.68 ± 3.70 mmol O2.m-2.h-1 and a productivity of 0.06 ± 0.01 mmol O2.m-2.h-1 per gram of Chl a corresponding to what is generally found in temperate environments, we have shown that our system is suitable for high frequency measurements and, by combining surficial measurements of modulated fluorescence and oxygen microprofiling in sediments, complementary information from a large dataset on photosynthetic and microphytobenthic migratory activity may be obtained under standard conditions. The development of this tool has made it possible to highlight a stabilization time for oxygen fluxes. For our study conducted in a temperate environment, we observed a time lag of a few minutes that should be considered when acquiring PE curves in the laboratory to study microphytobenthic photosynthetic capacities. This tool also allowed to describe microphytobenthic migration in response to light exposure, with successive steps observed through fluorescence and oxygen profiles. First, microphytobenthos migrated towards the surface until the optimal intensity of production at 475 µmol photons.m-2.s-1, then from this intensity as well as towards 780 µmol photons.m-2.s-1, downwards migratory movements were detected. This system is a working basis which can open interesting perspectives for the study of the effect of other abiotic (or biotic) parameters.

A Novel Semi-Solid Self-Emulsifying Formulation of Aprepitant for Oral Delivery: An In Vitro Evaluation.

Aprepitant is the first member of a relatively new antiemetic drug class called NK1 receptor antagonists. It is commonly prescribed to prevent chemotherapy-induced nausea and vomiting. Although it is included in many treatment guidelines, its poor solubility causes bioavailability issues. A particle size reduction technique was used in the commercial formulation to overcome low bioavailability. Production with this method consists of many successive steps that cause the cost of the drug to increase. This study aims to develop an alternative, cost-effective formulation to the existing nanocrystal form. We designed a self-emulsifying formulation that can be filled into capsules in a melted state and then solidified at room temperature. Solidification was achieved by using surfactants with a melting temperature above room temperature. Various polymers have also been tested to maintain the supersaturated state of the drug. The optimized formulation consists of CapryolTM 90, Kolliphor® CS20, Transcutol® P, and Soluplus®; it was characterized by DLS, FTIR, DSC, and XRPD techniques. A lipolysis test was conducted to predict the digestion performance of formulations in the gastrointestinal system. Dissolution studies showed an increased dissolution rate of the drug. Finally, the cytotoxicity of the formulation was tested in the Caco-2 cell line. According to the results, a formulation with improved solubility and low toxicity was obtained.

The power of academic and public opinion in conservation: The case of Ayyalon Cave, Israel

AbstractWhile pessimism dominates discussions on biodiversity loss, it is increasingly recognized that for the long‐term success of conservation programs, we also need hope. One way to foster hope is to celebrate the positive outcomes of conservation efforts. Here, we report on a successful step in the conservation efforts of Ayyalon cave, a unique subterranean ecosystem discovered in 2006 as a result of mining activities in a quarry in central Israel. Ayyalon cave is one of the few known fully sustained subterranean autotrophic sulfur‐based food webs, in turn supporting a diverse, specialized endemic fauna. Upon the discovery of the cave, its isolation from the surface was compromised, resulting in colonization of alien species and changes in environmental conditions. In May 2021, the cave was put at additional risk following a plan to inject millions of cubic meters of fresh, cold, and oxidized water into the quarry. A team of Israeli scientists decided to take action, starting a highly mediatic campaign to save the cave. This campaign involved cooperation among domestic and foreign academics, the general public sector, and diverse stakeholders. Despite strong economic interests, the conservation campaign succeeded in pushing the National Infrastructure Committee to rectify the plan to inject water into the cave. Stemming from this success, we discuss important take‐home messages that are paramount for the broader conservation science community.

The Most Effective Functioning of Competitive Supply Chain Pricing Based on Social Responsibility Dimensions: A Case Study of Oil Products of Knowledge-Based Companies

In today’s competitive environment, taking the advantage of supply chain which is both effective and efficient is a competitive advantage. An adequate supply chain has a multifaceted structure that focuses on integrating all factors, including pricing. The final product is delivered to customers based on maintaining market values and increasing strategic interactions. Present study aims to present the most effective functioning of competitive supply chain pricing in accordance with aspects of social responsibility. In doing so, we conducted a case study on oil-related products of Iranian knowledge-based companies. A combined analysis with 15 university-level industrial management experts was employed in this study to establish the components (competitive supply chain pricing function) and research propositions (dimensions of social responsibility). Twenty managers of knowledge-based enterprises in the oil field evaluated the components and propositions identified in the form of matrix questions using interpretative rating (IRP). The results showed that the proposition of the ethical dimension is the most effective measure of the social responsibility of knowledge-based companies in the oil field, creating competitive supply chain pricing functions based on value. This result shows that, under the ethical dimension of social responsibility, processes of competitive supply chain pricing are formed in accordance with the customer values and, according to the strategic relationship between the company and the economy with regional and global partners, maintaining values are a critical factor in developing our interactions between pricing factors. Given the results, in the first step for success, knowledge-based companies are recommended to consider the priorities of professional ethics in addition to knowledge in order to be able to gain the trust of customers by understanding their functional nature in the country’s developing economy. In this situation, the pricing process based on the creation of comprehensive values for customers can help to increase the company’s competitive position and make these companies to be at the first level of strategic interactions with companies that use petroleum products.

Treatment cascade for patients with multidrug- or rifampicin-resistant tuberculosis and associated factors with patient attrition in southeastern China: a retrospective cohort study

ObjectivesTo address gaps in health services for multidrug- or rifampicin-resistant tuberculosis (MDR/RR-TB), a treatment cascade model was used to evaluate patient retention and attrition at each successive step required to achieve a successful treatment outcome. MethodsFrom 2015–2018, a four-step treatment cascade model was established in patients with confirmed MDR/RR-TB in southeast China. Step 1: diagnosis of MDR/RR-TB, step 2: Initiation of treatment, step 3: still under treatment at 6 month and step 4: cure or completion of MDR/RR-TB treatment, with each successive step including a gap that shows attrition of patients between steps. The retention and attrition of each step were graphed. Multi-variate logistic regression was carried out to further identify potential factors associated with the attrition. ResultsIn the treatment cascade consisting of 1752 MDR/RR-TB patients, the overall patient attrition rate was 55.8% (978/1752), with 28.0% (491/1752), 19.9% (251/1261), and 23.4% (236/1010) of patients attrition in the first, second, and third gap. Factors associated with MDR/RR-TB patients not initiating treatment included age ≥60 years (OR:2.875), and time for diagnosis ≥30 days (OR: 2.653). Patients who were diagnosed with MDR/RR-TB through rapid molecular test (OR: 0.517) and non-migrant residents of Zhejiang Province (OR: 0.273) both exhibited a lower likelihood of attrition during the treatment initiation phase. Meanwhile, old age (OR: 2.190) and non-resident migrants to the province were factors associated with not completing ≥ 6 months of treatment. Old age (OR: 3.883), retreatment (OR: 1.440), and time to diagnosis ≥30 days (OR: 1.626) were factors contributing to poor treatment outcomes. ConclusionSeveral programmatic gaps were identified in the MDR/RR-TB treatment cascade. Future policies should provide more comprehensive support for vulnerable populations to improve the care quality at each step.

Postgraduate education to expand access to dental care: A roadmap to community dental program development.

Evidence indicates an increasing shortage of dentists in communities across the United States with potentially significant implications for oral health, as well as overall health and well-being. One strategy to increase access to dental care in rural and underserved communities is community-based postgraduate dental training. However, developing new dental programs requires navigating complex accreditation, financial and community governance, among other, barriers. The Roadmap for Teaching Health Center Dental Program Development presents a framework that guides institutions through the successive steps of developing new postgraduate training programs from identification of need to ultimate maintenance and sustainability. The tool assists programs in anticipating and understanding requirements, reducing time, expense, and uncertainty. While the framework was developed for community-based programs, the steps are applicable to postgraduate programs sponsored by academic institutions as well.

Oxygen Vacancy-Rich S-Scheme CeO2@Ni1–xCoxSe2 Hollow Spheres Derived from NiCo-MOF for Remarkable Photocatalytic CO2 Conversion

Photocatalytic CO2 conversion into chemicals has been a promising strategy to utilize sustainable solar energy and alleviate the greenhouse effect. Nonetheless, the achievements of these photocatalytic reactions are challenging. Herein, we present a strategy for the synthesis of hierarchical CeO2@Ni1–xCoxSe2 hollow spheres (HSs) including the successive steps of coating of the CeO2 nanolayer on SiO2 spheres, in situ growth of NiCo-MOF nanosheets, selenization reaction, and subsequent etching treatment. The hierarchical CeO2@Ni1–xCoxSe2 HSs exhibiting intimate interface contact between two nanoshells form an S-scheme heterojunction with fast charge/mass transport and excellent visible-light absorption, while maintaining the strong reducing power of electrons in the conduction band of Ni1–xCoxSe2 nanosheets and the strong oxidizing capacity of holes in the valence band of CeO2 HSs with oxygen vacancies. The S-scheme photogenerated charge transfer mechanism was testified by the work function and electron paramagnetic resonance measurements. These advantages make the optimized CeO2@Ni1–xCoxSe2 HS sample exhibit superior activity and high stability in photocatalytic CO2 reduction with a CO production rate of 25.93 μmol h–1 g–1. This work provides more opportunities to fabricate other hierarchical S-scheme semiconductor-based photocatalysts.

Endogenous biohydrogen from a rhizobium-legume association drives microbial biodegradation of polychlorinated biphenyl in contaminated soil

Endogenous hydrogen (H2) is produced through rhizobium-legume associations in terrestrial ecosystems worldwide through dinitrogen fixation. In turn, this gas may alter rhizosphere microbial community structure and modulate biogeochemical cycles. However, very little is understood about the role that this H2 leaking to the rhizosphere plays in shaping the persistent organic pollutants degrading microbes in contaminated soils. Here, we combined DNA-stable isotope probing (DNA-SIP) with metagenomics to explore how endogenous H2 from the symbiotic rhizobium-alfalfa association drives the microbial biodegradation of tetrachlorobiphenyl PCB 77 in a contaminated soil. The results showed that PCB77 biodegradation efficiency increased significantly in soils treated with endogenous H2. Based on metagenomes of 13C-enriched DNA fractions, endogenous H2 selected bacteria harboring PCB degradation genes. Functional gene annotation allowed the reconstruction of several complete pathways for PCB catabolism, with different taxa conducting successive metabolic steps of PCB metabolism. The enrichment through endogenous H2 of hydrogenotrophic Pseudomonas and Magnetospirillum encoding biphenyl oxidation genes drove PCB biodegradation. This study proves that endogenous H2 is a significant energy source for active PCB-degrading communities and suggests that elevated H2 can influence the microbial ecology and biogeochemistry of the legume rhizosphere.

Oral cancer awareness campaign in Northern Germany: successful steps to raise awareness for early detection.

Oral cancer is an underestimated health problem, and its existence and the relevant prevention measures are not sufficiently known by the general population. The project thus aimed to develop, implement and evaluate an oral cancer campaign in Northern Germany, and to increase problem awareness on various levels: draw public attention to the tumour by media coverage increase awareness of early detection opportunities for the target group, and raise awareness of carrying out early detection measures by the professional groups involved. For each level, a campaign concept was developed and documented in terms of content and timing. The identified target group was elderly educationally disadvantaged male citizens ≥ 50years. The evaluation concept for each level included pre-, post- and process evaluations. The campaign was carried out from April 2012 to December 2014. The issue of awareness within the target group was significantly increased. Media coverage showed that regional media adopted the topic of oral cancer and placed it on their published agenda. Furthermore, the continuous involvement of the professional groups over the course of the campaign led to an increased awareness of oral cancer. The development of the campaign concept with a comprehensive evaluation showed that the target group was successfully reached. The campaign was adapted to the required target group and specific conditions, and was also designed to be context sensitive. It is, therefore, recommended that the development and implementation of an oral cancer campaign on a national level be discussed.

Timely Teaching for the Time Poor

Introduction:Australian Standard 4080-2010 Planning for Emergencies in Health Care Facilities outlines the requirements for all health care facilities to have procedures in place to respond to internal and external emergencies. These procedures must include mechanisms to activate emergency response systems, and staff should be trained and familiar with these procedures.Method:To guide staff, Emergency Procedures Flip Charts have been developed and strategically placed throughout facilities. These Flip Charts address immediate actions for staff to follow, including notification and escalation via an internal emergency number.Specific training has been developed for identified key staff, such as Fire Wardens, but for the general staff the training in Emergency Codes is generic and does not provide scope for staff to contextualize response actions in relation to their department and its nuances.A survey of staff across all disciplines was conducted which identified knowledge gaps in the immediate response requirements for the different Emergency Codes. To address this knowledge gap, and to ensure staff have an increased understanding of the response expectations relevant to their department, the Six Minute Intensive Training (SMIT) Tools have been developed. These tools can be delivered by any staff member in any forum, such as safety huddles, handover, in-services and toolbox talks.Results:A survey was conducted three months after their implementation which identified an increased understanding of response requirements. This result, combined with After Action Reviews from actual responses, highlighted an increased knowledge of the Emergency Codes and response actions. It also identified areas to improve delivery using localized examples.Conclusion:The introduction of the SMITs is a successful first step for increasing staff knowledge and responses to Emergency Codes. The opportunity for staff to deliver these SMITs within their own departments provided an avenue to contextualize responses to local practices and nuances.

Enhancing Social Qualities in University Campus Outdoor Spaces through Islamic Spatial Configurations: The Case of the American University in Cairo

Universities are under more pressure than ever before to attract more students and move up in rankings. Due to bounded space and rising plot values in city areas, a spatial configuration that meets user needs has become a very important topic for well-prepared and spatially suitable educational settings. However, today there is a rapid pace in the establishment of universities in Egypt. Insufficient use of university campus outdoor spaces (UCOS) is considered one of the main negative impacts on social quality in these universities in Egypt. This study aims to evaluate the social qualities according to the Islamic spatial configurations of UCOS in The American University in Cairo (AUC). The research is based on using integrated observational and computational methods in different UCOS. Observational methods are applied through behavioral mapping and movement tracing. Computational methods are applied through space syntax software. The AUC campus is selected as a case study because its design is based on different types of UCOS. The methodology follows three successive steps. Firstly, a field observation of the most used UCOS was undertaken. Secondly, a spatial analysis examining the potential effect of the campus spatial configuration was conducted. Finally, a comparative analytical approach that illustrates the relationship between Islamic spatial configurations of UCOS and activity categories according to user behaviors was taken. The research shows the considered types of UCOS and their ranking according to the observational and computational methods that achieve the highest values for social qualities.

Ricci soliton equation with application to a coupled pendula

The Ricci equation and the soliton solutions are obtained in this paper for two coupled pendula in order to optimise its locomotion and structure. The robot is swinging repeatedly like a rope with successive movement steps along a mobile support. The cnoidal theory and a genetic algorithm are used to solve the problem via the Ricci solitons and the pseudospherical reduction of the rheological Zener equations. The Bäcklund transform is applied to Ricci equation to generate pseudo-spherical surfaces.

Understanding the effects of building block rings of π electron-rich organic photocatalysts in CO2 transformation to amino acids

Understanding the effective factors in the performance of some Oligo (p-phenylenes) (OPPs) and Polycyclic Aromatic Hydrocarbons (PAHs), as efficient organocatalysts in photocatalytic CO2 transformations are the main goals of this investigation. The studies are based on density functional theory (DFT) calculations on the mechanistic aspects of C–C bond formation through a coupling reaction between CO2•– and amine radical. The reaction is performed through two successive single electron transfer steps. After careful kinetic investigations by Marcus’ theory rules, powerful descriptors are used to describe the behavior of observed barrier energies of electron transfer steps. The studied PAHs and OPPs consist of different numbers of rings. Thus, it can be considered different charge densities, afforded from π electrons, of PAHs and OPPs that cause distinguished efficiency in kinetic aspects of electron transfer steps. Electrostatic Surface Potential (ESP) analyses reveal a good relationship between the charge density of the studied organocatalysts in single electron transfer (SET) steps and the kinetic parameters of the steps. Moreover, the contribution of rings in the framework of PAHs and OPPs would be another effective factor in the barrier energies of SET steps. Aromatic properties of the rings, studied by the Anisotropy of the Current-Induced Density (ACID), Nucleus-Independent Chemical Shift (NICS), the multi-center bond order (MCBO), and AV1245 Indexes, are the other impressive factors in the role of rings in SET steps. The results show that the aromatic properties of the rings are not similar to each other. Higher aromaticity affords remarkable reluctance of the corresponding ring to participate in SET steps.