Kinetics of in situ epoxidation of hemp oil under heterogeneous reaction conditions: an overview with preliminary results

Epoxidised hemp oil (EHO) was synthesised in the laboratory by reacting hemp oil (HO) with peroxyacetic acid (PA) in a batch reactor. The peroxyacetic acid was formed in situ from acetic acid (AA) and hydrogen peroxide (H2O2) in the presence on an acidic ion exchange resin (Amberlite IR-120) as catalyst. The overall reaction can be thought of as having two components. The first being epoxidation, a homogenous reaction which occurs at the interface of the aqueous phase and the HO phase while the second is the formation of PA, a heterogeneous reaction at the interface of the aqueous phase and the solid catalyst phase. The overall reaction kinetics were modelled by applying the Langmuir-Hinshelwood-Hougen-Watson (LHHW) model to heterogeneous reactions. Of the steps in the reaction it is postulated that the formation of PA is rate limiting, while the epoxidation occurs comparatively fast negating the requirement for an additional homogenous model. The diffusion steps in the reaction are also ignored in the kinetic model as it is believed that their effects are negligible due to intensive mixing in the batch reactor. Experiments were used to determine the optimal molar ratios of reactants and it was found that at these conditions 88% conversion of double bonds to epoxy groups occurred. The kinetic model was found to be in good agreement with the experimental results

A review of current development in natural fiber composites for structural and infrastructure applications

Natural fiber composites (NFC) as the name implies is made of natural resources thus possesses environmentally beneficial properties such as biodegradability. With its natural characteristics, NFC is obtaining more attention in recent years in various application including automotive, merchandise, structural and infrastructure. Several studies have shown that NFC can be developed into a load-bearing structural member for applications in structural and infrastructure application. As an engineered material, similar with synthetic fiber composites, the properties of NFC can be tailored to meet certain requirements. The challenge in working with NFC is the large variation in properties and characteristics. The properties of NFC to a large extent influenced by the type of fibers, environmental condition where the plant fibers are sourced and the type of fiber treatments. However, with their unique and wide range of variability, natural fiber composites could emerge as a new alternative engineering material which can substitute the use of synthetic fiber composites

Thinking twice about the evolution of photosynthesis

Sam Granick opened his seminal 1957 paper titled ‘Speculations on the origins and evolution of photosynthesis’ with the assertion that there is a constant urge in human beings to seek beginnings (I concur). This urge has led to an incessant stream of speculative ideas and debates on the evolution of photosynthesis that started in the first half of the twentieth century and shows no signs of abating. Some of these speculative ideas have become commonplace, are taken as fact, but find little support. Here, I review and scrutinize three widely accepted ideas that underpin the current study of the evolution of photosynthesis: first, that the photochemical reaction centres used in anoxygenic photosynthesis are more primitive than those in oxygenic photosynthesis; second, that the probability of acquiring photosynthesis via horizontal gene transfer is greater than the probability of losing photosynthesis; and third, and most important, that the origin of anoxygenic photosynthesis pre-dates the origin of oxygenic photosynthesis. I shall attempt to demonstrate that these three ideas are often grounded in incorrect assumptions built on more assumptions with no experimental or observational support. I hope that this brief review will not only serve as a cautionary tale but also that it will open new avenues of research aimed at disentangling the complex evolution of photosynthesis and its impact on the early history of life and the planet

HIGHER EDUCATION AND THE DEI CLIMATE: EXPLORING AND UNDERSTANDING THE ROLE OF SOCIAL MEDIA, SELF ESTEEM, AND INTERCULTURAL COMMUNICATION IN DIVERSITY, EQUITY, AND INCLUSION INITIATIVES ON THE COLLEGE CAMPUS

This study seeks to understand the effects and levels of impact that a university student’s intercultural communication competence, social media usage, and self-esteem have on the students’ attitudes towards diversity, equity, and inclusion (DEI) efforts implemented by institutions of higher education. By studying these three independent variables, this research seeks to improve the understanding of the university students’ attitudes on DEI efforts for leaders and change agents in higher education, providing an inspiration for leaders, administrators, and change agents of higher education to continue collaborating to innovate methods and avenues towards creating a diverse, equitable, and inclusive campus climate, as well as focusing on the roles that intercultural communication competence, social media usage, and self-esteem play in this construction of DEI programming. The researcher administered a questionnaire to 351 undergraduate, graduate, and professional students from the University of the Pacific Stockton, Sacramento, and San Francisco campuses using various scales examining campus DEI climate, intercultural communication competency levels, self-esteem, and university-specific and general social media usage. The data from the surveys were analyzed to determine how the independent variables influence the students’ attitudes towards the DEI efforts being implemented by their university. The results indicate that self-esteem (SE) (r= 0.30) and students’ satisfaction with the university’s DEI-related social media campaigns and content (SSPDEI) (r= 0.38) are strongly correlated with the students’ attitudes towards the university’s commitment to DEI. Although intercultural communication competence (ICC) (r= 0.20) and how students use university- affiliated social media (USEPSM) (r= 0.21) offer levels of influence on the students’ attitudes towards the university’s commitment to DEI, they lag behind the levels shown by SE and SSPDEI. The results indicate that the students’ satisfaction with the university’s DEI-related social media campaigns and content (SSPDEI) (r= 0.35) provides a significant correlation with the students’ feelings towards diversity, equity, and inclusion on the campus (DEISF). Although ICC (r= 0.20), SE (r= 0.20), and USEPSM (r= 0.19) offer levels of influence on the DEISF, they lag behind the level shown by SSPDEI. The results also indicate that the student’s satisfaction with the university’s DEI-related social media campaigns and content (SSPDEI) (r= 0.28) and self-esteem (SE) (r= 0.23) provide the greatest influence on evidence-based DEI (DEIEV), which includes the student’s feelings and beliefs about the university’s commitment to non- discrimination and respect of each student’s individual qualities and demographics. Although ICC (r= 0.19) and USEPSM (0.16) offer levels of influence on DEIEV, they lag behind the level shown by SSPDEI and SE. Intercultural Communication Competency, Self Esteem, and Social Media Usage all have a significant positive relationship with a student’s attitude towards the DEI efforts being implemented by their university. A regression analysis found that the variables of self-esteem and intercultural communication competency have a strong predicting effect on any variances that are seen in the students’ attitudes toward the university’s commitment to DEI. The students’ use of social media may provide enough positive effect on the student’s attitudes towards the university’s efforts and actions related to DEI, however, the focus should then be placed on student satisfaction with the overall strategy and implementation. The multiple linear regression analysis also provides further support that the variables of social media usage, intercultural communication competence, and self-esteem are significant in moving forward the work in creating a campus climate centered on DEI

Photosystem II is a chimera of reaction centers

A complete scenario for the evolution of photosynthesis must account for the origin and diversification of photochemical reaction centers. Two lively debated questions are how the distinct types of reaction centers evolved and how cyanobacteria acquired two distinct reaction centers—Photosystem I and Photosystem II—in the path towards the origin of light-driven water oxidation, or in other words, towards the evolution of oxygenic photosynthesis (Hohmann-Marriott and Blankenship 2011; Fischer et al. 2016). Here I show how the chimeric structure of Photosystem II provides unambiguous answer to these questions

Early Archean origin of heterodimeric Photosystem I

When and how oxygenic photosynthesis originated remains controversial. Wide uncertainties exist for the earliest detection of biogenic oxygen in the geochemical record or the origin of water oxidation in ancestral lineages of the phylum Cyanobacteria. A unique trait of oxygenic photosynthesis is that the process uses a Type I reaction centre with a heterodimeric core, also known as Photosystem I, made of two distinct but homologous subunits, PsaA and PsaB. In contrast, all other known Type I reaction centres in anoxygenic phototrophs have a homodimeric core. A compelling hypothesis for the evolution of a heterodimeric Type I reaction centre is that the gene duplication that allowed the divergence of PsaA and PsaB was an adaptation to incorporate photoprotective mechanisms against the formation of reactive oxygen species, therefore occurring after the origin of water oxidation to oxygen. Here I show, using sequence comparisons and Bayesian relaxed molecular clocks that this gene duplication event may have occurred in the early Archean more than 3.4 billion years ago, long before the most recent common ancestor of crown group Cyanobacteria and the Great Oxidation Event. If the origin of water oxidation predated this gene duplication event, then that would place primordial forms of oxygenic photosynthesis at a very early stage in the evolutionary history of life

Metodologia de investigacion en entomologia de frijol

The general objectives of CIAT's bean entomology program are mentioned. The 1st priority has been given to var. resistance as an ideal pest control method. At CIAT's headquarters (Palmira, Colombia), studies are conducted on Empoasca kraemeri, mites, and storage insects; var. resistance to Apion godmani and Epinotia aporema is being studied at other institutions. The steps of genetic improvement of beans for resistance to E. kraemeri are described: selection of sources of resistance, hybridization of selected materials, and selection of resistant progenies. (CIAT)Se mencionan los objetivos generales del programa de entomologia de frijol del CIAT. La mayor prioridad se ha dado a la resistencia var. como metodo ideal de control de plagas. En la sede principal del CIAT (Palmira, Colombia) se adelantan estudios con Empoasca kraemeri, acaros e insectos del frijol almacenado; en otras instituciones se esta estudiando la resistencia var. a Apion godmani y a Epinotia aporema. Se describen las etapas de mejoramiento genetico del frijol por resistencia a E. kraemeri: escogencia de fuentes de resistencia, hibridacion de los materiales seleccionados y seleccion de progenies resistentes. (CIAT

Folding and unfolding phylogenetic trees and networks

Phylogenetic networks are rooted, labelled directed acyclic graphs which are commonly used to represent reticulate evolution. There is a close relationship between phylogenetic networks and multi-labelled trees (MUL-trees). Indeed, any phylogenetic network $N$ can be "unfolded" to obtain a MUL-tree $U(N)$ and, conversely, a MUL-tree $T$ can in certain circumstances be "folded" to obtain a phylogenetic network $F(T)$ that exhibits $T$. In this paper, we study properties of the operations $U$ and $F$ in more detail. In particular, we introduce the class of stable networks, phylogenetic networks $N$ for which $F(U(N))$ is isomorphic to $N$, characterise such networks, and show that they are related to the well-known class of tree-sibling networks.We also explore how the concept of displaying a tree in a network $N$ can be related to displaying the tree in the MUL-tree $U(N)$. To do this, we develop a phylogenetic analogue of graph fibrations. This allows us to view $U(N)$ as the analogue of the universal cover of a digraph, and to establish a close connection between displaying trees in $U(N)$ and reconcilingphylogenetic trees with networks

Evolution of photochemical reaction centres: more twists?

One of the earliest events in the molecular evolution of photosynthesis is the structural and functional specialisation of Type I (ferredoxin-reducing) and Type II (quinone-reducing) reaction centres. In this opinion article we point out that the homodimeric Type I reaction centre of Heliobacteria has a calcium-binding site with striking structural similarities to the Mn4CaO5 cluster of Photosystem II. These similarities indicate that most of the structural elements required to evolve water oxidation chemistry were present in the earliest reaction centres. We suggest that the divergence of Type I and Type II reaction centres was made possible by a drastic structural shift linked to a change in redox properties that coincided with or facilitated the origin of photosynthetic water oxidation