Postsynthetic modification of zirconium metal-organic frameworks

Metal-organic frameworks (MOFs) have been in the spotlight for a number of years due to their chemical and topological versatility. As MOF research has progressed, highly functionalised materials have become desirable for specific applications, and in many cases the limitations of direct synthesis have been realised. This has resulted in the search for alternative synthetic routes, with postsynthetic modification (PSM), a term used to collectively describe the functionalisation of pre-synthesised MOFs whilst maintaining their desired characteristics, becoming a topic of interest. Advances in the scope of reactions performed are reported regularly; however reactions requiring harsh conditions can result in degradation of the framework. Zirconium-based MOFs present high chemical, thermal and mechanical stabilities, offering wider opportunities for the scope of reaction conditions that can be tolerated, which has seen a number of successful examples reported. This microreview discusses pertinent examples of PSM resulting in enhanced properties for specific applications, alongside fundamental transformations, which are categorised broadly into covalent modifications, surface transformations, metalations, linker and metal exchange, and cluster modifications

Crystallographic investigation into the self-assembly, guest binding, and flexibility of urea functionalised metal-organic frameworks

Introduction of hydrogen bond functionality into metal-organic frameworks can enhance guest binding and activation, but a combination of linker flexibility and interligand hydrogen bonding often results in the generation of unwanted structures where the functionality is masked. Herein, we describe the self-assembly of three materials, where Cd2+, Ca2+, and Zn2+ are linked by N,Nʹ-bis(4-carboxyphenyl)urea, and examine the effect of the urea units on structure formation, the generation of unusual secondary building units, structural flexibility, and guest binding. The flexibility of the Zn MOF is probed through single-crystal to single-crystal transformations upon exchange of DMF guests for CS2, showing that the lability of the [Zn4O(RCO2)6] cluster towards solvation enables the urea linkers to adopt distorted conformations as the MOF breathes, even facilitating rotation from the trans/trans to the trans/cis conformation without compromising the overall topology. The results have significant implications in the mechanistic understanding of the hydrolytic stability of MOFs, and in preparing heterogeneous organocatalysts

Algal Metallothioneins: Synthesis and regulation of two putative metallothioneins within the blue-green cyanobacteria anacystis nidulans

Metallothioneins are low molecular-weight, cysteine-rich, trace metal-binding proteins. Whereas class III metallothioneins (MTs) have been isolated in eukaryotic algae, Anacystis nidulans (Synechococcus TX20) remains the only prokaryote in which a class II MT has been isolated and characterized. Cadmium binding ligands produced in response to cadmium were separated using gel permeation HPLC, DEAE and a variety of physical methods. Results indicated that, in addition to the class II MT previously isolated, putative class III (gammaEC)(_n)G polypeptides may have been induced by the cadmium ions. An attempt was made to isolate and characterize the first prokaryotic metallothionein gene. Two synthetic oligonucleotides analogous to the Synechococcus TX20 MT protein were used as extension primers in an attempt to amplify the MT gene locus

Entrepreneurship inside and out: Three essays exploring the interplay between hybrid entrepreneurs and their organizational employee roles

A growing body of research focuses on undertaking new venture creation while remaining employed in existing organizations. Known as hybrid/part-time entrepreneurship, scholars suggest most entrepreneurs engage in entrepreneurship in a part-time capacity. As such, there exists an interesting space for the study of a new form of interrole dynamics: employee and entrepreneurial role interactions. Through three essays, I conceptually and empirically explore the effects of engaging in hybrid entrepreneurship on outcomes associated with employee and entrepreneurial roles. In Essay One I present a theoretical model of role enrichment from entrepreneurial to employee roles. Specifically, I propose that individuals engaged in entrepreneurship in a part-time capacity develop a unique skillset through entrepreneurial learning which can be effectively applied to tasks in employee roles in the form of recognizing and exploiting opportunities for innovation. In Essay Two, I empirically test these role enrichment hypotheses using a primary data sample of 1,245 employees; many of whom are engaged in part-time entrepreneurship. Results confirm that people engaged in running side businesses exhibit greater innovative behavior at work, especially in work groups that foster climates conducive for innovation and for individuals with goal orientations toward learning. In Essay Three, I examine the potentially negative effects of hybrid entrepreneurship on outcomes in both employee and entrepreneurial roles and test the existence of “work-venture” conflict through a sample of 34 entrepreneurs surveyed over several weeks. Results confirm negative impacts from conflict to satisfaction in employee roles and bricolage behaviors in entrepreneurial roles, and a positive impact on intentions to leave employee roles

Invoice from Ross & Marshall to Ogden Goelet

https://digitalcommons.salve.edu/goelet-personal-expenses/1071/thumbnail.jp

Tuning the endocytosis mechanism of Zr-based metal−organic frameworks through linker functionalization

A critical bottleneck for the use of metal-organic frameworks (MOFs) as drug delivery systems has been allowing them to reach their intracellular targets without being degraded in the acidic environment of the lysosomes. Cells take up particles by endocytosis through multiple biochemical pathways, and the fate of these particles depends on these routes of entry. Here, we show the effect of functional group incorporation into a series of Zr-based MOFs on their endocytosis mechanisms, allowing us to design an effi-cient drug delivery system. In particular, naphthalene-2,6-dicarboxylic acid and 4,4'-biphenyldicarboxylic acid ligands promote entry through the caveolin-pathway, allowing the particles to avoid lysosomal degradation and be delivered into the cytosol, en-hancing their therapeutic activity when loaded with drugs

The design, analysis and evaluation of a food frequency questionnaire for assessing the nutrient intake of New Zealand adults

A food frequency questionnaire was designed to assess the usual nutrient intake of New Zealand adults. National diet survey data was used as a basis for compiling the food list. The optimal design and analysis of the 132 item food frequency questionnaire was determined by a series of analyses using diet intake data from a sample of 101 female undergraduate Nutrition students (mean age 21 years). The performance of the food frequency questionnaire was assessed by comparison with seven-day diet records. The nutrients used in this comparison were ones of special consideration for New Zealanders according to the Nutrition Taskforce (1991), i.e carbohydrate, starch, sugars, fat, saturated fat, polyunsaturated fat, protein, dietary fibre, calcium, iron, zinc, thiamin and ascorbic acid. The comparison methods used were mean difference, standard deviation of the difference, classification into the same or adjacent quintile, gross misclassification, correlation coefficients and actual values for surrogate categories. There is a need for further investigation into the sensitivity of the 'classification into the same of adjacent quintile' method for assessing the ability of the food frequency questionnaire to classify subjects. The use of a statistical test to assess the significance in changes in classification is necessary. The use of more than five categories, e.g. 7 or 9, requires consideration for a more sensitive measure of the food frequency questionnaire's ability to classify individuals. General principles were formulated according to the effect of the design and analysis issues on the food frequency questionnaire's performance. The food frequency questionnaire's ability to estimate the group mean intake was enhanced through use of a categorical response scale format (rather than an open-ended scale), age and sex specific serving sizes (rather than common standard measures) and adjustments for the total servings of fruit, vegetables and meat. The food frequency questionnaire's ability to classify individuals was enhanced through use of a categorical response scale format (rather than an open-ended scale), use of common standard measures as serving sizes, and asking the respondent to specify small, medium or large serving sizes

Tin perovskite/fullerene planar layer photovoltaics : improving the efficiency and stability of lead-free devices

We report the first demonstration of orthorhombic CsSnI3 films prepared from solution at room temperature that have defect densities low enough for use as the light harvesting semiconductor in photovoltaic devices even without using excess Sn in the preparative method, and demonstrate their utility in a model p–i–n photovoltaic device based on a CuI | CsSnI3 | fullerene planar layer architecture. We also report an effective strategy for simultaneously improving both the efficiency and stability of these devices towards air exposure based on the use of excess of SnI2 during CsSnI3 synthesis from CsI and SnI2. A combination of photoelectron spectroscopy, contact potential measurements and device based studies are used to elucidate the basis for this improvement and role of the excess SnI2. The open-circuit voltage in these lead-free photovoltaic devices is shown to be strongly dependent on the degree of alignment between the perovskite conduction band edge and the lowest occupied molecular orbital (LUMO) in the fullerene electron transport layer. Furthermore, the energetics at the perovskite–fullerene interface are shown to be a function both of the LUMO energy of the fullerene and the nature of the interaction at the heterojunction which can give rise to a large abrupt vacuum level shift across the interface. A champion open-circuit voltage of ∼0.55 V is achieved using indene-C60 bis-adduct as the electron extraction layer, which is twice that previously reported for a CsSnI3 based PPV

Youth and the communication of Risk: developing connections between cancer council Australia and contemporary online youth culture

Through two focus groups, the project investigated how youth culture perceives online communication of risk. In two 90-minute sessions, investigators gaged the range of online activities that nine 18 - 24 year old university students engaged with. Through a guided discussion the participants explored how they would relate to the communication of health risk more generally and cancer risk more specifically.Participants’ online activity is very high and a range of social media forms are part of their everyday lives. In contrast, their use of traditional media is almost non-existent. Their relationship to accessing and being aware of health information demonstrated a range of views that pointed to quite new and different relationships to health and health professionals. To intersect with their online movements in the communication of health risk demands a sophisticated knowledge of their own searching patterns.Key ideas generated from the focus groups include: that it might be advantageous to group health risk beyond the specificity of cancer for online success; that an online persona would be useful to provide a face for the communication of risk; that a multi-platform campaign to raise the profile of a persona would be useful; and that success means moving between the serious and the light-hearted in a way that makes the persona a complete person of interest for them