Two‐dimensional coordination polymers (2DCPs) have been predicted to exhibit exotic properties such as superconductivity, topological insulating behavior, catalytic activity, and superior ion ...transport for energy applications; experimentally, these materials have fallen short of their expectation due to the lack of synthesis protocols that yield continuous, large crystallite domains, and highly ordered thin films with controllable physical and chemical properties. Herein, the fabrication of large‐area, highly ordered 2DCP thin films with large crystallite domains using chemical vapor deposition (CVD) approaches is described. It is demonstrated that defects and the packing motifs of 2DCP thin films may be controlled by adjusting the vapor–vapor and vapor–solid interactions of the metal and organic linker precursors during the CVD fabrication process. Such control allows for the fabrication of defects‐controlled 2DCP thin films that show either semiconducting or metallic behavior. The findings provide the first demonstration of tuning the electrical properties of sub 100 nm‐thick continuous 2DCP thin films by controlling their electronic landscape through defect engineering. As such, it is determined that large‐area, highly ordered 2DCP thin films may undergo a semiconducting to metallic transition that is correlated to changes in morphology, crystalline domain sizes, crystallite orientation, defect interactions, and electronic structure.
The emerging theme of “Materials Genome” inspires exciting opportunities for the design of large‐area, highly oriented 2D coordination polymer thin films where semiconducting and metallic behavior may be controlled at will to enable unprecedented device applications in the area of quantum electronics.
Two approaches to the total synthesis of the dimeric Lycopodium alkaloid complanadine B have been achieved. In the first approach (see scheme; route 1), a keto lycodine unit is coupled to another ...lycodine unit whereas in the latter approach (route 2), selective oxygenation of one of two pseudo‐benzylic positions is achieved.
It has recently been shown that surface energy effects can cause selective segregation at the active layer interfaces of a bulk heterojunction (BHJ) organic photovoltaic device. The active layer ...interface composition has been suggested to impact device performance. In this study changes in the BHJ vertical composition profile of BHJ active layers cast on two hole transport layers (HTL) with significantly different surface energies (γ) are characterized using spectroscopic ellipsometry and near-edge X-ray absorption fine structure spectroscopy. Changes in the HTL γ are shown to significantly affect the BHJ interfacial segregation at the buried interface near the HTL while the composition near the free surface (air) of the BHJ is unaffected. Despite the significant differences in vertical segregation at the HTL interface, the performances of the resulting organic photovoltaic devices were relatively similar.
Background Insulin is a mainstay of treatment in diabetic ketoacidosis (DKA) however controversy remains over the optimal dose and administration. An initial bolus dose of insulin prior to a ...continuous infusion is utilized despite a lack of data showing clinical benefit and potential for complications. Objective This study was designed to evaluate the safety and efficacy of an initial insulin bolus in the treatment of DKA. Methods A retrospective chart review of patients with DKA was conducted. Fifty-nine patients met inclusion for the bolus group and 108 in the no-bolus group. The primary outcome was a composite of interruption of insulin infusion, hypoglycemia (BG <70 mg/dL), or hypokalemia (K+ <3.4 mEq/L) occurring within eight hours of starting insulin. Secondary outcomes included time to discontinuation of insulin infusion, as well as time to discharge from the ICU and the hospital. Results Baseline characteristics were similar between groups. The majority of patients were classified as having mild DKA. The primary outcome occurred significantly more frequently in the bolus group (45.8% vs 25%, P = .003) which was primarily driven by incidence of hypokalemia. Time to anion gap closure (6:39 vs 9:00, P = .063) was shorter with a bolus, although not significantly so. This finding carried forward to non-significant differences in time to stopping insulin infusion as well as ICU and hospital discharge. Conclusion An insulin bolus prior to initiation of an insulin infusion was associated with significantly more adverse effects early in therapy without a corresponding benefit in time to resolution of DKA.
High performance, solution processable semiconductors are critical to the realization of low cost, large area electronics. We show that a signature molecular packing motifside-chain ...interdigitationcorrelates to high performance for a large and important class of organic semiconductors. The side chains of recently developed high performance copolymers of poly(alkylthiophenes) can and do interdigitate substantially, whereas they do not in the most common form of the extensively studied, lower performance poly(alkythiophenes). Side-chain interdigitation provides a mechanism for three-dimensional ordering; without it, poly(alkylthiophenes) are limited to small domains and poor performance. We propose the synthetic design rule that three-dimensional ordering is promoted by side-chain attachment densities sufficiently low to permit interdigitation.
Background
The literature on botulinum neurotoxin type A (BoNT‐A) is extensive, often contradictory, and confounded by a competitive market of products and research attempting to distinguish brand ...individuality.
Methods
A comprehensive review of literature on the principles of BoNT‐A in aesthetics as well as clinical examples.
Results
In 2017, the Eight Key Clinical Postulates were formulated as a guide for the aesthetic practitioner in understanding BoNT‐A pharmacodynamics and to compare different toxins. These are now updated to include (a) All type A toxins act identically; (b) The mathematical relationship between toxin and receptor is the basis of efficacy, and clinical efficacy is influenced by molecular potency and patient attributes including muscle mass, gender, age, and ethnicity; (c) Efficacy, onset, and duration are functions of “molecular potency” defined as the number of active 150 kDa molecules available for binding; (d) “Molecular potency” is difficult to objectively quantify for commercially available toxins; (e) Up to a point, increased molecular potency decreases time to onset and increases duration of effect, and the “Molecular Potency Quotient” is a construct for comparing molecular potency commercial cost; (f) The area of effect of a toxin injection is dependent upon molecular potency, diffusion (passive), and spread (active); (g) Differing reconstitution volumes; and (h) Increased number of injection sites can affect spread, onset, and duration of effect.
Conclusions
The principles of BoNT‐A use in aesthetics are complex yet understandable as outlined in the framework of the updated Eight Key Clinical Postulates and serves as a useful tool for providing the most effective treatment and interpreting research on present and future toxin formulations.
The characterization of the microstructure and molecular orientation is critical to understanding the performance of conjugated polymer semiconductors. In this work, near-edge X-ray absorption fine ...structure (NEXAFS) spectroscopy was used to study the molecular orientation of blade-coating thin films of regioregular PCDTPT (poly4-(4,4-dihexadecyl-4H-cyclopenta1,2-b:5,4-b′dithiophen-2-yl)-alt-1,2,5thiadiazolo3,4-cpyridine) on substrates with and without uniaxial nanogrooves. The prediction of NEXAFS spectra through density functional theory calculations allowed for the interpretation of the experimental spectral features and provided information about molecular orientation. Using the polarization dependence of the Nitrogen 1s to π*-resonance signals, the molecular orientation was quantified through calculations of the order parameters S (out-of-plane) and η (in-plane) for both the top side and bottom side of the film. All films have out-of-plane orientation where the conjugated backbones have a preferential “edge-on” alignment relative to the substrate surface. On the other hand, with increasing blade-coating rates, the greatest degree of in-plane polymer-chain orientation occurs on the bottom side of a film deposited on a nanogrooved substrate. The results demonstrate the utility of the nanogroove method to induce alignment of solution-processed semiconducting polymers.
Genome-wide studies have already shed light into the evolution and enormous diversity of the viral world. Nevertheless, one of the unresolved mysteries in comparative genomics today is the abundance ...of ORFans - ORFs with no detectable sequence similarity to any other ORF in the databases. Recently, studies attempting to understand the origin and functions of bacterial ORFans have been reported. Here we present a first genome-wide identification and analysis of ORFans in the viral world, with focus on bacteriophages.
Almost one-third of all ORFs in 1,456 complete virus genomes correspond to ORFans, a figure significantly larger than that observed in prokaryotes. Like prokaryotic ORFans, viral ORFans are shorter and have a lower GC content than non-ORFans. Nevertheless, a statistically significant lower GC content is found only on a minority of viruses. By focusing on phages, we find that 38.4% of phage ORFs have no homologs in other phages, and 30.1% have no homologs neither in the viral nor in the prokaryotic world. Phages with different host ranges have different percentages of ORFans, reflecting different sampling status and suggesting various diversities. Similarity searches of the phage ORFeome (ORFans and non-ORFans) against prokaryotic genomes shows that almost half of the phage ORFs have prokaryotic homologs, suggesting the major role that horizontal transfer plays in bacterial evolution. Surprisingly, the percentage of phage ORFans with prokaryotic homologs is only 18.7%. This suggests that phage ORFans play a lesser role in horizontal transfer to prokaryotes, but may be among the major players contributing to the vast phage diversity.
Although the current sampling of viral genomes is extremely low, ORFans and near-ORFans are likely to continue to grow in number as more genomes are sequenced. The abundance of phage ORFans may be partially due to the expected vast viral diversity, and may be instrumental in understanding viral evolution. The functions, origins and fates of the majority of viral ORFans remain a mystery. Further computational and experimental studies are likely to shed light on the mechanisms that have given rise to so many bacterial and viral ORFans.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The 5/6s2 lone-pair electrons of p-block cations in their lower oxidation states are a versatile electronic and geometric structure motif that can underpin lattice anharmonicity and often engender ...electronic and structural instabilities that underpin the function of active elements in nonlinear optics, thermochromics, thermoelectrics, neuromorphic computing, and photocatalysis. In contrast to periodic solids where lone-pair-bearing cations are part of the structural framework, installing lone-pair-bearing cations in the interstitial sites of intercalation hosts provides a means of a systematically modulating electronic structure through the choice of the group and the period of the inserted cation while preserving the overall framework connectivity. The extent of stereochemical activity and the energy positioning of lone-pair-derived mid-gap states depend on the cation identity, stoichiometry, and strength of anion hybridization. V2O5 polymorphs are versatile insertion hosts that can accommodate a broad range of s-, p-, and d-block cations. However, the insertion of lone-pair-bearing cations remains largely underexplored. In this article, we examine the implications of varying the 6s2 cations situated in interlayer sites between condensed V4O10 n double layers. Systematic modulations of lattice distortions, electronic structure, and magnetic ordering are observed with increasing strength of stereochemical activity from group 12 to group 14 cations. We compare and contrast p-block-layered M x V2O5 (M = Hg, Tl, and Pb) compounds and map the significance of local off-centering arising from the stereochemical activity of lone-pair cations to the emergence of filled antibonding lone-pair 6s2–O 2p-hybridized mid-gap states mediated by second-order Jahn–Teller distortions. Crystallographic studies of cation coordination environments and the resulting modulation of V–V interactions have been used in conjunction with variable-energy hard X-ray photoelectron spectroscopy measurements, first-principles electronic structure calculations, and crystal orbital Hamilton population analyses to decipher the origins of stereochemical activity. Magnetic susceptibility measurements reveal antiferromagnetic signatures for all the three compounds. However, the differences in V–V interactions significantly affect the energy balance of the superexchange interactions, resulting in an ordering temperature of 160 and 260 K for Hg0.5V2O5 and δ-Tl0.5V2O5, respectively, as compared to 7 K for δ-Pb0.5V2O5. In δ-Pb0.5V2O5, the strong stereochemical activity of electron lone pairs and the resulting electrostatic repulsions enforce superlattice ordering, which strongly modifies the electronic localization patterns along the V4O10 slabs, resulting in disrupted magnetic ordering and an anomalously low ordering temperature. The results demonstrate a versatile strategy for toggling the stereochemical activity of electron lone pairs to modify the electronic structure near the Fermi level and to mediate superexchange interactions.
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