Selection of Loss Function in Covariance Structure Analysis: Case of the Spherical Model

In this paper, we derive the asymptotic properties of estimators obtained from various kinds of loss functions in covariance structure analysis. We first show that the estimators except for OLS-based loss functions have the same asymptotic distribution when the dimension of the covariance matrix, p, is fixed and the sample size n tends to infinity. Then, focusing on the spherical model, we show that this equivalence does not hold when both n and p become larger. Specifically, we show that some estimators lose consistency, and even consistent estimators have different asymptotic variances. Among the estimators considered, the maximum likelihood estimator shows the best performance, while the less famous invGLS(ub) estimator performs better than the commonly used GLS estimator. We also demonstrate the validity of the likelihood ratio test for the spherical and diagonal models in a high-dimensional framework.</p

Data_Sheet_1_Association between omega-3/6 fatty acids and cholelithiasis: A mendelian randomization study.docx

BackgroundOmega-3 and omega-6 may be protective factors for cholelithiasis. However, this relationship has not yet been demonstrated clearly. Therefore, we attempted to identify these causal relationships.Materials and methodsThe omega-3/6 fatty acid discovery dataset was obtained from UK Biobank and contained 114,999 individuals. The validation set was derived from an independent genome-wide association study (GWAS) and contained 13,544 individuals. The cholelithiasis dataset was derived from FinnGen and contained 19,023 cases and 195,144 controls. The inverse variance weighting (IVW) method was used as the main method of analysis in this study. Multiple methods of analysis were also used in the repeated methods, including the MR-Egger, weighted median, MR-pleiotropic residual sum (MR-PRESSO), outliers, and maximum likelihood methods. In addition, we used multiple sensitivity analyses to identify the potential pleiotropy.ResultIn the discovery stage, the results of the random effect IVW analysis showed that higher omega-3 levels were correlated inversely with the risk of cholelithiasis (β = –0.22, 95% CI [–0.32 to –0.12], P = 1.49 × 10–5). When the replication analysis was performed using another set of instrumental variables (IVs), the causal relationship between omega-3 fatty acids and cholelithiasis remained stable (β = –0.42, 95% CI [–0.66 to –0.18], P = 5.49 × 10–4), except for the results obtained using the MR-Egger method, which were not significant. The results of the IVW approach showed that each SD increase in omega-6 levels was associated negatively with the risk of cholelithiasis, both in the discovery (β = –0.21, 95% CI [–0.35 to –0.06], P = 4.37 × 10–3) and the validation phases (β = –0.21, 95% CI [–0.40 to –0.02], P = 3.44 × 10–2).ConclusionThe results of our MR study suggest that omega-3/6 is associated with cholelithiasis risk. Attention to the risk of cholelithiasis in individuals with low serum omega-3/6 levels is necessary.</p

Desulfitative Cross-Coupling of Protecting Group-Free 2-Thiouracil Derivatives with Organostannanes

We here report a unique and efficient copper bromide mediated pallado-catalyzed coupling of protecting group-free 2-thiouracil derivatives with organostannanes. The nature of the copper appears to be crucial for successful cross coupling

Selective Disruption of Early/Recycling Endosomes: Release of Disulfide-Linked Cargo Mediated by a <i>N</i>-Alkyl-3β-Cholesterylamine-Capped Peptide

Selective Disruption of Early/Recycling Endosomes: Release of Disulfide-Linked Cargo Mediated by a N-Alkyl-3β-Cholesterylamine-Capped Peptid

Practical Synthesis of 3β-Amino-5-cholestene and Related 3β-Halides Involving <i>i</i>-Steroid and Retro-<i>i</i>-Steroid Rearrangements

Derivatives of 3β-amino-5-cholestene (3β-cholesterylamine) are of substantial interest as cellular probes and have potential medicinal applications. However, existing syntheses of 3β-amino-5-cholestene are of limited preparative utility. We report here a practical method for the stereoselective preparation of 3β-amino-5-cholestene, 3β-chloro-5-cholestene, 3β-bromo-5-cholestene, and 3β-iodo-5-cholestene from inexpensive cholesterol. A sequential i-steroid/retro-i-steroid rearrangement promoted by boron trifluoride etherate and trimethylsilyl azide converted cholest-5-en-3β-ol methanesulfonate to 3β-azido-cholest-5-ene with retention of configuration in 93% yield

Workflow for Large Scale Detection and Validation of Peptide Modifications by RPLC-LTQ-Orbitrap: Application to the <i>Arabidopsis thaliana</i> Leaf Proteome and an Online Modified Peptide Library

Post-translational modifications (PTMs) of proteins add to the complexity of proteomes, thereby complicating the task of proteome characterization. An efficient strategy to identify this peptide heterogeneity is important for determination of protein function, as well as for mass spectrometry-based protein quantification. Furthermore, studies of allelic variation or single nucleotide polymorphisms (SNPs) at the proteome level, as well as mRNA editing, are increasingly relevant, but validation and determination of false positive rates are challenging. Here we describe an effective workflow for large scale PTM and amino acid substitution identification based on high resolution and high mass accuracy RPLC-MS data sets. A systematic validation strategy of PTMs using RPLC retention time shifts was implemented, and a decision tree for validation is presented. This workflow was applied to Arabidopsis proteome preparations; 1.5 million MS/MS spectra were processed resulting in 20% sequence assignments, with 5% from modified sequences and matching to 2904 proteins; this high assignment rate is in part due to the high quality spectral data. A searchable modified peptide library for Arabidopsis is available online at http://ppdb.tc.cornell.edu/. We discuss confidence in peptide and PTM assignment based on the acquired data set, as well as implications for quantitative analysis of physiologically induced and preparation-related modifications

Aluminated Derivatives of Porous Magadiite Heterostructures for Acid-Catalyzed <i>tert</i>-Butylation of Catechol

Novel porous magadiite/Al-magadiite heterostructures (PMH/PAMH) and aluminated derivatives of PMH (<i>x</i>Al-PMH, <i>x</i> = Al/Si in feeding) were fabricated upon two-dimensional interlayer cosurfactant-directing TEOS hydrolysis–condensation–polymerization from synthetic Na-magadiite/Na-[Al]­magadiite and postgrafting of Al into the interlayer silica framework of PMH from NaAlO₂ precursor, respectively. Characterization studies indicate that PMH and PAMH possess high surface area (SA), high thermal stability, and unique supermicro–mesoporous structure upon effective assembly of interlayer mesostructured silica and clay layers but weak Lewis acidity. The <i>x</i>Al-PMH (<i>x</i> = 0.2, 0.4) samples show successful incorporation of Al into interlayer mesostructure of PMH mainly in tetra-coordinated form, leading to greatly increased Lewis acidity and newly created Brønsted acidity together with well-kept layered supermicro-mesoporous porosity and reduced SA (>280 m²/g) while 0.6Al-PMH shows collapsed layers. 0.4Al-PMH exhibits the highest liquid-phase Friedel–Crafts <i>tert</i>-butylation activity of catechol with 93.4% conversion and 80.4% 4-<i>tert</i>-butylcatechol selectivity due to the strongest synergy between the surface acidity and supermicro–mesostructure

Tailored Porous Organic Polymers for Task-Specific Water Purification

ConspectusThe Industrial Revolution has resulted in social and economic improvements, but unfortunately, with the development of manufacturing and mining, water sources have been pervaded with contaminants, putting Earth’s freshwater supply in peril. Therefore, the segregation of pollutantssuch as radionuclides, heavy metals, and oil spillsfrom water streams, has become a pertinent problem. Attempts have been made to extract these pollutants through chemical precipitation, sorbents, and membranes. The limitations of the current remediation methods, including the generation of a considerable volume of chemical sludge as well as low uptake capacity and/or selectivity, actuate the need for materials innovation. These insufficiencies have provoked our interest in the exploration of porous organic polymers (POPs) for water treatment. This category of porous material has been at the forefront of materials research due to its modular nature, i.e., its tunable functionality and tailorable porosity. Compared to other materials, the practicality of POPs comes from their purely organic composition, which lends to their stability and ease of synthesis. The potential of using POPs as a design platform for solid extractors is closely associated with the ease with which their pore space can be functionalized with high densities of strong adsorption sites, resulting in a material that retains its robustness while providing specified interactions depending on the contaminant of choice.POPs raise opportunities to improve current or enable new technologies to achieve safer water. In this Account, we describe some of our efforts toward the exploitation of the unique properties of POPs for improving water purification by answering key questions and proposing research opportunities. The design strategies and principles involved for functionalizing POPs include the following: increasing the density and flexibility of the chelator to enhance their cooperation, introducing the secondary sphere modifiers to reinforce the primary binding, and enforcing the orientation of the ligands in the pore channel to increase the accessibility and cooperation of the functionalities. For each strategy, we first describe its chemical basis, followed by presenting examples that convey the underlying concepts, giving rise to functional materials that are beyond the traditional ones, as demonstrated by radionuclide sequestration, heavy metal decontamination, and oil-spill cleanup. Our endeavors to explore the applicability of POPs to deal with these high-priority contaminants are expected to impact personal consumer water purifiers, industrial wastewater management systems, and nuclear waste management. In our view, more exciting will be new applications and new examples of the functionalization strategies made by creatively merging the strategies mentioned above, enabling increasingly selective binding and efficiency and ultimately promoting POPs for practical applications to enhance water security

A Tri-Layer Structural Film Containing Nickel Nanocoating for Electromagnetic Transmittance and Joule Heating

In the realm of military applications, the effective management of ice accumulation on strategic equipment without compromising the integrity of the electromagnetic signal transmission is a perennial challenge. To confront this issue, a revolutionary trilayered material composite known as MPE (metal-polyimide-electric heating layer) has been developed, demonstrating a sophisticated balance between deicing functionality and electromagnetic transparency. The MPE composite is ingeniously architected in a trilayer configuration, comprising a frequency-selective wave-transmissive stratum, an interjacent insulating dielectric interlayer, and an electric heating layer. The former is the result of a pioneering surface grafting modality of keratin, subsequently metallized with a nickel (Ni) coat via a chemical plating technique, which concurrently imparts the composite with a temperature-sensitivity range between −10 and 80 °C. The latter is formulated from a cyanate ester (CE) resin with organic conductive fillers, endowing the material with a high thermal threshold of up to 220 °C. Experimental evaluations of the MPE material have yielded a remarkable 88% transmissivity at the designated resonant frequency, a significant improvement over traditional graphene heating layer. This high level of performance, combined with the material’s inherent deicing properties and the capacity for remote control via integrated sensing technology, positions the MPE as a substantial breakthrough for military operations

An open framework for infinite walking with saccadic redirection

In this project we created an expandable framework for allowing infinite walking in virtual reality in a closed play area. A saccade is a rapid eye movement with a unique property: the eye temporarily gathers reduced information - saccadic suppression. We leverage the suppression to redirect the user's walking towards the center of the play area by rotating the virtual world around the camera's location. With the VR environment and corresponding pre and post experience questions we could already show an improvement in understanding on a set of participants. Modern VR hardware such as the Vive Eye Pro allows a reasonable sample rate of eye movement measurements. A self-developed VR testing environment was used and with corresponding pre and post experience questions we tested a group of participants regarding general motion and VR- sickness parameters. We found a certain angle for the maximum saccade rotation which was base of further testing. We found, that our framework and the default settings successfully allow saccadic redirection with only marginal discomfort for the users.</p