Analytical Solution of the Relativistic Coulomb Problem with a Hard-Core Interaction for a One-Dimensional Spinless Salpeter Equation

In this paper, we construct an analytical solution of the one-dimensional spinless Salpeter equation with a Coulomb potential supplemented by a hard core interaction, which keeps the particle in the x positive region

Synthesis of highly substituted alkenes by sulfur-mediated olefination of N-tosylhydrazones

Tetraphenylethylenes (TPEs) are well-known for their aggregation-induced emission properties. The synthesis of TPE derivatives, as well as other highly substituted olefins, generally requires the use of hazardous reagents, such as metalorganic compounds, to overcome the high activation energies caused by the sterically congested double bond. Herein, we present an efficient and metal-free procedure for the synthesis of tetraarylethylenes via alkylidene-homocoupling of N-tosylhydrazones, derived from readily available benzophenones, in excellent yields. The method relies only on cheap and benign additives, i.e. elemental sulfur and potassium carbonate, and easily competes with other established procedures in terms of scope, yield and practicability. A mechanistic study revealed a diazo compound, a thioketone and a thiirane as key intermediates in the pathway of the reaction. Based on this, a modified method, which allows for selective alkylidene-cross-coupling, generating a broader scope of tri- and tetrasubstituted olefins in good yields, is showcased as well

Novel Access to Known and Unknown Thiourea Catalyst via a Multicomponent-Reaction Approach

Thioureas are frequently used in organocatalysis and typically rely on 3,5‐bis(trifluoromethyl) phenyl moieties motifs to enhance their catalytic activity. In this work, these common motifs were replaced with tailorable functional groups, such as ester or sulfone aryls, applying elemental sulfur in a multicomponent reaction (MCR) strategy for the first time for thiourea catalyst synthesis. First, several thioureas bearing aryl, benzylic or aliphatic moieties were synthesized and tested for their hydrogen bonding strength by evaluating thiourea phosphine oxide complexes via $^{31}$P NMR and their catalytic activity in an Ugi four‐component reaction (U‐4CR). Finally, ester and sulfone aryl thioureas were tested in the aminolysis of propylene carbonate, leading to conversions similar to those previously reported in the literature using the 3,5‐bis(trifluoromethyl)phenyl moiety, proving that these groups are suitable alternatives for the trifluoromethyl group

A more sustainable isothiocyanate synthesis by amine catalyzed sulfurization of isocyanides with elemental sulfur

Isothiocyanates (ITCs) are typically prepared using amines and highly toxic reagents such as thiophosgene, its derivatives, or CS$_{2}$. In this work, an investigation of a multicomponent reaction (MCR) using isocyanides, elemental sulfur and amines revealed that isocyanides can be converted to isothiocyanates using sulfur and catalytic amounts of amine bases, especially DBU (down to 2 mol%). This new catalytic reaction was optimized in terms of sustainability, especially considering benign solvents such as Cyrene™ or γ-butyrolactone (GBL) under moderate heating (40 °C). Purification by column chromatography was further optimized to generate less waste by maintaining high purity of the product. Thus, E-factors as low as 0.989 were achieved and the versatility of this straightforward procedure was shown by converting 20 different isocyanides under catalytic conditions, while obtaining moderate to high yields (34–95%)

A more sustainable and highly practicable synthesis of aliphatic isocyanides

Synthesis protocols to convert N-formamides into isocyanides using three different dehydration reagents (i.e. p-toluenesulfonyl chloride (p-TsCl), phosphoryl trichloride (POCl3) and the combination of triphenylphosphane (PPh3) and iodine) were investigated and optimized, while considering the principles of green chemistry. Comparison of the yield and the E-factors of the different synthesis procedures revealed that, in contrast to the typically applied POCl3 or phosgene derivatives, p-TsCl was the reagent of choice for non sterically demanding aliphatic mono- or di-N-formamides (yields up to 98% and lowest E-factor 6.45). Apart from a significantly reduced E-factor, p-TsCl is cheap, offers a simplified reaction protocol and work-up, and is less toxic compared to other dehydration reagents. Thus, this procedure offers easier and greener access to aliphatic isocyanide functionalities

Alternative Approaches to the Validation of Nondestructive Testing Methods

There is currently considerable interest in devising appropriate means for measuring how well test methods suit their avowed purpose. One of the major expressions of this interest has been through implementation of standards and guidelines issued by ISO/IEC (International Organization for Standardization/International Electrotechnical Commission) and, in Europe, CEN/CENELEC (European Committee for Standardization/European Commission for Electrotechnical Standardization). Among the goals of the ISO 9000 family of International Standards is provision of quality system guidelines [1] to complement the specific product requirements that are typically incorporated in specifications provided by “customers”. These criteria are intended to aid “suppliers” in achieving continuing improvements in product quality and customer satisfaction. Four key “facets of quality” are identified, associated with a) definition of needs for the product; b) aspects of product design that influence performance of the product; c) consistency in conforming to the product design; and d) providing life-cycle product support

Removal of Transition-Metal Ions by Metal-Complexing Polythiosemicarbazone Membranes

Membrane technology is one of the many strategies to remove transition-metal ions from aqueous streams because of its relatively lower costs and ease of operation. Typically, adsorbent materials are added into polymeric membranes to impart chelating/complexing properties, but this often results in a limited number of adsorption sites within the membrane. In this work, polythiosemicarbazone (pTSC) is proposed as a material to prepare polymeric membranes due to its metal-complexing ligands in the backbone, providing more adsorption sites. The polymer was easily processed into membranes via the nonsolvent-induced phase separation technique and exhibited asymmetric structures with adequate mechanical strength. The porosity of the membranes was controlled by increasing the polymer concentration in the casting solution, leading to ultrafiltration- and nanofiltration-type membranes with permeabilities ranging from 30 to 0.7 L·m$^{–2}$·h$^{–1}$·bar$^{–1}$. The resulting pTSC membranes were applied for the removal of silver and copper ions in batch and, in the case of silver ions, also in dynamic adsorption experiments. The maximum removal rate of 17 mg·g$^{–1}$ for silver and 3.8 mg·g$^{–1}$ for copper ions was obtained in the batch removal experiment. Streaming potential, pH measurements, and infrared spectroscopy (FTIR) were conducted to verify the anionic binding of TSC groups, while neutral binding modes were revealed by FTIR and batch removal experiments. Furthermore, the removal of silver ions was also successfully demonstrated in a flow setup operated at 4 bar of applied pressure. The streaming potential and energy-dispersive X-ray (EDX) spectroscopy conducted on the membranes after the flow tests confirmed the complexation by TSC-functional groups as the separation mechanism. Finally, partial desorption of the silver ions was successfully conducted in water to demonstrate the reusability of pTSC membranes

Dual sequence definition increases the data storage capacity of sequence-defined macromolecules

Sequence-defined macromolecules offer applications in the field of data storage. Challenges include synthesising precise and pure sequences, reading stored information and increasing data storage capacity. Herein, the synthesis of dual sequence-defined oligomers and their application for data storage is demonstrated. While applying the well-established Passerini three-component reaction, the degree of definition of the prepared monodisperse macromolecules is improved compared to previous reports by utilising nine specifically designed isocyanide monomers to introduce backbone definition. The monomers are combined with various aldehyde components to synthesise dual-sequence defined oligomers. Thus, the side chains and the backbones of these macromolecules can be varied independently, exhibiting increased molecular diversity and hence data storage capacity per repeat unit. In case of a dual sequence-defined pentamer, 33 bits are achieved in a single molecule. The oligomers are obtained in multigram scale and excellent purity. Sequential read-out by tandem ESI-MS/MS verifies the high data storage capacity of the prepared oligomers per repeat unit in comparison to other sequence defined macromolecules

Validation and Generalizability of Preoperative PROMIS Scores to Predict Postoperative Success in Foot and Ankle Patients

Background: A recent publication reported preoperative Patient-Reported Outcomes Measurement Instrumentation System (PROMIS) scores to be highly predictive in identifying patients who would and would not benefit from foot and ankle surgery. Their applicability to other patient populations is unknown. The aim of this study was to assess the validation and generalizability of previously published preoperative PROMIS physical function (PF) and pain interference (PI) threshold t scores as predictors of postoperative clinically meaningful improvement in foot and ankle patients from a geographically unique patient population. Methods: Prospective PROMIS PF and PI scores of consecutive patient visits to a tertiary foot and ankle clinic were obtained between January 2014 and November 2016. Patients undergoing elective foot and ankle surgery were identified and PROMIS values obtained at initial and follow-up visits (average, 7.9 months). Analysis of variance was used to assess differences in PROMIS scores before and after surgery. The distributive method was used to estimate a minimal clinically important difference (MCID). Receiver operating characteristic curve analysis was used to determine thresholds for achieving and failing to achieve MCID. To assess the validity and generalizability of these threshold values, they were compared with previously published threshold values for accuracy using likelihood ratios and pre- and posttest probabilities, and the percentages of patients identified as achieving and failing to achieve MCID were evaluated using χ2 analysis. Results: There were significant improvements in PF (P \u3c .001) and PI (P \u3c .001) after surgery. The area under the curve for PF (0.77) was significant (P \u3c .01), and the thresholds for achieving MCID and not achieving MCID were similar to those in the prior study. A significant proportion of patients (88.9%) identified as not likely to achieve MCID failed to achieve MCID (P = .03). A significant proportion of patients (84.2%) identified as likely to achieve MCID did achieve MCID (P \u3c .01). The area under the curve for PROMIS PI was not significant. Conclusions: PROMIS PF threshold scores from published data were successful in classifying patients from a different patient and geographic population who would improve with surgery. If functional improvement is the goal, these thresholds could be used to help identify patients who will benefit from surgery and, most important, those who will not, adding value to foot and ankle health care. Level of evidence: Level II, Prospective Comparative Stud