True Complex Research Articles

Effect of negative remodeling of the side branch ostium on the efficacy of a two-stent strategy for distal left main bifurcation lesions: an intravascular ultrasound study.

To investigate whether negative remodeling (NR) detected by intravascular ultrasound (IVUS) of the side branch ostium (SBO) would affect in-stent neointimal hyperplasia (NIH) at the one-year follow-up and the clinical outcome of target lesion failure (TLF) at the long-term follow-up for patients with left main bifurcation (LMb) lesions treated with a two-stent strategy. A total of 328 patients with de novo true complex LMb lesions who underwent a 2-stent strategy of percutaneous coronary intervention (PCI) treatment guided by IVUS were enrolled in this study. We divided the study into two phases. Of all the patients, 48 patients who had complete IVUS detection pre- and post-PCI and at the 1-year follow-up were enrolled in phase I analysis, which aimed to analyze the correlation between NR and in-stent NIH at SBO at the 1-year follow-up. If the correlation was confirmed, the cutoff value of the remodeling index (RI) for predicting NIH ≥ 50% was analyzed next. The phase II analysis focused on the incidence of TLF as the primary endpoint at the 1- to 5-year follow-up for all 328 patients by grouping based on the cutoff value of RI. In phase I: according to the results of a binary logistic regression analysis and receiver operating characteristic (ROC) analysis, the RI cutoff value predicting percent NIH ≥ 50% was 0.85 based on the ROC curve analysis, with a sensitivity of 85.7%, a specificity of 88.3%, and an AUC of 0.893 (0.778, 1.000), P = 0.002. In phase II: the TLR rate (35.8% vs. 5.3%, P < 0.0001) was significantly higher in the several NR (sNR, defined as RI ≤ 0.85) group than in the non-sNR group. The NR of LCxO is associated with more in-stent NIH post-PCI for distal LMb lesions with a 2-stent strategy, and NR with RI ≤ 0.85 is linked to percent NIH area ≥ 50% at the 1-year follow-up and more TLF at the 5-year follow-up.

Periapical bacterial disinfection is critical for dental pulp regenerative cell therapy in apical periodontitis in dogs

BackgroundApplication of pulp regenerative cell therapy for mature teeth with periapical lesions is a critical clinical challenge. The bacterial infection in inaccessible location within the root canal system and in the periapical lesions could cause resistance and impediment, leading to limitations in successful therapy. Thus, the aim of this study was to examine the effect of residual bacteria on the outcome of pulp regeneration in mature teeth with apical periodontitis in dogs.MethodsPeriapical lesions were induced in 32 root canals of 4 dogs in two different models in severities, model A and model B. Model A (moderate infection): the canal exposed to the oral cavity for 2 weeks and then closed for 2 weeks. Model B (severe infection): the canal exposed to the oral cavity for 2 months and then closed for 5 months. All root canals were irrigated with 6% sodium hypochlorite, and 3% EDTA and further with 0.015% levofloxacin-containing nanobubbles, which was also used as an intracanal medicament. The aseptic conditions were examined by bacterial anaerobic culture and/or PCR analyses. The root canal treatment was repeated several times, and allogeneic dental pulp stem cells were transplanted into the root canals. The radiographic evaluation of periapical lesions was performed by cone-beam computed tomography before the first treatment, just after cell transplantation, and after 2 months and 6 months in both model A, model B, respectively. The animals were then sacrificed and the jaw blocks were harvested for histological and histobacteriological evaluations of pulp regeneration and periapical tissue healing. Furthermore, the DiI-labelled DPSCs were transplanted into the root canals after complete disinfection (n = 4) or without root canal treatment (n = 4) in the apical periodontitis model (model A) in one dog, and cell localization was compared 72 h after transplantation.ResultsIn 8 out of 12 canals from model A, and 10 out of 15 canals from model B, pulp regeneration with good vascularization, innervation, and a significant reduction in the radiolucent area of the periapical lesions were observed. However, in the other 4 canals and 5 canals from model A and model B, respectively, no pulp tissue was regenerated, and inflammation in the periapical tissue, and external resorption or healed external resorption were detected. The presence of residual bacteria in the periapical tissues and severe inflammation were significantly associated with inhibition of regenerated pulp tissue in these 9 unsuccessful canals (P < 0.05, each) (OR = 0.075, each) analyzed by multiple logistic regression analysis. For cellular kinetics, transplanted cells remained in the disinfected root canals, while they were not detected in the infected root canals, suggesting their migration through the apical foramen under the influence of inflammation.ConclusionsA true pulp-dentin complex was regenerated in the root canal by the pulp regenerative therapy in mature teeth with apical lesions. The successful pulp regeneration was negatively associated both with residual bacteria and inflammation in the periapical tissue.

An Aerial Robotics Investigation into the Stability, Coordination, and Movement of Strategies for Directing Swarm and Formation of Autonomous MAVs and Diverse Groups of Driverless Vehicles (UGVs)

This study will discuss the matter of movement communication and preparation of tight configurations of land &amp; flying robots. Remotely Operated Cars (UGVs) and Unmanned Aerial Vehicles (UAVs), in specific Micro Aerial Vehicles (MAVs), would be used to fix circumstances where a creation of UGVs and UAVs, in specific Micro Aerial Vehicles (MAVs), should counteract their velocity and direction to finish a mission of traffic sequence to a targeted area. The motion planning and stabilisation strategy given here is a useful tool for deploying closely collaborating robot teams including both outdoor and indoor settings. The installation of large groups of Micro Aerial Vehicles (MAVs) in a legitimate (indoor and outdoor) environment without the use of auxiliary positioning applications (such as Vicon or GPS) is indeed a natural development in the area of autonomously flying systems. Stability, control, and trajectory planning techniques for guiding swarm or configurations of unmanned MAVs, as well as diverse groups with Unmanned Ground Vehicles (UGVs) operating alongside MAVs, will be discussed in greater detail. These approaches discussed all are designed for the use of inter squads in true complex scenarios even without necessity for worldwide translation or motion capture systems, as they are predicated on board optical comparative localisation of single MAVs. This multi - objective optimisation being an enabler for the introduction of swarming of tiny autonomous drones beyond the labs with equipment for precise robot positioning. Model Predictive Control (MPC) is being used to address a formations to goal territory issue, and the form drive idea is based on a simulated approach. The Particle swarm optimization approach is utilised for digital leader trajectories planning, as well as control and stabilisation of follows (MAVs and UGVs). The proposed technique could be tested in the future using a range of simulation and practical tests.

Challenges of Transhumanism for Virtue Ethics

Abstract In this paper we consider some of the basic elements of virtue ethics in confrontation with selected ideas of representatives of trans- and post-humanism. Their ideas challenge us to re-justify and defend the uniqueness of man (the person) as a moral subject in his complex relational physical-psycho-spiritual unity. Using this holistic moral-anthropological vision, it is possible to justify the uniqueness of the human act as moral; the nature and significance of virtue as a moral disposition for a truly good and happy life; the nature and significance of happiness as a true complex eudaimonia in the dynamics of human development. In this complex process, technical artefacts and technologies help man to act in a truly human way towards himself and others, if he uses them rightly.

Functionalized Nanoparticles: A Paradigm Shift in Regenerative Endodontic Procedures.

Clinical treatment of inflamed tooth pulp mostly involves the removal of the entire pulp tissue. Because the vitality of the tooth is important for its ability to function, optimal regenerative biomaterials must be developed to maintain the vitality. Despite vast advances in the field of endodontics, the clinical translation of regenerative endodontic procedures and materials remains challenging. Patient-specific, tissue-derived stem cells play a major role in regeneration and revascularization, and these stem cells require an infection-free environment for a successful outcome. However, the high doses of antibiotics currently used to maintain an infection-free environment for tissue regeneration can be toxic for the stem cells. The introduction of nanotechnology in the field of regenerative procedures has overcome these issues and demonstrated promising results. Nanoparticles can be used to deliver antibiotics at very low doses owing to their small size, thereby enhancing antimicrobial activity and reducing the cytotoxic effect. Additionally, nanofibrous scaffolds provide an environment that is favorable for stem-cell migration and proliferation, thereby favoring the regeneration of the pulp-dentin complex. Nanotechnology can be used in the construction of nanofibrous scaffolds incorporated with different bioactive nanoparticles for favorable clinical outcomes. Nonetheless, the role of nanotechnology and the controlled release of various bioactive nanomolecules enhancing stem cell proliferation and regeneration of true pulp-dentin complex remains poorly understood. Given the importance of nanotechnology in tissue regeneration, this review provides an overview of the potential applications of nanotechnology in tooth pulp-dentin regeneration.

Bifurcation lesions : Are new strategies and devices needed?

Interventional treatment of bifurcation lesions, especially true complex bifurcation lesions, continue to be a challenge for interventional cardiologists. Aprimary one stent strategy is always preferred for simple bifurcation lesions, whereas studies in recent years have shown that a two stent strategy may be advantageous for true bifurcations, i.e. those involving at least the distal main branch as well as the side branch. This seems to be even more pronounced when the lesion presents as complex, i.e., the side branch shows high-grade stenosis over longer stretches and the complete lesion fulfils certain criteria, e.g., severe calcification and a bifurcation angle < 45° or > 70°. According to the latest randomized trials and meta-analyses, the double kissing (DK) crush and double kissing mini-crush (DKMC) techniques in particular seem to be advantageous for these lesions; however, in recent years the established techniques have been continuously refined and further developed. The DK culotte technique and the nano-crush technique deserve special attention. Both techniques seem to further improve and simplify the existing underlying strategies; however, further studies to prove the superiority of these techniques over the established ones are still pending. Overall, the implementation of the available randomized study results, the further development of the techniques and also of the materials can continuously improve the outcome of the patients after interventional treatment of bifurcation lesions. This is also confirmed by the latest registry data, which for the first time could show equal event rates in patients after treatment of complex lesions compared to simple lesions in the clinical practice.

Genesis of the gneissic core complexes in the Arabian-Nubian Shield and its tectonic implications: A regional overview

Metamorphic core complexes (MCCs) are a domed structures cored by high grade gneiss overlain by low grade supracrustal rocks. They are characterized by some common features such as extensional fabrics, ultra high-grade metamorphic facies, low angle normal fault (detachment fault), strike-slip shear zones surrounded the core complexes and ductile mylontitic shear zone (thrust zone) that separate the overlying low-grade rocks from the lower high-grade rocks. There is a debate about the presence or absence of metamorphic core complexes in the Arabian-Nubian Shield (ANS) especially in its northern part. The gneissic complexes in the ANS are considered as strike-slip core complexes like the Qazaz and Krish Domes whereas, those in the Egyptian Nubian Shield (ENS) are interpreted as antiformal stacks (e.g. Meatiq and Hafafit) formed during thrusting, or core complexes formed during orogen-parallel crustal extension. Some metamorphic core complexes are domes or contain gneiss domes within them, but not all gneiss domes possess the essential elements of a true metamorphic core complex. The most important points that negate the existence of MCCs in the ANS are absence of ultra-high grade metamorphic facies, absence of real low-angle normal faults, not all the gneisses have a domal structures, adjacent syn-extensional basins have fill that is older than the gneissic complexes, and models of ANS core complex exhumation include strike-slip faults with slip senses recently found to be inconsistent with the models. The gneissic complexes in the ANS differ from the Cordilleran-type or Aegean-type metamorphic core complexes. The origin of gneiss domes in the ANS is controversial, and many of them are presumably produced by mechanisms other than horizontal extension. During the oblique convergence of East and West Gondwana, the gneissic complexes in the ENS evolved from pure shear to simple shear-dominated transpression due to oblique convergence between East and West Gondwana along the Mozambique belt.

High spatial resolution spectral imaging method for space interferometers and its application to formation flying small satellites

Infrared space interferometers can surpass the spatial resolution limitations of single-dish space telescopes. However, stellar interferometers from space have not been realized because of technical difficulties. Two beams coming from individual satellites separated by more than a few tens of meters should precisely interfere such that the optical-path and angular differences between the two beams are reduced at the wavelength level. Herein, we propose a novel beam combiner for space interferometers that records the spectrally-resolved interferometric fringes using the densified pupil spectroscopic technique. As the detector plane is optically conjugated to a plane, on which the two beams interfere, we can directly measure the relative phase difference between the two beams. Additionally, when an object within the field of view is obtained with a modest signal-to-noise ratio, we can extract the true complex amplitude from a continuous broadband fringe (i.e., one exposure measurement), without scanning a delay line and chopping interferometry. We discovered that this spectral imaging method is validated for observing the solar system objects by simulating the reflected light from Europa with a small stellar interferometer. However, because the structure of the object spectrum may cause a systematic error in the measurement, this method may be limited in extracting the true complex amplitude for other astronomical objects. Applying this spectral imaging method to general astrophysics will facilitate further research. The beam combiner and spectral imaging method are applied to a formation-flying stellar interferometer with multiple small satellites in a Sun-synchronous orbit for observation of the solar system objects in visible and near-infrared. We present an overview of SEIRIOS and the optimized optical design for a limited-volume spacecraft.

Microadditive Manufacturing Technologies of 3D Microelectromechanical Systems

Conventional microfabrication processes have been well established, but their capabilities are generally limited simple and 2D extruded geometries. Additive manufacturing allows the ability to manufacture true 3D complex geometries, rapid design for manufacturing, mass customization, materials savings, and high precision, which have triggered the increased interest in manufacturing microelectromechanical systems (MEMS). Herein, MEMS manufacturing's recent advancements, including both conventional and additive manufacturing technologies, their working principles, and practical capabilities are consolidated. The use of additive manufacturing in several MEMS areas such as in microelectronics, circuitry, microfluidics, lab on a chip, packaging, and structural MEMS is also discussed in detail. Furthermore, the potentials and limitations of additive manufacturing are investigated with regard to the MEMS requirements. Finally, the technology outlook and improvements are discussed. This study shows that additive manufacturing offers a promising future for the fabrication of MEMS, especially using high‐resolution techniques such as microstereolithography, materials jetting, and materials extrusion. In contrast, current challenges such as materials requirements, equipment innovation, fabricating of in vivo devices for biomedical applications, inherited defects and poor surface finish, adhesion to substrates, and productivity are areas that require further study to increase the uptake by the MEMS community.

Machine Learning for Subtyping Concussion Using a Clustering Approach

Background: Concussion subtypes are typically organized into commonly affected symptom areas or a combination of affected systems, an approach that may be flawed by bias in conceptualization or the inherent limitations of interdisciplinary expertise.Objective: The purpose of this study was to determine whether a bottom-up, unsupervised, machine learning approach, could more accurately support concussion subtyping.Methods: Initial patient intake data as well as objective outcome measures including, the Patient-Reported Outcomes Measurement Information System (PROMIS), Dizziness Handicap Inventory (DHI), Pain Catastrophizing Scale (PCS), and Immediate Post-Concussion Assessment and Cognitive Testing Tool (ImPACT) were retrospectively extracted from the Advance Concussion Clinic's database. A correlation matrix and principal component analysis (PCA) were used to reduce the dimensionality of the dataset. Sklearn's agglomerative clustering algorithm was then applied, and the optimal number of clusters within the patient database were generated. Between-group comparisons among the formed clusters were performed using a Mann-Whitney U test.Results: Two hundred seventy-five patients within the clinics database were analyzed. Five distinct clusters emerged from the data when maximizing the Silhouette score (0.36) and minimizing the Davies-Bouldin score (0.83). Concussion subtypes derived demonstrated clinically distinct profiles, with statistically significant differences (p < 0.05) between all five clusters.Conclusion: This machine learning approach enabled the identification and characterization of five distinct concussion subtypes, which were best understood according to levels of complexity, ranging from Extremely Complex to Minimally Complex. Understanding concussion in terms of Complexity with the utilization of artificial intelligence, could provide a more accurate concussion classification or subtype approach; one that better reflects the true heterogeneity and complex system disruptions associated with mild traumatic brain injury.

Test structure in some pioneer multichambered Paleozoic foraminifera

Foraminiferal wall microstructures, consistent with the molecular-based high-rank classification, are critical to understanding foraminiferal evolution and advanced taxonomic relationships. Although test structures are well documented for recent, Cenozoic, and some Mesozoic foraminifera, the diagnostic characteristics of Paleozoic taxa are largely unexplored. The majority of calcareous Paleozoic foraminifera have been assigned to the Fusulinata based on questionable homogeneously "microgranular" test wall microstructures, which have never been sufficiently documented for most taxa. We investigated the test structures of exceptionally well-preserved Devonian (Eifelian) Semitextularia thomasi, representing the first calcareous true multichambered (serial) foraminifera, and compared this species with a large fusiform Permian representative of "true" fusulinids (Neoschwagerinidae). The tests of Semitextularia thomasi display lamellar structures that are not observed in any other fossil or recent foraminiferal group. The Paleozoic foraminifera, traditionally referred to one taxon (the class Fusulinata), possess at least three contrasting test wall microstructures, representing separate high-rank taxonomic groups. Fusulinata is most likely a highly polyphyletic group that is in need of taxonomic revision. The term Fusulinata, defined as including all Paleozoic calcareous forms except Miliolida and Lagenata, is not phylogenetically meaningful and should no longer be used or should be restricted to true complex fusulinids with microgranular test structures, which appeared in the Carboniferous.

Docetaxel/dimethyl-β-cyclodextrin inclusion complexes: preparation, in vitro evaluation and physicochemical characterization

Despite the development in novel drug delivery techniques and synthesis of multifunctional excipients, oral delivery of hydrophobic drug like docetaxel (DTX) is still challenging. The present work investigates the inclusion complexation of DTX, and dimethyl-β-cyclodextrin (DM-β-CD) to improve the solubility, dissolution and permeability of the drug. Amongst the native and modified β-cyclodextrins, DM-β-CD showed the highest solubility of DTX. Solid binary inclusion complex (IC) of DTX with DM-β-CD was prepared by solvent evaporation technique and thoroughly characterized for solubility, dissolution, permeability, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance (1H NMR). The aqueous solubility and in vitro dissolution rate of DTX/DM-β-CD IC were markedly increased by 76.04- and 3.55-fold compared to free DTX powder. The permeability of DTX/DM-β-CD IC showed similar absorptive permeability but decreased efflux from the absorbed DTX, compared to pure DTX. Further, physicochemical studies of IC revealed the change of crystalline state DTX to its amorphous form. Moreover, FT-IR and 1H NMR results indicate the formation of true inclusion complex between DTX and DM-β-CD at 1:1 molar ratio. Collectively, solid inclusion complexes prepared by spray drying method can be an effective strategy to enhance the biopharmaceutical performance of a highly hydrophobic drug DTX.

Imagerie du rhumatisme psoriasique

Imaging is one of the keys to diagnosing psoriatic arthritis. The different modalities will make it possible to highlight the key elements of the disease and its specificity in relation to other spondyloarthritis. This distinction concerns both axial and peripheral lesions, particularly dactylitis. First of all, the standard radiograph which visualizes periostitis present on the epiphyses or phalanges, a diagnostic element in the CASPAR classification criteria, but also juxta-articular erosions which make psoriatic arthritis one of the two chronic inflammatory erosive joint diseases with rheumatoid arthritis. The other anomalies such as acro-osteolysis, joint ankylosis, which are close to osteoarticular destruction on the same anatomical structure, hand or foot, are perfectly identified on the standard images. Ultrasound and MRI have made it possible to describe enthesitis and its capsulo-ligamentary and bony relationships, describing a true anatomical complex. These extra-articular inflammatory attacks are occurring often early in the disease course. Bone damage in the form of bone oedema is the prerogative of MRI to the sacroiliac joints and the spine, in the entheses areas, as in axial ankylosing spondylitis. Spinal damage includes C1-C2 damage like that of rheumatoid arthritis, multi-stage syndesmophytes, which are often larger and coarser, para-syndesmophytes, and radiological or MRI sacroiliitis, which is often less extensive and unilateral. The progression of peripheral joint lesions, erosions and joint space narrowing, is the hallmark of symmetrical or asymmetrical psoriatic polyarthritis.

The measure on the original space from a product measure

The measurability problems can arise in Gaussian and empirical processes underlying nonparametric and semiparametric problems critical in modern statistics and machine learning. The usual applications are high-dimensional data in random fields. To ensure the validity of recovering a true original complex object from its observed images treated in a product space that appears in existing high-dimensional data applications widely arising in physical, biological, and social sciences and engineering, we begin with the results on the σ-algebra of the original space Ω induced by a given map fT mapping from Ω to a product measure space (ΩT,FT,μT). We study the certain measurability issues on Ω with the induced measure μ from the image measure μT of the product space by establishing the outer measure ν⁎ restricted to the trace σ-algebra. We further investigate the measure μ on Ω under the map fT to obtain the conditions for the identifiability equality μT=μ∘fT−1 to hold so that a practical and rigorous foundation is provided for the nontrivial applications to work meaningfully.

Instability of Short Arm of Acrocentric Chromosomes: Lesson from Non-Acrocentric Satellited Chromosomes. Report of 24 Unrelated Cases

Satellited non-acrocentric autosomal chromosomes (ps–qs-chromosomes) are the result of an interchange between sub- or telomeric regions of autosomes and the p arm of acrocentrics. The sequence homology at the rearrangement breakpoints appears to be, among others, the most frequent mechanism generating these variant chromosomes. The unbalanced carriers of this type of translocation may or may not display phenotypic abnormalities. With the aim to understand the causative mechanism, we revised all the ps–qs-chromosomes identified in five medical genetics laboratories, which used the same procedures for karyotype analysis, reporting 24 unrelated cases involving eight chromosomes. In conclusion, we observed three different scenarios: true translocation, benign variant and complex rearrangement. The detection of translocation partners is essential to evaluate possible euchromatic unbalances and to infer their effect on phenotype. Moreover, we emphasize the importance to perform both, molecular and conventional cytogenetics methods, to better understand the behavior of our genome.

Possibility and application of all-weather lidar-radio sensing complexes

The article discusses the main problems of the development and applying of all-weather meteorological complexes of remote optical and radar atmospheric sensing. Discussed different areas of application depending on type of airports. The concept of a new mobile three-band true all-weather meteorological single platform complex for operational measurements in airports is proposed. Shown the results of multi-bands systems measurements in PPI mode and vertical profiler performed under various conditions.

The spectrum of kidney biopsy findings in HIV-infected patients in the modern era

HIV-associated kidney disease is evolving rapidly. Few North American studies have addressed modern trends and none has applied the 2018 Kidney Disease Improving Global Outcomes (KDIGO) pathologic classification. Therefore we performed a retrospective clinical-pathologic analysis of all HIV-positive patients with kidney biopsy interpreted at Columbia University from 2010-2018 using the KDIGO classification. The biopsy cohort of 437 HIV-positive patients had median age 53 years, including 66% males, 80% on anti-retroviral therapy, 57% with hypertension, 31% with diabetes, 27% with hepatitis C and 6% with hepatitis B co-infections. Race, known in 308 patients, included 58% black, 25% white and 17% Hispanic. Pathologic diagnoses were surprisingly diverse. Immune complex glomerulonephritis (ICGN) and diabetic nephropathy each outnumbered HIV-associated nephropathy, followed by tenofovir nephrotoxicity, FSGS- not otherwise specified (NOS) and global sclerosis (NOS). HIV-associated nephropathy was the most common disease in patients not on anti-retroviral therapy, and 94% were black. The association of FSGS (NOS) with black race (68%) and anti-retroviral therapy use (77%) suggests some cases may represent attenuated HIV-associated nephropathy. The most common ICGNs were IgA nephropathy and membranous glomerulopathy, both associating with anti-retroviral therapy (over 90%), followed by hepatitis C-associated proliferative ICGN. Among the 16 cases of uncharacterized ICGN lacking identifiable etiology, 69% were not on anti-retroviral therapy, possibly representing true HIV-associated immune complex kidney disease. Dual diseases occurred in 17% of patients, underscoring lesion complexity. Thus, anti-retroviral therapy has shifted the landscape of HIV-associated kidney disease toward diverse ICGN, diabetic nephropathy, and non-collapsing glomerulosclerosis, but has not eradicated HIV-associated nephropathy.

A Self-Assembled Iron(II) Metallacage as a Trap for Per- and Polyfluoroalkyl Substances in Water.

An anionic iron(II) tetrahedral molecular cage (FeMOP) was studied for its ability to interact with various per- and polyfluoroalkyl substances (PFASs) in aqueous media. Liquid chromatography tandem mass spectrometry revealed that longer-chain-length (more than six carbons) perfluorocarboxylic, -sulfonic, and fluorotelomers were removed from solution. In contrast, the steric bulk of N-ethyl substituted fluorosulfonamido acetic acid PFASs hindered association with the cage. Solution binding studies in D2O using 19F nuclear magnetic resonance (NMR) titrations and a Job plot show a 1:1 binding stoichiometry for perfluorohexanoic acid (PFHxA) and perfluoroheptanoic acid (PFHpA) with an association constant (Ka) of <103 and thus a favorable free energy of association (ΔG°). Perfluorononanoic acid (PFNA), on the other hand, forms an insoluble host-guest complex with FeMOP with a 1:1 host-guest ratio. Variable temperature (VT) NMR was used to determine the thermodynamic parameters of binding for a 1:1 FeMOP/PFHpA complex in water using a Curie-like model for fast-exchange processes. The extracted parameters suggest a low binding interaction (Ka < 103) driven by an increase in entropy from cage desolvation upon guest binding. The solid-state host-guest complexes formed from solution complexation of PFHxA, PFHpA, and PFNA into the cage were characterized by infrared spectroscopy (FT-IR) and powder X-ray diffraction (PXRD) methods. FT-IR studies suggest an interaction between the fluorocarbon groups of PFASs to the phenylsulfonate functional groups of the ligand. A docking model predicted by computation also indicates this interaction may occur, with the PFASs adsorbing onto the surface of the cage rather than forming a true host-guest complex within the internal cavity. PXRD studies reveal a crystal packing of the complex that is very similar to that of the water-treated FeMOP, with the exception of 1:2 FeMOP/PFNA and 1:1 and 2:1 FeMOP/PFHpA.

Computational study of the sensitivity of laser light scattering particle sizing to refractive index and irregularity

Measuring the size distribution of dust particles is of interest in many scientific and technological contexts. One of the most widely used techniques is laser light scattering (LLS), which provides the distribution of surface-equivalent spheres that fits the observed angular dependence of light scattered by a sample. We have revisited the problem of the uncertain lower size limit of this method by simulating laboratory measurements of the light intensity scattered by polydisperse spheres and irregular particles (agglomerated debris and pocked spheres), from which the original distributions are retrieved by regularized inversion with Mie and Fraunhofer phase functions. For the usual combination of blue (λ = 466 nm) and red (λ = 633 nm) light sources, size distributions of spheres with radii r > 0.1 μm are retrieved with Mie if the true complex refractive index (m = n – ik) is used. The retrieval for 0.1 μm < r < 3 μm is sensitive to errors in the assumed m, which results primarily from the dependence of the scattering efficiency Qsca on m. Irregular particle shape has also an impact on the Qsca vs. r curves, whose maxima are shifted towards larger r and are smoother compared to spherical particles. For a violet-blue wavelength (λ = 442 nm), good retrievals are obtained for irregular particles with r > 1 μm even if m is not very well known or the Fraunhofer model is used. Spurious slumps and enhancements appear for r < 1 μm, although if n is known, the actual lower limit decreases for increasing n. This implies that LLS size distributions of submicron irregular particles may not be accurate. Establishing the lower size limit requires inspection of the dependence on m and analysis of the irregularity of samples.

Theoretical Search for the Highest Valence States of the Coinage Metals: Roentgenium Heptafluoride May Exist.

We present here a relativistic density functional theory investigation of the penta- and heptavalent states of gold and roentgenium, employing the ZORA (zeroth order regular approximation to the Dirac equation) Hamiltonian, including spin-orbit coupling at the two-component level, and large all-electron relativistic Slater-type quadruple-ζ quadruple polarization (ZORA-STO-QZ4P) basis sets. Unsurprisingly, our calculations confirm the stability of the experimentally known complexes AuF6- and Au2F10 with respect to decomposition to trivalent Au products and F2. The calculations also predict that RgF6- and Rg2F10 should be even more stable with respect to an analogous decomposition pathway. Like an earlier DFT study ( Inorg. Chem. 2007, 46 (13), 5338-5342), our calculations rule out the true heptavalent Au complex AuF7 as a stable species, preferring instead a Cs AuF5···F2 formulation. Remarkably, our calculations confirm a D5 h pentagonal-bipyramidal structure of RgF7 as the global minimum, at an energy of approximately half an electron volt below the RgF5···F2 form.