Search

We aimed to assess DPNCheck's reliability for repeated sural nerve conduction (NC) parameters. This post hoc analysis used data from the randomized controlled ACUDPN trial assessing NC of the N. Suralis every eight weeks over a 6-month period in 62 patients receiving acupuncture against diabetic peripheral neuropathy (DPN) symptoms. The reliability of DPNCheck for nerve conduction velocity and amplitude was assessed using intraclass correlation coefficients (ICC) and was calculated using data from single time points and repeated measures design. The results of the NC measurements were correlated with the Total Neuropathy Score clinical (TNSc). Overall, for both nerve velocity and amplitude, the reliability at each measurement time point can be described as moderate to good and the reliability using repeated measures design can be described as moderate. Nerve velocity and amplitude showed weak correlation with TNSc. DPNCheck's reliability results question its suitability for monitoring DPN's progression. Given the limitation of our analysis, a long-term, pre-specified, fully crossed study should be carried out among patients with DPN to fully determine the suitability of the device for DPN progression monitoring. This was the first analysis assessing the reliability of the DPNCheck for DPN progression monitoring using data from multiple collection time points. [ABSTRACT FROM AUTHOR]

Background: A program of gasless laparoscopy (GL) has been implemented in rural North-East India. To facilitate safe adoption, participating rural surgeons underwent rigorous training prior to independent clinical practice. An online registry was established to capture clinical data on safety and efficacy and to evaluate initial learning curves for gasless laparoscopy. Methods: Surgeons who had completed the GL training program participated in the online RedCap Registry. Patients included in the registry provided informed consent for the use of their data. Data on operative times, conversion rates, perioperative complications, length of stay, and hospital costs were collected. Fixed reference cumulative sum (CUSUM) model was used to evaluate the learning curve based on operative times and conversion rates published in the literature. Results: Four surgeons from three rural hospitals in North-East India participated in the registry. The data were collected over 12 months, from September 2019 to August 2020. One hundred and twenty-three participants underwent GL procedures, including 109 females (88.6%) and 14 males. GL procedures included cholecystectomy, appendicectomy, tubal ligation, ovarian cystectomy, diagnostic laparoscopy, and adhesiolysis. The mean operative time was 75.3 (42.05) minutes for all the surgeries. Conversion from GL to open surgery occurred in 11.4% of participants, with 8.9% converted to conventional laparoscopy. The main reasons for conversion were the inability to secure an operative view, lack of operating space, and adhesions. The mean length of stay was 3 (2.1) days. The complication rate was 5.7%, with one postoperative death. The CUSUM analysis for GL cholecystectomy showed a longer learning curve for operative time and few conversions. The learning curve for GL tubal ligation was relatively shorter. Conclusion: Gasless laparoscopy can be safely implemented in the rural settings of Northeast India with appropriate training programs. Careful case selection is essential during the early stages of the surgical learning curve. [ABSTRACT FROM AUTHOR]

The structures and energetics of the binuclear cyclobutadiene vanadium carbonyls (C4H4)2V2(CO)n (n = 8, 7, 6, 5, 4, 3, 2) have been investigated by density functional theory (DFT). The lowest energy (C4H4)2V2(CO)8 structure consists of two C4H4V(CO)4 units linked by a V-V single bond of length 3.4 Å. The two lowest energy (C4H4)2V2(CO)7 structures also have formal V-V single bonds. The "extra" two electrons to give each vanadium atom in these heptacarbonyls the favored 18-electron configuration can come from either an agostic C-H-V interaction activating a hydrogen atom from one of the cyclobutadiene rings or from a four-electron donor bridging η2-µ-CO group with a short V–O distance. The lowest energy (C4H4)2V2(CO)6 structure has a formal V≡V triple bond of length 2.52 Å similar to the V≡V triple bond of length 2.46 Å found in the experimentally known cyclopentadienyl derivative (η5-C5H5)2V2(CO)5. The lowest energy structures for the more highly unsaturated (C4H4)2V2(CO)n (n = 5, 4, 3, 2) have at least two four-electron donor bridging η2-µ-CO groups and a vanadium-vanadium bond order sufficient to give each vanadium atom at least a 16-electron configuration. The structures and energetics of the binuclear cyclobutadiene vanadium carbonyls (C4H4)2V2(CO)n (n = 8, 7, 6, 5, 4, 3, 2) have been investigated by density functional theory. The two lowest energy (C4H4)2V2(CO)7 structures include one with an agostic C-H-V interaction activating a hydrogen atom from one of the cyclobutadiene rings and another with a four-electron donor bridging η2-µ-CO group with a short V–O bonding distance. [ABSTRACT FROM AUTHOR]

The rivers of the Hampshire Basin, southern England contain a genetically unique group of Atlantic salmon that have suffered dramatic declines in numbers over the last 40 years. Knowledge of levels and patterns of genetic diversity is essential for effective management of these vulnerable populations. Using restriction site-associated DNA sequencing (RADseq) data, we describe the development and characterisation of a panel of 94 single nucleotide polymorphism (SNP) loci for salmon from this region and investigate their applicability and variability in both target (i.e. southern English) and non-target populations. The SNP loci will be useful for population genetic and assignment studies on Atlantic salmon within the UK and beyond. [ABSTRACT FROM AUTHOR]

Background: In high-income countries, laparoscopic surgery is the preferred approach for many abdominal conditions. Conventional laparoscopy is a complex intervention that is challenging to adopt and implement in low resource settings. This systematic review and meta-analysis evaluate the clinical effectiveness of gasless laparoscopy compared to conventional laparoscopy with CO2 pneumoperitoneum and open surgery for general surgery and gynaecological procedures. Methods: A search of the MEDLINE, EMBASE, Global Health, AJOL databases and Cochrane Library was performed from inception to January 2021. All randomised (RCTs) and comparative cohort (non-RCTs) studies comparing gasless laparoscopy with open surgery or conventional laparoscopy were included. The primary outcomes were mortality, conversion rates and intraoperative complications. Secondary outcomes: operative times and length of stay. The inverse variance random-effects model was used to synthesise data. Results: 63 studies were included: 41 RCTs and 22 non-RCTs (3,620 patients). No procedure-related deaths were reported in the studies. For gasless vs conventional laparoscopy there was no difference in intraoperative complications for general RR 1.04 [CI 0.45–2.40] or gynaecological surgery RR 0.66 [0.14–3.13]. In the gasless laparoscopy group, the conversion rates for gynaecological surgery were high RR 11.72 [CI 2.26–60.87] when compared to conventional laparoscopy. For gasless vs open surgery, the operative times were longer for gasless surgery in general surgery RCT group MD (mean difference) 10 [CI 0.64, 19.36], but significantly shorter in the gynaecology RCT group MD − 18.74 [CI − 29.23, − 8.26]. For gasless laparoscopy vs open surgery non-RCT, the length of stay was shorter for gasless laparoscopy in general surgery MD − 3.94 [CI − 5.93, − 1.95] and gynaecology MD − 1.75 [CI − 2.64, − 0.86]. Overall GRADE assessment for RCTs and Non-RCTs was very low. Conclusion: Gasless laparoscopy has advantages for selective general and gynaecological procedures and may have a vital role to play in low resource settings. [ABSTRACT FROM AUTHOR]

The structures and energetics of the binuclear phospholyl vanadium carbonyls (C4H4P)2V2(CO)n (n = 7, 6, 5, 4, 3, 2, 1) have been investigated using density functional theory. The lowest energy heptacarbonyl (C4H4P)2V2(CO)7 structures resemble those of the dimanganese pentacarbonyl (C4H4P)2Mn2(CO)5 with one seven-electron donor bridging η5,η1-C4H4P ring and no direct vanadium–vanadium bond. Similarly, the lowest energy hexacarbonyl (C4H4P)2V2(CO)6 structure resembles that of the dimanganese tetracarbonyl (C4H4P)2Mn2(CO)4 with two seven-electron donor bridging η5,η1-C4H4P rings and no direct vanadium–vanadium bond. The lowest energy pentacarbonyl (C4H4P)2V2(CO)5 structure has terminal η5-C4H4P phospholyl rings and a formal V≡V triple bond of length ~ 2.45 Å similar to the experimentally known and structurally characterized cyclopentadienyl analogue (η5-C5H5)2V2(CO)5. Various combinations of V=V double bonds or V≡V triple bonds, four-electron donor bridging carbonyl groups and seven-electron donor bridging η5,η1-C4H4P rings are found in the more highly unsaturated derivatives (C4H4P)2V2(CO)n (n = 4, 3, 2) to give 17- and 18-electron vanadium configurations for triplet- and singlet-state structures, respectively. Formal V≣V quadruple bonds are found only in the highly unsaturated lowest energy singlet (C4H4P)2V2(CO)n (n = 2, 1) structures, which, however, lie at somewhat higher energies than isomeric triplet structures. [ABSTRACT FROM AUTHOR]

Deviation from the most spherical closo deltahedral geometry can occur in metallaboranes and metallacarbaboranes because of the energetic preference of transition metal moieties for higher degree vertices than boron and/or carbon. The isocloso structures with a metal at a degree 6 vertex and two fewer skeletal electrons than the corresponding closo structures represent a minor deviation from such sphericity and are particularly favorable for 10-vertex systems. Spherical supraicosahedral deltahedra with 14 to 16 vertices, also known as Frank-Kasper deltahedra, necessarily have several degree 6 vertices and accordingly can have isocloso skeletal electron counts. More substantial deviations from sphericality occurs in the oblate ellipsoidal structures of the dirhenaboranes Cp2Re2Bn–2Hn–2 (8 ≤ n ≤ 12) with the rhenium atoms antipodally situated at degree 6 or 7 vertices of relatively low local curvature and the boron atoms situation at degree 4 and 5 vertices of relatively high local curvature. Species isoelectronic with the Cp2Re2Bn–2Hn–2 derivatives can also have closo or isocloso structures with surface metal–metal multiple bonds. The experimentally known icosahedral Cp2Cr2C2B8H10 was believed to be such a species with a surface Cr≣Cr quadruple bond. However, theoretical prediction of chromium–chromium distances suggest that a Cp2Cr2(μ-H)2C2B8H10 structure with a surface Cr≡Cr triple bond bridged by two “extra” hydrogen atoms is more likely. The tri- and tetrametallaboranes Cp*3W3(H)B8H8 and Cp*4Mo4B7H7 of the groups 6 metals molybdenum and tungsten provide examples of non-spherical 11-vertex deltahedra with metal atoms located at degree 6 and 7 vertices and boron atoms located at degree 4 and 5 vertices. The topology of the lowest energy Cp*4Mo4Bn–4Hn–4 (n = 10, 11, 12) deltahedra can be generated by capping n – 8 vertices of a central Mo4B4 cube and then drawing diagonals across the remaining uncapped faces. [ABSTRACT FROM AUTHOR]

Data sources: Studies were selected, using appropriate key words, from the following databases: Cochrane Central Register of Controlled Trials; Medline (via Pubmed); Scopus/Elsevier; and Embase. A manual search was also conducted of five periodontology and oral and maxillofacial surgery journals. It was not clarified what proportion of studies included were derived from which source. Study selection: Inclusion criteria included prospective studies and randomised controlled trials published in English, with a minimum 6-month follow-up reporting on parameters of periodontal healing distal to the mandibular second molar following removal of M3M in human subjects. These parameters included pocket probing depth (PPD) reduction and final depth (FD), clinical attachment loss (CAL) reduction and FD, alveolar bone defect (ABD) change and FD. Given prognostic indictors and interventions were investigated, the studies were screened using PICO and PECO (Population, Intervention, Exposure, Comparison, Outcome). Cohen's kappa statistic measured the level of agreement between 2 selecting authors (0.96 stage 1 screening, 1.00 stage 2 screening). Disagreements were resolved with a tie-breaker 3rd author. Ultimately, from 918 studies, 17 met the inclusion criteria and 14 were included in the meta-analysis. Studies were excluded on the basis of same patient pools, non-representative outcomes of interest, insufficient follow-up period, and unclear results. Data extraction and synthesis: The 17 studies meeting the inclusion criteria underwent validity assessment and data extraction, including risk of bias analysis. Meta-analysis was performed to calculate mean difference and standard error for each outcome measure. If these were unavailable, a correlation coefficient was calculated. Meta-regression was used on different subgroups to determine factors affecting periodontal healing. For all analyses, statistical significance was determined as p < 0.05. Statistical variability in outcomes beyond the expected was estimated using I2 analyses, with a value >50% indicating significant heterogeneity. Results: The periodontal parameters investigated yielded the following results after meta-analysis: overall PPD reduction of 1.06 mm at 6 months and 1.67 mm at 12 months; final PPD of 3.81 mm at 6 months; CAL change of 0.69 mm at 6 months; final CAL of 4.28 mm at 6 months and 4.37 mm at 12 months; ABD reduction of 2.62 mm at 6 months; ABD of 3.2 mm at 6 months. The authors found no statistically significant effect on periodontal healing from the following confounding factors: age; M3M angulation (specifically, mesioangular impaction); optimisation of periodontal health prior to surgery; scaling and root planing of the distal second molar at the time of surgery; post-operative antibiotics or chlorhexidine prophylaxis. There were statistically significant correlations between baseline PPD and final PPD. There was improved PPD reduction at 6 months with a three-sided flap compared to others, and regenerative materials and bone grafts improved all periodontal parameters. Conclusions: Although M3M removal results in modest improvement in periodontal health distally of the second mandibular molar, periodontal defects remain onwards of 6 months. There is limited evidence suggesting a three-sided flap is more beneficial than an envelope flap in PPD reduction at 6 months. Regenerative materials and bone grafts result in significant improvements across all periodontal health parameters. The most important predictive factor in final PPD of the distal second mandibular molar is baseline PPD. [ABSTRACT FROM AUTHOR]

Accurate determination of sex ratios is an important metric for the conservation and management of wild Atlantic salmon populations. Previously published primers for a male-specific gene were shown to be unreliable at determining sex due to the presence of deletions in the forward primer-binding site. A new forward primer, used in conjunction with the existing reverse primer, greatly improved reliability of the genetic test, correctly assigning gender in samples of known sex. Using DNA extracted from both contemporary and archive tissues, comparison between the two primer sets screened on collections of unknown sex ratio showed significant discrepancies in the number of males identified. The new primer will help improve the management and conservation of Atlantic salmon by providing accurate sex ratios for the setting of Conservation Limits. [ABSTRACT FROM AUTHOR]

Criterion data for total energy expenditure (TEE) in elite rugby are lacking, which prediction equations may not reflect accurately. This study quantified TEE of 27 elite male rugby league (RL) and rugby union (RU) players (U16, U20, U24 age groups) during a 14-day in-season period using doubly labelled water (DLW). Measured TEE was also compared to estimated, using prediction equations. Resting metabolic rate (RMR) was measured using indirect calorimetry, and physical activity level (PAL) estimated (TEE:RMR). Differences in measured TEE were unclear by code and age (RL 4369 ± 979; RU 4365 ± 1122; U16, 4010 ± 744; U20, 4414 ± 688; U24, 4761 ± 1523 Kcal day- 1). Differences in PAL (overall mean 2.0 ± 0.4) were unclear. Very likely differences were observed in RMR by code (RL 2366 ± 296; RU 2123 ± 269 Kcal day- 1). Differences in relative RMR between U20 and U24 were very likely (U16, 27 ± 4; U20, 23 ± 3; U24, 26 ± 5 Kcal kg- 1 day- 1). Differences were observed between measured and estimated TEE, using Schofield, Cunningham and Harris-Benedict equations for U16 (187 ± 614, unclear; - 489 ± 564, likely and - 90 ± 579, unclear Kcal day- 1), U20 (- 449 ± 698, likely; - 785 ± 650, very likely and - 452 ± 684, likely Kcal day- 1) and U24 players (- 428 ± 1292; - 605 ± 1493 and - 461 ± 1314 Kcal day- 1, all unclear). Rugby players have high TEE, which should be acknowledged. Large inter-player variability in TEE was observed demonstrating heterogeneity within groups, thus published equations may not appropriately estimate TEE. [ABSTRACT FROM AUTHOR]

Background Oral potentially malignant disorders (OPMDs) include erythroplakia, erosive lichen planus, non-homogenous leukoplakia and many others. These lesions may revert to healthy tissues, remain unchanged, or undergo malignant change to oral squamous cell carcinoma (OSCC). Early detection allows early management, which subsequently improves survival rates for OSCC. Current diagnostic practice involves a tissue biopsy with histology. This can be uncomfortable for patients and delays diagnosis. Other, less invasive diagnostic tests are available which can provide immediate results. Objectives Primary objective: to evaluate the diagnostic accuracy of index tests in detecting OSCC and OPMDs. Secondary objective: to determine the relative accuracy of alternative diagnostic tests. Search methods Four online databases including Medline (OVID), Embase (OVID), the US National Institute of Health Ongoing Trials Register (clinicaltrials.gov) and the World Health Organisation International Clinical Trials Registry Platform were searched for ongoing trials to 20 October 2020. Citation searches were conducted, with no language restrictions, and reference lists were reviewed for any additional references. Selection criteria Studies reporting the diagnostic test accuracy of the following index tests were included if used in conjunction with oral examination in determining OPMDs or OSCC: oral spectroscopy, light-based detection, vital staining, saliva and/or blood analysis and oral cytology. Data collection and analysis Titles and abstracts were screened by two designated review authors to determine relevance. A minimum of two authors, both independently and together, assessed the eligibility of the papers and undertook the quality assessment and data extraction. The methodological quality was determined using the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2). Results of each index test in various studies were amalgamated using meta-analysis following the bivariate approach to determine sensitivity and specificity. Results Seventy-nine datasets were included, spanning from 1980 to 2020. A total of 7,942 lesions were examined. These studies assessed diagnostic sensitivity and specificity of tissue biopsy and histology in comparison to oral cytology (24 datasets), oral spectroscopy/light-based detection (24 datasets) and vital staining (22 datasets). Nine datasets evaluated two combined index tests. No eligible diagnostic accuracy studies assessing salivary or blood sample analysis were identified. Two studies were deemed low risk of bias in all categories (patient selection, index tests, reference standards and flow and timing) with 33 studies being low concern for applicability across three sectors. Patient selection, demographics, the index test and reference standard used were appropriate to a secondary care setting. Meta-analysis of eligible index tests showed the following results. Cytological sensitivity was 0.90 (CI 0.82-0.94) and specificity 0.94 (CI 0.88-0.97) from 24 datasets. For oral spectroscopy, sensitivity was 0.87 (CI 0.78-0.93) and specificity 0.50 (CI 0.32-0.68) from 24 datasets. For vital staining, sensitivity was 0.86 (CI 0.79-0.90) and specificity 0.68 (CI 0.58-0.77) from 22 datasets. For combined tests, sensitivity was 0.78 (CI 0.45-0.94) and specificity 0.71 (CI 0.53-0.84) from nine datasets. Conclusion None of the adjunctive tests can presently be recommended in lieu of tissue biopsy and histological assessment. Of the modalities, oral cytology showed the greatest potential based on the high summary estimate values for sensitivity and specificity. Further research is needed into the utility of these alternative diagnostic tests. [ABSTRACT FROM AUTHOR]

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Cloke and coworkers have recently (2006–2012) shown that reaction of carbon monoxide with organouranium compounds results in reductive coupling to yield the oligomeric anions CnOn2− (n = 2, 3, 4). In order to explore the possibilities of similar reductive coupling of carbon monoxide in organolanthanide systems, the structures and thermochemistry of the cyclopentadienyllanthanide carbonyls Cp2Ln2(CO)n (n = 2, 3, 4, 5) have been investigated using lanthanum and lutetium, which are diamagnetic in the favored +3 oxidation state. All of these Cp2Ln2(CO)n structures have long Ln···Ln distances exceeding 4.2 Å for La and 3.6 Å for Lu, indicating the lack of direct metal–metal bonding and suggesting the normally favored +3 oxidation state for these lanthanides. In the dicarbonyls Cp2Ln2(CO)2, the two CO groups couple to form a bridging µ-C2O24− ligand, which can be derived by removal of four protons from glycolaldehyde (hydroxyacetaldehyde). Similarly, in the tricarbonyls, the three CO groups couple to form a bridging µ-C3O34− ligand, which can be derived by removal of four protons from hydroxypyruvaldehyde. However, the lowest energy structures for the tetracarbonyls Cp2Ln2(CO)4 (by more than 13 kcal/mol) have four separate η2-µ-CO ligands bonded to the central Ln2 unit through both their carbon and oxygen atoms. Thermochemistry of the Cp2Ln2(CO)n systems suggests viability of Cp2Ln2(CO)2 and Cp2Ln2(CO)4. However, Cp2Ln2(CO)3 is predicted to be disfavored relative to disproportionation into Cp2Ln2(CO)2 + Cp2Ln2(CO)4. [ABSTRACT FROM AUTHOR]

The postglacial adaptive radiation of the threespine stickleback fish (Gasterosteus aculeatus) has been widely used to investigate the roles of both adaptive evolution and plasticity in behavioral and morphological divergence from the ancestral condition represented by present-day oceanic stickleback. These phenotypes tend to exhibit high levels of ecotypic differentiation. Population divergence in life history has also been well studied, but in contrast to behavior and morphology, the extent and importance of plasticity has been much less well studied. In this review, we summarize what is known about life-history plasticity in female threespine stickleback, considering four traits intimately associated with reproductive output: age/size at maturation, level of reproductive effort, egg size and clutch size. We envision life-history plasticity in an iterative, ontogenetic framework, in which females may express plasticity repeatedly across each of several time frames. We contrast the results of laboratory and field studies because, for most traits, these approaches give somewhat different answers. We provide ideas on what the cues might be for observed plasticity in each trait and, when possible, we inquire about the relative costs and benefits to expressed plasticity. We end with an example of how we think plasticity may play out in stickleback life history given what we know of plasticity in the ancestor. [ABSTRACT FROM AUTHOR]

Genetic variation was evaluated for spotted bass ( Micropterus punctulatus) at the edge of the species native range in central Texas. We analyzed mitochondrial D-Loop sequences from 64 individuals representing nine sites within the Brazos and Trinity River watersheds. Our primary objectives were to 1) compare the genetic diversity of spotted bass in central Texas to genetic diversity estimates of conspecifics in other geographic regions and to other species from similar geographic regions, to 2) determine whether there was evidence for within or between drainage genetic structure, and to 3) test whether the D-Loop sequence was a reliable marker for discriminating among native and introduced Texas micropterids. Genetic diversity was low relative to sympatric micropterids, as well as for the marker in general, but our results are similar to patterns observed for this species in Oklahoma and fit with broader multi-species patterns observed for this geographic area. AMOVA, SAMOVA, and isolation by distance analyses provided evidence that genetic differentiation exists among population groups. The sequence data suggests the D-Loop would be useful for discriminating among M. floridanus, M. salmoides, and M. dolomieu, but not among M. punctulatus, M. coosae, M. henshalli, and M. treculii. [ABSTRACT FROM AUTHOR]

Theoretical studies predict the lowest energy structures of the binuclear cyclopentadienylrhenium hydrides CpReH (Cp = η-CH; n = 4, 6, 8) to have a central doubly bridged Re(μ-H) unit with terminal η-Cp rings and the remaining hydrides as terminal ligands. However, the lowest energy CpReH structure by more than 12 kcal mol has one terminal η-Cp ring, a bridging η,η-Cp ring, and two terminal hydride ligands bonded to the same Re atom. The lowest energy hydride-free CpRe structure is a perpendicular structure with two bridging η,η-Cp rings. The previously predicted bent singlet CpRe structure with terminal η-Cp rings and a formal Re-Re sextuple bond lies ∼37 kcal mol above this lowest energy (η,η-Cp)Re structure. The thermochemistry of the CpReH and CpReH systems is consistent with the reported synthesis of the permethylated derivatives Cp*ReH and Cp*ReH (Cp* = η-MeC) as very stable compounds. Additionally, natural bond orbital analysis, atoms-in-molecules and overlap population density-of-state in AOMIX were applied to present the existence of rhenium-rhenium multiple bonds. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The recent discovery of boronyl complexes of the type (RP)Pt(BO)X (R = cyclohexyl; X = halogen) makes of interest the chemistry of complexes of the related thioboronyl (BS) ligand. In this connection, the binuclear iron carbonyl complex Fe(BS)(CO) is predicted by density functional theory to have a symmetrical unbridged structure similar to the valence isoelectronic Mn(CO). Higher-energy unsymmetrical (OC)Fe → Fe(BS)(CO) structures are also found as well as a doubly bridged Fe(BS)(CO)(µ-CO) structure. The complex Fe(BS)(CO) is predicted to be viable toward symmetrical dissociation into Fe(BS)(CO) fragments. However, the unsymmetrical dissociation of Fe(BS)(CO) into Fe(CO) + Fe(BS)(CO) is predicted to be exothermic by ~9 kcal mol. The low-energy structures of the mononuclear Fe(BS)(CO) include structures in which the two BS ligands have coupled to form a BS ligand through B-B bond formation. [ABSTRACT FROM AUTHOR]

We propose a series of icosahedral matryoshka clusters of A@B12@A20 (A = Sn, Pb; B = Mg, Zn, Cd), which possess large HOMO-LUMO gaps (1.29 to 1.54 eV) and low formation energies (0.06 to 0.21 eV/atom). A global minimum search using a genetic algorithm and density functional theory calculations confirms that such onion-like three-shell structures are the ground states for these A21B12 binary clusters. All of these icosahedral matryoshka clusters, including two previously found ones, i.e., [As@Ni12@As20]3- and [Sn@Cu12@Sn20]12-, follow the 108-electron rule, which originates from the high Ih symmetry and consequently the splitting of superatom orbitals of high angular momentum. More interestingly, two magnetic matryoshka clusters, i.e., Sn@Mn12@Sn20 and Pb@Mn12@Pb20, are designed, which combine a large magnetic moment of 28 µB, a moderate HOMO-LUMO gap, and weak inter-cluster interaction energy, making them ideal building blocks in novel magnetic materials and devices. [ABSTRACT FROM AUTHOR]

Copyright of International Orthopaedics is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The few distance sampling studies that use Bayesian methods typically consider only line transect sampling with a half-normal detection function. We present a Bayesian approach to analyse distance sampling data applicable to line and point transects, exact and interval distance data and any detection function possibly including covariates affecting detection probabilities. We use an integrated likelihood which combines the detection and density models. For the latter, densities are related to covariates in a log-linear mixed effect Poisson model which accommodates correlated counts. We use a Metropolis-Hastings algorithm for updating parameters and a reversible jump algorithm to include model selection for both the detection function and density models. The approach is applied to a large-scale experimental design study of northern bobwhite coveys where the interest was to assess the effect of establishing herbaceous buffers around agricultural fields in several states in the US on bird densities. Results were compared with those from an existing maximum likelihood approach that analyses the detection and density models in two stages. Both methods revealed an increase of covey densities on buffered fields. Our approach gave estimates with higher precision even though it does not condition on a known detection function for the density model. [ABSTRACT FROM AUTHOR]

Both coaxial and perpendicular singlet spin state structures are found for the dibenzene dimetal complexes (CH)M (M = Fe, Mn, and Cr) using density functional theory. For (CH)M (M = Fe, Mn), the coaxial structure is the lower energy structure, whereas for (CH)Cr the perpendicular structure is the lower energy structure. These coaxial structures are predicted to have very short M-M distances of ~1.98 Å for (CH)Fe, ~1.75 Å for (CH)Mn, and ~1.68 Å for (CH)Cr. Investigation into the frontier molecular orbitals suggests a formal 2 π Fe=Fe double bond in (CH)Fe, a σ + 2 π Mn≡Mn triple bond in (CH)Mn, and a σ + 2 π + δ quadruple bond in (CH)Cr. This gives each metal atom in these coaxial (CH)M (M = Fe, Mn, Cr) derivatives a 16-electron configuration suggesting an 8-orbital d p metal valence orbital manifold without the involvement of the s orbital. The coaxial (CH)M (M = Fe, Mn) derivatives have ideal sixfold D symmetry. However, distortion of coaxial (CH)Cr from D symmetry to D symmetry is observed because of involvement of only one orbital from the { d( xy), d( x − y)} set of δ symmetry of each chromium atom in the [InlineMediaObject not available: see fulltext.] formal quadruple bond. [ABSTRACT FROM AUTHOR]

The whitefly Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae) is a worldwide pest which has become one of the main pests in tomato crops. The predators Macrolophus pygmaeus (Rambur) and Nesidiocoris tenuis Reuter (Hemiptera: Miridae) and the parasitoid Eretmocerus mundus (Mercet) (Hymenoptera: Aphelinidae) have shown their efficacy at controlling B. tabaci populations when used as biological control agents. Intraguild predation (IGP) between natural enemies can affect their effectiveness at controlling pests. In the present study, the interaction of these three natural enemies and their effect on B. tabaci was studied on tomato plants by combining morphological observations and molecular analysis of trophic interactions. Under the conditions used in the present study, no IGP was detected between M. pygmaeus and N. tenuis by either counting dead predators or by PCR using prey-specific cytochrome c oxidase I primers. However, predation on B. tabaci decreased when they coexisted on the same plant, which could compromise the biological control of this pest. Although PCR analyses using E. mundus-specific primers showed predation on B. tabaci-parasitized nymphs in 27 % of M. pygmaeus and 17 % of N. tenuis, B. tabaci control was improved when both predators coexisted on the same plant with the parasitoid. The combined use of E. mundus and M. pygmaeus/ N. tenuis is therefore recommended in order to improve B. tabaci control in conservation biological control strategies. [ABSTRACT FROM AUTHOR]

The cobalt(III) complexes CpCoF and CpCo(CN) have been studied by density functional theory methods as representatives of the experimentally known CpCoX species with the weak-field fluoride ligand and the strong-field cyanide ligand. Both complexes were found to have relatively complicated energy surfaces with low-energy triplet and quintet spin state structures as well as the expected singlet-state structures for Co(III) complexes. This existence of singlet-, triplet-, and quintet-state structures of similar energies complicates the study of these complexes by density functional theory. The B3LYP* method of Reiher et al. was chosen in an effort to provide the most reliable estimates of the relative energies of the singlet, triplet, and quintet spin states. The lowest-energy CpCoF structure was found to be a doubly bridged quintet spin state structure, with similar triplet and singlet structures lying within ∼4 kcal mol of this quintet structure. The lowest-energy CpCo(CN) structure was found to be a triplet spin state structure, with a singlet structure lying within ∼1 kcal mol of this triplet structure. Almost all of the CpCoX structures were found to have nonbonding Co···Co distances in excess of 2.9 Å, as expected for Co(III) complexes. In general, structures with trans stereochemistry of the Cp and other terminal ligands were found to be of lower energy than the corresponding structures with cis stereochemistry. [ABSTRACT FROM AUTHOR]

The iron tricarbonyl complex of octafluorocyclooctatetraene was synthesized by Hughes and co-workers and shown by X-ray crystallography to have a trihapto-monohapto structure (η-CF)Fe(CO) in contrast to the tetrahapto structure (η-CH)Fe(CO) formed by the non-fluorinated cyclooctatetraene. This difference has stimulated a comprehensive density functional theoretical study of the octafluorocyclooctatetraene metal carbonyl complexes (CF)M(CO) ( n = 4, 3, 2, 1 for M = Ti, V, Cr, Mn, and Fe; n = 3, 2, 1 for M = Co, Ni) for comparison with their hydrogen analogues (CH)M(CO). In most such systems, the substitution of fluorine for hydrogen leads to relatively small changes in the preferred structures. However, for the iron carbonyl derivatives (CX)Fe(CO) (X = H, F), the difference observed experimentally has been confirmed by theory with (η-CF)Fe(CO) and (η-CH)Fe(CO) being the lowest energy structures by 4 and 14 kcal/mol, respectively. The ligand exchange reactions CH + (CF)M(CO) → CF + (CH)M(CO) are predicted to be exothermic for almost all of the systems considered, with the (η-CX)Fe(CO) system being the main exception. This suggests that the CF ligand generally bonds more weakly to transition metals than the CH ligand in accord with the electron-withdrawing effect of the ligand fluorine atoms. [ABSTRACT FROM AUTHOR]

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