Beryllium carbonyl Be(CO)n (n = 1-4) complex: a p-orbital analogy of Dewar-Chatt-Duncanson model.

Transition metal-carbonyl bonds are rationalized by M ← CO σ donation and M → CO π back donation where the d orbital of the transition metal is involved. This bonding model provided by Dewar, Chatt and Duncanson (DCD) has rationalized many transition metal-ligand bonds. The involvement of p orbital in such a DCD model can be intriguing. Alkaline earth metals with ns2np0 configuration may appear suitable as ns0np2 excitation has been recognized in many complexes. Herein, a theoretical study is presented for the Be(CO)n (n = 1-4) complex to verify this assumption. Detailed electronic structure analyses confirmed the involvement of the p orbital of beryllium in M → CO π back donation, thereby supporting the hypothesis. EDA-NOCV results reveal that the π-back donation from the central Be atom to CO ligands significantly predominates over the σ donation from the ligands for both Be(CO)3 and Be(CO)4. Our calculations reveal that Be(CO)4 is the highest carbonyl that may be experimentally detected.

Reply to the Comments on "Planar Tetracoordinate Hydrogen: Pushing the Limit of Multicentre Bonding (Angew. Chem. Int. Ed. 2024, 63, e202317312, DOI: 10.1002/anie.202317312" by Huo et al).

Recently, Huo et al. has commented on our communication (Angew. Chem. Int. Ed. 2024, 63, e202317312, DOI: 10.1002/anie.202317312), regarding the multireference character (MRC) of our proposed cluster. Their argument is based on small HOMO-LUMO gap, fractional occupation density (FOD) and CASPT2(12,13) calculations. They also proposed that the singlet planar In4H+ cluster cannot be observed. We present our calculations which reveals that some of their arguments are based on wrong interpretation of data and inadequate use of methodology. While we certainly agree with the strong physical ground of FOD, CASSF and CASPT2 methodology, we believe that such analysis for clusters is not adequate.

Association of Posterior Reversible Encephalopathy Syndrome (PRES) with Preeclampsia with Severe Symptoms and Eclampsia in South East Part of Bangladesh.

Posterior reversible encephalopathy syndrome (PRES) is a pathology seen not only in precelampsia with severe symptoms and eclampsia but in a varicty of diseases/ conditions. With the availability of neuroimaging, it is possible to know the exact underlying Central nervous system (CNS) pathology in preeclampsia with severe symptoms and eclampsia and thus therapy can be targeted. Preeclampsia with severe symptoms and eclampsia remains to be an important cause of maternal morbidity and mortality in both the developing and developed world. The objective of this study was to evaluate the association of Posterior reversible encephalopathy syndrome (PRES) by MRI (Magnetic resonance imaging) with preeclampsia with severe symptoms and eclampsia in south east part of Bangladesh. This cross-sectional observational study was performed among women suffering from preeclampsia with severe symptoms and eclampsia who attended at Obstetrics & Gynaecology department of Chittagong Medical College Hospital (CMCH), Bangladesh from January 2021 to June 2021. According to inclusion/exclusion criteria 50 samples were taken by convenient sampling for this study. A detail history was taken and complete general physical and gynecological examination was performed. Required data was collected through preset questionnaire. Neuroimaging reports were reviewed by both neurologist and radiologist. Data was analyzed by using windows based computer software device, SPSS 25.0. Results obtained from this study will be used to make a statement regarding aggressive management for cerebral vasospasm in severe preeclampsia and eclamptia related PRES. PRES has been reported to be reversible but late recognition or incorrect treatment can cause irreversible brain damage. Institution of early treatment leads to resolution of symptoms without any neurologic deficit and thus reduces maternal morbidity and mortality. PRES is a cliniconeuroradiologic entity. This study can aware doctors regarding prompt diagnosis of PRES in peripartum period among patient suffering from preeclampsia with severe symptoms and eclampsia by imaging aside clinical findings. A conclusive decision can be made to improve the outcome in this potentially life threatening but reversible condition.

Planar Tetracoordinate Hydrogen: Pushing the Limit of Multicentre Bonding.

Among the list of planar tetracoordinate atoms, the smallest element hydrogen is missing. No experimental and theoretical evidence have ever been put forwarded. Herein, we introduce the first planar tetracoordinate hydrogen atom (ptH) in the global minimum geometry of In4 H+ cluster. Bonding analysis indicates that the central hydrogen atom is acting like a proton and significant charge transfer from the surrounding In4 framework results in a negative charge of the central hydrogen atom. The proposed global minimum geometry possesses σ-aromaticity and the central hydrogen atom forms unusual multicentre bond with more than three centres.

AGA Clinical Practice Guideline on the Management of Pouchitis and Inflammatory Pouch Disorders.

BACKGROUND & AIMS: Pouchitis is the most common complication after restorative proctocolectomy with ileal pouch-anal anastomosis for ulcerative colitis. This American Gastroenterological Association (AGA) guideline is intended to support practitioners in the management of pouchitis and inflammatory pouch disorders. METHODS: A multidisciplinary panel of content experts and guideline methodologists used the Grading of Recommendations Assessment, Development and Evaluation framework to prioritize clinical questions, identify patient-centered outcomes, conduct an evidence synthesis, and develop recommendations for the prevention and treatment of pouchitis, Crohn's-like disease of the pouch, and cuffitis. RESULTS: The AGA guideline panel made 9 conditional recommendations. In patients with ulcerative colitis who have undergone ileal pouch-anal anastomosis and experience intermittent symptoms of pouchitis, the AGA suggests using antibiotics for the treatment of pouchitis. In patients who experience recurrent episodes of pouchitis that respond to antibiotics, the AGA suggests using probiotics for the prevention of recurrent pouchitis. In patients who experience recurrent pouchitis that responds to antibiotics but relapses shortly after stopping antibiotics (also known as "chronic antibiotic-dependent pouchitis"), the AGA suggests using chronic antibiotic therapy to prevent recurrent pouchitis; however, in patients who are intolerant to antibiotics or who are concerned about the risks of long-term antibiotic therapy, the AGA suggests using advanced immunosuppressive therapies (eg, biologics and/or oral small molecule drugs) approved for treatment of inflammatory bowel disease. In patients who experience recurrent pouchitis with inadequate response to antibiotics (also known as "chronic antibiotic-refractory pouchitis"), the AGA suggests using advanced immunosuppressive therapies; corticosteroids can also be considered in these patients. In patients who develop symptoms due to Crohn's-like disease of the pouch, the AGA suggests using corticosteroids and advanced immunosuppressive therapies. In patients who experience symptoms due to cuffitis, the AGA suggests using therapies that have been approved for the treatment of ulcerative colitis, starting with topical mesalamine or topical corticosteroids. The panel also proposed key implementation considerations for optimal management of pouchitis and Crohn's-like disease of the pouch and identified several knowledge gaps and areas for future research. CONCLUSIONS: This guideline provides a comprehensive, patient-centered approach to the management of patients with pouchitis and other inflammatory conditions of the pouch.

A Neutral Planar Four-Membered Si2B2 2π-Aromatic Ring.

The synthesis of the first inorganic four-membered neutral 2π-aromatic compound 2 is reported. This unique ring has been synthesized from a simple and straightforward reaction of amidinato-silylene with dichlorophenylborane, followed by the reduction with KC8 in THF. Compound 2 has been fully characterized by single-crystal X-ray diffraction (SC-XRD), NMR spectroscopy, and mass spectrometry. The computational calculations reveal that the Si2B2 ring is a π-delocalized system resulting from the interaction of pπ orbital of B and Si-N σ* orbitals having pseudo π symmetry. Compound 2 is the first known example of a neutral planar inorganic analogue of cyclobutenyl dication.

Visible Light-Active Ternary Heterojunction Photocatalyst for Efficient CO2 Reduction with Simultaneous Amine Oxidation and Sustainable H2O2 Production.

The present work described a unique approach for CO2 reduction to methanol along with the oxidation of various amines to the corresponding imines and photocatalytic H2O2 production from H2O and molecular O2 using a heterojunction photocatalyst made up of ZnIn2S4/Ni12P5/g-C3N4(NCZ) under visible light irradiation. The photocatalysts were synthesized via a high-temperature treatment of nickel and phosphorous precursors with g-C3N4 followed by decoration of ZnIn2S4. The synthesized photocatalysts were characterized using various spectroscopic and microscopic techniques. The density functional theory (DFT) studies suggested the participation of the valence band maximum (VBM) from Ni12P5 and the conduction band maximum (CBM) from ZnIn2S4 in the ternary NCZ heterojunction. The ternary composite exhibited superior photocatalytic activity compared to that of its individual components due to the formation of a heterojunction, thereby enhancing the transfer efficiency of electrons from the conduction band of g-C3N4 to that of ZnIn2S4 using Ni12P5 as an electron bridge. Moreover, the reduced band gap of the ternary heterojunction played a key role in its higher efficiency.

Inorganic Bergman Cyclization: An Appeal From Theory.

The scope of Bergman cyclization is expanded computationally by exploring the cyclization in inorganic B, N substituted derivative. This substitution has introduced polarity into the transition state, which resulted in dramatic lowering of the activation barrier. Natural charge distribution throughout the reaction profile has ascertained this hypothesis. Single B and N atom substitution at 1 and 6 terminal positions lowers the activation barrier by almost half of the original value which becomes even lower in the complete B, N analogue. The parent Bergman and single B, N substituted products were characterized by significant biradical character while the complete B, N substituted analogue was characterized by significant zwitterionic character. Reduction in electron delocalization is also observed in the complete B, N substituted analogue.

Ultra-high reversible hydrogen storage capacity of the Li4B2 cluster: a quantum chemical study.

Quantum chemical calculations have been carried out to investigate the hydrogen adsorption characteristics of the Li4B2 cluster. Calculations reveal that the cluster can adsorb a maximum of thirteen H2 molecules reaching a considerably high gravimetric density of 34.66 wt%. The nature of the interaction between the H2 molecule and Li center has been investigated within the realm of quantum theory of atoms in molecules which revealed the non-covalent character. The fate of H2 absorption by the cluster has been studied in the course of a 2000 fs time evolution through Born-Oppenheimer molecular dynamics simulations at different temperatures. The outcomes reveal that the H2 molecules are strongly bound at 77 K and get slowly released at elevated temperatures.

"Screen and Treat" Approach among VIA Positive Women during Cervical Cancer Screening Program: Experience at Low Resource Setting.

Cancer of the uterine cervix is one of the leading causes of mortality and morbidity among women in poor countries. It is the most common reproductive cancer among women in Bangladesh and most women are diagnosed at advanced stage when appropriate treatment is not possible. But this cancer is preventable through proper screening and simultaneous treatment of premalignant lesions. The same day "Screen and Treat" approach is an endeavour to reach the goal especially at low resource settings. Ablation of precancerous lesions by thermo-coagulation is a promising mode of complete cure as this method is easy to apply, effective and relatively cheaper than other procedures. To avoid the issue of overtreatment, an intermediate approach- colposcopy can be used. Aim of this study was to diagnose premalignant lesions of cervix during screening procedure and to treat the lesions by thermo-coagulation at the same sitting. This prospective study was carried out at Upzilla Health Complex (UHC), Rangunia, from 3rd February 2018 to 6th February 2018 in a campaign of cervical cancer screening program by visual inspection of cervix with 5.00% acetic acid (VIA). About 1000 women attending the outpatient department were enrolled in this study by consecutive sampling technique according to inclusion and exclusion criteria. Informed consent was taken after explaining the screening method, thermo-coagulation procedure and follow up schedule. VIA was found positive in 22 cases. Colposcopy was done in VIA positive cases by Gynocular colposcope. Punch biopsy was taken when colposcopy revealed positive in 12 women. Then thermo-coagulation was done. Histopathology report revealed, CIN1 (cervical intraepithelial neoplasia 1)- in 6 cases (50.00%); CIN 2 (cervical intraepithelial neoplasia 2)- in 01 case (8.33%); Chronic cervicitis with squamous metaplasia- in 05 cases (41.67%). Sensitivity and specificity of colposcopy was calculated considering colposcopy directed biopsy as gold standard, which was 100.00% and 75.00% respectively in CIN-1. While in CIN-2 it was 100.00% and 95.20% respectively. VIA is an effective screening tool for cancer cervix. Main advantage is the "screen and treat" approach can be attempted for at risk women in low resource setting by thermo-coagulation which is accepted by women while guaranteeing satisfactory cure rates. Thus, reduces loss to follow-up and have an impact on cervical cancer control.

Boron-boron quadruple bond in Li3B2- and Li4B2 clusters.

Homopolar quadruple bonding in first row p-block elements is expected due to the presence of four valence orbitals accessible for bonding. Although quadruple bonding in C2 has been proposed, no such proposal exists for B2. Here we report the unprecedented B-B quadruple bonding in Li3B2- and Li4B2 clusters based on high level theoretical calculations. The quadruple bonding is omnipresent in the global minimum, its nearest energy isomer and the transition states connecting them. Various bonding analyses reveal the unprecedented nature of the BB quadruple bonding interaction.

Is a transition metal-silicon quadruple bond viable?

Quadruple bonding in heavier main group elements is not known albeit having four valence orbitals accessible for bonding. Here we report the unprecedented quadruple bonding between a silicon atom and a transition metal fragment in the 1A1 electronic ground state of C3v symmetric SiRu(CO)3 based on high level theoretical calculations. Various bonding analyses reveal the nature of the Si[quadruple bond, length as m-dash]Ru quadruple bonding interaction, which involves one usual Si-Ru σ bond, two usual Si-Ru π bonds and one additional Si → Ru dative σ bond.

Unsupported Donor-Acceptor Complexes of Noble Gases with Group 13 Elements.

Unsupported donor-acceptor complexes of noble gases (Ng) with group 13 elements have been theoretically studied using density functional theory. Calculations reveal that heavier noble gases form thermodynamically stable compounds. The present study reveals that no rigid framework is necessary to stabilize the donor-acceptor complexes. Rather, prepyramidalization at the Lewis acid center may be an interesting alternative to stabilize these complexes. Detailed bonding analyses reveal the formation of two-center-two-electron dative bonding, where Ng atoms act as a donor.

Planar Pentacoordinate Nitrogen in a Pseudo-Double-Aromatic NBe5H4+ Cluster.

High-level quantum-chemical calculations have been used to predict a cationic ternary NBe5H4+ cluster containing a planar pentacoordinate nitrogen atom. The proposed cluster has pseudo dual aromaticity and is kinetically and thermodynamically very stable.

Transition metal carbon quadruple bond: viability through single electron transmutation.

Quadruple bonding to main group elements is extremely rare although they have four valence orbitals accessible for bonding. Here we report the unprecedented quadruple bonding between a carbon atom and a transition metal fragment Fe(CO)3 based on high level theoretical calculations. Various bonding analyses reveal the unprecedented nature of the C[quadruple bond, length as m-dash]Fe quadruple bonding interaction. The validity of the single electron transmutation concept has been tested which fruitfully reproduces the structural and bonding similarities between the two neighbours in the periodic table.

Double aromaticity in a BBe6H6+ cluster with a planar hexacoordinate boron structure.

Aromaticity is one of the central concepts in chemistry and stabilizes many clusters that have interesting structural motifs. Herein, a cationic BBe6H6 cluster featuring a planar hexacoordinate boron structure stabilized by 2π/6σ double aromaticity was predicted theoretically. The cluster was predicted to be dynamically stable well above room temperature.

Two New Species of the Genus Coomansinema Ahmad and Jairajpuri, 1989 (Nematoda: Dorylaimida) with a Key to its Species.

Two new species of the genus Coomansinema Ahmad and Jairajpuri, 1989 are described and illustrated. C. japonicum n. sp. is characterized by having medium size body (L= 1.40 - 1.45 mm); lip region truncate with completely amalgamated lips; amphideal fovea goblet - shaped; 16 - 20 µm long odontostyle; 23 - 25 µm long odontophore; comparatively anterior position of the second pair of pharyngeal glands; amphidelphic female genital system; longitudinal vulva; males with 48 - 54 µm long spicules; 7 - 8 spaced ventromedian supplements and tail long filiform in female and short conoid in male. C. longicaudatum n. sp. is characterized by having medium size body (L= 1.1 - 1.3 mm); lip region truncate, continuous with completely amalgamated lips; amphideal fovea cup - shaped; 16 - 17 µm long odontostyle; 19 - 20 µm long odontophore; comparatively anterior position of the second pair of pharyngeal glands; amphidelphic female genital system; transverse vulva, intestinal - prerectum junction with a tongue - like structure and 210 - 269 µm long filiform tail. A key to its seven valid species is provided.

Removal of Cu(II), Pb(II) and Cr(VI) ions from aqueous solution using amidoximated non-woven polyethylene-g-acrylonitrile fabric.

Pre-irradiation method was applied to graft acrylonitrile (AN) onto non-woven polyethylene film. Graft yield reached 130% at 70 kGy radiation dose, 60% monomer concentration and 4 h reaction time when H2SO4 was used as an additive. The modification of AN grafted films with hydroxyl amine hydrochloride was done for the preparation of amidoxime adsorbent. The constructed adsorbent was characterized using FTIR, DMA and SEM. The amidoxime adsorbent was used for adsorption of Cu(II), Pb(II) and Cr(VI). Adsorption capacity was investigated under different conditions: contact time, pH and initial metal ion concentration. The optimum condition for maximum adsorption was found to be contact time 72 h and initial metal concentration 500 ppm for all the metal ions studied and pH 5.2 for Cu(II), 5.4 for Pb(II), 1.5 for Cr(VI). Kinetic adsorption data was elucidated using pseudo-first-order and pseudo-second-order equations. The equilibrium experimental data of metal adsorption matched Langmuir isotherm model. From the Langmuir equation, the monolayer saturation adsorption capacity (highest adsorption capacity) of the adsorbent was found to be 74.62 mg/g for Cu(II), 107 mg/g for Pb(II) and 156.25 mg/g for Cr(VI). The thermodynamics of metal adsorption was also investigated. Furthermore, desorption and reuse of the adsorbent film was studied. The results suggest that the adsorbent can be effective for adsorption of Cu(II), Pb(II) and Cr(VI).

Ultra-Weak Metal-Metal Bonding: Is There a Beryllium-Beryllium Triple Bond?

Metal-metal triple bonds featuring s-block element have not been reported until now. Only Be-Be double bonds between have been predicted theoretically based on the intuitive electron donation from four s1 type electron-donating ligands. Herein, we theoretically predicted a novel species featuring a Be-Be triple bond in the Li6 Be2 molecule. The molecule was found to be thermodynamically stable. The presence of the triple bond was confirmed by adaptive natural density partitioning (AdNDP), electron localization function (ELF), and atoms in molecules (AIM) analyses. Moreover, the mechanical strength of the Be-Be triple bond was analyzed by using compliance matrix, pointing towards its ultra-weak nature.

Diagnostic Value of Extraoral Periapical Radiograph in Comparison to Intraoral Periapical Radiograph: A Cross-sectional, Institutional Study.

BACKGROUND: Radiographs form an invaluable adjunct in diagnosis, treatment planning, and postoperative evaluation during patient management in the dental office where intraoral periapical (IOPA) radiographs are the ones most commonly used. However, certain conditions render the placement of film difficult. In such cases, a panoramic radiograph may be taken, but it has the disadvantage of higher radiation exposure and cost. Extraoral periapical (EOPA) technique allows radiographs to be taken on an IOPA film by placing it extraorally. We aimed to evaluate its diagnostic accuracy compared to intraoral bisecting angle technique. MATERIALS AND METHODS: Forty-five patients were randomly selected. Ninety radiographs were taken; two for each patient. First image was obtained by intraoral bisecting angle technique and second by EOPA technique. A scale was devised for the comparison of radiographs taken by the two techniques. Two experienced oral radiologists rated them based on the scale followed by statistical analysis. RESULTS: Patients reported increased compliance with the EOPA technique. 84.40% of the EOPA radiographs (EOPARs) were diagnostically acceptable; sensitivity and specificity was 84% and 55%, respectively. CONCLUSION: EOPAR is beneficial in cases where intraoral film placement is difficult, and a radiograph is necessary for patient management, even though it demonstrates comparatively lesser diagnostic accuracy.