Monodentate Phosphinoamine Nickel Complex Supported on a Metal-Organic Framework for High-Performance Ethylene Dimerization.

Ethylene dimerization is an efficient industrial chemical process to produce 1-butene, with demanding selectivity and activity requirements on new catalytic systems. Herein, a series of monodentate phosphinoamine-nickel complexes immobilized on UiO-66 are described for ethylene dimerization. These catalysts display extensive molecular tunability of the ligand similar to organometallic catalysis, while maintaining the high stability attributed to the metal-organic framework (MOF) scaffold. The highly flexible postsynthetic modification method enables this study to prepare MOFs functionalized with five different substituted phosphines and 3 N-containing ligands and identify the optimal catalyst UiO-66-L5-NiCl2 with isopropyl substituted nickel mono-phosphinoamine complex. This catalyst shows a remarkable activity and selectivity with a TOF of 29 000 (molethyl/molNi/h) and 99% selectivity for 1-butene under ethylene pressure of 15 bar. The catalyst is also applicable for continuous production in the packed column micro-reactor with a TON of 72 000 (molethyl/molNi). The mechanistic insight for the ethylene oligomerization has been examined by density functional theory (DFT) calculations. The calculated energy profiles for homogeneous complexes and truncated MOF models reveal varying rate-determining step as ß-hydrogen elimination and migratory insertion, respectively. The activation barrier of UiO-66-L5-NiCl2 is lower than other systems, possibly due to the restriction effect caused by clusters and ligands. A comprehensive analysis of the structural parameters of catalysts shows that the cone angle as steric descriptor and butene desorption energy as thermodynamic descriptor can be applied to estimate the reactivity turnover frequency (TOF) with the optimum for UiO-66-L5-NiCl2. This work represents the systematic optimization of ligand effect through combination of experimental and theoretical data and presents a proof-of-concept for ethylene dimerization catalyst through simple heterogenization of organometallic catalyst on MOF.

Expression of syndecan-1 in different grades of oral squamous cell carcinoma: An immunohistochemical study.

Background: Syndecans are a family of transmembrane proteins, belonging to heparin sulphate proteoglycan family and are localized entirely to the epithelial cells with the stratified squamous epithelia. They are involved in cell-cell adhesion and interaction with the extracellular matrix and play a critical role in cell growth, differentiation, cell morphology, and migration. The down regulation of syndecan-1 indicates loss of cellular adhesion and possibility of invasion. The present study is aimed to evaluate the difference in immunohistochemical expression of syndecan-1 in different grades of oral squamous cell carcinoma (OSCC) patients and control group. Methods: The present study consists of 42 cases of paraffin-embedded tissue sections of OSCC; 14 well differentiated, 14 moderately differentiated, and 14 poorly differentiated. As a control, 10 paraffin-embedded tissue sections of unaffected oral mucosa were used. The sections were stained for immunohistochemical expression of syndecan -1. The intensity of staining was scored. The immunohistochemistry scores for each sample were obtained by Tissue Quant software. Results: Statistical analysis revealed that there was a significant decrease in intensity of staining between normal and different grades of OSCC. Conclusion: This study shows that as cellular differentiation was lost, syndecan-1 expression was less. This provides an insight and understanding of the pathophysiology of the invasive process of OSCC and helps in establishing the prognostic link.

Assessment of the role of the Edinburgh dysphagia score in referral triage in a national service evaluation of the urgent suspected upper gastrointestinal cancer pathway.

BACKGROUND: The British Society of Gastroenterology has recommended the Edinburgh Dysphagia Score (EDS) to risk-stratify dysphagia referrals during the endoscopy COVID recovery phase. AIMS: External validation of the diagnostic accuracy of EDS and exploration of potential changes to improve its diagnostic performance. METHODS: A prospective multicentre study of consecutive patients referred with dysphagia on an urgent suspected upper gastrointestinal (UGI) cancer pathway between May 2020 and February 2021. The sensitivity and negative predictive value (NPV) of EDS were calculated. Variables associated with UGI cancer were identified by forward stepwise logistic regression and a modified Cancer Dysphagia Score (CDS) developed. RESULTS: 1301 patients were included from 19 endoscopy providers; 43% male; median age 62 (IQR 51-73) years. 91 (7%) UGI cancers were diagnosed, including 80 oesophageal, 10 gastric and one duodenal cancer. An EDS ≥3.5 had a sensitivity of 96.7 (95% CI 90.7-99.3)% and an NPV of 99.3 (97.8-99.8)%. Age, male sex, progressive dysphagia and unintentional weight loss >3 kg were positively associated and acid reflux and localisation to the neck were negatively associated with UGI cancer. Dysphagia duration <6 months utilised in EDS was replaced with progressive dysphagia in CDS. CDS ≥5.5 had a sensitivity of 97.8 (92.3-99.7)% and NPV of 99.5 (98.1-99.9)%. Area under receiver operating curve was 0.83 for CDS, compared to 0.81 for EDS. CONCLUSIONS: In a national cohort, the EDS has high sensitivity and NPV as a triage tool for UGI cancer. The CDS offers even higher diagnostic accuracy. The EDS or CDS should be incorporated into the urgent suspected UGI cancer pathway.

Insights into Coke Formation and Removal under Operating Conditions with a Quantum Nanoreactor Approach.

The in situ formation and removal of coke is a critical problem in heterogeneous catalysis, but its mechanism is not well understood. This work investigates the mechanism of carbon deposition and hydrogenation on an Fe cluster under high-temperature conditions with the density functional tight-binding (DFTB) based nanoreactor molecular dynamics (NMD) method. Our study shows that successive formation of carbon chains, rings, and fused rings occurred during the carbon deposition on Fe clusters. Hydrogenation of activated carbon happens through direct C-H coupling, while the hydrogenation of graphitic carbon involves hydrogenation of the edge carbon, ring-opening reaction, and dealkylation reaction. The main function of the Fe catalyst is to provide the active sites for H2 dissociation and dissociated H spillover, while its activity toward C-C bond breaking is limited. These results highlight the role of the DFTB-NMD method as an effective tool to investigate reaction mechanisms under operating conditions in heterogeneous catalysis.

Evaluation of magnesium levels in blood and saliva of oral squamous cell carcinoma and potentially malignant disorders by xylidyl blue method.

BACKGROUND: Cancer is Latinized from Greek word 'karkinos' meaning crab, denoting how carcinoma extends its claws like a crab into adjacent tissues. It has been well established by researchers that virtually all oral cancer are preceded by visible clinical changes in the oral mucosa usually in the form of white or red patch (two-step process of cancer development). Mg is an essential mineral that is needed for a broad variety of physiological functions. Imbalances in Mg metabolism are common and are associated with different pathological conditions. The purpose of this study was to evaluate and compare the magnesium concentration in blood serum and saliva of oral squamous cell carcinoma, potentially malignant disorders and healthy subjects to serve as a positive marker or indicator in the process of carcinogenesis. MATERIALS AND METHODS: The study includes 17 precancerous (OSMF + Leukoplakia) patients, 17 OSCC and 17 control group. Blood and saliva was collected; serum and saliva was extracted from both the groups and was biochemically evaluated for magnesium levels. Statistical analysis was performed using ANOVA. RESULTS: The Salivary magnesium Mean ± SD of Healthy group is higher 1.6681 ± 0.0207 mmol mg/l followed by Potentially Malignant Disorder group 1.5532 ± 0.0283 and Oral Squamous Cell Carcinoma 0.5979 ± 0.0659. The mean values differ significantly between 3 groups (P < 0.001) The Serum magnesium Mean ± SD of Healthy group is higher 1.9188 ± 0.0550 mmol mg/l followed by Potentially Malignant Disorder group 1.6951 ± 0.0949 and Oral Squamous Cell Carcinoma 0.7329 ± 0.1561. The mean values differ significantly between 3 groups (P < 0.001) The study revealed decreased serum and salivary magnesium in oral precancerous patients and an Oral Squamous cell carcinoma patients compared to healthy individuals. CONCLUSION: The magnesium concentration was low in both blood plasma and saliva of oral squamous cell carcinoma as compared to potentially malignant disorders and healthy subjects. Thus the magnesium ion concentration in blood plasma and saliva could be considerd as tumor marker, playing an important role in carcinogenesis.

Comparative analysis of cell proliferation ratio in plaque and erosive oral lichen planus: An immunohistochemical study.

BACKGROUND: Proliferating cell nuclear antigen (PCNA) is a nuclear protein synthesized in the late G1 and S-phase of the cell cycle. Detection of this protein represents a useful marker of the proliferation status of lesions. This study has been carried out to evaluate the cell proliferation rate in oral lichen planus (OLP) and comparison between plaque and erosive lichen planus, which indicates the potential for malignant transformation. MATERIALS AND METHODS: This study was comprised of 64 cases of histologically proven lichen planus, out of which 32 cases of plaque and erosive each was taken. Two sections were taken from each, one for H and E staining to verify histological diagnosis according to Eisenberg criteria, other sections were stained according to super sensitive polymer horse radish peroxidise method for identifying immunohistochemical expression of PCNA. Data were statistically analyzed by Tukey high-range statistical domain test. Statistically significant P value was considered <0.05. RESULTS: In two types of lichen planus, erosive type (66.86%) showed higher expression of PCNA followed by plaque (17.07%). Overall, P value was <0.001, which was statistically significant. It indicates that proliferation activity is more in erosive lichen planus followed by plaque type, which ultimately results in increased rate of malignant transformation. CONCLUSION: PCNA is a good nuclear protein marker to evaluate the proliferation status of OLP. Out of the two types of lichen planus, erosive type possesses more proliferative ratio and chances of malignant change is more in this type. It emphasizes the importance of long-term follow-up with erosive type when compared with plaque type.

Unusual Case of Vogt-Koyanagi-Harada Syndrome Presenting as Non-specific Headache.

Vogt-Koyanagi-Harada syndrome (VKH) is a bilateral intraocular granulomatous panuveitis which is frequently associated with systemic manifestations such as meningismus, tinnitus, poliosis and vitiligo of autoimmune aetiology. Headache by itself, does not fulfill the diagnostic criteria and is insufficient for the diagnosis. A 22-year-old male presented with a 10 day history of headache, followed by decreased vision in both eyes. Slit lamp biomicroscopy revealed sluggishly reactive pupils with anterior uveitis, mild vitritis and hyperaemic discs with bilateral exudative retinal detachments. All uveitis workups were negative. Follow up of three years revealed no neurological or auditory symptoms. Headache alone, followed by decreased vision, before the onset of neurological and auditory symptoms, can be an initial presentation of Vogt-Koyanagi-Harada (VKH) syndrome. VKH should be considered in the differential diagnosis of atypical presentations of headache.

Focal active colitis: a prospective study of clinicopathological correlations in 90 patients.

AIMS: Considerable controversy exists about the clinical implication of a diagnosis of focal active colitis (FAC). The aim of this study was to assess clinicopathological correlations of FAC in 90 adults, representing the largest and only prospective series of FAC. METHODS AND RESULTS: Patients were assessed by comprehensive clinical follow-up and questionnaires. Fifteen histopathological features were scored and correlated with clinical outcome. In 24% of patients drugs, especially NSAIDs, were implicated. Infection was a probable cause in 19%. In 14 patients (15.6%), predominantly women, a diagnosis of chronic inflammatory bowel disease was ultimately made. Most were Crohn's disease, but this is the first study in which FAC has presaged an ultimate diagnosis of ulcerative colitis in adults (in two patients). A specific subtype of FAC, termed basal FAC, was significantly associated with drugs. These excepted, this study has found no histopathological parameters of FAC, such as amount, location and/or distribution, to correlate with clinical outcome or allowed selection of those patients more likely to show subsequent evidence of chronic inflammatory bowel disease. CONCLUSION: This study has provided powerful information on the implication of a diagnosis of FAC. In a small but not inconsiderable case number, the ultimate diagnosis will be chronic inflammatory bowel disease.