Removal Of Bulk Research Articles

Drying and Analysis of Aluminum (Oxy)hydroxide Films for Dry Storage of Aluminum-Clad Spent Nuclear Fuels

In aluminum-clad spent nuclear fuels, an (oxy)hydroxide layer on the surface of the cladding hosts chemisorbed water formed during reactor and post-discharge exposure to water. Any residual water is susceptible to generating hydrogen via radiolysis, which can be a risk associated with dry fuel storage. Engineering-scale forced helium dehydration (FHD) and vacuum drying tests were conducted on mock-up fuel assemblies that included corroded aluminum surrogate plates to assess the removal of bulk and chemisorbed water. Thermogravimetric analysis was performed on samples of the surrogate plates, both undried control samples used to determine onset temperatures associated with a phase change occurring in the oxide layer and samples from drying tests used to determine the effectiveness of each drying method. Both vacuum drying and FHD processes were capable of removing bulk water. However, FHD was determined to provide additional drying capabilities, including partial removal of chemisorbed water from bayerite due to the higher temperatures during drying. The temperature threshold for partial dehydroxylation of the oxide layer was determined to be around 220°C, meaning any drying methods attempting to remove chemisorbed water must exceed 220°C.

PD-L1 Expression in Endometrial Cancer and Its Association with Clinicopathological Features: A Systematic Review and Meta-Analysis.

Simple SummaryIn women, endometrial cancer is a crucial cancer cause-death, which is still not fully explored in its pathogenesis and immune system. Early detection is essential for proper treatment and follow-up in affected patients. This systematic review and meta-analysis aim to pool the prevalence of PD-L1 in endometrial cancer and its association with clinicopathological features. The pooled prevalence of PD-L1 was 34.26% in tumour cells, and 51.39% in immune cells among endometrial cancer patients. There was significant association of PD-L1 expression in both tumour cells and immune cells with advanced stage endometrial cancer. The presence of lympho-vascular invasion and poor overall survival were also associated with PD-L1 expression in immune cells. These information enable clinicians to stratify endometrial cancer patients for anti-PD-1/PD-L1 immune therapy.Endometrial cancer (EC) is one of the most common malignancies of the female genital tract and its current treatment mainly relies on surgical removal of the tumour bulk, followed by adjuvant radiotherapy with or without chemotherapy/hormonal therapy. However, the outcomes of these approaches are often unsatisfactory and are associated with severe toxicity and a higher recurrence rate of the disease. Thus, more clinical research exploring novel medical intervention is needed. Involvement of the immune pathway in cancer has become important and the finding of a high positive expression of programmed cell death-ligand 1 (PD-L1) in EC may offer a better targeted therapeutic approach. Numerous studies on the PD-L1 role in EC have been conducted, but the results remained inconclusive. Hence, this systematic review was conducted to provide an update and robust analysis in order to determine the pooled prevalence of PD-L1 expression in EC and evaluate its association with clinicopathological features in different focuses of tumour cells (TC) and immune cells (IC). A comprehensive literature search was conducted using the PubMed, Web of Science, and Scopus databases. Twelve articles between 2016 and 2021 with 3023 EC cases met the inclusion criteria. The effect of PD-L1 expression on the outcome parameters was estimated by the odds ratios (ORs) with 95% confidence intervals (CIs) for each study. The pooled prevalence of PD-L1 was 34.26% and 51.39% in the tumour cell and immune cell, respectively, among women with EC. The PD-L1 expression was significantly associated with Stage III/IV disease (in both TC and IC) and correlated to the presence of lympho-vascular invasion in IC. However, the PD-L1 expression in TC was not associated with the age groups, histology types, myometrial invasion, and lympho-vascular invasion. In IC, PD-L1 expression was not associated with age group, histology type, and myometrial invasion. The meta-analysis survival outcomes of PD-L1 high expression had a significant association with worse OS in IC but not in TC.

Radioresistance and Transcriptional Reprograming of Invasive Glioblastoma Cells

Infiltrative growth pattern is a hallmark of glioblastoma (GBM). Radiation therapy aims to eradicate microscopic residual GBM cells after surgical removal of the visible tumor bulk. However, in-field recurrences remain the major pattern of therapy failure. We hypothesized that the radiosensitivity of peripheral invasive tumor cells (peri) may differ from the predominantly investigated tumor bulk. Invasive GBM populations were generated via debulking of the visible tumor core and serial orthotopic transplantation of peri cells, and sustained proinvasive phenotype of peri cells was confirmed in vitro by scratch assay and time lapse imaging. In parallel, invasive GBM cells were selected by transwell assay and from peri cells of patient-derived 3-dimensional spheroid cultures. Transcriptome analysis deciphered a GBM invasion-associated gene signature, and functional involvement of key pathways was validated by pharmacologic inhibition. Compared with the bulk cells, invasive GBM populations acquired a radioresistant phenotype characterized by increased cell survival, reduced cell apoptosis, and enhanced DNA double-strand break repair proficiency. Transcriptome analysis revealed a reprograming of invasive cells toward augmented activation of epidermal growth factor receptor- and nuclear factor-κB-related pathways, whereas metabolic processes were downregulated. An invasive GBM score derived from this transcriptional fingerprint correlated well with patient outcome. Inhibition of epidermal growth factor receptor and nuclear factor-κB signaling resensitized invasive cells to irradiation. Invasive cells were eradicated with similar efficacy by particle therapy with carbon ions. Our data indicate that invasive tumor cells constitute a phenotypically distinct and highly radioresistant GBM subpopulation with prognostic impact that may be vulnerable to targeted therapy and carbon ions.

Dual column HPLC method for determination of lanthanides in zirconium matrix

A high performance liquid chromatography (HPLC) method is developed for the determination of lanthanides present in zirconium matrix. α-Hydroxyisobutyric acid (α-HIBA) is used as an eluent for the removal of bulk of zirconium and pre-concentration of lanthanides. Later the pre-concentrated lanthanides are individually separated by dynamic ion exchange method. The method offers linearity in the concentration range of lanthanides from 2 to 100 ppb. The developed methodology is validated by analyzing simulated zirconium sample containing known amounts of lanthanides. The method is then used for quantitative recovery and determination of lanthanides in ZrO2 matrix with Zr/Ln amount ratios up to 250,000.

CSIG-20. EFFECT OF TUMOR-TREATING FIELDS (TTFIELDS) ON EGFR PHOSPHORYLATION IN GBM CELL LINES

Abstract Glioblastoma (GBM) is the most common high grade and most devastating brain tumor among adults. About 50% of GBM express EGFR (epidermal growth factor receptor) and from these another 50% the mutated form EGFRvIII which is associated with a more aggressive disease and poorer prognosis. We have previously shown that expression of different status of EGFR in GBM cell lines drives the 5-ALA induced fluorescence downstream by influencing the rate-limiting enzyme heme oxygenase-1 (HO-1) probably via PI3K/Akt signalling. We demonstrated that 5-ALA-induced protoporphyrin IX (PpIX) fluorescence is pharmacologically influenced by adding different drugs such as deferoxamine (DFO) and tin-protoporphyrin (SnPP), which are an iron chelator of Fe2+ and an inhibitor of HO-1 respectively, or genistein that promotes PpIX accumulation via functional repression of ABCG2 (ABC transporter G2). Our aim is to increase these pharmacological effects on PpIX fluorescence using tumor-treating fields (TTFields). TTFields, a new therapeutic technology for treating newly diagnosed or recurrent GBM, is able to suppress the growth of cancer cells destabilising microtubule elongation and increasing membrane permeability. Interestingly, TTFields, like as other destabilising drugs and compounds, is able to inhibit the phosphorylation of EGFR and subsequent downregulation of EGFR-induced signalling acting for example on the mechanism that regulate the HO-1 activity. Here, we investigate the effects of TTFields on glioma cells, with different EGFR status and consequently different PpIX fluorescence. Exposure to TTFields during or after pharmacological treatments may represent a novel strategy to block or diminish the phosphorylation of EGFR to ameliorate the visualization of PpIX fluorescence in patients where it is not enough to ensure a safe and precise removal of the tumor bulk. In fact, if a combination of TTFields and drug treatment should give the desired results, this strategy could be applied on patients before being subjected to surgical resection.

Analysis of sub-picogram quantities of 238Pu by thermal ionization mass spectrometry

A multiple ion-counting total evaporation technique has been developed for precise analysis of sub-picogram (pg) quantities of 238Pu by thermal ionization mass spectrometry (TIMS). A resin bead loading procedure was tailored to minimize uranium (U) contamination during loading. This loading technique, coupled with a mass spectrometry protocol that minimizes U ionization and removal of bulk U with ion exchange chromatography, allows for single pg-sized aliquots of plutonium (Pu) to be measured without interference from 238U. This technique has the potential to provide complete isotopic characterization of trace amounts of Pu by TIMS, without the need for alpha spectrometry.

Challenges in choice of the treatment strategy for patients with recurrent pseudomyxoma peritonei

Pseudomixoma peritonei is a rare type of peritoneal carcinomatosis demonstrating an indolent course and a high rate of recurrence. primary surgical interventions in patients with pseudomixoma peritonei are extensive and traumatic, which worsens the chances for performing re-operation and may increase the rate of postoperative complications. above mentioned circumstances forms a problem in the choice of management for patients with recurrent pseudomyxoma peritonei. in this article we present a clinical case of successful treatment of recurrent disease.Сlinical case. The 62 years female patient in 2006 first noticed pain in the lower abdomen. the examination revealed a tumor near the right appendages. on 28.12.2006 the uterus was extirpated with appendages, appendectomy, resection of the large omentum; 6 courses of chemotherapy (cap) were conducted. in may 2007 and June 2009, repeated cytoreductive operations were performed with subsequent 12 courses of chemotherapy. in 2012 a patient with a relapse of the disease was re-operated at the N.N. Blokhin NmRcof oncology. Re-operation was performed in the volume of removal of bulk of the tumor in the right and left sub-diaphragmatic spaces with resection of both domes of the diaphragm, splenectomy, removal of the remaining part of the large omentum, with subsequent hyperthermic intraperitoneal chemoperfusion with cisplatin. complications were not noted. after 14 months, ctand ultrasound revealed progression of the disease. in 2013 an attempt was made to re-surgical intervention. during re-operation in the abdominal cavity a massive adhesive process was found. given the palliative nature of the intervention and the high risk of progression, the volume of surgery is limited to a biopsy of the tumor mass. later 4 courses of chemotherapy were conducted. during period of follow-up, relapse of tumor was noted with the development of partial small intestinal obstruction, which did not require emergency intervention. at present, 26 months after the combined treatment, the patient’s condition is satisfactory, with no signs of intestinal obstruction.Сonclusion. Performance repeated surgical interventions for pseudomixoma peritonei is a rather difficult task for, due to the fact that with continued growth, it is more difficult to achieve optimal cytoreduction. the basic condition for re-operation should be referred to the initial optimal level of cytoreduction and a long-term disease-free period.

Treatment of glioblastoma in adults.

The diagnosis of a glioblastoma is mainly made on the basis of their microscopic appearance with the additional determination of epigenetic as well as mutational analyses as deemed appropriate and taken into account in different centers. How far the recent discovery of tumor networks will stimulate novel treatments is a subject of intensive research. A tissue diagnosis is the mainstay. Regardless of age, patients should undergo a maximal safe resection. Magnetic resonance imaging is the surrogate parameter of choice for follow up. Patients should receive chemoradiotherapy with temozolomide with the radiation schedule adapted to performance status, age and tumor location. The use of temozolomide may be reconsidered according to methylguanine DNA methyltransferase (MGMT) promoter methylation status; patients with an active promoter may be subjected to a trial or further molecular work-up in order to potentially replace temozolomide; patients with an inactive (hypermethylated) MGMT promoter may be counseled for the co-treatment with the methylating and alkylating compound lomustine in addition to temozolomide. Tumor-treating fields are an additive option independent of the MGMT status. Determination of recurrence is still challenging. Patients with clinical or radiographic confirmed progression should be counseled for a second surgical intervention, that is, to reach another macroscopic removal of the tumor bulk or to obtain tissue for an updated molecular analysis. Immune therapeutic approaches may be dependent on tumor types and molecular signatures. In newly diagnosed and recurrent glioblastoma, bevacizumab prolongs progression-free survival without affecting overall survival in an unselected population of glioblastoma patients. Whether or not selection can be made on the basis of molecular or imaging parameters remains to be determined. Some patients may benefit from a second radiotherapy. In our view, the near future will provide support for translating the amazing progress in understanding the molecular background of glioblastoma in to more complex, but promising therapy concepts

Semi-autonomous image-guided brain tumour resection using an integrated robotic system: A bench-top study.

Complete brain tumour resection is an extremely critical factor for patients' survival rate and long-term quality of life. This paper introduces a prototype medical robotic system that aims to automatically detect and clean up brain tumour residues after the removal of tumour bulk through conventional surgery. We focus on the development of an integrated surgical robotic system for image-guided robotic brain surgery. The Behavior Tree framework is explored to coordinate cross-platform medical subtasks. The integrated system was tested on a simulated laboratory platform. Results and performance indicate the feasibility of supervised semi-automation for residual brain tumour ablation in a simulated surgical cavity with sub-millimetre accuracy. The modularity in the control architecture allows straightforward integration of further medical devices. This work presents a semi-automated laboratory setup, simulating an intraoperative robotic neurosurgical procedure with real-time endoscopic image guidance and provides a foundation for the future transition from engineering approaches to clinical application.

N‐Aryl‐9,10‐phenanthreneimines as Scaffolds for Exploring Noncovalent Interactions: A Structural and Computational Study

A series of 10‐[(4‐halo‐2,6‐diisopropylphenyl)imino]phenanthren‐9‐ones and derivatives of the phenanthrene‐9,10‐dione ligand have been synthesised and structurally characterised to explore two types of noncovalent interactions, namely the influence of the steric bulk upon the resulting C–H···π and π‐stacking interactions and halogen bonding. Selected noncovalent interactions have additionally been analysed by DFT and AIM techniques. No halogen bonding has been observed in these systems, but X lone pair···π, C–H···O=C and C–H···π interactions are the prevalent ones in the halogenated systems. Removal of the steric bulk in N‐(2,4,6‐trimethylphenyl)‐9,10‐iminophenanthrenequinone affords different noncovalent interactions, but the C–H···O=C hydrogen bonds are observed. Surprisingly, in N‐(2,6‐dimethylphenyl)‐9,10‐iminophenanthrenequinone and N‐(phenyl)‐9,10‐iminophenanthrenequinone these C–H···O=C hydrogen bonds are not observed. However, they are observed in the related 2,6‐di‐tert‐butylphenanthrene‐9,10‐dione. The π‐interactions in dimers extracted from the crystal structures have been analysed by DFT and AIM. Spectroscopic investigations are also presented and these show only small perturbations to the O=C–C=N fragment.

The added value of hysterectomy in the management of gestational trophoblastic neoplasia

BackgroundDespite the undoubted effectiveness of chemotherapeutic treatment in gestational trophoblastic neoplasia (GTN), problems related to toxicity of chemotherapy and chemo-resistant disease have led to reconsideration of the use of hysterectomy. Aim of the present study was to evaluate indications for and outcome of hysterectomy in patients with GTN in a nation-wide cohort. MethodsBetween 1977 and 2012, we identified all patients diagnosed with GTN and treated with hysterectomy from the Dutch national databases. Demographics, clinical characteristics and follow-up were recorded retrospectively. ResultsOne hundred and nine patients (16.5% of all registered patients with GTN) underwent hysterectomy as part of their management for GTN. The majority of patients was classified as low-risk disease (74.3%), post-molar GTN (73.5%) and disease confined to the uterus (65.1%). After hysterectomy, complete remission was achieved in 66.2% of patients with localized disease and in 15.8% of patients with metastatic disease. For patients with localized disease, treated with primary hysterectomy, treatment duration was significantly shorter (mean 3.2weeks and 8.0weeks respectively, p=0.01) with lower number of administered chemotherapy cycles (mean 1.5 and 5.8 respectively, p<0.01) than patients in a matched control group. ConclusionIn selected cases, a hysterectomy may be an effective means to either reduce or eliminate tumor bulk. Primary hysterectomy should mainly be considered in older patients with localized disease and no desire to preserve fertility, whereas patients with chemotherapy-resistant disease may benefit from additional hysterectomy, especially when disease is localized. For patients with widespread metastatic disease, the benefit of hysterectomy lies in the removal of chemotherapy-resistant tumor bulk with subsequent effect on survival.

Citric Acid as a Complexing Agent in Chemical Mechanical Polishing Slurries for Cobalt Films for Interconnect Applications

A colloidal silica-based slurry (3–10 wt%) containing H2O2 (1 wt%) and citric acid (50 mM) was found to polish chemical vapor-deposited (CVD) cobalt (Co) films with removal rates (RRs) of ∼180–500 nm/min and a dissolution rate (DR) of ∼0 nm/min at pH 8 along with an RMS roughness of ∼0.5 nm and a corrosion current of ∼50 μA/cm2. Our results suggest that, in the presence of H2O2, the Co film surface was covered with a passive film of CoO in acidic conditions and Co3O4 in alkaline conditions. However, in the presence of H2O2 and citric acid in acidic conditions, formation of the soluble complex [Co(C6H5O7)2]3− from abraded Co enhanced the RRs significantly. The roles of H2O2, citric acid, and silica abrasives as well as the pH on the Co material removal process are discussed and a removal mechanism is proposed. Two inhibitors namely, 1, 2, 4- Triazole (TAZ) and Benzotriazole (BTA), were tested in the presence of 50 mM citric acid at pH 8 but were found to be ineffective even at concentrations of 100 mM in reducing the ΔEcorr of Co-Ti couple to minimize galvanic corrosion that is essential when the Co/Ti structure is polished after the removal of bulk of Co and requires further study.

Antioxidative Theranostic Iron Oxide Nanoparticles toward Brain Tumors Imaging and ROS Production

Gliomas are the most common primary brain tumor in humans. To date, the only treatment of care consists of surgical removal of the tumor bulk, irradiation, and chemotherapy, finally resulting in a very poor prognosis due to the lack of efficiency in diagnostics. In this context, nanomedicine combining both diagnostic and magnetic resonance imaging (MRI) and therapeutic applications is a relevant strategy referred to theranostic. Magnetic nanoparticles (NP) are excellent MRI contrast agents because of their large magnetic moment, which induces high transverse relaxivity (r2) characteristic and increased susceptibility effect (T2*). NP can be also used for drug delivery by coating their surface with therapeutic molecules. Preliminary in vitro studies show the high potential of caffeic acid (CA), a natural polyphenol, as a promising anticancer drug due to its antioxidant, anti-inflammatory, and antimetastatic properties. In this study, the antioxidative properties of iron oxide NP functionalized with caffeic acid (γFe2O3@CA NP) are investigated in vitro on U87-MG brain cancer cell lines. After intravenous injection of these NP in mice bearing a U87 glioblastoma, a negative contrast enhancement was specifically observed on 11.7 T MRI images in cancerous tissue, demonstrating a passive targeting of the tumor with these nanoplatforms.

Impact of Extended Primary Surgery on Suboptimally Operable Patients With Advanced Ovarian Cancer.

Extensive surgical efforts to achieve an optimal debulking (no residual tumor) in primary surgery of ovarian cancer are today's criterion standard in gyneco-oncologic surgery. However, it is controversial whether extensive surgery, including resections of metastases in the upper abdomen and bowel resections, is justifiable in patients with not completely operable lesions. All patients who had undergone surgery for ovarian cancer in the years 2002 to 2013 at our institution were viewed (n = 472). We retrospectively identified 278 operations for primary ovarian cancer. Ninety-six (35%) of the 278 patients showed postoperative tumor residuals and were included in this study. Fifty-five (57%) of 96 patients underwent bowel resection, showing significantly higher complication rates (64% vs 39% minor complications, P = 0.017; 31% vs 9.8% severe complications, P = 0.013) compared with patients without bowel resections as well as no improvement in progression-free or overall survival (median overall survival, 19.5 vs 32.9; P = 0.382). Multiple anastomoses (≥2) were associated with higher rates for anastomotic leakage (16.7% vs 2.6%, P = 0.02) and a higher mortality (16.7% vs 0%, P = 0.04) compared with patients with only 1 anastomosis. Extensive surgery of the upper abdomen was not associated with a significant increase in complication rates. Because of the increased morbidity of bowel resections without any evidence for improvement of survival, we suggest to restrain from further resection of intestines if an optimal debulking seems not feasible after removal of the major tumor bulk.

Synergy between two natural gas sweetening processes

Merox process is a developed process for natural gas sweetening. However this process has one main disadvantage, which is the fact that carbon dioxide in the feed gas consumes the sorbent solution. High efficiency of carbonate based solutions for removal of bulk of CO2 from natural gas is a well-known fact. The alkalinity is important in removal of acid gases by potassium carbonate solution. The main idea behind this work was to investigate the possibility of inhibition of Merox solution consumption by a synergy between Merox and carbonate based sweetening processes. In this study, a carbonate based sweetening process is simulated using Aspen Plus simulator for sweetening the natural gas produced in one of gas fields located in Iran. The effects of addition of sodium hydroxide to the solution on the gas sweetening performance and efficiency are investigated. It is revealed that modifying the solution of this process using sodium hydroxide increases the capacity of the solution in removing acid gases.

A Novel Treatment System to Remove Phosphorus from Liquid Manure

Abstract. Lowering the phosphorus (P) content of animal manure is one approach of addressing concerns over surplus P accumulation in soils resulting from land application of animal manure. We sought to develop a treatment system for liquid manures that conserves manure nitrogen (N) while removing most of the manure P. Initial evaluation of a treatment system involving manure solid separation and precipitation of dissolved P with an alkaline salt (Ca(OH)2) resulted in poor liquid/solid separation and poor dissolved P removal and created conditions promoting ammonia-N (NH3-N) volatilization. As a result, we developed a three-stage system with iterative solid removal and acid salt (ferric sulfate – Fe2(SO4)3) sorption of dissolved P: (1) removal of bulk and intermediate sized solids (>25 μm); (2) chemical treatment to convert dissolved P; and (3) final removal of fine solids and chemically sorbed P. When tested on manure slurries from 150 and 2700 cow dairies, 96% to 99% aqua regia extractable P was removed along with 92% to 94% of the solids, resulting in liquid manure filtrates with N:P ratios greater than 19:1. While costs of treatment were roughly $38 kg-1 P removed, equivalent to $750 cow-1 yr-1, we anticipate that refinement of the process and beneficial uses of the solid materials (bedding, compost, etc.) will improve cost-efficacy considerably.

Novel scrubbing system for post-combustion CO2 capture and recovery: Experimental studies

Power plant emissions of flue gas to the atmosphere releases considerable CO2 which is considered to be the main contributor to global warming. Several gas absorption techniques are being investigated to reduce the capital and operating costs for CO2 capture from post-combustion flue gas. Conventional method of CO2 capture by an aqueous solution of monoethanolamine (MEA) and its subsequent stripping in a separate tower with steam at 120°C is highly energy intensive. The low partial pressure of CO2 in the flue gas inhibits the application of CO2-selective membranes unless methods are employed to increase the CO2 partial pressure in the flue gas to be treated. An absorption–stripping technique to potentially bypass the shortcomings of many existing approaches is described here. Bench-scale CO2 capture and recovery from simulated flue gas with and without moisture was demonstrated using an advanced hollow fiber membrane contactor. This was achieved by the use of a novel non-volatile absorbent, consisting of the ionic liquid [bmim][DCA] containing 20wt% polyamidoamine (PAMAM) dendrimer Gen 0. We have employed a simulated humidified flue gas containing around 14% CO2 and demonstrated successful removal of bulk of the CO2 and its recovery in a CO2-concentrated stream; the CO2 concentration achieved in the stripper out stream was ~92vol%. An estimate of the overall volumetric mass transfer coefficient (Kla) for the current CO2-IL-PAMAM Gen 0 system has been obtained.

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There are 2 major issues related to the treatment of large bladder tumors: the often difficult to find small size satellite or concomitant lesion (usually Stage pTa and carcinoma in situ) and the sometimes challenging endoscopic removal of the large size tumor bulk. Editorial CommentUrologyVol. 79Issue 4PreviewUrologists are interested in improving the detection and transurethral resection (TUR) of nonmuscle-invasive bladder tumors. The aim is to achieve better staging, derive rational treatments, and improve local surgical control to reduce the frequency of tumor recurrence and disease progression. Toward this end, the authors have studied narrow band imaging (NBI) cystoscopy coupled with bipolar plasma vaporization (BPV) for large bladder tumors in a randomized clinical trial. Compared with conventional TUR using white light cystoscopy, the combined surgical method reduced the residual tumor detection on repeat TUR from 17.5% to 6.7% and the 1-year tumor recurrence rate from 17.8% to 7.9%. Full-Text PDF

Hydrothermolysis of brown coal in cyclic pressurization–depressurization mode

The new technique of usage of supercritical water (SCW) for brown coals conversion into both liquid (condensed), and solid and gas (volatile) fuels is proposed. The method consists in cyclic filling of SCW up to the given pressure (pressurization) into the tubular reactor, filled with coal particles, and fast discharging of conversion products dissolved in SCW (depressurization). The dynamics and composition of conversion products in a mode of stepwise temperature (310–460°C) and pressure (9–31MPa) rise at cyclic filling and discharging of, first, the water vapor (T<374°C), and then of SCW have been investigated. The vapor stage of conversion has prevented agglomeration of coal particles at the stage of SCW conversion. The maximum yield of the condensed products is obtained at 390°C, 29.0MPa. High heating value of combustible products of conversion and solid residue appeared to be much more than that of initial coal because of removal of a great bulk (up to 85.2%) of native oxygen as CO2. H/C atomic ratio in the volatile combustible and condensed products is much higher than in the conversion residue because of redistribution of native hydrogen in coal organic matter (COM). It has been established that sulfur is mainly removed from COM as H2S (up to 77.2%) and nitrogen is concentrated (up to 67.2%) in the solid conversion residue.

Identification of putative residues involved in the accessibility of the substrate-binding site of lipoxygenase by site-directed mutagenesis studies

Lipoxygenases (LOXs) are a class of widespread dioxygenases catalyzing the hydroperoxidation of polyunsaturated fatty acids (PUFA). Recently, we isolated a cDNA encoding a LOX, named olive LOX1, from olive fruit of which the deduced amino acid sequence shows more than 50% identity with plant LOXs. In the present study, a model of olive LOX1 based on the crystal structure of soybean LOX-1 as template has been generated and two bulky amino acid residues highly conserved in LOXs (Phe277) and in plant LOXs (Tyr280), located at the putative entrance of catalytic site were identified. These residues may perturb accessibility of the substrate-binding site and therefore were substituted by less space-filling residues. Kinetic studies using linoleic and linolenic acids as substrates were carried out on wild type and mutants. The results show that the removal of steric bulk at the entrance of the catalytic site induces an increase of substrate affinity and of catalytic efficiency, and demonstrate that penetration of substrates into active site of olive LOX1 requires the movement of the side chains of the Phe277 and Tyr280 residues. This study suggests the involvement of these residues in the accessibility of the substrate-binding site in the lipoxygenase family.