RESUMEN

In present study a cylindrical module is studied based on air gap membrane distillation configuration and studied for desalination purpose. A complete theoretical model was developed with consideration of design and operating parameters that enabled a Cylindrical Air Gap Membrane Distillation (CAGMD) module specific performance analysis. Theoretical model was verified with the literature as well as with the experimental results carried out on a lab scale CAGMD module. The effect of support nets which supports the membrane on the air gap side is also discussed on the performance. Support nets made up of four different thermal conductivities material- copper, aluminum, brass and polypropylene (PP) are considered for this study. The effect of feed temperature and flow rate, air gap width, cold flow rate, effect of thermal conductivities of support nets and height of the module was studied on the performance of CAGMD module. Permeate flux, Specific Thermal Energy Consumption (STEC) and the Gained output ratio (GOR) was selected as the performance indicators and the results for all the resulted parameters obtained from experimental and theoretical model falls in good agreement with only 6% deviation, that suggests that the proposed model is best suitable for predicting the behavior of any cylindrical AGMD module with great effectiveness. It is suggested that for better performance of the system feed flow rate, temperature and cold flow rate should be maintained at higher level. Maximum permeate flux achieved from the CAGMD module is 9.22 kg/m2h.

Asunto(s)

RESUMEN

Glycerol (electrochemical) oxidation reaction (GOR) producing organic small molecule acid and coupling with hydrogen evolution reaction is a critical aspect of ensuring balanced glycerol capacity and promoting hydrogen generation on a large scale. However, the development of highly efficient and selective non-noble metal-based GOR electrocatalysts is still a key problem. Here, an S-doped CuO nanorod array catalyst (S-CuO/CF) constructed by sulfur leaching and oxidative remodeling is used to drive GOR at low potentials: It requires potentials of only 1.23 and 1.33 V versus RHE to provide currents of 100 and 500 mA cm-2, respectively. Moreover, it shows satisfactory comprehensive performance (at 100 mA cm-2, Vcell = 1.37 V) when assembled as the anode in asymmetric coupled electrolytic cell. Furthermore, we propose a detailed cycle reaction pathway (in alkaline environment) of S-doped CuO surface promoting GOR to produce formic acid and glycolic acid. Among them, the C-C bond breaking and lattice oxygen deintercalation steps frequently involved in the reaction pathway are the key factors to determine the catalytic performance and product selectivity. This research provides valuable guidance for the development of transition metal-based electrocatalysts for GOR and valuable insights into the glycerol oxidation cycle reaction pathway.

RESUMEN

This paper presents a comparative performance study of single-stage desalination processes with major configurations of membrane distillation (MD) modules. MD modules covered in this study are (a) direct contact MD (DCMD), (b) vacuum MD (VMD), (c) sweeping gas MD (SGMD), and (d) air gap MD (AGMD). MD-based desalination processes are simulated with rigorous theoretical MD models supported by molecular thermodynamic property models for the accurate calculation of performance metrics. The performance metrics considered in MD systems are permeate flux and energy efficiency, i.e., gained output ratio (GOR). A general criterion is established to determine the critical length of these four MDs (at fixed width) for the feasible operation of desalination in a wide range of feed salinities. The length of DCMD and VMD is restricted by the feed salinity and permeate flux, respectively, while relatively large AGMD and SGMD are allowed. The sensitivity of GOR flux with respect to permeate conditions is investigated for different MD configurations. AGMD outperforms other configurations in terms of energy efficiency, while VMD reveals the highest permeate production. With larger MD modules, utilization of thermal energy supplied by the hot feed for evaporation is in the order of VMD > AGMD > SGMD > DCMD. Simulation results highlight that energy efficiency of the overall desalination process relies on the efficient recovery of spent for evaporation, suggesting potential improvement in energy efficiency for VMD-based desalination.

RESUMEN

Apyrase from potato (Solanum tuberosum) is a divalent metal ion-dependent enzyme that catalyzes the hydrolysis of nucleoside di- and tri-phosphates with broad substrate specificity. The enzyme is widely used to manipulate nucleotide levels such as in the G protein-coupled receptor (GPCR) field where it is used to deplete guanine nucleotides to stabilize nucleotide-free ternary agonist-GPCR-G protein complexes. Potato apyrase is available commercially as the native enzyme purified from potatoes or as a recombinant protein, but these are prohibitively expensive for some research applications. Here, we report a relatively simple method for the bacterial production of soluble, active potato apyrase. Apyrase has several disulfide bonds, so we co-expressed the enzyme bearing a C-terminal (His)6 tag with the E. coli disulfide isomerase DsbC at low temperature (18 °C) in the oxidizing cytoplasm of E. coli Origami B (DE3). This allowed low level production of soluble apyrase. A two-step purification procedure involving Ni-affinity followed by Cibacron Blue-affinity chromatography yielded highly purified apyrase at a level of ∼0.5 mg per L of bacterial culture. The purified enzyme was functional for ATP hydrolysis in an ATPase assay and for GTP/GDP hydrolysis in a GPCR-G protein coupling assay. This methodology enables the time- and cost-efficient production of recombinant apyrase for various research applications.

Asunto(s)

RESUMEN

Oil rim reservoirs with very large gas caps, strong aquifers, and pay thickness below 30 ft. pose oil production challenges to operators. With best operational practices, very high gas oil ratios are recorded at the initial onset of oil production, thus such reservoirs are subjected to a gas cap blow down leading to an ultimate loss in oil reserves. This loss is attributed to a rapid and drastic drop in pressure over the productive life of the reservoir. To maximize oil production, a simulation study is focused on initiating oil wells at different time intervals and estimating oil recoveries at these points. It is believed that the gas cap would have been blown down in time to accommodate for substantial oil production. This study presents the reservoir data (from the Niger-Delta) that can be incorporated in a black oil reservoir simulator (Eclipse) coupled with best production and optimization strategies (water and gas injection) for maximum oil production during gas cap blow down. The data presented will provide a detailed process developing an oil rim synthetic model, support and enhance further studies in optimizing oil production in oil rims subjected to gas cap blow down, create a template for secondary and enhanced oil recovery processes.

RESUMEN

The aim of this prospective, non-randomized study was to evaluate the effect of nine different premedication medications on the incidence of gastroesophageal reflux (GOR) in anesthetized dogs. Two hundred and seventy dogs undergoing non-intrathoracic, non-intrabdominal elective surgeries or invasive diagnostic procedures were included in the study, and were allocated into nine groups (30 dogs/group) defined by the type of premedication administered. Premedication consisted of dexmedetomidine with either morphine, pethidine or butorphanol, acepromazine with either one of the three opioids or midazolam with one of the above-mentioned opioids. Anesthesia was induced with propofol and maintained with isoflurane in oxygen. Esophageal pH was measured with the use of a pH-meter electrode and a pH-value less than 4 and over 7.5 was considered to be GOR. The study revealed that 119/270 (44.1%) dogs experienced a reflux episode during anesthesia. The incidence of reflux did not differ among groups (p = 0.117). In group AB the dogs refluxed within 10 min of the beginning of pH-measurements, in comparison with group DB in which dogs refluxed within 30 min (p = 0.029). Invasive diagnostic procedures had a lower incidence of GOR in comparison to castrations (p = 0.09). The outcome of the study suggests that none of the opioids used increased the incidence of GOR in anesthetized dogs.

RESUMEN

BACKGROUND: In epilepsy surgery for cavernoma with intractable focal epilepsy, removal of the cavernoma with its surrounding hemosiderin deposition and other extended epileptogenic zone has been shown to improve postsurgical seizures. However, there has been no significant association between such an epileptogenic zone and intraoperative electrocorticography (ECoG) findings. The authors recently demonstrated that high regular gamma oscillation (30-70 Hz) regularity (GOR) significantly correlates with epileptogenicity. OBSERVATIONS: The authors evaluated the utility of intraoperative GOR analysis in epilepsy surgery for cavernomas. The authors also analyzed intraoperative ECoG data from 6 patients with cavernomas. The GOR was calculated using a sample entropy algorithm. In 4 patients, the GOR was significantly high in the area with the pathological hemosiderin deposition. In 2 patients with temporal cavernoma, the GOR was significantly high in both the hippocampus and the area with the pathological hemosiderin deposition. ECoG showed no obvious epileptic waveforms in 3 patients, whereas extensive spikes were observed in 3 patients. All patients underwent cavernoma removal plus resection of the area with significantly high GOR. The 2 patients with temporal cavernomas underwent additional hippocampal transection. All patients were seizure free after surgery. LESSONS: The high GOR may be a novel intraoperative marker of the epileptogenic zone in epilepsy surgery for cavernomas.

RESUMEN

This study aimed to investigate the effect of three different preoperative fasting regimens on the incidence of gastro-oesophageal reflux (GOR) in dogs under general anaesthesia. Ninety dogs undergoing non-abdominal and non-thoracic elective surgery were included in the study and equally allocated to three groups. Dogs received canned food providing half the daily resting energy requirements (RER) 3 h prior to premedication (group 3H), a quarter of the daily RER 3 h before premedication (group 3Q), and half the daily RER 12 h before premedication (group 12H). The animals were premedicated with acepromazine and pethidine, anaesthesia was induced with propofol and maintained with isoflurane vaporised in oxygen. Oesophageal pH was monitored throughout anaesthesia. Demographic and surgery-related parameters were not different among groups. The incidence of GOR was 11/30 in group 3H (36.7%), 9/30 in group 3Q (30.0%) and 5/30 in group 12H (16.7%), which was not statistically different (p = 0.262). Reduction of the amount of the preoperative meal from half to a quarter of the daily RER did not reduce the incidence of GOR but resulted in a lower oesophageal pH (p = 0.003). The results of this study suggest that the administration of a meal 3 h before anaesthesia does not have any beneficial effect in the reduction of GOR incidence in dogs compared to the administration of a meal 12 h before anaesthesia.

RESUMEN

Non-specific symptoms such as irritability, vomiting, and back arching during the infant period are often attributed to gastroesophageal reflux. While numerous studies have shown no significant benefit to the use of acid suppressant medications in this population, these medications are frequently prescribed in response to these symptoms. Our goals were to understand how often children were being prescribed this medication. To do this, data was extracted from a national database for reimbursement of prescribed medications through the General Medical Services scheme (GMS). Infants aged less than 1 year and eligible for reimbursement under GMS were included for analysis. A total of 450 infants per 10,000 eligible population received an anti-reflux preparation from the following drug classes (H2 antagonists, proton pump inhibitors, or alginate preparations) in 2018. This is compared with that in 2009 where only 137 per 10,000 eligible infants received these medications. This increase was predominantly attributable to an increase in ranitidine prescriptions.Conclusion: Despite a change in clinical guidelines, anti-reflux preparations are increasingly being prescribed to infants aged less than 1 year. The reasons behind the increase in prescriptions containing these medications cannot be ascertained from this data. This may suggest a proportion of these prescriptions may be unwarranted in this population. What is Known: • The prescription of PPIs in infants has increased in a number of countries. • Use of anti-reflux medications has a very poor evidence base in infancy. What is New: • This data focuses only on an infant age group in a "well" cohort. • Ranitidine may contribute to increased acid-suppressant use in infancy.

Asunto(s)

RESUMEN

Brine disposal is a major drawback for seawater desalination. Membrane distillation (MD) is an emerging technology to treat a high saline water including brine disposal instead of reverse osmosis, multi-stage flash and multi-effect distillation. This study investigated a pilot scale of a spiral-wound air gap MD (AGMD) module and evaluated its efficiency. A pilot-scale AGMD module with design production capacity of 10 m3/d was operated. Experiments with varying flow velocity showed increasing trend of water vapor flux as flow velocity increases. The temperature is one of the significant points in maximizing water permeate vapor flux in MD. Increasing temperature from 65 °C to 75 °C in evaporator channel has increased flux from 0.59 to 1.15 L/m2/h. Under various conditions, specific thermal energy consumption (STEC) and gained output ratio (GOR) was used to analyze energy efficiency. The pilot plant showed high GOR value in spite of a limited heating and cooling source available at the site. The highest GOR achieved was 3.54 with STEC of 182.78 kWh/m3. This study provides an overview of operation experience and its data analysis related to temperature, concentration, flow rate and energy supply.

Asunto(s)

RESUMEN

Trace element concentrations in the youngest Holocene sedimentary archives, historical mining, and archaeological sites are reliable indicators for historical anthropogenic contamination. The Pleistocene-Holocene strata and the overlying archaeological sites of the Peshawar Basin, NW Pakistan provide sedimentary archives to explore historical anthropogenic controls on the distributions of trace elements. The basin with 2500 y of human civilization was sampled using archaeological trenches at Gor Khuttree and Hund, and six sections of youngest Pleistocene-Holocene strata along river banks. Geochemical analysis of high-resolution samples were conducted for both the lacustrine-floodplain sediments and archaeological sites. Results from various horizons of the archaeological sites provide signals for anthropogenic control on the distribution of As, Zn, Cu, Mo, Pb, Hg, Ag, and Au during the Meghalayan Stage of Holocene that gain progressive strength since the 18th century. The geochemical proxies negate direct mining of Cu-Pb and Zn in the area. The consistent, anthropogenic Ag and Au contribution to the system throughout the basin's archaeological history is a significant finding. When correlated against the anthropogenic mercury contamination, it appears that Hund was a major silver-gold panning site throughout its known history whereas Gor Khuttree was the major silver-gold processing center. The Peshawar Basin anthropogenic signals contribute to widespread European early Anthropocene signals at around 2000 BP related to the Greek and Roman mining. Signals during the Hindu Shahi period correlate well with the Medieval period mining and smelting peak signals observed in Europe and China. Hg, Ag, and Au concentrations in the area since the start of the 19th century CE correlates to the start of industrialisation. During the mid-20th century, these geochemical signals from the Gor Khuttree reflect anthropogenic contributions to the local system and correlate to the suggested base of a formalised Anthropocene.

RESUMEN

Cadmium (Cd) is a heavy metal that is extremely toxic to many organisms; however, microbes are highly adaptable to extreme conditions, including heavy metal contamination. Bacteria can evolve in the natural environment, generating resistant strains that can be studied to understand heavy-metal resistance mechanisms, but obtaining such adaptive strains usually takes a long time. In this study, the genome replication engineering assisted continuous evolution (GREACE) method was used to accelerate the evolutionary rate of the Escherichia coli genome to screen for E. coli mutants with high resistance to cadmium. As a result, a mutant (8mM-CRAA) with a minimum inhibitory concentration (MIC) of 8 mM cadmium was generated; this MIC value was approximately eightfold higher than that of the E. coli BL21(DE3) wild-type strain. Sequencing revealed 329 single nucleotide polymorphisms (SNPs) in the genome of the E. coli mutant 8mM-CRAA. These SNPs as well as RNA-Seq data on gene expression induced by cadmium were used to analyze the genes related to cadmium resistance. Overexpression, knockout and mutation of the htpX (which encodes an integral membrane heat shock protein) and gor (which encodes glutathione reductase) genes revealed that these two genes contribute positively to cadmium resistance in E. coli. Therefore, in addition to the previously identified cadmium resistance genes zntA and capB, many other genes are also involved in bacterial cadmium resistance. This study assists us in understanding the mechanism of microbial cadmium resistance and facilitating the application of heavy-metal remediation.

RESUMEN

INTRODUCTION: Arachnoid cysts (ACs) account for a small proportion of all intracranial lesions. They are often incidental but can become symptomatic and even cause a threat to life. Symptoms are usually due to direct compression of neural elements and/or raised intracranial pressure. CASE REPORT: We report the case of an infant with an enlarging posterior fossa arachnoid cyst (PFAC) causing torticollis and gastro-oesophageal reflux (GOR), the combination of which had been previously unreported in this context. Endoscopic fenestration and cyst decompression were followed by complete resolution of the symptoms. We discuss the possible mechanisms of torticollis and GOR in this context.

Asunto(s)

RESUMEN

BACKGROUND: Gastro-oesophageal reflux (GOR) is common in infants. When the condition causes pathological symptoms and/or complications it is considered gastro-oesophageal reflux disease (GORD). It appears to be increasingly diagnosed and causes great distress in the first year of infancy. In New South Wales (NSW), residential parenting services support families with early parenting difficulties. These services report a large number of babies admitted with a label of GOR/GORD. The aim of this study was to explore the maternal and infant characteristics, obstetric interventions, and reasons for clinical reporting of GOR/GORD in NSW in the first 12 months following birth (2000-2011). METHODS: A three phase, mixed method sequential design was used. Phase 1 included a linked data population based study (n = 869,188 admitted babies). Phase 2 included a random audit of 326 medical records from admissions to residential parenting centres in NSW (2013). Phase 3 included eight focus groups undertaken with 45 nurses and doctors working in residential parenting centres in NSW. RESULTS: There were a total of 1,156,020 admissions recorded of babies in the first year following birth, with 11,513 containing a diagnostic code for GOR/GORD (1% of infants admitted to hospitals in the first 12 months following birth). Babies with GOR/GORD were also more likely to be admitted with other disorders such as feeding difficulties, sleep problems, and excessive crying. The mothers of babies admitted with a diagnostic code of GOR/GORD were more likely to be primiparous, Australian born, give birth in a private hospital and have: a psychiatric condition; a preterm or early term infant (37-or-38 weeks); a caesarean section; an admission of the baby to SCN/NICU; and a male infant. Thirty six percent of infants admitted to residential parenting centres in NSW had been given a diagnosis of GOR/GORD. Focus group data revealed two themes: "It is over diagnosed" and "A medical label is a quick fix, but what else could be going on?" CONCLUSIONS: Mothers with a mental health disorder are nearly five times as likely to have a baby admitted with GOR/GORD in the first year after birth. We propose a new way of approaching the GOR/GORD issue that considers the impact of early birth (immaturity), disturbance of the microbiome (caesarean section) and mental health (maternal anxiety in particular).

Asunto(s)

RESUMEN

Hydroxybenzylidene hydrazines exhibit a wide spectrum of biological activities. Here, we report synthesis and free radical scavenging activity of nine new N-(hydroxybenzylidene)-N'-[2,6-dinitro-4-(trifluoromethyl)]phenylhydrazines. The chemical structures of these compounds were confirmed by 1H-NMR, 13C-NMR, 19F-NMR, IR spectroscopy, LC-MS, and elemental analysis. The prepared compounds were tested for their activity to scavenge 2,2-diphenyl-1-picrylhydrazyl (DPPH), galvinoxyl radical (GOR), and 2,2'-azino-bis(3-ethylbenzothiazoline)-6-sulphonic acid (ABTS) radicals. The free radical scavenging activity expressed as SC50 values of these compounds varied in a wide range, from a strong to no radical scavenging effect. The most effective radical scavengers were hydroxybenzylidene hydrazines containing three hydroxyl groups in the benzylidene part of their molecules. The prepared compounds were also tested for their activity to inhibit photosynthetic electron transport in spinach chloroplasts. IC50 values of these compounds varied in wide range, from an intermediate to no inhibitory effect.

Asunto(s)

RESUMEN

The GOR is a computer program to predict secondary structures in proteins when the amino acid sequence is known using the theory of information. The program GOR was named much later after publication in 1978 at the dawn of bioinformatics. The program is still distributed. Its development is an example of interplay between scientific friendships, pleasure of doing research, opportunities, new technologies, and lack of the intervention of any grant agencies.

Asunto(s)

RESUMEN

The GOR method of protein secondary structure prediction is described. The original method was published by Garnier, Osguthorpe, and Robson in 1978 and was one of the first successful methods to predict protein secondary structure from amino acid sequence. The method is based on information theory, and an assumption that information function of a protein chain can be approximated by a sum of information from single residues and pairs of residues. The analysis of frequencies of occurrence of secondary structure for singlets and doublets of residues in a protein database enables prediction of secondary structure for new amino acid sequences. Because of these simple physical assumptions the GOR method has a conceptual advantage over other later developed methods such as PHD, PSIPRED, and others that are based on Machine Learning methods (like Neural Networks), give slightly better predictions, but have a "black box" nature. The GOR method has been continuously improved and modified for 30 years with the last GOR V version published in 2002, and the GOR V server developed in 2005. We discuss here the original GOR method and the GOR V program and the web server. Additionally we discuss new highly interesting and important applications of the GOR method to chameleon sequences in protein folding simulations, and for prediction of protein aggregation propensities. Our preliminary studies show that the GOR method is a promising and efficient alternative to other protein aggregation predicting tools. This shows that the GOR method despite being almost 40 years old is still important and has significant potential in application to new scientific problems.

Asunto(s)

RESUMEN

Predicting the secondary structure of a protein from its sequence still remains a challenging problem. The prediction accuracies remain around 80 %, and for very diverse methods. Using evolutionary information and machine learning algorithms in particular has had the most impact. In this chapter, we will first define secondary structures, then we will review the Consensus Data Mining (CDM) technique based on the robust GOR algorithm and Fragment Database Mining (FDM) approach. GOR V is an empirical method utilizing a sliding window approach to model the secondary structural elements of a protein by making use of generalized evolutionary information. FDM uses data mining from experimental structure fragments, and is able to successfully predict the secondary structure of a protein by combining experimentally determined structural fragments based on sequence similarities of the fragments. The CDM method combines predictions from GOR V and FDM in a hierarchical manner to produce consensus predictions for secondary structure. In other words, if sequence fragment are not available, then it uses GOR V to make the secondary structure prediction. The online server of CDM is available at http://gor.bb.iastate.edu/cdm/ .

Asunto(s)

RESUMEN

A hopeless upper central incisor was subjected to forced eruption before implant substitution to improve and develop the amount of soft tissue. This involved a GBR to insert the implant and a GTR to regenerate the tissue around the dehiscence of the nearby lateral using a "Guided Orthodontic Regeneration" (GOR) approach. The extrusion was performed esthetically in lingual orthodontics. The GOR technique included a Guided Orthodontic "Bone" Regeneration (GOBR) and a Guided Orthodontic "Soft Tissue" Regeneration (GOTR). This developed a 3D implant site while correcting the osseous defects and increasing the amount of soft tissue, which was used for a subsequent regenerative technique.

Asunto(s)

RESUMEN

PURPOSE: Cell-penetrating peptides (CPPs) are used for delivering drugs and other macromolecular cargo into living cells. In this paper, we investigated the relationship between the structural/physicochemical properties of four new synthetic peptides containing arginine-tryptophan in terms of their cell membrane penetration efficiency. METHODS: The peptides were prepared using solid phase synthesis procedure using FMOC protected amino acids. Fluorescence-activated cell sorting and fluorescence imaging were used to evaluate uptake efficiency. Prediction of the peptide secondary structure and estimation of physicochemical properties was performed using the GOR V method and MPEx 3.2 software (Wimley-White scale, helical wheel projection and total hydrophobic moment). RESULTS: Our data showed that the uptake efficiency of peptides with two tryptophans at the C- and N-terminus were significantly higher (about 4-fold) than that of peptides containing three tryptophans at both ends. The distribution of arginine at both ends also increased the uptake efficiency 2.52- and 7.18-fold, compared with arginine distribution at the middle of peptides. CONCLUSION: According to the obtained results the value of transfer free energies of peptides from the aqueous phase to membrane bilayer could be a good predictor for the cellular uptake efficiency of CPPs.