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Design of novel reaction-separation-recycle processes for the production of 4-hydroxybutyl acrylate
No full textTwo chemistry routes are known for 4-hydroxybutyl acrylate production: the direct esterification of acrylic acid with 1,4-butanediol, and the transesterification of methyl acrylate with 1,4-butanediol. However, very scarce information in the literature is available about industrial production, or design and operation of production processes. In this study, we propose three novel reaction–separation–recycle processes for 4-hydroxybutyl acrylate production by direct esterification based on solid catalyst. Use of solid catalysts may avoid well-known issues of the liquid catalysts like recovery and re-use of the catalyst, difficult product recovery and corrosion. Due to the nature of the chemical system and reactions conditions, the chemistry is not 100 % selective towards the acrylate, important amounts of diacrylate by-product being formed. All processes use fixed-bed tubular reactors to perform the reactions and distillation-based equipment to achieve the required separations. While all processes have a similar separation sequence, each has its key particularities: the RSR-A process accepts the loss of reactants due to formation and elimination from the process of the diacrylate, RSR-B converts the diacrylate into its reactants in the esterification reactor, while RSR-C converts the diacrylate in a dedicated hydrolysis reactor. A key element in the separation sequence is the use of pressure-swing distillation to make the difficult split of the alcohol/acrylate/diacrylate ternary mixture. All processes are capital and energy intensive. The economic analysis shows that the RSR-A process has the most favorable economics: a total annualized cost of 2 million /t of product. A control structure for the RSR-C process is presented, the dynamic simulations showing its efficiency in rejecting various disturbances
Rethinking the design of a 2-methoxy-2-methyl-heptane process by unraveling the true thermodynamics and kinetics
No full textAmong other fuel additives - such as MTBE, ETBE, or TAME - 2-methoxy-2-methyl heptane (MMH) can increase the fuel octane number and reduce the CO emission. MMH can be obtained through the exothermal etherification of 2-methyl-1-heptene and methanol. Lately, many researchers have developed more and more efficient processes considering the kinetics corresponding to an endothermal reaction. However, in this work we demonstrate that the reaction is actually quite exothermal, and this has strong impact on the designed process. Also, the vapor-liquid equilibrium data predicted by UNIQUAC model for 2-methoxy-2-methyl heptane and 2-methyl-2-heptanol mixture reveals that product purification is more difficult, and it requires more energy to recover and obtain MMH with high purity. Considering these aspects, the 54.87 ktpy process developed in this paper is more realistic and energy intensive (1.82 kWh/kg MMH), with a TAC of 5.3 M$/year. The controllability of the process is proven for ±20% changes of 2-methoxy-2-methyl-heptane production rate
Pore-Scale Modelling of Fluid-Rock Chemical Interactions in Shale during Hydraulic Fracturing
No full textDuring the hydraulic fracturing process in unconventional shale gas reservoirs, chemical interactions between the hydraulic fracturing fluid (HFF) and the shale rock could result in mineral precipitation and dissolution reactions, potentially influencing the gas transport by dissolving or clogging the fractures. The pore-scale distribution of the minerals, especially the highly reactive ones such as calcite, in the shale matrix can impact the structural evolution of the shale rocks. In the present study, a pore-scale reactive transport model is built to investigate the impact of the pore-scale distribution of calcite on the structural alteration of the shales. The alteration of the shales is caused by the barite precipitation, and the dissolution of calcite and pyrite. The simulation results show that the calcite dissolution leads to a permeability enhancement. The permeability enhancement for the shales with coarser calcite grains is more pronounced than that for the shales with finer grains of calcite. The results also indicate that the extent of the permeability enhancement is even more noticeable if the HFF is injected with a higher velocity. The fluid chemistry analysis indicates that the fluid pH for the shale with the fine grains of calcite is higher than that of the shale with the coarse calcite grains and that the injection of the HFF with a higher flowrate leads to the lower pH values. The calcite dissolution observed in the simulations mainly occurs near the inlet. For the shale with the finer calcite grains, barite precipitation also occurs mostly close to the inlet but for the shale with coarser calcite grains, barite precipitation extends more into the domain. This penetration depth increases when the HFF is injected with a higher velocity. In addition to the effect of the calcite distribution, we also used the pore-scale model to study the effect of the calcite content on the structural evolution of the shales. The results from these simulations showed that a higher calcite content can result in higher pH values, higher permeabilities, and also more barite precipitation in the domain
A Hamiltonian Decomposition for Fast Interior-Point Solvers in Model Predictive Control
No full textOptimal decision-making tools are essential in industry to achieve high performance. One of these tools is model predictive control (MPC),which is an advanced control technique that generates an action that affects the controlled variables, while satisfying the process’ operationalconstraints. At the core of the MPC algorithm lies an optimization problem that is solved by a numerical method at every sample time.New demand for more self-contained modular processes has seen MPC embedded in small-scale platforms. This has prompted a needfor custom-made numerical methods that help to run the computationally demanding optimization algorithms efficiently. In this paper, wepropose two approaches that factorize the Newton system of the interior-point method based on the two-point boundary-value problemstructure, rarely explored in MPC. Exploiting the Hamiltonian form of the augmented system, we derive an incomplete LU factorization.A direct method is available to compute the solution of the system using a forward substitution of a series of matrices. We also proposea preconditioned Krylov method that converges within a small number of iterations only depending on the number of states
Regenerative Potential of Hydrogels for Intracerebral Hemorrhage: Lessons from Ischemic Stroke and Traumatic Brain Injury Research
No full textIntracerebral hemorrhage (ICH) is a deadly and debilitating type of stroke, caused by the rupture of cerebral blood vessels. To date, there are no restorative interventions approved for use in ICH patients, highlighting a critical unmet need. ICH shares some pathological features with other acute brain injuries such as ischemic stroke (IS) and traumatic brain injury (TBI), including the loss of brain tissue, disruption of the blood-brain barrier, and activation of a potent inflammatory response. New biomaterials such as hydrogels have been recently investigated for their therapeutic benefit in both experimental IS and TBI, owing to their provision of architectural support for damaged brain tissue and ability to deliver cellular and molecular therapies. Conversely, research on the use of hydrogels for ICH therapy is still in its infancy, with very few published reports investigating their therapeutic potential. In this review, we comment on the published use of hydrogels in experimental ICH and describe how approaches reported in the IS and TBI fields may be applied to ICH research to inform the design of future therapies. We also highlight unique aspects of ICH that are distinct from IS and TBI that should be considered when translating biomaterial-based therapies between disease models
Self-harm in children 12 years and younger: characteristics and outcomes based on the Multicentre Study of Self-harm in England
No full textBackground: Very little is known about self-harm in children. We describe the characteristics and outcomes of children under 13 years who presented following self-harm to five hospitals in England.Methods: We included children under 13 years who presented after self-harm to hospitals in the Multicentre Study of Self-harm in England. Information on patients’ characteristics and method of self-harm was available through monitoring of self-harm in the hospitals. Area-level of socioeconomic deprivation was based on the English Index of Multiple Deprivation (IMD).Results: 387 children aged 5-12 years presented to the study hospitals in 2000-2016, 39% of whom were 5-11 years. Boys outnumbered girls 2:1 at 5-10 years. The numbers of boys and girls were similar at age 11, while at 12 years there were 3.8 girls to every boy. The proportion of study children living in neighbourhoods ranked most deprived (43.4%) was twice the national average. 61.5% of children self-poisoned, 50.6% of them by ingesting analgesics. Of children who self-injured, 45.0% self-cut/stabbed, while 28.9% used hanging/asphyxiation. 32% of the children had a repeat hospital presentation for self-harm, 13.5% re-presented within a year. Conclusions: Gender patterns of self-harm until age 11 years are different to those of adolescents, with a male preponderance, especially in 5-10 years, and hanging/suffocation being more common. The frequent use of self-poisoning in this age group highlights the need for public health messages to encourage safer household storage of medicines. Self-harm in children is strongly associated with socioeconomic deprivation; understanding the mechanisms involved could be important in effective prevention
Fibre Surface/Interfacial Engineering on Wearable Electronics
No full textSurface/interfacial engineering is an essential technique to explore the fibre materials properties and fulfil new functionalities. An extensive scope of current physical and chemical treating methods is reviewed here, alongside a variety of real-world applications. Moreover, we also introduce a new surface/interface engineering approach; self-assembly via π–π stacking, which has great potential for the surface modification of fibre materials due to its non-destructive working principle. This review also introduces a new fibre family member, MOF fibres, which show promising candidacy for fibre based wearable electronics. This review advances the understanding of surface/interfacial engineering techniques on fibre materials and will be expected to guide the rational design of future fibre based wearable electronics
First pilot study of extracellular volume MRI measurement in peripheral muscle of systemic sclerosis patients suggests diffuse fibrosis
No full textObjectives Peripheral muscle involvement in systemic sclerosis may comprise myositis or a non-inflammatory myopathy. There is little understanding on the nature of SSc myopathy. This pilot study aimed to evaluate for the presence of diffuse fibrosis in the peripheral muscle of patients with SSc by determining extracellular volume (ECV) MRI measurement. Methods SSc patients, with suspected myopathy or no muscle involvement, and healthy volunteers (HV) had native T1 and ECV MRI quantification of the thigh and creatine-kinase (CK) measured. Suspected myopathy was defined as current/history of minimally raised CK (<600 IU/l) +/- presence of clinical signs-symptoms (proximal muscle weakness and/or myalgia) +/- a Manual Muscle Testing score <5 in the thighs. Results 12 SSc patients and 10 HV were recruited. 9/12 patients had limited cutaneous SSc, 4/12 interstitial lung disease, 7/12 suspected myopathy. Higher skeletal muscle ECV was recorded in SSc patients compared to HV [mean (SD) 23(11)%, vs 11(4)% p=0.04]. Peripheral muscle ECV associated with CK (rho=0.554, p=0.061) and was higher in SSc patients with myopathy compared to those with no myopathy [mean (SD) 28 (10) vs 15 (5), p=0.023]. An ECV of 22% was determined to best identify myopathy with a sensitivity of 71% and a specificity of 80%. Conclusion This hypothesis-generating study showed higher ECV in SSc patients compared to HV as well as association of ECV with suspected myopathy, suggesting the presence of diffuse fibrosis in the peripheral muscle of SSc patients. Further studies are needed to understand the nature of SSc myopathy
The Li-Fraumeni Spectrum: An International Agency for Research on Cancer TP53 Database Analysis
No full textImportance Li-Fraumeni syndrome is a cancer predisposition syndrome that is associated with a high, lifelong risk of a broad spectrum of cancers, caused by pathogenic TP53 germline variants. A definition that reflects the broad phenotypic spectrum that has evolved since the gene discovery is lacking and mechanisms leading to phenotypic differences remain largely unknown.Objective To define the phenotypic spectrum of Li-Fraumeni syndrome and to conduct phenotype-genotype correlations across the phenotypic spectrum.Design, Setting, Participants We propose the term "Li-Fraumeni spectrum" to encompass (1) phenotypic Li-Fraumeni syndrome, defined by the absence of a pathogenic/likely pathogenic TP53 variant in persons/families meeting clinical Li-Fraumeni syndrome criteria; (2) Li-Fraumeni syndrome, defined by the presence of a pathogenic/likely pathogenic TP53 variant in persons/families meeting Li-Fraumeni syndrome testing criteria; (3) attenuated Li-Fraumeni syndrome, defined by the presence of a pathogenic/likely pathogenic TP53 variant in a person/family with cancer not meeting Li-Fraumeni syndrome testing criteria; and (4) incidental Li- Fraumeni syndrome, defined by the presence of a pathogenic/likely pathogenic TP53 variant in a person/family without a history of cancer. We analyzed the germline variant dataset of the International Agency for Research on Cancer TP53 databasethat contains 3034 persons from 1282 families.Results Tumor spectra showed significant differences with a higher proportion of early adrenal, brain, connective tissue and bone tumors in patients meeting Li-Fraumeni syndrome genetic testing criteria, whereas carriers not meeting Li-Fraumeni syndrome genetic testing criteria had a higher proportion of breast and other cancers, 50% of them occurring after age 45 years. “Hotspot” variants were present in both groups. Several variants were exclusively found in patients with Li-Fraumeni syndrome while others where exclusively found in patients with attenuated Li-Fraumeni syndrome. In patients meeting Li-Fraumeni syndrome genetic testing criteria, most TP53 variants classified as pathogenic/likely pathogenic (80.7%), whereas about 38.8% of TP53 variants identified in patients not meeting the Li-Fraumeni syndrome genetic testing criteria were classified as variants of uncertain significance, conflicting results, likely benign, or benign.Conclusions and Relevance The new classification is a step towards understanding the factors leading to phenotypic differences and may serve as a model for other cancer predisposition syndromes
Extended gene panel testing in lobular breast cancer
No full textPurpose: Lobular breast cancer (LBC) accounts for ~15% of breast cancer. Here, we studied the frequency of pathogenic germline variants (PGVs) in an extended panel of genes in women affected with LBC. Methods: 302 women with LBC and 1567 without breast cancer were tested for BRCA1/2 PGVs. A subset of 134 LBC affected women who tested negative for BRCA1/2 PGVs underwent extended screening, including: ATM, CDH1, CHEK2, NBN, PALB2, PTEN, RAD50, RAD51D and TP53. Results: 35 PGVs were identified in the group with LBC, of which 22 were in BRCA1/2. Ten actionable PGVs were identified in additional genes (ATM(4), CDH1(1), CHEK2(1), PALB2(2) and TP53(2)). Overall, PGVs in four genes conferred a significant increased risk for LBC. Odds ratios (ORs) were: BRCA1: OR=13.17 (95%CI: 2.83-66.38; P=0.0017), BRCA2: OR=10.33 (95%CI: 4.58-23.95; P<0.0001) and ATM: OR=8.01 (95%CI: 2.52-29.92; P=0.0053). We did not detect an increased risk of LBC for PALB2, CDH1 or CHEK2. Conclusion: The overall PGV detection rate was 11.59%, with similar rates of BRCA1/2 (7.28%) PGVs as for other actionable PGVs (7.46%), indicating a benefit for extended panel genetic testing in LBC. We also report a previously unrecognised association of pathogenic variants in ATM with LBC