Investigating the Effectiveness of Dispersants for Graphitic Carbon Black Suspensions

The dispersability of graphitic carbon black (Monarch 1000) selected as a model for carbon nanotubes has been investigated in aqueous and non aqueous media using rheological, conductivity measurements and atomic force microscopy. The effectiveness of eight dispersants used for water was investigated namely polyethylene oxide polypropylene oxide ABA copolymers (PE/F 103 with 2x16 ethylene oxide units and PE/F 108 with 2x148 ethylene oxide units), Triton X100 and Triton X405 which contains an alkyl (octyl) phenol group with 10 and 40 ethylene oxide groups attached respectively, Lugalvan BNO12 which is a Naphthol Ethoxylate with 12 ethylene oxide units, sodium dodecylsulfate (SDS) an anionic surfactant with a tail of 12 carbon atoms and sulphate group attached to the tail and Sodium dedecylbenzenesulfonate (SDBS) which contains benzene ring in its anchoring group and NPE1800 (nonyl phenyl polypropylene oxide-polyethylene oxide with 27 ethylene oxide units). While for non polar organic solvents three dispersants namely polyhydroxystearic acid (Hypermer LP1), PEG 30-dipolyhydroxystearic acid (Hypermer B246) and polyisobutylene succinimide (OLOA 11000) were used. Hypermer LP1 is homopolymer and Hypermer B246 is polyhydroxystearic acid/polyethylene oxide/polyhydroxystearic acid ABA block copolymer while OLOA 11000 has polar head group (polyamine) attached to a hydrocarbon chain (polyisobutylene). Two non polar organic solvents decalin and xylene were selected. Decalin is aliphatic in nature while xylene is aromatic and it was observed that dispersing carbon black in xylene was relatively easy but there was not much difference in results for either media, which showed that the role of aromaticity of medium in dispersing graphitic carbon black is not significant. Adsorption isotherms of all dispersants were studied. The adsorption isotherms of PE/F 103 in comparison with PE/F 108 and Triton X100 in comparison with Triton X405 revealed that in molar terms the adsorption decreases with increasing number of ethylene oxide units indicating that adsorption is governed by the size of PEO (polyethylene oxide) chain length. Triton X100, Triton X405, Lugalvan BNO12 and NPE 1800 contain aromatic rings in their anchor group and adsorbed more strongly and proved to be much more efficient stabilizers. SDBS also showed higher adsorption than SDS due to п-п interaction with the graphitic carbon black. In non aqueous media, adsorption is a minimum in molar terms for homopolymer Hypermer LP1 as compared to other polymers. As the whole polymer molecule has affinity to adsorb onto the surface and by consequence the whole molecule may lay flat onto the surface giving smaller adsorption amounts. While Hypermer B246 and OLOA 11000 both dispersants consist of an anchoring group which strongly adsorbs on the surface and stabilising chain which has good solubility in the solvent and extends sufficiently in the solvent to import stability. The relative viscosity-effective volume fraction curves were compared with the theoretical curves for the hard sphere dispersions calculated using Krieger-Dougherty equation and showed that Triton X100, Triton X405, Lugalvan BNO12, NPE 1800, SDS and SDBS dispersions could be prepared at much higher solid fraction than those dispersions stabilized by PE/F 103 and PE/F 108. The results indicate that the presence of aromatic groups in the hydrophobic group and sufficient number of ethylene oxide units in adsorbed layer of the surfactants is desirable in producing the stable dispersions for these graphitic carbon black dispersions and would be sensible choices in stabilising carbon nanotubes. In non aqueous media, Hypermer LP1 did not show good agreement with the Krieger-Dougherty equation; the viscosities were all slightly higher than that predicted by that equation. The other two dispersants Hypermer B246 and OLOA 11000 proved to be good stabilizers for crystalline graphitic carbon black as they made dispersions of lower viscosities. That means homopolymer Hypermer LP1 may be more suitable for polar particles but not effective for hydrophobic surfaces. For hydrophobic surfaces a dispersant with block copolymer structure is required rather than homopolymer. Oscillatory shear measurements showed high values of storage and loss modulus at high volume fractions indicating strong repulsive interactions between the carbon black particles. The effectiveness of all dispersants was investigated by measuring the electrical conductivity measurements of carbon black dispersions prepared by using polymers at their optimum concentrations. PE series and Hypermer LP1 produced flocculated dispersions of much higher electrical conductivity as compared to other polymers which might be due to less number of ethylene oxide units in adsorbed layer. The performance of polymers was also measured by atomic force microscopy which is a characterizing technique to evaluate the effectiveness of polymers by measuring the interaction forces (attractive or repulsive forces) between particles in the presence and in the absence of polymers. Spherical glassy carbon black (2-12 micron size) was used to model Monarch 1000 because a larger size carbon black particle was required in AFM and similar results were observed except PE/F 108. PE/F 108 showed repulsive forces on approach and separation which indicated it an effective stabilizer which was a contradiction with rheology and conductivity experiments. However PE/F 103 and Hypermer LP1 showed an attraction on approach and separation

A novel homozygous missense variant in MATN3 causes spondylo- epimetaphyseal dysplasia Matrilin 3 type in a consanguineous family

Peer reviewe

Mortality and pulmonary complications in patients undergoing surgery with perioperative SARS-CoV-2 infection: an international cohort study

Background: The impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on postoperative recovery needs to be understood to inform clinical decision making during and after the COVID-19 pandemic. This study reports 30-day mortality and pulmonary complication rates in patients with perioperative SARS-CoV-2 infection. Methods: This international, multicentre, cohort study at 235 hospitals in 24 countries included all patients undergoing surgery who had SARS-CoV-2 infection confirmed within 7 days before or 30 days after surgery. The primary outcome measure was 30-day postoperative mortality and was assessed in all enrolled patients. The main secondary outcome measure was pulmonary complications, defined as pneumonia, acute respiratory distress syndrome, or unexpected postoperative ventilation. Findings: This analysis includes 1128 patients who had surgery between Jan 1 and March 31, 2020, of whom 835 (74·0%) had emergency surgery and 280 (24·8%) had elective surgery. SARS-CoV-2 infection was confirmed preoperatively in 294 (26·1%) patients. 30-day mortality was 23·8% (268 of 1128). Pulmonary complications occurred in 577 (51·2%) of 1128 patients; 30-day mortality in these patients was 38·0% (219 of 577), accounting for 81·7% (219 of 268) of all deaths. In adjusted analyses, 30-day mortality was associated with male sex (odds ratio 1·75 [95% CI 1·28–2·40], p\textless0·0001), age 70 years or older versus younger than 70 years (2·30 [1·65–3·22], p\textless0·0001), American Society of Anesthesiologists grades 3–5 versus grades 1–2 (2·35 [1·57–3·53], p\textless0·0001), malignant versus benign or obstetric diagnosis (1·55 [1·01–2·39], p=0·046), emergency versus elective surgery (1·67 [1·06–2·63], p=0·026), and major versus minor surgery (1·52 [1·01–2·31], p=0·047). Interpretation: Postoperative pulmonary complications occur in half of patients with perioperative SARS-CoV-2 infection and are associated with high mortality. Thresholds for surgery during the COVID-19 pandemic should be higher than during normal practice, particularly in men aged 70 years and older. Consideration should be given for postponing non-urgent procedures and promoting non-operative treatment to delay or avoid the need for surgery. Funding: National Institute for Health Research (NIHR), Association of Coloproctology of Great Britain and Ireland, Bowel and Cancer Research, Bowel Disease Research Foundation, Association of Upper Gastrointestinal Surgeons, British Association of Surgical Oncology, British Gynaecological Cancer Society, European Society of Coloproctology, NIHR Academy, Sarcoma UK, Vascular Society for Great Britain and Ireland, and Yorkshire Cancer Research

Investigating the effectiveness of dispersants for graphitic carbon black suspensions

The dispersability of graphitic carbon black (Monarch 1000) selected as a model for carbon nanotubes has been investigated in aqueous and non aqueous media using rheological, conductivity measurements and atomic force microscopy. The effectiveness of eight dispersants used for water was investigated namely polyethylene oxide polypropylene oxide ABA copolymers (PE/F 103 with 2x16 ethylene oxide units and PE/F 108 with 2x148 ethylene oxide units), Triton X100 and Triton X405 which contains an alkyl (octyl) phenol group with 10 and 40 ethylene oxide groups attached respectively, Lugalvan BNO12 which is a Naphthol Ethoxylate with 12 ethylene oxide units, sodium dodecylsulfate (SDS) an anionic surfactant with a tail of 12 carbon atoms and sulphate group attached to the tail and Sodium dedecylbenzenesulfonate (SDBS) which contains benzene ring in its anchoring group and NPE1800 (nonyl phenyl polypropylene oxide-polyethylene oxide with 27 ethylene oxide units). While for non polar organic solvents three dispersants namely polyhydroxystearic acid (Hypermer LP1), PEG 30-dipolyhydroxystearic acid (Hypermer B246) and polyisobutylene succinimide (OLOA 11000) were used. Hypermer LP1 is homopolymer and Hypermer B246 is polyhydroxystearic acid/polyethylene oxide/polyhydroxystearic acid ABA block copolymer while OLOA 11000 has polar head group (polyamine) attached to a hydrocarbon chain (polyisobutylene). Two non polar organic solvents decalin and xylene were selected. Decalin is aliphatic in nature while xylene is aromatic and it was observed that dispersing carbon black in xylene was relatively easy but there was not much difference in results for either media, which showed that the role of aromaticity of medium in dispersing graphitic carbon black is not significant. Adsorption isotherms of all dispersants were studied. The adsorption isotherms of PE/F 103 in comparison with PE/F 108 and Triton X100 in comparison with Triton X405 revealed that in molar terms the adsorption decreases with increasing number of ethylene oxide units indicating that adsorption is governed by the size of PEO (polyethylene oxide) chain length. Triton X100, Triton X405, Lugalvan BNO12 and NPE 1800 contain aromatic rings in their anchor group and adsorbed more strongly and proved to be much more efficient stabilizers. SDBS also showed higher adsorption than SDS due to п-п interaction with the graphitic carbon black. In non aqueous media, adsorption is a minimum in molar terms for homopolymer Hypermer LP1 as compared to other polymers. As the whole polymer molecule has affinity to adsorb onto the surface and by consequence the whole molecule may lay flat onto the surface giving smaller adsorption amounts. While Hypermer B246 and OLOA 11000 both dispersants consist of an anchoring group which strongly adsorbs on the surface and stabilising chain which has good solubility in the solvent and extends sufficiently in the solvent to import stability. The relative viscosity-effective volume fraction curves were compared with the theoretical curves for the hard sphere dispersions calculated using Krieger-Dougherty equation and showed that Triton X100, Triton X405, Lugalvan BNO12, NPE 1800, SDS and SDBS dispersions could be prepared at much higher solid fraction than those dispersions stabilized by PE/F 103 and PE/F 108. The results indicate that the presence of aromatic groups in the hydrophobic group and sufficient number of ethylene oxide units in adsorbed layer of the surfactants is desirable in producing the stable dispersions for these graphitic carbon black dispersions and would be sensible choices in stabilising carbon nanotubes. In non aqueous media, Hypermer LP1 did not show good agreement with the Krieger-Dougherty equation; the viscosities were all slightly higher than that predicted by that equation. The other two dispersants Hypermer B246 and OLOA 11000 proved to be good stabilizers for crystalline graphitic carbon black as they made dispersions of lower viscosities. That means homopolymer Hypermer LP1 may be more suitable for polar particles but not effective for hydrophobic surfaces. For hydrophobic surfaces a dispersant with block copolymer structure is required rather than homopolymer. Oscillatory shear measurements showed high values of storage and loss modulus at high volume fractions indicating strong repulsive interactions between the carbon black particles. The effectiveness of all dispersants was investigated by measuring the electrical conductivity measurements of carbon black dispersions prepared by using polymers at their optimum concentrations. PE series and Hypermer LP1 produced flocculated dispersions of much higher electrical conductivity as compared to other polymers which might be due to less number of ethylene oxide units in adsorbed layer. The performance of polymers was also measured by atomic force microscopy which is a characterizing technique to evaluate the effectiveness of polymers by measuring the interaction forces (attractive or repulsive forces) between particles in the presence and in the absence of polymers. Spherical glassy carbon black (2-12 micron size) was used to model Monarch 1000 because a larger size carbon black particle was required in AFM and similar results were observed except PE/F 108. PE/F 108 showed repulsive forces on approach and separation which indicated it an effective stabilizer which was a contradiction with rheology and conductivity experiments. However PE/F 103 and Hypermer LP1 showed an attraction on approach and separation.EThOS - Electronic Theses Online ServiceUniversity of Engineering and Technology, Lahore, PakistanGBUnited Kingdo

The Impact of Innovation on the Pakistan Economy Measuring through Performance/Portfolio Innovation Index

Innovation plays pivotal role in economic development. Several proxies’ exports of high technology, manufacturing sector share in GDP, ICT goods exports, R & D spending, employment population ratio, capital formation (gross), tertiary enrollment rate, poverty rate and unemployment rate are selected from numerous literatures that plays key role in growth of economy and contributes in promoting the innovation activities as well. The study has used the time series data which covers the period from 1985 to 2016. Econometric techniques ARDL and GMM E-views tests suggested by Unit root test are applied on these variables by dividing it into two indices: input indices and output indices which give positive results of having long run relationship with GDP. Moreover Performance/ portfolio innovation index is calculated by taking above proxies as base variables by the method used by Purdue centre of R&D, USA (2009). Results revealed that Pakistan strongly needs to enhance its innovation capacity to accelerate growth level of its economy

Study of nano-mechanical performance of pretreated natural fiber in ldpe composite for packaging applications

In this work, the effects of chemical pretreatment and different fiber loadings on mechanical properties of the composites at the sub-micron scale were studied through nanoindentation. The composites were prepared by incorporating choline chloride (ChCl) pretreated rice husk waste (RHW) in low-density polyethylene (LDPE) using melt processing, followed by a thermal press technique. Nanoindentation experiments with quasi continuous stiffness mode (QCSM) were performed on the surface of produced composites with varying content of pretreated RHW (i.e., 10, 15, and 20 wt.%). Elastic modulus, hardness, and creep properties of fabricated composites were measured as a function of contact depth. The results confirmed the appreciable changes in hardness, elastic modulus, and creep rate of the composites. Compliance curves indicated that the composite having 20 wt.% of pretreated RHW loading was harder compared to that of the pure LDPE and other composite samples. The values of elastic modulus and hardness of the composite containing 20 wt.% pretreated RHW were increased by 4.1% and 24% as compared to that of the pure LDPE, respectively. The creep rate of 42.65 nm/s and change in depth of 650.42 nm were also noted for the composite with RHW loading of 20 wt.%, which showed the substantial effect of holding time at an applied peak load of 100 mN. We believe that the developed composite could be a promising biodegradable packaging material due to its good tribo-mechanical performance.</p

Synthesis of Organic–Inorganic Nanohybrids-Based Polymeric Nanocomposites

Organic–inorganic nanohybrids-based polymer nanocomposites are made up of two different components, and these hybrids attained great attention over last decades due to their diversified framework and fascinating features. These nanohybrids possess synergistic characteristics of both organic and inorganic substances. Different synthetic routes are used to synthesize these materials with enhanced morphology, tunable features, and fine nanostructures. This chapter focuses on various synthetic routes for fabrication of organic–inorganic-based nanopolymeric composites. Synthetic strategies and protocols of different routes have been described in details. We have also discussed the advantages and limitations of all synthetic methods in details.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Aerospace Manufacturing Technologie

Spontaneous acute subdural haemorrhage with rupture of distal anterior cerebral artery aneurysm: A case report and review of literature

Pure subdural hematoma with subarachnoid haemorrhage brought about by ruptured intracranial aneurysm is uncommon and is related to delayed analysis and treatment. We present an uncommon instance of spontaneous subdural hematoma because of intracranial aneurysmal rupture. Case description: A 26-year-old female presented with sudden onset of thunderclap headache at midnight followed by an episode of generalized tonic-clonic seizure and loss of consciousness. There was no associated history of trauma. Computed tomography showed convexity subdural hematoma extending into tentorium without subarachnoid haemorrhage. The catheter angiography revealed a distal anterior cerebral artery aneurysm at the anterior internal frontal artery. Consequently, this aneurysm was embolized with squid with no residual filling. The patient was neurologically intact and was discharged on the third post-procedure day with left partial third nerve palsy. Conclusion: This paper demonstrates characteristics, diagnostics, and treatment modalities of this rare condition of intracranial aneurysmal rupture associated with subdural hematoma along with the literature review

Experimental Study of Mechanical Properties of Polypropylene Random Copolymer and Rice-Husk-Based Biocomposite by Using Nanoindentation

Nanoindentation is widely used to investigate the surface-mechanical properties of biocomposites. In this study, polypropylene random copolymer (PPRC) and biowaste rice husk (BRH) were used as the main raw materials, and glass-fiber-reinforced polypropylene and talc were also used with BRH to enhance the mechanical characterization of the biocomposites. The interfacial bonding between the polymer and the rice husk was increased by treating them with maleic anhydride and NaOH, respectively. The results obtained from the nanoindentation indicated that the plastic behavior of the biocomposites was prominent when untreated BRH was used and vice versa. The modulus and hardness of the biocomposite improved by 44.8% and 54.8% due to the neat PPRC, respectively. The tribological properties were studied based on the hardness-to-modulus ratio and it was found that BRH- and talc-based biocomposites were better than other samples in terms of low friction and wear rate. The creep measurements showed that untreated rice husk biocomposite exhibited high resistance to load deformation.Aerospace Manufacturing Technologie