3D Printable Geopolymer Composites Reinforced with Carbon-Based Nanomaterials - A Review.

Three-dimensional (3D) geopolymer printing (3DGP) technology is a rapidly evolving digital fabrication method used in the construction industry. This technology offers significant benefits over 3D concrete printing in terms of energy saving and reduced carbon emissions, thus promoting sustainability. 3DGP technology is still evolving, and researchers are striving to develop high-performance printable materials and different methods to improve its robustness and efficiency. Carbon-based nanomaterials (CBNs) with beneficial properties have a wide range of applications in various fields, including as concrete/geopolymer systems in construction. This paper comprehensively reviews the research progress on carbon-based nanomaterials (CBNs) used to develop extrusion-based 3D geopolymer printing (3DGP) technology, including dispersion techniques, mixing methods, and the materials' performance. The rheological, mechanical, durability, and other characteristics of these materials are also examined. Furthermore, the existing research limitations and the prospects of using 3DGP technology to produce high-quality composite mixtures are critically evaluated.

Stabilization/solidification of heavy metal-contaminated marl soil using a binary system of cement and fuel fly ash.

The stabilization/solidification (S/S) method is one of the most effective remediation techniques for treating contaminated soils. Several stabilizers, mostly the cementitious materials, have been used for the S/S treatment. In this paper, the feasibility of utilizing fuel fly ash (FFA) as a partial replacement of ordinary Portland cement (OPC) for the S/S treatment of marl soil contaminated with heavy metals was investigated. Two industrial waste materials, namely steel and electroplating wastes, were used to synthetically contaminate the marl soil. The stabilizers comprising of OPC and FFA were mixed with the contaminated soil at different dosages ranging from 10 to 40%, by mass, and a total of 48 S/S-treated soil mixtures were prepared. A series of experiments, including density, porosity, permeability, unconfined compressive strength (UCS), and toxicity characteristics leaching procedure (TCLP), were carried out on the soil mixtures to evaluate the efficiency of the proposed S/S treatment. Test results showed that the incorporation of FFA at higher volumes reduced the density and increased the porosity and permeability of the treated mixtures. Although FFA addition resulted in reducing the UCS values by an average of 46%, and this reduction was more significant at higher FFA percentages, the UCS values of all mixtures were more than 0.35 MPa (350 kPa), which passed the minimum requirements set by USEPA. In addition, the metal immobilization ability of the proposed treatment was confirmed by the TCLP analysis. As compared to the negative effect of the contamination of the soil by the electroplating waste, the contamination of the soil by steel waste had a higher negative effect. The results of this study would contribute in selecting an environment-friendly treatment of the contaminated soils using industrial waste materials, such as FFA, as a partial replacement of OPC. Nevertheless, the present study is an initial attempt to explore the possibility of utilizing FFA as a partial replacement of OPC in S/S treatment of marl soil contaminated with heavy metals. It is recommended to conduct another study in future including analysis of the treated soil mixtures using XRD, SEM, and FTIR techniques to better understand the stabilization/solidification mechanism and its implications on the test results.

Simeprevir plus sofosbuvir for eight or 12 weeks in treatment-naïve and treatment-experienced hepatitis C virus genotype 4 patients with or without cirrhosis.

The OSIRIS study investigated efficacy and safety of simeprevir plus sofosbuvir for eight or 12 weeks in hepatitis C virus (HCV) genotype 4-infected patients with METAVIR F0-F4 fibrosis. Sixty-three patients (33 treatment-naïve and 30 peg-interferon/ribavirin (Peg-IFN/RBV)-experienced) enrolled in a partly randomized, open-label, multicentre, phase IIa study. Patients with F0-F3 fibrosis were randomized (1:1) into two groups (A1 and A2), stratified according to treatment experience and METAVIR score, to receive either eight weeks (Group A1, n=20) or 12 weeks (Group A2, n=20) of treatment. Patients with compensated cirrhosis (METAVIR F4) received 12 weeks of treatment (Group B, n=23). Treatment comprised simeprevir 150 mg and sofosbuvir 400 mg daily. The primary efficacy endpoint was sustained virologic response 12 weeks after planned end of treatment (SVR12). Safety and tolerability were assessed throughout. Overall, 92% (95% CI: 82-97) of patients achieved SVR12; 75% (15/20) in Group A1 and 100% in groups A2 and B. Patients who did not achieve SVR12 (n=5) experienced viral relapse during the first 32 days following treatment and were all prior Peg-IFN/RBV null responders. The most commonly reported treatment-emergent adverse events (TEAEs) were asymptomatic lipase increase (14%), pruritus (14%), headache (13%) and hyperbilirubinaemia (11%). No patients discontinued due to TEAEs. In conclusion, simeprevir plus sofosbuvir for 12 weeks achieved a 100% SVR rate in HCV genotype 4-infected patients with or without compensated cirrhosis (ClinicalTrials.gov: NCT02278419). The AE and laboratory profile were favourable and consistent with previous data for simeprevir plus sofosbuvir in eight- and 12-week regimens.

Innate Cellular Immune Responses in Aedes caspius (Diptera: Culicidae) Mosquitoes.

Mosquitoes transmit a variety of pathogens that have devastating consequences for global public and veterinary health. Despite their capacity to serve as vectors, these insects have a robust capacity to respond to invading organisms with strong cellular and humoral immune responses. In Egypt, Aedes caspius (Pallas, 1771) has been suspected to act as a bridge vector of Rift Valley Fever virus between animals and humans. Microscopic analysis of Ae. caspius hemolymph revealed the presence of phagocytic cells called granulocytes. We further evaluated cellular immune responses produced by Ae. caspius as a result of exposure to a Gram-negative, and Gram-positive bacterium, and to latex beads. After challenge, a rapid and strong phagocytic response against either a natural or synthetic invader was evident. Hemocyte integrity in bacteria-inoculated mosquitoes was not morphologically affected. The number of circulating granulocytes decreased with age, reducing the overall phagocytic capacity of mosquitoes over time. The magnitude and speed of the phagocytic response suggested that granulocytes act as an important force in the battle against foreign invaders, as has been characterized in other important mosquito vector species.

Trans-femoral versus trans-carotid access for transcatheter aortic valve replacement: an updated systematic review and meta-analysis.

Aim: This meta-analysis aims to shed light on any primacy the trans-carotid (TC-TAVR) access may have over the trans-femoral access (TF-TAVR) for those undergoing transcatheter aortic valve replacement (TAVR). Methods: PubMed/MEDLINE and Cochrane Library were searched, from inception to March 2023 retrieving seven adjusted studies with a total of 6609 patients, of which 5048 underwent TF-TAVR while 1561 underwent TC-TAVR. Results: No divergence in risk of mortality, major bleeding or stroke/transient ischemic attack in TC-TAVR when compared with TF-TAVR was found. In TC-TAVR, the risk of vascular complications was low (OR: 0.51, 95% CI: 0.32-0.83, p = 0.003) as compared with TF-TAVR. Conclusion: As of this analysis, the viability of TC-TAVR as first alternative to TF-TAVR is plausible.

Synthesis of waste limestone powder-based alkali-activated binder: experimental, optimization modeling, and eco-efficiency assessment.

More than half of the CO2 emissions during the manufacturing of ordinary Portland cement (OPC) occur due to the calcination of calcium carbonate in addition to burning of fossil fuel to power the process. Consequently, there is a concerted effort to decrease the carbon footprint associated with this process, by minimizing the use of OPC. In line with this trend, an attempt was made in the reported study to synthesize a novel alkali-activated binder using CaCO3-rich waste limestone powder (WLSP) as a precursor. Utilizing the Taguchi method, four important parameters were varied at three levels to optimize the alkali-activated mixture. Analysis of variance (ANOVA) of the obtained results was performed to assess the impact of each of the factors on the properties of the developed binder. To enhance the strength further, OPC was added as a partial replacement of WLSP. The binder was characterized using scanning electron microscopy. The results have indicated that alkaline activator to binder ratio, Na2SiO3 to NaOH ratio, and sand to binder ratio of 0.575, 1.57, and 2.5, respectively, were the optimum to obtain satisfactory strength and workability with a 13.7-M NaOH activator solution. The incorporation of a small quantity of OPC in the mixture remarkably improved the density and strength of the alkali-activated-WLSP binder. Pirssonite (CaCO3.Na2CO3.2H2O) and C/N-A-S-H were the dominant mineral phases formed in the developed binder, particularly in the ones alkali-activated WLSP/OPC. In addition, the eco-efficiency assessment revealed that the WLSP is a promising low-carbon binder that can be used in developing more sustainable alkali-activated binder. The results have shown that the WLSP can be potentially utilized in developing binder that can be potentially used in the structural applications.

Electrical Stability and Piezoresistive Sensing Performance of High Strain-Range Ultra-Stretchable CNT-Embedded Sensors.

Highly flexible and stretchable sensors are becoming increasingly widespread due to their versatile applicability in human/robot monitoring sensors. Conductive polymeric composites have been regarded as potential candidates for such sensors, and carbon nanotubes (CNTs) are widely used to fabricate such composites. In the present study, CNT-embedded high flexible sensors were fabricated using a facile three-roll milling method, which mitigates the drawbacks of the conventional fabrication methods. CNTs content varied between 0.5 and 4.0 wt.%, and the percolation threshold range was obtained via conductivity/resistivity values of the fabricated sensors. Following this, the electrical stability of the sensors was examined against the various DC and AC signals. Furthermore, the fabricated sensors were stretched up to 500% strain, and their sensitivity against varying strain amplitudes was investigated in terms of the change in resistance and gauge factors. Lastly, the fabricated sensors were applied to human fingers for monitoring finger bending and releasing motions to validate their potential applications. The experimental results indicated that these sensors have a percolation threshold of around 2% CNTs content, and the sensors fabricated with 2 to 4% CNTs content showed measurable resistance changes against the applied strain amplitudes of 50-500%. Among these sensors, the sensor with 2% CNTs content showed the highest sensitivity in the studied strain range, exhibiting a resistance change and gauge factor of about 90% and 1.79 against 50% strain amplitude and about 18,500% and 37.07 against 500% strain amplitude, respectively. All these sensors also showed high sensitivity for finger motion detection, showing a resistance change of between 22 and 69%.

Facile Synthesis of Sprayed CNTs Layer-Embedded Stretchable Sensors with Controllable Sensitivity.

Flexible electronic devices have gained significant interest due to their different potential applications. Herein, we report highly flexible, stretchable, and sensitive sensors made of sprayed CNT layer, sandwiched between two polymer layers. A facile fabrication process was employed in which the CNT solution was directly sprayed onto a patterned bottom polymer layer, above which a second polymer layer was casted to get a sandwiched composite structure. Varying amounts of CNT solution (i.e., 10, 25, 40, 70, and 100 mL) were sprayed to get conductive CNT layers of different thicknesses/densities. The physical characteristics of the conductive CNT layers were studied through SEM and optical images. The starting electrical resistance values (without strain) as well as the changes in electrical resistance against human body motions were monitored. The synthesized samples exhibited good response against finger and wrist bending. The conductivity of the samples increased with increase of CNT solution volume while the sensitivity followed the inverse relation, suggesting that the sensors with controlled sensitivity could be fabricated for targeted strain ranges using the proposed method.

The Effects of Temperature on the Hydrothermal Synthesis of Hydroxyapatite-Zeolite Using Blast Furnace Slag.

Blast furnace slag, an industrial by-product, is emerging as a potential raw material to synthesize hydroxyapatite and zeolite. In this study, the effects of temperature on the hydrothermal synthesis of hydroxyapatite-zeolite from blast furnace slag were investigated. Specimens were synthesized at different temperatures (room temperature, 50, 90, 120, or 150 °C). The synthesized specimens were analyzed qualitatively and quantitatively via X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), BET/BJH, and scanning electron microscopy/energy dispersive using X-ray analysis (SEM/EDX). It was found that the hydroxyapatite phase was synthesized at all the reaction temperatures, while faujasite type zeolite appeared in the specimens synthesized at 90 and 120 °C. Moreover, faujasite was replaced by hydroxysodalite in the specimens synthesized at 150 °C. Additionally, the crystals of the hydroxyapatite tended to become larger and total crystallinity increased as the reaction temperature increased.

Synthesis of geopolymer-supported zeolites via robust one-step method and their adsorption potential.

The present study proposes a robust one-step hydrothermal treatment method for synthesis of high strength geopolymer-supported zeolites utilizing industrial by-products (fly ash and blast furnace slag), which can be potentially used as bulk-type solid adsorbents. The results revealed that the geopolymer-supported zeolites, possessing distinct strengths, zeolite phases (Na-P1, Na-chabazite, and analcime) and pore features depending on the mix design and synthesis conditions, can be easily synthesized employing the proposed one-step method. The geopolymer-supported zeolites exhibited the characteristics of mesoporous materials which are typically desired for commercial adsorbents. The maximum adsorption capacity for Pb2+ was found to be about 37.9 mg/g which is relatively higher than the other bulk-type adsorbents reported for Pb2+ to date. Since industrial by-products are used for synthesis of these materials, it will help in reducing the environmental hazards associated with the permanent disposal of such by-products, with an added advantage that these bulk-type solid adsorbents can be easily retrieved after use unlike granular adsorbents.

Detection of Wuchereria bancrofti in mosquitoes by the polymerase chain reaction: a potentially useful tool for large-scale control programmes.

Focally endemic bancroftian filariasis is targeted for elimination in the Nile delta of Egypt. Improved methods are needed for identifying endemic villages to be included in the control programme and for monitoring its success. We have evaluated the performance of a polymerase chain reaction (PCR) assay in estimating Wuchereria bancrofti infection in pools of Culex pipiens (1-25 females) from 2 adjacent villages with high (El Qolzom, 10.8%) and low (Kafr Shorafa, 2.1%) prevalence rates of human filariasis. This assay detects a repeated sequence in W. bancrofti deoxyribonucleic acid (DNA). Mosquitoes resting within houses were captured by aspiration and pooled by house. Houses were classified as positive or negative for human filarial infection based on night blood examinations of residents. The assay detected parasite DNA in mosquitoes from 60% of 25 infected houses and 24% of 25 uninfected houses. PCR processing of mosquitoes caught within houses of unknown filariasis infection status (44 in El Qolzom, 37 in Kafr Shorafa) identified 31.8% and 8.1% of houses, respectively, as containing infected mosquitoes. These results support the validity of the PCR assay for evaluating filarial prevalence in different villages. C. pipiens collected outdoors in dry ice-baited traps and tested by PCR (266 in Qolzom, 82 in Kafr Shorafa) did not contain parasite DNA. Pools of female mosquitoes (296 in Qolzom, 240 in Kafr Shorafa) captured in oviposition traps were also negative. We concluded that the PCR based assay is a powerful epidemiological tool that can be used for evaluating W. bancrofti infection in villages in the Nile delta and for monitoring the application of control programmes in filariasis endemic areas.

Effect of Wuchereria bancrofti (Cobbold infection on the biological activities of Culex pipiens L. (Diptera: Culicidae) in Egypt.

The impact of moderate infection with Wuchereria bancrofti (Cobbold) (25 mf/50 microliters blood) on the biological activities of Culex pipiens L. were investigated. Data revealed that W. bancrofti parasites did not interfere significantly with the oviposition rate (81.97%, 80.228% in non-infected and infected mosquitoes, respectively), fecundity (73.56 +/- 4.56 and 74.23 +/- 5.05 eggs/female) duration of the gonotrophic cycle (6.34 +/- 0.29 and 6.05 +/- 0.26 days), or egg hatchability (88.06% and 90.07%) of infected mosquitoes. Furthermore adult survival to the extrinsic incubation period of infected females (91.8%), did not vary from that of non-infected ones (78.87%). It is suggested that the lack of variations is due to the relatively low level of microfilariae (mf) to which mosquitoes are generally exposed, as revealed by parasite burden. It is concluded that in Egypt the relationship of W. bancrofti to Cx. pipiens is that of a commensal rather than a parasite.

Determination and seasonal abundance of mite predators of the house fly eggs in Cairo and Giza, Egypt.

Mite predators on the house fly eggs were collected from manure in two slaughterhouses in Cairo and Giza for 2 successive years. Macrochelidae, Parasitidae and Uropodidae were generally collected in that order of abundance. Macrochelidae was represented by 3 species: M. mascaedomesticae (Scopoli), M. merdarius (Berlese) and Glyptholaspis confusa (Foa). Parasitidae and Uropodidae were represented by P. consanguineus (Oudemans & Voigts) and U. (Fuscuropoda) Marginata (C.L. Koch), respectively. The macrochelid and parasitid species generally attained their highest populations in winter and/or spring from December to May. However, the highest populations of the uropodid species were reached mainly in late spring, summer and autumn from May to October.

Uptake and development of Wuchereria bancrofti in Culex pipiens L. and Aedes caspius pallas.

Studies were conducted to compare early phenomena associated with W. bancrofti infection and further development in the filaria vector Culex pipiens and the refractory mosquito Aedes caspius. Ingestion rates evaluated immediately after simultaneous feeding on an infected human were 69.1% for 43 Cx. pipiens and 35.7% for 28 Ae. caspius. The observed number of mf ingested by either mosquito did not vary significantly (2.7 +/- 1.4, and 2.3 +/- 0.9, respectively) and, based on the size of the blood meal ingested (2.8 and 2.3 microliters respectively), a two-fold mf concentration factor was recorded for both species. Blood ingested by Cx. pipiens (N = 16) and Ae. caspius (N = 10) clotted within 120 and 90 min post-feeding respectively. The time difference observed, however, did not affect significantly the rates of migration into the hemocele (56 and 67% respectively). Comparison of initial infection rates with those obtained after the extrinsic incubation period of the parasite was completed, indicated that the proportion of infected Cx. pipiens was reduced by 3.9% and that of Ae. caspius by 30.0%. Furthermore, the observed infectivity ratio of 265 Cx. pipiens that had an infective blood meal was 0.74 and only 0.009 for 70 Ae. caspius. It is concluded that refractoriness of Ae. caspius to W. bancrofti is expressed through the feeding mechanism itself, by severely limiting the mf ingestion rate, and through physiological processes that inhibited the development of ingested worms.

Host-parasite relationships of Wuchereria bancrofti and mosquito hosts, Culex pipiens L. and Aedes caspius pallas.

We compared the defense mechanisms directed against Wuchereria bancrofti by a filaria susceptible mosquito, Culex pipiens, and a refractory one, Aedes caspius. The reciprocal deleterious effects of both the mosquito host and its parasite are reported. Anatomical and histological examinations of mosquitoes revealed minor differences in the general structure of the foregut of either species. The cibarial pump of Ae. caspius, however, lacked a cibarial armature and damage inflicted to some of the microfilariae (mf) ingested by this mosquito was not mechanical. In contrast, the cibarial armature of Cx. pipiens consisted of 24 delicate teeth which did not seem to affect ingested mf. The peritrophic membrane (pm) did not constitute a significant barrier to mf migrating through the midgut wall of either mosquito. Indeed, mf forced their way out into the hemocoel, immediately after they have been ingested, and up to 60 min post-feeding, when the pm was still thin and soft. It hardened 16 h post-feeding. Traversing mf perforated the pm and displaced the basement membrane. Within the thorax of Cx. pipiens, the parasite completed its development synchronously. In contrast, mf ingested by Ae. caspius did not develop beyond the sausage stage, and many of these larvae were vacuolated. In both mosquitoes, parasitized thoracic muscle fibers were tunnelled and, only in Ae. caspius, their nuclei were pyknotic. No worm encapsulation or melanization was observed in either mosquito. It is concluded that defense lines to invading parasites in Cx. pipiens are insignificant, and that in Ae. caspius, the main barrier to parasite development resides within the thoracic muscles. In the absence of cellular evidence, it is suggested that such a barrier is physiological in nature.

The impact of environmental and entomological factors on intervillage filarial focality in the Nile Delta.

In the Nile Delta of Egypt, levels of W. bancrofti infection in humans vary among nearby villages. Ecological and entomological factors that might explain variability between adjacent villages, El Qolzom (QOL) and Kafr Shorafa (KSH) with respective 10.8% and 2.1% microfilaria (MF) prevalence were examined. The epidemiological study covered 127 and 79 houses scattered in QOL and KSH, respectively, and described 25 items relating to housing characters, socio-economic state and human activities. It revealed that QOL is more rural than KSH, and therefore would be more favorable to the vector mosquito population and hence, filarial parasite transmission in QOL. Weekly records (N = 81 and 62 for QOL and KSH, respectively) of ambient temperature, relative humidity and wind speed taken at sunset, over 3 months during summer, revealed no significant variation between villages. Those measured at sunrise revealed significant, although inconsistent, differences at a particular month, but no difference over the whole period. Whether climatological conditions could have influenced mosquito bionomics in the study villages is questionable. Abundance of female Cx. pipiens collected weekly by standard sampling methods using 247 and 240 dry ice-baited CDC trap-nights in QOL and KSH, respectively, oral aspiration from within 346 and 304 respective house-nights, and 65 and 40 respective ovitrap-nights, did not vary significantly over the whole study period. Daily survival and survival to infectivity rates of wild-caught mosquitoes were based on parity and were generally more elevated in QOL than KSH. Monthly records of abundance and survival seemed to favor filaria transmission by mosquitoes in QOL. Autogeny amounted to 6.5 and 20% for QOL and KSH, respectively. Experimental infection of Cx. pipiens from the study villages with W. bancrofti revealed that QOL females were 3.3 times more efficient vectors than KSH ones, mainly because QOL mosquitoes survived longer. The ultimate outcome of observed entomological factors might explain its preponderance in QOL.