Standard Steam Research Articles

THE INFLUENCE OF STEAM TEACHING ACTIVITIES INTEGRATING LOCAL ENVIRONMENTAL AWARENESS ON UNIVERSITY STUDENTS’ PRO-ENVIRONMENTAL BEHAVIOR AND SCIENTIFIC CREATIVITY

This study aims to explore the impact of STEAM teaching activities that incorporate local environmental awareness on university students’ pro-environmental behavior (PEB), and scientific creativity. The teaching activity design of this study was centered on “designing livable housing in Taiwan”, and a total of four projects were designed. This research included university students (N=66) who were divided into a control group (n=33) and an experimental group (n=33). The experimental group added videos on local environmental awareness such as “local disasters and local household interview news”. The students were required to fill out the “Scientific Creativity Questionnaire” and “PEB Scale” before and after the teaching activities. The results of the study indicate that the experimental group outperformed the control group in the post-test for the sub-dimensions of "Green Behavior," "Global Warming Awareness," "Environmental Social Interaction," "Informal Environmental Education," and "Environmental Attitude." This suggests that incorporating local environmental awareness materials into STEAM teaching activities is more effective in enhancing university students' PEB compared to standard STEAM teaching activities. Additionally, both groups showed improvements in overall scientific creativity after participating in the different activities, particularly in the areas of fluency and flexibility. However, ANCOVA analysis revealed no significant difference in scientific creativity between the two groups in the post-test. The results indicated that the integration of local environmental awareness materials was not the primary factor contributing to improvements in scientific creativity. This study recommends that higher education lectures integrate both environmental awareness and scientific content into curriculum design to strengthen students' overall competencies. Keywords: local environmental awareness, quantitative research, pro-environmental behavior (PEB), scientific creativity, STEAM

Macro Performances and Microstructures of Graphene Oxide-Modified Cement Mortar Under Steam Curing Conditions

This study investigates the effects of incorporating polycarboxylate superplasticizer (PCE) and graphene oxide (GO) into cement mortar. The mechanical properties and durability of PCE-GO-modified cement mortar were compared under standard curing conditions and steam curing conditions. The results indicate that the optimal performance was achieved with a GO content of 0.04 wt% in a dosage of 0 to 0.06 wt%. Comparing the mortar’s performance under standard and steam curing conditions after 28 days revealed that the mechanical properties of the specimens cured under steam conditions were significantly lower than those cured under standard conditions. However, when 0.12 wt% PCE and 0.04 wt% GO were added, the filler effect of GO led to a 31.8% increase in flexural strength and a 28.4% increase in compressive strength for the specimens cured under steam conditions on the 28th day, effectively compensating for the strength loss caused by steam curing. The chloride ion penetration test and sulfate erosion test confirmed the optimal performance of the cement mortar specimens at 0.04 wt% GO, with corrosion resistance coefficients for flexural and compressive strength increasing by 68% and 70%, respectively, after 90 days of steam curing. Furthermore, SEM observations were conducted on the cement mortar specimens, revealing that GO not only fills the internal voids of the matrix but also organizes the hydration products of cement, resulting in a more compact matrix structure. This study enables PCE-GO-modified cement mortar to meet the requirements of early strength development without compromising the later-stage performance of the cement mortar due to steam curing-induced damage.

High Performance Organic Mixed Ionic‐electronic Polymeric Conductor with Stability to Autoclave Sterilization

We present a series of newly developed donor‐acceptor (D‐A) polymers designed specifically for organic electrochemical transistors (OECTs) synthesized by a straightforward route. All polymers exhibited accumulation mode behavior in OECT devices, and tuning of the donor comonomer resulted in a three‐order‐of‐magnitude increase in transconductance. The best polymer gFBT‐g2T, exhibited normalized peak transconductance (gm,norm) of 298±10.4 S cm‐1 with a corresponding product of charge‐carrier mobility and volumetric capacitance, μC*, of 847 F V‐1 cm‐1 s‐1 and a μ of 5.76 cm2 V‐1 s‐1, amongst the highest reported to date. Furthermore, gFBT‐g2T exhibited exceptional temperature stability, maintaining the outstanding electrochemical performance even after undergoing a standard (autoclave) high pressure steam sterilization procedure. Steam treatment was also found to promote film porosity, with the formation of circular 200 – 400 nm voids. These results demonstrate the potential of gFBT‐g2T in p‐type accumulation mode OECTs, and pave the way for the use in implantable bioelectronics for medical applications.

High Performance Organic Mixed Ionic-Electronic Polymeric Conductor with Stability to Autoclave Sterilization.

We present a series of newly developed donor-acceptor (D-A) polymers designed specifically for organic electrochemical transistors (OECTs) synthesized by a straightforward route. All polymers exhibited accumulation mode behavior in OECT devices, and tuning of the donor comonomer resulted in a three-order-of-magnitude increase in transconductance. The best polymer gFBT-g2T, exhibited normalized peak transconductance (gm,norm) of 298±10.4 S cm-1 with a corresponding product of charge-carrier mobility and volumetric capacitance, μC*, of 847 F V-1 cm-1 s-1 and a μ of 5.76 cm2 V-1 s-1, amongst the highest reported to date. Furthermore, gFBT-g2T exhibited exceptional temperature stability, maintaining the outstanding electrochemical performance even after undergoing a standard (autoclave) high pressure steam sterilization procedure. Steam treatment was also found to promote film porosity, with the formation of circular 200-400 nm voids. These results demonstrate the potential of gFBT-g2T in p-type accumulation mode OECTs, and pave the way for the use in implantable bioelectronics for medical applications.

Mechanical and Drying Shrinkage Performance Study of Ultra-High-Performance Concrete Prepared from Titanium Slag under Different Curing Conditions.

This research investigates the effects of various curing regimes, the incorporation of titanium slag, and the utilization of quartz sand on the strength properties and shrinkage behavior of ultra-high-performance concrete (UHPC). By using low-heat silicate cement to prepare UHPC, this study conducted standard curing and steam curing, and comprehensively analyzed the macro and micro performance of UHPC under different curing conditions. The findings indicate that the application of steam curing markedly enhances the mechanical attributes of UHPC while efficiently decreasing its drying shrinkage. In the comparative tests, we found that the compressive strength of concrete that had undergone 2 days of steam curing was 9.15% higher than that of concrete cured for 28 days under standard conditions. In addition, under the same curing conditions, titanium slag sand had higher mechanical properties than quartz sand. Under standard curing conditions, the 28-day compressive strength of UHPC using titaniferous slag aggregate was 12.64% higher than that of UHPC using standard sand. Through the data analysis of XRD, TG, and MIP, we found that the content of Ca(OH)2 in the hydration products after steam curing was reduced compared to the standard curing conditions, and the pore structure had been optimized. The UHPC prepared with titanium slag sand has greater advantages in mechanical properties and drying shrinkage, and has a smaller pore structure than the UHPC prepared with quartz sand. Moreover, the use of titanium slag sand offers ecological and economic benefits, making it a more sustainable and cost-effective option for high-performance construction applications.

A Novel Method to Sanitize Breast Pump Equipment in the Neonatal Intensive Care Unit.

Enhancing the current breast pump sanitization method may improve maternal satisfaction and increase a mother's likelihood of providing human milk for their hospitalized infants in the Neonatal Intensive Care Unit (NICU). Other than Centers for Disease Control (CDC) data, there is lack of studies on sanitization practices. Currently, the only option in the hospital setting for breast pump equipment cleaning is a steam sanitization plastic bag. Using the Q. Basin will increase participant satisfaction compared to the steam sanitization bag. A multi-phased pilot study was conducted in our quaternary care NICU to test the Q. Basin, a novel design developed to wash, dry, and safely steam sanitize breast pump equipment compared to the standard steam bag. A bacterial study was conducted on breast pump equipment from 10 mothers by swabbing the equipment immediately at hour zero and 24hours. Twenty NICU mothers concurrently evaluated their satisfaction via a 3-question survey comparing the Q. Basin and the steam sanitization plastic bag method. The results showed a 20% increase in satisfaction with Q. Basin compared to the steam bag method. Data analysis from the satisfaction survey concludes that mothers pumping preferred the Q. Basin as a quicker, faster, and more environmentally friendly method for breast pump part sanitization. Additional safety and materials studies are required before using the Q. Basin in the clinical environment.

Ion transportation properties of cement-based material under standard curing and steam curing

In coastal and saline environments, the infiltration of chloride and sulfate ions into cementitious materials can result in erosion and deterioration. This research focuses on the impact of temperature-related curing methods on the ion transport properties and microstructure of these materials. The results show the curing method does not alter the hydration products of cementitious materials. High-temperature curing reduces the content of ettringite, resulting in decreased Friedel's salt and gypsum after chloride ion corrosion. Meanwhile, high-temperature curing reduces the content of Ca(OH)2 and SiO2, decreasing the content of gypsum after sulfate ion erosion. It indicates that high-temperature curing reduces the binding capacity of both chloride ions and sulfate ions. Besides, high-temperature steam curing deteriorates the pore structure compared to standard curing. As a result, the resistance of concrete to ion corrosion is reduced under high-temperature steam curing. Besides, the surface ion concentration and binding capacity of chloride ions and sulfate ions both increase with the duration of erosion. Under the same erosion age, the binding capacity of sulfate ions is significantly higher than that of chloride ions. This research provides new insights into the transport characteristics of eroding ions under high-temperature steam curing.

Influence of Fly Ash Content on the Durability of Mortar Specimens under Dry/Wet Sulfate Attack.

To investigate the durability of cementitious materials under complex environmental conditions in Xinjiang, this study conducted durability tests on mortar specimens with different fly ash contents under dry/wet sulfate attack conditions, with standard curing and steam curing at 70 °C. The appearance loss and flexural and compressive strength variations in the specimens were analyzed, and an evolution model of the mortar strength under a dry/wet sulfate attack was established. Moreover, XRD and SEM techniques were used to characterize the erosion products and microstructure, and to explore the erosion resistance mechanism of fly ash cementitious materials. The results showed that, after 160 cycles of erosion, the flexural strength of the specimens decreased with the increase in the fly ash content. In the context of steam-cured mortar specimens, throughout the entire erosion period, specimens with a fly ash content of 45% exhibited the highest relative compressive strength. The established strength evolution model had a minimum determination coefficient of 0.879, indicating a good agreement between the model and experimental results. Microscopic research showed that fly ash would undergo a pozzolanic reaction under the action of sulfate and calcium hydroxide, which was beneficial to the improvement of the erosion resistance. As the fly ash content increased, the erosion products of the specimens gradually became dominated by gypsum.

Effect of Cooking with Superheated (SHS) vs. Standard Steam Oven on the Fatty Acids Profile of Different Kinds of Meat and Fish.

We compared the effect of two different kinds of steam oven-a standard (SO) and a superheated steam (SHS) oven-on four different kinds of samples: hamburgers, bovine steaks, pork steaks, and salmon fillets. Ten samples of each meat/fish were divided into three parts. Then samples were analyzed as (i) raw, (ii) cooked with SO, and (iii) cooked with SHS. For each sample, we determined the proximate composition, fatty acid composition and thiobarbituric acid reactive substances (TBARS). The results of fatty acid composition were processed both with a linear model and with a multivariate approach by using three complementary discriminant analysis techniques: canonical (CAN), stepwise (St) and discriminant (DA). SHS was effective in degreasing hamburgers but not the other kinds of samples. Cooking methods selectively affected the fatty acid profile of samples, SHS being higher in MUFA and lower in PUFA n-3 than SO. This result was also confirmed by the discriminant analysis. Finally, samples cooked with SHS showed a lower fatty acid oxidation extent than SO, as the TBARS value was significantly lower in the SHS than in the SO, irrespective of the type of meat/fish cooked.

Effect of curing regime on the immobilization of municipal solid waste incineration fly ash in sustainable cement mortar

Stabilizing/solidificating municipal solid waste incineration fly ash (MIFA) with cement is a common strategy, and it is critical to study the high-value utilization of MIFA in ordinary Portland cement (OPC) components. With this aim, binary-binding-system mortar was produced by partially replacing OPC (∼50%) with MIFA, and the effects of different curing regimes (steam curing and carbonation curing) on the properties of the cement mortar were studied. The results showed that the setting time of the cement paste was shorten with the increase of MIFA content, and steam curing accelerated the hardening of the mixture. Although the incorporation of MIFA reduced the strength of the mortar, compared to conventional curing method, steam curing and carbonation curing increased the 3-d strength of the mortar. For high-volume MIFA mortars, the CO2-cured samples had the highest long-term strength and lowest permeability. The incorporation of MIFA increased the initial porosity of the mortar, thereby significantly increasing the carbonation degree and crystallinity of the reaction product - CaCO3. Steam curing also further narrowed the difference in the hydration degree between MIFA-modified sample and plain paste, which may be due to the enhanced hydraulic reactivity of MIFA at high temperatures. Although the incorporation of MIFA increased the porosity of the mortar, this waste-derived SCM refined the bulk pore structure and decreased the interconnected porosity. Additionally, the heavy metal leaching contents of MIFA-modified mortars were all below 1%, which meet the requirements of Chinese standards. Compared with standard curing, steam curing and carbonation curing made the early-age and long-term performance of MIFA-modified mortar better, which can promote the efficient application of MIFA in OPC products.

Pore structure evolution and sulfate attack of high-volume slag blended mortars under standard curing and steam curing

Partial replacement of cement with high-volume slag reduces the amount of cement in concrete and thereby lessens the environmental pressure caused by cement production. This paper investigates the pore structure evolution and sulfate attack of high-volume slag blended mortars under standard curing and steam curing, discusses the effects of slag content and pore structure on sulfate attack, and evaluates the methods for determining the sulfate resistance performance. The pore structure results show that the hydration of cement and/or slag reduces the porosity and most probable pore diameter (MPPD) and refines the pore structure of mortars. Steam curing primarily affects the pore size distribution but not the porosity for the mortars within 3 d. Increasing slag replacement increases the porosity for standard-cured and steam-cured mortars at the age of 28 d; however, it significantly reduces the air voids that are detrimental to sulfate resistance. Sulfate attack results show that the combination of the flexural strength test with the sulfate-ion content can evaluate the sulfate resistance well. The sulfate resistance improves with increasing slag content, and 70% of slag improves the sulfate resistance significantly for both standard-cured and steam-cured mortars. In addition, the MPPD, gel pores, and mesopores do not seem to determine the sulfate resistance. Reducing the volume fractions of large capillary pores, especially air voids, can improve sulfate resistance.

Optimization of ultrasound pretreatment and enzymatic hydrolysis of wheat straw: From lab to semi-industrial scale

In this paper, the dominance of the physical effects of ultrasound (US) pretreatment in improving the delignification of wheat straw at a 1:20 solid/liquid (biomass/water) ratio is reported showing low-frequency/high power (25 kHz, 2 or 3 kW) as preferred conditions. The sonochemical pretreatment with alkali was identified as an optimal method to make the cellulose more susceptible to further enzymatic hydrolysis, thereby increasing the yield of soluble sugars. Previous bench-scale studies have shown that US pretreatment has a positive effect on delignification, nevertheless this has not yet been demonstrated on a larger scale. The objective of this study was to demonstrate the effectiveness of US pretreatment for wheat straw delignification from lab to semi-industrial scale (40 kg biomass) in terms of sugar yield and energy efficiency. A 59.2% of lignin removal was recorded after the cavitational treatment of wheat straw with a subsequent 68 ± 5.7% yield in terms of enzymatic hydrolysis (52.6% glucose, 42.9% xylose and 4.5% arabinose).It was demonstrated that the positive effect of US alkali pretreatment of wheat straw on sugar yield was due to a combination of factors, including (i) an easier accessibility of the biomass carbohydrate network to enzymes due to the increased wheat straw porosity, (ii) the partial removal of lignin, which increases the relative proportion of carbohydrates in the treated biomass, and (iii) the disordering (amorphization) of the cellulose structure, which promotes carbohydrate hydrolysis as well as saponification of the acetyl groups in the hemicellulose. With respect to the Life Cycle Assessment (LCA) and the Cost Benefit Analysis the US pretreatment process herein reported was compared to an alternative Steam Explosion pretreatment. The results of the LCA analysis showed, that for all five environmental categories (energy consumption, global warming potential, water and fossil depletion, and the land occupation) the US pretreatment has advantages in comparison with the standard industrial Steam Explosion pretreatment.

Effect of steam inhalation therapy as add-on to standard treatment in COVID-19 patients with mild symptoms

Background: The different ambient temperatures of the upper and lower respiratory tract could influence the replication kinetics of the virus. Objective: This study is aimed to evaluate the effect of steam inhalation on clinical progression of COVID-19 and its subsequent impact on viral load that was evaluated in patients. Materials and Methods: A randomized control trial in mildly infected COVID-19 was undertaken. The participants were randomized either to standard treatment plus steam inhalation (test, n = 22) or standard treatment alone (control, n = 22). Steam inhalation was continued for 20 min thrice daily for 10 days. The first reverse transcription polymerase chain reaction swab was collected on day 1 before steam inhalation and the second swab was obtained after its completion on the fourth day. In the control group, the swabs were collected at the matched time-points. The clinical progression of disease and the need of oxygen therapy were observed for 10 days. Reductions in cycle-threshold levels were assessed at the completion of 4 days of steam treatment. Results: Only one patient from the test group and six patients from the control group progressed to moderate disease. No patient from the steam group required oxygen therapy, whereas three patients from the control group needed it. The median cycle-threshold levels pertaining to N-gene, E-gene, and RNA-dependent RNA polymerase, respectively, were nonsignificant. All the patients showed clinical recovery. Conclusions: The clinical trends support the use of steam therapy as add on over standard treatment in mildly infected COVID-19 patients.

Characteristics of the Religious Element in STREAM Learning in Elementary Schools

One of the learning approaches that can help answer today’s challenges of development is the STREAM learning approach. This contains a religious element that is an addition to the standard STEAM approach. This research consisted of a literature review. 52 studies were found that met the inclusion criteria. Information was obtained from these studies about the development of STREAM learning in elementary schools and its religious characteristics. According to the findings, the characteristics of the religious element in elementary school STREAM learning include: 1) placing students as learning subjects and teachers as facilitators according to the dimensions of religious beliefs and feelings; 2) exposing students to direct experiences, which are in accordance with the dimensions of the religious effect, namely actual religious practices in everyday life; 3) integrating religious values into subjects in schools that are in accordance with the dimensions of religious influence and the practice of religion of each student; 4) presenting concepts in one process that is in line with the dimensions of students’ religious knowledge; 5) linking religious elements to teaching materials or other subject matter in accordance with religious knowledge and students’ religious practice; and 6) adjusting learning outcomes to the interests, needs, and characteristics of the students, because each student’s religious beliefs and religious feelings will be different.
 Keywords: religious, STEAM, STREAM, elementary school learning

Highly Selective Oxidative Dehydrogenation of Ethane to Ethylene via Chemical Looping with Oxygen Uncoupling through Structural Engineering of the Oxygen Carrier

AbstractThe oxidative dehydrogenation of ethane (ODH) to produce ethylene offers advantages compared to the industry standard steam cracking, but its industrial application is hindered by costly air separation units needed to supply oxygen. A chemical‐looping‐based oxidative dehydrogenation (CL‐ODH) scheme is presented, in which oxygen carriers supply gaseous oxygen in situ, which then reacts with ethane in the presence of a catalyst at a comparatively low temperature (500 °C). A common challenge of chemical looping processes beyond combustion is to suppress the overoxidation of hydrocarbons to COx to enable high product yields. It is demonstrated that the overoxidation of ethane can be eliminated completely through structural engineering of the perovskite oxygen carrier involving alkali‐metal‐based carbonate coatings, while maintaining the materials’ ability to generate oxygen. Through CL‐ODH, higher ethylene selectivity (≈91%) and yields (≈39%) are achieved compared to the conventional ODH scheme without oxygen carrier and cofeeding air/ethane. 18O‐labeling experiments demonstrate that the carbonate layer functions like a diffusion barrier for ethane while being permeable for oxygen. Both the CL‐ODH scheme and the material design strategy can be extended to other catalytic oxidation or dehydrogenation reactions requiring oxygen at different temperatures, offering enormous potential to intensify such processes.

Experimental research on the spalling behaviour of ultra-high performance concrete under fire conditions

Explosive spalling is a severe risk for ultra-high performance concrete (UHPC) structures exposed to fire, fundamentally obstructing the comprehensive study of fire safety and the extensive engineering application of UHPC. In contrast to previous studies on the optimisation of components and mixture properties, this paper proposes a new curing regime, two-stage hot air curing (THAC), to inhibit the explosive spalling of UHPC in a high stress state and under an extreme heating rate. Two hundred and twenty-eight UHPC cubes with variations in parameters such as curing regime, fibre type, and water-binder ratio were tested under the ISO 834 fire standard. The influence of THAC on the mechanical properties and explosive spalling of the samples was investigated, and scanning electron microscopy (SEM) was utilised to observe the microstructures of the tested cubes. On this basis, twelve full-scale UHPC beams with various curing regimes and load ratios were tested under thermal–mechanical coupling conditions. The explosive spalling behaviour of the beams was observed, and the influence of spalling on the fire resistance was analysed. The test results indicated that UHPC formed a dense microstructure during the first stage of 50 °C curing. With hot air curing at 150 °C, further hydration and pozzolanic reaction of residual cement and mineral admixtures could be activated, generating massive calcium-silica-hydrate (C-S-H) gels. Moreover, almost all the free water could be consumed and evaporated after THAC curing, dramatically improving the explosive spalling resistance of UHPC. THAC could completely prevent the fire-induced explosive spalling of UHPC of different sizes and with varying stress states and improve the mechanical properties. This occurred despite conventional curing such as standard curing, water curing, and steam curing potentially leading to more serious spalling and a significant reduction in fire resistance, even possibly affecting the failure mode of UHPC beams.

Improving flexural strength of UHPC with sustainably synthesized graphene oxide

Abstract Ultrahigh-performance concrete (UHPC) has been increasingly employed for infrastructure and building structure, thanks to its excellent durability and exceptional mechanical properties; however, improving its relatively low flexural strength remains a challenging issue. This study presents an experimental investigation on improving the compressive strength and flexural strength of UHPC by employing sustainably synthesized graphene oxide (GO). The content of micro steel fibers (MSFs) for the UHPC ranges from 0.5 to 1.5% by volume of concrete. For each level of MSFs addition, the dosage of GO added is from 0.00 to 0.03% by mass of cement. The results indicate that the electrochemical (EC) method to synthesize GO is greener, safer, and lower in cost for construction industry. And the compressive strength of UHPC is slightly improved, while its flexural strength is significantly increased from 33 to 65%, demonstrating that the incorporation of GO can be an effective measure to enhance the flexural strength of UHPC under standard curing and steam curing. This can be associated with the improvement in bond strength between the MSFs and the matrix contributed by the improved interfacial microstructure, the higher friction increase, and the mechanical interlock at the interface between the MSFs and the bulk matrix, thanks to the addition of GO.

ЭКСПЕРИМЕНТАЛЬНОЕ ОБОСНОВАНИЕ ПРОЕКТНЫХ ХАРАКТЕРИСТИК ПАРОГЕНЕРАТОРА РУ БРЕСТ-ОД-300

The project BREST-OD-300 reactor plant (RP) with a fast neutron reactor and a lead coolant in the primary circuit is being developed in NIKIET JSC. As a steam generator (SG), a helical-type steam generator with coiled tubes with subcritical pressure water in the second circuit is considered. To substantiate the design characteristics of the secondary coolant at the State Research Center of the Russian Federation - IPPE, thermohydraulic tests of various SG models were carried out at the SPRUT stand Initially, tests were carried out on a model of a coiled steam generator consisting of two three-tube modules with a longitudinal lead flow around a three-tube bundle of coiled tubes. The influence of operating parameters on thermohydraulic characteristics and hydrodynamic stability is shown in the case of operation of one module, as well as in the joint operation of two models in the investigated range of operating parameters. At the second stage, tests of a standard steam generator model were carried out with lead flowing around 18 heat exchange tubes. In the multitube model, the downward movement of the heating coolant took place with the flow around the bundle of heat transfer tubes close to the transverse flow. Data were obtained on the hydrodynamic stability of steam generating tubes and the entire model as a whole when operating in the entire range of changes in operating parameters, which are necessary for creating a databank and further verification of calculation codes describing the ongoing thermohydraulic processes. During the tests in both models of the steam generator, there were no noises inherent in unstable operating modes of the circuit. No pulsations of water and steam temperature were found, respectively, in the inlet and outlet collectors. At high lead temperatures, the temperature of the superheated steam was always close to the lead inlet temperature. A series of works devoted to the study of heat transfer from the side of a lead coolant with a transverse flow around a package of heat exchange tubes in normal heat transfer modes and with freezing of lead has been completed. Studies have been carried out on the effect of oxygen concentration in lead on heat transfer.

Number of macrophages and transforming growth factor β expression in Citrus limon L. Tlekung peel oil-treated traumatic ulcers in diabetic rats

Purpose: To analyse the potential use of Citrus limon L. Tlekung peel oil in the treatment of traumatic ulcers in diabetic rats based on number of macrophages and transforming growth factor β (TGF-β) expression.
 Method: Standard steam distillation was performed to produce Citrus limon L. peel oil with its components subsequently analysed by gas chromatography-mass spectrometry (GC-MS). Diabetes was induced with streptozotocin (STZ) via administration of a single 50 mg/kg dose. A traumatic ulcer was subsequently induced with a 5 mm burnisher heated for 30 s and applied without pressure for 1 s to the lower labial mucosa of the animals. Citrus limon L. oil gel containing 3% carboxyl methyl cellulose sodium was then topically administered to the traumatic ulcer for a period of three or five days. TGF-β expression was analysed through immunohistochemical staining and the macrophage number calculated with haematoxylin-eosin stain.
 Results: The major identified compounds in Citrus limon L. peel oil include fumaric (31.78 %), dlimonene (17.38 %), z-citral (13.55 %), L-linalool (8.51 %), geraniol nerol (3.56 %), geraniol (2.94 %,), αterpineol (1.25 %) and γ-terpinene (1.03 %) together with other minor constituents. Treatment of traumatic ulcers with Citrus limon L peel oil produced higher number of macrophages and TGF-β expression (p = 0.000). Treatment over a period of five days also indicated higher expression of TGF-β and number of macrophages compared to that lasting three days with Citrus limon L peel oil (p = 0.000).
 Conclusion: Citrus limon L peel oil stimulates TGF-β expression and an increase of macrophage numbers in diabetic subjects during traumatic ulcer healing after three and seven days. Clinical application of Citrus limon L peel oil constitutes a potential therapy in the treatment of traumatic ulcers in diabetic subjects.

Coaxial micro-extrusion of a calcium phosphate ink with aqueous solvents improves printing stability, structure fidelity and mechanical properties

Micro-extrusion-based 3D printing of complex geometrical and porous calcium phosphate (CaP) can improve treatment of bone defects through the production of personalized bone substitutes. However, achieving printing and post-printing shape stabilities for the efficient fabrication and application of rapid hardening protocol are still challenging. In this work, the coaxial printing of a self-setting CaP cement with water and ethanol mixtures aiming to increase the ink yield stress upon extrusion and the stability of fabricated structures was explored. Printing height of overhang structure was doubled when aqueous solvents were used and a 2 log increase of the stiffness was achieved post-printing. A standard and fast steam sterilization protocol applied as hardening step on the coaxial printed CaP cement (CPC) ink resulted in constructs with 4 to 5 times higher compressive moduli in comparison to extrusion process in the absence of solvent. This improved mechanical performance is likely due to rapid CPC setting, preventing cracks formation during hardening process. Thus, coaxial micro-extrusion-based 3D printing of a CPC ink with aqueous solvent enhances printability and allows the use of the widespread steam sterilization cycle as a standalone post-processing technique for production of 3D printed personalized CaP bone substitutes. Statement of significanceCoaxial micro-extrusion-based 3D printing of a self-setting CaP cement with water:ethanol mixtures increased the ink yield stress upon extrusion and the stability of fabricated structures. Printing height of overhang structure was doubled when aqueous solvents were used, and a 2 orders of magnitude log increase of the stiffness was achieved post-printing. A fast hardening step consisting of a standard steam sterilization was applied. Four to 5 times higher compressive moduli was obtained for hardened coaxially printed constructs.This improved mechanical performance is likely due to rapid CPC setting in the coaxial printing, preventing cracks formation during hardening process.