Optimal Concentration Research Articles

Synthesis and photoluminescence properties of CaMgAl10O17:Sm3+ phosphor for n-UV solid-state lighting

The combustion method was used to synthesize CaMgAl10O17:Sm3+ phosphor. The scanning electron microscopy and photoluminescence properties of phosphors were thoroughly investigated. The emission spectrum has three distinct peaks at 563, 604 and 642 nm under 405 nm excitation, which is corresponding to the transitions 4G5/2→6H5/2, 4G5/2→6H7/2 and 4G5/2→6H9/2 of Sm3+ ions. The optimum concentration of CaMgAl10O17:Sm3+ phosphor was discovered to be 1 mole %, above which concentration quenching was observed. The CIE coordinates for the CaMgAl10O17 phosphor with Sm3+ ion doped are 604 nm (x=0.644, y=0.355) falling in the red region. According to the current findings, CaMgAl10O17:Sm3+ phosphors might be useful in the fields of near UV-excited solid-state lighting.

Municipal sewage sludge dewatering performance enhancement by ultrasonic cavitation and advanced oxidation: A case study.

The number of published literature on the effect of ultrasonic cavitation and advanced oxidation pretreatment on the dewatering performance of anaerobically digested sludge is very limited. This study aims at determining the optimum operating conditions of large-scale filtering centrifuges in wastewater treatment plants. The optimum dose of hydrogen peroxide, ultrasonic power, ultrasonic duration, ultrasonic pulse and particle size distribution for improved dewatering performance were determined in this study. In addition, shear stress-shear rate and viscosity-shear rate rheograms were developed to show the rheological flow properties for varying ultrasonic power and treatment duration. Optimum sonication power, time, pulse and amplitude were determined to be 14 W, 1 min, 55/5 and 20%, respectively. At a pH of 6.8, the optimum concentration of hydrogen peroxide was found to be 43.5 g/L. The optimum hydrogen peroxide dose in the combined conditioning experiments was determined to be 500 mg/L at a pH of 3. Under these optimum conditions, capillary suction time was reduced significantly by 71.1%. This study helps to reduce polymer consumption and provides the optimum pretreatment and dewatering operating conditions, and better monitoring and control in the dewatering unit has significant impact in the overall economy of wastewater treatment plants.

In-situ biosynthesized plant exudate gums‑silver nanocomposites as corrosion inhibitors for mild steel in hydrochloric acid medium

Natural gums due to availability, multifunctionality, and nontoxicity are multifaceted in application. In corrosion inhibition applications, their performance, in unmodified form is unsatisfactory because of high hydration rate, solubility issues, algal and microbial contamination, as well as thermal instability. This work attempts to enhance the inhibitive performance of Berlinia grandiflora (BEG) and cashew (CEG) exudate gums through various modification approaches. The potential of biogenic BEG and CEG gums−silver (Ag) nanocomposites (NCPs) for corrosion inhibition of mild steel in 1 M HCl is studied. The nanocomposites were characterized using the FTIR, UV–vis, and TEM techniques. The corrosion studies through the gravimetric and electrochemical (PDP, EIS, LPR, and EFM) analyses reveal moderate inhibition performance by the nanocomposites. Furthermore, the PDP results reveal that both inhibitors are mixed-type with maximum corrosion inhibition efficiencies (IEs) of 61.2 % and 54.2 % for BEG-Ag NCP and CEG-Ag NCP, respectively at an optimum concentration of 1.0 %. Modification of these inhibitors with iodide ion (KI) significantly increased the IE values to 90.1 % and 88.5 % for BEG-Ag NCP and CEG-Ag NCP at the same concentration. Surface observation of the uninhibited and inhibited steel samples using SEM/EDAX, 3D Surface profilometer, and AFM affirm that the modified nanocomposites are highly effective.

Enhanced antioxidant activity in Curcuma caesia Roxb. microrhizomes treated with silver nanoparticles

Curcuma caesia Roxb. is a highly valuable, endangered herb of therapeutic importance that resides in their rhizomes. In the present investigation, the effect of ½ strength liquid Murashige and Skoog (MS) medium supplemented with 1 mg/l Indole-3-butyric acid (IBA) and different sucrose concentrations (1.5%, 3%, 6%, 9%, or 12%) was studied on microrhizomes induction of C. caesia. The shoot length, root length and microrhizomes dry weight of C. caesia decreased significantly at 6% sucrose and above. When compared to the control (1.5% sucrose), the current water content significantly decreased at 6% sucrose. The optimum concentration for in vitro microrhizomes induction in C. caesia was 6% sucrose. Therefore for further experiments, the 6% sucrose was used. We also studied the effect of silver nanoparticles (AgNP) on microrhizome induction and antioxidant activity in C. caesia cultures. Field-grown C. caesia rhizomes extract was used in the green synthesis of AgNP. The synthesized AgNP was further characterized through scanning electron microscopy and X-ray diffraction. The AgNP, ranging from 0, 0.025, 0.05, 0.075 or 0.1 mg/l was supplemented in ½ strength liquid MS medium with 6% sucrose and 1 mg/l IBA. The MS medium with 0.05 mg/l AgNP found with significant morphological changes in C. caesia cultures (root number, root length and microrhizomes fresh weight). For the total phenolic and total terpenoids content estimation as well as for antioxidant activity analysis, the extracts of un-treated cultures (6% sucrose + 1 mg/l IBA, without AgNP), AgNP treated cultures (6% sucrose + 1 mg/l IBA with 0.025 and 0.05 mg/l AgNP) was used. The 0.025 and 0.05 mg/l AgNP enhanced the phenolic and terpenoid content in the cultures compared to the field-grown mother plant. The antioxidant activity of the cultures treated with AgNP also increased compared to un-treated cultures and field-grown mother plant. The Gas Chromatography-Mass Spectrometry (GC-MS) analysis revealed that the extract treated with 0.05 mg/l AgNP had increased production of monoterpene (camphor) and sesquiterpenes (β-elemenone and curcumenone). These increased terpenes could be responsible for the enhanced antioxidant activity of C. caesia cultures.

99 Phytochemicals as medical growth promoter replacement on growth performance in wean to finisher pigs

Abstract Stress can disturb the ecological balance of the microbiota residing in the GI tract of piglets leading to dysbiosis. This unhealthy imbalance causes the piglets to be more vulnerable to deleterious effects induced by opportunistic pathogens. Antibiotics and increased zinc levels have often been used as dietary supplements to help minimize these stressors in pigs. Emerged evidence suggests that phytochemicals can promote growth by boosting nutrient digestibility, immune cell activity, and possessing bactericidal characteristics. We evaluated two phytochemicals formulations as safer and more environmentally friendly dietary alternatives for postweaning pigs. We used a total of 240 weaned piglets [average body weight (BW): 6.26 ± 0.36 kg] which were blocked (n = 8) by BW and then randomly assigned to 1 of 5 dietary treatments. Treatments were negative control (NC), Mecadox 10 (Phibro Animal Health Corp., Teaneck, NJ) + ZnO positive control (PC), Mecadox + phytochemical 1 (Lippia origanoides; Phyt1+AB), phytochemical 1 alone (Phyt1), and phytochemical 2 (Lippia origanoides + Rosmarinus officinalis + Sodium humates; Phyt2). The pigs were fed a 7-phase feeding regime: Nursery phase (NP) 1, 2, and 3, Grower phase 1 and 2 (Grower), and Finisher phase 1 and 2 (Finisher). The antibiotic and ZnO were withdrawn at the end of NP3, while Phyt1 and Phyt2 remained in feed throughout the entire study period. Data were analyzed using Mixed procedure of SAS (Cary, NC) with treatments as the main effect and BW blocks as the random effect. Pen was the experimental unit. Supplemental phytochemicals (Phyt1+AB, Phyt1, Phyt2) had greater average daily gain (ADG) and gain to feed ratio (G:F) during NP1 when compared with the pigs fed NC, but were still less than pigs fed PC (P < 0.0001). Pigs fed PC maintained a greater ADG during nursery overall than NC, Phyt1, and Phyt2 with pigs fed Phyt1+AB as intermediate (P < 0.0001). Phyt1 exerted an adverse effect (Phyt1+AB and Phyt1) on ADG during relatively mild stress in Grower phase (Grower, P = 0.0146), and resulted in the lighter BW at the end of Grower than pigs fed PC (P = 0.031). Notably, the pigs experienced summer heat stress during the Finisher phase, of which, the presence of phytochemicals minimized. Pigs fed Phyt2 had a greater ADG during Finisher than pigs fed NC with pigs fed PC, Phyt1+AB, and Phyt1 as intermediates (Finisher, P = 0.0419), while pigs fed Phyt1+AB and Phyt2 had greater G:F when compared with pigs fed PC and NC with pigs fed Phyt1 as intermediate (Finisher, P = 0.0032). Collectively, we demonstrated that phytochemical 2 can be a safer medication diet replacement to help pigs sustain weaning and heat stress. The mode of action and the optimum concentrations of these phytochemicals to achieve maximum benefits need further investigation.

Development and Validation of Fast and Sensitive RP-HPLC Stability-Indicating Method for Quantification of Piroxicam in Bulk Drug.

A simple, rapid, sensitive, and cost-effective green solvent-assisted reverse-phase high-performance liquid chromatographic technique, coupled with a photodiode array detector, was developed and validated for the estimation of piroxicam (PRXM). The chromatographic separation was achieved by using a C-18 (250 × 4.6) mm, 5-μm stationary phase and a mobile phase consisting of methanol and 0.1% ortho-phosphoric acid in water in a ratio of (80:20) v/v at a flow rate of 1ml/min. The detection was carried out at a wavelength of 254nm with a constant injection volume of 10μL throughout the analysis. The calibration curve was observed to be linear over the optimum concentration range of 50-300μgmL-1, with an R2 value of 0.9995. The developed method was validated as per the International Council for Harmonisation (ICH) Q2 (R1) guideline. Various parameters like selectivity/specificity, accuracy/recovery, linearity, precision, detection limit, quantitation limit, robustness and stability of analyte in solution were performed for the method validation. The PRXM was evaluated under stressed conditions, including acidic, basic, oxidative, thermal and photolytic, as per ICH Q1 (R2) guidelines. Significant degradation was observed in acidic and basic degradation conditions. Conversely, the drug substance showed stability when exposed to oxidative, photolytic and thermal degradation conditions.

Evaluation of dynamic behaviors in varied swirling flows for high-pressure offshore natural gas supersonic dehydration

The dehydration process involving the supersonic separator (SS) proves advantageous for the high-pressure offshore natural gas industry. By adeptly harnessing energy conversion from pressure to cold energy, the SS efficiently condenses and separates water vapor. In this process, swirl strength is the critical factor. To clarify the influences of different swirl strengths on flow field characteristics, droplet behavior, film formation, separation performance, and energy conversion of the SS in high-pressure offshore natural gas, a computational model was established and validated in this study. The prediction results of three representative thermodynamic models were compared in the Laval nozzle and the SS. The results show that the NIST real gas model possesses the highest prediction accuracy compared to the other two models. The inlet pressure has a significant influence on the separation performance of the SS. The maximum values of water vapor removal rate, dew point depression, optimum droplet diameter, and optimum droplet concentration can increase to 81.75 %, 37.65 K, 3.3 μm, and 0.0026 kg s−1, respectively. The swirl strength significantly influences separation performance and energy conversion. Notably, the normal swirl strength achieves the maximum separation performance, showcasing a water vapor removal rate surpassing that of strong swirl strength by 18.03 %. The temperature drop exhibits maximum deviations of 20.70 % and 12.51 % compared with weak and strong swirl strengths. Moreover, the utilization of supersonic separators in the pre-dehydration process results in a substantial cost reduction of $ 6,691,060 over a 20-year period.

Synthesis and characterization of a new eco-friendly dopamine derivative schiff base as an effective corrosion inhibitor for mild steel in acidic environment

The natural corrosion inhibitor behaviour of a newly synthesized dopamine derivative Schiff base (4-DBAB) has been inspected on mild steel in aggressive 1 M HCl using linear polarization, electrochemical impedance spectroscopy and potentiodynamic polarization techniques. The Schiff base was synthesized by eco-friendly pathway. Characterization of the synthesized new non-toxic inhibitor was performed using FT-IR and 1H-NMR spectroscopy techniques. The anti-corrosive efficiencies at optimum concentration of 4-DBAB inhibitor was 87.4% after 1 h and 98.4% after 120 h by impedance technique in acidic solution. The potential of zero charge of mild steel was also determined to elucidate the inhibition mechanism in the presence of the highest 4-DBAB solution. The atomic force microscopy and field emission scanning electron microscopy researches performed on surface morphology to provide additional support on the interaction between the mild steel surface and 4-DBAB molecules. Adsorption behaviour of the inhibitor was also studied at different durations by experimental inhibition results and showed the Langmuir isotherm involving chemisorption. Highlights A new dopamine-derived Schiff base (4-DBAB) with natural and environmentally friendly corrosion inhibition properties was synthesized. (Synthesis of eco-friendly compound). 4-DBAB demonstrated a high anti-corrosive efficiency after 120 hours in aggressive 1M HCl, as determined by impedance technique. (Exceptional corrosion inhibition). The determination of the potential of zero charge of mild steel provided insights into the inhibition mechanism in the presence of the highest 4-DBAB solution. (Mechanism elucidation). AFM and FE-SEM studies on surface morphology supported the interaction between the mild steel and 4-DBAB molecules, affirming its corrosion inhibition properties. (Surface interaction analysis).

Exceptional contribution of iron nanoparticle and aloe vera biomass additives to biogas production from anaerobic digestion of waste sludge

This study aims to investigate, for the first time, the improvement of the anaerobic digestion (AD) performance of waste sludge (WS) by utilizing Aloe vera waste (AVW) and Fe0 nanoparticles. Accordingly, a series of biogas generation experiments were conducted at different mixing ratios (AVW:WS = 0:1, 1:1, 2:1, and 3:1), to find out the optimum ratio for maximizing biogas generation. To gain insights into the improved biogas generation by the addition of AVW, pH value was monitored during the fermentation process and adjusted to different initial values (3, 7, and 12). Moreover, the effect of different concentrations (10 and 50 mg/L) and dosing times (0, 6, 12, 24, 48, and 96 h) of Fe0 nanoparticles on the digestion of the optimized ratio (AVW:WS = 2:1) were investigated. Results showed that the optimum ratio (AVW:WS = 2:1) resulted in improving biogas and methane generation by 62.5 % and 96.0 %, respectively, which is an excellent improvement rate of biogas and methane generation compared with the previously reported values in the literature. The addition of Fe0 at the optimum concentration (10 mg/L) and dosing time (12 h) to the optimized ratio (AVW:WS = 2:1) resulted in enhancing methane generation by 146.9 %.

Integrating low salinity water, surfactant solution, and functionalized magnetite nanoparticles with natural acidic groups for enhanced oil recovery: Interfacial tension study

In recent years, nanoparticles (NPs) have become a popular choice for improving oil recovery through enhanced oil recovery (EOR) methods. NPs can enhance oil recovery by reducing interfacial tension (IFT), altering wettability, and decreasing the mobility ratio. In this study, magnetic NPs with acidic groups (tartaric acid and malic acid), which are natural acids found in fruits such as grapes and apples, were synthesized and functionalized to reduce the IFT between oil and water. Various characterizations tests, including zeta potential (ZP), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), dynamic light scattering (DLS), field emission scanning electron microscopy (FE-SEM), and energy dispersive X-ray analysis (EDAX), were used to determine the properties of NPs. Afterwards, the IFT behaviour of crude oil and aqueous solutions, containing surfactant sodium dodecyl sulfate (SDS), two types of salts namely sodium chloride (NaCl) and sodium sulfate (Na2SO4), and functionalized magnetite NPs with tartaric acid and malic acid were investigated. Two crude oils were used in this study: light (A) and heavy (B). The results showed that increasing salt concentration decreases the IFT for crude oils down to an optimum point (20000 ppm for both salts), after which the IFT increases with increasing salt concentration. The presence of functionalized Fe3O4@Tartaric acid NPs (300 ppm) in the aqueous solutions containing salts at their optimum concentration (20000 ppm) and SDS (300 ppm) can decrease the IFT more significantly than that of Fe3O4 and Fe3O4@Malic acid for both crude oils. This is due to higher stability and higher ZP of functionalized Fe3O4@Tartaric acid NPs compared to Fe3O4@Malic. The IFT for oil A decreases from 20.8 mN/m to 2.87 mN/m for light crude oil and from 32.96 mN/m to 1.91 mN/m for heavy crude oil. The IFT for heavy crude oil was more reduced than that of light crude oil, which was due to the presence of asphaltene, resin, and other surface-active agents in heavy crude oil, which can act as a natural surfactant in oil and help reducing the IFT.

Stability, Thermophysical, Optical and Photothermal Properties of ZnO Nanofluids with Added Anionic/Cationic Mixed Surfactants

Metal oxide nanofluid is a new type of heat transfer medium with good thermal performance, which can be used to improve the heat collection and photothermal conversion performance of the collector. The development of new nanofluids with excellent stability, thermophysical and photothermal properties is very important for solar thermal utilization. In this paper, the ZnO nanofluids with SDS/CTAB mixed surfactants were prepared by two-step method. Their stability, thermophysical, optical and photothermal properties were studied based on experimental data. Then, the optimum concentration and preparation conditions of the proposed ZnO nanofluids adding SDS/CTAB with good photothermal performance were obtained. The results showed that the ZnO nanofluids with the addition of SDS/CTAB hybrid surfactant has good dispersion stability and its thermal conductivity can reach 0.772 W/(m·K). The transmittance was as low as 19.0.10% and the extinction coefficient was as high as 7.25 cm−1. In addition, the addition of the SDS/CTAB hybrid surfactant caused the ZnO nanofluids to exhibit better photothermal conversion efficiency up to 87%, which was superior to that of the control group with the addition of other surfactants. Therefore, ZnO nanofluids with the addition of SDS/CTAB have great potential as DASC working fluids.

Synthesis and upconversion luminescence properties of Ho3+-Yb3+ co-doped glass ceramics containing LiGd(WO4)2

Ho3+-Yb3+ co-doped glass ceramics containing LiGd(WO4)2 were prepared by melt crystallization method. By using the methods of differential scanning calorimetry (DSC), X-ray diffraction (XRD), transmittance, and scanning electron microscopy (SEM), the optimal heat treatment condition for the samples was identified to be 580 °C/140 min. In these conditions, the transmittance of glass ceramic is about 75 % in the 380–780 nm range. In the upconversion emission spectra, strong green emission (543 nm) and red emission (650 nm) due to 5F4/5S2, 5F5→5I8 transitions are observed at 980 nm excitation. Additionally, the optimum doping concentrations of Ho3+ and Yb3+ were 0.12 % and 0.4 %. The crystal field changes around dopant ions were analyzed using J-O theory and Eu3+ probe to explain the up-conversion luminescence enhancement of glass ceramics containing LiGd(WO4)2. The chrominance coordinates of 0.12 % Ho3+-0.4 % Yb3+ co-doped glass ceramics are located in the green light region, and the color purity is 95.6 %. In summary, Ho3+-Yb3+ co-doped transparent glass ceramics containing LiGd(WO4)2 have potential applications in infrared detection and green solid-state lasers.

Papain assisted preparation of chitosan: Feasibility study for candidate in-house reference material and antibacterial agent

Chitosan preparation assisted by papain was carried out to reduce the use of chemicals in the extraction of chitosan. This research aims to modify the chitosan extraction method to be more environmentally friendly and improve the physicochemical properties. Chitosan preparation is carried out in 4 main steps which include depigmentation, demineralization, deproteination, and deacetylation. Deproteination uses papain extract with varying concentrations of 5 - 25% for 7–11 h. The results of characterization using FTIR confirmed that the chitosan preparation was successful. The characteristic FTIR spectra are shown by the presence of a wideband at 3000–3600 cm−1 from stretching vibrations of the –OH and –NH and a peak at 1500–1700 cm−1 which indicates the N–H and CO stretching vibrations of the amino group. The XRD pattern verifies the peak characteristic of chitosan at an angle of 2 theta 9.39, 19.16, 25.96, 32.31, and 34.17°. SEM-EDX imaging shows the chitosan morphology whose particle arrangement is a uniform, smooth, and non-aggregated arrangement of its particles with the main composition of chitosan consisting of carbon, oxygen, and nitrogen atoms. The optimum papain concentration of 25% and deproteination time of 7 h with a deacetylation degree of 70.83% are the recommended conditions for chitosan preparation. The extracted chitosan was confirmed to satisfy the homogeneity and stability requirements as a candidate for in-house reference material. The homogeneity test results of the MSB and MSW values obtained F-test < F-critical (2.7858 < 3.1789) and the results of ANOVA (α = 95%, df = 9) obtained F-test < F-critical (0.4466 < 4.4139). The chitosan produced is validated as a stable material with a value of | X̅i - X̅HM | < 0,3 x nIQR (0.2501 < 1.7345). The chitosan produced has antibacterial activity against P. acnes, S. aureus, K. pneumoniae, P. aeruginosa, and E. coli.

Postsurgical utility of copeptin for the prediction of postoperative arginine vasopressin deficiency.

Arginine vasopressin deficiency (AVD) following neurosurgical procedures for pituitary disorders is common and can delay discharge. Copeptin, a stable surrogate marker of arginine vasopressin, may predict postoperative AVD. The authors' aim was to assess the optimal postoperative sampling time and cut-point concentration of copeptin to predict the development of postsurgical AVD. Adults without preexisting AVD who were undergoing surgery for a pituitary lesion between February 2020 and April 2022 were eligible for study inclusion. Two samples were drawn from each patient postoperatively to assess the copeptin concentration using an immunofluorescent assay. Samples were denoted as "early" (within 6 hours of extubation) or "postoperative day 1" (POD1; within 10-30 hours of extubation). Patients were evaluated for the development of AVD. One hundred ninety-two patients (54.2% female) with a median age of 54.5 years (IQR 39.8-67.0 years) were included in the study. The median copeptin concentration at both time points was significantly lower in those with AVD (transient or permanent; n = 22, 11.5%) than in those without (early: 4.9 vs 18.7 pmol/L, p < 0.001; POD1: 3.4 vs 4.9 pmol/L, p < 0.001) but did not differ in those who developed transient versus permanent AVD. The optimal copeptin cut point for the prediction of AVD was < 8.5 pmol/L for early samples (sensitivity 0.70, specificity 0.80, positive predictive value [PPV] 0.29, negative predictive value [NPV] 0.96) and < 4.3 pmol/L for POD1 samples (sensitivity 0.82, specificity 0.63, PPV 0.22, NPV 0.96). In early samples, a copeptin cutoff of 22.9 pmol/L increased the sensitivity for the detection of AVD to 95% with an NPV of 99%. The proportion of patients who had AVD was higher (60.0% vs 8.8%, p < 0.001) and the copeptin concentration lower (early: 4.3 vs 17.0 pmol/L, p < 0.001; POD1: 2.7 vs 4.9 pmol/L, p < 0.001) among those who had undergone surgery for a craniopharyngeal duct pathology versus a pituitary adenoma. Although copeptin was lower in patients with persistent Cushing's disease than in those in remission, the difference did not reach statistical significance (early p = 0.11, POD1 p = 0.52). Furthermore, the copeptin concentration could not predict the development of syndrome of inappropriate secretion of antidiuretic hormone. Patients without AVD who had received stress dose steroids intraoperatively had lower median early copeptin (11.7 vs 19.1 pmol/L, p = 0.027). In early postoperative copeptin samples, the optimal copeptin cut point for AVD diagnosis was < 8.5 pmol/L, and a level > 22.9 pmol/L had predicative utility in excluding AVD. Caution should be used when interpreting copeptin results, as patients administered glucocorticoids intraoperatively without AVD had lower median copeptin concentrations.

Improving salidroside stability using water-in-oil-in-water emulsion with whey protein isolate: Formation and characterization

A water-in-oil-in-water (W/O/W) emulsion for the encapsulation of salidroside (Sal) was constructed. This study aimed to detect the impact of whey protein isolate (WPI) on the microstructure and stability of Sal W/O/W emulsion, which was prepared by two-step emulsification. First, Sal and sodium alginate (SA) were added to the inner water phase, and polyglycerol polyricinoleate (PGPR) was added to the oil phase to prepare a water-in-oil (W/O) emulsion. Second, different concentrations of WPI were added to the outer water phase containing SA to prepare a Sal W/O/W emulsion. The microstructure, stability, moisture distribution, rheological properties, and encapsulation efficiency of Sal were detected. The results showed that the particle size and the size distribution range became smaller and narrower with increasing WPI concentration. When the concentration of WPI was greater than 2%, the double-layer structure remained stable over 28 days of storage at 4 °C. Moreover, when the WPI concentration reached 4%, the entrapment efficiency of Sal was the highest. These results indicated that the optimum concentration of WPI was 4%.

Enhancing microbial-induced carbonate precipitation (MICP) sand consolidation with alkali-treated jute fibers

Recent research has focused on reinforcing sand consolidated through microbial-induced carbonate precipitation (MICP) with alkali-treated fibers to enhance its mechanical properties and mitigate brittleness. This research investigated how modified fiber affected the microstructure and properties of MICP solid sand. The fiber content (0, 0.5, 1, 3, and 5%), pretreatment concentration (0, 1, 5, 10, and 20%), pretreatment time (0, 0.5, 1, 2, and 4 h), and pretreatment temperature (25, 35, 45, and 55 °C) required for the experiment were determined by MICP testing. The interactions between fiber, sand, and calcium carbonate(CaCO3) were analyzed by calcium carbonate content(CaCO3(%)), unconfined compressive strength (UCS), environmental scanning electron microscopy (ESEM), and X-ray diffraction (XRD). The specimen without added fiber had a UCS of 2.13 MPa, the UCS of the added fiber sample was 2.8 MPa, which was 31.46% more than that of the specimen without added fiber, and the UCS of the specimen with added alkali-treated fiber was 3.62 MPa, which was 70% more than that of the specimen without added fiber and 28.57% more than that of the added untreated fiber. The optimum content of jute fibers was 0.5%, and the optimum concentration of alkali treatment of jute fibers was 10% for one hour.

Properties and microstructure regulation of electrodeposited ultra-thin copper foil in a simple additive system

Hydroxyethyl cellulose (HEC) has been commonly used in a variety of complex formulations for acid copper plating. However, the roles of HEC acting in acid copper plating still lacks of systematic investigation. To explore the efficacy of HEC in the deposition of the ultra-thin electrodeposited copper foil (ED-Cu), we designed a simple formulation system, in which HEC was used as the single organic additive. Using electron backscatter diffraction (EBSD), microstructures of the prepared ED-Cu was comprehensively investigated. The results showed that the ED-Cu was characterized by a mixed distribution of columnar and equiaxed crystals. Grain morphology, dislocation density and crystal orientation of the ED-Cu could be regulated by HEC concentration. According to the cyclic voltammetry (CV) and chronoamperometry (CA) results, the introduction of HEC between 0–200 ppm led to a polarizing effect, which marginally increased with the HEC concentration. Meanwhile, the increase of HEC concentration enhanced the nucleation rates of copper and reduced the grain size during instantaneous nucleation. The introduction of the HEC also altered the preferred orientation of the ED-Cu foil. Mechanical results showed that the optimum concentration of HEC addition was 125 mg l−1.

Effect of activator concentration on setting time, workability and compressive strength of sustainable concrete with alkali-activated slag binder

The global need to reduce carbon dioxide (CO2) emissions prompted studies on sustainable alternatives to conventional concrete made with ordinary Portland cement (OPC) binders. Alkali-activated ground granulated blast furnace slag (GGBS) is a promising sustainable to OPC in terms of the impact on the environment and reduction of CO2 emissions. Concretes and mortars made with alkali-activated binders demonstrate promising fresh and mechanical properties. This article presents the findings of an experimental study investigating the fresh and mechanical properties of mortar using alkali-activated GGBS binder. The activators used were sodium silicate (Na2SiO3) and sodium hydroxide (NaOH) solution with 6 M, 8 M, 10 M, and 12 M molarities. The study assessed their initial setting time, workability, and 28-day compressive strength. The study evaluated the effect of partial replacement of GGBS with 5 % silica fume. The compressive strength was determined after 28 days of curing in three different environments: 1) ambient air temperature, 2) water submersion, and 3) water immersion for 7 days followed by 21 air curing in ambient temperature. The results showed an increase in compressive strength with higher NaOH concentration but a corresponding decrease in initial setting time and flowability. Depending on the curing method, efflorescence, and blue-green pigmentation were seen during the physical assessment of the samples. The highest 28-day compressive strength was 67.5 MPa when the NaOH activator molarity was 10 mol/L which represents an optimum concentration for strength development. Replacing 5 % of the GGBS binder with silica fume resulted in a decrease in the 28-day compressive strength and workability without affecting the initial setting time.

Critical evaluation of effects of polymer concentrations on the set time and compressive strength of cement slurries

Thickening time and compressive strength of cement slurry are very critical parameters in well cementing. Thickening or pump time and compressive strength of cement slurries are greatly affected by the slurry weight and temperature. Conventional Lead slurries usually require extenders such as bentonite and some polymers to stabilize the slurry and minimize excessive free fluid. The low slurry weight of lead slurries usually give rise to long pumping or set time and low compressive strength. Some of the polymers also retard the setting of the cement slurry. Therefore, this study focuses on the investigation of the performance of sodium silicate in comparison with gypsum and polyanionic cellulose (PAC-R) as extenders for cement slurries. The concentration of the light weight additives tested were 0%, 1.5% and 3.0% by weight of cement (bwoc) for 12.5ppg slurry using sea water. The slurry stability, compressive strength and quick set time were determined at room temperature. The higher the concentration of the lightweight additives, the more stable is the slurry, best stability was observed for recipe with sodium silicate while the slurry with PAC-R could not mix at 3% bwoc. At the lower concentrations, for sodium silicate, compressive increases and decreases for gypsum. The mixture with PAC-R had zero compressive strength. The gypsum has retarding effect on the slurry while the sodium silicate has accelerating effect. Conclusively, sodium silicate and gypsum powder performed very well as cement extender at optimum concentration, with the former showing the best performance and impacting accelerating properties that will be useful fort low temperature cementing.

Production of oil palm mesocarp fiber-based hydrogel using selected cross-linking acids

Abstract Over the years, studies showed that hydrogels can be produced through synthetic route to overcome the limitations in obtaining natural-based hydrogels. Biomass resources offer potential alternatives as renewable feedstocks due to their outstanding biodegradability and biocompatibility. Oil palm mesocarp fiber (MF) is the biomass residue obtained after the pressing of palm fruits during palm oil extraction. There is approximately 11 % MF generated from palm fruits after oil extraction. However, the applications of MF are limited. This study aimed to investigate the development of hydrogels from holocellulose MF instead of commonly used cellulose which involving several pretreatment steps, through acid cross-linkers. Holocellulose MF was selected as polymer for chemical cross-linking with two inexpensive and nontoxic hydrophilic organic acids, citric acid and acetic acid for hydrogel production. Comparison study was carried out to evaluate the physicochemical properties, and degree of swelling, as well as gel content in different media for both acids in the production of hydrogel from holocellulose MF. Results indicated that the optimum concentrations of citric acid and acetic acid for gel content and degree of swelling were 5 M and 2 M, respectively. Both optimized hydrogels exhibited comparable profiles in terms of morphology, thermal stability and functional groups, in addition to showing similar degree of swelling profile in different media, i.e., salt solution, acidic, neutral to alkaline, implying their distinctive characteristics. In summary, holocellulose MF is suitable for the production of hydrogel with citric acid and acetic acid as crosslinkers for different desired applications.