Predicting the Compressive Strength of Concrete Containing Fly Ash and Rice Husk Ash Using ANN and GEP Models

Climate change has become trending news due to its serious impacts on Earth. Initiatives are being taken to lessen the impact of climate change and mitigate it. Among the different initiatives, researchers are aiming to find suitable alternatives for cement. This study is a humble effort to effectively utilize industrial- and agricultural-waste-based pozzolanic materials in concrete to make it economical and environmentally friendly. For this purpose, a ternary blend of binders (i.e., cement, fly ash, and rice husk ash) was employed in concrete. Different variables such as the quantity of different binders, fine and coarse aggregates, water, superplasticizer, and the age of the samples were considered to study their influence on the compressive strength of the ternary blended concrete using gene expression programming (GEP) and artificial neural networking (ANN). The performance of these two models was evaluated using R², RMSE, and a comparison of regression slopes. It was observed that the GEP model with 100 chromosomes, a head size of 10, and five genes resulted in an optimum GEP model, as apparent from its high R² value of 0.80 and 0.70 in the TR and TS phase, respectively. However, the ANN model performed better than the GEP model, as evident from its higher R² value of 0.94 and 0.88 in the TR and TS phase, respectively. Similarly, lower values of RMSE and MAE were observed for the ANN model in comparison to the GEP model. The regression slope analysis revealed that the predicted values obtained from the ANN model were in good agreement with the experimental values, as shown by its higher R² value (0.89) compared with that of the GEP model (R² = 0.80). Subsequently, parametric analysis of the ANN model revealed that the addition of pozzolanic materials enhanced the compressive strength of the ternary blended concrete samples. Additionally, we observed that the compressive strength of the ternary blended concrete samples increased rapidly within the first 28 days of casting.

Impact of end-capped modification of MO-IDT based non-fullerene small molecule acceptors to improve the photovoltaic properties of organic solar cells

Density functional theory, along with its time dependent computational approach were employed in order to fine tune the photovoltaic attributes along with the efficiency of the MO-IDIC-2F molecule. Thus, five new molecules were designed by substitution of the different notable acceptor fragments in the MO-IDIC-2F molecule, along with the addition of the "[1, 2, 5] thiadiazolo[3,4-d] pyridazine" spacer moieties between donor core and newly substituted acceptor groups. In this research work, various photovoltaic properties, which could affect the efficiency of an organic chromophores, such as bandgap, oscillator strength, dipole moment, binding energy, light-harvesting efficiency, etc. were studied. All the newly proposed molecules demonstrated significantly improved outcomes in comparison to that of the reference molecule, in their absorption spectrum, excitation, as well as binding energy values, etc. In order to confirm the results of optoelectronic properties, density of states, transition density matrix, and electrostatic potential analyses of molecules were also performed, which supported our computational findings. All of the results confirmed the high potential of all the newly proposed molecules for the development of improved OSCs.

Prediction of Axial Capacity of Concrete Filled Steel Tubes Using Gene Expression Programming

The safety and economy of an infrastructure project depends on the material and design equations used to simulate the performance of a particular member. A variety of materials can be used in conjunction to achieve a composite action, such as a hollow steel section filled with concrete, which can be successfully utilized in the form of an axially loaded member. This study aims to model the ultimate compressive strength (P_u) of concrete-filled hollow steel sections (CFSS) by formulating a mathematical expression using gene expression programming (GEP). A total of 149 datapoints were obtained from the literature, considering ten input parameters, including the outer diameter of steel tube (D), wall thickness of steel tube, compressive strength of concrete (f_c'), elastic modulus of concrete (E_c), yield strength of steel (f_v), elastic modulus of steel (E_s), length of the column (L), confinement factor (ζ), ratio of D to thickness of column, and the ratio of length to D of column. The performance of the developed models was assessed using coefficient of regression R², root mean squared error RMSE, mean absolute error MAE and comparison of regression slopes. It was found that the optimal GEP Model T3, having number of chromosomes N_c = 100, head size H_s = 8 and number of genes N_g = 3, outperformed all the other models. For this particular model, R²_overall equaled 0.99, RMSE values were 133.4 and 162.2, and MAE = 92.4 and 108.7, for training (TR) and testing (TS) phases, respectively. Similarly, the comparison of regression slopes analysis revealed that the Model T3 exhibited the highest R² of 0.99 with m = 1, in both the TR and TS stages, respectively. Finally, parametric analysis showed that the P_u of composite steel columns increased linearly with the value of D, t and f_y.

Prediction of Rapid Chloride Penetration Resistance to Assess the Influence of Affecting Variables on Metakaolin-Based Concrete Using Gene Expression Programming

The useful life of a concrete structure is highly dependent upon its durability, which enables it to withstand the harsh environmental conditions. Resistance of a concrete specimen to rapid chloride ion penetration (RCP) is one of the tests to indirectly measure its durability. The central aim of this study was to investigate the influence of different variables, such as, age, amount of binder, fine aggregate, coarse aggregate, water to binder ratio, metakaolin content and the compressive strength of concrete on the RCP resistance using a genetic programming approach. The number of chromosomes (N_c), genes (N_g) and, the head size (H_s) of the gene expression programming (GEP) model were varied to study their influence on the predicted RCP values. The performance of all the GEP models was assessed using a variety of performance indices, i.e., R², RMSE and comparison of regression slopes. The optimal GEP model (Model T3) was obtained when the N_c = 100, H_s = 8 and N_g = 3. This model exhibits an R² of 0.89 and 0.92 in the training and testing phases, respectively. The regression slope analysis revealed that the predicted values are in good agreement with the experimental values, as evident from their higher R² values. Similarly, parametric analysis was also conducted for the best performing Model T3. The analysis showed that the amount of binder, compressive strength and age of the sample enhanced the RCP resistance of the concrete specimens. Among the different input variables, the RCP resistance sharply increased during initial stages of curing (28-d), thus validating the model results.

Synthesis, Characterization, DPPH, Ferric Reducing and Ferrous Ion-Chelating Activities of Isophthalate Schiff Bases

Aims:

Synthesis of bioactive compounds has antioxidant potential.

Background:

All aerobic bodies including human beings, have an antioxidant defense systems that protects them from oxidative damage, and many enzymes to remove or heal damaged molecules. However, this normal antioxidant mechanism can be incompetent, and hence dietary intakes of antioxidant compounds are important.

Objective:

Synthesis of isophthalate Schiff base derivatives 1-14 and screened for their antioxidant activities (DPPH, ferrous ion Fe2+ chelating and ferric Fe3+ reducing activities)

Method:

Schiff bases 1-14 were synthesized by two-step reaction scheme. First step was the esterification reaction of isophthalic acid followed by the hydrazinolysis of methyl isophthalate to afford isophthalic dihydrazide. Second step was the condensation reaction of isophthalic dihydrazide with a variety of benzaldehydes to afford Schiff bases 1-14. Synthetic compounds were characterized by spectroscopic techniques such as 1H-NMR and EI-MS.

Result:

Compounds were screened for their antioxidant activities (DPPH, ferrous ion Fe2+ chelating and ferric Fe3+ reducing activities). Most of the compounds showed significant antioxidant activities. A structure-activity relationship has also been discussed.

Conclusion:

Most of the synthetic isophthalate Schiff bases were found to be moderately active when screened for their antioxidant activities by three assays such as DPPH radical scavenging, ferrous ion-chelating and ferric reducing activities. These moderately active compounds can serve as lead molecules for further modification in the structure in order to identify more powerful antioxidant agents.

Impact of various heterocyclic π-linkers and their substitution position on the opto-electronic attributes of the A–π–D–π–A type IECIO-4F molecule: a comparative analysis

To investigate the consequence of different substitution positions of various π-linkers on the photovoltaic properties of an organic solar cell molecule, we have introduced two series of six three-donor molecules, by the substitution of some effective π-linkers on the A–π–D–π–A type reference molecule IECIO-4F (taken as IOR). In series “a” the thienyl or furyl bridge is directly linked between the donor and acceptor moieties, while in series “b” the phenyl ring of the same bridge is working as the direct point of attachment. The frontier molecular orbitals, density of states, transition density matrix, molecular electrostatic potential surfaces, exciton binding energy, excitation energy, wavelength of maximum absorption, open-circuit voltage, fill factor, and some other photovoltaic attributes of the proposed molecules were analyzed through density functional theory (DFT) and its time-dependent (TD) approach; the TD-DFT method. Though both series of newly derived molecules were a step up from the reference molecule in almost all of the studied characteristics, the “a” series (IO1_a to IO3_a) seemed to be better due to their desirable properties such as the highest maximum absorption wavelength (λ_max), open-circuit voltage, and fill factor, along with the lowest excitation and exciton dissociation energy, etc. of its molecules. Also, the studied morphology, optical characteristics, and electronic attributes of this series of proposed molecules signified the fact that the molecules with thienyl or furyl ring working as the direct link between the acceptor and donor molecules showed enhanced charge transfer abilities, and could provide a maximum quantum yield of the solar energy supplied.

We have introduced two series of six three-donor molecules, by the substitution of some effective π-linkers on the A–π–D–π–A type reference molecule IECIO-4F (taken as IOR) for efficient organic solar cells.

Marginal quality water arbitrated essential oil contents in metal hoarded flower petals of scented roses

Climate change and the consequent alteration in agricultural circumstances enhance the susceptibility of fresh water use particularly in water-scarce regions. Marginal quality water reuse is a common alternative practice but possible perils of metal accretion in plant parts are mostly ignored. The present research aimed to probe the impact of treated wastewater (TWW) and untreated wastewater (UTWW) on metal accumulation in flower petals and their influence on essential oil contents of fragrant Rosa species (R. Gruss-an-teplitz, R. bourboniana, R. centifolia, R. damascena) in a peri-urban area of Faisalabad, Pakistan during January, 2017 to December, 2018. The mineral and chemical contents in canal water (CW) and TWW were less than recommended levels of national environmental quality standards (NEQS) for wastewater of Pakistan. The experimentally UTWW possessed higher electrical conductivity (EC), biological and chemical oxygen demand (BOD and COD), and some metals (Pb, Co, Cr) that were above the permissible levels. The experimental data revealed that except Cr other metals contents in the flower petals were less than the WHO recommended limits (for medicinal plants) under experimental irrigation regimes. Rosa centifolia and R. damascena possessed higher metal i.e. Zn, Cu, Pb, Cr, Co contents while Fe and Ni contents were higher in R. Gruss-an-Teplitz and R. bourboniana respectively. There were twelve constituents which were detected in essential oil by gas chromatography. Major constituents were phenyl ethyl alcohol, citronellol, geranyl acetate, γ- undelactone, methyl eugenol, and limonene whose share was 48.17%, 41.11%, 8.46%, 4.82%, 4.44%, and 4.15% respectively whereas concentrations of other 06 constituents were less than 3.7%. Phenyl ethyl alcohol, lion shared constituent of essential oil was found highest (48.17%) in R. Gruss-an-Teplitz whereas minimum level was recorded in R. damascena (28.84%) under CW. In contrast, citronellol (chief component of fragrance) was highest in R. damascena (41.11%) in UTWW while the lowest level was found in R. Gruss-an-Teplitz (17.41%) in CW. This study confirmed the variations in metal concentrations of Rosa species due to different absorbability of each metal in flower petals. It also indicates that wastewater did not affect the composition but there were quantitative differences in aroma constituents and chemical composition of essential oil.

Modified QuEChERS extraction method followed by simultaneous quantitation of nine multi-class pesticides in human blood and urine by using GC-MS

Organophosphate, carbamate and pyrethroid pesticides are the most common insecticides used worldwide. They may cause chronic poisoning in farmers and acute poisoning in homicidal or suicidal cases. The determination of trace levels of these pesticides in human blood and urine is very challenging. This study focuses on a simultaneous quantitation method that was developed and validated for multi-class nine pesticides belonging to organophosphate, carbamate and pyrethroid classes in human blood and urine. Target pesticides were extracted from blood and urine using a modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) extraction method. Capillary column DB-35 ms (15 m × 0.25 mm, 0.25 µm) was used for chromatography with a 0.079 ml/min flow rate of carrier gas at constant pressure mode. Quantitation of sulfotep, phorate, carbofuran, chlorpyriphos, profenophos, triazophos, pyriproxyfen, lambda-cyhalothrin and permethrin was performed by mass spectrometer equipped with electron impact ionization source using selected ion monitoring (SIM) mode. The lower and upper limits of quantitation for all nine pesticides were 0.01 mg/L and 2.0 mg/dL respectively. The proposed method was proved to be simple, fast, sensitive, and robust. It has been applied to the analysis of 9 pesticides samples.

Designing novel morphologies of l-cysteine surface capped 2D covellite (CuS) nanoplates to study the effect of CuS morphologies on dye degradation rate under visible light

Novel CuS@l-Cys NPs are designed by a hydrothermal route. The effects of synthetic parameters on the morphologies of CuS@l-Cys NPs were investigated. CuS@l-Cys NPs exhibit an enhanced dye degradation rate under visible light.

Understanding brassinosteroid-regulated mechanisms to improve stress tolerance in plants: a critical review

Brassinosteroids (BRs) are steroidal plant hormones involved in regulation of physiological and molecular processes to ameliorate various biotic and abiotic stresses. Exogenous application of BRs to improve stress tolerance in plants has recently become a high research priority. Several studies have revealed the involvement of these steroidal hormones in upregulation of stress-related defense genes and their cross talk with other metabolic pathways. This is likely to stimulate research on many unanswered questions regarding their role in enhancing the ability of plants to tolerate adverse environmental conditions. Thus, this review appraises new insights on mechanisms mediating BR-regulated changes in plants, focused mainly on their involvement in regulation of physiological and molecular mechanisms under stress conditions. Herein, examples of BR-stimulated modulation of antioxidant defense system and upregulation of transcription factors in plants exposed to various biotic (bacterial, viral, and fungal attack) and abiotic stresses (drought, salinity, heat, low temperature, and heavy metal stress) are discussed. Based on these insights, future research in the current direction can be helpful to increase our understanding of BR-mediated complex and interrelated processes under stress conditions.

Role of Pristine and Acid-Functionalized Fullerene on Breaking Dye Aggregates and its Impact on the Efficiency of Solar Cells

Porphyrin dyes have an inherent tendency to aggregate. This leads to a self-quenching phenomenon that hinders electron transfer to the conduction band of semiconductors in dye-sensitized solar cells. Self-quenching adversely affects the efficiency of solar cells. Here, we report the interaction of porphyrin with pristine and acid-functionalized fullerene molecules on the surface of ZnO nanoparticles under chemisorbed conditions. Chemisorption of porphyrin only on ZnO nanoparticles instigates aggregation of the porphyrin molecules. These aggregates can be effectively broken by chemisorbing fullerene molecules on the surface of the ZnO nanoparticles. This is due to self-assembly formation processes because of porphyrin–fullerene interactions. The nanohybrid material, consisting of ZnO nanorods, acid-functionalized porphyrin, and fullerene derivatives, was characterized by UV–visible spectroscopy, fourier transform infrared spectroscopy, fluorescence spectroscopy, and transmission electron microscopy. The material generates better performing dye-sensitized solar cells when compared with those fabricated from porphyrin-based photo-active material.