Predicting Compressive and Splitting Tensile Strengths of Silica Fume Concrete Using M5P Model Tree Algorithm

Compressive strength (CS) and splitting tensile strength (STS) are paramount parameters in the design of reinforced concrete structures and are required by pertinent standard provisions. Robust prediction models for these properties can save time and cost by reducing the number of laboratory trial batches and experiments needed to generate suitable design data. Silica fume (SF) is often used in concrete owing to its substantial enhancements of the engineering properties of concrete and its environmental benefits. In the present study, the M5P model tree algorithm was used to develop models for the prediction of the CS and STS of concrete incorporating SF. Accordingly, large databases comprising 796 data points for CS and 156 data records for STS were compiled from peer-reviewed published literature. The predictions of the M5P models were compared with linear regression analysis and gene expression programming. Different statistical metrics, including the coefficient of determination, correlation coefficient, root mean squared error, mean absolute error, relative squared error, and discrepancy ratio, were deployed to appraise the performance of the developed models. Moreover, parametric analysis was carried out to investigate the influence of different input parameters, such as the SF content, water-to-binder ratio, and age of the specimen, on the CS and STS. The trained models offer a rapid and accurate tool that can assist the designer in the effective proportioning of silica fume concrete.     

Meroditerpenoids and derivatives from the brown alga Cystoseira baccata and their antifouling properties

The brown alga Cystoseira baccata harvested along the Atlantic coasts of Morocco yielded seven new meroditerpenoids (1-4) and derivatives (5-7), whose chemical structures were elucidated mainly by 2D NMR and mass spectrometry. Surprisingly, for all these compounds, which possess a bicyclo[4.3.0]nonane ring system, a trans fusion of the bicyclic system was deduced by stereochemical studies even though such compounds isolated from Cystoseira species are known to have a typical cis orientation for the bridgehead methyls. The antifouling and antibacterial activities of compounds 1-5 and 7 were evaluated, as well as their toxicity toward nontarget species. Compounds 4, 5, and 7 showed antifouling activities against growth of microalgae, macroalgal settlement, and mussel phenoloxidase activity, while being nontoxic to larvae of sea urchins and oysters.     

Carrier frequency of autosomal-recessive disorders in the Ashkenazi Jewish population: should the rationale for mutation choice for screening be reevaluated?

BACKGROUND: Ashkenazi Jewish (AJ) population is at increased risk for several recessive inherited diseases. Therefore, carrier testing of AJ members is important in order to identify couples at risk of having offspring with an autosomal recessive disorder. METHODS: In the present study, a database containing the results of 28 410 genotyping assays was screened. Ten thousand seventy eight nonselected healthy members of the AJ population were tested for carrier status for the following diseases; Gaucher disease (GD), cystic fibrosis (CF), Familial dysautonomia (FD), Alpha 1 antitrypsin (A1AT), Mucolipidosis type 4 (ML4), Fanconi anemia type C (FAC), Canavan disease (CD), Neimann-Pick type 4 (NP) and Bloom syndrome (BLM). RESULTS: The results demonstrated that 635 members were carriers of one mutation and 30 members were found to be carriers of two mutations in the different genes related to the development of the above mentioned diseases. GD was found to have the highest carrier frequency (1:17) followed by CF (1:23), FD (1:29), A1AT (1:65), ML4 (1:67) and FAC (1:77). The carrier frequency of CD, NP and BLM was 1:82, 1:103 and 1:157, respectively. CONCLUSIONS: The frequency of the disease-causing mutations screened routinely among the AJ population indicated that there are rare mutations with very low frequencies. The screening policy of the disease-causing mutations should be reevaluated and mutations with a high frequency should be screened, while rare mutations with a lower frequency may be tested in partners of carriers.     

Valorization of Rice Husk and Straw Agriculture Wastes of Eastern Saudi Arabia: Production of Bio-Based Silica,Lignocellulose, and Activated Carbon

Bio-based silica, lignocellulose, and activated carbon were simply produced via the recycling of Hassawi rice biomass waste of Al-Ahsa governorate in the eastern Saudi Arabia region using a fast chemical treatment procedure. Rice husk and rice straw wastes were collected, ground, and chemically treated with sodium hydroxide to extract silica/silicate from the dried plant tissues. The liquid extract is then treated with acid solutions in order to precipitate silica/silicate at neutral medium. Lowering the pH of the supernatant to 2 resulted in the precipitation of lignocellulose. Thermal treatment of the biomass residue under N₂ gas stream resulted in activated carbon production. Separated products were dried/treated and characterized using several physical examination techniques, such as FT-IR, SEM/EDX, XRD, and Raman spectroscopy in order to study their structure and morphology. Silica and lignocelluloses products were then preliminarily used in the treatment of wastewaters and water-desalination processes.     

Aramid-wrapped CNT hybrid sol–gel sorbent for polycyclic aromatic hydrocarbons

This work describes the preparation of an analytical microextraction sorbent using a simple and versatile sol–gel hybrid composite, i.e., aramid oligomers wrapping multi-walled carbon nanotubes (CNTs) covalently bonded to a porous silica network. To overcome the inherent shortcomings of the CNTs'' solubility and dispersion in both organic phases and in the sol–gel solution, the outer surface of the CNTs was initially functionalized with carboxylic acid groups and then reacted with both aramid oligomers and 3-aminopropyl triethoxysilane (APTES). The obtained sorbent was characterized by FT-IR, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). Using sol–gel chemistry, the functionalized CNTs were coated onto SPME fibers and used in conjunction with GC-MS for the analysis of polycyclic aromatic hydrocarbons (PAHs) in water and soil samples. Excellent repeatability (run-to-run RSD% ∼ 8) and reproducibility (fiber-to-fiber RSD% ∼ 6) were achieved in addition to low LODs (0.10–0.30 ng mL⁻¹) and noticeable recovery%. The present method of sorbent preparation led to enhanced thermal and chemical stabilities, a long sorbent lifetime and good affinity towards PAHs. Moreover, the present sorbent enhanced the extraction capability by more than 30% compared to that of commercially available PDMS counterparts.

This work describes the preparation of an analytical microextraction sorbent using a simple and versatile sol–gel hybrid composite, i.e., aramid oligomers wrapping multi-walled carbon nanotubes (CNTs) covalently bonded to a porous silica network.     

Moyamoya syndrome presenting in an adult with Down syndrome: A case report with a literature review

Moyamoya disease is an unusual occlusive cerebrovascular condition commonly seen in children, marked by stenosis of the internal carotid artery and circle of Willis, causing, cerebral ischemia. Moyamoya syndrome is a Moyamoya-like arteriopathy with risk factors including autoimmune disorders, thyroid disease, sickle cell disease, or Down syndrome. Trisomy 21 is a genetic disorder consistent with specific physical and behavioral characteristics, with intellectual impairment. We describe a rare case of Moyamoya syndrome manifesting as ischemic stroke in an adult with Down syndrome