In this paper, we study the singularities on a non-developable ruled surface according to Blaschke’s frame in the Euclidean 3-space. Additionally, we prove that singular points occur on this kind of ruled surface and use the singularity theory technique to examine these singularities. Finally, we construct an example to confirm and demonstrate our primary finding.

In this paper, we present the synthesis of new selenoloquinoxaline derivatives starting from 2-Chloroquinoxaline-3-carbonitrile 1. The compound 1 was subjected to a reaction with Selenium metal in the presence of NaBH₄ as a reducing agent in ethanol, under a nitrogen atmosphere. This reaction resulted in the formation of the sodium salt of 3-cyanoquinoxaline-2-selenolate, which was subsequently reacted with α-halogenated carbonyl compounds in situ. This reaction produced a serious of newly synthesized 3-aminoselenolo[2,3-b]quinoxaline-2-substituents. Ethyl 3-aminoselenolo[2,3-b]quinoxaline-2-carboxylate 3a was hydrolyzed by sodium hydroxide to give the corresponding sodium salt 9. This salt was then refluxed with acetic anhydride to produce oxazinone compound 10. The reaction of compound 10 with ammonium acetate afforded pyrimidoselenolo[2,3-b]qinoxaline derivative 11. Compound 11 was then Chlorinated using phosphorous oxychloride to give the corresponding chlorocompound.

A nanocomposite (NC) film containing polyvinyl alcohol (PVA), carboxymethyl
cellulose (CMC) and polyvinyl pyrrolidone (PVP) polymers
and tin chromium disulfide (Sn0.75Cr0.25S2) nanoparticles (NPs)
was prepared using thermolysis and casting techniques. The prepared
NPs were characterized using X-ray diffraction (XRD) and transmission
electron microscopy (TEM) techniques. The induced
alterations in the optical and color properties of the prepared PVA/
CMC/PVP/Sn0.75Cr0.25S2 NC film due to UV irradiation, within fluences
ranging from 10 to 80 Joule/cm2 (J/cm2), were characterized via UV
spectroscopy and the International Commission on Illumination (CIE)
color changes techniques. As the UV fluence increased up to 80 J/
cm2, the maximum fluence used, both the direct and indirect bandgaps
decreased. We attribute this to the dominance of formed chain
crosslinks that destroyed the ordered structure and, thus, increased
the amorphous regions. The effect of UV irradiation on the absorbance,
refractive index, real and imaginary dielectric parameters and
optical conductivity of the NC samples were studied. Furthermore,
the optical color changes between the pristine and the irradiated
films were evaluated. The pristine NC film was uncolored. It showed
significant color changes when irradiated with the UV radiation at
increasing fluences up to 80 J/cm2. The changes in the optical properties
of PVA/CMC/PVP/Sn0.75Cr0.25S2 NC film suggested its usage as
a promising candidate for future optoelectronics characterization
techniques.

Magnesium oxide (MgO) nanoparticles are among the most promising classes of nanomaterials
due to the fact that they have a rapid metabolism, are biocompatible, and are relatively lightweight.
For a considerable amount of time, these particular types of nanomaterials have been the most desired
substitute for hefty metallic substances in applications including photodynamic treatment and cancer
therapy. The primary objective of this research is to Look into the catalytic activity and toxicity of MgO
nanoparticles that have a variety of shapes. In order to conduct an analysis of the MgO that was created,
X-ray diffraction, electron microscopy, and UV-visible spectroscopy were used. Staphylococcus aureus
(S. aureus) and Escherichia coli (E. coli) models that are clinically relevant were used in order to evaluate
the factors that are dependant on toxicity respectively. On the basis of the observation of the UV-vis spectra,
the highest absorbance was obtained, along with a peak absorption that was very noticeable. In order
to determine the band gap that corresponds to MgO nanoparticles, Tauc's figure was used.

The photocatalytic activity of titanium dioxide (TiO₂) nanoparticles toward hydrogen generation can be significantly improved via the loading of various metals e.g., Ru, Co, Ni as co-catalysts. The metal co-catalysts are loaded into TiO₂ nanoparticles via different deposition methods; incipient wet impregnation (Imp), hydrothermal (HT), or photocatalytic deposition (PCD). Among all of the tested materials, 0.1 wt% Ru–TiO₂ (Imp) provided the highest initial hydrogen catalytic rate of 23.9 mmol h⁻¹ g⁻¹, compared to 10.82 and 16.55 mmol h⁻¹ g⁻¹ for 0.3 wt% Ni–TiO₂ (Imp) and 0.3 wt% Co–TiO₂ (Imp), respectively. The loading procedures, co-catalyst metals type, and their loading play a significant role in elevating the photocatalytic activity of pristine TiO₂ semiconductors toward hydrogen generation. Redox transition metals e.g., Co and Ni exhibit comparable photocatalytic performance to expensive elements such as Ru.

Cadmium ion Cd²⁺ contamination is a major environmental issue caused by industry. Polyarylidene N-hexane pyrrole (PAP_h) and crosslinked polyarylidene N-phenyl pyrrole (PAP_D) were prepared from the previously synthesized polymer (polyarylidene ketone (PAK)) by using the advantage of repeating carbonyl groups at the 1,4 position and reacting it with hexylamine and P-phenylenediamine via the Paal–Knorr reaction. Various methods were used to characterize polymers, such as FT-IR spectroscopy, X-ray diffraction (XRD), thermogravimetry analysis (TGA), UV–visible spectroscopy, scanning electron microscope (SEM), zeta potential, and surface area measurements (BET), revealing successful fabrication, good thermostability, and well-defined microporous structures useful for Cd²⁺ adsorption. Optimal adsorption capacities of 55.8 mg g⁻¹ for PAP_h and 86.95 mg g⁻¹ for PAP_D indicate a significant enhancement in Cd²⁺ adsorption via their microporous structures, Cd²⁺ adsorption was also investigated in terms of contact time, initial concentration, and pH. A total input concentration of 30 ppm Cd ions, may yield an 84.3% removal rate for PAP_h and an 89.2% removal rate for PAP_D. The experimental results were well-fit by many models, including pseudo-second-order kinetics (PSO), Freundlich isotherms, intraparticle diffusion, and Langmuir. The varying adsorption performances of the two polymers studied, (PAP_h) and (PAP_D), were found to be derived from their respective chemical structures, which include various functional groups, according to studies conducted on Cd²⁺ in an aqueous solution. Cd²⁺ adsorption on polymers was considered physisorption; π–cation interactions and surface complexation played significant roles in adsorption. The PAP polymers may be considered promising substitutes and innovative adsorbents to remove Cd²⁺ ions from a water solution.

Background

Hydrogen is a promising source of alternative energy. Fermentative production is more feasible because of its high hydrogen generation rate, simple operating conditions, and utilization of various organic wastes as substrates. The most significant constraint for biohydrogen production is supplying it at a low cost with fewer impurities.

Results

Leaf biomass of Calotropis procera was used as a feedstock for a dark fermentative production of hydrogen by Bacillus coagulans AH1 (MN923076). The optimum operation conditions for biohydrogen production were 5.0% substrate concentrationand pH 9.0, at 35 °C. In which the biohydrogen yield was 3.231 mmol H₂/g dry biomass without any pretreatments of the biomass. A freshwater microalga Oscillatroia sp was used for upgrading of the produced biohydrogen. It sequestrated 97 and 99% % of CO₂ from the gas mixture when it was cultivated in BG11 and BG11-N media, respectively After upgrading process, the residual microalgal cells exhibited 0.21mg/mL of biomass yield,high content of chlorophyll-a (4.8 µg/mL) and carotenoid (11.1 µg/mL). In addition to Oscillatroia sp residual biomass showed a lipid yield (7.5–8.7%) on the tested media.

Conclusion

Bacillus coagulans AH1 is a promising tool for biohydrogen production avoiding the drawbacks of biomass pretreatment. Oscillatroia sp is encouraged as a potent tool for upgrading and purification of biohydrogen. These findings led to the development of a multiproduct biorefinery with zero waste that is more economically sustainable.