Gemstone manufacturing in the Arab scientific heritage from the Umayyad Era to the end of the Mamlūk Era (41-923 AH/ 662-1517AD): A cultural historical study

Salih Maddah Aljedani, Layla Sulaiman Aloumi, Saad Saeed Alqarni — Mon, 29 Jun 2026 00:00:00 -0500

This research investigates the advanced experimental methodologies developed by Arabic chemists (8th-14th Calendar centuries) for the synthesis and imitation of gemstones, with a primary focus on the corpora of Jābir ibn Ḥayyān [1]. Diverging from traditional historiography that often relegates these works to the realm of allegorical alchemy, this study provides evidence of early "materials engineering" based on a sophisticated understanding of the optical and mechanical properties of inorganic substances. By analyzing historical recipes through the lens of modern solid-state chemistry, the paper reveals Arabic pioneering in four technical domains: First, refractive index tuning is done through the strategic incorporation of lead oxides into silicate glass matrices in order to enhance optical dispersion. Second, the management of redox potentials to precisely control the chromatic spectra of transition metal ions such as copper, iron, and manganese. Third, crystal growth via chemical vapor transport is evidenced by protocols involving the sublimation and condensation of arsenic sulfides to produce high-purity crystalline solids. Finally, colloidal and substrate engineering is utilized in order to plaster calcium-based carriers and organic binders to stabilize organometallic pigments. The findings demonstrate that these protocols functioned as "Standard Operating Procedures" (SOPs) aimed at engineering synthetic alternatives that replicate the specific gravity, hardness, and refractive indices of natural rubies, emeralds, and lapis lazuli. By achieving these objectives, the study contributes to a significant re-evaluation of the history of materials science, positioning medieval Arabic chemistry as a direct precursor to modern glass technology and solid-state physics.

A study on a hydrogen injection control method for fuel cell engines based on proportional valve polling

Ge Lixia, Mohammad Nizamuddin Inamdar, Aiman Alodainia — Mon, 06 Jul 2026 00:00:00 -0500

As the core component of fuel cell engine hydrogen supply systems, hydrogen injection solenoid valves suffer from high switching frequency, excessive power consumption and shortened service life under traditional equal-distribution control, which raises system failure risks and maintenance costs. To solve these problems, this paper puts forward a polling control strategy based on PI closed-loop pressure regulation. The stack inlet hydrogen pressure is sampled in real time to calculate the overall hydrogen injection duty cycle, which is evenly assigned to six solenoid valves via sequential allocation and cyclic rotation to balance valve workload and cut single-valve actuation frequency and heat loss. Co-simulation of Simulink and AMESim is conducted to compare three control modes, and a durability test bench is built for experimental validation. The Parker model is adopted to evaluate valve life attenuation. Simulation and test results reveal that the proposed polling method effectively suppresses hydrogen pressure fluctuation under low-flow conditions and improves control accuracy. It reduces valve switching times, power consumption and operating temperature, slowing insulation and seal aging. Durability tests show its first-failure time and total service life exceed the equal-distribution mode by over 2.5 times with fewer faulty valves. This strategy optimizes pressure control and component durability, offering great engineering application value for long-life commercial fuel cell vehicles.

International Journal of Innovative Research and Scientific Studies

Gemstone manufacturing in the Arab scientific heritage from the Umayyad Era to the end of the Mamlūk Era (41-923 AH/ 662-1517AD): A cultural historical study

A study on a hydrogen injection control method for fuel cell engines based on proportional valve polling