This article presents an investigation of dynamical behaviors of perfect and defected fixed– fixed single-walled carbon nanotube (SWCNTs) model as a beam structures. The fundamental frequencies and modal participation factors for fixed– fixedsupported SWCTS are considered through this analysis for the first time. Energy-equivalent model is implemented to find a relationship between the energy stored in atomic chemical bonding and potential energy of mechanical beam structure. Nanotube software modeler is exploited to create a geometrical structural of SWCNTs by defining its length of nanotube, bond distance between two atoms, and chiral angle. The tube of SWCNTs are simulated as fixed– fixed-supported structure at both ends, while bonding between each two atoms is modeled by 3D beam element with circular cross section. Parametric results are illustrated to display the effects of vacancy on activation and deactivation of vibration modes, fundamental frequencies, and modal participation factors of SWCNTs.

Currently, carbon quantum dots have attracted considerable attention due to their unique properties and desirable advantages. High crystallinity, water solubility, good dispersibility, small size, low toxicity, inexpensive raw materials, high chemical stability, environmental compatibility, low cost, stability under light, desirable charge transfer with advanced electronic conductivity, as well as specific thermal and mechanical properties are some of these features. Carbon quantum dots have various applications in different fields. Fabrication of precise chemical and biological sensors, bioimaging, solar cells, drug tracking, nanomedicine, light-emitting diodes (LEDs), and electrocatalysts are some of these applications. Biological sensors based on carbon quantum dots are capable of detecting various metal ions, acids, proteins, biotin, polypeptides, DNA and miRNA, water pollutants, hematin, drugs, vitamins, and other chemicals. In the present study, the properties of carbon quantum dots and some of their fabrication and applications methods have been addressed. In continuation of the paper, the effect of carbon quantum dots on important factors in plants such as growth and development, photosynthesis, absorption and transportation of substances, resistance to biotic and abiotic stresses, as well as their application in agriculture has been investigated.

Background and Objective: Fixed drug eruption (FDE) is one kind of drug rashes that is characterized by re-appearance of the lesions on the same sites after re-exposure to the causative drug. This study was performed to evaluate the epidemiologic characteristics of FDE. Materials and Methods: This descriptive study was done on a series of 100FDE cases, whom were admitted at the outpatient dermatology clinic of Hazrat-e-Rasoul Hospital over a six-year period. The primary diagnosis of FDE was suggested according to clinical findings including a remaining hyperpigmentation at the site of healed skin lesion(s). Oral challenge test with a single low dose administration of the suspected drug was used to confinn the diagnosis. Recurrence of the lesion(s) at the same body area(s) was considered as positive result. Results: Most commonly causative agents were co-trimoxazole and codein, which were found in 88% and 3% FDE cases; respectively. The most common site of involvement was penile glans in 57.7% of male patients and trunk in 48.3% of females. In one patient, reaction to multiple drugs including co-trimoxazole, codein and tetracycline was observed and after re-challenge with each drug, re-appearance of the skin lesion at the same site was evident. Several patients reported concomitant acetaminophen intake, but there was no reaction to that drug. Conclusion: Co-trimoxazole is the most common cause of FDE.      

Combustion of fossil fuels is one of the major sources of greenhouse gas (GHG) CO2, it is therefore necessary to develop technologies that will allow us to utilize the fossil fuels while reducing the emissions of GHG. Removal of CO2 from flue gasses has become an effective way to mitigate the GHG and adsorption is considered to be one of the methods. Adsorption of CO2 on zeolite 13X, zeolite 4A and activated carbon (AC) have been investigated at a temperature ranging from 25 to 60oC and pressure up to 1 bar. The experimental data were fitted with isotherm models like Langmuir and Freunlich isotherm model. The Langmuir model fit well with the two zeolites and Freunlich model fit well with AC. The thermodynamics parameters were calculated and found to be exothermic in natures for all three adsorbents. Moreover, regeneration studies have been conducted in order to verify the possibility of activated carbon reutilization, to determine its CO2 adsorption capacity within consecutive cycles of adsorption–desorption. Temperature swing adsorption was employed as the regeneration method through heating up to a temperature of approximately 100oC. There is no full reversibility for zeolites while AC can achieve complete regenerations.

The emerging contaminants are commonly derived from municipal, agricultural, and industrial wastewater sources and pathways. These compounds are polar and poorly biodegradable. The dynamic removal of atenolol from aqueous solutions by activated carbon in fixed bed column systems was investigated. As far as we know, this is the first study reporting the decontamination by adsorption in fixed bed of solutions containing atenolol, as model compound of b-blockers, which are pharmaceutical pollutants with a high occurrence in natural waters. The performance of fixed bed columns was described through the breakthrough curves obtained from column experiments. The Bohart-Adams, Thomas and Yoon-Nelson models were applied to predict different parameters of the column like service time (Bohart-Adams model), adsorption capacity (Thomas model) and time required for 50% breakthrough (Yoon-Nelson model). Also, the theoretical breakthrough adsorption curve has been obtained. For the last, an industrial scale adsorber was designed from characteristic parameters of the breakthrough curves obtained from experimental data.

In this research, carbon dioxide absorption by 13x zeolite was studied in a fixed bed reactor. The adsorption experiments were carried out in a fixed bed with 1 m height and 10 cm diameter. The adsorption experiments were carried out to investigate adsorption operating parameters including temprature, pressure, gas flow rate and adsorbent amount. The analyses result showed that adsorbent diameter avarege is 1.92 nm and interface area is 697 m2/gr. The experimental result showed that adsorption rate of carbon dioxide was increased by increasing pressure and bed height and decreasing temperature. The evaltuation of adsorption isotherm data showed that the CO2 adsorption is physical and the adsorbent has high capacity. Also the isotherm data was evaluated with different isotherm models and the results showed that Frendlich model with correlation coeffient 0.999 has good agreement with experimental data.

The carbon-alumina composite pellet was developed for the adsorption of acid fuchsin from its aqueous solution. The composite pellet was characterized using Brunauer-Emmett-Teller method, scanning Electron Microscopy and Fourier Transform Infrared Spectroscopy. The adsorption capacity of commercial alumina, commercial activated carbon and the prepared composite pellet was investigated against acid fuchsin, and the adsorption capacity was found to be increased in the order of alumina < carbon-alumina composite pellet < activated carbon. Although the adsorption capacity of carbon-alumina composite pellets was less than that of activated carbon, the use of the pelletized form of the present adsorbent was proven to be advantageous for the use in the packed-bed column. The experimental data were fitted to Langmuir, Freundlich and Temkin adsorption isotherms, and the equilibrium behavior was well explained by Langmuir isotherm. Besides, the kinetic behavior was well predicted by pseudo-second-order kinetics. The effects of inlet dye concentration (10-20 mg/L), feed flowrate (5-15 mL/min) and bed height (2.54-7.62 cm) on the breakthrough characteristics were investigated using a fixed-bed column. The maximum removal capacity in the column study was found to be 343.87 mg/L with an initial dye concentration and flowrate of 20 and 10 mL/min according to Bohart-Adams model. The breakthrough behavior was also effectively described by the Yoon-Nelson and Clark models.