In Vivo Endoscopic Tissue Identification by Rapid Evaporative Ionization Mass Spectrometry (REIMS)

Gastrointestinal cancers are a leading cause of mortality, accounting for 23 % of cancer‐related deaths worldwide. In order to improve outcomes from these cancers, novel tissue characterization methods are needed to facilitate accurate diagnosis. Rapid evaporative ionization mass spectrometry (REIMS) is a technique developed for the in vivo classification of human tissue through mass spectrometric analysis of aerosols released during electrosurgical dissection. This ionization technique was further developed by utilizing surface induced dissociation and was integrated with an endoscopic polypectomy snare to allow in vivo analysis of the gastrointestinal tract. We tested the classification performance of this novel endoscopic REIMS method in vivo. It was shown to be capable of differentiating between healthy layers of the intestinal wall, cancer, and adenomatous polyps based on the REIMS fingerprint of each tissue type in vivo.     

Effervescent tablet‐assisted demulsified dispersive liquid–liquid microextraction based on solidification of floating organic droplet for determination of methadone in water and biological samples prior to GC‐flame ionization and GC‐MS

A novel effervescent tablet‐assisted demulsified dispersive liquid–liquid microextraction based on the solidification of floating organic droplet was developed to determine methadone prior to gas chromatography with flame ionization detection and gas chromatography with mass spectrometry. In this method, a tablet composed of citric acid, sodium carbonate, and 1‐undecanol was utilized. The resulting effervescent tablet generated carbon dioxide in situ to disperse 1‐undecanol in the sample. Thus, the dispersive and extraction processes were performed in one synchronous step. An aliquot of acetonitrile as the demulsifier solvent was used for the separation of two phases instead of centrifugation. Under optimal conditions, the developed method was linear up to 50 000 µg/L with correlation coefficients higher than 0.99. Moreover, limits of detection and limits of the quantification were in the range of 3‐10  and 7‐30 µg/L in water and biological samples, respectively. Intra‐ and interday precisions (n = 6) of the spiked methadone at a concentration level of 50 µg/L were over ranges of 5.1‐6.8% and 5.7‐7.1%, respectively. The preconcentration factors and recovery values were obtained in the range of 140‐145 and 98.1 to 101.6% in real samples, respectively.     

Synthesis,biological evaluation and molecular docking study of dihydropyrimidine derivatives as potential anticancer agents

A series of dihydropyrimidine analogues were prepared via one-pot Biginelli three-component condensation reaction and characterized by NMR, FT-IR, MS spectra, and element analysis. Subsequently, they were screened for in vitro anticancer effect. These analogues revealed good cytotoxic activity against three human cancer cell lines including MCF-7, HepG-2, and A549. Among these analogues, compounds 4d and 4h were the most potent against three cell lines. Cell viability assays indicated 4a and 4c had lower cytotoxicity. In vitro cytotoxicity study on all synthesized compounds demonstrated that introduction of electron withdrawing substituents on C4 position of phenyl ring of dihydropyrimidine contributed to the antiproliferative potency. Moreover, in silico molecular docking results stipulated a sign of good correlation between experimental activity and calculated binding affinity. It proved 4d and 4h as the strongest compounds. Binding modes of analogues proposed the involvement of hydrophobic interactions and hydrogen bonds with Eg5 active site. Structure activity relationship studies indicated that incorporating electron withdrawing substituents on C4 position of phenyl ring of dihydropyrimidine are important for this biological activity.     

Bicontinuous cubic phase of monoolein and water as medium for electrophoresis of both membrane-bound probes and DNA

Porous hydrogels such as agarose are commonly used to analyze DNA and water-soluble proteins by electrophoresis. However, the hydrophilic environment of these gels is not suitable for separation of important amphiphilic molecules such as native membrane proteins. We show that an amphiphilic liquid crystal of the lipid monoolein and water can be used as a medium for electrophoresis of amphiphilic molecules. In fact, both membrane-bound fluorescent probes and water-soluble oligonucleotides can migrate through the same bicontinuous cubic crystal because both the lipid membrane and the aqueous phase are continuous. Both types of analytes exhibit a field-independent electrophoretic mobility, which suggests that the lipid crystal structure is not perturbed by their migration. Diffusion studies with four membrane probes indicate that membrane-bound analytes experience a friction in the cubic phase that increases with increasing size of the hydrophilic headgroup, while the size of the membrane-anchoring part has comparatively small effect on the retardation.     

Fractional-order single state reset element

Nonlinear Dynamics - This paper proposes a fractional-order reset element whose architecture allows for the suppression of nonlinear effects for a range of frequencies. Suppressing the nonlinear...     

Transmission dynamics of novel coronavirus SARS-CoV-2 among healthcare workers,a case study in Iran

One of the main concerns during the COVID-19 pandemic was the protection of healthcare workers against the novel coronavirus. The critical role and vulnerability of healthcare workers during the COVID-19 pandemic leads us to derive a mathematical model to express the spread of coronavirus between the healthcare workers. In the first step, the SECIRH model is introduced, and then the mathematical equations are written. The proposed model includes eight state variables, i.e., Susceptible, Exposed, Carrier, Infected, Hospitalized, ICU admitted, Dead, and finally Recovered. In this model, the vaccination, protective equipment, and recruitment policy are considered as preventive actions. The formal confirmed data provided by the Iranian ministry of health is used to simulate the proposed model. The simulation results revealed that the proposed model has a high degree of consistency with the actual COVID-19 daily statistics. In addition, the roles of vaccination, protective equipment, and recruitment policy for the elimination of coronavirus among the healthcare workers are investigated. The results of this research help the policymakers to adopt the best decisions against the spread of coronavirus among healthcare workers.

     

A Subgrid-Scale Model for Turbulent Flow in Porous Media

Transport in Porous Media - Given the analogy between the filtered equations of large eddy simulation and volume-averaged Navier–Stokes equations in porous media, a subgrid-scale model is...     

Non-linear vibrations and frequency response analysis of piezoelectrically driven microcantilevers

Microcantilevers have recently received widespread attentions due to their extreme applicability and versatility in both biological and non-biological applications. Along this line, this paper undertakes the non-linear vibrations of a piezoelectrically driven microcantilever beam as a common configuration in many scanning probe microscopy and nanomechanical cantilever biosensor systems. A part of the microcantilever beam surface is covered by a piezoelectric layer (typically ZnO), which acts both as an actuator and sensor. The bending vibrations of the microcantilever beam are studied considering the inextensibility condition and the coupling between electrical and mechanical properties in the piezoelectric materials. The non-linear terms appear in the form of quadratic expression due to presence of piezoelectric layer, and cubic form due to geometrical non-linearities. The Galerkin approximation is then utilized to discretize the equations of motion. In addition, the method of multiple scales is applied to arrive at the closed form solution for the fundamental natural frequency of the system. An experimental setup consisting of a commercial piezoelectric microcantilever attached on the stand of a state-of-the-art microsystem analyzer for non-contact vibration measurement is utilized to verify the theoretical developments. It is found that the experimental results and theoretical findings are in good agreement, which demonstrates that the non-linear modeling framework could provide a better dynamic representation of the microcantilever than the previous linear models. Due to microscale nature of the system, excitation amplitude plays an important role since even a small change in the amplitude of excitation can lead to significant vibrations and frequency shift.