The generation of cold plasma at atmospheric pressure by using atmospheric-pressure plasma jet (APPJ) system and its use in the treatment of the poly-methyl-methacrylate (PMMA) have been reported in the manuscript. The cold plasma is generated at atmospheric pressure with 120 watt and 200 watt power and 3 litres/min and 5 litres/min argon flow using a 13.56 MHz radio frequency generator. PMMA samples are treated with aforesaid parameters for different time durations. After treatment, the formation of a carbon-rich surface has been observed, while a visible and significant amount of changes in surface morphology, roughness, adhesion strength and contact angle have been observed. Due to the APPJ treatment, the Wenzel's model supportive microconical structures have been formed for hydrophobic surfaces. Optical emission spectroscopy has been used to identify the various species in the plasma and for electron temperature measurement. The discharge phenomenon at atmospheric pressure has been understood using the basic plasma model. The interaction of the plasma with the surface has been explained using the sub-plantation model.

Herein, a low-cost, label free Flexible Paper based microfluidic SERS sensor for thiram detection has been demonstrated. Hydrophilic wells of different sizes were engraved by wax-coated mould printing on paper using a hot laminator. The hydrophilic nature of the wells was confirmed by contact angle measurement. Silver nanoparticles (AgNPs) decorated GO nano-hybrid (Ag-rGO), was synthesized using wet chemical route. The uniform distribution of spherical AgNPs (similar to 40 nm) on GO was achieved. The synthesized Ag-rGO was then drop-casted on hydrophilic wells for thiram detection and fM sensitivity has been achieved. The limit of detection (LOD) and Enhancement factor (EF) were found to be 0.36 x 10(-16) M and 5.2 x 10(12) respectively. The reproducibility and uniformity of the fabricated substrates were tested, with RSD value < 5 % and < 3 % respectively. The recovery time of the sensors was examined for 2 months and the deviation in the intensity has been found to be < 4 %. Selectivity test was performed in the mixture of spinach leaves with thiram, the fM sensitivity with RSD value of 4.9 % was achieved. Thus, the Ag-rGO/wax paper (Ag-rGO/WP)- SERS sensor has the inherent potential to be used as an on-site portable sensing platform for food safety applications.

In this article, we have employed an atmospheric pressure plasma jet (APPJ) system to produce graphene layers on polymeric substrates for large-area applications. Herein, the graphene layers are grown on four different polymers polyamide6 (PA-6), high-density polyethylene (HDPE), polypropylene (PP), and polyurethane (PU) using 200 W of 13.56-MHz RF power supply-induced APPJ with argon as primary gas in an open atmosphere. The formation of the graphene layers has been confirmed by Raman spectroscopy, X-ray diffraction (XRD), and field emission electron microscopy (FESEM). The optical emission spectra (OES) of the plasma plume have been taken to analyze the presence of active species. To ensure the thermal integrity of the polymers, thermal gravimetric analysis (TGA) has been done after the plasma treatment. Furthermore, the prepared samples have been tested to verify various properties of graphene, like hydrophobicity, electrical conductivity, bacteria detection, and antimicrobial properties. The hydrophobic nature of graphene has been tested by measuring the contact angle. The electrical conductivity has been measured using the four-probe method to find out the applicability of the graphene-coated substrates for flexible electronic applications. The electrochemical three-probe-based $I$ – $V$ characterization has been done for E. coli bacteria detection, and the antimicrobial activity of the prepared samples has also been analyzed.

We demonstrate the detection of dipicolinic acid, (DPA), a biomarker of bacterial spores for Bacillus anthracis, 2,4-Dinitrotoluene (DNT) and picric acid (PA) nitroaromatic hazardous chemicals on ultra-sensitive, reusable femtosecond laser textured Au nanostructures decorated with hierarchical AuNPs as a SERS substrate. The AuNPs were achieved by ablating an Au sheet using two different laser scan speeds (1 and 0.1 mm/s) in linear and crossed patterns. The morphological studies revealed dense hierarchical nanostructures decorated with spherical AuNPs possessing 30-40 nm in size in 0.1 mm/s laser scan. The limits of detection (LOD) of the sensor were determined from the detailed SERS measurements and were estimated to be 0.83 pg/L, 3.6 pg/L and 2.3 pg/L for DPA, DNT, and PA, respectively. To the best of our knowledge, the achieved sensitivity is nearly 2 orders improved for DPA when compared with the currently reported LODs using other techniques and 1 order in the case of SERS. Moreover, for DNT and PA the LODs were found to be either superior or comparable with recent reports. We have also demonstrated the competence of our SERS substrates by testing a few real samples (water spiked with these analytes) and again obtained very good sensitivity.

In this paper, a new method for fabrication of surface enhanced Raman spectroscopy (SERS) substrates by atmospheric pressure plasma jet (APPJ) has been introduced. Arc free cold plasma is generated at atmospheric pressure by using atmospheric pressure plasma jet system with 120 W and 200 W RF power and 3 L/min and 5 L/min argon flow. SERS substrates are prepared by two-step treatment process. In first step, PMMA substrates are roughened by 15 min plasma treatment using APPJ and in second step, spin coated Ag/GO suspension (on roughened PMMA substrates) is again treated with APPJ for 1 min. Treated PMMA samples have been characterized by AFM and XPS to observe the morphology, roughness and the chemical changes on surface. Variation of the roughness with the variation of vertical distance has also been analysed. Treated spin coated Ag/GO samples are characterized by Raman and FESEM to observe the surface enhanced Raman spectra and the morphological changes, respectively. Plasma jet coming out form APPJ system has also been characterized by optical emission spectroscopy to identify the various species in the plasma jet and for electron energy measurement. The gas temperature of the plasma jet has also been measured.

We live in a world of systems driven by cause and effect. Those systems include financial, production, inventory, biological, chemical, thermodynamic or workflow. Systems can be modeled as nodes representing system variables and connecting lines representing causal effects. Determining production rate considering costs and revenues in order to maximize profit is one of the applied problems in small factories. Mostly existing models in production planning consider production system static and specify production rate, although the factors determining production rate include many different changes in practice.The changing value of one variable can cause another to increase or decrease as described by equations. Understanding how a system really works is the first step towards using, improving, automating or explaining it to others. This paper shows how to model dynamic systems, with an example of production system of a small foundry and present the system behavior with charts, graphs and tables.