A Simple and Green Route for Room‐Temperature Synthesis of Gold Nanoparticles and Selective Colorimetric Detection of Cysteine

Gold nanoparticles (AuNPs) were synthesized at room temperature following a simple, rapid, and green route using fresh‐squeezed apple juice as a reducing reagent. The optimal AuNPs, based on the particle color, stability, and color change suitable for colorimetric detection of cysteine (Cys), are synthesized using 5 mL of 10% apple juice, 1 mL of 10 mM gold precursor solution, and 1 mL of 0.1 M NaOH. Under this set of parameters, the AuNPs are synthesized within 30 min at room temperature. The average size (11.1 ± 3.2 nm) and ζ potential (–36.5 mV) of the AuNPs synthesized were similar to those of AuNPs prepared via the conventional citrate‐reduction method. In the presence of Cys, unlike with any other amino acid, the AuNPs aggregated, possibly due to the gold–sulfur covalent interaction, yielding red‐to‐purple color change of the sample solution. The red‐shift of the localized surface plasmon resonance peak of the AuNPs responsible for the color change was recorded by UV‐vis spectrometer. The effect of other potential interferents such as glucose, ascorbic acid, K⁺, Na⁺, Ca²⁺, Zn²⁺, Ag⁺, Ni²⁺, Cu²⁺, Co²⁺, and Hg²⁺ were also examined. The results show that AuNPs can be used to selectively detect and measure Cys with a linear dependency in the range of 2 to 100 μM and a limit of detection (signal‐to‐noise ratio > 3) of 50 nM. The results suggest that the green‐synthesized AuNPs are useful for simple, rapid, and sensitive colorimetric detection of Cys, which is an essential amino acid in food and biological systems.     

Optimization of particle number,substrate concentration and temperature of batch immobilized reactor system for biohydrogen production by dark fermentation

Immobilized cell bioreactor was operated in batch mode for biohydrogen generation by dark fermentation from acid hydrolyzed waste wheat powder. It was aimed to optimize the fermentation conditions with the purpose of obtaining the highest hydrogen yield (Y_H2) and production rate (HPR) by applying Box–Wilson statistical experimental design method. Particle number (PN = 120–240; X₁), initial total sugar concentration (TS₀ = 10–30 g/l; X₂) and fermentation temperature (T = 35–55 °C; X₃) were selected as independent variables. Polyester fibers with particle diameter “Dp” = 0.5 cm were used as support material to immobilize microorganisms with heat-pretreated sludge. Quadratic equations for production yield and rate were developed by using experimental results. The maximum Y_H2 (3.21 mol H₂/mol glucose) and HPR (73.3 ml H₂/h) were predicted at the optimum conditions of PN = 240, TS₀ = 10 g/l and T = 44.9 °C. Also, analysis of variance, as well as sum of ranking difference test results demonstrated that fitting models were statistically significant.     

Hydrogen supply chain architecture for bottom-up energy systems models. Part 2: Techno-economic inputs for hydrogen production pathways

This article is the second paper of a serial study on hydrogen energy system modelling. In the first study, we proposed a stylized hydrogen supply chain architecture and its pathways for the representation of hydrogen systems in bottom-up energy system models. In this current paper, we aim to present and assess techno-economic inputs and bandwidths for a hydrogen production module in bottom-up energy system models. After briefly summarizing the current technological status for each production method, we introduce the parameters and associated input data that are required for the representation of hydrogen production technologies in energy system modelling activities. This input data is described both as numeric values and trend line modes that can be employed in large or small energy system models. Hydrogen production technologies should be complemented with hydrogen storage and delivery pathways to fully understand the system integration. In this context, we will propose techno-economic inputs and technological background information for hydrogen delivery pathways in later work, as the final paper of this serial study.     

Species distribution,molecular characteristics and vancomycin resistance gene profiles of Enterococcus sp. isolates from farmhouse cheeses in western Turkey

Species distribution, virulence traits and vancomycin resistance gene profiles of Enterococcus isolated from 43 home‐made artisan cheese samples collected from open markets, located in Aydin region of Turkey, were investigated. Of the 129 isolates, 95 were identified as Enterococcus sp.; Enterococcus faecium being the most prevalent species (82.1%), followed by Enterococcus faecalis (13.6%) and Enterococcus durans (1.0%). None of the enterococci were harbouring vanA or vanC, while seven isolates (7.3%) were shown to harbour vanB gene by multiplex PCR. gelE (49.4%) being the most prevalent virulence factor was followed by asa1 (27.3%), esp (22.1%), cylA (4.2%) and hyl (3.1%).     

Improvement of polyvinyl alcohol/casein blend film properties by adding cellulose nanocrystals

This study aims to prepare and examine the properties of poly(vinyl alcohol)/casein (PVA/CAS) based films reinforced with cellulose nanocrystals (NC), which can be presented as an alternative to petroleum-based polymer packaging materials. PVA/CAS and 0.5–1–3–5 wt% NC containing PVA/CAS biocomposite films were prepared by solution casting method. Afterward, the 1NC film, which exhibited the best mechanical properties, was crosslinked with various amounts of glyoxal. Structural, morphological (polarized optical microscope), mechanical (tensile), thermal (differential scanning calorimetry, thermogravimetric analysis), contact angle, and water vapor transmission rate (WVTR) properties of the samples were investigated. The 1NC film exhibited the highest tensile strength (TS) and elongation values in PVA/CAS/NC films, and its mechanical properties decreased due to agglomeration with increasing NC amount. As expected, crosslinking improved the TS. The thermal stability of the PVA/CAS film was generally improved with the addition of NC and crosslinking. The high WVTR value of the PVA/CAS film decreased with the addition of NC and the 1NC film presented the lowest value. Thanks to the complex structure formed as a result of crosslinking and the reduced free volume, the WVTR of the 1NC film has reduced. The results showed that PVA/CAS-based films with good mechanical properties and water vapor barrier are promising as packaging materials.     

Room Temperature Photocatalytic Oxidation of Carbon Monoxide Over Pd/TiO2–SiO2 Catalysts

The photocatalytic oxidation of carbon monoxide over TiO₂–SiO₂ and Pd/TiO₂–SiO₂ catalysts was studied. The catalyst samples were synthesized by using sol–gel technique coupled with hydrothermal treatment and all samples were hydrothermally treated before calcination in air. The catalyst samples were characterized by XRD, BET and DRIFTS techniques. The photocatalytic activity of the samples was determined by using circulated batch photoreactor coupled with in line gas transmission FTIR cell charged with 2,000 ppm carbon monoxide in air initially over 0.5 g of catalyst sample under 33 W (254 nm) irradiation power. XRD and BET results confirmed the presence of anatase phase and the decrease on the crystallite size of TiO₂ with SiO₂ addition which yield higher surface area and better dispersion of TiO₂ over mesoporous SiO₂. DRIFTS results indicated the presence of surface hydroxyls coordinated to Ti⁴⁺ and Si–O–Ti sites. All samples containing 10–90 % TiO₂ over SiO₂ exhibited significant photo oxidation activity at room temperature. The photocatalytic oxidation rate of carbon monoxide is favored by SiO₂ addition due to high surface area, better dispersion of TiO₂ particles and higher surface defects. The addition of PdO improves the photocatalytic activity significantly and the synergy between the TiO₂ and PdO phases.     

Correlative Light-Ion Microscopy for biological applications

Here we report a new technique, Correlative Light-Ion Microscopy (CLIM), to correlate SEM-like micrographs with fluorescence images. This technique presents significant advantages over conventional methods in enabling topographical and biochemical information to be correlated with nanoscale resolution without destroying the fluorescence signal. We demonstrate the utility of CLIM for a variety of investigations of cell substrate interactions validating its potential to become a routine procedure in biomedical research.     

Meat species identification and Halal authentication using PCR analysis of raw and cooked traditional Turkish foods

The method performance characteristics of commercially available PCR kits for animal species identification were established. Comminuted meat products containing different levels of pork were prepared from authentic beef, chicken, and turkey. These meat products were analysed in the raw state and after cooking for 20 min at 200 °C. For both raw and cooked meats, the PCR kit could correctly identify the animal species and could reliably detect the addition of pork at a level below 0.1%. A survey of 42 Turkish processed meat products such as soudjouk, salami, sausage, meatball, cured spiced beef and doner kebap was conducted. Thirty-six samples were negative for the presence of pork (< 0.1%) and four were found to be correctly labelled as containing pork. However, one sausage sample was labelled as containing 5% beef, but beef DNA was not detected and a meatball sample labelled as 100% beef was found to contain chicken. Another turkey meatball sample was predominantly chicken.     

Optimization of temperature and light intensity for improved photofermentative hydrogen production using Rhodobacter capsulatus DSM 1710

Photofermentative hydrogen production is influenced by several parameters, including feed composition, pH levels, temperature and light intensity. In this study, experimental results obtained from batch cultures of Rhodobacter capsulatus DSM 1710 were analyzed to locate the maximum levels for the rate and yield of hydrogen production with respect to temperature and light intensity. For this purpose, a 3^k general full factorial design was employed, using temperatures of 20, 30 and 38 °C and light intensities of 100, 200 and 340 W/m². ANOVA results confirmed that these two parameters significantly affect hydrogen production. Surface and contour plots of the regression models revealed a maximum hydrogen production rate of 0.566 mmol H₂/L/h at 27.5 °C and 287 W/m² and a maximum hydrogen yield of 0.326 mol H₂/mol substrate at 26.8 °C and 285 W/m². Validation experiments at the calculated optima supported these findings.     

Hydrogen supply chain architecture for bottom-up energy systems models. Part 1: Developing pathways

The integration of hydrogen energy systems in the overall energy system is an important and complex subject for hydrogen supply chain management. The efficiency of the integration depends on finding optimum pathways for hydrogen supply. Accordingly, energy systems modelling methods and tools have been implemented to obtain the best configuration of hydrogen processes for a defined system. The appropriate representation of hydrogen technologies becomes an important stage for energy system modelling activities. This study, split in consecutive parts, has been conducted to analyse how representative hydrogen supply pathways can be integrated in energy systems modelling. The current paper, the first part of a larger study, presents stylised pathways of hydrogen supply chain options, derived on the basis of a detailed literature review. It aims at establishing a reference hydrogen energy system architecture for energy modelling tools. The subsequent papers of the study will discuss the techno-economic assumptions of the hydrogen supply chain components for energy modelling purposes.