Antimicrobial effects of selected plant essential oils on the growth of a Pseudomonas putida strain isolated from meat

Dielectric properties of beef biceps femoris muscle were recorded during heating (5-85°C) to assess their linkage to phase changes monitored by differential scanning calorimetry (DSC) and rheology. DSC indicated endotherms between 56 and 81°C corresponding to denaturation of actin, collagen and myosin. Matching changes in dielectric properties (dielectric constant (ε') and loss factor (ε″)) were noted at radio and/or microwave frequencies though the nature of the change differed depending upon frequency. The main observation in ε' was an increase above 65-66°C, most likely due to fluid release on collagen denaturation. This fluid plus liquid from myosin denaturation most likely solvated ions freed during myosin denaturation which manifested as an ε″ increase. However, it must be noted that meat structural protein denaturation is compounded with physical shrinkage which can also influence dielectric properties. Rheological parameters of beef muscle heated from 5 to 85°C also displayed marked changes relating to structural protein denaturation.     

Antimicrobial effects of alginate-based film containing essential oils for the preservation of whole beef muscle

Alginate-based edible films containing 1% (wt/vol) essential oils of Spanish oregano, Chinese cinnamon, or savory were immersed in 2% (wt/vol) or 20% (wt/vol) CaCl2 solution and then applied to beef muscle slices to control the growth of Escherichia coli O157:H7 and Salmonella Typhimurium. Whole beef muscle surfaces were inoculated with one of these strains at 10(3) CFU/cm2. During the 5 days of storage, samples of meat were obtained periodically for microbiological analysis. The availability of active compounds from essential oils present in films was evaluated by determination of total phenolic compounds for oregano- and savory-based films and of total aldehydes for cinnamon-based films during storage. After 5 days of storage, films containing oregano or cinnamon essential oils were the most effective against Salmonella Typhimurium regardless of the type of pretreatment used (2 or 20% CaCl2). During the same period, meat inoculated with E. coli O157:H7 and coated with films treated with 2% CaCl2 had significantly fewer bacteria (P < or = 0.05) when oregano-based films were used than when cinnamon- and savory-based films were used. The E. coli O157:H7 concentration was higher at the end of the storage period when films were pretreated with 20% CaCl2. Evaluation of the active compounds in films revealed that availability in oregano- and savory-based films was significantly more important (P < or = 0.05) than that in cinnamon-based films regardless of the type of pretreatment used (2 or 20% CaCl2). At the end of storage, release rates of 40, 60, and 77% were noted in oregano-, savory-, and cinnamon-based films in 2% CaCl2 and rates of 65, 62, and 90% were noted in the same films in 20% CaCl2.     

Nanometer-sized cerium oxide particles for solid phase extraction of trace amounts of mercury in real samples prior to cold vapor atomic adsorption spectrometry

Ceria (CeO₂) nanoparticles were synthesized using the microwave-assisted heating technique and employed as a sorbent for preconcentration of trace amounts of Hg(II) ions from aqueous solutions for the first time. The analysis of mercury was performed by cold vapor atomic absorption spectrometry (CV-AAS). The characteristics of nanoparticles were assessed using X-ray diffraction (XRD) and transmission electron microscopy (TEM) techniques. Experimental parameters influencing the extraction procedure recovery were thoroughly investigated. Under the optimized experimental conditions, the calibration curve was linear in the range of 0.035–0.8 µg/L of mercury. The method was validated by analysis of a certified reference material.     

A Pd(II) Magnetically Retrievable Catalyst for Hiyama Reaction: Functionalization of Magnetic Mesoporous Silica via Click Reaction

Catalysis Letters - A nitrogen ligand, i.e. 1,3-di-(o-aminophenoxy)-2-propyl propargyl ether (DPPE), has been synthesized and characterized. Magnetic mesoporous silica composite (MNP@SiO2-SBA) was...     

Advances in Triboelectric Nanogenerators for Self-Powered Regenerative Medicine

Over the last decade, in pursuit to provide suitable alternatives for power supplies of medical devices in regenerative medicine, extensive research on nanogenerators has been developed. Such devices can overcome current commercial battery challenges, including intense heat-on-body complications due to the electrical current during therapeutic usage, leading to protein denaturation, cell structure destruction, and even cell necrosis. In addition, these traditional batteries contain a bulky and heavy structure that prevents them from providing sustainable on body biomedical therapeutic intervention. Furthermore, advantages such as wide-range biocompatible and biodegradable materials, lightweight, and sufficient stretchability for device construction can minimize the side effects of implantable devices, including inflammation or toxicity, as well as eliminate secondary surgery to replace or remove batteries. Triboelectric nanogenerators (TENGs) are associated with harvesting mechanical energy in various forms, among which human body motions can serve as a renewable power source for healthcare systems. This review is written to emphasize the importance of TENG's applications in regenerative medicine and modulation purposes, particularly for the nervous system. Some crucial parameters for implantable consideration are discussed. In the concluding remarks, features for clinical utilization including output efficiency, encapsulation, stability, and miniaturization are suggested as challenges and prospects.     

Evaluating technological emergence using text analytics: two case technologies and three approaches

Scientometrics - Scientometric methods have long been used to identify technological trajectories, but we have seldom seen reproducible methods that allow for the identification of a technological...     

Porous conductive and biocompatible scaffolds on the basis of polycaprolactone and polythiophene for scaffolding

Polymer Bulletin - The fabrication of novel scaffolds was represented on the basis of conductive and biodegradable copolymers. The star-like polycaprolactone (S-PCL) was synthesized from...     

Highly selective hydrogen production from propane by Ru–Ni core–shell nanocatalyst deposited on reduced graphene oxide by sequential chemical vapor deposition

A narrow temperature window (160°C-190°C) was identified for the selective deposition of Ru on Ni supported on reduced graphene oxide (rGO) through a sequential chemical vapor deposition (CVD) method. Cyclopentadiene and cyclopentene were identified as decomposition products of nickelocene CVD on rGO, whereas only methane was detected in gaseous products from ruthenocene CVD. Heat treatment converted the selectively deposited Ru on Ni/rGO into Ru–Ni core–shell bimetallic system on the surface of rGO as confirmed by high-resolution transmission electron microscopy. The Ru–Ni/rGO thus prepared produced hydrogen with high selectivity in propane steam reforming performed in the temperature range of 350°C to 850°C. Addition of 3.6% Ru against Ni supported on rGO improved the turnover frequency (TOF) of propane up to 70% to 100% compared to the Ni/rGO catalyst at lower temperatures (350°C-450°C). The presence of Ru lowered the activation energy of propane SR from 65.7 kJ mol⁻¹ for Ni/rGO to 48.7 kJ mol⁻¹ for Ru–Ni/rGO catalyst.     

The effect of foamed cement nanocomposite as counter electrode on the performance of dye-sensitized solar cell

Improper interparticle connection between carbon-based materials, poor interface bonding between the carbon counter electrodes (CEs) and substrate, and low surface area are the main limitations of carbon-based CEs in dye-sensitized solar cells. In this study, we utilized foamed cement and binder for adherence and surface area improvement in carbon-based CEs, such as graphite, multi-walled carbon nanotubes, and carbon black (CB). The results revealed that incorporating foamed cement into carbon materials improved the resistance, short-circuit current density, fill factor, and power conversion efficiency of the device. The porous cement/CB nanocomposite CE with a photoconversion efficiency of 5.51% exhibited the best photovoltaic performance. Moreover, this nanocomposite electrode showed an enhancement catalytic activity by high current density in cyclic voltammogram, low charge transfer resistance $(R_{CT}$) in electrochemical impedance spectroscopy, and high exchange current density in Tafel measurements compared to other electrodes. The porosity of foamed cement has been found to be the main cause of its superior photovoltaic performance, which expands the contact area with the electrode and enables rich ion transport. Additionally, the enhanced performance was due to strong bonding, crack-free deposited films, superior conductivity, and high catalytic activity.