Physical sciences reviews 

About: Physical sciences reviews is an academic journal published by De Gruyter. The journal publishes majorly in the area(s): Chemistry & Biology. It has an ISSN identifier of 2365-659X. Over the lifetime, 786 publications have been published receiving 2985 citations. The journal is also known as: Physical sciences reviews.

Synthesis and characterization of size- and shape-controlled silver nanoparticles

Abstract: Abstract Silver nanoparticles (AgNPs) have application potential in diverse areas ranging from wound healing to catalysis and sensing. The possibility for optimizing the physical, chemical and optical properties for an application by tailoring the shape and size of silver nanoparticles has motived much research on methods for synthesis of size- and shape-controlled AgNPs. The shape and size of AgNPs are reported to vary depending on choice of the Ag precursor salt, reducing agent, stabilizing agent and on the synthesis technique used. This chapter provides a detailed review on various synthesis approaches that may be used for synthesis of AgNPs of desired size and shape. Silver nanoparticles may be synthesized using diverse routes, including, physical, chemical, photochemical, biological and microwave -based techniques. Synthesis of AgNPs of diverse shapes, such as, nanospheres, nanorods, nanobars, nanoprisms, decahedral nanoparticles and triangular bipyramids is also discussed for chemical-, photochemical- and microwave-based synthesis routes. The choice of chemicals used for reduction and stabilization of nanoparticles is found to influence their shape and size significantly. A discussion on the mechanism of synthesis of AgNPs through nucleation and growth processes is discussed for AgNPs of varying shape and sizes so as to provide an insight on the various synthesis routes. Techniques, such as, electron microscopy, spectroscopy, and crystallography that can be used for characterizing the AgNPs formed in terms of their shape, sizes, crystal structure and chemical composition are also discussed in this chapter. Graphical Abstract:

Polymers application in proton exchange membranes for fuel cells (PEMFCs)

Abstract: Abstract This review presents the most important research on alternative polymer membranes with ionic groups attached, provides examples of materials with a well-defined chemical structure that are described in the literature. Furthermore, it elaborates on the synthetic methods used for preparing PEMs, the current status of fuel cell technology and its application. It also briefly discusses the development of the PEMFC market.

The halogen bond: Nature and applications

Abstract: Abstract The halogen bond, corresponding to an attractive interaction between an electrophilic region in a halogen (X) and a nucleophile (B) yielding a R−X⋯B contact, found applications in many fields such as supramolecular chemistry, crystal engineering, medicinal chemistry, and chemical biology. Their large range of applications also led to an increased interest in their study using computational methods aiming not only at understanding the phenomena at a fundamental level, but also to help in the interpretation of results and guide the experimental work. Herein, a succinct overview of the recent theoretical and experimental developments is given starting by discussing the nature of the halogen bond and the latest theoretical insights on this topic. Then, the effects of the surrounding environment on halogen bonds are presented followed by a presentation of the available method benchmarks. Finally, recent experimental applications where the contribution of computational chemistry was fundamental are discussed, thus highlighting the synergy between the lab and modeling techniques.

Analytical Techniques for Trace Element Determination

Abstract: A lot of elements occur in different matrices at low levels of content, and a lot of these elements were not detectable by analytical methods for a long time. The knowledge about their presence appeared with the development of analytical technology and caused the origin of the term “trace elements.” Trace element defined by IUPAC [1] is any element having an average concentration of less than about 100 parts per million atoms or less than 100 mg/kg. In the second half of the 20th century, together with rapid increase of detection capabilities of analytical techniques, a new term of ultratrace elements appeared. Even though the term exists and is commonly used, there is no rigid definition. Ultratrace concerns elements at mass fraction below 1 ppm. The knowledge of trace and ultratrace elements is very important in various fields of science, industry, and technology. Ultralow concentrations of elements might be as well essential as hazardous doses for organisms; some traces can dramatically change properties of designed devices. Therefore, the need for accurate measurements at low amount of contents is required and very important. The common use of extremely sensitive instrumentation needs the adequate control of contamination and verification of the accuracy of determination. The gain of analytical sensitivity multiplied contamination as well as other problems. Therefore, correct precautions should be taken to determine trace elements in the parts per billion concentration range and below. Errors during trace and ultratrace elemental analysis can be caused by improper sampling, storage, sample preparation, and, finally, by analysis itself. Therefore, an accuracy of an analytical determination should be always established. Collecting a representative sample without contaminating is a key to the meaningful analysis and Thiers’ words from 1957 “unless the complete history of any given sample is known with certainty, the analyst is well advised not to spend his time analyzing it” [2] is always up to date. Nowadays, there are a large number of available analytical techniques allowing for trace and ultratrace analysis of elemental composition. For the trace elements that are present in parts per million concentration range, the most widely used technique is probably atomic absorption spectrometry with flame atomization. For ultratrace elements present in concentration of parts per billion and below, the number of suitable techniques drops due to the required analytical sensitivity. The determination of trace elements is commonly held with potentiometry, voltammetry, atomic spectrometry, X-ray, and nuclear methods. Electrochemical methods can measure either free ions in solution (potentiometry) or free ions together with ions bound in labile complexes (voltammetry), and they can also provide analysis of the oxidation state of some of the elements. Atomic spectrometric techniques are very sensitive and can be used to measure the total element content within a sample; however, accuracy of these techniques can be affected by the matrix of the sample. X-ray and nuclear techniques provide very low limit of detections and matrix insensitivity and are used for comparison of results due to their principles fundamentally different from those of the other analytical techniques. Therefore, they are less likely to be prone to the same systematic biases. Benefits and losses of each technique should concern the number of analytes possible to measure with the use of the technique, occurrence of interferences and difficulties, detection limits, throughput of samples, and expenses. The determination of trace elements and contaminants in complex matrices often requires extensive sample preparation and/or extraction prior to instrumental analysis. A large number of samples that need to have determined the concentration of essential and toxic elements belong to food [3, 4], environmental [5, 6], clinical and biological [5–7, 7–9] samples. Routinely, the determination of trace metals has been carried out by inductively coupled plasma atomic emission spectrometry (ICPAES), inductively coupled plasma mass spectrometry (ICPMS), electrothermal atomic absorption spectrometry (ETAAS), and flame atomic absorption spectrometry (FAAS). However, matrix of many samples (biological, clinical, environmental, etc.) is complex and consists of high amounts of soluble solid substances and large amounts of inorganic compounds (i.e., salts of Ca, K,

DFT computations on vibrational spectra: Scaling procedures to improve the wavenumbers

Abstract: Abstract The performance of ab initio and density functional theory (DFT) methods in calculating the vibrational wavenumbers in the isolated state was analyzed. To correct the calculated values, several scaling procedures were described in detail. The two linear scaling equation (TLSE) procedure leads to the lowest error and it is recommended for scaling. A comprehensive compendium of the main scale factors and scaling equations available to date for a good accurate prediction of the wavenumbers was also shown. Examples of each case were presented, with special attention to the benzene and uracil molecules and to some of their derivatives. Several DFT methods and basis sets were used. After scaling, the X3LYP/DFT method leads to the lowest error in these molecules. The B3LYP method appears closely in accuracy, and it is also recommended to be used. The accuracy of the results in the solid state was shown and several additional corrections are presented.