Different Types Of Molecules Research Articles

Application of Ribonucleic Acid (RNA) in Forensic Sciences

<p>Forensic science has been helping law enforcement agencies in better understanding and presenting the evidence in the court of law. In certain situations, when conventional forensic methods of investigations cannot make better conclusions with more specific accuracy, then molecular techniques do help in reaching the acquired accuracy in the results regarding the identification of evidence. Advanced molecular techniques, which are using Deoxyribose Nucleic acid (DNA), Ribose Nucleic Acid (RNA), and protein molecules to produce forensically important information from the samples recovered at the crime scene. DNA can only distinguish among individuals but is unable to discriminate the type of samples originated from the same sample. For this RNA has become a molecule of interest for its different levels of expressionin different cells/tissues of an individual. RNA molecules of different types are being used to build up models for several purposes (injury-age, new-born age, molecular cause of death, etc.). Modern techniques like Real-time Polymerase Chain Reaction (PCR) and Microarray are being used for the detection of RNA molecules of interest both in the form of its abundance and as a unique molecular detection. This script will help in understanding the importance of RNA application in forensic sciences by providing an overview of the research done to date and the techniques being used for this purpose.</p>

Sum capacity analysis of mobile broadcast diffusive molecular communication

In this paper, we study the mobile broadcast diffusive molecular communication (DMC) system which is composed of one mobile transmitter nanomachine (TN) and multiple mobile receiver nanomachines (RNs). Considering that the reception event at each RN is different due to the time-varying impulse response of the mobile diffusion channel, in order to ensure that RNs can share the common information from TN with lower bit error probability (BEP), we add two fusion centers (FCs) in this system which are used to gather the information from RNs to make global decisions by using an N-out-of-K fusion rule. We propose three reporting schemes for the transmission between RNs and FCs including perfect reporting, different type of molecules and same type of molecules. Then the mathematical expressions of the optimal decision thresholds at RNs and FCs by using maximum-a-posterior detection method are obtained. On this basis, the BEP and sum capacity under the three reporting schemes are analyzed. Furthermore, the impacts of different parameters and reporting schemes on the performance of this system are evaluated and discussed by the numerical results. The setting of these parameters and reporting schemes can be used to provide the guideline for designing the mobile broadcast DMC system with lower BEP and higher sum capacity.

Mechanism for H2 diffusion in sII hydrates by molecular dynamics simulations

Among the many different types of molecules that form clathrate hydrates, H2 is unique as it can easily diffuse into and out of clathrate cages, a process that involves the physical-chemical interactions between guest (H2) and host (water) molecules, and is unlike any other molecular system. The dynamic and nano-scale process of H2 diffusion into binary structure II hydrates, where the large cages are occupied by larger molecules, was studied using molecular dynamics simulation. As the H2 molecules diffused from one cage to another, two types of diffusion processes were observed: (i) when moving between a pair of large cages, the H2 molecules pass through the central part of the hexagonal rings; (ii) however, when the H2 molecules move from a large cage to a small one, it requires one of the pentagonal rings to partially break, as this allows the H2 molecule to pass through the widened space. While the diffusion of H2 molecules between large cages was found to occur more frequently, the presence of SF6 molecules in the large cages was found to inhibit diffusion. Therefore, in order to attain higher H2 storage capacities in binary hydrates, it is suggested that there is an optimal number of large cages that should be occupied by SF6 molecules.

Extraction and purification of peroxidase and trypsin inhibitor from soybean hulls: A strategy to revalue a waste as a source of different types of molecules of biotechnological interest

In this work, the extraction and purification of proteins present in soybean hull has been carried out, using simple methods and with the potential to be scaled. In the first stage, using statistical tools, the optimization of peroxidase extraction and various protease inhibitor factors was achieved through a leaching process using 50 mM phosphate buffer pH 6.00. The optimal conditions to achieve the best extraction of the proteins of interest were the following: contact time (360 min), mass/volume ratio (0.066) and particle size (40 mesh). The extract obtained was characterized by an electrophoresis gel, mass spectrometry and by measuring enzymatic activity, which, allowed to confirm the presence of the proteins of interest. Finally, the purification of peroxidase and protease inhibitors were optimized by adsorption onto aminated cellulose bed obtained from the same soybean hull. Under the optimal conditions, the peroxidase present in the extract was purified 8.1 times with a yield of 66.6%. While protease inhibitors were purified 2.5 times with a yield of 26.1%.

Automated Robotic Microinjection of the Nematode Worm Caenorhabditis elegans

The nematode worm Caenorhabditis elegans is a model organism widely used in biological research on genetics, development, neuroscience, and aging. Microinjection is an effective and widely adopted method to create transgenetic worms, perform ribonucleic acid (RNA) interference of certain genes, and introduce different types of molecules into specific locations inside a worm body. Based on microfluidics and robotic micromanipulation techniques, we develop a robotic system for automated microinjection of C. elegans with greatly improved injection speed and success rate over traditional manual microinjection. A double-layer microfluidic device with computer-controlled pneumatic valves is developed for automated on-chip loading, immobilization, injection, and downstream sorting of single worms. A new autofocusing-based contact detection algorithm is proposed to find the optimal injection position along the depth direction of the microscope field of view. The direction and location of the needle tip are reliably identified using an image processing algorithm. Through experiments on 240 worms, the system demonstrates automated injection at a speed of 6 worms/min (9.97 s/worm) with a presorting operation success rate of 78.8% (postsorting operation success rate: 100%), which are more than 23 times faster and 1.6 times higher than the speed (0.25 worm/min) and success rate (30%) of a proficient human operator, respectively. With the superior performance, this system will enable new large-scale gene- and molecule-screening studies on C. elegans that cannot be fulfilled by the conventional microinjection technique.

Electrospinning of Cyclodextrin Nanofibers: The Effect of Process Parameters

Cyclodextrin (CD) nanofibers have recently emerged as high-performance materials owing to their large surface area-to-volume ratio, along with the presence of high active CD content for their applications in drug delivery and water treatment. Even though there are several studies on the polymer-free electrospinning of CD molecules of different types, the effects of electrospinning process parameters on the morphology and diameter of the resultant fibers have not addressed yet. In this study, the influence of electrospinning process variables on the morphology and diameter of the resultant CD nanofibers is systematically studied using two different solvent systems, i.e., water and N, N-dimethylformamide (DMF). On adjusting the electrospinning process parameters (i.e., electrical field, flow rate, tip-to-collector distance (TCD), and needle diameter), uniform CD nanofibers could be produced from aqueous and DMF solutions. Generally, the electrospinning of thicker fibers was observed by increasing the applied voltage and flow rate due to higher mass flow. Increasing TCD boosted the fiber diameter. Likewise, the use of needles with larger diameters resulted in the electrospinning of thicker fibers from DMF solutions, which might be attributed to higher viscosity due to reduced shear rate.

Extracellular Vesicles: A Therapeutic Option for Liver Fibrosis.

Extracellular vesicles (EVs) are a heterogeneous population of small membrane vesicles released by all types of cells in both physiological and pathological conditions. EVs shuttle different types of molecules and are able to modify the behavior of target cells by various mechanisms of action. In this review, we have summarized the papers present in the literature, to our acknowledge, that reported the EV effects on liver diseases. EVs purified from serum, stem cells, and hepatocytes were investigated in different experimental in vivo models of liver injury and in particular of liver fibrosis. Despite the different EV origin and the different types of injury (toxic, ischemic, diet induced, and so on), EVs showed an anti-fibrotic effect. In particular, EVs had the capacities to inhibit activation of hepatic stellate cells, one of the major players of liver fibrosis development; to reduce inflammation and apoptosis; to counteract the oxidative stress; and to increase hepatocyte proliferation, contributing to reducing fibrosis and ameliorating liver function and morphology.

For organic chemists, micellar chemistry could be a revolution

Water is called the universal solvent for its ability to dissolve a broad range of chemicals. But you wouldn’t know that from spending time in chemistry labs, where the solvents of choice are almost exclusively organic. Water can react with so many different types of molecules that it can prevent scientists from getting good results out of complex reactions. So, many synthetic chemists see water as a hazard. Many, but not all. In the past several years, a small group of chemists has been experimenting with a technique that makes synthetic chemistry possible in water. Using surfactant molecules like detergents, these researchers can form microscopic spheres in water called micelles. The insides of these particles have an environment that’s friendly to greasy organic molecules. They are like tiny flasks, perfect for hosting organic reactions and shielding them from surrounding water molecules. Micellar chemistry—and chemistry in water in general—is often pitched

Nano-atomic scale hydrophobic/philic confinement of peptides on mineral surfaces by cross-correlated SPM and quantum mechanical DFT analysis.

The fundamental knowledge of the interaction between biomolecules and mineral surfaces is of utmost importance to drive new technological advancements, particularly for condensation, aggregation, catalysis and exchange of biomolecules. The mineral surface can be used in several fields and applications, for instance in biotechnology, environmental science and remediation, soil science, agro-food and related technology. This kind of knowledge may also provide several suggestions and have implications also for the prebiotic chemistry field, namely the study of the abiotic physicochemical steps that could have led to the 'creation' of the first known living organism. Nowadays, this kind of information at the micro and nanometric scale can be explored with several experimental and theoretical techniques and, among them, atomic force microscopy (AFM)-related methods and density functional theory (DFT) are particularly suited to investigate adsorption processes at single molecule level. In the present work, the specific interaction at the atomic scale between a small peptide (di-glycine) and the (001) surface of clinochlore, a mineral presenting alternately stacked talc-like layers (hydrophilic) and brucite-like sheets (hydrophobic), was characterized by means of a cross-correlated approach combining AFM and DFT simulations. The experiments evidenced the preferential adsorption of di-glycine onto the hydrophobic brucite-like sheet of the mineral, with the observed molecules organized as dot-like (single-molecules), agglomerates, filament-like and network structures by the surface, whereas only very few peptides were imaged onto the hydrophilic talc-like layer. From the theoretical analysis, the most stable conformation of the di-glycine peptide adsorbed on the mineral surface was calculated, and the binding energy analysis of the specific interaction of the molecule, depending on the local chemistry of the substrate, provided fundamental information to interpret end explain the experimental evidence. LAY DESCRIPTION: The present work aims at extending the knowledge of the biomolecules/minerals interaction world. The fundamental knowledge of the interaction between biomolecules and mineral surfaces is of utmost importance to drive the development of new technological advancements, particularly for condensation, aggregation, catalysis and exchange of biomolecules. The mineral surface can be used as substrate in several fields and applications, for instance in biotechnology, environmental science and remediation, soil science, agro-food and related technology. This kind of research may also provide several suggestions and have implications also for the prebiotic chemistry field, namely the study of the abiotic physicochemical steps that could have led to the "creation" of the first known living organism. Nowadays, this kind of research at the micro and nanometric scale can be performed with several experimental techniques and, among them, scanning probe microscopy-related methods are particularly suited to investigate surface adsorption processes at single molecule level. In the present work, the focus is on the specific interaction at the atomic scale between a small peptide (di-glycine) and the surface of clinochlore (a diffuse clay mineral). Clinochlore is a mineral belonging to the phyllosilicate, formed by alternately stacked hydrophilic talc-like layers [chemical formula Mg3 Si4 O10 (OH)2 ] and hydrophobic brucite-like sheets [magnesium hydroxide, Mg(OH)2 ]. Since these two kind of layered structures are held together by weak (van der Waals) forces, the mineral can be easily cleaved along the [001] crystallographic direction (the stacking direction) and the resulting (001) clinochlore surface may presents at the nanoscale some remainders of one layer (brucite-like or talc-like) on the other. This means that this mineral exposes to the environment two different type of surfaces, one hydrophilic and one hydrophobic, which can selectively interact with (adsorb) different type of molecules at the nanoscale. Clinochlore is also one of the 420 mineral species that were likely present on Earth at the time of life's origins, thus it could have played a fundamental role in prebiotic chemistry. In this study, the interaction between di-glycine and clinochlore was characterized by means of both atomic force microscopy (AFM) at the nanometric scale and density functional theory (DFT) simulations, correlating the results of the two methods (cross-correlation approach). The experiments evidenced the preferential adsorption of di-glycine onto the hydrophobic brucite-like sheet of the mineral, with the observed molecules organized as dot-like (single-molecules) structures, agglomerates, filaments and networks by the surface, whereas only very few peptides were imaged onto the hydrophilic talc-like layer. From the theoretical analysis, the most stable conformation of the di-glycine adsorbed on the mineral surface was calculated, and the binding energy analysis of the specific interaction of the molecule, depending on the local chemistry of the substrate, provided fundamental information to interpret end explain the experimental evidence.

Two-Way Molecular Communications

For nano-scale communications, there must be cooperation and simultaneous communication between nano devices. To this end, in this paper, we investigate two-way (a.k.a. bi-directional) molecular communications between nano devices. If different types of molecules are used for the communication links, the two-way system eliminates the need to consider self-interference. However, in many systems, it is not feasible to use a different type of molecule for each communication link. Thus, we propose a two-way molecular communication system that uses a single type of molecule. We derive a channel model for this system and use it to analyze the proposed system’s bit error rate, throughput, and self-interference. Moreover, we propose analog- and digital- self-interference cancellation techniques. The enhancement of link-level performance using these techniques is confirmed with both particle-based simulations and analytical results.

Experimental and Theoretical Insights to Physicochemical Properties of Aqueous Solutions of 1, 2-Ethanediol and 1, 2, 3-Propanetriol at Different Temperatures

Water is designated as “Universal solvent” due to its physical and chemical attributes. Water becomes attracted to different types of molecules due to the polar arrangement of oxygen and hydrogen atoms having partial negative and positive charges. The density (ρ), ultrasonic velocity (U), viscosity (η) and refractive index (nD) of the aqueous solutions of 1, 2-ethanediol / 1, 2, 3-propanetriol have been determined at three different temperatures. Derived properties such molar volume (V), isentropic compressibility (ᵝs), acoustic impedance (Z) and free length (Lf) have been calculated using density, ultrasonic velocity and refractive index values at the measured temperatures. To evaluate various, inter and intra-molecular associations present in the systems, the excess properties (VE, ᵝsE, ZE, Lf E, ηE and ∆nD) are estimated. The excess values obtained experimentally have been fitted to the Redlich -Kister polynomial equation. Multiple linear regression and mixing rules have been adopted to calculate the viscosity and refractive index for the aqueous solutions at 298.15, 308.15 and 318.15K.

The vaccine journey for COVID-19: a comprehensive systematic review of current clinical trials in humans

Since December 2019, there has been an outbreak of a novel beta-Coronavirus (SARS-CoV-2) in Wuhan, China. On March 11, 2020, the World Health Organization (WHO) declared COVID-19 as a pandemic, with over 118,000 cases in more than 110 countries around the world. In response to the global Coronavirus disease 2019 (COVID-19) emergency, clinical trial research assessing the efficacy and safety of experimental vaccines to prevent COVID-19 are emerging at an unprecedented rate. The aim of this systematic review was to summarize the preliminary experiences and ongoing clinical trials of the major candidates and challenges of the vaccine strategies in humans. After a-priori protocol registration with PROSPERO (181483), systematic research of the published literature was conducted on April 24, 2020, using Medline (via PubMed), Embase (via Ovid), and WHO databases. Moreover, to explore the more recent literature we also searched the preprint server medRxiv. Finally, we scrutinized the Cochrane COVID-19 study register and the COVID-19 section of ClinicalTrials.gov database to identify relevant ongoing clinical trials. Thereafter we selected the articles according to the PRISMA Guidelines. Animal or in-vitro experimental studies were excluded. Moreover editorials, commentaries, abstracts, reviews, book chapters, and articles not in English were not included. Our search identified 1359 published papers, 478 preprint articles and 367 ongoing clinical trials. Finally, only ten ongoing clinical trials met the inclusion criteria. Specifically, seven developed vaccines for the S protein of SARS-CoV-2 and three clinical trials assessed the protective role of BCG vaccine against COVID-19. The first group included phase I/II trials with different types of molecules (DNA or mRNA vaccine, bacterial plasmid or viral vectors), the latter were phase III/IV trials designed on the basis of a heterologous lymphocyte activation by the BCG vaccine. This new disease is pushing the scientific community to develop swiftly a safe and effective vaccine. Notwithstanding the limitations of our analysis, given by the absence of available results, we try to provide a comprehensive view of the ongoing clinical trials in humans. Our analysis reveals a worldwide effort of both scientists and enterprises to achieve one of the most challenging goals of our century.

Inorganic Gold and Polymeric Poly(Lactide-co-glycolide) Nanoparticles as Novel Strategies to Ameliorate the Biological Properties of Antimicrobial Peptides.

Cationic antimicrobial peptides (AMPs) are an interesting class of gene-encoded molecules endowed with a broad-spectrum of anti-infective activity and immunomodulatory properties. They represent promising candidates for the development of new antibiotics, mainly due to their membraneperturbing mechanism of action that very rarely induces microbial resistance. However, bringing AMPs into the clinical field is hampered by some intrinsic limitations, encompassing low peptide bioavailability at the target site and high peptide susceptibility to proteolytic degradation. In this regard, nanotechnologies represent an innovative strategy to circumvent these issues. According to the literature, a large variety of nanoparticulate systems have been employed for drug-delivery, bioimaging, biosensors or nanoantibiotics. The possibility of conjugating different types of molecules, including AMPs, to these systems, allows the production of nanoformulations able to enhance the biological profile of the compound while reducing its cytotoxicity and prolonging its residence time. In this minireview, inorganic gold nanoparticles (NPs) and biodegradable polymeric NPs made of poly(lactide-coglycolide) are described with particular emphasis on examples of the conjugation of AMPs to them, to highlight the great potential of such nanoformulations as alternative antimicrobials.

Recent advances in understanding mitochondrial genome diversity.

Ever since its discovery, the double-stranded DNA contained in the mitochondria of eukaryotes has fascinated researchers because of its bacterial endosymbiotic origin, crucial role in encoding subunits of the respiratory complexes, compact nature, and specific inheritance mechanisms. In the last few years, high-throughput sequencing techniques have accelerated the sequencing of mitochondrial genomes (mitogenomes) and uncovered the great diversity of organizations, gene contents, and modes of replication and transcription found in living eukaryotes. Some early divergent lineages of unicellular eukaryotes retain certain synteny and gene content resembling those observed in the genomes of alphaproteobacteria (the inferred closest living group of mitochondria), whereas others adapted to anaerobic environments have drastically reduced or even lost the mitogenome. In the three main multicellular lineages of eukaryotes, mitogenomes have pursued diverse evolutionary trajectories in which different types of molecules (circular versus linear and single versus multipartite), gene structures (with or without self-splicing introns), gene contents, gene orders, genetic codes, and transfer RNA editing mechanisms have been selected. Whereas animals have evolved a rather compact mitochondrial genome between 11 and 50 Kb in length with a highly conserved gene content in bilaterians, plants exhibit large mitochondrial genomes of 66 Kb to 11.3 Mb with large intergenic repetitions prone to recombination, and fungal mitogenomes have intermediate sizes of 12 to 236 Kb.

Payload delivery of anticancer drug Tegafur with the assistance of graphene oxide nanosheet during biomembrane penetration: Molecular dynamics simulation survey

It is known that the interaction of drug molecules with biomembranes affects their pharmacokinetic parameters. Biological membranes as physical barrier limit diffusion of different types of molecules across the membranes. For that, the drug delivery systems (DDS) are used to increase drug membrane permeability. In this work, the molecular dynamics (MD) simulation is performed to evaluate the mechanism of graphene oxide nanosheet (GO) as Tegafur (TG) drug delivery cargo across the cell membrane. MD simulation shows the spontaneously attraction of GO to the cell membrane during the initial time of simulation. It is found that the complete parallel orientation of nanosheet and further partially its insertion into the membrane is facilitated by increasing the hydrogen bonds (HBs) formation between the oxygen-containing groups of GO and lipid bilayer throughout the simulation trajectory. Molecular dynamics simulation reveals slow release of TG drug molecules from the graphene oxide nanosheet surface near the cell membrane, which highlights the efficiency of GO as a good carrier for the controlled release of Tegafur drug. This study reinforces the consideration of graphene oxide nanosheet for delivering an elevated therapeutic dose directly on the cancer cell target in biomedical applications.

Total Synthesis of Natural Products with Bridged Bicyclo[m.n.1] Ring Systems via Type II [5 + 2] Cycloaddition.

Natural products containing bridged ring systems are widely identified and show significant biological activity. The development of efficient synthesis reactions and strategies to construct bridged ring systems is a long-standing but very significant challenge in organic chemistry. In 2014, our group developed a unique type II [5 + 2] cycloaddition reaction that provides a facile and direct methodology for constructing highly functionalized bridged bicyclo[4.3.1], bicyclo[4.4.1], bicyclo[5.4.1], bicyclo[6.4.1], and other bicyclo[m.n.1] systems containing a strained bridgehead double bond. In this Account, we summarize the methodology development and report the results of application of our unique strategy for the total synthesis of several natural products with bridged ring systems (i.e., cyclocitrinol, cerorubenic acid-III, and vinigrol) during the past 5 years in our laboratory. In the first part, we introduce the logic behind the design and discovery of type II [5 + 2] cycloadditions. The substrates can be easily synthesized by a modular approach, followed by base-promoted group elimination under heat to form an oxidopyrylium ylide, which can undergo cycloaddition under relatively mild conditions with a variety of double bonds to generate bridged bicyclo[m.n.1] frameworks in high yield. The diastereocontrol and unique endo selectivity of this methodology are favorable for further application to the synthesis of complex natural products. In the second part, we highlight our endeavors in the total synthesis of several different types of molecules bearing bridged ring systems using our methodology. The bridged bicyclo[4.4.1] system is the core structure of two different types of natural products, cyclocitrinol and cerorubenic acid-III, that can be efficiently constructed by type II [5 + 2] cycloadditions. The development of suitable strategies and methods for site-selective cleavage of the C-O bond of the oxa-[3.2.1] ring system in the products of type II [5 + 2] cycloadditions is also discussed and highlighted during the syntheses. Moreover, the bridged bicyclo[5.3.1] system is the core structure of vinigrol, which can be constructed through a novel ring contraction sequence of the bicyclo[5.4.1] system formed by a type II [5 + 2] cycloaddition. By combining with a ring contraction cascade, we believe that type II [5 + 2] cycloadditions have the potential to be used as a unified approach to constructing natural products containing bridged bicyclo[m.n.1] frameworks.

Identification of Pathway-Specific Protein Domain by Incorporating Hyperparameter Optimization Based on 2D Convolutional Neural Network

Pathway-specific protein domain (PSPD) are associated with specific pathways. Many protein domains are pervasive in various biological processes, whereas other domains are linked to specific pathways. Many human disease pathways, such as cancer pathways and signaling pathway-related diseases, have caused the loss of functional PSPD. Therefore, the creation of an accurate method to predict its roles is a critical step toward human disease and pathways. In this study, we proposed a deep learning model based on a two-dimensional neural network (2D-CNN-PSPD) with a pathway-specific protein domain association prediction. In terms of the purposes of a sub-pathway, its parent pathway and its super pathway are linked to the Uni-Pathway. We also proposed a dipeptide composition (DPC) model and a dipeptide deviation (DDE) model of feature extraction profiles as PSSM. Then, we predicted the proteins associated with the same sub-pathway or with the same organism. The DDE model and DPC model of the PSSM feature profile input was associated with our proposed 2D-CNN method. We deployed several parameters to optimize the model’s output performance and used the hyperparameter optimization approach to find the best model for our dataset based on the 10-fold cross-validation results. Ultimately, we assessed the predictive performance of the current model by using independent datasets and cross-validation datasets. Therefore, we enhanced the efficiency of deep learning methods. PSPD is involved in any known pathway and then follow the association in different stages of the pathway hierarchy with other proteins. Our proposed method could identify 2D-CNN-PSPD with 0.83% sensitivity, 0.92% specificity, 87.27% accuracy, and 0.75% accuracy. We provided an important method for the analysis of PSPD proteins in the proposed research, and our achievements might promote computational biological research. We concluded our proposed model architecture in the future, the use of the latest features, and the multi-one structure to predict different types of molecules, such as DNA, RNA, and disease-pathway specific proteins associations.

Effects of Framing Errors on the Performance of Molecular Communications With Memory

In conventional digital communication systems, synchronous transmission is achieved by embedding the clocking information into the data signal. However, the implementation of this technique in molecular communication systems, which rely on the diffusion of molecules as information carriers, becomes very complex due to the randomness of the diffusion process. Hence, in this paper we consider the molecular communication between two nanoscale devices with no exchange of any clock signal. To initiate the communication, the transmitter sends a special molecular symbol called beacon in order to trigger the detection process in the receiver. Therefore, this beacon symbol is equivalent to the start bit used for framing in asynchronous serial communication systems. We assume that both transmitter and receiver clocks are perfect, but not synchronized. Accordingly, the analysis focuses on the effects of framing errors on the performance of the molecular channel, measured via the symbol error probability. These errors are inherent to the random nature of the beacon arrival instant, which tends to degrade the alignment between the transmitter and receiver frames. We also assume a molecular channel with any level of inter-symbol interference and the use of different types of molecules to encode information symbols. We validate the derived SEP expression by means of extensive simulation experiments, and finally we develop a design scheme for the beacon symbol that satisfactorily mitigates the effects of framing errors.

On dielectric relaxation equation for anisotropic polarizable reacting fluid mixtures

In this paper a linear theory for dielectric relaxation phenomena in polarizable reacting fluid mixtures is developed, in the frame of thermodynamics of irreversible processes with internal variables. The microscopic irreversible phenomena giving rise to dielectric relaxation are described splitting the total specific polarization in two irreversible parts and introducing one of these partial specific polarizations as internal variable in the thermodynamic state vector. The phenomenological equations for these fluid mixtures are derived and, in the linear case, a generalized Debye equation for dielectric relaxation phenomena is derived. Special cases are also treated. Linear theories for polarizable continuous media with dielectric relaxation phenomena were derived in the same frame of non-equilibrium thermodynamics with internal variables in previous papers by one of the authors (LR). A phenomenological theory for these phenomena was developed by Maugin for complex materials, using microscopic considerations and introducing articular partial polarizations per unit mass. The obtained results in this paper have applications in several fields of applied sciences, as, for instance, in medicine and biology, where complex fluids presenting dielectric relaxation, are constitued by different types of molecules, with own dielectric susceptibility and relaxation time.

Recovery, Purification, and Reusability of Building Blocks for Solid Phase Synthesis.

Solid phase synthesis (SPS) is well established for the synthesis of biomacromolecules such as peptides, oligonucelotides, and oligosaccharides, and today is also used for the synthesis of synthetic macromolecules and polymers. The key feature of this approach is the stepwise assembly of building blocks on solid support, enabling monodispersity and monomer sequence control. However, in order to achieve such control, a high excess of building blocks is required during the reaction. Herein, the recovery, purification, and reusability of building blocks used in SPS, including representative examples of tailor-made building blocks, Fmoc-protected amino acids, and functionalized carbohydrate ligands, are reported for the first time. Results demonstrate the general applicability with recovery in high yields and high purity. Furthermore, the described recovery process can be applied in both manual and automated synthesis using a standard peptide synthesizer. Overall, this process is envisioned to be applicable for a large variety of building blocks used in the SPS of different types of molecules, and to contribute to more resourceful SPS syntheses.