Synthetic biology strives to reliably control cellular behavior, typically in the form of user-designed interactions of biological components to produce a predetermined output. Engineered circuit ...components are frequently derived from natural sources and are therefore often hampered by inadvertent interactions with host machinery, most notably within the host central dogma. Reliable and predictable gene circuits require the targeted reduction or elimination of these undesirable interactions to mitigate negative consequences on host fitness and develop context-independent bioactivities. Here, we review recent advances in biological orthogonalization, namely the insulation of researcher-dictated bioactivities from host processes, with a focus on systematic developments that may culminate in the creation of an orthogonal central dogma and novel cellular functions.
Development of fully synthetic nucleobase pairs that faithfully interact in living cells, and their applications in creating semisynthetic organisms with expanded and orthogonal information-carrying capacity.Harnessing naturally occurring and mutually orthogonal DNA replication systems to enable replication of target genes. Highly error-prone variations on these systems enable robust directed evolution of biomolecules.Engineering and directed evolution of mutually orthogonal transcription factors that operate with high dynamic range, low background, and respond to a wide repertoire of stimuli in vivo.Recent developments in in vivo orthogonal protein translation including: orthogonal RBS–orthogonal anti-RBS pairs, covalently linked rRNA subunits to discover novel enzymatic capabilities, improved incorporation of non-canonical amino acids and decoding quadruplet codons.
Knowledge of root and root canal morphology is a prerequisite for effective nonsurgical and surgical endodontic treatments. The external and internal morphological features of roots are variable and ...complex, and several classifications have been proposed to define the various types of canal configurations that occur commonly. More recently, improvements in nondestructive digital image systems, such as cone‐beam and micro‐computed tomography, as well as the use of magnification in clinical practice, have increased the number of reports on complex root canal anatomy. Importantly, using these newer techniques, it has become apparent that it is not possible to classify many root canal configurations using the existing systems. The purpose of this article is to introduce a new classification system that can be adapted to categorize root and root canal configurations in an accurate, simple and reliable manner that can be used in research, clinical practice and training.
Abstract Research involving animal models of drug addiction can be viewed as a sort of reverse psychiatry. Contrary to clinicians who seek to treat addicted people to become and remain abstinent, ...researchers seek to make drug-naïve animals addicted to a drug with known addictive properties in humans. The goals of this research are to better understand the neuroscience of drug addiction and, ultimately, to translate this knowledge into effective treatments for people with addiction. The present review will not cover the vast literature that has accumulated over the past 50 years on animal models of drug addiction. It is instead more modestly devoted to recent research spanning the past decade on drug self-administration–based models of addiction in the rat (the animal species most frequently used in the field), with a special focus on current efforts to model compulsive cocaine use as opposed to nonaddictive use. Surprisingly, it turns out that modeling compulsive cocaine use in rats is possible but more difficult than previously thought. In fact, it appears that resilience to cocaine addiction is the norm in rats. As in human cocaine users, only few individual rats would be vulnerable. This conclusion has several important implications for future research on the neuroscience of cocaine addiction and on preclinical medication development. This article is part of a Special Issue entitled: Neuroscience Disease Models.
Pain is a global, complex health problem that includes physical, emotional and social components. The pain management process has many goals, including patient satisfaction, reducing clinical ...complications, and lowering costs. The physician describes the pain medications in terms of the proven cause and classification of the severity of the pain. The combination of celecoxib and tramadol was recently approved by the FDA in October 2021 for the treatment of acute pain in adults.
This paper presents the first published quantitative analytical methods for celecoxib and tramadol.
The UV absorption spectra of celecoxib and tramadol showed strong overlap. Mathematical simultaneous equation and ratio difference methods were developed to resolve the spectral overlap and quantify the drugs in the combination mixture. In the simultaneous equation method, the absorbance and absorptivity values at 252 and 217 nm were used to construct two mathematical equations that were used for the simultaneous mathematical quantification of the above drugs. The mathematical manipulation of the ratio difference based on the calculation of the differences in the amplitude values between 250 and 280 nm enabled the quantitative analysis of celecoxib, and the differences in the amplitude values between 221 and 272 nm enabled the quantitative analysis of tramadol.
The proposed methods were successfully applied to the selective quantitative analysis of celecoxib and tramadol in the synthetic mixtures and in the pharmaceutical tablets without interference of the tablet additives.
The first established simple and validated UV spectrophotometric methods were described for concurrent quantification of the celecoxib and tramadol in their recently approved pharmaceutical formulation.
The use of cellulosic polymers as efficient reducing, coating agents, and stabilizers in the formulation of silver nanoparticles (AgNPs) with antioxidant and antibacterial activity was investigated. ...AgNPs were synthesized using different cellulosic polymers, polyethylene glycol, and without polymers using tri-sodium citrate, for comparison. The yield, morphology, size, charge, in vitro release of silver ion, and physical stability of the resulting AgNPs were evaluated. Their antioxidant activity was measured as a scavenging percentage compared with ascorbic acid, while their antibacterial activity was evaluated against different strains of bacteria. The amount of AgNPs inside bacterial cells was quantified using an ICP-OES spectrometer, and morphological examination of the bacteria was performed after AgNPs internalization. Cellulosic polymers generated physically stable AgNPs without any aggregation, which remained physically stable for 3 months at 25.0 ± 0.5 and 4.0 ± 0.5 °C. AgNPs formulated using ethylcellulose (EC) and hydroxypropyl methylcellulose (HPMC) had significant (p ≤ 0.05; ANOVA/Tukey) antibacterial activities and lower values of MIC compared to methylcellulose (MC), PEG, and AgNPs without a polymeric stabilizer. Significantly (p ≤ 0.05; ANOVA/Tukey) more AgNPs-EC and AgNPs-HPMC were internalized in Escherichia coli cells compared to other formulations. Thus, cellulosic polymers show promise as polymers for the formulation of AgNPs with antioxidant and antibacterial activities.
In this study, electrospun cellulose acetate - poly(ethylene oxide) nanofibrous membrane was found to be unique in immobilizing bacterial cells. Here, removal of methylene blue in aqueous media was ...achieved by using isolated species of bacteria (Bacillus paramycoides) from industrial wastewater and immobilized on cellulose acetate- poly(ethylene oxide) nanofibers using DMSO as a solvent. The decolorization time was varied from 0 to 72 h, different dye concentrations from 20 to 200 mg/L and bacterial cells count was investigated to achieve the maximum MB removal by bacteria-immobilized CA/PEO nanofibrous membrane. The effective dye decolorization was achieved within 48 h and MB removal % was around 93%. Furthermore, reusability of the bacteria-immobilized CA/PEO nanofibrous membrane was tested. It was found that after the 4
usage, 44% of the dye decolorization capacity still could be achieved. These results are promising and suggest that bacteria-immobilized CA/PEO nanofibrous membrane could be economically feasible and eco-friendly when used in MB removal from industrial wastewater. Combination of both adsorption and biodegradation methods was found to be effective in MB removal from aqueous media.
4D electron microscopy Zewail, Ahmed H; Thomas, J. M. (John Meurig)
2010, 2010., 2009, 2009-12-24
eBook, Book
The modern electron microscope, as a result of recent revolutionary developments and many evolutionary ones, now yields a wealth of quantitative knowledge pertaining to structure, dynamics, and ...function barely matched by any other single scientific instrument. It is also poised to contribute much new spatially-resolved and time-resolved insights of central importance in the exploration of most aspects of condensed matter, ranging from the physical to the biological sciences. Whereas in all conventional EM methods, imaging, diffraction, and chemical analyses have been conducted in a static — time-integrated — manner, now it has become possible to unite the time domain with the spatial one, thereby creating four-dimensional (4D) electron microscopy. This advance is based on the fundamental concept of timed, coherent single-electron packets, or electron pulses, which are liberated with femtosecond durations. Structural phase transitions, mechanical deformations, and the embryonic stages of melting and crystallization are examples of phenomena that can now be imaged in unprecedented structural detail with high spatial resolution, and ten orders of magnitude as fast as hitherto.
Many transmitarray antennas are designed with multilayer frequency-selective surface (M-FSS) type elements. The goal of this paper is to reveal the transmission phase limit of M-FSS for transmitarray ...antenna designs. An analytical study of the transmission coefficient of multiple conductor layers separated by dielectric materials has been carried out, and the maximum transmission phase range has been determined according to the number of layers, substrate permittivity, and separation between conductor layers. It is revealed that the -1-dB transmission phase limits are 54°, 170°, 308°, and full 360 ° for single-, double-, triple-, and quad-layer FSS consisting of identical layers, respectively. Furthermore, it is shown that if -3-dB criteria is used, a triple-layer FSS is sufficient to achieve the full 360 ° phase range. The effectiveness of the analytical study has been validated through numerical simulations of several representative FSS examples.
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