A theoretical study of pure and simple competition between two microbial species in configurations of two interconnected chemostat

It is known that two microbial populations competing purely and simply for a common substrate cannot coexist in a steady state in an environment which is spatially homogeneous. Hence they cannot coexist in a chemostat something which implies that a mixed culture of two pure and simple competitors cannot be maintained in a single ideal reactor in a steady state. The present study investigates theoretically pure and simple competition between two populations in two interconnected chemostats. Three reactor configurations are considered and analyzed. It is proved that two pure and simple competitors can coexist in a steady state in both reactors in cases where the conditions are such that they favor the growth of one species in one reactor and the growth of its competitor in the other vessel. It is then concluded that spatial inhomogeneities can lead to steady state coexistence of pure and simple competitors. The results of this study have been derived analytically and numerically. The dynamic behavior of the system at all possible steady states has been studied analytically. A number of conditions sufficient and/or necessary for the existence of each one of the possible steady states have been derived also analytically. The numerical studies have shown that one can always find a range in the operating parameters space where coexistence occurs, that the steady states are mutually exclusive and that no steady state exhibits multiplicity. The results are presented in series of two-dimensional operating diagrams and the effect of all parameters on the behavior of the system is studied and discussed in detail. It has been also proved that it is not necessary for coexistence to externally feed both vessels with nutrient medium and that there is a design configuration which makes the environment always homogeneous in which case coexistence is impossible

Integrated anaerobic-aerobic system for the biodegradation of highly chlorinated aromatic compounds

A two-step process was developed for the complete mineralization of hazardous chlorinated aromatic compounds. The system consisted of an anaerobic reactor, in which reductive dehalogenation took place, coupled with an aerobic reactor in which the complete mineralization of the products of the anaerobic dehalogenation occurred. A mixed anaerobic culture from a municipal sewage treatment plant was enriched and then immobilized on silica-based porous beads to treat 2,4,6-trichlorophenol (TCP), which is the model target compound in this work. In the anaerobic reactor, TCP was degraded to 2,4-dichlorophenol which was, in turn, reduced to 4-chlorophenol (4-CP). Stoichiometric amounts of 4-CP were recovered at the end of the anaerobic step. No other unknown compound was produced to any significant extent during the anaerobic process. As the anaerobic culture got acclimated to the TCP, the dehalogenation rate of TCP increased from 21.7 to 43.2 μM/day. The effluent from the anaerobic reactor was subsequently treated in a suspended growth aerobic reactor to remove the 4-CP. The anaerobic effluent had to be buffered with a phosphate solution to adjust its μH to about 7 and maintain aerobic activity. When the system was run in batch mode, 106.4 μM of TCP could be dechlorinated to 4-CP in three days by an acclimated anaerobic culture. 98 μM of the 4-CP produced were then mineralized in the aerobic reactor in less than three days. When the system was run in continuous mode, 120 μM of TCP were entirely and continuously dechlorinated to 4-CP in the anaerobic reactor, and then completely mineralized in the aerobic reactor. The average residence times (which were not optimized) in the anaerobic and aerobic reactors were respectively 105 and 98 hours, although there are indications that these were longer than necessary

Journal of Orthopaedic Surgery and Research Editorial

Journal of Orthopaedic Surgery and Research is an open access, online journal that aims to expeditiously publish clinical and basic research studies related to musculoskeletal issues in different cultural communities. It provides a platform for exchanges of new clinical and scientific information in the most precise and expeditious way to achieve dissemination of information and cross-fertilization of ideas. The open access nature of this journal allows articles to be universally and freely accessible via the Internet. This ensures a rapid and efficient communication of research findings. The journal welcomes all types of articles related to musculoskeletal issues. Its timely publication and high visibility are the two most important features that make this journal different from other traditional journals in the orthopaedic field

Clinical development of liposome-based drugs: formulation, characterization, and therapeutic efficacy

Research on liposome formulations has progressed from that on conventional vesicles to new generation liposomes, such as cationic liposomes, temperature sensitive liposomes, and virosomes, by modulating the formulation techniques and lipid composition. Many research papers focus on the correlation of blood circulation time and drug accumulation in target tissues with physicochemical properties of liposomal formulations, including particle size, membrane lamellarity, surface charge, permeability, encapsulation volume, shelf time, and release rate. This review is mainly to compare the therapeutic effect of current clinically approved liposome-based drugs with free drugs, and to also determine the clinical effect via liposomal variations in lipid composition. Furthermore, the major preclinical and clinical data related to the principal liposomal formulations are also summarized

The Regulation Requirement of Dengue Vaccines

Dengue fever (dengue), a mosquito-borne disease caused by dengue viruses (DENVs), represents severe public health problems in Southeast Asia, Latin America, Africa and other subtropical regions. Many regulatory issues arise along with the development of dengue vaccines. It is required to follow the regulatory pathway for the license application. Dengue vaccines can be approved without local clinical phase III data. The national regulatory authorities (NRAs) must have the information, training and ability to review and approve the application. A novel vaccine product Dengvaxia® for dengue has been approved in many countries. The approval is based on clinical trials that show the vaccine could reduce about 60% dengue, prevented 90% of severe cases and 80% of hospitalizations. Several other DNA, live-attenuated, purified inactivated, subunit, vectored and chimeric vaccine candidates are currently developing in clinical phases. Although there are still some challenges for the development and regulation of vaccine, the prospects of dengue vaccines are promising provided that we can overcome the difficulty

Biotechnologies Applied in Biomedical Vaccines

Vaccination, the administration of an antigenic material (vaccine), is considered to be the most effective method for disease prevention and control. A vaccine usually contains an agent that resembles a diseases‐causing pathogen and is often made from inactivated microbes, live attenuated microbes, its toxins, or part of surface antigens (subunit). However, the modern biotechnological tools and genomics have opened a new era to develop novel vaccines and many products are successfully marketing around the world. It is important to formulate and deliver these vaccines appropriately to maximize the potential advances in prevention, therapy, and vaccinology. New vaccines employing biotechnological innovations are helping us to change the way for illness prevention. The clinical application of vaccines will be diversified along with the development of biotechnologies. In modern society, the outbreak of many infectious diseases has decreased through vaccination, but the burden of noninfectious diseases is growing. The new biotechnologies may result in not only the appreciation of vaccines which are critical in inducing protection against an infectious disease but also the production of therapeutic vaccines which are effective for alldiseases including infectious and noninfectious diseases

Nanotechnologies Applied in Biomedical Vaccines

Vaccination, one of the most effective strategies to prevent infectious diseases, is the administration of antigenic materials to stimulate an individual’s immune system to develop adaptive immunity to a specific pathogen. Though it is so advantageous for diseases control and prevention, vaccines still have some limitations. Nanotechnology is an approach to prepare a novel biomedicine vaccine with the vaccine consumption and side effects significantly decreased. Regulation is the most important criterion for the development of nanovaccines. All marketing products have to meet the requirement of regulation. The fast-track designation potentially aids in the development and expedites the review of nanovaccines that show promises in an unmet medical need. Here, some successful nanovaccine products are introduced—Inflexal® V, Epaxal®, GardasilTM, and CervarixTM have been widely used for the clinical applications, which are delivered either in the form of virosomes or virus-like particles. Vaccines based on nanotechnology may overcome their original disadvantages and lead to the development of painless, safer, and more effective products

Influence of Y-doped induced defects on the optical and magnetic properties of ZnO nanorod arrays prepared by low-temperature hydrothermal process

One-dimensional pure zinc oxide (ZnO) and Y-doped ZnO nanorod arrays have been successfully fabricated on the silicon substrate for comparison by a simple hydrothermal process at the low temperature of 90°C. The Y-doped nanorods exhibit the same c-axis-oriented wurtzite hexagonal structure as pure ZnO nanorods. Based on the results of photoluminescence, an enhancement of defect-induced green-yellow visible emission is observed for the Y-doped ZnO nanorods. The decrease of E(2)(H) mode intensity and increase of E(1)(LO) mode intensity examined by the Raman spectrum also indicate the increase of defects for the Y-doped ZnO nanorods. As compared to pure ZnO nanorods, Y-doped ZnO nanorods show a remarked increase of saturation magnetization. The combination of visible photoluminescence and ferromagnetism measurement results indicates the increase of oxygen defects due to the Y doping which plays a crucial role in the optical and magnetic performances of the ZnO nanorods