Axially Compressed Cylindrical Shell Containing Axisymmetric Random Imperfections:

ABSTRACT This paper presents the comparison of reliability technique that employ Fourier series representations of random asymmetric imperfections in axially compressed cylindrical shell with evaluations prescribed by ASME Boiler and Pressure Vessel Code, Section VIII, Division 1 and 2. The ultimate goal of the reliability type technique is to predict the buckling load associated with the axially compressed cylindrical shell. Initial geometric imperfections have significant effect on the load carrying capacity of asymmetrical cylindrical shells. Fourier decomposition is used to interpret imperfections as structural features can be easily related to the different components of imperfections. The initial functional description of the imperfections consists of an axisymmetric portion and a deviant portion appearing as a double Fourier series. The representation of initial geometrical imperfections in the cylindrical shell requires the determination of appropriate Fourier coefficients. The mean vector and the variance-covariance matrix of Fourier coefficients are calculated from the simulated shell profiles. Multi-mode analysis are expanded to evaluate a large number of potential buckling modes for both predefined geometries and associated asymmetric imperfections as a function of position within a given cylindrical shell. Large number of shells thus created can be used to calculate buckling stress for each shell. The probability of the ultimate buckling stress exceeding a predefined threshold stress can also be calculated. Keywords: Buckling; Asymmetric Imperfections; Fourier Series; Cylindrical Shell. NOMENCLATURE λ = Non-dimensional buckling load μ = Poisson"s ratio ξ i = Magnitude of imperfection as a fractional value of shell thickness θ = Non-dimensional number associated with the circumferential coordinates ξ = Non-dimensional number associated with the axial coordinates σ A (ξ) = Elements of Variance-covariance matrix C w0 (ξ 1 ,θ 1 ,ξ 2 ,θ 2 ) = Auto-covariance function k = Number of half waves in axial direction l = Number of full waves in circumferential direction P cl = Classical buckling load of a perfect shell P cr = Critical buckling load of a shell with imperfections Proceedings of IMECE2008 2008 ASME International Mechanical Engineering Congress and Exposition October 31-November 6, 2008, Boston, Massachusetts, USA Copyright©2008 by ASME 2 R = Radius of the shell E = Young"s Modulus L = Length of the shell t = Wall thickness of the shell D 0 = Outside diameter of the shell W n (ξ,θ) = Initial imperfection function IMECE2008-6879

Novel PEG-graft-PLA nanoparticles with the potential for encapsulation and controlled release of hydrophobic and hydrophilic medications in aqueous medium

This study concerns the encapsulation and controlled release of both hydrophobic and hydrophilic medications with one polymer, which are delivered together as a combined therapy to treat diseased tissue. To test our hypothesis that the novel PEG-graft-PLA (PEG, polyethylene glycol; PLA, polylactic acid) can deliver both the hydrophobic and hydrophilic medications on account of its amphiphility, charge, and graft structure, PEG-graft-PLA (molecular weight of PEG = 1900) with very low critical micelle concentration was synthesized. One hydrophilic (insulin) and one hydrophobic (naproxen) model medication were loaded in separately during its self-assembly in aqueous solution. The resulting nanoparticles (NPs) were narrowly distributed and spherical, with average particle size around 200 nm, zeta potential >−10 mV, and encapsulation efficiency >50%. The NPs realized controlled release of insulin and naproxen for over 24 and 160 hours, respectively. Specifically, the bioactivity of the insulin released from the NPs was maintained. Owing to encapsulation, both for hydrophobic and hydrophilic medicines, and NPs obtained with similar size and zeta potential, as well as maintenance of bioactivity of loaded protein, we expect the applications of PEG-graft-PLA NPs in combination therapy

Novel multi-biotin grafted poly(lactic acid) and its self-assembling nanoparticles capable of binding to streptavidin

Targeted drug delivery requires novel biodegradable, specific binding systems with longer circulation time. The aim of this study was to prepare biotinylated poly(lactic acid) (PLA) nanoparticles (NPs) which can meet regular requirements as well conjugate more biotins in the polymer to provide better binding with streptavidin. A biotin-graft-PLA was synthesized based on previously published biodegradable poly(ethylene glycol) (PEG)-graft-PLA, with one polymer molecule containing three PEG molecules. Newly synthesized biotin-graft-PLA had three biotins per polymer molecule, higher than the previous biotinylated PLA (≤1 biotin per polymer molecule). A PEG with a much lower molecular weight (MW ~1900) than the previous biotinylated PLA (PEG MW ≥ 3800), and thus more biocompatible, was used which supplied good nonspecific protein-resistant property compatible to PEG-graft-PLA, suggesting its possible longer stay in the bloodstream. Biotin-graft-PLA specifically bound to streptavidin and self-assembled into NPs, during which naproxen, a model small molecule (MW 230 Da) and hydrophobic drug, was encapsulated (encapsulation efficiency 51.88%). The naproxen-loaded NPs with particle size and zeta potential of 175 nm and −27.35 mV realized controlled release within 170 hours, comparable to previous studies. The biotin-graft-PLA NPs adhered approximately two-fold more on streptavidin film and on biotin film via a streptavidin arm both in static and dynamic conditions compared with PEG-graft-PLA NPs, the proven nonspecific protein-resistant NPs. The specific binding of biotin-graft-PLA NPs with streptavidin and with biotin using streptavidin arm, as well as its entrapment and controlled release for naproxen, suggest potential applications in targeted drug delivery

An information-theoretic analysis of genetics, gender and age in cancer patients

Peer reviewe

Formulation, stabilisation and encapsulation of bacteriophage for phage therapy

Against a backdrop of global antibiotic resistance and increasing awareness of the importance of the human microbiota, there has been resurgent interest in the potential use of bacteriophages for therapeutic purposes, known as phage therapy. A number of phage therapy phase I and II clinical trials have concluded, and shown phages don’t present significant adverse safety concerns. These clinical trials used simple phage suspensions without any formulation and phage stability was of secondary concern. Phages have a limited stability in solution, and undergo a significant drop in phage titre during processing and storage which is unacceptable if phages are to become regulated pharmaceuticals, where stable dosage and well defined pharmacokinetics and pharmacodynamics are de rigueur. Animal studies have shown that the efficacy of phage therapy outcomes depend on the phage concentration (i.e. the dose) delivered at the site of infection, and their ability to target and kill bacteria, arresting bacterial growth and clearing the infection. In addition, in vitro and animal studies have shown the importance of using phage cocktails rather than single phage preparations to achieve better therapy outcomes. The in vivo reduction of phage concentration due to interactions with host antibodies or other clearance mechanisms may necessitate repeated dosing of phages, or sustained release approaches. Modelling of phage-bacterium population dynamics reinforces these points. Surprisingly little attention has been devoted to the effect of formulation on phage therapy outcomes, given the need for phage cocktails, where each phage within a cocktail may require significantly different formulation to retain a high enough infective dose. This review firstly looks at the clinical needs and challenges (informed through a review of key animal studies evaluating phage therapy) associated with treatment of acute and chronic infections and the drivers for phage encapsulation. An important driver for formulation and encapsulation is shelf life and storage of phage to ensure reproducible dosages. Other drivers include formulation of phage for encapsulation in micro- and nanoparticles for effective delivery, encapsulation in stimuli responsive systems for triggered controlled or sustained release at the targeted site of infection. Encapsulation of phage (e.g. in liposomes) may also be used to increase the circulation time of phage for treating systemic infections, for prophylactic treatment or to treat intracellular infections. We then proceed to document approaches used in the published literature on the formulation and stabilisation of phage for storage and encapsulation of bacteriophage in micro- and nanostructured materials using freeze drying (lyophilization), spray drying, in emulsions e.g. ointments, polymeric microparticles, nanoparticles and liposomes. As phage therapy moves forward towards Phase III clinical trials, the review concludes by looking at promising new approaches for micro- and nanoencapsulation of phages and how these may address gaps in the field

PVP2009-77854 FOURIER SERIES ANALYSIS OF A CYLINDRICAL PRESSURE VESSEL SUBJECTED TO EXTERNAL PRESSURE

ABSTRACT This paper presents the comparison of a reliability technique that employs a Fourier series representation of random asymmetric imperfections in a cylindrical pressure vessel subjected to external pressure. Comparison with evaluations prescribed by the ASME Boiler and Pressure Vessel Code, Section VIII, Division 2 Rules for the same shell geometries are also conducted. The ultimate goal of the reliability type technique is to predict the critical buckling load associated with the chosen cylindrical pressure vessel. Initial geometric imperfections are shown to have a significant effect on the load carrying capacity of the example cylindrical pressure vessel. Fourier decomposition is employed to interpret imperfections as structural features that can be easily related to various other types of defined imperfections. The initial functional description of the imperfections consists of an axisymmetric portion and a deviant portion, which are availed in the form of a double Fourier series. Fifty simulated shells generated by the Monte Carlo technique are employed in the final prediction of the critical buckling load. The representation of initial geometrical imperfections in the cylindrical pressure vessel requires the determination of appropriate Fourier coefficients. Multi-mode analyses are expanded to evaluate a large number of potential buckling modes for both predefined geometries and associated asymmetric imperfections as a function of position within a given cylindrical shell. The probability of the ultimate buckling stress that may exceed a predefined threshold stress is also calculated. The method and results described herein are in stark contrast to the "knockdown factor" approach as applied to compressive stress evaluations currently utilized in industry. Recommendations for further study of imperfect cylindrical pressure vessels are also outlined in an effort to improve on the current design rules regarding column buckling of large diameter pressure vessels designed in accordance with ASME Boiler and Pressure Vessel Code, Section VIII, Division 2 and ASME STS-1

Not Available

Not AvailableIn a pilot study, as a prelude for characterization of the entire Trigonella germplasm conserved in the National Gene Bank, National Bureau of Plant Genetic Resources, New Delhi, genetic relatedness among a selection of 49 accessions of fenugreek (Trigonella-foenum-graecum L.) was assessed using 19 morphometric and 186 inter-simple sequence repeat (ISSR) markers. An accession of T. corniculata L. was also assessed as an out-group. The accessions were collected from different eco-geographical sites located in the states of Andhra Pradesh, Himachal Pradesh, Jammu and Kashmir, Madhya Pradesh, Uttar Pradesh, Uttarakhand, Rajasthan, Gujarat, Manipur and Bihar; and one of the accessions was imported from Eritrea. Data for 12 qualitative and seven quantitative morphometric descriptors were recorded. Significant differences within the accessions were found for all the quantitative descriptors except primary branches and seeds/pod. Shannon-Wiener Diversity Index revealed substantial diversity for all the quantitative descriptors. The morphometric data differentiated the fenugreek accessions into two clusters (at similar to 65% similarity). A total of 100 ISSR primers were used for initial screening, out of which only 21 primers were found polymorphic. ISSR analysis was performed with selected 21 primers to generate 186 amplicons, of which 92.4% were polymorphic. Cluster analysis put 47 accessions in a single group at similar to 65% similarity. Though there was no agreement between the groupings based on morphometric and ISSR markers (Mantel statistic 0.096), specific cases of geographic groupings were supported by both the markers. Phylogenetic positioning of the accessions with no passport information was found to be possible. The ISSR markers complemented the morphometric data in understanding the genetic divergence among the fenugreek accessions.NBPGR, New Delh

Sustainable Biofuel Production from Agricultural Residues an Eco-Friendly Approach: A Review

Biofuel production from agricultural residues presents an innovative solution to the global energy challenge. This study delves into the potential of using such residues as a renewable feedstock, addressing the pressing need to transition from conventional fossil fuels. By evaluating various agricultural residues' types and characteristics, a comprehensive assessment of their worldwide availability and potential yield was undertaken. Emphasizing sustainable and eco-friendly approaches, the research underscores closed-loop systems, efficient utilization of co-products, and the imperative of a holistic life cycle assessment (LCA) for biofuel production. The LCA revealed a significant reduction in greenhouse gas emissions, emphasizing water conservation and waste reduction during the process. Despite the evident potential, there are identifiable challenges, primarily technological research gaps, economic constraints, infrastructural limitations, and regulatory hurdles. Yet, the undeniable benefits include a notable reduction in carbon footprint, effective resource management, and a bolstered economy, especially for agrarian communities. Policies promoting sustainable farming practices, incentivizing research and development, and fostering collaborations are recommended. Such a framework can enhance biofuel infrastructure, necessitate regular monitoring, and optimize the biofuel production process. Conclusively, while challenges persist, with cohesive policy recommendations and technological innovations, agricultural residues can pivot as the linchpin in a sustainable energy future