Freeform Fabrication of Biological Scaffolds by Projection Photopolymerization

This article presents a micro-manufacturing method for direct, projection printing of 3- dimensional (3D) scaffolds for applications in the field of tissue engineering by using a digital micro-mirror-array device (DMD) in a layer-by-layer process. Multi-layered scaffolds are microfabricated using curable materials through an ultraviolet (UV) photopolymerization process. The pre-patterned UV light is projected onto the photocurable polymer solution by creating the “photomask” design with graphic software. Poly (ethylene glycol) diacrylate (PEGDA), is mixed with a small amount of dye (0.3 wt %) to enhance the fabrication resolution of the scaffold. The DMD fabrication system is equipped with a purging mechanism to prevent the accumulation of oligomer, which could interfere with the feature resolution of previously polymerized layers. The surfaces of the pre-designed, multi-layered scaffold are covalently conjugated with fibronectin for efficient cellular attachment. Our results show that murine marrow-derived progenitor cells successfully attached to fibronectin-modified scaffolds.Mechanical Engineerin

Microfabrication of spatially-patterned, polymer scaffolds for applications in stem cell and tissue engineering

textTissue engineering is a recently developed field that combines material science, cell biology, and engineering to create or improve functional tissues/organs. The field of tissue engineering has progressed from a fledgling science to an emerging technology, in large part due to parallel advances in the application of biomaterials and understanding stem cell behavior. Current studies have evaluated certain types of natural and synthetic biomaterials for feasibility of replicating the physio-chemical microenvironments of stem cells. Furthermore, technologies derived from micro-machining and solid free-form fabrication industries have utilized these biomaterials to create scaffolds that resemble tissue-like structures. Recent scaffold fabrication methods have attempted to overcome certain challenges in engineering tissues and organs. One of the fundamental limitations in current tissue engineering efforts has been the inability to develop multiple tissue types (i.e. bone, cartilage, muscles, ligaments) within a single scaffold structure in a predesigned manner. The differentiation of multiple cells within a three-dimensional (3D) scaffold using a single stem cell population has yet to be developed due to challenges in integrating various biochemical factors in a spatially-patterned method. This dissertation discusses scaffold micro-fabrication techniques that use layerby-layer, ultraviolet-based (UV) stereolithography systems. These approaches in microfabricating scaffolds provide an optimal, biomimetic environment for the pre-patterned differentiation of mesenchymal stem cells into skeletal-type tissues. We demonstrated both laser-based and digital micromirror device-based stereolithography systems for creating intricate scaffold architectures with multiple bio-factors encapsulated in predetermined regions. We showed that micro-stereolithography has the powerful capability of building 3D complex scaffolds with specific pore sizes and shapes in a layer-by-layer fashion using photo-crosslinkable monomers. These polymer-based scaffolds were functionalized with specific signaling proteins to create a biomimetic niche in which stem cells can respond, attach, and differentiate. The ultimate goal of this project is to integrate novel concepts of micro-manufacturing along with polymer-controlled release kinetics and stem cell biology to attain pre-designed architectures of tissue structures.Biomedical Engineerin

The efficacy and safety of nirsevimab for the prevention of RSV infection among infants: A systematic review and meta-analysis

BackgroundRespiratory syncytial virus (RSV) is a leading cause of morbidity and mortality among infants with a global incidence of 9.5% and a mortality rate of 2.2%. The management of RSV infection is mainly supportive and, aside from emerging monoclonal antibodies, there has been no benefit of most preventive measures. Recent evidence suggests the potential of nirsevimab in preventing RSV infection.ObjectiveThis study aims to determine the efficacy and safety of nirsevimab in preventing RSV infection among infants using a review of relevant clinical trials.MethodsWe performed a random-effects meta-analysis among infants comparing nirsevimab injection vs. placebo. MEDLINE, CENTRAL, Scopus, and ClinicalTrials.gov were searched for relevant trials from inception to June 2022. The selected studies were assessed for risk of bias using the Revised Cochrane Risk-of-Bias (RoB2) tool and for quality of evidence using the Grades of Recommendation, Assessment, Development and Evaluation (GRADE) approach.ResultsTwo studies were included. Data analysis showed that among infants, nirsevimab given before the RSV season significantly reduced the risk of medically attended RSV-related infection (RR: 0.26; 95% CI: 0.18–0.38) and the risk of hospitalization due to RSV infection (RR: 0.24; 95% CI: 0.13–0.47). There was no difference in terms of adverse events leading to death (RR: 0.78, 95% CI: 0.20–2.98) and adverse events of special interest (RR: 0.92, 95% CI: 0.25–3.38).ConclusionsThe use of nirsevimab to prevent RSV infections and hospitalization shows its promising potential, but studies on its cost-effectiveness are lacking. We recommend that further studies be done to look into the applicability and cost-effectiveness of nirsevimab

The safety and efficacy of direct oral anticoagulants among chronic kidney disease patients on dialysis with non-valvular atrial fibrillation: a meta-analysis

BackgroundIndividuals with chronic kidney disease (CKD) on dialysis are at an increased risk of stroke and embolic events especially in the presence of atrial fibrillation (AF). Vitamin K antagonists (VKA), including warfarin, have been used for decades for anticoagulation among CKD patients on dialysis with AF but recent evidence has shown increased bleeding. Direct oral anticoagulants (DOAC) have been emerging as an alternative to VKA which, based on several observational cohort studies, are at least as efficacious and safe as VKA. This meta-analysis looked into the safety and efficacy of DOACs compared to VKA among CKD patients on dialysis with non-valvular AF.MethodologyThis study used a random-effects meta-analysis using RevMan 5.4. PubMed, EMBASE, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and ClinicalTrials.gov were searched from their dates of inception to June 2023. The risk of bias was assessed using Cochrane RoB2 and the certainty of evidence was assessed using GRADE.ResultsThis meta-analysis showed that DOACs when compared to VKA have no significant difference in terms of risk for major bleeding (RR = 0.81, 95% CI 0.46–1.43), ischemic stroke (RR = 0.5, 95% CI 0.19–1.35), and cardiovascular death (RR = 1.34, 95% CI 0.69–2.60).DiscussionThis meta-analysis adds to the growing body of evidence supporting that the use of DOACs has similar efficacy and safety outcomes in CKD patients on dialysis with non-valvular AF patients compared to VKA. The findings need to be replicated in larger and more adequately powered clinical trials in order to ascertain its level of evidence

Insecticide contamination in organic agriculture: Evidence from a long-term farming systems comparison trial

Synthetic pesticides applied in conventional agriculture to control pests tend to compromise ecosystem services, and their residues may contaminate organic agriculture. To understand the significance of this contamination, also in small-scale farming systems in sub-Saharan Africa, quantitative data is required. Therefore, we compared synthetic insecticide and botanical/biopesticide residues in conventional and organic agricultural production systems after nine years of continuous cultivation of a maize-based crop rotation system at two sites in Kenya. Our results show high detectable concentrations of synthetic insecticide residues (imidacloprid, acetamiprid, chlorpyrifos, and chlorantraniliprole) in conventional plant produce and soil. Furthermore, the organophosphate chlorpyrifos was detected at concentrations above European Union Maximum Residue Limits (MRL) for plant produce, indicating potential risks for human health. Additionally, we detected imidacloprid, acetamiprid, chlorpyrifos, and chlorantraniliprole concentrations in the soil, indicating potential environmental harm. No residues of biopesticide/botanicals were detected in any of the production systems. However, we detected imidacloprid and chlorantraniliprole in organic plots. The findings indicate that the MRLs can be crossed even if synthetic insecticides are applied according to or below the recommended rates on the conventional plots. Thus, synthetic insecticides potentially risk human health and the environment, while botanicals and bio-pesticides represent a safe alternative

Control of self-assembly in micro- and nano-scale systems

Control of self-assembling systems at the micro- and nano-scale provides new opportunities for the engineering of novel materials in a bottom-up fashion. These systems have several challenges associated with control including high-dimensional and stochastic nonlinear dynamics, limited sensors for real-time measurements, limited actuation for control, and kinetic trapping of the system in undesirable configurations. Three main strategies for addressing these challenges are described, which include particle design (active self-assembly), open-loop control, and closed-loop (feedback) control. The strategies are illustrated using a variety of examples such as the design of patchy and Janus particles, the toggling of magnetic fields to induce the crystallization of paramagnetic colloids, and high-throughput crystallization of organic compounds in nanoliter droplets. An outlook of the future research directions and the necessary technological advancements for control of micro- and nano-scale self-assembly is provided

Passive neutron techniques for the nondestructive assay of nuclear material

Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to [email protected], referencing the URI of the item.Includes bibliographical references (leaves 114-115).Issued also on microfiche from Lange Micrographics.Three drums containing potentially contaminated lead bricks were assayed with the Segmented Gamma Scan Neutron Assay System (SGSNAS) at Pacific Northwest National Laboratory's (PNNL) Nondestructive Assay Center. The assay system reported that the drums contained transuranic material. These results were based solely on the number of time-correlated neutron events. The gamma spectra for all three drums were inspected and no gamma ray lines corresponding to transuranic nuclides were found. Further investigations found that the lead in one of the drums had not been part of a contaminated area cleanup and should not be radiologically contaminated. This thesis examines the nuclear reactions that produce neutrons, the principles of neutron detectors including the circuitry required for coincidence counting, and how neutrons interact with matter. The premise is that time-correlated neutrons are produced from high-energy muon interactions with the lead nucleus, a spallation reaction. Muons are a component of the "air shower cascade" as cosmic rays traverse through the earth's atmosphere; therefore, an extensive study of cosmic rays has been undertaken. Verification that time-correlated neutrons are emitted from lead was performed using three completely separate systems

Land-use and water quality : a GIS evaluation of the problems, interaction, and initiatives, in the Pampanga River Basin, Central Luzon, Philippines

Agricultural activities in the Pampanga river Basin (PRB) are threatened by the increasing population and development thrusts of the Philippine government. This study was conducted to develop a framework by which problems, initiatives, and interactions among land-use changes, water quality and governance issues may be assessed employing Geographic Information Systems (GIS) techniques. Stream stations were sampled for nitrate, phosphate, temperature, dissolved oxygen, total dissolved solids, chemical oxygen demand and pH. Land-use changes were analyzed through GIS, while land-use planning was investigated through workshop participation and review of government plans. Agricultural land increased 0.6% annually from 1953 to 1980 due to conversion of grasslands, wetlands and forests to agriculture, and declined 0.5 % annually from 1980 to 1993 due to expansion of settlements. A provincial land-use plan would accelerate conversion rather than protect agricultural lands. Water quality in the Pampanga river and its tributaries is deteriorating in both the spatial and temporal dimensions. The eruption of Mt. Pinatubo was responsible for increased levels of ortho-phosphate, TDS, and temperature in streams, but the low DO during the start of the rainy season and the high nitrate-N concentrations are indicators of human influence on water quality. Streams with catchments having the same predominant land-use classification exhibited similar trends in water quality. Animal species in different area classifications also affected water quality at different flow periods. Buffer analysis on 500 metre zone along the streams gave best values. The effect of runoff is altered by the type of land-use, specifically the presence of rice fields. The management of nitrate-N based on a nitrogen budget revealed that animal manure and inorganic fertilizer are major sources of nitrogen in the basin. The hotspot areas are catchments with large settlement areas, and/or with a very high animal population. Alternative scenarios revealed no significant changes in water quality even with a three-fold increase in animal production or 10 % agricultural land conversion. A cautious optimism is anticipated in involving the barangay captains in the overall management of the environment, in particular, the control of stream pollution that endangers the fishing industry.Science, Faculty ofResources, Environment and Sustainability (IRES), Institute forGraduat

Fundamentals of nursing law, jurisprudence and ethics

Fundamentals of nursing law, jurisprudence and ethics is a compilation of law and jurisprudence on nursing law, code of ethics for registered nurses and other legislations relating to nursing.xxv, 817 hlm.; 23 c