A Study of the Synthesis of Cellulose by the Bacteria \u3cem\u3eKomagataeibacter xylinus\u3c/em\u3e (\u3cem\u3eK. xylinus\u3c/em\u3e) when Under the Action of an Electric Field in a Microfluidic Reactor

Dielectrophoresis (DEP) is an established technique used as a label-free method to manipulate microorganisms by exploiting the interaction of targeted microorganisms with a non-uniform electric field. The strength and direction of the DEP force on a targeted cell, specifically Komagataeibacter xylinus (K. xylinus), is dependent on the frequency of the applied electric field as well as the dielectric properties of the bacterial cell and suspending media. K. xylinus is a microorganism that can synthesize a fibrous, web-shaped organic material called bacterial cellulose (BC), which contains desirable properties such as high mechanical strength and increased water holding capabilities. By combining DEP techniques with this BC synthesizing microorganism, this creates the potential for controlled and enhanced growth allowing BC to be tailored to specific properties at specific locations. However, literature has reported limited information regarding the use of DEP techniques to study how electric fields affect BC synthesis in a microfluidic reactor. In this study, a titanium-based semicircular microelectrode chip was used to study how electrostimulation can potentially manipulate and influence the synthesis of BC at unique regions of interest where the electric field is greatest. This study features experiments running over fourteen days with an AC induced electric field at polarization voltages of 1 Vpp, 2 Vpp, and 5 Vpp at a frequency of 750 kHz. Results suggest that BC synthesis is possible and can be manipulated over an extended period as the polarization voltage increased where the electric field is greatest

Activity Of Soil Enzymes In Constructed Wetlands Treated With Swine Wastewater

The objectives of this research were to investigate the activity of soil enzymes at different depths of CW treated with swine wastewater and to assess the relationship between the enzyme activity and nutrient concentration. One continuous marsh (CM) and one marsh-pond-marsh (MPM) wetland cells were studied, which were in operation for the last ten years treating swine wastewater

Decision Models in Supply Chain Management: A Social Responsibility Perspective

Recent events in emerging countries concerning supplier unethical practices and the resulting fatalities have stressed the need for social responsibility in supply chains. Rising consumer awareness regarding such events and their negative impact pose a challenge in supply management decisions for firms. This research integrates the risk of supplier irresponsibility and the impact of such events from the consumer perspective in developing supply management decision models for maximizing economic performance of firms. Two important issues in supply management: supplier selection and supplier development are addressed through stylized modeling approach.First, a supplier selection decision model is analyzed that will aid a firm to select between an ethical and unethical (risky) supplier considering the supplier learning for long-term contracts. Next, the decision model is modified to study supplier development decision considering penalty costs to select between three development decisions: direct/binding, non-binding, and third-party/intermediaries.Our results suggest that firms prefer long-term type of strategies in both supplier selection and development under high risk or impact or both. Contingent policies are only optimal for supplier selection decisions, while firms may use intermediate sourcing/development when the penalty costs are high and the cost of sourcing is low. However, it is also economically optimal for firms to choose unethical supplier or to not invest in supplier development when the risk and the impact are extremely low. This research contributes to the literature in operations and supply chain management by addressing social responsibility including the consumer perspective addressing the research gap in the field of operations and supply chain managemen

Anaerobic Fermentation of Hemicellulose Present in Green Liquor and Hot Water Extracts to Carboxylic Acids

Wood is composed of cellulose, hemicellulose and lignin. In the paper industry the cellulose fraction is the major resource used in paper production, whereas the hemicellulose and the lignin are usually burned for heat recovery. Recently, wood-derived hemicellulose extracts have received much attention for the production of valuable bioproduct fuels and chemicals. Mixed-culture microbial ecosystems are capable of converting biomass materials, such as wood extracts, into mixtures of carboxylic acids (C1-C7), which can in turn be purified and sold as products, or converted into other organic chemicals through chemical means. The relative concentrations of the acids produced in the fermentations vary depending upon the type of extracts used and also on the microbial communities employed, such as those growing at mesophilic or thermophilic temperatures or different buffered pH levels . In this study, we were looking for the maximum production of carboxylic acids at varying temperatures using mesophilic and the thermophilic microbes growing on green liquor and hot water extracts. Steps had to be taken to restrict the growth of methanogenic cultures, thereby inhibiting the production of methane and enabling higher carboxylic acid accumulation. The inhibition of methane was done by adding iodoform at low concentrations or using ammonium bicarbonate as a buffer. The buffering agents calcium carbonate and ammonium bicarbonate were tested as alternate means of maintaining neutral pH during acidogenic growth on pure sugars. Results from the pure sugar fermentations led to applying ammonium bicarbonate as the buffer of choice for wood extracts fermentations. During fermentations, samples were collected at specific time intervals and the pH, off-gas volume, off-gas composition and total sugar and carboxylic acid contents were measured Analytical methods used included GC for determining gas composition and GC and HPLC for determining acid and sugar concentrations.. Results indicated that mixed microbial cultures were capable of converting glucose and xylose sugars and hydrolyzing oligomeric hemicellulose without addition of supplemental enzymes. Conversion yields of organic acids to carbohydrate ranged from 50 to 80%, with lactic acid dominating in lower pH fermentations and acetic acid dominating in fermentations at closer to neutral pH. Methane production in all cases was detected at very low levels compared to CO2 production rates. With the benefits of autohydrolysis, high product yields and low operating costs due to the non-aseptic fermentation, conversion of aqueous wood extracts to carboxylic acids may be an economically attractive method of adding value to these extracts

Decision Models in Supply Chain Management: A Social Responsibility Perspective

Recent events in emerging countries concerning supplier unethical practices and the resulting fatalities have stressed the need for social responsibility in supply chains. Rising consumer awareness regarding such events and their negative impact pose a challenge in supply management decisions for firms. This research integrates the risk of supplier irresponsibility and the impact of such events from the consumer perspective in developing supply management decision models for maximizing economic performance of firms. Two important issues in supply management: supplier selection and supplier development are addressed through stylized modeling approach.First, a supplier selection decision model is analyzed that will aid a firm to select between an ethical and unethical (risky) supplier considering the supplier learning for long-term contracts. Next, the decision model is modified to study supplier development decision considering penalty costs to select between three development decisions: direct/binding, non-binding, and third-party/intermediaries.Our results suggest that firms prefer long-term type of strategies in both supplier selection and development under high risk or impact or both. Contingent policies are only optimal for supplier selection decisions, while firms may use intermediate sourcing/development when the penalty costs are high and the cost of sourcing is low. However, it is also economically optimal for firms to choose unethical supplier or to not invest in supplier development when the risk and the impact are extremely low. This research contributes to the literature in operations and supply chain management by addressing social responsibility including the consumer perspective addressing the research gap in the field of operations and supply chain managemen

Data collection and transmission for leisure time boats : based on Arduino WSNs and LTE

There has been an astonishing research development in the field of wireless sensor networks (WSNs) in the last decade. A large number of low power capacity devices have been implemented in different vehicles, where sensor nodes act as a team to monitor the environment and forecast the potential defects. In this thesis, we aim to design a data collection system using a WSN on a leisure boat in order to monitor and maintain the boat after sale. The designed system aims to collect data from different sensors on board using WSNs and transmits the collected data to a remote server through cellular network. For the WSNs part, we select a low-power driven Adruino Lilypad as a controller and a XBee interface as transceiver for each sensor node in order to provide a reliable data collection mechanism with a low amount of power consumption. Furthermore, to upload the collected data to a remote server, we adopt a 3G/LTE cellular network for the long range wireless communication. We utilize a PandaBoard as a gateway to connect the WSN and the 3G/LTE network. The designed network is implemented and tested in a lab scenario at university and on a Marex boat along the coast

Validation of a measure to assess Post-Traumatic Stress Disorder: a Sinhalese version of Impact of Event Scale

BACKGROUND: There is paucity of measures to conduct epidemiological studies related to disasters in Sri Lanka. This study validates a Sinhalese translation of the Impact of Event Scale- 8 items version (IES-8) for use in Sri Lanka. METHODS: This cross-sectional validation study was conducted in the densely populated rural area of Tangalle in the Southern province of Sri Lanka. The English version of the IES-8 after translation procedures in to Sinhalese was administered by trained raters to a community sample of 30 survivors of tsunami aged 13 years and above. Diagnostic accuracy, reproducibility and validity of the translated IES was assessed in terms of sensitivity, specificity, predictive values, likelihood ratios, diagnostic odds ratio, inter-rater reliability, internal consistency, criterion validity and construct validity. RESULTS: The cut-off score of 15 gave a fair sensitivity (77%) for screening along with other components of diagnostic accuracy. The inter-rater reliability was high (0.89). The internal consistency for the whole scale was high (0.78) with a high face and content validity. The criterion validity was high (0.83) and the construct validity demonstrated the two factor structure documented in the literature. CONCLUSION: This study demonstrates that this Sinhalese version of the Impact of Event Scale has sound diagnostic accuracy as well as psychometric properties and makes it an ideal measure for epidemiological studies related to natural and man made disasters in Sri Lanka

Suture Trainer: Improving Tissue Handling Technique

Tissue handling is fundamental to performing mechanical tasks of suturing and surgery on live humans and animals. While the mechanics of suturing can be taught, there is no available simulation product designed to specifically teach tissue handling skills. It is important as a future medical professional to gain better tissue handling skills in order to prevent unnecessary injury to the tissue via scarring. The suture trainer focuses on providing feedback in order to standardize tissue handling technique in order to prevent poor habits from developing. Our project deliverables included a model, working prototype, and test data collected from practicing physicians which was incorporated into the final prototype. Constraints that were considered included cost of the product, having the device be reusable, and having the device be representative of suturing in surgery. The suture trainer is a modified Adson forceps with a piezoelectric sensor on top and a feedback mechanism that incorporates two ranges: a safe range and a danger range. The suture trainer reinforces proper grip and pressure of the Adson forceps in order to improve tactile and proprioceptive skills to allow development of gentle tissue handling skills outside of a live patient situation . Future designs would incorporate a microprocessor which would be able to record data over a certain period and would give the user feedback on improvement of tissue handling skills over time. This invention can be used in suturing simulations for medical students and for all medical providers that suture patients. This includes physician assistants, nurse practitioners, and surgical technicians and residents. It can be used for a variety of simulated tissues including skin, hollow organ, and blood or lymphatic vessels.https://scholarscompass.vcu.edu/capstone/1071/thumbnail.jp

Solution Properties and Self-Assembling of Cationic Diblock Copolymers

Solution properties and self-assembling of three polycations have been studied. The main emphasis was on poly((vinylbenzyl) trimethylammonium triflate) (PVBTMA-OTf), synthesized via RAFT polymerization. The PVBTMA-OTf is soluble in water, however, the presence of triflate ions turned it thermoresponsive. Both PVBTMA-OTf and its counterpart with a chloride counterion (PVBTMAC) underwent an UCST type phase transition in aqueous triflate solutions. With increasing the molar mass the cloud point shifted to higher temperatures. The behavior was different in two less hydrophobic polycations, poly((2-(methacryloyloxy)ethyl) trimethylammonium chloride) (PMOTAC) and poly (3-(acrylamidopropyl)trimethylammonium chloride) (PAMPTMAC). Higher amounts of hydrophobic ions were needed to induce the UCST behavior. Diblock copolymers comprised of a poly(ethylene glycol) (PEG) block and PVBTMA-OTf with different block lengths were synthesized via controlled RAFT polymerizations. The block copolymers underwent stepwise phase separation when the polycation blocks were kept short. During cooling, the polymers first phase separated below cloud point temperature (TcU), but solutions became clear (at TcL) upon further cooling. The stepwise phase separation was dependent on the LiOTf concentration and molar mass of the polymers. The copolymers with longer cationic blocks phase separated in a single step similarly to the phase separation of the homopolymer PVBTMA-OTf. The block copolymers formed core-shell particles below TcL. Copolymers with short cationic blocks built up PEG-stabilized particles, however, when the positively charged blocks were long, PEG was buried inside the particles. Due to the complex interactions between two blocks and as well as the interactions mediated by the counterions, the segregation of the blocks is difficult. As a result, with increasing the cationic block length the copolymers phase separated into complex aggregates. Styrenic polycations PVBTMAC were chain extended with diacetone acrylamide (DAAM) via RAFT in aqueous solutions. Only spherical particles were obtained in pure water. However, by increasing the ionic ratio [NaCl]/[Cp] (where [Cp] is the concentration of cationic repeating unit), the particle morphology changed from spheres to fused aggregates or worms, even to vesicles when short styrenic macroCTAs were used. The final morphology depended on the second block length and the solids content. Copolymers with either long styrenic stabilizers or with other macroCTAs, PMOTAC and PAMPTMAC formed spheres, cloudberries, or raspberries with increasing the salt concentration or the solids content. Cationic particles from PVBTMAC prepared in salt-free dispersions phase separated in aqueous triflate solutions at a critical temperature. In some cases, the phase separation occurred in two steps. When the PISA reactions were conducted in triflate solutions, fused spheres were obtained. Increasing the solids content, particle morphologies evolved to vesicles with small lumens. The particles prepared at 70° C in aqueous LiOTf changed from spheres or fused spheres to wormlike networks/ fused aggregates when cooled to room temperature. On the other hand, the morphologies of the particles prepared with PMOTAC or PAMPTMAC macroCTAs were not affected by triflate ions. To sum up, this work presents the use of triflate ions to induce thermoresponsive behavior in polycations and their diblock copolymers. Covalent linkage of hydrophilic PEG blocks to the responsive polycation PVBTMA-OTf enhances the stability of the particles, and the behavior is dependent on molar mass and LiOTf concentration. Using styrenic polycations as sole steric stabilizers in PISA, a full morphological window of particles can be obtained simply by adjusting the ionic strength. The particles made with styrene based cationic stabilizers also show UCST behavior. This study demonstrates the use of triflate ions in PISA to induce order-order or morphological transitions.Työssä on tutkittu kolmen polykationin liuosominaisuuksia ja itsejärjestymistä. Päähuomio oli poly((vinyylibentsyyli)trimetyyliammoniumtriflaatissa) (PVBTMA-OTf), joka oli valmistettu RAFT-polymeroinnilla. PVBTMA-OTf on vesiliukoinen, mutta triflaatti-ionit tekivät siitä lämpöherkän. Sekä PVBTMA-OTf, että saman polykationin kloridi (PVBTMAC) faasierottuivat (UCST) triflaatin vesiliuoksissa. Moolimassan kasvaessa samepiste siirtyi korkeampiin lämpötiloihin. Kaksi vähemmän hydrofobista polykationia, poly(2-(metakroyylioksi)etyylitrimetyyliammoniumkloridi) (PMOTAC) ja poly(3-(akryyliamidopropyyli)trimetyyliammoniukmkloridi) (PAMPTMAC) käyttäytyivät käyttäytyivät eri tavalla. UCST:n indusoimiseksi tarvittiin suuremmat määrät hydrofobisia ioneja. Kontrolloidulla RAFT-polymeroinnilla syntetisoitiin diblokkikopolymeereja poly(etyleeniglykolista) (PEG) ja eripituisista PVBTMA-OTf-blokeista. Kun polykationiblokit olivat lyhyitä, polymeerien faasierottuminen tapahtui vaiheittain. Jäähdytettäessä polymeerit ensin faasierottuivat samepisteen (TcU) alapuolella, mutta edelleen jäähdytettäessä liuokset kirkastuivat lämpötilassa TcL. Vaiheittainen faasierottuminen riippui IlOTF-konsentraatiosta ja polymeerien moolimassasta. Polymeerit, joissa oli pitkä polykationiblokki, erottuivat yhdessä vaiheessa, kuten homopolymeeri PVBTMA-OTf. Blokkikopolymeerit muodostivat ydin-kuori-partikkeleita TcL:n alapuolella. Ne polymeerit, joissa kationinen blokki oli lyhyt, muodostivat PEG:n stabiloimia partikkeleita, mutta jos kationinen blokki oli pitkä, PEG-blokit hautautuivat partikkelien sisään. Johtuen blokkien välisistä monimutkaisista vuorovaikutuksista, sekä vastaionien välittämistä vuorovaikutuksista, kahden blokin erottuminen erillisiksi faaseiksi on vaikeaa. Tästä johtuen kationisen blokin pidentäminen johti monimutkaisten aggregaattien muodostumineen faasierottumisen yhteydessä. Styreenipohjaisia PVBTMAC-polykationeja pidennettiin vedessä RAFT-tekniikalla diasetoniakryyliamidilla (DAAM). Puhtaassa vedessä muodostui vain pyöreitä partikkeleita. Ionisuhdetta [NaCl]/[Cp] kasvatettaessa partikkelien morfologia muuttui palloista fuusioituneiksi aggregaateiksi tai madoiksi, jopa vesikkeleiksi jos styreenipohjainen makroketjunsiirtäjä oli lyhyt. Lopullinen morfologia riippui kasvavan ketjun pituudesta ja kiintoainepitoisuudesta. Kopolymeerit, joissa oli käytetty pitkää styreenipohjaista stabilisaattoria tai muita ketjunsiirtäjiä PMOTAC ja PAMPTMAC, muodostivat suolakonsentraation tai kiintoainepitoisuuden kasvaessa palloja, lakkoja tai vadelmia. Kationiset partikkelit, jotka oli valmistettu suolattomissa dispersioissa käyttäen PVBTMAC:a faasierottuivat kriittisessä lämpötilassa triflaatin vesiliuoksissa. Joissain tapauksissa faasierottuminen tapahtui kahdessa vaiheessa. Kun PISA-reaktiot oli suoritettu triflaattiliuoksissa, tuloksena oli toisiinsa takertuneita palloja. Kiintoainepitoisuutta nostettaessa muodostui vesikkeleitä, joiden sisällä oleva aukko oli pieni. Kun LiOTF:n vesiliuoksissa 70 °C:ssa valmistetut partikkelit jäähdytettiin huoneenlämpöön, pallot tai toisiinsa takertuneet pallot muodostivat käärmemäisiä verkkoja/fuusioituneita aggregaatteja. Toisaalta, triflaatti-ionit eivät vaikuttaneet niiden partikkeleiden morfologiaan, jotka oli valmistettu käyttäen PMOTAC:a tai PAMPTMAC:a ketjunsiirtäjänä. Yhteenvetona voidaan todeta, että tässä työssä selvitettiin, kuinka polykationit ja niiden blokkikopolymeerit voidaan muuttaa lämpöherkiksi triflaatti-ioneilla. Hydrofiilisen PEGin kovalenttinen kiinnittäminen lämpöherkkään PVBTMA-OTf:in parantaa polymeeripartikkelien stabiilisuutta, ja partikkelien ominaisuudet riippuvat ketjun moolimassasta LiOTf:n konsentraatiosta. Kun käytetään styreenipohjaisia polykationeja ainoana steerisenä stabilisaattorina PISA-reaktiossa, kaikki mahdolliset partikkelimorfologiat on mahdollista saavuttaa yksinkertaisesti ionivahvuutta säätämällä. Työssä osoitettiin, kuinka käyttämällä triflaatti-ioneja PISA-reaktioissa voidaan indusoida järjestyksen tai morfologian muutoksia.

Polycation-PEG Block Copolymer Undergoes Stepwise Phase Separation in Aqueous Triflate Solution

A block copolymer poly(ethylene glycol)-b-poly(vinylbenzyltrimethylammonium triflate), PEG-PVBTMA-OTf, and a homopolymer PVBTMA-OTf were synthesized through RAFT reactions. The polymers were studied in aqueous triflate solutions with varying temperatures, changing also the polymer and salt concentrations. The hydrophobic triflate anion turns polycations thermoresponsive, and they show an UCST. In the block copolymer, the interaction between the PEG and the cationic block makes the phase separation occur in distinct steps. Upon cooling, transparent solutions first turn turbid and then partially clear at T-cL. The T-cL is not observed in a mixed solution of PVBTMA-OTf and PEG macro-CTA. By considering the interplay between ionic, hydrogen bonding, and hydrophobic interactions, an overall picture of the complex phase separation processes is suggested.Peer reviewe