The application of nanowires (NWs) in solar cells (SCs) is of great interest due to their new promising aspects established in nanoelectronics. Semiconductors associated with plasmonic metal nanoparticles (NPs) such as Silver (Ag), Gold (Au) and Copper (Cu), show enhanced performance in solid state light absorbing SCs owing to plasmonic characteristic of noble metal NPs. Plasmonic NPs presented a significant role in development of visible light harvesting for many applications such as photocatalytic materials, photodynamic in Surface Enhanced Raman Spectroscopy (SERS) and photovoltaics (PVs). Integration of plasmonic NPs in semiconductor materials have opened the routes to expand new PV systems with high efficiency light absorption. In this project, we introduce the synthesis ZnO and TiO2 NWs used as N-type semiconducting substrates and various methods for isolating plasmonic metal NPs, which are later deposited on the semiconducting substrates. Vertically aligned ZnO and TiO2 NWs arrays were grown on the fluorine-doped tin oxide (FTO) conductive glass substrates via hydrothermal method at low temperature and the plasmonic NPs were synthesized by wet chemistry procedures and finally decorated on the NW films by using electrophoretic deposition.  The impact of metal NPs loaded on the ZnO and TiO2 NWs substrates was studied by means of UV-vis spectroscopy and Photoluminescence (PL) spectroscopy. The absorbance spectra of individual NPs were recorded. Remarkably, the reflectance spectra of produced samples presented an enhancement in light absorption of the substrates after uptake of NPs on the ZnO and TiO2 NWs. The optical properties of the as grown ZnO NWs films decorated with Ag NPs (I) in direct contact with substrate and (II) in presence of an Al2O3 insulating spacer layer have been investigated. Both systems exhibited an enhancement in the UV band-edge emission from the ZnO when excited at 325 nm. In contrast, the broad bend defect emission of the samples did not have a significant change compare to bare ZnO substrates. The observed results suggested that the ZnO and TiO2 NWs decorated with plasmonic nanoparticles can boost the optical properties of MOs NWs substrates and hence effectively enhance the separation of photoexcited electron-hole pairs and photo-conversion applications.

La présente étude avait pour but d'identifier de nouvelles stratégies pour la présentation sélective d'enzymes à la surface de nanoparticules virales dans le but d’une application potentielle dans la technologie des biocapteurs ou des puces à protéines. Les potyvirus ont été choisis comme nanosupports modèles. Les Potyvirus, le genre le plus large de la famille des Potyviridae, la seconde plus grande famille de virus de plante, sont responsables de très graves pertes dans les cultures. Ils forment des capsides flexibles en forme de bâtonnet entourant une seule molécule d'ARN positif simple brin. Les événements moléculaires conduisant à la sélection et à l'encapsidation spécifiques de l'ARN potyviral sont inconnus. Afin de mieux exploiter le potentiel de ces virus comme nanosupports, la première étape de ce travail a porté sur l’étude, in vivo, du processus d'encapsidation de l'ARN de particules de potyvirus. Des études précédentes ont montré que la protéine d'enveloppe (CP) du virus de la pomme de terre A (PVA) interfère avec la traduction de l'ARN viral lorsqu'elle est fournie en excès en trans suggérant que cela pourrait se produire pour initier l’encapsidation de l’ARN viral. Dans cette étude, nous avons montré que cette inhibition est médiée par des interactions CP-CP co-traductionnelles se produisant entre deux populations de CP, produites en trans et en cis et permettant très probablement le recrutement spécifique de l'ARN potyviral pour son encapsidation. En accord avec les études d'assemblage in vitro publiées précédemment nous proposons un mécanisme selon lequel l’encapsidation de l'ARN viral est initiée par des interactions CP-CP co-traductionnelles. Dans la deuxième partie de ce travail, différentes approches ont été testées afin d’organiser des enzymes sur les plateformes virales dans le but d’optimiser la canalisation des intermédiaires réactionnels. Parmi les trois stratégies testées seule celle utilisant un peptide qui se liant aux anticorps, le peptide z33 de la protéine A de Staphylococcus aureus a été couronnée de succès. Une couverture de 87 % des sites sur les particules de potyvirus avec l'enzyme a été obtenue. Cette stratégie a été utilisée pour piéger deux enzymes, la 4-coumarate: coenzyme A ligase (4Cl2) et stilbène synthase (STS), catalysant des étapes consécutives dans la voie de synthèse de resvératrol à partir de lysats cellulaires solubles d’E. coli clarifiés, à la surface de particules de potyvirus immobilisées sur les parois d'un tube en polypropylène. Cette stratégie rassemble les approches ascendante et descendante pour construire des nanomatériaux à base de virus et offre un moyen efficace et économique pour co-immobiliser et purifier des enzymes / The present study intended to identify new strategies for the selective presentation of biocatalysts on the surface of viral nanoparticles with potential application in biosensor technology or protein chips. Potyviruses were chosen as model nanoscaffolds for biocatalysts. Potyviruses are the largest genus in the family Potyviridae and cause significant plant damage. They form flexible rod-shaped capsids surrounding a single stranded positive sense RNA molecule. The molecular events leading to the specific selection and encapsidation of potyviral RNA are unknown. To better exploit the potential of these viruses as nanocarriers, the first step in this study was to look into their in vivo RNA encapsidation process. Earlier studies showed that Potato virus A (PVA) coat protein (CP) interferes with viral RNA translation when provided in excess in trans and it was suggested this could occur to initiate viral RNA encapsidation. In this follow up study, we used the agroinfiltration approach for the transient expression of full length, truncated or mutated viral RNAs with wild type CP (CPwt) and showed that this inhibition is mediated by co-translational CPCP interactions occurring between two CP populations, produced in trans and in cis. Because CP inhibited translation of the entire viral genome and virus particles were formed later than during normal infection, it was assumed that the CP acted during this inhibition process to specifically recruit viral RNA for encapsidation. In line with previously published in vitro assembly studies, we propose a mechanism through which viral RNA encapsidation is initiated through co-translational CP-CP interactions. The second part of this work entailed the investigation of novel approaches for organizing biocatalysts on virus platforms. The aim was to control the display of enzymes on virus surfaces while maximizing channelling of reaction intermediates. Three strategies were tested but only one involving an antibody binding peptide, the z33 peptide from Staphylococcus aureus was successful. An 87 % occupancy of accessible sites on the potyvirus particles by the enzyme was achieved. The same strategy was used to graft potyvirus particles with two enzymes: 4- coumarate:coenzyme A ligase (4CL2) and stilbene synthase (STS), catalysing consecutive steps in resveratrol synthetic pathway or a protein chimera, generated by the genetic fusion of both enzymes. This was achieved by trapping either the monoenzymes or the protein chimera from clarified soluble E. coli cell lysates on to the surface of potyvirus particles preimmobilized in a polypropylene tube. Resveratrol was synthesized from both mono-enzymes and the protein chimera in solution and on potyvirus particles. This strategy brings together a bottom-up and top down approach for designing virus based nano-materials and offers a cost effective and efficient way to co-immobilize and purify enzymes.

Cellulose nanocrystals (CNC) are great candidates for composite materials. The reasons why CNCs are such attractive materials for them are due to their great mechanical properties, high aspect ratio and low density. On the other hand, hydroxyapatite (HAp) is a kind of calcium phosphate and a main component of bones and teeth. The purpose of the present study is to make oriented nano-sized composites with CNC and HAp. Although some researchers carried out to make CNC composites with HAp for biomedical materials, nano-sized and oriented ones haven’t been achieved yet. Also, films made of CNC and other compounds are known to be transparent and have good oxygen permeability. Especially when CNCs’ direction is in parallel, they show high strength. However most previous researches dealt with particles or plate-like minerals in inorganic/CNC films, so there is no case that coated CNCs themselves were aligned in the films. Therefore fabrication of composite-oriented thin films is quite unique and it will be a potential step for bone-like hierarchical structure. In experiment, certain amount of CNC suspension with functional groups were put into revised simulated body fluid (r-SBF) solutions which were adjusted between pH 6.9-7.9 to make the molar ratio of calcium ion per functional groups on CNC surfaces between 30-230. The suspensions were put into the ultrasonic bath for 15 minutes and stirred in the thermostatic oven at 37 ⁰C for 1 hour. The process of ultrasound and stirring in oven was repeated 1-3 times depending on conditions. Precipitated products were collected with the centrifuge instrument and dried with the freeze dryer. Functional groups induced HAp’s nucleation and the HAp/CNC composites could be obtained under control of molar ratio of calcium ions per functional groups on CNC and pH. Morphology of the composites could be determined by pH and HAp content could be controlled between 25-75 wt% by initial molar ratio. The suspension having the composites synthesized in pH 7.9 with low initial molar ratio was dropped on superhydrophilic glass substrates. At the moment, the substrates were set with leans of 20 degrees. Then they were dried at 60 oC for 3 hours and transparent films containing 25-40 wt% of HAp were obtained. The transmittances of the films were more than 90 % and their thicknesses were 2.2-4.2 μm. The films were suggested to have oriented structure by polarization microscope when the shape of the composites were needle-like homogeneously and independent each other. From the results from SEM, they were aligned longitudinally at both ends of the film and laterally at the upper middle part of the films. It is considered that controlling drying direction influenced on the orientation. The current study should become a promising step to build up a bone-like hierarchical structure artificially.

Zinc oxide (ZnO) is a well-known II-VI semiconductor material that has gained renewed interest in the past decade due to the developments of growth technologies and the availability of high-quality ZnO bulk single crystals. Owing to a wide direct band gap (3.37 eV), large exciton binding energy (60 meV), and high electron mobility (440 cm2 V-1 s-1), ZnO has been used for applications including actuators, optoelectronics, and sensors. ZnO nanoparticles can be synthesized in a broad variety of morphologies, such as nanotetrapods, nanotubes, and nanowires. Among these nanostructures, the tetrapods have attracted significant attention due to their unique morphology consisting of four legs connected together in a tetrahedral symmetry. Recently, it has been reported that nano-microstructured ZnO tetrapods (ZnO-Ts) can be synthesized by flame transport synthesis (FTS) in a rapid and up-scalable approach. Compared to conventional ZnO nanoparticles, the nano-microstructured ZnO-Ts can reduce cellular uptake, while still exhibiting specific nanomaterial properties due to the nanoscale tips. Moreover, the anisotropic ZnO-Ts have the advantages of multiple electron transfer paths, chemical stability, and biocompatibility, which make the ZnO-Ts promising candidates for biomolecule sensing applications. This work herein reports a systematical study on the structural, optical and electrochemical properties of the ZnO-Ts, which were synthesized by FTS using precursor Zn microparticles. The morphology of the ZnO-Ts was confirmed by scanning electron microscopy (SEM) as joint structures of four single crystalline legs, of which the diameter of each leg is 0.7-2.2 μm in average from the tip to the stem. The ZnO-Ts were dispersed in glucose solutions to study the photoluminescence as well as photocatalytic activity in a mimicked biological environment. The photoluminescence (PL) intensity in the ultraviolet (UV) region decreased with linear dependence on the glucose concentration up to 4 mM. The ZnO-Ts were also attached with glucose oxidase (GOx) and over coated with Nafion® to form the active media for electrochemical glucose sensing. The active layers were confirmed by Fourier transform infrared spectroscopy (FT-IR). Furthermore, the current response of the active layers to glucose was studied by cyclic voltammetry (CV) in various glucose concentration conditions. Stable current response to glucose was detected with linear dependence on the glucose concentration up to 12 mM, which confirms the potential of ZnO-Ts for biomolecule sensing applications.

The layer-by-layer (LbL) technique was used to modify the surface of cellulose fibers by consecutive adsorption of poly(allylamine hydrochloride) (PAH) and poly(acrylic acid) (PAA) followed by a final adsorbed layer of anionic paraffin wax colloids. Paper hand sheets made from the modified fibers were found to be highly hydrophobic with a contact angle of 150°. In addition to the significantly increased hydrophobicity, the sheets showed improved mechanical properties, such as a higher tensile strength. Heat treatment of the prepared sheets further enhanced both the mechanical properties and the hydrophobicity. These results demonstrate the flexibility and robustness of the LbL technique, which allows us to combine the known adhesive effect of PAH/PAA LbL films with the functionality of wax nanoparticles, creating a stronger and highly hydrophobic paper. It was further observed that LbL modified sheets without wax also displayed increased hydrophobicity when heat treated. The mechanism was studied through model experiments where LbL films of PAH/PAA were assembled on flat non-porous model cellulose surfaces. Contact angle measurements showed the same trend due to heat treatment of the model films, although, the absolute value of the contact angles were smaller. Analysis using the highly interfacial sensitive vibrational sum frequency spectroscopy technique showed an enrichment of CH3 groups (from the polymer chain ends) at the solid/air interface. These results indicate that during the heat treatment, a reorientation of polymer chains occurs to minimize the surface energy of the LbL film. In the second part of this work, the adhesive interactions between the main constituents of wood fibers were studied using high-resolution measuring techniques and well-defined model films of cellulose, hemicellulose and lignin. Successful surface modification of polydimethylsiloxane (PDMS) caps, needed in the Johnson-Kendall-Roberts (JKR) measuring methodology, by LbL deposition of nanofibrillated cellulose (NFC) and poly(ethylene imine) (PEI) allowed for the first known all-wood biopolymer JKR measurements of the adhesion between cellulose/cellulose, cellulose/lignin and the cellulose/glucomannan surfaces. The work of adhesion on loading and the adhesion hysteresis were similar for all three systems, suggesting that adhesion between the different wood biopolymers does not differ greatly. / <p>QC 20120314</p>

In this Licentiate Thesis, the properties and effects of iron and iron oxide filled carbon nanotube (Fe-CNT) memories are investigated using experimental characterization and quantum physical theoretical models. Memory devices based on the simple assembly of Fe-CNTs between two metallic contacts are presented as a possible application involving the resistive switching phenomena of this material. It is known that the electrical conductivity of these nanotubes changes significantly when the materials are exposed to different atmospheric conditions. In this work, the electrical properties of Fe-CNTs and potential applications as a composite material with a semiconducting polymer matrix are investigated. The current voltage characteristics are directly related to the iron oxide that fills the nanotubes, and the effects are strongly dependent on the applied voltage history. Devices made of Fe-CNTs can thereby be designed fo gas sensors and electric memory technologies. The electrical characterization of the Fe-CNT devices shows that the devices work with an operation ratio (ON/OFF) of 5 μA. The applied operating voltage sequence is -10 V (to write), +8 V (to read ON), +10 V (to erase) and +8 V (to read OFF) monitoring the electrical current. This operation voltage (reading ON/OFF) must be sufficiently higher than the voltage at which the current peak appears; in most cases the peak position is close to 5 V. The memory effect is based on the switching behavior of the material, and this new feature for technological applications such as resistance random access memory (ReRAM). In order to better understand the memory effect in the Fe-CNTs, thesis also presents a study of the surface charge configuration during the operation of the memory devices. Here, Raman scattering analysis is combined with electrical measurements. To identify the material electronic state over a wide range of applied voltage, the Raman spectra are recorded during the device operation and the main Raman active modes of the carbon nanotubes are studied. The applied voltage on the carbon nanotube G-band indicates the presence of Kohn anomalies, which are strongly related to the material’s electronic state. As expected, the same behavior was shown by the other carbon nanotube main modes. The ratio between the D- and G-band intensities (ID/IG) is proposed to be an indicative of the operation’s reproducibility regarding a carbon nanotube memory cell. Moreover, the thermal/electrical characterization indicates the existence of two main hopping charge transports, one between the carbon nanotube walls and the other between the filling and the carbon nanotube. The combination of the hopping processes with the possible iron oxide oxygen migration is suggested as the mechanism for a bipolar resistive switching in this material. Based on these studies, it is found that the iron oxide which fills the carbon nanotube, is a major contribution to the memory effect in the material. Therefore, a theoretical study of hematite (i.e., α-Fe2O3) is performed. Here, the antiferromagnetic (AFM) and ferromagnetic (FM) configurations of α-Fe2O3 are analyzed by means of an atomistic first-principles method within the density functional theory. The interaction potential is described by the local spin density approximation (LSDA) with an on-site Coulomb correction of the Fe d-orbitals according to the LSDA+U method. Several calculations on hematite compounds with high and low concentrations of native defects such as oxygen vacancies, oxygen interstitials, and hydrogen interstitials are studied. The crystalline structure, the atomic-resolved density-of-states (DOS), as well as the magnetic properties of these structures are determined. The theoretical results are compared to earlier published LSDA studies and show that the Coulomb correction within the LSDA+U method improves both the calculated energy gaps and the local magnetic moment. Compared to the regular LSDA calculations, the LSDA+U method yields a slightly smaller unit-cell volume and a 25% increase of the local magnetic for the most stable AFM phase. This is important to consider when investigating the native defects in the compound. The effect is explained by better localization of the energetically lower Fe d-states in the LSDA+U calculations. Interestingly, due to the localization of the d-states the intrinsic α-Fe2O3 is demonstrated to become an AFM insulator when the LSDA+U method is considered. Using the LSDA+U approach, native defects are analyzed. The oxygen vacancies are observed to have a local effect on the DOS due to the electron doping. The oxygen and hydrogen interstitials influence the band-gap energies of the AFM structures. Significant changes are observed in the ground-state energy and also in the magnetization around the defects; this is correlated to Hund’s rules. The presence of the native defects (i.e., vacancies, interstitial oxygen and interstitial hydrogen) in the α-Fe2O3 structures changes the Fe–O and Fe–Fe bonds close to the defects, implying a reduction of the energy gap as well as the local magnetization. The interstitial oxygen strongly stabilizes the AFM phase, also decreases the band-gap energy without forming any defect states in the band-gap region. / <p>QC 20131107</p>

The increasing price of oil, global warming and rapid industrial growth has drawn much attention to renewable energy technologies over the last few decades. The total energy consumption is estimated to increase 1.4% per year globally. About 90% of this energy supply is generated through fossil fuel combustion with a typical efficiency of 30-40%. The remaining 60-70% of the energy is lost to the environment via automotive exhaust or industrial processes. It is highly desired to retrieve wasted heat to improve the overall efficiency of the energy conversion. Developing thermoelectric materials and devices is a potential solution to utilize waste heat as an energy source. Skutterudites are known to be promising thermoelectric materials in the temperature range 600K to 900K. Novel nanoengineering approaches and filling of skutterudites structure can further improve the transport properties of the material. In this work, Cobalt Antimonide (Co4Sb12) based skutterudites were fabricated via mechanical milling and alloying. Rear earth material Ytterbium and Cerium are used as fillers to substitute the cages in the crystal lattice of these materials. Base material is synthesized via thermochemical reduction of the precursors under hydrogen. Further processing of the material is performed with ball milling and Spark Plasma Sintering (SPS). Ball milling parameters were optimized for nanostructuring of Co4Sb12. Grain size was significantly reduced after SPS compaction. Finally, Thermoelectric transport properties of the material is evaluated over the temperature range 300K to 900K for five different composition of the skutterudites materials. Significant reduction in materials thermal conductivity was achieved through nanostructuring.

This thesis explores the practical usefulness of surface enhanced Raman spectroscopy on a colloidal substrate for quantification of organic analytes in a water matrix. The method evaluated is very simple and accessible as it utilizes a commercially available hand held Raman spectrometer and citrate reduced silver colloid substrate. Spectra of 4-mercaptopyridine (Mpy) and riboflavin (Rf) samples in distilled water were recorded. A Raman enhancement factor on the order of 108 was achieved for Mpy and its limit of detection was 0.1 nM. The standard deviation of Mpy intensity was &lt;10% for 25 nM samples recorded at the same point in time, but significantly higher for samples recorded at different times. Mpy and Rf could be detected in parallel and both analytes had a close to linear Raman intensity to concentration relationship over a 100 times relative concentration change. We conclude that with improved substrate stability, a similar method should be practically applicable for quantification of suitable analytes down to the nM-range in samples of well defined composition. Considering the method's simplicity and the limited optimization efforts it has a large room for improvement.

Magnetic nanoparticles have great potential in the biomedical and diagnostics field. Due to their small size, the particles have a high surface-to-volume ratio which enables for biofunctionalisation with different molecular probes. This makes itpossible to target them against a wide variety of biomarkers. In this project, the aim was to develop a magnetic nanoparticle-based DNA detection method with respectto sensitivity by employing circle-to-circle amplification, which is an extension of rolling circle amplification, in order to increase the assay sensitivity. The method provides high specificity due to the use of padlock probes for amplification. The project included testing and optimising the protocol used for DNA amplification and detection with a synthetic target, which involved testing different padlock probes, incubation times and incubation temperatures. Lastly, the method was tested on a biological target. It has recently been shown that specific aggregation occurs between magnetic nanoparticles and DNA, which enables for a visual readout strategy sincethe aggregates are visible to the naked eye. Initial testing of the method yielded asensitivity of about 100 attomoles. The achieved sensitivity after the optimisation work was 1 attomole of both synthetic and biological DNA targets. This is an improvement compared to the 400 attomoles that has previously been reported with one round of rolling circle amplification. The results can be used in further development of the naked-eye DNA detection method towards the realisation of a commercially attractive bioanalytical device.

In the semiconductor industry, the purification process of the silicon wafers is of a great importance. If water of sufficient quality is not used, the silicon wafer surface runs a risk of being destroyed by particles and bacteria sticking to its surface. Semiconductors cannot be manufactured on the destroyed surfaces and to achieve the highest efficiency of the circuits, water with high purity is required for the purification process. The silicon wafers produced by the manufacturer have an oxide layer on them as a protective layer. This oxide layer needs to be cleaned off before it can be used for the manufacture of semiconductors. The oxide layer is removed by applying 5% hydrogen fluoride (HF) to the surface which is afterwards cleaned away with water. It is mainly within this part of the purification process that particles and bacteria get stuck on the surface of the silicon wafer. At present, water of poor quality is used which is unable to dilute and purify the mixture that becomes with hydrogen fluoride and the oxide layer.   As development is constantly advancing and the line width of the circuits becomes narrower and smaller, water with almost no particles is needed to clean these small areas. The particle size of the water must not exceed 20 nm in order to effectively clean the silicon wafers and preferably the particle size should not exceed 10 nm.   In the present study, an air gap membrane distillation module was investigated for the purpose of verifying the purity of the water where spherical spheres of 20 nm diameter were added into the purified water and examined in a dynamic light scattering (DLS). Because ultra-pure water (UPW) is a very aggressive water, storage is a problem. Four different container materials ability to store UPW with maintained purity were studied; white borosilicate ice cream, brown borosilicate ice cream, ethylene chlorotrifluoroethylene (ECTFE) and polyvinylidene fluoride (PVDF).   Experiments were also done to further verify the purity of the water by adding ultra-pure water on a silicon wafer and allowing it to dry to study the dry spots. The dry spots were studied in an SEM to see if the water left any particles behind on the surface. The same experiment was also done with tap water and distilled water which was dripped on a silicon wafer and dried. These dry spots were examined in a scanning electron microscope (SEM). To investigate how effectively ultra-pure water cleans a silicon wafer, an amount of 5% hydrogen fluoride on a silicon wafer was added and rinsed with ultra-pure water and tap water respectively. The same experiment was also done with tap water for comparison. These silicon wafers were studied in an SEM to see if any particles were left on its surface from the respective water. An initial methodology was also done when 5% hydrogen fluoride was diluted with ultra-pure water and tap water to compare the amount of respective water it used to dilute this acid.   In the present study, simulations were made on the air gap membrane distillation module in COMSOL where four different geometries were simulated with the aim to see how the temperature profile on the hot and cold side changed as the geometry and area of the membranes changed.   The purity of the water produced with the air gap membrane distillation were verified with DLS and the particle size did not exceed 20 nm. Further experiments showed that with UPW, there were no dry spots on the surface of the silicon wafer and no particles could be seen when the silicon wafer was examined in an SEM. When the tap water was dropped on the silicon wafer and dried, one could clearly see the drying spots. When the silicon wafer was examined in an SEM, there were many particles left on the surface. The distilled water left no drying stains on the surface but on the other hand, it was able to see particles on the surface examined when in an SEM. When 5% hydrogen fluoride had been dropped on the surface and washed away with UPW, no particles could be detected when examined in an SEM. However, particles were found when the same amount of hydrogen fluoride was rinsed off with tap water.   When 5% hydrogen fluoride was diluted to a neutral pH of 6-7, about 200 ml of UPW was used as separated from tap water where it went to the quadruple to dilute the same amount of hydrogen fluoride. This showed the purity of the ultra-pure water compared to tap water.   For the simulations it was possible to see how the temperature profile changed with the area. With a large area, the temperature profile on the hot and cold side became very poor. The temperature on the hot side dropped a lot and on the cold side it increased a lot. The largest area simulated was 255x255 mm. With a smaller area, a more even temperature profile was obtained. The area that gave the best temperature profile was 180x100 mm, which was the smallest area investigated. In contrast, the diffusion area becomes smaller as the area decreases, leading to a reduced production of ultra-pure water.   This study is close to research and is about developing new technology and modifying/improving existing technology.