Tetragonally Packed Inverted Cylindrical Microdomains from Binary Block Copolymer Blends with Enhanced Hydrogen Bonding.

Hexagonally packed (HEX) cylindrical microdomains can be obtained through the self-assembly of block copolymers (BCPs) with a moderately asymmetric volume fraction of one block (f), resulting in the formation of minor cylinders. However, for next-generation lithography and high-density memory devices, it is desirable to obtain densely and tetragonally packed inverted cylindrical microdomains, which are composed of the major block in the minor matrix. The inverted cylinders differ from conventional HEX cylinders, which consist of the minor block in the matrix of the major block. In this study, we achieved this objective by utilizing a binary blend of a polystyrene-b-poly(4-vinylpyridine) copolymer (S4VP) and polystyrene-b-poly(4-hydroxystyrene) copolymer (SHS), where the P4VP block exhibited a strong hydrogen bonding interaction with the PHS block. By carefully controlling the molecular weight ratio of S4VP and SHS as well as the blend composition, we successfully observed tetragonally packed inverted PS cylinders with a square cross-section at a volume fraction of PS of 0.69.

Dual Nanopatterns Consisting of Both Nanodots and Nanoholes on a Single Substrate.

Block copolymers (BCPs) with various nanostructures such as spheres, cylinders, gyroid, and lamellae, have received great attention for their application in nanolithography through nanopattern transfer to substrates. However, the fabrication of diverse geometries, shapes and sizes of nanostructure on a single substrate at the desired position could not be achieved because the nanostructure based on BCPs is mainly determined by the volume fraction of one block. Here, we synthesize polystyrene-hv-poly(methyl methacrylate) copolymer (PS-hv-PMMA), which contains a photocleavable linker at the junction point between PS and PMMA blocks. After vertically oriented PMMA cylindrical nanodomains in a thin film on a substrate were obtained, dual nanopatterns composed of high-density array of nanodots and nanoholes were successfully fabricated at the desired area on a single substrate using selective irradiation with a mask. The dual nanopatterns could be used to prepare metal (or metal oxide) nanostructure arrays consisting of both nanodots and nanoholes, which are utilized for smart sensors capable of simultaneously detecting two independent molecules on nanodots and nanoholes.

Improved Electricity Generation by a Microbial Fuel Cell after Pretreatment of Ammonium and Nitrate in Livestock Wastewater with Microbubbles and a Catalyst.

Livestock wastewater containing high concentrations of ammonium and nitrate ions was pretreated with microbubbles and an Fe/MgO catalyst prior to its application in microbial fuel cells because high ion concentrations can interfere with current generation. Therefore, tests were designed to ascertain the effect of pretreatment on current generation. In initial tests, the optimal amount of catalyst was found to be 300 g/l. When 1,000 ml/min O2 was used as the oxidant, the removal of ammonium- and nitrate-nitrogen was highest. After the operating parameters were optimized, the removal of ammonium and nitrate ions was quantified. The maximum ammonium removal was 32.8%, and nitrate was removed by up to 75.8% at a 500 g/l catalyst concentration over the course of the 2 h reaction time. The current was about 0.5 mA when livestock wastewater was used without pretreatment, whereas the current increased to 2.14 ± 0.08 mA when livestock wastewater was pretreated with the method described above. This finding demonstrates that a 4-fold increase in the current can be achieved when using pretreated livestock wastewater. The maximum power density and current density performance were 10.3 W/m³ and 67.5 A/m³, respectively, during the evaluation of the microbial fuel cells driven by pretreated livestock wastewater.

Characterization of Polyester Cloth as an Alternative Separator to Nafion Membrane in Microbial Fuel Cells for Bioelectricity Generation Using Swine Wastewater.

Polyester cloth (PC) was selected as a prospective inexpensive substitute separator material for microbial fuel cells (MFCs). PC was compared with a traditional Nafion proton exchange membrane (PEM) as an MFC separator by analyzing its physical and electrochemical properties. A single layer of PC showed higher mass transfer (e.g., for O2/H⁺/ions) than the Nafion PEM; in the case of oxygen mass transfer coefficient (ko), a rate of 50.0 × 10⁻5 cm·s⁻¹ was observed compared with a rate of 20.8 × 10⁻5 cm/s in the Nafion PEM. Increased numbers of PC layers were found to reduce the oxygen mass transfer coefficient. In addition, the diffusion coefficient of oxygen (DO) for PC (2.0-3.3 × 10⁻6 cm²/s) was lower than that of the Nafion PEM (3.8 × 10⁻6 cm²/s). The PC was found to have a low ohmic resistance (0.29-0.38 Ω) in the MFC, which was similar to that of Nafion PEM (0.31 Ω); this resulted in comparable maximum power density and maximum current density in MFCs with PC and those with Nafion PEMs. Moreover, a higher average current generation was observed in MFCs with PC (104.3 ± 15.3 A/m³) compared with MFCs with Nafion PEM (100.4 ± 17.7 A/m³), as well as showing insignificant degradation of the PC surface, during 177 days of use in swine wastewater. These results suggest that PC separators could serve as a low-cost alternative to Nafion PEMs for construction of cost-effective MFCs.

Non-destructive quality evaluation of pepper (Capsicum annuum L.) seeds using LED-induced hyperspectral reflectance imaging.

In this study, we developed a viability evaluation method for pepper (Capsicum annuum L.) seeds based on hyperspectral reflectance imaging. The reflectance spectra of pepper seeds in the 400-700 nm range are collected from hyperspectral reflectance images obtained using blue, green, and red LED illumination. A partial least squares-discriminant analysis (PLS-DA) model is developed to classify viable and non-viable seeds. Four spectral ranges generated with four types of LEDs (blue, green, red, and RGB), which were pretreated using various methods, are investigated to develop the classification models. The optimal PLS-DA model based on the standard normal variate for RGB LED illumination (400-700 nm) yields discrimination accuracies of 96.7% and 99.4% for viable seeds and nonviable seeds, respectively. The use of images based on the PLS-DA model with the first-order derivative of a 31.5-nm gap for red LED illumination (600-700 nm) yields 100% discrimination accuracy for both viable and nonviable seeds. The results indicate that a hyperspectral imaging technique based on LED light can be potentially applied to high-quality pepper seed sorting.

Diffuser-incorporated transmission NIR measurement for reliable analysis of packed granular samples.

A diffuser-incorporated transmission near-infrared (NIR) scheme that enables direct spectral collection of packed granular samples with reliable sample representation and reproducibility has been demonstrated. The analytical utility of this method has been evaluated for the determination of polyethylene (PE) pellet density and the discrimination of the geographical origin of rice samples. Based on the preliminary observation of transmission spectral features acquired from spherical polyoxymethylene (POM) packings composed of different particle sizes as well as packing thickness, a portion of the radiation was propagated through the void space in the packing without fully interacting with the POM pellets. This type of radiation, so-called non-fully interacted radiation (NFIR), adversely affected the sample representation as well as the reproducibility of transmission measurements. To maximize the interaction of NIR radiation with granular samples, a polytetrafluoroethylene (PTFE) diffuser was positioned in front of the sample packing to introduce isotropically diffused radiation into the sample. This diffuser-incorporated scheme resulted in highly reproducible transmission spectra for both packed granular samples. Consequently, the density determination of PE pellets as well as discrimination of rice samples according to geographical origin was more accurate using the proposed scheme.

Enhanced Raman spectroscopic discrimination of the geographical origins of rice samples via transmission spectral collection through packed grains.

Transmission Raman spectroscopy has been effectively utilized for the discrimination of rice samples according to geographical origin. Since the constituents of rice are heterogeneously distributed and/or localized in a grain, the collection of Raman spectra providing a better compositional representation of packed rice grains is an essential requirement for accurate analysis. The optimal packing thickness yielding the most reproducible transmission spectra was initially determined. Internal propagation of radiation was more sensitively influenced by random packing when a packing was thinner; while, a thicker packing largely attenuated transmitting Raman signal and eventually degraded the signal-to-noise ratio of collected spectra. At the determined packing thickness, transmission spectra of all rice samples were collected, and discrimination into two different geographical origins was performed using principal component analysis (PCA) combined with linear discriminant analysis (LDA). For comparison, back-scattering Raman spectra of the same samples were also collected. The discrimination accuracy was improved when Raman spectra collected directly through the packed rice grains were used. Since the constituents of rice were not homogeneously distributed in a grain as confirmed using Raman microscopy, the transmission measurement enabling transversal sampling across a packing of rice grains was better for compositional representation of individual grains in the packing and able to recognize minute spectral differences between two groups, ultimately leading to more accurate discrimination of geographical origin.

Multispectral fluorescence lifetime imaging of feces-contaminated apples by time-resolved laser-induced fluorescence imaging system with tunable excitation wavelengths.

We recently developed a time-resolved multispectral laser-induced fluorescence (LIF) imaging system capable of tunable wavelengths in the visible region for sample excitation and nanosecond-scale characterizations of fluorescence responses (lifetime imaging). Time-dependent fluorescence decay characteristics and fluorescence lifetime imaging of apples artificially contaminated with a range of diluted cow feces were investigated at 670 and 685 nm emission bands obtained by 418, 530, and 630 nm excitations. The results demonstrated that a 670 nm emission with a 418 nm excitation provided the greatest difference in time-dependent fluorescence responses between the apples and feces-treated spots. The versatilities of the time-resolved LIF imaging system, including fluorescence lifetime imaging of a relatively large biological object in a multispectral excitation-emission wavelength domain, were demonstrated.

Fluorescence characteristics of wholesome and unwholesome chicken carcasses.

Each chicken carcass intended for U.S. consumers is mandated to be inspected by Food Safety and Inspection Service (FSIS) inspectors for its wholesomeness at the processing plants. Fluorescence responses of wholesome and unwholesome chicken carcasses were characterized and further evaluated for potential on-line applications for detection and classification of wholesome and unwholesome chicken carcasses. For this study, unwholesome chicken carcasses included cadaver and those with disease conditions such as airsacculitis and septicemia. Fluorescence characteristics from the epidermal layers in the breast areas of chicken carcasses were dynamic in nature. Emission peaks and ridges (maxima) were observed at 386, 444, 472, 512, and 554 nm and valleys (minima) were observed at 410, 460, 484, and 538 nm. One of the major factors affecting the line shapes of fluorescence responses from chicken carcass skin layers was absorption by hemoglobin. With the use of the normalized ratio spectra (NRS) approach, oxyhemoglobin was shown to be a major constituent in chicken carcasses affecting the fluorescence emission line shapes. Subtle line shape changes in the NRS also provided a qualitative means by which to assess the minute differences in oxy- and deoxyhemoglobin compositions perturbed by poultry diseases such as septicemia and airsacculitis. With the use of simple fluorescence band ratios as a multivariate model, wholesome and unwholesome chicken carcasses were correctly classified with 97.1% and 94.8% accuracies, respectively. On-line implementation of fluorescence techniques for the assessment of chicken carcass wholesomeness appears promising.

A management information system to study space diets.

A management information system (MIS), including a database management system (DBMS) and a decision support system (DSS), was developed to dynamically analyze the variable nutritional content of foods grown and prepared in an Advanced Life Support System (ALSS) such as required for long-duration space missions. The DBMS was designed around the known nutritional content of a list of candidate crops and their prepared foods. The DSS was designed to determine the composition of the daily crew diet based on crop and nutritional information stored in the DBMS. Each of the selected food items was assumed to be harvested from a yet-to-be designed ALSS biomass production subsystem and further prepared in accompanying food preparation subsystems. The developed DBMS allows for the analysis of the nutrient composition of a sample 20-day diet for future Advanced Life Support missions and is able to determine the required quantities of food needed to satisfy the crew's daily consumption. In addition, based on published crop growth rates, the DBMS was able to calculate the required size of the biomass production area needed to satisfy the daily food requirements for the crew. Results from this study can be used to help design future ALSS for which the integration of various subsystems (e.g., biomass production, food preparation and consumption, and waste processing) is paramount for the success of the mission.