Integration of in situ spectral ellipsometry with MMST machinecontrol

The transformation of desired physical effects to process settings has been achieved through extensive use of appropriate in situ sensors for the MMST program. In situ sensors like an ellipsometer can be used to monitor film thicknesses as well as etch or growth rate in real time, and to determine endpoint time. This capability is opposed to conventional processing, which uses pilot wafers and ex situ statistical process control. In situ sensors enable real-time wafer-to-wafer compensation for equipment and process drifts and also diagnosis of equipment status for preventive maintenance. This paper discusses the use of a spectral ellipsometer (SE) developed at Texas Instruments and the issues involved in the integration of this SE to the machine control as well as to the factory-wide computer integrated manufacturing (CIM) environment for feedforward and feedback control     

Investigation of SPPO Membranes by Positron Annihilation Lifetime Spectroscopy

Positron annihilation lifetime spectroscopy （PALS） is a powerful technique to study the free volume in polymers. The lifetime of ortho-positronium （o-Ps）, a bound state of an electron and a positron, can be used to assess the pore size while the intensity can be used to characterize the number of pores. On the basis of the values of the long-lived o-Ps components in the lifetime spectra, the radii and fractional free volumes in the sulfonated poly （2,6-dimethyl-1,4- phenyleneoxide） （SPPO） membranes with different amounts of LiCl were calculated. It was found that, with the increasing amount of LiCl, the free volume radius and the fractional free volume firstly increased and then decreased. After immersing the membranes in distilled water, the free volume radius and the fractional free volume changed with different water concentrations in the membrane.     

Feasibility study for reclamation of a secondary treated sewage effluent mainly from industrial sources using a dual membrane process

A feasibility study for reclamation of a secondary treated sewage effluent mainly from industrial sources (60%) in Singapore has been conducted using a dual membrane UF-RO process. The pilot system had a treatment capacity of 2 m³/h. The UF unit and RO unit were operated at 70–80% and 40% water recovery, respectively. Six-month run for the pilot was carried out to study the stability and fouling tendency of membranes.

The characteristics of the raw feed indicated that ammonia-N was consistently high at 30–50 mg/L. Very high fluctuations in iron (0.3–3.7 mg/L), turbidity (1–27.1 NTU) and TOC (3.2–56.7 mg/L) were observed. Nitrate was low at <0.2 mg/L. The results of the study showed that dosage of alum in the UF process significantly reduced organic foulants and phosphate scalants. The polymeric RO membrane could tolerate organics from industrial wastewater and performed >96% salt rejection at the end of the study after 6 months. The study concluded the dual membrane process was capable of reclaiming the sewage effluent mainly from industrial sources for industrial use.     

Simple indoline based donor–acceptor dye for high efficiency dye-sensitized solar cells

A simple metal-free donor–acceptor type sensitizer U01, bearing strong electron donor indoline-triphenylamine was synthesized for panchromatic sensitization of TiO₂ nanocrystalline film. Photovoltaic properties of U01 showed remarkably enhanced light harvesting due to the presence of strong electron donor and robust structure. The new U01 sensitized solar cell exhibited a photovoltaic performance: a short-circuit photocurrent density (J_sc) of 10.70 mA cm⁻², an open-circuit photovoltage (V_oc) of 0.758 V and a fill factor (FF) of 0.74, corresponding to an overall conversion efficiency of 6.01% under standard global AM 1.5 solar light condition. Our results suggest that indoline-triphenylamine based robust D–A molecular architecture is a highly promising class of panchromatic sensitizers for improvement of the performance of dye-sensitized solar cells (DSCs).     

Investigation on thermal performance of glazed solar chimney walls

This paper reports investigation on the thermal performance of glazed solar chimney walls (GSCW) under the tropical climatic conditions of Thailand. The GSCW consisted of double glass panes with an air layer and openings located at the bottom (room side glass pane) and at the top (ambient side glass pane). A prototype of GSCW was integrated into the southern wall of a small room of 2.8 m³ volume. Its dimensions were as follows: 0.74 m height, 0.50 m width and 0.10 m air gap. The size of openings was 0.05 × 0.5 m². With a clear glass of 6 mm thickness, velocity field measurement indicated that the induced airflow rate was about 0.13–0.28 m³/s. The temperature difference between room and ambient was less than that with a single layer clear glass window. The reduction of daylight due to the double glass layer is negligible. Comparison between simulated and experimental results showed a reasonable agreement, therefore, the developed numerical model is valid and could be used as a tool for the design of GSCW.     

Silicified microcrystalline cellulose based pellets and their physicochemical properties

Silicified microcrystalline cellulose (SMCC), Prosolv SMCC 50 was used as spheronization aid to manufacture pellets by extrusion and spheronization. Different ratios of SMCC to lactose were used to manufacture pellets using appropriate levels of water as liquid binder. Avicel PH101 based pellets were also manufactured for comparison of their physical properties. The ratio of liquid binder to spheronization aid was critical to produce pellets of desired size and shape. Extrudates composed of 20% aid could withstand only smaller spheronization force in order to be shaped into pellets. The successful products fulfilled the quality of pellets such as narrow size distribution and spherical in shape. The highest surface tensile strength was observed in pellets with equal ratio of lactose to SMCC while pellets having 20% aid disintegrated rapidly within 15 min. Furthermore, Prosolv SMCC 50 based pellets possessed a stronger surface tensile strength when compared with Avicel PH101 based pellets. In conclusion, Prosolv SMCC 50 has showed to be a good spheronization aid for extrusion and spheronization when used in the range of 20 to 80% content. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43829.     

The economic feasibility of sugar beet biofuel production in central North Dakota

This study examines the financial feasibility of producing ethanol biofuel from sugar beets in central North Dakota. Under the Energy Independence and Security Act (EISA) of 2007, biofuel from sugar beets uniquely qualifies as an “advanced biofuel”. EISA mandates production of 21 billion gallons of advanced biofuels annually by 2022. A stochastic simulation financial model was calibrated with irrigated sugar beet data from central North Dakota to determine economic feasibility and risks of production for 0.038 hm³y⁻¹ (or 10 MGY (Million Gallon per Year) and 0.076 hm³y⁻¹ (or 20 MGY) ethanol plants. Study results indicate that feedstock costs, which include sugar beets and beet molasses, account for more than 70 percent of total production expenses. The estimated breakeven ethanol price for the 0.076 hm³y⁻¹ plant is $400 m⁻³ ($1.52 per gallon) and $450 m⁻³ ($1.71 per gallon) for the 0.038 hm³y⁻¹ plant. Breakeven prices for feedstocks are also estimated and show that the 0.076 hm³y⁻¹ plant can tolerate greater ethanol and feedstock price risks than the 0.038 hm³y⁻¹ plant. Our results also show that one of the most important factors that affect investment success is the price of ethanol. At an ethanol price of $484.21 m⁻³ ($1.84 per gallon), and assuming other factors remain unchanged, the estimated net present value (NPV) for the 0.076 hm³y⁻¹ plant is $41.54 million. By comparison, the estimated NPV for the 0.038 hm³y⁻¹ plant is only $8.30 million. Other factors such as changes in prices of co-products and utilities have a relatively minor effect on investment viability.