Flat Fresnel doublets made of PMMA and PC: combining low cost production and very high concentration ratio for CPV

Purpose The main aim of this study was a preparation development of dopant solution (DS) which can be deposited by a spray-on method and subsequently allows obtaining the n+ emitter layer with surface resistance in the range of 65-80 Ω−1. The intention of chosen spray-on method was to gain a cheaper way of dopant source deposition, compared to the commonly used methods, which is of particular importance for the new low-cost production processes. Design/methodology/approach This paper presents the sequence in producing a spray-on glass solution (DS) with very high concentration of phosphorus, which allows to perform diffusion doping at relatively low temperatures. DS contained deionized water, ethyl alcohol, tetraethoxysilane and othophosphoric acid. Findings The sequence in producing a DS was performed with respect to enabling the application to silicon wafers by spray-on method. Furthermore, the equations defined density and viscosity of DS in term of storage time were referred to determine the possibility of applying this solution by spray-on method. Besides, the dependence of the emitter surface resistance on the doping (diffusion) time was determined. Accordingly, optimal process conditions were specified. Originality/value The paper presents a new, so far unpublished composition of DS with very high concentration of phosphorus, which can be applied using a spray-on method. Moreover, original are also investigations respecting some properties of obtained DS relative to storage time.

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Wide-Band High Concentration-Ratio Volume-Holographic Grating for Solar Concentration

Sensors ◽

10.3390/s20216080 ◽

2020 ◽

Vol 20 (21) ◽

pp. 6080

Author(s):

Chengchen Wang ◽

Jianshe Ma ◽

Hongxu Kao ◽

Taihui Wu ◽

Ping Su

Keyword(s):

Concentration Ratio ◽

Low Cost ◽

Large Angle ◽

Wide Band ◽

Wave Theory ◽

Holographic Grating ◽

High Concentration ◽

Holographic Gratings ◽

Recording Conditions ◽

Light Concentration

Efficient and low-cost solar-energy collection has become the focus of many research works. This paper proposes a recording method and an experimental verification of a wide-band, large-angle, and high concentration-ratio volume-holographic grating for solar concentration. We applied the Kogelnik coupled-wave theory and photopolymer diffusion model to analyse the formation mechanism and influencing factors on the diffraction efficiency of monochromatic volume-holographic gratings. We design and construct a three-color laser-interference system to record three monochromatic volume-holographic gratings. The best recording conditions are determined by experiment and simulation. A trichromatic volume-holographic grating is obtained by gluing the three monochromatic gratings together. The experimental results show that the trichromatic volume-holographic grating with a working angle of 6.7° and a working band of visible light has a light concentration ratio of 149.2 under an illumination of the combined recorded three-color beams, and that under sunlight is 27.2. We find that the proposed trichromatic volume-holographic grating for light concentration offers the advantages of wide band and high light concentration ratio, which provide a reference for solar concentration.

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Decomposition of the metastable beta titanium alloy Ti-15-3

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100075117 ◽

1983 ◽

Vol 41 ◽

pp. 264-265

Author(s):

Y. L. Chen ◽

S. Fujlshiro

Keyword(s):

Low Cost ◽

High Strength ◽

Alpha Phase ◽

Thick Sheet ◽

Omega Phase ◽

Beta Titanium Alloy ◽

Beta Titanium ◽

Beta Matrix ◽

Metastable Beta ◽

Very High

Metastable beta titanium alloys have been known to have numerous advantages such as cold formability, high strength, good fracture resistance, deep hardenability, and cost effectiveness. Very high strength is obtainable by precipitation of the hexagonal alpha phase in a bcc beta matrix in these alloys. Precipitation hardening in the metastable beta alloys may also result from the formation of transition phases such as omega phase. Ti-15-3 (Ti-15V- 3Cr-3Al-3Sn) has been developed recently by TIMET and USAF for low cost sheet metal applications. The purpose of the present study was to examine the aging characteristics in this alloy.The composition of the as-received material is: 14.7 V, 3.14 Cr, 3.05 Al, 2.26 Sn, and 0.145 Fe. The beta transus temperature as determined by optical metallographic method was about 770°C. Specimen coupons were prepared from a mill-annealed 1.2 mm thick sheet, and solution treated at 827°C for 2 hr in argon, then water quenched. Aging was also done in argon at temperatures ranging from 316 to 616°C for various times.

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Ground water quality of selected areas of Punjab and Sind Provinces, Pakistan: Chemical and microbiological aspects

10.31221/osf.io/wns25 ◽

2019 ◽

Author(s):

Chem Int

Keyword(s):

Ionic Concentration ◽

Chloride Ions ◽

Potassium Ions ◽

Ammonium Ions ◽

High Concentration ◽

Phosphate Ions ◽

Sodium Magnesium ◽

Very High ◽

Microbiological Aspects

The assessment of groundwater is essential for the estimation of suitability of water for safe use. An attempt has been made to study the groundwater of selected areas of Punjab (Sheikhupura & Sahiwal) and Sindh (Sindh, Jawar Dharki and Dharki), Pakistan. The results indicate that pH, color and odor were all within limits of WHO that is pH ranges 6.5–8.5, colorless and odorless, respectively. The high values of suspended solids were observed in the Sindh-1 and Dharki samples. Microbiologically only Sahiwal and Jawar Dharki were found fit for drinking purpose. Trace metals analysis of Sheikhupura-1 and Sindh-1 showed that values do not fall within limits of WHO for Iron. The ionic concentration analysis showed that high bicarbonate (HCO3-), ions are present in the samples of Sahiwal and Dharki; Sindh-1 and Jawar Dharki samples showed very high concentration for chloride ions, all samples were satisfactory level for sulphate (SO42-), sodium, magnesium and phosphate ions except samples of Sindh-1 and Jawar Dharki. High concentration of calcium and potassium ions was observed in samples of Sindh-1, while all other samples were found fit for drinking purposes in respect of nitrate, nitrite and ammonium ions. The high concentration of Fluoride was found only in Sheikhupura-2 samples.

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Review on Switches for Power Applications: Macro to Micro

Recent Advances in Electrical & Electronic Engineering (Formerly Recent Patents on Electrical & Electronic Engineering) ◽

10.2174/2352096511666180518105734 ◽

2019 ◽

Vol 12 (3) ◽

pp. 200-209

Author(s):

Femi Robert

Keyword(s):

Leakage Current ◽

Power Loss ◽

Low Cost ◽

Electrical System ◽

High Isolation ◽

Fast Switching ◽

Environmental Friendly ◽

State Resistance ◽

Very High ◽

Bulk Production

Background: Switches are important component in electrical system. The switches needs to have the advantages of low ON-state resistance, very high OFF-state resistance, high isolation, no leakage current, less power loss, fast switching, high linearity, small size, arcless and low cost in bulk production. Also these switches have to be reliable and environmental friendly. Methods: In this paper, macro and microswitches for power applications are extensively reviewed and summarized. Various types of switches such as mechanical, solid-state, hybrid and micromechanical switches have been used for power applications are reviewed. The importance and challenge in achieving arcless switching is presented. Results: The use of micromechanical switches for power applications, actuation techniques, switching modes, reliability and lifetime are also reviewed. The modeling and design challenges are also reviewed. Conclusion: The applications of micromechanical switches shows that the switches can reduce the leakage current in battery operated systems and reduce the size of the system considerably.

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Near quantitative synthesis of urea macrocycles enabled by bulky N-substituent

Nature Communications ◽

10.1038/s41467-021-21678-3 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Yingfeng Yang ◽

Hanze Ying ◽

Zhixia Li ◽

Jiang Wang ◽

Yingying Chen ◽

...

Keyword(s):

High Efficiency ◽

Molecular Structures ◽

High Yield ◽

Kinetic Control ◽

High Concentration ◽

Weak Association ◽

Quantitative Synthesis ◽

Thermodynamic Stabilization ◽

Discrete Structures ◽

Very High

AbstractMacrocycles are unique molecular structures extensively used in the design of catalysts, therapeutics and supramolecular assemblies. Among all reactions reported to date, systems that can produce macrocycles in high yield under high reaction concentrations are rare. Here we report the use of dynamic hindered urea bond (HUB) for the construction of urea macrocycles with very high efficiency. Mixing of equal molar diisocyanate and hindered diamine leads to formation of macrocycles with discrete structures in nearly quantitative yields under high concentration of reactants. The bulky N-tert-butyl plays key roles to facilitate the formation of macrocycles, providing not only the kinetic control due to the formation of the cyclization-promoting cis C = O/tert-butyl conformation, but also possibly the thermodynamic stabilization of macrocycles with weak association interactions. The bulky N-tert-butyl can be readily removed by acid to eliminate the dynamicity of HUB and stabilize the macrocycle structures.

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Small-volume vitrification and rapid warming yield high survivals of one-cell rat embryos in cryotubes

Biology of Reproduction ◽

10.1093/biolre/ioab059 ◽

2021 ◽

Author(s):

Yasuyoshi Fukuda ◽

Misako Higashiya ◽

Takahiro Obata ◽

Keita Basaki ◽

Megumi Yano ◽

...

Keyword(s):

Cooling Rate ◽

Small Volume ◽

Sucrose Solution ◽

High Concentration ◽

Rat Embryos ◽

Low Concentrations ◽

Intracellular Ice Formation ◽

Intracellular Ice ◽

Warming Rate ◽

Very High

Abstract To cryopreserve cells, it is essential to avoid intracellular ice formation during cooling and warming. One way to achieve this is to convert the water inside the cells into a non-crystalline glass. It is currently believed that to accomplish this vitrification, the cells must be suspended in a very high concentration (20–40%) of a glass-inducing solute, and subsequently cooled very rapidly. Herein, we report that this belief is erroneous with respect to the vitrification of one-cell rat embryos. In the present study, one-cell rat embryos were vitrified with 5 μL of EFS10 (a mixture of 10% ethylene glycol, 27% Ficoll, and 0.45 M sucrose) in cryotubes at a moderate cooling rate, and warmed at various rates. Survival was assessed according to the ability of the cells to develop into blastocysts and to develop to term. When embryos were vitrified at a 2,613 °C/min cooling rate and thawed by adding 1 mL of sucrose solution (0.3 M, 50 °C) at a warming rate of 18,467 °C/min, 58.1 ± 3.5% of the EFS10-vitrified embryos developed into blastocysts, and 50.0 ± 4.7% developed to term. These rates were similar to those of non-treated intact embryos. Using a conventional cryotube, we achieved developmental capabilities in one-cell rat embryos by rapid warming that were comparable to those of intact embryos, even using low concentrations (10%) of cell-permeating cryoprotectant and at low cooling rates.

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Improved photocatalytic conversion of high−concentration ammonia in water by low−cost Cu/TiO2 and its mechanism study

Chemosphere ◽

10.1016/j.chemosphere.2021.129689 ◽

2021 ◽

Vol 274 ◽

pp. 129689

Author(s):

Jianpei Feng ◽

Xiaolei Zhang ◽

Guan Zhang ◽

Ji Li ◽

Wei Song ◽

...

Keyword(s):

Low Cost ◽

Mechanism Study ◽

High Concentration

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Synthesis of poly (n-butyl acrylate) with tempo by nitroxide mediated polymerization method

Polymers and Polymer Composites ◽

10.1177/09673911211024577 ◽

2021 ◽

pp. 096739112110245

Author(s):

Amrita Sharma ◽

PP Pande

Keyword(s):

Butyl Acrylate ◽

Low Cost ◽

Polymerization Process ◽

Polymerization Reaction ◽

High Concentration ◽

Acrylate Monomer ◽

Controlled Polymerization ◽

Acrylate Monomers ◽

Nitroxide Mediated Polymerization ◽

Polymerization Method

It has been observed that acrylate monomers are very difficult to polymerize with the low cost nitroxide catalyst 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO). Therefore, costly acyclic nitroxides such as N-tert-butyl-N-(1-diethylphosphono-2,2-dimethyl)-N-oxyl, (SG1), 2,2,5-Trimethyl-4-phenyl-3-azahexane-3-nitroxide (TIPNO) and TIPNO derivatives have to be used for the polymerization of the acrylic acid derivatives. There are very few reports on the use of TEMPO-derivatives toward the polymerization of n-butyl acrylate. Generally different reducing agents viz. glucose, ascorbic acid, hydroxyacetone etc. have been used to destroy excess TEMPO during the polymerization reaction. The acrylate polymerizations fail in the presence of TEMPO due to the strong C–O bond formed between the acrylate chain end and nitroxide. To the best of our knowledge, no literature report is available on the use of TEMPO without reducing agent or high temperature initiators, toward the polymerization of n-butyl acrylate. The present study has been carried out with a view to re-examine the application of low cost nitroxide TEMPO, so that it can be utilized towards the polymerization of acrylate monomers (e.g. n-butyl acrylate). We have been able to polymerize n-butyl acrylate using the nitroxide TEMPO as initiator (via a macroinitiator). In this synthesis, a polystyrene macroinitiator was synthesized in the first step from TEMPO, after this TEMPO end-capped styrene macroinitiator (PSt-TEMPO) is used to polymerize n-butyl acrylate monomer. The amount of macroinitiator taken was varied from 0.05% to 50% by weight of n-butyl acrylate monomer. The polymerization was carried out at 120°C by bulk polymerization method. The experimental findings showed a gradual increase in molecular weight of the polymer formed and decrease in the polydispersity index (PDI) with increase in amount of PSt-TEMPO macroinitiator taken. In all experiments conversion was more than 80%. These results indicate that the polymerization takes place through controlled polymerization process. Effect of different solvents on polymerization has also been investigated. In the following experiments TEMPO capped styrene has been used as macroinitiator leading to the successful synthesis of poly n-Butyl acrylate. It has been found that styrene macroinitiator is highly efficient for the nitroxide mediated polymerization, even in very small concentration for the synthesis of poly n-butyl acrylate. High concentration of macroinitiator results in the formation of block copolymers of polystyrene and poly ( n-butyl acrylate) viz. polystyrene-block-poly-( n-butyl acrylate). The use of TEMPO toward controlled polymerization is of much importance, because it is the nitroxide commercially available at the lowest cost.

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