High-temperature Thermal Processing Research Articles

Associations between cooking method of food and type 2 diabetes risk: A prospective analysis focusing on cooking method transitioning

Cooking process for food significantly impacts household air and increase exposure to endocrine disruptors such as acrylamide and, consequently, affecting human health. In the past 30 years, the transformation of cooking methods to high-temperature thermal processing has occurred widely in China. Yet the transition of cooking methods on the onset of type 2 diabetes (T2D) remains unclear, which may hinder health-based Sustainable Development Goals. We aimed to estimate the associations between dietary intake with different cooking methods and T2D risk. We included 14,745 participants (>20 y) from the China Health and Nutrition Survey (1991–2015). Food consumption was calculated using three consecutive 24-h dietary recalls combined with both individual participant level and household food inventory. Cooking methods, including boiled, steamed, baked, griddled, stir-fried, deep-fried, and raw, were also recorded. The consumption of baked/griddle foods and deep-fried foods are positively associated with 39% and 35% higher of T2D risk by comparing the highest with the lowest categories of food consumption, respectively. The overall unhealthy cooking method for processing foods including baked/griddled and deep-fried foods was attributable for 15 million T2D cases of the total T2D burden in 2011, resulting in a medical cost of $2.7 billion and was expected to be attributable for 39 million T2D cases in 2030, producing a medical cost of $223.8 billion. Replacing one serving of deep-fried foods and baked/griddle foods with boiled/steamed foods was related to 50% and 20% lower risk of T2D, respectively. Our findings support healthy driven cooking methods for daily diet are recommended to nourish sustainable T2D prevention in China.

Study of high-temperature deformation behavior and thermal processing diagram of cast TA15 titanium alloy

Study of high-temperature deformation behavior and thermal processing diagram of cast TA15 titanium alloy

Low-temperature ozone treatment for p-xylene perm-selective MFI type zeolite membranes: Unprecedented revelation of performance-negating cracks larger than 10 nm in polycrystalline membrane structures

We report that low-temperature ozone calcination allowed MFI type polycrystalline zeolite membranes to maximize their p-/o-xylene separation factor (as high as ca. 2000) by suppressing defect formation. Conventional high-temperature calcination and rapid thermal processing, which provide poor and marked p-/o-xylene separation abilities, respectively, were used for comparison. The corresponding defect structures were quantitatively analyzed by image processing of fluorescence confocal optical microscopy images combined with membrane permeation modeling, revealing the main defects (grain boundary defects and cracks) and their tortuosity, porosity, and size. To the best of our knowledge, we, for the first time, demonstrated that in contrast to common belief, the minor portion of wider cracks instead of the major portion of narrower grain boundary defects determined the final permeation rates. Specifically, the MFI membrane prepared by high-temperature calcination contained many grain boundary defects (narrow; ca. 1 nm) and few cracks (wide; ca. 20 nm) that accounted for ca. 0.1% and 99.8%, respectively, of the slowly permeating o-xylene molar flux. In contrast, the ozone-treated MFI membranes, which only possessed grain boundary defects, achieved the high p-/o-xylene separation performance, underlining the need for the selective reduction in the number of wider cracks rather than ubiquitous, narrow grain boundary defects.

Solid Phase Recrystallization in Arsenic Ion-Implanted Silicon-On-Insulator by Microsecond UV Laser Annealing

UV laser annealing (UV-LA) enables surface-localized high-temperature thermal processing to form abrupt junctions in emerging monolithically stacked devices, where the applicable thermal budget is restricted. In this work, UV-LA is performed to regrow a silicon-on-insulator wafer partially amorphized by arsenic ion implantation as well as to activate the dopants. In a microsecond scale ( 10^-6 s to 10^-5 s) UV-LA process, monocrystalline solid phase recrystallization and dopant activation without junction deepening are evidenced, thus opening various applications in low thermal budget integration flows. However, some concerns remain. First, the surface morphology is degraded after the regrowth, possibly because of the non-perfect uniformity of the used laser beam and/or the formation of defects near the surface involving the excess dopants. Second, many of the dopants are inactive and seem to form deep levels in the Si band gap, suggesting a further optimization of the ion implantation condition to manage the initial crystal damage and the heating profile to better accommodate the dopants into the substitutional sites.

Flexible iron oxide supercapacitor electrodes by photonic processing

We report the preparation of flexible and nano-porous iron oxide-reduced graphitic oxide (Fe2O3–rGO) electrodes using a novel photonic processing method. Due to this unique technique, high-temperature thermal processing could be accomplished on inexpensive and low-temperature substrates instantaneously as opposed to longer processing times of conventional thermal processing. The nano-porous morphology of the electrode not only accommodates the volume changes of the electrode but also facilitates the transport of the electrolyte ions into the electrodes. The as-prepared electrode showed excellent electrochemical performance with an initial specific capacitance of 179 F/g at 2 A/g. Moreover, it exhibited excellent specific capacitance retention after 5000 cycles (70%), revealing its superior cyclic stability. Along with having specific capacitance comparable to that of rigid electrodes, the as-prepared electrode is bendable and lightweight, signifying its potential application in foldable and wearable consumer electronic devices which require continuous energy supply while going through physical deformation.Graphic abstract

(Invited) Facile Formation of Luminescent Colloidal Silicon Quantum Dots from Porous Silicon

Silicon quantum dot is nanometer sized single crystalline silicon particles. It shows exotic luminescence properties such as size tuneablilty of luminescence band and quasi-direct electron-hole recombination resulting in efficient visible luminescence at room temperature, due to quantum confinement effects. Because of its environmental friendliness and low cost, the silicon quantum dot is a promising material for future light-emitting applications. Recently, a free-standing form of silicon quantum dot dispersed in solution, i.e., colloidal silicon quantum dots are intensively investigated due to their potential usefulness in solution based light emitting technology. The luminescence properties and solution dispersibility in silicon quantum dots are known to depend on the surface properties such as the coverage of surface termination and the kinds of surface terminated species.Various formation techniques for colloidal silicon quantum dot have been proposed, such as wet-chemical synthesis, plasma synthesis and high-temperature thermal processing. Pulsed-laser irradiation in liquid is one of the simplest top-down method for the formation of colloidal silicon quantum dots. By irradiating bulk crystalline silicon target with a high power pulsed-laser beam in liquid, silicon quantum dots are easily formed due to the ablation of silicon crystal and resultant condensation effect of ablated silicon at the liquid interface. An additional merit of this process is the easiness of surface termination control; because the nanocrystal surface formed by laser ablation actively reacts with molecules consisting of solution, one can control the surface termination by changing the kinds of solution. However, the control of the formed quantum dot size is still a challenging work and the size distribution of the quantum dots prepared by this process is usually wide.To overcome these issues, we developed a novel top-down pulsed laser irradiation technique for the formation of colloidal silicon quantum dots. We used an interconnected wire-nanostructure assembly, i.e., porous silicon (PSi), as a target material for the laser irradiation process, on behalf of bulk crystalline silicon target. PSi has beneficial properties for laser irradiation target such as low thermal conductivity and large surface areas. Because of these properties, the pulsed-laser irradiation of PSi target in organic solution allows us to generate the silicon quantum dots with relatively high preparation yields, and with various emission bands by changing irradiation conditions and the porosity of PSi. Furthermore, in our developed process, the formed dots are brighter than the original PSi target due to the stable organic terminations.Recently, we further improved our developed facile formation process of luminescent colloidal silicon quantum dots via porous silicon target. In the improved process, we employed electrochemically prepared PSi flakes, which purely consists of porous layer. The PSi flakes show extremely low thermal conductivity and heat capacity due to their intrinsic geometrical feature. Thus, even a low temperature thermal treatment as well as pulsed laser irradiation to PSi flakes in organic solution are efficiently converted porous silicon layer to colloidal silicon quantum dots. Furthermore, we succeeded in preparing silicon quantum dots dispersed in a polar and non-polar solvent depending on the ligands terminated on the dot surface by using different solutions. The present facile formation process of silicon quantum dots from PSi allows us to develop future top-down and low-cost mass production of luminescent colloidal silicon quantum dots.

Identification and characterization of two novel antioxidant peptides from silkworm pupae protein hydrolysates

Silkworm pupae are a kind of insect resource food that rich of good quality protein. To identify the peptide with high antioxidant activity from silkworm pupae protein hydrolysates, and provide the basis for the application of silkworm pupae protein hydrolysates and antioxidant peptides in functional foods, silkworm pupae proteins were hydrolysed by a dual-enzyme system consisting of acidic protease and neutral protease. The hydrolysates were purified sequentially by ultrafiltration, gel filtration chromatography and high-performance liquid chromatography (HPLC). The ABTS radical scavenging activity was used to evaluate antioxidant activity. Fractions with high activity were further analyzed by liquid chromatography- tandem mass spectrometry (LC–MS/MS). Two peptides, FKGPACA and SVLGTGC with molecular weights of 692.34 and 635.30 Da were obtained. To further determine the major active sites of FKGPACA and SVLGTGC, four peptides, FKGP, ACA, SVLG and TGC were artificially synthesized. ACA and TGC had higher ABTS radical scavenging activities than FKGP and SVLG. The main active sites of FKGPACA and SVLGTGC were possibly located in the ACA and TGC fragments, which are related to Cys, Ala or Thr residues. Both FKGPACA and SVLGTGC proved to good antioxidants even after high-temperature thermal processing for 1 h. After digestion with pepsin, the ABTS radical scavenging activity of FKGPACA was stable, while the ABTS radical scavenging activity of SVLGTGC decreased slightly. After further digestion with pancreatin, the ABTS radical scavenging activities of FKGPACA and SVLGTGC decreased by 10.59% and 43.56%, respectively. After digestion with chymotrypsin, the ABTS radical scavenging activities of FKGPACA and SVLGTGC were stable. The silkworm pupae protein hydrolysates and FKGPACA could be potentially used as natural antioxidants in functional foods.

Influence of Tabula Rasa on Process- and Light-Induced Degradation of Solar Cells Fabricated From Czochralski Silicon

Monocrystalline Si solar cells are fabricated from Czochralski (Cz) Si, which contains 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">17</sup> -10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">18</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> oxygen atoms. Cz Si undergoes degradation during high-temperature thermal processing steps, such as dopant diffusion to form the p-n junction. This degradation in the bulk minority carrier lifetime can be related to the formation of oxygen precipitates. We found that a high-temperature annealing process known as tabula rasa (TR) not only mitigates process-induced degradation via oxygen precipitate nuclei dissolution, but also modifies subsequent light-induced degradation. We report on the bulk carrier lifetime of n- and p-type Cz Si after TR, which homogenizes the interstitial oxygen in the bulk Si to its monoatomic form in either an N2 or O2 environment. A control sample, which was not subjected to a TR processing step, experienced severe process-induced degradation during a boron emitter thermal budget as oxygen precipitates were formed in the Si bulk. These precipitates could be imaged using photoluminescence. Additionally, samples that underwent a TR processing step prior to the boron emitter thermal budget show efficient gettering of metallic impurities compared to the control sample, which showed a decline in the implied open-circuit voltage after the gettering step. Furthermore, modification of the interstitial oxygen bonding by TR had a strong effect on the light-induced degradation kinetics. Instead of a typically observed monotonic decrease, minority carrier lifetime increases first, followed by a nonmonotonic decrease over a ~20 h period. We conclude that by modifying the interstitial oxygen bonding via TR pretreatment, p-type Cz Si wafers become substantially resistant to harsh solar cell processes and strongly modified light-induced degradation, which would open alternative ways to mitigate this degradation mechanism.

Performance Comparison of Four-year-old Trees of Two Short-rotation Species Modified by High Temperature Thermal Process For Producing Furniture Artifacts

Four-year-old trees of two fast growing species, namely Corymbia citriodora (V1) and Eucalyptus hybrid (E. camaldulensis* E. urophylla) (V2) were subjected to high temperature thermal processing technique for improving certain wood quality parameters. Although, these species are generally grown for pulpwood production, value-added solid wood applications in furniture and other lifestyle artifacts can be produced after modifying the wood by eco-friendly thermal treatments. Small billets from bottom portion (2 meters) of the trees were converted into wooden planks which were subjected to heat treatment at 175±5°C for a fixed duration of 4 hours underpartial vacuum condition. Effect of he at treatment on physical and mechanical properties such as equilibrium moisture content (EMC), density, water absorption (WA), shrinkage, flexural strength (modulus of rupture-MOR) andstiffness (modulus ofelasticity-MOE), compressive strength parallel and perpendicular to grain and surface hardness was evaluated in both species and compared with respective controls. The moisture related wood properties such as EMC, WA and shrinkage were observed to be reduced significantly after thermal modification. Antishrinkage efficiency (ASE) increased by 43% in V1 compared to 31% in V2. MOE and maximum compressive strength values improved significantly in heat treated wood compared to respective controls. Reduction in MOR due to thermal processing was lower in V1 compared to V2.V1 samples showed greater enhancement in several desirable wood properties than V2. Basal portion of short rotation Corymbia citriodora (V1) trees can be thermally modified to improve aesthetic and techno-mechanical parameters for making value-added artifacts such as furniture, wall paneling etc. in nonstructural industry sectors, as an alternative to traditionally used species.

Supercritical CO2 Processing of a Functional Beverage Containing Apple Juice and Aqueous Extract of Pfaffia glomerata Roots: Fructooligosaccharides Chemical Stability after Non-Thermal and Thermal Treatments

The effects of supercritical CO2 processing on the chemical stability of fructooligosaccharides (FOS) and other functional and nutritional compounds were evaluated employing non-thermal and thermal approaches. Apple juice was enriched with Pfaffia glomerata roots aqueous extract due to its high content of short-chain FOS and then subjected to different levels of temperature (40 and 60 °C), pressure (8 and 21 MPa), and CO2 volume ratio (20 and 50%). The percentage of CO2 volume was evaluated concerning the total volume of the high-pressure reactor. Also, the functional beverage was thermally treated at 105 °C for 10 min. Physicochemical properties (pH and soluble solid content), beta-ecdysone, sugars (glucose, fructose, and sucrose), and FOS (1-kestose, nystose, and fructofuranosylnystose) content were determined. The pH and soluble solid content did not modify after all treatments. The pressure and CO2 volume ratio did not influence the FOS content and their chemical profile, however, the temperature increase from 40 to 60 °C increased the nystose and fructofuranosylnystose content. High-temperature thermal processing favored the hydrolysis of 1-kestose and reduced the sucrose content. Regarding beta-ecdysone, its content remained constant after all stabilization treatments demonstrating thus its high chemical stability. Our results demonstrated that supercritical CO2 technology is a promising technique for the stabilization of FOS-rich beverages since the molecular structures of these fructans were preserved, thus maintaining their prebiotic functionality.

Short duration high temperature thermal processing to reduce interfacial trapping states in perovskite solar cells obtained by a green route

Short duration high temperature thermal processing (SDTP) using ethyl acetate as an alternate to chlorobenzene, is implemented in the fabrication of CH3NH3PbI3 perovskite solar cells. Charge transfer dynamics at the TiO2/perovskite interface is found to benefit from short-duration (8 s) SDTP at 230 °C due to changes in morphology, grain size, and interfacial characteristics. SDTP at 230 °C decreases the band gap and work function of the material. Surface photovoltage and electrochemical impedance spectroscopy studies show that the density of trap states at the surface and/or TiO2/perovskite interface is lowest for the film annealed at 230 °C (8 s). Improvements in charge transfer dynamics increased the short circuit current density from 17.64 to 21.59 mA/cm2, resulting in power conversion efficiency of 14.03%.

Application of microwave-irradiation technique in deglycosylation of ginsenosides for improving apoptosis induction in human melanoma SK-MEL-2 cells

To increase the contents of medicinally effective ginsenosides, we used high-temperature and high-pressure thermal processing of ginseng by exposing it to microwave irradiation. To determine the anti-melanoma effect, the malignant melanoma SK-MEL-2 cell line was treated with an extract of microwave-irradiated ginseng. Microwave irradiation caused changes in the ginsenoside contents: the amounts of ginsenosides Rg1, Re, Rb1, Rb2, Rc, and Rd were disappeared, while those of less polar ginsenosides, such as Rg3, Rg5, and Rk1, were increased. In particular, the contents of Rk1 and Rg5 markedly increased. Melanoma cells treated with the microwave-irradiated ginseng extract showed markedly increased cell death. The results indicate that the microwave-irradiated ginseng extract induced melanoma cell death via the apoptotic pathway and that the cytotoxic effect of the microwave-irradiated ginseng extract is attributable to the increased contents of specific ginsenosides.

Linear topology in amorphous metal oxide electrochromic networks obtained via low-temperature solution processing

Amorphous transition metal oxides are recognized as leading candidates for electrochromic window coatings that can dynamically modulate solar irradiation and improve building energy efficiency. However, their thin films are normally prepared by energy-intensive sputtering techniques or high-temperature solution methods, which increase manufacturing cost and complexity. Here, we report on a room-temperature solution process to fabricate electrochromic films of niobium oxide glass (NbOx) and 'nanocrystal-in-glass' composites (that is, tin-doped indium oxide (ITO) nanocrystals embedded in NbOx glass) via acid-catalysed condensation of polyniobate clusters. A combination of X-ray scattering and spectroscopic characterization with complementary simulations reveals that this strategy leads to a unique one-dimensional chain-like NbOx structure, which significantly enhances the electrochromic performance, compared to a typical three-dimensional NbOx network obtained from conventional high-temperature thermal processing. In addition, we show how self-assembled ITO-in-NbOx composite films can be successfully integrated into high-performance flexible electrochromic devices.

Thermal and Hygroscopic Properties of Indoor Particulate Matter Collected on an Underground Subway Platform

In order to clarify the thermal and hygroscopic properties of indoor particulate matter (PM) in a semiclosed subway space, which is critically important for understanding of the distinctive particle formation processes as well as the assessment of their health effects, the size-resolved PMs (i.e., <TEX>$PM_{2.5}$</TEX> and <TEX>$PM_{10-2.5}$</TEX>) were intensively collected on the platform of Miasageori station on the Seoul Subway Line-4. The elemental concentrations in soluble and insoluble fractions were determined by PIXE from the bulkily pretreated <TEX>$PM_{2.5}$</TEX>. The thermal and hygroscopic characteristics of individual particles were investigated via a combination of the unique pretreatment techniques (i.e., the high-temperature rapid thermal process and the water dialysis) and SEM-EDX analysis. Iron and calcium were unequaled in insoluble and soluble <TEX>$PM_{2.5}$</TEX> fractions, respectively, with overwhelming concentration. The SEM-EDX's elemental net-counts for the pre- and post-pyrolyzed PMs newly suggest that magnesium and several elements (i.e., silica, aluminum, and calcium) may be readily involved in the newly generated subway fine PM by a high-temperature thermal processing when trains are breaking and starting. Through the water dialysis technique, it turned out that calcium has meaningful amount of water soluble fraction. Furthermore, the concentrations of the counter-ions associated with the calcium in subway <TEX>$PM_{10-2.5}$</TEX> were theoretically estimated.

Mathematical Modelling of Radiative Hydromagnetic Thermosolutal Nanofluid Convection Slip Flow in Saturated Porous Media

High temperature thermal processing of nanomaterials is an active area of research. Many techniques are being investigated to manipulate properties of nanomaterials for medical implementation. In this paper, we investigate thermal radiation processing of a nanomaterial fluid sheet extruded in porous media. A mathematical model is developed using a Darcy drag force model. Instead of using linear radiative heat flux, the nonlinear radiative heat flux in the Rosseland approximation is taken into account which makes the present study more meaningful and practically useful. Velocity slip and thermal and mass convective boundary conditions are incorporated in the model. The Buongiornio nanofluid model is adopted wherein Brownian motion and thermophoresis effects are present. The boundary layer conservation equations are transformed using appropriate similarity variables and the resulting nonlinear boundary value problem is solved usingMaple 14which uses the Runge-Kutta-Fehlberg fourth fifth order numerical method. Solutions are validated with previous nonmagnetic and nonradiative computations from the literature, demonstrating excellent agreement. The influence of Darcy number, magnetic field parameter, hydrodynamic slip parameter, convection-conduction parameter, convection-diffusion parameter, and conduction-radiation parameter on the dimensionless velocity, temperature, and nanoparticle concentration fields is examined in detail. Interesting patterns of relevance are observed to improve manufacturing of nanofluids.

Efficient Thermal Deglycosylation of Ginsenoside Rd and Its Contribution to the Improved Anticancer Activity of Ginseng

The root of ginseng is a famous functional food and a herbal medicine. Research into the development of a method for increasing the pharmaceutical effect of ginseng by conversion of ginsenosides, the major active components of ginseng, by high-temperature and high-pressure thermal processing has been conducted. However, changes in the structures of each ginsenoside by heat processing and their contributions to anticancer activity have not yet been fully elucidated. Here, we investigated whether anticancer activity of ginsenosides, such as Rb1, Rb2, Rc, Rd, and Re, was associated with changes in the structures of each ginsenoside by heat processing in human stomach cancer AGS cells. Upon heat processing at 120 °C, most peaks of ginsenosides Rb1, Rb2, Rc, and Rd disappeared and the contents of less-polar ginsenosides 20(S,R)-Rg3, Rk1, and Rg5 were newly detected. From the quantitative analysis of ginsenosides, the generated amounts of less-polar ginsenosides were the highest after heat processing of ginsenoside Rd. After heat processing, the diol-type ginsenosides Rb1, Rb2, Rc, and Rd gained significant antiproliferative activity. In particular, ginsenoside Rd induced the strongest cell death among the diol-type ginsenosides, whereas the triol-type gisenoside Re showed weak antiproliferative activity. Ginsenoside Rd-induced cell death was associated with caspase-dependent apoptosis. Taken together, these results demonstrate that deglycosylation of Rd contributes to improved anticancer activity of ginseng and provide new insight on the mechanism of increased anticancer effects of ginsenosides upon heat processing.

Prediction of the propagation probability of individual cracks in brittle single crystal materials

We show that x-ray diffraction imaging (topography) and finite-element modelling can determine accurately the probability of propagation of individual cracks in brittle single crystal materials. The x-ray image of the crack provides a critical parameter for crack propagation which informs a predictive model, enabling us to identify critical defects that lead to catastrophic shattering of silicon wafers during high temperature thermal processing. Wafers fracture on cooling and finite element modelling shows that, during cooling, the tangential stress at the wafer edge is tensile and results in crack propagation. The predicted fracture geometry agrees extremely well with that observed experimentally.

Identification of Listeria innocua Surrogates for Listeria monocytogenes in Hamburger Patties

Listeria innocua M1 has been used by many researchers as a nonpathogenic thermal processing surrogate for Listeria monocytogenes. However, L. innocua M1 has been criticized because its thermal survivability characteristics are not as closely parallel to L. monocytogenes as some would like in a variety of foods and processing conditions. The present study was conducted to compare multiple L. innocua and L. monocytogenes strains to validate L. innocua M1 as the ideal surrogate under high-temperature thermal processing conditions for L. monocytogenes. The D- and z-values of L. innocua M1, L. innocua strain SLCC 5639 serotype (6a), SLCC 5640 (6b), SLCC 2745 (4ab), and L. monocytogenes F4243 (4b) were calculated for raw hamburger patties. Hamburger patties were inoculated with 10(7-8) CFU/g of L. monocytogenes or L. innocua. Samples were heat treated at 4 temperatures (62.5 to 70 degrees C). At each temperature, the decimal reduction time (D-value) was obtained by linear regression of survival curves. The D- and z-values were determined for each bacterium. The D-values of L. innocua and L. monocytogenes serotypes ranged from 3.17 to 0.13 min at 62.5 to 70 degrees C, and the z-values of L. innocua and L. monocytogenes were 7.44 to 7.73 degrees C. Two of the 4 L. innocua serotypes used in this experiment have the potential for use as surrogates in hamburger meat with varying margins of safety. L. innocua M1 should serve as the primary nonpathogenic surrogate with the greatest margin of safety in verifying a new thermal process to destroy L. monocytogenes.

Analysis of acrylamide in traditional foodstuffs in Zimbabwe

We carried out a preliminary study on the occurrence of acrylamide in potentially high risk traditional foodstuffs consumed in Zimbabwe. Various studies have shown that acrylamide, a ‘probable human carcinogen’, is formed by high temperature thermal processing of carbohydrate rich foodstuffs (lnternational Agency for Research on Cancer, 1994). Acrylamide concentrations in roasted maize, groundnuts, soy beans and boiled maize were determined using liquid chromatography tandem mass spectrometer (LC-MS/MS). The relative standard deviation of the analytical technique was 5% and the limit of detection was 0.02 µg/kg. Acrylamide was not detected in boiled maize. Roasted maize contained 450 µg/kg acrylamide. Roasted groundnuts had 140 µg/kg and finally, roasted soybeans with a concentration of 70 µg/kg acrylamide.

Fundamentals of silicon material properties for successful exploitation of strain engineering in modern CMOS manufacturing

Semiconductor industry has increasingly resorted to strain as a means of realizing the required node-to-node transistor performance improvements. Straining silicon fundamentally changes the mechanical, electrical (band structure and mobility), and chemical (diffusion and activation) properties. As silicon is strained and subjected to high-temperature thermal processing, it undergoes mechanical deformations that create defects, which may significantly limit yield. Engineers have to manipulate these properties of silicon to balance the performance gains against defect generation. This paper will elucidate the current understanding and ongoing published efforts on all these critical properties in bulk strained silicon. The manifestation of these properties in CMOS transistor performance and designs that successfully harness strain is reviewed in the last section. Current manufacturable strained-silicon technologies are reviewed with particular emphasis on scalability. A detailed case study on recessed silicon germanium transistors illustrates the application of the fundamentals to optimal transistor design.