RESULTS ON ESTIMATION AND TESTING FOR A UNIT ROOT IN THE NONSTATIONARY AUTOREGRESSIVE MOVING-AVERAGE MODEL

Abstract. We review the limiting distribution theory for Gaussian estimation of the univariate autoregressive moving-average (ARMA) model in the presence of a unit root in the autoregressive (AR) operator, and present the asymptotic distribution of the associated likelihood ratio (LR) test statistic for testing for a unit root in the ARMA model. The finite sample properties of the LR statistic as well as other unit root test procedures for the ARMA model are examined through a limited simulation study. We conclude that, for practical empirical work that relies on standard computations, the LR test procedure generally performs better than other standard procedures in the presence of a substantial moving-average component in the ARMA model.     

Effects of geometric parameters on confined impinging jet heat transfer

The objective of this work is to carry out a numerical investigation to examine the effects of geometric parameters on the confined impinging jet heat transfer. Parameters such as Nusselt number, Reynolds number, H/W have been studied. Nozzle width H ranges from 0.6 mm to 2 mm, and nozzle-to-plate spacing W ranges from 0.5 mm to 10 mm. The jet flow is in the range of laminar flow with Reynolds number from 26.8 to 1000. This paper presents distributions of target surface temperature, local and average Nusselt number on the target plate. Pressure drop for different H/W is also obtained. This study can provide useful information to the application of impinging jet heat transfer in industry.     

Effect of Cathode Designs on Radiation Emission of Compact Diode (CD) Device

A comparative study on the radiation emission such as X-ray yield and efficiency has been carried out in compact diode device. Two different designs of cathode having sharp-edged razor blade (of 0.5 mm thickness with width 2 mm) and a sewing machine needle (of 0.5 mm diameter at tip with length of 39 mm) have been tested for this study. The radiation emission (X-ray yield) was determined by employing two set of PIN diodes at fixed positions. The maximum X-ray yield depends on cathode designs and electrodes separation in few mm. The yield of X-ray is small in the case of sharp-edged razor blade cathode than the sewing machine needle cathode. The X-ray yield, measured by 4π-geometry, shows its dependence on the cathode designs. The maximum X-ray yield is found to be 939.2 ± 65.7 mJ with efficiency of 0.4142 ± 0.0289%. This study indicates that the compact diode device could be optimized to a great extent for optimal X-ray yield by using an appropriate cathode design.     

Development of polymer derived carbon coated monolith for liquid adsorption application by response surface methodology

The preparation of polymer derived activated carbon coated monolith is reported. The response surface methodology based on Box–Behnken design is used to find the optimal condition for synthesis of mesoporous carbon. The dominant parameters identified are the carbonization temperature, concentration, and molecular weight of pore former agent. Typical values for BET surface area are 341 m²/g _carbon and 20 m²/g _{supported carbon} with pores size distribution in the range of 4–400 nm. The highest pore volume obtained is 182.77 mm³/g _{supported carbon}.     

The reliability of traditional authentication – A case of ginseng misfit

Ginseng is a famous herb in traditional Chinese medicine. Herbs like ginseng have traditionally been authenticated by morphological and histological means, but it is difficult to identify these herbs nowadays since they look morphologically similar. The quality of food and pharmaceutical products is important for ensuring efficacy and consumer safety. Although several studies have stated that these traditional methods of authenticating ginseng are now hardly reliable, there have been little or no studies which have documented the reliability of such approaches. We report in this study a case of misidentification of ginsengs based on traditional methods of authentication via morphology, and the ability of using infrared spectroscopy and principal component analysis as a rapid form of quality surveillance by discriminating this error.     

Shock analysis of non-operating hard disk drives based on a multibody dynamic formulation

Dropping, striking, or bouncing a hard disk drive (HDD) against a hard surface can damage it internally without external evidence of damage. Contact with a hard ground will lift the slider off the disk surface and then slap back on the surface. A drive that is subjected to this type of shock may fail on initial use or the reliability of the drive may degrade over time. Therefore, industry has a lot of interest on the shock conditions that cause a slider to lift off the disk surface. Finite element software such as ANSYS/LS-DYNA is often used to analyze this shock problem. However, this method consumes a great amount of time. It is also difficult to perform design parameter studies because it requires re-analysis of the model of the entire HDD system when certain design variables are changed. This paper presents a flexible multi-body dynamics formulation to analyze the shock problem of non-operating HDDs. Governing equations of motion of the voice coil motor (VCM)–actuators assembly and the disks–spindle system are derived using a Lagrangian formulation. By introducing constraint equations between the slider and the disk surface, the shock response of the whole HDD system has been obtained. Numerical results show that the method is reasonable and the acceleration amplitude which makes the slider lift off can be determined in a significantly shorter time than by the conventional approach. Finally, the effect of drive parameters on shock resistance, such as shock duration and slider resting location are analyzed.     

Effect of ceria morphology on the catalytic activity of Ru/ceria for the dehydrogenation of ammonia borane

Although the effect of CeO₂ morphology on catalytic properties has been studied, research interests mainly focus on the oxidation reactions while the effect of CeO₂ morphology on other reactions, such as dehydrogenation reaction, has rarely been reported. In this study, the dehydrogenation of ammonia borane (AB) was chosen as a model reaction to study the effect of CeO₂ morphology (“c”, “r” and “o” denote cube, rod, and octahedron, respectively) on the catalytic properties of Ru/CeO₂. Our study shows that the activity follows the order of Ru/c-CeO₂ > Ru/r-CeO₂ > Ru/o-CeO₂, which is different from the order observed in other catalytic oxidation reactions. X-ray photoelectron spectroscopy (XPS), Raman and H₂-Temperature program reduction (H₂-TPR) measurements reveal that there is a weak interaction between Ru and c-CeO₂, and metallic Ru is the dominant species in Ru/c-CeO₂, which are possibly responsible for the highest catalytic activities among three Ru/CeO₂ catalysts.     

The Regulatory Framework Across International Jurisdictions for Risks Associated with Consumption of Botanical Food Supplements

Dietary supplements, including those containing botanical ingredients and botanical‐derived compounds, have been marketed to consumers globally for many decades. However, the legislative framework for such products remains inconsistent across jurisdictions internationally. This study aims to compare the regulatory framework of botanical food supplements in the EU, USA, Canada, Australia, New Zealand, India, Japan, and China. The study also aims to investigate and describe safety assessment criteria for botanical food supplements where they are present in the above said jurisdictions, and attempts to analyze whether these criteria are suitable for addressing the toxicological risks associated with the use of botanical food supplement products, based on the evaluation of reported adverse effects related to botanical food supplement use as examples. Finally, this study discusses some future issues that need further attention, such as the consideration of less than lifetime exposures, potential for misidentification, and adulteration of botanical supplements by pharmacologically active substances. It is concluded that the regulatory approaches towards botanical food supplements differ significantly across jurisdictions. In addition, national authorities are increasingly considering having more regulatory oversight for such products. Further consideration of the actual impact of adverse events arising from botanical food supplement usage will be helpful in guiding such decisions.     

Cosmeceutical Therapy: Engaging the Repercussions of UVR Photoaging on the Skin’s Circadian Rhythm

Sunlight is an important factor in regulating the central circadian rhythm, including the modulation of our sleep/wake cycles. Sunlight had also been discovered to have a prominent influence on our skin’s circadian rhythm. Overexposure or prolonged exposure to the sun can cause skin photodamage, such as the formation of irregular pigmentation, collagen degradation, DNA damage, and even skin cancer. Hence, this review will be looking into the detrimental effects of sunlight on our skin, not only at the aspect of photoaging but also at its impact on the skin’s circadian rhythm. The growing market trend of natural-product-based cosmeceuticals as also caused us to question their potential to modulate the skin’s circadian rhythm. Questions about how the skin’s circadian rhythm could counteract photodamage and how best to maximize its biopotential will be discussed in this article. These discoveries regarding the skin’s circadian rhythm have opened up a completely new level of understanding of our skin’s molecular mechanism and may very well aid cosmeceutical companies, in the near future, to develop better products that not only suppress photoaging but remain effective and relevant throughout the day.