Laser oscillation of Er3+:YVO4 and Er3+, Yb3+:YVO4 crystals in the spectral range around 1.6 μm

Laser oscillation around 1.6 μm was realised at room temperature for low-doped Er:YVO₄ crystals (0.5 at % and 1 at %) as well as for Er(1 at %), Yb(5 at %):YVO₄ crystal in continuous-wave mode. The maximum slope of the input–output curve was about 19% (vs. absorbed power) for Er(0.5 at %):YVO₄. The laser oscillation was discretely tunable in the spectral range between 1531 and 1604 nm. Received: 24. August 2000 / Published online: 8 November 2000     

Analysis of Cation-Dependent DNA (G<Subscript>3</Subscript>T<Subscript>1</Subscript>)<Subscript>4</Subscript> Shape Change Using Fluorescence Correlation Spectroscopy

In G-rich DNA, it is well known that the form changes from single-strand DNA to G-quadruplex due to cations. In this study, we analyze the diffusion coefficient and fluorescence intensity obtained by fluorescence correlation spectroscopy for short G-rich DNA of the (G₃T₁)₄ sequence labeled as 5-Carboxytetramethylrhodamine (TAMRA) with variation of the K⁺ ion concentration. At a K⁺ ion concentration of more than 200 mM, the single-strand DNA was changed to the G-quadruplex. The size of the G-quadruplex decreased to 86% than the size of the single strand DNA at K⁺ ion concentration of 0 M. The size of the G-quadruplex and the fluorescence intensity of TAMRA attached to the DNA were constant with an increase in the K⁺ ion concentration between 200 and 800 mM. This means that the size of the DNA and the fluorescence intensity of the TAMRA are not affected by the K⁺ ion concentration at the G-quadruplex structure because the binding structure of DNA and TAMRA dye leads to stability at a concentration of less than 100 mM K⁺. Based on our short G-rich DNA results, longer G-rich DNA is analyzed for the diffusion coefficient of the DNA and the fluorescence intensity variation of fluorescence dye attached to the DNA.     

Analysis of Quantum Rod Diffusion by Polarized Fluorescence Correlation Spectroscopy

To measure the polarization dependence of fluorescent probes, a confocal-microscope-based polarized fluorescence correlation spectroscopy system was developed, and the polarization dependence on the rotational diffusion of well-defined quantum rods (Qrods) was investigated and characterized. The rotational diffusion region of the Qrods was observed over a time range of less than 10^?5 s in a water solution, and the rotational diffusion parameters were extracted using a rotational diffusion model in which the viscosity of the solution media was varied. Our work demonstrated that polarized fluorescence correlation spectroscopy (FCS) is useful for investigating both the rotational and translational diffusion of fluorescent probes.     

The Health-Promoting Properties and Clinical Applications of Rice Bran Arabinoxylan Modified with Shiitake Mushroom Enzyme—A Narrative Review

Rice bran arabinoxylan compound (RBAC) is derived from defatted rice bran hydrolyzed with Lentinus edodes mycelial enzyme. It has been marketed as a functional food and a nutraceutical with health-promoting properties. Some research has demonstrated this rice bran derivative to be a potent immunomodulator, which also possesses anti-inflammatory, antioxidant, and anti-angiogenic properties. To date, research on RBAC has predominantly focused on its immunomodulatory action and application as a complementary therapy for cancer. Nonetheless, the clinical applications of RBAC can extend beyond cancer therapy. This article is a narrative review of the research on the potential benefits of RBAC for cancer and other health conditions based on the available literature. RBAC research has shown it to be useful as a complementary treatment for cancer and human immunodeficiency virus infection. It can positively modulate serum glucose, lipid and protein metabolism in diabetic patients. Additionally, RBAC has been shown to ameliorate irritable bowel syndrome and protect against liver injury caused by hepatitis or nonalcoholic fatty liver disease. It can potentially ease symptoms in chronic fatigue syndrome and prevent the common cold. RBAC is safe to consume and has no known side effects at the typical dosage of 2–3 g/day. Nevertheless, further research in both basic studies and human clinical trials are required to investigate the clinical applications, mechanisms, and effects of RBAC.     

High‐performance liquid chromatographic method for the quantification of Mitragyna inermis alkaloids in order to perform pharmacokinetic studies

In Africa, Mitragyna inermis (Willd.) O. Kuntze (Rubiaceae) is commonly used in traditional medicine to treat malaria. Antimalarial activity is mostly due to the hydromethanolic extract of M. inermis leaves and especially to the main alkaloids, uncarine D and isorhynchophilline. In the present study, we describe for the first time an HPLC method for the simultaneous quantification of uncarine D and isorhynchophylline in biological matrices. SPE was used to extract the components and the internal standard naphthalene from human and pig plasma samples. Chromatographic separation was performed on a C‐18 reversed column at a flow rate of 1 mL/min, using methanol–phosphate buffer (10:90, pH 7), as a mobile phase. Good linearity was observed over the concentration ranges of 0.0662–3.31 μg/mL for uncarine D and 0.0476–2.38 μg/mL for isorynchophylline. The precision was less than 12% and the accuracy was from 86 to 107% without any discrepancy between the two species. Uncarine D and isorhynchophylline recoveries were over 80%. These results allowed the quantification of both uncarine D and isorhynchophylline in pig plasma after intravenous administration of M. inermis extract.     

The univalence of α‐project starlike functions

We solve the univalence problem in the class of α‐project starlike function. The α‐project close‐to‐convex function, α‐project Bazilevi? and α‐project Φ‐like functions are also considered here.     

A Micellar Multitasking Device: Sensing pH Windows and Gauging the Lipophilicity of Drugs with Fluorescent Signals

A multitasking fluorescent device can be obtained by forming micelles of Triton X‐100, containing a lipophilic macrocyclic Cu²⁺ complex and the coordinating fluorophore Coumarin 343 (C343), which features a COOH moiety. At low pH the two micellised components do not interact, and the fluorescence of Courmarin 343 (C343) is intense. At intermediate pH, C343 is deprotonated and coordinates to the Cu²⁺ centre in its apical position, with fluorescence quenching. At higher pH the deprotonated C343 is displaced from Cu²⁺ by the formation of an OH^? complex, and the fluorescence is revived. This allows the system to carry out its first task as it behaves as an “on–off–on” fluorescent sensor for pH windows. The “off” part of the window ranges from pH 6 to 8. In this interval, in which the carboxylate form of C343 is apically coordinated to the Cu²⁺ complex inside micelles, the device carries out its second task, that is, it behaves as a gauge for lipophilicity. For pHs between 6 and 8, molecules containing a COOH group are in their COO^? form and distribute between bulk water and micelles proportionally to their lipophilicity. Upon entering the micelle, their COO^? moiety competes for coordination with C343, displacing it from the Cu²⁺ centre, and this results in fluorescence revival, the intensity of which is also proportional to the lipophilicity of the examined molecule. We have chosen the physiological pH value (7.4) as the working pH, and we have examined the lipophilicity of fatty acids and of the widely used family of non‐steroidal anti‐inflammatory drugs (NSAIDs). The device successfully measures their lipophilicity, expressing it with an “off–on” type fluorescent signal, as demonstrated by the correlation of the fluorescence increase with the logarithmic water/octanol partition coefficient (log P) and with the difference between the pK_a observed in micelles and that measured in water for NSAIDs.     

Light radiation through a transparent cathode plate with single-walled carbon nanotube field emitters

In the conventional carbon nanotube backlight units (CNT-BLUs), light passes through the phosphor-coated anode glass plate, which thus faces closely the thin film transistor (TFT) backplate of a liquid crystal display panel. This configuration makes heat dissipation structurally difficult because light emission and heat generation occur simultaneously at the anode. We propose a novel configuration of a CNT-BLU where the cathode rather than the anode faces the TFT backplate by turning it upside down. In this design, light passes through the transparent cathode glass plate while heating occurs at the anode. We demonstrated a novel design of CNT-BLU by fabricating transparent single-walled CNT field emitters on the cathode and by coating a reflecting metal layer on the anode. This study hopefully provides a clue to solve the anode-heating problem which would be inevitably confronted for high-luminance and large-area CNT-BLUs.     

Graph coloring and Graham’s greatest common divisor problem

In this paper we introduce and study two graph coloring problems and relate them to some deep number-theoretic problems. For a fixed positive integer $k$ consider a graph $B_k$ whose vertex set is the set of all positive integers with two vertices $a,b$ joined by an edge whenever the two numbers $a∕gcd(a,b)$ and $b∕gcd(a,b)$ are both at most $k$. We conjecture that the chromatic number of every such graph $B_k$ is equal to $k$. This would generalize the greatest common divisor problem of Graham from 1970; in graph-theoretic terminology it states that the clique number of $B_k$ is equal to $k$. Our conjecture is connected to integer lattice tilings and partial Latin squares completions.