A pH‐Triggered Polymer Degradation or Drug Delivery System by Light‐Mediated Cis / Trans Isomerization of o ‐Hydroxy Cinnamates

A new methodology for the pH-triggered degradation of polymers or for the release of drugs under visible light irradiation based on the cyclization of ortho-hydroxy-cinnamates (oHC) to coumarins is described. The key oHC structural motif can be readily incorporated into the rational design of novel photocleavable polymers via click chemistry. This main-chain moiety undergoes a fast photocleavage when irradiated with 455 nm light provided that a suitable base is added. A series of polyethylene glycol-alt-ortho-hydroxy cinnamate (polyethylene glycol (PEG)n-alt-oHC)-based polymers are synthesized and the time-dependent visible-light initiated cleavage of the photoactive monomer and polymer is investigated in solution by a variety of spectroscopic and chromatographic techniques. The photo-degradation behavior of the water-soluble poly(PEG2000-alt-oHC) is investigated within a broad pH range (pH = 2.1–11.8), demonstrating fast degradation at pH 11.8, while the stability of the polymer is greatly enhanced at pH 2.1. Moreover, the neat polymer shows long-term stability under daylight conditions, thus allowing its storage without special precautions. In addition, two water-soluble PEG-based drug-carrier molecules (mPEG2000-oHC-benzhydrol/phenol) are synthesized and used for drug delivery studies, monitoring the process by UV–vis spectroscopy in an ON/OFF intermittent manner

Growth performance of common carp, Cyprinus carpio fed varying lipid levels through low protein diet, with a note on carcass composition and digestive enzyme activity

Protein sparing by lipid has been demonstrated in certain cultivable species of fish. This study was carried out using four low protein isonitrogenous diets (24% crude protein) formulated by supplementing varied levels of fish oil (0, 3, 6, and 9%). The diets were fed for 120 days at 5% body weight to triplicate groups of common carp (av. wt. 2.13-2.21 g) stocked at 1 per m2 in mud bottomed cement tanks (18 m2), fertilized with poultry manure. The growth of fish was the highest (P 0.05) from that of the control. Survival ranged from 96.29 (T1) to 100% (T0) without any significant (P > 0.05) difference among the treatments. While there was a general increase in amylase activity in the treated fish, protease activity showed a reduction with increase in oil supplementation. No difference (P > 0.05) in lipase activity was observed between the different treatments. The results indicate the beneficial effects of incorporating fish oil in the diet of common carp

Sparse Recovery Methods Hold Promise for Diffuse Optical Tomographic Image Reconstruction

The sparse recovery methods utilize the l(p)-normbased regularization in the estimation problem with 0 <= p <= 1. These methods have a better utility when the number of independent measurements are limited in nature, which is a typical case for diffuse optical tomographic image reconstruction problem. These sparse recovery methods, along with an approximation to utilize the l(0)-norm, have been deployed for the reconstruction of diffuse optical images. Their performancewas compared systematically using both numerical and gelatin phantom cases to show that these methods hold promise in improving the reconstructed image quality

Momordica charantia seed extract exhibits strong anticoagulant effect by specifically interfering in intrinsic pathway of blood coagulation and dissolves fibrin clot

The current study explores the anticoagulant and fibrin clot-hydrolyzing properties of Momordica charantia seed extract (MCSE). MCSE hydrolyzed casein with the specific activity of 0.780 units/mg per min. Interestingly, it enhanced the clot formation process of citrated human plasma from control 146 to 432 s. In addition, the intravenous injection of MCSE significantly prolonged the bleeding time in a dose-dependent manner from control 150 to more than 800 s, and strengthened its anticoagulant activity. Interestingly, MCSE specifically prolonged the clotting time of only activated partial thromboplastin time, but not prothrombin time, and revealed the participation of MCSE in the intrinsic pathway of the blood coagulation cascade. Furthermore, MCSE completely hydrolyzed both A alpha and B beta chains of the human fibrinogen and partially hydrolyzed the gamma chain. However, it hydrolyzed all the chains (alpha polymer, alpha chain, beta chain and gamma-gamma dimmers) of partially cross-linked human fibrin clot. The proteolytic activity followed by the anticoagulant effect of the MCSE was completely abolished by the 1,10-phenanthroline and phenyl methyl sulphonyl fluoride, but iodoacetic acid, EDTA, and ethylene glycol-N, N, N', N'-tetra acetic acid did not. Curiously, MCSE did not hydrolyze any other plasma proteins except the plasma fibrinogen. Moreover, MCSE was devoid of RBC lysis, edema and hemorrhagic properties, suggesting its nontoxic nature. Taken together, MCSE may be a valuable candidate in the treatment of blood clot/thrombotic disorders. Copyright (C) 2015 Wolters Kluwer Health, Inc. All rights reserved

Symmetry-protected dual bound states in the continuum in metamaterials

Bound state in the continuum (BIC) is a mathematical concept with an infinite radiative quality factor (Q) that exists only in an ideal infinite array of resonators. In photonics, it is essential to achieve high Q resonances for enhanced light-mater interactions that could enable low-threshold lasers, ultrasensitive sensors, and optical tweezers. Hence, it is important to explore BICs in different photonic systems including subwavelength metamaterials where symmetry-protected dual BICs exist. The spectral features of dual BICs are experimentally verified in the terahertz domain by breaking the C2 symmetry that invokes a leakage channel in the form of weakly radiating Fano resonance and electromagnetically induced transparency. The radiative Q factors tend to infinity at discrete symmetry-restoring points and obey an inverse square dependence on the structural asymmetry. BICs in metamaterials allow extreme field confinement with small mode volumes, thereby improving the rate of spontaneous emission in the cavity with much larger Purcell factor. In addition, the topological nature enables a robust existence of BICs with a vector beam profile that is ideal for lasing. The symmetry-protected BICs in metamaterials also possess a unique advantage of scalability at different wavelengths for potential applications in sensing, lasing, switching, and spectral filtering.NRF (Natl Research Foundation, S’pore)MOE (Min. of Education, S’pore)Accepted versio

Multi-Institutional Audit of FLASH and Conventional Dosimetry with a 3D-Printed Anatomically Realistic Mouse Phantom.

We conducted a multi-institutional dosimetric audit between FLASH and conventional dose rate (CONV) electron irradiations by using an anatomically realistic 3D-printed mouse phantom. A CT scan of a live mouse was used to create a 3D model of bony anatomy, lungs, and soft tissue. A dual-nozzle 3D printer was used to print the mouse phantom using acrylonitrile butadiene styrene (∼1.02 g/cm &lt;sup&gt;3&lt;/sup&gt; ) and polylactic acid (∼1.24 g/cm &lt;sup&gt;3&lt;/sup&gt; ) simultaneously to simulate soft tissue and bone densities, respectively. The lungs were printed separately using lightweight polylactic acid (∼0.64 g/cm &lt;sup&gt;3&lt;/sup&gt; ). Hounsfield units (HU), densities and print-to-print stability of the phantoms were assessed. Three institutions were each provided a phantom, and each institution performed two replicates of irradiations at selected anatomic regions. The average dose difference between FLASH and CONV dose distributions and deviation from the prescribed dose were measured with radiochromic film. Compared to the reference CT scan, CT scans of the phantom demonstrated mass density differences of 0.10 g/cm &lt;sup&gt;3&lt;/sup&gt; for bone, 0.12 g/cm &lt;sup&gt;3&lt;/sup&gt; for lung, and 0.03 g/cm &lt;sup&gt;3&lt;/sup&gt; for soft tissue regions. Differences in HU between phantoms were &lt;10 HU for soft tissue and bone, with lung showing the most variation (54 HU), but with minimal impact on dose distribution (&lt;0.5%). Mean differences between FLASH and CONV decreased from the first to the second replicate (4.3% to 1.2%), while differences from the prescribed dose decreased for both CONV (3.6% to 2.5%) and FLASH (6.4% to 2.7%). Total dose accuracy suggests consistent pulse dose and pulse number, though these were not specifically assessed. Positioning variability was observed, likely due to the absence of robust positioning aids or image guidance. This study marks the first dosimetric audit for FLASH using a non-homogeneous phantom, challenging conventional calibration practices reliant on homogeneous phantoms. The comparison protocol offers a framework for credentialing multi-institutional studies in FLASH preclinical research to enhance reproducibility of biological findings