Improved Decoding of Expander Codes

We study the classical expander codes, introduced by Sipser and Spielman [M. Sipser and D. A. Spielman, 1996]. Given any constants 0 < ?, ? < 1/2, and an arbitrary bipartite graph with N vertices on the left, M < N vertices on the right, and left degree D such that any left subset S of size at most ? N has at least (1-?)|S|D neighbors, we show that the corresponding linear code given by parity checks on the right has distance at least roughly {? N}/{2 ?}. This is strictly better than the best known previous result of 2(1-?) ? N [Madhu Sudan, 2000; Viderman, 2013] whenever ? < 1/2, and improves the previous result significantly when ? is small. Furthermore, we show that this distance is tight in general, thus providing a complete characterization of the distance of general expander codes. Next, we provide several efficient decoding algorithms, which vastly improve previous results in terms of the fraction of errors corrected, whenever ? < 1/4. Finally, we also give a bound on the list-decoding radius of general expander codes, which beats the classical Johnson bound in certain situations (e.g., when the graph is almost regular and the code has a high rate). Our techniques exploit novel combinatorial properties of bipartite expander graphs. In particular, we establish a new size-expansion tradeoff, which may be of independent interests

Enhanced production of bacterial cellulose by using a biofilm reactor and its material property analysis

Bacterial cellulose has been used in the food industry for applications such as low-calorie desserts, salads, and fabricated foods. It has also been used in the paper manufacturing industry to enhance paper strength, the electronics industry in acoustic diaphragms for audio speakers, the pharmaceutical industry as filtration membranes, and in the medical field as wound dressing and artificial skin material. In this study, different types of plastic composite support (PCS) were implemented separately within a fermentation medium in order to enhance bacterial cellulose (BC) production by Acetobacter xylinum. The optimal composition of nutritious compounds in PCS was chosen based on the amount of BC produced. The selected PCS was implemented within a bioreactor to examine the effects on BC production in a batch fermentation. The produced BC was analyzed using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA), and dynamic mechanical analysis (DMA). Among thirteen types of PCS, the type SFYR+ was selected as solid support for BC production by A. xylinum in a batch biofilm reactor due to its high nitrogen content, moderate nitrogen leaching rate, and sufficient biomass attached on PCS. The PCS biofilm reactor yielded BC production (7.05 g/L) that was 2.5-fold greater than the control (2.82 g/L). The XRD results indicated that the PCS-grown BC exhibited higher crystallinity (93%) and similar crystal size (5.2 nm) to the control. FESEM results showed the attachment of A. xylinum on PCS, producing an interweaving BC product. TGA results demonstrated that PCS-grown BC had about 95% water retention ability, which was lower than BC produced within suspended-cell reactor. PCS-grown BC also exhibited higher Tmax compared to the control. Finally, DMA results showed that BC from the PCS biofilm reactor increased its mechanical property values, i.e., stress at break and Young's modulus when compared to the control BC. The results clearly demonstrated that implementation of PCS within agitated fermentation enhanced BC production and improved its mechanical properties and thermal stability

Lignocellulose-based analytical devices: bamboo as an analytical platform for chemical detection

This article describes the development of lignocellulose-based analytical devices (LADs) for rapid bioanalysis in low-resource settings. LADs are constructed using either a single lignocellulose or a hybrid design consisting of multiple types of lignocellulose. LADs are simple, low-cost, easy to use, provide rapid response, and do not require external instrumentation during operation. Here, we demonstrate the implementation of LADs for food and water safety (i.e., nitrite assay in hot-pot soup, bacterial detection in water, and resazurin assay in milk) and urinalysis (i.e., nitrite, urobilinogen, and pH assays in human urine). Notably, we created a unique approach using simple chemicals to achieve sensitivity similar to that of commercially available immunochromatographic strips that is low-cost, and provides on-site, rapid detection, for instance, of Eschericia coli (E. coli) in water

Antioksidativna i citotoksična aktivnost ekstrakata mlijeka proizvedenog iz fermentirane crne soje

In this study, ethanol extracts from 2-day fermented black soybean milk (FBE) by immobilized Rhizopus oligosporus NTU5 have been evaluated for both antioxidant and cytotoxic activities. The results reveal that a 2-day FBE had strong 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging effect (76 %). The extracts were further fractionated by silica gel column chromatography and an unknown compound, FBE5-A, was obtained, which exhibited strong antioxidant activity. IC50 of the DPPH scavenging effect of FBE5-A was 7.5 μg/mL, which is stronger than a commonly used antioxidant, vitamin E (α-tocopherol; 17.4 μg/mL), and similar to vitamin C (ascorbic acid; 7.6 μg/mL). The cytotoxic test demonstrated that extracts of 2-day fermented broth exhibited selective cytotoxic activity towards human carcinoma cells, Hep 3B (IC50=150.2 μg/mL), and did not affect normal human lung fibroblasts, MRC-5 (p<0.05). The results indicate the potential applications of fermented black soybean milk as functional food, pharmaceutical or cancer therapy formula.U radu je ispitana antioksidativna i citotoksična aktivnost etanolnih esktrakata mlijeka dobivenog nakon 2 dana fermentacije crne soje pomoću imobiliziranoga soja Rhizopus oligosporus NTU5. Rezultati su pokazali da takvo mlijeko ima izraženu sposobnost uklanjanja slobodnih DPPH radikala (76 %). Ekstrakti su mlijeka zatim frakcionirani kromatografijom na silikagelu i izdvojen je nepoznati sastojak, nazvan FBE5-A, izraženog antioksidativnog svojstva. Sposobnost toga sastojka da uklanja slobodne DPPH radikale kudikamo je veća (IC50=7,5 μg/mL) nego vitamina E, koji se obično koristi kao antioksidans (α-tokoferol, IC50=17,4 μg/mL) i približno jednaka vitaminu C (askorbinska kiselina, IC50=7,6 μg/mL). Ispitivanje citotoksičnog učinka FBE5-A pokazalo je da selektivno djeluje na ljudske stanice raka Hep 3B (IC50=150,2 μg/mL), a pritom ne utječe na normalne fibroblaste iz pluća MRC-5 (p<0,05). Rezultati upućuju na to da se mlijeko dobiveno fermentacijom crne soje može upotrijebiti kao funkcionalna hrana i za liječenje raznih bolesti, uključujući i rak

FFTPL: An Analytic Placement Algorithm Using Fast Fourier Transform for Density Equalization

We propose a flat nonlinear placement algorithm FFTPL using fast Fourier transform for density equalization. The placement instance is modeled as an electrostatic system with the analogy of density cost to the potential energy. A well-defined Poisson's equation is proposed for gradient and cost computation. Our placer outperforms state-of-the-art placers with better solution quality and efficiency

Ginseng essence, a medicinal and edible herbal formulation, ameliorates carbon tetrachloride-induced oxidative stress and liver injury in rats

AbstractBackgroundGinseng essence (GE) is a formulation comprising four medicinal and edible herbs including ginseng (Panax ginseng), American ginseng (Panax quinquefolius), lotus seed (Nelumbo nucifera), and lily bulb (Lilium longiflorum). This study was aimed at investigating the hepatoprotective effect of GE against carbon tetrachloride (CCl4)-induced liver injury in rats.MethodsWe treated Wistar rats daily with low, medium, and high [0.625 g/kg body weight (bw), 1.25 g/kg bw, and 3.125 g/kg bw, respectively] doses of GE for 9 wk. After the 1st wk of treatment, rats were administered 20% CCl4 (1.5 mL/kg bw) two times a week to induce liver damage until the treatment ended.ResultsSerum biochemical analysis indicated that GE ameliorated the elevation of aspartate aminotransferase and alanine aminotransferase and albumin decline in CCl4-treated rats. Moreover, CCl4-induced accumulation of hepatic total cholesterol and triglyceride was inhibited. The hepatoprotective effects of GE involved enhancing the hepatic antioxidant defense system including glutathione, glutathione peroxidase, glutathione reductase, glutathione S-transferase, superoxide dismutase, and catalase. In addition, histological analysis using hematoxylin and eosin and Masson's trichrome staining showed that GE inhibited CCl4-induced hepatic inflammation and fibrosis. Furthermore, immunohistochemical staining of alpha-smooth muscle actin indicated that CCl4-triggered activation of hepatic stellate cells was reduced.ConclusionThese findings demonstrate that GE improves CCl4-induced liver inflammation and fibrosis by attenuating oxidative stress. Therefore, GE could be a promising hepatoprotective herbal formulation for future development of phytotherapy