Published Date 20 October 2015, Vol.131:134–141,doi:10.1016/j.carbpol.2015.05.060 Title Synthesis of surface bound silver nanoparticles on cellulose fibers using lignin as multi-functional agent
Author
Sixiao Hu
You-Lo Hsieh,
Fiber and Polymer Science, University of California-Davis, One Shields Avenue, Davis, CA 95616, United States
Received 15 April 2015. Revised 12 May 2015. Accepted 13 May 2015. Available online 4 June 2015. Highlights . Silver nanoparticles were synthesized and robustly bound on cellulose nanofibers. . Lignin was used as multifunctional complexing, reducing and capping agents. . The enhanced thermal stability of silver nanoparticles were achieved. . UV-absorbing ability of cellulose nanofibers were gained. . The nanoparticles bound celluloses showed excellent antimicrobial activities towardE.-coli. Abstract Lignin has proven to be highly effective “green” multi-functional binding, complexing and reducing agents for silver cations as well as capping agents for the synthesis of silver nanoparticles on ultra-fine cellulose fibrous membranes. Silver nanoparticles could be synthesized in 10 min to be densely distributed and stably bound on the cellulose fiber surfaces at up to 2.9% in mass. Silver nanoparticle increased in sizes from 5 to 100 nm and became more polydispersed in size distribution on larger fibers and with longer synthesis time. These cellulose fiber bound silver nanoparticles did not agglomerate under elevated temperatures and showed improved thermal stability. The presence of alkali lignin conferred moderate UV absorbing ability in both UV-B and UV-C regions whereas the bound silver nanoparticles exhibited excellent antibacterial activities towardEscherichia coli. Graphical abstract
Published Date January 2016, Vol.82:856–862,doi:10.1016/j.ijbiomac.2015.09.066 Title Silver nanoparticle synthesis using lignin as reducing and capping agents: A kinetic and mechanistic study
Author
Sixiao Hu
You-Lo Hsieh
Abstract
Silver nanoparticles (AgNPs) were robustly synthesized from aqueous AgNO3with alkali lignin (low sulfonate) (ALls) severing as dual reducing and capping agent. The AgNP synthesis mechanisms were highly pH dependent. Under neutral and acidic conditions, polydispersed AgNPs were synthesized via the self-catalyzed reduction of Ag+on instantaneously formed Ag2O surfaces followed by the slower pseudo-first order reduction. The Ag2O nanoparticles functioned as the nucleating sites for the reduction of remaining silver cations to form AgNPs whose size and size distribution strongly dependent of lignin concentrations. AgNPs were optimally synthesized by reducing 2 mmol/L AgNO3with 0.16 wt% ALlsat pH 10 and 85 °C in 30 min to near 100% yield in bimodal distributed sizes with 23% and 77% in feret diameters of 7.3 (±2.2) nm and 14.3 (±1.8) nm, respectively.
Published Date January 2016, Vol.82:39–47,doi:10.1016/j.ijbiomac.2015.09.072 Title Hydrogen peroxide sensing and cytotoxicity activity ofAcacialignin stabilized silver nanoparticles
Author
Keshaw Ram Aadil a
Anand Barapatre a
Avtar Singh Meena b
Harit Jha a,,
aDepartment of Biotechnology, Guru Ghasidas Vishwavidyalaya (Central University), Bilaspur 495009, Chhattisgarh, India
bTumor Biology Laboratory, National Institute of Pathology, New Delhi 110029, India
Received 26 February 2015. Revised 13 June 2015. Accepted 29 September 2015. Available online 3 October 2015. Highlights . Study reported the detection of H2O2usingAcacialignin mediated silver nanoparticles. . One step method for the synthesis of AGNPs was developed. . Sensing properties of AGNPs toward hydrogen peroxide were investigated. . Lignin mediated AGNPs demonstrated toxicity effects in MCF-7 and A375 cell lines. Abstract The study is aimed at detection of hydrogen peroxide (H2O2) usingAcacialignin mediated silver nanoparticles (AGNPs). The synthesis of AGNPs was achieved at conditions optimized as, 3 ml of 0.02% lignin and 1 mM silver nitrate incubated for 30 min at 80 °C and pH 9. Initial screening of AGNPs was performed by measuring the surface plasmon resonance peak at 410–430 nm using UV–vis spectrophotometer. Transmission electron microscopy, atomic force microscopy, X-ray diffraction and particle size analysis confirmed the spherical shaped face centered cubic structure and 10–50 nm size of AGNPs. The infrared spectroscopy study further revealed that the active functional groups present in lignin were responsible for the reduction of silver ions (Ag+) to metallic silver (Ag0). Lignin stabilized silver nanoparticles showed good sensitivity and a linear response over wide concentrations of H2O2(10−1to 10−6M). Further, thein vitrocytotoxicity activity of the lignin mediated AGNPs (5–500 μg/ml) demonstrated toxicity effects in MCF-7 and A375 cell lines. Thus, lignin stabilized silver nanoparticles based optical sensor for H2O2could be potentially applied in the determination of reactive oxygen species and toxic chemicals which further expands the importance of lignin stabilized silver nanoparticles.
A man and woman are walking together.Photo Credit RK Studio/Blend Images/Getty Images
Walking can improve your overall health in a number of ways. It benefits your entire body by increasing your heart and breathing rate in an efficient, low-effort way. Walking at any level provides health benefits, but optimum cardiovascular benefits occur by working at a moderately brisk level for 30 minutes on five or more days weekly. Check with your doctor first, since walking may not be for you.
Your Cardiovascular Systm
Walking strengthens your cardiovascular system and its functioning. Your cardiovascular system consists of your heart, arteries and blood pathways. Engaging in cardiovascular activities, such as walking, for only 30 minutes daily can reduce the risk of heart disease, according to the American Heart Association. If walking 30 minutes each time proves time-consuming, divide your workout into 10-minute increments. Alternatively, wear a pedometer that keeps track of your steps throughout the day. When you reach 10,000 steps, you will walked the equivalent of 30 minutes. Walking at a moderately brisk level or higher can improve your cholesterol profile by lowering harmful cholesterol and increasing beneficial cholesterol. A healthy cholesterol profile lowers your risks of developing heart disease, according to the American Heart
Improving Your Musculoskeletal System
Your musculoskeletal system consists of your body's bones and muscles. Walking benefits your musculoskeletal system in a variety of ways. It provides a low-impact activity that strengthens bones without placing too much stress upon the skeletal system. This proves especially beneficial for recuperating surgical patients or individuals afflicted with joint concerns or mobility issues such as arthritis. Walking increases bone density, which lowers risks of developing the weakened bone condition known as osteoporosis.
Reducing Body Fat
Walking burns calories and can play a major role in weight management and weight loss. Walking one mile at a moderately brisk rate burns 100 calories, according to an article by Martina Navratilova in "AARP Magazine." When done on a consistent basis, walking can help you lose weight. Lower weight means less abdominal fat and a lower risk of developing cardiovascular conditions.
Improving Your Mental Outlook
Walking improves your mental outlook. As a form of cardiovascular, or aerobic, exercise, walking releases endorphins. Endorphins provide an enhanced feeling of overall well-being while lowering stress levels, both physically and emotionally. Physically, lower stress levels reduce muscle soreness, high blood pressure, pain and tightness, and they promote healing. Emotionally, lower stress levels reduce your risks of depression as well as negative mindsets such as impatience, feeling out of control, anger, feelings of hopelessness, pessimism and isolation. Walking can also improve your independence and self-confidence levels.
Title Compatibilizing role of carbon nanotubes in poly(vinyl alcohol)/starch blend KAUST Repository Author Jose, Jobin Vinodh Published Date 2014-10-03 Abstract Polymer nanocomposites based onpoly(vinylalcohol)/starchblendand carbon nanotubes (CNT) were prepared by solution mixing, followed by casting. Glycerol was used as a plasticizer and added in the starch dispersion. The uniform dispersion of CNT in water before mixing with PVA/starchblend, was achieved by using an Ultrasonicator probe. The composites were characterized by measurement of tensile properties, thermal analysis, FE-SEM, TEM, XRD studies, and water uptake. It was observed that the decrease in tensile strength, modulus, and elongation at break on addition of starch into PVA can be arrested by incorporation of CNT. The strong physical bonding such as hydrogen bonding among the hydroxyl groups of polymer components and oxygen containing groups on CNT surface resulted in a more tortuous path for the water to follow, lowering of water uptake. Thermal analysis and spectroscopic images showed an increase inblend homogeneity in the presence of CNT. For further details log on website : http://worldwidescience.org/topicpages/p/polyvinyl+alcohol-polyacrylamide+blends.html
When faced with a stressful situation, the human body responds with the fight-or-flight response. The sympathetic nervous system reacts, resulting in symptoms such as a racing heart beat and increased sweating. After the stress goes away, the parasympathetic nervous system activates, returning the body to normal. Certain events cause high levels of stress in people, such as major life changes. A woman is standing behind a stack of papers.Photo Credit Jupiterimages/Stockbyte/Getty Images.
Work
A person's job can be a source of stress, especially because of the amount of time spent there each week. The Mayo Clinic states that an overwhelming workload or a difficult boss can increase the level of stress. If a person does not like her job, has a long commute or has altercations with her co-workers, she can experience even more stress. Helpguide.org notes that on the Holmes-Rahe Life Stress Inventory, getting fired from a job is the eighth most stressful life event.
Life Changes
Certain major changes in a patient's life can cause large amount of stress. The Mayo Clinic notes that both positive life changes, such as a pregnancy, and negative life changes, such as the death of a loved one, can result in stress. The death of a spouse is the most stressful life event on the Holmes-Rahe Life Stress Inventory, and the death of a close relative is the fifth. While a positive event for many people, retirement is considered the tenth most stressful event.
Environment
Some environmental factors can cause or add to a person's life of stress. Mayo Clinic notes that two environmental factors, noise and excessive light, can induce stress. These environmental stressors can be worse if they are not controllable.
Self-Generated
Stress also can be caused by a person's inner thinking. For example, unrealistic expectations and perfectionism can make events in which a person did not realize his ideals even more stressful. Pessimism and negative self-talk also can cause stress.
CAMBIAL GROWTH PERIODICITY STUDIES OF SOUTH AMERICAN WOODY SPECIES – A REVIEW
Authors: Cátia Henriques Callado; Fidel Alejandro Roig; Mário Tomazello-Filho and Claudia Franca Barros
Source:IAWA Journal,Volume 34, Issue 3,pages213 – 230 Publication Year :2013
DOI: 10.1163/22941932-00000019
ISSN: 0928-1541 E-ISSN: 2294-1932
Abstract
This paper reviews histological studies of cambium activity in South American woody species and provides future research prospects. The majority of the studies almost exclusively describe radial increment and/or its periodicity. There are 15 papers concerning the cambial activity of 17 woody species from the South American flora and 3 exotic species in 4 countries that were published to date. Despite endogenous factors affecting the radial meristem, the seasonality of rains has been identified as the main factor influencing cambial activity in the tropics and subtropics. There is a lack of standardization and a need for improvement and discussion concerning the methods used. Moreover, radial growth studies conducted by monitoring cambium cell production are still scarce in South America, especially when considering the high diversity of the continent’s flora and ecosystems.
