My Child Is Unable to Show Empathy

Empathy -- the ability to feel for others and mentally put yourself in their place -- develops as a child ages. Because empathy is learned, you as a parent can help foster empathetic behavior and understanding. At certain ages, a lack of empathy is a perfectly normal developmental trait. If your child continues to lack empathy as he gets older, talk to his doctor for an opinion on whether or not this is normal at his age.

Parent speaking with child. Photo Credit Plush Studios/Blend Images/Getty Images

Age of the Child

It's unrealistic to expect a child under age 5 to truly empathize with others; a child this young doesn't yet have the ability to put himself in another person's shoes. True empathy for others normally doesn't start to blossom until age 8 or 9, according to the BabyCenter website. If your child shows no signs of empathy for others by this age or doesn't appear to understand why you find his lack of empathy concerning, he may have a psychological issue blocking his understanding.

Contributing Factors

Child with attention deficit hyperactivity disorder may have a difficult time understanding empathy. Children who are overwhelmed with too many emotional feelings from parents and caregivers may also have trouble developing empathy for others, child psychiatrist Dr. Liane Leedom explains. Children with personality disorders such as narcissism, borderline personality disorder and antisocial personality disorder may have a difficult time understanding empathy. Children with addiction issues can also lack empathy for others, according to Leedom.

Developing Empathy

You can and should participate in the process of developing empathy in your child. Even if your child is very young, you can talk to her about how nice it is to help others. While a child age 2 or 3 won't understand exactly why this makes her feel good, you can foster the pride she feels when she brings the baby a toy or comforts a crying friend. By age 5, present hypothetical situations to your child, asking how she imagines a friend would feel if someone laughed at her mistakes or made fun of her. Give your child the words for the feelings she expresses -- tell her she looks sad, is acting grumpy or looked very excited about a new toy. Model empathy and praise behaviors that show empathy toward others.

Danger Signs

Lack of empathy in the preteen or teenager can be one warning sign of a psychiatric disorder. Other signs that should lead concerned parents to look for medical help and guidance include cruelty to animals, fire-setting, frequent lying, petty thievery, defiance, bullying others, aggressive behavior, unresponsiveness to punishment and lack or remorse. Talk to your doctor if you notice these signs in your child. Consider asking for a referral to see a mental health provider or family therapist.

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Modeling particle population balances in fluidized-bed wood gasifiers.

Title

Modeling particle population balances in fluidized-bed wood gasifiers.

Authors

Natale, G.; Galgano, A.; Blasi, C. di

Journal

Biomass and Bioenergy 2014 Vol. 62 pp. 123-137

ISSN

0961-9534

DOI

10.1016/j.biombioe.2014.01.006

Abstract

An unsteady model is developed for the particle size distribution in fluidized-bed reactors including fragmentation, abrasion, elutriation and the chemical reactions of wood gasification. Based on the assumption of constant conditions (gas composition, temperature, velocity) of the surrounding atmosphere, an analytical solution is developed for the distribution of sizes belonging to the classes of mother and fine particles. It is found that for the typical feed sizes (minimum above 3×10^-2 mm) and the usual maximum size of fine particles (2.4×10^-3 mm), the behavior of fine particles is quasi-steady with respect to mother particles. The numerical solution of the quasi-steady formulation of particle population balances is also coupled with a two-phase (bubble and emulsion), three-zone (bed, splash zone and freeboard) model for a bubbling fluidized-bed reactor, giving predictions of the producer gas composition in agreement with measurements for air gasification of wood.


For further details log on website :

http://cabdirect.cab.semcs.net/abstracts/20143139304.html?start=56800

Managing chipper knife wear to increase chip quality and reduce chipping cost.

Title

Managing chipper knife wear to increase chip quality and reduce chipping cost.

Authors

Spinelli, R.; Glushkov S.,; Markov,I.

Journal

Biomass and Bioenergy 2014 Vol. 62 pp. 117-122

ISSN

0961-9534

DOI

10.1016/j.biombioe.2014.01.007

Abstract

Wood biomass is turned into industrial fuel through chipping. The efficiency of chipping depends on many factors, including chipper knife wear. Chipper knife wear was determined through a long-term follow-up study, conducted at a waste wood recycling yard. Knife wear determined a sharp drop of productivity (>20%) and a severe decay in product quality. Dry sharpening with a grinder mitigated this effect, but it could not replace proper wet sharpening. Increasing the frequency of wet sharpening sessions determined a moderate increase of knife depreciation cost, but it could drastically enhance machine performance and reduce biomass processing cost. Since benefits largely exceed costs, increasing the frequency of wet sharpening sessions may be an effective measure for reducing overall chipping cost. If the main goal of a chipper operator is to increase productivity and/or decrease fuel consumption, then managing knife wear should be a primary target.


For further details log on website :

http://cabdirect.cab.semcs.net/abstracts/20143139303.html;jsessionid=3397FE2033BC7799A4AECCAF7E1A9D9B?start=56800

Why Can't I Take Melatonin Because I Have an Autoimmune Disease?

Melatonin is a neurohormone produced by the pineal gland at the base of your brain. Its release is enhanced when you are in darkness and suppressed when you are exposed to bright light. By stimulating receptors in specific areas of your brain, melatonin helps establish your diurnal rhythm and determine your sleep cycles. The April 2011 issue of "Archives of Oral Biology" reports that melatonin also acts as an antioxidant, an anti-inflammatory, a stimulator of bone growth and an immune-regulating hormone.

Melatonin could make some inflammatory conditions worse. Photo Credit Proud to be American image by painless from Fotolia.com

Autoimmunity

According to "The Merck Manual of Diagnosis and Therapy," autoimmune disorders occur when your immune system produces antibodies that are directed against your own tissues. When these so-called autoantibodies attack your cells or tissues, they trigger an inflammatory response that can cause widespread damage. Components of this abnormal immune response include white blood cells and the inflammatory chemicals they produce, such as cytokines and prostaglandins.

Neuroendocrine Immune System

Your immune system is regulated by a multitude of internal and external forces. A 2009 review in "Arthritis Research and Therapy" states that an imbalance between your immune system and several of your hormones, such as vitamin D, melatonin, cortisol and sex hormones, is one of the primary driving forces behind a variety of diseases, including many autoimmune disorders. The interaction between your hormones and your immune system is called the neuroendocrine immune system, or NEI.

Suppression

Among the various hormones involved in the NEI, some act to heighten your immune response, while others help to suppress it. Under normal circumstances, these opposing forces allow your immune system to efficiently address threats without causing injury to your own tissues. Cortisol and vitamin D have been shown to exert suppressing effects on the immune response, making them desirable agents for treating conditions where your immune system is overactive, such as autoimmune disorders.

Activation

In spite of melatonin's antioxidant properties, it has demonstrated a tendency to stimulate inflammation in patients with certain autoimmune disorders. A study published in the October 2007 issue of "British Journal of Clinical Pharmacology" demonstrated that rheumatoid arthritis actually worsened in study subjects who took melatonin. This finding both surprised and disappointed the study's authors, whose original hypothesis centered on the potential benefit from using melatonin to treat autoimmune diseases. However, these results mirrored those of other studies, which showed that melatonin stimulated immune cells to release inflammatory cytokines.

Considerations

The interactions among immune cells, hormones and your nervous system -- the NEI -- are complex. Some previously observed properties of melatonin, such as its antioxidant activity, have not been borne out in all clinical studies. This has led some experts to recommend that you not use melatonin if you have an autoimmune disease, since it could aggravate your already overactive immune system and lead to a worsening of your symptoms.

www.livestrong.com

5 Things You Need to Know About Melatonin

A little girl asleep with her stuffed animal. Photo Credit Lisa5201/iStock/Getty Images

Melatonin is a hormone produced by the pineal gland, which is located at the base of the brain. Melatonin may play a role in helping your body go to sleep at night and wake up in the morning. It may also aid in keeping your body's circadian rhythm, which is basically your body's natural clock. Your melatonin levels can decrease as you age, which could make it more difficult for you to sleep as you get older.

Melatonin is a hormone produced by the pineal gland, which is located at the base of the brain. Melatonin may play a role in helping your body go to sleep at night and wake up in the morning. It may also aid in keeping your body's circadian rhythm, which is basically your body's natural clock. Your melatonin levels can decrease as you age, which could make it more difficult for you to sleep as you get older.

www.livestrong.com

Cellulose Nanocrystals/ZnO as a Bifunctional Reinforcing Nanocomposite for Poly(vinyl alcohol)/Chitosan Blend Films: Fabrication, Characterization and Properties

Title

Cellulose Nanocrystals/ZnO as a Bifunctional Reinforcing Nanocomposite for Poly(vinyl alcohol)/Chitosan Blend Films: Fabrication, Characterization and Properties

Author 
Susan Azizi 1,* ,  Mansor B. Ahmad 1,* ,  Nor Azowa Ibrahim 1,4

,Mohd Zobir Hussein 2 and   Farideh Namvar 3,4

1 Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia

2 Materials Synthesis and Characterization Laboratory, Institute of Advanced Technology, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia

3 Institute of Tropical Forestry and Forest Products, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia

4 Mashhad Branch, Islamic Azad University, Mashhad 9187147578, Iran

* Authors to whom correspondence should be addressed. 

Received: 4 April 2014 / Revised: 14 May 2014 / Accepted: 26 May 2014 / Published: 18 June 2014

Abstract

In this study, cellulose nanocrystals/zinc oxide (CNCs/ZnO) nanocomposites were dispersed as bifunctional nano-sized fillers into poly(vinyl alcohol) (PVA) and chitosan (Cs) blend by a solvent casting method to prepare PVA/Cs/CNCs/ZnO bio-nanocomposites films. The morphology, thermal, mechanical and UV-vis absorption properties, as well antimicrobial effects of the bio-nanocomposite films were investigated. It demonstrated that CNCs/ZnO were compatible with PVA/Cs and dispersed homogeneously in the polymer blend matrix. CNCs/ZnO improved tensile strength and modulus of PVA/Cs significantly. Tensile strength and modulus of bio-nanocomposite films increased from 55.0 to 153.2 MPa and from 395 to 932 MPa, respectively with increasing nano-sized filler amount from 0 to 5.0 wt %. The thermal stability of PVA/Cs was also enhanced at 1.0 wt % CNCs/ZnO loading. UV light can be efficiently absorbed by incorporating ZnO nanoparticles into a PVA/Cs matrix, signifying that these bio-nanocomposite films show good UV-shielding effects. Moreover, the biocomposites films showed antibacterial activity toward the bacterial species Salmonella choleraesuis and Staphylococcus aureus. The improved physical properties obtained by incorporating CNCs/ZnO can be useful in variety uses.

For further details log on website :

http://www.mdpi.com/1422-0067/15/6/11040?trendmd-shared=0

Physical Properties, Antioxidant and Antimicrobial Activity of Chitosan Films Containing Carvacrol and Pomegranate Peel Extract

Title

Physical Properties, Antioxidant and Antimicrobial Activity of Chitosan Films Containing Carvacrol and Pomegranate Peel Extract 

Author ,  
Gaofeng Yuan 1,2, Hua Lv 2, Bingjie Yang 2,  Xiaoe Chen 1,2 and Haiyan Sun 1,2,* 

1 Key Laboratory of Health Risk Factors for Seafood of Zhejiang Province, Zhejiang Ocean University, Zhoushan 316022, China

2 College of Food and Medicine, Zhejiang Ocean University, Zhoushan, Zhejiang 316022, China

* Author to whom correspondence should be addressed. 

Academic Editor: Derek J. McPhee

Received: 4 May 2015 / Revised: 8 June 2015 / Accepted: 9 June 2015 / Published: 15 June 2015

Abstract

Chitosan-based active films were developed by incorporation of carvacrol (10 g/L), pomegranate peel extract (PPE, 10 g/L) and carvacrol + PPE (10 g/L of each) and their physical, antioxidant and antimicrobial properties were investigated. Incorporation of carvacrol and carvacrol + PPE into the films significantly decreased the water vapor permeability, tensile strength and percentage of elongation at break. Incorporation of carvacrol, PPE and carvacrol + PPE into the films decreased the transparency, but significantly increased the total phenol content and antioxidant activity. All the films, with the exception of PPE-incorporated film, exhibited antibacterial activity against Escherichia coli and Staphylococcus aureus. In addition, the antibacterial activity against Staphylococcus aureus of the film incorporated with carvacrol + PPE was moderately higher than that incorporated with carvacrol or PPE alone, suggesting a synergistic action between carvacrol and PPE.

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http://www.mdpi.com/1420-3049/20/6/11034?trendmd-shared=0

SPATIO-ECOLOGICAL NICHE SEGREGATION OF TWO SYMPATRIC SPECIES OF CLIDEMIA (MELASTOMATACEAE ) IN WESTERN AMAZONIAN NON-FLOODED RAINFORESTS.

Title

SPATIO-ECOLOGICAL NICHE SEGREGATION OF TWO SYMPATRIC SPECIES OF CLIDEMIA (MELASTOMATACEAE ) IN WESTERN AMAZONIAN NON-FLOODED RAINFORESTS

Author
Schulman, Leif; Koivunen, Hannele; Ruokolainen, Kalle

Published Date 
June 2004

Source 
Folia Geobotanica;Jun2004, Vol. 39 Issue 2, p143

Source Type 
Academic Journal


Abstract

The frequent occurrence of sympatric series of closely related plant species in tropical rainforests has evoked claims for and against the application of the competitive exclusion principle in these ecosystems. Narrow niche limits defined by biotic as well as abiotic specialization have been reported for sympatric species of the same genus or family. In Amazonian lowland rainforests this question deserves renewed attention because: (1) the existence of edaphically defined community types has recently been well established, and (2) spatio-ecological niche segregation of congeneric species may help explain not only the maintenance of the high Amazonian alpha-diversity, but also its origin through sympatric ecological speciation. In this study, the morphology, ecology, and distribution patterns of two species, Clidemia epiphytica and C. longifolia (Melastomataceae), from western Amazonia, were analyzed. The aims were to find out whether they really are two distinct taxonomic species and if so, whether they also can be considered biological species; if the species are sympatric; and if they are ecologically specialized. The results showed that the morphological variation of the species seems continuous, but that they exhibit opposite morphological responses to variation in soil cation concentration, which suggests that they also are separate biological species. Furthermore, the species occur sympatrically but in different habitats. It is suggested that a part of the enigma of sympatric congeners in rainforests may be explainable by spatial segregation stemming from ecological specialization in relation to subtle environmental variation. It is hypothesized that the studied species are a...


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http://connection.ebscohost.com/c/articles/15123187/spatio-ecological-niche-segregation-two-sympatric-species-clidemia-melastomataceae-western-amazonian-non-flooded-rainforests

Invasion and management of alien Hedychium gardnerianum (kahili ginger, Zingiberaceae) alter plant species composition of a montane rainforest on the island of Hawai’i.

Title

Invasion and management of alien Hedychium gardnerianum (kahili ginger, Zingiberaceae) alter plant species composition of a montane rainforest on the island of Hawai’i

Author 

Minden, Vanessa; Hennenberg, Klaus Josef; Porembski, Stefan; Boehmer, Hans Juergen

Published Date 
February 2010

Source 
Plant Ecology;Feb2010, Vol. 206 Issue 2, p321

Source Type 
Academic Journal


Abstract

Hedychium gardnerianum is a major invader of native Hawaiian forests and suspected of smothering native understory species and preventing native tree seedlings’ establishment. In this study, effects on species composition in six vegetation layers of a Hawaiian rainforest were examined (Tree Layer 1, Tree Layer 2, Fern-Shrub Layer, Herb Layer, Bryophyte–Herb Layer, and Bryophyte Layer). Three different area types were compared, which included (i) Natural area types with no influence of non-native species, (ii) Ginger area types with a Hedychium gardnerianum dominated herb layer, and (iii) Cleared area types, which were treated with herbicide to remove alien species in 1998. Species composition sampled in 2004 of the upper three vegetation layers (Tree Layer 1, Tree Layer 2, and Fern-Shrub Layer) differed little. The lower three vegetation layers (Herb Layer, Bryophyte–Herb Layer, and Bryophyte Layer) showed highly significant differences. Species composition in the Ginger area types showed notable abundances of non-native Psidium cattleianum, but low coverage of native species. In the area freed of Hedychium gardnerianum (Cleared area types), native species are regenerating, although it still reveals signs of disturbance. If this area is managed to prevent reinvasion, then it is likely to regain a natural forest structure.


For further details log on website :

http://connection.ebscohost.com/c/articles/47145496/invasion-management-alien-hedychium-gardnerianum-kahili-ginger-zingiberaceae-alter-plant-species-composition-montane-rainforest-island-hawai-i

Barriers to Communication in Children

Overview

Communication involves using language to express ideas and share information, such as through listening, reading, speaking and writing. Children require good language and speech skills to interact with people and succeed in educational settings and other areas of life. If your child experiences problems communicating, she may fall behind in school and struggle with situations that rely on effective communication.

Communication barriers can limit a child's interactions, well-being and future success. Photo Credit Medioimages/Photodisc/Photodisc/Getty Images.

Cognitive Problems

Children with cognitive problems may have insufficient thinking skills, which can lead to problems in such areas as imagination, intellect, judgment, memory, perception and reasoning, according to the American Speech-Language-Hearing Association. Causes of poor cognitive functioning include brain or head injuries, neurological conditions and premature birth. If your child has a cognitive disorder, the Cincinnati Children's Hospital Medical Center recommends seeking qualified medical assistance as early as possible, preferably while your child is of preschool age, when language skills begin evolving.

Fluency Problems

Fluency refers to your child's ability to talk with normal, uninterrupted speech flow. The speech of children with fluency problems often contains a large amount of hesitations, prolonged sounds or repetitions,states the American Speech-Language-Hearing Association. Stuttering is a common example of a fluency disorder, which is also called dysfluency. More than 15 million people worldwide stutter, according to Psychology Today. The condition is most common in children aged 2 to 6, and it lasts less than six months in about 97 percent of children.

Language Problems

Language disorders affect the ability to understand speech or use spoken or written language effectively, according to the American Speech-Language-Hearing Association. Examples of language disorders include expressive language disorder, which makes it difficult for a child to use the correct words to state what she means to others, and receptive language disorder, which makes it difficult for a child to understand the words that others use. Children can have expressive and receptive problems at the same time, and they can also have a language disorder even if they seem to produce and understand speech well.

Speech Problems

Also called articulation disorders, speech disorders prevent a child from pronouncing sounds correctly, states the American Speech-Language-Hearing Association. As a result, his speech may include a lot of mistakes and sound poorly articulated. Types of errors found in the speech of children with speech disorders include distortions due to pronouncing sounds unclearly, omissions due to leaving out required sounds and substitutions due to the use of incorrect sounds instead of the correct version. Speech problems often occur because of physical issues, such as cleft palate, hearing loss and teeth problems, according to the Cincinnati Children's Hospital Medical Center.

Voice Problems

Voice problems arise when certain aspects of your child's voice affects its quality, according to the American Speech-Language-Hearing Association. The disorder may then lead to issues, including nasality, hoarseness and inappropriate volume, such as being too soft or too loud. Voice disorders are usually related to phonation, which concerns how air from the lungs make the vocal cords vibrate, or resonance, which involves the way air travels through mouth, nose and throat.

www.livestrong.com

Do You Really Need a Recovery Week From Working Out?

Exercising places a tremendous strain on the body. When you exercise, you tear muscle fibers, which the body must repair in order to make you stronger. In order to do this, your body must have time to recover. Because exercise programs vary in duration and intensity, some athletes need more time to recover than others. The average exerciser is fine taking one to three rest days off a week and doesn't require an entire week's recovery. However, athletes doing intense weightlifting or long endurance races should include recovery weeks in their schedule.

A couple relaxing at home together. Photo Credit Michael Blann/Digital Vision/Getty Images.

Recovery

The body does not grow stronger or build endurance while you're exercising. It's the period after your workout when your body makes all of these important changes. It's vital to give your body this time to repair itself or your fitness will not increase. In fact, your fitness will likely plateau or decline if you continue to push yourself without recovery. Proper recovery means resting the day after a hard workout or engaging in very light exercise. You should also eat a healthy diet and aim to sleep for at least seven hours a night. Plan recovery days and weeks into your training program and do not skip them.

Recovery Week

A recovery week gives the body more time to heal and adapt to the new physical stimulus. Scheduling a week off will give your body time to do this and will also help you return to your workout stronger and ready to challenge your body once again. Many endurance athletes end their season with a week off and many weightlifters will take a week off from their program every four to eight weeks. It's also common for runners and cyclists to have a down week after a marathon or century as their bodies recover. This helps them transition into the next set of workouts and to keep their minds fresh and engaged in their sport.

When to Recover

If you're setting up a training program, be it lifting weights, cardio or a combination of the two, schedule at least one recovery day into your week. If you're a beginner, take two to three. Advanced exercisers should take a week off at the end of your season or every two to three months. According to M. Doug McGuff, M.D., a week off will not have negative implications on your fitness and is instead highly beneficial for muscular growth and adaptation. Consult a physician or coach if you're unsure of when to schedule recovery.

Overtraining

When athletes do not allow proper recovery time, they risk overtraining. Symptoms of overtraining include chronic fatigue, a foul mood or depression, an elevated resting heart rate, trouble sleeping and decreased athletic performance. The body is also more vulnerable to infections and injury at this time. Symptoms can be severe, so it's important to consult your doctor during the early signs to decrease the length of recovery time.

www.livestrong.com

Enzymatic hydrolysis of potato starches containing different amounts of phosphorus

Published Date

1 January 2009, Vol.112(1):57–62, doi:10.1016/j.foodchem.2008.05.045

Title 
Enzymatic hydrolysis of potato starches containing different amounts of phosphorus

Author 

Nurul Absar ^a,b

I.S.M. Zaidul ^a,c

Shigenobu Takigawa ^a

Naoto Hashimoto ^a

Chie Matsuura-Endo^a

Hiroaki Yamauchi ^a

Takahiro Noda ^a,,

• aMemuro Upland Farming Research Station, National Agricultural Research Center for Hokkaido Region, Shinsei, Memuro, Kasai, Hokkaido 082-0071, Japan
• bDepartment of Biochemistry and Biotechnolgy, University of Science and Technology Chittagong, Foy’s lake, Chittagong 4202, Bangladesh
• cFaculty of Food Science and Technology, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor DE, Malaysia

Received 28 February 2008. Revised 26 March 2008. Accepted 12 May 2008. Available online 21 May 2008.

Abstract

The rapid hydrolysis of potato starches differing in phosphorus content, as well as sweet potato, cassava and yam starches, was accomplished by treatment of gelatinised starches with bacterial liquefying α-amylase at 50 °C for 1 h, followed by Bacillus licheniformis α-amylase at 55 °C up to 24 h, and then by glucoamylase at 40 °C for a further 24 h. Among the potato starches, the high-phosphorus starches showed higher starch resistant capacity than the medium-phosphorus starches, as well as other tuber and root starches. The hydrolysis rate of tuber and root starches was not greatly influenced by their amylose content and median granule size. Only glucose was detected in the almost completely hydrolysed tuber and root starch samples, indicating that the concomitant enzymes treatment could hydrolyse both the α-1,4 and α-1,6 linkages of the starches examined.

Keywords

Gelatinised potato starches

Phosphorus content

α-Amylase

Glucoamylase

 Table 1

Table 1.

 Table 2

Table 2.

 Table 3

Table 3.

 Table 4

Table 4.

Fig. 1.

• ⁎ 
  Corresponding author. Tel.: +81 155 62 9278; fax: +81 155 62 2926.

For further details log on website :

http://www.sciencedirect.com/science/article/pii/S0308814608005943

A Study of Specific Heat Capacity Functions of Polyvinyl Alcohol- Cassava Starch Blends

Title

A Study of Specific Heat Capacity Functions of Polyvinyl Alcohol- Cassava Starch Blends
(Science.gov (United States)

Author 

Sin, Lee Tin; Rahman, W. A. W. A.; Rahmat, A. R.; Morad, N. A.; Salleh, M. S. N.

Published Date 

2010-03-01

Abstract 

The specific heat capacity ( C sp) of polyvinyl alcohol (PVOH) blends with cassava starch (CSS) was studied by the differential scanning calorimetry method. Specimens of PVOH-CSS blends: PPV37 (70 mass% CSS) and PPV46 (60 mass% CSS) were prepared by a melt blending method with glycerol added as a plasticizer. The results showed that the specific heat capacity of PPV37 and PPV46 at temperatures from 330 K to 530 K increased from (2.963 to 14.995) J· g-1 · K-1 and (2.517 to 14.727) J · g-1· K-1, respectively. The specific heat capacity of PVOH-CSS depends on the amount of starch. The specific heat capacity of the specimens can be approximated by polynomial equations with a curve fitting regression > 0.992. For instance, the specific heat capacity (in J · g-1 · K-1) of PPV37 can be expressed by C sp = -17.824 + 0.063 T and PPV46 by C sp = -18.047 + 0.061 T, where T is the temperature (in K).


For further details log on website :

http://adsabs.harvard.edu/abs/2010IJT....31..525S

Tailor-made starch-based conjugates containing well-defined poly(vinyl acetate and its derivative poly(vinyl alcohol

Title
Tailor-made starch-based conjugates containing well-defined poly(vinyl acetate and its derivative poly(vinylalcohol)
Directory of Open Access Journals (Sweden)

Published Date 
2011-06-01

Abstract 

Full Text Available Reversible addition-fragmentation chain transfer (RAFT polymerization was adopted to synthesize starch-based conjugates that possessed controllable architecture and properties. Starch-based xanthate agent was prepared and applied as chain transfer agent to conduct the living/controlled polymerization (LCP of vinyl acetate, which generated tailor-made conjugates of starch and well-defined poly(vinyl acetate (SVAc. The relevant derivatives, conjugates of starch and chain length-controlled poly(vinylalcohol (SVA, were obtained subsequently. Various characterizations such as Fourier transform infrared spectra (FTIR, ultraviolet-visible spectroscopy (UV, proton nuclear magnetic resonance (1H NMR, gel permeation chromatography (GPC, X-ray diffraction (XRD, Thermogravimetric analysis (TGA, and dynamic mechanical thermal analysis (DMTA were performed to examine the structure of intermediates and the starch-based conjugates. Static contact angle measurements revealed that the hydrophilic character of starch-based conjugates was tunable. Well-defined SVAc was amphiphilic and it was able to self-assemble into size controllable micelles, which was verified by contact angles, transmission electron microscopy (TEM and dynamic light scattering (DLS tests. SVA exhibited much higher capability to form physically cross-linked hydrogel than starch did. Both the characteristic of SVAc and SVA were chain length-dependent.



For further details log on website :

http://worldwidescience.org/topicpages/s/starch+polyvinyl+alcohol.html#