The study was conducted during 2017 in the laboratories of the department of Botany
at Tishreen University, Lattakia, Syria. The effect of ultraviolet radiation (UV-C and UVB)
for different periods (0.5, 1, 3, 5, 15, 15, 30, 45, 60 minutes) on the
photosynthetic
pigments of Euglena gracilis (with three stages of measurements) was studied. The results
showed that chlorophyll pigments were more sensitive to UV-C compared to UV-B. These
reductions were correlated with the increase in the exposure time, reaching the lowest
value after 60 minutes exposure (97.83, 98.73, 99.18% for chlorophyll a, chlorophyll b and
carotenoids when measured after 24 hours respectively).
The polyethylene films protect the chlorophyll pigments against UV radiation.
The protection rate was more evident against UV-C reaching .7.7% after 24 hours in the
algae exposed for 30 minutes according to the experimental conditions.
This research demonstrated a way to study the thermal properties
of raw and recycled High Density Polyethylene HDPE which is
used to make oil containers. Also, the research has dealt with the
effect of recycling on blow molding process used to manufacture
these containers.
The goal of this study is to produce STFs and measure
their rheological behavior In order to select the appropriate STF for
liquid armor application.
Young sun flower plants were exposed to ultraviolet radiation of the type UV-B (295
nm) for 3 days (2 hours per day) with or without excluding the UV-radiations using
polyethylene layers (blue and transparent) (0.5 mm thick). The amount of photosyn
thesis
pigments was measured whereby a variation in the chlorophyll contents. Chlorophyll a
(chl.a) was noticed at these rates (without covering 19.59%, transparent polyethylene
3.40%, blue polyethylene 1.66%), chlorophyll b (chl.b) at rates (7.81, 25.13, 22.79%) and
the total chlorophyll content (2.88, 21.76, 20.53%), while the amount of carotenoid
pigments has increased in the studied samples (24.45, 19.23, 17.32%). A decrease in the
rate of photosynthetic electron transport has also been noticed (88.04, 78.71, 58.81%) in
the plant samples exposed to ultraviolet radiation (on the third day) without UV excluding
and with transparent and blue polyethylene successively. All results were compared to the
sample which was not exposed to radiation.
All results indicate the negative effect of ultraviolet radiation on the chlorophyll
content and the rate of photosynthetic electron transport, therefore, on photosynthesis and
the productivity of sun flower plants. They also point out the importance of carotenoid
pigments in protecting chlorophyll pigments from the negative effects of this radiation.
Results showed the clear positive effect of polyethylene layers, specifically the blue one, in
protecting plants against this radiation.
This research aims to study the effect of adding Zinc Borate and
Aluminum Hydroxide as flame retardants to Low Density
polyethylene.
Specimens have been prepared through pouring them in a mold.
Results have revealed that replacement of certain am
ount of
Aluminum Hydroxide with Zinc Borate could lead to improving the
resistance of flame spread in Low Density polyethylene.
these improvements were basically due to further contribution of
Zinc Borate to the physical barrier mechanism of Aluminum
Hydroxide in both gas and solid phases.
The objective of the study was to determine experimentally
the dust pollution of polyethylene pipe during head- to - head
welding in the workshops piping and its impact on the efficiency of
welding.
Some kinetic parameters have been determined in this work for thermal and catalytic
cracking of the mixed of polyethylene and polypropylene using batch method. The
cracking reaction was carried out at different temperature 470,490 and 510oC under
atmospheric pressure. The mass of products (liquid and gas fractions) were determined and
used to plot the curves of the thermal and catalytic decomposition. We used two types of
catalysts: Syrian natural Zeolite and the same after loading with sulfate ions using
impregnation method. The thermal cracking has a long time and has firs-pseud order
reaction. While in the case of catalytic process we note that the reaction finished in the
short time and the process is the Zero-pseud order reaction. The rate of the cracking
increased very much, the rate constant was k1=0.0032.min-1 in the thermal cracking at
4700C and ko=0.111.min-1 in the case of catalytic cracking in presence of Z catalyst and
ko= 0.206 min-1 in presence of 15-SO4
2-/Z as catalytic at the same temperature. In the other
hand activation energy was 208.7 kj/mol in the thermal process and decreased to 116.6
kj/mol at Z catalytic presence and to 87.3 kj/mol at 15-SO4
2-/Z catalytic presence.
This paper focus on studying the elastic of modified cement mortar by polyethylene (stress-strain) curve in order to have Young's elastic modulus, this made by tri-phases modeling that allow to determination the property of this item depending on t
he property of it's three components individual.
The validation of the proposed model has been studied extensively depending on a sample of cement mortar divided into two groups, the first one patterning normal cement mortar, second patterning modified cement mortar by Polyethylene witch substitute five percentage ratio of weight of sand by the same ratio of Polyethylene.
Modified cement mortar is treated as composite of three components, Sand, Paste cement and Polyethylene. It's will be proposed models involving series, parallel and series-parallel coupling. This composite action is described by series-parallel model in which a portion of paste acts in parallel with sand and polyethylene and the remaining portion in series with this parallel coupling. Then according to the model we get Young's elastic modulus theoretically, reliance basic modulus factors of components.
The proposed model is calibrated and verified by means of data set by experiment modulus results perform on cast samples in laboratory.
It was found quite agreement of measured modulus factors experimentally versus theoretically.
The results showed the possibility of getting at a wide rang of board with different properties, and all investigated percentage had special properties which to use in industrial application, also the result showed the possibility to produce these bo
ard without pretreatment of particles wood or without addition any virgin plastic to RLDPE
The results showed the possibility of getting of a wide spectrum of boards with different properties, and all studied percentages had special properties which allow them to use in industrial application, also the result showed the possibility to produce these boards without treatment of the wood particles or without addition any virgin plastic to RLDPE
The aim of this investigation is studying effect of heat treatment and polyethylene packaging method in storability and quality of lemon fruits' Monachello and Enterdonato'. The experience was carried out in cold store of agriculture college in /Dama
scus university/, lemon fruits were stored at 10°c and 85% humidity for 180 days. laboratory experiences was carried out in laboratory of department of horticultural science in the same college during 2010-2011&2011-2012. Part of fruits were packaged in polyethylene bags with 30 microns, the other part of fruits dipped with hot water (62°c for 3 seconds)+ fungicide then were packed in polyethylene packs in addition to the control which untreated and unpacked.
The obtained results indicated the significant effect of dipping and packaging in perforated and unperforated bags treatments in maintain fruits quality of 'Monachello and Enterdonato' until the end of storage. maintaining of (32.89 and 39.06%( juice rate of Monachello respectively, and(11.05 and10.01%) of Enterdonato respectively. (35.27 and 36.57 mg/100ml (vitamin C of Monachello and (18 and11.07mg/100 ml( of Enterdonato, respectively.
On the other hand, the present investigation showed the positive effect of packaging treatment with 30 microns packs by reducing the weight loss for two sorts which was (51.94 and 68.83%) in dipping and packaging in perforated bags treatment respectively, and the important role to stop fruit decadence, and conserve their marketing specification until end of storage.
