Enzymatic Hydrolysis of Pretreated Chitin by Aspergillus carneus Chitinase

Abdel, Naby.,Mohamed, A.,Kwon, Dae Young 한국미생물 · 생명공학회 1992 Journal of microbiology and biotechnology Vol.2 No.3

Studies of the pretreatment of chitin and its subsequent hydrolysis by Aspergillus carneus chitinase are reported. Ball milling was found to be the most effective way among the pretreatment methods tested. Data are presented describing the effect of enzyme and substrate concentrations on the rate and extent of the hydrolysis process. It was found that the successive addition of enzyme improved the saccharification yield. Significant product inhibition of the chitinase was observed when N-acetylglucosamine concentration was 3.6% or higher. Adsorption of enzymes to the substrate occurred during a 24 hr hydrolysis period. An initial rapid and extensive adsorption occurred, followed by gradual desorption which increased during the time of reaction. Intermediate removal of the hydrolyzate and continuation of the hydrolysis by adsorbed enzyme on the residual chitin was also investigated. A total of 75.4g/ℓ reducing sugars, corresponding to 69.2% saccharificaton yield (as N-acetylglucosamine) was obtained. In addition an increase in the amount of recoverable enzymes was observed under these conditions. Evidence presented here suggests that the technique, whereby the free enzymes in the recovered hydrolyzate are re-adsorbed onto the new substrate, may provide a means of recirculating the dissolved enzymes.

The Production of Xylanase and β-Xylosidase by Aspergillus niger NRC 107

Abdel Naby, Mohamed A.,Kwon, Dae Young 한국산업미생물학회 1992 한국미생물·생명공학회지 Vol.20 No.5

Hemicellulose를 효소에 의하여 분해시키기 위하여 Aspergillus niger NRC 107로부터 xylanase와 β-xylosidase의 생산 조건에 대하여 조사하였다. 이들 효소 생산 최적 pH는 6.0이었으며 탄소원 중 corn-cob xylan과 질소원 중 Na_2N0_3이 효소 생산에 제일 좋은 기질이었으며 이들의 최적농도는 각각 15g/ℓ와 2.67g/ℓ이다. 이들 효소는 인산염(KH_2P0_4)과 Tween-80의 농도를 조절하므로 수율을 높일 수 있으며 wheat bran은 xylanase의 생산에 L(-) sorbose는 β-xylosidase의 생산에 좋은 영향을 주었다. 이와같이 이 Aspergillus niger NRC 107의 회분식 배양에서 이들 효소에 영향을 미치는 생산조건을 최적화한 결과 xylanase는 39.43 units/㎖, β-xylosidase는 4.2 units/㎖까지 생산할 수 있었다. The production of xylanase and β-xylosidase was investigated in submerged culture of Aspergillus niger NRC 107. The maximum production occurred when the pH was controlled at 6.0 during the fermentation. Among the various carbon sources investigated, corn-cob xylan(1.5%, w/v) yielded maximal production of the enzymes. The NaNO_3 was the most favorable nitrogen source for enzyme production and KH_2P0_4 concentration at 0.3%(w/v) was found to be optimum. Incorporation of wheat bran to the culture medium improved xylanase production. Addition of L(-) sorbose to the culture medium promoted the secretion of β-xylosidase. It was possible to increase the production of xylanase (39.43 units/㎖) and that of β-xylosidase (4.2 units/㎖) by submerged culturing the A. niger NRC 107 in the modified medium.

Optimization of Some Fermentation Parameters for Maximal Productivity of Lactic Acid by Calcium Alginate Immobilized Lactococcus lactis

Mohamed A . Abdel - Naby,Cherl Ho Lee 한국미생물생명공학회(구 한국산업미생물학회) 1992 한국미생물생명공학회 학술발표초록집 Vol.1992 No.2

Technological and economic study of ship recycling in Egypt

Welaya, Yousri M.A.,Abdel Naby, Maged M.,Tadros, Mina Y. The Society of Naval Architects of Korea 2012 International Journal of Naval Architecture and Oc Vol.4 No.4

The ship recycling industry is growing rapidly. It is estimated that the International Maritime Organization's (IMO) decision to phase-out single hull tankers by 2015 will result in hundreds of ships requiring disposal. At present, the ship recycling industry is predominantly based in South Asia. Due to the bad practice of current scrapping procedure, the paper will highlight the harm occurring to health, safety and environment. The efforts of the Marine Environment Protection Committee (MEPC) which led to the signing of the Hong Kong International Convention are also reviewed. The criteria and standards required to reduce the risk and damage to the environment are discussed and a proposed plan for the safe scrapping of ships is then presented. A technological and economic study for the ship recycling in Egypt is carried out as a case study. This includes the ship recycling facility size and layout. The equipment and staff required to operate the facility are also evaluated. A cost analysis is then carried out. This includes site development, human resources, machineries and equipment. A fuzzy logic approach is used to assess the benefits of the ship breaking yard. The use of the fuzzy logic approach is found suitable to make decisions for the ship breaking industry. Based on given constraints, the proposed model has proved capable of assessing the profit and the internal rate of return.

Assessment of anterior positioning splint in conjunction with lateral pterygoid BTX injection to treat TMJ disc displacement with reduction — a preliminary report

Maram Taema,Nouran Abdel Nabi,Samira Ibrahim,Heba Ahmed Kamal,Aala’a Emara 대한악안면성형재건외과학회 2021 Maxillofacial Plastic Reconstructive Surgery Vol.43 No.-

Objective: Treatment of temporomandibular disc displacement with reduction is controversial. This study assessesthe use of an anterior positioning splint with botulinum toxin in the lateral pterygoid muscle (BTX) for such cases. Methods: Twelve joints were included; groups I and II received BTX injection while group II also received ananterior positioning splint. Pain scores and clicking status were recorded at regular intervals then a postoperativeMRI was done after 4 months. Results: Clinical improvement was noted in both groups. Mean pain scores dropped significantly and clicks in thetwelve joints disappeared in 83% of group I and 33% of group II. MRIs showed significant disc positionimprovement with the higher mean change (1.33 ± 0.76) in group I. Group I showed better improvement of discal position and only one joint regained a click. Patients of group IIreported discomfort from the splint which may have caused psychological distress and so worst pain scores. Conclusions: Group I showed slightly better results but the cost of BTX injections and the complications of thesplint should be kept in mind and the decision of treatment selection made according to each condition.

Technological and economic study of ship recycling in Egypt

Yousri M. A. Welaya,Maged M. Abdel Naby,Mina Y. Tadros 대한조선학회 2012 International Journal of Naval Architecture and Oc Vol.4 No.4

The ship recycling industry is growing rapidly. It is estimated that the International Maritime Organiz¬ation’s (IMO) decision to phase-out single hull tankers by 2015 will result in hundreds of ships requiring disposal. At present, the ship recycling industry is predominantly based in South Asia. Due to the bad practice of current scrapping procedure, the paper will highlight the harm occurring to health, safety and environment. The efforts of the Marine Environment Protection Committee (MEPC) which led to the signing of the Hong Kong International Convention are also reviewed. The criteria and standards required to reduce the risk and damage to the environment are discussed and a proposed plan for the safe scrapping of ships is then presented. A technological and economic study for the ship recycling in Egypt is carried out as a case study. This includes the ship recycling facility size and layout. The equipment and staff required to operate the facility are also evaluated. A cost analysis is then carried out. This includes site development, human resources, machineries and equipment. A fuzzy logic approach is used to assess the benefits of the ship breaking yard. The use of the fuzzy logic approach is found suitable to make decisions for the ship breaking in¬dustry. Based on given constraints, the proposed model has proved capable of assessing the profit and the internal rate of return.

Comparing the Passive Sampler and Biomonitoring of Organic Pollutants in Water: A Laboratory Study

Nahla S. El-Shenawy,Richard Greenwood,Ismail M. Abdel-Nabi,Zohour I. Nabil 한국해양과학기술원 2009 Ocean science journal Vol.44 No.2

Passive sampling could provide the solution to problems associated with costly and time consuming sampling programmes and biomonitoring. Mussels (Mytilus edulis) and Chemcatcher passive sampler were simultaneously analyzed for sequestered pesticides and polychlorinated biphenyls (PCBs) by gas chromatography with mass spectrometry (GC/MSD). The Chemcatcher passive sampler based on a solid phase extraction disc with two types of diffusion-limiting membranes (polyethelene and polysulphone), were also compared. Diuron, atrazine, irgarol and lindane were accumulated in the polysulphone passive sampler in greater concentration than in the mussels or in the other passive samplers with polyethelene limiting-membrane. Mussels can accumulate in their tissue high concentration of non polar compounds such as PCB 52, dieldren and PCB 153; more than the passive sampler with polysulphone membrane. The device with polyethelene limiting membrane has high affinity capacity to concentrate high amount of phenenthrene, dieldrin, PCB 153 and PCB 52, so it acts as a sampler for non-polar compounds. The highest uptake rate of hydrophobic compounds by Chemcatcher was observed for analytes with log octanol-water partition coefficient (KOW) between 4.5 and 7.5. Laboratorybased studies using passive samplers to assess the potential for bioaccumulation could provide robust and reliable information at relatively low cost compared to biomonitoring data. Laboratory data obtained using passive samplers could be related to accumulation under field conditions where field assessments are required. Passive sampling could provide the solution to problems associated with costly and time consuming sampling programmes and biomonitoring. Mussels (Mytilus edulis) and Chemcatcher passive sampler were simultaneously analyzed for sequestered pesticides and polychlorinated biphenyls (PCBs) by gas chromatography with mass spectrometry (GC/MSD). The Chemcatcher passive sampler based on a solid phase extraction disc with two types of diffusion-limiting membranes (polyethelene and polysulphone), were also compared. Diuron, atrazine, irgarol and lindane were accumulated in the polysulphone passive sampler in greater concentration than in the mussels or in the other passive samplers with polyethelene limiting-membrane. Mussels can accumulate in their tissue high concentration of non polar compounds such as PCB 52, dieldren and PCB 153; more than the passive sampler with polysulphone membrane. The device with polyethelene limiting membrane has high affinity capacity to concentrate high amount of phenenthrene, dieldrin, PCB 153 and PCB 52, so it acts as a sampler for non-polar compounds. The highest uptake rate of hydrophobic compounds by Chemcatcher was observed for analytes with log octanol-water partition coefficient (KOW) between 4.5 and 7.5. Laboratorybased studies using passive samplers to assess the potential for bioaccumulation could provide robust and reliable information at relatively low cost compared to biomonitoring data. Laboratory data obtained using passive samplers could be related to accumulation under field conditions where field assessments are required.

Histopathologic Biomarker Response of Clam, Ruditapes decussates, to Organophosphorous Pesticides Reldan and Roundup: A Laboratory Study

El-Shenawy, Nahla S.,Moawad, Tarak I.S.,Mohallal, Mahmoud E.,Abdel-Nabi, Ismail M.,Taha, Inas A. 한국해양학회 2009 Ocean science journal Vol.44 No.1

Clam Ruditapes decussates was used as a biomonitoring organism to measure the potential impact of pollution. The present study investigated histological alterations of R. decussates following a long-term exposure to a sublethal-level of pesticides Reldan and Roundup. The clams were taken to the laboratory and kept for days to adjust to a continuous closed flow system with quality water control. After the adjustment period, clams were exposed either to sublethal concentrations of Reldan (0.6 $\mu$l $L^{-1}$) or Roundup (1.1 $\mu$l $L^{-1}$) for 90 days. Clams were taken to determine the histological damage at 30, 60 and 90 days. Most histological alterations were highly localized in the glandular cells of the gills, mantle tissues and digestive gland; secretions of glandular cells were found to be increased by increasing the time of exposure. Histopathological results showed the activation of resistance mechanisms that allowed the clams to survive under sublethal stresses. Thus, histological changes on localized tissues were sensitive and they have positive correlation to the time of exposure to the pesticides, suggesting that they may serve as biomarkers for Reldan and Roundup exposures.

Histopathologic Biomarker Response of Clam, Ruditapes decussates, to Organophosphorous Pesticides Reldan and Roundup: A Laboratory Study

Nahla S. El-Shenawy,Tarak I. S. Moawad,Mahmoud E. Mohallal,Ismail M. Abdel-Nabi,Inas A. Taha 한국해양과학기술원 2009 Ocean science journal Vol.44 No.1

Clam Ruditapes decussates was used as a biomonitoring organism to measure the potential impact of pollution. The present study investigated histological alterations of R. decussates following a long-term exposure to a sublethal-level of pesticides Reldan and Roundup. The clams were taken to the laboratory and kept for days to adjust to a continuous closed flow system with quality water control. After the adjustment period, clams were exposed either to sublethal concentrations of Reldan (0.6 μl L−1) or Roundup (1.1 μl L−1) for 90 days. Clams were taken to determine the histological damage at 30, 60 and 90 days. Most histological alterations were highly localized in the glandular cells of the gills, mantle tissues and digestive gland; secretions of glandular cells were found to be increased by increasing the time of exposure. Histopathological results showed the activation of resistance mechanisms that allowed the clams to survive under sublethal stresses. Thus, histological changes on localized tissues were sensitive and they have positive correlation to the time of exposure to the pesticides, suggesting that they may serve as biomarkers for Reldan and Roundup exposures. Clam Ruditapes decussates was used as a biomonitoring organism to measure the potential impact of pollution. The present study investigated histological alterations of R. decussates following a long-term exposure to a sublethal-level of pesticides Reldan and Roundup. The clams were taken to the laboratory and kept for days to adjust to a continuous closed flow system with quality water control. After the adjustment period, clams were exposed either to sublethal concentrations of Reldan (0.6 μl L−1) or Roundup (1.1 μl L−1) for 90 days. Clams were taken to determine the histological damage at 30, 60 and 90 days. Most histological alterations were highly localized in the glandular cells of the gills, mantle tissues and digestive gland; secretions of glandular cells were found to be increased by increasing the time of exposure. Histopathological results showed the activation of resistance mechanisms that allowed the clams to survive under sublethal stresses. Thus, histological changes on localized tissues were sensitive and they have positive correlation to the time of exposure to the pesticides, suggesting that they may serve as biomarkers for Reldan and Roundup exposures.