scholarly journals FORMULASI DAN STABILITAS MIKROEMULSI O/W DENGAN METODE EMULSIFIKASI SPONTAN MENGGUNAKAN VCO DAN MINYAK SAWIT SEBAGAI FASE MINYAK: PENGARUH RASIO SURFAKTAN-MINYAK

2015 ◽  
Vol 35 (01) ◽  
pp. 27 ◽  
Author(s):  
Setyaningrum Ariviani ◽  
Sri Raharjo ◽  
Sri Anggrahini ◽  
Sri Naruki
Keyword(s):  
Palm Oil ◽  
Room Temperature ◽  
Particle Diameter ◽  
Tween 80 ◽  
Food Grade ◽  
Heating Treatment ◽  
The Mean ◽  
Span 80 ◽  
And Storage ◽  
Formulation Stability

This study was aimed to (1) formulate o/w microemulsion using different surfactant oil ratio, (2) determine the microemulsions stability toward centrifugation, heating and storage at room temperature, and (3) characterize microemulsions which were shown the best stability. Microemulsions were prepared using ternary food grade surfactantwith low HLB (span 80), medium HLB (span 20 or span 40) and high HLB (tween 80), and surfactant oil ratio 2,3,4 and 5. VCO and palm oil were used as oil phase, whereas 10 μM phosphate buffer pH 7 was used as aqueous phase. O/W microemulsionwere formed at surfactant oil ratio 3 or more for VCO and at higher surfactant oil ratio (i.e 4 or 5) when palm oil was used as oil phase. Microemulsions with VCO as oil phase which were stable toward centrifugation, heating treatment and storage at room temperature i.e. microemulsions with surfactant oil ratio 4 or 5, while the use of palm oil as oil phase produce stable microemulsions at surfactant oil ratio 4. Microemulsions with surfactant oil ratio 4 showedthe best stability. This microemulsions have a monomodal particle size distribution, the mean particle diameter and viscosity reached 21.7 ± 0.02nm and 6.0 ± 0.10cp (VCO), 22.9 ± 0.15nm and 6.2 ± 0.05cp (palm oil).Keywords: Microemulsion, formulation, stability, surfactant, oil ABSTRAKPenelitian ini bertujuan untuk (1) formulasi mikroemulsi o/w dengan variasirasio surfaktan-minyak, (2) menentukan stabilitas mikroemulsiterhadap sentrifugasi, pemanasan dan penyimpanan suhu ruang, dan (3) karakterisasi mikroemulsi dengan stabilitas terbaik. Mikroemulsi dibuat menggunakan campuran tiga surfaktan food grade yaitu surfaktan HLB rendah (span 80), sedang (span 20 atau span 40), dan tinggi (tween 80), dengan rasio surfaktan minyak 2, 3, 4 dan 5. VCOdan minyak kelapa sawit digunakan sebagai fase minyak, 10 μM bufer fosfat pH 7 sebagai fase aqueous. Mikroemulsi o/w terbentuk pada rasio surfaktan minyak 3 atau lebih untuk penggunaan VCO dan pada rasio surfaktan minyak yang lebih tinggi (yaitu 4 atau 5) untuk penggunaan minyak sawit sebagai fase minyak. Mikroemulsi dengan fase minyakVCO yang stabil terhadap sentrifugasi, pemanasan maupun penyimpanan suhu ruang adalah mikroemulsi dengan rasio surfaktan-minyak 4 atau 5, sedangkan penggunaan minyak sawit sebagai fase minyak menghasilkan mikroemulsi yang stabil pada rasio surfaktan-minyak 4. Mikroemulsi dengan rasio surfaktan-minyak 4 memperlihatkan stabilitas terbaik.Mikroemulsi tersebut memiliki distribusi ukuran partikel monomodal, rerata diameter partikel dan viskositas mencapai 21,7 ± 0,02nm dan 6,0 ± 0,10cp (VCO), 22,9 ± 0,15nm dan 6,2 ± 0,05cp (minyak sawit).Kata kunci: Mikroemulsi, formulasi, stabilitas, surfaktan minyak

scholarly journals Karakterisasi dan Uji Stabilitas Digestif Nanoemulsi β-Karoten yang Dibuat dengan Metode Emulsifikasi Spontan

2018 ◽  
Vol 38 (1) ◽  
pp. 30
Author(s):  
Setyaningrum Ariviani ◽  
Windi Atmaka ◽  
Sri Raharjo
Keyword(s):  
Palm Oil ◽  
Particle Diameter ◽  
Coconut Oil ◽  
Tween 80 ◽  
Virgin Coconut Oil ◽  
Food Grade ◽  
Span 80 ◽  
Β Carotene ◽  
Mean Particle Diameter

β-Carotene exhibits a wide range of health benefits, but its application in food formulation is very limited because of its instability and susceptibility to degradation. The stability of β-carotene can be improved by incorporation into an oil-in-water (o/w) emulsions. The objective of this research was to characterize β-carotene loaded nanoemulsions prepared with spontaneous emulsification method using ternary food-grade surfactants (Tween 80, Span 40, Span 80) and palm oil or VCO (virgin coconut oil) as oil phase with the surfactant-oil ratio of 4. The physicochemical stability of β-carotene loaded nanoemulsions during simulated digestions, which consist of the mouth, stomach, and intestine phases, was also evaluated using in-vitro digestion model. The results showed that β-carotene loaded nanoemulsions, prepared either using VCO or palm oil as the oil phase, had neutral pH (6.8±0.1), mean particle diameter of 129 -159 nm, showed monomodal particle size distribution with low polydispersity index (PdI) values  (0.214 - 0.266), and were not significantly different in zeta potential values ([-6,59]–[-8,9]). The β-carotene loaded nanoemulsions with VCO as the oil phase had a smaller mean particle diameter than that of palm oil. The physical stability of the β-carotene loaded nanoemulsions against digestive simulation in the mouth, stomach or intestine phases was not influenced by the oil phase type.  Both nanoemulsions were stable against simulated digestion in the mouth and stomach phases. After passing through the intestinal phase, the mean particle diameter increased and the particle size distribution changed from monomodal to bimodal. The β-carotene retention after passing through the mouth, stomach and intestinal phases of the β-carotene loaded nanoemulsion prepared using VCO were not significantly different from the palm oil. ABSTRAKβ-Karoten mempunyai berbagai manfaat kesehatan, namun aplikasinya dalam formulasi pangan sangat terbatas karena tidak stabil dan mudah mengalami degradasi. Stabilitas β-karoten dapat ditingkatkan dengan menggabungkannya dalam sistem penghantaran berbasis emulsi minyak dalam air (o/w). Penelitian ini bertujuan untuk melakukan karakterisasi nanoemulsi β-karoten yang dibuat dengan metode emulsifikasi spontan menggunakan kombinasi tiga surfaktan food grade (Tween 80, Span 40, Span 80), minyak sawit maupun VCO (virgin coconut oil) sebagai fase minyak dengan rasio surfaktan-fase minyak 4.. Penelitian ini juga mengkaji stabilitas fisikokimiawi nanoemulsi β-karoten selama pencernaan di mulut, lambung dan usus dengan menggunakan model digesti in vitro. Hasil penelitian memperlihatkan bahwa nanoemulsi β-karoten yang dibuat dengan fase minyak VCO maupun minyak sawit memiliki pH netral (6,8±0,1), rerata diameter partikel 129–159 nm, distribusi ukuran partikel monomodal dengan nilai indeks polidispersitas (polydispersity index, PdI) rendah (0,214–0,266) dan zeta potensial yang tidak berbeda nyata ([-6,59]–[-8,9]). Nanoemulsi β-karoten dengan fase minyak VCO memiliki rerata diameter partikel yang lebih kecil dibanding minyak sawit sebagai fase minyak. Jenis fase minyak tidak berpengaruh terhadap stabilitas fisik nanoemulsi β-karoten selama simulasi pencernaan di mulut, lambung maupun usus. Nanoemulsi β-karoten dengan fase minyak VCO maupun minyak sawit stabil terhadap pencernaan di mulut maupun lambung. Setelah melewati fase usus, terjadi peningkatan diameter partikel rerata dan perubahan distribusi ukuran partikel dari monomodal menjadi bimodal. Retensi β-karoten dalam nanoemulsi VCO setelah melewati simulasi pencernaan mulut, lambung dilanjutkan fase usus tidak berbeda nyata dengan retensi β-karoten dalam nanoemulsi minyak sawit.

scholarly journals Mineral Phase and Physical Properties of Red Mud Calcined at Different Temperatures

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Chuan-sheng Wu ◽  
Dong-yan Liu
Keyword(s):  
Red Mud ◽  
Room Temperature ◽  
Structural Transition ◽  
Particle Diameter ◽  
Physical Property ◽  
Mineral Phase ◽  
Sem Images ◽  
Tricalcium Aluminate ◽  
Different Temperatures ◽  
The Mean

Different characterizations were carried out on red mud uncalcined and samples calcined in the range of 100°C–1400°C. In the present paper, the phase composition and structural transition of red mud heated from room temperature are indicated by XRD, TG-DTA, and SEM techniques. The mean particle diameter, density, and bond strength of these samples also have been investigated. The results indicate the decomposition of gibbsite into Al2O3and H2O between 300°C and 550°C and calcite into CaO and CO2in the interval of 600–800°C. Tricalcium aluminate and gehlenite are formed in the range of 800–900°C. Combined with the SEM images, the results of physical property testing show that the particle size and the strength each has a continuous rise during the heat treatment from 150°C to 1350°C. But the value of density will undergo a little drop before 450°C and then increases to a higher value at the temperature of 1200°C. These obtained results provide an important base for the further studies of comprehensive utilization of red mud.

scholarly journals Stability of hepatitis B virus pregenomic RNA in plasma specimens under various temperatures and storage conditions

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11207
Author(s):  
Pakkapon Rattanachaisit ◽  
Sirinporn Suksawatamnuay ◽  
Supachaya Sriphoosanaphan ◽  
Kessarin Thanapirom ◽  
Panarat Thaimai ◽  
...  
Keyword(s):  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Room Temperature ◽  
Plasma Samples ◽  
Freeze Thaw ◽  
B Virus ◽  
The Mean ◽  
Clinically Significant ◽  
The Stability ◽  
And Storage

Background Hepatitis B virus (HBV) pregenomic RNA (pgRNA) has gained increasing attention owing to its role in replication of covalently closed circular DNA (cccDNA) in HBV. This marker has the potential to be used in clinical programs aimed to manage HBV infections. However, several reports on HBV pgRNA levels in clinical cases have conflicting results. RNA is easily degraded when exposed to heat and other environmental stressors. However, the stability of HBV pgRNA, during blood sample collection before the standard automated quantification, has never been estimated. This study aimed to demonstrate the effect of two different temperature conditions and storage durations on the stability of HBV pgRNA. Method Blood from forty patients with chronic hepatitis B infection, who also showed evidence of active HBV DNA replication, was collected and processed within 2 h of collection. Plasma from each patient was divided and stored at 4 °C and 25 °C (room temperature) for six different storage durations (0, 2, 6, 12, 24, and 48 h) and subsequently transferred to −80 °C for storage. The effect of multiple cycles of freezing and thawing of plasma at −20 °C or −80 °C was evaluated using samples from ten patients. Quantification of pgRNA from the samples was performed simultaneously, using the digital polymerase chain reaction (dPCR) method. The differences in pgRNA levels at baseline and each time point were compared using generalized estimating equation (GEE). A change greater than 0.5 log10 copies/mL of pgRNA is considered clinically significant. Statistical analyses were conducted using Stata 16.0. Results The mean HBV pgRNA level in the initially collected plasma samples was 5.58 log10copies/mL (ranging from 3.08 to 8.04 log10 copies/mL). The mean pgRNA levels in samples stored for different time periods compared with the initial reference sample (time 0) significantly decreased. The levels of pgRNA for 6, 12, 24, and 48 h of storage reduced by −0.05 log10 copies/mL (95% confidence interval (CI) −0.095 to −0.005, p = 0.03), −0.075 log10 copies/mL (95% CI [−0.12 to −0.03], p = 0.001), −0.084 log10 copies/mL (95% CI [−0.13 to −0.039], p =  < 0.001), and −0.120 log10 copies/mL (95% CI [−0.17 to −0.076], p =  < 0.001), respectively. However, these changes were below 0.5 log10 copies/mL and thus were not clinically significant. Compared with the samples stored at 4 °C, there were no significant differences in pgRNA levels in samples stored at 25 °C for any of the storage durations (−0.01 log10 copies/mL; 95% CI [−0.708 to 0.689], p = 0.98). No significant difference in the levels of pgRNA was observed in the plasma samples, following four freeze-thaw cycles at −20 °C and −80 °C. Conclusion The plasma HBV pgRNA level was stable at 4 °C and at room temperature for at least 48 h and under multiple freeze-thaw cycles. Our results suggest that pgRNA is stable during the process of blood collection, and therefore results of pgRNA quantification are reliable.

scholarly journals Formulation of Snail Slime (Achatina Fulica) Anti-Acne Emulgel using Tween 80-Span 80 as Emulsifying and HPMC as Gelling Agent

2018 ◽  
Vol 1 (2) ◽  
pp. 64-67 ◽  
Author(s):  
Nur Saadah Daud ◽  
Achnis Jum Akbar ◽  
Eny Nurhikma ◽  
Karmilah Karmilah
Keyword(s):  
Room Temperature ◽  
Ph Value ◽  
Normal Skin ◽  
Tween 80 ◽  
Gelling Agent ◽  
Achatina Fulica ◽  
Cycling Test ◽  
Oil In Water ◽  
Irritation Test ◽  
Span 80

Acne is the condition of abnormal skin which is indicated by inflammation caused by the bacterial infection of Propionibacterium acnes. The natural one which can be used for the medical treatment of acne is the snail mucus (Achatina fulica). The achasin protein of it has antibacterial activity. That snail mucus was made to the emulgel form. This research has used an experimental method and the emulgel formulation used the various concentration of emulsifying agents and the gelling agent. They were Tween 80 1.76%, 2.44%, 3.12%, Span 80 2.24%, 4.06%, 5.88% and HPMC 3.5%, 4.5%, 5.5%. Other additives were propylene glycol, Methylparaben, Propylparaben, paraffin liquid, menthol, and aquadest. Those formulations were tested in physical evaluation during 4 weeks of storage in room temperature, irritation test, hedonic test, and cycling test. The organoleptic test showed that the emulgel were the milk-white color with a distinctive smell. All emulgel were homogenous, non-irritant, with emulsion type oil in water (o/w). This emulgel also met the normal skin of pH value and spread ability�s range. The emulgel viscosity shift was < 10%, with the viscosity value inversely proportional to spreadability. Formula C with 3.12% of Tween 80, 5.88% of Span 80 and 5.5% of HPMC was claimed as the most stable formula both in room temperature and after cycling test. It was also the most preferred by the panelist.

Investigations on the Nature of Hemophilia A

1963 ◽  
Vol 09 (01) ◽  
pp. 030-052 ◽  
Author(s):  
Eberhard Mammen
Keyword(s):  
Factor Viii ◽  
Human Plasma ◽  
Barium Sulfate ◽  
Freeze Drying ◽  
Room Temperature ◽  
Hemophilia A ◽  
Normal Human Plasma ◽  
Normal Human ◽  
And Storage ◽  
Prothrombin Activation

SummaryIn this paper an inhibitor is described that is found in hemophilic plasma and serum different from any till now described inhibitor. The inhibitor only inhibits prothrombin activation in the “intrinsic clotting systems”. This inhibitor is probably not present in normal human plasma or serum. It is destroyed by ether and freeze drying, is labile to acid and storage at room temperature. It is stable upon dialysis and has not been adsorbed on barium sulfate, aluminum hydroxide or kaolin. It precipitates at 50% v/v saturation with alcohol. The nature of this inhibitor seems to be a protein or lipoprotein.Factor VIII was isolated from hemophilic plasma. The amount isolated was the same as from normal plasma and the activity properties were not different. Hemophiliacs have normal amounts of factor VIII.

PERILAKU DISOLUSI KETOPROFEN DAN INDOMETASIN FARNESIL TERSALUT GEL KITOSAN-GOM GUAR

2012 ◽  
Vol 12 (1) ◽  
Author(s):  
Purwantiningsih Sugita ◽  
Bambang Srijanto ◽  
Budi Arifin ◽  
Fithri Amelia ◽  
Mahdi Mubarok
Keyword(s):  
Room Temperature ◽  
Guar Gum ◽  
Tween 80 ◽  
Chitosan Solution ◽  
In Vitro Dissolution ◽  
Dissolution Profile ◽  
Magnetic Stirrer ◽  
Dissolution Behaviour ◽  
Shrimp Shell Waste

Chitosan, a modification of shrimp-shell waste, has been utilized as microcapsule. However, it’s fragile gel property needs to be strengthened by adding glutaraldehyde (glu) and natural hydrocolloid guar gum (gg). This research’s purposes were to study dissolution behaviour of ketoprofen and infar through optimum chitosan-guar gum microcapsule. Into 228.6 mL of 1.75% (w/v) chitosan solution in 1% (v/v) acetic acid,38.1 mL of gg solution was added with concentration variation of 0.35, 0.55, and 0.75% (w/v) for ketoprofen microcapsules and 0.05, 0.19, and 0.33% (w/v) for infar microcapsules, and stirred with magnetic stirrer until homogenous. Afterwards, 7.62mL of glu was added slowly under stirring, with concentrations varied: 3, 3.5, and 4% (v/v) for ketoprofen microcapsules, and 4, 4.5, and 5% (v/v) for infar microcapsules. All mixtures were shaked for 20 minutes for homogenization. All mixtures wereshaked for 20 minutes for homogenization. Into each  microcapsule mixture for ketoprofen, a solution of 2 g of ketoprofen in 250 mL of 96% ethanol was added, whereas solution of 100 mg of in 250 mL of 96% ethanol was added into each microcapsule mixture for infar. Every mixture was then added with 5 mL of 2% Tween-80 and stirred with magnetic stirrer for an hour at room temperature. Everymixture was then added with 5 mL of 2% Tween-80 and stirred with magnetic stirrer for an hour at room temperature. Conversion of suspension into fine powders/granules (microcapsules) was done by using spray dryer. The data of [gg], [glu], and medicine’s content from each microcapsule were treated with Minitab 14 software to obtain optimum [gg] and [glu] for microencapsulation. The dissolution behaviour of optimum ketoprofen and infar microcapsules were investigated. The result of optimization by using Minitab Release 14 software showed that among the microcapsule compositions of [gg] and [glu] were 0.35% (w/v) and 3.75% (v/v), respectively, optimum to coat ketoprofen, whereas [gg] and [glu] of 0.05% (w/v) and4.00% (v/v), respectively, optimum to coat infar, at constant chitosan concentration (1.75% [w/v]). In vitro dissolution profile showed that chitosan-guar gum gel microcapsule was more resistant in intestinal pH condition (rather basic) compared with that in gastric pH (very acidic).

scholarly journals Evaluating the Effects of Sediment Transport on Pipe Flow Resistance

Water ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2091
Author(s):  
Vito Ferro ◽  
Alessio Nicosia
Keyword(s):  
Velocity Profile ◽  
Pipe Flow ◽  
Power Distribution ◽  
Flow Resistance ◽  
Unit Length ◽  
Particle Diameter ◽  
Self Similarity ◽  
Sediment Size ◽  
The Mean ◽  
The Relationship

In this paper, the applicability of a theoretical flow resistance law to sediment-laden flow in pipes is tested. At first, the incomplete self-similarity (ISS) theory is applied to deduce the velocity profile and the corresponding flow resistance law. Then the available database of measurements carried out by clear water and sediment-laden flows with sediments having a quasi-uniform sediment size and three different values of the mean particle diameter Dm (0.88 mm, 0.41 mm and 0.30 mm) are used to calibrate the parameter of the power-velocity profile). The fitting of the measured local velocity to the power distribution demonstrates that (i) for clear flow the exponent δ) can be estimated by the equation of Castaing et al. and (ii) for the sediment-laden flows δ is related to the diameter Dm. A relationship for estimating the parameter Гv obtained by the power-velocity profile) and that Гf of the flow resistance law) is theoretically deduced. The relationship between the parameter Гv, the head loss per unit length and the pipe flow Froude number is also obtained by the available sediment-laden pipe flow data. Finally, the procedure to estimate the Darcy–Weisbach friction factor is tested by the available measurements.

scholarly journals Evaluation of Microbial Culture Techniques for the Isolation of Pythium Insidiosum from Equine Tissues

2002 ◽  
Vol 14 (4) ◽  
pp. 288-294 ◽  
Author(s):  
Amy M. Grooters ◽  
Amy Whittington ◽  
Mae K. Lopez ◽  
Michelle N. Boroughs ◽  
Alma F. Roy
Keyword(s):  
Room Temperature ◽  
Microbial Culture ◽  
Sample Type ◽  
Pythium Insidiosum ◽  
Selective Media ◽  
Culture Techniques ◽  
Media Type ◽  
Antibiotic Solution ◽  
And Storage ◽  
Storage Technique

The purpose of this study was to evaluate the effects of sample handling, storage, and culture techniques on the isolation of Pythium insidiosum from infected equine tissues. Tissue and kunker samples obtained immediately posteuthanasia from a horse with subcutaneous pythiosis were used to assess the effects of sample type (kunkers vs. tissues), media type (selective vs. nonselective), storage technique, and storage time on P. insidiosum isolation rate. Overall, isolation rates were higher from fresh kunkers (94.6%) and stored kunkers (76.4%) than from fresh tissues (8.3%) or stored tissues (4.6%). Isolation of P. insidiosum also occurred more often on antibiotic-containing media than on nonselective media for both fresh and stored samples. For samples that were stored for 1–3 days prior to culture, P. insidiosum isolation rates were highest for the following techniques: kunkers stored at room temperature and plated on selective media (100%), kunkers stored at 4 C and then plated on either nonselective (91.7%) or selective (95.8%) media, kunkers stored on cold packs and then plated on either nonselective (93.8%) or selective (100%) media, kunkers stored in ampicillin solution and plated on selective media (100%), and kunkers stored in ampicillin/gentocin solution and plated on selective media (87.5%). For samples stored for 4–5 days, P. insidiosum isolation rates were highest for kunkers stored at 4 C and then plated on either nonselective (81.3%) or selective (87.5%) media, kunkers stored in ampicillin solution and then plated on selective media (87.5%), and kunkers stored in ampicillin/gentocin solution and plated on selective media (87.5%). Results of this study suggest that optimal isolation rates of P. insidiosum from infected equine tissues are achieved by culturing fresh kunkers on selective media. For samples that cannot be processed immediately, acceptable handling techniques include storage at room temperature for up to 3 days, refrigeration for up to 5 days, shipping on cold packs, and storage in antibiotic solution, each combined with subsequent inoculation on selective media.

scholarly journals Eggs viability of Aedes aegypti Linnaeus (Diptera, Culicidae) under different environmental and storage conditions in Manaus, Amazonas, Brazil

2016 ◽  
Vol 77 (2) ◽  
pp. 396-401 ◽  
Author(s):  
V. C. Soares-Pinheiro ◽  
W. Dasso-Pinheiro ◽  
J. M. Trindade-Bezerra ◽  
W. P. Tadei
Keyword(s):  
Aedes Aegypti ◽  
Storage Conditions ◽  
Amazon Region ◽  
Storage Site ◽  
Egg Hatching ◽  
Plastic Bag ◽  
The Mean ◽  
And Storage ◽  
Storage Type ◽  
Hatching Rates

Abstract The viability of Aedes aegypti eggs was assessed in the Amazon region. The eggs were maintained under different conditions: indoors (insectarium) and outdoors (natural environment), as well as in different storage types (plastic cup, paper envelope, plastic bag) for different days. Egg viability was measured as the mean of hatchings observed from egg-bearing sheets of filter paper immersed in water, using three sheets randomly selected from each storage type and at both sites. There were significant differences in the viability of Ae. aegypti eggs with respect to the location (F=30.40; DF=1; P<0.0001), storage type (F=17.66; DF=2; P<0.0001), and time of storage (F=49.56; DF=9; P<0.0001). The interaction between storage site versus storage type was also significant (F=15.96; DF=2; P<0.0001). A higher hatching mean was observed for the eggs kept in the insectarium than for those outdoors (32.38 versus 7.46). Hatching rates of egg batches stored for 12 to 61 days ranged between 84 and 90%. A reduction was observed between 89 and 118 days, with values of 63 and 48%, respectively. With respect to type of storage, mean egg hatching was higher for the eggs in plastic cups (44.46). It was concluded that the viability of the eggs of Ae. aegypti in the Amazon region remains high up to 4 months, after which it declines drastically, although in this study hatching occurred for up to 8 months in very low percentages.

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