scholarly journals CHEMICAL AND STRUCTURAL CHANGES IN POPLAR WOOD UPON STEAM TREATMENT AT CONSTANT TEMPERATURE AND PRESSURE CONDITIONS FOR DIFFERENT TIME INTERVALS

2021 ◽  
Vol 55 (9-10) ◽  
pp. 961-969
Author(s):  
SHARAD RAGHUVANSHI ◽  
◽  
HINA KHAN ◽  
VAISHALI SAROHA ◽  
ASHISH KADAM ◽  
...  
Keyword(s):  
Constant Temperature ◽  
Treatment Duration ◽  
Critical Time ◽  
Raw Material ◽  
Steam Treatment ◽  
Time Interval ◽  
Cellulose Ii ◽  
Crystalline Region ◽  
Poplar Wood ◽  
Temperature And Pressure

Technology advancement has helped in the development of high-throughput equipment for the analysis of raw material in paper industries. In this research, we have used some advanced techniques to analyze the pore size, structural and chemical changes, and cellulose crystallinity of poplar wood pretreated with steam at constant temperature and pressure conditions for different treatment time. Samples were analyzed by the nitrogen adsorption test, Fourier-transform infrared spectroscopy – attenuated total reflectance (FTIR–ATR), X-ray diffraction (XRD), and field scanning electron microscopy (FE-SEM). Slit-shaped pores were formed, with a diameter of 2.12 nm, after 30 minutes of treatment. FTIR results revealed the degradation of the lignin skeleton through the formation of guaiacyl and syringyl units and deformation in the cellulose and hemicelluloses structure. The crystallinity index (CI) increased upon steam treatment for up to 15 min, but after that, a drop in the CI was observed. The crystallite thickness (d200) increased after 15 min of treatment, due to the rearrangement of cellulose chains. However, a further increase in steam treatment duration to 30 min resulted in a decline of d200, followed by an increase in the cellulose II crystalline region and d020. The steam treatment duration of 15-30 min was found to be a critical time interval, which led to increases in the number of mesopores, CI, d200, and the cellulose II region in the poplar wood.

Optimization of steam pretreatment conditions for enzymatic hydrolysis of poplar wood

Holzforschung ◽  
2011 ◽  
Vol 65 (4) ◽  
Author(s):  
Fokko Schütt ◽  
Jürgen Puls ◽  
Bodo Saake
Keyword(s):  
Enzymatic Hydrolysis ◽  
Raw Material ◽  
Steam Pretreatment ◽  
Alkaline Extraction ◽  
Poplar Wood ◽  
Steam Refining ◽  
Severity Factor ◽  
Short Rotation ◽  
Pretreatment Conditions ◽  
Hydrolysis Of

Abstract Steam refining was investigated as a pretreatment for enzymatic hydrolysis of poplar wood from a short rotation plantation. The experiments were carried out without debarking to use an economically realistic raw material. Steam refining conditions were varied in the range of 3–30 min and 170–220°C, according to a factorial design created with the software JMP from SAS Institute Inc., Cary, NC, USA. Predicted steaming conditions for highest glucose and xylose yields after enzymatic hydrolysis were at 210°C and 15 min. Control tests under the optimized conditions verified the predicted results. Further pretreatments without bark showed that the enzymes were not significantly inhibited by the bark. The yield of glucose and xylose was 61.9% of theoretical for the experiments with the whole raw material, whereas the yield for the experiments without bark was 63.6%. Alkaline extraction of lignin from the fibers before enzymatic hydrolysis resulted in an increase of glucose yields from mild pretreated fibers and a decrease for severe pretreated fibers. The extracted lignin had a high content of xylose of up to 14% after very mild pretreatments. On the other hand, molecular weights of the extracted lignin increased substantially after pretreatments with a severity factor above 4. Hence, alkaline extraction of the lignin seems only attractive in a narrow range of steaming conditions.

Accurate and efficient integration for molecular dynamics simulations at constant temperature and pressure

2013 ◽  
Vol 139 (16) ◽  
pp. 164106 ◽  
Author(s):  
Ross A. Lippert ◽  
Cristian Predescu ◽  
Douglas J. Ierardi ◽  
Kenneth M. Mackenzie ◽  
Michael P. Eastwood ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Constant Temperature ◽  
Efficient Integration ◽  
Temperature And Pressure ◽  
Dynamics Simulations

Brief cytochalasin-induced disruption of microfilaments during a critical interval in 1-cell C. elegans embryos alters the partitioning of developmental instructions to the 2-cell embryo

Development ◽  
1990 ◽  
Vol 108 (1) ◽  
pp. 159-172 ◽  
Author(s):  
D.P. Hill ◽  
S. Strome
Keyword(s):  
Cell Cycle ◽  
Asymmetric Cell Division ◽  
Critical Time ◽  
Time Interval ◽  
Critical Interval ◽  
Cell Stage ◽  
C Elegans ◽  
Daughter Cells ◽  
Correct Pattern ◽  
Cell Embryo

We are investigating the involvement of the microfilament cytoskeleton in the development of early Caenorhabditis elegans embryos. We previously reported that several cytoplasmic movements in the zygote require that the microfilament cytoskeleton remain intact during a narrow time interval approximately three-quarters of the way through the first cell cycle. In this study, we analyze the developmental consequences of brief, cytochalasin D-induced microfilament disruption during the 1-cell stage. Our results indicate that during the first cell cycle microfilaments are important only during the critical time interval for the 2-cell embryo to undergo the correct pattern of subsequent divisions and to initiate the differentiation of at least 4 tissue types. Disruption of microfilaments during the critical interval results in aberrant division and P-granule segregation patterns, generating some embryos that we classify as ‘reverse polarity’, ‘anterior duplication’, and ‘posterior duplication’ embryos. These altered patterns suggest that microfilament disruption during the critical interval leads to the incorrect distribution of developmental instructions responsible for early pattern formation. The strict correlation between unequal division, unequal germ-granule partitioning, and the generation of daughter cells with different cell cycle periods observed in these embryos suggests that the three processes are coupled. We hypothesize that (1) an ‘asymmetry determinant’, normally located at the posterior end of the zygote, governs asymmetric cell division, germ-granule segregation, and the segregation of cell cycle timing elements during the first cell cycle, and (2) the integrity or placement of this asymmetry determinant is sensitive to microfilament disruption during the critical time interval.

scholarly journals A 3-In-1 Approach to Evaluate Gas Hydrate Inhibitors

Energies ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 2921
Author(s):  
Narendra Kumar ◽  
Niaz Bahar Chowdhury ◽  
Juan G. Beltran
Keyword(s):  
Constant Temperature ◽  
Gas Hydrates ◽  
Equilibrium Points ◽  
Hydrate Formation ◽  
Temperature Gradients ◽  
Fixed Temperature ◽  
Single Experiment ◽  
Temperature Growth ◽  
Temperature And Pressure ◽  
Methane Gas Hydrates

With a single apparatus and very short experimentation times, we have assessed phase equilibria, apparent kinetics and morphology of methane gas hydrates in the presence of thermodynamic inhibitors ethane-1,2-diol (MEG) and sodium chloride (NaCl); and kinetic hydrate inhibitor polyvinyl-pyrrolidone (PVP). Tight, local temperature control produced highly repeatable crystal morphologies in constant temperature systems and in systems subject to fixed temperature gradients. Hydrate-Liquid-Vapor (HLV) equilibrium points were obtained with minimal temperature and pressure uncertainties ( u T avg = 0 . 13 K and u p = 0 . 005 MPa). By applying a temperature gradient during hydrate formation, it was possible to study multiple subcoolings with a single experiment. Hydrate growth velocities were determined both under temperature gradients and under constant temperature growth. It was found that both NaCl and MEG act as kinetic inhibitors at the studied concentrations. Finally, insights on the mechanism of action of classical inhibitors are presented.

Electrical activity in mesenteric nerves after perfusion of gut lumen

1962 ◽  
Vol 202 (4) ◽  
pp. 725-730 ◽  
Author(s):  
K. N. Sharma ◽  
E. S. Nasset
Keyword(s):  
Amino Acids ◽  
Small Intestine ◽  
Amino Acid ◽  
Electrical Activity ◽  
Constant Temperature ◽  
Amino Acid Mixture ◽  
Acid Mixture ◽  
Temperature And Pressure

Impulses from the peripheral cut end of mesenteric nerves to the intestinal loops of anesthetized cats were recorded oscilloscopically. Dogs with Thiry-Vella loops and with electrodes implanted in mesenteric nerves were used for chronic studies. The loops were perfused with different solutions at constant temperature and pressure. After glucose perfusion of the lumen the increase in frequency of firing was more marked in medium and larger fibers. After perfusion with single amino acids the increase was more conspicuous in smaller fibers. Amigen (amino acid mixture, dextrose, and salts) perfusion resulted in mixed patterns. No appreciable changes were observed with 0.9% NaCl, Tyrode's solution, and 0.025 n NaOH, but a slight increase was obtained with 0.025 n HCl. The possibility of some chemoreceptor mechanism in the small intestine is suggested. Its possible role in ingestion of food is discussed.

scholarly journals The Effect of Time Interval from MRI to Rotator Cuff Repair on Tear Size: Imaged vs. Actual Tear Size

2019 ◽  
Vol 7 (7_suppl5) ◽  
pp. 2325967119S0027
Author(s):  
Amanda J. Naylor ◽  
Michael D. Charles ◽  
Allison Jamie Rao ◽  
Gregory Louis Cvetanovich ◽  
Michael C. O’Brien ◽  
...  
Keyword(s):  
Rotator Cuff ◽  
Rotator Cuff Repair ◽  
Critical Time ◽  
T Test ◽  
Rotator Cuff Tears ◽  
Time Interval ◽  
Consecutive Series ◽  
Full Thickness ◽  
Cuff Repair ◽  
Tear Size

Objectives: Magnetic resonance imaging (MRI) is the advanced imaging modality of choice for the evaluation and diagnosis of full thickness rotator cuff tears (RCT). Tear size progression has been correlated with increasing pain. However, there is little data on tear size progression in symptomatic RCT with regard to time from MRI to actual rotator cuff repair (RCR). The purpose of the study was to evaluate the effect of time (from date of MRI measured tear dimensions to date of RCR measured intraoperative tear dimensions) on tear size progression. Methods: In the course of a study on physical examination manual muscle tests in patients with known full thickness RCT requiring repair, MRI was obtained for each patient undergoing RCR. Tears were measured intraoperatively in the Anterior-Posterior (A-P) and Medial-Lateral (M-L) dimensions with a graduated probe. Location (anterior, central, posterior in the supraspinatus tendon), area of the tear, and anterior band of supraspinatus status (intact/ not intact) were recorded.The preoperative MRI was evaluated by the same examiner blinded to the operative results at least 4 weeks after the RCR and the same parameters measured.There were 64 consecutive shoulders with 40 male, 24 female at an average age of 58 yrs (40-76) that had MRI and underwent RCR. The mean MRI dimensions were: A-P tear:16.53 mm (SD 9.70); M-L tear: 17.3 mm (SD 9.75); Tear area: 366.7 square mm. The average time from preoperative MRI to RCR was 107.3 days (range 12-399 days). Operative mean RCT dimensions were: A-P tear: 18.38 mm (SD 10.0); M-L tear: 14.06 mm (SD 8.15); Tear area: 307.7 square mm.Descriptive statistical analysis with two-sample T-test was performed to determine the temporal effect on tear size from date of MRI to the date of surgery, and whether there was a change.Patients were grouped in the following time cohorts based on the length of time elapsed between the preoperative MRI and date of RCR: ≤1 month, 1 month to 2 months, 2 months to 3 months, 3 months to 9 months, and ≥9 months. The delta, or difference between intraoperative measurements and preoperative MRI measurements, was calculated for each cohort. Results: The t-test revealed a significant time effect with regard to tear size between the MRI and the intraoperative measured tear requiring repair. This was significant for the A-P dimension (p<0.001), the Medial-Lateral dimension (p<0.001), and the total area of the tear (p=0.009). In an attempt to determine a “watershed” or critical time interval where MRI and RCT size correlated, an additional analysis was performed. The change in A-P tear dimension between MRI and RCR findings showed increasing delta with increasing time. Positive mean delta in A-P dimension was seen in the 2-3 month group (2.64), with larger differences seen in the 3 month to 9 month (5.89) and ≥9 month (7.3) groups. A similar trend was seen for mean delta values in the M-L dimension among the cohorts. Conclusion: In a consecutive series of RCTs undergoing repair, the measured MRI dimensions and the intraoperative dimensions were recorded and analyzed. A surgeon can have a level of confidence that the RCT size will correlate with MRI tear size within a certain time frame. There is a significant effect of time on tear size progression from MRI dimensions to actual RCT dimensions at time of repair.

The Diffusivity of Methane Into Air Within Vertical Tubes

1990 ◽  
Vol 112 (4) ◽  
pp. 268-273
Author(s):  
R. Petela ◽  
G. A. Karim
Keyword(s):  
Constant Temperature ◽  
Vertical Cylinder ◽  
Effective Diffusivity ◽  
Concentration Changes ◽  
Temperature And Pressure ◽  
Vertical Tubes

An experimentally based effective diffusivity for methane is derived. Its application for predicting the concentration changes following the release of methane upwards into air at constant temperature and pressure within a vertical cylinder is then examined. Examples relating to the formation and dissipation of flammable mixtures following the release of methane into air are presented and discussed.

scholarly journals Effect of exposure time of pregnant females guppies, Poecilia reticulata Peters, in 17a-methyltestosterone solution on sex ratio of their offsprings

2007 ◽  
Vol 1 (1) ◽  
pp. 47
Author(s):  
M. Zairin Junior ◽  
A. Yunianti ◽  
R.R.S.P.S. Dewi ◽  
Kusman Sumawidjaja
Keyword(s):  
Sex Ratio ◽  
Exposure Time ◽  
Treatment Duration ◽  
Poecilia Reticulata ◽  
Female Offspring ◽  
Control Group ◽  
Time Interval ◽  
Water Flea ◽  
Pregnant Females ◽  
Males And Females

<p>ABSTRACT</p><p>This experiment was carried out to study the effect of female broodstocks immersion in 17amethyltestosterone (MT) solution on sex ratio of their offspring, Three-months old males and females were paired to mate in aquaria for four days.  Broodstocks were fed with frozen blood worm and water flea 2-3 tii-nes daily.  Twelve days after mating, female broodstock were treated by immersing in 2 mg/1 MT solution for 0. 6, 12, 24 and 48 hours.  Birthed guppy babies were collected and reared separately from their parents.  During the rearing period, the babies were fed with artemia nauplius and silkworm until identification for male and female.  Percentage of female offspring in control group were higher than those of male.  Exposure of pregnant females to MT solution for 0, 6, 12, 24, and 48 hours resulted in 42, 1'/o, 51%, 84,6%, 1 00%, dan 100% of males offspring, respectively.  The best result was obtained from 24 hours treatment.  Longer treatment duration tend to shorten time interval between treatment and birth. Key words :  Guppy, 17(x-methyltestosterone, exposure time, broodstock immersion, sex ratio   ABSTRAK Penefitian ini bertuiuan untuk mengetahui pengaruh lama waktu perendaman induk di dalam larutan hormon 17a-metiltestosteron (MT) terhadap nisbah kelamin ikan gapi.  Induk Ikan gapi berumur tiga bulan dikawinkan berpasangan di dalam akuarium selama empat hari Induk diberi pakan cuk merah beku dan kutu air dengan frekuensi 2-3 kali sehari.  Dua belas hari setelah masa perkawinan, induk betina diberi perlakuan berupa perendaman di dalam larutan MT 2 mg/1 selama 0 (kontrol), 6, 12, 24, dan 48 jam.  Anak-anak ikan gapi yang baru lahir dipelihara terpisah dari induknya.  Selama masa pemeliharaan, anak ikan gapi diberi pakan nauplius artemia dan cacing rambut.  Pemeliharaan berlangsung sampai jenis kelamin anak ikan gapi dapat diidentifikasi.  Persentase anak ikan gapi betina pada semua ulangan kontrol lebih tinggi daripada .iantan dengan perbandingan persentase rata-rata 57,9%: 42,1%.  Adapun pada lama waktu perendaman 0, 6, 12, 24, dan 48 jam, menghasilkan persentase anak ikan gapi berfenotip jantan berturut-turut sebesar 42,1%, 51%, 84,6%, 100%, dan 100%.  Lama waktu perendaman terbaik adalah 24 jam.  Selain itu terdapat kecenderungan bahwa semakin lama waktu perendaman semakin cepat kelahirannya. Kata kunci :  Ikan gapi, 17ot-metiltestosteron, lama perendaman, perendaman induk, nisbah kelamin</p>

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