Effect of Heat Treatment on Dilute Solution Properties of Sugar Beet Pectin

Beet Pectin (SBP) polysaccharide. Aqueous solution properties of these samples have been studied using Ubbelohde capillary viscometer in the dilute regime. Intrinsic viscosity [?] was estimated for different SBP solution samples prepared from heat-treated SBP powdered samples with different heating time. Results suggest that heat treatment has a significant effect on solution behavior of SBP samples. Intrinsic viscosities decreased with increasing heating time indicating that heat-treated SBP molecules are compact than the untreated one and the compactness increases with increasing heating time at 80°C. The intrinsic viscosities of these samples were plotted as a function of the corresponding molecular weight of the samples and can be expressed by a power law. The power law exponent was estimated as 1.4 indicating that pectin molecules takes the conformation of stiff polymer chains in dilute solution. Dhaka Univ. J. Sci. 61(1): 117-123, 2013 (January) DOI: http://dx.doi.org/10.3329/dujs.v61i1.15107

Dispersion dependence of linewidth in actively mode-locked ring lasers

We studied the spectral linewidth narrowing of wavelength-swept actively mode-locked ring lasers (AMLLs). The numerical calculations for the static-state AMLL led us to predict that anomalous dispersion would narrows the linewidth. We examined the effect experimentally using AMLL setups for normal and anomalous dispersive cavities via the normal or inverse use of a linearly chirped fiber Bragg grating. The experiment indicated that the cavity with anomalous dispersion always generates narrower linewidth lasers than its normal dispersion equivalent. The cavity with anomalous dispersion also achieved a 0.08 nm linewidth. Using the anomalous dispersion setup, we observed instantaneous linewidth broadening during wavelength sweeping. Although the coherence of AMLL decreased drastically when the sweep rate became very rapid beyond a single roundtrip, narrow-linewidth lasing was observed within a single roundtrip. In summary, we demonstrated the use of 150 kHz wavelength sweeping with a 40-nm range and a 2.7-m short-length anomalous dispersion cavity.

A prelinguistic gestural universal of human communication

Several cognitive accounts of human communication argue for a language-independent, prelinguistic basis of human communication and language. The current study provides evidence for the universality of a prelinguistic gestural basis for human communication. We used a standardized, semi-natural elicitation procedure in seven very different cultures around the world to test for the existence of preverbal pointing in infants and their caregivers. Results were that by 10-14 months of age, infants and their caregivers pointed in all cultures in the same basic situation with similar frequencies and the same proto-typical morphology of the extended index finger. Infants' pointing was best predicted by age and caregiver pointing, but not by cultural group. Further analyses revealed a strong relation between the temporal unfolding of caregivers' and infants' pointing events, uncovering a structure of early prelinguistic gestural conversation. Findings support the existence of a gestural, language-independent universal of human communication that forms a culturally shared, prelinguistic basis for diversified linguistic communication.

Bactericidal effect of HM-242, a novel disinfectant, against Pseudomonas aeruginosa

The bactericidal effect of HM-242, a novel antimicrobial agent, against Pseudomonas aeruginosa was investigated by using Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) values and the time-kill study. Furthermore, we also morphologically investigated its effect against P. aeruginosa by use of transmission electron microscopy (TEM) in comparison with that of chlorhexidine digluconate (CHG). The bactericidal activity of HM-242 after 1 min incubation evaluated by MBC was 25 microg/mL, while the MBC of CHG was 50 microg/mL. In the time-kill study, the killing activity of HM-242 with 25 microg/mL incubation was stronger than that of CHG with 50 microg/mL incubation. MIC values of HM-242 and CHG against P. aeruginosa were 25 microg/mL and 12.5 microg/mL, respectively. We also observed via TEM the morphological changes in the test bacteria after being treated with each drug at 1/2MBC, 1MBC, 2MBC and 4MBC after 1 min or 5 min incubation. Under treatment with the same concentration of the test drugs, the cell damage with HM-242 treatment was greater than that with CHG. The appearance of empty cells was recognized at the concentrations greater than 50 microg/mL (2MBC) of HM-242 and 200 microg/mL of CHG (4MBC) after 1 min exposure, although no cell damage was evident below these concentrations. The cell-damaging effect against the test strain was dependent on the drug concentration and incubation time. The release of cell components and bleb formation were also recognized. These results suggest that HM-242 has more potent bactericidal activity in low concentrations under shorter time treatments than CHG. Both HM-242 and CHG act on the cell membrane and cell wall of P. aeruginosa and can destroy the cell integrity. We finally emphasize that HM-242 as well as CHG might be a suitable disinfectant for use in the medical field.

Influence of ethanol on physical state of freeze-dried mannitol

PURPOSE

The purpose of this study is to characterize freeze-dried mannitol prepared from an ethanol-containing solution as a function of the ethanol ratio, mannitol concentration, and annealing in the freeze-drying cycle.

METHODS

The characteristics of the freeze-dried mannitol were evaluated by X-ray diffractometry (XRD) and differential scanning calorimetry (DSC). The reconstitution time was measured for the freeze-dried solids as well as the residual moisture and ethanol by Karl-Fischer titration and gas chromatography, respectively.

RESULTS

The XRD pattern of 5% (w/v) mannitol freeze-dried from aqueous solution with no annealing cycle showed all the five characteristic peaks at 13.6 degrees and 17.2 degrees 2theta for the alpha polymorph, at 14.6 degrees and 23.4 degrees 2theta for the beta polymorph and at 9.7 degrees 2theta for the delta polymorph. The addition of ethanol to the initial solutions resulted in only a peak at 9.7 degrees 2theta, indicating the presence of only the delta polymorph, regardless of the ethanol ratio in the initial solutions used [10, 20, 30, and 40% (v/v)]. However, annealing during freeze-drying influenced the XRD pattern; in particular, for the solid prepared from the 10% ethanol solution. Annealing of the 10% ethanol solution promoted the formation of the alpha polymorph and produced a different peak that might be attributable to another polymorph. In DSC thermograms, an endotherm and a subsequent exotherm were found in the temperature range of 150 degrees C to 160 degrees C, which corresponded to the transition of the delta form to alpha or beta forms. The magnitude of this transition was smaller as the ethanol ratio increased for the solids from ethanol-containing solutions with an annealing cycle. In other words, annealing of the ethanol-containing solutions promoted delta polymorph formation in the lyophiles. In addition, the mannitol concentration affected the polymorphism in freeze-dried solids prepared from aqueous and 10% ethanol solutions. Addition of ethanol in the initial solution, in particular, at a lower ethanol level (10% v/v), and a higher concentration of mannitol could also promote the generation of lumps in freeze-dried solids during reconstitution, and result in longer reconstitution time. The residual moisture levels were less than 0.5%, and residual ethanol levels were less than 0.1%, irrespective of the formulation used.

CONCLUSIONS

The physical state and reconstitution time of the freeze-dried mannitol appears to be a complex function of the ethanol and mannitol concentrations in the initial solution before freeze-drying and of annealing during the freeze-drying process.

Subambient behavior of mannitol in ethanol-water co-solvent system

PURPOSE

The purpose of this study is to characterize the freezing behavior of mannitol in ethanol-water co-solvent systems in comparison with the corresponding aqueous solution.

METHODS

Subambient differential scanning calorimetry (DSC) and microscopy techniques were used to investigate the freezing behavior of mannitol in aqueous solutions and in ethanol-water co-solvent systems.

RESULTS

The DSC thermogram of the frozen aqueous solution, which was warmed after cooling at 5.0 degrees C/min, consisted of a glass transition, an endothermic transition, and a crystallization exotherm from mannitol, respectively. The thermograms of ethanol-containing solutions were different in view of including some thermal events attributable to ethanol hydrates. The glass transition of amorphous mannitol was also observed in the thermograms, but became unclear with increasing ethanol in the co-solvent system. The microscopy experiments enabled understanding of the subambient behavior of mannitol. Ethanol was largely removed by vacuum drying rather than freeze-drying. In addition, such manipulations as annealing during the freezing process and slower cooling (0.5 degrees C/min) enhanced the crystallization of mannitol in the frozen system.

CONCLUSIONS

In the presence of ethanol, crystallization of mannitol was inhibited under subambient conditions. Annealing or slower cooling promoted the crystallization of mannitol during the freezing process.

Dissociation of NEPH1 from nephrin is involved in development of a rat model of focal segmental glomerulosclerosis

Focal segmental glomerulosclerosis (FSGS) is a disease showing severe proteinuria, and the disease progresses to end-stage kidney failure in many cases. However, the pathogenic mechanism of FSGS is not well understood. The slit diaphragm (SD), which bridges the neighboring foot processes of glomerular epithelial cells, is understood to function as a barrier of the glomerular capillary wall. To investigate the role of SD dysfunction in the development of FSGS, we analyzed the expression of SD-associated molecules in rat adriamycin-induced nephropathy, a mimic of FSGS. The staining of the SD molecules nephrin, podocin, and NEPH1 had already shifted to a discontinuous dotlike pattern at the initiation phase of the disease, when neither proteinuria nor any morphological alterations were detected yet. The alteration of NEPH1 expression was the most evident among the molecules examined, and NEPH1 was dissociated from nephrin at the initiation phase. On day 28, when severe proteinuria was detected and sclerotic changes were already observed, alteration of the expressions of nephrin, podocin, and NEPH1 worsened, but no alteration in the expression of other SD-associated molecules or other podocyte molecules was detected. It is postulated that the dissociation of NEPH1 from nephrin initiates proteinuria and that the SD alteration restricted in these molecules plays a critical role in the development of sclerotic changes in FSGS.

Boroxol Rings in Liquid and Vitreous B2O3 from First Principles

We investigate the structural and vibrational properties of glassy B2O3 using first-principles molecular dynamics simulations. In particular, we determine the boroxol rings fraction f for which there is still no consensus in the literature. Two numerical models containing either a low or a high level of boroxol rings are tested against a gamut of experimental probes (static structure factor, Raman, 11B and 17O NMR data). We show that only the boroxol-rich model (f=75%) can reproduce the full set of observables. Total-energy calculations show that at the glass density, boroxol-rich structures are favored by about 6 kcal/(mol boroxol). Finally, the liquid state is explored in the 2,000-4,000 K range and a reduction of f to 10%-20% is obtained.