Phase diagram of model anisotropic particles with octahedral symmetry

We computed the phase diagram for a system of model anisotropic particles with six attractive patches in an octahedral arrangement. We chose to study this model for a relatively narrow value of the patch width where the lowest-energy configuration of the system is a simple cubic crystal. At this value of the patch width, there is no stable vapour-liquid phase separation, and there are three other crystalline phases in addition to the simple cubic crystal that is most stable at low pressure. Firstly, at moderate pressures, it is more favourable to form a body-centred cubic crystal, which can be viewed as two interpenetrating, and almost non-interacting, simple cubic lattices.Secondly, at high pressures and low temperatures, an orientationally ordered face-centred cubic structure becomes favourable. Finally, at high temperatures a face-centred cubic plastic crystal is the most stable solid phase.Comment: 12 pages,10 figure

The stability of a crystal with diamond structure for patchy particles with tetrahedral symmetry

The phase diagram of model anisotropic particles with four attractive patches in a tetrahedral arrangement has been computed at two different values for the range of the potential, with the aim of investigating the conditions under which a diamond crystal can be formed. We find that the diamond phase is never stable for our longer-ranged potential. At low temperatures and pressures, the fluid freezes into a body-centred-cubic solid that can be viewed as two interpenetrating diamond lattices with a weak interaction between the two sublattices. Upon compression, an orientationally ordered face-centred-cubic crystal becomes more stable than the body-centred-cubic crystal, and at higher temperatures a plastic face-centered-cubic phase is stabilized by the increased entropy due to orientational disorder. A similar phase diagram is found for the shorter-ranged potential, but at low temperatures and pressures, we also find a region over which the diamond phase is thermodynamically favored over the body-centred-cubic phase. The higher vibrational entropy of the diamond structure with respect to the body-centred-cubic solid explains why it is stable even though the enthalpy of the latter phase is lower. Some preliminary studies on the growth of the diamond structure starting from a crystal seed were performed. Even though the diamond phase is never thermodynamically stable for the longer-ranged model, direct coexistence simulations of the interface between the fluid and the body-centred-cubic crystal and between the fluid and the diamond crystal show that, at sufficiently low pressures, it is quite probable that in both cases the solid grows into a diamond crystal, albeit involving some defects. These results highlight the importance of kinetic effects in the formation of diamond crystals in systems of patchy particles.Comment: 15 pages, 13 figure

Effect of calcium carbide on the rate of ripening of Ambon Bananas (Musa paradisiaca Var. Sapientum (L). Kunt)

Bananas are one of the most widely consumed sources of nutrients in Indonesia. Generally, bananas are consumed fresh and processed into various snacks. This leads to an increased demand for bananas in the market. However, the natural ripening process takes 7-8 days after harvest, which is a long time to meet consumer demand. One solution is to use calcium carbide to accelerate fruit ripening. The reason for using calcium carbide is that it is readily available and inexpensive, so banana producers use carbide as a fruit ripening agent.  The objective of this study was to determine the effects of calcium carbide on fruit ripening of Ambon bananas. The method used was a laboratory experiment with a post-test-only control group design. There were three treatments with calcium carbide concentrations of 12%, 6%, and 3%, and positive control, namely rapining with rice. Data were analyzed descriptive qualitative by collecting, presenting, reducing, and conclusions. The process of fruit ripening can be observed using the variables of color, texture and aroma. The results obtained were differences in color, texture, and aroma at concentrations of 12%, 6%, and 3% based on the length of aging. Based on the color parameter, the concentration of 6% and 12% showed a blackish yellow/brown color, while the concentration of 3% was yellow with black spots. The texture parameters of the 6% and 12% concentrations had a very soft texture, while the 3% concentration had a smooth texture. The aroma parameters of the 12%, 6%, and 3% concentrations had a rancid aroma on day six, while days one, two, and three were fragrant. The conclusion is that using calcium carbide at different concentrations affects the rate of fruit ripening. The higher the concentration of calcium carbide used, the faster the respiration rate of the bananas, thus initiating the ripening proces

Frequency of human papillomavirus infection and genotype distribution among women with known cytological diagnosis in a Southern Italian region

Introduction. In the Puglia region (South Italy) about 200 new hospitalizations for cervical cancer are registered every year. The study investigated the frequency of Human Papillomavirus (HPV) infection and the genotype distribution of HPV in a sample of women with known cytology attending the outpatient clinics of four Gynecological Departments of the University of Bari over a four-year period (2005-2008). Methods. Cervical samples from 1,168 women were analyzed for the presence of HPV-DNA through Polymerase Chain Reaction (PCR) in L1 region and reverse hybridization. The cytological results were associated with HPV positivity and type-specific prevalence. Results. Overall, HPV infection was found in 355 (30.4%) women. HPV-DNA was found in 34.4% of women with a cytological diagnosis of ASCUS, in 46.8% of women with Low-grade Squamous Intraepithelial Lesion (LSIL) and in 87.0% of women with High-grade Squamous Intraepithelial Lesion (HSIL)/carcinoma. Also 16.0% of women with normal Pap smear were found to be HPV-DNA positive. The most common HPV genotype was type 16 found in 27.3% of positives, followed by type 53 (11.5%), type 66 (9.2%) and type 31 (9.0%). HPV genotype 18 was found in 6.4% of positives. Types 16 or 18 were detected in about 34% (120/355) of all infected women, in about 33% of LSIL and in 60% of HSIL/ carcinoma HPV-positive women. Among low risk (LR) genotypes, type 61 was found in 10.7% of HPV positive women, type 62 in 8.4%, type 42 in 8.1% and type CP6108 in 7.8%. Discussion and conclusions. The findings of the study give evidence that HPV infection is frequent in the studied cohort of women. The most widespread genotypes found were 16 and 53. These data may represent a benchmark for future evaluation after the recent introduction of vaccination against HPV in 12-year-old girls

Disconnecting Symmetry Breaking from Seeded Growth for the Reproducible Synthesis of High Quality Gold Nanorods

https://pubs.acs.org/doi/suppl/10.1021/acsnano.8b09658/suppl_file/nn8b09658_si_002.pdfOne of the major difficulties hindering the widespread application of colloidal anisotropic plasmonic nanoparticles is the limited robustness and reproducibility of multistep synthetic methods. We demonstrate herein that the reproducibility and reliability of colloidal gold nanorod (AuNR) synthesis can be greatly improved by disconnecting the symmetry-breaking event from the seeded growth process. We have used a modified silver-assisted seeded growth method in the presence of the surfactant hexadecyltrimethylammonium bromide and n-decanol as a co-surfactant to prepare small AuNRs in high yield, which were then used as seeds for the growth of high quality AuNR colloids. Whereas the use of n-decanol provides a more-rigid micellar system, the growth on anisotropic seeds avoids sources of irreproducibility during the symmetry breaking step, yielding uniform AuNR colloids with narrow plasmon bands, ranging from 600 to 1270 nm, and allowing the fine-tuning of the final dimensions. This method provides a robust route for the preparation of high quality AuNR colloids with tunable morphology, size, and optical response in a reproducible and scalable manner

Quantum contributions in the ice phases: the path to a new empirical model for water -- TIP4PQ/2005

With a view to a better understanding of the influence of atomic quantum delocalisation effects on the phase behaviour of water, path integral simulations have been undertaken for almost all of the known ice phases using the TIP4P/2005 model, in conjunction with the rigid rotor propagator proposed by Muser and Berne [Phys. Rev. Lett. 77, 2638 (1996)]. The quantum contributions then being known, a new empirical model of water is developed (TIP4PQ/2005) which reproduces, to a good degree, a number of the physical properties of the ice phases, for example densities, structure and relative stabilities.Comment: Accepted for publication in the Journal of Chemical Physic

Low Sensitivity of the Formol-Ethyl Acetate Sedimentation Concentration Technique in Low-Intensity Schistosoma japonicum Infections

Schistosoma japonicum is parasitic fluke (worm) found in China, Indonesia and the Philippines. A lot of effort has been put into combating the parasite, and the result has been a large drop in the number of infected people over the last decades. The average infected person also now has few worms, and hence excretes few eggs in stool. This has made it increasingly difficult to get a correct diagnosis by the diagnostic tests traditionally used. Tests based on detecting eggs in stool can be false-negative and tests detecting antibodies can be false-positive due to persisting antibodies or antibodies from other worm infections. Hence there is a need for new diagnostic strategies. Formol-ethyl acetate sedimentation concentration is a technique for detecting eggs in stool by microscopy, but has not to our knowledge been evaluated for S. japonicum. We compared the technique, using a single stool sample and a commercial preparation kit, with three tests traditionally used in the endemic countries (Kato-Katz thick smear, hatching test and indirect hemagglutination antibody detection). The sedimentation technique detected disappointing few positives and seems not to be an advantage in the diagnosis of low-intensity S. japonicum infection, compared to the traditionally used tests