Preparation of DPPC liposomes using probe-tip sonication: Investigating intrinsic factors affecting temperature phase transitions

Preparation of DPPC liposomes using probe-tip sonication: investigating intrinsic factors affecting temperature phase transitions

10.1101/742437 ◽

2019 ◽

Author(s):

Monica D. Rieth ◽

Andrew Lozano

Keyword(s):

Phase Transition ◽

Phase Transitions ◽

Effective Means ◽

Temperature Phase ◽

Scanning Calorimetry ◽

Factors Affecting ◽

Dipalmitoyl Phosphatidylcholine ◽

Intrinsic Factors ◽

Physical Effects ◽

Therapeutic Compounds

AbstractLiposomes are an important tool and have gained much attention for their promise as an effective means of delivering small therapeutic compounds to targeted sites. In an effort to establish an effective method to produce liposomes from the lipid, dipalmitoyl-phosphatidylcholine or DPPC, we have found important aspects that must be taken into consideration. Here, we used probe-tip sonication to prepare liposomes on a batch scale. During this process we uncovered interesting steps in their preparation that altered the thermodynamic properties and phase transitions of the resulting liposome mixtures. Using differential scanning calorimetry to assess this we found that increasing the sonication time had the most dramatic effect on our sample, producing almost an entirely separate phase transition relative to the main phase transition. This result is consistent with reports from the current literature. We also highlight a smaller transition, which we attribute to traces of unincorporated lipid that seems to gradually disappear as the total lipid concentration decreases. Overall, sonication is an effective means of producing liposomes, but we cannot assert this method is optimal in producing them with precise physical properties. Here we highlight the physical effects at play during this process.

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High temperature phase transitions and proton conductivity in some kdp-family crystals

Ferroelectrics ◽

10.1080/00150198908007907 ◽

1989 ◽

Vol 100 (1) ◽

pp. 135-141 ◽

Cited By ~ 113

Author(s):

A. I. Baranov ◽

V. P. Khiznichenko ◽

L. A. Shuvalov

Keyword(s):

Phase Transitions ◽

High Temperature ◽

Proton Conductivity ◽

High Temperature Phase ◽

Temperature Phase

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Clinical analysis of tracheobronchial foreign body aspiration in children: a focus on external and intrinsic factors

BMC Surgery ◽

10.1186/s12893-021-01089-3 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Weigang Gan ◽

Ning Xiao ◽

Yiyuan Feng ◽

Danmei Zhou ◽

Juanjuan Hu ◽

...

Keyword(s):

Foreign Body ◽

Pediatric Patients ◽

Treatment Delay ◽

Rigid Bronchoscopy ◽

Foreign Body Aspiration ◽

External Factors ◽

Factors Affecting ◽

Intrinsic Factors ◽

Common Location ◽

Tracheobronchial Foreign Body

Abstract Background Tracheobronchial foreign body aspiration (TFBA) is a critical disease in children and is extremely dangerous, even life-threatening. The factors affecting the occurrence and prognosis of TFBA are complex. The purpose of this study is to examine the external and intrinsic factors affecting clinical features of TFBA in West China and propose potential effective intervention measures. Methods We retrospectively analyzed the clinical data of pediatric patients diagnosed with TFBA with foreign bodies (FBs) removed by rigid bronchoscopy under general anesthesia at the otolaryngology department from December 2017 to November 2018. The data included age, sex, clinical symptoms, type and location of FB, guardians, prehospital duration and residence of these pediatric patients. Results The ratio of males (72) to females (53) was 1.4:1. Children aged from 1 to 3 years accounted for 76% (95/125) of patients. Cough, continuous fever and dyspnea were the primary symptoms. The right primary bronchus was the most common location of FB detection by rigid bronchoscopy (67 cases, 53.6%). Organic FBs were most common in our study. Guardians of patients significantly differed in the rural (parents 16, grandparents 31) and urban (parents 52, grandparents 26) groups (χ2 = 12.583, p = 0.000). More children in the rural group than in the urban group had a treatment delay longer than 72 h. More children in the group with no history of FB aspiration (12, 25%) than in the group with prior FB aspiration had a treatment delay longer than 72 h. Conclusion Pediatric TFBA is a common emergency in otolaryngology. Age, sex, tracheobronchial anatomy and other physiological elements were defined as intrinsic factors, while guardians, residence, FB species and prehospital time were defined as external factors of TFBA. External and intrinsic factors both influence the occurrence and progression of TFBA. It is extremely important to take effective measures to control external factors, which can decrease morbidity and mortality.

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Fate of false vacua in holographic first-order phase transitions

Journal of High Energy Physics ◽

10.1007/jhep12(2020)200 ◽

2020 ◽

Vol 2020 (12) ◽

Author(s):

Francesco Bigazzi ◽

Alessio Caddeo ◽

Aldo L. Cotrone ◽

Angel Paredes

Keyword(s):

Phase Transitions ◽

Chiral Symmetry ◽

Metastable Phase ◽

Chiral Symmetry Breaking ◽

Model Parameters ◽

Temperature Phase ◽

Thin Wall ◽

Critical Temperatures ◽

First Order ◽

First Order Phase

Abstract Using the holographic correspondence as a tool, we study the dynamics of first-order phase transitions in strongly coupled gauge theories at finite temperature. Considering an evolution from the large to the small temperature phase, we compute the nucleation rate of bubbles of true vacuum in the metastable phase. For this purpose, we find the relevant configurations (bounces) interpolating between the vacua and we compute the related effective actions. We start by revisiting the compact Randall-Sundrum model at high temperature. Using holographic renormalization, we compute the derivative term in the effective bounce action, that was missing in the literature. Then, we address the full problem within the top-down Witten-Sakai-Sugimoto model. It displays both a confinement/deconfinement and a chiral symmetry breaking/restoration phase transition which, depending on the model parameters, can happen at different critical temperatures. For the confinement/deconfinement case we perform the numerical analysis of an effective description of the transition and also provide analytic expressions using thick and thin wall approximations. For the chiral symmetry transition, we implement a variational approach that allows us to address the challenging non-linear problem stemming from the Dirac-Born-Infeld action.

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