Raman and infrared spectroscopic characterization of the silicate mineral lamprophyllite

The mineral lamprophyllite is fundamentally a silicate based upon tetrahedral siloxane units with extensive substitution in the formula. Lamprophyllite is a complex group of sorosilicates with general chemical formula given as A2B4C2Si2O7(X)4, where the site A can be occupied by strontium, barium, sodium, and potassium; the B site is occupied by sodium, titanium, iron, manganese, magnesium, and calcium. The site C is mainly occupied by titanium or ferric iron and X includes the anions fluoride, hydroxyl, and oxide. Chemical composition shows a homogeneous phase, composed of Si, Na, Ti, and Fe. This complexity of formula is reflected in the complexity of both the Raman and infrared spectra. The Raman spectrum is characterized by intense bands at 918 and 940 cm−1. Other intense Raman bands are found at 576, 671, and 707 cm−1. These bands are assigned to the stretching and bending modes of the tetrahedral siloxane units.

Raman and infrared spectroscopic study of the borate mineral kaliborite

We have studied the mineral kaliborite. The sample originated from the Inder B deposit, Atyrau Province, Kazakhstan, and is part of the collection of the Geology Department of the Federal University of Ouro Preto, Minas Gerais, Brazil. The mineral is characterized by a single intense Raman band at 756 cm−1 assigned to the symmetric stretching modes of trigonal boron. Raman bands at 1229 and 1309 cm−1 are assigned to hydroxyl in-plane bending modes of boron hydroxyl units. Raman bands are resolved at 2929, 3041, 3133, 3172, 3202, 3245, 3336, 3398, and 3517 cm−1. These Raman bands are assigned to water stretching vibrations. A very intense sharp Raman band at 3597 cm−1 with a shoulder band at 3590 cm−1 is assigned to the stretching vibration of the hydroxyl units. The Raman data are complimented with infrared data and compared with the spectrum of kaliborite downloaded from the Arizona State University database. Differences are noted between the spectrum obtained in this work and that from the Arizona State University database. This research shows that minerals stored in a museum mineral collection age with time. Vibrational spectroscopy enhances our knowledge of the molecular structure of kaliborite.

The role of environmental factors in the spatial distribution of Japanese encephalitis in mainland China

Japanese encephalitis (JE) is the most common cause of viral encephalitis and an important public health concern in the Asia-Pacific region, particularly in China where 50% of global cases are notified. To explore the association between environmental factors and human JE cases and identify the high risk areas for JE transmission in China, we used annual notified data on JE cases at the center of administrative township and environmental variables with a pixel resolution of 1 km×1 km from 2005 to 2011 to construct models using ecological niche modeling (ENM) approaches based on maximum entropy. These models were then validated by overlaying reported human JE case localities from 2006 to 2012 onto each prediction map. ENMs had good discriminatory ability with the area under the curve (AUC) of the receiver operating curve (ROC) of 0.82-0.91, and low extrinsic omission rate of 5.44-7.42%. Resulting maps showed JE being presented extensively throughout southwestern and central China, with local spatial variations in probability influenced by minimum temperatures, human population density, mean temperatures, and elevation, with contribution of 17.94%-38.37%, 15.47%-21.82%, 3.86%-21.22%, and 12.05%-16.02%, respectively. Approximately 60% of JE cases occurred in predicted high risk areas, which covered less than 6% of areas in mainland China. Our findings will help inform optimal geographical allocation of the limited resources available for JE prevention and control in China, find hidden high-risk areas, and increase the effectiveness of public health interventions against JE transmission.

Spatiotemporal transmission dynamics of hemorrhagic fever with renal syndrome in China, 2005-2012

Background Hemorrhagic fever with renal syndrome (HFRS) is a rodent-borne disease caused by many serotypes of hantaviruses. In China, HFRS has been recognized as a severe public health problem with 90% of the total reported cases in the world. This study describes the spatiotemporal dynamics of HFRS cases in China and identifies the regions, time, and populations at highest risk, which could help the planning and implementation of key preventative measures. Methods Data on all reported HFRS cases at the county level from January 2005 to December 2012 were collected from Chinese Center for Disease Control and Prevention. Geographic Information System-based spatiotemporal analyses including Local Indicators of Spatial Association and Kulldorff's space-time scan statistic were performed to detect local high-risk space-time clusters of HFRS in China. In addition, cases from high-risk and low-risk counties were compared to identify significant demographic differences. Results A total of 100,868 cases were reported during 2005–2012 in mainland China. There were significant variations in the spatiotemporal dynamics of HFRS. HFRS cases occurred most frequently in June, November, and December. There was a significant positive spatial autocorrelation of HFRS incidence during the study periods, with Moran's I values ranging from 0.46 to 0.56 (P<0.05). Several distinct HFRS cluster areas were identified, mainly concentrated in northeastern, central, and eastern of China. Compared with cases from low-risk areas, a higher proportion of cases were younger, non-farmer, and floating residents in high-risk counties. Conclusions This study identified significant space-time clusters of HFRS in China during 2005–2012 indicating that preventative strategies for HFRS should be particularly focused on the northeastern, central, and eastern of China to achieve the most cost-effective outcomes.

Interpersonal coordination tendencies supporting the creation/prevention of goal scoring opportunities in futsal

Research on 1vs1 sub-phases in team sports has shown how one player coordinates his/her actions with his/her opponent and the location of a target/goal to attain performance objectives. In this study, we extended this approach to analysis of 5vs5 competitive performance in the team sport of futsal to provide a performance analysis framework that explains how players coordinate their actions to create/prevent opportunities to score goals. For this purpose, we recorded all 10 futsal matches of the 2009 Lusophony Games held in Lisbon. We analysed the displacement trajectories of a shooting attacker and marking defender in plays ending in a goal, a goalkeeper's save, and a defender's interception, at four specific moments during performance: (1) assisting attacker's ball reception; (2) moment of passing; (3) shooter's ball reception, and; (4) shot on goal. Statistical analysis showed that when a goal was scored, the defender's angle to the goal and to the attacker tended to decrease, the attacker was able to move to the same distance to the goal alongside the defender, and the attacker was closer to the defender and moving at the same velocity (at least) as the defender. This study identified emergent patterns of coordination between attackers and defenders under key competitive task constraints, such as the location of the goal, which supported successful performance in futsal.

Global, regional, and national comparative risk assessment of 79 behavioural, environmental and occupational, and metabolic risks or clusters of risks in 188 countries, 1990–2013: a systematic analysis for the Global Burden of Disease Study 2013

Background The Global Burden of Disease, Injuries, and Risk Factor study 2013 (GBD 2013) is the first of a series of annual updates of the GBD. Risk factor quantification, particularly of modifiable risk factors, can help to identify emerging threats to population health and opportunities for prevention. The GBD 2013 provides a timely opportunity to update the comparative risk assessment with new data for exposure, relative risks, and evidence on the appropriate counterfactual risk distribution. Methods Attributable deaths, years of life lost, years lived with disability, and disability-adjusted life-years (DALYs) have been estimated for 79 risks or clusters of risks using the GBD 2010 methods. Risk–outcome pairs meeting explicit evidence criteria were assessed for 188 countries for the period 1990–2013 by age and sex using three inputs: risk exposure, relative risks, and the theoretical minimum risk exposure level (TMREL). Risks are organised into a hierarchy with blocks of behavioural, environmental and occupational, and metabolic risks at the first level of the hierarchy. The next level in the hierarchy includes nine clusters of related risks and two individual risks, with more detail provided at levels 3 and 4 of the hierarchy. Compared with GBD 2010, six new risk factors have been added: handwashing practices, occupational exposure to trichloroethylene, childhood wasting, childhood stunting, unsafe sex, and low glomerular filtration rate. For most risks, data for exposure were synthesised with a Bayesian meta-regression method, DisMod-MR 2.0, or spatial-temporal Gaussian process regression. Relative risks were based on meta-regressions of published cohort and intervention studies. Attributable burden for clusters of risks and all risks combined took into account evidence on the mediation of some risks such as high body-mass index (BMI) through other risks such as high systolic blood pressure and high cholesterol. Findings All risks combined account for 57·2% (95% uncertainty interval [UI] 55·8–58·5) of deaths and 41·6% (40·1–43·0) of DALYs. Risks quantified account for 87·9% (86·5–89·3) of cardiovascular disease DALYs, ranging to a low of 0% for neonatal disorders and neglected tropical diseases and malaria. In terms of global DALYs in 2013, six risks or clusters of risks each caused more than 5% of DALYs: dietary risks accounting for 11·3 million deaths and 241·4 million DALYs, high systolic blood pressure for 10·4 million deaths and 208·1 million DALYs, child and maternal malnutrition for 1·7 million deaths and 176·9 million DALYs, tobacco smoke for 6·1 million deaths and 143·5 million DALYs, air pollution for 5·5 million deaths and 141·5 million DALYs, and high BMI for 4·4 million deaths and 134·0 million DALYs. Risk factor patterns vary across regions and countries and with time. In sub-Saharan Africa, the leading risk factors are child and maternal malnutrition, unsafe sex, and unsafe water, sanitation, and handwashing. In women, in nearly all countries in the Americas, north Africa, and the Middle East, and in many other high-income countries, high BMI is the leading risk factor, with high systolic blood pressure as the leading risk in most of Central and Eastern Europe and south and east Asia. For men, high systolic blood pressure or tobacco use are the leading risks in nearly all high-income countries, in north Africa and the Middle East, Europe, and Asia. For men and women, unsafe sex is the leading risk in a corridor from Kenya to South Africa. Interpretation Behavioural, environmental and occupational, and metabolic risks can explain half of global mortality and more than one-third of global DALYs providing many opportunities for prevention. Of the larger risks, the attributable burden of high BMI has increased in the past 23 years. In view of the prominence of behavioural risk factors, behavioural and social science research on interventions for these risks should be strengthened. Many prevention and primary care policy options are available now to act on key risks.

Fernando Pessoan ortonyymi ja heteronyymit modernistis-romanttisena myyttinä

Tutkimuksessani selvitän portugalilaisrunoilija Fernando Pessoan (1888-1935) heteronyymejä ja ortonyymiä modernistis-romanttisena myyttinä. Myytin piirteet paljastuivat Pessoan omia kirjoituksia ja runoja tutkimalla ja käyttämällä apuna Pessoa-tutkimusta. Tutkimusaineistonani ovat Pessoa-ortonyymin Mensagem-runoelma ja ”Autopsykografia”-runo, Álvaro de Campoksen vuonna 1917 Portugal Futurista –lehdessä julkaistu ”Ultimatum”-runomanifesti, Alberto Caeiron ”Guardador de Rebanhos”-runosikermä sekä Ricardo Reisin ”Oodit”-kokonaisuuteen kuuluvat runot: n:ro 59 ”Acima da verdade estão os deuses” (”Totuuden yläpuolella ovat jumalat”, 1914), n:ro 66 ”Olho os campos, Neera” (”Katson peltoja, Neera”, 1917), n:ro 181 ”Amo o que vejo” (”Rakastan sitä mitä näen”, 1934), n:ro 175 ”Estas só. Ninguem o sabe.” (”Olet yksin. Kukaan ei tiedä sitä”, 1933). Tutkimuksessani romanttisen runouden keskeisinä piirteinä pidetään uskoa taiteilijaneroon (geniukseen), mimeettiseen illuusioon (taide tavoittelee ulkoisen todellisuuden toisintamista mahdollisimman autenttisena) ja tekijän ja kokijan eli subjektin ja objektin erottamiseen toisistaan. Käsitänkin modernin runon tutkimuksessani hylänneen monia entisiä käsityksiä ja vastakkainasetteluja muun muassa tekijän ja ulkopuolisen maailman, mielen ja kielen välillä. Näitä moderneja ”rikkomuksia” identifioin ja määrittelen Pessoan heteronyymien runoudessa. Tutkimukseni apukäsitteitä ovat vilpittömyys ja autenttisuus, jotka kuvaavat runoilijan suhdetta itseensä ja muihin ja joita on pohtinut mm. Lionel Trilling teoksessaan Sincerity and authencity. Romanttisessa runoudessa suhde yhteisöön muodostui ensisijaisesti suhteessa omaan itseen, yhtenäiseen minuuteen nojaavan vilpittömyyden kautta, modernissa runoudessa hajanaisuutta ja yksilön suhdetta myös yhteisöön korostavan autenttisuuden avulla. Tutkimuksessani havaitsin, että Pessoa on jo tuotantonsa alusta lähtien kehittänyt tietoisesti modernistis-romanttista myyttiä – päätelmää tukivat niin Pessoan omat kirjoitukset kuin runoanalyysini. Pessoa ennusti ensimmäisen kerran romanttiseen nerotaiteilijaan vertautuvaa ”supra-Camõesia” ”A nova poesia Portuguesa Sociologicamente considerada” –esseessään vuonna 1912. Campoksen ”Ultimatum”-manifestissa puhuja uskoi muutaman useita kymmeniä persoonallisuuksia hallitsevan ”Synteesi-Ihmisen” tai ”supra-Camõesin” ilmestymiseen. ”Synteesi-Ihmisen” oli määrä palauttaa kukoistukseensa lamaantuneessa tilassa ollut Portugalin kirjallisuus uuteen kukoistukseensa. Eräänlaisen perustan koko myytille loi vuotta ennen Pessoan kuolemaa julkaistu Mensagem (suom. Viesti), jossa runoilija esittää saudosistisen ja sebastianistisen perustan. Teixeira de Pascoaesin kehittämä saudosismi näkyy Mensagemissa uskona Portugalin valtion perustajien ja laajentajien – löytöretkeilijöiden – edustamaan voittoisaan lusofoniseen mentaliteettiin, jonka Pessoa asettaa niin kansakunnan, runoilijan kuin ihmisen ihanteeksi. Toinen Mensagemissa esiintyvä myytin rakennusaine on sebastianismi eli usko kuningas Sebastianin (1554-1578) paluuseen. ”Synteesi-Ihminen”/”supra-Camões” oli reinkarnoitunut Sebastian, jonka piti palauttaa kansa ja kulttuuri kukoistukseensa lusofonisen valloittajamentaliteetin avulla. ”Autopsykografia”-runossaan Pessoa esittää puolestaan runoilijaa koskevan modernin poetiikan ongelmineen: esittävyyteen perustuva taide etäännyttää kokijan – taiteilijan – aina väistämättä ensimmäisestä, spontaanista ja luonnollisesta kokemuksesta ja tekee hänestä teeskentelijän ja simulakrumien (Baudrillard), toisen tason merkityksen tuottajan. ”Autopsykografian” moderni poetiikka koskee myös lukijaa, joka ei tavoita runoilijan välittämää merkitystä vaan kolmannen tason merkityksen. ”Autopsykografian” runous- ja ihmiskäsitys on moderni: runoilija on ammattimainen teeskentelijä, lähtökohtaisesti vilpillinen ja epäautenttinen. Pessoa ja Campos edustavat Pessoan objektiivisia heteronyymejä ja myytin modernia puolta. Pessoan subjektiiviset heteronyymit Reis ja Caeiro täydentävät objektiviisia, modernin ihmisen ahdistusta ja levottomuutta ilmaisseita Pessoaa ja Camposta ollen luonteeltaan romanttisia vilpittömyyden kannattajia. Caeiro arvosti näköaistia yli muiden aistien. Hänen tavoitteenaan oli katsoa aina kuin ensimmäistä kertaa, spontaanisti ja välittömästi kuin lapsi. Reis puolestaan korosti harmoniaa jumalten, ihmisten ja luonnon välillä ja uskoi kohtuullisiin aistinautintoihin. Molemmat muodostivat Pessoan myytin romanttisen puolen yhteisessä halussaan hylätä sosiaaliset roolit ja opetukset ja palata kohti yksilöllistä minää. Vilpittömyys ja autenttisuus ovat Caeiron ja Reisin ohjeita runoilijalle ja ihmiselle. Objektiiviset ja subjektiiviset heteronyymit yhdessä muodostavat modernistis-romanttisen myytin, joka kokonaisuudessaan on looginen: objektiiviset heteronyymit esittivät teeskentelyn, vilpillisyyden ja moderniuden ongelmat; subjektiiviset tarjosivat ratkaisua niihin, poisopettelua sosiaalisista rooleista ja rohkeutta mennä kohti omaa yksilöllistä minuutta.

International contact lens prescribing in 2014

Since the late 1990s, the International Contact Lens Prescribing Survey Consortium has prospectively gathered information about 285,000 contact lens fits from more than 50 countries. This article presents our 14th annual summary of current trends published in Contact Lens Spectrum. With only minor differences in the distribution of our surveys among markets, we have continued to adopt the same approach throughout the past 18 years. Through national coordinators, we approach contact lens prescribers in each country and ask them to record information about the first 10 patients whom they fit with contact lenses after receipt of our survey form. The information collected is generic, and respondents are weighted to reflect the volume of contact lens fits undertaken by each. For this 2014 report, we present information about 25,179 contact lens fits from 32 countries...

International contact lens prescribing in 2015

We have been collecting data on worldwide contact lens prescribing habits for almost 20 years. Over this time period, we have amassed prospective information about 315,000 contact lens fits in 59 countries. This article marks our 15th report in Contact Lens Spectrum and features a breakdown of more than 23,000 contact lens fits in 34 markets. As in previous years, our international network of coordinators distributed survey forms to eyecare practitioners in their market who then recorded generic information about the first 10 patients fit with contact lenses after receipt. Information is gathered about patient age and gender; whether the contact lenses are prescribed as a new fit or a refit; contact lens material, design, and replacement frequency; number of intended days per week of use; wearing modality; and care system. Contact lens fits are weighted to reflect the number of fits undertaken by each eyecare practitioner. The study data were entered and processed at the University of Manchester and at the University of Waterloo.

Rapid increase in scrub typhus incidence in Mainland China, 2006-2014

Scrub typhus is a vector-borne disease, which has recently reemerged in China. In this study, we describe the distribution and incidence of scrub typhus cases in China from 2006 to 2014 and quantify differences in scrub typhus cases with respect to sex, age, and occupation. The results of our study indicate that the annual incidence of scrub typhus has increased during the study period. The number of cases peaked in 2014, which was 12.8 times greater than the number of cases reported in 2006. Most (77.97%) of the cases were reported in five provinces (Guangdong, Yunnan, Anhui, Fujian, and Shandong). Our study also demonstrates that the incidence rate of scrub typhus was significantly higher in females compared to males (P < 0.001) and was highest in the 60–69 year age group, and that farmers had a higher incidence rate than non farmers (P < 0.001). Different seasonal trends were identified in the number of reported cases between the northern and southern provinces of China. These findings not only demonstrate that China has experienced a large increase in scrub typhus incidence, but also document an expansion in the geographic distribution throughout the country.

Spatiotemporal clustering analysis and risk assessments of human cutaneous anthrax in China, 2005–2012

Objective To investigate the epidemic characteristics of human cutaneous anthrax (CA) in China, detect the spatiotemporal clusters at the county level for preemptive public health interventions, and evaluate the differences in the epidemiological characteristics within and outside clusters. Methods CA cases reported during 2005–2012 from the national surveillance system were evaluated at the county level using space-time scan statistic. Comparative analysis of the epidemic characteristics within and outside identified clusters was performed using using the χ2 test or Kruskal-Wallis test. Results The group of 30–39 years had the highest incidence of CA, and the fatality rate increased with age, with persons ≥70 years showing a fatality rate of 4.04%. Seasonality analysis showed that most of CA cases occurred between May/June and September/October of each year. The primary spatiotemporal cluster contained 19 counties from June 2006 to May 2010, and it was mainly located straddling the borders of Sichuan, Gansu, and Qinghai provinces. In these high-risk areas, CA cases were predominantly found among younger, local, males, shepherds, who were living on agriculture and stockbreeding and characterized with high morbidity, low mortality and a shorter period from illness onset to diagnosis. Conclusion CA was geographically and persistently clustered in the Southwestern China during 2005–2012, with notable differences in the epidemic characteristics within and outside spatiotemporal clusters; this demonstrates the necessity for CA interventions such as enhanced surveillance, health education, mandatory and standard decontamination or disinfection procedures to be geographically targeted to the areas identified in this study.

A generic method of engagement to elicit regional coastal management options

Stakeholder engagement is important for successful management of natural resources, both to make effective decisions and to obtain support. However, in the context of coastal management, questions remain unanswered on how to effectively link decisions made at the catchment level with objectives for marine biodiversity and fisheries productivity. Moreover, there is much uncertainty on how to best elicit community input in a rigorous manner that supports management decisions. A decision support process is described that uses the adaptive management loop as its basis to elicit management objectives, priorities and management options using two case studies in the Great Barrier Reef, Australia. The approach described is then generalised for international interest. A hierarchical engagement model of local stakeholders, regional and senior managers is used. The result is a semi-quantitative generic elicitation framework that ultimately provides a prioritised list of management options in the context of clearly articulated management objectives that has widespread application for coastal communities worldwide. The case studies show that demand for local input and regional management is high, but local influences affect the relative success of both engagement processes and uptake by managers. Differences between case study outcomes highlight the importance of discussing objectives prior to suggesting management actions, and avoiding or minimising conflicts at the early stages of the process. Strong contributors to success are a) the provision of local information to the community group, and b) the early inclusion of senior managers and influencers in the group to ensure the intellectual and time investment is not compromised at the final stages of the process. The project has uncovered a conundrum in the significant gap between the way managers perceive their management actions and outcomes, and community's perception of the effectiveness (and wisdom) of these same management actions.

Co-distribution and co-infection of chikungunya and dengue viruses

BACKGROUND Chikungunya and dengue infections are spatio-temporally related. The current review aims to determine the geographic limits of chikungunya, dengue and the principal mosquito vectors for both viruses and to synthesise current epidemiological understanding of their co-distribution. METHODS Three biomedical databases (PubMed, Scopus and Web of Science) were searched from their inception until May 2015 for studies that reported concurrent detection of chikungunya and dengue viruses in the same patient. Additionally, data from WHO, CDC and Healthmap alerts were extracted to create up-to-date global distribution maps for both dengue and chikungunya. RESULTS Evidence for chikungunya-dengue co-infection has been found in Angola, Gabon, India, Madagascar, Malaysia, Myanmar, Nigeria, Saint Martin, Singapore, Sri Lanka, Tanzania, Thailand and Yemen; these constitute only 13 out of the 98 countries/territories where both chikungunya and dengue epidemic/endemic transmission have been reported. CONCLUSIONS Understanding the true extent of chikungunya-dengue co-infection is hampered by current diagnosis largely based on their similar symptoms. Heightened awareness of chikungunya among the public and public health practitioners in the advent of the ongoing outbreak in the Americas can be expected to improve diagnostic rigour. Maps generated from the newly compiled lists of the geographic distribution of both pathogens and vectors represent the current geographical limits of chikungunya and dengue, as well as the countries/territories at risk of future incursion by both viruses. These describe regions of co-endemicity in which lab-based diagnosis of suspected cases is of higher priority.

Functional dissection of alternative secretory pathways in the yeast S. cerevisiae

Eukaryotic cells are characterized by having a subset of internal membrane compartments, each one with a specifi c identity, structure and function. Proteins destined to be targeted to the exterior of the cell need to enter and progress through the secretory pathway. Transport of secretory proteins from the endoplasmic reticulum (ER) to the Golgi takes place by the selective packaging of proteins into COPII-coated vesicles at the ER membrane. Taking advantage of the extensive genetic tools available for S. cerevisiae we found that Hsp150, a yeast secretory glycoprotein, selectively exited the ER in the absence of any of the three Sec24p family members. Sec24p has been thought to be an essential component of the COPII coat and thus indispensable for exocytic membrane traffic. Next we analyzed the ability of Hsp150 to be secreted in mutants, where post-Golgi transport is temperature sensitive. We found that Hsp150 could be selectively secreted under conditions where the exocyst component Sec15p is defective. Analysis of the secretory vesicles revealed that Hsp150 was packaged into a subset of known secretory vesicles as well as in a novel pool of secretory vesicles at the level of the Golgi. Secretion of Hsp150 in the absence of Sec15p function was dependent of Mso1p, a protein capable of interacting with vesicles intended to fuse with the plasma membrane, with the SNARE machinery and with Sec1p. This work demonstrated that Hsp150 is capable of using alternative secretory pathways in ER-to-Golgi and Golgi-to-plasma membrane traffi c. The sorting signals, used at both stages of the secretory pathway, for secretion of Hsp150 were different, revealing the highly dynamic nature and spatial organization of the secretory pathway. Foreign proteins usually misfold in the yeast ER. We used Hsp150 as a carrier to assist folding and transport of heterologous proteins though the secretory pathway to the culture medium in both S. cerevisiae and P. pastoris. Using this technique we expressed Hsp150Δ-HRP and developed a staining procedure, which allowed the visualization of the organelles of the secretory pathway of S. cerevisiae.

Adsorption and Unfolding of Lysozyme at a Polarized Aqueous-Organic Liquid Interface

The adsorption of proteins at the interface between two immiscible electrolyte solutions has been found to be key to their bioelectroactivity at such interfaces. Combined with interfacial complexation of organic phase anions by cationic proteins, this adsorption process may be exploited to achieve nanomolar protein detection. In this study, replica exchange molecular dynamics simulations have been performed to elucidate for the first time the molecular mechanism of adsorption and subsequent unfolding of hen egg white lysozyme at low pH at a polarized 1,2-dichloroethane/water interface. The unfolding of lysozyme was observed to occur as soon as it reaches the organic−aqueous interface,which resulted in a number of distinct orientations at the interface. In all cases, lysozyme interacted with the organic phase through regions rich in nonpolar amino acids, such that the side chains are directed toward the organic phase, whereas charged and polar residues were oriented toward the aqueous phase. By contrast, as expected, lysozyme in neat water at low pH does not exhibit significant structural changes. These findings demonstrate the key influence of the organic phase upon adsorption of lysozyme under the influence of an electric field, which results in the unfolding of its structure.