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Record W1607106830

X-ray diffraction of a gram-negative bacterial membrane mimetic

2009· dissertation· en· W1607106830 on OpenAlexfundno aff
Panteha. Razavi

Bibliographic record

VenueBrock University Digital Repository (Brock University) · 2009
Typedissertation
Languageen
FieldMaterials Science
TopicX-ray Diffraction in Crystallography
Canadian institutionsnot available
FundersBrock University
KeywordsGramDiffractionMembraneMaterials scienceChemistryPhysicsBiologyBacteriaOpticsGeneticsBiochemistry
DOInot available

Abstract

fetched live from OpenAlex

This thesis applies x-ray diffraction to measure he membrane structure of lipopolysaccharides and
\nto develop a better model of a LPS bacterial melilbrane that can be used for biophysical research on
\nantibiotics that attack cell membranes. \\iVe ha'e Inodified the Physics department x-ray machine
\nfor use 3.'3 a thin film diffractometer, and have lesigned a new temperature and relative humidity
\ncontrolled sample cell.\\Ve tested the sample eel: by measuring the one-dimensional electron density
\nprofiles of bilayers of pope with 0%, 1%, 1G :VcJ, and 100% by weight lipo-polysaccharide from
\nPse'udo'lTwna aeTuginosa.
\nBackground
\nVVe now know that traditional p,ntibiotics ,I,re losing their effectiveness against ever-evolving
\nbacteria. This is because traditional antibiotic: work against specific targets within the bacterial
\ncell, and with genetic mutations over time, themtibiotic no longer works.
\nOne possible solution are antimicrobial peptides. These are short proteins that are part of the
\nimmune systems of many animals, and some of them attack bacteria directly at the membrane of
\nthe cell, causing the bacterium to rupture and die. Since the membranes of most bacteria share
\ncommon structural features, and these featuret, are unlikely to evolve very much, these peptides
\nshould effectively kill many types of bacteria wi Lhout much evolved resistance.
\nBut why do these peptides kill bacterial cel: '3 , but not the cells of the host animal? For gramnegative
\nbacteria, the most likely reason is that t Ileir outer membrane is made of lipopolysaccharides
\n(LPS), which is very different from an animal :;ell membrane. Up to now, what we knovv about
\nhow these peptides work was likely done with r !10spholipid models of animal cell membranes, and
\nnot with the more complex lipopolysa,echaricies, If we want to make better pepticies, ones that we
\ncan use to fight all types of infection, we need a more accurate molecular picture of how they \\vork.
\nThis will hopefully be one step forward to the ( esign of better treatments for bacterial infections.

Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.

How this classification was reachedexpand

Full frame distilled prediction

Teacher imitation

Not calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.

metaresearch head score (Codex)0.000
metaresearch head score (Gemma)0.000
Version: codex-gemma-dda1882f352aValidation status: machine_predicted_unvalidated
Candidate categoriesMeta-epidemiology (narrow)
Consensus categoriesnone
DomainCandidate signal: none · Consensus signal: none
Study designCandidate signal: Bench or experimental · Consensus signal: none
GenreCandidate signal: Empirical · Consensus signal: Empirical
Teacher disagreement score0.681
Threshold uncertainty score0.999

Codex and Gemma teacher scores by category

CategoryCodexGemma
Metaresearch0.0000.000
Meta-epidemiology (narrow)0.0010.001
Meta-epidemiology (broad)0.0010.001
Bibliometrics0.0020.001
Science and technology studies0.0010.000
Scholarly communication0.0000.003
Open science0.0010.000
Research integrity0.0010.001
Insufficient payload (model declined to judge)0.0000.000

Machine scores (provisional)

The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.

Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.

Opus teacher head0.008
GPT teacher head0.198
Teacher spread0.191 · how far apart the two teachers sit on this one work
Validation statusscore_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it

Classification

machine, unvalidated

Machine predicted; a candidate call from one teacher head, not a consensus.

Study designBench or experimental
Domainnot available
GenreEmpirical

How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".

Quick stats

Citations0
Published2009
Admission routes1
Has abstractyes

Explore more

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