Displaying all 3 publications

  1. Goh YP, Yam WS, Yip FW, Hegde G
    Curr Org Synth, 2021;18(4):352-365.
    PMID: 33530909 DOI: 10.2174/1570179418666210202123935
    INTRODUCTION: This is the first report on chiral polymorphic hydrazine-based asymmetric liquid crystal trimers, 1-[4'-(4''-(5-Cholesteryloxy)carbonyl)butyloxy]-3-[N-benzylideneoxy-N'-(4'''-decyloxybenzylidene) hydrazine] butyloxybenzenes, and 1-[4'-(4''-(10-cholesteryloxy)carbonyl)nonyloxy]-3-[N-benzylideneoxy-N'-(4'''- decyloxybenzylidene)hydrazine]butyloxybenzenes., in which the hydrazine and cholesterol arms were connected via two flexible methylene spacers (n = 3-12 units and m = 4 or 9, respectively) to the central resorcinol core.

    MATERIALS AND METHODS: FT-IR, 1D and 2D NMR spectroscopy, and CHN microanalysis were used to elucidate the structures of the trimers. Differential scanning calorimetry, polarizing optical microscopy and X-ray diffraction were used to study the transitional and phase properties of the trimers, which were length and spacer parity dependent. Trimers with short spacer length in the cholesteryl arm, m = 4 showed an interesting phase sequence of BP/N*-TGBA*-SmA*.

    RESULTS AND DISCUSSION: The TGBA* phase was sensitive to spacer length as it was only observed in trimers with short ester linkage. For the long analogues, m = 9, characteristic visible reflection and a much simpler phase sequence with only N* and SmA* phases were observed.

    CONCLUSION: The X-ray diffraction measurements revealed that layer periodicities of the SmA* phase were approximately half the estimated all-trans molecular length (d/L ≈ 0.44-0.52), thus suggesting that the molecules are either strongly intercalated or bent.

  2. Yuvaraj AR, Yam WS, Chan TN, Goh YP, Hegde G
    Spectrochim Acta A Mol Biomol Spectrosc, 2015 Jan 25;135:1115-22.
    PMID: 25173529 DOI: 10.1016/j.saa.2014.08.009
    The first example of non-symmetric isoflavone-based fast photo-switchable liquid crystals with different functional groups at the terminal position were synthesized and characterized. Polarizing optical microscopy study revealed that the compounds showed least ordered nematic phase. Optical photo switching study exhibited very fast photoisomerization effect in solution. The E-Z and Z-E conversion occurred around 3-5s and 40-700 s respectively. This is also the first example of para-substituted non-symmetric isoflavone liquid crystals exhibiting very fast photo switching property in solution. Argument based on non-symmetrical behaviour might be the reason for the observed behaviour.
  3. Goh YP, Tan PC, Hong JGS, Sulaiman S, Omar SZ
    Int J Gynaecol Obstet, 2021 Dec;155(3):532-538.
    PMID: 33484158 DOI: 10.1002/ijgo.13613
    OBJECTIVE: To evaluate the combined effect of massage and warm compress to the perineum (MassComp) compared with standard "hands-off" in the second stage of labor.

    METHODS: A randomized trial was conducted in a University hospital in Malaysia. Nulliparous women at term who were about to start pushing were randomized to massage during pushing and warm compress to the perineum in between pushes or to standard "hands-off" care. Primary outcome was suturing for perineal injury (episiotomy or tear).

    RESULTS: A total of 156 participants were analyzed based on intention to treat. Perineal repair rates were 53/79 (67%) for MassComp versus 70/77 (91%) for control (relative risk [RR] 0.72, 95% confidence interval [CI] 0.61-0.98, number needed to treat for an additional beneficial outcome [NNTb ] 5, 95% CI 2.83-8.62, P 

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