Protection of high-frequency low-intensity pulsed electric fields and brain-derived neurotrophic factor for SH-SY5Y cells against hydrogen peroxide-induced cell damage

Neurodegenerative diseases (NDDs) pose a significant global health threat. In particular, Alzheimer disease, the most common type causing dementia, remains an incurable disease. Alzheimer disease is thought to be associated with an imbalance of reactive oxygen species (ROS) in neurons, and scientists considered ROS modulation as a promising strategy for novel remedies. In the study, human neural cell line SH-SY5Y was used in probing the effect of combining noninvasive high-frequency low-intensity pulsed electric field (H-LIPEF) and brain-derived neurotrophic factor (BDNF) in protection against hydrogen peroxide (H2O2)-induced neuron damage. Our result finds that the combination approach has intensified the neuroprotective effect significantly, perhaps due to H-LIPEF and BDNF synergistically increasing the expression level of the phosphorylated epidermal growth factor receptor (p-EGFR), which induces the survival-related mitogen-activated protein kinases (MAPK) proteins. The study confirmed the activation of extracellular signal-regulated kinase (ERK) and the downstream pro-survival and antioxidant proteins as the mechanism underlying neuron protection. These findings highlighted the potential of H-LIPEF combined with BDNF in the treatment of NDDs. Furthermore, BDNF-mimetic drugs combining with noninvasive H-LIPEF to patients is a promising approach worthy of further research. This points to strategies for selecting drugs to cooperate with electric fields in treating neurodegenerative disorders.

Study on the effect of a triple cancer treatment of propolis, thermal cycling-hyperthermia, and low-intensity ultrasound on PANC-1 cells

To reduce side effects and enhance treatment efficacy, study on combination therapy for pancreatic cancer, a deadly cancer, has gained much attraction in recent years. In this study, we propose a novel triple treatment combining propolis and two physical stimuli-thermal cycling-hyperthermia (TC-HT) and low-intensity ultrasound (US). The study found that, after the triple treatment, the cell viability of a human cancer cell line PANC-1 decreased to a level 80% less than the control, without affecting the normal pancreatic cells. Another result was excessive accumulation of reactive oxygen species (ROS) after the triple treatment, leading to the amplification of apoptotic pathway through the MAPK family and mitochondrial dysfunction. This study, to the best of our knowledge, is the first attempt to combine TC-HT, US, and a natural compound in cancer treatment. The combination of TC-HT and US also promotes the anticancer effect of the heat-sensitive chemotherapy drug cisplatin on PANC-1 cells. It is expected that optimized parameters for different agents and different types of cancer will expand the methodology on oncological therapy in a safe manner.

Thermal cycling-hyperthermia ameliorates Aβ25-35-induced cognitive impairment in C57BL/6 mice

Despite continuation of some controversies, Alzheimer's disease (AD), the most common cause of dementia nowadays, has been widely believed to derive mainly from excessive β-amyloid (Aβ) aggregation, that would increase reactive oxygen species (ROS) and induce neuroinflammation, leading to neuron loss and cognitive impairment. Existing drugs on Aβ have been ineffective or offer only temporary relief at best, due to blood-brain barrier or severe side effects. The study employed thermal cycling-hyperthermia (TC-HT) to ease the Aβ-induced cognitive impairments and compared its effect with continuous hyperthermia (HT) in vivo. It established an AD mice model via intracerebroventricular (i.c.v.) injection of Aβ25-35, proving that TC-HT is much more effective in alleviating its performance decline in Y-maze and novel object recognition (NOR) tests, in comparison with HT. In addition, TC-HT also exhibits a better performance in decreasing the hippocampal Aβ and β-secretase (BACE1) expressions as well as the neuroinflammation markers-ionized calcium-binding adapter molecule 1 (Iba-1) and glial fibrillary acidic protein (GFAP) levels. Furthermore, the study finds that TC-HT can elevate more protein expressions of insulin degrading enzyme (IDE) and antioxidative enzyme superoxide dismutase 2 (SOD2) than HT. In sum, the study proves the potential of TC-HT in AD treatment, which can be put into application with the use of focused ultrasound (FUS).

Multiple Nucleocapsid Structural Forms of Shrimp White Spot Syndrome Virus Suggests a Novel Viral Morphogenetic Pathway

White spot syndrome virus (WSSV) is a very large dsDNA virus. The accepted shape of the WSSV virion has been as ellipsoidal, with a tail-like extension. However, due to the scarcity of reliable references, the pathogenesis and morphogenesis of WSSV are not well understood. Here, we used transmission electron microscopy (TEM) and cryogenic electron microscopy (Cryo-EM) to address some knowledge gaps. We concluded that mature WSSV virions with a stout oval-like shape do not have tail-like extensions. Furthermore, there were two distinct ends in WSSV nucleocapsids: a portal cap and a closed base. A C14 symmetric structure of the WSSV nucleocapsid was also proposed, according to our Cryo-EM map. Immunoelectron microscopy (IEM) revealed that VP664 proteins, the main components of the 14 assembly units, form a ring-like architecture. Moreover, WSSV nucleocapsids were also observed to undergo unique helical dissociation. Based on these new results, we propose a novel morphogenetic pathway of WSSV.

Subunit vaccines with a saponin-based adjuvant boost humoral and cellular immunity to MERS coronavirus

Middle East respiratory syndrome coronavirus (MERS-CoV) outbreaks have constituted a public health issue with drastic mortality higher than 34%, necessitating the development of an effective vaccine. During MERS-CoV infection, the trimeric spike protein on the viral envelope is primarily responsible for attachment to host cellular receptor, dipeptidyl peptidase 4 (DPP4). With the goal of generating a protein-based prophylactic, we designed a subunit vaccine comprising the recombinant S1 protein with a trimerization motif (S1-Fd) and examined its immunogenicity and protective immune responses in combination with various adjuvants. We found that sera from immunized wild-type and human DPP4 transgenic mice contained S1-specific antibodies that can neutralize MERS-CoV infection in susceptible cells. Vaccination with S1-Fd protein in combination with a saponin-based QS-21 adjuvant provided long-term humoral as well as cellular immunity in mice. Our findings highlight the significance of the trimeric S1 protein in the development of MERS-CoV vaccines and offer a suitable adjuvant, QS-21, to induce robust and prolonged memory T cell response.

Effect of high-frequency low-intensity pulsed electric field on protecting SH-SY5Y cells against hydrogen peroxide and β-amyloid-induced cell injury via ERK pathway

As the most common type of neurodegenerative diseases (NDDs), Alzheimer's disease (AD) is thought to be caused mainly by the excessive aggregation of β-amyloid protein (Aβ). However, a growing number of studies have found that reactive oxygen species (ROS) play a key role in the onset and progression of AD. The present study aimed to probe the neuroprotective effect of high-frequency low-intensity pulsed electric field (H-LIPEF) for SH-SY5Y cells against hydrogen peroxide (H2O2) and Aβ-induced cytotoxicity. By looking in a systematic way into the frequency- and amplitude-dependent neuroprotective effect of pulsed electric field (PEF), the study finds that H-LIPEF at 200 Hz produces the optimal protective effect for SH-SY5Y cells. The underlying mechanisms were confirmed to be due to the activation of extracellular signal-regulated kinase (ERK) pathway and the downstream prosurvival and antioxidant proteins. Because the electric field can be modified to focus on specific area in a non-contact manner, the study suggests that H-LIPEF holds great potential for treating NDDs, whose effect can be further augmented with the administering of drugs or natural compounds at the same time.

Thermal cycling protects SH-SY5Y cells against hydrogen peroxide and β-amyloid-induced cell injury through stress response mechanisms involving Akt pathway

Neurodegenerative diseases (NDDs) are becoming a major threat to public health, according to the World Health Organization (WHO). The most common form of NDDs is Alzheimer’s disease (AD), boasting 60–70% share. Although some debates still exist, excessive aggregation of β-amyloid protein (Aβ) and neurofibrillary tangles has been deemed one of the major causes for the pathogenesis of AD. A growing number of evidences from studies, however, have suggested that reactive oxygen species (ROS) also play a key role in the onset and progression of AD. Although scientists have had some understanding of the pathogenesis of AD, the disease still cannot be cured, with existing treatment only capable of providing a temporary relief at best, partly due to the obstacle of blood-brain barrier (BBB). The study was aimed to ascertain the neuroprotective effect of thermal cycle hyperthermia (TC-HT) against hydrogen peroxide (H₂O₂) and Aβ-induced cytotoxicity in SH-SY5Y cells. Treating cells with this physical stimulation beforehand significantly improved the cell viability and decreased the ROS content. The underlying mechanisms may be due to the activation of Akt pathway and the downstream antioxidant and prosurvival proteins. The findings manifest significant potential of TC-HT in neuroprotection, via inhibition of oxidative stress and cell apoptosis. It is believed that coupled with the use of drugs or natural compounds, this methodology can be even more effective in treating NDDs.

Application of non-invasive low-intensity pulsed electric field with thermal cycling-hyperthermia for synergistically enhanced anticancer effect of chlorogenic acid on PANC-1 cells

Most existing cancer treatments involve high-cost chemotherapy and radiotherapy, with major side effects, prompting effort to develop alternative treatment modalities. It was reported that the combination of thermal-cycling hyperthermia (TC-HT) and phenolic compound exhibited a moderate cytotoxic effect against human pancreatic cancer PANC-1 cells. In this study, we investigate the efficacy of triple combination in PANC-1 cancer cells by adopting low-intensity pulsed electric field (LIPEF) to couple with TC-HT and CGA (chlorogenic acid). The study finds that this triple combination can significantly impede the proliferation of PANC-1 cells, with only about 20% viable cells left after 24h, whereas being non-toxic to normal cells. The synergistic activity against the PANC-1 cells was achieved by inducing G2/M phase arrest and apoptosis, which were associated with up-regulation of p53 and coupled with increased expression of downstream proteins p21 and Bax. Further mechanism investigations revealed that the cytotoxic activity could be related to mitochondrial apoptosis, characterized by the reduced level of Bcl-2, mitochondrial dysfunction, and sequential activation of caspase-9 and PARP. Also, we found that the triple treatment led to the increase of intracellular reactive oxygen species (ROS) production. Notably, the triple treatment-induced cytotoxic effects and the elevated expression of p53 and p21 proteins as well as the increased Bax/Bcl-2 ratio, all could be alleviated by the ROS scavenger, N-acetyl-cysteine (NAC). These findings indicate that the combination of CGA, TC-HT, and LIPEF may be a promising modality for cancer treatment, as it can induce p53-dependent cell cycle arrest and apoptosis through accumulation of ROS in PANC-1 cells.

Thermal cycling as a novel thermal therapy to synergistically enhance the anticancer effect of propolis on PANC‑1 cells

Hyperthermia (HT) has shown potential in cancer therapy. In particular, it appears to sensitize cancer cells to chemotherapy. However, a major concern associated with HT is that the thermal dosage applied to the tumor cells may also harm the normal tissue cells. Besides, the drugs used in HT are conventional chemotherapy drugs, which may cause serious side effects. The present study demonstrated a novel methodology in HT therapy called thermal cycle (TC)‑HT. With this strategy, a therapeutic window with a maximum synergistic effect was created by combining TC‑HT with natural compounds, with minimal unwanted cell damage. The natural compound propolis was selected, and the synergistic anticancer effect of TC‑HT and propolis was investigated in pancreatic cancer cells. The present results demonstrated for the first time that TC‑HT could enhance the anticancer effect of propolis on PANC‑1 cancer cells through the mitochondria‑dependent apoptosis pathway and cell cycle arrest. Combined treatment greatly suppressed mitochondrial membrane potential, which is an important indicator of damaged and dysfunctional mitochondria. Furthermore, the cell cycle‑regulating protein cell division cycle protein 2 was downregulated upon combined treatment, which prevented cellular progression into mitosis. The present study offers the first report, to the best of our knowledge, on the combination of TC‑HT with a natural compound for pancreatic cancer treatment. It is anticipated that this methodology may be a starting point for more sophisticated cancer treatments and may thereby improve the quality of life of many patients with cancer.

Thermal cycling-hyperthermia in combination with polyphenols, epigallocatechin gallate and chlorogenic acid, exerts synergistic anticancer effect against human pancreatic cancer PANC-1 cells

Hyperthermia (HT) has shown feasibility and potency as an anticancer therapy. Administration of HT in the chemotherapy has previously enhanced the cytotoxicity of drugs against pancreatic cancer. However, the drugs used when conducting these studies are substantially conventional chemotherapeutic agents that may cause unwanted side effects. Additionally, the thermal dosage in the treatment of cancer cells could also probably harm the healthy cells. The purpose of this work was to investigate the potential of the two natural polyphenolic compounds, epigallocatechin gallate (EGCG) and chlorogenic acid (CGA), as heat synergizers in the thermal treatment of the PANC-1 cells. Furthermore, we have introduced a unique strategy entitled the thermal cycling-hyperthermia (TC-HT) that is capable of providing a maximum synergy and minimal side effect with the anticancer compounds. Our results demonstrate that the combination of the TC-HT and the CGA or EGCG markedly exerts the anticancer effect against the PANC-1 cells, while none of the single treatment induced such changes. The synergistic activity was attributed to the cell cycle arrest at the G2/M phase and the induction of the ROS-dependent mitochondria-mediated apoptosis. These findings not only represent the first in vitro thermal synergistic study of natural compounds in the treatment of pancreatic cancer, but also highlight the potential of the TC-HT as an alternative strategy in thermal treatment.

Enhanced anticancer effects of low-dose curcumin with non-invasive pulsed electric field on PANC-1 cells

Background

Pulsed electric field (PEF) has been considered as a cell permeability enhancing agent for cancer treatment. Nevertheless, application of PEF for conventional electrochemo-therapy is usually at high intensity, and contact or even invasive electrodes are typically used, which may cause unwanted side effects. In this study, a non-invasive way of applying low intensity, non-contact PEF was adopted to study its combination effect with herb, curcumin, against pancreatic cancer cells and the mechanism involved.

Methods

The pancreatic cancer PANC-1 cells were treated with curcumin and PEF alone or in combination, and MTT assay was used to determine the viability of PANC-1 cells. Apoptosis and uptake of curcumin were analyzed by microscopy and flow cytometry. Western blot was further performed to evaluate the expression of apoptotic proteins.

Results

Our results demonstrated that PEF synergized with curcumin to inhibit the proliferation of PANC-1 cells in a field strength- and dose-dependent manner and caused apoptotic death of PANC-1 cells. The apoptotic induction of combination treatment was characterized by an increase in Bax/Bcl-2 ratio, and cleavage of caspase-8, -9, and -3. Moreover, the increase of curcumin uptake via electro-endocytosis was clearly observed in the cells following the exposure of PEF.

Conclusion

We show for the first time that a non-contact approach using low intensity electric field in a pulsed waveform could enhance the anticancer effect of low-dose curcumin on PANC-1 cells through triggering both extrinsic and intrinsic pathways. The findings highlight the potential of this alternative treatment, non-invasive electric field and curcumin, to increase therapeutic efficacy with minimum cytotoxicity and side effects, which may provide a new aspect of cancer treatment in combination of PEF and other anticancer agents.

Studies on the non-invasive anticancer remedy of the triple combination of epigallocatechin gallate, pulsed electric field, and ultrasound

Cancer is one of the most troublesome diseases and a leading cause of death worldwide. Recently, novel treatments have been continuously developed to improve the disadvantages of conventional therapies, such as prodigious expenses, unwanted side effects, and tumor recurrence. Here, we provide the first non-invasive treatment that has combined epigallocatechin gallate (EGCG), the most abundant catechin in green tea, with a low strength pulsed electric field (PEF) and a low energy ultrasound (US). It has been observed that the cell viability of human pancreatic cancer PANC-1 was decreased approximately to 20% of the control after this combination treatment for 72 h. Besides, the combined triple treatment significantly reduced the high tolerance of HepG2 cells to the EGCG-induced cytotoxicity and similarly exhibited compelling proliferation-inhibitory effects. We also found the combined triple treatment increased the intracellular reactive oxygen species (ROS) and acidic vesicles, and the EGCG-induced inhibition of Akt phosphorylation was dramatically intensified. In this study, the apoptosis inhibitor Z-VAD-FMK and the autophagy inhibitor 3-MA were, respectively, shown to attenuate the anticancer effects of the triple treatment. This indicates that the triple treatment-induced autophagy was switched from cytoprotective to cytotoxic, and hence, cooperatively caused cell death with the apoptosis. Since the EGCG is easily accessible from the green tea and mild for a long-term treatment, and the non-invasive physical stimulations could be modified to focus on a specific location, this combined triple treatment may serve as a promising strategy for anticancer therapy.

Liquid-crystal-modulated correlated color temperature tunable light-emitting diode with highly accurate regulation

A precise correlated color temperature (CCT) tuning method for light-emitting diodes (LEDs) has been developed and is demonstrated in this article. By combining LEDs and a liquid crystal (LC) cell, a light source with continuous CCT variation along a straight track on the chromaticity diagram is achieved. Moreover, the manner of CCT variation can be modulated by choosing appropriate LEDs and phosphors to yield a variation going from 3800 K to 6100 K with the track near the black-body locus. By adapting various developed LC technologies for diverse demands, the performance and applications of LEDs can be greatly improved.

Enhancement of electro-optical properties of twisted nematic liquid crystals by doping aromatic hydrocarbon liquids

In this paper, doping liquid materials to enhance the electro-optical (EO) properties of twisted nematic liquid crystals (NLCs) was presented. Two aromatic hydrocarbon (AH) liquids, toluene and 1-methylnaphthalene, were chosen as dopants in order to lower the driving voltage and response time of the NLCs. A 18% decrease in driving voltage and response time was achieved by doping 10 wt% toluene into NLCs. The main reason of this phenomenon is due to a large amount of reduction in the rotational viscosity of AH liquids doped NLCs. This method provides an easy and potential choice for applications in various LC display systems.

Supramolecular liquid-crystal gels formed by polyfluorene-based π-conjugated polymer for switchable anisotropic scattering device

To overcome the problem of high driving voltage and low contrast ratio in the switchable scattering device of conventional liquid-crystal (LC) physical gel, a new type of supramolecular LC physical gel has been developed and fabricated through the fibrous self-assembly of the polyfluorene-based π-conjugated polymer, poly(9,9-dioctylfluorene-alt-benzothiadiazole) (F8BT), in nematic LC mixture E7. It was found that the rubbed interface between the LC molecules and polyimide layer can induce the LC physical gels to demonstrate fantastic light scattering characteristic. The gels with oriented self-assembled supramolecular structures exhibiting significant anisotropic light scattering in the main-chain direction of the F8BT molecules under an extremely low driving voltage (ca. 2.7 V) are reported for the first time. In addition, the contrast ratio can be reached exceeding 1000. In contrast to conventional LC physical gels, the large reduction of driving voltages of the supramolecular gel provides great possibility for application in various electro-optical devices such as tunable polarizers, transflective displays, and polarized light modulators.

Low-dose dextromethorphan, a NADPH oxidase inhibitor, reduces blood pressure and enhances vascular protection in experimental hypertension

Background

Vascular oxidative stress may be increased with age and aggravate endothelial dysfunction and vascular injury in hypertension. This study aimed to investigate the effects of dextromethorphan (DM), a NADPH oxidase inhibitor, either alone or in combination treatment, on blood pressure (BP) and vascular protection in aged spontaneous hypertensive rats (SHRs).

Methodology/Principal Findings

Eighteen-week-old WKY rats and SHRs were housed for 2 weeks. SHRs were randomly assigned to one of the 12 groups: untreated; DM monotherapy with 1, 5 or 25 mg/kg/day; amlodipine (AM, a calcium channel blocker) monotherapy with 1 or 5 mg/kg/day; and combination therapy of DM 1, 5 or 25 mg/kg/day with AM 1 or 5 mg/kg/day individually for 4 weeks. The in vitro effects of DM were also examined. In SHRs, AM monotherapy dose-dependently reduced arterial systolic BP. DM in various doses significantly and similarly reduced arterial systolic BP. Combination of DM with AM gave additive effects on BP reduction. DM, either alone or in combination with AM, improved aortic endothelial function indicated by ex vivo acetylcholine-induced relaxation. The combination of low-dose DM with AM gave most significant inhibition on aortic wall thickness in SHRs. Plasma total antioxidant status was significantly increased by all the therapies except for the combination of high-dose DM with high-dose AM. Serum nitrite and nitrate level was significantly reduced by AM but not by DM or the combination of DM with AM. Furthermore, in vitro treatment with DM reduced angiotensin II-induced reactive oxygen species and NADPH oxidase activation in human aortic endothelial cells.

Conclusions/Significance

Treatment of DM reduced BP and enhanced vascular protection probably by inhibiting vascular NADPH oxidase in aged hypertensive animals with or without AM treatment. It provides the potential rationale to a novel combination treatment with low-dose DM and AM in clinical hypertension.

Lead distribution in blood and organs of mice exposed to lead by vein injection

To study lead (Pb) distribution in organs and blood in the case of Pb poisoning, mice were firstly exposed to Pb as 0.1 mL or 0.2 mL of lead nitrate solution (0.1 mg/mL) by vein injection every other day. Then, after metabolic absorption, the Pb level in the blood and organs of the mice was measured using flame atomic absorption spectrometry. The resulting data showed that 93% of Pb in blood was accumulated in red cells, but this percentage slightly decreased with increasing exposure time and injection volume. For other target organs, the highest Pb level was in the kidney, followed by the liver, spleen, heart and lung, and was lowest in the brain. Moreover, the Pb level in the heart and brain is in a growth trend at all times for 0.1 mL and 0.2 mL of Pb injection exposure in 15 days, while the growth trend of Pb in other target organs become slow for 0.2 mL of injection after exposure Pb 11 days.

Numerical and experimental study of velocity and temperature characteristics in a ventilated enclosure with underfloor ventilation systems

Airflow and temperature distributions in an enclosure with heat sources ventilated by floor supply jets with floor or ceiling air exit vents were investigated using experimental and numerical approaches. These ventilation configurations represent the floor return or the top return underfloor ventilation systems found in real applications. Experiments and numerical simulations were performed on a full-sized environmental chamber. The results reveal that the temperature stratification in the enclosure highly depended on the thermal length scale of the floor supply jets. When the thermal length scale of the supply jet was >>1, temperature stratification was minor for all tested heat densities and air distribution methods. Significant vertical temperature gradients occurred when the jet thermal length scale was <<1. Changes in air distribution methods also became significant for temperature stratification at small supply jet thermal length scales. Temperature stratification also affected the terminal height of the momentum-dominant region of the vertical buoyant supply jets. The applicability of these results to underfloor ventilation design was also discussed.

PRACTICAL IMPLICATIONS

In designing underfloor ventilation systems, supply jet conditions and heat load density have to be considered to avoid thermal discomfort because of excessive temperature stratifications. This study demonstrated, by both numerical simulations and experiments, that thermal length scale can be used as a design indicator to predict thermal stratifications under a floor return and a top return underfloor ventilation setting.

New hexatic liquid phase observed in lyotropic thin films

An intermediate surface hexatic phase between the liquid and the crystalline phases has been found for the first time in a lyotropic lamellar liquid-crystal system. This phase is highly unusual in that it has long-range sixfold bond-orientational order but liquidlike nearest-neighbor positional correlations, and could represent a significant departure from our current understanding of defect-mediated melting in two dimensions.

Experimental study of ventilation performance and contaminant distribution of underfloor ventilation systems vs. traditional ceiling-based ventilation system

Ventilation performance and pollutant distribution in a traditional ceiling-type ventilation system, a top-return (TR)-type and a floor-return (FR)-type underfloor ventilation systems were performed in a controlled experimental room. Tracer gas method was utilized to determine the age of air and the contaminant removal effectiveness. Tobacco smoke was also introduced to study the particle-phase pollutant distribution. The TR system delivered conditioned air more efficiently in the occupied zone and exhibited higher gaseous contaminant removal effectiveness. It also showed the lowest smoke particle concentration compared with the other two systems. The FR system showed better ventilation performance over the mixing system at the space that was close to the floor supply outlet and at the lower height level. The FR system was less effective than the TR system in removing buoyant tobacco smoke particles at the upper part of the room indicating its highly localized characteristics. Differences in experimental conditions between the present and the previous studies and their effects on the experimental results are discussed. In general, the experimental data suggested that both types of the underfloor ventilation systems have the potential of improving air quality at the breathing zone over the ceiling-based mixing system with suitable designs.

PRACTICAL IMPLICATIONS

This study shows the possibility of improving indoor air quality using underfloor ventilation systems compared with the traditional ceiling-based ventilation system. However, different configurations of the underfloor ventilation system show various ventilation characteristics. The engineers should consider these features when implementing an underfloor ventilation design. The top-return (TR) configuration improves indoor air quality by creating a displacement-like flow pattern while the floor-return (FR) configuration shows highly localized ventilation characteristics. The FR configuration improved the indoor air quality at spaces near the floor diffusers and up to certain heights.

Thickness-dependent smectic-A–smectic-C*transition in chiral smectic free-standing liquid-crystal films

We have conducted heat-capacity measurements near the smectic-A -smectic-C* phase transition in free-standing films of a chiral liquid-crystal compound. The heat-capacity behavior confirms the evolution of the transition in the interior layers from first to second order as a function of film thickness suggested earlier in tilt angle measurements. The asymmetry in the heat-capacity anomaly exhibits an interesting crossover in thinner films. We also observed the phase transitions leading to the crystallization to the tilted crystal-G phase in these films at lower temperatures. The surface ordering strength in these films is found to be much larger than that in other orthogonal-smectic films, which we speculate is due to the molecular tilt.

Multiple electron diffraction and two-dimensional crystalline order in liquid-crystal thin films

Electron diffraction in freestanding thin films in the crystal-B phase reveals extensive multiple diffraction in films of 14S5 but not of 4O.8, suggesting an important difference in the structural order in these films despite the similarities in their positional correlations found in earlier experiments. The result in a two-layer 14S5 film indicates surprisingly that secondary diffraction can occur in a crystal with only pseudo-long-range positional order.

Surface phase transitions in free-standing films of nonchiral tilted hexatic liquid crystals

Surface freezing transitions in free-standing films of achiral Schiff's-base liquid crystals 5O.6 and 7O.7 exhibiting tilted hexatic phases have been studied using optical textures. The evolution of textures with temperature in 5O.6 films is qualitatively similar to that reported earlier in the ferphenyl ester FTE1, suggesting the existence of the surface smectic-L phase, except that the stripe texture in 5O.6 consists of alternating light and dark stripes of unequal widths. No stripe texture is observed in 7O.7.