Evolution of the Magnetic Excitations in Electron-Doped La_{2-x}Ce_{x}CuO_{4}

We investigated the high energy spin excitations in electron-doped La_{2-x}Ce_{x}CuO_{4}, a cuprate superconductor, by resonant inelastic x-ray scattering (RIXS) measurements. Efforts were paid to disentangle the paramagnon signal from non-spin-flip spectral weight mixing in the RIXS spectrum at Q_{∥}=(0.6π,0) and (0.9π,0) along the (1 0) direction. Our results show that, for doping level x from 0.07 to 0.185, the variation of the paramagnon excitation energy is marginal. We discuss the implication of our results in connection with the evolution of the electron correlation strength in this system.

Anisodamine hydrobromide in the treatment of critically ill patients with septic shock: a multicenter randomized controlled trial

BACKGROUND

Septic shock is the development of sepsis to refractory circulatory collapse and metabolic derangements, characterized by persistent hypotension and increased lactate levels. Anisodamine hydrobromide (Ani HBr) is a Chinese medicine used to improve blood flow in circulatory disorders. The purpose of this study was to determine the therapeutic efficacy of Ani HBr in the treatment of patients with septic shock.

METHODS

This was a prospective, multicenter, randomized controlled trial focusing on patients with septic shock in 16 hospitals in China. Patients were randomly assigned in a 1:1 ratio to either the treatment group or the control group. The primary endpoint was 28-day mortality. The secondary outcomes included 7-day mortality, hospital mortality, hospital length of stay, vasopressor-free days within 7 days, etc. These indicators were measured and collected at 0, 6h, 24h, 48h, 72h and 7d after the diagnosis.

RESULTS

Between September 2017 and March 2021, 404 subjects were enrolled. 203 subjects received Ani HBr and 201 subjects were assigned to the control group. The treated group showed lower 28-day mortality than the control group. Stratified analysis further showed significant differences in 28-day mortality between the two groups for patients with a high level of illness severity. We also observed significant differences in 7-day mortality, hospital mortality and some other clinical indicators between the two groups.

CONCLUSION

Ani HBr might be an important adjuvant to conventional treatment to reduce 28-day mortality in patients with septic shock. A large-scale prospective randomized multicenter trial is warranted to confirm our results.

Effects of viral infection and microbial diversity on patients with sepsis: A retrospective study based on metagenomic next-generation sequencing

BACKGROUND

The study aims to investigate the performance of a metagenomic next-generation sequencing (NGS)-based diagnostic technique for the identification of potential bacterial and viral infections and effects of concomitant viral infection on the survival rate of intensive care unit (ICU) sepsis patients.

METHODS

A total of 74 ICU patients with sepsis who were admitted to our institution from February 1, 2018 to June 30, 2019 were enrolled. Separate blood samples were collected from patients for blood cultures and metagenomic NGS when the patients' body temperature was higher than 38 °C. Patients' demographic data, including gender, age, ICU duration, ICU scores, and laboratory results, were recorded. The correlations between pathogen types and sepsis severity and survival rate were evaluated.

RESULTS

NGS produced higher positive results (105 of 118; 88.98%) than blood cultures (18 of 118; 15.25%) over the whole study period. Concomitant viral infection correlated closely with sepsis severity and had the negative effect on the survival of patients with sepsis. However, correlation analysis indicated that the bacterial variety did not correlate with the severity of sepsis.

CONCLUSIONS

Concurrent viral load correlates closely with the severity of sepsis and the survival rate of the ICU sepsis patients. This suggests that prophylactic administration of antiviral drugs combined with antibiotics may be beneficial to ICU sepsis patients.

Measurement of the toroidal radiation asymmetry during massive gas injection triggered disruptions on J-TEXT

Disruptions have the potential to cause severe damage to large tokamaks like ITER. The mitigation of disruption damage is one of the essential issues for the tokamak. Massive gas injection (MGI) is a technique in which large amounts of a noble gas are injected into the plasma in order to safely radiate the plasma energy evenly over the entire plasma-facing wall. However, the radiated energy during the disruption triggered by massive gas injection is found to be toroidally asymmetric. In order to investigate the spatial and temporal structures of the radiation asymmetry, the radiated power diagnostics for the J-TEXT tokamak have been upgraded. The multi-channel arrays of absolute extreme ultraviolet photodiodes have been upgraded at four different toroidal positions to investigate the radiation asymmetries during massive gas injection. It is found that the toroidal asymmetry is associated with plasma properties and MGI induced MHD activities.

Design of a shattered pellet injection system on J-TEXT tokamak

Disruptions have the possibility of causing severe wall damage to large tokamaks like ITER. The mitigation of disruption damage is essential to the safe operation of a large-scale tokamak. The shattered pellet injection (SPI) technique, which is regarded as the primary injection method for ITER, presents several advantages relative to massive gas injection, including more rapid particle delivery, higher total particle assimilation, and more centrally peaked particle deposition. A dedicated argon SPI system that focuses on disruption mitigation and runaway current dissipation has been designed for the Joint Texas Experimental Tokamak (J-TEXT). A refrigerator is used to form a single argon pellet at around 64 K. The pellet will be shaped with a 5 mm diameter and a 1.5-10 mm length. Helium gas at room temperature will be used as a propellant gas for pellet acceleration. The pellet can be injected with a speed of 150-300 m/s. The time interval between injection cycles is about 8 min. The pellet will be shattered at the edge of the plasma and then injected into the core of plasma. The first experiments of SPI fast shutdown and runaway current dissipation have been performed.

Vertical fast electron bremsstrahlung diagnostic on J-TEXT tokamak

Fast electron bremsstrahlung (FEB) emission during Ohmic discharge experiments on the Joint Texas Experimental Tokamak (J-TEXT) has been measured by a recently developed vertical multi-channel FEB diagnostic based on CdZnTe detectors. There are 5 sight lines to observe the vertical emission of fast electrons at the high-field side with a spatial resolution of 5 cm. The FEB emission in the energy range of 30-300 keV can be measured. The generation of fast electrons accelerated by loop voltage has been confirmed during the early phase of discharge by analyzing the signals of FEB emission. The runaway electron beam instabilities have been observed with the FEB diagnostic on J-TEXT.

Rhubarb Monomers Protect Intestinal Mucosal Barrier in Sepsis via Junction Proteins

Background:

Leakage of the intestinal mucosal barrier may cause translocation of bacteria, then leading to multiorgan failure. This study hypothesized that rhubarb monomers might protect the gut mucosal barrier in sepsis through junction proteins.

Methods:

Healthy male Sprague-Dawley rats (weighing 230–250 g) under anesthesia and sedation were subjected to cecal ligation and perforation (CLP). After surgical preparation, rats were randomly assigned to eight groups (n = 6 or 8 each group): sham group (Group A: normal saline gavage); sepsis group (Group B: normal saline gavage); Group C (intraperitoneally, dexamethasone 0.5 mg/kg) immediately after CLP surgery; and rhubarb monomer (100 mg/kg in normal saline)-treated groups (Group D: rhein; Group E: emodin; Group F: 3,8-dihydroxy-1-methyl-anthraquinone-2-carboxylic acid; Group G: 1-O-caffeoyl-2-(4-hydroxy-O-cinnamoyl)-D-glucose; and Group H: daucosterol linoleate). Animals were sacrificed after 24 h. Intestinal histology, lactulose, mannitol concentrations were measured, and zonula occludens (ZO)-1, occludin and claudin-5 transcription (polymerase chain reaction), translation (by Western blot analysis), and expression (by immunohistochemistry) were also measured.

Results:

Intestinal histology revealed injury to intestinal mucosal villi induced by sepsis in Group B, compared with Group A. Compared with Group A (0.17 ± 0.41), the pathological scores in Groups B (2.83 ± 0.41, P < 0.001), C (1.83 ± 0.41, P < 0.001), D (2.00 ± 0.63, P < 0.001), E (1.83 ± 0.41, P < 0.001), F (1.83 ± 0.75, P < 0.001), G (2.17 ± 0.41, P < 0.001), and H (1.83 ± 0.41, P < 0.001) were significantly increased. Lactulose/mannitol (L/M) ratio in Group B (0.046 ± 0.003) was significantly higher than in Group A (0.013 ± 0.001, P < 0.001) while L/M ratios in Groups C (0.028 ± 0.002, P < 0.001), D (0.029 ± 0.003, P < 0.001), E (0.026 ± 0.003, P < 0.001), F (0.027 ± 0.003, P < 0.001), G (0.030 ± 0.005, P < 0.001), and H (0.026 ± 0.002, P < 0.001) were significantly lower than that in Group B. ZO-1, occludin and claudin-5 transcription, translation, and expression in Group B were significantly lower than that in Group A (P < 0.001), but they were significantly higher in Groups C, D, E, F, G, and H than those in Group B (P < 0.05).

Conclusion:

Rhubarb monomer treatment ameliorated mucosal damage in sepsis via enhanced transcription, translation, and expression of junction proteins.

Rhubarb Antagonizes Matrix Metalloproteinase-9-induced Vascular Endothelial Permeability

Background:

Intact endothelial structure and function are critical for maintaining microcirculatory homeostasis. Dysfunction of the latter is an underlying cause of various organ pathologies. In a previous study, we showed that rhubarb, a traditional Chinese medicine, protected intestinal mucosal microvascular endothelial cells in rats with metastasizing septicemia. In this study, we investigated the effects and mechanisms of rhubarb on matrix metalloproteinase-9 (MMP9)-induced vascular endothelial (VE) permeability.

Methods:

Rhubarb monomers were extracted and purified by a series of chromatography approaches. The identity of these monomers was analyzed by hydrogen-1 nuclear magnetic resonance (NMR), carbon-13 NMR, and distortionless enhancement by polarization transfer magnetic resonance spectroscopy. We established a human umbilical vein endothelial cell (HUVEC) monolayer on a Transwell insert. We measured the HUVEC permeability, proliferation, and the secretion of VE-cadherin into culture medium using fluorescein isothiocyanate-dextran assay, 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide assay, and enzyme-linked immunosorbent assay, respectively, in response to treatment with MMP9 and/or rhubarb monomers.

Results:

A total of 21 rhubarb monomers were extracted and identified. MMP9 significantly increased the permeability of the HUVEC monolayer, which was significantly reduced by five individual rhubarb monomer (emodin, 3,8-dihydroxy-1-methyl-anthraquinone-2-carboxylic acid, 1-O-caffeoyl-2-(4-hydroxyl-O-cinnamoyl)-β-D-glucose, daucosterol linoleate, and rhein) or a combination of all five monomers (1 μmol/L for each monomer). Mechanistically, the five-monomer mixture at 1 μmol/L promoted HUVEC proliferation. In addition, MMP9 stimulated the secretion of VE-cadherin into the culture medium, which was significantly inhibited by the five-monomer mixture.

Conclusions:

The rhubarb mixture of emodin, 3,8-dihydroxy-1-methyl-anthraquinone-2-carboxylic acid, 1-O-caffeoyl-2-(4-hydroxyl-O-cinnamoyl)-β-D-glucose, daucosterol linoleate, and rhein, at a low concentration, antagonized the MMP9-induced HUVEC monolayer permeability by promoting HUVEC proliferation and reducing extracellular VE-cadherin concentrations.

Comparative Study of Plasma Endotoxin with Procalcitonin Levels in Diagnosis of Bacteremia in Intensive Care Unit Patients

BACKGROUND

Both procalcitonin (PCT) and plasma endotoxin levels cannot be solely used for a definite diagnosis of bacteremia or sepsis, and there has been few study comparing the values of the two biomarkers for the diagnosis of bacteremia. The aim of this study was to identify bacteria causing bacteremia and evaluate the role of the two biomarkers in the diagnosis of bacteremia in Intensive Care Unit (ICU).

METHODS

The medical records of 420 patients in ICU were retrospectively reviewed. Patients (n = 241) who met the inclusion criteria were subjected to blood culture (BC) for the analysis of the endotoxin or PCT levels. The exclusion criteria included the presence of infection with human immunodeficiency virus and/or AIDS, neutropenia without sepsis, pregnancy, treatment with immunosuppressive therapies, or blood diseases such as hematological tumors. Patients' BC episodes were divided into BC negative, Gram-negative (GN) bacteria, Gram-positive bacteria, and fungi groups. The PCT and plasma endotoxin levels were compared in the different groups.

RESULTS

A total of 241 patients with 505 episodes of BC were analyzed. The GN bacteria group showed higher levels of PCT and endotoxin than the BC negative, Gram-positive bacteria, and fungi groups. GN bacteremia was more prevalent than Gram-positive bacteremia. The GN bacteremia caused by non-Enterobacteriaceae infection presented higher endotoxin level than that by Enterobacteriaceae, but no significant difference in PCT levels was observed between the two groups. The plasma endotoxin significantly differed among different groups and was bacterial species dependent.

CONCLUSIONS

Plasma endotoxin was more related to GN than to Gram-positive bacteremia, and that endotoxin level was species dependent, but PCT level remained relatively more stable within the GN bacteria caused bacteremia. Both GN and positive bacteria caused bacteremia in the ICU patients in different regions of China. And PCT is a more valuable biomarker than endotoxin in the diagnosis of bacteremia.

Use of Platelet Indices for Determining Illness Severity and Predicting Prognosis in Critically Ill Patients

Background:

Decreased platelet (PLT) count is one of the independent risk factors for mortality in intensive care unit (ICU) patients. This study was to investigate the relationship between PLT indices and illness severity and their performances in predicting hospital mortality.

Methods:

Adult patients who admitted to ICU of Changzheng Hospital from January 2011 to September 2012 and met inclusion criteria were included in this study. Univariate analysis was used to identify potential independent risk factors for mortality. Multiple logistic regression analysis was used to calculate adjusted odds ratio for mortality in patients with normal or abnormal PLT indices. The relationship between PLT indices and illness severity were assessed by the Acute Physiology and Chronic Health Evaluation II (APACHE II) scores or sequential organ failure assessment (SOFA) scores in patients with normal and abnormal PLT indices. The performances of PLT indices in predicting mortality were assessed by receiver operating curves and diagnostic parameters. The survival curves between patients with normal and abnormal PLT indices were compared using Kaplan–Meier method.

Results:

From January 2011 to September 2012, 261 of 361 patients (204 survivors and 57 nonsurvivors) met the inclusion criteria. After adjustment for clinical variables, PLT count <100 × 10¹²/L (P = 0.011), plateletcrit (PCT) <0.108 (P = 0.002), mean platelet volume (MPV) >11.3 fL (P = 0.023) and platelet distribution width (PDW) percentage >17% (P = 0.009) were identified as independent risk factors for mortality. The APACHE II and SOFA scores were 14.0 (9.0–20.0) and 7.0 (5.0–10.5) in the “low PLT” tertile, 13.0 (8.0–16.0) and 7.0 (4.0–11.0) in the “low PCT” tertile, 14.0 (9.3–19.0) and 7.0 (4.0–9.8) in the “high MPV” tertile, 14.0 (10.5–20.0) and 7.0 (5.0–11.0) in the “high PDW” tertile, all of which were higher than those in patients with normal indices. Patients with decreased PLT and PCT values (all P < 0.001), or increased MPV and PDW values (P = 0.007 and 0.003, respectively) had shortened length of survival than those with normal PLT indices.

Conclusions:

Patients with abnormally low PLT count, high MPV value, and high PDW value were associated with more severe illness and had higher risk of death as compared to patients with normal PLT indices.

Effect of ulinastatin on HMGB1 expression in rats with acute lung injury induced by sepsis

The aim of this study was to investigate the influence of ulinastatin (UTI) on high mobility group box 1 (HMGB1), tumor necrosis factor (TNF)-α, and interleukin (IL)-6 expression in acute lung injury (ALI) rats with sepsis caused by cecal ligation and puncture (CLP) surgery, as well as to examine the underlying biological mechanism. Thirty rats were randomly and evenly divided into sham (control), CLP, and CLP + UTI groups. Thirty minutes after the surgery, the rats in the CLP + UTI group received UTI via the caudal vein, while normal saline was administered to rats in the other groups. Blood, lung tissues, and bronchoalveolar lavage fluid (BALF) were collected at different time points (6, 12, 24, and 48 h) after surgery for determination of related indicators. Compared with the CLP group, rats in the CLP + UTI group exhibited higher seven day survival rates, less lung injury, and decreased HMGB1 expression in the lung tissue, serum, and BALF. In addition, the levels of TNF-α and IL-6 at 24 h in the CLP + UTI group were markedly lower than those in the CLP group. These results suggest that by deregulation, UTI might decrease the lung injury and increase the survival time of ALI rats by downregulating HMGB1 expression as well as by inhibiting TNF-α and IL-6 levels in serum and BALF.

Prognostic value of CD4(+)CD25(+) Tregs as a valuable biomarker for patients with sepsis in ICU

BACKGROUND

Sepsis is a common complication of infections, burns, traumas, surgeries, poisonings, and post-cardiopulmonary resuscitation. The present study aimed to investigate prognostic value of CD4(+)CD25(+) regulatory T cells (Treg) in peripheral blood of patients with sepsis.

METHODS

Periphery blood from 28 patients diagnosed with sepsis was collected on day 1 and 7 after hospitalization in the ICU of Shanghai Changzheng Hospital between December 2013 to April 2014. The blood was used for analyses of Treg ratio using flow cytometry and for analyses of blood routine test, C-reactive protein (CRP), bilirubin, procalcitonin (PCT), and coagulation. APACHE II and sequential organ failure assessment (SOFA) scores were also investigated. The results were compared between two outcome groups of survival or death to evaluate prognostic value for sepsis.

RESULTS

The patients had an average age of 60.36±15.03 years, APACHE II score 16.68±7.00, and SOFA score 7.18±3.78. Among the 28 patients, 12 had severe trauma (42.9%), 10 had septic shock (35.7%), and 9 (32.2%) died. The median ratio of Tregs was 2.10% (0.80%, 3.10%) in the survival group vs. 1.80% (1.15%, 3.65%) in the death group (Z=-0.148, P=0.883) on day 1; however it was significantly changed to 0.90% (0.30%, 2.80%) vs. 5.70% (2.60%, 8.30%) (Z=-2.905, P=0.004).

CONCLUSION

With better prospects for clinical application, dynamic monitoring of Tregs ratio in peripheral blood has potential value in predicting prognosis of sepsis.

Proteome changes in mesenteric lymph induced by sepsis

The present study aimed to examine the changes in mesenteric lymph during the development of sepsis and to identify the distinct proteins involved, as targets for further study. The sepsis animal model was constructed by cecal ligation and puncture (CLP). The mesenteric lymph was collected from 28 adult male Sprague-Dawley rats, which were randomly divided into the following four groups (n=7 per group): CLP-6 h, CLP-24 h, sham-6 h and sham-24 h groups. Capillary high performance liquid chromatography-tandem mass spectrometry was performed to analyze the proteome in mesenteric lymph. A comprehensive bioinformatic analysis was then conducted to investigate the distinct proteins. Compared with the sham group, 158 distinct proteins were identified in the lymph samples from the CLP group. Five of these proteins associated with the same lipid metabolism pathway were selected, apolipoprotein E (ApoE), annexin A1 (Anxa1), neutrophil gelatinase-associated lipocalin (NGAL), S100a8 and S100a9. The expression of ApoE, Anxa1, NGAL, S100a8 and S100a9 were all elevated in the progression of sepsis. The five proteins were reported to be closely associated with disease development and may be a potential target for the diagnosis and treatment of sepsis. In conclusion, identifying proteome changes in mesenteric lymph provides a novel perspective to understand the pathological mechanisms underlying sepsis.

Effect of rhubarb pre-treatment on intestinal microcirculation in septic rats

The intestine plays a vital role in the pathophysiology of sepsis development. The objective of the present study was to explore the effects of rhubarb on intestinal microcirculation in septic rats. We used moorFLPI laser speckle imaging to detect the blood flow of the intestinal mucosa and wall. Using an ELISA, we assayed the concentration of lactate (L) and pyruvic acid (P) in the intestinal tissue to calculate the ratio of lactate to pyruvic acid (L/P ratio). To observe the intestinal mucosal capillaries, gelatin and ink were perfused into the intestine and subsequently stained with hematoxylin and eosin (HE) to measure the ratio of the vessel area. We then used immunohistochemistry to measure CD31 expression. Using an MTT assay, the effect of the rhubarb extract on the proliferation of human umbilical vein endothelial cells (HUVECs) was analyzed. The blood flow in the intestinal wall and mucosa of the control, sham and rhubarb-treated groups was significantly higher, while the sepsis group had relatively low blood flow. The L/P ratio in the intestinal tissue was larger in the sepsis group than in the other three groups. The microvascular area (MVA) in the sepsis group was smaller than in the control group, sham group or rhubarb group. Positive expression for CD31 was observed in the cytoplasm of vascular endothelial cells. The intestinal mucosal capillaries were reduced in septic rats as compared to the other three groups. HUVEC proliferation was enhanced by the rhubarb extract monomers at 1 μmol/L, but suppressed at higher concentrations of 10 to 100 μmol/L. These results suggest that pre-treatment with rhubarb prior to sepsis induction promotes the expansion of the intestinal mucosal capillaries, protects intestinal mucosal capillary endothelial cells and increases the number of functional intestinal capillaries.

Impact of imipenem treatment on colonic mycobiota in rats with double-hit sepsis

BACKGROUND

Broad-spectrum antibiotic administration promotes intestinal colonization of exogenous fungal pathogens in healthy animals and has been recognized as one of the risk factors of invasive fungal infection in clinical settings. It is unclear whether broad-spectrum antibiotic treatment would change the intestinal mycobiota without exogenous fungal challenge in the context of sepsis.

METHODS

We established a rat model of double-hit sepsis using burn injury and endotoxin challenge. Rats with burn injury or double-hit sepsis received imipenem treatment for 3 days or 9 days, and their colon contents were sampled for selective fungal culture and isolation counts.

RESULTS

Imipenem treatment promoted the overgrowth of the commensal fungus Geotrichum capitatum in rats with burn injury. Imipenem treatment also promoted colon colonization by exogenous fungi in rats with burn injury and double-hit sepsis, including Trichosporon cutaneum, Candida albicans, Candida krusei, and Candida glabrata. A longer duration of imipenem treatment had a stronger impact on colon colonization by exogenous fungi.

CONCLUSION

Imipenem treatment facilitates the overgrowth of commensal fungi and colonization by exogenous, potentially pathogenic fungi in the colons of rats with burn injury or double-hit sepsis.

A modified rat model for cannulation and collection of thoracic duct lymph

Difficulty in collecting lymph samples in small animals has impeded studies on lymphatic function and lymph composition. Here we report a simple and effective modified rat model for thoracic duct lymph drainage where animals remain in full consciousness and have free movement and access to water and food over 12 hours. The operative procedure required approximately 30 minutes to perform. Mean lymph drainage was 0.71 +/- 0.33 ml/h, and protein concentration did not change significantly (mean 37 +/- 2.59 mg/ml) over the 12 hours. However, the number of lymphocytes fluctuated widely between 0.08 +/- 0.03 x 10(6)/ml and 12.17 +/- 6.58 x 10(6)/ml. This modified animal model of thoracic duct lymph collection avoids influences of lipid intake, general anesthesia, or limited activity of animals on experimental outcomes, and therefore more accurately reflects lymph flow and composition under normal physiological conditions.

Strong light-induced negative optical pressure arising from kinetic energy of conduction electrons in plasmon-type cavities

We found that very strong negative optical pressure can be induced in plasmonic cavities by LC resonance. This interesting effect could be described qualitatively by a Lagrangian model which shows that the negative optical pressure is driven by the internal inductance and the kinetic energy of the conduction electrons. If the metal is replaced by perfect conductors, the optical pressure becomes much smaller and positive.

Longitudinal elliptically polarized electromagnetic waves in off-diagonal magnetoelectric split-ring composites

We study the propagation of plane electromagnetic waves through different systems consisting of arrays of split rings of different orientations. Many extraordinary EM phenomena were discovered in such systems, contributed by the off-diagonal magnetoelectric susceptibilities. We find a mode such that the electric field becomes elliptically polarized with a component in the longitudinal direction (i.e. parallel to the wavevector). Even though the group velocity [Formula: see text] and the wavevector k are parallel, in the presence of damping, the Poynting vector does not just get 'broadened', but can possess a component perpendicular to the wavevector. The speed of light can be real even when the product ϵμ is negative. Other novel properties are explored.

Probing states with macroscopic circulations in magnetic photonic crystals

We predict that when light is reflected off a magnetic photonic crystal (MPC) there is a grazing component that is parallel to the surface; the magnitude of this component can be changed by an external field. The direction of this parallel component is reversed as the direction of the magnetization is reversed. This provides a way to probe states with macroscopic circulations inside the MPC.

Manipulating electromagnetic radiation with magnetic photonic crystals

We examine manipulating electromagnetic waves in magnetic photonic crystals (MPCs) with external magnetic fields. We predict new giant magnetoreflectivity and giant magnetorefractivity effects: with an external magnetic field of a magnitude much smaller than the anisotropy field of the ferromagnet, the MPC can be changed from completely reflecting to nonreflecting with corresponding changes in the angle of refraction. Application to the storage of electromagnetic radiation is also discussed.

Multilayer structures as negative refractive and left-handed materials

We examine multilayer structures as negative refractive index and left-handed materials, and find that for one polarization there is a wide range (≈90°) of incident angle within which negative refraction will occur. This comes about because the group velocity and the Poynting vector have a large component parallel to the layers, no matter what the angle of incidence of the incoming radiation is. This behaviour in turn comes from the large anisotropy of the phase velocities. If one of the components is a ferromagnetic metal, the system can be a left-handed material above the ferromagnetic resonance frequency.

Development of quantitative structure activity relationships in toxicity prediction of complex mixtures

AIM

To predict the toxicity of mixtures of halogenated benzenes (narcotics).

METHODS

Acute toxicity test of single chemicals and mixtures was performed using Photobacterium phosphoreum. Partition coefficients of mixtures were calculated by a special equation. Quantitative structure-activity relationship (QSAR) studies were carried out based on results of toxicity tests, n-octanol/water partition coefficient (Kow), and partition coefficient of mixtures (Kmix).

RESULTS

1) There was a good relationship between toxicity and lgKow for single compounds. 2) QSAR analysis showed a perfect correlation between the calculated Kmix and the mixture toxicity for binary mixtures. 3) Using the QSAR model of binary mixtures, the toxicity of other related mixtures containing different composition and fraction was predicted very well.

CONCLUSION

The toxicity of halogenated benzene mixtures (narcotics) was predicted by QSAR. This kind of study is helpful for assessing the toxicity of narcotic mixtures.

Photosynthetic characteristics of Amaranthus tricolor, a C4 tropical leafy vegetable

The gas exchange characteristics are reported for Amaranthus tricolor, a C4 vegetable amaranth of southeastern Asia. Maximum photosynthetic capacity was 48.3±1.0μmol CO2 m(-2)s(-1) and the temperature optimum was 35°C. The calculated intercellular CO2 concentration at this leaf temperature and an incident photon flux (400-700 mm) of 2 mmol m(-2)s(-1) averaged 208±14 μl l(-1), abnormally high for a C4 species. The photosynthetic rate, intercellular CO2 concentration, and leaf conductance all decreased with an increase in water vapor pressure deficit. However, the decrease in leaf conductance which resulted in a decrease in intercellular CO2 concentration accounted for only one fourth of the observed decrease in photosynthetic rate as water vapor pressure deficit was increased. Subsequent measurements indicated that the depence of net photosynthesis on intercellular CO2 concetration changed with water vapor pressure deficit.

Protein kinases from spinach chloroplasts. I. Purification and identification of two distinct protein kinases

Two protein kinases (chloroplast protein kinases 1 and 2 (ChlPK1 and ChlPK2)) were isolated from spinach chloroplasts. After solubilization of the chloroplasts with octylglucoside and cholate, these kinases were purified by ammonium sulfate precipitation, sucrose gradient centrifugation, and hydroxylapatite chromatography. ChlPK1 traveled as a single band in polyacrylamide gel electrophoresis corresponding to 25,000 daltons; ChlPK2 traveled as a single band corresponding to 38,000 daltons. After exposure to 8-azido-[gamma-32P]ATP, the radioactive bands appeared in the same positions revealed by Coomassie blue staining. However, a trace of ChlPK2 was detected in the ChlPK1 preparation and a faint second lower molecular weight radioactive band was seen in the ChlPK2 preparations. Both enzymes acted on casein or histone IIIS as substrate and phosphorylated a serine residue. The proteolytic peptide maps, however, were clearly distinguishable in autoradiograms, suggesting that different serine residues were phosphorylated by ChlPK1 and ChlPK2.