Synthetic Strategies for Semiconductor Nanocrystals Expressing Localized Surface Plasmon Resonance.

The field of semiconductor plasmonics has grown rapidly since its outset, only roughly six years ago, and now includes many crystalline substances ranging from GeTe to wide-bandgap transition-metal oxides. One byproduct of this proliferation is the sea of differing synthetic methods to realize localized surface plasmon resonances (LSPRs) based on the studied material. Strategies vary widely from material to material, but all have the common goal of introducing extremely high carrier densities to the semiconductor system. This doping results in tunable, size-quantized, and on/off-switchable LSPR modes, which are a complete departure from traditional metal-nanoparticle-based plasmon resonances. This Minireview will provide an overview of the current state of nanocrystal and quantum-dot plasmonics and the physical basis thereof, however its main purpose is to summarize the methods for realizing LSPRs in the various syntheses and systems that have been reported to date.

Electrical Control of near-Field Energy Transfer between Quantum Dots and Two-Dimensional Semiconductors.

We investigate near-field energy transfer between chemically synthesized quantum dots (QDs) and two-dimensional semiconductors. We fabricate devices in which electrostatically gated semiconducting monolayer molybdenum disulfide (MoS2) is placed atop a homogeneous self-assembled layer of core-shell CdSSe QDs. We demonstrate efficient nonradiative Förster resonant energy transfer (FRET) from QDs into MoS2 and prove that modest gate-induced variation in the excitonic absorption of MoS2 leads to large (∼500%) changes in the FRET rate. This in turn allows for up to ∼75% electrical modulation of QD photoluminescence intensity. The hybrid QD/MoS2 devices operate within a small voltage range, allow for continuous modification of the QD photoluminescence intensity, and can be used for selective tuning of QDs emitting in the visible-IR range.

Plasmonic Cu(x)In(y)S2 quantum dots make better photovoltaics than their nonplasmonic counterparts.

A synthetic approach has recently been developed which results in Cu(x)In(y)S2 quantum dots (QDs) possessing localized surface plasmon resonance (LSPR) modes in the near-infrared (NIR) frequencies.1 In this study, we investigate the potential benefits of near-field plasmonic effects centered upon light absorbing nanoparticles in a photovoltaic system by developing and verifying nonplasmonic counterparts as an experimental control. Simple QD-sensitized solar cells (QD-SSCs) were assembled which show an 11.5% relative increase in incident photon conversion efficiency (IPCE) achieved in the plasmon-enhanced devices. We attribute this increase in IPCE to augmented charge excitation stemming from near-field "antenna" effects in the plasmonic Cu(x)In(y)S2 QD-SSCs. This study represents the first of its kind; direct interrogation of the influence of plasmon-on-semiconductor architectures with respect to excitonic absorption in photovoltaic systems.

Enhanced non-esterified fatty acids and corticosterone in blood plasma of chickens treated with insulin are significantly depleted by reverse T: minor changes in hypoglycaemia.

Previously, it has been observed that dexamethasone or adrenaline-induced hyperlipaemia in blood of chicken was significantly reduced after administration of reverse triiodothyronine (rT3). The present experiment was performed on chicken to determine the altered circulating non-esterified fatty acids (NEFA) induced by physiologically enhanced endogenous corticosterone and catecholamines may also be influenced by rT3. Rise of both hormones were induced by insulin administration. Changes in circulating glucose, corticosterone and catecholamines were additionally measured. Following insulin injection blood glucose fell on the average by 32.7% below control at 2 h of the experiment. Additional treatment with rT3 (rT3 + insulin group) gradually attenuated this decrease and at 4 and 6 h of the experiment it was 17.1% and 12.9% below control, respectively, suggesting on slight inhibition by rT3 of insulin-stimulated glucose utilization. Exposure to insulin significantly increased NEFA levels to about 670% above control group. Additional treatment with rT3 reduced this increase to 309% of control, suggesting inhibition of lipolysis by rT3. Similar alterations were observed in plasma corticosterone levels. Insulin treatment peaked the corticosterone levels maximally by 507.6% above control. Additional treatment with rT3 abolished this rise in the averages to 194.2% above control, possibly by interaction of rT3 with hypothalamo-adrenal axis. Insulin injection increased plasma catecholamines on the average by 21.5% and 53.4% for adrenaline and noradrenaline respectively. Supplementary treatment with rT3 intensified this rise by 55.6% and 71.6% respectively. The obtained results suggest on inhibitory effect of rT3 on hypoglycaemia, hyperlipaemia and plasma corticosterone concentrations in chickens treated with insulin. Contrary to this, rT3 enhanced the rise of plasma catecholamines due to insulin treatment. The obtained data favour the assumption that hypometabolic properties of rT3 depends mainly upon reduced supply of NEFA as a result of restricted lipolysis and to a lesser extent upon the supply of glucose.

Reverse 3,3',5'-triiodothyronine suppresses increase in free fatty acids in chickens elicited by dexamethasone or adrenaline.

Reverse triiodothyronine (rT3) displays hypometabolic properties and antagonizes the hypermetabolic effect of 3,5,3'-triiodothyronine (T3). Previous experiments revealed that exogenous rT3 enhanced free fatty acids (FFA) in heat-stressed pullets and in chickens infected with lipopolysaccharide from Escherichia coli. To gain more data concerning the action of rT3, its effect on lipaemia produced by two main stress hormones: glucocorticoids and catecholamines, has been investigated. Synthetic glucocorticoid [dexamethasone (Dex)] and adrenaline (Adr) were used in two experiments. The experiments differed in duration, i.e. 24 h (Dex) or 150 min (Adr), and frequency of rT3 injections, i.e. two (Dex) or single (Adr) injections. The doses of hormones were as follows: rT3: 14 microg 100 g body weight/ injection (subcutaneously): Dex: 5 mg/animal (subcutaneously) and Adr: 1 mg/animal (intramuscularly). Maximal increases in FFA of 230.5 and 227.5% were noted after 1.5 and 3 h, respectively, in birds treated with Dex. Reverse T3 almost completely suppressed the rise of plasma FFA elicited by Dex. The increase in Dex + rT3-treated fowl was only 30.4% (not significant in comparison to control). Adr increased FFA by a maximum of 89.1 % and treatment with rT3 (Adr + rT3 group) suppressed this FFA increase to 42.5%. The data obtained demonstrate that rT3 suppresses lipaemia induced by an exogenous glucocorticoid and adrenaline. This suppression was more pronounced in glucocorticoid-treated birds, where Dex produced a higher lipolytic response than Adr.

Effect of transport on the intensity of stress reactions in mares and foals.

The aim of this study was to determine the effect of transportation on the behaviour and stress responses of the sympatho-adrenal and hypothalamo-pituitary-adrenal systems in mares and their foals by measuring the peripheral plasma concentrations of adrenaline, noradrenaline and cortisol. Control blood samples were taken from mares and their foals (n=5 pairs) on day 8 after parturition to establish whether blood sampling caused any changes in adrenaline, noradrenaline or cortisol concentrations in blood plasma. The experiment was conducted during foal oestrus (on day 9 after parturition). Adrenaline and noradrenaline concentrations increased in the blood plasma of mares after only 10 min transportation and the increased concentrations were maintained until 30 min after transportation. The adrenaline and noradrenaline concentrations in foal blood plasma increased after 10 min transportation and decreased rapidly to basal concentrations. Cortisol concentrations in the blood plasma of mares reached a peak after 60 min transportation. Peak cortisol concentrations in foal blood plasma were attained after transport was completed. The results of the present study indicate that transportation during foal oestrus is a stronger stress-causing factor for mares than for their foals.

Acute reserpine treatment alters the catecholamine, glucocorticoid and opioid response to walking exercise in sheep.

The aim of the study was to examine the effects of reserpine on the plasma levels of adrenaline, noradrenaline, cortisol and alpha-neoendorphin in sheep under control conditions and during walking exercise. One hour of walking (5 km/h) caused a significant increase in both catecholamines and cortisol between 10 and 30 min of stress, and transiently decreased the level of alpha-neoendorphin at the same time. Reserpine at the dose of 0.3 mg/kg i.v. given before stress significantly lowered the basal levels of all tested parameters. A combination of the reserpine and walking exercise significantly attenuated the stress-induced changes in the plasma level of measured hormones.

The effect of hyperbaric oxygen therapy on a burn wound model in human volunteers.

A previous nonblinded study has suggested beneficial effects from hyperbaric oxygen treatment of superficial partial-thickness radiation burns in human volunteers. This protocol was designed to either confirm or challenge these previous findings in a randomized, blinded format. Twelve healthy, nonsmoking volunteers (7 males, 5 females) participated. All were screened for contraindications to hyperbaric oxygen therapy (acute sinusitis, otitis media, pneumonia, pregnancy, active cancer, pneumothorax) and given a single test hyperbaric exposure. A standardized wound model was employed for the painless creation of a volar forearm lesion on volunteers by applying a suction device to form a blister, excising its epidermal roof, and irradiating the exposed dermis with ultraviolet light. Subjects were randomized into either a hyperbaric oxygen group (100% oxygen at 2.4 ATA, n = 6) or the sea-level air-breathing equivalent control group (8.75% oxygen at 2.4 ATA, n = 6). Both groups then underwent standard hyperbaric therapy. The subjects, the hyperbaric oxygen chamber operators, and the monitoring clinicians were all blinded to the oxygen concentration administered. Each subject received two dives per day over a 3-day period. The wounds were studied noninvasively prior to treatment and once per day over 6 days for size, hyperemia, and exudation, with epithelialization as the endpoint. The averages for each measurement of the hyperbaric oxygen group versus the control group were computed by means of a one-tail t test; p was considered significant at less than 0.05. Daily wound size, hyperemia, and exudation measurements were significantly different on day 2. The hyperbaric oxygen group showed a 42 percent reduction in wound hyperemia, a 35 percent reduction in the size of the lesion, and a 22 percent reduction in wound exudation (p values of 0.05, 0.03, and 0.04, respectively). No significant difference was noted for epithelialization. Observed differences in wound size, hyperemia, and exudation were attributable to hyperbaric oxygen therapy. This study further supports earlier conclusions that hyperbaric oxygen therapy is beneficial in a superficial dermal wound.

Responses of heat stressed chickens to exogenous reverse triiodothyronine (rT3).

Heat stress is accompanied by a decrease in basal metabolic rate and plasma thyroid hormones. Unlike 3,5,3'-triiodothyronine (T3) and thyroxine (T4), 3,3',5'-triiodothyronine (rT3) displays hypometabolic properties and antagonizes the hypermetabolic effect of T3. This study analyses the role of rT3 in heat (38-39 degrees C) stressed immature chickens. Two experiments which differed in frequency of rT3 injections (one or two times a day), duration of heat stress (72 or 48 h) and blood sampling were performed. The dose was 14 micrograms rT3/100 gb.wt./injection (s.c.). It has been shown that rT3 treatment aggravates heat stress symptoms (enhances circulating corticosterone, catecholamines and free fatty acids) and increases mortality. The critical survival time of the rT3 treated and heated birds was at first 24 h of stress. No more chickens died during the next days of the experiment despite the continuation of rT3 injection, suggesting that rT3 might disturb the adaptation to heat. Reverse T3 in heat stressed chickens led to the highest reduction in food consumption (69.9%) and body weight gain (14.0% compared to initial weight). The opposite effect in water consumption (216.9%) was observed. In a neutral environment, rT3 significantly suppressed body temperature 6 h after injection (40.4; control; 41.1 degrees C), confirming its hypometabolic properties. However, at the same time rT3 significantly enhanced body temperature in heat stress (43.03 versus heated control 42.56 degrees C). In addition, in rT3 treated birds decreased plasma triglycerides (TG; 24.3%) and increased plasma free fatty acids (FFA; neutral temperature; 26.4% heat stress: 57%) were demonstrated. A correlation between corticosterone and FFA (r = 0.52) shows that some of the FFA may originate from lipolysis since hormones of the pituitary-adrenocortical axis accelerate lipolysis. The remaining part of the increased FFA appears to be due to suppressed utilization of FFA as a consequence of hypometabolic properties of rT3. Low and negative relation between TG and FFA (r = -0.26; P < 0.05) may support such an assumption. The two times higher peak of corticosterone in the rT3 and the overheated group, as compared to the heated control, occurred at 6 h of heat stress and indicates that rT3 increases the unfavourable effect of high temperature. This was also confirmed by elevated plasma adrenaline and noradrenaline in rT3-injected and heated chickens (55.5 and 120%, respectively). However, a single and two times higher peak of adrenaline at 24 h of heat stress was observed in saline treated birds, but not in rT3 supplemented animals, suggesting that this difference might explain one of the factors responsible for high mortality. In conclusion, the results obtained demonstrate that physiological doses of rT3, a hypometabolic hormone, enhance the unfavourable effect of heat stress in chickens.

Endogenous opioids may modulate the activity of the hypothalamus-pituitary-adrenocortical axis in domestic fowl.

The activity of the hypothalamus-pituitary-adrenocortical (HPA) axis is under complex neuronal, hormonal and peptidergic control. In order to determine the role of the endogenous opioids in the modulation of the HPA axis in hens we have examined the changes of the plasma levels of Met-enkephalin, alpha-neo-endorphin, catecholamines and corticosterone during rest, stress (30 min of overcrowding) and after naltrexone pretreatment. Short overcrowding induced an increase of all parameters, but the time of response and duration of elevation was different. Plasma Met-enkephalin showed a biphasic response: decrease followed by increase at the end of stress. Catecholamines and corticosterone peaked at 30 min of overcrowding and the highest level of alpha-neo-endorphin has been noticed at 20 min after the experiment was started. Naltrexone (2 mg/kg b.w., i.v) diminished the responses to stress of all parameters and did not change their basal levels, except for corticosterone. These results indicate that the endogenous opioids may take part in the mediation of HPA activity in hens during resting and stressful situations.

Continuous ambulatory peritoneal dialysis.

Many patients with end-stage renal disease are maintained on continuous ambulatory peritoneal dialysis (CAPD). This technique offers a number of advantages over hemodialysis, but it is associated with certain potential complications. Peritonitis and other infectious complications are the most commonly seen in the emergency department. The evaluation and management of other emergency problems may also need to be modified in patients on CAPD.

Statistical evidence that endogenous reverse triiodothyronine (rT3) may affect oxygen consumption in food deprived chickens.

Exogenous rT3 decreases O2 consumption in mammals and birds. Until now a correlation coefficient and a regression equation have not been presented. Statistical evaluation seems to be requisite for verifying the answer to the question of whether endogenous rT3 may be able to reduce O2 consumption in birds where the normal level of plasma rT3 is 10 times less than the corresponding level of T3. Food deprived chickens (for 48 h) were used in this study because fasting enhances plasma rT3. The results revealed a reciprocal relation of T3 and rT3 in the circulation. Reverse T3 began to increase when T3 decreased to a plateau at 53.9% of initial level. As expected a reciprocal relationship was obtained (r = -0.749; n = 36) between plasma rT3 and O2 consumption. The regression line was calculated according to the equation: Y = -0.388X + 0.856. This relation differs from the linear relationship between T3 and O2 consumption (r = 0.796; Y = 0.107X + 0.449). The regression line lies in the range of 0.122-0.778 nmol rT3/l, which is found in some physiological conditions in birds where elevated plasma rT3 occurs. This suggests that endogenous rT3 may participate in modifying O2 consumption in birds. Using the rT3:T3 ratio the correlation coefficient was somewhat higher (r = -0.831; Y = -0.673X + 0.831) suggesting common involvement of both triiodothyronines in the reduction of O2 consumption during food deprivation. The drop in O2 consumption after 48 h of food deprivation was 28.4%; decreased T3 and increased rT3 may participate in 15.4% and 13.0% of this fall, respectively. The hypometabolic effectiveness of rT3 seems to be greater than the hypermetabolic effectiveness of T3, since a smaller increase of plasma rT3 was needed to reduce O2 consumption compared to the amount of T3 necessary to enhance it.

Response of sympatho-adrenal axis and adrenal cortex to short-term restraint stress in sheep.

The sympatho-adrenal and pituitary-adrenal cortex axes are the most sensitive, and specific indicators of stress in animals. Increased plasma levels of catecholamines and glucocorticoids are generally considered as the classical response to stress. Most experiments on immobilization have been performed on rats and only a few of them concerned domestic animals. In this experiment we want to learn whether short-term restraint-a stressor most commonly used in animal husbandry-is a stressor for sheep (ewes) like in rats. For this reason we measured adrenaline (A), noradrenaline (NA) (radioenzymatic method), cortisol (RIA method), glucose and free fatty acids (FFA). Unlike in rats, in stressed sheep the peak of A appeared earlier than the NA peak, i.e. at 2 and 5 min. of stress, respectively. In contrast to rats, the basal and stress levels of NA exceeded the corresponding level of A. Cortisol concentration rose 7 fold above baseline and maximal concentration appeared at a time (15-30 min.) observed in other animal species. A similar time-related increase was observed in the plasma FFA concentration. It increased maximally 3.2 fold at 15 min. of stress. A significant correlation coefficient was found between plasma cortisol and FFA (r = 0.91) what may suggest the lipolytic effect of ACTH and/or a positive feedback of FFA on the hypophysis-adrenal axis. The plasma glucose of stressed animals rose only 1.47 fold above the basal level. A significant correlation was found between cortisol and glucose (r = 0.53) whereas no correlations have been obtained between A, NA and glucose or FFA.(ABSTRACT TRUNCATED AT 250 WORDS)

Modified responses of circulating cortisol, thyroid hormones, and glucose to exogenous corticotropin and thyrotropin-releasing hormone in food-deprived sheep.

In a previous experiment, food deprivation was found to suppress the increase of plasma cortisol and thyroid hormones in stressed animals. Because both the hypothalamo-adrenocortical and the thyroid axes are stimulated during stress, we investigated in this study whether a similar pattern of changes occurs in food-deprived sheep following corticotropin (ACTH) or thyrotropin-releasing hormone (TRH) administration. Each hormone was given as a bolus injection on the fifth day of food deprivation. Blood was sampled by venipuncture five times: 0.5 h before and 1, 3, 5, and 9 h after injection of the hormone. The peak of plasma cortisol in food-deprived sheep following ACTH administration exceeded fourfold the corresponding peak in fed animals. This suggests that food deprivation may enhance the sensitivity of the adrenocortical gland to ACTH and/or reduce binding sites for cortisol in target tissues. In fed animals, TRH was without effect on plasma cortisol level, whereas in food-deprived sheep cortisol transiently increased 2.5-fold, suggesting greater permeability of the blood-brain barrier for TRH. In food-deprived animals, plasma T3 was decreased to 22.6% of basal level, and elevated plasma cortisol after ACTH injection was not able to decrease it further. On the other hand, in fed sheep increased plasma cortisol did decrease plasma T3 as much as 4.2-fold. Circulating T4 was not affected by ACTH treatment. The delta increase of plasma T3 and T4 following TRH administration was comparable in fed and fasted animals.(ABSTRACT TRUNCATED AT 250 WORDS)

[Effect of phenothiazine derivative on adrenal cortex response of sheep to repeated emotional stress]. / Wplyw pochodnej fenotiazyny na reakcje kory nadnerczy owiec w czasie wielokrotnego stresu emocjonalnego.

The study was aimed at the evaluation of propiopromazine (Combelen, Bayer), a derivative of phenothiazine, as an agent lowering in sheep the response to stress. The stress of emotional origin was induced in sheep by the isolation from herd lasting 1 hour. The isolation experiments were repeated 6 times on the same group of sheep, first three isolations (1-3) in daily intervals and next three (4-6) in weekly intervals. Propiopromazine was administered before each isolation experiment. The reaction of sheep to the isolation stress was weaker after propiopromazine administration. This was suggested by smaller increase in blood serum cortisol and glucose levels when compared to sheep subjected to isolation but not receiving the drug. Such effect was especially conspicuous during the course of the first isolation experiment; during the next experiments the difference concerning the reaction to stress between the sheep isolated from the herd receiving and not receiving the drug was gradually diminishing. It was shown in addition that propiopromazine administration to the sheep not subjected to stress caused an increase in cortisol level by 125 per cent and that in glucose level by 35 per cent. These results suggest that propiopromazine administration protects the organism against the effects of emotional stress only partially. Moreover, the effect of its administration gradually weakens with repeating of the stress inducing experiment, and propiopromazine itself may act as a stress inducing factor. It seems therefore that the use of propiopromazine and similar compounds as anti-stress agents may be questionable.

Pharyngoesophageal perforation after blunt neck trauma.

Pharyngoesophageal perforation secondary to blunt neck trauma is an uncommon injury that can cause serious morbidity and mortality if not recognized and treated. Pharyngeal perforation secondary to blunt trauma sustained while boxing is reported. Review of the world literature found 10 cases of pharyngoesophageal perforation secondary to blunt neck trauma. Analysis of these cases indicates that perforations less than 2 cm and limited to the pharynx may be treated medically with close observation. Large perforations and those perforations that extend to the esophageal inlet or involve the esophagus exclusively are best treated surgically.

Food deprivation suppresses stress-induced rise in catabolic hormones with a concomitant tendency to potentiate the increment of blood glucose.

The organism of a food-deprived animal is directed toward minimizing energy expenditure and plasma levels of catabolic hormones and glucose are also reduced. Stress, on the other hand, is associated with enhancement of metabolic processes, elevated plasma catabolic hormones, and higher glucose levels. The question arises as to whether food deprivation may be able to attenuate the rise of plasma catabolic hormones seen in stress. For this purpose the variations in triiodothyronine (T3), thyroxine (T4), cortisol and glucose in blood plasma of sheep were monitored during 101 hr of food deprivation and 5 hr of stress. Stress was evoked by isolation of individual sheep from the flock. Blood was sampled by venipuncture once a day during 4 days preceding the isolation stress. On the day of isolation, blood was taken 4 times at 1.5- to 2-hr intervals. Food deprivation lowered the T3, T4 and glucose levels to 45.0, 59.5 and 78.0 percent of the basal level, respectively. Plasma cortisol level did not change over the fasting period in sheep not having visual contact with fed animals. Maintaining such a contact elevated cortisol level maximally by 139 percent over basal level. This indicates that the involvement of an emotional factor seems to be necessary for manifestation of stress. Isolation stress acting on fed and fasting sheep increased all measured hormones and glucose levels. However, in fed sheep, the maximal levels of T3, T4 and cortisol were 72.5, 48.4 and 50.0 percent higher than in corresponding isolated and food-deprived animals. Inversely, the maximal concentration of plasma glucose was about 16.6 percent higher in food-deprived than in fed animals.(ABSTRACT TRUNCATED AT 250 WORDS)