Experimental study of the fast scintillating behavior of ZnO:Ga crystal under MeV electron beam.

An experimental study on the scintillating behavior of ZnO:Ga crystals was conducted using a 7-MeV electron accelerator. The ZnO:Ga crystals were grown using both hydrothermal and chemical vapor transport methods. One of the ZnO:Ga crystals grown via the hydrothermal method exhibited a 1.5-ns afterglow time when excited by an MeV electron beam. The ultra-short scintillation was captured using both an ultrafast streak camera and a framed camera. The experimental results also confirm its potential for diagnosing electron beam trains with a repetition rate of hundreds of MHz.

Rhodotron and rotating target: A solution towards micro-spot for high energy and high dose rate bremsstrahlung sources.

High energy over MeV bremsstrahlung sources that employ normal conducting radio frequency linear accelerators have expanding applications in industrial computerized tomography (CT) for non-destructive inspection and evaluation. The X-ray spot size that mainly affects the imaging quality is yet limited by the electron beam width in the high resolution CT systems. In a short exposure time, high beam power is required to generate sufficient photons to improve the signal to noise ratio of imaging. However, with ∼kW level of average beam power these linear accelerators usually have a beam spot size over 1 mm since the temperature rising due to the beam energy deposition in the target should be far below its melting point. We propose a concept of using a Rhodotron-based accelerator to provide high power electron beams in a long duration pulse and a rotating target to mitigate the overheating issue, such that the gap between micro-spot and high dose rate can be bridged in the high energy bremsstrahlung sources. This article presents an in-depth simulation work to discuss and evaluate this scheme of X-ray source. The simulations of beam dynamics in the accelerator and bremsstrahlung process in the target predict the generated X-rays with a spot size as small as 68 µm at full-width half-maximum and a dose rate as high as 4700 cGy/min from a 9 MeV electron beam interacting with a 1 mm thickness tantalum target. Further thermal analysis in the rotating target indicates a significant improvement of beam power handling in comparison with the conventional stationary one.

Demonstration of low energy proton radiography on an 11-MeV cyclotron.

Lens focused proton radiograph on thin objects is demonstrated using an 11-MeV proton cyclotron at China Academy of Engineering Physics. The proton beam exiting from the tested objects is focused onto the image plane by a magnetic lens system mitigating image blur caused by multiple Coulomb scattering. Both simulations and experiments show that clear images can be obtained with a lens system for the objects with thickness up to 2.7 × 10-2 g/cm2 and the error for the areal density measurement is measured to be less than 2.3%. For the objects with thickness between 2.7 × 10-3 g/cm2 and 2.7 × 10-2 g/cm2, 100-200 µm of spatial resolution is achieved.

Measurements and effects of backstreaming ions produced at bremsstrahlung converter target in Dragon-I linear induction accelerator.

Positive ions released from x-ray converter target impacted by electron beam of millimeter spot size can be trapped and accelerated in the incident beam's potential well. As the ions move upstream, the beam will be pinched first and then defocused at the target. Four Faraday cups are used to collect backstreaming ions produced at the bremsstrahlung converter target in Dragon-I linear induction accelerator (LIA). Experimental and theoretical results show that the backstreaming positive ions density and velocity are about 10(21)/m(3) and 2-3 mm/micros, respectively. The theoretical and experimental results of electron beam envelope with ions and without ions are also presented. The discussions show that the backstreaming positive ions will not affect the electron beam focusing and envelope radius in Dragon-I LIA.

[Apoptosis of neutrophil in peripheral blood in experimental sepsis].

OBJECTIVE: To evaluate the changes in apoptosis of neutrophil in peripheral blood in sepsis in rats. METHODS: The rat sepsis model was reproduced by cecum ligation and puncture (CLP). One hundred and forty-four rats were randomly divided into normal control group, sham operation group and 2, 6, 12, 24, 48, 72 hours after CLP groups. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) was used to identify neutrophil apoptosis. RESULTS: In early period after CLP, neutrophil apoptosis in peripheral blood was limited with a positive rate of less than 5.00%. The positive rate rose to (48.33+/-12.53)% at 48 hours, and it began to lower, approaching the normal level at 72 hours after CLP. CONCLUSION: Death is the main pathway of loss of neutrophils which are produced in the acute phase of sepsis, and apoptosis is the main pathway of loss of neutrophil in the later phase of sepsis.

[Effects of carbachol on apoptosis of peripheral white blood cells and expression of cytokines in rats suffering from gut ischemia/reperfusion injury].

OBJECTIVE: To evaluate the effect of cholinergic drug carbachol on apoptosis and expression of certain cytokines of peripheral blood lymphocytes and neutrophils in rats subjected to ischemia/reperfusion injury of the intestine. METHODS: Thirty-six Wistar male rats were randomly divided into groups as follows: sham operation, 1 and 2 hour-gut ischemia, 1 hour-gut ischemia followed by reperfusion for 1 hour and 2 hours, carbachol + 1 hour-gut ischemia, and carbachol + 1 hour-gut ischemia followed by reperfusion for 2 hours. Then the gut was subjected to ischemia/reperfusion. At different time points after the said injury, the total number and differential count of leukocytes, apoptosis rate of lymphocytes and neutrophils, and the mRNA expression levels of certain cytokines in peripheral blood leukocytes, were determined. RESULTS: At 1 hour after gut ischemia, the total number of leukocytes decreased (the ratio of lymphocytes increased and that of neutrophils decreased), but it increased after gut reperfusion. Carbachol could reduce the apoptosis rate of lymphocytes, but enhance that of neutrophils after gut ischemia. In leukocytes, mRNAs expression of inflammatory (TNF-alpha) and antiinflammatory (IL-10) cytokines were upregulated at 1 hour after gut ischemia, while that of IL-10, IL-4 and interferon-gamma were down-regulated distinctly at 2 hours following reperfusion. All of these phenomena were ameliorated by giving carbachol. CONCLUSION: Carbachol could reduce the peripheral lymphocytes apoptosis subsequent to gut ischemia, and regulate the balance between inflammatory and antiinflammatory cytokines expression in leukocytes during gut ischemia and reperfusion. The results suggest that carbachol might be a potential therapeutic agent in preventing uncontrolled inflammatory response as a result of ischemia/reperfusion injury of the intestine.

[Change in intestinal function in sepsis in rat].

OBJECTIVE: To study the barrier function, absorption, permeability and peristalsis of intestine in sepsis in rats. METHODS: A Wistar rat model of sepsis was reproduced by ischemia/reperfusion (I/R) of the intestine combined with endotoxin challenge. Animal were randomly divided into normal, I/R 1 hours (I/R 1), I/R 2 hours (I/R 2), I/R 4 hours (I/R 4) and I/RL groups. The following parameters were measured in the experiments: (1) diamin oxidase activity (DAO), D-lactate and D-xylose levels in blood using spectrophotometry; (2) transit function of small intestine; (3) pathological examination of small intestine by light microscope. RESULTS: The results showed that plasma DAO activity was increased in I/R 1, I/R 4 and I/RL (all P<0.05), and small intestinal tissue DAO was decreased in I/R 2 and I/RL (both P<0.05). Negative correlations were found between plasma and intestinal DAO (r=-0.909, P<0.001). Plasma D-lactate was elevated significantly in I/R 1, I/R 2, and I/RL (all P<0.05). D-xylose content was increased at I/R1 and I/RL groups (both P<0.05), and it was significantly higher than controls at 3 hours. Similarly, a positive correlation was found between plasma DAO activity and plasma D-lactate level (r=0.559, P<0.05). CONCLUSION: The intestinal barrier function, absorption function, permeability, and transit are impaired after gut ischemia/reperfusion combined with endotoxin challenge.

[Effects of carbachol injection in intestine on plasma levels of inflammatory medium in rats during gut ischemia/reperfusion].

OBJECTIVE: To investigate the effects of carbachol injection in intestine on plasma levels of tumor necrosis factor-alpha(TNF-alpha), interleukin-10 (IL-10) and cortisol in rats during gut ischemia/reperfusion. METHODS: Wistar rats were anaesthetized with soluble pentobarbitone, and subjected to superior mesenteric artery occlusion (SMAO) for 60 minutes, followed by reperfusion for 60 minutes. Animals were divided into three groups, pretreated group (carbachol injection in intestine at 30 minutes after SMAO; 0.1 mg/kg), treated group (carbachol injection at 30 minutes from onset of reperfusion), and controls (saline injection). Plasma TNF-alpha, IL-10 and cortisol levels were determined at 1.0, 2.5 and 6.0 hours after SMAO. RESULTS: The plasma levels of TNF-alpha significantly decreased in pretreated and treated groups than those in controls after carbachol injection (both P<0.01). However, the levels of IL-10 and cortisol didn't show significant differences among three groups. CONCLUSION: The RESULTS suggest that carbachol can reduce the proinflammatory cytokine release and have a less inhibitory effect on the anti-inflammatory cytokine. It is indicated that carbachol play a potential role in alleviating systemic inflammatory response during splanchnic ischemia/reperfusion injury.

[Carbachol alleviates inflammation in gut tissue during ischemia/reperfusion in rats].

OBJECTIVE: To investigate the effects of carbachol on local inflammation in gut tissue during ischemia/reperfusion (I/R). METHODS: A jejunal sac was formed in Wistar rats. The superior mesenteric artery was occluded (SMAO) for 60 minutes followed by reperfusion for another 60 minutes. Animals were divided into three groups, pretreatment group (carbachol was injected into the jejunal sac 30 minutes after SMAO, 0.1 mg/kg), treatment group (carbachol was injected in same dosage into the jejunal sac 30 minutes after reperfusion), and controls (saline injection). The contents of tumor necrosis factor-alpha(TNF-alpha) and activity of myeloperoxidase (MPO) in gut tissue were determined at 1 hours, 2.5 hours and 6 hours after SMAO. RESULTS: The contents of TNF-alpha and activity of MPO were significantly decreased in pretreatment and treatment groups compared with control group at 2.5 hours after SMAO (both P<0.05). There were no differences in both contents between pretreatment group and treatment group at any specified time. It was also found that there were less inflammatory pathological changes in the gut tissues in the two treated groups than that of control. CONCLUSION: The RESULTS suggest that carbachol could alleviate gut inflammatory response during gut ischemia/reperfusion injury by inhibiting proinflammatory cytokine release.

[Effects of carbachol on plasma levels of tumor necrosis factor-alpha and interleukin-10 in rats during gut ischemia-reperfusion].

OBJECTIVE: To investigate the effects of carbachol on the levels of tumor necrosis factor-alpha (TNF-alpha), interleukin-10 (IL-10) and cortisol in plasma of rats during gut ischemia-reperfusion. METHODS: Wistar rats were anaesthetized with soluble pentobarbitone, and subjected to superior mesenteric artery occlusion (SMAO) for 60 minutes, followed by reperfusion for 60 minutes. Animals were divided into three groups, pretreated group (intramuscular injection carbachol at 30 minutes after SMAO, 0.1 mg/kg), treated group (intramuscular injection of carbachol at 30 minutes after reperfusion), and control group (saline injected). The levels of TNF-alpha, IL-10 and cortisol in plasma were determined at 0 hour, 1 hour, 2.5 hours and 6 hours after SMAO. RESULTS: The levels of TNF-alpha, IL-10 and cortisol significantly increased after SMAO (P<0.01 ). The levels of TNF-alpha significantly decreased in pretreated and treated groups than that in control after the intramuscular injection of carbachol (all P<0.01). However, the levels of IL-10 and cortisol did not show significant differences among three groups. It was also found that lower content of TNF-alpha in pretreated group than that in treated group, especially at 1 hour and 6 hours. CONCLUSION: The results suggest that carbachol reduce the proinflammatory cytokine releasing and has a less inhibiting effect on the anti-inflammatory cytokine. It is indicated that carbachol play a potential role in alleviating systemic inflammatory response during splanchnic ischemia-reperfusion injury.

[A small dose of intraperitoneal injection of zymosan induces systemic inflammatory response and multiple organ dysfunction following gut ischemia-reperfusion injury].

OBJECTIVE: To investigate the effects of a small dose of intraperitoneal injection of zymosan following gut ischemia-reperfusion injury on systemic inflammatory response and distant organ function. METHODS: Wistar rats were randomly divided into three groups: gut ischemia-reperfusion injury (I-R) alone, intraperitoneal injection of zymosan (Z) alone, and gut ischemia-reperfusion followed by intraperitoneal injection of zymosan (M). Gut (I-R) was produced by occluding superior mesenteric artery for 60 minutes followed by gut reperfusion. A small dose(125 mg/kg) of zymosan was given intraperitoneally at 12 hours after recovery of gut blood flow. RESULTS: Systemic inflammatory responses were found in all rats of three groups. The plasma level of tumor necrosis factor-alpha and activities of myeloperoxidase in lungs and intestines were significantly higher in animals in M group compared with those in I-R and Z groups. The incidence of multiple organ dysfunction syndrome (MODS) and mortality rate at 72 hours postinjury in two-hits group were significantly higher than those in I-R and Z group. CONCLUSION: A small dose of intraperitoneal injection of zymosan could induce systemic inflammatory response and multiple organ dysfunction more readily when there is a precedent gut ischemia-reperfusion injury.

[Effects of efferent vagus nerve excitation on inflammatory response in heart tissue in rats with endotoxemia].

OBJECTIVE: To study the effects of electrical stimulation of efferent vagus nerve on the inflammatory response in heart tissue in rats with endotoxemia. METHODS: Two hundred and ten Wistar rats were randomly divided into seven groups. Animals were subjected to bilateral cervical vagotomy, or a comparable sham surgical procedure in which the vagus nerves were isolated but not transected. The distal end of a vagus nerve trunk was placed across bipolar electrodes connected to a stimulation module and controlled by an acquisition system. Stimuli with constant voltage (5 V, 2 ms, 1 Hz) were applied to the nerve for 20 minutes immediately after administration of lipopolysaccharide (LPS, 10 mg/kg, E coli O111: B4, Sigma), and then were repeated 2 times after each of 10 minutes interval. Blood and tissue samples of these rats were collected at 1, 1.5 and 2 hours after LPS administration in all groups. Tumor necrosis factor-alpha (TNF-alpha) and myeloperoxidase (MPO) in heart tissue and serum MB isoenzyme of creatine kinase(CK-MB) were determined. RESULTS: The electrical stimulation of the efferent vagus nerve significantly decreased the contents of TNF-alpha and MPO in heart tissue and CK-MB in serum, and alleviated myocardial inflammation in heart tissue at all time points, especially at 1.5 hours after endotoxin challenge. CONCLUSION: The results suggested that excitation of the efferent vagus nerve can significantly alleviate the inflammatory response in the heart tissue, thus it might produce a potential protective effect on the heart during endotoxemia in rats.

[Effects of different enteral nutrients on gut absorptive capacity and energy metabolism during gut ischemia/reperfusion].

OBJECTIVE: To evaluate the effects of different enteral nutrients on intestinal absorptive capacity and ATP content of intestinal mucosa after ischemia-reperfusion (I/R) of the intestine. METHODS: A segment of jejunum was isolated to form a pouch in Sprague-Dawley rats. The jejunal pouches of animals were filled with either a mixture of nutrients (5 mmol/L alanine + 5 mmol/L glucose), glucose alone (10 mmol/L), alanine alone (10 mmol/L) or mannitol alone (10 mmol/L) as a nonabsorbable osmotic control. The superior mesenteric artery was then occluded for 60 minutes, followed by reperfusion for 60 minutes. Gut absorptive capacity, as measured by the changes in short circuit current (DeltaIsc), and mucosal ATP content were determined both at the end of 60 minutes ischemia and 60 minutes of reperfusion. RESULTS: DeltaIsc and ATP levels were decreased after I/R. Intraluminal alanine alone or alanine/glucose mixture further reduced DeltaIsc and ATP content. On the other hand, intraluminal glucose significantly increased DeltaIsc and ATP levels compared with intraluminal alanine, alanine/glucose mixture or I/R alone. CONCLUSION: Intraluminal alanine increases the absorptive capacity and energy metabolism of the gut caused by I/R, and indicated that intraluminal glucose improves gut absorptive capacity and energy metabolism and provides a protective effect on gut from ischemia and reperfusion injury.