Capture Deformation Twinning in Mg during Shock Compression with Ultrafast Synchrotron X-Ray Diffraction

Deformation twinning plays a vital role in accommodating plastic deformation of hexagonal-close-packed (hcp) metals, but its mechanisms are still unsettled under high strain rate shock compression. Here we investigate deformation twinning in shock-compressed Mg as a typical hcp metal with in situ, ultrafast synchrotron x-ray diffraction. Extension twinning occurs upon shock compression along ⟨112[over ¯]0⟩ and ⟨101[over ¯]0⟩, but only upon release for loading along ⟨0001⟩. Such deformation mechanisms are a result of the polarity of deformation twinning, which depends on directionality and relative magnitude of resolved shear stress and may be common for Mg and its alloys in a wide range of strain rates.

[Analysis on treatment of eight extremely severe burn patients in August 2nd Kunshan factory aluminum dust explosion accident]

Objective: To summarize the measures and experience of treatment in mass extremely severe burn patients. Methods: The clinical data and treatment of 8 extremely severe burn patients in August 2 Kunshan factory aluminum dust explosion accident who were admitted in the 100th Hospital of PLA on August 2nd, 2014, were retrospectively analyzed. There were 4 males and 4 females, aging 22-45 (34±7) years, with total burn area of 55%-98% [(89±15)%] total body surface area (TBSA) and full-thickness burn area of 45%-97% [(80±21)%] TBSA. All the 8 patients were accompanied with severe shock, inhalation injury, and blast injury. According to the requirements of former PLA General Logistics Department and Nanjing Military Command, a treatment team was set up including a special medical unit and a special care unit, with Chai Jiake from the First Affiliated Hospital of PLA General Hospital as the team leader, Zheng Qingyi from the 175th Hospital of PLA (the Affiliated Dongnan Hospital of Xiamen University) as the deputy leader, the 100th Hospital of PLA as the treatment base, and burn care, respiratory, nephrology, nursing specialists from the First Affiliated Hospital of PLA General Hospital, and the burn care experts and nursing staff from the 180th Hospital of PLA, 118th Hospital of PLA, 98th Hospital of PLA, and 175th Hospital of PLA, and nurses from the 85th Hospital of PLA, 455th Hospital of PLA, 101th Hospital of PLA, 113th Hospital of PLA as team members. Treatment strategies were adopted as unified coordination by the superior, unified responsibility of team leader, division of labor and cooperation between team members, and multidisciplinary cooperation led by department of burns. With exception of one patient who received deep vein catheterization before admission, the other 7 patients were treated with deep vein catheterization 0.5 to 3.0 hours after admission to correct hypovolemic shock as soon as possible. Eight patients received tracheotomy, and 7 patients were treated with mechanical ventilation by ventilator in protective ventilation strategy with low tide volume and low volume pressure to assist breathing. Fiberoptic bronchoscopy was done one to three times for all the 8 patients to confirm airway injuries and healing status. Escharectomy and Meek dermatoplasty in the extremities of all the 8 patients were performed 3 to 6 days after injury for the first time. Escharectomy, microskin grafting, and covering of large pieces of allogeneic skin on the trunks of 4 patients were performed 11 to 16 days after injury for the second time. The broad-spectrum antibiotics were uniformly used at first time of anti-infective therapy, and then the antibiotics species were adjusted in time. The balance of internal environment was maintained and the visceral functions were protected. One special care unit was on responsibility of only one patient. Psychological intervention was performed on admission. The rehabilitative treatment was started at early stage and in company with the whole treatment. Results: Acute renal injury occurred in 5 patients within 36 hours after injury and their renal function was restored to normal 4 days after injury due to active adjustment of fluid resuscitation program. No pulmonary complications, such as severe pulmonary infection and ventilator-associated pneumonia, occurred in the survived patients. One of the 8 patients died, and the other 7 patients were cured successfully. The wounds were basically healed in 2 patients in 26 or 27 days by 2 or 3 times of operation, and in 5 patients by 4 or 5 times of operation. The basic wound healing time was 26-64 (48±15) days for all the 7 patients. Conclusions: Treatment strategies of unified coordination by the superior, unified responsibility of team leader, division of labor and cooperation between team members, and multidisciplinary cooperation led by department of burns are the bases to successful treatment. Correcting shock as soon as possible is the prerequisite and closing wound as soon as possible is the key to successful treatment. Comprehensive treatment measures, such as maintaining and regulating the function of viscera, improving the body immunity, and preventing and treating the complications, are the important components to successful treatment. It is emphasized that in the treatment of mass extremely severe burn patients, specialist burn treatment should always be in the dominant position, and other related disciplines may play a part in auxiliary function.

RapidArc vs intensity-modulated radiation therapy for hepatocellular carcinoma: a comparative planning study

OBJECTIVE

The purpose of this study is to compare the dose-volumetric results of RapidArc (RA Varian Medical Systems, Palo Alto, CA) with those of intensity-modulated radiation therapy (IMRT) for hepatocellular carcinoma.

METHODS

20 patients previously treated for hepatocellular carcinoma were the subjects of this planning study. 10 patients were treated for portal vein tumour thrombosis (Group A), and 10 patients for primary liver tumour (Group B). Prescription dose to the planning target volume was 54 Gy in 30 fractions, and the planning goal was to deliver more than 95% of prescribed dose to at least 95% of planning target volume.

RESULTS

In Group A, mean doses to liver were increased with RA vs IMRT (22.9 Gy vs 22.2 Gy, p=0.0275). However, V(30 Gy) of liver was lower in RA vs IMRT (31.1% vs 32.1%, p=0.0283). In Group B, in contrast, neither mean doses nor V(30 Gy) of liver significantly differed between the two plans. V(35 Gy) of duodenum and V(20 Gy) of kidney were decreased with RA in Groups A and B, respectively (p=0.0058 and 0.0124, respectively). Both maximal doses to spinal cord and monitor unit were significantly lower in the RA plan, regardless of the group.

CONCLUSION

The dose-volumetric results of RA vs IMRT were different according to the different target location within the liver. In general, RA tended to be more effective in the sparing of non-liver organs at risk such as duodenum, kidney, and/or spinal cord. Moreover, RA was more efficient in the treatment delivery than IMRT in terms of total monitor unit used.

Micromixing in fermentors: metabolic changes in Saccharomyces cerevisiae and their relationship to fluid turbulence

Even when microorganisms are grown in highly agitated fermentors, calculation predicts a mismatch between the microscale of the turbulence (where the smallest eddy is typically 50-300 microm diameter) and the cellular dimensions (1-5 microm). The cell thus spends substantial portions of time in an apparently stagnant eddy, depleted of nutrients. The local fluid microscales were measured in a laboratory fermenter to confirm this. Using S. cerevisiae in continuous culture, it is shown that the local microscales influence cell metabolism dramatically. The issues addressed in this study are thus micromixing and microsegregation of reactants and how they influence cell yield.

Reducing loss in lateral charged-particle equilibrium due to air cavities present in x-ray irradiated media by using longitudinal magnetic fields

The underdosing of lesions distal to air cavities, such as those found in upper respiratory passages, occurs due to the loss in lateral charged-particle equilibrium (CPE). The degree of underdosing worsens for smaller field sizes, resulting in more frequent recurrence of the cancer treated. Higher photon energies further aggravate the outcome by producing longer second build-up regions beyond the cavity. Besides underdosing, the larger lateral spread of secondary electron fluence in the air cavity produces diffuse dose distributions at the tissue-air interface for shaped or intensity modulated fields. These disequilibrium effects create undesirable deviations from the intended treatment. The clinical concern is further intensified by the failure of traditional treatment planning systems to even account for such defects. In this work, the use of longitudinal magnetic fields on the order of 0.5 T is proposed for alleviating lateral electronic disequilibrium due to the presence of air cavities in the irradiated volume. The magnetic field enforces lateral CPE by restricting the lateral range of electrons in the air cavity. The problem is studied in a simple water-air-water slab geometry using EGS4 Monte Carlo simulations for 6 MV photons. Electronic disequilibrium is evaluated for beams of various sizes, shapes and intensity distributions constructed by linear superposition of the dose distributions for 0.5 x 0.5 cm2 beamlets. Comparison is also made with 60Co irradiation. The results indicate that the lateral confinement of secondary electrons in the air cavity by sub-MRI strength longitudinal fields is effective in reducing deterioration of dose distributions near tissue-air interfaces. This can potentially reduce recurrence rates of cancers such as the larynx carcinoma.

Dosimetric perturbations of linear array of beta-emitter seeds and metallic stent in intravascular brachytherapy

The radiation treatment with catheter-based beta-emitter sources is under clinical trials to prevent restenosis following interventional coronary procedures. There are still large uncertainties in the dose calculation due to the complicated treatment geometry. We present the Monte Carlo simulations to account for the dosimetric perturbations due to neighboring trained seeds, proximal/distal gold markers, and a stainless steel stent. A catheter-based beta-emitter system is modeled using the Monte Carlo code, MCNP4B. Dose distributions and dose rates are calculated in voxels (0.64x0.64x0.5 mm3) around the long cylindrical trains of 90Sr/Y source with and without the stent (at 1.92 mm from the source axis). For the total activity of 70 mCi (2.59x10(9) Bq), the dose around most of the source length (except for edge seeds and gold markers) varies from 40 to 0.23 cGy/s as the radial distance from the source axis (r) increases from 0.64 to 6.4 mm. At the prescription range of r = 1.5-4.0 mm, the dose gradient is very steep and the contribution of neighboring seeds to the dose is significant. The dose enhancement due to neighboring seeds (the so-called "train effect") varies from 9% to 64% as r increases from 0.64 to 5.2 mm. The doses at r = 2 mm from the last edge seed and the gold marker are about 80% and 40% of that of the nonedge seed (8.7 cGy/s), respectively. The dose enhancement due to the secondary electrons and the primary electrons scattered with the stent is shown to be about 9.3% in the voxel including the stent. However, as r increases beyond the stent (r = 2.0-6.4 mm), the dose is slightly reduced by 4%-12%, compared to that without the stent.

Boron self-shielding effects on dose delivery of neutron capture therapy using epithermal beam and boronophenylalanine

Previous dosimetry studies for boron neutron capture therapy have often neglected the thermal neutron self-shielding effects caused by the 10B accumulation in the brain and the tumor. The neglect of thermal neutron flux depression, therefore, results in an overestimation of the actual dose delivery. The relevant errors are expected to be more pronounced when boronophenylalanine is used in conjunction with an epithermal neutron beam. In this paper, the boron self-shielding effects are calculated in terms of the thermal neutron flux depression across the brain and the dose delivered to the tumors. The degree of boron self-shielding is indicated by the difference between the thermal neutron fluxes calculated with and without considering a 10B concentration as part of the head phantom composition. The boron self-shielding effect is found to increase with increasing 10B concentrations and penetration depths from the skin. The calculated differences for 10B concentrations of 7.5-30 ppm are 2.3%-8.3% at 2.3 cm depth (depth of the maximum brain dose) and 4.6%-17% at 7.3 cm depth (the center of the brain). The additional self-shielding effects by the 10B concentration in a bulky tumor are investigated for a 3-cm-diam spherical tumor located either near the surface (3.3 cm depth) or at the center of the brain (7.3 cm depth) along the beam centerline. For 45 ppm of 10B in the tumor and 15 ppm of 10B in the brain, the dose delivered to the tumors is approximately 10% lower at 3.3 cm depth and 20% lower at the center of the brain, compared to the dose neglecting the boron self-shielding in transport calculations.

Monte Carlo based protocol for cell survival and tumour control probability in BNCT

A mathematical model to calculate the theoretical cell survival probability (nominally, the cell survival fraction) is developed to evaluate preclinical treatment conditions for boron neutron capture therapy (BNCT). A treatment condition is characterized by the neutron beam spectra, single or bilateral exposure, and the choice of boron carrier drug (boronophenylalanine (BPA) or boron sulfhydryl hydride (BSH)). The cell survival probability defined from Poisson statistics is expressed with the cell-killing yield, the 10B(n,alpha)7Li reaction density, and the tolerable neutron fluence. The radiation transport calculation from the neutron source to tumours is carried out using Monte Carlo methods: (i) reactor-based BNCT facility modelling to yield the neutron beam library at an irradiation port; (ii) dosimetry to limit the neutron fluence below a tolerance dose (10.5 Gy-Eq); (iii) calculation of the 10B(n,alpha)7Li reaction density in tumours. A shallow surface tumour could be effectively treated by single exposure producing an average cell survival probability of 10(-3)-10(-5) for probable ranges of the cell-killing yield for the two drugs, while a deep tumour will require bilateral exposure to achieve comparable cell kills at depth. With very pure epithermal beams eliminating thermal, low epithermal and fast neutrons, the cell survival can be decreased by factors of 2-10 compared with the unmodified neutron spectrum. A dominant effect of cell-killing yield on tumour cell survival demonstrates the importance of choice of boron carrier drug. However, these calculations do not indicate an unambiguous preference for one drug, due to the large overlap of tumour cell survival in the probable ranges of the cell-killing yield for the two drugs. The cell survival value averaged over a bulky tumour volume is used to predict the overall BNCT therapeutic efficacy, using a simple model of tumour control probability (TCP).

Morphometry of rat germ cells during spermatogenesis

BACKGROUND

There has never been a study of the components of germ cells as they progress through spermatogenesis.

METHODS

The structural changes taking place in rat germ cells, from spermatogonia to late spermatids, were studied utilizing morphometric techniques conducted largely at the ultrastructural level.

RESULTS

Volume and surface area parameters for virtually all cellular and subcellular features were obtained for nine periods during the spermatogenic cycle. Virtually all germ cell components show dynamic properties associated with specific phases of their development.

CONCLUSIONS

The data provided can be used in an objective way to characterize structural changes taking place during spermatogenesis and to relate those structural changes to functional properties of germ cells.

Surface and surface-to-volume relationships of the Sertoli cell during the cycle of the seminiferous epithelium in the rat

The surface relationships of the Sertoli cell and the surface relationships of the Sertoli cell in comparison to the changing volumes of developing germ cells were studied using morphometric techniques at periods representing nine groupings of the fourteen defined periods in the cycle of the seminiferous epithelium of the adult rat. No cyclic variation in the total Sertoli plasma membrane surface area was noted. Cyclic variations were noted in the area of the Sertoli cell surface that faces the basal compartment germ cells, but not the basal lamina. No cyclic variations were noted in the amount of contact of the Sertoli cells with each other at the level of the Sertoli cell barrier. However, when areas in the adluminal compartment were studied, significantly less Sertoli-Sertoli contact was seen in stages V through VII than in other stages with the exception of stages II-IV. Surface contact of germ cells with Sertoli cells increased progressively as germ cells entered the intermediate compartment and progressed to late spermatids. However, a calculation of the surface-to-volume ratio showed that surface increases of the Sertoli cell in relation to the volume of germ cells were greatest in elongating spermatids past step 12 of spermiogenesis. The area in which Sertoli ectoplasmic specializations faced germ cells was determined throughout spermatogenesis, and these data demonstrated that the first appearance of ectoplasmic specialization was at the mid-pachytene phase. They also showed that stage VIII was a period when ectoplasmic specialization loss from the cell surface was evident. Less Sertoli ectoplasmic specialization face step 8 and step 19 spermatids than comparable germ cell types at other stages. In addition to Sertoli cell surface area changes during the cycle, volumes of individual germ cell types were determined for the first time. The data presented allow an objective understanding of the complex structure and relationships of the Sertoli cell and provide a basis for understanding functional changes and interpreting biochemical data.

Sertoli cell cycle: a re-examination of the structural changes during the cycle of the seminiferous epithelium of the rat

Seminiferous tubules in mammals are composed of cell associations that show a cyclic pattern of renewal and development. The cyclic nature of germ cell development suggests that the cells supporting the spermatogenic process, the Sertoli cells, might also differ structurally during the spermatogenic cycle in terms of the quantity of their constituents. In the present study, cyclic differences in volumes, and surface areas were determined using a sampling technique at the electron microscope level that proportionally samples the Sertoli cell within the seminiferous tubule. Among the many parameters studied, only the surface area of the cell, the volume of lipid, and the volume and surface area of the rough endoplasm reticulum were shown by statistical analysis to vary cyclically. Regarding rough endoplasm reticulum, the volume and surface area of this organelle peaked at mid-cycle and its low was recorded near the end of the cycle, exhibiting an approximate 15-fold difference between extremes. The rough endoplasm reticulum parameters generally correlated with known patterns of protein secretion within the tubule and with the secretion of specific proteins as well as the factors important in controlling protein secretion. Many Sertoli cell structural parameters suggested to be influenced cyclically in the rat in other studies could not be confirmed by the present study. Methodological differences in the present study and past studies are discussed as potential sources of error for these discrepancies.

[Effect of Rheum tanguticum Maxim ex Balf on cAMP in the central nervous system]

Rabbit model of fever was produced by means of subcutaneous inoculation of pneumocci. Third ventricular intubation and irrigation were carried out in rabbits. Irrigation fluid was collected during the stage of normal temperature, at the peak of fever and when the temperature was lowered by rhubarb. cAMP was detected with RlA in each of the three portions of the irrigated CSF. The result showed that cAMP level was raised during fever and decreased after rhubarb administration. Irrigation of CSF without medication had no significant influence on cAMP level.

Subcellular site of antispermatogenic effect of gossypol and its possible molecular mechanism of action

This paper reports the results of gossypol effects on the testicular mitochondrial ultrastructures and functions. A hypothesis of mechanism of gossypol action based on our experimental data was postulated. Electron microscopic observations confirmed further our previous studies that the mitochondria of the target germ cells were the most sensitive and the most severely damaged among cellular organelles in response to gossypol. The damages included the swelling, vacuolation, crista depletion, lysis, granular accumulation in matrix and the process of intact mitochondria disintegration. The activity of the mitochondrial marker enzyme, the LDH-X of human spermatozoa, was markedly decreased or suppressed completely after gossypol treatment. The functions of isolated testicular mitochondria determined by Warburg manometric and oxygen electrode polarographic methods indicated that gossypol stimulated respiration but inhibited slightly the oxidative phosphorylation at low concentrations (20-40 microM) in vitro. With the increase in concentration of gossypol, the mitochondrial respiration and phosphorylation decreased obviously, they were completely inhibited at a concentration of 80 microM for oxidative phosphorylation and at about 300 microM for respiration. The degree of uncoupling of phosphorylation appears to be dose-dependent. Similar results were obtained for the testicular mitochondria isolated from rats that had been administered per os gossypol previously (6 mg, 10 mg and 15 mg/day X 21 respectively), in which the P/0 ratio decreased significantly (P less than 0.001) as compared with that of the control group. The distribution of 14C-gossypol in mitochondrial was found to be 2-3 times higher than that in other subcellular fractions. Similar pattern of distribution was shown in double labeling experiments with 14C-gossypol and 3H-ouabain.